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Welcome toyour Digital Edition ofAerospace & Defense

TechnologyFebruary 2014

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Electronics Take Charge of Aircraft Engine Controls

Optically Transparent EMI Shielding for Defense and

Aerospace Applications

Pumped Two-Phase Coolingfor Thermal Management of High Heat Flux Electronics

Supplement to NASA Tech Briefs

February 2014

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www.aerodefensetech.com

Electronics Take Charge of Aircraft Engine Controls

Optically Transparent EMI Shielding for Defense and


Pumped Two-Phase Coolingfor Thermal Management of High Heat Flux Electronics

Supplement to NASA Tech Briefs

February 2014

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Precision Metal Stamping (High and Low Volume)

Welded and Mechanical Assemblies

Complex CNC Machining

Rapid Prototyping

Close Tolerance Grinding

Tooling, Fixtures and Gages

Laser Cutting and Welding

Wire EDM


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Aerospace & Defense Technology

ContentsFEATURES ________________________________________

6 Avionics/Electronics6 Electronics Take Charge

12 Aerospace Materials/Manufacturing12 Optically Transparent EMI Shielding for Defense and


16 Thermal Management16 Pumped Two-Phase Cooling for Thermal Management of High

Heat Flux Electronics

20 Testing & Simulation20 Thermal Simulation and Testing of Expanded Metal Foils for

Lightning Protection

24 RF & Microwave Technology24 Software Defined Radio Enables Flexible Communications for

NASA28 Automated Testing of Advanced, High-Performance, Point-to-

Multipoint Radio Systems

34 Tech Briefs34 Power Management for the Electric Taxiing System

Incorporating the More Electric Architecture36 Simultaneous Vibration Suppression and Energy Harvesting

38 Cascading Failures in Coupled Distributed Power Grids andCommunication Networks

39 Implementing Interconnected Generation in Future CivilAircraft

DEPARTMENTS ___________________________________

4 What’s Online30 Technology Update41 Application Briefs44 New Products48 Advertisers Index

ON THE COVER ___________________________________

A Lockheed Martin F-35B prepares to land on thedeck of an aircraft carrier. During short take-off andvertical landing (STOVL) operation, the F-35B’sengine control software uses advanced methods tode-couple a highly coupled engine system com-prised of the main engine and a lift fan with a drive-shaft attached in between. The result is wings-level,rock-solid hover and vertical landing performance.To learn more, read the feature article on page 6.

Photo courtesy of Lockheed Martin

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4 www.aerodefensetech.com Aerospace & Defense Technology, February 2014

What’s Online

Top productsShielded twisted pair cables

W. L. Gore & Associates’ Shielded Twisted Pair Cables re-duce weight while maintaining reliable signal integrity. Thecables meet ANSI/NEMA WC27500 standards for aerospaceand industrialelectrical cable,type 24, and theymaintain high-speed com muni -cation betweenavionics trans-mitters and re-ceivers. They aremade from fluoro -poly mers that re-duce cable jacketweight by as much as 37% when compared to ETFE materials,and 50% when compared to FEP. The materials also result insmaller cable diameters, which translate to significantlysmaller, lighter, and higher-density cable bundles. More detailat http://articles.sae.org/12625.

Atomic force microscopy imagingAsylum Research’s blueDrive photothermal excitation is

available on its Cypher atomic force microscopes. blueDrivemakes tapping mode imaging simple, stable, and accurate. Itreplaces the conventional piezoacoustic excitation mecha-nism, instead using a blue laser to directly excite the AFMcantilever photothermally. This results in an ideal cantileverdrive response in both air and liquids, which provides signifi-cant performance and ease-of-use benefits for tapping modeimaging. More detail at http://articles.sae.org/12626.

Two-component electrically conductive epoxyMade with silver-coated nickel filler, Master Bond EP79FL is

a two-part, electrically conductive epoxy for bonding, sealing,and coating applications. It has a low-volume resistivity ofless than 0.005 ohm-cm and is suitable for applications in theelectronic, aerospace, computer, semiconductor, and electro-optic industries. In addition to its electrical properties, thesystem is flexible upon curing, enabling its use in applica-tions involving thermal cycling, and thermal and mechanicalshocks. More detail at http://articles.sae.org/12627.

Custom dial face designsPalmer Wahl Instrumentation Group's custom dial

faces—its BiMetal and Direct Drive Dial thermometers, aswell as its pressure gauges with screw-on bezels—may becustomized, no matter the dial size. Customers may submittheir own ideas and artwork, or they may work with thefirm’s in-house engineering services to design a model spe-cific to their application and needs. Options for customiz-ing include dual scales with different units of measure, col-ored scales, high-visibility markings, color pie-wedgesectors, bands, or lines. More detail at http://articles.sae.org/12628.

Top articles Hybrid copter is first of its kind

Regulatory authorities in Germany decided to develop anew aircraft category called volocopter to accommodate thenew 18-motor VC200. Read more at http://articles.sae.org/12585.

Canadian researchers employ recycled carbon-fiber matsto produce thermoset composites

Carbon-fiber-reinforced thermoset composites continue tobe difficult to recycle, as they are a complex mixture of dif-ferent materials such as thermosetting polymers, carbonfibers, and fillers. Researchers from the Universite Du Quebecat Montreal, Bell Helicopter Textron Canada, and the Na-tional Research Council Canada investigated using carded re-cycled carbon-fiber mats and epoxy resin to fabricate ther-moset composite plates. Read more at http://articles.sae.org/12559.

Overcoming design challenges of next-generation UASsNext-generation unmanned air systems will require more

performance and must integrate increasing capabilities forguidance control, weaponry, and surveillance—all in a verylimited space. Read more at http://articles.sae.org/12546.

Heated air technology helps optimize CFRP assemblyAssembly of large and complex carbon-fiber-reinforced

plastic (CFRP) components requires the use of liquid resin-based materials for applications such as shimming and aero-dynamic sealing. These materials generally require curingtimes up to 12 h; heated air technology can reduce that timeto 2 h. Read more at http://articles.sae.org/12510.

A holistic approach to aircraft assemblyIt is the "automation and tooling partner" who offers a per-

formance-based and advanced manufacturing systems inte-gration approach that offers the next step-change, say Bom-bardier Aerospace and AIP Aerospace Odyssey. Read more athttp://articles.sae.org/12568.

The range-extender version of the volocopter will have a propellerbehind the cockpit. Shown is the all-electric version.

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Electronic controls are slowlytransforming aircraft engines ofall types, bringing improvedfuel consumption, improved ef-

ficiency, and more power. As the func-tionality of control units for jet enginesincreases, digital management is alsoadding more capabilities for helicoptersand small piston engines.

Full authority digital engine controls(FADEC) continue to leverage the ad-vances in semiconductors and softwareto improve engine management. As mi-crocontroller capabilities soar, enginecontrollers can handle functions be-yond the engines themselves. For ex-ample, the Lockheed Martin F-35B’s en-gine controller also manages the shorttakeoff/vertical landing system.

“Engine controls can be linked toother electronic systems on the aircraftwhen the engine control is expected tobe the flight control,” said Louis Celib-erti, Director of Control & DiagnosticSystems at Pratt & Whitney Engineer-ing. “During STOVL operation, the F135engine control is the heart of the inte-grated flight and propulsion control.The engine control software uses ad-vanced methods to de-couple a highlycoupled engine system comprised ofthe main engine and a lift fan with a

driveshaft attached in between. The re-sult is wings-level, rock-solid hover andvertical landing performance.”

While the F135 represents the highend for engine controls, digital systemsare also expanding their reach into thelow end. Rockwell Collins is shipping

what it says is the first dual-channel en-gine control unit for use in light sportaircraft. The controls for the Rotax 912iS piston engine were developed in con-junction with the BRP-Powertrain affili-ate of Bombardier Recreational Products.The ECU automates tasks like adjusting

Electronics Take ChargeDigital controls are handling more engine control tasks on a wider range of aircraft.

by Terry Costlow, Contributing Editor

Pratt & Whitney is linking engine controls to other systems to let the F-35B hover.

Helicopter performance is enhanced by Rolls Royce controllers.

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Avionics/Electronics

air/fuel mixture and controlling exhaustgas temperatures.

“Now operators can operate the en-gine with ease, without having to worryabout completing manual tasks to opti-mize performance throughout all oper-ating conditions,” said David Vos, Sen-ior Director, Control Technologies, forRockwell Collins.

Design teams are also doing morewith ECUs in helicopters. Rolls-Roycerecently deployed a dual-channelFADEC system on the M250-C47E, thefirst new helicopter to be launched bythe company since 2005. The advancedFADEC helps improve the fuel burn andcut engine operating costs.

Complex DesignsWhether FADECs are employed on

the simplest recreational plane or themost advanced jets, design teams facemyriad challenges. Hardware and soft-ware must operate efficiently without dSpace tools make it easier for test engineers to comply with DO-178B regulations.

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Aerospace & Defense Technology, February 2014 9Free Info at http://info.hotims.com/49742-803


Green Taxiing MachinesThe push to trim fuel consumption and emissions may

prompt aircraft manufacturers to adopt some of the elec-tric motor technologies used in hybrid cars and trucks.Honeywell Aerospace and Safran have teamed up to de-sign a system that uses an auxiliary power unit (APU) topower planes during taxi operations.

The Electric Green Taxiing System demonstrated by Air-bus in Paris, uses a small APU to power electric motors inthe main landing gear so an aircraft can push back and taxiwithout engaging its main engines. In short-haul opera-tions, this can trim fuel consumption an average of 4%.

Honeywell APUs already provide power for ventilation,lighting, and starting engines for many aircraft. In a system setfor production in 2016, the APU will drive electric motorsplaced on the two mainwheel units. One wheelon each main gear em-ploys an electric motor,reduction gearbox, andclutch assembly to drivethe aircraft.

Dedicated power elec - tronics and system con-trollers let pilots controlan aircraft’s speed anddirection. During development, the design team ran severaltests before many of the components were ready.

“When you’re modifying the landing gear that much,you need to do a lot with the control circuitry,” said Ma-hendra Muli, New Business Development Director atdSpace. “Honeywell did a lot of modeling and simulationwith hardware-in-the-loop, using our system onboard tocontrol the drive motors.”

Currently, the wheel assemblies add around 300 poundseach. Honeywell and Safran say that this weight can bereduced significantly over time. Some of these gains maycome by leveraging the myriad efforts by semiconductorsuppliers to help automakers develop electrified power-trains. Many semiconductor suppliers are adding hard-ware that makes it easier to drive the high-powered mo-tors needed to move vehicles.

“We added 12 models to our Hercules microcontrollerline, adding PWM for motor control,” said Dave Maples,Safety MCU Product Line Manager at Texas Instruments.“That will help people move to brushless motors.”

Brushless motors, which are quieter and use less powerthan direct current motors, are moving to less expensivetechnologies. NXP Semiconductors is focusing its designefforts on aniso tropic magnetroresistive sensors, whichlet motor manufacturers use any type of magnet, not justrare earth materials now used in many brushless motors.

Honeywell and Safran have developed asystem that lets planes taxi without turningon their main engines.

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glitches or failures, forcing engineers towork overtime to eliminate mistakes.

Software is a primary focus. Many air-craft routinely run several million linesof code. Increasingly, this software is gen-erated by computer, not programmers.

“As controls get more complex, codegeneration tools are gaining attention,”said Mahendra Muli, New Business De-velopment Director at dSpace. “Ad-vanced automatic code generation toolsare being used to convert algorithmmodels into well-documented C-codeused in production controllers with ef-ficiency, repeatability, and high quality,while easing the process to comply withstringent standards such as DO178B/C."

Both hardware and software mustcontinue to run even if other systemson the aircraft fail. Though many sys-tems share information, they must alsobe segregated from each other so prob-lems in one subsystem don’t cause er-rors in a related system.

“Engine controls should be isolatedfrom other systems when a level of sys-tem redundancy is required to achieveflight safety requirements,” Celibertisaid. “Systems require isolation to en-sure cross contamination does not takeplace and allow secondary systems to bedeployed when primary systems fail.”

Enhanced DevelopmentEnsuring that software and hardware

operate efficiently in all conditions re-quires plenty of planning and testing.Modeling and simulation have becomecommon tools, facilitated by hardware-and software-in-the-loop testing. Mod-els can be used to improve engine per-formance.

“The benefits come from the preci-sion of scheduling control effectors (ac-tuators, valves, etc.) to meet dynamicperformance and steady state schedul-ing requirements while maximizing sys-tem safety and reliability. This is all fa-cilitated by high-fidelity, onboardmodel predictive control technology,”Celiberti said.

These virtual tests have helped engi-neers find faults in components and dis-crete systems for years, but simulationswere often limited to fairly small ele-ments. More powerful computers andimproved software now make it possibleto see how multiple subsystems work to-gether to spot problems before costlyphysical prototypes are built.

“With capabilities for simulating buscommunications over various standardcommunication bus interfaces such asARINC 429, 1394B, and Ethernet, theentire system can be simulated without

the need for real components,” Mulisaid. “This is helping reduce costs in de-velopment as more and more testing onthe test bench is helping catch errorsearly on.”

As designs move forward, physicaltesting will be added. Hardware- andsoftware-in-the-loop let test engineerscombine the physical components andsystems that are ready with models.These tools continue to evolve, address-ing changes in regulatory requirements.

“DO-178B regulations have promptedsome to revisit some of their tooling,”Muli said. “We’ve got tools that providea way for companies to qualify theirtest environments.”

While virtual testing brings manybenefits and helps shorten developmenttime, it’s not the end all. Developersstrive to reach a point where flight testsserve to prove the validity of virtualtests. While modeling and simulationmake it possible to eliminate some test-ing, these flight tests are in no dangerof disappearing.

“Demonstrating this technology in asimulation environment is one thing;flight clearing it for use in a commercialor military aircraft via FAA and DODsoftware qualification requirements isanother,” Celiberti said.

Modeling and simulation help Pratt & Whitney design and test the engines used in the F-35.

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Modern electronic devices andcomputing equipment areoften integrated with wirelesscapabilities which utilize

multi-bands for high speed communica-tion, as well as high speed circuits andhigh definition graphical displays thatoperate at a wide range of frequencies.As such, hardware systems are becomingincreasingly complex, resulting in prod-ucts that are highly sensitive to electro-magnetic interference (EMI). The vulner-ability to EMI is further heightenedwhen multiple components are packedclose together within the device due tospace, size and weight constraints. Assuch, traditional shielding methods thatemploy materials like thick metal Fara-day cages are not always practical due totheir heavy weight and bulkiness. De-spite its complexity, managing this inter-ference and increasing the resilience ofcomponents, interconnects and subsys-tems within the device is crucial to en-suring reliability and functionality.

For aerospace and defense applica-tions, the requirements for EMI shield-ing will be more stringent as the shield-ing structure and material should alsowithstand potential high power EM at-

tacks such as electromagnetic pulse(EMP) and electrostatic discharge (ESD),which can result in electrical short or di-electric breakdown. Today, an increasingrange of military equipment and avion-ics have displays; shielding EM interfer-ence through optical paths such as cock-pit windows, displays on globalpositioning systems and vehicles, touch-screens on advanced avionics equipmentand computer screens, pose an evengreater challenge as the optical trans-parency of the material is as importantas its shielding effectiveness. As such,there is high demand for EMI shieldingmaterials that are resilient to extremeenvironmental conditions, lightweight,optically transparent and provide mili-tary compliant shielding performance.

Transparent conductive films are usedfor EMI shielding on displays andtouchscreens to reduce radiofrequencyinterference (RFI). Today, Indium TinOxide (ITO) is one of the incumbentmaterials commonly used for this pur-pose, but shielding effectiveness is lim-ited to 35dB or less, depending on theradiofrequency. The shielding effective-ness of other optically transparent ma-terials, such as conductive polymer, car-

bon nanotube and graphene, provideless than 20dB attenuation. Whileshielding results of 20 – 35 dB may besufficient to prevent interference fromlow power consumer electronics, thisperformance does not meet the EMIshielding requirements for defense andaerospace applications.

“Advanced composite materials arereplacing metal in a wide range of ap-plications, in particular for aerospace,due to its attractive properties like lightweight, high stiffness, dimensional sta-bility, and chemical/temperature resist-ance,” commented Steve Hanson, Presi-dent of Precision Gasket Company(PGC), a leading EMI shielding solu-tions provider for military and globalcorporations. “Unfortunately, advancedcomposite materials do not provideshielding levels close to the perform-ance of metal and EMI shielding is be-coming one of the major challenges inaircraft designs.”

At present, the most promising opti-cally transparent EMI shielding solu-tion for defense and aerospace is metalmesh, which is a cross-hatched wirenetwork formed by micrometer-sizedmetal wires. Metal mesh with wire spac-

Optically Transparent EMI Shielding forDefense and Aerospace Applications

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Aerospace & Defense Technology, February 2014 13

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ing and conductivity that is optimizedfor the targeted frequency range canachieve shielding effectiveness of morethan 60dB. In principle, metal meshwires can be developed to be thinenough to become invisible to thehuman eye. This would require theamount of light shaded by the microwires to be engineered to less than 10%,or more than 90% light-through with-out substrate. Thus, the total transmit-tance of metal mesh with a film sub-strate can be higher than 80% if light

reflection from the substrate can beminimized. However, in practice, atlarge-area, high-volume manufacturing,the micro wires are typically thicker andvisible to the human eye. Additionaldrawbacks of this technology are itscomplicated, high-cost, precision man-ufacturing process. Another challengewhen using metal mesh for displays ismoiré, or the visible interference pat-tern that results from placing the metalmesh on the LCD panel in a non-opti-mal position to the liquid crystal pixels.

Next Generation Metal MeshSolution

An innovative new solution, SANTE®

Technology, provides not only the EMIshielding performance of metal mesh,but it can also be mass producedthrough a standard wet coating, roll-to-roll manufacturing process for higherthroughput and volumes.

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Figure 1. SANTE® Technology Self-Assembly Process

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SANTE® EMI Shielding Films can be integrated ontomost displays and touchscreens, including resistive andprojective capacitive, via lamination on either the front orrear surface of the display.

In addition to being a material forEMI shielding on displays, SANTE®

can also be used as a transparent wire-less antenna for Bluetooth, WiFi andLTE networks. SANTE® Films can alsofunction as a transparent conductorfor capacitive sensors with direct andproximity touch capabilities to en -hance the user expereince.

Finally, SANTE® Film is transpar-ent enough to be laminated on glassfor shielding the lens of a surveil-lance camera. It’s conductive net-work can also be transferred fromthe original PET film onto a new sub-

strate like polycarbonate, PC/ABS, or PMMA by addingan adhesive resin, thus providing a solution for inte-grated EMI shielding.

Integration of SANTE® EMI Shielding Films



pure nanoparticles (< 50nm in size) intoan emulsion consisting of water, sol-vents, and chemical bind ers. A thinlayer of this emulsion is wet coatedonto a substrate such as PET film. Underambient conditions, the solvent andwater evaporates, and the emulsion self-assembles into a conductive networkwith a dense array of random nanoscalepores (Figure 1). Within a few seconds,the silver nanoparticles come togetherinto agglomerated, interconnected, mi-cron-size metal wires with line width ofapproximately 5-8 microns, height of 3-5 microns and pore size ranging from250-350 microns. The mesh, alsoknown as the SANTE® Network, shades5-10% of light on the coated surface de-pending on the formulation. Coupledwith a film substrate, the total transmit-

tance is between 80% - 88%. To view avideo of this self-assembly process, goto: www.techbriefs.com/tv/SANTE.

The SANTE® Technology formula-tion used varies for applications de-pending on the requirements forshielding effectiveness, conductivityand transparency. For applications re-quiring higher attenuation, theSANTE® Network can act as a seed layerfor additional metal coating. This post-processing step, or electroplating, cus-tomizes the optical and electrical prop-erties of SANTE® Films for targetedapplications. Other post-processingsteps include sintering or densification,which engineers the RF current flowand the skin depth to improve shield-ing performance at a wider range of RFfrequencies. Adding multiple layers of

SANTE® Film can also further boost itsoverall shielding performance.

EMI Shielding PerformanceEMI shielding effectiveness is heavily

dependent on conductivity and surfaceresistance – lower surface resistance andhigher conductivity results in bettershielding performance. Figure 2 showsthe surface resistance achievable bySANTE® Technology and the correspon-ding shielding effectiveness forEMI/EMC frequencies of 30MHz to1.5GHz, as measured by the ASTMD4935 standard. Typically, an attenua-tion of 40dB or less is sufficient to meetthe EMI/EMC shielding requirements ofconsumer electronics and industrial ap-plications. Defense and aerospace appli-cations, on the other hand, require

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shielding of 50dB andabove. Cima NanoTech iscurrently developing anew series of EMI shield-ing films with surface re-sistance less than 0.1 /sqfor applications which re-quire higher shielding ef-fectiveness.

Areas WhereTransparent EMIShielding is Required

Today, advanced de-fense and aerospace equip -ment such as digital vi-sion systems, military autonomousvehicles, surveillance devices, handheldGPS systems, tactical radios, andruggedized computers have displayswhich emit radiation that may not ful-fill the required military standards(MIL-STD-461 and MIL-STD-464); theshielding effectiveness required is 20-30

dB higher than that of consumer andindustrial applications, as shown in Fig-ure 2. Without proper shielding, mili-tary personnel using such unprotecteddevices risk sending an unwanted sig-nal which alerts others of their loca-tion. In most cases, radiated emissionlevels can be easily reduced by design-

ing a full enclosure that forms aGaussian sphere to shield theoutside from the inside. However,the challenge comes when EMIshielding is required for the dis-plays on these equipment. Un-like materials used in other partsof the device, displays require ashielding material that is trans-parent.

Another application which re-quires a transparent material isshielding for glass doors and win-dows. Many military bases todaybuild shielded rooms to ensureconfidential information dis-

cussed within is not communicated toexternal parties.

This article was written by Chan-darasekaran Krishnan, Senior ApplicationsEngineer, Cima NanoTech Pte. Ltd. (Singa-pore). For more information, visithttp://info.hotims.com/49742-500.

Figure 2. SANTE Technology Shielding Effectiveness

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< 1.0 Ω/sq

< 4.0 Ω/sq

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Pumped two-phase cooling pro-vides a compact, low pumpingpower option for thermal man-agement in high heat flux appli-

cations (300-500W/cm2). Compared tosingle-phase convection, significantlyhigher heat transfer coefficients can beachieved at substantially lower flowrates.Two-phase cooling also provides a highdegree of isothermality, which is impor-tant in many applications such as laserswhose emission wavelengths are temper-ature-dependent.

The phase change (latent heat) ofthe coolant enables two-phase sys-tems to handle high heat fluxes withlow pumping power compared tosingle-phase systems for a given heatload. Two-phase cooling systems areprone to flow/ thermal instabilities,yet engineering solutions are avail-able to address such issues. Specifi-cally, two-phase systems are not newand techniques to effectively man-age instabilities have been studiedand are available, including the ap-plication of engineered microporouscoatings on the heated surface(s),evaluated in this study. The porouscoatings considered here enhancethe boiling performance by increas-ing the nucleation site density andprovide a capillary-driven mecha-nism for resupplying the liquid/

coolant to the heat transfer surface thatpostpones dry-out.

A schematic of a typical pumped two-phase cooling system is shown in Fig-ure 1. Key components include a pump,preheater, surge tank, evaporator/ heatsink, condenser and accumulator. Thesurge tank and the preheater differenti-ate this system from a conventional liq-uid cooling loop. The surge tank con-sists of vapor and liquid at saturation;by controlling the pressure in the tank,the saturation (boiling) temperature of

the working fluid can be controlled.The preheater heats the subcooled liq-uid exiting the condenser to a tempera-ture close to the saturation temperaturebefore it enters the evaporator/ heatsink. This is important as boiling heattransfer is most efficient at saturation(minimal subcooling).

For the sake of illustration, represen-tative experimental results on the cool-ing performance of a pumped two-phasecooling loop are presented here, alongwith some practical considerations con-

cerning the design and operation oftwo-phase cooling systems.

Experimental Hardware The laboratory test setup shown

in Figure 2a is outfitted with a cop-per minichannel heat sink havingoverall dimensions 20.4mm ×12.3mm × 6.0mm with 8 rectangularchannels each having a hydraulic di-ameter 1.8 mm and a channel aspectratio (H/W) of 2.8 (housed withinthe Test Section Assembly). The heatload applied to the heat sink wassimulated using a copper heaterblock containing cartridge heater in-serts. As shown in Figure 2b, theheater block narrows down to apedestal through which heat is trans-ferred to the heat sink. The heat fluxapplied to the minichannel heat sink

Figure 1. Schematic of a pumped two-phase cooling systemshowing key components.

Pumped Two-PhaseCooling for ThermalManagement of High Heat FluxElectronics

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Aerospace & Defense Technology, February 2014 www.aerodefensetech.com 17

Thermal Management

is approximated by the product of thethermal gradient (ΔT/Δx) measuredwith thermocouples positioned alongthe pedestal length using the 1-D heat

conduction formula where

kc is the thermal conductivity of thecopper heater block.

Boiling Enhancement Coatings Micro- and nano-textured porous sur-

face coatings can help stabilize boilingand suppress undesirable flow oscilla-

tions 1, 2. In addition, the use of coat-ings in pool boiling experiments havebeen shown to lower wall superheat ΔT(difference between the wall tempera-ture and the saturation temperature ofthe coolant) for a given input heat fluxas well as increase the Critical Heat Flux(CHF)3. In the current study, the per-formance of porous coatings was evalu-ated in flow boiling conditions whereboth nucleate boiling and forced con-vection play important roles. Images ofselect uncoated and coated heat sinks/

evaporators considered in this study areshown in Figure 3.

ResultsThe thermal performance of coated

and uncoated minichannel heat sinkswas evaluated in the pumped two-phasecooling system shown in Figure 2. Theheat transfer coefficient (HTC) [W/m2K]and the Incipient Wall Superheat [K]were evaluated as a function of the inputheat flux and coolant mass flux [kg/m2s]using refrigerant R134a. Here, the HTC

Figure 2. a) Experimental pumped two-phase cooling system; b) test section containing a minichannel heat sink/ evaporator, housing and heater block used to sim-ulate the heat load.

Figure 3. Minichannel heat sinks (a) without coating, (b) with porous sintered powder coating, and (c) with epoxy-based boiling enhancement coatings preparedcompliments of Dr. You at University of Texas Dallas.

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Thermal Management

was calculated using a one-dimensional

resistance model that yields .

Here, Ts is the average temperature ofthe heat sink base, Tf is the averagefluid temperature (average of the inletand outlet temperatures) and Rb and Rcare the thermal resistances of the copperbase and channel. Notably, Rb = thick-ness of the base/thermal conductivity of

copper and where

Ww is the fin width, Wc is the channelwidth, ζ is the fin efficiency (function ofHTC) and Hc is the channel height. Substi-tuting the experimentally measured values,the equation was then solved for the HTC.

Figure 4a shows the HTC versus heatflux for a fixed coolant flowrate (0.6 gpmequivalent to a mass flux of 1400 kg/m2s).Results of a bare copper heat sink and acoated (sintered copper powder – mesh200-230) are compared. As shown, HTCdepends on the input heat flux. Regard-ing the effect of the microporous coat-ing, it can be seen that the HTC increasesby as much as a factor of 2 with the ap-plication of the coating. Also note thatthe coating has a negligible effect on thepressure drop across the heat sink sincethe coating is very thin (order 100 mi-crons) relative to the channel dimen-sions. Additionally, the HTC as a func-tion of mass flux is plotted in Figure 4b.At low heat fluxes (i.e., 40W/cm2), HTCdoes not vary much as a function of mass

flux. This is characteristic of nucleateboiling. However, at high heat fluxes(160W/cm2), the HTC increases with in-creasing mass flux, characteristic of sin-gle-phase forced convection.

The incipient wall superheat is alsoplotted in Figure 5a as a function ofinput heat flux on coated and uncoated(bare) heat sinks. As shown, the coatingenhances the thermal performance ofthe heat sinks as evident by lower valuesof incipient wall superheat; this meansthat an electronic device mounted on atwo phase heat sink with coating can bemaintained at a lower temperature com-pared to one that is mounted on an iden-tical uncoated heat sink. In Figure 5b,the Critical Heat Flux (CHF) is reportedfor three different surface coatings (lower

qT T

R Rs f

b c

Figure 5. a) Incipient wall superheat is lower for coated heat sinks; b) CHF increases with application of coatings.

Figure 4. (a) HTC as a function of input heat flux for a coated and uncoated (bare) minichannel heat sink and (b) HTC as a function of coolant mass flux for a coat-ed minichannel heat sink with two different applied heat fluxes (40W/cm2 and 160W/cm2)

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Thermal Management

mesh numbers correspond to coarser coatings having largerparticle sizes) and compared to the baseline (no coating). Thismeans that the coating enables the heat sink to handle higherheat fluxes before drying out, at which point the heat sink canno longer efficiently dissipate the high heat fluxes. While allcoatings increase the CHF above the baseline, there is an opti-mum coating that provides the best performance for the heatsink and operating conditions tested. In other words, coatingthickness, particle and pore size of the coating need to be opti-mized for a given application.

In short, coated heat sinks have higher heat transfer coeffi-cients, lower wall superheat, and higher CHF than uncoatedheat sinks. Moreover, temperature and pressure fluctuations(not presented) in the heat sink/ evaporator are suppressedwith the coated heat sinks, thus enabling accurate thermalcontrol and isothermalization of high-power electronics andlaser diodes.

SummaryPumped two-phase cooling systems can handle very high

heat fluxes, operate with small pumps (low pumping power),and can be designed to be compact and reliable. At ACT, effortsare underway to develop an ultra-compact two-phase coolingsystem for ground and air-based platforms. In this study, theheat sink temperature for all cases considered (heat fluxes ashigh as 320 W/cm2 or ~105 W/cm2 on the wetted surface) wasmaintained below 90°C (with a condenser temperature of 30°C).Among other benefits, a two-phase system allows for precisecontrol of the boiling temperature, which in turn enables accu-rate control of the device’s operating temperature.

Flow boiling heat transfer on minichannel copper heat sinkswas evaluated as a function of coolant mass flux, input heatflux, and boiling enhancement coatings. The microporouscoatings substantially improve heat transfer by promoting nu-cleate boiling on the heat transfer surfaces as demonstrated inthe substantial reduction in the incipient wall superheat re-quired to dissipate a given heat flux. For the best performance,for a given application, special attention should however begiven to optimizing the thickness of the porous coating and itsparticle and pore size.

This article was written by Ehsan Yakhshi-Tafti, Xudong Tang,Pete Ritt, and Howard Pearlman, Advanced Cooling Technologies,Inc. (ACT) (Lancaster, PA). For more information, visit http://info.hotims.com/49742-501.

AcknowledgementsSpecial thanks are given to Dr. Tadej Semenic who developed and testedsome of the initial prototypes and Dr. Seung You at the University of TexasDallas for coating select heat sinks and helping characterize their thermalperformance under pool boiling conditions. Funding for this work wasprovided by the National Science Foundation under contract #1127293.

References1. Forster, H. K., & Zuber, N. (1955). Dynamics of vapor bubbles and

boiling heat transfer. AIChE Journal, 1(4), 531-535.2. Semenic, T., & You, S. M. (2013). Two-Phase Heat Sinks with

Microporous Coating. Heat Transfer Engineering, 34(2-3), 246-257.3. Chang, J. Y., & You, S. M. (1997). Boiling heat transfer phenomena from

microporous and porous surfaces in saturated FC-72. International Journalof Heat and Mass Transfer, 40(18), 4437-4447.

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Testing & Simulation

Cracking of coatings and surfacelayers is evident on a variety ofstructures including buildings,automobiles, and aircraft. In

some situations, the appearance of thecoated or painted surface is degradedand the aesthetic appeal is lessened.However, in others, such as compositeaircraft structures, paint cracking isboth aesthetically undesirable and po-tentially deleterious from the electro-magnetic effects aspect.

In the latter case, cracks can propagateinto the structure or around fasteners,providing a path for moisture and otherenvironmental species to enter, resultingin corrosion and degradation of the pro-tection measures including expandedmetal foils (EMF) required for lightningabatement and safe operation. Conse-quently, over several decades there havebeen numerous efforts and investiga-tions concerning the degradation of sur-face layer protection schemes.

Cracking typically develops over ex-tended periods of time due to environ-mental factors and thermal cycling ofthe surface layers and substructure. Thethermal cycling of aircraft is a direct re-sult of the typical ground-to-air-to-ground, often repeated, flight cycle.Subsequently, stresses accumulate inthe coatings, eventually leading to fail-ure of their protective functionality.

There are several contributors to thestress buildup, including the paint,primer, corrosion isolation layer, sur-facer, EMF, and the underlying compos-ite substructure. Boeing recently did astudy that focused primarily on the EMFcontribution to the cracking mechanism.

A representative surface layer protec-tion scheme was addressed that was com-

posed of the layers men-tioned above. The approachtaken was to simulate thetemperature cycle of the lay-ers using a coefficient of ther-mal expansion (CTE) modeldeveloped with the commer-cially available COMSOLMultiphysics software.

The simulation alloweddetermination of the ther-mal stress and displacementsthat result from repeatedduty cycles. Though the fullcomplexity of crack genesiswas not included, some in-sight could be gained regard-ing what the sensitive pa-rameters of the EMF may beand the variations that canbe employed to mitigate theresulting stress and displace-ments that lead to cracking.

Thermal Simulation and Testing of Expanded Metal Foils for

Lightning ProtectionWith the implementation of major aircraft structures fabricated from

carbon fiber reinforced plastic materials, lightning protection has become a more complicated issue for designers and engineers to solve.

Figure 1. Representative surface protection scheme modeled using COMSOL Multiphysics. The compositewas modeled as two layers indicated by the red and light blue regions.

Figure 2. Examples of SWD/LWD ratios from 0.25 to 1.00 for a 1 in2

EMF.

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Of particular interest are the EMF width,height, aspect ratio, composition (alu-minum (Al) or copper (Cu)), and surfacelayup structure.

In the case of Al used for EMF, thereis a need for fiberglass between the alu-minum and the structure to preventgalvanic corrosion. Though not themajor thrust of this research, the poten-tial effect on stress and displacementthat results from the glass transitiontemperature of the paint layer must beconsidered.

Model Solving Boeing developed a CTE model to

simulate the effects of EMFs incorpo-rated in a composite surface protectionscheme undergoing thermal excursionsusing COMSOL Multiphysics software,a finite element solver that contains avariety of physics and engineering ap-plications with an emphasis on coupledor multiphysics analysis.

In particular, Boeing used the ThermalStress Multiphysics Interface that com-bines solid mechanics with heat transfer.Coupling occurs where the temperaturefrom heat transfer acts as a thermal loadfor the solid mechanics, causing thermalexpansion. The interface has the equa-tions and features for stress analysis andgeneral linear solid mechanics, solvingfor the displacements.

A representative surface protectionscheme was created using the COMSOLmodel builder. The layup consisted ofpaint, primer, fiberglass, surfacer, EMF(Cu or Al), and fiberglass on a compos-ite substrate. The height and size of allthe layers could be varied using inputparameters. In addition to geometricalparameters, the initial and final temper-atures could be varied and were chosento be typical of altitude and ground, re-spectively. The strain reference temper-ature was the initial temperature and arepresentative heat transfer coefficientof 5 W/m2K was used.

In addition to the height and width,the aspect ratio of the EMF mesh couldalso be varied. The metallic mesh aspectratio is given by SWD/LWD where SWDis the short way of the diamond andLWD is the long way of the diamond,as described by Dexmet, a commercialproducer of EMF.

The material properties needed foreach of the layers were the CTE, heatcapacity, density, thermal conductiv-ity, Young's Modulus, and Poisson'sratio. Many of these parameters havea dependency on temperature, but forthe simple model references here, re-searchers used the values across thetemperature range of interest. Theone exception was the CTE of thepaint layer where a step function was

employed at the glass transition tem-perature.

The paint had a larger CTE, heat ca-pacity, and Poisson's Ratio than the un-derlying layers. Among other effects,this meant that the paint would un-dergo compressive stress when the lay-ers were heated, and tensile strain whencooled. Hot materials under stress relaxthrough creep, but this effect was notincluded in this particular model. For

Representative Input Material Parameters

Figure 3. Von-Mises stress patterns due to thermal air-to-ground heating cycle. EMF mesh bleed-throughis evident in the central portion of the figure, and relatively large displacement variations are observedabove the metal and voids. Note that the displacements have been magnified for illustrative purposes.

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the other material parameters used, thedensity, thermal conductivity, andYoung's Modulus were larger than thepaint layer. In particular, for the EMF,Al has a larger CTE than Cu, and asmaller Young's Modulus.

Simulation Results For the purposes of this research, Boe-

ing confined its simulations to heatingover a representative air-to-ground tem-perature range that the surface protec-tion scheme was expected to perform.The resulting false color Von-Mises stressand displacement patterns are shown inFigure 3. In this figure, the view is fromthe top paint layer with cross-sectionalviews from the four sides. Obviously,the displacements have been magnified

to highlight the movement that is in-duced by the temperature cycle. In thecentral portion of the figure, the patternof the underlying EMF can be seen.

Variations in the displacement abovethe metal mesh and voids are quite evi-dent in the cross-sectional profiles.Also, high stress (red—high, blue—low)can be seen in the mesh itself and theregion in the mesh voids where surfacermaterial was modeled. The profilesshow that the stress decreases from thebottom to the top of the surface layers.High stresses are clearly indicated in theEMF, where a semi-transparent stressimage was generated.

A more quantitative examination ofthe EMF stresses and displacementscould be determined by creating pro-

files along a selected path through themetallic layer. For this profile, the EMFwas composed of Al with a SWD/LWDratio of 0.50. It was expected that theprofile would show five transitions aseach metal-void region is crossed.

The arrows in Figure 4 indicate cen-tral locations where stress and displace-ments were determined for parametricvariations of EMF SWD/LWD ratio,width, and height. These determina-tions were made for both Al and CuEMFs. The nominal SWD/LWD ratiowas 0.50. Fiberglass was modeled aboveand below both Al and Cu, but in prac-tice is used only below the Al EMF.

For the variation of SWD/LWD from0.25 to 0.75 for both Al and Cu, the dis-placement decreased slightly with anincreasing SWD/LWD ratio. A higherSWD/LWD ratio corresponded to amore open mesh structure (as shown inFigure 2), resulting in lower metal den-sity and hence lower weight. Also, in-clusion of fiberglass below the Cu in-creased the displacement.

By varying the EMF width by a factorof 2.6 for both Al and Cu, the displace-ment remained essentially constant,but was significantly greater for Al thanCu. Varying the EMF height by a factorof 2.7 for both Al and Cu resulted in adisplacement that increased with metalheight and was also significantly greaterfor Al than Cu.

Boeing used a representative tempera-ture dependence of the CTE for the paintlayer to simulate the effect of a shift ofthe glass transition temperature, tg, fromwithin the nominal temperature range toabove it at 350 K. This variation permit-ted the examination of what occurs if thepaint CTE remains constant throughoutthe nominal operating range.

There was a reduction in the surfacedisplacement of the paint when the tgwas above the maximum expected oper-ating temperature. However, when thetg was above the operating temperaturerange, the paint remained in a more brit-tle, glassy state, which is expected to beprone to crack formation. Moving the tgbelow the operating range reduced themodulus that may compensate for theincreased CTE that would occur. Suchtrade studies will be the subject of futuresimulations using this model.

Figure 4. Relative stress and displacement along EMF profile path indicated in Figure 5 for Al with anSWD/LWD of 0.50. The arrows indicate the locations selected for the parametric variations to be shownbelow. Note that five transition regions appear as delineated by the EMF.

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Test Results Quantitative determinations of stress

and displacement were not conductedin the experimental evaluations. There-fore, no detailed comparisons were pos-sible with this model. However, qualita-tive agreement was observed with thesimulations since the EAF (expandedaluminum foil) consistently exhibitedgreater displacement over the variousparameter sets than the ECF (expandedcopper foil) displacements.

Researchers associated greater ther-mally induced displacements with in-creased probability that cracks willeventually become evident. The dis-placement differences may be small,but over thousands of cycles will even-tually generate residual stress, defects,and result in cracking. From this stand-point, both the simulations and testingindicate that Cu would be a betterchoice for the EMF than Al.

The individual parametric variationsalso suggested some interesting effects.The parametric variation of SWD/LWDshown in Figure 5 indicated that larger-ratio, more open EMF meshes lead tolower displacements. The dependenceis weak, but high thermal cycling has acumulative effect. From a weight per-spective, higher SWD/LWD is also desir-able. Provided the EME function is notseriously degraded, there appears to bebenefit with the more open mesh frommultiple perspectives.

The effect of the additional layer offiberglass under the EMF is also shownin Figure 5. When the fiberglass wasadded under ECF, the displacement wassignificantly increased. The remainingdifference between EAF and ECF is mostlikely due to the larger CTE of alu-minum by ~35%. As noted previously,the fiberglass is incorporated under alu-minum to inhibit galvanic corrosion.

Examination of the thermally in-duced displacements suggests that thereis little cracking penalty from increasingthe width of the EMF. Hence, if greatercurrent-carrying capability is desiredfrom the electromagnetic environmentprotection function, increased width ap-pears to be a viable approach. Of course,increased width leads to greater weightpenalty and these conflicting require-ments need to be balanced.

Alternatively, the increased currentcarrying capacity of the EMF layermay also be realized with increasingheight. However, height increase isnot as desirable as it leads to greater

displacements and hence crackinglikelihood.

This article is based on SAE technicalpaper 2013-01-2132 by Jeffrey Morgan ofBoeing (Chicago, IL).

Figure 5. EMF displacement dependence on metal mesh SWD/LWD ratio for Al and Cu.

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From its invention until now, theradio has undergone somemighty technological advances.Conventional or legacy radios are

not programmable; they are designed forone fixed configuration. They are builtto produce a single waveform at a speci-fied frequency. Conventional radiosoften also have limited tuning optionsand fixed data rates. While some con-ventional radios carry multiple types ofdata, they are incapable of adapting tonew waveforms. To make changes onthese legacy radios, the radio wouldphysically need to be changed. Once aradio is out in space, that task becomesnearly impossible to accomplish. Theselimitations created a need for improvedcommunication in space.

NASA engineers needed radios to bemore flexible, adaptable, and evolvable.In the late 20th century, a new type ofradio was developed that would be ableto meet those needs. Software definedradios (SDR) are a type of reconfigurableradio in which some or all of the physi-cal layers of functionality are imple-mented in software and/or firmware.

SDR is a relatively new wireless tech-nology based on the familiar radio tech-nology that has been used for manyyears. Traditional Earth-based radiotechnology involves the transmissionof a signal — typically “analog” speechor music — as electromagnetic wavesusing a single-purpose radio transmit-ter. The electromagnetic waves travelthrough the air until they encounter a

radio receiver that has been tuned to re-ceive the right frequency. This receiverprocesses the signal and sends the re-sult to a speaker. You then hear what-ever was broadcast from the radio sta-tion. In SDR, the transmitter mod u lationis produced by a digital signal processorto produce digital signals; the signalsare then converted to “analog” and sentto the transmitter’s antenna. The re-ceiver uses a computer to recover thesignal intelligence.

"For NASA, SDR applies to the trans-mission of data, rather than sound,"said Jason Soloff, an SDR technologistat NASA’s Goddard Space Flight Centerin Greenbelt, MD. However, Soloff addsthat you may be most familiar with thesound-related commercial applicationsof SDR. "When you are in your car, andyou use your MP3 player to receive anFM signal digitally, you are using SDR-like technology. Or, when you travelfrom an area with an analog cellphone

Software DefinedRadio EnablesFlexibleCommunicationsfor NASACommunication is key to just about any endeavor.NASA’s ability to update and modify communicationcapabilities to reflect the latest upgrades withoutimpacts to mission time or a trip back to Earthensures optimal communication continues. In-orbitreconfiguration for spacecraft radios and systems,including those on the International Space Station, is the goal behind NASA’s Space Communicationsand Navigation (SCaN) Testbed. Ground testing and processing of SCAN Testbed hardware. (JPL)

Glenn Research Center engineers prepare the SCaN Testbed flight system hardware for thermal-vacuumtesting. (NASA)

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AIntro


signal to a digital signal, and yourphone switches automatically, yourphone is acting as a software defined orreconfigurable radio."

With SDR, manufacturers could in-stall a generic radio chip into electronicdevices and later “educate” them to per-form functions quite different thantheir original job through a simple soft-ware download. Similarly, engineerscould reconfigure future SDR-enabledNASA missions at will, allowing for-merly independent satellites to belinked and give a more complete pic-ture of a unique scientific event. Inother applications, two satellites couldinteract and share information, or anolder satellite could be updated with anew function and mission, extendingits life and usefulness.

"Many of our current satellites weredeveloped with a fixed set of data ratesand modulations, so they can only talkto the ground or the space network,"said Soloff. "SDR would allow us toswitch between a ground network and aspace network with simple uploads,making the satellite or instrumentmuch more flexible."

The growth of SDRs offers NASA theopportunity to improve the way spacemissions develop and operate spacetransceivers for communications, net-working, and navigation. Reconfig-urable SDRs with communications andnavigation functions implemented insoftware provide the capability tochange the functionality of the radioduring a mission and optimize the datacapabilities (e.g. video, telemetry, voice,etc.). The ability to change the operat-ing characteristics of a radio throughsoftware once deployed to space offersthe flexibility to adapt to new scienceopportunities, recover from anomalieswithin the science payload or commu-nication system, and potentially reducedevelopment cost and risk throughreuse of common space platforms tomeet specific mission requirements.SDRs can be used on space-based mis-sions to almost any destination.

An On-Orbit TestbedThe NASA Space Communications

and Navigation (SCaN) Program is re-sponsible for providing communications

and navigation services to spaceflightmissions throughout the solar system.Astronauts, mission controllers, and sci-entists depend upon the reliable trans-mission of information between Earthand spacecraft, from low-Earth orbit todeep space. The SCaN Testbed, designed

and built at NASA’s John Glenn ResearchCenter in Cleveland, OH, is an advancedintegrated communications system andlaboratory facility that was installed onthe International Space Station (ISS) inJuly 2012. Using a new generation ofSDR technologies, this ISS facility allows


RF & Microwave Technology

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www.aerodefensetech.com Aerospace & Defense Technology, February 2014Free Info at http://info.hotims.com/49742-811


researchers to develop, test, and demon-strate new communications, networking,and navigation capabilities in the actualen viron ment of space.

NASA’s SCaN office has developed anarchitecture standard for SDRs used inspace and ground-based platforms to pro-vide commonality among radio develop-ments to provide enhanced capabilityand services while reducing mission andprogrammatic risk. The Space Telecom-munications Radio System (STRS) archi-tecture standard defines common wave-form software interfaces, as well asmethods of instantiation, operation, andtesting among different compliant hard-ware and software products. These com-mon interfaces within the architectureremove the application software fromthe underlying hardware to enable tech-nology insertion independently at eitherthe software or hardware layer.

The SCaN Testbed began conductingexperiments last April after completingits checkout and commissioning opera-tions aboard the ISS. The testbed is in-stalled on the EXPRESS Logistics Carrier-3 on the ISS truss. The installation,activation, checkout, and commissioningactivities resulted in a healthy report cardfor the launch software, the three soft-ware defined radios (SDRs), and the an-tennas, avionics, and other subsystems.

The testbed's purpose is to allow forthe development, testing, and demon-stration of cutting-edge communica-tions, networking, and navigation tech-nologies in the challenging environmentof space. These advances will enable

technology developers and mission plan-ners to understand how NASA can useSDRs in future missions, as well as de-velop new concepts such as new algo-rithms for determining orbits using GPS.The technology also can help advancesimilar communications tools here onEarth. SDRs are a viable technology forgroundbased platforms, and are alreadybeing used in smartphones and otherterrestrial applications. NASA's supportfor a common, open architecture aids inthe development of open standards forother domains beyond space.

The testbed is the first space hardwareto provide an experimental laboratory todemonstrate many new capabilities, in-cluding new commu nications, network-ing, and navigation techniques that uti-lize SDR technology. Research andtechnology areas the SCAN Testbed wasdesigned to support include SDRs operat-ing at S, L, and Ka-band; onboard datamanagement function and payload net-working; radio science experiments usingthe unique capabilities of the SDRs; andprecise navigation and timing.

“A software defined radio is purposelyreconfigured during its lifetime, whichmakes it unique,” said Diane CifaniMalarik, a project manager for the SCaNTestbed. This is made possible by softwarechanges that are sent to the device, allow-ing scientists to use it for a multitude offunctions, some of which might not beknown before launch. Traditional radiodevices cannot be upgraded after launch.

By developing these devices, futurespace missions will be able to return

External image of ISS showing SCAN Testbed installed on ELC 4 nadir side. (NASA)

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more scientific information, becausenew software loads can add new func-tions or accommodate changing missionneeds. New software loads can changethe radio's behavior to allow communi-cation with later missions that may usedifferent signals or data formats.

The SCaN Testbed is comprised ofthree SDRs, each with unique capabili-ties aimed at advancing different aspectsof the technology. These devices will beused by researchers to advance this tech-nology over the testbed's five-yearplanned life in orbit. Two SDRs were de-veloped under cooperative agreementswith General Dynamics and HarrisCorp., and the third was developed byNASA's Jet Propulsion Laboratory (JPL)in Pasadena, CA. JPL also provided thefive-antenna system on the exterior ofthe testbed that’s used to communicatewith NASA's orbiting communicationsrelay satellites and NASA ground stationsacross the United States.

NASA Glenn led the design, develop-ment, integration, test, and evaluationeffort, and provided all the facilitiesneeded to fabricate, assemble, and testthe SCaN Testbed, including a flight ma-chine shop, large thermal/vacuum cham-ber, electromagnetic interference testingwith reverberant capabilities, a largecleanroom, and multiple antenna ranges,including one inside the cleanroom.

"The SCaN Testbed represents a signifi-cant advancement in SDRs and its appli-cations for NASA," said David Irimies, aproject manager for the testbed at NASAGlenn. "Investigating these SDR technolo-gies in the dynamic space environment

increases their technology readiness leveland maturity, which in turn can be usedfor future missions as risk reduction."

The future of communications aboardthe space station will improve with theSCaN Testbed's ability to update andmodify capabilities with minimal im-pacts to crew and mission. This technol-ogy also stands to provide time and costsavings for future hardware platforms.With the ability for industry and gov-ernment agencies to partner with NASAto use the SCaN Testbed, this develop-ment can advance space communica-tions of today and tomorrow.

RESOURCES

Watch a video describing the SCaN Testbed on Tech Briefs TV at:www.techbriefs.com/tv/scan-testbed

Visit:www.nasa.gov/mission_pages/station/research/experiments/1058.htmlhttp://spaceflightsystems.grc.nasa.gov/SOPO/SCO/SCaNTestbed/

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Automated Testing of Advanced, High-Performance, Point-to-MultipointRadio Systems

In 2008, 4RF Communications started development of anew range of radio products to augment their existing

point-to-point, long-range wireless link product. Used byoil, gas, and utility companies for monitoring and controlapplications, the Aprisa SR is a point-to-multipoint SmartSupervisory Control and Data Acquisition (SCADA) radiooperating in the 400 to 470-MHz licensed spectrum bandwith a 12.5-kHz channel size and narrowband 9.6-kbps ca-pacity. The Aprisa SR is designed to address the key concernsfacing the industry, such as the need for enhanced security,the need to efficiently handle the increasing complexity ofSCADA networks, and the evolution to an IP-based andsmart grid infrastructure.

The Aprisa SR’s comprehensive feature set and highly reli-able, technically advanced radio platform enable a variety ofmonitoring and control applications that address current andfuture requirements. The radio is configurable as a base sta-tion, remote station, or repeater for seamless integration intoany network topology (Figure 1). It supports a large numberof serial and Ethernet interfaces in a single box, and has built-in security features.

Project Challenge4RF Communications required a different test strategy to

ensure low unit test costs, high throughput, and good testcoverage for the new product features. Therefore, 4RF turnedto test and measurement company CPE Systems to designand develop a test system for cost-effective production testingof the radio. The test requirements for the product includedcomponent and unpowered testing, device programming,radio signal analysis and calibration, and no operator inter-vention.

4RF Communications outsourced the test system develop-ment due to their limited experience with medium- to high-volume test fixtures and limited internal engineering re-sources. The development was contracted to CPE Systems,which selected the National Instruments PXI platform cou-pled with LabVIEW and NI TestStand software to provide theflexible test solution.

Test Development ProcessTest targets for the system were:Test a board in 5 minutesBe suitable for a volume of 3,000 products per monthHave no operator attendance during the testBe operated by nontechnical staffAccess all test points by test probes on one side of the boardInclude a debug facility

Capable of expanding for future product variants such asother RF bands and bandwidthsThe tests were split into three main areas. First was DC test-

ing for testing component values, supply voltages, and cur-rent consumption, and functional testing of the low-voltageshutdown, switch panel, and LED indication. The second area

was built-in self-test (BIST) for boot loader and software in-stallation, testing of the RAM and flash, and confirmation ofEthernet address allocation. These tests were programmedinto the device and accessed through a command line inter-face. The third area was RF functional testing and calibration,which was used to test and calibrate the transmitter, receiver,and system functions of the Aprisa SR board.

Development ChallengesDue to the product development schedule, the test system

was developed in parallel with the product, which entailedfive re-spins of the board design. However, due to how thetest system was designed and specified with flexibility inmind, these PCB redesigns required only one change to thejig. Using NI hardware and software enhanced the ability tocarry out concurrent development.

One of the key constraints for the test system was test time,with an overall target of 5 minutes per board. This target re-quired a significant amount of optimization in the RF calibra-tion algorithms to ensure they operated efficiently. The NIPXIe-5663 vector signal analyzer (VSA) and NI PXIe-5673 vec-tor signal generator (VSG) supported this algorithm optimiza-tion process.

The Aprisa SR printed circuit board assembly included RFtransmission and reception circuits, and had to be testedout of its enclosure. As such, RF interference and screeninghad to be included in the jig design. This was achievedusing the CAD model of the product housing to machine anRF screening enclosure that formed part of the top plate ofthe jig (Figure 2). This shielding produced results from thetest fixture that were close to those achieved with the boardin its enclosure.

The Aprisa SR radio has internal data encryption, whichmakes it impossible to generate simulated data streams totest the receiver sensitivity. Using the VNA, the radio sig-

Figure 1. Test fixture showing screening of RF section.

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nal recorded and retransmitted using the VSG at differentlevels to test the receiver sensitivity with actual data. Thismethodology meant that the encryption process couldchange in the future without affecting the test system soft-ware.

Developing the RF test system presented challenges interms of the management processes required to coordinatethe project across multiple sites, and in terms of the tech-nical challenges that involved testing a complex RF prod-uct at high speeds with screening incorporated in the fix-ture. The outcome of the development was a custom, yetaffordable, test system that tests and supports the manu-facturing process of the high-performance SCADA radioproduct.

This article was written by Stephen Patterson of CPE Systems,Chatswood, New Zealand, using hardware and software from Na-tional Instruments, Austin, TX. For more information, visit http://info.hotims.com/49742-542.

Figure 2. The final test system.

Aerospace & Defense Technology, February 2014

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Technology Update

Automated drilling machine takes the burr out of fuselage joint

More than 1200 large-diameter (up to¾-in) holes must be drilled into tita-

nium/carbon stacks for the side-of-bodyjoint on a particular Boeing commercialaircraft fuselage. This is the joint be-tween the upper shell (section 44) of thecenter fuselage and the lower correspon-ding section (section 45), which includesthe wingbox and the landing gear well.

The upper shell material is mainlycarbon-fiber-reinforced plastic (CFRP)reinforced with a thick titanium innerstructure (Boeing prefers not to discloseany more specific aircraft design de-tails). The upper shell is secured to sec-tion 45 on both sides by a long tita-nium side-of-body fitting.

One of the many challenges associatedwith side-of-body joints is keeping debris,or burrs, from entering between the layerswhile drilling holes. This is especially truewith titanium/CFRP material stack-ups.The burrs can cause stress concentrations,reducing the life of the aircraft.

Because manual drilling was notyielding consistent hole quality, Boeingdecided to automate the side-of-bodydrilling process, teaming with Elec-troimpact to develop a solution.

Boeing required that the automateddrilling process eliminate burrs betweenthe layers to allow for one-up-assembly.One-up-assembly eliminates the needto remove the upper shell for cleaningand deburring, avoiding time- and cost-intensive operations.

Implementing an automated solutioninto existing assembly lines was com-plicated by the location of the workarea, which is more than 15 ft abovethe factory floor.

The focus was first on stabilizing thedrilling process. A support structure wasneeded to provide the necessary travelfor a small drilling machine and to pro-vide access to the fuselage and auto-mated guided vehicle (AGV) system inthe existing assembly lines. The result-ing support structure (a long beam ele-vated on two columns) needed to beoptimized for both stiffness as well asnatural frequency due to the “invertedpendulum” effect of the layout. Elec-troimpact engineers used extensive FEAto optimize the structure for both low

deflection and high natural frequency.As it turned out, the stiffest beam wasnot the most stable solution in this case.

Another key was developing an auto-mated drilling machine that was lightbut that could also support the heavydrilling loads created when drillingholes in titanium of up to ¾-in diame-ter. Engineers had to take into account

how these drilling forces would affectoverall system (i.e., machine and struc-ture) stability, which determines holequality.

The final machine package weighsless than 6500 lb and includes a mobileinterface to give Boeing the flexibilityto move the machine from one side ofthe aircraft to the other or to different

Computer rendering of the side-of-body drilling machine showing the basic components: support structureand moveable drilling machine. The blacked-out area is the wingbox and landing gear well. The machineworks above the wingbox and gear well along the shell’s length. (The rendering does not necessarily showthe actual length of the section.)

In addition to drilling holes and installing fasteners along the length of the side-of-body fitting, themachine performs the same duties for a portion of the circumferential joints between the upper shells infront of and in back of the center shell. Most of that work is done via Flex Tracks (shown), which are alsosupplied by Electroimpact.

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Technology Update

In the case of composite materials,material properties are vastly depend-

ent on the manufacturing process.While shifting the manufacturingprocess of a composite part from pre-impregnated to a new liquid resin in-jection process, the Composites Devel-opment team at Bombardier Aerospacehad to redesign the component to anew set of design allowables. The Inte-grated Product Development Team(IPDT) was able to quickly provide aturnkey solution that assessed three as-pects of airframe engineering: design,materials and processes (M&P), andstress.

The stress substantiation process, ledby the team’s stress engineers, requiredthree distinct checks be confirmed: thatthe global behavior of the surroundingstructure remained unaffected, that alllocal failure modes still exhibited posi-tive margins of safety, and that detaillevel testing was organized to provide

complete substantiation for the certifi-cation authorities.

This method was used successfully oncomponents of programs currentlyunder development at BombardierAerospace. The IPDT approach as wellas the novel means of substantiation al-lowed for a quick turnaround, resulting

in the rapid preparation of a positivebusiness case for both weight and cost.

Stress substantiation process Typically, non-recurring costs associ-

ated with high-performance resin trans-fer molding (RTM) manufacturing pre-clude small aeronautical production

assembly lines using the existing fac-tory crane.

The drilling machine is an all-servosystem capable of storing hundreds ofdrilling process parameters to providecustom drilling profiles for each holetype and material stack-up configura-tion. Hole quality and cycle times wereoptimized with the different profiles tocontrol burrs at the material interfacesor transition points.

Parameters for up to five unique mate-rial layers could be referenced along withadditional processes for breakthroughand countersink operations. Parametersinclude spindle speeds, feed rates, clampforce, peck times, and lubrication. To en-sure that parameters were switched ap-propriately, drill depth was determinedfrom either the tip or from the full diam-eter. This was extremely important whenentering or exiting titanium, whichwould destroy cutters if CFRP parameterswere used. Drill thrust and distancedrilled is monitored to increase holequantity and maximize drill life.

To achieve a drilling process for one-up-assembly, the machine is capable

of installing a temporary doweling/clamping fastener. It is pro-grammed to automatically select afastener based on the programmedstack thickness and install the fas-tener in certain holes. These fasten-ers provide the clamping force re-quired to eliminate burrs fromentering between the layers. Shift-ing of the different layers is pre-vented by having a close fit be-tween the fastener and holediameters.

The drilling and fastening pro -cesses are qualified by Boeing toachieve the one-up-assembly for theside-of-body joint.

The stability of the system (boththe support structure and machine),controllability of the drilling process,and mobility of the machines pro-vide Boeing with a flexible and reli-able drilling system.

This article is based on SAE Interna-tional technical paper 2013-01-2296by Michael Assadi, Christopher Martin,and Eliot Siegel of Electroimpact Inc.;and Dennis Mathis of Boeing.

Photo of the machine in actual deployment. A workingsurface area has been constructed level with the sup-port beam, and the machine had to be designed to fitunder an overhead structure.

Redesign of composite parts for structural integrity

Containment of buckling waves to bays by stiffening members.

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Technology Update

volumes. However, repeating part num-bers created a business case where thenon-recurring costs were amortizedover enough components that the RTMprocess yielded decreased cost in addi-tion to a shorter cycle time.

The need to size the part to a com-plete new set of design allowables in-cluded a drastic variation in laminacured ply thickness, as well as notablevariations in matrix type failures suchas compression after impact and inter-laminar shear and tensile stress. As a

starting point, both the material andprocess were qualified and allowableswere readily available.

The first consideration while re-designing a component is to ensure theredesigned structure behaves identicallyto the baseline. Fuselage structures aresimply thin skin sheets supported bystiffening members. These membersserve two major roles: they providesome area to the fuselage cross-sectionto carry loads, and they provide sup-port to the skin and prevent it frombuckling. For thin sheets subjected toshear or compressive loading, the loadsat which the plates buckle are muchlower than the material strength.

While it is a good practice to targetthe baseline design’s stiffness for longi-tudinal axis and out-of-plane bending,this is not necessary. This is due in partby the fact the rigidity of the fuselage isonly provided in fraction by thestringers, which represent at most 50%of the total area. Furthermore, the stiff-ness of the fuselage is provided mostimportantly by the total area of skinand stringer of the fuselage and its dis-tance from the centroid. Large varia-

tions in area-moment-of-inertia relativeto the stringer are negligible to the di-mensions of the fuselage and do notcontribute to a redistribution of loadswith the surrounding structure. Thisopens up the design space significantlyand allows engineers to tailor the lami-nate to manufacturing and stress allow-ables.

To ensure that the global modes werestill met, buckling analysis was per-formed using FEA. While beam theorycan provide insight on the general be-havior of the structure, buckling is anEigenvalue problem that is far too com-plex when applied to large structures tobe solved analytically. Linear bucklinganalysis using commercial finite ele-ment codes provides a means to cor-rectly evaluate the structure and deter-mine the most critical buckling modes.

The strategy was to use detailed finiteelement models (FEMs) of sections ofthe baseline fuselage that were affectedby the redesign and subject them tounitary compressive, shear, and com-bined loading. By subsequently substi-tuting in the FEM the laminate of thebaseline design with that of the re-designed component, and re-evaluatingthe first eigen modes, it is possible toconfirm that the redesigned componentdoes not change the modes in whichthe structure buckles, and that the asso-ciated buckling loads are unaffected.

Local failure modes The approach taken for pre-sizing the

redesigned part was to reuse as much ofthe work already completed for sizingthe baseline as possible. In sizing re-ports for skin and stringer panels, it iscustomary to present shear-bending-axial force (VMA) plots and assess theload levels within the structure andconfirm the extracts from the globalFEM are coherent.

With a standard plot of envelopeaxial force along the length of the forefuselage, it is possible to notice the max-imum positive value is slightly largerdue to the effect of pressurization whencompared to the compressive loads.With the transverse shear loads in astringer positioned at the window belt,it is possible to notice the windowcutouts where large values are obtained,

Buckling shape of fuselage panel subjected tocompression-shear combined loading.

Typical axial load distribution of fore fuselage.

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AIntro


as well as the fore passenger door onthe left hand of the plot.

Having defined that the redesignedcomponent was to be subjected to thesame loading as the baseline, it was pos-sible to use the plots to extract the mostcritical load cases. The three maximumand three minimum values of eachaxial, transverse shear, and bending mo-ment load were determined. These val-ues correspond to combinations of fuse-lage station (FS)—i.e., position alongthe fuselage length—and load case andthe associated selection criteria. Consis-tent loading was subsequently extractedfor the 18 most critical FS/load casecombinations and was used to size thecomponents.

The beam loads subsequently need tobe decomposed and distributed to com-pute the numerous margins of safety as-sociated with the different allowables.This includes primarily laminatestrength and local stability of the weband flanges. For this, composite beamtheory is used.

The essence of the methodology re-lies on the fact that equivalent beamrigidities for axial, shear, and bendingmoments were used to calculate beamstrains. These were then used to evalu-ate the strains at multiple locationsalong the member cross-sections. Thesecalculated strains were comparedagainst strain allowables for laminatestrength. Plate running loads at variouslocations along the cross-section werealso evaluated and compared againstbuckling allowables or crippling.

The methodology was easily imple-mented using procedural programming.This contributed to the quick turn-around as multiple iterations of variouslaminates could be evaluated withoutthe need for a complex analysis to berecomputed. Following inputs from de-sign and manufacturing, a laminate wasdefined that incorporated requirementsfor ease of manufacturing. The lami-nate defined presented little to no fiberdeviation and increased drapabilitywhile still meeting all stress margins ofsafety.

While the substantiation methodol-ogy is insufficient for the initial designof airframe structures due to the lack ofprior knowledge, it does allow for

turnkey solutions to be implementedefficiently at all stages of program de-velopment. Most importantly, this re-design approach is not associated withthe customary exponential cost increaseof late changes to projects. This waspossible only through prior knowledge

of both the new manufacturing processand the current baseline design.

This article is based on SAE Interna-tional technical paper 2013-01-2328 byJean-Philippe Lachance and Jean-EvrardBrunel of Bombardier Aerospace.


Technology Update

Whether you have an existing CMM device or about to purchase one, Verisurf-X is the only software you need. With its 3D CAD-based architecture, fl exible reporting options, and ease of use, Verisurf-X will reduce training time and increase productivity, right out of the box. No matter what you are making or measuring, Verisurf-X provides the power to drive your devices, reduce cost, improve quality, and streamline data management – all while maintaining CAD-based digital workfl ow.

Learn more about the power of Verisurf-X by visiting our Website,

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Tech Briefs

Power Management for the Electric Taxiing SystemIncorporating the More Electric ArchitectureThe electric taxiing system does not require the use of jet engines or the auxiliary power unit.

IHI Corporation/IHI Aerospace, Tokyo, Japan

With airlines increasingly direct-ing their attention to operating

costs and environmental initiatives,the More Electric Architecture forAircraft and Propulsion (MEAAP) isemerging as a viable solution for im-proved performance and ecofriendlyaircraft operations. An electric taxi-ing system was developed that doesnot require the use of jet engines orthe auxiliary power unit (APU) dur-ing taxiing, either from the depar-ture gate to takeoff, or from landingto the arrival gate.

Cutting engine operating timesduring taxiing, including wait andstandby times, would require anelectric power management systemthat shuts down the main powersupply, including the engines andAPU. Clearly, the alternative elec-tric power source would simultane-ously need to supply power notjust for taxiing propulsion, but forall aircraft electric and electronicssystems.

The MEAAP concept offers thepromise of greater power manage-ment efficiency compared to con-ventional aircraft systems. Re-searchers have developed severalcornerstone technologies, includinghigh-voltage drivers, fault tolerancesystems, and electrical-mechanicalengineering tech nol ogies, all withthe goal of building more efficientelectric systems for aerospace appli-cations.

This work targets practical applica-tions of energy management tech-nology, focusing primarily on elec-tric power systems that take over theroles of conventional aircraft sys-tems. This system must address twoissues: safety and reliability, andpower source and storage. The au-tonomous taxiing approach must in-corporate an electrically drivenwheel system. A more eco friendlyapproach requires the replacement Power system block diagram of an Electric Taxiing System.

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of devices that run on jet fuel. Insteadof an engine or APU generator, a smallerprimary power source based on a fuelcell or other battery system can be used.Comprised of a common electric motorand inverter, the electric taxiing systemdrives the front gear or main gearwheels. Each of the aircraft's electric-powered wheels is controlled by state-of-the-art power electronics and con-trollers. This system gives pilots totalcontrol of aircraft speed, direction, andbraking while on the loading apron andtaxiway.

This electric system requires awholly new electric power source. Be-fore taxiing, the aircraft avionics sys-tem must be activated, while the envi-ronmental control system (ECS),including air conditioning, must workcontinuously. The ECS must draw itspower from another power source,since we cannot draw on conventionalengines or APU power. To shift fromthe engine and APU to a substitutepower source at the airport, aircraftsystems must be designed to reducepower requirements, since the substi-tute power sources will have lower en-ergy and power densities than gas tur-bine generators.

After leaving the loading apron, theaircraft operates on a taxiway. Smoothrunway performance in real-world sys-tems will likely require an electricaltaxiing system capable of speeds of 30to 40 km/h. A single-aisle aircraft re-quires a 6-kW power source to run at 4km/h. Based on the taxiing speed goal,approximately 60 kW power will be re-quired when running at maximumspeed (40 km/h).

As it moves on the taxiway, the air-craft will repeatedly stop and gowhile lining up and waiting for take-off. To meet the significant peakpower requirements for heavy air-craft, a temporary power energy stor-age system can augment the primarypower source. In addition to accom-modating high-density accelerationand bump climbing during the typicaltaxiway traffic cycle, the power energystorage system can provide energy tothe electrically driven wheels with thehigher power levels required for rela-tively short durations.

When the power required to propelthe aircraft is less than the power pro-duced by the primary power source,the excess energy can be stored in thepower energy storage system for lateruse, thereby achieving eco friendlypower/energy control. General electri-

cal specifications for aircraft systemsdo not permit regeneration to the elec-trical system. Regenerative currentcauses distortion on the power buses.A power energy storage system capa-ble of absorbing high regeneratedpower during regenerative braking will


Tech Briefs

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The goal of this work was to investi-gate the concept of using harvested

energy to directly control the vibrationresponse of flexible aerospace systems.Small, lightweight, flexible micro airvehicles (MAVs) operate near flutter,providing both harvesting opportuni-ties and vibration suppression require-ments. The possibility that the ambientenergy might be harnessed and recy-cled to provide energy to mitigate thevibrations through various control laws

was investigated. The goal was to inte-grate harvesting, storage, control, andcomputation into one multifunctionalstructure.

As ambient energy is relatively lowlevel and the hope was to run vibrationsuppression systems off of harvested am-bient energy, feedback control laws weresought that used a minimum amount ofenergy. Such control laws did not exist,so ways to minimize control effort forvibration suppression had to be discov-

ered. Basic control laws were tuned toachieve the same performance. The re-quired amount of energy in each casewas calculated and compared.

It was found that as much as two-thirds of the required energy can besaved by using a saturation control. Thisreduction makes running a control lawoff of harvested energy possible. In im-plementing these control laws, it wasdiscovered that the high voltages com-manded by the control laws result in the

piezoelectric coupling coefficientbeing non-constant. An adaptivecontrol law (exponential actually)was implemented to account forthe change in coupling coeffi-cient as the control voltage de-mand increased. The next majorresult was to integrate harvestingand storage into the same pack-age with a control actuator and acontrol law (i.e. the circuitry) allembedded in a multifunctionalcomposite structure as illustratedin the accompanying schematic.

A multifunctional system wasfabricated, modeled, and tested,and was capable of energy har-vesting, sensing, energy storage,


Tech Briefs

Schematic of a Multifunctional Structure containing harvesting, control, energy storage, and computing.

Simultaneous Vibration Suppression and EnergyHarvestingThis technology can be used to provide energy to micro air vehicles.

Virginia Polytechnic Institute and State University, Blacksburg, Virginia

boost system efficiency. Assuming re-generative power is equivalent to thepower required for acceleration, regen-erative energy storage must be capableof providing 80 kW over 10 seconds.Several available storage devices canmeet these regenerative power needs,including lithium-ion batteries, super-capacitors, and flywheel batteries.

To overcome the issues posed by con-ventional fuel cell systems, a regenera-tive fuel cell (RFC) system is one solu-tion for FC fuel supply and onboardstorage. An RFC system requires merewater as fuel, since the RFC, which in-corporates a water electrolyzer, is an

autonomous system that produces oxy-gen and hydrogen. The RFC consists ofproton exchange membrane fuel cells(FC), electrolyte cells (EC) linked to themain power bus, and fuel storage tanks.Some of the main bus power is suppliedto the EC to produce hydrogen andoxygen from water for FC operations.The power generated from the mainengine generators during climb, cruise,and descent is transmitted to the ECfor hydrogen and oxygen refueling, aswell as for supplying electricity for allaircraft systems. Hydrogen- and oxy-gen-fueled FC power is used for electricpower generation when needed.

Once the aircraft arrives at the gate,the power supply from an internalsource shuts down. Aircraft electricity isprovided from the external power sup-ply — the Ground Power Unit

(GPU). The GPU provides the powerneeded to generate hydrogen and oxy-gen in the RFC system to prepare forthe subsequent flight and operations.

This work was done by Hitoshi Oyori ofIHI Aerospace Co. Ltd. and Noriko Moriokaof IHI Corporation. The full technical paperon this technology is available for purchasethrough SAE International at http://papers.sae.org/2013-01-2106.

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Tech Briefs

vibration suppression using active con-trol, embedded computing (providingenergy management and control laws),and structural integrity. Before proceed-ing, the harvesting, sensing, and con-trol authority of several different typesof piezoelectric material were consid-ered in order to choose the best compo-nents for each task. Macro fiber com-posites form the best control actuationdevices, and monolithic piezoceramicforms the best sensing and harvestingdevice.

Following these initial results, theconcept of a multifunctional compositebeam was applied to a problem preva-lent in unmanned air vehicles (UAVs).UAVs tend to be light and travel neartheir flutter speed, which means thatthey are susceptible to instabilitiescaused by gusts. While the UAV is innormal flight, its wing vibrates. Themultifunctional wing spar, modeledafter the schematic, would transfer the

wing vibration into electrical energyand store it in the embedded battery.When the UAV hits a gust, the sensorfunction of the multifunctional sparwould then see the increased strain, andturn on the active control system em-bedded in the PCB part of the spar.

The resulting feedback control lawwould then quiet the gust response andkeep the vibration suppressed duringthe period of the gust. The laboratoryresults show great agreement with thetheoretical models and numerical simu-lations.

Simulations were then used to pre-dict how the system would behave as agust suppression system for a smallUAV. The gust and clear sky condition(the condition of vibration induced dur-ing normal flight) were simulated usingthe Dryden PSD signal for both clearsky and gust. The simulations were fedinto the model of the multifunctionalwing spar. The response of the wing to

a gust shows a large tip deflection. Theresponse of the wing tip with the con-troller turned on and the gust as inputshows substantial vibration reduction.

There are applications where har-vested energy can be of use, even whenthe energy requirements exceed thosethat are required, if there is not a con-stant need for that energy. This is surelythe case illustrated here with the gustalleviation example. Many other exam-ples exist in the area of structural healthmonitoring. The main work here showsthat closed loop control can be accom-plished with harvested energy.

This work was done by Daniel J. Inmanand Pablo Tarazaga of Virginia Tech for theAir Force Office of Scientific Research. Formore information, download the Tech-nical Support Package (free white paper)at www.aerodefensetech.com/tsp underthe Physical Sciences category. AFOSR-0005


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http://www.abpi.net/ntbpdfclicks/l.php?201402ADTPTSP




Tech Briefs

Cascading Failures in Coupled Distributed Power Grids andCommunication NetworksCommunication network-based power measurement and control approaches can impact power net-works in the face of weapons of mass destruction-induced cascading failures.

Defense Threat Reduction Agency, Fort Belvoir, Virginia

Emerging distributed power grid systemswill integrate tightly coupled networks,

namely a power grid and a communica-tion network, to provide distributed powermonitoring and control. While distribut-ing power monitoring and control awayfrom a central site enhances the robustnessof the power grid to multiple, dispersedfailures and attacks, such communication-based distributed control schemes can in-troduce complex cascading failure scenar-ios in the face of large-scale weapons ofmass destruction (WMD) attacks.

The objective of this project is to modeland analyze the interactions between cou-pled communication networks and powerdistribution grids so that potential cascad-ing failures in the composite complex bi-infrastructure network can be examined,analyzed, and avoided. This work is moti-vated by fundamental challenges presentedby potential distributed power grid topolo-gies and structures currently under discus-sion in the power community. Using acombination of graph-theoretic dynamicalmodeling of cascading failures, optimal dis-tributed control algorithm design, and dis-tributed estimation techniques, it is possi-ble to see how various communicationnetwork-based power measurement andcontrol approaches impact the robustnessand efficiency of power networks in theface of WMD-induced cascading failures.

Investigation of cascading failure mech-anisms has shown that load shedding canbe an effective method of reducing thelikelihood of cascading failure, if imple-mented in a timely manner. However, cur-rently load shedding is generally imple-mented by an operator manually,following a request from a system opera-tor. Moreover, requests are subject tohuman judgment, and sometimes fail tobe implemented correctly, in a timely man-ner, and/or in their entirety. An automatedresponse, making use of energy storage,would have two benefits: first, its imple-mentation would not depend on humanjudgment, and second, its impact on end

users would be less severe. For example,storage units (thermal storage, communityelectric storage, utility-scale electric stor-age) may be deployed to produce a certainlevel of load shed, rather than resorting torolling blackouts or brownouts.

There are a number of challenges inthe implementation of automated, fast-acting load shedding strategies for WMDprotection. First, the mechanism must becompatible with “normal” grid operationmechanisms. Second, the mechanismmust be compatible with local regula-tions. For example, control by real-timepricing (RTP) may be possible in some re-gions, but not others. Where RTP is notavailable, other control mechanisms mustbe adopted. Finally, the control strategiesmust be robust – for example, high-band-width communications requirementsmay pose problems because, in the caseof WMD attack, communications net-works may become congested or even in-operable. Two strategies for load controlwere considered – RTP and stochastic.

With RTP control, the cost of power is afunction of the residual capacity of the sys-tem. This is in line with industry practices,and is also compatible with WMD re-sponse, since a WMD attack would auto-matically result in reduced capacity. Thecustomers use automated response to acti-vate their storage devices. Thermal load iseither met by depleting storage or by pur-chasing power from the network, depend-ing on an internal power price threshold.The threshold for meeting thermal load, inturn, is set based on the state of charge ofthe storage – a high threshold when stateof charge is low, and vice versa. The thresh-old for charging is set similarly.

Stochastic control (SC) could be used inregions where RTP is not allowed by regu-lation. In this case, the utility or somecontrol agency would send a signal to allcustomers, between 0 and unity, repre-senting the probability of activating a dis-tributed resource. In turn, each resourcegenerates a random number, which is

compared with the utility signal. Based onthe result of the comparison, the device iseither activated or not. With stochasticcontrol, loads can choose to op-in, and befinancially compensated as a result.

Results have shown that both RTP andSC are effective means of controlling thetotal load on the grid, and can respond ef-fectively to both renewable energy inter-mittency and load shedding requests.Moreover, the bandwidth for communica-tion is very low – only requiring a commonsignal to be broadcast at regular intervals,typically on the order of minutes. Thesesame mechanisms could be used for en-hanced readiness to WMD threats. For ex-ample, it is possible to increase the storageSOC in cases of enhanced threat, simply bymodifying the RTP or the stochastic signal.

Simulations were performed to revealthe effects of the control/communica-tion system parameters on the cascadingfailures in power grids. Simulations haveshown that vulnerabilities in the con-trol/communication systems can increasethe probability of large cascading failuresinitiated by small disturbances over thepower grid. In addition, the topologicallocation and characteristics of the fail-ures affect the cascading behaviors in thepower grid. Since inhibition and cluster-ing can be important attributes of WMDattacks, which exhibit a great level ofspatial correlation, the effects of spatialinhibition and clustering among the un-controllable load buses were studied.These effects can be important due to thenature of certain disaster events that mayaffect the power grid and theircontrol/communication systems.

This work was done by Majeed M.Hayat, Andrea Mammoli, YasaminMostofi, and Patrick Bridges of the Univer-sity of New Mexico for the Defense ThreatReduction Agency. For more informa-tion, download the Technical SupportPackage (free white paper) at www.aerodefensetech.com/tsp under thePhysical Sciences category. DTRA-0002

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Implementing Interconnected Generation in Future CivilAircraftPower protection equipment enables detection and interruption of transients and arc faults occurringat a single point in an aircraft’s electrical network.

University of Strathclyde, Glasgow, UK, and Rolls-Royce PLC, London, England

In addition to providing thrust, the en-gines on conventional civil jet airlin-

ers generate power for onboard systemsand ancillary loads in the form of pneu-matic, hydraulic, and electrical power.There is a move to begin replacing me-chanically, hydraulically, and pneumat-ically powered aircraft systems withelectrical equivalents, towards the ulti-mate goal of achieving the All-ElectricAircraft (AEA).

Until recently, a number of aircraftloads were powered pneumaticallyusing air bled from the high-pressurecompressor stages in the thrust en-gines. On conventional aircraft, thishot, high-pressure air is used to heatthe leading edges of the wing and en-gine nacelle to prevent potentially dan-gerous ice buildup, and is also cooledand expanded to provide pressurizedcabin air. This is a convenient methodof supplying such loads. Compressorbleeding, however, carries a significantefficiency impact, and pneumatic sys-tems are prone to leaks and difficult tomaintain.

The Boeing 787 represents the state-of-the-art in more electric civil aircraft,and is the first civil airliner to replacemost of the pneumatic systems withelectric equivalents. As well as progres-sively replacing ancillary loads withelectrical equivalents, the industry isturning towards electrical power forflight control as well.

Recent developments in fast-acting,solid-state protection equipment, to-gether with work in the field of engineefficiency and fuel savings, provide theplatform for a move towards intercon-nected generation. Reducing the isola-tion of the electrical system will neces-sitate more advanced and faster-actingprotection strategies. By increasing thedegree of interconnection, a greater pro-portion of the aircraft’s systems will beexposed to transients and faults occur-ring at a single point in the network.

This increased effect will need to be mit-igated by protection equipment thatcan detect and clear faults in the net-work before bus conditions become inbreach of the power quality standards.

Several advancements in the field ofelectrical network protection equip-ment have been realized that may en-able such protection coverage to be at-tained. In particular, Solid State PowerControllers (SSPCs) and Fault Isola-tion Devices (FIDs) offer advancedfunctionality that may facilitate thesafe interconnection of generation.Such solid-state devices offer very fast(25 – 50 μs) operation with improved

reliability and the possibility of moreintelligent control. They provide amore predictable and consistent oper-ation over a longer life because theyhave no moving parts; therefore, theydo not suffer as much from issues withwear and tear. Unlike conventionalcircuit breakers, they are capable ofdetecting and interrupting arc faults,and can operate according to a num-ber of profiles.

A salient requirement in an initial im-plementation of interconnected genera-tion would be the provision of a mini-mum of two channels. This approachwould be required to comply with cur-


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Tech Briefs

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Tech Briefs

rent standards that require separate iso-lated supplies for critical systems such asflight control and pilots’ instruments. Itwould also create a stepwise path toachieving a fully interconnected system

while still offering potential fuel savingsand operability improvements throughthe inter con nection of generators con-nected to multiple shafts on the sameengine.

Sources that are interconnected mustbe protected from becoming impairedor damaged by transients and faultscaused by the failure of other sources.This is an explicit requirement of exist-ing standards, but is also a sensible con-sideration to ensure continuity of sup-ply and compliance with the reliabilityrequirements. It is anticipated that inaddition to use of faster-acting protec-tion equipment, a suitably advancedprotection strategy will make use of dis-tributed local systems with authorityover smaller portions of the overall net-work, together with careful network de-sign with consideration to fault propa-gation times.

Ideally, a dynamically reconfigurablenetwork would be realized that is capa-ble of adapting to current load condi-tions and component health. This maymean that the eventual embodiment ofthis technology will be “dynamicallyinterconnected,” with the networktopology able to adapt to existing con-ditions.

It is possible for the essential electri-cal bus to be supplied from any of theisolated generator buses on current air-craft. A more interconnected systemwould necessarily reduce the availablesupply redundancy for the essential bus,and this would have to be taken intoaccount when designing the intercon-nected architecture. It is expected thatthe topology of the essential system it-self (with attached loads and emergencysupplies) would remain unchanged, butthat some appropriate interface bemade with the interconnected systembus/buses.

Interconnected generation could pro-vide the platform for a number of fuelefficiency and engine operability im-provements. It could also provide amore reliable, dynamic network that ismore able to meet the increasing elec-trical power demands of modern air-craft.

This work was done by Gordon Macken-zie-Leigh, Patrick Norman, Stuart Galloway,and Graeme Burt of the University of Strath-clyde; and Eddie Orr of Rolls-Royce PLC.The full technical paper on this technologyis available for purchase through SAE Inter-national at http://papers.sae.org/2013-01-2125.

Overview of the 747 Electrical System. During normal operation, all breakers are closed.

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Application Briefs

Pictorial Representation Tool forFirst-Aid Training

Charles River AnalyticsCambridge, MA617-491-3474www.cra.com

Reducing combat fatalities demands quick and effectiveemergency care on the battlefield, and all soldiers are ex-

pected to provide immediate, basic care to themselves or theircomrades. Critical first-aid procedures are described in theSoldier's Manual of Common Tasks, but recalling the proce-dures in stressful, life-threatening battlefield environments ischallenging. In addition, each first-aid skill is composed ofnumerous, interrelated subtasks and processes. Successful ac-complishment of the subtasks and processes depends heavilyon an individual soldier's basic aptitude, underlying skills,and understanding of the task flow involved.

Charles River was chosen by the US Army Aeromedical Re-search Laboratory at Fort Rucker, Alabama, inventors of thetraining tool concept, to design and create Pictorial Represen-tations of Medical Procedures to Train for Effective Recall,also known as PROMPTER, to improve the retention of USArmy soldiers' battlefield first-aid skills. Critical first-aid skillsare represented in PROMPTER through simple, intuitive sym-bols that represent first-aid actions or emergency medicalprocedures.

The symbols are then incorporated within a frameworkthat aids long-term memorization of the first-aid methods.The memorization aids are presented to soldiers throughadaptive microgames that provide an engaging gameplay ex-perience tailored to their individual skills and training needs.Charles River made the games available to soldiers throughsmartphone apps and Web browsers that can be accessedfrom any location. It is believed that soldiers who are able to

effectively perform these first-aid procedures under traumaticbattlefield conditions can reduce the number of preventablecombat deaths.

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Tactical Fighting System SimulatorEnvironmental Tectonics CorporationSouthampton, PA 215-355-9100www.etcusa.com

Most fighter aircraft simulators are fixed-base, with no mo-tion or sustained G-capability. Even those with six de-

gree of freedom (6-DOF) motion bases provide only motioncues and cannot replicate an authentic, sustained high-G en-vironment. While providing useful training for cognitivetasks, and providing some workload and environmental stres-sors, the devices cannot present the complete spectrum ofphysical stresses inherent in actual flight operations. Thus,current simulator training cannot effectively reproduce live-aircraft training events such as Basic Fighter Maneuvers(BFM), Air-to-Ground Weapons Delivery, Close Air Support

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Application Briefs

(CAS), Offensive/ Defensive Counter Air (OCA & DCA), Car-rier Qualification (CQ) Operations, Field Carrier LandingPractice (FCLP), and air refueling.

By combining simulation, visual, and motion technologies,the Authentic Tactical Fighting System (ATFS-400™) over-comes simulator limitations and effectively trains pilots. Pilotinputs command a multi-axis, high-performance motion sys-tem, which accurately produces properly aligned G forces,whether in positive or negative G flight. The combination ofcontrol system architecture, control laws, and flight modelsprovides not only the rapid-onset and sustained performance

motion of 4th- and 5th-generation fighter aircraft, but also thetrue feel of the specific aircraft with Signature Technology™.

In a two-shift operation, one ATFS-400 replaces 12 to 16aircraft sorties per day, with surge capability to higher rates, ifnecessary. The ATFS-400 greatly reduces first flight risk in sin-gle-seat aircraft for new F-22 and F-35 pilots, and users trainwith a F-35 Helmet Mounted Display. The aircraft trainingtool can also be integrated into Distributed Mission Opera-tions Network (DMON) for multi-ship, multi-platform train-ing events.


Ultra-Light Prototype VehicleU.S. Army Tank Automotive Research, Development andEngineering Center (TARDEC)Warren, MI586-215-8763tardec.army.mil

At the U.S. Army Tank Automotive Research, Developmentand Engineering Center (TARDEC), final testing is beginning

on the Ultra Light Vehicle (ULV) Research Prototype platform. Funded by the Office of the Secretary of Defense, the ULV

project was set up to design, develop and build three identi-cal, lightweight tactical research prototype vehicles, empha-sizing survivability for occupants and meeting four researchobjectives:

Payload – 4,500 lbsPerformance – at 14,000 lbs curb weight

Protection – comparable to the currently fielded Mine-Re-sistant Ambush-Protected (MRAP) vehiclesPrice – $250,000 each in a hypothetical 5,000-unit produc-tion run. TARDEC’s Ground System Survivability group partnered

with non-traditional defense contractors. In only 16months, the team moved from design to prototype. Theteam produced three vehicles: two will be used for mobil-ity, mine blast, and ballistic survivability testing, and thethird is moving into TARDEC’s Ground Systems Powerand Energy Laboratory (GSPEL) for mobility and fuel effi-ciency testing. Results are expected to be available inearly 2014.

The hybrid design allows for a “clean underbody”through the elimination of various automotive compo-nents, allowing for blast-mitigation technologies to per-form uninhibited during a blast event. Either of the electricmotors can power the vehicle, providing redundancy.

ULV’s final design was devel-oped by lead contractor HardwireLLC (www.hardwirellc.com). Re-mote-mounted and remote-con-trolled vehicle electronics reduceHVAC loads and create more in-terior space than similarlyequipped tactical vehicles.“Clamshell” front and rear doorsopen away from the B-pillar, cre-ating a protected area for soldiersto exit.

Interior technologies includea crushable floating floor sys-tem that absorbs energy and de-couples the crew’s feet and legsfrom the steel hull. ULV alsoutilizes high-strength steels andadvanced composite materials,offering lightweight ballisticprotection.


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Application Briefs

Electro-Optical Boresight WeaponSystemSenso OpticsYokneam, Israel +972-4-993-5527www.senso-optics.com

The combat effectiveness of a weapon system depends substan-tially on its hit probability. The most accurate aiming occurs

when an optical device is aligned to the weapon’s bore centerline. Senso Optics has announced the VBS-80, an electro-optical

boresight for accurately aligning sights to guns. The VBS-80features a user-friendly interface that calibrates 7.62mm -155mm muzzle gun barrels. The boresighting system allows asingle soldier to complete the aligning procedure by utilizinga video camera.

The VBS-80 contains an Electro-Optical module (EOU),which aligns the optical axis with the mechanical axis. Its opti-cal focus is fixed but can operate from 20 meters to infinity.The socket that receives the caliber rod is fine-polish-machinedso that the caliber rod retains center accurately when dis-mounting and re-mounting the EOU. The VBS-80 features ahigh-resolution CCD camera, electronically adjustable reticule,and an interface to existing Fire-Control-System (FCS) displays.


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Signal AHPEC PlatformGE Intelligent Platforms (Waltham, MA) has announced the

DSP281, a rugged, dual-node, quad-core 6U OpenVPX HighPerformance Embedded Computing (HPEC) deployed serverplatform. GE’s HPEC architecture scales from one to manyprocessor nodes per enclosure via RDMA-enabled InfiniBand®and Ethernet dual port network interface cards. In addition,system integrators can minimize card count by mapping mul-tiple platform functions, such as control, DSP, image and

video processing and graphics, ontoone or more DSP281s.

The DSP281 is supported by GE’sAXIS Advanced Multiprocessor Inte-grated Software development envi-ronment. AXISPro includes a high-

performance IPC middleware and GUI for task levelprogramming and fast prototyping.


Upmast Radar System Kelvin Hughes (Enfield, UK)

offers a carbon composite hous-ing for its SharpEye™ radar sys-tem. With coherent transmis-sion and Doppler processing,the system separates targetsfrom clutter, resulting in greatly improved situational aware-ness, even in adverse weather conditions. A lightweight an-tenna turning unit and transceiver housing is resistant toshock, vibration, and corrosion. The technology also featuresa low Radar Cross Section (RCS) design and a GaN-transistorTransceiver.

SharpEye™ is an upmast system resulting in virtually nosignal loss in the interconnecting waveguide between the an-tenna and transceiver. The use of a synchronous motor hasremoved the need for a gearbox, with the antenna rotationrate being controlled electronically. Peak power has increasedfrom 200W to up to 300W.


Inductance-to-Digital Converter Texas Instruments (Dallas, TX) unveiled an inductance-to-

digital converter (LDC), a new data converter category thatuses coils and springs asinductive sensors. Induc-tive sensing measures theposition, motion, orcomposition of a metal or conductive target, as well as detectsthe compression, extension or twist of a spring.

Benefits of LDC technology include sub-micron resolutionin position-sensing applications with 16-bit resonance im-pedance and 24-bit inductance values; contactless sensingthat is immune to nonconductive contaminants; and lessthan 8.5 mW system during standard operation. The 16-pin,4 × 5 mm LDC1000EVM includes an MSP430F5528 micro-controller (MCU).


New Products

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possibilities without the preparation of solutions. Specially formulated compounds and can be used for contact repair, prototype development work, electronic instrument repair,

medical instrument repair etc.

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New Products

COTS Benchtop SDSIThe LibertyGT™ 1200B from

RADX Technologies (San Diego,CA) combines RADX real-timemeasurement science softwareand firmware with NI PXI mod-ules and NI LabVIEW system de-sign software. The 1200B, a pro-

grammable benchtop Software Defined Synthetic Instrument(SDSI), is housed in an integrated, field-service-optimizedbenchtop enclosure equipped with a comprehensive RF Inter-face Unit (RFIU) and High-Definition (HD) touchscreen dis-play. With its LabVIEW software framework, multicore Intel®Core™ i7-based embedded controller and multiple Xilinx®

FPGA processing capabilities, the 1200B supports the integra-tion of user Test Procedure Sets (TPS), user programs andscripts via industry standard APIs, and languages such as Lab-VIEW, IVI, Python, and XML.


Thermoelectric Air ConditionersTECA Corporation (Chicago, IL) offers a flush-mounted

thermoelectric air conditioner. For enclosures with limitedspace, flush-mounted air condition-ers provide cooling without physi-cal intrusion into the enclosure.Environmental gasket and hard-ware preserve the enclosure's envi-ronmental integrity.

TECA’s “Green Zone,” or high-ef-ficiency, model has a C.O.P. rating of 0.83. An Eco-Mode fea-ture also uses up to 85% less energy than the active mode.The air conditioners are configured for environments includ-ing NEMA-12, NEMA-4, and NEMA-4X. Customization isavailable.


Printer Interface UnitSabtech (Yorba Linda, CA) has announced its new Printer

Interface Unit™ (PIU). The technology allows any commer-cial off-the-shelf (COTS) printer to be used in place of a mili-tarized PT-540 or compatible printer. Sabtech’s PIU has passedU.S. military environmental qualification tests, includingshock, vibration, temperature, humidity, electromagnetic in-terference (EMI), airborne noise, altitude, and drip.

A PT-540 printer can be connected directly to the compact,fanless unit via USB or the built-in Ethernet port, and can be

located on a network with ap-propriate configuration. Inputpower and data connectors areplug-compatible with those onthe PT-540 printer, allowing ex-isting cables to be easily con-nected. Power to the printer is

provided from the PIU, eliminating the need to run new ca-bling at the installation site.


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New Products

Optical Backplane InterconnectSystem

TE Connectivity (Harrisburg, PA) hasreleased the new VITA 66.1 RuggedizedOptical Backplane interconnect system.The optical system is offered in both areceptacle (backplane) and mating plug(daughtercard) connectors, which inter-connect up to two MT ferrules, each ac-commodating up to 24 fiber paths.

TE’s Ruggedized Optical System isbuilt to survive: Cycle Life (Mate/Un-mate) of 100 Mates; shock levels OS1(20G) / OS2 (40G) & Bench Handling;and random vibration levels V1 & V2(PSD = 0.04 G^2/Hz), V3 (PSD = 0.1G^2/Hz).

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Graphics Display ModuleCurtiss-Wright Controls Defense So-

lutions (Ashburn, VA) has introduced anew embedded graphics module, theVPX3-716 3U OpenVPX™ six-head

graphics display card. The module is de-signed for use on deployed airborne andground vehicle platforms.

The VPX3-716 supports embeddedtraining, moving maps, Geographic In-formation Systems (GIS), 360 degree sit-uational awareness, Diminished VisionEnhancement (DVE), and other graph-ics- and video-intensive applications.The module features six independentgraphics outputs, 2 GB of dedicatedvideo memory, and H.264 MPEG4 mo-tion video decoders. A CoreAVI suite ofembedded software drivers includesOpenGL graphics, OpenCL computedriver, and H.264/MPEG 2 video decodedrivers.

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New Products

Rackmount RecordersPentek (Upper Saddle River, NJ) has introduced the Model

RTR 2728 rugged portable and the Model RTR 2748 ruggedrackmount recorders. SSD (solid state drive) storage technol-ogy achieves aggregate recording and play-back rates up to 4 GBytes per second.

Systems are built on a Windows 7 Pro-fessional workstation with an Intel CoreI7 processor. The tools provide both aGUI and API to control the sys-tem. Signal analysis tools are alsoprovided to allow the user tomonitor and analyze signals priorto, during, and after a recording.

Data files include time stamping as well as recording pa-rameters and optional GPS information. Files are stored inthe native Windows NTFS (new technology file system) for-mat, and they can also be transferred from the systemthrough gigabit Ethernet, USB ports, or written to opticaldisks using the built-in 8X double layer DVD±R/RW drive.

The recorder’s SSDs are configured to support numerous RAIDlevels. The rackmount system is scalable to accommodate multi-ple chassis for more channels and higher aggregate data rates.


Interconnect SolutionsMolex (Lisle, IL) manufac-

tures a variety of interconnectsolutions for the aerospaceand defense industry. Theirhigh performance cable as-semblies include a range of RF/Microwave cable assembliesutilizing Temp-Flex® Low-Loss and Ultra Low-Loss FlexibleCable for applications through 50 GHz. These cables are flex-ible alternatives to semi-rigid styles, including 0.047, 0.086and 0.141 inch sizes. Molex can provide standard assembliesin three-inch increments with a range of connectors includ-ing 2.92 mm, SMP, SMA, SMPM and many others.

Their ruggedized backplane cable assemblies deliver high-speed data transfer between commercial backplanes or servers,including Impact™, Impel™, VHDM® and others, to commer-cial-off-the-shelf (COTS) connectors or full military-qualified in-terfaces. These rugged assemblies provide reliable data through-put of between 2 to 25 Gbps even in the harshest environments.Their fiber optic technologies for aerospace and defense applica-tions include FlexPlane™ Optical Flex Circuitry, Circular MT As-semblies, VITA 66.1 Ruggedized Optical MT Backplane Intercon-nect System and Optical EMI Shielding Adapters.



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10HTS is a silver-filled, one part epoxy adhesive withhigh electrical conductivity and superior strengthproperties. It cures to a tough thermoset and is resist-ant to thermal shock and vibration. Supreme 10HTSis ideal for applications where low outgassing isrequired. www.masterbond.com/tds/supreme-10hts

Master Bond Inc.

THERMALCONTROL VALVEThe Senior AerospaceThermal Control Valve inte-grates the temperature sens-ing, actuation, and valvefunction into a compactpackage. The all-metal con-struction is capable of opera-

tion at temperature extremes and meets today’s high-er reliability requirements. Designs may be fine-tunedfor specific actuation temperature ranges. This is ide-ally suited for turbine engine accessories coolingrequirements or anywhere where automatic thermalcontrol is required. http://www.metalbellows.com/

Senior Aerospace


CUSTOM RUBBERMOLDING TO EXACTSPECIFICATIONSYou probably know us best as pro-ducers of rubber molded parts.However, you may not know thatwe’ve produced many parts that

other companies considered nearly impossible tomake. Our specialty? Precision custom molded partsat a competitive price with on time delivery.Injection, transfer and compression molding ofSilicone, Viton, Neoprene, etc. Hawthorne RubberManufacturing Corp., 35 Fourth Ave., Hawthorne,NJ 07506; Tel: 973-427-3337, Fax: 800-643-2580,www.HawthorneRubber.com

Hawthorne Rubber

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S.I. Tech

MULTIPHYSICSSIMULATIONPAPERS ANDPRESENTATIONSBrowse over 700 papers,posters, and presentationsfrom the COMSOLConference, the world’s

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COMSOL, Inc.

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Ad Index For free product literature, enter advertisers’ reader service numbers at www.techbriefs.com/rs, or visitthe Web site beneath their ad in this issue.

Reader ServiceCompany Number Page

Reader ServiceCompany Number Page

www.aerodefensetech.comPublished by Tech Briefs Media Group (TBMG),

an SAE International Company

ACCES I/O Products . . . . . . . . . . . . . . . . . .814 . . . . . . . . . . . .35

AeroDef Manufacturing 2014 . . . . . . . . . .780 . . . . . . . . . . .46

AMPTEC RESEARCH Corp. . . . . . . . . . . . .820 . . . . . . . . . . .45

Associated Spring . . . . . . . . . . . . . . . . . . .798 . . . . . . . . . . . . .2

Aurora Bearing Company . . . . . . . . . . . . .818 . . . . . . . . . . . .43

Avionics Interface Technologies . . . . . . .796 . . . . . . . .COV II

Avnet Electronics . . . . . . . . . . . . . . . . . . . .801 . . . . . . . . . . . . .7

Bal Seal Engineering, Inc. . . . . . . . . . . . . .809 . . . . . . . . . . . .23

Coilcraft CPS . . . . . . . . . . . . . . . . . . . . . . .800 . . . . . . . . . . . . .5

COMSOL, Inc. . . . . . . . . . . . . . . . . . . .840, 825 . . . . .47, COV IV

Crane Aerospace & Electronics . . . . . . . .803 . . . . . . . . . . . . .9

CST of America, Inc. . . . . . . . . . . . . . . . . . .824 . . . . . . . .COV III

Dexmet Corporation . . . . . . . . . . . . . . . . . .819 . . . . . . . . . . . .43

FEKO - EM Software & Systems (USA) . . .811 . . . . . . . . . . . .26

Hawthorne Rubber Mfg. Corp. . . . . . . . . .841 . . . . . . . . . . . .47

Heilind Electronics . . . . . . . . . . . . . . . . . . .842 . . . . . . . . . . . .47

Herber Aircraft Service Inc. . . . . . . . . . . . .817 . . . . . . . . . . .40

Hunter Products Inc. . . . . . . . . . . . . . . . . .823 . . . . . . . . . . .44

Lyons Tool & Die Co. . . . . . . . . . . . . . . . . . .797 . . . . . . . . . . . . .1

M.S. Kennedy Corporation . . . . . . . . . . . .802 . . . . . . . . . . . . .8

Master Bond Inc. . . . . . . . . . . . . . . . . .821, 843 . . . . . . . .45, 47

Mini-Systems, Inc. . . . . . . . . . . . . . . . . . . . .812 . . . . . . . . . . . .27

New England Wire Technologies . . . . . . .806 . . . . . . . . . . . .15

OMICRON Lab . . . . . . . . . . . . . . . . . . . . . . .805 . . . . . . . . . . . .13

Photon Engineering . . . . . . . . . . . . . . . . . .815 . . . . . . . . . . . .37

Proto Labs, Inc. . . . . . . . . . . . . . . . . . . . . .804 . . . . . . . . . . . . .11

S.I. Tech . . . . . . . . . . . . . . . . . . . . . . . . . . . .844 . . . . . . . . . . . .47

Senior Aerospace . . . . . . . . . . . . . . . . . . . .845 . . . . . . . . . . . .47

Tech Briefs TV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Techspray . . . . . . . . . . . . . . . . . . . . . . . . . .808 . . . . . . . . . . . .19

TRUMPF Inc. . . . . . . . . . . . . . . . . . . . . . . . .799 . . . . . . . . . . . . .3

TTI, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .816 . . . . . . . . . . . .39

Verisurf Software, Inc. . . . . . . . . . . . . . . . .813 . . . . . . . . . . . .33

Voltage Multipliers, Inc. . . . . . . . . . . . . . . .822 . . . . . . . . . . .44

W.L. Gore . . . . . . . . . . . . . . . . . . . . . . . . . . .810 . . . . . . . . . . . .25

Editorial ______________________________________

Production/Circulation __________________________

Sales & Marketing ________________________________Thomas J. DrozdaDirector of Programs & ProductDevelopment (SAE)

Linda L. BellEditorial Director (TBMG)

Kevin JostEditorial Director (SAE)

Bruce A. BennettEditor (TBMG)

Jean L. BrogeManaging Editor (SAE)

Lindsay BrookeSenior Editor (SAE)

Billy HurleyAssociate Editor (TBMG)

Patrick Ponticel, Ryan GehmAssociate Editors (SAE)

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Matt Monaghan Assistant Editor (SAE)

Lisa ArrigoCustom Electronic Products Editor (SAE)

Kami BuchholzDetroit Editor (SAE)

Richard GardnerEuropean Editor (SAE)

Jack YamaguchiAsian Editor (SAE)

Terry Costlow, John Kendall, Bruce Morey, Jenny Hessler, Jennifer Shuttleworth, Linda Trego,Steven AshleyContributing Editors (SAE)

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Lois ErlacherArt Director (TBMG)

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Tech Briefs Media Group, an SAE International Company

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CST of America®, Inc. | To request literature, call (508) 665 4400 | www.cst.com

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© Copyright 2013–2014 COMSOL. COMSOL, COMSOL Multiphysics, Capture the Concept, COMSOL Desktop, and LiveLink are either registered trademarks or trademarks of COMSOL AB. All other trademarks are the property of their respective owners, and COMSOL AB and

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