introduccion sensores ilene busch-vischniac

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Mechanical EngineeringResearch News and Projects



he Department of Mechanical Engineering has evolved substantially over the two years since the last

Newsletter was published. Our research programs have grown, and our academic programs are flourishing.

Our faculty continue to receive accolades from the scientific and professional communities. Two exciting

young faculty members have joined us: Allison Okamura in the area of robotics and Jean-François Molinari

in computational mechanics. This brings our faculty size to fifteen, and we have plans for three more hires in

the near future.

The most notable development, however, is a recent reorganization that we have undertaken as part of a

process I call “Reconstructing Mechanical Engineering.” As a result, we now characterize the research activi-

ties of the Department in terms of the following areas:

• Microscale/nanoscale science and engineering

• Computational engineering

• Aerospace and marine systems

• Robotics and human-machine interaction

• Energy and the environment

• Mechanical engineering in biology and medicine

This reconstruction effectively moves us away from the traditional compartmentalization in terms of disci-

pline, and focuses instead on the cutting-edge research that we do. Associated with this reconstruction is are-organization of the options afforded to our undergraduates, and the development of several targeted

Masters programs that focus in some of these areas. Managing these changes will take us some time, and I

expect to report to you on our progress in succeeding issues of this Newsletter.

In the past, the Department has published two distinct documents: a Newsletter for our alumni and friends,

and a Brochure for potential students and visitors. This publication replaces both of the previous documents,

and is intended to serve a larger audience, including our alumni, potential and current students, visitors and

peers. By nature, therefore, we can include here only a sampling of the many exciting things that happen in

the Department. A much more detailed picture of the Department can be obtained from our web site,

www.me.jhu.edu, which includes links to each of the research laboratories, the academic programs, and lists

undergraduate and graduate students, and alumni.

The Department has always benefited from the goodwill of its alumni and friends, and I hope that you will

continue to support our students and academic programs. As always, all contributions are valuable, large or

small, and whether financial or through direct action on behalf of the students and faculty. A selection of spe-

cific ways in which you can contribute to our development is included in this document (see p. 29).

I encourage you to visit us at Homewood if you are in the area. Please feel free to call us at 410-516-6451, or

to send us email, or simply to drop by. There is very little that the faculty and students enjoy more than

showing off the wonderful things that they work on every day, and I expect that you will enjoy feeling the

pounding pulse of one of the leading engineering departments in this great research university.

With best wishes,

K.T. Ramesh

September 2001

Letter from the Chair

T



Micro/nanoscale Science and Engineering 4

Computational Engineering 10

Aerospace and Marine Systems 14

Robotics and Human-Machine Interaction 17

Energy and the Environment 20

Mechanical Engineering in Biology and Medicine 23

Senior Design Projects 26

Awards and honors 29

Endowment Naming Opportunities 29

Society of Scholars 30

Table of Contents

Contact Information

Department of Mechanical

Engineering

Latrobe Hall

3400 N. Charles Street

Baltimore, MD 21218-2681

Phone: 410.516.7132

Fax: 410.516.4316

Web: www.me.jhu.edu

The Johns Hopkins

University does not discrimi-

nate on the basis of race,

color, gender, religion, sexual

orientation, national or ethnic

origin, age, disability, veteran

status or marital status in any

student program or activity

administered by the universi-

ty or with regard to admission

or employment. Defense

Department discrimination in

ROTC programs on the basis

of sexual orientation conflicts

with this university policy.

The university continues its

ROTC program, but encour-

ages a change in the Defense

Department policy.

Questions or concerns regard-

ing Title VI, Title IX and

Section 504 should be referred

to the Director of Affirmative

Action Programs, 205

Garland Hall, 410.516.8075.

AAO 10/00 (102.1)

Writing/Editing:

Mary Parlange

Faculty Coordinator:

Charles Meneveau



Think Small

Enter the world of Professors Kevin

Hemker and William Sharpe, and you

step into an incredible shrinking universe.

Imagine a sensor so small that it could be

placed on the end of a catheter to measureblood pressure intravenously. Inside the doors

of a new car, tiny accelerometers stand ready to

deploy the side airbags in a

crash. These and other sim-

ilar devices, known as

MicroElectroMechanical

Systems, or MEMS, consist

of tiny mechanical systems,

often bundled together with

electronic processing cir-

cuitry, all on a silicon chip

the size of your fingernail or

smaller. Driven by the pos-sibility of exciting commercial applications

and encouraged by a manufacturing technology

already in place thanks to the prevalence of

microchips, scientists have unleashed a virtual

flood of MEMS research in the past decade. As

a result, nanotechnology is quickly moving

from the realm of science fiction into everyday

life. Mini-robots, mini-tweezers, mini-gyro-

scopes, and any number of millimeter-size

devices may soon be manufactured at very low

cost and employed in many aspects of our lives.

To imagine things this small, relative scales

help—the trip from 10 m to the atomic scale(nanometers) spans the same orders of magni-

tude as going from 10 m to

the solar system scale. A

micrometer is about 100

times smaller than the

width of a hair. Tiny pieces

of a material at the

microscale behave very dif-

ferently than large hunks of

the same stuff at the

macroscale. Gravity,

weight, and inertial forces

are overshadowed by frictional forces, surface

tension, and electrostatics. Understanding the

mechanical properties of materials at this tiny

scale and predicting the materials’ behavior are

fundamental to improving MEMS technology.

Professor Kevin Hemker explores how individ-

ual grains of a material will behave under vari-

ous conditions, testing microsamples for

strength and other mechanical properties, and

watching defects form and spread in single

crystals of a material.

Atoms in a material line up in a particular

way, into “grains” that form a crystalline struc-

ture. By altering the processing parameters

slightly, it is possible to “tune” the underlin-

ing structure to optimize the mechanical prop-erties of the material, such as its strength.

Strength is governed by how defects spread,

both within a grain and

from one grain to the next

throughout the sample. The

smaller the grains within a

structure, the more bound-

aries there are to stop a dis-

location from spreading,

and thus the stronger the

material. In a related proj-

ect, Prof. Hemker and PhD

student John Balk haveemployed Transmission Electron Microscopy,

or TEM, to characterize the atomic structure of

defects in a sample of single-crystal gold, about

10 nm thick (25-30 atoms high). They found

that the defects always spread on a specific

plane, about 6 atoms wide, and showed that

defects in iridium have the same atomic struc-

ture as in gold. This similarity was predicted

by colleagues at Northwestern University, and

the TEM observations are now being used as

benchmarks for more detailed calculations.

When he’s not peering at TEM images of

atoms, Prof. Hemker is testing microsamplesof materials from other laboratories. The sam-

ples, which look like flea-

size dog bones, are destined

for use in a variety of

MEMS applications, and

benchmarks for their

mechanical properties are

needed for proper design of

MEMS devices. With spe-

cial tools, he stretches and

examines the samples, dis-

covering when they behave

elastically (i.e., whether they return to normal

after stretching), deform, or break.

Tensile tests on materials used in MEMS

technology are not commonplace; in fact the

JHU facility is the only place in the United

States that conducts tensile tests on MEMS

materials. Professor William Sharpe laid the

foundations for this strain testing measurement

method back when he was working as a gradu-

Micro/nanoscale Science and Engineering

4

Kevin J. Hemker

Professor Joint Appointment, Materials Science and Engineering

Postdoctoral Fellow ÉcolePolytechnique Féderale de

Lausanne, Switzerland 1990–93

Ph.D. Materials Science and Engineering, Stanford University, 1990

M.S. Materials Science and Engineering, Stanford University, 1987

B.S. Metallurgical Engineering, University of Cincinnati, 1985

Research Interests:

Microstructural characteriza-tion, using advanced electronmicroscopy techniques and computer generated image simulations



ate student at Hopkins in the 1960s. He spent

the last 35 years perfecting the technique,

coming full circle in the process, back to

Hopkins, where he has been a member of the

ME faculty since 1983, and chaired the depart-

ment from 1983 to 1988 and from 1991 to

1997.Some of the materials sent by MEMS man-

ufacturers have seen use in microelectronics,

but their mechanical properties have never

been considered. Polysilicon, for example, is a

ceramic widely used in integrated circuits as an

electrical material, but in MEMS technology it

is often used struc-

turally. Its strength

and other mechani-

cal properties there-

fore become the crit-

ical factors. Prof.

Sharpe uses anInterferometric

Strain Displacement gauge to assess the

strength, modulus of elasticity, and Poisson’s

ratio of the material. In this technique, each

specimen, about a micron thick and 50

microns wide, is “marked” in the middle with

two tiny gold lines. The tester then shines a

laser beam across the sample, and the beam is

diffracted by the lines, setting up an interfer-

ence pattern. As the material is stretched, the

lines move relative to one another, and this

change is picked up in the interference pattern.

This technique can detect changes as small asone or two nanometers. The way a material

deforms under a given strain reveals its

mechanical properties. Their strain measure-

ments of polysilicon and silicone nitride, both

widely used in MEMS technology, were an

essential contribution to the acceptance of a

standard value for the modulus of elasticity of

these materials.

Micro-cool

In the ever-shrinking land of MEMS, heat

can be a problem. As these devices shrink insize, power per unit volume increases, and

components get hot. Blowing cool air over

them is not very effective because the heat

capacity of air does not provide enough cooling

for these tiny areas. A possible solution is to

cycle fluid cooled via a MEMS-scale thermoa-

coustic refrigerator around a device, according

to Professor Cila Herman, an expert in ther-

moacoustic refrigeration.

A thermoacoustic refrigerator uses sound

energy to transport thermal energy. Using a

sound source such as a loudspeaker, a standing

wave is set up in a tube filled with noble gas.

As the wave travels back and forth in the

chamber, the gas compresses (heating up) andexpands (cooling off). The gas also oscillates in

the chamber. To exploit this energy, a “ther-

moacoustic core,” consisting of a densely

packed stack of plates, is placed in the cham-

ber. As the gas oscillates, it compresses and

heats up, transferring heat to the plates. Then,

as the gas expands

and cools down, it

absorbs heat from

the plates. This sets

up a temperature

gradient within the

plates, effectivelypumping heat from

the cool side to the hot side of the core. Attach

heat exchangers to the thermoacoustic core,

and this device becomes a useful refrigerator.

Fluid cooled with the thermoacoustic refrigera-

tor can cycle over microelectronic components,

absorbing their heat, and then return to the

heat exchanger to cool down and repeat the

cycle. Prof. Herman and former graduate stu-

dent Martin Wetzel (currently with BMW

Research in Munich, Germany) are well-known

for their groundbreaking experimental and

theoretical work in thermoacoustic refrigera-tion. The Heat Transfer Lab in the basement of

Latrobe Hall houses a working thermoacoustic

device, and Prof. Herman and her students

study the heat transfer using a variety of tech-

niques, including holographic interferometry

and digital image processing.

Building an efficient device that can tackle

a specific cooling load involves applying theory

carefully to the scale of the problem at hand.

The cooling that a MEMS-scale thermoacoustic

refrigerator can do is a problem involving

many parameters, such as the thermal proper-

ties of the fluid being used for the cooling, the

material of the plates in the stack, the length

of the stack, and the length of the tube.

Optimization of the system involves combin-

ing groups of these parameters with a specific

outcome in mind. Interestingly, Prof. Herman

found that sets of parameters leading to two

seemingly similar outcomes—maximum effi-

ciency and maximum cooling—were not the


5

William N. Sharpe Jr.

Alonzo G. Decker Professor of Mechanical Engineering

Ph.D. MechanicsThe Johns Hopkins University,

1966

M.S. Mechanical Engineering, North Carolina State

University, 1961

B.S. Mechanical Engineering North Carolina State

University, 1960

Research Interests:

Experimental solid mechanics,emphasizing microsample

testing and strainmeasurements at notch roots

The most thermodynamically efficient device will

minimize the work going in and maximize the

useful effect, the cooling—this is a system with the

most energy conversion. On the other hand, a

device that provides maximum cooling will be one

that removes the most heat.



same. In addition, she, former graduate student

Martin Wetzel, and post-doctoral researcher

Zdenek Travnicek found a novel way to col-

lapse the number of parameters needed to per-

form the optimization, streamlining the

approach significantly. Instead of 20 parame-

ters, she now works with a manageable six.Finding the optimal set of design parameters

for a MEMS-scale thermoacoustic refrigerator

is therefore much more straighforward, and

Prof. Herman predicts that commercially

viable models won’t be far behind.

Bubble Pumps

Professor Andrea Prosperetti has done the

engineering equivalent of pulling a rab-

bit out of a hat—by designing a pump with no

moving parts. These pumps are not likely to

take over municipal water delivery, however,

because they are about the same size as a

human hair. Prof. Prosperetti’s pump consists

of a channel about 100 to 200 microns in

diameter and several hundred microns long,

connecting two reservoirs of liquid. Within the

channel a single vapor bubble expands and

then collapses in response to a pulse of current.

In the process, liquid is displaced, moving

from one reservoir to the other. The entire

cycle is completed in a few milliseconds and

can be repeated hundreds of times a second.

This simple device is surprisingly powerful;

flow rates of hundreds of microliters perminute and pressure heads of several tenths of

atmospheres are easily achieved. Another way

to power these bubble pumps is by means of a

sound wave, which causes areas of relative low

and high pressure to form. A bubble will

change in volume, or oscillate, in response to

these pressure changes. When the bubble

vibrates like this, the fluid in the channel

moves. Prof. Prosperetti and his team are mod-

eling these kinds of bubble behaviors, as well

as experimenting with bubble pumps in the

laboratory.

Practical applications have started to mate-rialize, and many more appear possible. For

example: In the interest of eventually putting

humans in space, NASA might have a good

use for bubble pumps—growing food. If peo-

ple are going to spend much time in space,

says Prof. Prosperetti, they will need to eat

their spinach, and it will have to be grown in

space. Every pound that exits the Earth’s

atmosphere costs around $10,000, and every

drop of water in space will have to be recycled.

If the plants are grown hydroponically with a

legion of bubble pumps circulating the water

through their root zone, nutrients could be

delivered in an ultra-efficient manner with

minimal water inventory. Or, imagine a drug-delivery system that could be implanted under

the skin and deliver medication (such as

insulin) on demand via a pulse-driven bubble

pump. Or perhaps a bubble pump could be

activated automatically with a sensor that

would monitor the insulin level in the blood.

The use of an ultrasonic field—which propa-

gates harmlessly through living tissue—might

make it possible to power such devices remote-

ly with no need to undergo periodic operations

to replace implanted batteries, as for example

is currently the case with pacemakers.

Designer Materials

Back in the Middle Ages (and even earli-

er in China), weapons and tools were

made of iron; either wrought iron, which was

fairly soft and wouldn’t hold an edge for long,

or cast iron, which was extremely hard, unable

to deform, and would break quite easily.

Introducing a precise amount of carbon in the

smelting process produced steel, which com-

bined the useful qualities of wrought and cast

iron, making it infinitely more useful and

much more valuable.Materials science has come a long way since

the Middle Ages, but one thing remains the

same—as our technology improves we increase

our demands on structural materials, subject-

ing them to greater loads and more severe

environments. In the same way that steel was a

big improvement over iron, today’s metal

alloys are giving way to advanced materials

that can perform better under a variety of

demanding conditions, from outer space to

thousand-degree jet engines. Professor K.T.

Ramesh is the director of JHU’s new Center

for Advanced Metallic and Ceramic Systems(CAMCS), where faculty from Hopkins’

Mechanical Engineering and Materials Science

departments design, fabricate, and study state-

of-the-art materials for a variety of defense-

and industry-related applications.

An ideal material combines the best prop-

erties of metals and ceramics—the toughness,

electrical conductivity, and machinability of


6

Professor Andrea

Prosperetti has done

the engineering

equivalent of

pulling a rabbit out of a hat—by

designing a pump

with no moving

parts.



metals, and the low density, high strength,

high stiffness, and temperature resistance of

ceramics. Take away some of the brittleness of

ceramics and make strong metals lighter and

stiffer, and the material becomes really useful.

You’ve got a material that is hard but won’t

break; one that will conduct electricity but canwithstand high temperatures. These materials,

known as Metal Matrix Composites (MMCs) or

Ceramic Matrix Composites (CMCs) have

incredible promise in many engineering appli-

cations. Demand for such materials comes from

the automotive industry (lightweight and

strong materials would increase fuel efficiency

and last longer), electronics, telecommunica-

tions, and the aerospace and defense industries.

Such advanced materials can be “function-

ally graded” to provide the exact combination

of characteristics desired. Functionally Graded

Materials (FGMs) are materials or structures inwhich the material properties vary with loca-

tion in such a way as to optimize some func-

tion of the overall FGM. The matrix alloy (the

metal), the reinforcement material (the ceram-

ic), the volume, shape, and location of the rein-

forcement, and the fabrication method can all

be tailored to achieve particular desired proper-

ties. In MMCs, for example, ceramic reinforce-

ments in the form of either fibers, whiskers, or

particulates are introduced into the metal; the

structure is controlled at scales varying from

100 nm to several millimeters. The design of

FGMs requires an explicit understanding of the material behavior at each location and over

all these length scales.

However, the responses of such advanced

materials to dynamic and impact loadings

(severe mechanical environments) are generally

unknown. Prof. Ramesh runs the Laboratory

for Impact Dynamics and Rheology (LIDAR),

an offshoot lab of CAMCS, in which he sub-

jects these materials to impact loadings in an

effort to understand their mechanical proper-

ties under high strain rates. With ultra-high-

speed instrumentation, lasers, a dynamic tem-

perature sensing system, and a camera capable

of taking 100 million pictures per second,

Prof. Ramesh can characterize dynamic fracture

and failure processes in these materials. Using

the results of these experiments in combination

with finite-element models developed by Prof.

Molinari and scanning and transmission elec-

tron microscopy techniques developed by Prof.

Hemker, Prof. Ramesh hopes to be able to pin-

point how failure evolves in advanced materi-

als. Knowing exactly how a material will

behave under a certain kind of loading will

allow engineers to tailor the FGM precisely to

the kind of load or environment it will need to

withstand in service.

Making an Impact

Strain rate testing is a great concept

when the details of the impact, environ-

ment, or wear conditions are well-understood

and can be reproduced and modeled. But often

even getting that far stretches what we know.

Prof. Ramesh also uses the equipment in his

LIDAR laboratory to study impact dynamics—

the deformation, flow, and failure of materials

during the very first milliseconds of an impact

event.

Strain rates that occur during an impact

vary from as gentle as 10-5 per second to as

fierce as 10+8 per second, depending on the

event. A bat hitting a baseball is about 10+2 per

second. A projectile hitting a tank or a bullet

hitting a bulletproof vest is about 10+5 per sec-

ond. An extreme event like a micro-meteorite

hitting the space station, a meteorite hitting

the Earth, or a nuclear explosion would be

about 10+8 per second. As the impact event pro-

ceeds, the strain rate usually falls off quickly. A

meteorite travels at tens of thousands of miles

per hour; at the moment of impact, huge shock

waves are generated that propagate away fromthe impact site, generating most of the damage.

At the moment the shock wave arrives at your

location, the strain rate is about 10+8 per sec-

ond. After 10 microseconds, it’s decayed to 10+5

per second, and in a matter of milliseconds,

we’re back to baseball, at 10+2 per second.

Pressure during impact also varies dramati-

cally, going as high as 1 million atmospheres

in some events. Huge pressure changes like

this can do all sorts of interesting things to

materials. Glass is created at meteorite

impacts. Liquids can turn to solids because the

high pressures effectively lock the molecules inplace. Cracks that might have lurked in ceram-

ics are forced closed under high pressure, mak-

ing them stronger than before.

To test material behavior in the initial mil-

liseconds of an impact event, Prof. Ramesh

takes small pieces of a material and deforms

them very, very quickly. From measurements

taken during the test, he can predict what


7

…as our technology

improves we increase

our demands on

structural materi-

als, subjecting them

to greater loads and

more severe environ-

ments. In the same

way that steel was

a big improvement

over iron, today’s

metal alloys are

giving way to

advanced materials

that can performbetter under a vari-

ety of demanding

conditions, from

outer space to

thousand-degree

jet engines.



would happen in an actual event. If we under-

stand extreme events well enough, he argues,

perhaps we can make modifications to armor-

ing materials or somehow alter the impact

event in an effort to minimize damage. Perhaps

he will find an answer to the nagging question

that keeps some of us up late at night: Wouldit be better for us to get hit by a big meteorite,

or to break the meteorite up in space and get

hit by lots of little meteorites?

Foiled Again

T urn off the ovens. Put away the blow

torches. Save the Velcro for clothing acces-

sories. In 1994 Dr. Tim Weihs (now a professor

in JHU’s Materials Science and Engineering

Depart-ment) and Dr. Troy Barbee of Lawrence

Livermore National Laboratory made a ground-

breaking discovery that held the promise of

changing the way many materials are held

together. Components that are joined by sol-

dering or brazing in ovens or with blowtorches

can be damaged by heat exposure, and the

heating process also introduces oxygen, com-

promising the strength of the joint. Recent

advances in ceramic armor materials have seen

limited use because they have proven so diffi-

cult to attach to metal. Weihs and Barbee’s

invention, a thin sheet of foil made up of

nanoscale layers of alternating materials, makes

it possible to create ultra-strong bonds without

overheating components and without the pres-ence of oxygen.

Weihs and Barbee patented their invention

in 1996, and set to the lengthy task of making

these foils ready to manufacture. In this effort

they are joined by Professor Omar Knio, who

is spearheading the computational modeling

effort that will eventually lead to optimizing

the foil’s design.

Each layer in a multilayer foil is from 1 to

100 nanometers thick, alternating between a

light element such as aluminum and a transi-

tion metal such as nickel. The layers (about

1,000 of them) are deposited by magnetronsputtering to create a foil sheet about 10

microns thick (for reference, a human hair is

about 60 microns in diameter). Because nickel

would rather be bonded to aluminum than to

itself, according to Weihs, once a reaction is

started, say, with a spark or a match, a self-

propagating exothermic reaction begins and

speeds through the foil at about 5m/s. The

temperature goes from 25C to 1600C in about

10 milliseconds as the reaction front flashesthrough the foil. When sandwiched between

two components and two sheets of solder and

ignited, the foil melts the solder, joining the

materials together. Only the surface layer of

the material being joined is exposed to the

heat during the process, and this is the beauty

of the invention. Because the entire component

is not subjected to an external heat source dur-

ing bonding, the kinds of materials, solders,

and brazes that are used in manufacturing

processes can expand dramatically. Appli-

cations include soldering of temperature-

sensitive microelectronics and semiconductors,hermetic sealing, and metal-ceramic joining.

The trick is finding the right thickness and

composition for a given joining application.

The velocities, heats, and temperatures of the

reactions can be controlled by varying the

thicknesses of the alternating layers. A foil

with very thin layers, about 20-50 atoms

thick, will get very hot very fast, melting a lot

of braze or solder and creating an extremely

strong joint. But if the individual layers in the

foil are too thin, oscillations in the temperature

front can quench the reaction. Prof. Knio has

been numerically modeling the heat transfertaking place in the exothermic reaction, in

order to optimize the melting of solders while

at the same time minimizing the heating of

components. By combining numerical predic-

tions with experimental measurements of

mechanical properties, Prof. Knio plans to

develop software that can be used to determine

the combination of foils, brazes, solders, and

geometries that optimizes the joint shear

strength and interfacial fracture resistance.

Weihs and Knio have set up a company

called Reactive NanoTechnologies and are

working to commercialize the reactive foil

technology. The patents are rolling in. This

spring, they patented a method to manufacture

the foils and two foil structures.


8

Omar Knio

Professor

Ph.D. Mechanical Engineering, Massachusetts Institute of Technology, 1990

S.M. Mechanical Engineering, Massachusetts Institute of Technology, 1986

B.E. Mechanical Engineering, American University of Beirut,1984

Research Interests:

Computational fluid mechanics,vortex methods, turbulent reacting flows, acoustics



Sensors and Actuators

In the shrinking world of MEMS, devices get

smaller, better, cheaper, and more amazing

all the time. Improvements have been made in

materials, machining techniques, and testing

capabilities. But one important piece lags therest—the part of the device that acts as a trans-

ducer. In fact, according to Dean Ilene Busch-

Vishniac, in virtually all measurement and con-

trol systems the sensors and actuators account

for the bulk of the cost, the limitations on size,

and the majority of system failure situations.

Her recently pub-

lished book,

Electromechanical

Sensors and Actuators,

aims to remedy that

situation by taking a

novel approach to the theory and modeling of these devices.

A transducer, for the less mechanically-

minded, is a device that takes energy in one

form (mechanical, electrical, optical, magnetic,

chemical, or thermal) and converts it into

another form. A telephone has two transducers.

A microphone in the mouthpiece takes the

sound energy from your voice and translates

that into an electrical signal. The earpiece con-

verts the electrical signal coming down the

wire into a mechanical sound wave. Transducers

in a clothes dryer sense when the clothes are dry

and switch the dryer off automatically.Transducers are typically separated into sensors

and actuators: sensors monitor something about

a system, ideally without altering the system in

the process, and actuators impose a state on a

system. Typical actuators are motors, pumps,

and force heads. Sensors measure parameters

such as temperature, humidity, flow velocity,

pressure, or acceleration. Sensors and actuators

are often used together, as part of a measure-

ment and control system. Cars are full of them.

In a passenger side airbag, for example, there is

a tiny accelerometer that is connected to a

deployment mechanism for the airbag. If the

acceleration exceeds some threshold, then the

airbag is deployed. The thermostat in the

engine, the antilock brake system and keyless

door locks are all systems governed by sensors

and actuators.

To improve the performance of sensors and

actuators, argues Busch-Vishniac, we need to

revisit the way we think about them.

Traditionally, engineers study transducers by

categorizing them into what they do: temper-

ature sensors, accelerometers, motors, pumps,

and so on. She argues that it makes much moresense to look instead at the fundamental cou-

pling mechanisms that link the electrical and

mechanical domains, rather than at specific

sensors and actuators that are already in use.

She categorizes transducers by the material or

structural behavior that leads to transduction.

Often a single prin-

ciple can be applied

in many ways to

achieve various dif-

ferent sensing and

actuating outcomes.

Looking at just one of those outcomes, say,humidity sensing, limits the potential use of

the same mechanism for other applications.

Busch-Vishniac takes a “systems dynamics”

approach, centered around the energy in the

system and the parameters that can be varied

to translate that energy into different domains.

Instead of the traditional circuit models used

to describe energy flow through transducers,

she takes a unique modeling approach known

as Bond Graph Modeling. These bond graph

models don’t assume linearity, and they are

capable of describing causal relations as well as

conservation equations. Similarities and domi-nant effects stand out, and they give a powerful

visual picture of the way a system works, with-

out solving all the equations involved. Because

they can show causal relations, bond graph

models identify immediately the information

needed to create the system state equations

much more accurately than typical circuit

models.

The design of transducers hasn’t kept pace

with the incredible advances in electronics in

the past few decades, indicating that the cur-

rent approach is limited and needs reevalua-

tion. The demand for automated sensing

devices, and the increasing importance of elec-

tronic devices in our everyday lives, gives an

added impetus to the problem. Busch-

Vishniac’s book provides a much-needed fresh

look at the issue.


9

Ilene J. Busch-Vishniac

Professor and Dean,Whiting School of Engineering

Ph.D. Mechanical Engineering, Massachusetts

Institute of Technology, 1981

M.Sc. Mechanical Engineering, Massachusetts

Institute of Technology, 1978

B.S./B.A. Physics/ Mathematics, University of

Rochester, 1976

Research Interests:

Transduction applications in system dynamics and control

techniques for sensors andactuators

…in virtually all measurement and control sys-

tems the sensors and actuators account for the bulk

of the cost, the limitations on size, and the major-

ity of system failure situations.



Computational Modeling of

Complex Flows

Improvements in computing power and mod-

eling sophistication over the past 15–20

years have made it possible for scientists to sim-

ulate increasingly complex physical processes.This, in turn, makes it possible for engineers to

make significant progress in design. For exam-

ple, computational improvements have let to

advances in modeling of fluid flows, tradition-

ally a very important area of research at JHU.

Computational Fluid Dynamics (CFD) software

is used to model the complex, turbulent flows

encountered in IC engines, HVAC systems, fire

safety applications, aircraft aerodynamics, and

turbomachinery.

Computational fluid dynamics is typically

approached in two very different ways. In the

classical “top-down” approach, the field equa-tions governing macro-

scopic flow phenomena are

approximated by numeri-

cal techniques (like finite-

differencing or spectral

methods) that discretize

these continuum equations

in order to solve them on a

computer. The “bottom-

up” approach involves

solving Newtonian laws of

motion describing individ-

ual molecules and thenworking “upwards” to the

large scale flow, a tech-

nique known as Molecular

Dynamics. Although this

microscopic description is

technically the most accurate, it strains even

the fastest supercomputers. Models like this

can only handle very small systems (10 million

particles) and very short times (a few picosec-

onds). Professor Shiyi Chen, an expert in vari-

ous CFD methodologies who came to Johns

Hopkins from Los Alamos National Laboratory

in 1999, solves various fluid flow problems

using the Lattice Boltzmann Method (LBM), a

technique that occupies an intermediate

ground between typical “top-down” and “bot-

tom-up” methods.

The LBM is constructed as a simplified

kinetic molecular system in which single-parti-

cle distribution functions (i.e., very coarse his-

tograms of how often a particle has a certain

velocity) reside on discrete nodes of a lattice.

During each time step, the particles move to

the nearest lattice site along their direction of

motion, where they “collide” with other parti-

cles that arrive at the same site. Only a few

directions are allowed (e.g., up, down, left,

right). The outcome of the collision is deter-mined by solving the kinetic (Boltzmann)

equation, and a new particle distribution func-

tion is determined for that site. This simplified

molecular dynamics includes the essentials of

the underlying microscopic processes, and so

the averaged properties of LBM simulations

obey macroscopic continuum equations, in this

case, the classical Navier-Stokes equations. The

fact that equations at each lattice node can be

solved in parallel simplifies and speeds up

the computation significantly. And because

boundary conditions are imposed locally, lat-

tice methods are ideal for simulating flows incomplex geometry.

The data set that has

to be crunched by LBM

is impressively huge.

But instead of taking

the traditional approach

and farming the data off

to a supercomputer,

Prof. Chen has put

together a cluster of 64

networked PCs. This

exploits the inherently

parallel nature of theLBM technique by solv-

ing different parts of the

problem simultaneously

on different CPUs of the

cluster and then

reassembling them at various stages of the sim-

ulation, greatly reducing overall computing

time. This system is used as well by Professor

Joe Katz to analyze the huge amounts of data

he collects in his Particle Image Velocimetry

experiments (see Aerospace and Marine

Systems, page 15).

Professor Chen has used LBM techniques to

solve problems ranging from the flow of oil

and water through sandstone (oil extraction),

to flow over and around tires and automobiles

for industry partners, and the complex flow

patterns of granular materials, such as sand or

snow.

Turbulence is another example of an area in

which increased computer power translates

Computational Engineering

10

Shiyi Chen

Professor Joint appointment in Mathematical Sciences Department

Ph.D. Mechanics,

Peking University, 1987 M.S. Mechanics,Peking University, 1984

B.S. Mechanics,Zhejiang University, 1981

Research Interests:

Turbulence, computational fluid dynamics, latticeBoltzmann applications,molecular dynamics, flow in porous media.

The figures show the time evolution of the interface for the two-

dimensional Rayleigh-Taylor instability using the lattice

Boltzmann method developed by Professor Shiyi Chen and his

group.



11

directly into more complex and robust models.

Hopkins has a long and illustrious history of

turbulence research, including the work of

Professor Stanley Corrsin, who was one of the

first scientists to capture the dynamics of tur-

bulence experimentally in the wind tunnel he

built for that purpose. Professors CharlesMeneveau, Joe Katz, Shiyi Chen, and Omar

Knio are carrying on this tradition by con-

ducting experiments and testing theories that

may eventually give us a variety of reliable

ways to model turbulent flows.

In 1883, British physicist Osborne

Reynolds demonstrated that the transition

from laminar to turbulent flow in a pipe

depends on the ratio of inertial forces to vis-

cous forces in the flow, a non-dimensional

number now known as the Reynolds Number.

The higher the Reynolds Number, the more

complex the flow, and the more difficult it isto model. Realistic turbulent flows such as

those encountered in many engineering and

atmospheric applications have very high

Reynolds numbers, and several different

approaches are taken to try and quantify what

is happening in the flow.

In turbulent flow, large-scale structures

such as big vortices break down into smaller

and smaller eddies, eventually being diffused

by friction at the viscous scale. That range

spans many orders of magnitude (e.g., for flow

over aircraft fuselage, from tens of meters in

the wake to tens of micrometers and less in thethin boundary layers). To further complicate

matters, the equations governing turbulent

fluid flow have a “closure problem”—meaning

that the equations at a large scale contain

unknown contributions from the smaller scales,

which themselves are affected by even smaller

scales, and so on. In addition, unlike smooth

laminar flow, turbulent flow cannot be simpli-

fied by reducing the equations to two dimen-

sions, since the eddies are inherently three-

dimensional.

Direct Numerical Simulation (DNS) solves

the Navier-Stokes equations without averaging

any of the turbulent eddies. Professor Chen

uses spectral methods to discretize the equa-

tions and solves them on parallel computers.

DNS is limited to low and moderate Reynolds

number flows in which the ratio of viscous to

large-scale eddies is manageable, but it pro-

vides very detailed, three-dimensional and

time-dependent information about the funda-

mental structure of turbulence.

Large Eddy Simulation

One promising “top-down” approach to

predicting turbulent flows in a number

of engineering applications simplifies the com-

puting by separating the scales. Professor

Charles Meneveau is studying this particularapproach to modeling turbulence with a

method known as Large Eddy Simulation

(LES), in which the equations of motion are

solved explicitly for all scales larger than some

given threshold (the grid-scale). Motions

smaller than these (the sub-grid scales) are

parameterized by a set of models that depend

on various simplifying assumptions about the

small-scale dynamics. In contrast to other “top-

down” modeling approaches, such as Reynolds

averaging, LES does not rely on averaging all

the turbulent eddies but only the smaller ones,

thus making it capable of capturing muchmore accurately the dynamics taking place in

turbulence.

This method, while elegant in principle, is

inherently difficult because little is actually

known about the physics of the flow at the

small scales. Without good experimental data

to test different sub-grid-scale model possibili-

ties, their accuracy remains questionable. Prof.

Meneveau uses carefully controlled wind-tun-

nel experiments to test the assumptions and

models that determine how the small-scale

physics is represented in LES.

In a recent experiment, Prof. Meneveau andpostdoctoral scholar Hyung Suk Kang placed

an electrically heated metal cylinder horizon-

tally in the Corrsin Wind Tunnel. Downwind

of the hot cylinder, they placed an array of

probes that measured both velocity and tem-

perature. As the turbulent eddies that formed

in the wake of the cylinder became smaller and

smaller, the flow lost its structure, and the

velocity field became more and more random,

or isotropic (about equal in all directions). But

to their great interest, the statistical data they

gathered indicated that the temperature field

did not follow suit; rather, it retained some

sense of the larger-scale spatial orientation even

as it “cascaded” into smaller scales. This effect

had not been captured correctly with the sub-

grid scale models, which assumed that temper-

ature was also isotropic at the sub-grid scale.

For an in-depth look at some applications of

LES modeling to specific engineering problems,

see Energy and the Environment, page 21 and

Aerospace and Marine Systems, page 15.


In turbulent flow,

large-scale struc-

tures such as big

vortices break down

into smaller and smaller eddies, even-

tually being dif-

fused by friction at

the viscous scale.

That range spans

many orders of

magnitude (e.g., for

flow over aircraft fuselage, from tens

of meters in the

wake to tens of

micrometers and less

in the thin

boundary layers).



Solid Mechanics and

Understanding Failure

T he newest addition to the ME department,

Professor Jean-François Molinari, is inter-

ested in failure. Not failure of the personal

kind, assuredly, but failure analysis of solidsthat are subjected to a variety of stressful con-

ditions. Materials subjected to tremendous

pressure and highly repetitive activities, such

as human knee prostheses or high-speed manu-

facturing tools, exhibit wear and roughening,

eventually leading to failure. Satellites confront

micrometeorites traveling at speeds of about

4,000 m/s, and damage is inevitable and costly.

For such complex problems, in which material

deformation is very large, no closed form ana-

lytical solutions exist. It is often not practical

or even possible to subject an object to various

real-world fatigue-inducing conditions in thelaboratory. A solution

to this problem is

Computational

Mechanics. Prof.

Molinari is an expert in

using finite-element

computational meth-

ods to study different

kinds of material fail-

ure, including thermal

and mechanical

fatigue, large deforma-

tions, and wear.Ultimately, this kind

of modeling could lead to improved design

specifications for various engineering applica-

tions, by optimizing the overall structure and

the composite materials used.

In finite element analysis, the structure to

be modeled is subdivided into a finite set of

elements of simple shape, say, tetrahedra or

cubes. The mechanical, thermal, chemical, or

other properties are then approximated at a

finite number of nodes defining the elements.

Upon applying boundary conditions, mathe-

matical techniques are used to solve very large

systems of equations. For dynamic problems

the numerical time steps range from the order

of nanoseconds, for impact events, to seconds

or larger, for fatigue events. This means that

the equation solving needs to be repeated a

large number of times, and computational effi-

ciency is an important consideration. When a

large deformation occurs, the arrangement of

nodes and elements, referred to as the “mesh,”

becomes distorted. The way the mesh evolves

over time tells a “story” of the deformation and

the response of the material under scrutiny.

Prof. Molinari uses an adaptive mesh, which

adjusts itself when areas of significant deforma-

tion occur, preventing nodes from crossing overeach other and providing finer detail in areas of

interest. With the ability to pinpoint and

selectively analyze areas that are undergoing

relatively more change, the finite element

analysis combined with adaptive meshing opti-

mizes the computational resources.

Prof. Molinari uses this model to computa-

tionally test different kinds of composite mate-

rials, conditions, and geometries in an effort to

optimize design parameters. Coating turbine

blades with an extra layer of material, for

example, protects them from thermal fatigue

and wear. The interface characteristics (such asroughness) between the

substrate and the coating

layer can also be opti-

mized to achieve better

fatigue properties. This

kind of modeling effort is

particularly useful, since

by coupling mechanical,

thermal, and chemical

effects together—a “mul-

tiphysics” approach—

much can be learned

about the characteristicsand behavior of newly

designed composite materials before they are

used in any real applications. Likewise, those

interested in designing new materials and

structures can turn to these models to deter-

mine what kinds of chemical and mechanical

properties the material will need if it is to

withstand a particular environment.

Multi-phase Flow

W hen crude oil is pumped from the

ground, it enters a pipeline as a mix-ture of liquid oil and some water. As the liquid

moves along the pipeline, the pressure falls and

hydrocarbon gases (e.g., methane) originally

dissolved in the oil come out of solution, much

like opening a soft drink. The fluid being

pumped then becomes a mixture of gas and

liquid, which behaves very differently from liq-

uid alone. This is one of the many headaches


12

Jean-François Molinari

Assistant Professor

Ph.D., Aeronautics (minor Applied Mathematics),California Institute of Technology,2001

M.S., Aeronautics, California Institute of Technology, 1997

B.S., Mechanical Engineering,Universite de Technologie deCompiegne (France), 1997

Research Interests:

Computational Solid Mechanics, contact and wear,constitutive modeling, meshing techniques

Finite element Lagrangian analysis of shaped charges. The shaped charge technology is mainly used in the oil and gas industry.



13

that multiphase flows (i.e., flows in which

gases, liquids, and, in other cases, solids are

mixed together) present to the engineer.

Farther down the line in the oil refinery,

another important instance of multiphase flow

arises in the “crack-

ing” process, inwhich the long

chains of hydrocar-

bons that constitute

crude oil are broken

down into products such as gasoline, kerosene,

naptha, and household heating oil. Cracking is

accomplished by mixing oil vapor with catalyst

powder at very high temperatures. Any gain in

the efficiency of the cracking process would

have a tremendous impact in terms of reduced

pollution and enhanced productivity.

Oil refining is just one of many examples

of the many ways in which multi-phase flows affect technology and,

ultimately, our lives. Others

include agriculture (e.g., the flow

of grains in a silo), food process-

ing, combustion, and power gen-

eration.

In all these instances, the par-

ticles or bubbles traveling along

with the fluid complicate fluid

dynamics considerably—they

exert drag on the flow, change the

density of the medium, affect its

compressibility, and introduce all

sorts of complex flow structures

in their paths.

Current understanding of

these complex phenomena is not

well enough developed to permit the

reliable design of optimized indus-

trial systems. In the absence of a

robust theory, it is also difficult to rely on

experiment: if one runs tests on a small-scale

version of a plant, there is no way to know how

the full-scale system would behave.

In principle, since the laws of mechanicsare known, the equations describing each parti-

cle or bubble together with the motion of the

surrounding fluid could be solved—an

approach called Direct Numerical Simulation.

In practice, the amount of computational fire-

power necessary to tackle even relatively small

practical problems in this way is far beyond

what is feasible not only now but in the fore-

seeable future. Hence a “shortcut” must be

found, and this is a problem that has plagued

the field for decades.

Professor Andrea

Prosperetti has spentthe better part of the

past 20 years work-

ing on such

“reduced” approach-

es to multiphase flow, and his stature at the

front of the field is a tribute to his tenacity.

The challenge is to devise a formulation in

which the complex details of the actual flow

(e.g., what each particle does) are lumped

together in an average description of the sys-

tem. Many such approaches have been attempt-

ed over the years, mostly with disappointing

results. As long as the fluid con-tains only a few particles or bub-

bles, our intuition is sufficient to

develop a satisfactory formulation,

but when their density increases,

one is at a loss to capture the unex-

pected effects that arise. Prof.

Prosperetti’s approach consists in

trying to gain a physical under-

standing of what happens in these

situations by means of Direct

Numerical Simulation. He makes

the point that while, as mentioned

before, it is impossible to simulate

large realistic systems, much can be

learned by looking at small assem-

blies of, for example, 500 particles.

The task of building a “reduced”

formulation for multiphase flow is

therefore to take the computer output

of the DNS simulation, develop aver-

age laws that describe those results, and finally

come up with equations that govern this

“reduced” system. This is in some sense the

reverse of what is normally done: usually one

starts with the equations and ends up withnumbers by solving the equations on a com-

puter. Needless to say, this reversal of roles

makes things rather complicated and that ulti-

mate “high-tech” tool—mathematics—has to

be relied upon very heavily to carry out the

job.


In practice, the amount of computational firepower necessary to tackle even relatively small practical

problems in this way is far beyond what is feasi-

ble not only now but in the foreseeable future.

Andrea Prosperett

Charles A. Miller JrDistinguished Professor of Mechanical Engineering

Ph.D. Engineering ScienceCalifornia Institute of

Technology, 1974 M.S. Engineering Science,

California Institute ofTechnology, 1972

Laurea in Fisica,University di Milano, 1968

Research Interests:

Thermal-fluid mechanics ofmultiphase flows, underwater

acoustics, air entrainment,bubbles in liquids

Numerical simulations of the

flow through random arrange-

ments of spheres and correspon-

ding effective viscosities.



Invisible Turbomachinery

T he ME Department at JHU houses the

Axial Turbomachine Facility, a unique lab-

oratory funded by the Air Force and the Navy

that is used to study the flow in turboma-

chines. The term “turbomachine” refers to adevice that uses rotating elements to transfer

energy either to or from a continuously moving

fluid. Machines such as compressors and

pumps add energy

to the fluid,

increasing the

fluid pressure.

Gas, steam, or

hydraulic turbines

absorb energy

from the fluid,

generating power

in the process.Designing

highly efficient,

durable, and quiet

turbomachines is

one of the “holy

grails” of mechan-

ical engineering.

Better turboma-

chine technology would affect all of us, from

improvements in power generation to quieter

commercial airplane engines. But design tools

for turbomachines are far from optimized, due

to the complex fluid motion around the rotat-ing elements and the sheer numbers of ele-

ments in a typical turbomachine. A compressor

for a commercial jet engine has 37 blade rows,

each containing 30–100 blades, resulting in a

very complex machine with an impressive

50,000 pounds of thrust. In the turbulent

flows around the blades, secondary flow phe-

nomena such as wakes and trailing vortices,

and leakage adversely affect efficiency and per-

formance. Noise is also a big problem, from

suburban homeowners under commercial flight

paths to highly sensitive applications such as

pumps in the reactors that power submarines.

A better understanding of the fluid dynamics

within these turbomachines is therefore critical

to improving design parameters, and Professors

Joseph Katz and Charles Meneveau, with fund-

ing from the Air Force and the Navy (in sepa-

rate projects), employ novel flow visualization

techniques to gain insight into the nature of

the flow.

In a technique known as Particle Image

Velocimetry (PIV), a laser beam is expanded

into a thin sheet of light, illuminating a sec-

tion of the fluid, and a camera records a multi-

ple exposure image of the cloud of particles.

The displacement of particles between expo-

sures reveals the 2D instantaneous velocity dis-tribution. The problem with using this tech-

nique to study flow in turbomachines is that

the multiple blades limit access, both to the

laser and to the

camera. Prof. Katz

recently solved this

problem by using

acrylic blades and a

fluid that has the

same index of

refraction as the

blades, rendering

them invisible.This flow visualiza-

tion allowed them

to obtain, for the

first time ever, data

on the flow at any

point of the turbo-

machine.

Quiet, Please

T urbulence, interacting with solid bound-

aries, generates noise. Underwater, sound

is the only means of detection, and it propa-

gates very efficiently in water, so for sub-

marines, any source of noise is a huge problem.

Turbulence also causes structural vibrations

that generate additional noise. Engineers do

not have reliable tools to predict noise genera-

tion due to turbulence; most of what we know

is based on simplified formulations derived

from empirical relationships. Unlike other

applications of turbulent flow, studying noise

requires full characterization of turbulence near

the vicinity of the boundaries, precisely where

most simplified models break down. Because of

limitations in resolution, Direct NumericalSimulation, or DNS, (see Computational

Engineering, page 10), the only accurate

method available, cannot be used to compute

the full turbulent flow around bodies in the

foreseeable future. Consequently, the Navy has

invested substantial effort to develop approxi-

mate techniques for modeling the turbulence

and its dynamics in the vicinity of boundaries.

Aerospace and Marine Systems

14

Joseph Katz

Professor Whiting School Mechanical Engineering Chaired Professor

Ph.D. Mechanical Engineering, California

Institute of Technology, 1982 M.S. Mechanical Engineering,California Institute of Technology, 1978

B.S. Mechanical Engineering,Tel Aviv University, 1977

Research Interests:

Experimental fluid mechanics,bubble dynamics, cavitation,holography, PIV, naval hydrodynamics, oceaninstrumentation

Graduate student Yi-Chih Chow (left) and postdoc Oguz Uzol near the axial

turbomachinery facility—a joint project of Profs. Katz and Meneveau (funded

by AFOSR and ONR).



15

Large Eddy Simulation (LES) is one such

approach. In LES, the equations of motion are

solved explicitly for all scales larger than some

given threshold (the grid-scale). Motions

smaller than these (the sub-grid scale) are para-

meterized by a set of models that depend on

various simplifying assumptions about thesmall-scale dynamics. Profs. Meneveau and

Katz are conducting 2D and 3D flow visualiza-

tion experiments to modify and improve cur-

rent LES modeling techniques.

Typical LES models treat turbulence as

isotropic, meaning that statistical properties of

the flow are equal in all directions. In the

vicinity of a boundary, however, turbulence

undergoes rapid straining and rotation. This in

turn alters the physics of the turbulence, mak-

ing it anisotropic. To account for this, modifi-

cations must be made to the sub-grid scale

models used in LES. (See ComputationalEngineering, page 13, for details on LES

methodology.)

To create a 3D

velocity distribution of

the flow in the vicinity

of a boundary, Prof.

Katz draws upon his

experience in hologra-

phy. In the laboratory,

he “seeds” a turbulent

flow with particles, and

then records multiple-

exposure holograms.The holograms are

reconstructed and

scanned, and he obtains

the 3D velocity distribu-

tion from the displace-

ment of the particles. The data are then spa-

tially filtered, giving the filtered velocity field

and the subgrid stresses. This three-dimension-

al version of the Particle Image Velocimetry

technique (see Turbomachinery, above), known

as Holographic PIV, gives instantaneous vector

maps of 130 x 130 x 130 vectors—an unprece-

dented level of resolution. This highly resolved

data set is the only one of its kind in the

world, and promises to lead to very important

advances in our understanding of turbulence.

From the more practical viewpoint of the

Navy, someday this may help solve some seri-

ous underwater noise problems.

Profs. Katz and Meneveau have joined

forces with Professor Shiyi Chen to obtain a

second grant, this time from the NSF, to devel-

op a system that can generate instantaneous

vector maps of 500 x 500 x 500 vectors. This

research requires extensive (not to mention

expensive) new equipment and will take the

state of the art in flow visualization to a com-

pletely new level. Stay tuned!Underwater Robots for

Deep Ocean Exploration

Most of the world’s sea floor has never

been observed by human eyes. At pres-

ent, according to Professor Louis Whitcomb,

the surface of the moon has been mapped and

photographed more thoroughly than the sub-

merged portions of the Earth’s surface. Only a

few percent of the world’s seafloor is shallow

enough for direct examination by human scuba

divers. The problem is hydrostatic pressure.

Every 10 meters of depth adds another atmos-phere of pressure. In consequence, even mixed-

gas scuba divers can descend to only about 100

meters. Until recent-

ly, the only way for a

scientist to directly

examine the benthic

floor was to descend

in a specially

designed deep-diving

submarine. The deep-

est diving U.S. inhab-

ited submarine, the

DSRV Alvin, can

descend to 4,500

meters depth, yet this

is less than half-way

to the ocean’s deepest

depth of 11,000

meters. By comparison, Mount Everest is only

8,848 meters in height. To reach these great

depths, Prof. Whitcomb and researchers around

the world have developed underwater robotic

vehicles that enable scientists to explore, by

remote control, these deepest and most inacces-

sible parts of the ocean.Whitcomb and his students have conducted

original research on the navigation and control

systems for these underwater “Remotely

Operated Vehicles” (ROVs) for over a decade.

They collaborate closely with researchers at the

Woods Hole Oceanographic Institution

(WHOI), where most of the U.S. deep-submer-

gence oceanographic vehicles are developed and


Former graduate student Ralph Bachmeier looking at propeller in a

marine system.

Louis L. Whitcomb

Associate Professor

Ph.D. Electrical EngineeringYale university, 1992

M.Phil. Electrical Engineering, Yale University

1990

M.S. Electrical Engineering,Yale University, 1988

B.S. Mechanical EngineeringYale University, 1984

Research Interests:

Adaptive control of robot sys-tems for real-world applications



operated. Whitcomb is co-developer of the nav-

igation and control system for the Jason ROV,

the deepest diving U.S. ROV presently in oper-

ation. He and his students participate frequent-

ly in deep-ocean deployments to experimental-

ly evaluate their newly developed systems. In

June 1999, for example, Whitcomb and hisPh.D. student David Smallwood tested out a

new Doppler-based sonar navigation system

with their WHOI collaborators in the

Mediterranean Sea between Malta and Israel.

This expedition was led by leading geologist

and oceanographic explorer Dr. Robert Ballard,

and Harvard University archaeologist Dr.

Lawrence Stager. On this expedition, equipped

with video and still cameras, sonar devices, and

a robotic arm, Jason photographed and explored

the topography of several pre-Roman ship-

wrecks, sending the data to a ship on the sur-

face via a fiber-optic cable. The artifacts docu-mented and recovered for the archaeologists by

the Jason team dated from about 750 BC, and

they reveal clues about trading routes, econom-

ic and political alliances, and lifestyles in

ancient cultures. Before the development of

vehicles like Jason, it was infeasible to explore

shipwrecks deeper than the scuba divers’ limit.

An invaluable museum of human history lies

waiting on the 97% of the ocean floor that

remains unexplored.

Back at Hopkins Prof. Whitcomb and his

PhD students built and, in August 2000,

launched their own ROV, the JHU ROV. They

have tested it in the United States Naval

Academy’s 380-foot

test basin. Whitcomb

and his students use

data they gather dur-

ing these tests to

develop accurate mathematical models of the

vehicle’s dynamics, which in turn allows them

to design improved control systems. They also

use this ROV to field-test new designs. Once

these designs are validated by field-testing,

Prof. Whitcomb’s group can quickly transition

them for use on other vehicles.

In June 2001, Prof. Whitcomb and his stu-

dent James Kinsey again went to sea to test

their newly developed sonar navigation system

called DVL NAV aboard the new WHOI vehi-

cle DSL120A. Whitcomb and his students

developed the new navigation system on the

JHU ROV, and have successfully deployed it

on the new DSL120A vehicle and the inhabit-

ed submersible Alvin.

Whitcomb and his students are now col-

laborating with WHOI to help develop

JASON II, a new vehicle designed to succeed

Jason. It is “bigger, stronger, faster,” according

to Prof. Whitcomb, and will have more sophis-

ticated systems on board, including the naviga-tion systems now being tested. Jason II can

help unveil the mysteries of unique life forms,

hydrothermal vents, and other natural phe-

nomena of the deep. Prof. Whitcomb, by

designing Jason II’s “brains,” has an important

role to play in this exciting future of deep sea

exploration.

Cavitation

Cav.i.ta.tion \ kav’ i ta’ shun \ n [1. the

rapid formation and collapse of vapor

pockets in a flowing liquid in regions of very

low pressure. 2. such a pocket formed.](Webster). Like any little boy with a penchant

for watching things explode, Professor Joe

Katz has had a lifelong fascination with the

problem of cavitation.

In a water environment, cavitation occurs

when the pressure in a certain region falls

below the vapor pressure of the surrounding

water, causing the sudden creation of a cavity

of gas that then rapidly and explosively col-

lapses. Situations like this occur around pro-

peller blades, around hydro-turbine blades in

hydroelectric power generation, and in pumps.

The result is a very noisy, very destructive

event. The Glen Canyon Dam had to be shut

down after only 15

years of operation

because cavitation

events from the tur-

bine blades ate

through a three-foot wall of concrete. The

noisy belch of a cavitation event around a ship

propeller can be heard underwater from 70 to

100 miles away; an inconvenient “here I am”

announcement for naval vessels that prefer to

roam silently.Probably the most dramatic example of

cavitation occurs in the oxidizer fuel pump in

the space shuttle’s main engine, which operates

at about 80,000 HP (for comparison, a trac-

tor-trailer is about 500 HP) with a 14-inch

impeller. During the space shuttle’s design

phase in the 1970s, instabilities caused by cav-

itation in this pump caused repeated engine


16

The Glen Canyon Dam had to be shut down

after only 15 years of operation because cavita-

tion events from the turbine blades ate through

a three-foot wall of concrete.

Jason II can help

unveil the mysteries

of unique life forms,

hydrothermal vents,

and other natural phenomena of the

deep.



17

blowup. Even now, cavitation-related instabili-

ties in liquid fuel rocket pumps are a major

problem, and cavitation control is a primary

design factor in these engines.

Because situations that lead to cavitation

involve turbulent flow and a very rapid phase

change—on the order of microseconds—the

phenomenon has proved very difficult to study

in the laboratory, and, as a result, difficult to

model. Profs. Katz and Knio and their team go

“small-scale” to tackle this problem. They sim-

ulate real cavitation situations by creating care-

fully controlled flow conditions in JHU’s

experimental fluid dynamics laboratory. They

study the cavitation phenomenon, as well as

the flow that caused the cavitation, in detail at

very high magnification using microscopy, PIV

techniques (see Turbomachinery, above), high-

speed photography (up to 3,000 frames per

second), and noise and pressure measurements.Data obtained from these explorations of the

relationship between flow structure and cavita-

tion may someday allow engineers to develop a

way to control the phenomenon.

Laboratory Robots

In the basement of Latrobe Hall “lives” a

mechanical arm that, purely through pneu-

matic on/off switches operating pistons on a

series of joints, can maneuver a tool into any

pre-programmed position. An algorithm trans-

lates the user’s input of a spatial coordinate

into a series of on/off switches for the pistons

on the arm that take it to that coordinate. This

“superarm,” designed by Professor Gregory

Chirikjian, can perform highly repetitive tasks

efficiently and cheaply, even fairly complicated

ones involving a series of movements, such as

placing parts in an assembly line.

For situations in which the motion desired

by the robot cannot be programmed ahead of

time, engineers depend on motors that can

provide as many degrees of freedom as possible.

One degree of freedom means that the motorcan move, say, up and down; two degrees

means that it can go up and down and side to

side, and so on. In each joint of a robotic arm

there is a motor, and the more degrees of free-

dom that motor has, the more general its

movement can be. Consider the amazing appa-

ratus that is our shoulder joint —its range of

motion is phenomenal. Attach it to the highly

articulated elbow and wrist joints, and the

human hand becomes a truly miraculous tool,

able to reach with ease in any place or any

direction. Engineers have good reason to want

to mimic this range of motion robotically. Theclosest they have come is the “spherical” motor,

a motor that can rotate in a sphere around any

axis. Prof. Chirikjian and his student David

Stein have recently built a spherical stepper

motor. The moving portion of the motor is a

hollow plastic sphere in which magnets have

been placed in a regular pattern. This sphere is

placed in a cap containing several soft iron

cores that are polarized to form a magnetic

field. The whole arrangement looks a bit like

an egg (albeit a spherical egg) in an egg cup. A

current is run through the coils in the cap,

changing the magnetic field, and the plastic

sphere moves in response. Although

Chirikjian’s group is one of many working on

the design of a spherical motor, theirs has dis-

tinct advantages. In most current spherical

motors, the “egg-cup” part of the motor has to

envelop the rotor, whereas Chirikjian’s cap is

less than a hemisphere and thus provides a

greater degree of freedom of movement.

Robotics and Human-Machine Interaction

Rotor for a spherical motor

Stator for a spherical motor

Gregory S. Chirikjian

Professor Joint Appointment, Computer

Science

Ph.D. Applied Mechanics,California institure of

Technology, 1992 M.S.E

Mechanical Engineering,The Johns Hopkins University,

1988

B.S. Engineering Mechanics,The Johns Hopkins University,

1988

B.A. MathematicsThe Johns Hopkins University,

1988

Research Interests:

Robotics, mechanical design,applications of group theory in

engineering, dynamics ofbiological macromolecules



Spherical motors would fill engineering

needs in many important applications. Robotic

wrist, elbow, and shoulder actuators might be

used in small spaces where a human arm would

not fit, such as in surgical procedures, or in

uninhabitable environments. For a computer to

“see,” a camera (its “eye”) would have to oper-ate like our eyes, smoothly tracking an object

as it moves within the field of vision. A roam-

ing robot with three spherical-motor wheels

under it becomes “omni-directional.” An

object placed on a platform made up of an

array of spherical motors could move smoothly

in any direction.

Haptic Happiness

Needle insertion is a challenging task,

especially in areas with little room for

error. Brachy-therapy for prostate cancer, for

example, is the localized placement of sealedradioactive sources (seeds) using 6-inch long,

18-gauge needles. The target area for seed

delivery is a small volume (40-50 ccs) with

limited access and through a small cross-sec-

tional area of the perineum. At least 20 needles

must be inserted to place anywhere from 80 to

150 seeds. These constraints make the proce-

dure very difficult to perform. To practice,

physicians use “phantoms,” or non-biological

substitutes for human flesh and bone. Even the

best phantoms, however, can-

not come close to the com-

plexity of textures and the

individual variability of true

human anatomy.

Alternatively, some surgeons

are turning to virtual envi-

ronment training tools to

practice their technique. One

of these, which trains sur-

geons for endoscopic sinus

surgery, uses a virtual envi-

ronment created from MRI images. But

because these images are limited to data about

shape, not stiffness or texture, doctors are notsatisfied with it, insisting that it does not

“feel” realistic.

Professor Allison Okamura envisions

another approach, one in which a robot plays

an important role. Okamura is an expert in

robotic haptic exploration. When we touch

something, we have a “haptic” experience of

that object that includes sensations such as tex-

ture, hardness/softness, weight, temperature,

and shape. Scientists know very little of how

the brain processes sensory experiences, partic-

ularly haptic ones, and so it is impossible at

this point to recreate a true haptic experience

in virtual reality. But Prof. Okamura is tack-

ling the problem one step at a time, using sim-ple robotic systems and complex models.

Eventually, she hopes to help build a virtual

reality environment that can give feedback on

many of the important pieces of a haptic expe-

rience, making virtual reality “feel real.”

The model she is developing must translate

data that a robot takes from a real environment

into a motor-driven combination of accelera-

tion, force, and position that will be delivered

to a human hand on the other end of a stylus,

thereby allowing the human to “feel” the envi-

ronment that the robot does. Prof. Okamura’s

masters’ student, Christina Simone, is current-ly working on a needle insertion system in

which a robot performs many real needle inser-

tions in various organs, all the while recording

data on force, acceleration, and position.

Once the haptic experience of poking is

fully modeled, she can move her robot on to

using scissor-like tools, exploring the forces

involved in grasping and cutting. Eventually,

these individual haptic experiences can be

woven together to form a modeled “reality”

that feels more like the real thing.

The data collected in Okamura’s

research could find use in variousapplications such as training simula-

tions, telerobotics, and cooperative

(assistive) robots. In robotic proce-

dures, data coming in real time

could be compared to some idealized

model and used to give the doctor

feedback on his/her performance. In

addition, feedback from real needle

insertions could also be compared

with data collected from phantoms

and used to improve the materials that make

up phantoms, making them more realistic. The

possibility exists, notes Okamura, for

autonomous robotic procedures, where the

robot does an entire procedure on its own,

although she believes that these are many years

away.


18

Allison Okamura

Assistant Professor

Ph.D., Mechanical Engineering Stanford University, 2000

M.S., Mechanical Engineering Stanford University,1996

B.S., Mechanical Engineering University of California at Berkeley, 1994

Research Interests:

haptic exploration with robotic fingers, vibration and force feedback in virtual environments, and assistiverobotics

Haptic Forceps/Scissors



19

The Microsurgical Assistant

Humans possess an extraordinary tactile

dexterity, yet we are designed to manip-

ulate tools and perform tasks on the scale of

our own bodies. Microsurgical operations

require exquisite dexterity, yet even the steadi-est-handed doctor still has an imperceptible

hand tremor, on the order of tens of microns.

Moreover, humans cannot accurately gauge tac-

tile forces less than a few grams. These limits

on human tactile performance directly deter-

mine the feasible limits of microsurgical proce-

dures. Recently, researchers from the JHU

School of Engineering and the JHU Medical

School collaborated to develop a novel robot to

enhance a surgeon’s tactile performance. This

new robot, called the “Steady Hand Robot,”

extends a surgeon’s ability to perform small-

scale manipulation tasks—especially tasksrequiring human judgment, sensory integra-

tion and eye-hand coordination.

In the steady hand system, the surgical tool

is held simultaneously by the surgeon’s hand

and a robotic arm. The robotic arm has a con-

troller that senses the forces exerted by the

human hand on the tool, and by the tool on

the environment. It can then scale down the

force of the surgeon’s hand to provide precise,

delicate movements that are virtually tremor-

free. It also amplifies minute tool-tip forces to

the surgeon’s hand, thus “amplifying” the sur-

geon’s sense of touch. Professor Whitcomb andhis students have developed novel control algo-

rithms for this robot. A prototype of the

steady-hand system was developed with

Professor Russell Taylor of the Department of

Computer Science and Eugene deJuan, MD of

the JHU Wilmer Eye Institute. They are

presently experimentally evaluating the sys-

tem’s performance in collaboration with Daniel

Rothbaum, MD, and John K. NiParko, MD,

from JHU’s Department of Otolaryngology.

One form of hearing loss, otosclerosis, is

caused by the immobilization of the stapes

bone in the middle ear. A surgical procedure to

correct it, stapedotomy, involves removing a

portion of the stapes bone, drilling a tiny hole

in the piece that’s left, and connecting a little

piston-like prosthesis to another bone in themiddle ear with a wire crimp. With the pros-

thesis in place, sound vibrations can propagate

through to the inner ear, restoring hearing.

To perform this procedure with a steady-

hand robot, the surgeon holds a stylus,

attached to the robotic arm, with a surgical

tool at the tip. The robot operates under a

“proportional velocity” control during the

crimping procedure, in which virtually no

tremor propagates to the instrument tip. Users

feel that their hands are “steadied”. In “force-

control” mode, used in the drilling procedure,

small contact forces between the instrumentand the user feel amplified, allowing the sur-

geon to exert tiny forces that would otherwise

be below the threshold of human tactile sensa-

tion. Using a full-scale instrumented model of

the human ear, the Hopkins researchers are

comparing assisted and unassisted outcomes of

the drilling and crimping procedures.

The development of the Steady Hand

Robot holds enormous promise. From delicate

surgical procedures like stapedotomy to the

injection of stem cells into the cochlea, which

cannot be done manually, to directly breaking

up blood clots in veins or arteries, it may wellfundamentally change what is considered pos-

sible in medicine. Surgical robots may change

medicine in a manner similar to the way that

the development of the integrated circuit revo-

lutionized information processing in the 20th

century. This work done by Hopkins

researchers is an example of successful interdis-

ciplinary and interdepartmental work that taps

into the extraordinary skills of all the

researchers involved.


3-degree-of-freedom haptic interface

From delicate surgi-

cal procedures like

stapedotomy to the

injection of stem

cells into thecochlea, which

cannot be done

manually, to

directly breaking up

blood clots in veins

or arteries, it may

well fundamentally

change what is

considered possible

in medicine.



21

vast clouds, consume all the food in the area,

and then disappear, and researchers have no

good explanation for why these creatures appear

to simply eat themselves out of existence. Some

plankton luminesce in

response to shear, caus-

ing problems for theNavy, since this lumi-

nescence effectively

announces the presence

of a submarine to any-

one in the vicinity or to

satellites.

Professor Joe Katz is

studying plankton with

Dr. Edith Widder, a

world expert in biolumi-

nescence from the

Harbor Branch Oceanographic Institute, and

postdoctoral researcher Dr. Ed Mekiel. In a div-ing expedition off the Gulf of Maine, they col-

lected data on plankton with a submersible

holographic camera that records

in situ holograms of sample

volumes of ocean water. When

reconstructed, these holograms

create a 3D image of the origi-

nal sample volume that can be

examined in the laboratory.

They scan the volume with a

microscope to a resolution of

3–10 microns, revealing a

three-dimensional picture of the various species of plankton

and their distribution in space.

These multi-exposure holo-

grams are used for measuring

the flow and reveal a story of

the plankton’s behavior over

time, providing a unique window on the inter-

action between plankton species and the condi-

tions under which they tend to gather or to

luminesce.

Atmospheric Turbulence

Heightened interest in the transport and

fate of atmospheric pollutants and the

impact of turbulent dynamics on large-scale

climatic flow patterns have made atmospheric

turbulence an increasingly important area of

research. Large Eddy Simulation (see computa-

tional engineering) has emerged as one of the

best ways to model atmospheric turbulence,

because the huge Reynolds Numbers in atmos-

pheric flow and the size of the physical domain

preclude the use of direct numerical methods.

In Large Eddy Simulation (LES), the equa-

tions of motion are

solved explicitly for all

scales larger than somegiven threshold (the

grid-scale) and motions

smaller than these (the

sub-grid scale) are

parameterized by a set

of models that depend

on various simplifying

assumptions about the

small-scale dynamics.

Current atmospheric

LES suffers from a lack

of experimental data on the finer scale physics

of atmospheric dynamics. Professors CharlesMeneveau and Marc Parlange (of JHU’s

Department of Geography and Environmental

Engineering) are not comfort-

able with the assumptions

made by many of the current

sub-grid scale models.

In a venue far removed from

the carefully controlled

wind and water tunnel laborato-

ries, Professors Parlange and

Meneveau have done

several groundbreaking experi-

ments that record turbulentvelocity, temperature and

humidity data in the atmos-

pheric surface layer over large

fields. In a succession of field

campaigns in Iowa and

California, fine-scale measure-

ments were made over the past three summers

using arrays of vertically and horizontally

arranged anemometers. This has allowed them

to explore properties of the sub-grid scale mod-

els, for the first time based directly on field

experimental data. In addition, they have devel-

oped several new modeling approaches based on

the insights gained from these experiments.

Bubbles in Space

W hen microelectronic components heat

up, cycling fluid around them is a great

way to cool them off (see Micro-cool, in

Micro/nanoscale Science and Engineering, page

Photograph and schematic of array of sonic

anemometers during a c ollaborative field experi-

ment between NCAR and JHU, Kettleman

City, CA, summer 2000 (Funded by NSF).

Energy and the Environment

Holography system mounted on manned submersible. The system

allows recording holograms of ocean plankton in situ. Top left: a

copepod captured in a hologram. Bottom right: 30 velocity

distribution (funded by NSF).

Charles meneveau

Professor

Ph.D. Mechanical Engineering, Yale University

1989

M. Phil. Mechanical Engineering, Yale University

1988

M.Sc. Mechanical Engineering, Yale University

1987

B.S. Mechanical EngineeringUniv. Técnica F.S.M

Valparaíso, Chile, 1985

Research Interests:

Theoretical, experimental, and

numerical studies in turbu-lence. Large-eddy-Simulationand modeling, fractals



5). To provide even more cooling, engineers

exploit the large amounts of energy consumed

in boiling. So much energy is required to break

the bonds and rearrange the atoms from the

liquid to the gaseous phase that even when

energy continues to be added to the system, the

temperature of the liquid stays constant. Andbecause gas is less dense than liquid, the bub-

bles move away from the hot surface, cooling it.

Engineers routinely use boiling to cool

equipment. But boiling only cools things when

the buoyant bubbles leave the hot surface. As

any hurried cook knows, putting an empty pot

to boil ruins the pot. In a micro-gravity envi-

ronment, bubbles don’t rise—the gas created

by boiling remains trapped next to the hot sur-

face, which often does not

get cooled well. In order

to use boiling in space,

engineers must findanother way to move the

bubbles. Prof. Cila

Herman is pioneering one

interesting possibility—

using electric fields. She

and post-doctoral

researcher Estelle Iacona

and visiting scholar

István Földes modeled the

fundamentals of this bub-

ble formation problem

and have begun testing

their theory experimental-ly. As a first step, they are

working with electric

fields in the laboratory,

looking at the behavior of single isothermal

bubbles.

The next step is to see how electric fields

affect bubble behavior in micro-gravity condi-

tions. With funding from NASA, Prof.

Herman conducted her experiments on a plane

officially nicknamed the “Weightless Wonder”

and fondly known by researchers as the “Vomit

Comet.”

Early in the morning of one of these para-

bolic flights, a number of scientists (there are

several experiments on each flight), a doctor

and the NASA support crew climb aboard the

KC135 military aircraft—the same one that

was used to film “Apollo 13.” They are strong-

ly encouraged to refrain from eating breakfast.

The airborne plane goes into a series of steep

rises and falls—25 seconds of microgravity

while it heads up, and then—“feet down, com-

ing around” —25 seconds of 2G while it

plunges back down the parabola. Over the

course of the 2 hour flight, this is repeated 40

to 60 times. During those 25 seconds of micro-

gravity, the scientists have to concentrate on

getting good data. During the transition, it’simportant to be upright and away from the

equipment, since falling on one’s head or get-

ting bonked by something at 2G can be very

painful. During the 25 seconds of 2G,

researchers have to hustle their suddenly

extremely cumbersome arms, legs, and hands

to get the setup ready for the next “take.” Just

reaching over and operating a valve is a huge

effort under these conditions. To make things

worse, almost everyone

gets nauseous. It’s a

shame to waste valuable

research time throwing up(special bags for that pur-

pose are stacked into

pockets of the flight suit

at the beginning of the

flight and regularly col-

lected by the NASA

crew), but sometimes it

can’t be helped. Prof.

Herman was proud to

report that she never suc-

cumbed. She was also

impressed by Math

Sciences Prof. and ChairEd Scheinerman who

managed to eat breakfast

before a flight with no ill

effects.

In 1999–2000, Prof. Herman went on

three parabolic flights, accompanied at various

times by graduate student Gorkem Suner, once

by Prof. Scheinerman, and once by graduate

student Steven Marra. Data collected from

these experiments in micro-gravity indicate

that an increased electric field causes the bub-

ble to elongate and move away from the sur-

face, bearing out their predictions. The

remaining task is to digitally analyze the data

to calculate the force components involved. At

the moment, they are running more experi-

ments back on the ground, and tentatively

scheduled to fly an experiment in conjunction

with a team from NASA on the space station

in 2004.

22

Detailed high-speed photography of the coalesc ence and bubble growth processes during microgravity. Top photograph shows

Prof. Herman with graduate students aboard NASA’s

“Weightless Wonder.”

Energy and the Environment

Cila herman

Associate Professor

Dr.-Ing. Mechanical Engineering, Technical University of Munich and University of Hannover,

Germany, 1992 M.S. Control Engineering,University of Novi Sad,Yugoslavia, 1998

B.S. Electrical Engineering,University of Novi Sad,Yugoslavia, 1982

Research Interests:

Experimental heat transfer and fluid flow, heat transfer augmentation, thermoacoustics,

optical techniques



23

Put Your Heart Into It

F rom an engineering standpoint, a person

with a “good heart” possesses an organ

that can produce a 60% change in volume as it

contracts. Very little is actually known about

the mechanical properties of the human heart.For Professor Jean-François Molinari, an object

undergoing a large deformation like this is a

perfect opportunity to apply constitutive mod-

eling techniques. Not only is it a “multi-

physics” problem, involving

chemistry, biology, and

mechanics, but it is also an

optimization problem.

What is the ideal shape of

the heart? What is the ideal

orientation pattern for the

muscle fibers as they con-

tract in response to an elec-trical pulse? Surgeons cur-

rently operate on patients

with “poor hearts” (<30%

volume change on contrac-

tion) by altering the organ

from a roundish shape to a

football shape. The surgery

is highly empirical, and it

is probable that finite ele-

ment modeling can be used

to optimize the procedure.

Prof. Molinari is enthusiastic about the possi-

bility of interacting with JHU’s BiomedicalEngineering Department to apply his expertise

in constitutive modeling to biomechanical

problems.

Mimicking Mother Nature

It’s doubtful whether the little creatures that

inhabit seashells can fully appreciate the

amazing structures in which they live. But

engineers and materials scientists certainly do.

Seashells are incredibly hard and strong, yet

amazingly lightweight. Materials scientists

would dearly love to have the cosmic recipe formaking this kind of material, along with blue-

prints for other nifty things like tooth enamel,

cartilage, and muscle. Materials like this could

be used in countless ways; the market possibil-

ities are huge. The fact that it took billions of

years for these things to evolve doesn’t faze

engineers—they hope to be able to come up

with workable copies in a matter of decades.

Professor K.T. Ramesh and Associate Dean

Andrew Douglas form the faculty core of

JHU’s Laboratory for Active Materials and

Biomimetics (LAMB), JHU’s contribution to

this effort. They characterize the mechanical

and electromechanical properties of natural

materials as well as active materials that aresupposed to mimic nature. They also generate

active materials though tissue engineering.

Prof. Ramesh explains that there are two

basic approaches to biomimetics: in the first,

the researcher takes a mate-

rial concept from nature,

like the material of a

seashell or the fibrous mus-

cles of the heart, and uses

that concept in an artificial

system. The second

approach looks at the func-

tional concept in nature, inan attempt to isolate the

mechanisms responsible for

the unique way a certain

material works. To under-

stand muscle material, for

example, researchers look at

how muscle fibers undergo

a complicated dance of con-

tracting and swelling in

preferred directions through

the diffusion of calcium.

Because muscle itself is highly variable from

one person to the next and from one part of thebody to another, this involves huge numbers of

experiments on muscle tissue and extensive

data mining. The functional approach preferred

by Profs. Ramesh and Douglas instead centers

around an artificial analogy based on the mech-

anism occurring in muscle tissue. They build a

mathematical model that mimics the mathe-

matics of the natural phenomena they wish to

understand, and then work their way back-

wards through various artificial models until

they are at a point where they can consider the

actual biological processes taking place.

Prof. Douglas collaborates with Professor

Bill Hunter and his former PhD student John

Criscione of JHU’s Biomedical Engineering

Department, using experimental materials to

refine their mathematical models of muscle

function. The mathematical description first

isolates important mechanical concepts such as

strain, activation, and time dependency. How

much internal force (or stress) causes muscle

Mechanical Engineering in Biology and Medicine

Andrew S. Douglas

Professor and Associate Dean for Academic Affairs, Whiting

School of Engineering Joint Appointment,

Biomedical Engineering

Ph.D. Engineering MechanicsBrown University, 1982

Sc.M. Engineering Mechanics,Brown University, 1979

M.Sc. Civil Engineering,University of Cape Town,

1977

B.Sc. Civil Engineering,University of Cape Town,

1975

Research Interests:

Soft tissue mechanics, activematerials, fracture



24

fibers to move, and how does their movement

evolve over time? Like rubber bands, muscle

fibers elongate, and strain is a measure of their

elongation per unit length. But while rubber

bands double their length or more when

pulled, muscle fibers only elongate up to about

25% and can also contract when activated.While muscles are activated by the concentra-

tion of calcium ions, the artificial materials

used in the LAMB lab are complex polymers

that respond to a change in pH of the environ-

ment. They have been able to mimic the defor-

mation characteristics of smooth muscle fibers

isotropically, that is, swelling and contracting

with strains between

2% and 25%, in all

directions evenly.

The next step,

according to

Douglas, is to makethe material work in

a preferred direction,

as muscle tissue does.

Pain in the

Knee

Occasionally, we

think nature

could do better. It

would be nice if we

had a limitless tooth

supply, like sharks.

And the fact that car-

tilage does not regen-

erate itself is a very

real pain, especially

in joints like the knee. Cartilage is formed

when a special bunch of cells, called chondro-

cytes, excrete an extracellular matrix contain-

ing collagen (among other things). This matrix

provides the unique mechanical and lubricat-

ing conditions we need in our joints. In

healthy tissue, the chondrocytes keep churning

out the extracellular matrix as needed, and we

move about without giving it a thought. Butlose those chondrocytes to a disease like arthri-

tis, and it’s curtains for your cartilage. They

don’t regenerate. Even the best polymer

replacements degrade over time and have to be

replaced every two years or so.

Prof. Ramesh is working with Dr.

Carmelita Frondoza, a cell biologist in the

Department of Orthopedics at JHU’s School of

Medicine, on a different approach; using har-

vested chondrocytes to create living tissue that

can replace cartilage. Unfortunately, this is

anything but straightforward. The type of col-

lagen matrix excreted by the chondrocytes

depends on whether they receive the correct

mechanical stimulation. Inside the body, thecells experience a mechanical load and generate

the right kind of collagen. Outside the body, if

the cells experience no load, the matrix pro-

duced is stiff and inflexible, resembling scar

tissue instead of cartilage. Theory holds that

these cells have little “receptors” that sense

load/deformation changes, and in response, the

cell produces a cer-

tain type of colla-

gen. Create a

mechanical load on

the harvested cells,

and they mightexcrete the right

kind of collagen.

But what kind of

load? And is it the

load itself or merely

the deformation

caused by the load

that causes the cells

to do what they do?

If they could figure

out the kind of

mechanical envi-

ronment the cellswant to “see,” says

Prof. Ramesh, then

they could optimize

the engineering of replacement cartilage.

To explore this, Prof. Ramesh takes living

cells and places them in artificial “scaffolds”

made out of an inactive polymer. Then he sub-

jects the whole scaffold to various loads or

deformations. Afterward, he and Dr. Frondoza

extract the cells and examine how the cells

grow and reproduce while under the load, to

find the appropriate load needed to generate

tissue at an accelerated rate for eventual

implantation into a joint.

The work done by Profs. Ramesh and

Frondoza on cartilage cells may one day be

applied to problems involving other cell types

(e.g., bone cells), in the hope that by engineer-

ing living tissues, various debilitating condi-

tions might be eased or cured.


K.T. Ramesh

Professor and Department Chair Joint Appointment, Materials Science and Engineering

Ph.D. Solid Mechanics, Brown

University, 1987 Sc.M. Applied Mathematics,Brown University, 1987

Sc.M. Solid Mechanics,Brown University, 1985

B.E. Mechanical Engineering,Bangalore University, 1982

Research Interests:

Material failure at high strainrates, composite materials,

biomimetics, active materials,rheology of microstructured fluids



25

Protein Folding

T he work that Professor Gregory Chirikjian

has done modeling and designing highly

articulated robotic arms has an unusual biolog-

ical application at the nanoscale—in our

understanding of molecules, particularly pro-

teins. Present in all living cells, proteins are

formed when ribosomes, acting upon instruc-

tions from a messenger RNA template, string

thousands of amino acids together into long

chains. Within minutes these chains then

“fold,” like long shoelaces, into complex struc-

tures. But out of the

huge numbers of possible

structures into which a

given chain of amino

acids could fold, only one

allows that particular

protein to function prop-erly. The human body

forms at least 30,000 dif-

ferent proteins.

Alzheimer’s disease, cys-

tic fibrosis, and possibly

certain types of cancer

are among the diseases

caused when something goes wrong with the

way a protein is folded.

The question is, Why, out of all those pos-

sible geometries, does the protein end up in

one particular shape? What causes it to go

wrong in certain cases? And what does thishave to do with mechanical engineering?

Biologists have typically assumed that the

atomic bonds in molecules are simple “lock

and key” mechanisms, and the molecule a rigid

structure. We now know that the bonds

between atoms are highly flexible, allowing the

molecule to deform, fluctuate, or vibrate in

response to its environment, and that individ-

ual atoms within a molecule might also influ-

ence each other.

Johns Hopkins Medical Institutions, as

well as the Homewood campus Biophysics

Department, are hotbeds of protein folding

research, and Prof. Chirikjian has recently

joined the effort in an unusual way. He and his

colleague Robert Jernigan of the NIH point

out that the atoms in complex molecules like

proteins are joined together much like the

joints in an arm, and the key to understanding

how a protein folds and fluctuates depends in

part on understanding the mechanics of those

joints. By using computational techniques

developed for robotics research, they are study-

ing proteins by applying classical mechanics to

the bonds between atoms. In one modeling

approach, every atom in a protein is simulated,

and the complex mechanics and chemistry gov-

erning the bonding and folding of the amino

acid chain are carefully calculated. This is

time-consuming; a supercomputer needs a

month to produce what it takes nature a mat-

ter of seconds to accomplish; a folded protein.

Prof. Chirikjian is working on “coarse-grain-

ing” these models to

improve the efficiency of

the calculations while still

maintaining accuracy.

Using spatial-averaging

techniques he developed

in his robotics research, hehopes to be able to model

the fluctuating protein

within minutes on a PC.

Protein folding is a

competitive and exciting

area of research because

there is a huge amount of

medical progress and financial profit to be

made from solving this problem. Once

researchers understand how the atoms in a pro-

tein behave under standard conditions, they

can explore how the mechanics, and thus the

folding, would be altered if different forceswere in place. The ramifications of these dis-

coveries would be felt throughout the biotech

industry—from protein manufacturing, to

drug design, to genetic engineering. Perhaps

the process that goes awry in patients with

Alzheimer’s or other diseases involving mis-

formed proteins could be discovered, and a

treatment found. The race to develop an accu-

rate model also makes practical sense—it takes

six months or more for experimentalists to

image a single normal protein using Nuclear

Magnetic Resonance Imaging or X-ray data.

Working at that rate, the possibility of analyz-

ing all the human proteins seems remote. But

if a fast, reliable, and accurate algorithm can be

developed, we might actually see some of the

applications of an improved understanding of

protein folding and mechanics within a

generation.


…out of the huge

numbers of possible

structures into

which a given chain

of amino acids could fold, only one

allows that

particular protein to

function properly.

Actin Protein



Each year ME seniors take a yearlong

design course taught by Professor Andy

Conn and assisted by Undergraduate Lab

Coordinator Curt Ewing. Students working in

groups of two or three select small-scale engi-

neering design problems suggested and funded

by corporations, government, or non-profitagencies. With funding for FY 2001 not

exceeding $8,000 per project, the students

handled every aspect of the design process,

from brainstorming possible solutions to

preparing a budget to purchasing equipment

and putting together a final device or product.

In the first semester, they present oral reports

describing how they settled on their final solu-

tion to the problem. At the end of the year,

their final devices or products are presented

and demonstrated in a special two-day series of

presentations, with industry representatives

and ASME judges present. The ASME judgesselected Team ARMED as this year’s award-

winning project.

This year, Professor Conn and Mr. Ewing

guided 12 projects to conclusion. Below are

brief capsules of each project.

Project CHIPS (Chilling and

Piping System)

This project, funded by Johnson Controls Inc.

was a scale-model of the chilled-water flow sys-

tem that is used to cool and heat buildings on

the Homewood campus, as well as a software

program for simulating the campus cooling

system. The students built a three-

level miniature model of the cool-

ing system—each level represented

a building. Their software deter-

mined the heating/cooling loads for

the buildings under normal condi-

tions and three extreme events—

heavy traffic, hundred-degree days,

and plant capacity loss. They found

that their chilled water configura-

tion could meet those extreme

events. Students: Des Jui, ScottMartorana, and Craig Miller.

Project RUDY (Raising

Up Disabled Youth)

This project, funded by Volunteers for Medical

Engineering and the JHU BME Department,

asked students to design a lift that would

allow disabled children to access playground

equipment. The students’ lift was powered

pneumatically by a scuba tank and operated

with a pulley mechanism. It was portable,

weatherproof and cost-efficient, could access

varying heights, was easily interfaced with

playground equipment, and met strict safety

requirements. Students: Christian Callaghan(now working in an architectural firm in

Chicago), Denise Koh, and Nate Kruis.

Project CAMERA (Computer

Aided Monitoring Equipment

for Remote Analysis)

A paper products manufacturing company

funded this project that asked students to

come up with a way to monitor and diagnose

problems with a food packaging machine.

When the machines are off-line, valuable prod-

uct and time is lost waiting for a technician to

come service them. The students came up withthe remote sensing equipment and software

program that enables a technician to diagnose

the machine from an off-site location.

Students: Cara Libby (will be at Stanford in

Fall 2001), Angus Shee (headed for Northrop

Grumman Corp.), and Zheng Xu.

Project GATE (Guard Against

Tumbling Exits)

Every year, several deaths occur and thousands

of hospitalizations result from children falling

out of high-rise apartment building windows,particularly in public housing complexes. This

project, funded by the JHU

Center for Injury Research and

Prevention, was a window

guard designed to prevent

these kinds of injuries. Current

guards have drawbacks—they

don’t permit entry from the

outside (for firefighters), kids

can pretty quickly figure out

how to release them, and there

are no security features that let

the resident know when theguard has been released. The

students came up with a

durable, detachable guard system, with a child-

proof latch and integrated alarm system. They

took advantage of work done on safety release

mechanisms by last year’s team GAT, who did

extensive research into mental and physical

challenges for young children in the design of

Senior Design Projects

Denise Koh in Project RUDY

26

With funding for

FY 2001 not

exceeding $8,000

per project, the

students handled

every aspect of the

design process, from

brainstorming possible solutions to

preparing a budget

to purchasing

equipment and put-

ting together a final

device or product.

W I L L K

I R K



27

an anti-firing mechanism for handguns. Fellow

classmates enjoyed acting as firemen, bashing

their way through the guard using fire axes.

Current guards run $70–$100 each; their

improved version could be made for $150.

Students: Mike Barnard (headed for an engi-

neering firm in Pittsburgh) and Howard Ku.Project N’SYNCC (Northrop

Grumman Shakeless Yet Not

Costly Cart)

As electronic equipment is moved on carts

from a calibration facility on moving equip-

ment such as forklifts, it gets jostled about as

the carts bump over cracks, vibrate on rough

floor surfaces, dip into potholes, or occasionally

run into walls. As a result, delicate equipment

gets knocked out of calibration. Northrop

Grumman asked the students to come up with

a cart that could protect equipment subjectedto 8-10 Gs of force, and not to exceed $1,500

in price. It had to hold items of varying size,

prevent them from sliding on the shelving,

have securely latching doors, be able to fit onto

a forklift, and it had to be weather resistant

and operable by a single person. The students’

novel design used foam and carpeting, com-

bined with dampers on the shelving and a sus-

pension system under the cart. Their cart had

stackable bins, semi-pneumatic tires, a special

forklift mating system, and a nice changeable

sign on the front. And when bought in sets of

20, each cart costs only $1,369.02! They had

fun testing the cart with the help of a shaker

table, a brick wall, some accelerometers, and an

oscilloscope. Students: Josh Buckley (headed

for Lehman Brothers), Kevin Leiske (working

in sales for Modine Corp.), and Howard

Turner.

Project STAR (Shear-

Thickening Armor Research)

This group of students was involved in a

potentially revolutionary new concept in body

armor—ceramic slurries. The Army ResearchLaboratory asked for help in creating a testing

device that would give information on the

shear rates of these slurries under impact. Such

slurries are known to stiffen under rapid rates

of loading, thus offering the possibility of

remaining soft until impacted by a projectile.

The students designed and built a loading

mechanism, a spring-driven Testing Machine,

which provided the rapid rates of shearing

required to evaluate these slurries. Students:

Josh Mengers (now at the Army Research

Laboratory), Jenna Mikus (now at Andersen

Consulting), and Tyler Tom.

Project ARMED (Actuated

Reusable MiniatureElectronic Door)

In space, sensing equipment is at the mercy of

micrometeorites and extreme temperature and

UV fluctuations. To protect sensors while not

in use, the Space Department of JHU’s

Applied Physics Laboratory asked students to

come up with a door mechanism that could be

remotely opened and closed. It had to use min-

imal voltage (5V DC) and be lightweight, able

to withstand temperature ranges of -90 C to

+90 C, have a rotating angle of 180 degrees,

and a latching system with feedback control.The students settled on a flip-top design and

an aluminum alloy material. They used a set of

springs made from a shape memory alloy as

actuators, and subjected the whole device to a

vibration test to simulate takeoff conditions.

Students: Matt Eby (headed for University of

Colorado, Boulder), Seth Hubbard (now at the

Naval Surface Warfare Center), and Song

Hwang (headed for Cornell University).

Project ACDC (Automated

Control of Drainage and

Concentration)

Sponsored by the Baltimore Aircoil Company,

this project was to automate the process of

“blowdown” in cooling towers. A cooling

tower works by using evaporation, which even-

tually leads to increasing levels of minerals and

other solids in the water that is cycling

through the tower. When concentrated solids

are not removed, they cause buildup on the

tower, which then has to be shut down and

cleaned periodically. “Blowdown” is the process

by which water with a high concentration of

solids is removed from the cooling tower. Thestudents came up with three possible alterna-

tive methods of automating the blowdown

mechanism, using only the power available

from the incoming makeup water. Their cost

was kept within prescribed boundaries, and

they created models of each device that could

be scaled to different-sized cooling towers.

Students: Steve Lomnes (working for General


In space, sensing

equipment is at the

mercy of micromete-

orites and extreme

temperature andUV fluctuations.

(Project ARMED)



28

Electric Corp.), Rob Sola (now at Baltimore

Aircoil Company), and Abby Winthrop

(headed for MIT).

Project SHIPS (Sonar Hull

Inspection Positioning

System)

When roving underwater depths, exploring the

ocean floor or inspecting the undersides of

ships for damage, Remotely Operated Vehicles

(ROVs) use sonar equipment as their eyes and

ears. Because the ROV itself is difficult to tilt,

it was only able to “look” in the fixed direc-

tions of its rigidly mounted sonar camera. The

Naval Surface Warfare Center asked students to

devise a remotely controlled robotic arm that

could hold the sonar device and provide rotat-

ing and tilting capabilities to increase the view

angles of sonar camera devices on ROVs. It had

to have no more than a 2 Amp power supply,operate at 200 ft. below sea level, and meet

strict size constraints. The students came up

with an arm that met these requirements; it

had two operating speeds, was waterproofed

against sea water, was operable either with a

joystick or on autopan (an automatic full scan

in one plane). Students: Suhaila Ehr (now a

reporter for TV3 in Malaysia), Katie Mangum

(at the Naval Surface Warfare Center), and

Brian McFadden.

Project CHAP (Calibrated

HARP Apparatus Phantom)

Researchers at Hopkins are developing a prom-

ising new, fast and, non-invasive method of

measuring cardiac function using Magnetic

Resonance Imaging, (MRI), known as HARP-

MRI (Harmonic-Phase MRI). JHU’s

Engineering Research Center for Computer

Integrated Surgical Systems and Technology

(CISST) asked ME students to come up with a

“phantom” heart that could be used in the

MRI scanner to calibrate this new method. The

material had to be elastic, non-magnetic, non-

conducting, and image successfully. This“heart” was supposed to undergo radial com-

pression, torsion, longitudinal compression,

and ellipticalization, all controlled by a remote

operator, since no one is allowed in the MRI

room during a scan. After playing around with

various kinds of sticky gel substances, the stu-

dents settled on a silicon-gel embedded with a

meshlike netting to provide focus for the MRI

calibrations. They were able to provide two of

the desired degrees of motion, radial motion

and ellipticallization. Students: Thanh Lam

(headed for the University of Pittsburgh), Bob

Matarese (headed for Stanford University), and

Mathan Shanmugham.

Project JIMI (Jet Injection

for Mass Inoculation)

Over 100 patents have been issued for various

devices that jet-inject vaccines and other med-

ications into the body without the use of nee-

dles. In fact, the technology is over 50 years

old. It’s a great idea; it’s quicker for mass inoc-

ulation applications, it’s safer, there is less

long-term trauma and scarring at the injection

site, it’s easy to perform, and jet injections are

often just better at drug delivery than needles.

But with current technology, the cost of injec-

tions is quite high, and splashback from the jet

poses cross-contamination risks. Felton MedicalInc. sponsored a project to design a device that

would test how well various different injectors

are working (it would simulate skin) and to

design a proof-of-principle device. In addition

to testing several current injectors, the stu-

dents in this group designed a needle-less

injector that outperformed other current mod-

els, including a model developed in the previ-

ous year’s senior design class! Students: Matt

Coggin, Meave Garigan (now at the Naval

Surface Warfare Center, Panama City), and

Jake Jenkins.

Project SLIPP (Slip-

Integrated Polymer

Processing)

As part of the process of manufacturing nylon

filters, nylon is heated and spun into long fila-

ments that pass over an aluminum roller and

onto the filter. Unfortunately, the rollers often

overheat, causing the nylon to melt and adhere

to the roller instead of passing on to the filter,

causing a big sticky mess. Two ME students

were asked by a filter manufacturer to come up

with a method to cool the rollers. Their designhad to fit into the current roller configuration,

be simple and cheap to operate, and reduce

current operating costs. Their requirement—to

deliver one complete roller system to the com-

pany. The students came up with a new roller

design that incorporated a cooling system, and

delivered their filter. Students: Moon Hwang

and Sam Martin.


When roving

underwater depths,

exploring the ocean

floor or inspecting

the undersides of ships for damage,

Remotely Operated

Vehicles (ROVs) use

sonar equipment as

their eyes and ears.

(project SHIPS)



29

T wo new faculty have joined the

Department: Assistant Professors Allison

Okamura, in the area of robotics and haptics,

and Jean-François Molinari, in the area of com-

putational solid mechanics.

Kevin Hemker was promoted to professor,

Spring 2001. Also, he has been awarded the2001 Materials Science Research Silver Medal

from ASM International.

Bill Sharpe has received the B. J. Lazan

Award from the Society for Experimental

Mechanics—“In recognition of his outstanding

original contributions to experimental mechan-

ics on the microscale.”

Louis Whitcomb is the recipient of the

prestigious 2001 Johns Hopkins University

Student Council Award for Teaching. He

became associate professor, July 2000. Also, he

was appointed associate editor, IEEE Journal of

Oceanic Engineering .Eight New Pi Tau Sigma Members were

initiated on May 8, 2001: Tyler Tom, Angus

Shee, Brian Weibeler, Daniel Olson, Abigail

Winthrop, Robert Matarese, Rory Thomas, and

Michael Cordeiro.

Shiyi Chen became associate editor for

Journal of Computational Physics.

Gregory Chirikjian was promoted to pro-

fessor, Spring 2001. Also, he became associate

editor of IEEE Transactions on Robotics and

Automation.

Joe Katz has become the technical editor

for the ASME Journal of Fluids Engineering , andhas been named to the Whiting School

Mechanical Engineering Professorship

(chaired).

Andrea Prosperetti was elected foreign

member, Royal Academy of Arts and Sciences

of The Netherlands, and to the governing

board of the International Conference on

Multiphase Flow.

Dean Ilene Busch-Vishniac will be receiv-

ing the Silver Medal in Engineering Acoustics

from the Acoustical Society of America.

Associate Dean Andrew Douglas has won

the year’s Wendell Dunn Award, sponsored by

the Johns Hopkins University Student

Council, for his commitment to improving

students’ lives at Hopkins and admirable and

impacting leadership.

Omar Knio was promoted to the rank of

professor, Spring 2001.

Charles Meneveau was appointed associate

editor for Physics of Fluids and served as guesteditor of Annual Review of Fluid Mechanics.

Department chair K.T. Ramesh was elected

a fellow of the American Society of Mechanical

Engineers. He is serving as chair of the AMD

Technical Committee on Dynamic Response of

Materials.

Former Ph.D. student Dr. Kausik Sarkar

will become assistant professor in Mechanical

Engineering at University of Delaware in

September 2001.

Recent Ph.D. graduate Dr. Bo Tao will join

the faculty of Civil Engineering of Purdue

University as assistant professor in September2001.

Former Ph.D. student Dr. Alberto Scotti

has joined Marine Sciences Department of the

University of North Carolina as assistant

professor.

Ph.D. graduate Darren Hitt, currently on

the faculty of the University of Vermont,

received a CAREER award and an NSF Major

Research Instrumentation Grant for microscale

fabrication facility.

The Center for Advanced Metallic and

Ceramic Systems (CAMCS) has been awarded a

grant from the Army, Director is K.T. Ramesh.Former postdoctoral researcher Carl

Boehlert will join the faculty of Materials

Science at Alfred University as an assistant

professor, in September 2001.

Former postdoc Zeliang Xie will become

assistant professor in the School of Materials

Engineering at Nanyang Technological

University, Singapore, in September 2001.

Ph.D. graduate Imme Ebert-Uphoff , cur-

rently on the faculty of Georgia Tech, received

a Career Award from the NSF and the Out-

standing Young Manufacturing Engineer

Award from the Society of Manufacturing

Engineers.

Awards and honors

Endowment Naming

Opportunities

The educational and research

excellence of the Department

of Mechanical Engineering

can be significantly enhanced

by increasing and strengthen-

ing its financial resources.

The contributions of individ-

uals and corporations can be

permanently recognized

through the following pro-

grams:

• Named Professorship

• Named Teaching Assistant

Award

• Named Graduate Student

Fellowship

• Naming the Department of

Mechanical Engineering

To learn more about how you

may support the priorities of

the Department of Mechanical

Engineering through endow-

ment Gift opportunities,

please contact the Office of

Development and Alumni

Relations at 410.516.8723.

Industrial Partnerships:

Corporations may also be

interested in the “Industrial

Partnerships” with the

Mechanical Engineering

Department. For details,

please contact the Department

Chair, Dr. K.T. Ramesh at

410.516.7735.



T o honor the significant accomplishments

of men and women who spent part of their

careers at Johns Hopkins, the Society of

Scholars was created by the board of trustees in

May 1967 on the recommendation of former

president Milton S. Eisenhower.

The society—the first of its kind in thenation—inducts former postdoctoral fellows

and junior or visiting faculty at Johns Hopkins

who have gained marked distinction in their

fields of physical, biological, medical, social or

engineering sciences or in the humanities and

for whom at least five years have elapsed since

their last Hopkins affiliation.

Two of the 15 scholars elected in 2001

were former members of the Department of

Mechanics at JHU, (now Mechanical

Engineering), and one, Wolfgang Kollman,

was elected in absentia in 2000 and was able to

join us this year for the induction ceremony,held May 23 at the Evergreen House.

Ron F. Blackwelder, professor, Department

of Aerospace Engineering, University of

Southern California.

At Hopkins: Postdoctoral fellow in the

Department of Mechanics, May to September

1970. Nominated by Andrea Prosperetti.

Ron Blackwelder has made seminal contri-

butions in the areas of turbulence, flow

stability, drag reduction, and instrumentation.

Michael A. Hayes, professor of mathemati-

cal physics in the Department of Mathematical

Physics, University College Dublin.

At Hopkins: Postdoctoral fellow in the

Mechanics Department, 1961–62. Nominatedby Marc Parlange.

A professor in the Department of

Mathematical Physics at University College

Dublin, Michael Hayes has done pioneering

work in all areas of mechanics. In particular,

wave propagation in materials, deformation of

materials and fluid mechanics.

Wolfgang Kollmann, professor,

Department of Mechanical Engineering,

University of California, Davis.

At Hopkins: Fellow in the Department of

Mechanics and Materials Science, 1973–75.

Nominated by Marc Parlange and CharlesMeneveau.

Recognized as a world leader in the study

of turbulence, turbulent combustion, and

numerical simulation of turbulent flows,

Wolfgang Kollmann has over the past 25 years

advanced the state of the art in the solution of

important engineering problems associated

with complex flows.

Society of Scholars

Big smiles after the induction ceremony for new Society of Scholars members, held at the Evergreen House on May 23, 2001 (L to R): Wolfgang Kollmann, Eleanor Kollman, Colette Hayes, Prof. Grace Brush, Michael Hayes, Prof. Andrea Prosperetti, Prof. Marc Parlange, May Knio, Mary Parlange, Prof. Omar Knio, Judy Blackwelder, Ron Blackwelder, Brigitte Meneveau, Prof. Charles Meneveau

The Society of

Scholars was created

to honor the

significant

accomplishments of men and women

who spent part of

their careers at

Johns Hopkins.

introduccion sensores ilene busch-vischniac

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