IEEE TRANSACTIONS ON EDUCATION, NOVEMBER 1976

Short Notes

Infornation Retrieval Techniques in theEngineering Curriculum

MADHU SUDAN GUPTA, MEMBER, IEEE

Abstract-The need for training engineers in the use of informationresources and retrieval techniques, and the advantages to be gainedfrom such a training, are stressed. The possibility of replacing theforeign language proficiency requirement by such a training in doctoraldegree programs is examined. Some of the anticipated argumentsagainst this training are answered. Possible course contents and someoperational problems are discussed.

I. INTRODUCTION"Nothing so needs reforming," wrote Mark Twain, "as other

people's habits." This remark would be worthy of considera-tion had Mark Twain been referring to the information gather-ing habits of engineers.The purpose of this short paper is to emphasize the need for

training students (and in particular graduate students pursuingresearch) in the techniques of information retrieval. It ispointed out that new information services and retrieval toolshave been, and are being, developed to increase the efficiencyof scientists and engineers. An awareness of, and exposure to,these resources is necessary before they can be fully used. Atthe risk of being charged with contributing to the proliferationof courses, it is proposed that a deliberate attempt be made toexpose the students to information retrieval techniques.

II. NEED FOR TRAINING IN INFORMATIONRETRIEVAL METHODS

The tremendous growth in the scientific and technicalresearch efforts, and the consequent increase in the literatureof these fields, hardly needs to be pointed out [ 1 ], [ 21 . Theestimated yearly publication of two million papers in all fieldsof science and technology taken together, the doubling ofpublished research every 10 to 15 years, and other such stag-gering statistics are now well known. At the same time, therising cost of research, the pressure to reduce the time-lagbetween research and application, and the need for largeamounts of information from different disciplines, make itnecessary to use this literature effectively. The duplication ofresearch must be avoided by retrieving and using the availableinformation whenever possible, and therefore, large amountsof literature must be searched through efficiently.Fortunately, much is being done to help the information

users in finding the necessary literature [3 ]: a large number ofindexing and abstracting journals are being published in spe-cialized fields, many information centers, document deposito-ries, and data compilation services have come into existence;professional societies such as the IEEE have initiated new pro-grams often with government aid, several literature search andcomputer-aided retrieval services are now available, specialpublications like bibliographies, literature guides and reprint/review books are being prepared and finally, the research andactivity in the field of information storage and retrieval itselfhas greatly accelerated.

Manuscript received November 18, 1975; revised May 10, 1976.The author is with the Department of Electrical Engineering and Com-

puter Science and the Research Laboratory of Electronics, Massachu-setts Institute of Technology, Cambridge, MA 02139.

But, of course, a service must be used in order for it to beuseful. Unfortunately, there are reasons to believe that en-gineers, and particularly, "young engineers are generally igno-rant of the present information systems available to them"[4]. This observation is supported by two different forms ofevidence.

1) As a result of the current interest in improving the dis-semination and use of technical information, the informationgathering habits of scientists and engineers have been studiedin depth [5] -[9]. One of the significant conclusions of thesestudies is that, as compared to other professionals, the engi-neers are more dependent upon oral information and uponcommunication on individual level. The conventional methodsof getting information, such as correspondence, conversations,or personal contacts (the "scientific grapevine") become lessefficient 1) as the number of workers in a field increases, 2)when the workers are scattered in many countries around theworld, and 3) when it is necessary to obtain the informationfrom adjoining areas related to one's field. Yet the engineerscontinue to rely heavily on these older methods.

2) New information services cannot be cost-effective unlessthere is sufficient use. The casuality figures in informationindustry are high and heavily subsidized services fail to achieveself-sufficiency after years of trial use.' User apathy seems tobe an important reason for the demise or nonexistence of in-novative services and facilities. This apathy results partly fromignorance about available resources and partly from "tradi-tion." Most of the established research workers have set habitsof searching infonnation related to their work, such as relianceon regularly scanning a few specialized journals. This practicecan be self-deceiving because the primary information is usu-ally scattered in a large number of journals and other sourcesand is often disguised under different names.

It may seem surprising that on the one hand there is a needfor technical information and on the other hand there is un-derutilization of existing information resources. This apparentcontradiction is resolved by the aforementioned surveys ofinformation use. These surveys indicate that the preferencefor a given method of information gathering reflects the esti-mated ease of use of the method rather than the amount ofinformation expected [7] . Users find it natural to rely on themost accessible and familiar sources rather than to experimentwith new ones that may require a greater initial investment ofeffort. The Committee on Scientific and Technical Communi-cation (SATCOM) of the National Academy of Sciences-National Academy of Engineering reports [ 11 that the usersof scientific and technical information are slow to changetheir habits, usually learned in their formative years. As aconsequence, there are strong tendencies toward "in a rut"behavior and toward apathetic responses to new and moreeffective services. SATCOM therefore recommends educatingusers for new options and information services which arebecoming available.Given that

1') there is much scientific information available today andsome of this information is valuable, or even crucial, toongoing engineering research;

2) older, informal techniques of keeping abreast are nolonger adequate, but there are available an increasingly largenumber of aids for information retrieval;

Admittedly,not all proposed services are well designed and worthyof continued existence, and the noncompetitive ones willalways meetthis fate.

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IEEE TRANSACTIONS ON EDUCATION, NOVEMBER 1976

3) there is a user apathy towards new information services dueto ignorance and the force of information gathering habitslearned in formative years;

the duty and the role of an educator are clear. Some trainingin the use of information resources and retrieval methods isdesirable for all engineers. In particular, for graduate studentsready to embark on a research program, this training wouldnot only help the dissertation work but would have the long-term benefit of teaching good research habits.

III. CURRICULAR IMPLICATIONS OF THE TRAINING

Stated objectives of engineering education differ somewhatfrom each other but usually include the teaching of the use ofan engineer's tools. The literature of electrical engineering isalso a tool to be used in research, much like an oscilloscope ora computer. Most university courses are, however, taught withthe aid of one or more textbooks so that the students do notseriously encounter the literature of electrical engineering untilthey reach a seminar course, or at worst, their thesis work.Formal training in the use of this tool appears to be rare. Theusual "library instruction" programs (see [ 101, for example)are much more limited in scope and objectives than the train-ing proposed here.Engineering curricula have often included "nontechnical"

courses for professional development on subjects like patentsand inventions, technological assessment, societal implicationsof technology, history of engineering, technical writing, pro-fessional ethics, and legal aspects. The retrieval of technicalinformation has not received a similar emphasis as a subjectworthy of instruction to engineers. The practice of teachingprofessionals (other than librarians) the use of library re-sources and information retrieval methods is not new-forexample, the law students can review court decisions onlyafter learning the use of law libraries. Among the sciences,medicine and chemistry are two fields in which the ability touse the literature has been considered important; surveys haveshown that a formal course in chemical literature is taught atapproximately 40 percent of all schools offering a major inchemistry, while some informal methods are used at the rest[111 . In some other fields, notably education, the use ofliterature is usually taught as part of a more general course,typically entitled "Research Techniques." 'There have beenscattered attempts at a similar training in other disciplinesalso [121. Note that the fields mentioned above (law, medi-cine, chemistry, and education) are not "academic" in theworst sense of the word, where the literature might be an endin itself.

It is evident that the curriculum is already under a greatpressure due to the same phenomenon that makes informationretrieval necessary, namely an unprecedented growth in thetechnical fields, and there is a limit to what can be squeezedinto the curriculum. But a training in information retrievalshould be viewed as a method of reducing this pressure ratherthan as additional burden on curriculum. A university will,in effect, be placing the responsibility for learning on theindividuals by giving them training in efficient methods oflearning. To quote John W. Gardner [ 131, "the ultimategoal of the educational system is to shift to the individual theburden of pursuing his own education." The rate of scien-tific development has already made it unfeasible to teach anengineer in college all of the technical information requiredby him in his lifetime. The proposed course will tend tocompensate for the fact that much of the technology learnedin engineering school has only a limited lifetime. An individ-ual trained in the use of technical literature should be betterprepared to fight technical obsolescence (14] and is in a betterposition to fill-in the gaps in his technical education.From a pragmatic point of view, it may be necessary to de-

lete some existing course work before adding anything new to

an already over-burdened curriculum. One possibility to beconsidered is the replacement of the usual foreign-languageproficiency requirement in doctoral degree programs by profi-ciency in information retrieval techniques.2 A training in in-formation retrieval serves at least one of the stated purposes ofinstruction in a foreign language: increasing the students' abil-ity to reach a larger amount of relevant professional literature.If the foreign language requirement is indeed to be replaced,a more substantial program of training in communication skillscan be envisaged, in which the retrieval of information will beone of the components. Other subjects that may be worthy ofconsideration include training in engineering writing and pre-sentation of technical information.

IV. THE CASE AGAINST THE TRAININGIt is possible to raise many arguments against the proposed

training in information retrieval techniques. Half a dozen ofthe principal criticisms of the training are anticipated andrebutted here.Perhaps the most common argument advanced against a

deliberately designed training program in the use of informa-tion retrieval techniques is that such skills can be learned "on-the-job" as and when needed. (Incidently, this argument canbe applied to almost all skills and teaching, not just to infor-mation retrieval techniques). While the motivation for infor-mation retrieval may be high in the context of a researchprogram in which the student is involved, there is a disadvan-tage in relying on this incidental mode of learning: one learnsthe use of only those services and tools that are immediatelyneeded and does not become familiar with the whole range ofavailable resources.Some may feel that the skills of information retrieval are

based on conventions and practices rather than on difficultconcepts and fundamental principles which are typical ofacademic disciplines. They can therefore be self-learned,making it unnecessary to design an explicit training programfor this purpose. This argument overlooks the fact that evena self-training program needs learning resources and can bemade more efficient by recognizing its need and making facili-ties available for it. If a training in information retrievaltechniques is important, it deserves to be taught to futureresearch workers and should not be left to be picked up acci-dently, casually, or inadvertently.Doubts have sometimes been expressed about the utility of

a training in information retrieval techniques when librariansand information specialists are available to serve an engineer.However, the reasons why an engineer should learn the use ofinformation retrieval techniques even though librarians areavailable are the same as the reasons an engineer learns com-

puter programming despite the existence of professional pro-grammers. Some information services are most effective whenused by the engineer himself rather than through an interme-diary. He may also have to adapt his reading and browsinghabits to the new information tools. In addition, an engineermust know what is available in order to ask for it. The pro-posed course is not intended to eliminate the need for librar-

2It is not the purpose here to discuss the desirability, or otherwise,of foreign language training in doctoral degree programs. This subjecthas been argued for decades in almost every doctoral degree grantinguniversity in the country, and very little that is new can be added to thestandard pro and con arguments. A recent survey shows that the foreign-language requirement has already been dropped by about half of allinstitutions offering the Ph.D. in electrical engineering in the UnitedStates and Canada over the past decade [15 ] . The present discussionis confined to exploring a possible alternative to the foreign languagerequirement in view of this already existing trend. Suggestions haveoften been made that the language training can be usefully replaced bytraining in problem solving, effective teaching, scientific management,statistics, experiment design and error analysis, computer programming,etc. Still another alternative is being proposed here.

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SHORT NOTES

ians but to expose the engineer to research techniques havinghigh efficiency. For this reason the training will have to beoriented towards users rather than the professionals in infor-mation science.

Futility of such a course might also be pointed out on thegrounds that an extensive literature search frequently turnsup obscure references, often in a different language, which arenot easily procured. Even if this is so, a knowledge of theexistence of a reference helps in making a better judgementthan does ignorance. An abstract in English can usually befound easily and it may be sufficient in itself, or even suffi-ciently interesting to justify the effort involved in obtainingor translating the entire article.There is a possible danger that a student with this training

may get so preoccupied and engrossed with the literature thathe may neglect his own work. (While creative individuals areusually avid consumers of literature, all heavy-readers may notbe creative). The course may also encourage the perfectionistattitude that everything related to a specific subject must beread and understood before one can contribute creatively, anda feeling of panic or frustration may result when everything onthe subject cannot be read. It appears unlikely that the solu-tion to such problems lies in continuing to use inefficientmethods of literature searching. The confidence that is to bederived from a search known to be extensive is comforting andmay dispel some of the other fears. Perhaps the danger can bereduced if the use of information retrieval is emphasized as anefficient tool for problem solving rather than for scholarlyreading.The question whether the literature is worth searching at all

has also been asked. The answer must be yes for at least someof the literature, because an engineer cannot work in a literary-vacuum. The retrieval of older periodical literature may be-come unnecessary as its content becomes either obsolete orassimilated into textbooks and handbooks. However, there isno alternative to retrieval for obtaining most of the nonperi-odical literature and much of the recent periodical literature.While some of the literature may get progressively obsolete,the ability to retrieve literature is always needed for activitieslike initiation of research projects, teaching, and writing ofbooks and papers.

V. CONTENT AND IMPLEMENTATION OF THETRAINING PROGRAM

It is not necessary that the training in the use of engineeringliterature and information retrieval techniques be impartedthrough a formal course. An informal course may have theadvantage of attracting students who attend for the sake oftraining rather than for the purpose of credentials. An infor-mal program may also reach a larger audience than a formaloptional course requiring scheduling, examination, and grades.On the other hand, it may be argued that if the training isworth giving, it is worth giving rigorously, with full motivationand effort. In addition, offering a formal course will empha-size that the training is to be taken seriously.The ultimate purpose of a course in information retrieval

techniques should be to prepare a student so that he can makeefficient and effective use of the existing and proposed retrie-val systems. A fundamental principle in learning theory is that"a student learns to do best what he does." Therefore, thiscourse should involve actual use of the retrieval techniques,and should not rely completely on lecturing. Several source-books and guides are available to serve as "text books" forsuch a course [3 1. However, the course would hopefullyconsist of demonstrations and practice in the actual use ofretrieval aids rather than a sermon on the subject. Learningactivities may include the use of some of the existing infor-mation tools and retrieval aids, manual and computer-aidedliterature searches, tracing the development of a subject, find-

ing of the state-of-the-art values of some parameters, retrievalof technical data, standards and patents relating to a product,and the compilation of a subject bibliography [ 16 1.The content of the course will depend upon what the stu-

dents already know, what they need to know, and what canbe taught under given circumstances, i.e., upon preparation,interest, and constraints.3 It is perhaps safe to assume nopreparation except for those students who have some researchexperience. Variations of interest can be taken into accountby appropriate individual assignments. The constraints, suchas available time, library resources, and computer facilities,are likely to restrict the course contents most.Naturally, the course content will also be influenced, to

certain extent, by the individual teaching the course. Thequestion as to who should teach such a course deserves someattention if the training is to be successful. A unique answerto this question cannot be given because every university hasits own special circumstances. Professional information sci-entists, technical librarians, and electrical engineers in aca-demic and industrial fields having sufficient exposure toinformation resources, are all qualified in different ways toteach such a course.A survey of engineers employed in research activity could

be carried out to determine their need and desire for a trainingin information retrieval, formal or informal sources whichhelped them increase their efficiency in this area, and theextent of their knowledge and awareness. The results of sucha survey would help in establishing whether the proposedtraining is worthy of further consideration and whether thesuggested course activities will be helpful.In addition to the selection of appropriate course content,

several other problems must be solved before a trainingprogram can be made operational. Some of these problemswere considered at the American Society of EngineeringEducation Conference on Information Sources, Systems, andMedia in Engineering Education about a decade ago [ 171.It was recommended that the first phase of such a programshould be the training of engineering faculty who can in turntrain the students at their respective institutions. The financialsupport for such a program must come from the individualinstitutions and from government, as suggested by Garfield[ 181 . Preparation of curricular material and the evaluationof the program are some of the other necessary ingredients.Above the main entrance of the graduate school building

(Dodd Hall) at Florida State University are engraved the fol-lowing words of wisdom: "Half the knowledge is to knowwhere to find the knowledge." The words are no exaggera-tion and they become even more true as years pass; only thefraction "half" could be revised upwards, if anything. Foryears, an introductory course in library science (LS500) orits equivalent was required of all students beginning doctoralstudy at this university. There have been several other schoolsfollowing this practice, see for example [19] . Hopefully, theneed for such a training will be more widely recognized.

REFERENCES

[1] National Academy of Sciences-National Academy of Engineer-ing, Committee on Scientific and Technical Communication,Scientific and Technical Communications, National Academy ofSciences, Washington, DC, 1969.

[2] W. K. MacAdam, "Technology's greatest need: Informationretrieval," Bell Telephone Magazine, vol. 46, pp. 8-11, July/Aug. 1967; also IEEE Trans. Eng. Writing Speech, vol. EWS-11,pp. 3-6, July 1968; also IEEE Trans. Professional Commun.,vol. PC-18, pp. 50-53, Mar. 1975.

3The author, in teaching such an informal course at the MassachusettsInstitute of Technology, Cambridge, found it best to rely upon thenatural curiosity of students, and as a result spent more time on infor-mation sources with which the students were least familiar, such asstandards and patents.

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[31 M. S. Gupta, "Information retrieval: Where to find it when youneed it," IEEE Spectrum, vol. 11, pp. 72-77. May 1974.

[41 J. C. R. Licklider, Nat. Eng. Inform. Conf., Office of Sci.Technol., Executive Office of the President, Washington, DC,June 1965.

[5] D. J. Marquis and T. J. Allen, "Communication patterns inapplied technology," Amer. Psych., vol. 21, pp. 1052-1060,Nov. 1966.

[61 C. Scott, "The use of technical literature by industrial technol-ogists," IRE Trans. Eng. Manag., vol. EM-9, pp. 76-86, June1962.

[7] V. Rosenberg, "Factors affecting the preference of industrialpersonnel for information gathering methods," Inform. Stor.Retrieval, vol. 3, no. 3, pp. 1 19-127, July 196 7.

[81 C. E. Nelson and D. K. Pollock, Eds., Communication AmongScientists and Engineers. Lexington, MA: Heath, 1970.

[9] C. A. Cuadra, Ed., "Information needs and uses," in.AnnualReviews ofInformation Science and Technology, vol. 1, NewYork: Wiley, 1966; vol. 2. New York: Wiley, 1967; vol. 3.Chicago, IL: Encylopaedia Britannica, 1968; vol. 4. Chicago,IL: Encyclopaedia Britannica, 1969; vol. 5. Chicago, IL:Encyclopaedia Britannica, 1970; vol. 6. Chicago, IL: Encyclo-paedia Britannica, 1971; vol. 7. Washington, DC: AmericanSociety for Information Science, 1972; vol. 9. Washington, DC:American Society for Information Science, 1974.

[10] P. A. Henning and M. E. Stillman, Eds., Special Issue on Integra-ting Library Instruction in the College Curriculum, DrexelLibrary Quart., vol. 7, July-Oct. 1971.-Special Issue on Library Instruction: Methods, materials,evaluation, Drexel Library Quart., vol. 8, July 1972.

[11] D. F. Martin and D. E. Robison, "Who's teaching chemicalliterature courses these days," J. Chem. Documentation, vol. 9,pp. 95-99, May 1969.

[12] L. D. Will, "Finding information: A course for physics stu-dents," Phys. Bull., vol. 23, pp. 539-540, Sept. 1972.

[13] J. W. Gardner, Self Renewal. New York: Harper, 1964.[14] R. J. Schwarz, "The technical literature in continued educa-

tion," Proc. IEEE (Editorial), vol. 52, p. 755, July 1964.[15] F. W. Fairman, "Foreign language requirement for the Ph.D. in

electrical engineering: A survey of U.S. and Canadian policy,"IEEE Trans. Education, vol. E-16, pp. 197-198, Nov. 1973.

[161 M. S. Gupta, "Preparation of a Technical Bibliography," IEEETrans. Prof. Commun., vol. PC-16, pp. 7-10. Mar. 1973.

[17] R. S. Taylor, Ed., Information Management in Engineering Edu-tion, Proceedings and Recommendations of the Conference onInformation Services Systems and Media in Engineering Educa-tion. Bethlehem, PA: Lehigh University, 1966.

[18] E. Garfi-eld, "Putting our money where our needs are," Bull.Amer. Soc. Inform. Sci., vol. 1, p. 10, June-July 1974.

[19] A. R. Krull, "Transistors and their applications, A bibliography,1948-1953," IRE Trans. Electron Devices, vol. ED-1, pp. 40-77,Aug. 1954.

Matched filters are discussed in courses on digital communi-cations, radar, pattern recognition, and computer signal pro-cessing as well as in network synthesis and filter design. Theuse of such filters is to achieve maximum signal-to-noise ratio(SNR) at some specific moment in time relative to the time ofoccurrence of a specific signal in the presence of a wide sensestationary noise.The transfer function of a matched filter is

HM(f)= S*(f ) e-j2rfTN(f)

where

S*(f)

N(f)T

complex conjugate of the spectrum of the signalbeing matched;power density spectrum of the noise;"causality delay."

The type of spectrum used may be Fourier transform, Fourierseries, or discrete Fourier transform depending on the type ofsignal processing; Fourier transforms will be used herein.The purpose of this short note is to separate two matchings

that occur in (1); namely, spectral phase matching that pro-duces the desired output peak at time T, and spectral ampli-tude matching that gives this peak value its optimum S/Nvalue. In polar form the spectrum of the signal being matchedis written

S(f)==S(f)jeios(f). (2)

A filter may be said to be spectral phase matched to a signalif

H(f) =A(f)e-js(f ) e-j2rfT (3)

where A(f ) is real and nonnegative.If a signal is applied to a filter that is phase matched to it,

then the output V(t) is

V(t) = F-1 {S(f)H(f)} = JIS(f)IA(f)ed2Wf(t-T) df.

(4)

Because the product IS(f)IA(f) is real and nonnegative themaximum output will occur at t = T:

V(t) < V(T) = IS(f)IA(f) df.-00

(5)

(1)

On Understanding the Matched Filter in theFrequency Domain

THEODORE G. BIRDSALL

Abstract-A matched filter is viewed as a cascade of a spectral-phasematched flter and a spectral-amplitude shading filter. The former pro-vides the peak output in time, and the latter guarantees that that peakhas maximum signal-to-noise ratio (SNR), or the latter may alterna-tively be chosen to provide better time resolution.

Manuscript received February 5, 1976; revised June 9, 1976. Thiswork was supported by the Office of Naval Research Code 222.The author is with the Department of Electrical and Computer Engi-

neering, University of Michigan, Ann Arbor, MI 48109.

The spectral amplitude factor A(f) may be chosen to shapethe output for good resolution, or for best S/N at t = T, or forother purposes. For best S/N one uses

S(= )Af=N(f) (6)

and the standard matched filter is the result.The phase matching is based on the signal spectrum only and

causes all the spectral components of the output to add con-structively at t = T; and hence, cause the output peak. Thespectral amplitude matching of (6) is based on both the signalspectrum and the noise spectrum; this is intuitively pleasingsince this spectral amplitude match achieves the maximumsignal-to-noise ratio (at t = T).Example: The seven digit Barker code (+++- - +-) used in

biphase pulse compression work is shown in Fig. 1(a). If itstotal duration is 77T and W = lIT, the effect of bandlimiting

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