Showing papers in "IEEE Transactions on Education in 1992"

A comparison of two approaches to feedback circuit analysis

Abstract: Two approaches for analyzing single-loop feedback circuits are compared and contrasted. One approach is based on the return-radio concept, and the other is based on two-port analysis. A frequent error in many popular texts-interchanging the computation of return ratio for a dependent source and loop gain of the idealized feedback network-is discussed. Assumptions commonly made in many texts when presenting two-port feedback analysis are examined for validity. Examples are given to highlight the differences between the two approaches. >

Feedback control in ancient water and mechanical clocks

Abstract: Attention is focused on Ktesibios' water clock and the outstanding mechanical clocks based on the crown wheel escapement that first appeared in Europe at the end of the thirteenth century. Specifially, block diagrams and the related equations are derived for both the Ktesibios and the verge and foliot clock. The essential role of feedback for controlling the speed of such devices is pointed out. In particular, each mechanical clock discussed can be regarded as a sampled-feedback control system. This explains why the average angular velocity of the wheel would be constant even in the absence of friction. The operation of the verge and foliot clock is compared to that of the pendulum clock built by Ch. Huygens in the seventeenth century. >

Building intelligent tutorial systems for teaching simulation in engineering education

Abstract: A framework for building intelligent tutoring systems (ITSs) to teach students the use of various simulation systems used in engineering education is described. Case studies to two widely used simulators in electronics education (LASAR, a digital logic simulator, and SPICE, an integrated circuit simulator) provide the basis of pedagogical methodology for teaching the use of simulators. This methodology is used to develop a tutorial environment which includes: an authoring system that enables an instructor to develop and tailor the course contents; and a course presentation system that communicates this information via a direct manipulation interface to the user. The student perceives the tutorial as a hypertext network which can be freely explored; however, the tutoring system monitors and dynamically reconfigures the accessible information according to the level and attainment of expertise by the student. The environment includes components to monitor and evaluate the performance of the student. This tutorial framework is used to create intelligent tutorial systems for SPICE and LASAR. >

Intelligent tutoring system for electric circuit exercising

Abstract: An intelligent tutoring system called Circuit Exerciser is described. The system is designed to help university students learn more about electric circuits. It can formulate drill problems, solve them, and infer mistakes in a student's answer. It can also provide helpful comments to the students on how the mistake was made. The system shows the circuit of the presented problem on graphic displays and is student-friendly. The system architecture, pedagogical cycle, and execution of the system are presented. >

Baseband equivalents in digital communication system simulation

Abstract: In this tutorial the authors attempt to clarify the quantitative relationships among the three signal models, namely, the narrowband, complex envelope, and discrete-time complex sequence forms, commonly used in digital communication systems simulation and analysis. Consistent definitions are adopted in order to prevent confusion and potential resultant 3 dB error. Practical methods are derived for calibration of digital computer simulation quantities. >

Use of symbolic computation in robotics education

Abstract: An application of symbolic computation in robotics education is described. A software package is presented which combines generality, user interaction, and user-friendliness with the systematic usage of symbolic computation and artificial intelligence techniques. The software utilizes MACSYMA, a LISP-based symbolic algebra language, to automatically generate closed-form expressions representing forward and inverse kinematics solutions, the Jacobian transformation matrices, robot pose error-compensation models equations, and Lagrange dynamics formulation for N degree-of-freedom, open chain robotic manipulators. The goal of such a package is to aid faculty and students in the robotics course by removing burdensome tasks of mathematical manipulations. The software package has been successfully tested for its accuracy using commercially available robots. >

A prototype flexible robot arm-an interdisciplinary undergraduate project

Abstract: An interdisciplinary undergraduate project to set up a prototype flexible robot link is discussed. The project consists of modeling, fabrication, and control of the flexible link. The combination of already well-known Lagrange and finite-element methods seems to be a great advantage in this modeling procedure. Lightwave flexible links, although known to save a large amount of operational energy, are not popular in the industry because of difficulty in their modeling and control. Following the methodology suggested, modeling is reduced to a mechanical procedure capable of efficient computer implementation. A simple controller is suggested. The controller is designed using the MATLAB simulation package, and the results are compared graphically. The lessons learned form the project are reported. >

Analysis of electrical machines using Symphony

Abstract: The application of Symphony spreadsheet programs to electrical machine analysis is described. Seven typical examples are presented, namely steady-state performance of a DC shunt generator, speed control of a DC shunt motor, magnetizing current waveform of a transformer, steady-state performance of a three-phase induction machine, frequency control of a three-phase induction motor, induction motor run-up, and swing curves of a synchronous generator. Advantage is taken of the spreadsheet environment for such operations as tabular calculation, table lookup, numerical integration, and what-if analysis. Extensive use is made of the integrated graphics facilities of Symphony for producing good quality screen displays on a personal computer, which proves very convenient and useful for computer-aided instruction. Certain features of Symphony are described in the context of the applications described. >

A capstone design experience for electrical engineers

Abstract: A senior-year sequence in design required of all electrical engineering students at the Milwaukee School of Engineering is described. Commencing in the fall quarter, students form groups of either three or four and formulate a problem having multiple possible solutions which must be approved by their instructor. They must then conduct a feasibility study and present their approach to solving the problem by the end of the fall quarter. During the winter quarter, they perform the paper design and analysis and begin prototyping. Spring quarter consists of prototyping, testing, modifying, retesting, and final documentation. All projects are displayed in a trade-show-type format during the day before spring commencement. Four senior classes have completed the nine-credit sequence to date. >

Tubes and slices: a new way of teaching the principles of electric and magnetic fields

Abstract: To overcome the difficulty experienced by students in visualizing electric and magnetic fields, a graphical method is proposed using a personal computer to display the field. It is argued that the natural structure of such fields is given by tubes of flux and/or slices bounded by equipotentials. These two descriptions are shown to provide upper and lower bounds for the system energy and for the equivalent circuit parameters describing that energy. The calculations are extremely simple and can be used by the student in an interactive mode. The method is, therefore, suitable as a design tool. It can also be usefully combined with a finite element calculation to improve the accuracy. A suitable computer package called TAS is briefly described. >

A laboratory for microprocessor teaching at different levels

Abstract: The design of a laboratory for microprocessor experimental teaching in which flexibility is one of the major design requirements is presented. The laboratory is intended to be used for software and hardware experiments, and is dedicated to students with very different levels of microprocessor knowledge. The basic development station includes a VME single-board computer, based on the 68010 microprocessor, connected through a serial link to a personal computer that acts as the system user interface, allowing the editing, assembly, loading, and debugging of low-level programs. The microprocessor may be connected to the user hardware through a VME interface board which has been specifically designed and developed for this purpose. This interface provides the user with the microprocessor bus signals, some of which have been emulated, and makes the VME bus transparent to users. Thus, the user needs no prior knowledge of this bus. It also acts as a protection system against critical errors in the user hardware. >

Heaviside's operational calculus applied to electrical circuit problems

Abstract: Heaviside's operational calculus approach is compared with the one-sided Laplace transform method augmented with distribution theory analysis as applied to electrical circuit problems. It is seen that there is a high degree of commonality to these methods, but also several significant problem-solving and pedagogical advantages to Heaviside's method. In particular, the Heaviside operational calculus is better physically motivated, conceptually parallel to the well-established complex sinusoidal circuit analysis (the jw method), and less mathematically intricate, and may with ease also handle initial value problems. Moreover, the mathematical theory of the impulse or delta (t) function, defined as the convolution identity and developed using Heaviside's operational approach, compares very favorably with the quite extensive mathematical machinery of the theory of distributions. >

Transient electromagnetic plane wave reflection from a dielectric slab

Abstract: Reflection of a transient plane wave normally incident upon a lossless dielectric slab is analyzed via the Fourier transform. The exact expression for the time-harmonic field is used in the inverse Fourier transform to obtain the transient response to a class of exponential exciting functions. Cauchy's integral theorem and the Poisson sum formula yield closed-form expressions for the unit step and impulse response functions. >

Incorporating computer-aided design into an electrical engineering/computer science curriculum

Abstract: The restructuring of the circuits and computer hardware courses at the University of Michigan's Department of Electrical Engineering and Computer Science to include a uniform set of electronic design automation (EDA) tools beginning early in the undergraduate curriculum is discussed. The ability to teach good engineering in the department has been significantly strengthened by these changes. The program and the details which have made it successful, including using a consistent set of well-supported commercial tools throughout the curriculum, providing adequate computing resources through a tuition surcharge for engineering students, and offering department-wide support through CAD short courses and consulting hours, are described. >

Using spreadsheets in introductory EE courses

Abstract: Ways in which spreadsheet programs can be used to introduce practical considerations in introductory electrical engineering courses are discussed. Examples are presented which show that spreadsheets can be used to predict and/or minimize the errors due to loading, the availability of only standard resistor values, and resistor tolerances. The circuits considered in these examples were selected to be as simple as possible. These examples could be used in the first semester of sophomore credits. They illustrate trade-offs, performance criteria, and nonunique solutions, and are intended to illustrate the power of spreadsheet programs. In the first example, a macro is used to implement a simple iterative optimization procedure. In the second example, minimization is done by exhaustive search using the table lookup capabilities of the spreadsheet. In the final example, the spreadsheet's random number generator is used to perform a Monte Carlo analysis. >

What makes the picture talk: AT&T and the development of sound motion picture technology

Abstract: The development of technological system that brought sound to motion pictures in the 1920s at AT&T's Bell Laboratories and its predecessor, the Western Electric Engineering Department, is described. The telephone company had set out to perfect the national telephone network. Among the technologies developed in this effort were amplifiers, loud speaking telephones (i.e. loudspeakers), condenser microphones, and electrical sound recording and reproduction. In 1922, all the pieces necessary for the addition of sound to movies were in place except for a means to synchronize sound and picture, a task then given to a team of engineers. By 1924, AT&T has produced a complete working system. Western Electric established a subsidiary in 1927 to work with the motion picture industry to develop commercial sound film production, and with the theater owners to equip thousands of theaters to show sound films. >

An engineering practices course

Abstract: A so-called capstone design course at the University of Texas at Arlington (UTA) that maximizes engineering practices is described. The central design project is essentially used as a vehicle for the presentation and experience of engineering practices. To the extent possible, the students are afforded a real-life industry experience. They work in teams, select and propose their systems/projects, specify their systems, plan their projects in depth, design and test their systems, document and orally present their project, and demonstrate their systems. Where appropriate, practices lecture topics are synchronized with the project requirement, providing student preparation and reinforcement. Although the course is part of the Computer Science Engineering program (continuously ABET accredited since 1983), the format and most of the specifics can be applied to any engineering discipline. >

Signals and linear systems: a teaching approach based on learning styles concepts

Abstract: The exclusive teaching of continuous-time concepts before discrete-time concepts in undergraduate signals and linear systems is advocated when circuit analysis is a prerequisite. The reasons for this approach are based on learning styles concepts of inductive/deductive organization, sequential/global understanding and sensory/intuitive perception. This approach is promoted because it: (1) supports inductive progression of material; (2) addresses the needs of students who learn through sensing; and (3) supports both global and sequential learners. Arguments are made that the presentation of continuous-time concepts first promotes the deepest understanding of the material in the largest number of students. >

PC-based spectrum analyzer

Abstract: The design and performance analysis of a low-cost, low-frequency spectrum analyzer are described. This instrument has been conceived as a plug-in board to be incorporated in an IBM PC. Although intended primarily for educational purposes, this analyzer is suitable for other applications such as audio, vibrations, etc. The frequency synthesizer, superheterodyne, and harmonics identifier used in the spectrum analyzer are discussed. >

Frequency domain identification for undergraduates

Abstract: A method to synthesize a transfer function from experimentally obtained gain and phase data is presented. The least squares technique discussed minimizes the error between the inverse transfer function and the inverse of the experimental frequency response data. The relevant formulas are derived in a straightforward manner so that undergraduate students can follow the development. The inverse formulation appears to give a better fit to the data than the previous approaches. This is most likely due to the fact that the technique biases the error with the numerator rather than the denominator of the derived transfer function. There is, however, no guarantee that a minimum phase transfer function will result from this technique. The user of this technique must preselect the numerator and denominator orders. The formulation assumes that there are no zeros at the origin. A modification to the basic scheme is presented for this case. >

An effective approach to obtain model parameters for BJTS and FETS from data books

Abstract: The authors address the problem of obtaining the values of small signal parameters of the high frequency hybrid- pi models of bipolar junction transistors (BJTs) and junction FETs (JFETs) for a given set of bias conditions from the data-book values. They also show the methods of determining the 'typical' values of the input parameters to be used in the model statements of circuit simulators, such as SPICE. >

Prolog simulation of computer architecture in laboratory activities

Abstract: Implementation of a computer architecture simulator prototype written in Turbo Prolog, which is suitable for educational purposes, is described. Besides adapting to teaching needs for conventional use, the simulator design incorporates features for an easy alteration of computer architectural structures appropriate to the trainee's learning level. Thus, this simulator is not limited to a particular architecture but permits the student to vary dynamically the architectural characteristics of the computer under study in order to verify the consequences of his decisions and to experiment with families of computers and alternatives of design. >

A programmable logic array suitable for use in digital system design laboratories

Abstract: A specially designed programmable logic array (PLA) suitable for use in digital system design laboratories for undergraduates is presented. Rewriting the PLA is done just by transferring the new codes; no explicit erasing process is required. The number of product terms allowed implementation on the PLA is unlimited. The computation speed of the PLA is less than 100 ns. The PLA can communicate with a host computer by accepting a variety of commands for writing PLA codes and monitoring input and output values for the PLA. Using software tools developed for the PLA, the student can perform laboratory experiments at various levels. Another software tool permits programming the PLA in a high-level language. The excitation (next-state) and output functions of a controller circuit are naturally described in a simple syntactic construct. Laboratory experiments utilizing the PLA and student responses are also given. >

A VLSI design system for teaching introduction to microelectronics

Abstract: A set of software tools currently used for teaching a course on introduction to VLSI design to graduate and undergraduate students at Osaka University (Japan), the University of Toulouse (France), and the Polytechnical University of Barcelona (Spain), is described. The system includes tools such as schematic capture, mask-level design, and mix-mode simulation. Specific tools such as logic and analog simulation, three-dimensional process simulation, and CMOS logic cell compiler are also included in the software, which represents a valuable educational environment successfully used by a large number of students. The authors present an overview of the complete tool set, essential matters about MOS devices, and the CMOS process. They detail the techniques used for logic design, mask-level design, and mix-mode simulation. They discuss the interest of using such tools in such a course. >

PSpice circuit generation through the method of simulated annealing

Abstract: A software package that was developed to generate a graphical representation of an electrical circuit diagram from a PSpice text file is described. This package uses the simulated annealing method for multivariate optimization. This algorithm is applied to global component connections and circuit design of realistic size and complexity. >

System identification: human tracking response

Abstract: An experiment performed to develop transfer functions for human tracking response is discussed The experiment tested one-dimensional, sine-wave tracking to determine time delay and the transfer function Using system identification techniques, best models were selected for each of five different frequencies of the test sine-wave input Bode plots, magnitude, and phase are given for the system that best models the way humans react Step responses for these models are also given This process provides an excellent tutorial in programming, system modelling, and simulation >

Top-down design process for gate-level combinational logic design

Abstract: A pedagogical process for designing gate-level combinational logic circuits is described. The process can be used for either combinational logic circuits or the combinational logic sections of sequential logic circuits. Positive logic signals (active high signals) as well as negative logic signals (active low signals) can be used in the design process. The top-down design process allows the student to draw functional logic diagrams in a rather routine manner using the positive logic convention, or the direct polarity convention. After obtaining functional logic diagrams, realizable logic diagrams can be easily obtained using any of the common off-the-shelf gate types including AND, OR, NAND, and NOR elements with appropriate inverter symbols. The advantage of the top-down design process is that students can very easily understand and implement gate-level combinational logic functions. Examples are provided to illustrate the top-down design process in teaching combinational logic design. >

Integrating UAHPL-DA systems with VLSI design tools to support VLSI DA courses

Abstract: A complete operational environment established with the help of state-of-the-art tools, to support courses in design automation (DA) of VLSI circuits, is described. It was accomplished with the integration of two systems: (1) a DA system which automatically produces VLSI layouts of digital systems modeled in Universal Hardware Programming Language (UAHPL); and (2) a set of VLSI tools, which in addition to several other functions can be used for simulation and verification of layout designs. Compared with other approaches, the integrated DA system provides a very simple user interface, fast turnaround time, no restriction on the final structure of the layout, and simulation and verification of all phases of design. The new environment, called UAHPL-based VLSI DA, is excellent for teaching and research at universities. >

A computer-aided approach to teaching band structure formation

Abstract: A computer-aided method for teaching energy band formation in a superlattice which enables direct comparison to energy band formation in crystals through the tight-binding method is presented. The time-independent Schroedinger equation for a heterostructure stack is solved by the transfer matrix method along with the effective mass approximation using a standard Fortran 77 computer code. The code is suitable for use on a personal computer which provides a ready laboratory in which the student can examine the effect of varying the electron wavefunction overlap between adjacent sites. In this way, the student can perform a series of computer experiments which vividly illustrate energy miniband formation in superlattices and by direct analogy energy band formation in crystals. >

On the relationship of number of students to academic level

Abstract: Increasing the number of students admitted generally involves a lowering of academic standards This can be offset by splitting classes so that there are fewer students in the classroom Quantitative data indicating a significant improvement in the number and percentage of graduating students are given It is suggested that the qualitative improvement is even greater >