Ronald R. DeLyser

Analysis of composite walls and their effects on short-path propagation modeling

For short-propagation paths, correctly representing reflections of electromagnetic energy from surfaces is critical for accurate signal-level predictions. In this paper, the method of homogenization is used to determine the effective material properties of composite materials commonly used in construction. The reflection coefficients for block walls and other types of materials calculated with these homogenized effective material properties are presented. The importance of accurately representing the reflections for signal-level prediction models is also investigated. It is shown that a 5-10-dB error in received signal strength (RSS) can occur if the composite walls are not handled appropriately. Such accurate predictions of signal propagation over a short distance is applicable to microcellular personal communications services deployments in urban canyons as well as indoor wireless private branch exchanges and local-area networks.

Using MathCad in understanding the induction motor characteristics

Computer-aided multimedia education is increasingly popular within the classroom and laboratory. The applications of market-ready mathematical and database programming software for teaching engineering course outline is well appreciated. This article shows how MathCad can be used to introduce electrical machine characteristics simulated at different possible control modes. The undergraduate students require minimum knowledge of a programming language. The examples presented in the article show how MathCad software can be used to simplify some of the characteristics of the three-phase and one-phase induction machine. The result of introducing math software as a teaching tool at the third- and fourth-year level have been accepted and are now used as part of the practical sessions for the electrical machine and other credited courses at Birzeit University, West Bank and Gaza in the Palestine.

Using Mathcad in electromagnetics education

Mathcad is an effective learning tool in electromagnetics courses. Use of Mathcad by students in such courses at the University of Denver incorporate four essential ingredients needed for the successful integration of computer aided learning into a curriculum component: (1) involvement by the student in establishing what is to be analyzed by the computer; (2) a general purpose tool rather than concept-specific software; (3) a user friendly interface; and (4) effective integration of the computational tool(s) into the course. This paper gives examples of the use of Mathcad in the subject areas of electrostatics, plane wave propagation, transmission lines, antennas, and advanced topics.

Figure of merit for low frequency anechoic chambers based on absorber reflection coefficients

Return loss as a function of frequency and angle of incidence is studied to determine the effectiveness of the absorbing material used in an anechoic chamber. This alone is not enough to determine a figure of merit for an anechoic chamber or to compare the figure of merit for one anechoic chamber to that of another. While the information gained from return loss calculations and measurements as a function of angle of incidence is valuable, an overall measure of anechoic chamber effectiveness is necessary in order to compare different designs. In this paper, a new chamber figure of merit which is based on the decay time of the chamber is introduced. This decay time is, in turn, based on the average power absorbed by the chamber walls. The resulting model is simple and does not require intensive numerical computation. Calculations of the figure of merit for anechoic chambers which contain different types of absorbing materials are shown, and calculated and measured values of decay time for a primary standards calibrations facility are compared.

Use of equivalent boundary conditions for the solution of a class of strip grating structures

Equivalent boundary conditions for an electromagnetic strip grating are used to derive reflection and transmission coefficients for a boundary value problem consisting of three nonconducting media where the strip grating exists at one of the planar boundaries. The results are used to generate data for a number of cases where data and/or theories exist. The theory presented compares favorably with the literature cited for the limiting condition that the period of the grating be small when compared with the free-space wavelength of the radiation. >

Undergraduate engineering curricula revision at the University of Denver

The Department of Engineering, in anticipation of the changing needs of future graduates is redesigning its engineering programs. The curricular programs prepare its graduates to be globally competitive. The curricula innovations include interdisciplinary team design projects throughout the four years, increased use of computers, emphasis in communicative skills, forensic analysis of previous projects with a purpose to improve the original design, an increase in electives permitting more tailoring of individual programs, and an overall reduction in program hours to 192 quarter hours.

Outcomes based assessment and a successful ABET 2000 accreditation at the University of Denver

The paper addresses the outcome assessment process at the University of Denver, how it was received by the ABET visiting team and what changes were and are continually being made. The Engineering Department at the University of Denver was selected as one of 12 to be visited in autumn 1998 and evaluated under Criteria 2000. The department has undergraduate programs in computer, electrical, general and mechanical engineering. These BS degrees are also combined with a Masters in Business Administration (MBA) resulting in two degrees in 5 years. All 8 programs were evaluated under Criteria 2000 and all received accreditation.

Enabling effective learning, curriculum delivery reform at the University of Denver

The Engineering Department at the University of Denver (USA) has received a Sturm Program Development Award for reform of its curricula. Specifically they have: (1) changed the learning environment from predominately teacher centered to student centered; (2) implemented a quality based grading method that allows students to know what is expected of them and to actually take part in the procedure; (3) created more studio type classrooms with current technology to facilitate learning and demonstrate state of the art engineering methods and procedures; and (4) blended engineering topics with English topics in an integrated freshman sequence.

A novel multidisciplinary course: measurement and automated data acquisition

A novel multidisciplinary course was developed by the authors that integrates knowledge gained and tools acquired from the introductory freshman, circuits, mechanics and C/C++ courses and is built around the concepts associated with automated data acquisition systems. This lab intensive course uses a suite of data acquisition equipment located in a new Computer Aided Teaching Lab. The presentation format is two lectures and 1 three hour lab per week. The lectures are designed to cover material that directly supports the labs. Labs early in the course explore the subsystems of an automated data acquisition system. The students then learn the operation of the parallel port on the personal computer write C/C++ programs to control the parallel port, learn the operation of analog to digital and digital to analog converters, and learn the use of the C/C++ commands provided for controlling these subsystems. The students learn these concepts while doing typical experiments dealing with the measurement of temperature, strain, and the evaluation of a temperature controller.

A sophomore capstone course in measurement and automated data acquisition

A novel multidisciplinary course (Engineering Applications III) was developed that integrates knowledge gained and tools acquired from the introductory freshman circuits, mechanics, and C/C++ courses. It is built around the concepts associated with automated data acquisition systems. This three-quarter-hour, laboratory-intensive course uses a suite of data acquisition equipment located in the computer aided teaching laboratory at the University of Denver, Denver, CO. The presentation format is two lectures and one three-hour laboratory per week. The lectures are designed to cover material that directly supports the laboratories. Early in the course, laboratories explore the subsystems of an automated data acquisition system. The students then learn the operation of a PCMCIA (personal computer memory card international association) data acquisition card, write C/C++ programs to control the data acquisition, learn the operation of analog-to-digital and digital-to-analog converters, and learn the use of the C/C++ commands provided for controlling these subsystems. These concepts are introduced while doing typical experiments dealing with the measurement of temperature and strain and the evaluation of a temperature controller.