Acoustic field patterns from a planar multi-element ultrasonic applicator were determined experimentally and compared with theory. Measurements were obtained from square arrays of 4 and 16 elements. The acoustic fields produced by various configurations of individual square elements (3.6 cm X 3.6 cm) driven at 1 MHz were measured in water. Transverse and axial scans paths were used to characterize the acoustic beam for different aperture sizes and individual element excitations. Unequal power excitation of adjacent elements produced multiple peaked acoustic intensity patterns. While a simple theoretical model was not able to account for all the experimentally determined transverse and axial field patterns, a model including mechanical damping improved the agreement between theory and experiment. However, less ripple in the axial pattern was measured than predicted by either theoretical model. The ability of the applicator to generate acoustic field patterns suitable for local tissue heating was demonstrated by an experimental study in dog thigh muscle.

A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode-dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low (epsilon r = 10) and high (epsilon r = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios at 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.

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College where he has taught since 1993. Over the past 20+ years, he has become known for his work with students on an eclectic mix of practical, hands-on projects involving such things as electric vehicles, aircraft, vehicles for use in developing countries, and methods of finding and removing antipersonnel land mines. Dr. Pratt is a co-founder of the Collaboratory for Strategic Partnerships and Applied Research. He and his wife of 30+ years have two grown children and three grandchildren. An avid pilot and builder, he enjoys flying over the beautiful farms and forests of the Cumberland Valley.c American Society for Engineering Education, 2015 Page 26.362.1 Combining Digital with Analog Circuits in a Core Course for a Multidisciplinary Engineering CurriculumA multidisciplinary engineering curriculum requires certain core courses to provide students with the content they will need to be successful in subsequent coursework, projects and beyond. Circuit Analysis, a common core course, has traditionally emphasized the analog side, leaving digital circuits for electrical or computer specializations. While a number of recent papers [3][4][5][6][7][8] address improved methods of instruction for Circuit Analysis, strategic ordering of topics and selection of content also makes a difference in preparing students for the curriculum as a whole.With the growing infusion of digital technology in contemporary practice, we believe students in all engineering disciplines should have exposure to digital theory, at least at a basic level. Thus, at Messiah College, we have formed a new Circuits I core course combining introductory analog and digital circuit theory. Accordingly, we replaced our Circuit Analysis and Digital Electronics courses with a new Circuits 1, 2 sequence. While the Circuits 2 course takes up more advanced topics required for electrical and computer specializations, the Circuits 1 course covers basic analog and digital theory, including both discrete circuits and selected integrated circuit devices, working knowledge of which is required for competency in all engineering disciplines. Such competency allows multidisciplinary teams to work together more effectively, when deciding how to implement circuit functionality, make digital measurements, analyze and share digitized data, and plan the flow of information through newly designed systems. This paper provides details on course content division, textbook selection, lecture and lab adjustments, student reaction and other lessons learned, for the benefit of those who wish to try this approach. I. IntroductionA course on electric circuits has long been one of the core courses in a traditional engineering curriculum, providing a basic foundation for students specializing in a variety of disciplines. A typical first semester engineering course on electric circuits such as Circuit Analysis emphasizes linear, discrete elements such as the voltage and/or current source, resistor (R), capacitor (C) and inductor (L), focusing on how to find simplified equivalent circu...

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