The determination of the amplitude-response characteristic is an important means of checking a network design. However, this measurement is usually a time-consuming procedure and at best does not yield a continuous curve. A device which would produce a continuous curve corresponding to the amplitude-response characteristic would be extremely useful in network design and development. It is shown that the system response to a frequency-modulated signal can be made to approximate the amplitude-response characteristic if the frequency is varied slowly enough so that the "quasi-stationary" conditions exist. The physical realization of this slowly varying frequency requires an oscillator with an extremely large frequency range, controllable by one circuit parameter. The greatest difficulties involved in the design of this oscillator were the development of a simple and stable subtractor and the synthesis of the frequency-determining networks. A mathematical analysis was made to determine the characteristics of the network necessary to produce a logarithmic relation between the oscillator frequency and the control position. The audio-frequency sweep generator was constructed using networks designed to approximate the required characteristics and when tested proved to have a satisfactory output waveform. Any improvement in the oscillator performance would require a better approximation to the specified network characteristics. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The study of the reciprocating internal combustion engine is of prime importance to the student engineer. In our present civilization, the number of units and the total rated power of internal combustion engines in use is far greater than that of all other prime movers combined. Many basic engineering problems are present in the study of the operation of internal combustion engines. A number of mechanical and electrical devices have been developed to aid the engineer in his studies of engine performance. The purpose of this project is to provide the Mechanical Engineering Department of the North Dakota State University with an addition to its laboratory facilities which will enable the student to do additional experimental work in the internal combustion engines field. / North Dakota State University (NDSU)

The thesis presents the principles, design, implementation, and test results of a prototype three-dimensional audio processor based upon the Analog Devices EZ-KIT Lite digital signal processing development platform. The three-dimensional audio processor simulates a virtual sound source that is free to move in three-dimensional space using a monaural audio source for input, a personal computer and mouse for source position control, and six loudspeakers arranged in a Cartesian array for output. Source distance, direction, and speed cues are produced by the processor using the Inverse Square Law, time delay, loudspeaker mixing, and sampling rate conversion by third-order polynomial interpolation. Test results confirm the performance of the three-dimensional audio processor.

Nitrogen oxides control the photochemical production of ozone 03 in the lower atmosphere and influence the concentration of the hydroxyl radical HO in the troposphere. As an important member of the nitrogen oxide family, N02 plays a significant role in serving as the only known source of ozone (through photolysis) in the lower atmosphere and as sink for HO via formation of nitric acid. Therefore, accurate measurements of nitrogen dioxide are essential for the understanding of the processes that determine the distribution of tropospheric ozone and for assessing the impact of human activity on the troposphere. Although reliable and sensitive techniques for the direct measurement of nitric oxide NO have been developed, these results could not be fully applied to direct N02 measurements. The purpose of the present study was to further develop a low pressure laser-excited fluorescence technique for measuring N02 by introducing the idea of a Two-Chamber-Fluorescence-Cell. Theoretical considerations of the performance of such a cell and the flow regime within the cell were done in order to assess the optimum cell design and the conditions for optimum operation. Measurements on a provided two-chambered test cell were done to verify the theoretical predictions made. This test cell has been explored with a Nd:Y AG pumped dye laser (100mW@564nm, 30Hz) and a supplied N02 concentration of lOOppm. The theoretical results suggest that the concept of a Two-Chamber-N02- Fluorescence-Cell yields an improved sensitivity compared to present direct techniques for measuring N02 In addition, experimental results give a better understanding of how to realize the initial idea of an operating Two-Chamber-N02- Fluorescence-Cell.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.