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Railguns have great potential in military roles; however, they currently lack a fieldable power supply. Recent advances in the state of low voltage power storage devices may enable practical Pulse Forming Inductive Network power supplies to be developed if a suitable current interruption device is developed. A solid-state device in a counterpulsed opening switch configuration is a possible solution. A demonstration counterpulsed solid-state opening switch was constructed and successfully tested. This circuit consisted of Silicon Controlled Rectifier components, which can nominally only turn on current. The counterpulsed configuration allowed them to function as opening switches and to do so at much higher current relative to their specifications. We demonstrated current interruption at up to 1 kA of peak current. This demonstration system validates the counterpulsing concept and prepares for the construction of a modular, 250 kJ system.

This project deals with the critical evaluation of a Poisson windowed test signal which was proposed for in-service and production testing of filtered pulse code modulation systems. The Poisson windowed test signal has various advantages over the existing two test methods specified by the International Consultive Committee for Telephone and Telegraph (CCITT). The main goals of the new test signal are to minimise the test time and to accommodate the send- and reel eve filters normally found in communication systems. The evaluation process included the compilation of performance curves of signal ,to noise ratio vs. signal level and gain variation vs. signal level. These curves were compiled by simulating the codec and filters on a digital computer and processing the output data. Three sets of programs were The results obtained revealed some fundamental limitations of the proposed test signal. Using the basic properties of the Poisson windowed signal, an alternative test signal was proposed. It was the single sided exponentially windowed sinusoidal which proved to be suitable for the testing of filtered pulse code modulation stems.

<p>In practice, many systems are modeled by first and second order models including a time delay. These low-order models can often be used to describe the most important and characteristic features of a system and be a base for control design. In industry, it is important to have fast, reliable, and easily applicable methods for estimating the parameters in such models. It is well-known that, for practical reasons, many systems can not be excited by an arbitrary input signal. However, a pulse-shaped input signal can most often be used. The aim with this thesis project is to study identification of low-order models based on pulse-shaped input signals.</p>

In practice, many systems are modeled by first and second order models including a time delay. These low-order models can often be used to describe the most important and characteristic features of a system and be a base for control design. In industry, it is important to have fast, reliable, and easily applicable methods for estimating the parameters in such models. It is well-known that, for practical reasons, many systems can not be excited by an arbitrary input signal. However, a pulse-shaped input signal can most often be used. The aim with this thesis project is to study identification of low-order models based on pulse-shaped input signals.

In the past several decades the technology for the creation and use of ultrashort pulses has progressed tremendously. Now, it is possible to generate laser pulses as short as a few femtoseconds in duration, and such pulses have been used for a wide range of applications. In addition, the means of measuring these pulses has progressed so rapidly. However, despite recent great advances in ultrashort-pulse measurement techniques, much remains to be done. In particular, pulse-measurement devices have relatively small wavelength-tuning ranges, and the phase-match is problematic for the pulses with a wide bandwidth such as supercontinuum. In this thesis, I will demonstrate a new pulse measurement technique which can phase-match ultra-broad bandwidth of super-continuum using transient grating frequency-resolved-optical-gating (TG FROG). Also, I will demonstrate a simplified device which can measure the UV ultra-short pulse using transient grating process, one of the third-order nonlinearity and can cover from UV to IR with the same arrangement.

This thesis is to design a Positive/Negative pulse battery charger with a high positive pulse current to charge battery quickly , The negative impulsive discharge current is used to accelerate chemical reaction between pole plates be response. Finally, there is a rest time to let charging effect uniform and to reduce temperature so as to last battery life cycle. The thesis uses dsp to control the single-stage Flyback converter charging battery then combine flyback DCM model and voltage follower control to increase efficiency. The chemical reaction of the negative pulse discharging mode. CMOS switch series connection resistance would speed up . Finally we join two-stage positive/negative pulse battery deep discharging to strengthen the lithium battery chemical reaction and efficient reduce the charging time ,it causes the fixed current charge able to enter more electric quantities until achieving 4.2v lithium battery's definition voltage sufficiently then transforms into the fixed voltage charge. this circuit has reached the goal of high-power Factor and quickly charging to extend life cycle of battery In order to understand the influence of positive/negative pulse ,we measure voltage, temperature and time period of charging and discharging in the experiment.

In this thesis, we will address several important issues on the direct sequence ultra-wideband (DS-UWB) wireless system and will provide a comprehensive analytical study on DS-UWB with different channel models, as well as the impact of pulse shapes on the overall performance.

In this thesis, we studied chirp response and slow light properties in strained saturable Bragg reflector (SSBR). In the part of chirp response studying, we simulated the chirp response of SSBR of pulses with different chirps, and verified the results of related work. The trend of simulation was consistent with experimental result. Therefore firmly believing the broadening or compression ability of chirped incident pulse in SSBR, the pulse compression ability facilitates the mode-locking in laser cavity and generates more narrow pulse. In the studying of slow light properties in SSBR, a home-made pulse shaper system and a cross-correlator system were demonstrated. We control the chirp of the pulse by pulse shaper, and then pulse enter SSBR and reflect from SSBR, and measure the signal distribution in time domain by cross-correlator, finally we can analyze the properties of slow light of SSBR. We have demonstrated the slow light phenomenon was observed as central wavelength of incident pulse approach to resonance absorption of SSBR. In the aspect of chirp control, contrast with negative chirped incident pulse, slower group velocity with larger group delay for positive chirped incident pulse was observed. This could be attributing to absorption increasing which result from more efficient for creating carrier and less-sensitive to the carrier-scattering effect. In addition, we further study power dependence of slow light properties in SSBR under various incident chirps. Increasing group delay with power of incident pulse was performed. In addition, more group delay under saturation was also characterized and analyzed.

Thesis (M. Phil.)--University of Hong Kong, 1989.