Techn. Universiẗat, Diss., 2000--Berlin.

Techn. Universiẗat, Diss., 2002--Braunschweig.

Techn. University, Diss., 2005--Darmstadt.

A method for estimating distance, in one dimension, to a transmitter for a receiver in motion relative to that transmitter is given with simulation data. The method relies on a stateful preprocessor filter and does not require envelopment of the transmitter.

Design procedures are presented for varactor tuned microwave bandpass and bandstop filters constructed in Microwave Integrated Circuit form. The tunable bandpass filters were based on a combline filter incorporating novel input and output coupling networks which compensate for the frequency dependence of the coupling between the resonators. Using this filter, tuning over an octave band with an acceptable response and approximately constant passband bandwidth is possible. The tunable bandstop filters consisted of a uniform impedance main line with capacitively decoupled resonators located at intervals along it. A novel design technique is presented for evaluating the correct phase shifts between the resonators of this filter in order to obtain the optimum symmetrical frequency response. Detailed computer analysis of the filters, including both varactor and integrated circuit loss, and the effects of tuning is presented. The measured performances of several practical devices, constructed in Suspended Substrate Stripline, and operating in the frequency range 2-10 GHz are presented, these agree closely with computed performances.

No description available.

In an ideal world, unwanted or undesirable effects in a system could and would be completely ignored. In fact, this was the case in mid-80s' PC design when an 80286 microprocessor running at a "blazing" 12 MHz was considered leading-edge technology. As technology continued to push the envelope and ever-faster designs were realized, more demanding software packages were developed and utilized efficiently. These increasingly sophisticated software packages in turn allowed designers of all disciplines to test systems of escalating complexity. These more complex models placed a heavier burden on the hardware, prompting a push for better and faster hardware designs. The cycle repeats to this day. As such, we are now in an environment where a 1 GHz microprocessor is considered somewhat dated. More importantly, whereas a small 1 nH (1 billionth of a Henry) inductance in a power delivery path was considered inconsequential a decade ago, it is now a barrier to implementing a design. Similarly, the equivalent series inductance (ESL) of a capacitor plays an increasing (and detrimental) role in the behavior and design of today's VRM (Voltage Regulator Module) design. In fact, it is the ESL of the capacitor that hinders proper voltage regulation at high frequencies by increasing the output impedance beyond a desired level. This dilemma has been recognized and several topologies have been proposed to overcome this problem. One category is improved passive devices, with the latest involving array capacitors to achieve near-zero ESL. As passive devices are almost always preferable to active solutions due to their lower losses, these technologies hold great promise, though they are inherently limited in small-footprint applications. A second category is the addition of active devices, which involves the use of some filtering technique to inject or absorb current during a fast transient by the use of semiconductor switches connected to a power source. These switching-state topologies have been shown to be prone to unstable oscillations, often caused by over-reactions or over-corrections of one transient prompting the opposite switch to engage its power source. The research goal is to develop a methodology to use active filters to more-seamlessly extend the control bandwidth of today's VRM technology. A hybrid active power filter is developed which uses bipolar junction transistors (BJT) in the forward-active region to connect a power supply source to the microprocessor. In this way, the switches are used in a way analogous to a dimmer switch (vs. simply 'on' or 'off'). By proper design of the compensator in the feedback loop, the active power filter can be used to suppress transients in any desired frequency range, limited only by the amplifier's current rating and bandwidth. The compensator design's derivation shows the relationship to the output impedance of the active filter. In essence, we are 'designing' a capacitor with a very low ESL, having more desirable output impedance vs. frequency relationship than either a capacitor, or a more complicated VRM with an extended bandwidth. Using this design, however, at very high frequencies (i.e., approaching 1 GHz, or one trillion cycles per second) requires state-of-the-art packaging designs to limit unwanted impedances, and also an ultra-wide GHz bandwidth, high-current operational amplifier. Both of these barriers are outside the scope of this research. As is often the case in research efforts, we have not '˜solved' the problem, but have shifted it to a frequency range where the effect isn't problematic. Experimental results show the use of a hybrid power filter with a VRM with Adaptive Voltage Positioning (AVP) can significantly suppress voltage undershoot during fast transient load current changes. In addition, the design is modified to reduce and possibly eliminate bulk output capacitors. This provides a promising alternative to a Voltage Regulator Module with a very high control bandwidth. Lastly, simulations give an estimate of the required IC design to use an APF to augment packaging capacitors. / Master of Science

The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University was awarded a project to study the feasibility of measuring particulate matter downstream of a high efficiency particulate air (HEPA) filter by testing commercially available equipment used to monitor the downstream side of a HEPA filter. In order to perform the work required for this project, a test stand to accommodate a 12? x 12? x 11.5? HEPA filter with a rated flow of 250 standard cubic feet per minute (scfm) was constructed. The test stand required an aerosol generator capable of producing a mass loading rate of 30 mg/m3 of dry aerosol at the face of the HEPA filter. It was determined that there was not a commercially available aerosol generator that quite fit the needs of the project. Therefore, it was necessary to develop an aerosol generator with the capabilities required for the project.

No description available.

No description available.