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Parameter Estimation of Microwave Filters

Description: The focus of this thesis is on developing theories and techniques to extract lossy microwave filter parameters from data. In the literature, the Cauchy methods have been used to extract filters’ characteristic polynomials from measured scattering parameters. These methods are described and some examples are constructed to test their performance. The results suggest that the Cauchy method does not work well when the Q factors representing the loss of filters are not even. Based on some prototype filters and the relationship between Q factors and the loss, we conduct preliminary studies on alternative representations of the characteristic polynomials. The parameters in these new models are extracted using the Levenberg–Marquardt algorithm to accurately estimate characteristic polynomials and the loss information.
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Date: December 2015
Creator: Sun, Shuo
Partner: UNT Libraries

Design of a Tunable High-Q Superconducting Notch Filter

Description: The design of a tunable high-Q superconducting notch filter is presented. The filter is designed to be manufactured from high Tc superconductors (Nb3S, Nb3Ge) made by high-rate magnetron sputtering on sapphire substrates. The geometry of the various elements, holder materials for the cryostat, studies relating to the preparation of suitable high Tc materials, and the photo-etching procedures for the filter elements are discussed.
Date: October 1978
Creator: Falco, Charles M.; Kampwirth, R. T.; Pang, C. S. & Schuller, Ivan K.
Partner: UNT Libraries Government Documents Department

Recent applications of bandpass filtering

Description: Bandpass filtering has been applied recently in two widely different seismic applications: S.R. Taylor and A.A. Velasco in their source-path amplitude-correction (SPAC) algorithm and N.K. Yacoub in his maximum spectral energy algorithm for picking teleseismic P-wave arrival times. Though the displacement spectrum is the intermediate product in both cases, the filters and scaling corrections used to estimate it are entirely different. They tested both and found that the scaling used by Taylor and Velasco worked in all cases tested whereas Yacoub's did not. They also found that bandpass filtering as implemented by Taylor and Velasco does not work satisfactorily; however, the Gaussian filter used by Yacoub does work. The bandpass filter of Taylor and Velasco works satisfactorily when the results are centered in the band; however, a comb filter with the same number of poles and zeros as the bandpass used by Taylor and Velasco works better than the bandpass filter.
Date: March 15, 1999
Creator: Denny, M D
Partner: UNT Libraries Government Documents Department

Clarification of Redox Feed (1AF) by Filtration : A Semi-Works Study Progress, Redox Technical Data Study No. 8

Description: The following report was made to determine the effective clarity improvement, flow rate characteristics, and operational problems encountered on passing Redox uranium feed solution through sintered, modified Type 304 stainless steel filter elements.
Date: October 15, 1948
Creator: Cooper, V. R. & Coleman, E. M.
Partner: UNT Libraries Government Documents Department

Spatial filter issues

Description: Beamlet measurements show that cone pinholes outperform other types tested with regard to both closure and back reflections. A ±150 µrad stainless steel cone remained open for a 15.5 kJ, 10:1 contrast shaped pulse with ±7.5 µrad of SSD divergence, which more than meets the requirements for a NIF ignition pulse. Measurements also showed the maximum tolerable pressures in the NIF spatial filters to be a few milliTorr, leading to recommendations of 0.1 and 0.6 mTorr for the NIF transport and cavity spatial filters, respectively.
Date: July 23, 1998
Creator: Boley, C. D.; Bonneau, F.; Estabrook, K. G.; Milam, D. & Murray, J. E.
Partner: UNT Libraries Government Documents Department

ITP Filtrate Benzene Removal Alternatives

Description: Existing ITP filtrate hold tanks may provide sufficient capacity and residence time to strip dissolved benzene from the incoming filtrate using nitrogen sparging in the bottom of the old tanks. This is based on equilibrium supported by late Wash test data using aged washed slurry. Theoretical considerations indicate that benzene stripping will be more difficult from the ITP unwashed high salt filtrates due to reduced mass transfer. Therefore experimental sparging data is needed to quantify the theoretical effects.Foaming limits which dictate allowable sparging rate will also have to be established. Sparging in the hold tanks will require installation of sintered metal spargers, and possibly stirrers and foam monitoring/disengagement equipment. The most critical sparging needs are at the start of the precipitation/concentration cycle, when the filtrate flux rate is the highest,and at the end of wash cycle where Henry`s equilibrium constant falls off,requiring more gas to sparge the dissolved benzene. With adequate recycle (for proper distribution) or sparging in the old tanks, the 30 inch column could be used for the complete ITP process. A courser packing would reduce back pressure while enabling benzene stripping. The Late Wash Tests indicate adequate benzene stripping even at reduced gas flow. This will require experimental verification under ITP conditions. Using the 30 in. column vs 18 in. during the wash cycle will enhance stripping without need for additional sparging provided the minimum flow requirements are met.
Date: May 21, 1993
Creator: Dworjanyn, L.O.
Partner: UNT Libraries Government Documents Department

Electric filter with movable belt electrode

Description: A method and apparatus are disclosed for removing airborne contaminants entrained in a gas or airstream. The apparatus includes an electric filter characterized by a movable endless belt electrode, a grounded electrode, and a filter medium sandwiched therebetween. Inclusion of the movable, endless belt electrode provides the driving force for advancing the filter medium through the filter, and reduces frictional drag on the filter medium, thereby permitting a wide choice of filter medium materials. Additionally, the belt electrode includes a plurality of pleats in order to provide maximum surface area on which to collect airborne contaminants.
Date: February 23, 1982
Creator: Bergman, W.
Partner: UNT Libraries Government Documents Department

TESTING AND EVALUATION OF THE MODIFIED DESIGN OF THE 25-DISK ROTARY MICROFILTER

Description: This report details redesign of a commercially available rotary microfilter to meet the operational and maintenance requirements for radioactive service. Personnel developed the design and coordinated procurement of two filters followed by testing of one unit. System testing examined the ability to rinse soluble material from the system, filtration performance using several insoluble solids loadings, effectiveness in washing sludge, amount of wear to parts and maintenance of the system including the insertion and removal of the filter stack, and the ability to flush solids from the system. The test program examined flushing the filter for soluble material by filling the system with a Rhodamine WT dye solution. Results showed that draining the system and rinsing with 50 gallons of water resulted in grater than 100X reduction of the dye concentration. Personnel determined filter performance using various amounts of insoluble sludge solids ranging from 0.06 to 15 weight percent (wt%) insoluble solids in a 3 molar (M) sodium simulated supernate. Through approximately 120 hours of start-and-stop (i.e., day shift) operation and various insoluble solids loadings, the filter produced filtration rates between 3 and 7 gallons per minute (gpm) (0.12-0.29 gpm/ft{sup 2}) for a 25-disk filter. Personnel washed approximately 80 gallons of simulated sludge using 207 gallons of inhibited water. Washing occurred at constant volume with wash water fed to a well mixed tank at the same rate as filtrate removal. Performance measurement involved collecting and analyzing samples throughout the washing for density and sodium content. Results showed an effective washing, mimicking a predicted dilution calculation for a well mixed tank and reducing the sodium concentration from 3.2 M to less than 0.3 M. Filtration rates during the washing process ranged between 3 and 4.3 gpm for one filter unit. The filter system then concentrated the washed 15 wt% insoluble solids slurry ...
Date: September 29, 2006
Creator: Herman, D; Michael Poirier, M & Samuel Fink, S
Partner: UNT Libraries Government Documents Department

Filter Media Recommendation Review

Description: The original filter recommended by PNNL for the RASA is somewhat difficult to dissolve and has been discontinued by the manufacturer (3M) because the manufacturing process (substrate blown microfiber, or SBMF) has been superceded by a simpler process (scrim-free blown microfiber, or BMF). Several new potential filters have been evaluated by PNNL and by an independent commercial lab. A superior product has been identified which provides higher trapping efficiency, higher air flow, is easier to dissolve, and is thinner, accommodating more filters per RASA roll. This filter is recommended for all ground-based sampling, and with additional mechanical support, it could be useful for airborne sampling, as well.
Date: January 7, 2002
Creator: Thompson, Robert C.; Miley, Harry S. & Arthur, Richard J.
Partner: UNT Libraries Government Documents Department