Load compensation techniques using multi-tapped potentiometers

The theory is developed for loading error compensation techniques utilising multi-tapped potentiometers. Two methods of compensation are derived, and their relative advantages discussed. Design formulae are given for calculating appropriate values of the shunt resistors to be used in association with the tapped potentiometers. Numerical examples of each method are given

Identification of Management and Planning Problems of Urban Water Resources in the Metropolitan Area of Greater San Antonio

This interim report describes the research performed to date on Project A-017-TEX sponsored by the U. S. Department of Interior Office of Water Resources Research and the Texas A&M University Texas Water Resources Institute. The research reported herein describes the region Encompassed by the San Antonio river basin. Included in the description is a brief summary of the regional economy, demography, and geographical characteristics. Additionally, the quantitative and qualitative information including the inventory and planning control for both surface and ground Water Resource Management of the San Antonio area are presented. Emphasis has been placed upon the identification of the probabilistic nature of various decision-making parameters of Urban Water Resources Management. The methodogies and techniques for the handling of specific problems are being developed and will be presented in the project completion report. Appreciation is expressed to the Alamo Area Council of Governments and the Texas Water Development Board for their assistance in this research. Numerous graduate students contributed to this research. Chief among these is Miss Sharon Tu for her efforts in developing the San Antonio Data Retrieval Program. Special acknowledgement is given to Mr. John Little for his assistance in preparing the manuscript for publication. The cooperation of Dr. J. R. Runkles and the entire staff of the Texas Water Resources Institute is appreciated. Finally, a special thanks to Mrs. Cynthia Fong for her diligent effort in typing the manuscript

Improving the performance of GPR based landmine detection through fusion [abstract]

Abstract only availableThroughout the twentieth century, landmines have been used to inhibit the movement of military troops and vehicles. Traditionally, metal detectors have been used to effectively detect these mines. However, today, many varieties of mines are plastic-cased and contain little or no metal content, making traditional detection methods ineffective. For both military and humanitarian de-mining, a practical and reliable detection method is needed. In response to this need, several alternative detection technologies are being developed. These modern technologies are faced with the challenge of distinguishing buried non-metallic mines from rocks and other geological clutter. They also have to be capable of operating under a variety of environmental and soil conditions. One such technology being developed is ground penetrating radar (GPR). By transmitting high frequency electromagnetic pulses into the ground and analyzing the reflected signals with a detection algorithm, both metallic and non-metallic mines can be identified with relatively high success. However, a tradeoff occurs when trying to maximize the detection rate: as the sensitivity of the detection algorithm is increased, the number of false alarms is also increased. Having a high detection rate is crucial to the reliability of the detection system, but having a high false alarm rate makes it impractical to use. The goal of this research is to optimize both of these factors, by statistically correlating the results of multiple detection algorithms and fusing their confidence outputs together. By incorporating multiple algorithms in the detection process, the benefits of the individual algorithms can be coalesced to improve the overall detection and false alarm rates.College of Engineering Undergraduate Research Optio

Heat pipes for wing leading edges of hypersonic vehicles

Wing leading edge heat pipes were conceptually designed for three types of vehicle: an entry research vehicle, aero-space plane, and advanced shuttle. A full scale, internally instrumented sodium/Hastelloy X heat pipe was successfully designed and fabricated for the advanced shuttle application. The 69.4 inch long heat pipe reduces peak leading edge temperatures from 3500 F to 1800 F. It is internally instrumented with thermocouples and pressure transducers to measure sodium vapor qualities. Large thermal gradients and consequently large thermal stresses, which have the potential of limiting heat pipe life, were predicted to occur during startup. A test stand and test plan were developed for subsequent testing of this heat pipe. Heat pipe manufacturing technology was advanced during this program, including the development of an innovative technique for wick installation

Permutation combinatorics of worldsheet moduli space

52 pages, 21 figures52 pages, 21 figures; minor corrections, "On the" dropped from title, matches published version52 pages, 21 figures; minor corrections, "On the" dropped from title, matches published versio

S-, P- and D-wave resonances in positronium-sodium and positronium-potassium scattering

Scattering of positronium (Ps) by sodium and potassium atoms has been investigated employing a three-Ps-state coupled-channel model with Ps(1s,2s,2p) states using a time-reversal-symmetric regularized electron-exchange model potential fitted to reproduce accurate theoretical results for PsNa and PsK binding energies. We find a narrow S-wave singlet resonance at 4.58 eV of width 0.002 eV in the Ps-Na system and at 4.77 eV of width 0.003 eV in the Ps-K system. Singlet P-wave resonances in both systems are found at 5.07 eV of width 0.3 eV. Singlet D-wave structures are found at 5.3 eV in both systems. We also report results for elastic and Ps-excitation cross sections for Ps scattering by Na and K.Comment: 9 pages, 5 figures, Accepted in Journal of Physics

Critical role for Piccolo in synaptic vesicle retrieval

Loss of function of the presynaptic active zone protein Piccolo has recently been linked to a devastating disease causing brain atrophy. Here, we address how Piccolo inactivation adversely affects synaptic function and thus may contributes to neuronal loss. Our analysis shows that Piccolo is critical for the activity dependent recycling and maintenance of synaptic vesicles (SVs). Specifically, we find that boutons lacking Piccolo have deficits in the Rab5/EEA1 dependent formation of early endosomes and thus the recycling of SVs. Mechanistically, impaired Rab5 function was caused by the reduced synaptic recruitment of Pra1, known to interact selectively with the zinc fingers of Piccolo. Importantly, over-expression of GTPase deficient Rab5 or the Znf1 domain of Piccolo restores the size and recycling of SV pools. These data provide a molecular link between the active zone and endosome sorting at synapses providing hints to how Piccolo contributes to both developmental and psychiatric disorders

Identification of Water Resources Planning Problems in the Metropolitan Area of Greater San Antonio and its Associated Counties

Growth in population and economic activity has been accepted as the essential elements of American life for almost two centuries. Since the beginning of the seventies, we have begun to concern ourselves with the quality of this growth. Meanwhile, modern civilization has created the high concentration in urban areas, the enormous inflation of resources consumption and the consequent increase of production requirements. Unfortunately, all these phenomena also became the driving force for the acceleration of waste generation and resources depletion. The development of the San Antonio metropolitan area has followed the same pattern as that of other urban areas in the United States. It has become the largest metropolitan area primarily depending upon groundwater for its water supply. The availability of water has also played a most important role in shaping the history and development of the San Antonio area and its vicinity. Along with age of this metropolitan area, multiplicity of governments, planning agencies, river authorities and interest groups in water resources management have evolved into a complicated system in this area. Thus, it was realized that an overview embedded with the systems approach for the current water resources problems is needed. However, the total spectrum of problems would be enormous and the analysis phase must then be concentrated on one of the most urgent problems. The primary objective of this study as reported herein is to give overview of the current status of different aspects of urban water. resources management in the San Antonio area. Special emphasis has been placed upon handling of water quantity and quality data and analysis of regional water quality of the San Antonio River. Specific investigations which have been conducted are as follows: 1. Identification of basic managerial problems for the urban water resources management in the San Antonio area. 2. Development of information storage and retrieval programs for quality and quantity. 3. Development of a mathematical model describing the variability ofregional water quality of San Antonio River Basin. There are three distinct parts in this report. The first part describes urban water resources management components in San Antonio (Chapters II and III). The second part describes the information retrieval programs developed in this project (Chapter IV), and the third part concentrates on the development of a regional water quality reliability analysis model and its implications

Invasive North American bullfrogs transmit lethal fungus Batrachochytrium dendrobatidis infections to native amphibian host species

Invasive species can be a threat to native species in several ways, including transmitting lethal infections caused by the parasites they carry. However, invasive species may also be plagued by novel and lethal infections they acquire when invading, making inferences regarding the ability of an invasive host to vector disease difficult from field observations of infection and disease. This is the case for the pathogenic fungus Batrachochytrium dendrobatidis (Bd) in Europe and one invasive host species, the North American bullfrog Lithobates catesbeianus, hypothesized to be responsible for vectoring lethal infection to European native amphibians. We tested this hypothesis experimentally using the alpine newt Ichthyosaura alpestris as our model native host. Our results show that infected bullfrog tadpoles are effective vectors of Bd. Native adult newts co-housed with experimentally infected bullfrog tadpoles became Bd infected (molecular and histological tests). Moreover, the exposed adult newts suffered mortality while the majority of infected bullfrog tadpoles survived until metamorphosis. Invasive species can be a threat to native species in several ways, including transmitting lethal infections caused by the parasites they carry. However, invasive species may also be plagued by novel and lethal infections they acquire when invading, making inferences regarding the ability of an invasive host to vector disease difficult from field observations of infection and disease. This is the case for the pathogenic fungus Batrachochytrium dendrobatidis (Bd) in Europe and one invasive host species, the North American bullfrog Lithobates catesbeianus, hypothesized to be responsible for vectoring lethal infection to European native amphibians. We tested this hypothesis experimentally using the alpine newt Ichthyosaura alpestris as our model native host. Our results show that infected bullfrog tadpoles are effective vectors of Bd. Native adult newts co-housed with experimentally infected bullfrog tadpoles became Bd infected (molecular and histological tests). Moreover, the exposed adult newts suffered mortality while the majority of infected bullfrog tadpoles survived until metamorphosis. These results cannot resolve the historical role of alien species in establishing the distribution of Bd across Europe or other regions in the world where this species was introduced, but they show its potential role as a Bd reservoir capable of transmitting lethal infections to native amphibians. Finally, our results also suggest that the removal of infected bullfrogs from aquatic environments may serve to reduce the availability of Bd in European amphibian communities, offering another justification for bullfrog eradication programmes that are currently underway or may be considere