27 Matching Results

Search Results

Advanced search parameters have been applied.

An example of a digital synthesis approach to DSP design: The AGS transverse damper

Description: Using Verilog HDL and Synopsys, the digital signal processing of the AGS Transverse Damper was designed and fitted to an Altera Flex l0k FPGA. Using a control point specification style in the high level description greatly simplified the design by placing the burden of specifying the controller on the digital synthesizer. The basic design and low level simulation are presented as well as the design methodology. The purpose of the AGS Transverse Damper is to control instabilities and injection errors that may arise in high intensity proton beams being accelerated in the AGS. The system block diagram for the DSP is shown in Figure 1. The inputs to the system come from a normalization unit. This normalization unit takes two signals as input, a sum of beam position signal plates, and a difference from the plates. The output of the normalization unit is the difference divided by the sum. This Quotient is sent to the first ALU (as Qin[11..0]). Taking differences between position measurements the system acts as a notch filter. The Second ALU computes a running sum of the output of the first ALU. This then acts to remove any offsets in the Quotient (and thus this part acts as a high pass filter - removing any baseline components to the signal). The depth of the first FIFO (between adder and subtract units) basically determines the low pass behaviour. The multiplier serves the purpose of overall loop gain for the system (the complete system is a real-time feedback system). The FIFO on the output is used to provide the correct amount of delay for the system.
Date: July 1, 1997
Creator: Brown, K.A.; Smith, G. & Wong, V.
Partner: UNT Libraries Government Documents Department

Assigning functional meaning to digital circuits

Description: During computer-aided design, the problem of how to determine the logical function of a digital circuit arises in many contexts. For example, assigning functional meaning to a circuit is a fundamental operation in both reverse engineering and implementation validation. This report describes such a determination by discussing how a higher-level functional representation is constructed from a detailed circuit description (i.e., a gate-level netlist, which is a list of logic gates and their interconnections). The approach used involves transforming parts of the netlist into a functional representation and then manipulating this representation. Two types of functional representations are described: (1) a mathematical representation based on the logical operators ``exor`` and ``and`` and (2) a directed acyclic graph representation based on binary decision trees. Each representation provides a canonical form of the logical function being implemented (i.e., a form that is independent of implementation details). Such forms, however, have a well-known problem associated with the ordering of inputs: for each order, a unique form exists. A solution to this problem is given for both representations. Experimental results that demonstrate the use of these representations in the process of assigning functional meaning to a circuit are provided. The report also identifies and discusses issues critical to the performance required of this fundamental operation.
Date: July 1, 1997
Creator: Eckmann, S.T. & Chisholm, G.H.
Partner: UNT Libraries Government Documents Department

Effects of smoke on functional circuits

Description: Nuclear power plants are converting to digital instrumentation and control systems; however, the effects of abnormal environments such as fire and smoke on such systems are not known. There are no standard tests for smoke, but previous smoke exposure tests at Sandia National Laboratories have shown that digital communications can be temporarily interrupted during a smoke exposure. Another concern is the long-term corrosion of metals exposed to the acidic gases produced by a cable fire. This report documents measurements of basic functional circuits during and up to 1 day after exposure to smoke created by burning cable insulation. Printed wiring boards were exposed to the smoke in an enclosed chamber for 1 hour. For high-resistance circuits, the smoke lowered the resistance of the surface of the board and caused the circuits to short during the exposure. These circuits recovered after the smoke was vented. For low-resistance circuits, the smoke caused their resistance to increase slightly. A polyurethane conformal coating substantially reduced the effects of smoke. A high-speed digital circuit was unaffected. A second experiment on different logic chip technologies showed that the critical shunt resistance that would cause failure was dependent on the chip technology and that the components used in the smoke exposures were some of the most smoke tolerant. The smoke densities in these tests were high enough to cause changes in high impedance (resistance) circuits during exposure, but did not affect most of the other circuits. Conformal coatings and the characteristics of chip technologies should be considered when designing circuitry for nuclear power plant safety systems, which must be highly reliable under a variety of operating and accident conditions. 10 refs., 34 figs., 18 tabs.
Date: October 1997
Creator: Tanaka, T. J.
Partner: UNT Libraries Government Documents Department

Validation of an FPGA fault simulator.

Description: This work describes the radiation testing of a fault simulation tool used to study the behavior of FPGA circuits in the presence of configuration memory upsets . There is increasing interest in the use of Field Programmable Gate Arrays (FPGAs) in space-based applications such as remote sensing[1] . The use of reconfigurable Field Programmable Gate Arrays (FPGAs) within a spacecraft allows the use of digital circuits that are both application-specific and reprogrammable. Unlike application-specific integrated circuits (ASICs), FPGAs can be configured after the spacecraft has been launched . This flexibility allows the same FPGA resources to be used for multiple instruments, missions, or changing spacecraft objectives . Errors in an FPGA design can be resolved by fixing the incorrect design and reconfiguring the FPGA with an updated configuration bitstream . Further, custom circuit designs can be created to avoid FPGA resources that have failed during the course of the spacecraft mission .
Date: January 1, 2003
Creator: Wirthlin, M. J. (Michael J.); Johnson, D. E. (Darrel Eric); Graham, P. S. (Paul S.) & Caffrey, M. P. (Michael Paul)
Partner: UNT Libraries Government Documents Department

Circuit bridging of digital equipment caused by smoke from a cable fire

Description: Advanced reactor systems are likely to use protection systems with digital electronics that ideally should be resistant to environmental hazards, including smoke from possible cable fires. Previous smoke tests have shown that digital safety systems can fail even at relatively low levels of smoke density and that short-term failures are likely to be caused by circuit bridging. Experiments were performed to examine these failures, with a focus on component packaging and protection schemes. Circuit bridging, which causes increased leakage currents and arcs, was gauged by measuring leakage currents among the leads of component packages. The resistance among circuit leads typically varies over a wide range, depending on the nature of the circuitry between the pins, bias conditions, circuit board material, etc. Resistance between leads can be as low as 20 k{Omega} and still be good, depending on the component. For these tests, the authors chose a printed circuit board and components that normally have an interlead resistance above 10{sup 12} {Omega}, but if the circuit is exposed to smoke, circuit bridging causes the resistance to fall below 10{sup 3} {Omega}. Plated-through-hole (PTH) and surface-mounted (SMT) packages were exposed to a series of different smoke environments using a mixture of environmentally qualified cables for fuel. Conformal coatings and enclosures were tested as circuit protection methods. High fuel levels, high humidity, and high flaming burns were the conditions most likely to cause circuit bridging. The inexpensive conformal coating that was tested - an acrylic spray - reduced leakage currents, but enclosure in a chassis with a fan did not. PTH packages were more resistant to smoke-induced circuit bridging than SMT packages. Active components failed most often in tests where the leakage currents were high, but failure did not always accompany high leakage currents.
Date: March 1, 1997
Creator: Tanaka, T.J. & Anderson, D.J.
Partner: UNT Libraries Government Documents Department

Larger bases and mixed analog/digital neural nets

Description: The paper overviews results dealing with the approximation capabilities of neural networks, and bounds on the size of threshold gate circuits. Based on an explicit numerical algorithm for Kolmogorov`s superpositions the authors show that minimum size neural networks--for implementing any Boolean function--have the identity function as the activation function. Conclusions and several comments on the required precision are ending the paper.
Date: December 31, 1998
Creator: Beiu, V.
Partner: UNT Libraries Government Documents Department

Optimal neural computations require analog processors

Description: This paper discusses some of the limitations of hardware implementations of neural networks. The authors start by presenting neural structures and their biological inspirations, while mentioning the simplifications leading to artificial neural networks. Further, the focus will be on hardware imposed constraints. They will present recent results for three different alternatives of parallel implementations of neural networks: digital circuits, threshold gate circuits, and analog circuits. The area and the delay will be related to the neurons` fan-in and to the precision of their synaptic weights. The main conclusion is that hardware-efficient solutions require analog computations, and suggests the following two alternatives: (i) cope with the limitations imposed by silicon, by speeding up the computation of the elementary silicon neurons; (2) investigate solutions which would allow the use of the third dimension (e.g. using optical interconnections).
Date: December 31, 1998
Creator: Beiu, V.
Partner: UNT Libraries Government Documents Department

Technical Progress Report for PEPCO: Turbo-Z Battery Charging System

Description: The authors are entering the final phase of development for this project. Work has been imparted to define the components of the flexible battery charger control board. Detailed analog and digital circuits are complete. Improved analog to digital and digital to analog converters have been selected for use with the control board. The control board schematics are complete and construction of the hardware is in progress. The programming of the circuit board modules is underway. The documentation and circuit schematic drawings are in process. The test stand has added the integration of a dedicated fast computer/microprocessor to control the test stand. This will allow measurements to be taken and recorded more often. This has required modification of the software. The software is being debugged. The modules to be controlled by the test stand microprocessor include the charger module, the battery simulator, the discharge pulse, and discharger. Integrating these components will greatly enhance design and testing. An SCR charger power module has been has been designed, built, and debugged. The circuits for the battery simulator and discharge pulse have been detailed and debugged. The discharge pulse characteristics have been defined and designed. The charger power and discharge pulse modules can be used with either the test stand or the flexible control board. This work is the result of extensive catalog and internet research for the test stand and control board components. The documentation for the project is underway. It is important to have this documentation for reference purposes. Also, the drawing schematics will help with future projects, and they will help with flow-charting the projects for all parties involved. The drawings and some output parameters as of June 1999 are attached.
Date: July 22, 1999
Partner: UNT Libraries Government Documents Department

Preliminary studies on the impact of smoke on digital equipment

Description: Last year the USNRC initiated a program at Sandia National Laboratories to determine the potential impact of smoke on advanced safety-related digitial instrumentation. In recognition of the fact that the reliability of safety-related equipment during or shortly after a fire in a nuclear power plant is more risk significant than long-term effects, we are concentrating on short-term failures. We exposed a multiplexer module board to three different types of smoke to determine whether the smoke would affect its operation. The operation of the multiplexer board was halted by one out of the three smoke exposures. In coordination with Oak Ridge National Laboratory, an experimental digital safety system was also smoke tested. The series of tests showed that smoke can cause potentially serious failures of a safety system. Most of these failures were intermittent and showed that smoke can temporarily interrupt communication between digital systems.
Date: December 1, 1995
Creator: Tanaka, T.J.; Korsah, K. & Antonescu, C.
Partner: UNT Libraries Government Documents Department

Digital signal processing for beam position feedback

Description: Stabilization of the particle beam position with respect to the focusing optics in the third generation synchrotron light sources is crucial to achieving low emittance and high brightness. For this purpose, global and local beam orbit correction feedbacks will be implemented in the APS storage ring. In this article, the authors discuss application of digital signal processing to particle/photon beam position feedback using the PID (proportional, integral, and derivative) control algorithm.
Date: April 1, 1992
Creator: Chung, Y.; Emery, L. & Kirchman, J.
Partner: UNT Libraries Government Documents Department

On automatic synthesis of analog/digital circuits

Description: The paper builds on a recent explicit numerical algorithm for Kolmogorov`s superpositions, and will show that in order to synthesize minimum size (i.e., size-optimal) circuits for implementing any Boolean function, the nonlinear activation function of the gates has to be the identity function. Because classical and--or implementations, as well as threshold gate implementations require exponential size, it follows that size-optimal solutions for implementing arbitrary Boolean functions can be obtained using analog (or mixed analog/digital) circuits. Conclusions and several comments are ending the paper.
Date: December 31, 1998
Creator: Beiu, V.
Partner: UNT Libraries Government Documents Department

Circuit bridging of components by smoke

Description: Smoke can adversely affect digital electronics; in the short term, it can lead to circuit bridging and in the long term to corrosion of metal parts. This report is a summary of the work to date and component-level tests by Sandia National Laboratories for the Nuclear Regulatory Commission to determine the impact of smoke on digital instrumentation and control equipment. The component tests focused on short-term effects such as circuit bridging in typical components and the factors that can influence how much the smoke will affect them. These factors include the component technology and packaging, physical board protection, and environmental conditions such as the amount of smoke, temperature of burn, and humidity level. The likelihood of circuit bridging was tested by measuring leakage currents and converting those currents to resistance in ohms. Hermetically sealed ceramic packages were more resistant to smoke than plastic packages. Coating the boards with an acrylic spray provided some protection against circuit bridging. The smoke generation factors that affect the resistance the most are humidity, fuel level, and burn temperature. The use of CO{sub 2} as a fire suppressant, the presence of galvanic metal, and the presence of PVC did not significantly affect the outcome of these results.
Date: October 1, 1996
Creator: Tanaka, T.J.; Nowlen, S.P. & Anderson, D.J.
Partner: UNT Libraries Government Documents Department

360/sup 0/ digital phase detector with 100-kHz bandwidth

Description: The general availability of digital circuit components with propagation delay times of a few nanoseconds makes a digital phase detector with good bandwidth feasible. Such a circuit has a distinct advantage over its analog counterpart because of its linearity over wide range of phase shift. A phase detector that is being built at Los Alamos National Laboratory for the Fusion Materials Irradiation Test (FMIT) project is described. The specifications are 100-kHz bandwidth, linearity of +- 1/sup 0/ over +- 180/sup 0/ of phase shift, and 0.66/sup 0/ resolution. To date, the circuit has achieved the bandwidth and resolution. The linearity is approximately +- 3/sup 0/ over +- 180/sup 0/ phase shift.
Date: January 1, 1981
Creator: Reid, D.W.; Riggin, D.; Fazio, M.V.; Biddle, R.S.; Patton, R.D. & Jackson, H.A.
Partner: UNT Libraries Government Documents Department

Compatibility Study of Protective Relaying in a Grid-Connected Fuel Cell

Description: A 200-kW fuel cell produced by International Fuel Cells (IFC), a United Technologies Company, began operation at the National Transportation Research Center (NTRC) in early June 2003. The NTRC is a joint Oak Ridge National laboratory (ORNL) and University of Tennessee research facility located in Knoxville, Tennessee. This research activity investigated the protective relaying functions of this fully commercialized fuel cell power plant, which uses ''synthesized'' protective relays. The project's goal is to characterize the compatibility between the fuel cell's interconnection protection system and the local distribution system or electric power system (EPS). ORNL, with assistance from the Electric Power Research Institute-Power Electronics Applications Center (EPRI-PEAC) in Knoxville, Tennessee, monitored and characterized the system compatibility over a period of 6 months. Distribution utility engineers are distrustful of or simply uncomfortable with the protective relaying and hardware provided as part of distributed generation (DG) plants. Part of this mistrust is due to the fact that utilities generally rely on hardware from certain manufacturers whose reliability is well established based on performance over many years or even decades. Another source of concern is the fact that fuel cells and other types of DG do not use conventional relays but, instead, the protective functions of conventional relays are simulated by digital circuits in the distributed generator's grid interface control unit. Furthermore, the testing and validation of internal protection circuits of DG are difficult to accomplish and can be changed by the vendor at any time. This study investigated and documented the safety and protective relaying present in the IFC fuel cell, collected data on the operation of the fuel cell, recorded event data during EPS disturbances, and assessed the compatibility of the synthesized protective circuits and the local distribution system. The project also addressed other important and timely issues. For instance, the study ...
Date: April 15, 2004
Creator: Staunton, R.H.
Partner: UNT Libraries Government Documents Department

Power electronics system modeling and simulation

Description: This paper introduces control system design based softwares, SIMNON and MATLAB/SIMULINK, for power electronics system simulation. A complete power electronics system typically consists of a rectifier bridge along with its smoothing capacitor, an inverter, and a motor. The system components, featuring discrete or continuous, linear or nonlinear, are modeled in mathematical equations. Inverter control methods,such as pulse-width-modulation and hysteresis current control, are expressed in either computer algorithms or digital circuits. After describing component models and control methods, computer programs are then developed for complete systems simulation. Simulation results are mainly used for studying system performances, such as input and output current harmonics, torque ripples, and speed responses. Key computer programs and simulation results are demonstrated for educational purposes.
Date: December 31, 1994
Creator: Lai, Jih-Sheng
Partner: UNT Libraries Government Documents Department

A trellis-searched APC (adaptive predictive coding) speech coder

Description: In this paper we formulate a speech coding system that incorporates trellis coded vector quantization (TCVQ) and adaptive predictive coding (APC). A method for optimizing'' the TCVQ codebooks is presented and experimental results concerning survivor path mergings are reported. Simulation results are given for encoding rates of 16 and 9.6 kbps for a variety of coder parameters. The quality of the encoded speech is deemed excellent at an encoding rate of 16 kbps and very good at 9.6 kbps. 13 refs., 2 figs., 4 tabs.
Date: January 1, 1990
Creator: Malone, K.T. (Sandia National Labs., Albuquerque, NM (USA)) & Fischer, T.R. (Washington State Univ., Pullman, WA (USA). Dept. of Electrical and Computer Engineering)
Partner: UNT Libraries Government Documents Department

Triggering the LBL time projection chamber

Description: A fast digital trigger was built for the LBL Time Projection Chamber (TPC) installed in the PEP-4 detector at SLAC. The TPC is an innovative High Energy Physics detector which will provide particle identification from dE/dx information within the tracking volume. The TPC trigger uses discriminator signals from 2220 dE/dx wire channels to require a track of ionization in the TPC which originates from the colliding beam intersection region. The trigger processing is performed as the ionization drifts onto the proportional wires and is completed 17 ..mu..s after beam crossing. This report describes the basic operation of the TPC detector and its trigger; a pretrigger which uses prompt TPC information from the endcap region; and the electronic implementation. The trigger can be tested with realistic simulated patterns of ionization deposits in the TPC which are stored in local memories. Test results from electronic simulations and first results of a test with cosmic rays are shown.
Date: October 1, 1981
Creator: Ronan, M.; Millaud, J. & McGathen, T.
Partner: UNT Libraries Government Documents Department

Charged particle detector system for ISABELLE spectrometers

Description: A detector system combining the good time resolution and low dead time of PWC's and the good space resolution of drift chambers is proposed for use in ISABELLE spectrometers. Central to this detector is the development of two integrated electronic circuit systems. The detectors are described with special emphasis on the electronic systems. The detector system proposed will be capable of handling particle flux rates typical of conventional PWC's yet providing a spacial resolution of 100 ..mu..m. Another advantage is that a large area detector of such performance will become technically feasible as well as economicaly viable. The detector is a conventional narrow anode spacing drift chamber with field wires. A digital delay-time encoder circuit is used for readout.
Date: January 1, 1977
Creator: Platner, E.D.
Partner: UNT Libraries Government Documents Department

Research in radiation monitoring survey instrumentation. Final report

Description: Two low-power solid-state prototype readout units were developed, an LED display and a LCD display. This display output was in a bar-graph format, covering four-decades of information, with 10-segments per decade. The displays accept a frequency input, which is standardly available from several portable radiation-survey instruments. Both readout units will operate on two D-cell batteries (3.0 Volt), with a typical current drain requirement of 0.3 MA for the LED display and 30..mu..A for the LCD display. A wide-range electrometer circuit was also developed. The circuit covers an input current range from 10/sup -13/ A to 10/sup -8/ A. The output signal is a pulse whose frequency is directly proportional to input current. The circuit requires no high-megohm resistors, and is autoranging. Several candidate input amplifiers were analyzed and evaluated for use with the electrometer circuit.
Date: January 20, 1978
Creator: Blalock, T.V.; Kennedy, E.J.; Phillips, R.G. & Walker, E.W. Jr.
Partner: UNT Libraries Government Documents Department

Improved assembly processes for the Quartz Digital Accelerometer cantilever

Description: This report covers the development of improved assembly processes for the Quartz Digital Accelerometer cantilever. In this report we discuss improved single-assembly tooling, the development of tooling and processes for precision application of polyimide adhesive, the development of the wafer scale assembly procedure, and the application of eutectic bonding to cantilever assembly. 2 refs., 17 figs.
Date: July 1, 1990
Creator: Romero, A.M. & Gebert, C.T.
Partner: UNT Libraries Government Documents Department

IPF Temperature Control System

Description: The Internal Picket Fence (IPF) is made of a set of proportional wire tube chambers which sit inside the outer vacuum vessel of the 15' Bubble Chamber. Though they are covered with layers of super-insulation, they are partially exposed to the cryogenic system of the Bubble Chamber and the Bubble Chamber magnet. The chambers are, therefore, equipped with heaters designed to maintain them at a reasonable temperature. As the operating conditions of the bubble chamber are changed, particularly during warm-up and cool-down, it is necessary to control the power to the heaters dynamically. Due to the adverse conditions in the area and the number of chambers (96 cans), we decided to operate the heaters remotely with a computer control system. The IPF Temperature Control System consists of five basic sub-systems. A STD bus Z80 microprocessor system, a serial communication link, a temperature monitor, a heater controller and heater driver card. The separate sub-systems are described. Each chamber has a 4-wire platinum resistor (RTD, R = 100 ohms at 0'C) and a 220 ohm resistance wire heater for temperature readback and control.
Date: December 1, 1985
Creator: Mangene, C.
Partner: UNT Libraries Government Documents Department

Pocket neutron REM meter

Description: This paper describes a pocket-calculator-sized, neutron-sensitive, REM-responding personnel dosimeter that uses three tissue-equivalent cylindrical proportional counters as neutron-sensitive detectors. These are conventionally called Linear Energy Transfer (LET) counters. Miniaturized hybrid circuits are used for the linear pulse handling electronics, followed by a 256-channel ADC. A CMOS microprocessor is used to calculate REM exposure from the basic rads-tissue data supplied by the LET counters and also to provide timing and display functions. The instrument is used to continuously accumulate time in hours since reset, total counts accumulated, rads-tissue, and REM. The user can display any one of these items or a channel number (an aid in calibration) at any time. Such data are provided with a precision of +- 3% for a total exposure of 1 mREM over eight hours.
Date: January 1, 1982
Creator: Quam, W.; Del Duca, T.; Plake, W.; Graves, G.; DeVore, T. & Warren, J.
Partner: UNT Libraries Government Documents Department

High resolution ADC interface to main magnet power supply at the NSLS

Description: Previous readings of DCCT were limited to 11 bits of resolution with large offsets and drifts, providing inaccurate data. The current design overcomes this limitation by using Analog Device's AD7703 20 bit serial output ADC to digitize the main magnet DCCT at the power supply, and transmit the data serially at 2KHz over to the VME controller.
Date: January 1, 1993
Creator: Bordoley, M.
Partner: UNT Libraries Government Documents Department