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Single SQUID frequency-domain multiplexer for large bolometer arrays

Description: We describe the development of a frequency-domain superconducting quantum interference device (SQUID) multiplexer which monitors a row of low-temperature sensors simultaneously with a single SQUID. Each sensor is ac biased with a unique frequency and all the sensor currents are added in a superconducting summing loop. A single SQUID measures the current in the summing loop, and the individual signals are lock-in detected after the room temperature SQUID electronics. The current in the summing loop is nulled by feedback to eliminate direct crosstalk. We have built an eight-channel prototype and demonstrated channel separation and signal recovery.
Date: August 20, 2001
Creator: Yoon, Jongsoo; Clarke, John; Gildemeister, J.M.; Lee, Adrian T.; Myers, M.J.; Skidmore, J.T. et al.
Partner: UNT Libraries Government Documents Department

Single SQUID multiplexer for arrays of voltage-biased superconducting bolometers

Description: We describe a frequency domain superconducting quantum interference device (SQUID) multiplexer which monitors a row of low-temperature sensors simultaneously with a single SQUID. Each sensor is ac biased with a unique frequency and all the sensor currents are added in a superconducting summing loop. A single SQUID measures the current in the summing loop, and the individual signals are lock-in detected after the room temperature SQUID electronics. The current in the summing loop is nulled by feedback to eliminate direct crosstalk. In order to avoid the accumulation of Johnson noise in the summing loop, a tuned bandpass filter is inserted in series with each sensor. For a 32-channel multiplexer for Voltage-biased Superconducting Bolometer (VSB) with a time constant {approx}1msec, we estimate that bias frequencies in the range from {approx}500kHz to {approx}600kHz are practical. The major limitation of our multiplexing scheme is in the slew rate of a readout SQUID. We discuss a ''carrier nulling'' technique which could be used to increase the number of sensors in a row or to multiplex faster bolometers by reducing the required slew rate for a readout SQUID.
Date: August 20, 2001
Creator: Yoon, Jongsoo; Clarke, John; Gildemeister, J.M.; Lee, Adrian T.; Myers, M.J.; Richards, P.L. et al.
Partner: UNT Libraries Government Documents Department

Gigabit network technology. Final technical report

Description: Current digital networks are evolving toward distributed multimedia with a wide variety of applications with individual data rates ranging from kb/sec to tens and hundreds of Mb/sec. Link speed requirements are pushing into the Gb/sec range and beyond the envelop of electronic networking capabilities. There is a vast amount of untapped bandwidth available in the low-attenuation communication bands of an optical fiber. The capacity in one fiber thread is enough to carry more than two thousand times as much information as all the current radio and microwave frequencies. And while fiber optics has replaced copper wire as the transmission medium of choice, the communication capacity of conventional fiber optic networks is ultimately limited by electronic processing speeds.
Date: October 1, 1996
Creator: Davenport, C.M.C.
Partner: UNT Libraries Government Documents Department

Multi-mode fiber coarse WDM grating router using broadband add/drop filters for wavelength re-use

Description: For single mode fiber (SMF) applications the arrayed waveguide grating router (AWG) provides passive wavelength routing with spectral channels being used more than once in the routing table to achieve full NxN interconnection with only N wavelengths[l]. AWGs cannot be used with MMF due to the excessive losses in coupling from MMF to single mode waveguides. We report the development of a wavelength router (NxN wavelength multiplexer) for use in h and lF based optical networks. The device uses a blazed diffraction grating and broadband add/drop filters to provide wavelength re-use thus enabling fully non-blocking NxN interconnection with only N wavelengths. Initial experimental results using 3 inputs and 3 outputs are presented.
Date: June 1, 1999
Creator: Bond, S W; Deri, R J; Larson, M C; Lowry, M E; Patel, R R & Pocha, M D
Partner: UNT Libraries Government Documents Department

Cascaded wavelength division multiplexing for byte-wide optical interconnects

Description: We demonstrate a wavelength division multiplexing approach for byte-wide optical interconnects over multimode fiber optic ribbon cable using filters based on common plastic ferrules. A dual wavelength link with eight cascaded filter stages exhibits bit error rates {le}l0{sup -l4}.
Date: November 17, 1997
Creator: Deri, R. J.; Garrett, H. E.; Germelos, S.; Haigh,R. E.; Henderer, B. D.; Lowry, M. E. et al.
Partner: UNT Libraries Government Documents Department

Self-calibrating multiplexer circuit

Description: A time domain multiplexer system with automatic determination of acceptable multiplexer output limits, error determination, or correction is comprised of a time domain multiplexer, a computer, a constant current source capable of at least three distinct current levels, and two series resistances employed for calibration and testing. A two point linear calibration curve defining acceptable multiplexer voltage limits may be defined by the computer by determining the voltage output of the multiplexer to very accurately known input signals developed from predetermined current levels across the series resistances. Drift in the multiplexer may be detected by the computer when the output voltage limits, expected during normal operation, are exceeded, or the relationship defined by the calibration curve is invalidated.
Date: December 31, 1995
Creator: Wahl, C. P.
Partner: UNT Libraries Government Documents Department

Feasibility of optically interconnected parallel processors using wavelength division multiplexing

Description: New national security demands require enhanced computing systems for nearly ab initio simulations of extremely complex systems and analyzing unprecedented quantities of remote sensing data. This computational performance is being sought using parallel processing systems, in which many less powerful processors are ganged together to achieve high aggregate performance. Such systems require increased capability to communicate information between individual processor and memory elements. As it is likely that the limited performance of today`s electronic interconnects will prevent the system from achieving its ultimate performance, there is great interest in using fiber optic technology to improve interconnect communication. However, little information is available to quantify the requirements on fiber optical hardware technology for this application. Furthermore, we have sought to explore interconnect architectures that use the complete communication richness of the optical domain rather than using optics as a simple replacement for electronic interconnects. These considerations have led us to study the performance of a moderate size parallel processor with optical interconnects using multiple optical wavelengths. We quantify the bandwidth, latency, and concurrency requirements which allow a bus-type interconnect to achieve scalable computing performance using up to 256 nodes, each operating at GFLOP performance. Our key conclusion is that scalable performance, to {approx}150 GFLOPS, is achievable for several scientific codes using an optical bus with a small number of WDM channels (8 to 32), only one WDM channel received per node, and achievable optoelectronic bandwidth and latency requirements. 21 refs. , 10 figs.
Date: March 1, 1996
Creator: Deri, R.J.; De Groot, A.J. & Haigh, R.E.
Partner: UNT Libraries Government Documents Department

Subcarrier multiplexing system with built-in dispersion reduction

Description: Dispersion is effectively reduced in a 1550-nm subcarrier-multiplexed fiber link by using optical pre-filtering at the receiver. Recent experimental results demonstrate transmission of two 2.5 Gbit/s data channels over 220 km of ordinary single-mode fiber.
Date: September 8, 1995
Creator: Sargis, P.D.; Haigh, R.E. & McCammon, K.G.
Partner: UNT Libraries Government Documents Department

Run control techniques for the Fermilab DART data acquisition system

Description: DART is the high speed, Unix based data acquisition system being developed by the Fermilab Computing Division in collaboration with eight High Energy Physics Experiments. This paper describes DART run-control which implements flexible, distributed, extensible and portable paradigms for the control and monitoring of data acquisition systems. We discuss the unique and interesting aspects of the run-control - why we chose the concepts we did, the benefits we have seen from the choices we made, as well as our experiences in deploying and supporting it for experiments during their commissioning and sub-system testing phases. We emphasize the software and techniques we believe are extensible to future use, and potential future modifications and extensions for those we feel are not.
Date: October 1, 1995
Creator: Oleynik, G.; Engelfried, J. & Mengel, L.
Partner: UNT Libraries Government Documents Department

An experimental study of VBR video over various ATM switch architectures

Description: One of the most important components of an Asynchronous Transfer Mode (ATM) network is the switch. Switch design is not a part of the ATM standards so vendors use a wide variety of techniques to build their switches. In this paper, the authors present experimental results of switching and multiplexing real-time Variable Bit Rate (VBR) video traffic (JPEG, MPEG-1, and MPEG-2) through two different ATM switch architectures. Real-time VBR traffic, such as digital video, is particularly interesting due to its high demands in terms of bandwidth, real-time delivery and processing requirements. The experiments show that the fastest switches, i.e., lowest latencies, do not necessarily perform better when transmitting VBR video. The impact of the high speed network components; characteristics, such as switch fabric architecture, buffering strategies, and higher layer transport protocols (i.e., UDP, TCP/IP), are illustrated through the experimental results.
Date: December 31, 1997
Creator: Tsang, R.P.; Hsieh, J. & Du, D.H.C.
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

Dispersion-reduction technique using subcarrier multiplexing

Description: We have developed a novel dispersion-reduction technique using subcarrier multiplexing (SCM) which permits the transmission of multiple 2.5 Gbit/s data channels over hundreds of kilometers of conventional fiber-optic cable with negligible dispersion. Using a lithium niobate external modulator having a modulation bandwidth of 20 GHz, we are able to multiplex several high-speed data channels at a single wavelength. At the receiving end, we demultiplex the data and detect each channel using a 2-GHz bandwidth optical detector. All of the hardware in our system consists of off-the-shelf components and can be integrated to reduce the overall cost. We demonstrated our dispersion-reduction technique in a recent field trial by transmitting two 2.5 Gbit/s data channels over 90 km of commercially-installed single-mode fiber, followed by 210 km of spooled fiber. For comparison, we substituted the 300 km of fiber with equivalent optical attenuation. We also ran computer simulations to evaluate link behavior. Technical details and field trial results will be presented.
Date: October 18, 1995
Creator: Sargis, P. D.; Haigh, R. E. & McCammon, K. G.
Partner: UNT Libraries Government Documents Department

Innovative Aspects of the SDL Control System

Description: The Source Development Lab at BNL consists of a 230 MeV electron linac and 10m long wiggler for short wavelength FEL development. The control system is based on that in use at the NSLS. Two new extensions of the control system using VXI equipment are described. The first extension is the replacement of patch panels and lab oscilloscopes to monitor RF equipment. Instead, the RF waveforms are fed through a multiplexor into VXI digitizers. The waveforms can then be monitored remotely on any control console. The second extension is the replacement of the analog RF hardware needed to process beam position monitor signals. A digital system based on very fast (sub-nanosecond) VXI waveform digitizers is under development. The difficult operations requiring precise time alignment are then done in software.
Date: December 31, 1997
Creator: Graves, W.S.; Feng, S.K.; Pearson, P.S. & Smith, J.D.
Partner: UNT Libraries Government Documents Department

Technical Progress Report for PEPCO: Turbo-Z Battery Charging System. Calendar Quarter Ending March 31, 1999

Description: The project is proceeding at a rapid pace now. The software is in development for the control board and the test stand. Portions of the writing and debugging of this software have been in conjunction with the hardware development. The software now interfaces with all the measurement instruments and displays the measurements on the screen, and it saves the measurements to a disc file. There is still cleanup work to do on the display items. Work must still be imparted to the code to control a charging sequence while taking measurements of the results. The test stand hardware has received a good development effort this quarter. The timer-counter board is working in the computer. This board paces the measurement cycle and times the discharge pulse (whine circuit). The thermocouple multiplexer is scanning at the same time the analog to digital converter is taking measurements. We have made a good number of hardware modifications to solve problems revealed while writing the software. The power factor correction for the charger power section is still in development. The engineers have found additional sources for the PFC chips, and they have obtained more technical data sheets and acquired samples. The control board schematics are complete, and the software is far along in the development phase. The functions of the control board have been detailed. The control board must next be integrated with the power supply unit. The next phase of development will concentrate on integrating the components together. At this time, the final debugging of the hardware and software will begin. Additionally, the capacitive coupler development is proceeding. The annual DARPA/DoT Advanced Transportation review will be held on May 16, 1999. We expect to learn the status of our project proposal during this conference. Should we more forward, UL has agreed to help us ...
Date: April 1, 2000
Partner: UNT Libraries Government Documents Department

A unique data acquisition system for electrical resistance tomography

Description: Unique capabilities are needed in instrumentation used for acquiring data to do electrical resistance tomography (ERT). A data acquisition system is described which has a good combination of the required capabilities and yet is field rugged and user friendly. The system is a multichannel detector for high data rates, can operate over a wide range of load conditions, will measure both in phase and quadrature resistance at frequencies between 0.0007 Hz and 8 kHz. The system has been used in both the field and laboratory to collect data with a typical accuracy between 1 and 10%.
Date: January 4, 1996
Creator: Daily, W.; Ramirez, A. & Zonge, K.
Partner: UNT Libraries Government Documents Department

Web tools to monitor and debug DAQ hardware

Description: A web-based toolkit to monitor and diagnose data acquisition hardware has been developed. It allows for remote testing, monitoring, and control of VxWorks data acquisition computers and associated instrumentation using the HTTP protocol and a web browser. This solution provides concurrent and platform independent access, supplementary to the standard single-user rlogin mechanism. The toolkit is based on a specialized web server, and allows remote access and execution of select system commands and tasks, execution of test procedures, and provides remote monitoring of computer system resources and connected hardware. Various DAQ components such as multiplexers, digital I/O boards, analog to digital converters, or current sources can be accessed and diagnosed remotely in a uniform and well-organized manner. Additionally, the toolkit application supports user authentication and is able to enforce specified access restrictions.
Date: June 4, 2003
Creator: Desavouret, Eugene & Nogiec, Jerzy M.
Partner: UNT Libraries Government Documents Department

Self-consistent temperature compensation for resonant sensors with application to quartz bulk acoustic wave chemical sensors

Description: Since resonant sensors have a temperature sensitivity which is often greater than their sensitivity to the phenomena they are being used to detect, it is imperative to include either temperature control or temperature compensation in any resonant sensor system. The authors have developed a temperature-compensation scheme for resonant sensors which is amenable to integration into a resonator-driver integrated circuit. An integrated circuit incorporating this scheme has been designed, built, and tested.
Date: May 1, 1995
Creator: Smith, J.H. & Senturia, S.D.
Partner: UNT Libraries Government Documents Department

Application of optical interconnect technology at Lawrence Livermore National Laboratory

Description: Optical interconnects will be required to meet the information bandwidth requirements of future communication and computing applications. At Lawrence Livermore National Laboratory, the authors are involved in applying optical interconnect technologies in two distinct application areas: Multi-Gigabit/sec Computer Backplanes and Gigabit/sec Wide Area Networking using Wavelength Division Multiplexing. In this paper, the authors discuss their efforts to integrate optical interconnect technologies into prototype computing and communication systems.
Date: August 10, 1995
Creator: Haigh, R. E.; Lowry, M. E.; McCammon, K.; Hills, R.; Mitchell, R. & Sweider, D.
Partner: UNT Libraries Government Documents Department

Lithium Lens Interlocks

Description: The lithium lens in the antiproton source target vault is protected by an interlock system, which is located in relay racks R5 and R6 near the southwest corner of the Target Hall (building APO). The interlock system consists of crates of commercial signal conditioner and alarm modules built by Acromag, Inc and interlock Master Modules built by Fermilab: Twenty analog signals from the lens/transformer, power supply, and cooling water system are buffered with signal conditioners (amplifiers), which are located in creates R5C and R5E. The signals and conditioner assignments are listed in Table 1. Interconnection details are shown in Figure 1. Thermocouple signals come into the conditioners directly from the vault or water system via 12-pair multiconductor thermocouple extension cables. All other signals pass through a master connection panel on the east end of rack R6. Water flow signals are AC voltages which must be converted by electronics in crate D2B to DC voltages before entering their signal conditioners. Each conditioner drives two parallel outputs. One output goes to a Multiplexed Analog to Digital Converter (MADC 25), which is located in R5D. This voltage output is read by the accelerator control network (ACNET) and can be displayed at any control console on parameter page P46. The other voltage output is connected to an alarm module. Thirteen analog signals are processed by alarm modules, which are located in crates R6B and R6C. Alarm connection details are shown in Figure 2. Each alarm module contains two DPDT relays, one for an upper limit and one for a lower limit. The relays are latching, so that once an input has passed outside a limit, that limit relay remains in the tripped condition until an operator issues a reset pulse. The reset may be generated locally with a pushbutton on the appropriate interlock master ...
Date: December 18, 1985
Creator: Krider, J.
Partner: UNT Libraries Government Documents Department

Low-cost hadron colliders at Fermilab: A discussion paper

Description: New more economic approaches are required to continue the dramatic exponential rise in collider energies as represented by the well known Livingston plot. The old idea of low cost, low field iron dominated magnets in a small diameter pipe may become feasible in the next decade with dramatic recent advances in technology: (1) advanced tunneling technologies for small diameter, non human accessible tunnels, (2) accurate remote guidance systems for tunnel survey and boring machine steering, (3) high T{sub c} superconductors operating at liquid N{sub 2} or liquid H{sub 2} temperatures, (4) industrial applications of remote manipulation and robotics, (5) digitally multiplexed electronics to minimize cables, (6) achievement of high luminosities in p-p and p-{anti P} colliders. The goal of this paper is to stimulate continuing discussions on approaches to this new collider and to identify critical areas needing calculations, construction of models, proof of principle experiments, and full scale prototypes in order to determine feasibility and arrive at cost estimates.
Date: June 21, 1996
Creator: Foster, G.W. & Malamud, E.
Partner: UNT Libraries Government Documents Department

Environmental testing of an experimental digital safety channel

Description: This document presents the results of environmental stress tests performed on an experimental digital safety channel (EDSC) assembled at the Oak Ridge National Laboratory (ORNL) as part of the NRC-sponsored Qualification of Advanced Instrumentation and Controls (W) System program. The objective of this study is to investigate failure modes and vulnerabilities of microprocessor-based technologies when subjected to environmental stressors. The study contributes to the technical basis for environmental qualification of safety-related digital I&C systems. The EDSC employs technologies and digital subsystems representative of those proposed for use in advanced light-water reactors (ALWRs) or for retrofits in existing plants. Subsystems include computers, electrical and optical serial communication links, fiber-optic network links, analog-to-digital and digital-to-analog converters, and multiplexers. The EDSC was subjected to selected stressors that are a potential risk to digital equipment in a mild environment. The selected stressors were electromagnetic and radio-frequency interference (EMYRFI), temperature, humidity, and smoke exposure. The stressors were applied over ranges that were considerably higher than what the channel is likely to experience in a normal nuclear power plant environment. Ranges of stress were selected at a sufficiently high level to induce errors so that failure modes that are characteristic of the technologies employed could be identified.
Date: September 1996
Creator: Korsah, K.; Tanaka, T.J.; Wilson, T.L. Jr. & Wood, R.T.
Partner: UNT Libraries Government Documents Department

Characterization of NIR InGaAs imager arrays for the JDEM SNAPmission concept

Description: We present the results of a study of the performance of InGaAs detectors conducted for the SuperNova Acceleration Probe (SNAP) dark energy mission concept. Low temperature data from a nominal 1.7um cut-off wavelength 1kx1k InGaAs photodiode array, hybridized to a Rockwell H1RG multiplexer suggest that InGaAs detector performance is comparable to those of existing 1.7um cut-off HgCdTe arrays. Advances in 1.7um HgCdTe dark current and noise initiated by the SNAP detector research and development program makes it the baseline detector technology for SNAP. However, the results presented herein suggest that existing InGaAs technology is a suitable alternative for other future astronomy applications.
Date: May 23, 2006
Creator: Seshadri, S.; Cole, M.D.; Hancock, B.; Ringold, P.; Wrigley, C.; Bonati, M. et al.
Partner: UNT Libraries Government Documents Department

100kW Energy Transfer Multiplexer Power Converter Prototype Development Project

Description: Project Final Report for "100kW Energy Transfer Multiplexer Power Converter Prototype Development Project" prepared under DOE grant number DE-FG36-03GO13138. This project relates to the further development and prototype construction/evaluation for the Energy Transfer Multiplexer (ETM) power converter topology concept. The ETM uses a series resonant link to transfer energy from any phase of a multiphase input to any phase of a multiphase output, converting any input voltage and frequency to any output voltage and frequency. The basic form of the ETM converter consists of an eight (8)-switch matrix (six phase power switches and two ground power switches) and a series L-C resonant circuit. Electronic control of the switches allows energy to be transferred in the proper amount from any phase to any other phase. Depending upon the final circuit application, the switches may be either SCRs or IGBTs. The inherent characteristics of the ETM converter include the following: Power processing in either direction (bidirectional); Large voltage gain without the need of low frequency magnetics; High efficiency independent of output load and frequency; Wide bandwidth with fast transient response and; Operation as a current source. The ETM is able to synthesize true sinusoidal waveforms with low harmonic distortions. For a low power PM wind generation system, the ETM has the following characteristics and advantages: It provides voltage gain without the need of low frequency magnetics (DC inductors) and; It has constant high efficiency independent of the load. The ETM converter can be implemented into a PM wind power system with smaller size, reduced weight and lower cost. As a result of our analyses, the ETM offers wind power generation technology for the reduction of the cost and size as well as the increase in performance of low power, low wind speed power generation. This project is the further theoretical/analytical exploration of ...
Date: March 21, 2006
Creator: Skeist, S. Merrill; Baker, Richard H. (Dick); Marini, Anthony G.P. & Bennett, DOE Project Officer - Keith
Partner: UNT Libraries Government Documents Department