Science.gov

Sample records for digital system simulation

  1. Real time digital propulsion system simulation for manned flight simulators

    NASA Technical Reports Server (NTRS)

    Mihaloew, J. R.; Hart, C. E.

    1978-01-01

    A real time digital simulation of a STOL propulsion system was developed which generates significant dynamics and internal variables needed to evaluate system performance and aircraft interactions using manned flight simulators. The simulation ran at a real-to-execution time ratio of 8.8. The model was used in a piloted NASA flight simulator program to evaluate the simulation technique and the propulsion system digital control. The simulation is described and results shown. Limited results of the flight simulation program are also presented.

  2. Aid For Simulating Digital Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Hartman, Richard M.

    1991-01-01

    DIVERS translator is computer program to convert descriptions of digital flight-control systems (DFCS) into computer program. Language developed to represent design charts of DFCS. Translator converts DIVERS source code into easily transportable language, while minimizing probability that results are affected by interpretation of programmer. Final translated program used as standard of comparison to verify operation of actual flight-control systems. Applicable to simulation of other control systems; for example, electrical circuits and logic processes. Written in C.

  3. Common modeling system for digital simulation

    NASA Technical Reports Server (NTRS)

    Painter, Rick

    1994-01-01

    The Joint Modeling and Simulation System is a tri-service investigation into a common modeling framework for the development digital models. The basis for the success of this framework is an X-window-based, open systems architecture, object-based/oriented methodology, standard interface approach to digital model construction, configuration, execution, and post processing. For years Department of Defense (DOD) agencies have produced various weapon systems/technologies and typically digital representations of the systems/technologies. These digital representations (models) have also been developed for other reasons such as studies and analysis, Cost Effectiveness Analysis (COEA) tradeoffs, etc. Unfortunately, there have been no Modeling and Simulation (M&S) standards, guidelines, or efforts towards commonality in DOD M&S. The typical scenario is an organization hires a contractor to build hardware and in doing so an digital model may be constructed. Until recently, this model was not even obtained by the organization. Even if it was procured, it was on a unique platform, in a unique language, with unique interfaces, and, with the result being UNIQUE maintenance required. Additionally, the constructors of the model expended more effort in writing the 'infrastructure' of the model/simulation (e.g. user interface, database/database management system, data journalizing/archiving, graphical presentations, environment characteristics, other components in the simulation, etc.) than in producing the model of the desired system. Other side effects include: duplication of efforts; varying assumptions; lack of credibility/validation; and decentralization in policy and execution. J-MASS provides the infrastructure, standards, toolset, and architecture to permit M&S developers and analysts to concentrate on the their area of interest.

  4. Interactive simulation of digital communication systems

    NASA Astrophysics Data System (ADS)

    Modestino, J. W.; Matis, K. R.

    1984-01-01

    In this paper, efforts to develop a comprehensive tool for the digital simulation of a wide variety of point-to-point digital communication systems are described. These efforts have resulted in the interactive communications simulator (ICS), a flexible, graphics-oriented, and highly interactive hardware/software system consisting of a typical minicomputer acting as host to a fast peripheral array processor. This system is presently being employed both to evaluate existing modem performance and to explore new modulation/coding concepts approprate for military, commercial, and space applications. A detailed functional description of the ICS is provided together with pertinent software considerations. An outline of existinig ICS capabilities is presented and illustrated through typical graphical output. A discussion of channel modeling considerations is provided. The use of the ICS in the overall design of receiver structures for impulsive noise channels will be illustrated.

  5. System Equivalent for Real Time Digital Simulator

    NASA Astrophysics Data System (ADS)

    Lin, Xi

    2011-07-01

    The purpose of this research is to develop a method of making system equivalents for the Real Time Digital Simulator (RTDS), which should enhance its capability of simulating large power systems. The proposed equivalent combines a Frequency Dependent Network Equivalent (FDNE) for the high frequency electromagnetic transients and a Transient Stability Analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the Vector Fitting method. An approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data is also introduced. A new scheme of incorporating TSA solution in RTDS is proposed. This report shows how the TSA algorithm can be adapted to a real time platform. The validity of this method is confirmed with examples, including the study of a multi in-feed HVDC system based network.

  6. Digital system for structural dynamics simulation

    SciTech Connect

    Krauter, A.I.; Lagace, L.J.; Wojnar, M.K.; Glor, C.

    1982-11-01

    State-of-the-art digital hardware and software for the simulation of complex structural dynamic interactions, such as those which occur in rotating structures (engine systems). System were incorporated in a designed to use an array of processors in which the computation for each physical subelement or functional subsystem would be assigned to a single specific processor in the simulator. These node processors are microprogrammed bit-slice microcomputers which function autonomously and can communicate with each other and a central control minicomputer over parallel digital lines. Inter-processor nearest neighbor communications busses pass the constants which represent physical constraints and boundary conditions. The node processors are connected to the six nearest neighbor node processors to simulate the actual physical interface of real substructures. Computer generated finite element mesh and force models can be developed with the aid of the central control minicomputer. The control computer also oversees the animation of a graphics display system, disk-based mass storage along with the individual processing elements.

  7. Digital system for structural dynamics simulation

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.; Lagace, L. J.; Wojnar, M. K.; Glor, C.

    1982-01-01

    State-of-the-art digital hardware and software for the simulation of complex structural dynamic interactions, such as those which occur in rotating structures (engine systems). System were incorporated in a designed to use an array of processors in which the computation for each physical subelement or functional subsystem would be assigned to a single specific processor in the simulator. These node processors are microprogrammed bit-slice microcomputers which function autonomously and can communicate with each other and a central control minicomputer over parallel digital lines. Inter-processor nearest neighbor communications busses pass the constants which represent physical constraints and boundary conditions. The node processors are connected to the six nearest neighbor node processors to simulate the actual physical interface of real substructures. Computer generated finite element mesh and force models can be developed with the aid of the central control minicomputer. The control computer also oversees the animation of a graphics display system, disk-based mass storage along with the individual processing elements.

  8. A digital IF simulator for FM ranging systems

    NASA Astrophysics Data System (ADS)

    Bartlett, M. C.; Johnson, R. C.

    1980-03-01

    A digital intermediate frequency signal simulator (DIFSS) which is useful for testing many periodically modulated FM ranging systems is described. The DIFSS digitally computes the IF signal angle using angle tables stored in EPROM's and generates the cosine of the angle with a cosine PROM and D/A converter. Target delay time tau and doppler frequency can be varied as desired for static tests or dynamic target trajectories. The simulator is useful for testing real-time hardware or for testing ambiguous ranging system responses in a scaled-time mode.

  9. Upset susceptibility study employing circuit analysis and digital simulation. [digital systems and electromagnetic interference

    NASA Technical Reports Server (NTRS)

    Carreno, V. A.

    1984-01-01

    An approach to predict the susceptibility of digital systems to signal disturbances is described. Electrical disturbances on a digital system's input and output lines can be induced by activities and conditions including static electricity, lightning discharge, electromagnetic interference (EMI), and electromagnetic pulsation (EMP). The electrical signal disturbances employed for the susceptibility study were limited to nondestructive levels, i.e., the system does not sustain partial or total physical damage and reset and/or reload brings the system to an operational status. The front-end transition from the electrical disturbances to the equivalent digital signals was accomplished by computer-aided circuit analysis. The super-sceptre (system for circuit evaluation of transient radiation effects) programs was used. Gate models were developed according to manufacturers' performance specifications and parameters resulting from construction processes characteristic of the technology. Digital simulation at the gate and functional level was employed to determine the impact of the abnormal signals on system performance and to study the propagation characteristics of these signals through the system architecture. Example results are included for an Intel 8080 processor configuration.

  10. SDLDS--System for Digital Logic Design and Simulation

    ERIC Educational Resources Information Center

    Stanisavljevic, Z.; Pavlovic, V.; Nikolic, B.; Djordjevic, J.

    2013-01-01

    This paper presents the basic features of a software system developed to support the teaching of digital logic, as well as the experience of using it in the Digital Logic course taught at the School of Electrical Engineering, University of Belgrade, Serbia. The system has been used for several years, both by students for self-learning and…

  11. Digital simulation and modeling of nonlinear stochastic systems

    SciTech Connect

    Richardson, J M; Rowland, J R

    1981-04-01

    Digitally generated solutions of nonlinear stochastic systems are not unique but depend critically on the numerical integration algorithm used. Some theoretical and practical implications of this dependence are examined. The Ito-Stratonovich controversy concerning the solution of nonlinear stochastic systems is shown to be more than a theoretical debate on maintaining Markov properties as opposed to utilizing the computational rules of ordinary calculus. The theoretical arguments give rise to practical considerations in the formation and solution of discrete models from continuous stochastic systems. Well-known numerical integration algorithms are shown not only to provide different solutions for the same stochastic system but also to correspond to different stochastic integral definitions. These correspondences are proved by considering first and second moments of solutions that result from different integration algorithms and then comparing the moments to those arising from various stochastic integral definitions. This algorithm-dependence of solutions is in sharp contrast to the deterministic and linear stochastic cases in which unique solutions are determined by any convergent numerical algorithm. Consequences of the relationship between stochastic system solutions and simulation procedures are presented for a nonlinear filtering example. Monte Carlo simulations and statistical tests are applied to the example to illustrate the determining role which computational procedures play in generating solutions.

  12. An Introduction to Register Transfer Level Simulation of Digital Systems.

    ERIC Educational Resources Information Center

    Hemming, Cliff; Smith R. J., II

    Register transfer level (RTL) descriptions of digital systems have certain advantages over other descriptive techniques, especially during early phases of the design effort. There are at least three identifiable major uses for RTL-type descriptions. First, RTL can serve as documentation of digital processor behavior, recording in a concise fashion…

  13. Digital simulation of continuous error models with application to an instrument landing system error

    NASA Technical Reports Server (NTRS)

    Merrick, R. B.; Smith, G. L.

    1972-01-01

    A digital simulation of the continuous error of the localized beam of a conventional instrument landing system is discussed. The digital simulation was developed during the analysis of space shuttle navigation capabilities. A discrete mathematical model for use on a digital computer is described. The model generates an output random sequence which is equivalent, for simulation purposes, to the desired random process. The model is a system of difference equations driven by a zero-mean Gaussian random sequence.

  14. Digital simulation program improved

    NASA Technical Reports Server (NTRS)

    Bramblett, E. K.

    1970-01-01

    Modified Integration Digital Analog Simulation /MIDAS/ program, which provides time oriented solutions to equations from system block diagram descriptions, is given greater speed, accuracy, flexibility, and applicability. Improved program incorporates additional elements for extended solution capability not readily available from analog computers.

  15. Multiple-access phased array antenna simulator for a digital beam forming system investigation

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Yu, John; Walton, Joanne C.; Perl, Thomas D.; Andro, Monty; Alexovich, Robert E.

    1992-01-01

    Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on-board digital beamforming techniques which will allow multiple users to simultaneously access a single S-band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design, and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise, and nonlinearities.

  16. Digital simulation of dynamic processes in radiometer systems. [microwave radiometers

    NASA Technical Reports Server (NTRS)

    Stanley, W. D.

    1980-01-01

    The development and application of several computer programs for simulating different classes of microwave radiometers are described. The programs are dynamic in nature, and they may be used to determine the instantaneous behavior of system variables as a function of time. Some of the programs employ random variable models in the simulations so that the statistical nature of the results may be investigated. The programs have been developed to utilize either the Continuous System Modeling Program or the Advanced Continuous System Language. The validity of most of the programs was investigated using statistical tests, and the results show excellent correlation with theoretical predictions. The programs are currently being used in the investigation of new design techniques for microwave radiometers.

  17. A digital-analog hybrid system and its application to the automatic flight control system simulation research

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The characteristics of a digital-analog hybrid system composed of a DJS-8 digital computer and a HMJ-200 analog computer are described as well as its applications to simulation research for an automatic flight control system. A hybrid computational example is included to illustrate the application.

  18. Signal-to-noise ratio estimation in digital computer simulation of lowpass and bandpass systems with applications to analog and digital communications, volume 3

    NASA Technical Reports Server (NTRS)

    Tranter, W. H.; Turner, M. D.

    1977-01-01

    Techniques are developed to estimate power gain, delay, signal-to-noise ratio, and mean square error in digital computer simulations of lowpass and bandpass systems. The techniques are applied to analog and digital communications. The signal-to-noise ratio estimates are shown to be maximum likelihood estimates in additive white Gaussian noise. The methods are seen to be especially useful for digital communication systems where the mapping from the signal-to-noise ratio to the error probability can be obtained. Simulation results show the techniques developed to be accurate and quite versatile in evaluating the performance of many systems through digital computer simulation.

  19. A digital computer simulation and study of a direct-energy-transfer power-conditioning system

    NASA Technical Reports Server (NTRS)

    Burns, W. W., III; Owen, H. A., Jr.; Wilson, T. G.; Rodriguez, G. E.; Paulkovich, J.

    1974-01-01

    A digital computer simulation technique, which can be used to study such composite power-conditioning systems, was applied to a spacecraft direct-energy-transfer power-processing system. The results obtained duplicate actual system performance with considerable accuracy. The validity of the approach and its usefulness in studying various aspects of system performance such as steady-state characteristics and transient responses to severely varying operating conditions are demonstrated experimentally.

  20. Digital spall radiograph analysis system: Report on simulated three- dimensional digital spall image reconstruction fidelity

    SciTech Connect

    Harris, C.L.

    1990-01-01

    This report describes progress on work to develop a cost effective, rapid response system for measuring momentum and kinetic energy of spall for the Advanced Technology Assessment Center (ATAC) Armor/Anti-Armor (A{sup 3}) program at Los Alamos National Laboratory. The system will exploit data contained in two sets of simultaneous co-planar flash radiographs taken along the center line of anticipated spall motion. Data contained in each set (which is proportional to the mass and z- number of the spall material intersected by the exposing x-ray at each point) is digitized and used to construct a three dimensional model (called the reconstructed spall image) that approximates the original spall cloud. From the model the mass of spall fragments is computed. The two sets of radiographs, separated in time, represent the spall configuration at two instants of time. Spall fragments from the first instant are matched with those from the second instant to determine velocity. Evaluation of the fidelity of candidate reconstruction algorithms is the highest priority task in this development program for the obvious reason that the efficacy of the projected spall analysis system depends upon the fidelity of the reconstruction techniques. The purpose of this document is to report the results of analysis of the fidelity of best reconstruction procedure (for one radiograph set) investigated to date. The reconstruction procedure uses data from four simultaneous radiographs representing two sides and two diagonals of a cube. The procedure makes use of an available space algorithm, two probabilistic devices (a mass placement probability heuristic, and a mass clumping heuristic), and a stochastic procedure for mass that cannot be placed by the algorithm or either of the heuristics. The procedure is fully described in the body of the report.

  1. Improved importance sampling technique for efficient simulation of digital communication systems

    NASA Technical Reports Server (NTRS)

    Lu, Dingqing; Yao, Kung

    1988-01-01

    A new, improved importance sampling (IIS) approach to simulation is considered. Some basic concepts of IS are introduced, and detailed evolutions of simulation estimation variances for Monte Carlo (MC) and IS simulations are given. The general results obtained from these evolutions are applied to the specific previously known conventional importance sampling (CIS) technique and the new IIS technique. The derivation for a linear system with no signal random memory is considered in some detail. For the CIS technique, the optimum input scaling parameter is found, while for the IIS technique, the optimum translation parameter is found. The results are generalized to a linear system with memory and signals. Specific numerical and simulation results are given which show the advantages of CIS over MC and IIS over CIS for simulations of digital communications systems.

  2. Digital video timing analyzer for the evaluation of PC-based real-time simulation systems

    NASA Astrophysics Data System (ADS)

    Jones, Shawn R.; Crosby, Jay L.; Terry, John E., Jr.

    2009-05-01

    Due to the rapid acceleration in technology and the drop in costs, the use of commercial off-the-shelf (COTS) PC-based hardware and software components for digital and hardware-in-the-loop (HWIL) simulations has increased. However, the increase in PC-based components creates new challenges for HWIL test facilities such as cost-effective hardware and software selection, system configuration and integration, performance testing, and simulation verification/validation. This paper will discuss how the Digital Video Timing Analyzer (DiViTA) installed in the Aviation and Missile Research, Development and Engineering Center (AMRDEC) provides quantitative characterization data for PC-based real-time scene generation systems. An overview of the DiViTA is provided followed by details on measurement techniques, applications, and real-world examples of system benefits.

  3. An object-oriented simulator for 3D digital breast tomosynthesis imaging system.

    PubMed

    Seyyedi, Saeed; Cengiz, Kubra; Kamasak, Mustafa; Yildirim, Isa

    2013-01-01

    Digital breast tomosynthesis (DBT) is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART) were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT) imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI) helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART) and total variation regularized reconstruction techniques (ART+TV) are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM) values. PMID:24371468

  4. Evaluation of effective dose with chest digital tomosynthesis system using Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Kim, Dohyeon; Jo, Byungdu; Lee, Youngjin; Park, Su-Jin; Lee, Dong-Hoon; Kim, Hee-Joung

    2015-03-01

    Chest digital tomosynthesis (CDT) system has recently been introduced and studied. This system offers the potential to be a substantial improvement over conventional chest radiography for the lung nodule detection and reduces the radiation dose with limited angles. PC-based Monte Carlo program (PCXMC) simulation toolkit (STUK, Helsinki, Finland) is widely used to evaluate radiation dose in CDT system. However, this toolkit has two significant limits. Although PCXMC is not possible to describe a model for every individual patient and does not describe the accurate X-ray beam spectrum, Geant4 Application for Tomographic Emission (GATE) simulation describes the various size of phantom for individual patient and proper X-ray spectrum. However, few studies have been conducted to evaluate effective dose in CDT system with the Monte Carlo simulation toolkit using GATE. The purpose of this study was to evaluate effective dose in virtual infant chest phantom of posterior-anterior (PA) view in CDT system using GATE simulation. We obtained the effective dose at different tube angles by applying dose actor function in GATE simulation which was commonly used to obtain the medical radiation dosimetry. The results indicated that GATE simulation was useful to estimate distribution of absorbed dose. Consequently, we obtained the acceptable distribution of effective dose at each projection. These results indicated that GATE simulation can be alternative method of calculating effective dose in CDT applications.

  5. Modeling and Simulation of Upset-Inducing Disturbances for Digital Systems in an Electromagnetic Reverberation Chamber

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2014-01-01

    This report describes a modeling and simulation approach for disturbance patterns representative of the environment experienced by a digital system in an electromagnetic reverberation chamber. The disturbance is modeled by a multi-variate statistical distribution based on empirical observations. Extended versions of the Rejection Samping and Inverse Transform Sampling techniques are developed to generate multi-variate random samples of the disturbance. The results show that Inverse Transform Sampling returns samples with higher fidelity relative to the empirical distribution. This work is part of an ongoing effort to develop a resilience assessment methodology for complex safety-critical distributed systems.

  6. Development, simulation validation, and wind tunnel testing of a digital controller system for flutter suppression

    NASA Technical Reports Server (NTRS)

    Hoadley, Sherwood Tiffany; Buttrill, Carey S.; Mcgraw, Sandra M.; Houck, Jacob A.

    1991-01-01

    Flutter suppression (FS) is one of the active control concepts being investigated by the AFW program. The design goal for FS control laws was to increase the passive flutter dynamic pressure by 30 percent. In order to meet this goal, the FS control laws had to be capable of suppressing both symmetric and antisymmetric flutter instabilities simultaneously. In addition, the FS control laws had to be practical and low-order, robust and capable of real time execution within the 200 hz. sampling time. The purpose here is to present an overview of the development, simulation validation, and wind tunnel testing of a digital controller system for flutter suppression.

  7. Tracking Performance Analysis and Simulation of the Digital Pointing System for the Optical Communication Demonstrator

    NASA Astrophysics Data System (ADS)

    Racho, C.; Portillo, A.

    1998-10-01

    Over the past 3 years, JPL has been heavily engaged in designing and developing a reduced-complexity optical communication terminal for high-data-volume applications. The terminal is called the Optical Communication Demonstrator (OCD) and has the ability to point microradian-level beams with a very small number of detectors and steering elements. Using only a single steering mirror and a charge-coupled device (CCD) detector array, the OCD can accomplish the functions of beacon signal acquisition, beacon tracking, transmit and receive beam coalignment, and transmit beam point-ahead offset. At a higher system level, developing an understanding of the OCD performance is an essential part of achieving a better understanding of the end-to-end optical communication system performance in the field. During the latter half of fiscal year 1998, a series of experiments was conducted between Table Mountain and Strawberry Peak using the OCD as a transmitting terminal for terrestrial ground-to- ground optical link demonstrations. The OCD was taken to Strawberry Peak and set up to receive the multibeam laser beacon from the 0.6-meter telescope located at Table Mountain, a distance of approximately 40 kilometers. In the presence of atmospheric effects, the laser beacon will fluctuate both in intensity and position. The ability to determine the performance of the control loop under atmospheric-induced fades and distortion becomes very important in evaluating the results of the field testing. This article describes the design and performance of the OCD digital control loop system, which includes the steering mirror, the CCD detector array tracker, and the associated electronics. The digital control loop performance is a key factor in the ultimate performance of the laser beacon acquisition and tracking algorithm of the OCD. A model of the OCD digital control loop is developed for use in simulations. The analytical results from control loop simulations are compared with measured data

  8. Digital systems design language

    NASA Technical Reports Server (NTRS)

    Shiva, S. G.

    1979-01-01

    Digital Systems Design Language (DDL) is implemented on the SEL-32 Computer Systems. The detaileds of the language, the translator, and the simulator, and the smulator programs are given. Several example descriptions and a tutorial on hardware description languages are provided, to guide the user.

  9. Learning Management Systems: Coupled Simulations and Assessments in a Digital Systems Course

    ERIC Educational Resources Information Center

    Wuttke, Heinz-Dietrich; Henke, Karsten

    2009-01-01

    Purpose: The content, provided in learning management systems (LMS), is often text oriented as in a usual textbook, extended by some animations and links. Hands on activities and experiments are not possible. The paper aims to give an overview about the concept to couple smart simulation and assessment tools with an LMS to provide a more…

  10. Analog-digital simulation of transient-induced logic errors and upset susceptibility of an advanced control system

    NASA Technical Reports Server (NTRS)

    Carreno, Victor A.; Choi, G.; Iyer, R. K.

    1990-01-01

    A simulation study is described which predicts the susceptibility of an advanced control system to electrical transients resulting in logic errors, latched errors, error propagation, and digital upset. The system is based on a custom-designed microprocessor and it incorporates fault-tolerant techniques. The system under test and the method to perform the transient injection experiment are described. Results for 2100 transient injections are analyzed and classified according to charge level, type of error, and location of injection.

  11. Clinical simulation and workflow by use of two clinical information systems, the electronic health record and digital dictation.

    PubMed

    Koldby, Sven; Schou Jensen, Iben

    2013-01-01

    Clinical information systems do not always support clinician workflows. An increasing number of unintended clinical incidents might be related to implementation of clinical information systems and to a new registration praxis of unintended clinical incidents. Evidence of performing clinical simulations before implementation of new clinical information systems provides the basis for use of this method. The intention has been to evaluate patient safety issues, functionality, workflow, and usefulness of a new solution before implementation in the hospitals. Use of a solution which integrates digital dictation and the EHR (electronic health record) were simulated in realistic and controlled clinical environments. Useful information dealing with workflow and patient safety were obtained. The clinical simulation demonstrated that the EHR locks during use of the integration of digital dictation, thus making it impossible to use the EHR or connected applications during digital dictation. The results of the simulations showed that the tested and evaluated solution does not support the clinical workflow. Conducting the simulations enabled us to improve the solution before implementation, but further development is necessary before implementation of the solution.

  12. Digital Simulation in Education.

    ERIC Educational Resources Information Center

    Braun, Ludwig

    Simulation as a mode of computer use in instruction has been neglected by educators. This paper briefly explores the circumstances in which simulations are useful and presents several examples of simulation programs currently being used in high-school biology, chemistry, physics, and social studies classes. One program, STERIL, which simulates…

  13. Advanced simulation of digital filters

    NASA Astrophysics Data System (ADS)

    Doyle, G. S.

    1980-09-01

    An Advanced Simulation of Digital Filters has been implemented on the IBM 360/67 computer utilizing Tektronix hardware and software. The program package is appropriate for use by persons beginning their study of digital signal processing or for filter analysis. The ASDF programs provide the user with an interactive method by which filter pole and zero locations can be manipulated. Graphical output on both the Tektronix graphics screen and the Versatec plotter are provided to observe the effects of pole-zero movement.

  14. High-temperature deformation field measurement by combining transient aerodynamic heating simulation system and reliability-guided digital image correlation

    NASA Astrophysics Data System (ADS)

    Pan, Bing; Wu, Dafang; Xia, Yong

    2010-09-01

    To determine the full-field high-temperature thermal deformation of the structural materials used in high-speed aerospace flight vehicles, a novel non-contact high-temperature deformation measurement system is established by combining transient aerodynamic heating simulation device with the reliability-guided digital image correlation (RG-DIC). The test planar sample with size varying from several mm 2 to several hundreds mm 2 can be heated from room temperature to 1100 °C rapidly and accurately using the infrared radiator of the transient aerodynamic heating simulation system. The digital images of the test sample surface at various temperatures are recorded using an ordinary optical imaging system. To cope with the possible local decorrelated regions caused by black-body radiation within the deformed images at the temperatures over 450 °C, the RG-DIC technique is used to extract full-field in-plane thermal deformation from the recorded images. In validation test, the thermal deformation fields and the values of coefficient of thermal expansion (CTEs) of a chromiumnickel austenite stainless steel sample from room temperature to 550 °C is measured and compared with the well-established handbook value, confirming the effectiveness and accuracy of the proposed technique. The experimental results reveal that the present system using an ordinary optical imaging system, is able to accurately measure full-field thermal deformation of metals and alloys at temperatures not exceeding 600 °C.

  15. Digital systems design language. Design synthesis of digital systems

    NASA Technical Reports Server (NTRS)

    Shiva, S. G.

    1979-01-01

    The Digital Systems Design Language (DDL) is implemented on the SEL-32 computer systems. The details of the language, translator and simulator programs are included. Several example descriptions and a tutorial on hardware description languages are provided, to guide the user.

  16. Estimation variance bounds of importance sampling simulations in digital communication systems

    NASA Technical Reports Server (NTRS)

    Lu, D.; Yao, K.

    1991-01-01

    In practical applications of importance sampling (IS) simulation, two basic problems are encountered, that of determining the estimation variance and that of evaluating the proper IS parameters needed in the simulations. The authors derive new upper and lower bounds on the estimation variance which are applicable to IS techniques. The upper bound is simple to evaluate and may be minimized by the proper selection of the IS parameter. Thus, lower and upper bounds on the improvement ratio of various IS techniques relative to the direct Monte Carlo simulation are also available. These bounds are shown to be useful and computationally simple to obtain. Based on the proposed technique, one can readily find practical suboptimum IS parameters. Numerical results indicate that these bounding techniques are useful for IS simulations of linear and nonlinear communication systems with intersymbol interference in which bit error rate and IS estimation variances cannot be obtained readily using prior techniques.

  17. Simulating social-ecological systems: the Island Digital Ecosystem Avatars (IDEA) consortium.

    PubMed

    Davies, Neil; Field, Dawn; Gavaghan, David; Holbrook, Sally J; Planes, Serge; Troyer, Matthias; Bonsall, Michael; Claudet, Joachim; Roderick, George; Schmitt, Russell J; Zettler, Linda Amaral; Berteaux, Véronique; Bossin, Hervé C; Cabasse, Charlotte; Collin, Antoine; Deck, John; Dell, Tony; Dunne, Jennifer; Gates, Ruth; Harfoot, Mike; Hench, James L; Hopuare, Marania; Kirch, Patrick; Kotoulas, Georgios; Kosenkov, Alex; Kusenko, Alex; Leichter, James J; Lenihan, Hunter; Magoulas, Antonios; Martinez, Neo; Meyer, Chris; Stoll, Benoit; Swalla, Billie; Tartakovsky, Daniel M; Murphy, Hinano Teavai; Turyshev, Slava; Valdvinos, Fernanda; Williams, Rich; Wood, Spencer

    2016-01-01

    Systems biology promises to revolutionize medicine, yet human wellbeing is also inherently linked to healthy societies and environments (sustainability). The IDEA Consortium is a systems ecology open science initiative to conduct the basic scientific research needed to build use-oriented simulations (avatars) of entire social-ecological systems. Islands are the most scientifically tractable places for these studies and we begin with one of the best known: Moorea, French Polynesia. The Moorea IDEA will be a sustainability simulator modeling links and feedbacks between climate, environment, biodiversity, and human activities across a coupled marine-terrestrial landscape. As a model system, the resulting knowledge and tools will improve our ability to predict human and natural change on Moorea and elsewhere at scales relevant to management/conservation actions.

  18. Simulating social-ecological systems: the Island Digital Ecosystem Avatars (IDEA) consortium.

    PubMed

    Davies, Neil; Field, Dawn; Gavaghan, David; Holbrook, Sally J; Planes, Serge; Troyer, Matthias; Bonsall, Michael; Claudet, Joachim; Roderick, George; Schmitt, Russell J; Zettler, Linda Amaral; Berteaux, Véronique; Bossin, Hervé C; Cabasse, Charlotte; Collin, Antoine; Deck, John; Dell, Tony; Dunne, Jennifer; Gates, Ruth; Harfoot, Mike; Hench, James L; Hopuare, Marania; Kirch, Patrick; Kotoulas, Georgios; Kosenkov, Alex; Kusenko, Alex; Leichter, James J; Lenihan, Hunter; Magoulas, Antonios; Martinez, Neo; Meyer, Chris; Stoll, Benoit; Swalla, Billie; Tartakovsky, Daniel M; Murphy, Hinano Teavai; Turyshev, Slava; Valdvinos, Fernanda; Williams, Rich; Wood, Spencer

    2016-01-01

    Systems biology promises to revolutionize medicine, yet human wellbeing is also inherently linked to healthy societies and environments (sustainability). The IDEA Consortium is a systems ecology open science initiative to conduct the basic scientific research needed to build use-oriented simulations (avatars) of entire social-ecological systems. Islands are the most scientifically tractable places for these studies and we begin with one of the best known: Moorea, French Polynesia. The Moorea IDEA will be a sustainability simulator modeling links and feedbacks between climate, environment, biodiversity, and human activities across a coupled marine-terrestrial landscape. As a model system, the resulting knowledge and tools will improve our ability to predict human and natural change on Moorea and elsewhere at scales relevant to management/conservation actions. PMID:26998258

  19. Digital solar system geology

    NASA Technical Reports Server (NTRS)

    Batson, R. M.; Kozak, R. C.; Isbell, Nancy K.

    1991-01-01

    All available synoptic maps of the solid-surface bodies of the Solar System were digitized for presentation in the planned Atlas of the Solar System by Greeley and Batson. Since the last report (Batson et al., 1990), preliminary Uranian satellite maps were replaced with improved versions, Galilean satellite geology was simplified and digitized, structure was added to many maps, and the maps were converted to a standard format, with corresponding standing colors for the mapped units. Following these changes, the maps were re-reviewed by their authors and are now undergoing final editing before preparation for publication. In some cases (for Mercury, Venus, and Mars), more detailed maps were digitized and then simplified for the Atlas. Other detailed maps are planned to be digitized in the coming year for the Moon and the Galilean satellites. For most of the remaining bodies such as the Uranian satellites, the current digitized versions contain virtually all the detail that can be mapped given the available data; those versions will be unchanged for the Atlas. These digital geologic maps are archived at the digital scale of 1/16 degree/ pixel, in sinusoidal format. The availability of geology of the Solar System in a digital database will facilitate comparisons and integration with other data: digitized lunar geologic maps have already been used in a comparison with Galileo SSI observations of the Moon.

  20. Design of a digital beam attenuation system for computed tomography: Part I. System design and simulation framework

    SciTech Connect

    Szczykutowicz, Timothy P.; Mistretta, Charles A.

    2013-02-15

    Purpose: The purpose of this work is to introduce a new device that allows for patient-specific imaging-dose modulation in conventional and cone-beam CT. The device is called a digital beam attenuator (DBA). The DBA modulates an x-ray beam by varying the attenuation of a set of attenuating wedge filters across the fan angle. The ability to modulate the imaging dose across the fan beam represents another stride in the direction of personalized medicine. With the DBA, imaging dose can be tailored for a given patient anatomy, or even tailored to provide signal-to-noise ratio enhancement within a region of interest. This modulation enables decreases in: dose, scatter, detector dynamic range requirements, and noise nonuniformities. In addition to introducing the DBA, the simulation framework used to study the DBA under different configurations is presented. Finally, a detailed study on the choice of the material used to build the DBA is presented. Methods: To change the attenuator thickness, the authors propose to use an overlapping wedge design. In this design, for each wedge pair, one wedge is held stationary and another wedge is moved over the stationary wedge. The composite thickness of the two wedges changes as a function of the amount of overlap between the wedges. To validate the DBA concept and study design changes, a simulation environment was constructed. The environment allows for changes to system geometry, different source spectra, DBA wedge design modifications, and supports both voxelized and analytic phantom models. A study of all the elements from atomic number 1 to 92 were evaluated for use as DBA filter material. The amount of dynamic range and tube loading for each element were calculated for various DBA designs. Tube loading was calculated by comparing the attenuation of the DBA at its minimum attenuation position to a filtered non-DBA acquisition. Results: The design and parametrization of DBA implemented FFMCT has been introduced. A simulation

  1. Digital simulation for post-docking response

    NASA Technical Reports Server (NTRS)

    Roberts, J. R.; Todd, R. S.

    1974-01-01

    The digital program, 2BODY, which simulates the translational and rotational motion of two connected rigid bodies and provides both digital and plot output is described. Relative rotation of the bodies at the connection is allowed, thereby providing a model suitable for studying system stability and response during a soft-dock regime. A users manual for the program is given as well as all the details and background pertaining to the equations of motion and mathematical models, integration scheme, and input/output routines.

  2. Hardware synthesis from DDL description. [simulating a digital system for computerized design of large scale integrated circuits

    NASA Technical Reports Server (NTRS)

    Shiva, S. G.; Shah, A. M.

    1980-01-01

    The details of digital systems can be conveniently input into the design automation system by means of hardware description language (HDL). The computer aided design and test (CADAT) system at NASA MSFC is used for the LSI design. The digital design language (DDL) was selected as HDL for the CADAT System. DDL translator output can be used for the hardware implementation of the digital design. Problems of selecting the standard cells from the CADAT standard cell library to realize the logic implied by the DDL description of the system are addressed.

  3. Digital autopilots: Design considerations and simulator evaluations

    NASA Technical Reports Server (NTRS)

    Osder, S.; Neuman, F.; Foster, J.

    1971-01-01

    The development of a digital autopilot program for a transport aircraft and the evaluation of that system's performance on a transport aircraft simulator is discussed. The digital autopilot includes three axis attitude stabilization, automatic throttle control and flight path guidance functions with emphasis on the mode progression from descent into the terminal area through automatic landing. The study effort involved a sequence of tasks starting with the definition of detailed system block diagrams of control laws followed by a flow charting and programming phase and concluding with performance verification using the transport aircraft simulation. The autopilot control laws were programmed in FORTRAN 4 in order to isolate the design process from requirements peculiar to an individual computer.

  4. Digital system upset. The effects of simulated lightning-induced transients on a general-purpose microprocessor

    NASA Technical Reports Server (NTRS)

    Belcastro, C. M.

    1983-01-01

    Flight critical computer based control systems designed for advanced aircraft must exhibit ultrareliable performance in lightning charged environments. Digital system upset can occur as a result of lightning induced electrical transients, and a methodology was developed to test specific digital systems for upset susceptibility. Initial upset data indicates that there are several distinct upset modes and that the occurrence of upset is related to the relative synchronization of the transient input with the processing sate of the digital system. A large upset test data base will aid in the formulation and verification of analytical upset reliability modeling techniques which are being developed.

  5. Physical and digital simulations for IVA robotics

    NASA Technical Reports Server (NTRS)

    Hinman, Elaine; Workman, Gary L.

    1992-01-01

    Space based materials processing experiments can be enhanced through the use of IVA robotic systems. A program to determine requirements for the implementation of robotic systems in a microgravity environment and to develop some preliminary concepts for acceleration control of small, lightweight arms has been initiated with the development of physical and digital simulation capabilities. The physical simulation facilities incorporate a robotic workcell containing a Zymark Zymate II robot instrumented for acceleration measurements, which is able to perform materials transfer functions while flying on NASA's KC-135 aircraft during parabolic manuevers to simulate reduced gravity. Measurements of accelerations occurring during the reduced gravity periods will be used to characterize impacts of robotic accelerations in a microgravity environment in space. Digital simulations are being performed with TREETOPS, a NASA developed software package which is used for the dynamic analysis of systems with a tree topology. Extensive use of both simulation tools will enable the design of robotic systems with enhanced acceleration control for use in the space manufacturing environment.

  6. Digital sonar system

    DOEpatents

    Young, K.K.; Wilkes, R.J.

    1995-11-21

    A transponder of an active digital sonar system identifies a multifrequency underwater activating sonar signal received from a remote sonar transmitter. The transponder includes a transducer that receives acoustic waves, including the activating sonar signal, and generates an analog electrical receipt signal. The analog electrical receipt signal is converted to a digital receipt signal and cross-correlated with a digital transmission signal pattern corresponding to the activating sonar signal. A relative peak in the cross-correlation value is indicative of the activating sonar signal having been received by the transponder. In response to identifying the activating sonar signal, the transponder transmits a responding multifrequency sonar signal. 4 figs.

  7. Digital sonar system

    DOEpatents

    Young, Kenneth K.; Wilkes, R. Jeffrey

    1995-01-01

    A transponder of an active digital sonar system identifies a multifrequency underwater activating sonar signal received from a remote sonar transmitter. The transponder includes a transducer that receives acoustic waves, including the activating sonar signal, and generates an analog electrical receipt signal. The analog electrical receipt signal is converted to a digital receipt signal and cross-correlated with a digital transmission signal pattern corresponding to the activating sonar signal. A relative peak in the cross-correlation value is indicative of the activating sonar signal having been received by the transponder. In response to identifying the activating sonar signal, the transponder transmits a responding multifrequency sonar signal.

  8. Digital and analog communication systems

    NASA Technical Reports Server (NTRS)

    Shanmugam, K. S.

    1979-01-01

    The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.

  9. A digital simulation of the glacial-aquifer system in the northern three-fourths of Brown County, South Dakota

    USGS Publications Warehouse

    Emmons, P.J.

    1990-01-01

    A digital model was developed to simulate groundwater flow in a complex glacial-aquifer system that includes the Elm, Middle James, and Deep James aquifers in South Dakota. The average thickness of the aquifers ranges from 16 to 32 ft and the average hydraulic conductivity ranges from 240 to 300 ft/day. The maximum steady-state recharge to the aquifer system was estimated to be 7.0 in./yr, and the maximum potential steady- state evapotranspiration was estimated to be 35.4 in/yr. Maximum monthly recharge for 1985 ranged from zero in the winter to 2.5 in in May. The potential monthly evapotranspiration for 1985 ranged from zero in the winter to 7.0 in in July. The average difference between the simulated and observed water levels from steady-state conditions (pre-1983) was 0. 78 ft and the average absolute difference was 4.59 ft for aquifer layer 1 (the Elm aquifer) from 22 observation wells and 3.49 ft and 5.10 ft, respectively, for aquifer layer 2 (the Middle James aquifer) from 13 observation wells. The average difference between the simulated and observed water levels from simulated monthly potentiometric heads for 1985 in aquifer layer 1 ranged from -2.54 ft in July to 0.59 ft in May and in aquifer layer 2 ranged from -1.22 ft in April to 4.98 ft in November. Sensitivity analysis of the steady-state model indicates that it is most sensitive to changes in recharge and least sensitive to changes in hydraulic conductivity. (USGS)

  10. Digital capacitance measuring system

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The hardware phase of a digital capacitance measuring system is presented with the major emphasis placed on the electrical design and operation. Test results are included of the three units fabricated. The system's interface is applicable to existing requirements for the space shuttle vehicle.

  11. Hydrology and digital simulation of the regional aquifer system, eastern Snake River Plain, Idaho

    USGS Publications Warehouse

    Garabedian, S.P.

    1992-01-01

    The transient model was used to simulate aquifer changes from 1981 to 2010 in response to three hypothetical development alternatives: (1) Continuation of 1980 hydrologic conditions, (2) increased pumpage, and (3) increased recharge. Simulation of continued 1980 hydrologic conditions for 30 years indicated that head declines of 2 to 8 feet might be expected in the central part of the plain. The magnitude of simulated head declines was con- sistent with head declines measured during the 1980 water year. Larger declines were calculated along model boundaries, but these changes may have resulted from underestimation of tribu- tary drainage-basin underflow and inadequate aquifer definition. Simulation of increased ground-water pumpage (an additional 2,400 cubic feet per second) for 30 years indicated head declines of 10 to 50 feet in the central part of the plain. These relatively large head declines were accompanied by increased simulated river leakage of 50 percent and decreased spring discharge of 20 percent. The effect of increased recharge (800 cubic feet per sec- ond) for 30 years was a rise in simulated heads of 0 to 5 feet in the central part of the plain.

  12. Digital flight control systems

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Vanlandingham, H. F.

    1977-01-01

    The design of stable feedback control laws for sampled-data systems with variable rate sampling was investigated. These types of sampled-data systems arise naturally in digital flight control systems which use digital actuators where it is desirable to decrease the number of control computer output commands in order to save wear and tear of the associated equipment. The design of aircraft control systems which are optimally tolerant of sensor and actuator failures was also studied. Detection of the failed sensor or actuator must be resolved and if the estimate of the state is used in the control law, then it is also desirable to have an estimator which will give the optimal state estimate even under the failed conditions.

  13. Digital model simulation of the hydrologic flow system, with emphasis on ground water in Spokane Valley, Washington and Idaho

    USGS Publications Warehouse

    Bolke, E.L. Vaccaro; Washington, J.J.

    1980-01-01

    A digital-computer model of the hydrologic flow system, with emphasis on ground water, was developed for the Spokane Valley, Washington and Idaho. The current rate of ground water pumping has little effect on water levels in the Spokane aquifer, although short-term water-level declines occur locally. The model was used to show the effects of increased ground-water pumping on aquifer heads and streamflow. Increasing the pumping rates, by a factor of 2 from the 1977 rates, lowered water levels in the Spokane aquifer less than 3 feet during a 1-year simulation. Doubling the ground-water pumping caused a decrease in discharge of the Spokane River, as measured at Spokane, of about 150 cubic feet per second during the summer months and about 50 cubic feet per second during the rest of the year. The leakage from the aquifer to the Little Spokane River was decreased by less than 10 cubic feet per second by doubling the ground-water pumping. (USGS)

  14. Real time simulator with Ti floating point digital signal processor

    SciTech Connect

    Razazian, K.; Bobis, J.P.; Dieckman, S.L.; Raptis, A.C.

    1994-08-01

    This paper describes the design and operation of a Real Time Simulator using Texas Instruments TMS320C30 digital signal processor. This system operates with two banks of memory which provide the input data to digital signal processor chip. This feature enables the TMS320C30 to be utilized in variety of applications for which external connections to acquire input data is not needed. In addition, some practical applications of this Real Time Simulator are discussed.

  15. Digital system bus integrity

    NASA Technical Reports Server (NTRS)

    Eldredge, Donald; Hitt, Ellis F.

    1987-01-01

    This report summarizes and describes the results of a study of current or emerging multiplex data buses as applicable to digital flight systems, particularly with regard to civil aircraft. Technology for pre-1995 and post-1995 timeframes has been delineated and critiqued relative to the requirements envisioned for those periods. The primary emphasis has been an assured airworthiness of the more prevalent type buses, with attention to attributes such as fault tolerance, environmental susceptibility, and problems under continuing investigation. Additionally, the capacity to certify systems relying on such buses has been addressed.

  16. DDL system: Design systhesis of digital systems

    NASA Technical Reports Server (NTRS)

    Shiva, S. G.

    1983-01-01

    Digital Systems Design Language was integrated into the CADAT system environment of NASA-MSFC. The major technical aspects of this integration are summarized. Automatic hardware synthesis is now possible starting with a high level description of the system to be synthesized. The DDL system provides a high level design verification capability, thereby minimizing design changes in the later stages of the design cycle. An overview of the DDL system covering the translation, simulation and synthesis capabilities is provided. Two companion documents (the user's and programmer's manuals) are to be consulted for detailed discussions.

  17. Digital Channel Simulator Developed and Tested

    NASA Technical Reports Server (NTRS)

    Bizon, Thomas P.

    2000-01-01

    The Digital Channel Simulator (DCS) is a real-time test set developed in-house by the NASA Glenn Research Center at Lewis Field that simulates the characteristics of the modulator, demodulator, and transmission medium in a typical communications system to enable controlled laboratory testing of codec pairs. The DCS can support data rates up to 100 megasymbols per second (Msymbols/sec) with symbol sizes up to 10 bits and is compatible with both TTL (transistor transistor logic) and ECL (emitter coupled logic) interfaces. Because of its use of digital integrated circuits (IC's), the DCS offers the user accurate and repeatable testing while maintaining a simple reconfiguration of the modulation scheme and noise characteristics. The PC-based graphical user interface (GUI) assures user friendly operation for configuring, controlling, and monitoring the DCS and system during tests. In a typical communications system, the modulator places a symbol in constellation space and puts it on a carrier to be sent to the demodulator. Because of noise on the channel, the I and Q position in constellation space cannot be recovered exactly, and the received coordinates shift. To mimic this process in the laboratory, the DCS uses a mapper to place the symbol in constellation space. It simulates the shift in coordinates by digitally adding "noise" to the I and Q values. The mapper and noise source are implemented in lookup tables. Modulation schemes and noise characteristics are set by the values loaded in these tables. The mapper also has a pass-through mode to facilitate modulator testing, allowing noise to be added to 8-bit I and Q values of modulated data without a second mapping. To achieve high symbol rates, eight processing circuits are placed in parallel between an ECL demultiplexer and multiplexer. A graphical user interface was developed to calculate, load, and verify the values for the lookup tables. This interface can also be used to debug and verify proper operation of the

  18. Genetic Algorithms for Digital Quantum Simulations

    NASA Astrophysics Data System (ADS)

    Las Heras, U.; Alvarez-Rodriguez, U.; Solano, E.; Sanz, M.

    2016-06-01

    We propose genetic algorithms, which are robust optimization techniques inspired by natural selection, to enhance the versatility of digital quantum simulations. In this sense, we show that genetic algorithms can be employed to increase the fidelity and optimize the resource requirements of digital quantum simulation protocols while adapting naturally to the experimental constraints. Furthermore, this method allows us to reduce not only digital errors but also experimental errors in quantum gates. Indeed, by adding ancillary qubits, we design a modular gate made out of imperfect gates, whose fidelity is larger than the fidelity of any of the constituent gates. Finally, we prove that the proposed modular gates are resilient against different gate errors.

  19. Efficacy of lead foil for reducing doses in the head and neck: a simulation study using digital intraoral systems

    PubMed Central

    Silva, A I V; Brasil, D M; Vasconcelos, K F; Haiter Neto, F; Boscolo, F N

    2015-01-01

    Objectives: To assess the efficacy of lead foils in reducing the radiation dose received by different anatomical sites of the head and neck during periapical intraoral examinations performed with digital systems. Methods: Images were acquired through four different manners: phosphor plate (PSP; VistaScan® system; Dürr Dental GmbH, Bissingen, Germany) alone, PSP plus lead foil, complementary metal oxide semiconductor (CMOS; DIGORA® Toto, Soredex®, Tuusula, Finland) alone and CMOS plus lead foil. Radiation dose was measured after a full-mouth periapical series (14 radiographs) using the long-cone paralleling technique. Lithium fluoride (LiF 100) thermoluminescent dosemeters were placed in an anthropomorphic phantom at points corresponding to the tongue, thyroid, crystalline lenses, parotid glands and maxillary sinuses. Results: Dosemeter readings demonstrated the efficacy of the addition of lead foil in the intraoral digital X-ray systems provided in reducing organ doses in the selected structures, approximately 32% in the PSP system and 59% in the CMOS system. Conclusions: The use of lead foils associated with digital X-ray sensors is an effective alternative for the protection of different anatomical sites of the head and neck during full-mouth periapical series acquisition. PMID:26084474

  20. Real-time digital simulator with digital/analog conversion interface for testing power instruments

    SciTech Connect

    Taoka, Hisao; Iyoda, Isao; Noguchi, Hideo ); Sato, Nobuyuki; Nakazawa, Taro; Yamazaki, Akira )

    1994-05-01

    The need for real-time simulation stems from the fact that in many practical situations it is desirable to analyze the dynamic behavior of a large power system with advanced equipment that has complex and high-speed performance. Analog simulators are effective, however they impose serious limitations on the size of the system that is being modeled. The authors have studied and developed a real-time digital simulator using a hypercube computer, and realized a real-time performance available for the analysis of large power systems. Now as the second step of their study, they developed a digital/analog conversion interface for testing actual power instruments. The interface exchanges the variables of fundamental frequency domain in the real-time digital simulator, and the variables of exact time domain in the analog equipment connected to the simulator. In this paper, the authors describe the detail of their digital/analog conversion interface of a real-time digital simulator for testing advanced power instruments. Its conversion algorithm, system configuration of the simulator with the interface, experimental results are also presented in it.

  1. Digital communication system

    NASA Technical Reports Server (NTRS)

    Monford, L. G., Jr. (Inventor)

    1974-01-01

    A digital communication system is reported for parallel operation of 16 or more transceiver units with the use of only four interconnecting wires. A remote synchronization circuit produces unit address control words sequentially in data frames of 16 words. Means are provided in each transceiver unit to decode calling signals and to transmit calling and data signals. The transceivers communicate with each other over one data line. The synchronization unit communicates the address control information to the transceiver units over an address line and further provides the timing information over a clock line. A reference voltage level or ground line completes the interconnecting four wire hookup.

  2. Quadruplex digital flight control system assessment

    NASA Technical Reports Server (NTRS)

    Mulcare, D. B.; Downing, L. E.; Smith, M. K.

    1988-01-01

    Described are the development and validation of a double fail-operational digital flight control system architecture for critical pitch axis functions. Architectural tradeoffs are assessed, system simulator modifications are described, and demonstration testing results are critiqued. Assessment tools and their application are also illustrated. Ultimately, the vital role of system simulation, tailored to digital mechanization attributes, is shown to be essential to validating the airworthiness of full-time critical functions such as augmented fly-by-wire systems for relaxed static stability airplanes.

  3. Floating-point system quantization errors in digital control systems

    NASA Technical Reports Server (NTRS)

    Phillips, C. L.

    1973-01-01

    The results are reported of research into the effects on system operation of signal quantization in a digital control system. The investigation considered digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. An error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. As an output the program gives the programing form required for minimum system quantization errors (either maximum of rms errors), and the maximum and rms errors that appear in the system output for a given bit configuration. The program can be integrated into existing digital simulations of a system.

  4. Digital TV processing system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Two digital video data compression systems directly applicable to the Space Shuttle TV Communication System were described: (1) For the uplink, a low rate monochrome data compressor is used. The compression is achieved by using a motion detection technique in the Hadamard domain. To transform the variable source rate into a fixed rate, an adaptive rate buffer is provided. (2) For the downlink, a color data compressor is considered. The compression is achieved first by intra-color transformation of the original signal vector, into a vector which has lower information entropy. Then two-dimensional data compression techniques are applied to the Hadamard transformed components of this last vector. Mathematical models and data reliability analyses were also provided for the above video data compression techniques transmitted over a channel encoded Gaussian channel. It was shown that substantial gains can be achieved by the combination of video source and channel coding.

  5. Developing Digital Dashboard Management for Learning System Dynamic Cooperative Simulation Behavior of Indonesia. (Study on Cooperative Information Organization in the Ministry of Cooperatives and SME)

    NASA Astrophysics Data System (ADS)

    Eni, Yuli; Aryanto, Rudy

    2014-03-01

    There are problems being experienced by the Ministry of cooperatives and SME (Small and Medium Enterprise) including the length of time in the decision by the Government to establish a policy that should be taken for local cooperatives across the province of Indonesia. The decision-making process is still analyzed manually, so that sometimes the decisions taken are also less appropriate, effective and efficient. The second problem is the lack of monitoring data cooperative process province that is too much, making it difficult for the analysis of dynamic information to be useful. Therefore the authors want to fix the system that runs by using digital dashboard management system supported by the modeling of system dynamics. In addition, the author also did the design of a system that can support the system. Design of this system is aimed to ease the experts, head, and the government to decide (DSS - Decision Support System) accurately effectively and efficiently, because in the system are raised alternative simulation in a description of the decision to be taken and the result from the decision. The system is expected to be designed dan simulated can ease and expedite the decision making. The design of dynamic digital dashboard management conducted by method of OOAD (Objects Oriented Analysis and Design) complete with UML notation.

  6. Comparison of flight results with digital simulation for a digital electronic engine control in an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Myers, L. P.; Burcham, F. W., Jr.

    1983-01-01

    Substantial benefits of a full authority digital electronic engine control on an air breathing engine were demonstrated repeatedly in simulation studies, ground engine tests, and engine altitude test facilities. A digital engine electronic control system showed improvements in efficiency, performance, and operation. An additional benefit of full authority digital controls is the capability of detecting and correcting failures and providing engine health diagnostics.

  7. Digital Rock Simulation of Flow in Carbonate Samples

    NASA Astrophysics Data System (ADS)

    Klemin, D.; Andersen, M.

    2014-12-01

    Reservoir engineering has becomes more complex to deal with current challenges, so core analysts must understand and model pore geometries and fluid behaviors at pores scales more rapidly and realistically. We introduce an industry-unique direct hydrodynamic pore flow simulator that operates on pore geometries from digital rock models obtained using microCT or 3D scanning electron microscope (SEM) images. The PVT and rheological models used in the simulator represent real reservoir fluids. Fluid-solid interactions are introduced using distributed micro-scale wetting properties. The simulator uses density functional approach applied for hydrodynamics of complex systems. This talk covers selected applications of the simulator. We performed microCT scanning of six different carbonate rock samples from homogeneous limestones to vuggy carbonates. From these, we constructed digital rock models representing pore geometries for the simulator. We simulated nonreactive tracer flow in all six digital models using a digital fluid description that included a passive tracer solution. During the simulation, we evaluated the composition of the effluent. Results of tracer flow simulations corresponded well with experimental data of nonreactive tracer floods for the same carbonate rock types. This simulation data of the non-reactive tracer flow can be used to calculate the volume of the rock accessible by the fluid, which can be further used to predict response of a porous medium to a reactive fluid. The described digital core analysis workflow provides a basis for a wide variety of activities, including input to design acidizing jobs and evaluating treatment efficiency and EOR economics. Digital rock multiphase flow simulations of a scanned carbonate rock evaluated the effect of wettability on flow properties. Various wetting properties were tested: slightly oil wet, slightly water wet, and water wet. Steady-state relative permeability simulations yielded curves for all three

  8. Measuring noise equivalent irradiance of a digital short-wave infrared imaging system using a broadband source to simulate the night spectrum

    NASA Astrophysics Data System (ADS)

    Green, John R.; Robinson, Timothy

    2015-05-01

    There is a growing interest in developing helmet-mounted digital imaging systems (HMDIS) for integration into military aircraft cockpits. This interest stems from the multiple advantages of digital vs. analog imaging such as image fusion from multiple sensors, data processing to enhance the image contrast, superposition of non-imaging data over the image, and sending images to remote location for analysis. There are several properties an HMDIS must have in order to aid the pilot during night operations. In addition to the resolution, image refresh rate, dynamic range, and sensor uniformity over the entire Focal Plane Array (FPA); the imaging system must have the sensitivity to detect the limited night light available filtered through cockpit transparencies. Digital sensor sensitivity is generally measured monochromatically using a laser with a wavelength near the peak detector quantum efficiency, and is generally reported as either the Noise Equivalent Power (NEP) or Noise Equivalent Irradiance (NEI). This paper proposes a test system that measures NEI of Short-Wave Infrared (SWIR) digital imaging systems using a broadband source that simulates the night spectrum. This method has a few advantages over a monochromatic method. Namely, the test conditions provide spectrum closer to what is experienced by the end-user, and the resulting NEI may be compared directly to modeled night glow irradiance calculation. This comparison may be used to assess the Technology Readiness Level of the imaging system for the application. The test system is being developed under a Cooperative Research and Development Agreement (CRADA) with the Air Force Research Laboratory.

  9. Genetic Algorithms for Digital Quantum Simulations.

    PubMed

    Las Heras, U; Alvarez-Rodriguez, U; Solano, E; Sanz, M

    2016-06-10

    We propose genetic algorithms, which are robust optimization techniques inspired by natural selection, to enhance the versatility of digital quantum simulations. In this sense, we show that genetic algorithms can be employed to increase the fidelity and optimize the resource requirements of digital quantum simulation protocols while adapting naturally to the experimental constraints. Furthermore, this method allows us to reduce not only digital errors but also experimental errors in quantum gates. Indeed, by adding ancillary qubits, we design a modular gate made out of imperfect gates, whose fidelity is larger than the fidelity of any of the constituent gates. Finally, we prove that the proposed modular gates are resilient against different gate errors. PMID:27341220

  10. Digital Simulation Games for Social Studies Classrooms

    ERIC Educational Resources Information Center

    Devlin-Scherer, Roberta; Sardone, Nancy B.

    2010-01-01

    Data from ten teacher candidates studying teaching methods were analyzed to determine perceptions toward digital simulation games in the area of social studies. This research can be used as a conceptual model of how current teacher candidates react to new methods of instruction and determine how education programs might change existing curricula…

  11. Digital image-rectification system

    NASA Technical Reports Server (NTRS)

    Van Wie, P. H.; Stein, M.; Puccinelli, E.; Fields, B.

    1977-01-01

    System removes spatial distortions from data and brings data into conformance with Universal Transverse Mercator map projection, produces digital output products suitable for further machine processing and analysis, and fills need for geometrically corrected Landsat multispectral scanner digital data in several remote sensing application areas.

  12. Complex Digital Visual Systems

    ERIC Educational Resources Information Center

    Sweeny, Robert W.

    2013-01-01

    This article identifies possibilities for data visualization as art educational research practice. The author presents an analysis of the relationship between works of art and digital visual culture, employing aspects of network analysis drawn from the work of Barabási, Newman, and Watts (2006) and Castells (1994). Describing complex network…

  13. Obtaining schedules for digital systems

    NASA Technical Reports Server (NTRS)

    Jagadish, H. V.; Kailath, Thomas

    1991-01-01

    A systematic technique is presented to derive correct schedules for a synchronous digital system, given a signal flow graph for an algorithm. It is also shown how to use this technique to derive designs that are optimal in having the lowest latency, the highest throughput, or the smallest number of registers. The same technique can also be used to verify digital systems that have already been designed.

  14. FORTRAN IV Digital Filter Design Programs. Digital Systems Education Project.

    ERIC Educational Resources Information Center

    Reuss, E.; And Others

    The goals of the Digital Systems Education Project (DISE) include the development and distribution of educational/instructional materials in the digital systems area. Toward that end, this document contains three reports: (1) A FORTRAN IV Design Program for Low-Pass Butterworth and Chebychev Digital Filters; (2) A FORTRAN IV Design Program for…

  15. A method to produce and validate a digitally reconstructed radiograph-based computer simulation for optimisation of chest radiographs acquired with a computed radiography imaging system

    PubMed Central

    Moore, C S; Liney, G P; Beavis, A W; Saunderson, J R

    2011-01-01

    Objectives The purpose of this study was to develop and validate a computer model to produce realistic simulated computed radiography (CR) chest images using CT data sets of real patients. Methods Anatomical noise, which is the limiting factor in determining pathology in chest radiography, is realistically simulated by the CT data, and frequency-dependent noise has been added post-digitally reconstructed radiograph (DRR) generation to simulate exposure reduction. Realistic scatter and scatter fractions were measured in images of a chest phantom acquired on the CR system simulated by the computer model and added post-DRR calculation. Results The model has been validated with a phantom and patients and shown to provide predictions of signal-to-noise ratios (SNRs), tissue-to-rib ratios (TRRs: a measure of soft tissue pixel value to that of rib) and pixel value histograms that lie within the range of values measured with patients and the phantom. The maximum difference in measured SNR to that calculated was 10%. TRR values differed by a maximum of 1.3%. Conclusion Experienced image evaluators have responded positively to the DRR images, are satisfied they contain adequate anatomical features and have deemed them clinically acceptable. Therefore, the computer model can be used by image evaluators to grade chest images presented at different tube potentials and doses in order to optimise image quality and patient dose for clinical CR chest radiographs without the need for repeat patient exposures. PMID:21933979

  16. Advanced distributed simulation technology: Digital Voice Gateway Reference Guide

    NASA Astrophysics Data System (ADS)

    Vanhook, Dan; Stadler, Ed

    1994-01-01

    The Digital Voice Gateway (referred to as the 'DVG' in this document) transmits and receives four full duplex encoded speech channels over the Ethernet. The information in this document applies only to DVG's running firmware of the version listed on the title page. This document, previously named Digital Voice Gateway Reference Guide, BBN Systems and Technologies Corporation, Cambridge, MA 02138, was revised for revision 2.00. This new revision changes the network protocol used by the DVG, to comply with the SINCGARS radio simulation (For SIMNET 6.6.1). Because of the extensive changes to revision 2.00 a separate document was created rather than supplying change pages.

  17. Digital quantum simulation of fermionic models with a superconducting circuit.

    PubMed

    Barends, R; Lamata, L; Kelly, J; García-Álvarez, L; Fowler, A G; Megrant, A; Jeffrey, E; White, T C; Sank, D; Mutus, J Y; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Hoi, I-C; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Vainsencher, A; Wenner, J; Solano, E; Martinis, John M

    2015-01-01

    One of the key applications of quantum information is simulating nature. Fermions are ubiquitous in nature, appearing in condensed matter systems, chemistry and high energy physics. However, universally simulating their interactions is arguably one of the largest challenges, because of the difficulties arising from anticommutativity. Here we use digital methods to construct the required arbitrary interactions, and perform quantum simulation of up to four fermionic modes with a superconducting quantum circuit. We employ in excess of 300 quantum logic gates, and reach fidelities that are consistent with a simple model of uncorrelated errors. The presented approach is in principle scalable to a larger number of modes, and arbitrary spatial dimensions. PMID:26153660

  18. Digital quantum simulation of fermionic models with a superconducting circuit

    PubMed Central

    Barends, R.; Lamata, L.; Kelly, J.; García-Álvarez, L.; Fowler, A. G.; Megrant, A; Jeffrey, E; White, T. C.; Sank, D.; Mutus, J. Y.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Hoi, I.-C.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Vainsencher, A.; Wenner, J.; Solano, E.; Martinis, John M.

    2015-01-01

    One of the key applications of quantum information is simulating nature. Fermions are ubiquitous in nature, appearing in condensed matter systems, chemistry and high energy physics. However, universally simulating their interactions is arguably one of the largest challenges, because of the difficulties arising from anticommutativity. Here we use digital methods to construct the required arbitrary interactions, and perform quantum simulation of up to four fermionic modes with a superconducting quantum circuit. We employ in excess of 300 quantum logic gates, and reach fidelities that are consistent with a simple model of uncorrelated errors. The presented approach is in principle scalable to a larger number of modes, and arbitrary spatial dimensions. PMID:26153660

  19. Digital quantum simulation of fermionic models with a superconducting circuit

    NASA Astrophysics Data System (ADS)

    Barends, R.; Lamata, L.; Kelly, J.; García-Álvarez, L.; Fowler, A. G.; Megrant, A.; Jeffrey, E.; White, T. C.; Sank, D.; Mutus, J. Y.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Hoi, I.-C.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Vainsencher, A.; Wenner, J.; Solano, E.; Martinis, John M.

    2015-07-01

    One of the key applications of quantum information is simulating nature. Fermions are ubiquitous in nature, appearing in condensed matter systems, chemistry and high energy physics. However, universally simulating their interactions is arguably one of the largest challenges, because of the difficulties arising from anticommutativity. Here we use digital methods to construct the required arbitrary interactions, and perform quantum simulation of up to four fermionic modes with a superconducting quantum circuit. We employ in excess of 300 quantum logic gates, and reach fidelities that are consistent with a simple model of uncorrelated errors. The presented approach is in principle scalable to a larger number of modes, and arbitrary spatial dimensions.

  20. Security assessment of power systems including energy storage and with the integration of wind energy. Volume I. Digital transient simulation effort consulting Agreement No. 1. Final report

    SciTech Connect

    Anderson, P. M.

    1982-06-30

    The purpose of the effort reported has been to adapt the MOD-2 simulation models for implementation on a digital transient stability program. This has involved: selection of an appropriate host program, examination of the host program interface, analysis of the analog models for digital implementation, FORTRAN coding of the model equations, installation and debugging on the host program, and final model verification. Synchronous machine equations are analyzed, with particular emphasis on numerical solution. (LEW)

  1. Digital data processing system dynamic loading analysis

    NASA Technical Reports Server (NTRS)

    Lagas, J. J.; Peterka, J. J.; Tucker, A. E.

    1976-01-01

    Simulation and analysis of the Space Shuttle Orbiter Digital Data Processing System (DDPS) are reported. The mated flight and postseparation flight phases of the space shuttle's approach and landing test configuration were modeled utilizing the Information Management System Interpretative Model (IMSIM) in a computerized simulation modeling of the ALT hardware, software, and workload. System requirements simulated for the ALT configuration were defined. Sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and the sensitivity analyses, a test design is described for adapting, parameterizing, and executing the IMSIM. Varying load and stress conditions for the model execution are given. The analyses of the computer simulation runs were documented as results, conclusions, and recommendations for DDPS improvements.

  2. Upset susceptibility study employing circuit analysis and digital simulation

    NASA Technical Reports Server (NTRS)

    Carreno, V. A.

    1984-01-01

    This paper describes an approach to predicting the susceptibility of digital systems to signal disturbances. Electrical disturbances on a digital system's input and output lines can be induced by activities and conditions including static electricity, lightning discharge, Electromagnetic Interference (EMI) and Electromagnetic Pulsation (EMP). The electrical signal disturbances employed for the susceptibility study were limited to nondestructive levels, i.e., the system does not sustain partial or total physical damage and reset and/or reload will bring the system to an operational status. The front-end transition from the electrical disturbances to the equivalent digital signals was accomplished by computer-aided circuit analysis. The Super-Sceptre (system for circuit evaluation of transient radiation effects) Program was used. Gate models were developed according to manufacturers' performance specifications and parameters resulting from construction processes characteristic of the technology. Digital simulation at the gate and functional level was employed to determine the impact of the abnormal signals on system performance and to study the propagation characteristics of these signals through the system architecture. Example results are included for an Intel 8080 processor configuration.

  3. Comparison of digital controllers used in magnetic suspension and balance systems

    NASA Technical Reports Server (NTRS)

    Kilgore, William A.

    1990-01-01

    Dynamic systems that were once controlled by analog circuits are now controlled by digital computers. Presented is a comparison of the digital controllers presently used with magnetic suspension and balance systems. The overall responses of the systems are compared using a computer simulation of the magnetic suspension and balance system and the digital controllers. The comparisons include responses to both simulated force and position inputs. A preferred digital controller is determined from the simulated responses.

  4. Digital video display system

    NASA Technical Reports Server (NTRS)

    Zygielbaum, A. I.; Martin, W. L.; Engle, A.

    1973-01-01

    System displays image data in real time on 120,000-element raster scan with 2, 4, or 8 shades of grey. Designed for displaying planetary range Doppler data, system can be used for X-Y plotting, displaying alphanumerics, and providing image animation.

  5. BROADBAND DIGITAL GEOPHYSICAL TELEMETRY SYSTEM.

    USGS Publications Warehouse

    Seeley, Robert L.; Daniels, Jeffrey J.

    1984-01-01

    A system has been developed to simultaneously sample and transmit digital data from five remote geophysical data receiver stations to a control station that processes, displays, and stores the data. A microprocessor in each remote station receives commands from the control station over a single telemetry channel.

  6. Digital television system design study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.

    1976-01-01

    The use of digital techniques for transmission of pictorial data is discussed for multi-frame images (television). Video signals are processed in a manner which includes quantization and coding such that they are separable from the noise introduced into the channel. The performance of digital television systems is determined by the nature of the processing techniques (i.e., whether the video signal itself or, instead, something related to the video signal is quantized and coded) and to the quantization and coding schemes employed.

  7. A telerobotic digital controller system

    NASA Technical Reports Server (NTRS)

    Brown, Richard J.

    1992-01-01

    This system is a network of joint mounted dual axes digital servo-controllers (DDSC), providing control of various joints and end effectors of different robotic systems. This report provides description of and user required information for the Digital Controller System Network (DSCN) and, in particular, the DDSC, Model DDSC-2, developed to perform the controller functions. The DDSC can control 3 phase brushless or brush type DC motors, requiring up to 8 amps. Only four wires, two for power and 2 for serial communication, are required, except for local sensor and motor connections. This highly capable, very flexible, programmable servo-controller, contained on a single, compact printed circuit board measuring only 4.5 x 5.1 inches, is applicable to control systems of all types from sub-arc second precision pointing to control of robotic joints and end effectors. This document concentrates on the robotic applications for the DDSC.

  8. Digital Systems Analysis

    ERIC Educational Resources Information Center

    Martin, Vance S.

    2009-01-01

    There have been many attempts to understand how the Internet affects our modern world. There have also been numerous attempts to understand specific areas of the Internet. This article applies Immanuel Wallerstein's World Systems Analysis to our informationalist society. Understanding this world as divided among individual core, semi-periphery,…

  9. Modular all-digital closed-loop simulation for analysis and simulation of strategic interceptors

    NASA Astrophysics Data System (ADS)

    Finch, Mark T.; Flynn, David S.; Sieglinger, Breck A.; Franques, Victoria T.

    1993-08-01

    Simulation methods offer a time- and cost-effective approach to the evaluation and testing of guided missiles. These include hardware-in-the-loop as well as all-digital simulations which provide information about how a particular existing or proposed missile system might perform in hypothetical situations which may not be practically duplicated in reality. This paper describes an all-digital simulation developed using available components. The paper describes the functional flow of the simulation, and identifies the information which is passed between the independent modules. Several applications are described, and results such as intercept miss distances, line-of-sight pointing error statistics, and sensitivity to certain system parameters are demonstrated.

  10. Real-time simulation of jet engines with digital computer. 1: Fabrication and characteristics of the simulator

    NASA Technical Reports Server (NTRS)

    Nishio, K.; Sugiyama, N.; Koshinuma, T.; Hashimoto, T.; Ohata, T.; Ichikawa, H.

    1983-01-01

    The fabrication and performance of a real time jet engine simulator using a digital computer are discussed. The use of the simulator in developing the components and control system of a jet engine is described. Comparison of data from jet engine simulation tests with actual engine tests was conducted with good agreement.

  11. An improved method for simulating microcalcifications in digital mammograms

    PubMed Central

    Zanca, Federica; Chakraborty, Dev Prasad; Van Ongeval, Chantal; Jacobs, Jurgen; Claus, Filip; Marchal, Guy; Bosmans, Hilde

    2008-01-01

    The assessment of the performance of a digital mammography system requires an observer study with a relatively large number of cases with known truth which is often difficult to assemble. Several investigators have developed methods for generating hybrid abnormal images containing simulated microcalcifications. This article addresses some of the limitations of earlier methods. The new method is based on digital images of needle biopsy specimens. Since the specimens are imaged separately from the breast, the microcalcification attenuation profile scan is deduced without the effects of over and underlying tissues. The resulting templates are normalized for image acquisition specific parameters and reprocessed to simulate microcalcifications appropriate to other imaging systems, with different x-ray, detector and image processing parameters than the original acquisition system. This capability is not shared by previous simulation methods that have relied on extracting microcalcifications from breast images. The method was validated by five experienced mammographers who compared 59 pairs of simulated and real microcalcifications in a two-alternative forced choice task designed to test if they could distinguish the real from the simulated lesions. They also classified the shapes of the microcalcifications according to a standardized clinical lexicon. The observed probability of correct choice was 0.415, 95% confidence interval (0.284, 0.546), showing that the radiologists were unable to distinguish the lesions. The shape classification revealed substantial agreement with the truth (mean kappa=0.70), showing that we were able to accurately simulate the lesion morphology. While currently limited to single microcalcifications, the method is extensible to more complex clusters of microcalcifications and to three-dimensional images. It can be used to objectively assess an imaging technology, especially with respect to its ability to adequately visualize the morphology of the

  12. A Automated Tool for Supporting FMEAs of Digital Systems

    SciTech Connect

    Yue,M.; Chu, T.-L.; Martinez-Guridi, G.; Lehner, J.

    2008-09-07

    Although designs of digital systems can be very different from each other, they typically use many of the same types of generic digital components. Determining the impacts of the failure modes of these generic components on a digital system can be used to support development of a reliability model of the system. A novel approach was proposed for such a purpose by decomposing the system into a level of the generic digital components and propagating failure modes to the system level, which generally is time-consuming and difficult to implement. To overcome the associated issues of implementing the proposed FMEA approach, an automated tool for a digital feedwater control system (DFWCS) has been developed in this study. The automated FMEA tool is in nature a simulation platform developed by using or recreating the original source code of the different module software interfaced by input and output variables that represent physical signals exchanged between modules, the system, and the controlled process. For any given failure mode, its impacts on associated signals are determined first and the variables that correspond to these signals are modified accordingly by the simulation. Criteria are also developed, as part of the simulation platform, to determine whether the system has lost its automatic control function, which is defined as a system failure in this study. The conceptual development of the automated FMEA support tool can be generalized and applied to support FMEAs for reliability assessment of complex digital systems.

  13. Digital-simulation and projection of head changes in the Potomac-Raritan-Magothy aquifer system, coastal plain, New Jersey

    USGS Publications Warehouse

    Luzier, James E.

    1980-01-01

    (1) no increase in ground-water extractions; (2) continued growth in ground-water extractions at the rate of 1.7 and 3 percent annually; and (3) continued growth in ground-water extractions at the rate of 3 percent annually, in conjunction with the activitation of a freshwater head barrier in the fresh-salty transition zone. Under the first set of conditions, further head reduction would cease over very large regions within two years. Under the second set of conditions involving a 3 percent growth rate similar to that experienced during the simulation period, the broad cone of depression already encompassing most of the New Jersey Coastal Plain would broaden and deepen. Heads would range from 60 to 160 feet below National Geodetic Vertical Datum of 1929. The reduction of head after 1973 would approach 90 feet in some areas. The resultant steeper hydraullic gradients would accelerate the rate of movement of salty ground water toward the pumping centers. A freshwater head barrier could be established in the transition zone to prevent migration of salty ground water across a 35-mile stretch in Gloucester, Camden, and Burlington Counties. A line of injection wells would be required, with total rates of injection to the head barrier ranging from about 56 cubic feet per second in 1984 to about 95 cubic feet per second in 2000. Barrier recharge rates would be equivalent to about 20 percent of the ground water pumped in the fine-grid area in any particular year for a 3 percent increase in extractions.

  14. Interactive digital image manipulation system

    NASA Technical Reports Server (NTRS)

    Henze, J.; Dezur, R.

    1975-01-01

    The system is designed for manipulation, analysis, interpretation, and processing of a wide variety of image data. LANDSAT (ERTS) and other data in digital form can be input directly into the system. Photographic prints and transparencies are first converted to digital form with an on-line high-resolution microdensitometer. The system is implemented on a Hewlett-Packard 3000 computer with 128 K bytes of core memory and a 47.5 megabyte disk. It includes a true color display monitor, with processing memories, graphics overlays, and a movable cursor. Image data formats are flexible so that there is no restriction to a given set of remote sensors. Conversion between data types is available to provide a basis for comparison of the various data. Multispectral data is fully supported, and there is no restriction on the number of dimensions. In this way multispectral data collected at more than one point in time may simply be treated as a data collected with twice (three times, etc.) the number of sensors. There are various libraries of functions available to the user: processing functions, display functions, system functions, and earth resources applications functions.

  15. Hydrogeology, digital solute-transport simulation, and geochemistry of the Lower Cretaceous aquifer system near Baltimore, Maryland

    USGS Publications Warehouse

    Chapelle, Francis H.; with a section compiled by Kean, Tracey M.

    1985-01-01

    aquifer has a smaller zone of brackish-water contamination that has decreased in size since 1945. Borehole data demonstrate that the Arundel Formation has been breached by Pleistocene river channels near the Harbor district. These erosional channels provide a conduit for brackish water to intrude into the Patuxent aquifer. A two-dimensional areal solute-transport model of the Patuxent aquifer was constructed. This model was designed to estimate the future movement of the brackish-water plume based on alternative scenarios of aquifer use. Model simulations suggest that the plume will remain relatively immobile if 1982 pumping patterns continue into the foreseeable future. However, increased pumpage in the Marley Neck peninsula could draw the plume to the southeast and increase contamination of the Fairfield area. The water quality of the Patuxent aquifer is extremely variable. Because of this variability, it is useful to divide the aquifer into three water-quality zones: Zone 1 -- This zone corresponds to the plume of brackish-water contamination. Zone 2 -- This zone exhibits evidence of urbanization-related contamination such as measurable concentrations of organic chemicals and elevated concentrations of trace elements and total organic carbon. Zone 3 -- Water composition in this zone is controlled exclusively by naturally occurring chemical processes. These processes are dominated by reactions involving dissolved iron. Near the outcrop area, oxidation of pyrite and lignite consumes dissolved oxygen and produces ledges of iron hydroxide-cemented sandstones and conglomerates. The predominant dissolved iron species in oxic water is Fe(OH)2+. Downgradient, the water becomes anoxic and sulfate reduction becomes an important process. The predominant dissolved iron species in anoxic water is Fe2+.

  16. Optimal generalized multistep integration formulae for real-time digital simulation

    NASA Technical Reports Server (NTRS)

    Moerder, D. D.; Halyo, N.

    1985-01-01

    The problem of discretizing a dynamical system for real-time digital simulation is considered. Treating the system and its simulation as stochastic processes leads to a statistical characterization of simulator fidelity. A plant discretization procedure based on an efficient matrix generalization of explicit linear multistep discrete integration formulae is introduced, which minimizes a weighted sum of the mean squared steady-state and transient error between the system and simulator outputs.

  17. Simulating Rain Fade In A Communication System

    NASA Technical Reports Server (NTRS)

    Shalkhauser, Kurt A.; Nagy, Lawrence A.; Svoboda, James K.

    1994-01-01

    Automated, computer-controlled assembly of electronic equipment developed for use in simulation testing of downlink portion of Earth/satellite microwave digital communication system. Designed to show effects upon performance of system of rain-induced fading in received signal and increases in transmitted power meant to compensate for rain-induced fading. Design of communication system improved iteratively in response to results of simulations, leading eventually to design ensuring clear, uninterrupted transmission of digital signals.

  18. Digital Simulations: Facilitating Transition for Students with Disabilities

    ERIC Educational Resources Information Center

    Zionch, Allenda

    2011-01-01

    Today's students are digital natives. From computers to MP3 players, the everyday use of technology in society underscores the necessity of using technology in education. The use of digital simulations especially has had positive outcomes for students with disabilities in generalizing various life skills necessary for transition beyond high…

  19. Integrated assurance assessment of a reconfigurable digital flight control system

    NASA Technical Reports Server (NTRS)

    Ness, W. G.; Davis, R. M.; Benson, J. W.; Smith, M. K.; Eldredge, D.

    1983-01-01

    The integrated application of reliability, failure effects and system simulator methods in establishing the airworthiness of a flight critical digital flight control system (DFCS) is demonstrated. The emphasis was on the mutual reinforcement of the methods in demonstrating the system safety.

  20. A real-time digital computer program for the simulation of a single rotor helicopter

    NASA Technical Reports Server (NTRS)

    Houck, J. A.; Gibson, L. H.; Steinmetz, G. G.

    1974-01-01

    A computer program was developed for the study of a single-rotor helicopter on the Langley Research Center real-time digital simulation system. Descriptions of helicopter equations and data, program subroutines (including flow charts and listings), real-time simulation system routines, and program operation are included. Program usage is illustrated by standard check cases and a representative flight case.

  1. Digital quantum simulation of Dirac equation with a trapped ion

    NASA Astrophysics Data System (ADS)

    Shen, Yangchao; Zhang, Xiang; Zhang, Junhua; Casanova, Jorge; Lamata, Lucas; Solano, Enrique; Yung, Man-Hong; Zhang, Jingning; Kim, Kihwan; Department Of Physical Chemistry Collaboration

    2014-05-01

    Recently there has been growing interest in simulating relativistic effects in controllable physical system. We digitally simulate the Dirac equation in 3 +1 dimensions with a single trapped ion. We map four internal levels of 171Yb+ ion to the Dirac bispinor. The time evolution of the Dirac equation is implemented by trotter expansion. In the 3 +1 dimension, we can observe a helicoidal motion of a free Dirac particle which reduces to Zitterbewegung in 1 +1 dimension. This work was supported in part by the National Basic Research Program of China Grant 2011CBA00300, 2011CBA00301, the National Natural Science Foundation of China Grant 61033001, 61061130540. KK acknowledge the support from the recruitment program of global youth experts.

  2. [Digital ulcers in systemic scleroderma].

    PubMed

    Belz, D; Hunzelmann, N; Moinzadeh, P

    2014-11-01

    Digital ulcers (DU's) are one of the main symptoms of systemic scleroderma and occur in approximately 60% of all scleroderma patients. Due to possible complications such as infections, gangrene or amputation, they require regular medical attention and a good wound treatment by doctors and nursing staff. A definition of DU's has not yet been established. In 2009 the European League Against Rheumatism (EULAR) published guidelines for the treatment of DU's. An improvement of the healing of active ulcers has been described with Iloprost. Bosentan significantly reduced the frequency of occurrence of new DU's. In some small studies PDE-5 inhibitors appear helpful. Further studies with other therapeutic approaches will follow in the next few years. PMID:25336296

  3. Simulation of digital pixel readout chip architectures with the RD53 SystemVerilog-UVM verification environment using Monte Carlo physics data

    NASA Astrophysics Data System (ADS)

    Conti, E.; Marconi, S.; Christiansen, J.; Placidi, P.; Hemperek, T.

    2016-01-01

    The simulation and verification framework developed by the RD53 collaboration is a powerful tool for global architecture optimization and design verification of next generation hybrid pixel readout chips. In this paper the framework is used for studying digital pixel chip architectures at behavioral level. This is carried out by simulating a dedicated, highly parameterized pixel chip description, which makes it possible to investigate different grouping strategies between pixels and different latency buffering and arbitration schemes. The pixel hit information used as simulation input can be either generated internally in the framework or imported from external Monte Carlo detector simulation data. The latter have been provided by both the CMS and ATLAS experiments, featuring HL-LHC operating conditions and the specifications related to the Phase 2 upgrade. Pixel regions and double columns were simulated using such Monte Carlo data as inputs: the performance of different latency buffering architectures was compared and the compliance of different link speeds with the expected column data rate was verified.

  4. Comparison of properties of digital spectrometer systems.

    PubMed

    Mazanova, Monika; Dryak, Pavel; Kovar, Petr; Auerbach, Pavel

    2014-05-01

    We have tested two digital spectrometer systems, the DSP 9660 and Lynx(®) modules, connected to a HPGe detector. Lynx(®) is a fully integrated 32K channel signal analyzer based on digital signal processing techniques, which offers advanced digital stabilization. The model DSP 9660 digitalizes the signal directly at a very high sampling rate. The evaluated properties were integral nonlinearity, differential linearity, channel profiles, resolution and throughput. We found that the DSP system has slightly inferior resolution and throughput in comparison with the Lynx(®) system.

  5. Expected accuracy of tilt measurements on a novel hexapod-based digital zenith camera system: a Monte-Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Hirt, Christian; Papp, Gábor; Pál, András; Benedek, Judit; Szũcs, Eszter

    2014-08-01

    Digital zenith camera systems (DZCS) are dedicated astronomical-geodetic measurement systems for the observation of the direction of the plumb line. A DZCS key component is a pair of tilt meters for the determination of the instrumental tilt with respect to the plumb line. Highest accuracy (i.e., 0.1 arc-seconds or better) is achieved in practice through observation with precision tilt meters in opposite faces (180° instrumental rotation), and application of rigorous tilt reduction models. A novel concept proposes the development of a hexapod (Stewart platform)-based DZCS. However, hexapod-based total rotations are limited to about 30°-60° in azimuth (equivalent to ±15° to ±30° yaw rotation), which raises the question of the impact of the rotation angle between the two faces on the accuracy of the tilt measurement. The goal of the present study is the investigation of the expected accuracy of tilt measurements to be carried out on future hexapod-based DZCS, with special focus placed on the role of the limited rotation angle. A Monte-Carlo simulation study is carried out in order to derive accuracy estimates for the tilt determination as a function of several input parameters, and the results are validated against analytical error propagation. As the main result of the study, limitation of the instrumental rotation to 60° (30°) deteriorates the tilt accuracy by a factor of about 2 (4) compared to a 180° rotation between the faces. Nonetheless, a tilt accuracy at the 0.1 arc-second level is expected when the rotation is at least 45°, and 0.05 arc-second (about 0.25 microradian) accurate tilt meters are deployed. As such, a hexapod-based DZCS can be expected to allow sufficiently accurate determination of the instrumental tilt. This provides supporting evidence for the feasibility of such a novel instrumentation. The outcomes of our study are not only relevant to the field of DZCS, but also to all other types of instruments where the instrumental tilt

  6. Benefits of digital thoracic drainage systems.

    PubMed

    Danitsch, Debbie

    A number of risks and complications are associated with traditional chest drainage systems. A trust decided to trial digital drainage systems, and found the new systems improved treatment time and patient mobility. PMID:22536712

  7. DIGITAL SPALL RADIOGRAPH ANALYSIS SYSTEM

    SciTech Connect

    CURTIS L. HARRIS - LATA

    1990-01-01

    This report describes progress on work to develop a cost effective, rapid response system for measuring Technology Assessment National Laboratory. momentum and kinetic energy of span for the Advanced Center (ATAC) Armor/Anti-Armor (As) program at Los Alamos The system will exploit data contained in two sets of simultaneous co-planar flash radiographs taken along the center line of anticipated span motion. Data contained in each set (which is proportional to the mass and z-number of the span material intersected by the exposing x-ray at each point) is digitized and used to construct a three dimensional model (called the reconstructed span image) that approximates the original span cloud. From the model the mass of span fragments is computed. The two sets of radiographs, separated in time, represent the span configuration at two instants of time. Span fragments from the first instant are matched with those from the second instant to determine velocity. Evaluation of the fidelity of candidate reconstruction algorithms is the highest priority task in. this development program for the obvious reason that the efficacy of the projected span analysis system depends upon the fidelity of the reconstruction techniques.

  8. Digital Distortion Caused by Traveling- Wave-Tube Amplifiers Simulated

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Andro, Monty

    2002-01-01

    use a nonlinear, black-box model to represent the TWTA. The models vary in complexity, but most make several assumptions regarding the operation of the high-power amplifier. When the MAFIA TWT interaction model was used, these assumptions were found to be in significant error. In addition, digital signal performance, including intersymbol interference, was compared using direct data input into the MAFIA model and using the system-level analysis tool SPW for several higher order modulation schemes. Results show significant differences in predicted degradation between SPW and MAFIA simulations, demonstrating the significance of the TWTA approximations made in the SPW model on digital signal performance. For example, a comparison of the SPW and MAFIA output constellation diagrams for a 16-ary quadrature amplitude modulation (16-QAM) signal (data shown only for second and fourth quadrants) is shown. The upper-bound degradation was calculated from the corresponding eye diagrams. In comparison to SPW simulations, the MAFIA data resulted in a 3.6-dB larger degradation.

  9. Computer Simulation and Digital Resources for Plastic Surgery Psychomotor Education.

    PubMed

    Diaz-Siso, J Rodrigo; Plana, Natalie M; Stranix, John T; Cutting, Court B; McCarthy, Joseph G; Flores, Roberto L

    2016-10-01

    Contemporary plastic surgery residents are increasingly challenged to learn a greater number of complex surgical techniques within a limited period. Surgical simulation and digital education resources have the potential to address some limitations of the traditional training model, and have been shown to accelerate knowledge and skills acquisition. Although animal, cadaver, and bench models are widely used for skills and procedure-specific training, digital simulation has not been fully embraced within plastic surgery. Digital educational resources may play a future role in a multistage strategy for skills and procedures training. The authors present two virtual surgical simulators addressing procedural cognition for cleft repair and craniofacial surgery. Furthermore, the authors describe how partnerships among surgical educators, industry, and philanthropy can be a successful strategy for the development and maintenance of digital simulators and educational resources relevant to plastic surgery training. It is our responsibility as surgical educators not only to create these resources, but to demonstrate their utility for enhanced trainee knowledge and technical skills development. Currently available digital resources should be evaluated in partnership with plastic surgery educational societies to guide trainees and practitioners toward effective digital content. PMID:27673543

  10. Computer Simulation and Digital Resources for Plastic Surgery Psychomotor Education.

    PubMed

    Diaz-Siso, J Rodrigo; Plana, Natalie M; Stranix, John T; Cutting, Court B; McCarthy, Joseph G; Flores, Roberto L

    2016-10-01

    Contemporary plastic surgery residents are increasingly challenged to learn a greater number of complex surgical techniques within a limited period. Surgical simulation and digital education resources have the potential to address some limitations of the traditional training model, and have been shown to accelerate knowledge and skills acquisition. Although animal, cadaver, and bench models are widely used for skills and procedure-specific training, digital simulation has not been fully embraced within plastic surgery. Digital educational resources may play a future role in a multistage strategy for skills and procedures training. The authors present two virtual surgical simulators addressing procedural cognition for cleft repair and craniofacial surgery. Furthermore, the authors describe how partnerships among surgical educators, industry, and philanthropy can be a successful strategy for the development and maintenance of digital simulators and educational resources relevant to plastic surgery training. It is our responsibility as surgical educators not only to create these resources, but to demonstrate their utility for enhanced trainee knowledge and technical skills development. Currently available digital resources should be evaluated in partnership with plastic surgery educational societies to guide trainees and practitioners toward effective digital content.

  11. Digital flight control actuation system study

    NASA Technical Reports Server (NTRS)

    Rossing, R.; Hupp, R.

    1974-01-01

    Flight control actuators and feedback sensors suitable for use in a redundant digital flight control system were examined. The most appropriate design approach for an advanced digital flight control actuation system for development and use in a fly-by-wire system was selected. The concept which was selected consisted of a PM torque motor direct drive. The selected system is compatible with concurrent and independent development efforts on the computer system and the control law mechanizations.

  12. Integrating TV/digital data spectrograph system

    NASA Technical Reports Server (NTRS)

    Duncan, B. J.; Fay, T. D.; Miller, E. R.; Wamsteker, W.; Brown, R. M.; Neely, P. L.

    1975-01-01

    A 25-mm vidicon camera was previously modified to allow operation in an integration mode for low-light-level astronomical work. The camera was then mated to a low-dispersion spectrograph for obtaining spectral information in the 400 to 750 nm range. A high speed digital video image system was utilized to digitize the analog video signal, place the information directly into computer-type memory, and record data on digital magnetic tape for permanent storage and subsequent analysis.

  13. Enhanced TCAS 2/CDTI traffic Sensor digital simulation model and program description

    NASA Technical Reports Server (NTRS)

    Goka, T.

    1984-01-01

    Digital simulation models of enhanced TCAS 2/CDTI traffic sensors are developed, based on actual or projected operational and performance characteristics. Two enhanced Traffic (or Threat) Alert and Collision Avoidance Systems are considered. A digital simulation program is developed in FORTRAN. The program contains an executive with a semireal time batch processing capability. The simulation program can be interfaced with other modules with a minimum requirement. Both the traffic sensor and CAS logic modules are validated by means of extensive simulation runs. Selected validation cases are discussed in detail, and capabilities and limitations of the actual and simulated systems are noted. The TCAS systems are not specifically intended for Cockpit Display of Traffic Information (CDTI) applications. These systems are sufficiently general to allow implementation of CDTI functions within the real systems' constraints.

  14. Preservation Film: Platform for Digital Access Systems.

    ERIC Educational Resources Information Center

    Jones, C. Lee

    Preservation efforts for an increasingly digitally oriented future have turned to advanced and improved methods of preservation on microfilm, which has a life expectancy of more than 500 years when properly prepared, stored, and managed, and can support a wide range of digital access systems. Computer controlled cameras can provide significantly…

  15. Digital hydraulic valving system. [design and development

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The design and development are reported of a digital hydraulic valving system that would accept direct digital inputs. Topics include: summary of contractual accomplishments, design and function description, valve parameters and calculations, conclusions, and recommendations. The electrical control circuit operating procedure is outlined in an appendix.

  16. A multi-channel waveform digitizer system

    SciTech Connect

    Bieser, F.; Muller, W.F.J. )

    1990-04-01

    The authors report on the design and performance of a multichannel waveform digitizer system for use with the Multiple Sample Ionization Chamber (MUSIC) Detector at the Bevalac. 128 channels of 20 MHz Flash ADC plus 256 word deep memory are housed in a single crate. Digital thresholds and hit pattern logic facilitate zero suppression during readout which is performed over a standard VME bus.

  17. Digital Video Over Space Systems and Networks

    NASA Technical Reports Server (NTRS)

    Grubbs, Rodney

    2010-01-01

    This slide presentation reviews the use of digital video with space systems and networks. The earliest use of video was the use of film precluding live viewing, which gave way to live television from space. This has given way to digital video using internet protocol for transmission. This has provided for many improvements with new challenges. Some of these ehallenges are reviewed. The change to digital video transmitted over space systems can provide incredible imagery, however the process must be viewed as an entire system, rather than piece-meal.

  18. [Digital photograph storage systems in clinical dermatology].

    PubMed

    Taberner, R; Contestí, T

    2010-05-01

    In recent years, digital photography has consolidated its role in clinical dermatology. In view of the quality and low cost of current equipment and the simplicity of digital storage, almost all dermatologists now use digital photography, which is also extremely versatile and readily applicable to teaching. However, to maximize its full potential, image retrieval must be available at any time and with the patient present. This requires a suitable storage system that may vary according to the characteristics of each center. Dermatologists must also find time to maintain and organize the digital archives. The present article describes current options in digital image storage and retrieval, ranging from multidepartmental picture archiving and communication systems at one end to image management freeware at the other, and also including dedicated dermatology software.

  19. Digital controller design: Analysis of the annular suspension pointing system

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The annular suspension and pointing system (ASPS) a payload auxiliary pointing device of the space shuttle is briefly described along with the function of the digital controller. The equations of motion of a simplified plan planar model of the ASPS are derived. Results of computer simulations are discussed.

  20. Plans for wind energy system simulation

    NASA Technical Reports Server (NTRS)

    Dreier, M. E.

    1978-01-01

    A digital computer code and a special purpose hybrid computer, were introduced. The digital computer program, the Root Perturbation Method or RPM, is an implementation of the classic floquet procedure which circumvents numerical problems associated with the extraction of Floquet roots. The hybrid computer, the Wind Energy System Time domain simulator (WEST), yields real time loads and deformation information essential to design and system stability investigations.

  1. Digital Autonomous Terminal Access Communication (DATAC) system

    NASA Technical Reports Server (NTRS)

    Novacki, Stanley M., III

    1987-01-01

    In order to accommodate the increasing number of computerized subsystems aboard today's more fuel efficient aircraft, the Boeing Co. has developed the DATAC (Digital Autonomous Terminal Access Control) bus to minimize the need for point-to-point wiring to interconnect these various systems, thereby reducing total aircraft weight and maintaining an economical flight configuration. The DATAC bus is essentially a local area network providing interconnections for any of the flight management and control systems aboard the aircraft. The task of developing a Bus Monitor Unit was broken down into four subtasks: (1) providing a hardware interface between the DATAC bus and the Z8000-based microcomputer system to be used as the bus monitor; (2) establishing a communication link between the Z8000 system and a CP/M-based computer system; (3) generation of data reduction and display software to output data to the console device; and (4) development of a DATAC Terminal Simulator to facilitate testing of the hardware and software which transfer data between the DATAC's bus and the operator's console in a near real time environment. These tasks are briefly discussed.

  2. Modular digital holographic fringe data processing system

    NASA Technical Reports Server (NTRS)

    Downward, J. G.; Vavra, P. C.; Schebor, F. S.; Vest, C. M.

    1985-01-01

    A software architecture suitable for reducing holographic fringe data into useful engineering data is developed and tested. The results, along with a detailed description of the proposed architecture for a Modular Digital Fringe Analysis System, are presented.

  3. Digital control system for space structural dampers

    NASA Technical Reports Server (NTRS)

    Haviland, J. K.

    1984-01-01

    Digital control systems for space structural dampers, also referred to as inertia or proof-mass dampers are investigated. A damper concept is improved by adding a small taper to the proof-mass, and using a proximeter to determine position. Another damper using a three inch stroke rather than the standard one inch stroke is described. Provisions are made for a relative velocity feedback. In one approach, the digital controller is modified to accept the signal from a linear velocity transducer. In the other, the velocity feedback is included in the digital program. An overall system concept for the use of the dampers is presented.

  4. Experimental OAI-Based Digital Library Systems

    NASA Technical Reports Server (NTRS)

    Nelson, Michael L. (Editor); Maly, Kurt (Editor); Zubair, Mohammad (Editor); Rusch-Feja, Diann (Editor)

    2002-01-01

    The objective of Open Archives Initiative (OAI) is to develop a simple, lightweight framework to facilitate the discovery of content in distributed archives (http://www.openarchives.org). The focus of the workshop held at the 5th European Conference on Research and Advanced Technology for Digital Libraries (ECDL 2001) was to bring researchers in the area of digital libraries who are building OAI based systems so as to share their experiences, problems they are facing, and approaches they are taking to address them. The workshop consisted of invited talks from well-established researchers working in building OAI based digital library system along with short paper presentations.

  5. High Density Digital Data Storage System

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth D., II; Gray, David L.; Rowland, Wayne D.

    1991-01-01

    The High Density Digital Data Storage System was designed to provide a cost effective means for storing real-time data from the field-deployable digital acoustic measurement system. However, the high density data storage system is a standalone system that could provide a storage solution for many other real time data acquisition applications. The storage system has inputs for up to 20 channels of 16-bit digital data. The high density tape recorders presently being used in the storage system are capable of storing over 5 gigabytes of data at overall transfer rates of 500 kilobytes per second. However, through the use of data compression techniques the system storage capacity and transfer rate can be doubled. Two tape recorders have been incorporated into the storage system to produce a backup tape of data in real-time. An analog output is provided for each data channel as a means of monitoring the data as it is being recorded.

  6. Digital simulation of hybrid loop operation in RFI backgrounds.

    NASA Technical Reports Server (NTRS)

    Ziemer, R. E.; Nelson, D. R.

    1972-01-01

    A digital computer model for Monte-Carlo simulation of an imperfect second-order hybrid phase-locked loop (PLL) operating in radio-frequency interference (RFI) and Gaussian noise backgrounds has been developed. Characterization of hybrid loop performance in terms of cycle slipping statistics and phase error variance, through computer simulation, indicates that the hybrid loop has desirable performance characteristics in RFI backgrounds over the conventional PLL or the costas loop.

  7. Rocket noise filtering system using digital filters

    NASA Technical Reports Server (NTRS)

    Mauritzen, David

    1990-01-01

    A set of digital filters is designed to filter rocket noise to various bandwidths. The filters are designed to have constant group delay and are implemented in software on a general purpose computer. The Parks-McClellan algorithm is used. Preliminary tests are performed to verify the design and implementation. An analog filter which was previously employed is also simulated.

  8. Digital quantum simulation of the statistical mechanics of a frustrated magnet.

    PubMed

    Zhang, Jingfu; Yung, Man-Hong; Laflamme, Raymond; Aspuru-Guzik, Alán; Baugh, Jonathan

    2012-06-06

    Many problems of interest in physics, chemistry and computer science are equivalent to problems defined on systems of interacting spins. However, most such problems require computational resources that are out of reach with classical computers. A promising solution to overcome this challenge is quantum simulation. Several 'analogue' quantum simulations of interacting spin systems have been realized experimentally, where ground states were prepared using adiabatic techniques. Here we report a 'digital' quantum simulation of thermal states; a three-spin frustrated magnet was simulated using a nuclear magnetic resonance quantum information processor, and we were able to explore the phase diagram of the system at any simulated temperature and external field. These results help to identify the challenges for performing quantum simulations of physical systems at finite temperatures, and suggest methods that may be useful in simulating thermal open quantum systems.

  9. Numerical Simulations of the Digital Microfluidic Manipulation of Single Microparticles.

    PubMed

    Lan, Chuanjin; Pal, Souvik; Li, Zhen; Ma, Yanbao

    2015-09-01

    Single-cell analysis techniques have been developed as a valuable bioanalytical tool for elucidating cellular heterogeneity at genomic, proteomic, and cellular levels. Cell manipulation is an indispensable process for single-cell analysis. Digital microfluidics (DMF) is an important platform for conducting cell manipulation and single-cell analysis in a high-throughput fashion. However, the manipulation of single cells in DMF has not been quantitatively studied so far. In this article, we investigate the interaction of a single microparticle with a liquid droplet on a flat substrate using numerical simulations. The droplet is driven by capillary force generated from the wettability gradient of the substrate. Considering the Brownian motion of microparticles, we utilize many-body dissipative particle dynamics (MDPD), an off-lattice mesoscopic simulation technique, in this numerical study. The manipulation processes (including pickup, transport, and drop-off) of a single microparticle with a liquid droplet are simulated. Parametric studies are conducted to investigate the effects on the manipulation processes from the droplet size, wettability gradient, wetting properties of the microparticle, and particle-substrate friction coefficients. The numerical results show that the pickup, transport, and drop-off processes can be precisely controlled by these parameters. On the basis of the numerical results, a trap-free delivery of a hydrophobic microparticle to a destination on the substrate is demonstrated in the numerical simulations. The numerical results not only provide a fundamental understanding of interactions among the microparticle, the droplet, and the substrate but also demonstrate a new technique for the trap-free immobilization of single hydrophobic microparticles in the DMF design. Finally, our numerical method also provides a powerful design and optimization tool for the manipulation of microparticles in DMF systems.

  10. Numerical Simulations of the Digital Microfluidic Manipulation of Single Microparticles.

    PubMed

    Lan, Chuanjin; Pal, Souvik; Li, Zhen; Ma, Yanbao

    2015-09-01

    Single-cell analysis techniques have been developed as a valuable bioanalytical tool for elucidating cellular heterogeneity at genomic, proteomic, and cellular levels. Cell manipulation is an indispensable process for single-cell analysis. Digital microfluidics (DMF) is an important platform for conducting cell manipulation and single-cell analysis in a high-throughput fashion. However, the manipulation of single cells in DMF has not been quantitatively studied so far. In this article, we investigate the interaction of a single microparticle with a liquid droplet on a flat substrate using numerical simulations. The droplet is driven by capillary force generated from the wettability gradient of the substrate. Considering the Brownian motion of microparticles, we utilize many-body dissipative particle dynamics (MDPD), an off-lattice mesoscopic simulation technique, in this numerical study. The manipulation processes (including pickup, transport, and drop-off) of a single microparticle with a liquid droplet are simulated. Parametric studies are conducted to investigate the effects on the manipulation processes from the droplet size, wettability gradient, wetting properties of the microparticle, and particle-substrate friction coefficients. The numerical results show that the pickup, transport, and drop-off processes can be precisely controlled by these parameters. On the basis of the numerical results, a trap-free delivery of a hydrophobic microparticle to a destination on the substrate is demonstrated in the numerical simulations. The numerical results not only provide a fundamental understanding of interactions among the microparticle, the droplet, and the substrate but also demonstrate a new technique for the trap-free immobilization of single hydrophobic microparticles in the DMF design. Finally, our numerical method also provides a powerful design and optimization tool for the manipulation of microparticles in DMF systems. PMID:26241832

  11. A Digital Computer Simulation of Cardiovascular and Renal Physiology.

    ERIC Educational Resources Information Center

    Tidball, Charles S.

    1979-01-01

    Presents the physiological MACPEE, one of a family of digital computer simulations used in Canada and Great Britain. A general description of the model is provided, along with a sample of computer output format, options for making interventions, advanced capabilities, an evaluation, and technical information for running a MAC model. (MA)

  12. Digital Simulation-Based Training: A Meta-Analysis

    ERIC Educational Resources Information Center

    Gegenfurtner, Andreas; Quesada-Pallarès, Carla; Knogler, Maximilian

    2014-01-01

    This study examines how design characteristics in digital simulation-based learning environments moderate self-efficacy and transfer of learning. Drawing on social cognitive theory and the cognitive theory of multimedia learning, the meta-analysis psychometrically cumulated k?=?15 studies of 25 years of research with a total sample size of…

  13. A digital simulation of the glacial-aquifer system in Sanborn and parts of Beadle, Miner, Hanson, Davison, and Jerauld counties, South Dakota

    USGS Publications Warehouse

    Emmons, P.J.

    1988-01-01

    The drought in South Dakota from 1974-76 and the near drought conditions in 1980-81 have resulted in increased demands on the groundwater resources within many of the irrigated areas of the James River basin in eastern South Dakota. These increases in demand for irrigation water from the glacial aquifer system, and continued requests to the State for additional irrigation well permits, have created a need for a systematic water management program to avoid over-development of this system in the James River basin. An equally spaced grid containing 56 rows and 52 columns used to simulate the glacial aquifer system, was calibrated using water level data collected before significant groundwater development (before 1973). The aquifer was also simulated in 11 annual transient stress periods from 1973 through 1983 and in 12 monthly transient stress periods for 1976. The simulated pre-development potentiometric heads were compared to average water levels from 32 observation wells to check the accuracy of the simulate potentiometric surface. The average arithmetic difference between the simulated and observed water levels was 1.68 ft and the average absolute difference was 4.38 ft. The non-pumping steady-state simulated water budget indicates that recharge from precipitation accounts for 97.1% of the water entering the aquifer and evapotranspiration accounts for 98.2% of the water leaving the aquifer. The sensitivity analysis of the steady-state model indicates that the model is most sensitive to reductions in recharge and least to changes in hydraulic conductivity. The maximum annual recharge varied from 0.10 inch in 1976 to 8.14 inches in 1977. The potential annual evapotranspiration varied from 29.9 inches in 1982 to 48.9 inches in 1976. Withdrawals from the glacial aquifer system increased 2.6 times between 1975 and 1976. The average annual arithmetic difference between the simulated and observed water levels ranged from 3.88 ft in 1974 to 2.23 ft in 1982; the average

  14. Distribution system simulator

    NASA Technical Reports Server (NTRS)

    Bahrami, K. A.; Kirkham, H.; Rahman, S.

    1986-01-01

    In a series of tests performed under the Department of Energy auspices, power line carrier propagation was observed to be anomalous under certain circumstances. To investigate the cause, a distribution system simulator was constructed. The simulator was a physical simulator that accurately represented the distribution system from below power frequency to above 50 kHz. Effects such as phase-to-phase coupling and skin effect were modeled. Construction details of the simulator, and experimental results from its use are presented.

  15. Development Of A Digital Mammography System

    NASA Astrophysics Data System (ADS)

    Yaffe, M. J.; Nishikawa, R. M.; Maidment, A. D. A.; Fenster, A.

    1988-06-01

    A digital breast imaging system is under development to provide improved detectability of breast cancer. In previous work, the limitations of screen-film mammography were studied using both theoretical and experimental techniques. Important limitations were found in both the acquisition and the display components of imaging. These have been addressed in the design of a scanned-projection digital mammography system. A high resolution x-ray image intensifier (XRII), optically coupled to a self-scanned linear photodiode array, is used to record the image. Pre- and post-patient collimation virtually eliminates scattered radiation and veiling glare of the XRII with only a 20% increase in dose due to penumbra. Geometric magnification of 1.6 times is employed to achieve limiting spatial resolution of 7 1p/mm. For low-contrast objects as small as 0.1 mm in diameter, the digital system is capable of producing images with higher contrast and signal-to-noise ratio than optimally-exposed conventional film-screen mammography systems. Greater latitude is obtainable on the digital system because of its wide dynamic range and linearity. The slit system is limited due to long image acquisition times, and poor quantum efficiency. This motivated our current work on a slot beam digital mammography system which is based on a fiber-optic x-ray detector. Preliminary results of this system will be presented.

  16. FAST DIGITAL ORBIT FEEDBACK SYSTEMS AT NSLS.

    SciTech Connect

    PODOBEDOV,B.; KUSHNER,B.; RAMAMOORTHY,S.; TANG,Y.; ZITVOGEL,E.

    2001-06-18

    We are implementing digital orbit feedback systems to replace the analog ones in both the VUV and the X-ray rings. We developed an original VME-based design which is run by a powerful Motorola 2305 CPU and consists entirely of off-the-shelf VME boards. This makes the system inexpensive and easy to configure, and allows for high digitizing rates. The new 5 kHz digital global feedback system is currently operational in the VUV ring, and the X-ray system is in the commissioning phase. Some of the parameters achieved include vertical correction bandwidth of 200 Hz (at DC gain of 100) and typical orbit drift over a fill of <3% of the rms beam size. In this paper we discuss the system architecture, implementation and performance.

  17. A new digital land mobile satellite system

    NASA Technical Reports Server (NTRS)

    Schneider, Philip

    1990-01-01

    A description is given of the different digital services planned to be carried over existing and planned mobile satellite systems. These systems are then compared with analog services in terms of bandwidth and power efficiency. This comparison provides the rationale for the establishment of a digital land mobile satellite service (DLMSS) to use frequencies that are currently available but not yet assigned to a domestic mobile satellite system in the United States. The focus here is on the expected advantages of digital transmission techniques in accommodating additional mobile satellite systems in this portion of the spectrum, and how such techniques can fully satisfy voice, data and facsimile mobile communications requirements in a cost effective manner. A description is given of the system architecture of the DMLSS service proposed by the Geostar Messaging Corporation (GMC) and the market potential of DLMSS.

  18. Comparison of slot scanning digital mammography system with full-field digital mammography system

    SciTech Connect

    Lai, C.-J.; Shaw, Chris C.; Geiser, William; Chen, Lingyun; Arribas, Elsa; Stephens, Tanya; Davis, Paul L.; Ayyar, Geetha P.; Dogan, Basak E.; Nguyen, Victoria A.; Whitman, Gary J.; Yang, Wei T.

    2008-06-15

    The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125-160 and 200-250 {mu}m calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose/50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (A{sub z}) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher A{sub z}'s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant.

  19. Description of a digital computer simulation of an Annular Momentum Control Device (AMCD) laboratory test model

    NASA Technical Reports Server (NTRS)

    Woolley, C. T.; Groom, N. J.

    1981-01-01

    A description of a digital computer simulation of an Annular Momentum Control Device (AMCD) laboratory model is presented. The AMCD is a momentum exchange device which is under development as an advanced control effector for spacecraft attitude control systems. The digital computer simulation of this device incorporates the following models: six degree of freedom rigid body dynamics; rim warp; controller dynamics; nonlinear distributed element axial bearings; as well as power driver and power supply current limits. An annotated FORTRAN IV source code listing of the computer program is included.

  20. How processing digital elevation models can affect simulated water budgets

    USGS Publications Warehouse

    Kuniansky, E.L.; Lowery, M.A.; Campbell, B.G.

    2009-01-01

    For regional models, the shallow water table surface is often used as a source/sink boundary condition, as model grid scale precludes simulation of the water table aquifer. This approach is appropriate when the water table surface is relatively stationary. Since water table surface maps are not readily available, the elevation of the water table used in model cells is estimated via a two-step process. First, a regression equation is developed using existing land and water table elevations from wells in the area. This equation is then used to predict the water table surface for each model cell using land surface elevation available from digital elevation models (DEM). Two methods of processing DEM for estimating the land surface for each cell are commonly used (value nearest the cell centroid or mean value in the cell). This article demonstrates how these two methods of DEM processing can affect the simulated water budget. For the example presented, approximately 20% more total flow through the aquifer system is simulated if the centroid value rather than the mean value is used. This is due to the one-third greater average ground water gradients associated with the centroid value than the mean value. The results will vary depending on the particular model area topography and cell size. The use of the mean DEM value in each model cell will result in a more conservative water budget and is more appropriate because the model cell water table value should be representative of the entire cell area, not the centroid of the model cell.

  1. Scalable computer architecture for digital vascular systems

    NASA Astrophysics Data System (ADS)

    Goddard, Iain; Chao, Hui; Skalabrin, Mark

    1998-06-01

    Digital vascular computer systems are used for radiology and fluoroscopy (R/F), angiography, and cardiac applications. In the United States alone, about 26 million procedures of these types are performed annually: about 81% R/F, 11% cardiac, and 8% angiography. Digital vascular systems have a very wide range of performance requirements, especially in terms of data rates. In addition, new features are added over time as they are shown to be clinically efficacious. Application-specific processing modes such as roadmapping, peak opacification, and bolus chasing are particular to some vascular systems. New algorithms continue to be developed and proven, such as Cox and deJager's precise registration methods for masks and live images in digital subtraction angiography. A computer architecture must have high scalability and reconfigurability to meet the needs of this modality. Ideally, the architecture could also serve as the basis for a nonvascular R/F system.

  2. Instrumented Architectural Simulation System

    NASA Technical Reports Server (NTRS)

    Delagi, B. A.; Saraiya, N.; Nishimura, S.; Byrd, G.

    1987-01-01

    Simulation of systems at an architectural level can offer an effective way to study critical design choices if (1) the performance of the simulator is adequate to examine designs executing significant code bodies, not just toy problems or small application fragements, (2) the details of the simulation include the critical details of the design, (3) the view of the design presented by the simulator instrumentation leads to useful insights on the problems with the design, and (4) there is enough flexibility in the simulation system so that the asking of unplanned questions is not suppressed by the weight of the mechanics involved in making changes either in the design or its measurement. A simulation system with these goals is described together with the approach to its implementation. Its application to the study of a particular class of multiprocessor hardware system architectures is illustrated.

  3. Digital adaptive optics line-scanning confocal imaging system.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2015-01-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  4. Digital adaptive optics line-scanning confocal imaging system

    PubMed Central

    Liu, Changgeng; Kim, Myung K.

    2015-01-01

    Abstract. A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea. PMID:26140334

  5. Digital adaptive optics line-scanning confocal imaging system.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2015-01-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea. PMID:26140334

  6. Digital adaptive optics line-scanning confocal imaging system

    NASA Astrophysics Data System (ADS)

    Liu, Changgeng; Kim, Myung K.

    2015-11-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack-Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  7. 47 CFR 74.796 - Modification of digital transmission systems and analog transmission systems for digital operation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Modification of digital transmission systems and analog transmission systems for digital operation. 74.796 Section 74.796 Telecommunication FEDERAL....796 Modification of digital transmission systems and analog transmission systems for digital...

  8. Life-critical digital flight control systems

    NASA Technical Reports Server (NTRS)

    Mcwha, James

    1990-01-01

    Digital autopilot systems were first used on commercial airplanes in the late 1970s. The A-320 airplane was the first air transport airplane with a fly-by-wire primary flight control system. On the 767-X (777) airplane Boeing will install all fly-by-wire flight controls. Activities related to safety, industry status and program phases are discussed.

  9. The Role of a Digital Librarian in the Management of Digital Information Systems (DIS).

    ERIC Educational Resources Information Center

    Sreenivasulu, V.

    2000-01-01

    Discusses the need for digital librarians who will manage and organize digital libraries. Topics include digital information systems; the information superhighway; navigation, browsing, and filtering; multimedia searching and indexing; data mining; information access and retrieval; competencies and skills for a digital librarian; and professional…

  10. Simulation results for an innovative anti-multipath digital receiver

    NASA Technical Reports Server (NTRS)

    Painter, J. H.; Wilson, L. R.

    1973-01-01

    Simulation results are presented for the error rate performance of the recursive digital MAP detector for known M-ary signals in multiplicative and additive Gaussian noise. Plots of detection error rate versus additive signal to noise ratio are given, with multipath interference strength as a parameter. For comparison, the error rates of conventional coherent and noncoherent digital MAP detectors are simultaneously simulated and graphed. It is shown that with nonzero multiplicative noise, the error rates of the conventional detectors saturate at an irreducible level as additive signal to noise ratio increases. The error rate for the innovative detector continues to decrease rapidly with increasing additive signal to noise ratio. In the absence of multiplicative interference, the conventional coherent detector and the innovative detector are shown to exhibit identical performance.-

  11. Digital imaging-based retinal photocoagulation system

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Wright, Cameron H. G.; Oberg, Erik D.; Rockwell, Benjamin A.; Cain, Clarence P.; Rylander, Henry G., III; Welch, Ashley J.

    1997-05-01

    Researchers at the USAF Academy and the University of Texas are developing a computer-assisted retinal photocoagulation system for the treatment of retinal disorders (i.e. diabetic retinopathy, retinal tears). Currently, ophthalmologists manually place therapeutic retinal lesions, an acquired technique that is tiring for both the patient and physician. The computer-assisted system under development can rapidly and safely place multiple therapeutic lesions at desired locations on the retina in a matter of seconds. Separate prototype subsystems have been developed to control lesion depth during irradiation and lesion placement to compensate for retinal movement. Both subsystems have been successfully demonstrated in vivo on pigmented rabbits using an argon continuous wave laser. Two different design approaches are being pursued to combine the capabilities of both subsystems: a digital imaging-based system and a hybrid analog-digital system. This paper will focus on progress with the digital imaging-based prototype system. A separate paper on the hybrid analog-digital system, `Hybrid Retinal Photocoagulation System', is also presented in this session.

  12. Digital PIV (DPIV) Software Analysis System

    NASA Technical Reports Server (NTRS)

    Blackshire, James L.

    1997-01-01

    A software package was developed to provide a Digital PIV (DPIV) capability for NASA LaRC. The system provides an automated image capture, test correlation, and autocorrelation analysis capability for the Kodak Megaplus 1.4 digital camera system for PIV measurements. The package includes three separate programs that, when used together with the PIV data validation algorithm, constitutes a complete DPIV analysis capability. The programs are run on an IBM PC/AT host computer running either Microsoft Windows 3.1 or Windows 95 using a 'quickwin' format that allows simple user interface and output capabilities to the windows environment.

  13. High-Density Digital Data Storage System

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth D.; Gray, David L.

    1995-01-01

    High-density digital data storage system designed for cost-effective storage of large amounts of information acquired during experiments. System accepts up to 20 channels of 16-bit digital data with overall transfer rates of 500 kilobytes per second. Data recorded on 8-millimeter magnetic tape in cartridges, each capable of holding up to five gigabytes of data. Each cartridge mounted on one of two tape drives. Operator chooses to use either or both of drives. One drive used for primary storage of data while other can be used to make a duplicate record of data. Alternatively, other drive serves as backup data-storage drive when primary one fails.

  14. Immunizing digital systems against electromagnetic interference

    NASA Astrophysics Data System (ADS)

    Ewing, P. D.; Korsah, K.; Antonescu, C.

    This paper discusses the development of the technical basis for acceptance criteria applicable to the immunization of digital systems against electromagnetic interference (EMI). The work is sponsored by the US Nuclear Regulatory Commission and stems from the safety-related issues that need to be addressed as a result of the application of digital instrumentation and control systems in nuclear power plants. Designers of digital circuits are incorporating increasingly higher clock frequencies and lower logic level voltages, thereby leading to potentially greater susceptibility of spurious interference being misinterpreted as legitimate logic. Development of the technical basis for acceptance criteria to apply to these digital systems centers around establishing good engineering practices to ensure that sufficient levels of electromagnetic compatibility (EMC) are maintained between the nuclear power plant's electronic and electromechanical systems. First, good EMC design and installation practices are needed to control the emissions from interference sources and thereby their impact on other nearby circuits and systems. Secondly, a test and evaluation program is needed to outline the EMI tests to be performed, the associated test methods to be followed, and adequate test limits to ensure that the circuit or system under test meets the recommended guidelines. Test and evaluation should be followed by periodic maintenance to assess whether the recommended EMI control practices continue to be adhered to as part of the routine operation of the nuclear power plant. By following these steps, the probability of encountering safety-related instrumentation problems associated with EMI will be greatly reduced.

  15. A LANDSAT digital image rectification system

    NASA Technical Reports Server (NTRS)

    Vanwie, P.; Stein, M.

    1976-01-01

    DIRS is a digital image rectification system for the geometric correction of LANDSAT multispectral scanner digital image data. DIRS removes spatial distortions from the data and brings it into conformance with the Universal Transverse Mercator (UTM) map projection. Scene data in the form of landmarks are used to drive the geometric correction algorithms. Two dimensional least squares polynominal and spacecraft attitude modeling techniques for geometric mapping are provided. Entire scenes or selected quadrilaterals may be rectified. Resampling through nearest neighbor or cubic convolution at user designated intervals is available. The output products are in the form of digital tape in band interleaved, single band or CCT format in a rotated UTM projection. The system was designed and implemented on large scale IBM 360 computers.

  16. Digital control system for space structure dampers

    NASA Technical Reports Server (NTRS)

    Haviland, J. K.

    1985-01-01

    A digital controller was developed using an SKD-51 System Design Kit, which incorporates an 8031 microcontroller. The necessary interfaces were installed in the wire wrap area of the SKD-51 and a pulse width modulator was developed to drive the coil of the actuator. Also, control equations were developed, using floating-point arithmetic. The design of the digital control system is emphasized, and it is shown that, provided certain rules are followed, an adequate design can be achieved. It is recommended that the so-called w-plane design method be used, and that the time elapsed before output of the up-dated coil-force signal be kept as small as possible. However, the cycle time for the controller should be watched carefully, because very small values for this time can lead to digital noise.

  17. Integrated digital avionic systems - Promise and threats

    NASA Astrophysics Data System (ADS)

    Zempolich, B. A.

    1983-10-01

    The progress being made in effective systems design implementation for digital equipment for aircraft avionics sytems is assayed. The history of digital systems integration in avionics hardware is traced from use of 16-transistor chips to emerging 100,000 gate chips, and attention is given to architectural considerations for future hardware. Design considerations include top-down or bottom-up architecture, distributed microprocessor and computer resources, integrated components or data fusion, etc. Systems decomposition practices in design permit separate design of flight safety systems, redundancy, fault tolerance, and identifying components that feature different technologies. Present flight control systems sport a MBTF of 1,000,000 hr when separate controls are installed for each flight system.

  18. National Guidelines for Digital Camera Systems Certification

    NASA Astrophysics Data System (ADS)

    Yaron, Yaron; Keinan, Eran; Benhamu, Moshe; Regev, Ronen; Zalmanzon, Garry

    2016-06-01

    Digital camera systems are a key component in the production of reliable, geometrically accurate, high-resolution geospatial products. These systems have replaced film imaging in photogrammetric data capturing. Today, we see a proliferation of imaging sensors collecting photographs in different ground resolutions, spectral bands, swath sizes, radiometric characteristics, accuracies and carried on different mobile platforms. In addition, these imaging sensors are combined with navigational tools (such as GPS and IMU), active sensors such as laser scanning and powerful processing tools to obtain high quality geospatial products. The quality (accuracy, completeness, consistency, etc.) of these geospatial products is based on the use of calibrated, high-quality digital camera systems. The new survey regulations of the state of Israel specify the quality requirements for each geospatial product including: maps at different scales and for different purposes, elevation models, orthophotographs, three-dimensional models at different levels of details (LOD) and more. In addition, the regulations require that digital camera systems used for mapping purposes should be certified using a rigorous mapping systems certification and validation process which is specified in the Director General Instructions. The Director General Instructions for digital camera systems certification specify a two-step process as follows: 1. Theoretical analysis of system components that includes: study of the accuracy of each component and an integrative error propagation evaluation, examination of the radiometric and spectral response curves for the imaging sensors, the calibration requirements, and the working procedures. 2. Empirical study of the digital mapping system that examines a typical project (product scale, flight height, number and configuration of ground control points and process). The study examine all the aspects of the final product including; its accuracy, the product pixels size

  19. A digital computer program for the dynamic interaction simulation of controls and structure (DISCOS), volume 1

    NASA Technical Reports Server (NTRS)

    Bodley, C. S.; Devers, A. D.; Park, A. C.; Frisch, H. P.

    1978-01-01

    A theoretical development and associated digital computer program system for the dynamic simulation and stability analysis of passive and actively controlled spacecraft are presented. The dynamic system (spacecraft) is modeled as an assembly of rigid and/or flexible bodies not necessarily in a topological tree configuration. The computer program system is used to investigate total system dynamic characteristics, including interaction effects between rigid and/or flexible bodies, control systems, and a wide range of environmental loadings. In addition, the program system is used for designing attitude control systems and for evaluating total dynamic system performance, including time domain response and frequency domain stability analyses.

  20. C-130 Automated Digital Data System (CADDS)

    NASA Technical Reports Server (NTRS)

    Scofield, C. P.; Nguyen, Chien

    1991-01-01

    Real time airborne data acquisition, archiving and distribution on the NASA/Ames Research Center (ARC) C-130 has been improved over the past three years due to the implementation of the C-130 Automated Digital Data System (CADDS). CADDS is a real time, multitasking, multiprocessing ROM-based system. CADDS acquires data from both avionics and environmental sensors inflight for all C-130 data lines. The system also displays the data on video monitors throughout the aircraft.

  1. Adaptive Embedded Digital System for Plasma Diagnostics

    NASA Astrophysics Data System (ADS)

    González, Angel; Rodríguez, Othoniel; Mangual, Osvaldo; Ponce, Eduardo; Vélez, Xavier

    2014-05-01

    An Adaptive Embedded Digital System to perform plasma diagnostics using electrostatic probes was developed at the Plasma Engineering Laboratory at Polytechnic University of Puerto Rico. The system will replace the existing instrumentation at the Laboratory, using reconfigurable hardware to minimize the equipment and software needed to perform diagnostics. The adaptability of the design resides on the possibility of replacing the computational algorithm on the fly, allowing to use the same hardware for different probes. The system was prototyped using Very High Speed Integrated Circuits Hardware Description Language (VHDL) into an Field Programmable Gate Array (FPGA) board. The design of the Embedded Digital System includes a Zero Phase Digital Filter, a Derivative Unit, and a Computational Unit designed using the VHDL-2008 Support Library. The prototype is able to compute the Plasma Electron Temperature and Density from a Single Langmuir probe. The system was tested using real data previously acquired from a single Langmuir probe. The plasma parameters obtained from the embedded system were compared with results computed using matlab yielding excellent matching. The new embedded system operates on 4096 samples versus 500 on the previous system, and completes its computations in 26 milliseconds compared with about 15 seconds on the previous system.

  2. Digital radiographic systems detect boiler tube cracks

    SciTech Connect

    Walker, S.

    2008-06-15

    Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.

  3. Observing System Simulation Experiments

    NASA Technical Reports Server (NTRS)

    Prive, Nikki

    2015-01-01

    This presentation gives an overview of Observing System Simulation Experiments (OSSEs). The components of an OSSE are described, along with discussion of the process for validating, calibrating, and performing experiments. a.

  4. Operational characteristic analysis of conduction cooling HTS SMES for Real Time Digital Simulator based power quality enhancement simulation

    NASA Astrophysics Data System (ADS)

    Kim, A. R.; Kim, G. H.; Kim, K. M.; Kim, D. W.; Park, M.; Yu, I. K.; Kim, S. H.; Sim, K.; Sohn, M. H.; Seong, K. C.

    2010-11-01

    This paper analyzes the operational characteristics of conduction cooling Superconducting Magnetic Energy Storage (SMES) through a real hardware based simulation. To analyze the operational characteristics, the authors manufactured a small-scale toroidal-type SMES and implemented a Real Time Digital Simulator (RTDS) based power quality enhancement simulation. The method can consider not only electrical characteristics such as inductance and current but also temperature characteristic by using the real SMES system. In order to prove the effectiveness of the proposed method, a voltage sag compensation simulation has been implemented using the RTDS connected with the High Temperature Superconducting (HTS) model coil and DC/DC converter system, and the simulation results are discussed in detail.

  5. Simulation of synthetic aperture radar 3: Evaluation of prototype digital feature analysis data

    NASA Astrophysics Data System (ADS)

    Crane, Peter M.; Bell, Herbert H.

    1989-12-01

    This experiment evaluated the suitability of the Defense Mapping Agency (DMA) prototype Level 3c Digital Feature Analysis Data (DFAD) for the simulation of Synthetic Aperture Radar (SAR). The suitability of Prototype Level 3c DFAD was evaluated by comparing simulations generated from samples of Level 3c and from samples of DFAD previously demonstrated to be adequate for SAR simulation; these products, however, were unsuitable for production in the quantities required to meet Air Force needs. B-1B Offensive Systems Officers performed a navigation update task using simulated and actual SAR images. Crosshair placement accuracy, operator confidence in the placement, and ratings of acceptability for use in a Weapon System Trainer were recorded using both simulated and actual SAR images. The results indicated that SAR simulation can be supported as well by Level 3c DFAD as by the other products.

  6. Accelerating the Customer-Driven Microgrid Through Real-Time Digital Simulation

    SciTech Connect

    I. Leonard; T. Baldwin; M. Sloderbeck

    2009-07-01

    Comprehensive design and testing of realistic customer-driven microgrids requires a high performance simulation platform capable of incorporating power system and control models with external hardware systems. Traditional non real-time simulation is unable to fully capture the level of detail necessary to expose real-world implementation issues. With a real-time digital simulator as its foundation, a high-fidelity simulation environment that includes a robust electrical power system model, advanced control architecture, and a highly adaptable communication network is introduced. Hardware-in-the-loop implementation approaches for the hardware-based control and communication systems are included. An overview of the existing power system model and its suitability for investigation of autonomous island formation within the microgrid is additionally presented. Further test plans are also documented.

  7. A novel digital burst demodulator for TDMA satellite communication systems

    NASA Astrophysics Data System (ADS)

    Sakata, Tetsu; Morikura, Masahiro; Kato, Shuzo

    A baseband reverse modulation carrier revovery scheme with phase compensated carrier filters is proposed as a high performance digital burst demodulator for TDMA (Time Division Multiple Access) satellite communication systems. Computer simulations show that the phase acquisition time of the proposed scheme is 90% less than that of the conventional Costas loop scheme, assuming that they have the same carrier cycle slipping rate at an Eb/No of 2dB. Moreover, a novel carrier AFC (Automatic Frequency Control) circuit is proposed to realize simple and digitalized AFC. The proposed AFC circuit reduces the hardware size to 25% of that of a conventional cross product frequency discriminator, and computer simulations show good AFC performance to countermeasure common carrier frequency error.

  8. Characterizing Digital Camera Systems: A Prelude to Data Standards

    NASA Technical Reports Server (NTRS)

    Ryan, Robert

    2002-01-01

    This viewgraph presentation profiles: 1) Digital imaging systems; 2) Specifying a digital imagery product; and 3) Characterization of data acquisition systems. Advanced large array digital imaging systems are routinely being used. Digital imagery guidelines are being developed by ASPRS and ISPRS. Guidelines and standards are of little use without standardized characterization methods. Characterization of digital camera systems is important for supporting digital imagery guidelines. Specifications are characterized in the lab and/or the field. Laboratory characterization is critical for optimizing and defining performance. In-flight characterization is necessary for an end-to-end system test.

  9. A comparison of hardware description languages. [describing digital systems structure and behavior to a computer

    NASA Technical Reports Server (NTRS)

    Shiva, S. G.

    1978-01-01

    Several high level languages which evolved over the past few years for describing and simulating the structure and behavior of digital systems, on digital computers are assessed. The characteristics of the four prominent languages (CDL, DDL, AHPL, ISP) are summarized. A criterion for selecting a suitable hardware description language for use in an automatic integrated circuit design environment is provided.

  10. A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging

    PubMed Central

    Gallio, Elena; Rampado, Osvaldo; Gianaria, Elena; Bianchi, Silvio Diego; Ropolo, Roberto

    2015-01-01

    Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies. PMID:26545097

  11. A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging.

    PubMed

    Gallio, Elena; Rampado, Osvaldo; Gianaria, Elena; Bianchi, Silvio Diego; Ropolo, Roberto

    2015-01-01

    Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies. PMID:26545097

  12. A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging.

    PubMed

    Gallio, Elena; Rampado, Osvaldo; Gianaria, Elena; Bianchi, Silvio Diego; Ropolo, Roberto

    2015-01-01

    Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies.

  13. Intermittent/transient fault phenomena in digital systems

    NASA Technical Reports Server (NTRS)

    Masson, G. M.

    1977-01-01

    An overview of the intermittent/transient (IT) fault study is presented. An interval survivability evaluation of digital systems for IT faults is discussed along with a method for detecting and diagnosing IT faults in digital systems.

  14. Validation of simulation of calcifications for observer studies in digital mammography

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Green, F. H.; Shrestha, L.; Mackenzie, A.; Dance, D. R.; Young, K. C.

    2013-08-01

    Studies using simulated calcifications can be performed to measure the effect of different imaging factors on calcification detection in digital mammography. The simulated calcifications must be inserted into clinical images with realistic contrast and sharpness. MoCa is a program which modifies the contrast and sharpness of simulated calcification clusters extracted from images of mastectomy specimens acquired on a digital specimen cabinet at high magnification for insertion into clinical mammography images. This work determines whether the use of MoCa results in simulated calcifications with the correct contrast and sharpness. Aluminium foils (thickness 0.1-0.4 mm) and 1.60 µm thick gold discs (diameter 0.13-0.8 mm) on 0.5 mm aluminium were imaged with a range of thicknesses of polymethyl methacrylate (PMMA) using an amorphous selenium direct digital (DR) system and a powder phosphor computed radiography (CR) system (real images). Simulated images of the tests objects were also generated using MoCa. The contrast of the aluminium squares and the degradation of the contrast of the gold discs as a function of disc diameter were compared in the real and simulated images. The average ratios of the simulated-to-real aluminium contrasts over all aluminium and PMMA thicknesses were 1.03±0.04 (two standard errors in the mean) and 0.99±0.03 for the DR and CR systems, respectively. The ratio of the simulated-to-real degradations of contrast averaged over all disc diameters and PMMA thicknesses were 1.007±0.008 and 1.002±0.013 for DR and CR, respectively. The use of MoCa was accurate within the experimental errors.

  15. Project ITCH: Interactive Digital Simulation in Electrical Engineering Education.

    ERIC Educational Resources Information Center

    Bailey, F. N.; Kain, R. Y.

    A two-stage project is investigating the educational potential of a low-cost time-sharing system used as a simulation tool in Electrical Engineering (EE) education. Phase I involves a pilot study and Phase II a full integration. The system employs interactive computer simulation to teach engineering concepts which are not well handled by…

  16. Digital Data Acquisition System for Gammasphere

    NASA Astrophysics Data System (ADS)

    Hoffman, C. R.; Anderson, J. T.; Carpenter, M. P.; Hayden, T. A.; Janssens, R. V. F.; Kreps, A.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Wilt, P.; Zhu, S.; Cromaz, M.; Lionberger, C.; Lee, I. Y.

    2010-11-01

    A new digital-based data acquisition system for Gammasphere is under development. This system leverages the electronics designed for the GRETINA collaboration. At the center of this development are the GRETINA 10-channel digitizer modules which digitize the Ge preamp signals at a 100MHz rate [1]. The new DAQ will increase event throughput significantly over the existing system while addressing multiple repair and maintenance issues. New hardware and firmware to integrate the GRETINA electronics with Gammasphere has been developed allowing for a staged changeover so that the experimental program will not be adversely affected. A successful field test of a small number of channels running parasitically to the analog system has demonstrated the anticipated increase in event rate and shown that the energy resolution will still remain satisfactory at these higher rates. The current status of project will be presented. This research is supported by the DOE Office of Nuclear Physics under Contract No. DE-AC02-06CH11357. [1] J.T. Anderson et al., IEEE Transactions on Nuclear Science, vol. 56, issue 1, pp. 258-265.

  17. Numerical Propulsion System Simulation

    NASA Technical Reports Server (NTRS)

    Naiman, Cynthia

    2006-01-01

    The NASA Glenn Research Center, in partnership with the aerospace industry, other government agencies, and academia, is leading the effort to develop an advanced multidisciplinary analysis environment for aerospace propulsion systems called the Numerical Propulsion System Simulation (NPSS). NPSS is a framework for performing analysis of complex systems. The initial development of NPSS focused on the analysis and design of airbreathing aircraft engines, but the resulting NPSS framework may be applied to any system, for example: aerospace, rockets, hypersonics, power and propulsion, fuel cells, ground based power, and even human system modeling. NPSS provides increased flexibility for the user, which reduces the total development time and cost. It is currently being extended to support the NASA Aeronautics Research Mission Directorate Fundamental Aeronautics Program and the Advanced Virtual Engine Test Cell (AVETeC). NPSS focuses on the integration of multiple disciplines such as aerodynamics, structure, and heat transfer with numerical zooming on component codes. Zooming is the coupling of analyses at various levels of detail. NPSS development includes capabilities to facilitate collaborative engineering. The NPSS will provide improved tools to develop custom components and to use capability for zooming to higher fidelity codes, coupling to multidiscipline codes, transmitting secure data, and distributing simulations across different platforms. These powerful capabilities extend NPSS from a zero-dimensional simulation tool to a multi-fidelity, multidiscipline system-level simulation tool for the full development life cycle.

  18. Relationship between magnification and resolution in digital pathology systems.

    PubMed

    Sellaro, Tiffany L; Filkins, Robert; Hoffman, Chelsea; Fine, Jeffrey L; Ho, Jon; Parwani, Anil V; Pantanowitz, Liron; Montalto, Michael

    2013-08-22

    Many pathology laboratories are implementing digital pathology systems. The image resolution and scanning (digitization) magnification can vary greatly between these digital pathology systems. In addition, when digital images are compared with viewing images using a microscope, the cellular features can vary in size. This article highlights differences in magnification and resolution between the conventional microscopes and the digital pathology systems. As more pathologists adopt digital pathology, it is important that they understand these differences and how they ultimately translate into what the pathologist can see and how this may impact their overall viewing experience.

  19. A Landsat Digital Image Rectification System

    NASA Technical Reports Server (NTRS)

    Van Wie, P.; Stein, M.

    1976-01-01

    DIRS is a Digital Image Rectification System for the geometric correction of Landsat Multispectral Scanner digital image data. DIRS removes spatial distortions from the data and brings it into conformance with the Universal Transverse Mercator (UTM) map projection. Scene data in the form of landmarks or Ground Control Points (GCPs) are used to drive the geometric correction algorithms. The system offers extensive capabilities for 'shade printing' to aid in the determination of GCPs. Affine, two dimensional least squares polynominal and spacecraft attitude modeling techniques for geometric mapping are provided. Entire scenes or selected quadralaterals may be rectified. Resampling through nearest neighbor or cubic convolution at user designated intervals is available. The output products are in the form of digital tape in band interleaved, single band or CCT format in a rotated UTM projection. The system was designed and implemented on large scale IBM 360 computers with at least 300-500K bytes of memory for user application programs and five nine track tapes plus direct access storage.

  20. Lessons learned in digital upgrade projects digital control system implementation at US nuclear power stations

    SciTech Connect

    Kelley, S.; Bolian, T. W.

    2006-07-01

    AREVA NP has gained significant experience during the past five years in digital upgrades at operating nuclear power stations in the US. Plants are seeking modernization with digital technology to address obsolescence, spare parts availability, vendor support, increasing age-related failures and diminished reliability. New systems offer improved reliability and functionality, and decreased maintenance requirements. Significant lessons learned have been identified relating to the areas of licensing, equipment qualification, software quality assurance and other topics specific to digital controls. Digital control systems have been installed in non safety-related control applications at many utilities within the last 15 years. There have also been a few replacements of small safety-related systems with digital technology. Digital control systems are proving to be reliable, accurate, and easy to maintain. Digital technology is gaining acceptance and momentum with both utilities and regulatory agencies based upon the successes of these installations. Also, new plants are being designed with integrated digital control systems. To support plant life extension and address obsolescence of critical components, utilities are beginning to install digital technology for primary safety-system replacement. AREVA NP analyzed operating experience and lessons learned from its own digital upgrade projects as well as industry-wide experience to identify key issues that should be considered when implementing digital controls in nuclear power stations.

  1. Software simulator for multiple computer simulation system

    NASA Technical Reports Server (NTRS)

    Ogrady, E. P.

    1983-01-01

    A description is given of the structure and use of a computer program that simulates the operation of a parallel processor simulation system. The program is part of an investigation to determine algorithms that are suitable for simulating continous systems on a parallel processor configuration. The simulator is designed to accurately simulate the problem-solving phase of a simulation study. Care has been taken to ensure the integrity and correctness of data exchanges and to correctly sequence periods of computation and periods of data exchange. It is pointed out that the functions performed during a problem-setup phase or a reset phase are not simulated. In particular, there is no attempt to simulate the downloading process that loads object code into the local, transfer, and mapping memories of processing elements or the memories of the run control processor and the system control processor. The main program of the simulator carries out some problem-setup functions of the system control processor in that it requests the user to enter values for simulation system parameters and problem parameters. The method by which these values are transferred to the other processors, however, is not simulated.

  2. Flight test of a full authority Digital Electronic Engine Control system in an F-15 aircraft

    NASA Technical Reports Server (NTRS)

    Barrett, W. J.; Rembold, J. P.; Burcham, F. W.; Myers, L.

    1981-01-01

    The Digital Electronic Engine Control (DEEC) system considered is a relatively low cost digital full authority control system containing selectively redundant components and fault detection logic with capability for accommodating faults to various levels of operational capability. The DEEC digital control system is built around a 16-bit, 1.2 microsecond cycle time, CMOS microprocessor, microcomputer system with approximately 14 K of available memory. Attention is given to the control mode, component bench testing, closed loop bench testing, a failure mode and effects analysis, sea-level engine testing, simulated altitude engine testing, flight testing, the data system, cockpit, and real time display.

  3. Data Systems Dynamic Simulator

    NASA Technical Reports Server (NTRS)

    Rouff, Christopher; Clark, Melana; Davenport, Bill; Message, Philip

    1993-01-01

    The Data System Dynamic Simulator (DSDS) is a discrete event simulation tool. It was developed for NASA for the specific purpose of evaluating candidate architectures for data systems of the Space Station era. DSDS provides three methods for meeting this requirement. First, the user has access to a library of standard pre-programmed elements. These elements represent tailorable components of NASA data systems and can be connected in any logical manner. Secondly, DSDS supports the development of additional elements. This allows the more sophisticated DSDS user the option of extending the standard element set. Thirdly, DSDS supports the use of data streams simulation. Data streams is the name given to a technique that ignores packet boundaries, but is sensitive to rate changes. Because rate changes are rare compared to packet arrivals in a typical NASA data system, data stream simulations require a fraction of the CPU run time. Additionally, the data stream technique is considerably more accurate than another commonly-used optimization technique.

  4. Basic problems of digital simulation of solid rocket motor (SRM) structural reliability

    NASA Astrophysics Data System (ADS)

    Tan, Sanwu; Wang, Binxun

    1993-08-01

    Discussed are several basic problems in the digital simulation of SRM structural reliability, such as verification testing for critical components. Simulations of fiber-reinforced composite cases and SRM solid grains are presented to illustrate the general program of digital simulation for SRM structural reliability.

  5. Digital control system for space structural dampers

    NASA Technical Reports Server (NTRS)

    Haviland, J. K.

    1984-01-01

    A recently developed concept for a damper was improved by adding a small taper to the proof-mass, and using a proximeter to determine position. Also, an experimental damper was built using a three-inch stroke in place of the standard one-inch stroke. The analog controller initially used was replaced by an independent digital controller slaved to a TRS-80 Model I computer, which also serves as a highly effective, low-cost development system. An overall system concept for the use of proof-mass dampers is presented.

  6. Advanced Digital Avionics System for general aviation

    NASA Technical Reports Server (NTRS)

    Smyth, R. K.; Hoh, R. H.; Teper, G. L.

    1977-01-01

    Objectives and functions of the Advanced Digital Avionics System (ADAS) for general aviation are outlined with particular reference to navigation, flight control, engine management, ATC surveillance, flight management, communications, and the pilot controls and displays. The resulting ADAS design comprises the selection of off-the-shelf avionics to be integrated with ADAS-unique elements including new pilot displays and controls along with a microcomputer control complex (MCC). Reasons for which the ADAS achieves increased avionics capability are mentioned, including overall system integration through the MCC and pilot orientation from navigation map display.

  7. Advanced optical manufacturing digital integrated system

    NASA Astrophysics Data System (ADS)

    Tao, Yizheng; Li, Xinglan; Li, Wei; Tang, Dingyong

    2012-10-01

    It is necessarily to adapt development of advanced optical manufacturing technology with modern science technology development. To solved these problems which low of ration, ratio of finished product, repetition, consistent in big size and high precision in advanced optical component manufacturing. Applied business driven and method of Rational Unified Process, this paper has researched advanced optical manufacturing process flow, requirement of Advanced Optical Manufacturing integrated System, and put forward architecture and key technology of it. Designed Optical component core and Manufacturing process driven of Advanced Optical Manufacturing Digital Integrated System. the result displayed effective well, realized dynamic planning Manufacturing process, information integration improved ratio of production manufactory.

  8. A digital video model deformation system

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Snow, W. L.; Goad, W. K.; Childers, B. A.

    1987-01-01

    The use of solid-state array cameras and a PC-controlled image acquisition system to measure model deformation in a wind tunnel is discussed. This digital system improves an earlier video model deformation system that used high-resolution tube cameras and required the manual measurement of targets on video hardcopy images. The new system eliminates both the vibration-induced distortion associated with tube cameras and the manual readup of video images necessary in the earlier version. Camera calibration and data reduction procedures necessary to convert pixel image plane data from two cameras into wing deflections are presented. Laboratory tests to establish the uncertainty of the system with the geometry to be used are described.

  9. A digital sensor simulator of the pushbroom Offner hyperspectral imaging spectrometer.

    PubMed

    Tao, Dongxing; Jia, Guorui; Yuan, Yan; Zhao, Huijie

    2014-12-11

    Sensor simulators can be used in forecasting the imaging quality of a new hyperspectral imaging spectrometer, and generating simulated data for the development and validation of the data processing algorithms. This paper presents a novel digital sensor simulator for the pushbroom Offner hyperspectral imaging spectrometer, which is widely used in the hyperspectral remote sensing. Based on the imaging process, the sensor simulator consists of a spatial response module, a spectral response module, and a radiometric response module. In order to enhance the simulation accuracy, spatial interpolation-resampling, which is implemented before the spatial degradation, is developed to compromise the direction error and the extra aliasing effect. Instead of using the spectral response function (SRF), the dispersive imaging characteristics of the Offner convex grating optical system is accurately modeled by its configuration parameters. The non-uniformity characteristics, such as keystone and smile effects, are simulated in the corresponding modules. In this work, the spatial, spectral and radiometric calibration processes are simulated to provide the parameters of modulation transfer function (MTF), SRF and radiometric calibration parameters of the sensor simulator. Some uncertainty factors (the stability, band width of the monochromator for the spectral calibration, and the integrating sphere uncertainty for the radiometric calibration) are considered in the simulation of the calibration process. With the calibration parameters, several experiments were designed to validate the spatial, spectral and radiometric response of the sensor simulator, respectively. The experiment results indicate that the sensor simulator is valid.

  10. A Digital Sensor Simulator of the Pushbroom Offner Hyperspectral Imaging Spectrometer

    PubMed Central

    Tao, Dongxing; Jia, Guorui; Yuan, Yan; Zhao, Huijie

    2014-01-01

    Sensor simulators can be used in forecasting the imaging quality of a new hyperspectral imaging spectrometer, and generating simulated data for the development and validation of the data processing algorithms. This paper presents a novel digital sensor simulator for the pushbroom Offner hyperspectral imaging spectrometer, which is widely used in the hyperspectral remote sensing. Based on the imaging process, the sensor simulator consists of a spatial response module, a spectral response module, and a radiometric response module. In order to enhance the simulation accuracy, spatial interpolation-resampling, which is implemented before the spatial degradation, is developed to compromise the direction error and the extra aliasing effect. Instead of using the spectral response function (SRF), the dispersive imaging characteristics of the Offner convex grating optical system is accurately modeled by its configuration parameters. The non-uniformity characteristics, such as keystone and smile effects, are simulated in the corresponding modules. In this work, the spatial, spectral and radiometric calibration processes are simulated to provide the parameters of modulation transfer function (MTF), SRF and radiometric calibration parameters of the sensor simulator. Some uncertainty factors (the stability, band width of the monochromator for the spectral calibration, and the integrating sphere uncertainty for the radiometric calibration) are considered in the simulation of the calibration process. With the calibration parameters, several experiments were designed to validate the spatial, spectral and radiometric response of the sensor simulator, respectively. The experiment results indicate that the sensor simulator is valid. PMID:25615727

  11. Digital pilot aided carrier frequency offset estimation for coherent optical transmission systems.

    PubMed

    Zhao, Donghe; Xi, Lixia; Tang, Xianfeng; Zhang, Wenbo; Qiao, Yaojun; Zhang, Xiaoguang

    2015-09-21

    We present a digital pilot aided carrier frequency offset estimation (FOE) method for coherent optical transmission systems. Unlike the conventional pilot tone insertion scheme, the pilot of the proposed method is generated in a digital manner and can serve as a good FOE indicator. Aided by this kind of digital pilot, the FOE is implemented by determining the location of the digital pilot in the spectrum. Theoretical analysis and numerical simulations show that the proposed method has the advantages in wide range, high accuracy, modulation formats independent, no need to remove the modulation, and high tolerance to the residual chromatic dispersion (CD) and polarization mode dispersion (PMD).

  12. Digital controller design: Continuous and discrete describing function analysis of the IPS system

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The digital IPS with wire cable and flex pivot nonlinearity is simulated on the digital computer to determine the effects of varying the sampling period T on the system stability, and to determine a range of optimal values of the parameters of the digital controller. The listing of the computer program is shown as well as the Dahl model for the flex pivot nonlinearity. For the wire cable nonlinearity, two ranges of values were used and the nominal values of the digital controller parameters are included.

  13. Phase transfer function of digital imaging systems

    NASA Astrophysics Data System (ADS)

    Bhakta, Vikrant R.

    For the past several decades, optical engineering has relied heavily on Fourier analysis of linear systems as a valuable aid in realizing numerous imaging applications. Today, spatial frequency analysis via the optical transfer function (OTF) remains an integral tool for the design, characterization and testing of incoherent imaging systems. The magnitude of the complex OTF is known as the modulation transfer function (MTF) and its phase is given by the phase transfer function (PTF). The MTF represents the contrast reduction at each spatial frequency; whereas, the PTF represents the spatial shift of these frequencies. While the MTF has been used extensively to characterize imaging systems, the PTF has long been ignored because it was thought to have an insignificant presence and to be difficult to understand and measure. Through theoretical analysis and experimental demonstrations, this work addresses all of these issues and shows that the PTF is a valuable tool for modern-day digital imaging systems. The effects of optical aberrations on the PTF of an imaging system in the absence of aliasing have been analyzed in detail. However, for the digital imaging systems, the effect of aliasing on the overall system behavior becomes an important consideration. To this end, the effects of aliasing on the PTF of the sampled imaging system are described and its key properties are derived. The role of PTF as an essential metric in today's imaging systems necessitates practical PTF measurement techniques. Two, easy-to-implement, image-based methods for PTF measurement are described and experimentally validated. These measurement methods and the insights gained from the theoretical analysis are leveraged for several applications spanning diverse fields such as optical system characterization, computational imaging, and image processing.

  14. Rotorcraft Digital Advanced Avionics System (rodaas)

    NASA Technical Reports Server (NTRS)

    Taira, B.

    1985-01-01

    A simulator is being built to determine the practicality of using an advanced avionics system in a helicopter. Features include an autopilot; a navigation and flight planning component; an advisory system built into the computer; conventional gages and displays; a clock function; a fuel totalizer; a weight and balance computator; a performance evaluator; and emergency and normal checklists. The translation of a computer program written in PASCAL into a form that can be read by the graphics package for the simulator and basic electronic work in simulator construction are discussed.

  15. Preparation, applications, and digital simulation of carbon interdigitated array electrodes.

    PubMed

    Liu, Fei; Kolesov, Grigory; Parkinson, B A

    2014-08-01

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltammetry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10(-5) molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. PMID:24998907

  16. Preparation, Applications, and Digital Simulation of Carbon Interdigitated Array Electrodes

    SciTech Connect

    Liu, Fei; Kolesov, Grigory; Parkinson, Bruce A.

    2014-12-16

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltam-metry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10–5 molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science Office of Basic Energy Sciences.

  17. Discrete-time pilot model. [human dynamics and digital simulation

    NASA Technical Reports Server (NTRS)

    Cavalli, D.

    1978-01-01

    Pilot behavior is considered as a discrete-time process where the decision making has a sequential nature. This model differs from both the quasilinear model which follows from classical control theory and from the optimal control model which considers the human operator as a Kalman estimator-predictor. An additional factor considered is that the pilot's objective may not be adequately formulated as a quadratic cost functional to be minimized, but rather as a more fuzzy measure of the closeness with which the aircraft follows a reference trajectory. All model parameters, in the digital program simulating the pilot's behavior, were successfully compared in terms of standard-deviation and performance with those of professional pilots in IFR configuration. The first practical application of the model was in the study of its performance degradation when the aircraft model static margin decreases.

  18. Analog/Digital System for Germanium Thermometer

    NASA Technical Reports Server (NTRS)

    Woodhouse, Christopher

    1988-01-01

    Electronic system containing analog and digital circuits makes high-precision, four-wire measurements of resistance of each germanium resistance thermometer (GRT) in array of devices, using alternating current (ac) of 1 micro-A. At end measurement interval, contents of negative register subtracted from positive one, resulting in very-narrow-band synchronous demodulation of carrier wave and suppression of out-of-band noise. Microprocessor free to perform other duties after measurement complete. Useful in noisy terrestrial environments encountered in factories.

  19. A simple method for simulating gasdynamic systems

    NASA Technical Reports Server (NTRS)

    Hartley, Tom T.

    1991-01-01

    A simple method for performing digital simulation of gasdynamic systems is presented. The approach is somewhat intuitive, and requires some knowledge of the physics of the problem as well as an understanding of the finite difference theory. The method is explicitly shown in appendix A which is taken from the book by P.J. Roache, 'Computational Fluid Dynamics,' Hermosa Publishers, 1982. The resulting method is relatively fast while it sacrifices some accuracy.

  20. CEBAF NEW DIGITAL LLRF SYSTEM EXTENDED FUNCTIONALITY

    SciTech Connect

    T. Allison; K. Davis; H. Dong; C. Hovater; L. King; J. Musson; T. Plawski

    2007-06-18

    The new digital LLRF system for the CEBAF 12GeV accelerator will perform a variety of tasks, beyond field control [1]. In this paper we present the superconducting cavity resonance control system designed to minimize RF power during gradient ramp and to minimize RF power during steady state operation. Based on the calculated detuning angle, which represents the difference between reference and cavity resonance frequency, the cavity length will be adjusted with a mechanical tuner. The tuner has two mechanical driving devices, a stepper motor and a piezo-tuner, to yield a combination of coarse and fine control. Although LLRF piezo processing speed can achieve 10 kHz bandwidth, only 10 Hz speed is needed for 12 GeV upgrade. There will be a number of additional functions within the LLRF system; heater controls to maintain cryomodule's heat load balance, ceramic window temperature monitoring, waveguide vacuum interlocks, ARC detector interlock and quench detection. The additional functions will be divided between the digital board, incorporating an Altera FPGA and an embedded EPICS IOC. This paper will also address hardware evolution and test results performed with different SC cavities.

  1. Monitoring Digital Closed-Loop Feedback Systems

    NASA Technical Reports Server (NTRS)

    Katz, Richard; Kleyner, Igor

    2011-01-01

    A technique of monitoring digital closed-loop feedback systems has been conceived. The basic idea is to obtain information on the performances of closed-loop feedback circuits in such systems to aid in the determination of the functionality and integrity of the circuits and of performance margins. The need for this technique arises as follows: Some modern digital systems include feedback circuits that enable other circuits to perform with precision and are tolerant of changes in environment and the device s parameters. For example, in a precision timing circuit, it is desirable to make the circuit insensitive to variability as a result of the manufacture of circuit components and to the effects of temperature, voltage, radiation, and aging. However, such a design can also result in masking the indications of damaged and/or deteriorating components. The present technique incorporates test circuitry and associated engineering-telemetry circuitry into an embedded system to monitor the closed-loop feedback circuits, using spare gates that are often available in field programmable gate arrays (FPGAs). This technique enables a test engineer to determine the amount of performance margin in the system, detect out of family circuit performance, and determine one or more trend(s) in the performance of the system. In one system to which the technique has been applied, an ultra-stable oscillator is used as a reference for internal adjustment of 12 time-to-digital converters (TDCs). The feedback circuit produces a pulse-width-modulated signal that is fed as a control input into an amplifier, which controls the circuit s operating voltage. If the circuit s gates are determined to be operating too slowly or rapidly when their timing is compared with that of the reference signal, then the pulse width increases or decreases, respectively, thereby commanding the amplifier to increase or reduce, respectively, its output level, and "adjust" the speed of the circuits. The nominal

  2. A digital bandlimited chaos-based communication system

    NASA Astrophysics Data System (ADS)

    Fontes, Rodrigo T.; Eisencraft, Marcio

    2016-08-01

    In recent years, many communication systems that use a function to encode an information in a chaotic signal were proposed. Since every transmission channel is bandlimited in nature, it is required to determine and to control the chaotic signal spectrum. This way, a bandlimited chaos-based communication system (CBCS) was proposed using digital filters and chaotic synchronization. As the filters modify the original chaotic system, it is necessary to study how their insertion affects chaotic synchronization. In this work, we present a digital discrete-time bandlimited CBCS system analysis, considering practical settings encountered in conventional communication systems. The proposed system is based on master-slave chaotic synchronization and the required conditions for its synchronization is obtained analytically for a general K-dimensional chaos generator map. The performance of this system is evaluated in terms of bit error rate. As a way to improve the signal to noise ratio, we also propose to filter the out-of-band noise in the receiver. Numerical simulations show the advantages of using such a scheme.

  3. Distributed and recoverable digital control system

    NASA Technical Reports Server (NTRS)

    Stange, Kent (Inventor); Hess, Richard (Inventor); Kelley, Gerald B (Inventor); Rogers, Randy (Inventor)

    2010-01-01

    A real-time multi-tasking digital control system with rapid recovery capability is disclosed. The control system includes a plurality of computing units comprising a plurality of redundant processing units, with each of the processing units configured to generate one or more redundant control commands. One or more internal monitors are employed for detecting data errors in the control commands. One or more recovery triggers are provided for initiating rapid recovery of a processing unit if data errors are detected. The control system also includes a plurality of actuator control units each in operative communication with the computing units. The actuator control units are configured to initiate a rapid recovery if data errors are detected in one or more of the processing units. A plurality of smart actuators communicates with the actuator control units, and a plurality of redundant sensors communicates with the computing units.

  4. Random digital encryption secure communication system

    NASA Technical Reports Server (NTRS)

    Doland, G. D. (Inventor)

    1982-01-01

    The design of a secure communication system is described. A product code, formed from two pseudorandom sequences of digital bits, is used to encipher or scramble data prior to transmission. The two pseudorandom sequences are periodically changed at intervals before they have had time to repeat. One of the two sequences is transmitted continuously with the scrambled data for synchronization. In the receiver portion of the system, the incoming signal is compared with one of two locally generated pseudorandom sequences until correspondence between the sequences is obtained. At this time, the two locally generated sequences are formed into a product code which deciphers the data from the incoming signal. Provision is made to ensure synchronization of the transmitting and receiving portions of the system.

  5. Digital control algorithms for microgravity isolation systems

    NASA Technical Reports Server (NTRS)

    Sinha, Alok; Wang, Yung-Peng

    1992-01-01

    New digital control algorithms were developed to achieve the desired acceleration transmissibility function. The attractive electromagnets have been taken as actuators. The relative displacement and the acceleration of the mass were used as feedback signals. Two approaches were developed to find that controller transfer function in Z-domain, which yields the desired transmissibility at each frequency. In the first approach, the controller transfer function is obtained by assuming that the desired transmissibility is known in Z-domain. Since the desired transmissibility H sub d(S) = 1/(tauS+1)(exp 2) is given in S-domain, the first task is to obtain the desired transmissibility in Z-domain. There are three methods to perform this task: bilinear transformation, and backward and forward rectangular rules. The bilinear transformation and backward rectangular rule lead to improper controller transfer functions, which are physically not realizable. The forward rectangular rule does lead to a physically realizable controller. However, this controller is found to be marginally stable because of a pole at Z=1. In order to eliminate this pole, a hybrid control structure is proposed. Here the control input is composed of two parts: analog and digital. The analog input simply represents the velocity (or the integral of acceleration) feedback; and the digital controller which uses only relative displacement signal, is then obtained to achieve the desired closed-loop transfer function. The stability analysis indicates that the controller transfer function is stable for typical values of sampling period. In the second approach, the aforementioned hybrid control structure is again used. First, an analog controller transfer function corresponding to relative displacement feedback is obtained to achieve the transmissibility as 1/(tauS+1)(exp 2). Then the transfer function for the digital control input is obtained by discretizing this analog controller transfer function via bilinear

  6. An all digital low data rate communication system

    NASA Technical Reports Server (NTRS)

    Chen, C.; Fan, M.

    1973-01-01

    The advent of digital hardwares has made it feasible to implement many communication system components digitally. With the exception of frequency down conversion, the proposed low data rate communication system uses digital hardwares completely. Although the system is designed primarily for deep space communications with large frequency uncertainty and low signal-to-noise ratio, it is also suitable for other low data rate applications with time-shared operation among a number of channels. Emphasis is placed on the fast Fourier transform receiver and the automatic frequency control via digital filtering. The speed available from the digital system allows sophisticated signal processing to reduce frequency uncertainty and to increase the signal-to-noise ratio. The practical limitations of the system such as the finite register length are examined. It is concluded that the proposed all-digital system is not only technically feasible but also has potential cost reduction over the existing receiving systems.

  7. The CADSS design automation system. [computerized design language for small digital systems

    NASA Technical Reports Server (NTRS)

    Franke, E. A.

    1973-01-01

    This research was designed to implement and extend a previously defined design automation system for the design of small digital structures. A description is included of the higher level language developed to describe systems as a sequence of register transfer operations. The system simulator which is used to determine if the original description is correct is also discussed. The design automation system produces tables describing the state transistions of the system and the operation of all registers. In addition all Boolean equations specifying system operation are minimized and converted to NAND gate structures. Suggestions for further extensions to the system are also given.

  8. Digital Video Over Space Systems and Networks

    NASA Technical Reports Server (NTRS)

    Grubbs, Rodney

    2010-01-01

    This slide presentation reviews the improvements and challenges that digital video provides over analog video. The use of digital video over IP options and trade offs, link integrity and latency are reviewed.

  9. The needs of digital games content rating system in Malaysia

    NASA Astrophysics Data System (ADS)

    Hamid, Ros Syammimi; Shiratuddin, Norshuhada

    2016-08-01

    Numerous studies revealed that playing digital games with adverse contents can lead to negative effects. Therefore, this article presents a review of the harmful contents and the detrimental effects of playing digital games. Violent and sexual contents of digital games, digital games scenarios in Malaysia, and review of existing content rating system are covered. The review indicates that Malaysia should have its own digital games content ratings system to control the contents and inform the users about the contents of the games that they wish to consume.

  10. A real-time digital computer program for the simulation of automatic spacecraft reentries

    NASA Technical Reports Server (NTRS)

    Kaylor, J. T.; Powell, L. F.; Powell, R. W.

    1977-01-01

    The automatic reentry flight dynamics simulator, a nonlinear, six-degree-of-freedom simulation, digital computer program, has been developed. The program includes a rotating, oblate earth model for accurate navigation calculations and contains adjustable gains on the aerodynamic stability and control parameters. This program uses a real-time simulation system and is designed to examine entries of vehicles which have constant mass properties whose attitudes are controlled by both aerodynamic surfaces and reaction control thrusters, and which have automatic guidance and control systems. The program has been used to study the space shuttle orbiter entry. This report includes descriptions of the equations of motion used, the control and guidance schemes that were implemented, the program flow and operation, and the hardware involved.

  11. Digital Badge Systems: The Promise and Potential

    ERIC Educational Resources Information Center

    Thigpen, Kamila

    2014-01-01

    Digital badges--defined as digital credentials that convey an array of skills, interests, and achievements--are steadily growing in acceptance as a way to validate learning that takes place not only in school but also at home and in a number of other out-of-school settings. This report builds on the growing body of literature about digital badge…

  12. Fourier transform digital holographic adaptive optics imaging system

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    A Fourier transform digital holographic adaptive optics imaging system and its basic principles are proposed. The CCD is put at the exact Fourier transform plane of the pupil of the eye lens. The spherical curvature introduced by the optics except the eye lens itself is eliminated. The CCD is also at image plane of the target. The point-spread function of the system is directly recorded, making it easier to determine the correct guide-star hologram. Also, the light signal will be stronger at the CCD, especially for phase-aberration sensing. Numerical propagation is avoided. The sensor aperture has nothing to do with the resolution and the possibility of using low coherence or incoherent illumination is opened. The system becomes more efficient and flexible. Although it is intended for ophthalmic use, it also shows potential application in microscopy. The robustness and feasibility of this compact system are demonstrated by simulations and experiments using scattering objects. PMID:23262541

  13. A robotic system for digital photography

    NASA Astrophysics Data System (ADS)

    MacDonald, Lindsay W.

    2006-02-01

    The European collaborative research project IST-2000-28008-VITRA ('Veridical Imaging of Transmissive and Reflective Artefacts') developed an innovative system for high-resolution digital image acquisition for conservation and heritage applications. Using a robotic platform to carry both camera and lighting, it can capture colorimetric images up to 15 metres above floor level, thus eliminating the need for scaffold towers. Potential applications include wall-paintings, tapestries, friezes and stained glass windows in historic buildings such as churches, cathedrals, palaces and monuments. Evaluation of the system was conducted at four sites in Germany and the UK. In the course of the project a number of significant technical innovations were made, including a new panoramic image viewer for the Internet.

  14. Class 1E digital systems studies

    SciTech Connect

    Hecht, H.; Tai, A.T.; Tso, K.S.

    1993-10-01

    This document is furnished as part of the effort to develop NRC Class 1E Digital Computer Systems Guidelines which is Task 8 of USAF Rome Laboratories Contract F30602-89-D-0100. The report addresses four major topics, namely, computer programming languages, software design and development, software testing and fault tolerance and fault avoidance. The topics are intended as stepping stones leading to a Draft Regulatory Guide document. As part of this task a small scale survey of software fault avoidance and fault tolerance practices was conducted among vendors of nuclear safety related systems and among agencies that develop software for other applications demanding very high reliability. The findings of the present report are in part based on the survey and in part on review of software literature relating to nuclear and other critical installations, as well as on the authors` experience in these areas.

  15. A digital simulation of message traffic for natural disaster warning communications satellite

    NASA Technical Reports Server (NTRS)

    Hein, G. F.; Stevenson, S. M.

    1972-01-01

    Various types of weather communications are required to alert industries and the general public about the impending occurrence of tornados, hurricanes, snowstorms, floods, etc. A natural disaster warning satellite system has been proposed for meeting the communications requirements of the National Oceanic and Atmospheric Administration. Message traffic for a communications satellite was simulated with a digital computer in order to determine the number of communications channels to meet system requirements. Poisson inputs are used for arrivals and an exponential distribution is used for service.

  16. Geohydrology and digital simulation of the ground-water flow system in the Umatilla Plateau and Horse Heaven Hills area, Oregon and Washington

    USGS Publications Warehouse

    Davies-Smith, A.; Bolke, E.L.; Collins, C.A.

    1988-01-01

    The Columbia Plateau is underlain by massive basalt flows, with a composite thickness of about 10,000 ft. Structural features within the study area include a series of anticline-syncline pairs. The main avenues of groundwater movement in the basalt are the interflow zone between basalt flows. Individual interflow zones may be rather extensive in the lateral direction and are largely isolated from overlying and underlying interflows by poorly permeable basalt flow centers. Four aquifers were defined for this study. The uppermost aquifer (layer 1) consists of unconsolidated deposits of gravel, sand, silt, and clay that overlie the basalt: layer 2 consists of the Saddle Mountains Basalt, layer 3 the Wanapum Basalt, and layer 4 consists of the upper thousand ft of Grande Ronde Basalt. Recharge to the groundwater system is from precipitation, leakage from streams, and seepage from surface water irrigation. Natural discharge of aquifers is principally to streams. Discharge by groundwater pumpage from the study area ranged from approximately 2,000 acre-ft in 1950 to 144,000 acre-ft in 1980. About 85% of the total pumpage in 1980 was from the Oregon part of the study area. Water level declines of over 300 ft occur locally in parts of the study area. (USGS)

  17. Quantitative evaluation of digital dental radiograph imaging systems.

    PubMed

    Hildebolt, C F; Vannier, M W; Pilgram, T K; Shrout, M K

    1990-11-01

    Two digital imaging systems, a video camera and analog-to-digital converter, and a charge-coupled device linear photodiode array slide scanner, were tested for their suitability in quantitative studies of periodontal disease. The information content in the original films was estimated, and digital systems were assessed according to these requirements. Radiometric and geometric performance criteria for the digital systems were estimated from measurements and observations. The scanner-based image acquisition (digitization) system had no detectable noise and had a modulation transfer function curve superior to that of the video-based system. The scanner-based system was equivalent to the video-based system in recording radiographic film densities and had more geometric distortion than the video-based system. The comparison demonstrated the superiority of the charge-coupled device linear array system for the quantification of periodontal disease extent and activity. PMID:2234888

  18. Interference into digital radio systems from communications satellites. I - Theory and model description

    NASA Astrophysics Data System (ADS)

    Cheilik, P.

    The effect of satellite interference on terrestrial digital radio systems was examined by means of a computer simulation model which determines co-channel interference from geostationary communication satellites. The equivalent bit error rate is determined as a function of Eb/No ratio, where Eb is the energy per bit, and the No term is noise per bit, which incorporates interference. Simulation runs were made, with the digital radio signals subject to fade, to determine the performance of the 64 QAM system operating in the 4 GHz band, and the 16 QAM, 64 QAM, 8 PSK, and 49 QPRS systems in the 11 band.

  19. Simulation Exercises for an Undergraduate Digital Process Control Course.

    ERIC Educational Resources Information Center

    Reeves, Deborah E.; Schork, F. Joseph

    1988-01-01

    Presents six problems from an alternative approach to homework traditionally given to follow-up lectures. Stresses the advantage of longer term exercises which allow for creativity and independence on the part of the student. Problems include: "System Model,""Open-Loop Simulation,""PID Control,""Dahlin Algorithm,""Analytical Predictor," and…

  20. Analysis of satellite broadcasting systems for digital television

    NASA Astrophysics Data System (ADS)

    de Gaudenzi, Riccardo; Elia, Carlo; Viola, Roberto

    1993-01-01

    This paper introduces the new concept of digital direct satellite broadcasting (D-DBS), which allows unprecedented flexibility by providing a large number of audio-visual services. The concept elaborated on in this paper assumes an information rate of about 40 Mb/s, which is compatible with practically all present-day transponders. After discussion of the general system concept, the optimization procedure is introduced and results of the transmission system optimization are presented. Channel distortion and uplink/downlink interference effects are taken into account by means of a time domain system computer simulation approach. It is shown, by means of link budget analysis, how a medium power direct-to-home TV satellite can provide multimedia services to users equipped with small (60 cm) dish antennas.

  1. Transportation Anslysis Simulation System

    SciTech Connect

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at the level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not account

  2. Transportation Anslysis Simulation System

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at themore » level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not

  3. Digital control of wind tunnel magnetic suspension and balance systems

    NASA Technical Reports Server (NTRS)

    Britcher, Colin P.; Goodyer, Michael J.; Eskins, Jonathan; Parker, David; Halford, Robert J.

    1987-01-01

    Digital controllers are being developed for wind tunnel magnetic suspension and balance systems, which in turn permit wind tunnel testing of aircraft models free from support interference. Hardware and software features of two existing digital control systems are reviewed. Some aspects of model position sensing and system calibration are also discussed.

  4. Development Of A Digital Flight-Control System

    NASA Technical Reports Server (NTRS)

    Smith, G. Allan; Meyer, George

    1988-01-01

    Feed-forward control path includes inversion of model of the aircraft. Report describes concept, development, tests of digital flight-control system for vertical-attitude-takeoff-and-landing aircraft. System based in airborne digital computer. Combines control of attitude and thrust in unified system for operation over full coupled ranges of velocity, altitude, attitude, and acceleration.

  5. Simulation of an on-board hierarchical multistage digital FDM demultiplexer for mobile SCPC satellite communications

    NASA Astrophysics Data System (ADS)

    Eyssele, Helmut; Goeckler, Heinz

    1990-04-01

    Focus is placed on the finite-precision time-domain simulation of the hierarchical multistage method for the demultiplexing of an FDM signal composed of L = 32 slot signals. This approach is based on the processing of complex signals by linear-phase FIR filters, where at any stage of processing the respective signals are always oversampled by a factor of two. The FDM demultiplexer is part of a multicarrier demodulator to be used in the return link (from the mobile vehicle to the earth station) of a future satellite digital communication system. The simulation results fully confirm previously predicted system performance by modelling the distortions (spectral foldover and quantization noise) inherent in the system.

  6. Digital position determination system for electron microscopy.

    PubMed

    Hohmann-Marriott, Martin F; Sharp, William P; Roberson, Robert W; Blankenship, Robert E

    2005-06-01

    The precise determination of object positions within a specimen grid is important for many applications in electron microscopy. For example, real-time position determination is necessary for current statistical approaches and the efficient mapping and relocation of objects. Unfortunately, precise real-time position determination is not available on many older electron microscopes with manual stage controls. This report demonstrates the cost-effective and flexible implementation of a digital position determination system that can be adapted to many hand-operated electron microscopes. A customized solution that includes the hardware and software to accomplish position determination is presented. Lists of required parts, instructions for building the hardware, and descriptions of the developed programs are included. Two LED-photodiode assemblies detect x and y movements via an optical wheel that is in physical contact with the mechanical x and y stage control elements. These detector assemblies are interfaced with an integrated circuit that converts movement information into serial port-compatible signals, which are interpreted by a computer with specialized software. Two electron microscopes, a Philips CM12 (S)TEM and a Philips 201 TEM, were equipped with the described digital position determination system. The position fidelity and position fidelity after reloading of grids were determined for both microscopes. The determined position deviation was 1.06 microm in the x axis and 0.565 microm in the y axis for the Philips CM12 (S)TEM, and 0.303 microm in the x axis and 0.545 microm in the y axis for the Philips 201 TEM. After reloading and computational realigning, the determined average position variation was 2.66 microm in the x axis and 2.61 microm in the y axis for the Philips CM12 (S)TEM, and 1.13 microm in the x axis and 1.27 microm in the y axis for the Philips 201 TEM.

  7. Digital-Analog Quantum Simulation of Spin Models in Trapped Ions

    NASA Astrophysics Data System (ADS)

    Arrazola, Iñigo; Pedernales, Julen S.; Lamata, Lucas; Solano, Enrique

    2016-07-01

    We propose a method to simulate spin models in trapped ions using a digital-analog approach, consisting in a suitable gate decomposition in terms of analog blocks and digital steps. In this way, we show that the quantum dynamics of an enhanced variety of spin models could be implemented with substantially less number of gates than a fully digital approach. Typically, analog blocks are built of multipartite dynamics providing the complexity of the simulated model, while the digital steps are local operations bringing versatility to it. Finally, we describe a possible experimental implementation in trapped-ion technologies.

  8. Digital-Analog Quantum Simulation of Spin Models in Trapped Ions

    PubMed Central

    Arrazola, Iñigo; Pedernales, Julen S.; Lamata, Lucas; Solano, Enrique

    2016-01-01

    We propose a method to simulate spin models in trapped ions using a digital-analog approach, consisting in a suitable gate decomposition in terms of analog blocks and digital steps. In this way, we show that the quantum dynamics of an enhanced variety of spin models could be implemented with substantially less number of gates than a fully digital approach. Typically, analog blocks are built of multipartite dynamics providing the complexity of the simulated model, while the digital steps are local operations bringing versatility to it. Finally, we describe a possible experimental implementation in trapped-ion technologies. PMID:27470970

  9. Simulating neural systems with Xyce.

    SciTech Connect

    Schiek, Richard Louis; Thornquist, Heidi K.; Mei, Ting; Warrender, Christina E.; Aimone, James Bradley; Teeter, Corinne; Duda, Alex M.

    2012-12-01

    Sandias parallel circuit simulator, Xyce, can address large scale neuron simulations in a new way extending the range within which one can perform high-fidelity, multi-compartment neuron simulations. This report documents the implementation of neuron devices in Xyce, their use in simulation and analysis of neuron systems.

  10. Digital processing system for developing countries

    NASA Technical Reports Server (NTRS)

    Nanayakkara, C.; Wagner, H.

    1977-01-01

    An effort was undertaken to perform simple digital processing tasks using pre-existing general purpose digital computers. An experimental software package, LIGMALS, was obtained and modified for this purpose. The resulting software permits basic processing tasks to be performed including level slicing, gray mapping and ratio processing. The experience gained in this project indicates a possible direction which may be used by other developing countries to obtain digital processing capabilities.

  11. Digital redesign of uncertain interval systems based on time-response resemblance via particle swarm optimization.

    PubMed

    Hsu, Chen-Chien; Lin, Geng-Yu

    2009-07-01

    In this paper, a particle swarm optimization (PSO) based approach is proposed to derive an optimal digital controller for redesigned digital systems having an interval plant based on time-response resemblance of the closed-loop systems. Because of difficulties in obtaining time-response envelopes for interval systems, the design problem is formulated as an optimization problem of a cost function in terms of aggregated deviation between the step responses corresponding to extremal energies of the redesigned digital system and those of their continuous counterpart. A proposed evolutionary framework incorporating three PSOs is subsequently presented to minimize the cost function to derive an optimal set of parameters for the digital controller, so that step response sequences corresponding to the extremal sequence energy of the redesigned digital system suitably approximate those of their continuous counterpart under the perturbation of the uncertain plant parameters. Computer simulations have shown that redesigned digital systems incorporating the PSO-derived digital controllers have better system performance than those using conventional open-loop discretization methods.

  12. Generation of linear dynamic models from a digital nonlinear simulation

    NASA Technical Reports Server (NTRS)

    Daniele, C. J.; Krosel, S. M.

    1979-01-01

    The results and methodology used to derive linear models from a nonlinear simulation are presented. It is shown that averaged positive and negative perturbations in the state variables can reduce numerical errors in finite difference, partial derivative approximations and, in the control inputs, can better approximate the system response in both directions about the operating point. Both explicit and implicit formulations are addressed. Linear models are derived for the F 100 engine, and comparisons of transients are made with the nonlinear simulation. The problem of startup transients in the nonlinear simulation in making these comparisons is addressed. Also, reduction of the linear models is investigated using the modal and normal techniques. Reduced-order models of the F 100 are derived and compared with the full-state models.

  13. Digital Control Analysis and Design of a Field-Sensed Magnetic Suspension System

    PubMed Central

    Li, Jen-Hsing; Chiou, Juing-Shian

    2015-01-01

    Magnetic suspension systems are mechatronic systems and crucial in several engineering applications, such as the levitation of high-speed trains, frictionless bearings, and wind tunnels. Magnetic suspension systems are nonlinear and unstable systems; therefore, they are suitable educational benchmarks for testing various modeling and control methods. This paper presents the digital modeling and control of magnetic suspension systems. First, the magnetic suspension system is stabilized using a digital proportional-derivative controller. Subsequently, the digital model is identified using recursive algorithms. Finally, a digital mixed linear quadratic regulator (LQR)/H∞ control is adopted to stabilize the magnetic suspension system robustly. Simulation examples and a real-world example are provided to demonstrate the practicality of the study results. In this study, a digital magnetic suspension system model was developed and reviewed. In addition, equivalent state and output feedback controls for magnetic suspension systems were developed. Using this method, the controller design for magnetic suspension systems was simplified, which is the novel contribution of this study. In addition, this paper proposes a complete digital controller design procedure for magnetic suspension systems. PMID:25781508

  14. Digital control analysis and design of a field-sensed magnetic suspension system.

    PubMed

    Li, Jen-Hsing; Chiou, Juing-Shian

    2015-03-13

    Magnetic suspension systems are mechatronic systems and crucial in several engineering applications, such as the levitation of high-speed trains, frictionless bearings, and wind tunnels. Magnetic suspension systems are nonlinear and unstable systems; therefore, they are suitable educational benchmarks for testing various modeling and control methods. This paper presents the digital modeling and control of magnetic suspension systems. First, the magnetic suspension system is stabilized using a digital proportional-derivative controller. Subsequently, the digital model is identified using recursive algorithms. Finally, a digital mixed linear quadratic regulator (LQR)/H∞ control is adopted to stabilize the magnetic suspension system robustly. Simulation examples and a real-world example are provided to demonstrate the practicality of the study results. In this study, a digital magnetic suspension system model was developed and reviewed. In addition, equivalent state and output feedback controls for magnetic suspension systems were developed. Using this method, the controller design for magnetic suspension systems was simplified, which is the novel contribution of this study. In addition, this paper proposes a complete digital controller design procedure for magnetic suspension systems.

  15. Digital control analysis and design of a field-sensed magnetic suspension system.

    PubMed

    Li, Jen-Hsing; Chiou, Juing-Shian

    2015-01-01

    Magnetic suspension systems are mechatronic systems and crucial in several engineering applications, such as the levitation of high-speed trains, frictionless bearings, and wind tunnels. Magnetic suspension systems are nonlinear and unstable systems; therefore, they are suitable educational benchmarks for testing various modeling and control methods. This paper presents the digital modeling and control of magnetic suspension systems. First, the magnetic suspension system is stabilized using a digital proportional-derivative controller. Subsequently, the digital model is identified using recursive algorithms. Finally, a digital mixed linear quadratic regulator (LQR)/H∞ control is adopted to stabilize the magnetic suspension system robustly. Simulation examples and a real-world example are provided to demonstrate the practicality of the study results. In this study, a digital magnetic suspension system model was developed and reviewed. In addition, equivalent state and output feedback controls for magnetic suspension systems were developed. Using this method, the controller design for magnetic suspension systems was simplified, which is the novel contribution of this study. In addition, this paper proposes a complete digital controller design procedure for magnetic suspension systems. PMID:25781508

  16. Formal methods and digital systems validation for airborne systems

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1993-01-01

    This report has been prepared to supplement a forthcoming chapter on formal methods in the FAA Digital Systems Validation Handbook. Its purpose is as follows: to outline the technical basis for formal methods in computer science; to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used on board aircraft; and to suggest factors for consideration when formal methods are offered in support of certification. These latter factors assume the context for software development and assurance described in RTCA document DO-178B, 'Software Considerations in Airborne Systems and Equipment Certification,' Dec. 1992.

  17. The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis

    SciTech Connect

    Shaheen, Eman; Van Ongeval, Chantal; Zanca, Federica; Cockmartin, Lesley; Marshall, Nicholas; Jacobs, Jurgen; Young, Kenneth C.; Dance, David R.; Bosmans, Hilde

    2011-12-15

    Purpose: This work proposes a new method of building 3D models of microcalcification clusters and describes the validation of their realistic appearance when simulated into 2D digital mammograms and into breast tomosynthesis images. Methods: A micro-CT unit was used to scan 23 breast biopsy specimens of microcalcification clusters with malignant and benign characteristics and their 3D reconstructed datasets were segmented to obtain 3D models of microcalcification clusters. These models were then adjusted for the x-ray spectrum used and for the system resolution and simulated into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. Six radiologists were asked to distinguish between 40 real and 40 simulated clusters of microcalcifications in two separate studies on 2D mammography and tomosynthesis datasets. Receiver operating characteristic (ROC) analysis was used to test the ability of each observer to distinguish between simulated and real microcalcification clusters. The kappa statistic was applied to assess how often the individual simulated and real microcalcification clusters had received similar scores (''agreement'') on their realistic appearance in both modalities. This analysis was performed for all readers and for the real and the simulated group of microcalcification clusters separately. ''Poor'' agreement would reflect radiologists' confusion between simulated and real clusters, i.e., lesions not systematically evaluated in both modalities as either simulated or real, and would therefore be interpreted as a success of the present models. Results: The area under the ROC curve, averaged over the observers, was 0.55 (95% confidence interval [0.44, 0.66]) for the 2D study, and 0.46 (95% confidence interval [0.29, 0.64]) for the tomosynthesis study, indicating no statistically significant difference between real and simulated

  18. Direct digital simulation of power semiconductor-controlled electrical machines

    NASA Astrophysics Data System (ADS)

    Bahnassy, H. M.

    1981-06-01

    Generalized computer programming techniques for simulating power semiconductor-controlled electric machines in coil-variable representation are presented. These techniques are developed primarily for implementation in large scale general purpose computer-aided design and analysis (CADA) circuit programs. To demonstrate the validity of the developed techniques, a coil-variable model of a brushless synchronous generator with an ac exciter and rotating rectifiers was constructed. The performance of the control system (thyristor voltage regulator) is represented by a transfer function block diagram model. The CADA circuit program used is the recently developed SUPER SCEPTRE program. The model is validated using the design data and test results of a 60 kVA brushless generator. Numerous computer simulation cases are presented including the steady state and transient conditions. Brushless generator performance under diode failure faults (opened-diode, shorted-diode) is simulated. The effects of the external faults, at the main generator terminals, on the main generator, as well as its excitation system currents, are simulated.

  19. Aviation spectral camera infinity target simulation system

    NASA Astrophysics Data System (ADS)

    Liu, Xinyue; Ming, Xing; Liu, Jiu; Guo, Wenji; Lv, Gunbo

    2014-11-01

    With the development of science and technology, the applications of aviation spectral camera becoming more widely. Developing a test system of dynamic target is more important. Aviation spectral camera infinity target simulation system can be used to test the resolution and the modulation transfer function of camera. The construction and work principle of infinity target simulation system were introduced in detail. Dynamic target generator based digital micromirror device (DMD) and required performance of collimation System were analyzed and reported. The dynamic target generator based on DMD had the advantages of replacing image convenient, size small and flexible. According to the requirement of tested camera, by rotating and moving mirror, has completed a full field infinity dynamic target test plan.

  20. Research and development of a digital design system for hull structures

    NASA Astrophysics Data System (ADS)

    Zhan, Yi-Ting; Ji, Zhuo-Shang; Liu, Yin-Dong

    2007-06-01

    Methods used for digital ship design were studied and formed the basis of a proposed frame model suitable for ship construction modeling. Based on 3-D modeling software, a digital design system for hull structures was developed. Basic software systems for modeling, modifying, and assembly simulation were developed. The system has good compatibility, and models created by it can be saved in different 3-D file formats, and 2D engineering drawings can be output directly. The model can be modified dynamically, overcoming the necessity of repeated modifications during hull structural design. Through operations such as model construction, intervention inspection, and collision detection, problems can be identified and modified during the hull structural design stage. Technologies for centralized control of the system, database management, and 3-D digital design are integrated into this digital model in the preliminary design stage of shipbuilding.

  1. Digital computer simulation of inductor-energy-storage dc-to-dc converters with closed-loop regulators

    NASA Technical Reports Server (NTRS)

    Ohri, A. K.; Owen, H. A.; Wilson, T. G.; Rodriguez, G. E.

    1974-01-01

    The simulation of converter-controller combinations by means of a flexible digital computer program which produces output to a graphic display is discussed. The procedure is an alternative to mathematical analysis of converter systems. The types of computer programming involved in the simulation are described. Schematic diagrams, state equations, and output equations are displayed for four basic forms of inductor-energy-storage dc to dc converters. Mathematical models are developed to show the relationship of the parameters.

  2. Development of a digital solar simulator based on full-bridge converter

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Feng, Jian; Liu, Zhilong; Tong, Weichao; Ji, Yibo

    2014-02-01

    With the development of solar photovoltaic, distribution schemes utilized in power grid had been commonly application, and photovoltaic (PV) inverter is an essential equipment in grid. In this paper, a digital solar simulator based on full-bridge structure is presented. The output characteristic curve of system is electrically similar to silicon solar cells, which can greatly simplify research methods of PV inverter, improve the efficiency of research and development. The proposed simulator consists on a main control board based on TM320F28335, phase-shifted zero-voltage-switching (ZVS) DC-DC full-bridge converter and voltage and current sampling circuit, that allows emulating the voltage-current curve with the open-circuit voltage (Voc) of 900V and the short-circuit current (Isc) of 18A .When the system connected to a PV inverter, the inverter can quickly track from the open-circuit to the maximum power point and keep stability.

  3. Digital Collaboration inside and outside Educational Systems

    ERIC Educational Resources Information Center

    Birkeland, Nils Rune; Drange, Eli-Marie Danbolt; Tønnessen, Elise Seip

    2015-01-01

    This article takes its outset in findings from an ongoing research project investigating the use of digital and multimodal resources in teacher education (TE) in Norway. The material studied is mandatory assignments in different courses in TE, asking how teacher students collaborate through digital media in their production of texts for learning,…

  4. A Reduced Power Digital Electronics System for a Digital Beamforming Space Exploration Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Carter, L. M.; Rincon, R. F.; Novak, M.

    2016-10-01

    We will discuss design of an orbital P-band (70 cm wavelength) digital beamforming radar system that is modular and can be used for imaging polarimetry of Earth and rocky planets and moons, as well as asteroids and comets.

  5. Dual function seal: visualized digital signature for electronic medical record systems.

    PubMed

    Yu, Yao-Chang; Hou, Ting-Wei; Chiang, Tzu-Chiang

    2012-10-01

    Digital signature is an important cryptography technology to be used to provide integrity and non-repudiation in electronic medical record systems (EMRS) and it is required by law. However, digital signatures normally appear in forms unrecognizable to medical staff, this may reduce the trust from medical staff that is used to the handwritten signatures or seals. Therefore, in this paper we propose a dual function seal to extend user trust from a traditional seal to a digital signature. The proposed dual function seal is a prototype that combines the traditional seal and digital seal. With this prototype, medical personnel are not just can put a seal on paper but also generate a visualized digital signature for electronic medical records. Medical Personnel can then look at the visualized digital signature and directly know which medical personnel generated it, just like with a traditional seal. Discrete wavelet transform (DWT) is used as an image processing method to generate a visualized digital signature, and the peak signal to noise ratio (PSNR) is calculated to verify that distortions of all converted images are beyond human recognition, and the results of our converted images are from 70 dB to 80 dB. The signature recoverability is also tested in this proposed paper to ensure that the visualized digital signature is verifiable. A simulated EMRS is implemented to show how the visualized digital signature can be integrity into EMRS.

  6. Simulation of Controller Pilot Data Link Communications over VHF Digital Link Mode 3

    NASA Technical Reports Server (NTRS)

    Bretmersky, Steven C.; Murawski, Robert; Nguyen, Thanh C.; Raghavan, Rajesh S.

    2004-01-01

    The Federal Aviation Administration (FAA) has established an operational plan for the future Air Traffic Management (ATM) system, in which the Controller Pilot Data Link Communications (CPDLC) is envisioned to evolve into digital messaging that will take on an ever increasing role in controller to pilot communications, significantly changing the way the National Airspace System (NAS) is operating. According to FAA, CPDLC represents the first phase of the transition from the current analog voice system to an International Civil Aviation Organization (ICAO) compliant system in which digital communication becomes the alternate and perhaps primary method of routine communication. The CPDLC application is an Air Traffic Service (ATS) application in which pilots and controllers exchange messages via an addressed data link. CPDLC includes a set of clearance, information, and request message elements that correspond to existing phraseology employed by current Air Traffic Control (ATC) procedures. These message elements encompass altitude assignments, crossing constraints, lateral deviations, route changes and clearances, speed assignments, radio frequency assignments, and various requests for information. The pilot is provided with the capability to respond to messages, to request clearances and information, to report information, and to declare/rescind an emergency. A 'free text' capability is also provided to exchange information not conforming to defined formats. This paper presents simulated results of the aeronautical telecommunication application Controller Pilot Data Link Communications over VHF Digital Link Mode 3 (VDL Mode 3). The objective of this simulation study was to determine the impact of CPDLC traffic loads, in terms of timely message delivery and capacity of the VDL Mode 3 subnetwork. The traffic model is based on and is used for generating air/ground messages with different priorities. Communication is modeled for the en route domain of the Cleveland

  7. Development and validation of novel digitalized cervicography system

    PubMed Central

    Kim, Soo-Nyung; Kim, Yun Hwan; Nam, Kye-Hyun; Lee, Seon-Kyung; Lee, Tae Sung; Choi, Ho-Sun; Han, Sei-Jun

    2016-01-01

    Objective Digital cervicography systems would be expected to reduce the costs of film cervicography, and provide the opportunity for "telemedicine-based" screening. We aimed to develop web-based digital cervicography system, and validate it compared with conventional film cervicography. Methods A hundred cases from five centers were prospectively included, and cervical images (analogue, digitalized by scanning analogue, and digital) were taken separately using both analogue (Cerviscope) and digital camera (Dr. Cervicam) in each patient. Nine specialists evaluated the three kinds of images of each case with time interval between evaluations of each image. To validate novel digitalized system, we analyzed intra-observer variance among evaluation results of three kinds of images. Results Sixty-three cases were finally analyzed after excluding technically defective cases that cannot be evaluable on analogue images. The generalized kappa for analogue versus digital image was 0.83, for analogue versus scanned image 0.72, and for digital versus scanned image was 0.71; all were in excellent consensus. Conclusion Digitalized cervicography system can be substituted for the film cervicography very reliably, and can be used as a promising telemedicine tool for cervical cancer screening. PMID:27200314

  8. Advanced digital image archival system using MPEG technologies

    NASA Astrophysics Data System (ADS)

    Chang, Wo

    2009-08-01

    Digital information and records are vital to the human race regardless of the nationalities and eras in which they were produced. Digital image contents are produced at a rapid pace from cultural heritages via digitalization, scientific and experimental data via high speed imaging sensors, national defense satellite images from governments, medical and healthcare imaging records from hospitals, personal collection of photos from digital cameras. With these mass amounts of precious and irreplaceable data and knowledge, what standards technologies can be applied to preserve and yet provide an interoperable framework for accessing the data across varieties of systems and devices? This paper presents an advanced digital image archival system by applying the international standard of MPEG technologies to preserve digital image content.

  9. Digital pathology and anatomic pathology laboratory information system integration to support digital pathology sign-out

    PubMed Central

    Guo, Huazhang; Birsa, Joe; Farahani, Navid; Hartman, Douglas J.; Piccoli, Anthony; O’Leary, Matthew; McHugh, Jeffrey; Nyman, Mark; Stratman, Curtis; Kvarnstrom, Vanja; Yousem, Samuel; Pantanowitz, Liron

    2016-01-01

    Background: The adoption of digital pathology offers benefits over labor-intensive, time-consuming, and error-prone manual processes. However, because most workflow and laboratory transactions are centered around the anatomical pathology laboratory information system (APLIS), adoption of digital pathology ideally requires integration with the APLIS. A digital pathology system (DPS) integrated with the APLIS was recently implemented at our institution for diagnostic use. We demonstrate how such integration supports digital workflow to sign-out anatomical pathology cases. Methods: Workflow begins when pathology cases get accessioned into the APLIS (CoPathPlus). Glass slides from these cases are then digitized (Omnyx VL120 scanner) and automatically uploaded into the DPS (Omnyx® Integrated Digital Pathology (IDP) software v.1.3). The APLIS transmits case data to the DPS via a publishing web service. The DPS associates scanned images with the correct case using barcode labels on slides and information received from the APLIS. When pathologists remotely open a case in the DPS, additional information (e.g. gross pathology details, prior cases) gets retrieved from the APLIS through a query web service. Results: Following validation of this integration, pathologists at our institution have signed out more than 1000 surgical pathology cases in a production environment. Integration between the APLIS and DPS enabled pathologists to review digital slides while simultaneously having access to pertinent case metadata. The introduction of a digital workflow eliminated costly manual tasks involving matching of glass slides and avoided delays waiting for glass slides to be delivered. Conclusion: Integrating the DPS and APLIS were instrumental for successfully implementing a digital solution at our institution for pathology sign-out. The integration streamlined our digital sign-out workflow, diminished the potential for human error related to matching slides, and improved the sign

  10. A Feedback Intervention to Increase Digital and Paper Checklist Performance in Technically Advanced Aircraft Simulation

    ERIC Educational Resources Information Center

    Rantz, William G.; Van Houten, Ron

    2011-01-01

    This study examined whether pilots operating a flight simulator completed digital or paper flight checklists more accurately after receiving postflight graphic and verbal feedback. The dependent variable was the number of checklist items completed correctly per flight. Following treatment, checklist completion with paper and digital checklists…

  11. A Collusion-Resistant Fingerprinting System for Restricted Distribution of Digital Documents

    PubMed Central

    Munoz-Hernandez, Mario Diego; Garcia-Hernandez, Jose Juan; Morales-Sandoval, Miguel

    2013-01-01

    Digital fingerprinting is a technique that consists of inserting the ID of an authorized user in the digital content that he requests. This technique has been mainly used to trace back pirate copies of multimedia content such as images, audio, and video. This study proposes the use of state-of-the-art digital fingerprinting techniques in the context of restricted distribution of digital documents. In particular, the system proposed by Kuribayashi for multimedia content is investigated. Extensive simulations show the robustness of the proposed system against average collusion attack. Perceptual transparency of the fingerprinted documents is also studied. Moreover, by using an efficient Fast Fourier Transform core and standard computer machines it is shown that the proposed system is suitable for real-world scenarios. PMID:24349165

  12. A collusion-resistant fingerprinting system for restricted distribution of digital documents.

    PubMed

    Munoz-Hernandez, Mario Diego; Garcia-Hernandez, Jose Juan; Morales-Sandoval, Miguel

    2013-01-01

    Digital fingerprinting is a technique that consists of inserting the ID of an authorized user in the digital content that he requests. This technique has been mainly used to trace back pirate copies of multimedia content such as images, audio, and video. This study proposes the use of state-of-the-art digital fingerprinting techniques in the context of restricted distribution of digital documents. In particular, the system proposed by Kuribayashi for multimedia content is investigated. Extensive simulations show the robustness of the proposed system against average collusion attack. Perceptual transparency of the fingerprinted documents is also studied. Moreover, by using an efficient Fast Fourier Transform core and standard computer machines it is shown that the proposed system is suitable for real-world scenarios. PMID:24349165

  13. An all digital low data rate communication system

    NASA Technical Reports Server (NTRS)

    Chen, C.-H.; Fan, M.

    1973-01-01

    The advent of digital hardwares has made it feasible to implement many communication system components digitally. With the exception of frequency down conversion, the proposed low data rate communication system uses digital hardware completely. Although the system is designed primarily for deep space communications with large frequency uncertainty and low signal-to-noise ratio, it is also suitable for other low data rate applications with time-shared operation among a number of channels. Emphasis is placed on the fast Fourier transform receiver and the automatic frequency control via digital filtering. The speed available from the digital system allows sophisticated signal processing to reduce frequency uncertainty and to increase the signal-to-noise ratio.

  14. Phrase-programmable digital speech system

    SciTech Connect

    Raymond, W.J.; Morgan, R.L.; Miller, R.L.

    1987-01-27

    This patent describes a phrase speaking computer system having a programmable digital computer and a speech processor, the speech processor comprising: a voice synthesizer; a read/write speech data segment memory; a read/write command memory; control processor means including processor control programs and logic connecting to the memories and to the voice synthesizer. It is arranged to scan the command memory and to respond to command data entries stored therein by transferring corresponding speech data segments from the speech data segment memory to the voice synthesizer; data conveyance means, connecting the computer to the command memory and the speech data segment memory, for transferring the command data entries supplied by the computer into the command memory and for transferring the speech data segments supplied by the computer into the speech data segment memory; and an enable signal line connecting the computer to the speech processor and arranged to initiate the operation of the processor control programs and logic when the enable signal line is enabled by the computer; the programmable computer including speech control programs controlling the operation of the computer including data conveyance command sequences that cause the computer to supply command data entries to the data conveyance means and speech processor enabling command sequences that cause computer to energize the enable signal line.

  15. Electronic polarization-division demultiplexing based on digital signal processing in intensity-modulation direct-detection optical communication systems.

    PubMed

    Kikuchi, Kazuro

    2014-01-27

    We propose a novel configuration of optical receivers for intensity-modulation direct-detection (IM · DD) systems, which can cope with dual-polarization (DP) optical signals electrically. Using a Stokes analyzer and a newly-developed digital signal-processing (DSP) algorithm, we can achieve polarization tracking and demultiplexing in the digital domain after direct detection. Simulation results show that the power penalty stemming from digital polarization manipulations is negligibly small.

  16. Feed-forward digital phase and amplitude correction system

    DOEpatents

    Yu, David U. L.; Conway, Patrick H.

    1994-01-01

    Phase and amplitude modifications in repeatable RF pulses at the output of a high power pulsed microwave amplifier are made utilizing a digital feed-forward correction system. A controlled amount of the output power is coupled to a correction system for processing of phase and amplitude information. The correction system comprises circuitry to compare the detected phase and amplitude with the desired phase and amplitude, respectively, and a digitally programmable phase shifter and attenuator and digital logic circuitry to control the phase shifter and attenuator. The Phase and amplitude of subsequent are modified by output signals from the correction system.

  17. Feed-forward digital phase and amplitude correction system

    DOEpatents

    Yu, D.U.L.; Conway, P.H.

    1994-11-15

    Phase and amplitude modifications in repeatable RF pulses at the output of a high power pulsed microwave amplifier are made utilizing a digital feed-forward correction system. A controlled amount of the output power is coupled to a correction system for processing of phase and amplitude information. The correction system comprises circuitry to compare the detected phase and amplitude with the desired phase and amplitude, respectively, and a digitally programmable phase shifter and attenuator and digital logic circuitry to control the phase shifter and attenuator. The phase and amplitude of subsequent are modified by output signals from the correction system. 11 figs.

  18. RAPID: A random access picture digitizer, display, and memory system

    NASA Technical Reports Server (NTRS)

    Yakimovsky, Y.; Rayfield, M.; Eskenazi, R.

    1976-01-01

    RAPID is a system capable of providing convenient digital analysis of video data in real-time. It has two modes of operation. The first allows for continuous digitization of an EIA RS-170 video signal. Each frame in the video signal is digitized and written in 1/30 of a second into RAPID's internal memory. The second mode leaves the content of the internal memory independent of the current input video. In both modes of operation the image contained in the memory is used to generate an EIA RS-170 composite video output signal representing the digitized image in the memory so that it can be displayed on a monitor.

  19. Monte Carlo simulation of x-ray scatter based on patient model from digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Liu, Bob; Wu, Tao; Moore, Richard H.; Kopans, Daniel B.

    2006-03-01

    We are developing a breast specific scatter correction method for digital beast tomosynthesis (DBT). The 3D breast volume was initially reconstructed from 15 projection images acquired from a GE prototype tomosynthesis system without correction of scatter. The voxel values were mapped to the tissue compositions using various segmentation schemes. This voxelized digital breast model was entered into a Monte Carlo package simulating the prototype tomosynthesis system. One billion photons were generated from the x-ray source for each projection in the simulation and images of scattered photons were obtained. A primary only projection image was then produced by subtracting the scatter image from the corresponding original projection image which contains contributions from the both primary photons and scatter photons. The scatter free projection images were then used to reconstruct the 3D breast using the same algorithm. Compared with the uncorrected 3D image, the x-ray attenuation coefficients represented by the scatter-corrected 3D image are closer to those derived from the measurement data.

  20. A Digital Full-Text Biotechnology System at Georgetown University.

    ERIC Educational Resources Information Center

    Broering, Naomi C.

    1994-01-01

    Discusses Georgetown University's prototype digital full-text system designed to provide medical clinicians and researchers with electronically transmitted journal articles that include illustrations. Topics addressed include project design; digital full-text database design and maintenance; storage/retrieval and transmission technologies…

  1. Knowledge Organisation Systems in North American Digital Library Collections

    ERIC Educational Resources Information Center

    Shiri, Ali; Chase-Kruszewski, Sarah

    2009-01-01

    Purpose: The purpose of this paper is to report an investigation into the types of knowledge organisation systems (KOSs) utilised in North American digital library collections. Design/methodology/approach: The paper identifies, analyses and deep scans online North American hosted digital libraries. It reviews the literature related to the…

  2. SIMULATING LOCAL DENSE AREAS USING PMMA TO ASSESS AUTOMATIC EXPOSURE CONTROL IN DIGITAL MAMMOGRAPHY.

    PubMed

    Bouwman, R W; Binst, J; Dance, D R; Young, K C; Broeders, M J M; den Heeten, G J; Veldkamp, W J H; Bosmans, H; van Engen, R E

    2016-06-01

    Current digital mammography (DM) X-ray systems are equipped with advanced automatic exposure control (AEC) systems, which determine the exposure factors depending on breast composition. In the supplement of the European guidelines for quality assurance in breast cancer screening and diagnosis, a phantom-based test is included to evaluate the AEC response to local dense areas in terms of signal-to-noise ratio (SNR). This study evaluates the proposed test in terms of SNR and dose for four DM systems. The glandular fraction represented by the local dense area was assessed by analytic calculations. It was found that the proposed test simulates adipose to fully glandular breast compositions in attenuation. The doses associated with the phantoms were found to match well with the patient dose distribution. In conclusion, after some small adaptations, the test is valuable for the assessment of the AEC performance in terms of both SNR and dose. PMID:26977073

  3. Digital quantum simulation of many-body non-Markovian dynamics

    NASA Astrophysics Data System (ADS)

    Sweke, R.; Sanz, M.; Sinayskiy, I.; Petruccione, F.; Solano, E.

    2016-08-01

    We present an algorithmic method for the digital quantum simulation of many-body locally indivisible non-Markovian open quantum systems. It consists of two parts: first, a Suzuki-Lie-Trotter decomposition of the global system propagator into the product of subsystem propagators, which may not be quantum channels, and second, an algorithmic procedure for the implementation of the subsystem propagators through unitary operations and measurements on a dilated space. By providing rigorous error bounds for the relevant Suzuki-Lie-Trotter decomposition, we are able to analyze the efficiency of the method, and connect it with an appropriate measure of the local indivisibility of the system. In light of our analysis, the proposed method is expected to be experimentally achievable for a variety of interesting cases.

  4. A Model-Based Expert System For Digital Systems Design

    NASA Astrophysics Data System (ADS)

    Wu, J. G.; Ho, W. P. C.; Hu, Y. H.; Yun, D. Y. Y.; Parng, T. M.

    1987-05-01

    In this paper, we present a model-based expert system for automatic digital systems design. The goal of digital systems design is to generate a workable and efficient design from high level specifications. The formalization of the design process is a necessity for building an efficient automatic CAD system. Our approach combines model-based, heuristic best-first search, and meta-planning techniques from AI to facilitate the design process. The design process is decomposed into three subprocesses. First, the high-level behavioral specifications are translated into sequences of primitive behavioral operations. Next, primitive operations are grouped to form intermediate-level behavioral functions. Finally, structural function modules are selected to implement these functions. Using model-based reasoning on the primitive behavioral operations level extends the solution space considered in design and provides more opportunity for minimization. Heuristic best-first search and meta-planning tech-niques control the decision-making in the latter two subprocesses to optimize the final design. They also facilitate system maintenance by separating design strategy from design knowledge.

  5. Invited article: Digital beam-forming imaging riometer systems.

    PubMed

    Honary, Farideh; Marple, Steve R; Barratt, Keith; Chapman, Peter; Grill, Martin; Nielsen, Erling

    2011-03-01

    The design and operation of a new generation of digital imaging riometer systems developed by Lancaster University are presented. In the heart of the digital imaging riometer is a field-programmable gate array (FPGA), which is used for the digital signal processing and digital beam forming, completely replacing the analog Butler matrices which have been used in previous designs. The reconfigurable nature of the FPGA has been exploited to produce tools for remote system testing and diagnosis which have proven extremely useful for operation in remote locations such as the Arctic and Antarctic. Different FPGA programs enable different instrument configurations, including a 4 × 4 antenna filled array (producing 4 × 4 beams), an 8 × 8 antenna filled array (producing 7 × 7 beams), and a Mills cross system utilizing 63 antennas producing 556 usable beams. The concept of using a Mills cross antenna array for riometry has been successfully demonstrated for the first time. The digital beam forming has been validated by comparing the received signal power from cosmic radio sources with results predicted from the theoretical beam radiation pattern. The performances of four digital imaging riometer systems are compared against each other and a traditional imaging riometer utilizing analog Butler matrices. The comparison shows that digital imaging riometer systems, with independent receivers for each antenna, can obtain much better measurement precision for filled arrays or much higher spatial resolution for the Mills cross configuration when compared to existing imaging riometer systems.

  6. Invited Article: Digital beam-forming imaging riometer systems

    NASA Astrophysics Data System (ADS)

    Honary, Farideh; Marple, Steve R.; Barratt, Keith; Chapman, Peter; Grill, Martin; Nielsen, Erling

    2011-03-01

    The design and operation of a new generation of digital imaging riometer systems developed by Lancaster University are presented. In the heart of the digital imaging riometer is a field-programmable gate array (FPGA), which is used for the digital signal processing and digital beam forming, completely replacing the analog Butler matrices which have been used in previous designs. The reconfigurable nature of the FPGA has been exploited to produce tools for remote system testing and diagnosis which have proven extremely useful for operation in remote locations such as the Arctic and Antarctic. Different FPGA programs enable different instrument configurations, including a 4 × 4 antenna filled array (producing 4 × 4 beams), an 8 × 8 antenna filled array (producing 7 × 7 beams), and a Mills cross system utilizing 63 antennas producing 556 usable beams. The concept of using a Mills cross antenna array for riometry has been successfully demonstrated for the first time. The digital beam forming has been validated by comparing the received signal power from cosmic radio sources with results predicted from the theoretical beam radiation pattern. The performances of four digital imaging riometer systems are compared against each other and a traditional imaging riometer utilizing analog Butler matrices. The comparison shows that digital imaging riometer systems, with independent receivers for each antenna, can obtain much better measurement precision for filled arrays or much higher spatial resolution for the Mills cross configuration when compared to existing imaging riometer systems.

  7. Unattended digital video surveillance: A system prototype for EURATOM safeguards

    SciTech Connect

    Chare, P.; Goerten, J.; Wagner, H.; Rodriguez, C.; Brown, J.E.

    1994-09-01

    Ever increasing capabilities in video and computer technology have changed the face of video surveillance. From yesterday`s film and analog video tape-based systems, we now emerge into the digital era with surveillance systems capable of digital image processing, image analysis, decision control logic, and random data access features -- all of which provide greater versatility with the potential for increased effectiveness in video surveillance. Digital systems also offer other advantages such as the ability to ``compress`` data, providing increased storage capacities and the potential for allowing longer surveillance Periods. Remote surveillance and system to system communications are also a benefit that can be derived from digital surveillance systems. All of these features are extremely important in today`s climate Of increasing safeguards activity and decreasing budgets -- Los Alamos National Laboratory`s Safeguards Systems Group and the EURATOM Safeguards Directorate have teamed to design and implement a period surveillance system that will take advantage of the versatility of digital video for facility surveillance system that will take advantage of the versatility of digital video for facility surveillance and data review. In this Paper we will familiarize you with system components and features and report on progress in developmental areas such as image compression and region of interest processing.

  8. Systems and methods for self-synchronized digital sampling

    NASA Technical Reports Server (NTRS)

    Samson, Jr., John R. (Inventor)

    2008-01-01

    Systems and methods for self-synchronized data sampling are provided. In one embodiment, a system for capturing synchronous data samples is provided. The system includes an analog to digital converter adapted to capture signals from one or more sensors and convert the signals into a stream of digital data samples at a sampling frequency determined by a sampling control signal; and a synchronizer coupled to the analog to digital converter and adapted to receive a rotational frequency signal from a rotating machine, wherein the synchronizer is further adapted to generate the sampling control signal, and wherein the sampling control signal is based on the rotational frequency signal.

  9. Representation and matching of knowledge to design digital systems

    NASA Technical Reports Server (NTRS)

    Jones, J. U.; Shiva, S. G.

    1988-01-01

    A knowledge-based expert system is described that provides an approach to solve a problem requiring an expert with considerable domain expertise and facts about available digital hardware building blocks. To design digital hardware systems from their high level VHDL (Very High Speed Integrated Circuit Hardware Description Language) representation to their finished form, a special data representation is required. This data representation as well as the functioning of the overall system is described.

  10. Simulating The SSF Information System

    NASA Technical Reports Server (NTRS)

    Deshpande, Govind K.; Kleine, Henry; Younger, Joseph C.; Sanders, Felicia A.; Smith, Jeffrey L.; Aster, Robert W.; Olivieri, Jerry M.; Paul, Lori L.

    1993-01-01

    Freedom Operations Simulation Test (FROST) computer program simulates operation of SSF information system, tracking every packet of data from generation to destination, for both uplinks and downlinks. Collects various statistics concerning operation of system and provides reports of statistics at intervals specified by user. FROST also incorporates graphical-display capability to enhance interpretation of these statistics. Written in SIMSCRIPT 11.5.

  11. The new digital data acquisition system for Gammasphere

    NASA Astrophysics Data System (ADS)

    Carpenter, M. P.; Albers, M.; Anderson, J. T.; Ayangeakaa, A.; David, H. M.; Hoffman, C. R.; Janssens, R. V. F.; Lauritsen, T.; Madden, T.; Oberling, M.; Seweryniak, D.; Wilt, P.; Zhu, S.

    2015-10-01

    A new digital-based data acquisition system (DAQ) for Gammasphere has been developed. This system leverages the electronics designed for the GRETINA collaboration. At the center of this development are the GRETINA 10-channel digitizer modules which handle the Ge preamp signals at a 100MHz rate, and master trigger and router modules which allow triggers to be constructed from information obtained from the digitizer channels. The new DAQ increases event throughput significantly over the existing system while addressing multiple repair and maintenance issues. New hardware and firmware to integrate the DAQ with Gammasphere and its suite of ancillary detectors has been developed allowing for a seamless changeover from the analog DAQ to the new digital system. An overview of the system and illustrative results from several recent experiments will be presented. This material is based on work supported by the DOE, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-06CH11357.

  12. HMD digital night vision system for fixed wing fighters

    NASA Astrophysics Data System (ADS)

    Foote, Bobby D.

    2013-05-01

    Digital night sensor technology offers both advantages and disadvantages over standard analog systems. As the digital night sensor technology matures and disadvantages are overcome, the transition away from analog type sensors will increase with new programs. In response to this growing need RCEVS is actively investing in digital night vision systems that will provide the performance needed for the future. Rockwell Collins and Elbit Systems of America continue to invest in digital night technology and have completed laboratory, ground and preliminary flight testing to evaluate the important key factors for night vision. These evaluations have led to a summary of the maturity of the digital night capability and status of the key performance gap between analog and digital systems. Introduction of Digital Night Vision Systems can be found in the roadmap of future fixed wing and rotorcraft programs beginning in 2015. This will bring a new set of capabilities to the pilot that will enhance his abilities to perform night operations with no loss of performance.

  13. Digital core based transmitted ultrasonic wave simulation and velocity accuracy analysis

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Shan, Rui

    2016-06-01

    Transmitted ultrasonic wave simulation (TUWS) in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When simulating wave propagates in a 3D digital core, two additional layers are attached to its two surfaces vertical to the wave-direction and one planar wave source and two receiver-arrays are properly installed. After source excitation, the two receivers then record incident and transmitted waves of the digital rock. Wave propagating velocity, which is the velocity of the digital core, is computed by the picked peak-time difference between the two recorded waves. To evaluate the accuracy of TUWS, a digital core is fully saturated with gas, oil, and water to calculate the corresponding velocities. The velocities increase with decreasing wave frequencies in the simulation frequency band, and this is considered to be the result of scattering. When the pore fluids are varied from gas to oil and finally to water, the velocity-variation characteristics between the different frequencies are similar, thereby approximately following the variation law of velocities obtained from linear elastic statics simulation (LESS), although their absolute values are different. However, LESS has been widely used. The results of this paper show that the transmission ultrasonic simulation has high relative precision.

  14. Digital flight control research

    NASA Technical Reports Server (NTRS)

    Potter, J. E.; Stern, R. G.; Smith, T. B.; Sinha, P.

    1974-01-01

    The results of studies which were undertaken to contribute to the design of digital flight control systems, particularly for transport aircraft are presented. In addition to the overall design considerations for a digital flight control system, the following topics are discussed in detail: (1) aircraft attitude reference system design, (2) the digital computer configuration, (3) the design of a typical digital autopilot for transport aircraft, and (4) a hybrid flight simulator.

  15. Modeling digital breast tomosynthesis imaging systems for optimization studies

    NASA Astrophysics Data System (ADS)

    Lau, Beverly Amy

    Digital breast tomosynthesis (DBT) is a new imaging modality for breast imaging. In tomosynthesis, multiple images of the compressed breast are acquired at different angles, and the projection view images are reconstructed to yield images of slices through the breast. One of the main problems to be addressed in the development of DBT is the optimal parameter settings to obtain images ideal for detection of cancer. Since it would be unethical to irradiate women multiple times to explore potentially optimum geometries for tomosynthesis, it is ideal to use a computer simulation to generate projection images. Existing tomosynthesis models have modeled scatter and detector without accounting for oblique angles of incidence that tomosynthesis introduces. Moreover, these models frequently use geometry-specific physical factors measured from real systems, which severely limits the robustness of their algorithms for optimization. The goal of this dissertation was to design the framework for a computer simulation of tomosynthesis that would produce images that are sensitive to changes in acquisition parameters, so an optimization study would be feasible. A computer physics simulation of the tomosynthesis system was developed. The x-ray source was modeled as a polychromatic spectrum based on published spectral data, and inverse-square law was applied. Scatter was applied using a convolution method with angle-dependent scatter point spread functions (sPSFs), followed by scaling using an angle-dependent scatter-to-primary ratio (SPR). Monte Carlo simulations were used to generate sPSFs for a 5-cm breast with a 1-cm air gap. Detector effects were included through geometric propagation of the image onto layers of the detector, which were blurred using depth-dependent detector point-spread functions (PRFs). Depth-dependent PRFs were calculated every 5-microns through a 200-micron thick CsI detector using Monte Carlo simulations. Electronic noise was added as Gaussian noise as a

  16. Automatic digital photo-book making system

    NASA Astrophysics Data System (ADS)

    Wang, Wiley; Teo, Patrick; Muzzolini, Russ

    2010-02-01

    The diversity of photo products has grown more than ever before. A group of photos are not only printed individually, but also can be arranged in specific order to tell a story, such as in a photo book, a calendar or a poster collage. Similar to making a traditional scrapbook, digital photo book tools allow the user to choose a book style/theme, layouts of pages, backgrounds and the way the pictures are arranged. This process is often time consuming to users, given the number of images and the choices of layout/background combinations. In this paper, we developed a system to automatically generate photo books with only a few initial selections required. The system utilizes time stamps, color indices, orientations and other image properties to best fit pictures into a final photo book. The common way of telling a story is to lay the pictures out in chronological order. If the pictures are proximate in time, they will coincide with each other and are often logically related. The pictures are naturally clustered along a time line. Breaks between clusters can be used as a guide to separate pages or spreads, thus, pictures that are logically related can stay close on the same page or spread. When people are making a photo book, it is helpful to start with chronologically grouped images, but time alone wont be enough to complete the process. Each page is limited by the number of layouts available. Many aesthetic rules also apply, such as, emphasis of preferred pictures, consistency of local image density throughout the whole book, matching a background to the content of the images, and the variety of adjacent page layouts. We developed an algorithm to group images onto pages under the constraints of aesthetic rules. We also apply content analysis based on the color and blurriness of each picture, to match backgrounds and to adjust page layouts. Some of our aesthetic rules are fixed and given by designers. Other aesthetic rules are statistic models trained by using

  17. Subjective image quality comparison between two digital dental radiographic systems and conventional dental film

    PubMed Central

    Ajmal, Muhammed; Elshinawy, Mohamed I.

    2014-01-01

    Objectives Digital radiography has become an integral part of dentistry. Digital radiography does not require film or dark rooms, reduces X-ray doses, and instantly generates images. The aim of our study was to compare the subjective image quality of two digital dental radiographic systems with conventional dental film. Materials & methods A direct digital (DD) ‘Digital’ system by Sirona, a semi-direct (SD) digital system by Vista-scan, and Kodak ‘E’ speed dental X-ray films were selected for the study. Endodontically-treated extracted teeth (n = 25) were used in the study. Details of enamel, dentin, dentino-enamel junction, root canal filling (gutta percha), and simulated apical pathology were investigated with the three radiographic systems. The data were subjected to statistical analyzes to reveal differences in subjective image quality. Results Conventional dental X-ray film was superior to the digital systems. For digital systems, DD imaging was superior to SD imaging. Conclusion Conventional film yielded superior image quality that was statistically significant in almost all aspects of comparison. Conventional film was followed in image quality by DD, and SD provided the lowest quality images. Conventional film is still considered the gold standard to diagnose diseases affecting the jawbone. Recommendations Improved software and hardware for digital imaging systems are now available and these improvements may now yield images that are comparable in quality to conventional film. However, we recommend that studies still use more observers and other statistical methods to produce ideal results. PMID:25382946

  18. Modular Aero-Propulsion System Simulation

    NASA Technical Reports Server (NTRS)

    Parker, Khary I.; Guo, Ten-Huei

    2006-01-01

    The Modular Aero-Propulsion System Simulation (MAPSS) is a graphical simulation environment designed for the development of advanced control algorithms and rapid testing of these algorithms on a generic computational model of a turbofan engine and its control system. MAPSS is a nonlinear, non-real-time simulation comprising a Component Level Model (CLM) module and a Controller-and-Actuator Dynamics (CAD) module. The CLM module simulates the dynamics of engine components at a sampling rate of 2,500 Hz. The controller submodule of the CAD module simulates a digital controller, which has a typical update rate of 50 Hz. The sampling rate for the actuators in the CAD module is the same as that of the CLM. MAPSS provides a graphical user interface that affords easy access to engine-operation, engine-health, and control parameters; is used to enter such input model parameters as power lever angle (PLA), Mach number, and altitude; and can be used to change controller and engine parameters. Output variables are selectable by the user. Output data as well as any changes to constants and other parameters can be saved and reloaded into the GUI later.

  19. A 3D digital medical photography system in paediatric medicine.

    PubMed

    Williams, Susanne K; Ellis, Lloyd A; Williams, Gigi

    2008-01-01

    In 2004, traditional clinical photography services at the Educational Resource Centre were extended using new technology. This paper describes the establishment of a 3D digital imaging system in a paediatric setting at the Royal Children's Hospital, Melbourne.

  20. A method for reducing sampling jitter in digital control systems

    NASA Technical Reports Server (NTRS)

    Anderson, T. O.; HURBD W. J.; Hurd, W. J.

    1969-01-01

    Digital phase lock loop system is designed by smoothing the proportional control with a low pass filter. This method does not significantly affect the loop dynamics when the smoothing filter bandwidth is wide compared to loop bandwidth.

  1. DigitalGlobe(TM) Incorporated Corporate and System Update

    NASA Technical Reports Server (NTRS)

    Thomassie, Brett

    2007-01-01

    This viewgraph presentation describes a system update of Quickbird, the world's highest resolution commercial imaging satellite, operated by DigitalGlobe (TM) Incorporated. A satellite comparison of Quickbird, WorldView-60, and WorldView-110 is also presented.

  2. Analog-digital models of stream-aquifer systems

    USGS Publications Warehouse

    Moulder, E.A.; Jenkins, C.T.

    1969-01-01

    The best features of analog and digital computers were combined to make a management model of a stream-aquifer system. The analog model provides a means for synthesizing, verifying, and summarizing aquifer properties; the digital model permits rapid calculation of the effects of water management practices. Given specific management alternatives, a digital program can be written that will optimize operation plans of stream-aquifer systems. The techniques are demonstrated by application to a study of the Arkansas River valley in southeastern Colorado.

  3. Optical-digital hybrid image search system in cloud environment

    NASA Astrophysics Data System (ADS)

    Ikeda, Kanami; Kodate, Kashiko; Watanabe, Eriko

    2016-09-01

    To improve the versatility and usability of optical correlators, we developed an optical-digital hybrid image search system consisting of digital servers and an optical correlator that can be used to perform image searches in the cloud environment via a web browser. This hybrid system employs a simple method to obtain correlation signals and has a distributed network design. The correlation signals are acquired by using an encoder timing signal generated by a rotating disk, and the distributed network design facilitates the replacement and combination of the digital correlation server and the optical correlator.

  4. Optical–digital hybrid image search system in cloud environment

    NASA Astrophysics Data System (ADS)

    Ikeda, Kanami; Kodate, Kashiko; Watanabe, Eriko

    2016-09-01

    To improve the versatility and usability of optical correlators, we developed an optical–digital hybrid image search system consisting of digital servers and an optical correlator that can be used to perform image searches in the cloud environment via a web browser. This hybrid system employs a simple method to obtain correlation signals and has a distributed network design. The correlation signals are acquired by using an encoder timing signal generated by a rotating disk, and the distributed network design facilitates the replacement and combination of the digital correlation server and the optical correlator.

  5. Digital transmitter for data bus communications system

    NASA Technical Reports Server (NTRS)

    Proch, G. E.

    1974-01-01

    Digital transmitter designed for Manchester coded signals (and all signals with ac waveforms) generated at a rate of one megabit per second includes efficient output isolation circuit. Transmitter consists of logic control section, amplifier, and output isolation section. Output isolation circuit provides dynamic impedance at terminals as function of amplifier output level.

  6. The Description, Simulation, and Automatic Implementation of Digital Computer Processors.

    ERIC Educational Resources Information Center

    Darringer, John A.

    A programing language, called APDL (Algorithmic Processor Description Language), is developed for describing the behavior of digital computer processors irrespective of their eventual implementation. ALGOL 60 is used as a base language and several features are added including: (1) register data types and operators to allow the convenient and…

  7. Digital document imaging systems: An overview and guide

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This is an aid to NASA managers in planning the selection of a Digital Document Imaging System (DDIS) as a possible solution for document information processing and storage. Intended to serve as a manager's guide, this document contains basic information on digital imaging systems, technology, equipment standards, issues of interoperability and interconnectivity, and issues related to selecting appropriate imaging equipment based upon well defined needs.

  8. System for objective assessment of image differences in digital cinema

    NASA Astrophysics Data System (ADS)

    Fliegel, Karel; Krasula, Lukáš; Páta, Petr; Myslík, Jiří; Pecák, Josef; Jícha, Marek

    2014-09-01

    There is high demand for quick digitization and subsequent image restoration of archived film records. Digitization is very urgent in many cases because various invaluable pieces of cultural heritage are stored on aging media. Only selected records can be reconstructed perfectly using painstaking manual or semi-automatic procedures. This paper aims to answer the question what are the quality requirements on the restoration process in order to obtain acceptably close visual perception of the digitally restored film in comparison to the original analog film copy. This knowledge is very important to preserve the original artistic intention of the movie producers. Subjective experiment with artificially distorted images has been conducted in order to answer the question what is the visual impact of common image distortions in digital cinema. Typical color and contrast distortions were introduced and test images were presented to viewers using digital projector. Based on the outcome of this subjective evaluation a system for objective assessment of image distortions has been developed and its performance tested. The system utilizes calibrated digital single-lens reflex camera and subsequent analysis of suitable features of images captured from the projection screen. The evaluation of captured image data has been optimized in order to obtain predicted differences between the reference and distorted images while achieving high correlation with the results of subjective assessment. The system can be used to objectively determine the difference between analog film and digital cinema images on the projection screen.

  9. Several basic problems in digital simulation of structural reliability of Solid Rocket Motor (SRM)

    NASA Astrophysics Data System (ADS)

    Tan, Sanwu; Wang, Binxun

    1993-08-01

    The aim of the research, the main technical specifications, the verification test, and the critical technical items are discussed. The simulation process of fiber-reinforced composite cases and the solid grain of the SRM were presented as examples to illustrate the general program of digital simulation for SRM structural reliability.

  10. A Digital Simulation Program for Health Science Students to Follow Drug Levels in the Body

    ERIC Educational Resources Information Center

    Stavchansky, Salomon; And Others

    1977-01-01

    The Rayetheon Scientific Simulation Language (RSSL) program, an easily-used simulation on the CDC/6600 computer at the University of Texas at Austin, offers a simple method of solving differential equations on a digital computer. It is used by undergraduate biopharmaceutics-pharmacokinetics students and graduate students in all areas. (Author/LBH)

  11. Healthcare system simulation using Witness

    NASA Astrophysics Data System (ADS)

    Khakdaman, Masoud; Zeinahvazi, Milad; Zohoori, Bahareh; Nasiri, Fardokht; Yew Wong, Kuan

    2013-02-01

    Simulation techniques have a proven track record in manufacturing industry as well as other areas such as healthcare system improvement. In this study, simulation model of a health center in Malaysia is developed through the application of WITNESS simulation software which has shown its flexibility and capability in manufacturing industry. Modelling procedure is started through process mapping and data collection and continued with model development, verification, validation and experimentation. At the end, final results and possible future improvements are demonstrated.

  12. Refinement and validation of two digital Microwave Landing System (MLS) theoretical models

    NASA Technical Reports Server (NTRS)

    Duff, W. G.; Guarino, C. R.

    1975-01-01

    Two digital microwave landing system theoretical models are considered which are generic models for the Doppler and scanning-beam frequency reference versions of the MLS. These models represent errors resulting from both system noise and discrete multipath. The data used for the validation effort were obtained from the Texas Instrument conventional scanning beam and the Hazeltine Doppler feasibility hardware versions of the MLS. Topics discussed include tape read software, time history plots, computation of power spectral density, smoothed power spectra, best-fit models, different equations for digital simulation, and discrete multipath errors.

  13. Method for simulating dose reduction in digital mammography using the Anscombe transformation

    PubMed Central

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Bakic, Predrag R.; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

    2016-01-01

    Purpose: This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. Methods: The method developed in this work consists of scaling a mammogram acquired at the standard radiation dose and adding signal-dependent noise. The algorithm accounts for specific issues relevant in digital mammography images, such as anisotropic noise, spatial variations in pixel gain, and the effect of dose reduction on the detective quantum efficiency. The scaling process takes into account the linearity of the system and the offset of the detector elements. The inserted noise is obtained by acquiring images of a flat-field phantom at the standard radiation dose and at the simulated dose. Using the Anscombe transformation, a relationship is created between the calculated noise mask and the scaled image, resulting in a clinical mammogram with the same noise and gray level characteristics as an image acquired at the lower-radiation dose. Results: The performance of the proposed algorithm was validated using real images acquired with an anthropomorphic breast phantom at four different doses, with five exposures for each dose and 256 nonoverlapping ROIs extracted from each image and with uniform images. The authors simulated lower-dose images and compared these with the real images. The authors evaluated the similarity between the normalized noise power spectrum (NNPS) and power spectrum (PS) of simulated images and real images acquired with the same dose. The maximum relative error was less than 2.5% for every ROI. The added noise was also evaluated by measuring the local variance in the real and simulated images. The relative average error for the local variance was smaller than 1%. Conclusions: A new method is proposed for simulating dose reduction in clinical mammograms. In this method, the dependency between image noise and image signal is addressed using a novel application of the Anscombe

  14. Intellectual property protection systems and digital watermarking.

    PubMed

    Lacy, J; Quackenbush, S; Reibman, A; Snyder, J

    1998-12-01

    Adequate protection of digital copies of multimedia content - both audio and video - is a prerequisite to the distribution of this content over networks. Until recently digital audio and video content has been protected by its size: it is difficult to distribute and store without compression. Modern compression algorithms allow substantial bitrate reduction while maintaining high-fidelity reproduction. If distribution of these algorithms is controlled, cleartext uncompressed content is still protected by its size. However, once the compression algorithms are generally available cleartext content becomes extremely vulnerable to piracy. In this paper we explore the implications of this vulnerability and discuss the use of compression and watermarking in the control of piracy. PMID:19384398

  15. A multiprocessor operating system simulator

    SciTech Connect

    Johnston, G.M.; Campbell, R.H. . Dept. of Computer Science)

    1988-01-01

    This paper describes a multiprocessor operating system simulator that was developed by the authors in the Fall of 1987. The simulator was built in response to the need to provide students with an environment in which to build and test operating system concepts as part of the coursework of a third-year undergraduate operating systems course. Written in C++, the simulator uses the co-routine style task package that is distributed with the AT and T C++ Translator to provide a hierarchy of classes that represents a broad range of operating system software and hardware components. The class hierarchy closely follows that of the Choices family of operating systems for loosely and tightly coupled multiprocessors. During an operating system course, these classes are refined and specialized by students in homework assignments to facilitate experimentation with different aspects of operating system design and policy decisions. The current implementation runs on the IBM RT PC under 4.3bsd UNIX.

  16. A Multiprocessor Operating System Simulator

    NASA Technical Reports Server (NTRS)

    Johnston, Gary M.; Campbell, Roy H.

    1988-01-01

    This paper describes a multiprocessor operating system simulator that was developed by the authors in the Fall semester of 1987. The simulator was built in response to the need to provide students with an environment in which to build and test operating system concepts as part of the coursework of a third-year undergraduate operating systems course. Written in C++, the simulator uses the co-routine style task package that is distributed with the AT&T C++ Translator to provide a hierarchy of classes that represents a broad range of operating system software and hardware components. The class hierarchy closely follows that of the 'Choices' family of operating systems for loosely- and tightly-coupled multiprocessors. During an operating system course, these classes are refined and specialized by students in homework assignments to facilitate experimentation with different aspects of operating system design and policy decisions. The current implementation runs on the IBM RT PC under 4.3bsd UNIX.

  17. Real-time hybrid computer simulation of a small turboshaft engine and control system

    NASA Technical Reports Server (NTRS)

    Hart, C. E.; Wenzel, L. M.

    1984-01-01

    The development of an analytical model of a small turboshaft engine designed for helicopter propulsion systems is described. The model equations were implemented on a hybrid computer system to provide a real time nonlinear simulation of the engine performance over a wide operating range. The real time hybrid simulation of the engine was used to evaluate a microprocessor based digital control module. This digital control module was developed as part of an advanced rotorcraft control program. After tests with the hybrid engine simulation the digital control module was used to control a real engine in an experimental program. A hybrid simulation of the engine's electrical hydromechanical control system was developed. This allowed to vary the fuel flow and torque load inputs to the hybrid engine simulation for simulating transient operation. A steady-state data and the experimental tests are compared. Analytical model equations, analog computer diagrams, and a digital computer flow chart are included.

  18. GPS system simulation methodology

    NASA Technical Reports Server (NTRS)

    Ewing, Thomas F.

    1993-01-01

    The following topics are presented: background; Global Positioning System (GPS) methodology overview; the graphical user interface (GUI); current models; application to space nuclear power/propulsion; and interfacing requirements. The discussion is presented in vugraph form.

  19. Digital data storage systems, computers, and data verification methods

    DOEpatents

    Groeneveld, Bennett J.; Austad, Wayne E.; Walsh, Stuart C.; Herring, Catherine A.

    2005-12-27

    Digital data storage systems, computers, and data verification methods are provided. According to a first aspect of the invention, a computer includes an interface adapted to couple with a dynamic database; and processing circuitry configured to provide a first hash from digital data stored within a portion of the dynamic database at an initial moment in time, to provide a second hash from digital data stored within the portion of the dynamic database at a subsequent moment in time, and to compare the first hash and the second hash.

  20. Comparison of analog and digital pulse-shape-discrimination systems

    NASA Astrophysics Data System (ADS)

    Sosa, C. S.; Flaska, M.; Pozzi, S. A.

    2016-08-01

    Pulse shape discrimination (PSD) performance of two optimized PSD systems (one digital and one analog) is compared in this work. One system uses digital charge integration, while the other system uses analog zero crossing. Measurements were conducted with each PSD system using the CAEN V1720 (250 MHz) data acquisition system. An organic-liquid scintillator, coupled to a photo-multiplier tube, was used to detect neutrons and gamma rays from a Cf-252 spontaneous-fission source. The PSD performance of both systems was optimized and quantified using a traditional figure-of-merit (FOM) approach. FOM's were found for three, 300 keVee light-output bins, spanning from 100 to 1000 keVee, and one larger bin from 100 to 1800 keVee. Digital PSD outperformed analog PSD in the lowest light-output bin by approximately 50%, and by 11% for the highest light-output bin.

  1. State-of-the-art digital data acquisition system

    SciTech Connect

    Scudiere, M.B.; Adams, D.J.; Beshears, D.L.; Capps, G.J.; Jordan, J.K.; Napier, R.W.; Ott, G.W.; White, C.P.; Nodine, R.N.; Todd, R.A.

    1988-11-01

    The torpedo data acquisition (TORDAC) system is a stand-alone, transportable data acquisition system, packaged to fit into a torpedo-sized vehicle, and is designed to record a mix of user-selectable analog and digital data. TORDAC calibrates, conditions, digitizes, and records multiple channels of analog voltage outputs generated by arrays of vehicle sensors and it also records digital data streams from on-board digital processors. The maximum write speed of the system is 107 Mb/s (one hour duration) which provides a recordable analog bandwidth in excess of 1800 kHz with 96-dB resolution. Configuration of analog signal inputs is flexible; a typical configuration will record 60 wide-band channels (sampled at 100 kHz with a 16-bit analog-to-digital (A/D) converter) and 56 narrow-band channels (sampled at 1.5 kHz with a 12-bit A/D converter). TORDAC also generates programmable output signals (to control internal or external functions) based on the status of inputs being recorded. Operator control of the system for setup, checkout, playback, data validation, and data reduction is performed on networked computer workstations. Dedicated hardware is provided to reconstitute all analog voltage waveforms in real time (from recorded digitized data) to permit quick-look data validation. 14 figs., 1 tab.

  2. A feedback intervention to increase digital and paper checklist performance in technically advanced aircraft simulation.

    PubMed

    Rantz, William G; Van Houten, Ron

    2011-01-01

    This study examined whether pilots operating a flight simulator completed digital or paper flight checklists more accurately after receiving postflight graphic and verbal feedback. The dependent variable was the number of checklist items completed correctly per flight. Following treatment, checklist completion with paper and digital checklists increased from 38% and 39%, respectively, to nearly 100% and remained close to 100% after feedback and praise for improvement were withdrawn. Performance was maintained at or near 100% during follow-up probes.

  3. Wind Energy System Time-domain (WEST) analyzers using hybrid simulation techniques

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.

    1979-01-01

    Two stand-alone analyzers constructed for real time simulation of the complex dynamic characteristics of horizontal-axis wind energy systems are described. Mathematical models for an aeroelastic rotor, including nonlinear aerodynamic and elastic loads, are implemented with high speed digital and analog circuitry. Models for elastic supports, a power train, a control system, and a rotor gimbal system are also included. Limited correlation efforts show good comparisons between results produced by the analyzers and results produced by a large digital simulation. The digital simulation results correlate well with test data.

  4. Joint modeling and simulation system

    NASA Astrophysics Data System (ADS)

    Boyer, Richard T.; McQuay, William K.

    1993-08-01

    The defense budget is shrinking. Weapon systems are getting more complex. Test requirements are increasing. The training and war gaming scenarios are getting more demanding as fielded systems and training simulators are integrated to support combined arms training. To cope with these requirements and still stay within the budget, the Department of Defense is relying on modeling and simulation. The state of the modeling and simulation (M&S) art has advanced to the point where a user can now create incredibly realistic, extremely detailed models which can augment test and evaluation, support the acquisition process, enhance training and war gaming, facilitate intelligence gathering, and support detailed engineering.

  5. Gallium arsenide digital integrated circuits - A systems perspective

    NASA Astrophysics Data System (ADS)

    Kanopoulos, Nick

    The characteristics of GaAs electronic components and their integration into digital circuits are examined in an introduction for graduate engineering students. Chapters are devoted to GaAs components, GaAs logic-gate design, GaAs logic circuits, GaAs digital-IC design principles, packaging, high-speed testing and design for testability, and GaAs insertion into system design. Diagrams, drawings, and exercises for each chapter are included.

  6. Accurate Behavioral Simulator of All-Digital Time-Domain Smart Temperature Sensors by Using SIMULINK.

    PubMed

    Chen, Chun-Chi; Chen, Chao-Lieh; Lin, You-Ting

    2016-01-01

    This study proposes a new behavioral simulator that uses SIMULINK for all-digital CMOS time-domain smart temperature sensors (TDSTSs) for performing rapid and accurate simulations. Inverter-based TDSTSs offer the benefits of low cost and simple structure for temperature-to-digital conversion and have been developed. Typically, electronic design automation tools, such as HSPICE, are used to simulate TDSTSs for performance evaluations. However, such tools require extremely long simulation time and complex procedures to analyze the results and generate figures. In this paper, we organize simple but accurate equations into a temperature-dependent model (TDM) by which the TDSTSs evaluate temperature behavior. Furthermore, temperature-sensing models of a single CMOS NOT gate were devised using HSPICE simulations. Using the TDM and these temperature-sensing models, a novel simulator in SIMULINK environment was developed to substantially accelerate the simulation and simplify the evaluation procedures. Experiments demonstrated that the simulation results of the proposed simulator have favorable agreement with those obtained from HSPICE simulations, showing that the proposed simulator functions successfully. This is the first behavioral simulator addressing the rapid simulation of TDSTSs. PMID:27509507

  7. Accurate Behavioral Simulator of All-Digital Time-Domain Smart Temperature Sensors by Using SIMULINK

    PubMed Central

    Chen, Chun-Chi; Chen, Chao-Lieh; Lin, You-Ting

    2016-01-01

    This study proposes a new behavioral simulator that uses SIMULINK for all-digital CMOS time-domain smart temperature sensors (TDSTSs) for performing rapid and accurate simulations. Inverter-based TDSTSs offer the benefits of low cost and simple structure for temperature-to-digital conversion and have been developed. Typically, electronic design automation tools, such as HSPICE, are used to simulate TDSTSs for performance evaluations. However, such tools require extremely long simulation time and complex procedures to analyze the results and generate figures. In this paper, we organize simple but accurate equations into a temperature-dependent model (TDM) by which the TDSTSs evaluate temperature behavior. Furthermore, temperature-sensing models of a single CMOS NOT gate were devised using HSPICE simulations. Using the TDM and these temperature-sensing models, a novel simulator in SIMULINK environment was developed to substantially accelerate the simulation and simplify the evaluation procedures. Experiments demonstrated that the simulation results of the proposed simulator have favorable agreement with those obtained from HSPICE simulations, showing that the proposed simulator functions successfully. This is the first behavioral simulator addressing the rapid simulation of TDSTSs. PMID:27509507

  8. Choosing a Digital Asset Management System That's Right for You

    ERIC Educational Resources Information Center

    Kaplan, Deborah

    2009-01-01

    Planning is necessary in selecting the appropriate digital asset management system for your institution. Key issues one should consider in planning: the objects to be stored, where they come from, and how they will be accessed; the end users; and the needed staffing levels for system maintenance. During the development of the system requirements,…

  9. Digital Avionics Information System (DAIS): Training Requirements Analysis Model (TRAMOD).

    ERIC Educational Resources Information Center

    Czuchry, Andrew J.; And Others

    The training requirements analysis model (TRAMOD) described in this report represents an important portion of the larger effort called the Digital Avionics Information System (DAIS) Life Cycle Cost (LCC) Study. TRAMOD is the second of three models that comprise an LCC impact modeling system for use in the early stages of system development. As…

  10. 47 CFR 76.640 - Support for unidirectional digital cable products on digital cable systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... transporting programs and services from its headend to receiving devices. Cable systems that only pass through...) For each digital transport stream that includes one or more services carried in-the-clear, such... the channel identified with in-band PSIP data for all unscrambled in-the-clear services. (2)...

  11. Radiation dose implications of digital angiographic systems.

    PubMed

    Hynes, D M; Gershater, R; Edmonds, E W; Rowlands, J A; Baranoski, D; Turow, D G

    1984-08-01

    Digital subtraction angiography (DSA) has been widely accepted and applied. The concentration of iodine in the vessels of interest is low in intravenous DSA. The resultant images can be improved to some extent by increasing the radiation dose. Therefore DSA could become, and possibly could remain, a relatively high-dose procedure. The contributions to dose from the various components of the examination such as fluoroscopy, positioning, test exposures, and final acquisition runs are considered separately. Individual segments of a DSA examination are discussed to show how and where opportunities arise to reduce doses to the lowest levels consistent with satisfactory images. PMID:6377858

  12. Digital holographic video service system for natural color scene

    NASA Astrophysics Data System (ADS)

    Seo, Young-Ho; Lee, Yoon-Hyuk; Koo, Ja-Myung; Kim, Woo-Youl; Yoo, Ji-Sang; Kim, Dong-Wook

    2013-11-01

    We propose a new system that can generate digital holograms using natural color information. The system consists of a camera system for capturing images (object points) and software (S/W) for various image processing. The camera system uses a vertical rig, which is equipped with two depth and RGB cameras and a cold mirror, which has different reflectances according to wavelength for obtaining images with the same viewpoint. The S/W is composed of the engines for processing the captured images and executing computer-generated hologram for generating digital holograms using general-purpose graphics processing units. Each algorithm was implemented using C/C++ and CUDA languages, and all engines in the form of library were integrated in LabView environment. The proposed system can generate about 10 digital holographic frames per second using about 6 K object points.

  13. A field-deployable digital acoustic measurement system

    NASA Technical Reports Server (NTRS)

    Gray, David L.; Wright, Kenneth D., II; Rowland, Wayne D.

    1991-01-01

    A field deployable digital acoustic measurement system was developed to support acoustic research programs at the Langley Research Center. The system digitizes the acoustic inputs at the microphone, which can be located up to 1000 feet from the van which houses the acquisition, storage, and analysis equipment. Digitized data from up to 12 microphones is recorded on high density 8mm tape and is analyzed post-test by a microcomputer system. Synchronous and nonsynchronous sampling is available with maximum sample rates of 12,500 and 40,000 samples per second respectively. The high density tape storage system is capable of storing 5 gigabytes of data at transfer rates up to 1 megabyte per second. System overall dynamic range exceeds 83 dB.

  14. [Application of ecological classification system in China's digital forestry].

    PubMed

    Tang, Li-Na; Dai, Li-Min

    2008-02-01

    In China's conventional forest management system, there are two types of sub-compartment, i.e., the 2nd- and 3rd-level sub-compartments, which are concurrent but inconsistent in size and boundary locations. Even in the same type of sub-compartments, the inconsistency still existed at different time, which is unbeneficial to the long-term forest management planning by using digital technologies. With the mountainous region in eastern Liaoning Province as a case, this paper established an ecological classification system (ECS), which contained 5 ecological land types (ELTs) and 34 ecological land type phases (ELTPs). Based on the basic technical needs of China's digital forestry, the ELTPs could be used as a fixed sub-compartment system. A compatible forest inventory system was designed then. It was concluded that ecosystem management based on ECS and geospatial information technologies combined with computer models and decision-support systems would be the important component of digital forestry.

  15. Digital item for digital human memory--television commerce application: family tree albuming system

    NASA Astrophysics Data System (ADS)

    Song, Jaeil; Lee, Hyejoo; Hong, JinWoo

    2004-01-01

    Technical advance in creating, storing digital media in daily life enables computers to capture human life and remember it as people do. A critical point with digitizing human life is how to recall bits of experience that are associated by semantic information. This paper proposes a technique for structuring dynamic digital object based on MPEG-21 Digital Item (DI) in order to recall human"s memory and providing interactive TV service on family tree albuming system as one of its applications. DIs are a dynamically reconfigurable, uniquely identified, described by a descriptor language, logical unit for structuring relationship among multiple media resources. Digital Item Processing (DIP) provides the means to interact with DIs to remind context to user, with active properties where objects have executable properties. Each user can adapt DIs" active properties to tailor the behavior of DIs to match his/her own specific needs. DIs" technologies in Intellectual Property Management and Protection (IPMP) can be used for privacy protection. In the interaction between the social space and technological space, the internal dynamics of family life fits well sharing family albuming service via family television. Family albuming service can act as virtual communities builders for family members. As memory is shared between family members, multiple annotations (including active properties on contextual information) will be made with snowballing value.

  16. VHDL Modeling and Simulation for a Digital Target Imaging Architecture for Multiple Large Targets Generation

    NASA Astrophysics Data System (ADS)

    Bergoen, Halkan

    2002-09-01

    The subject of this thesis is to model and verify the correctness of the architecture of the Digital Image Synthesizer (DIS). The DIS, a system-on-a-chip, is especially useful as a counter-targeting repeater. It synthesizes the characteristic echo signature of a pre-selected target. The VHDL (VHSIC (Very High Speed Integrated Circuit) Hardware Description Language) description of the DIS architecture was exported from Tanner S-Edit, modified, and simulated. Different software oriented verification approaches were researched and a White-box approach to functional verification was adopted. An algorithm based on the hardware functionality was developed to compare expected and simulated results. Initially, the architecture of one Range Bin Modulator was exported. Modifications to the VHDL source code included modeling of the behavior of the N-FET and P-FET (Positive Channel Field Effect Transistor) transistors as well as Ground and Vdd (the voltages connected to the drains of the FETs). It also included renaming of entities to comply with VHDL naming conventions. Simulation results were compared to manual calculations and Matlab programs to verify the architecture. The procedure was repeated for the architecture of an Eight-Range Bin Modulator with equally successful results. VHDL was then used to create a super class of a 32-Range Bin Modulator. Test vectors developed in Matlab were used to yet again verify correct functionality.

  17. Field-Deployable Acoustic Digital Systems for Noise Measurement

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Wright, Kenneth D.; Lunsford, Charles B.; Smith, Charlie D.

    2000-01-01

    Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for the first time in the field along with DAMS system for the Community Noise Flight Test using the NASA LaRC-757 aircraft during April, 2000. The test was performed at Airborne Airport in Wilmington, OH to validate predicted noise reduction benefits from alternative operational procedures. The test matrix was composed of various combinations of altitude, cutback power, and aircraft weight. The DAMS digitizes the acoustic inputs at the microphone site and can be located up to 2000 feet from the van which houses the acquisition, storage and analysis equipment. Digitized data from up to 10 microphones is recorded on a Jaz disk and is analyzed post-test by microcomputer system. The RASS digitizes and stores acoustic inputs at the microphone site that can be located up to three miles from the base station and can compose a 3 mile by 3 mile array of microphones. 16-bit digitized data from the microphones is stored on removable Jaz disk and is transferred through a high speed array to a very large high speed permanent storage device. Up to 30 microphones can be utilized in the array. System control and monitoring is accomplished via Radio Frequency (RF) link. This paper will present a detailed description of both systems, along with acoustic data analysis from both systems.

  18. Analog/digital pH meter system I.C.

    NASA Astrophysics Data System (ADS)

    Vincent, Paul; Park, Jea

    The project utilizes design automation software tools to design, simulate, and fabricate a pH meter integrated circuit (IC) system including a successive approximation type seven-bit analog to digital converter circuits using a 1.25 micron N-Well CMOS MOSIS process. The input voltage ranges from 0.5 to 1.0 V derived from a special type pH sensor, and the output is a three-digit decimal number display of pH with one decimal point.

  19. Analog/digital pH meter system I.C.

    NASA Technical Reports Server (NTRS)

    Vincent, Paul; Park, Jea

    1992-01-01

    The project utilizes design automation software tools to design, simulate, and fabricate a pH meter integrated circuit (IC) system including a successive approximation type seven-bit analog to digital converter circuits using a 1.25 micron N-Well CMOS MOSIS process. The input voltage ranges from 0.5 to 1.0 V derived from a special type pH sensor, and the output is a three-digit decimal number display of pH with one decimal point.

  20. Digital control in LLRF system for CYCIAE-100 cyclotron

    NASA Astrophysics Data System (ADS)

    Yin, Zhiguo; Fu, Xiaoliang; Ji, Bin; Zhang, Tianjue; Wang, Chuan

    2016-05-01

    As a driven accelerator, the CYCIAE-100 cyclotron is designed by China Institute of Atomic Energy for the Beijing Radio Ion-beam Facility project. The cyclotron RF system is designed to use two RF power sources of 100 kW to drive two half-wavelength cavities respectively. Two Dee accelerating electrodes are kept separately from each other inside the cyclotron, while their accelerating voltages are maintained in phase by the efforts of LLRF control. An analog-digital hybrid LLRF system has been developed to achieve cavity tuning control, dee voltage amplitude and phase stabilization etc. The analog subsystems designs are focused on RF signal up/down conversion, tuning control, and dee voltage regulation. The digital system provides an RF signal source, aligns the cavity phases and maintains a Finite State Machine. The digital parts combine with the analog functions to provide the LLRF control. A brief system hardware introduction will be given in this paper, followed by the review of several major characteristics of the digital control in the 100 MeV cyclotron LLRF system. The commissioning is also introduced, and most of the optimization during the process was done by changing the digital parts.

  1. High-precision digital charge-coupled device TV system

    NASA Astrophysics Data System (ADS)

    Vishnevsky, Grigory I.; Ioffe, S. A.; Berezin, V. Y.; Rybakov, M. I.; Mikhaylov, A. V.; Belyaev, L. V.

    1991-06-01

    In certain test, measurement, and research applications of CCD TV systems, the greater accuracy than usual 8-bit frame-grabbers can provide is demanded without the system being too expensive. The paper presents the concept and features of the high-precision low-cost digital CCD TV system intended for obtaining 12-bit monochrome images of immobile or relatively slow moving objects. The increase in accuracy is achieved by the specific digitization procedure -- one column per frame, which combines the benefits of a slow A/D converter with real-time TV imaging compatibility. To reduce speed restrictions on sample- and-hold circuits, a zoomed pixel read out cycle, corresponding to the pixel to be digitized, is proposed. The system provides great flexibility in choice of integration times and readout rates by means of a programmable readout sequencer, and is easily adaptable to various user demands and CCDs types.

  2. Digital interface of electronic transformers based on embedded system

    NASA Astrophysics Data System (ADS)

    Shang, Qiufeng; Qi, Yincheng

    2008-10-01

    Benefited from digital interface of electronic transformers, information sharing and system integration in substation can be realized. An embedded system-based digital output scheme of electronic transformers is proposed. The digital interface is designed with S3C44B0X 32bit RISC microprocessor as the hardware platform. The μCLinux operation system (OS) is transplanted on ARM7 (S3C44B0X). Applying Ethernet technology as the communication mode in the substation automation system is a new trend. The network interface chip RTL8019AS is adopted. Data transmission is realized through the in-line TCP/IP protocol of uClinux embedded OS. The application result and character analysis show that the design can meet the real-time and reliability requirements of IEC60044-7/8 electronic voltage/current instrument transformer standards.

  3. Pilot Study on the Detection of Simulated Lesions Using a 2D and 3D Digital Full-Field Mammography System with a Newly Developed High Resolution Detector Based on Two Shifts of a-Se.

    PubMed

    Schulz-Wendtland, R; Bani, M; Lux, M P; Schwab, S; Loehberg, C R; Jud, S M; Rauh, C; Bayer, C M; Beckmann, M W; Uder, M; Fasching, P A; Adamietz, B; Meier-Meitinger, M

    2012-05-01

    Purpose: Experimental study of a new system for digital 2D and 3D full-field mammography (FFDM) using a high resolution detector based on two shifts of a-Se. Material and Methods: Images were acquired using the new FFDM system Amulet® (FujiFilm, Tokio, Japan), an a-Se detector (receptor 24 × 30 cm(2), pixel size 50 µm, memory depth 12 bit, spatial resolution 10 lp/mm, DQE > 0.50). Integrated in the detector is a new method for data transfer, based on optical switch technology. The object of investigation was the Wisconsin Mammographic Random Phantom, Model 152A (Radiation Measurement Inc., Middleton, WI, USA) and the same parameters and exposure data (Tungsten, 100 mAs, 30 kV) were consistently used. We acquired 3 different pairs of images in the c-c and ml planes (2D) and in the c-c and c-c planes with an angle of 4 degrees (3D). Five radiologists experienced in mammography (experience ranging from 3 months to more than 5 years) analyzed the images (monitoring) which had been randomly encoded (random generator) with regard to the recognition of details such as specks of aluminum oxide (200-740 µm), nylon fibers (0.4-1.6 mm) and round lesions/masses (diameters 5-14 mm), using special linear glasses for 3D visualization, and compared the results. Results: A total of 225 correct positive decisions could be detected: we found 222 (98.7 %) correct positive results for 2D and 3D visualization in each case. Conclusion: The results of this phantom study showed the same detection rates for both 2D and 3D imaging using full field digital mammography. Our results must be confirmed in further clinical trials.

  4. System Simulation by Recursive Feedback: Coupling a Set of Stand-Alone Subsystem Simulations

    NASA Technical Reports Server (NTRS)

    Nixon, D. D.

    2001-01-01

    Conventional construction of digital dynamic system simulations often involves collecting differential equations that model each subsystem, arran g them to a standard form, and obtaining their numerical gin solution as a single coupled, total-system simultaneous set. Simulation by numerical coupling of independent stand-alone subsimulations is a fundamentally different approach that is attractive because, among other things, the architecture naturally facilitates high fidelity, broad scope, and discipline independence. Recursive feedback is defined and discussed as a candidate approach to multidiscipline dynamic system simulation by numerical coupling of self-contained, single-discipline subsystem simulations. A satellite motion example containing three subsystems (orbit dynamics, attitude dynamics, and aerodynamics) has been defined and constructed using this approach. Conventional solution methods are used in the subsystem simulations. Distributed and centralized implementations of coupling have been considered. Numerical results are evaluated by direct comparison with a standard total-system, simultaneous-solution approach.

  5. Cyber secure systems approach for NPP digital control systems

    SciTech Connect

    McCreary, T. J.; Hsu, A.

    2006-07-01

    Whether fossil or nuclear power, the chief operations goal is to generate electricity. The heart of most plant operations is the I and C system. With the march towards open architecture, the I and C system is more vulnerable than ever to system security attacks (denial of service, virus attacks and others), thus jeopardizing plant operations. Plant staff must spend large amounts of time and money setting up and monitoring a variety of security strategies to counter the threats and actual attacks to the system. This time and money is a drain on the financial performance of a plant and distracts valuable operations resources from their real goals: product. The pendulum towards complete open architecture may have swung too far. Not all aspects of proprietary hardware and software are necessarily 'bad'. As the aging U.S. fleet of nuclear power plants starts to engage in replacing legacy control systems, and given the on-going (and legitimate) concern about the security of present digital control systems, decisions about how best to approach cyber security are vital to the specification and selection of control system vendors for these upgrades. The authors maintain that utilizing certain resources available in today's digital technology, plant control systems can be configured from the onset to be inherently safe, so that plant staff can concentrate on the operational issues of the plant. The authors postulate the concept of the plant I and C being bounded in a 'Cyber Security Zone' and present a design approach that can alleviate the concern and cost at the plant level of dealing with system security strategies. Present approaches through various IT cyber strategies, commercial software, and even postulated standards from various industry/trade organizations are almost entirely reactive and simply add to cost and complexity. This Cyber Security Zone design demonstrates protection from the four classes of cyber security attacks: 1)Threat from an intruder attempting to

  6. Digital transmitter for data bus communications system

    NASA Technical Reports Server (NTRS)

    Proch, G. E. (Inventor)

    1975-01-01

    An improved digital transmitter for transmitting serial pulse code modulation (pcm) data at high bit rates over a transmission line is disclosed. When not transmitting, the transmitter features a high output impedance which prevents the transmitter from loading the transmission line. The pcm input is supplied to a logic control circuit which produces two discrete logic level signals which are supplied to an amplifier. The amplifier, which is transformer coupled to the output isolation circuitry, converts the discrete logic level signals to two high current level, ground isolated signals in the secondary windings of the coupling transformer. The latter signals are employed as inputs to the isolation circuitry which includes two series transistor pairs operating into a hybrid transformer functioning to isolate the transmitter circuitry from the transmission line.

  7. Feasibility of digitally stained multimodal confocal mosaics to simulate histopathology

    NASA Astrophysics Data System (ADS)

    Gareau, Daniel S.

    2009-05-01

    Fluorescence confocal mosaicing microscopy of tissue biopsies stained with acridine orange has been shown to accurately identify tumors and with an overall sensitivity of 96.6% and specificity of 89.2%. However, fluorescence shows only nuclear detail similar to hematoxylin in histopathology and does not show collagen or cytoplasm, which may provide necessary negative contrast information similar to eosin used in histopathology. Reflectance mode contrast is sensitive to collagen and cytoplasm without staining. To further improve sensitivity and specificity, digitally stained confocal mosaics combine confocal fluorescence and reflectance images in a multimodal pseudo-color image to mimic the appearance of histopathology with hematoxylin and eosin and facilitate the introduction of confocal microscopy into the clinical realm.

  8. Development of a Digital Portfolio System for Preservice Teachers

    ERIC Educational Resources Information Center

    Pardieck, Sherrie Chan; McMullen, David W.

    2005-01-01

    This paper is a report on the development of a digital portfolio system for a teacher education program. The development of the system was based upon a three-year comparative case study of four principals representing rural and urban schools and included pre-kindergarten through 12th grade levels in a Midwestern state. The research generated…

  9. Digital Data Recording System (DDRS) operating and maintenance manual

    NASA Technical Reports Server (NTRS)

    Griffin, C. R.; Jones, J. I.

    1980-01-01

    The digital data recording system (DDRS) was designed, fabricated, tested, and delivered. This unit is the interface between the synthetic aperture radar (SAR) and the recording system. The SAR data are formatted in the DDRS for data processing on the ground.

  10. Development of Boolean calculus and its applications. [digital systems design

    NASA Technical Reports Server (NTRS)

    Tapia, M. A.

    1980-01-01

    The development of Boolean calculus for its application to developing digital system design methodologies that would reduce system complexity, size, cost, speed, power requirements, etc., is discussed. Synthesis procedures for logic circuits are examined particularly asynchronous circuits using clock triggered flip flops.

  11. Optical Disk for Digital Storage and Retrieval Systems.

    ERIC Educational Resources Information Center

    Rose, Denis A.

    1983-01-01

    Availability of low-cost digital optical disks will revolutionize storage and retrieval systems over next decade. Three major factors will effect this change: availability of disks and controllers at low-cost and in plentiful supply; availability of low-cost and better output means for system users; and more flexible, less expensive communication…

  12. Practical Maintenance of Digital Systems: Guidance to Maximize the Benefits of Digital Technology for the Maintenance of Digital Systems and Plant Equipment

    SciTech Connect

    Hill, D; Scarola, K

    2004-10-30

    This report presents detailed guidance for the maintenance and testing of modern digital systems. The guidance provides practical means for plants to take advantage of the increased diagnostic and self-test capabilities of these systems. It helps plants avoid mistakes in design and installation that could lead to increased maintenance burden and decreased system reliability and availability.

  13. Space shuttle orbiter digital data processing system timing sensitivity analysis OFT ascent phase

    NASA Technical Reports Server (NTRS)

    Lagas, J. J.; Peterka, J. J.; Becker, D. A.

    1977-01-01

    Dynamic loads were investigated to provide simulation and analysis of the space shuttle orbiter digital data processing system (DDPS). Segments of the ascent test (OFT) configuration were modeled utilizing the information management system interpretive model (IMSIM) in a computerized simulation modeling of the OFT hardware and software workload. System requirements for simulation of the OFT configuration were defined, and sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and these sensitivity analyses, a test design was developed for adapting, parameterizing, and executing IMSIM, using varying load and stress conditions for model execution. Analyses of the computer simulation runs are documented, including results, conclusions, and recommendations for DDPS improvements.

  14. Systems study for an Integrated Digital-Electric Aircraft (IDEA)

    NASA Technical Reports Server (NTRS)

    Tagge, G. E.; Irish, L. A.; Bailey, A. R.

    1985-01-01

    The results of the Integrated Digital/Electric Aircraft (IDEA) Study are presented. Airplanes with advanced systems were, defined and evaluated, as a means of identifying potential high payoff research tasks. A baseline airplane was defined for comparison, typical of a 1990's airplane with advanced active controls, propulsion, aerodynamics, and structures technology. Trade studies led to definition of an IDEA airplane, with extensive digital systems and electric secondary power distribution. This airplane showed an improvement of 3% in fuel use and 1.8% in DOC relative to the baseline configuration. An alternate configuration, an advanced technology turboprop, was also evaluated, with greater improvement supported by digital electric systems. Recommended research programs were defined for high risk, high payoff areas appropriate for implementation under NASA leadership.

  15. Examination of a Digital FLL System Design for SQUIDs

    NASA Astrophysics Data System (ADS)

    Oyama, Daisuke; Kobayashi, Koichiro; Simizu, Takayuki; Yoshizawa, Masahito; Uchikawa, Yoshinori

    Biomagnetic field measurements in unshielded environment require both large dynamic range and high slew rate. Noise amplitudes at 50Hz and under 10 Hz of significantly more than 1μT are not at all exotic in an industrial or a hospital environment. A digital FLL (D-FLL) system for a SQUID magnetometer has high resolution and large dynamic range of magnetic field. Slew rate of a D-FLL system by using a double-counter is limited by its digital feedback loop. It can increase the slew rate that optimum feedback loop gain is divided into an analog preamplifier and a digital amplifier on a microcontroller. We show design method of their amplifiers. The slew rate of a D-FLL system with optimum amplifiers is 483 Φ0/s , and its noise level is about 50.0fT√Hz@120Hz.

  16. Systems Engineering Simulator (SES) Simulator Planning Guide

    NASA Technical Reports Server (NTRS)

    McFarlane, Michael

    2011-01-01

    The simulation process, milestones and inputs are unknowns to first-time users of the SES. The Simulator Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their engineering personnel in simulation planning and execution. Material covered includes a roadmap of the simulation process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, facility interfaces, and inputs necessary to define scope, cost, and schedule are included as an appendix to the guide.

  17. Detection of simulated microcalcifications in a phantom with digital mammography: effect of pixel size

    PubMed Central

    Suryanarayanan, Sankararaman; Karellas, Andrew; Vedantham, Srinivasan; Sechopoulos, Ioannis; D’Orsi, Carl J

    2008-01-01

    PURPOSE To evaluate the effect of pixel size on the detection of simulated microcalcifications in digital mammography using a phantom. MATERIALS AND METHODS A high-resolution prototype imager with variable pixel size of 39 and 78 μm, and a clinical full-field digital mammography (FFDM) system with pixel size of 100 μm were used. X-ray images of a contrast-detail (CD) phantom were obtained to perform alternative forced choice (AFC) observer experiments. Polymethyl-methacrylate (PMMA) was added to obtain phantom thickness of 45 and 58 mm which are typical breast thickness conditions encountered in mammography. Phantom images were acquired with both systems under nearly identical exposure conditions using an anti-scatter grid. Twelve images were acquired for each phantom thickness and pixel size (total of 72 images) and six observers participated in this study. Observer responses were used to compute the fraction of correctly detected disks. A signal detection model was used to fit the recorded data from which CD characteristics were obtained. Repeated-measures analyses using mixed effects linear models were performed for each of the 6 observers. All statistical tests were 2-sided and unadjusted for multiple comparisons. A P value of 0.05 or less was considered to indicate statistical significance. RESULTS Statistical analysis indicated significantly better CD characteristics with 39 and 78 μm pixel sizes compared to the 100 μm pixel for all disk diameters and phantom thickness conditions (p<0.001). Increase in phantom thickness degraded CD characteristics irrespective of pixel size (p<0.001). CONCLUSION Based on the conditions of this study, reducing pixel size below 100 μm with low imaging system noise enhances the visual perception of small objects that correspond to typical microcalcification size. PMID:17522348

  18. Implementation of the Pegasus Digital Plasma Control System

    NASA Astrophysics Data System (ADS)

    Bongard, M. W.; Battaglia, D. J.; Fonck, R. J.; Garstka, G. D.; Lewicki, B. T.; Squires, B. J.; Unterberg, E. A.

    2006-10-01

    A primary goal of the Phase II Pegasus ST experiment is to achieve high normalized current IN at low toroidal field. Active feedback control is required to adequately guide the plasma evolution and attain stable high IN operation at near-unity aspect ratio. To that end, the control of our programmable power supplies is transitioning to a digital Plasma Control System (PCS) based on the software framework currently in use on DIII-D. This architecture allows for implementation of arbitrary control algorithms. A near-term goal is to provide feedback control of R(t), Z(t), and Ip(t) via in-shot analysis of magnetics measurements and adjustment to appropriate power supply demands. New hardware and software has been developed to support the PCS, including improved signal processing electronics and the creation of a cross-platform MDSplus compatibility layer for the LabVIEW 8.0 and Igor Pro programming environments. Control algorithm development is assisted by coupling improved power supply, vacuum vessel, and rigid plasma displacement response models into a comprehensive Pegasus simserver simulator.

  19. A Digitalized Gyroscope System Based on a Modified Adaptive Control Method.

    PubMed

    Xia, Dunzhu; Hu, Yiwei; Ni, Peizhen

    2016-03-04

    In this work we investigate the possibility of applying the adaptive control algorithm to Micro-Electro-Mechanical System (MEMS) gyroscopes. Through comparing the gyroscope working conditions with the reference model, the adaptive control method can provide online estimation of the key parameters and the proper control strategy for the system. The digital second-order oscillators in the reference model are substituted for two phase locked loops (PLLs) to achieve a more steady amplitude and frequency control. The adaptive law is modified to satisfy the condition of unequal coupling stiffness and coupling damping coefficient. The rotation mode of the gyroscope system is considered in our work and a rotation elimination section is added to the digitalized system. Before implementing the algorithm in the hardware platform, different simulations are conducted to ensure the algorithm can meet the requirement of the angular rate sensor, and some of the key adaptive law coefficients are optimized. The coupling components are detected and suppressed respectively and Lyapunov criterion is applied to prove the stability of the system. The modified adaptive control algorithm is verified in a set of digitalized gyroscope system, the control system is realized in digital domain, with the application of Field Programmable Gate Array (FPGA). Key structure parameters are measured and compared with the estimation results, which validated that the algorithm is feasible in the setup. Extra gyroscopes are used in repeated experiments to prove the commonality of the algorithm.

  20. A Digitalized Gyroscope System Based on a Modified Adaptive Control Method.

    PubMed

    Xia, Dunzhu; Hu, Yiwei; Ni, Peizhen

    2016-01-01

    In this work we investigate the possibility of applying the adaptive control algorithm to Micro-Electro-Mechanical System (MEMS) gyroscopes. Through comparing the gyroscope working conditions with the reference model, the adaptive control method can provide online estimation of the key parameters and the proper control strategy for the system. The digital second-order oscillators in the reference model are substituted for two phase locked loops (PLLs) to achieve a more steady amplitude and frequency control. The adaptive law is modified to satisfy the condition of unequal coupling stiffness and coupling damping coefficient. The rotation mode of the gyroscope system is considered in our work and a rotation elimination section is added to the digitalized system. Before implementing the algorithm in the hardware platform, different simulations are conducted to ensure the algorithm can meet the requirement of the angular rate sensor, and some of the key adaptive law coefficients are optimized. The coupling components are detected and suppressed respectively and Lyapunov criterion is applied to prove the stability of the system. The modified adaptive control algorithm is verified in a set of digitalized gyroscope system, the control system is realized in digital domain, with the application of Field Programmable Gate Array (FPGA). Key structure parameters are measured and compared with the estimation results, which validated that the algorithm is feasible in the setup. Extra gyroscopes are used in repeated experiments to prove the commonality of the algorithm. PMID:26959019

  1. A Digitalized Gyroscope System Based on a Modified Adaptive Control Method

    PubMed Central

    Xia, Dunzhu; Hu, Yiwei; Ni, Peizhen

    2016-01-01

    In this work we investigate the possibility of applying the adaptive control algorithm to Micro-Electro-Mechanical System (MEMS) gyroscopes. Through comparing the gyroscope working conditions with the reference model, the adaptive control method can provide online estimation of the key parameters and the proper control strategy for the system. The digital second-order oscillators in the reference model are substituted for two phase locked loops (PLLs) to achieve a more steady amplitude and frequency control. The adaptive law is modified to satisfy the condition of unequal coupling stiffness and coupling damping coefficient. The rotation mode of the gyroscope system is considered in our work and a rotation elimination section is added to the digitalized system. Before implementing the algorithm in the hardware platform, different simulations are conducted to ensure the algorithm can meet the requirement of the angular rate sensor, and some of the key adaptive law coefficients are optimized. The coupling components are detected and suppressed respectively and Lyapunov criterion is applied to prove the stability of the system. The modified adaptive control algorithm is verified in a set of digitalized gyroscope system, the control system is realized in digital domain, with the application of Field Programmable Gate Array (FPGA). Key structure parameters are measured and compared with the estimation results, which validated that the algorithm is feasible in the setup. Extra gyroscopes are used in repeated experiments to prove the commonality of the algorithm. PMID:26959019

  2. Carrier: Interference ratios for frequency sharing between satellite systems transmitting frequency modulated and digital television signals

    NASA Technical Reports Server (NTRS)

    Barnes, S. P.

    1979-01-01

    Results are presented of subjective and quantitative tests describing the results of interference to a particular digital television system from a frequency modulated (FM) television system, and for interference to an FM television system from a digital television system.

  3. AFTI/F-16 digital flight control system experience

    NASA Technical Reports Server (NTRS)

    Mackall, D. A.

    1984-01-01

    The Advanced Flighter Technology Integration (AFTI) F-16 program is investigating the integration of emerging technologies into an advanced fighter aircraft. The three major technologies involved are the triplex digital flight control system; decoupled aircraft flight control; and integration of avionics, pilot displays, and flight control. In addition to investigating improvements in fighter performance, the AFTI/F-16 program provides a look at generic problems facing highly integrated, flight-crucial digital controls. An overview of the AFTI/F-16 systems is followed by a summary of flight test experience and recommendations.

  4. The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis

    SciTech Connect

    Shaheen, Eman De Keyzer, Frederik; Bosmans, Hilde; Ongeval, Chantal Van; Dance, David R.; Young, Kenneth C.

    2014-08-15

    Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly

  5. Digital Audio Radio Broadcast Systems Laboratory Testing Nearly Complete

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Radio history continues to be made at the NASA Lewis Research Center with the completion of phase one of the digital audio radio (DAR) testing conducted by the Consumer Electronics Group of the Electronic Industries Association. This satellite, satellite/terrestrial, and terrestrial digital technology will open up new audio broadcasting opportunities both domestically and worldwide. It will significantly improve the current quality of amplitude-modulated/frequency-modulated (AM/FM) radio with a new digitally modulated radio signal and will introduce true compact-disc-quality (CD-quality) sound for the first time. Lewis is hosting the laboratory testing of seven proposed digital audio radio systems and modes. Two of the proposed systems operate in two modes each, making a total of nine systems being tested. The nine systems are divided into the following types of transmission: in-band on-channel (IBOC), in-band adjacent-channel (IBAC), and new bands. The laboratory testing was conducted by the Consumer Electronics Group of the Electronic Industries Association. Subjective assessments of the audio recordings for each of the nine systems was conducted by the Communications Research Center in Ottawa, Canada, under contract to the Electronic Industries Association. The Communications Research Center has the only CCIR-qualified (Consultative Committee for International Radio) audio testing facility in North America. The main goals of the U.S. testing process are to (1) provide technical data to the Federal Communication Commission (FCC) so that it can establish a standard for digital audio receivers and transmitters and (2) provide the receiver and transmitter industries with the proper standards upon which to build their equipment. In addition, the data will be forwarded to the International Telecommunications Union to help in the establishment of international standards for digital audio receivers and transmitters, thus allowing U.S. manufacturers to compete in the

  6. Digital data registration and differencing compression system

    NASA Technical Reports Server (NTRS)

    Ransford, Gary A. (Inventor); Cambridge, Vivien J. (Inventor)

    1990-01-01

    A process is disclosed for x ray registration and differencing which results in more efficient compression. Differencing of registered modeled subject image with a modeled reference image forms a differenced image for compression with conventional compression algorithms. Obtention of a modeled reference image includes modeling a relatively unrelated standard reference image upon a three-dimensional model, which three-dimensional model is also used to model the subject image for obtaining the modeled subject image. The registration process of the modeled subject image and modeled reference image translationally correlates such modeled images for resulting correlation thereof in spatial and spectral dimensions. Prior to compression, a portion of the image falling outside a designated area of interest may be eliminated, for subsequent replenishment with a standard reference image. The compressed differenced image may be subsequently transmitted and/or stored, for subsequent decompression and addition to a standard reference image so as to form a reconstituted or approximated subject image at either a remote location and/or at a later moment in time. Overall effective compression ratios of 100:1 are possible for thoracic x ray digital images.

  7. Digital Data Registration and Differencing Compression System

    NASA Technical Reports Server (NTRS)

    Ransford, Gary A. (Inventor); Cambridge, Vivien J. (Inventor)

    1996-01-01

    A process for X-ray registration and differencing results in more efficient compression. Differencing of registered modeled subject image with a modeled reference image forms a differenced image for compression with conventional compression algorithms. Obtention of a modeled reference image includes modeling a relatively unrelated standard reference image upon a three-dimensional model, which three-dimensional model is also used to model the subject image for obtaining the modeled subject image. The registration process of the modeled subject image and modeled reference image translationally correlates such modeled images for resulting correlation thereof in spatial and spectral dimensions. Prior to compression, a portion of the image falling outside a designated area of interest may be eliminated, for subsequent replenishment with a standard reference image. The compressed differenced image may be subsequently transmitted and/or stored, for subsequent decompression and addition to a standard reference image so as to form a reconstituted or approximated subject image at either a remote location and/or at a later moment in time. Overall effective compression ratios of 100:1 are possible for thoracic X-ray digital images.

  8. Digital data registration and differencing compression system

    NASA Technical Reports Server (NTRS)

    Ransford, Gary A. (Inventor); Cambridge, Vivien J. (Inventor)

    1992-01-01

    A process for x ray registration and differencing results in more efficient compression is discussed. Differencing of registered modeled subject image with a modeled reference image forms a differential image for compression with conventional compression algorithms. Obtention of a modeled reference image includes modeling a relatively unrelated standard reference image upon a three dimensional model, which three dimensional model is also used to model the subject image for obtaining the modeled subject image. The registration process of the modeled subject image and modeled reference image translationally correlates such modeled images for resulting correlation thereof in spatial and spectral dimensions. Prior to compression, a portion of the image falling outside a designated area of interest may be eliminated, for subsequent replenishment with a standard reference image. The compressed differenced image may be subsequently transmitted and/or stored, for subsequent decompression and addition to a standard reference image so as to form a reconstituted or approximated subject image at either remote location and/or at a later moment in time. Overall effective compression ratios of 100:1 are possible for thoracic x ray digital images.

  9. Digital video data archive for crash test systems

    NASA Astrophysics Data System (ADS)

    Hock, Christian

    1997-04-01

    Kayser-Threde has been invested many years in developing technology used in crash testing, data acquisition and test data archiving. Since 1976 the department Measurement Systems has ben supplying European car manufacturers and test houses with ruggedized on-board data acquisition units for use in safety tests according to SAE J 211. The integration of on-board high-speed digital cameras has completed the data acquisition unit. Stationary high-speed cameras for external observation are also included in the controlling and acquisition system of the crash test site. The occupation of Kayser-Threde's department High Speed Data Systems is the design and integration of computerized data flow systems under real-time conditions. The special circumstances of crash test applications are taken into account for data acquisition, mass storage and data distribution. The two fundamental components of the video data archiving systems are, firstly, the recording of digital high-speed images as well as digital test data and secondly, an organized filing in mass archiving systems with the capability of near on-line access. In combination with sophisticated and reliable hardware components Kayser-Threde is able to deliver high performance digital data archives with storage capacities of up to 2600 TeraBytes.

  10. A digital communications system for manned spaceflight applications.

    NASA Technical Reports Server (NTRS)

    Batson, B. H.; Moorehead, R. W.

    1973-01-01

    A highly efficient, all-digital communications signal design employing convolutional coding and PN spectrum spreading is described for two-way transmission of voice and data between a manned spacecraft and ground. Variable-slope delta modulation is selected for analog/digital conversion of the voice signal, and a convolutional decoder utilizing the Viterbi decoding algorithm is selected for use at each receiving terminal. A PN spread spectrum technique is implemented to protect against multipath effects and to reduce the energy density (per unit bandwidth) impinging on the earth's surface to a value within the guidelines adopted by international agreement. Performance predictions are presented for transmission via a TDRS (tracking and data relay satellite) system and for direct transmission between the spacecraft and earth. Hardware estimates are provided for a flight-qualified communications system employing the coded digital signal design.

  11. NASA develops new digital flight control system

    NASA Technical Reports Server (NTRS)

    Mewhinney, Michael

    1994-01-01

    This news release reports on the development and testing of a new integrated flight and propulsion automated control system that aerospace engineers at NASA's Ames Research Center have been working on. The system is being tested in the V/STOL (Vertical/Short Takeoff and Landing) Systems Research Aircraft (VSRA).

  12. Radiologist's clinical information review workstation interfaced with digital dictation system.

    PubMed

    McEnery, K W; Suitor, C T; Hildebrand, S; Downs, R L

    2000-05-01

    Efficient access to information systems integrated into the radiologist's interpretation workflow will result in a more informed radiologist, with an enhanced capability to render an accurate interpretation. We describe our implementation of radStation, a radiologist's clinical information review workstation that combines a digital dictation station with a clinical information display. radStation uses client software distributed to the radiologist's workstation and central server software, both running Windows NT (Microsoft, Redmond, WA). The client system has integrated digital dictation software. The bar-code microphone (Boomerang, Dictaphone Corp, Stratford, CT) also serves as a computer input device forwarding the procedure's accession number to the server software. This initiates multiple queries to available legacy databases, including the radiology information system (RIS), laboratory information system, clinic notes, hospital discharge, and operative report system. The three-tier architecture then returns the clinical results to the radStation client for display. At the conclusion of the dictation, the digital voice file is transferred to the dictation server and the client notifies the RIS to update the examination status. The system is efficient in its information retrieval, with queries displayed in about 1 second. The radStation client requires less than 5 minutes of radiologist training in its operation, given that its control interface integrates with the well-learned dictation process. The telephone-based dictation system, which this new system replaced, remains available as a back-up system in the event of an unexpected digital dictation system failure. This system is well accepted and valued by the radiologists. The system interface is quickly mastered. The system does not interrupt dictation workflow with the display of all information initiated with examination bar-coding. This system's features could become an accepted model as a standard tool

  13. Environmental fog/rain visual display system for aircraft simulators

    NASA Technical Reports Server (NTRS)

    Chase, W. D. (Inventor)

    1982-01-01

    An environmental fog/rain visual display system for aircraft simulators is described. The electronic elements of the system include a real time digital computer, a caligraphic color display which simulates landing lights of selective intensity, and a color television camera for producing a moving color display of the airport runway as depicted on a model terrain board. The mechanical simulation elements of the system include an environmental chamber which can produce natural fog, nonhomogeneous fog, rain and fog combined, or rain only. A pilot looking through the aircraft wind screen will look through the fog and/or rain generated in the environmental chamber onto a viewing screen with the simulated color image of the airport runway thereon, and observe a very real simulation of actual conditions of a runway as it would appear through actual fog and/or rain.

  14. Picture archiving and communication systems in digital cytology.

    PubMed

    Morelli, Sandra; Grigioni, Mauro; Giovagnoli, Maria Rosaria; Balzano, Simone; Giansanti, Daniele

    2010-01-01

    The paper describes a fundamental feature of digital cytology relevant to the implementation of the technology in the hospital net services: the electronic recording of the virtual slides (VS) in the hospital information system (HIS) through a picture archiving and communication system (PACS). Starting from the digital cytology (D-CYT) state of art and considering the most important products in the field, particular attention has been devoted in this review to the comparison with the digital radiology (D-RAD). Two main indications emerged from the study: 1. there is not a standard in the digital files relevant to the virtual slides in D-CYT, while in D-RAD the standard digital imaging and communications in medicine (DICOM), introduced by the National Electrical Manufacturers Association (NEMA), has been adopted from several years; 2. the PACS in D-CYT are not standardized from manufacturers. The study makes a proposal of a useful software architecture to improve the PACS integration for D-CYT applications, with potentialities in the HIS.

  15. Shape determination of microcalcifications in simulated digital mammography images with varying pixel size

    NASA Astrophysics Data System (ADS)

    Ruschin, Mark; Bath, Magnus; Hemdal, Bengt; Tingberg, Anders

    2005-04-01

    The purpose of this work was to study how the pixel size of digital detectors can affect shape determination of microcalcifications in mammography. Screen-film mammograms containing microcalcifications clinically proven to be indicative of malignancy were digitised at 100 lines/mm using a high-resolution Tango drum scanner. Forty microcalcifications were selected to cover an appropriate range of sizes, shapes and contrasts typically found of malignant cases. Based on the measured MTF and NPS of the combined screen-film and scanner system, these digitised images were filtered to simulate images acquired with a square sampling pixel size of 10 μm x 10 μm and a fill factor of one. To simulate images acquired with larger pixel sizes, these finely sampled images were re-binned to yield a range of effective pixel sizes from 20 μm up to 140 μm. An alternative forced-choice (AFC) observer experiment was conducted with eleven observers for this set of digitised microcalcifications to determine how pixel size affects the ability to discriminate shape. It was found that observer score increased with decreasing pixel size down to 60 μm (p<0.01), at which point no significant advantage was obtained by using smaller pixel sizes due to the excessive relative noise-per-pixel. The relative gain in shape discrimination ability at smaller pixel sizes was larger for microcalcifications that were smaller than 500 μm and circular.

  16. Image Chain Analysis For Digital Image Rectification System

    NASA Astrophysics Data System (ADS)

    Arguello, Roger J.

    1981-07-01

    An image chain analysis, utilizing a comprehensive computer program, has been gen-erated for the key elements of a digital image rectification system. System block dia-grams and analyses for three system configurations employing film scanner input have been formulated with a parametric specification of pertinent element modulation transfer functions and input film scene spectra. The major elements of the system for this analy-sis include a high-resolution, high-speed charge-coupled device film scanner, three candidate digital resampling option algorithms (i.e., nearest neighbor, bilinear inter-polation and cubic convolution methods), and two candidate printer reconstructor implemen-tations (solid-state light-emitting diode printer and laser beam recorder). Suitable metrics for the digital rectification system, incorporating the effects of interpolation and resolution error, were established, and the image chain analysis program was used to perform a quantitative comparison of the three resampling options with the two candi-date printer reconstructor implementations. The nearest neighbor digital resampling function is found to be a good compromise choice when cascaded with either a light-emit-ting diode printer or laser beam recorder. The resulting composite intensity point spread functions, including resampling, and both types of reconstruction are bilinear and quadratic, respectively.

  17. ISSUES ASSOCIATED WITH PROBABILISTIC FAILURE MODELING OF DIGITAL SYSTEMS

    SciTech Connect

    CHU,T.L.; MARTINEZ-GURIDI,G.; LEHNER,J.; OVERLAND,D.

    2004-09-19

    The current U.S. Nuclear Regulatory Commission (NRC) licensing process of instrumentation and control (I&C) systems is based on deterministic requirements, e.g., single failure criteria, and defense in depth and diversity. Probabilistic considerations can be used as supplements to the deterministic process. The National Research Council has recommended development of methods for estimating failure probabilities of digital systems, including commercial off-the-shelf (COTS) equipment, for use in probabilistic risk assessment (PRA). NRC staff has developed informal qualitative and quantitative requirements for PRA modeling of digital systems. Brookhaven National Laboratory (BNL) has performed a review of the-state-of-the-art of the methods and tools that can potentially be used to model digital systems. The objectives of this paper are to summarize the review, discuss the issues associated with probabilistic modeling of digital systems, and identify potential areas of research that would enhance the state of the art toward a satisfactory modeling method that could be integrated with a typical probabilistic risk assessment.

  18. Simulations of Solar AO Systems

    NASA Astrophysics Data System (ADS)

    Sridharan, R.; Bayanna, A. Raja; Venkatakrishnan, P.

    In this paper, first we compare the two kinds of algorithms that are being used in solar AO systems to sense a distorted wave-front through simulations. Then, we comment on the various issues related to solar AO systems and describe solar features that can be studied using AO as a tool. Then we briefly describe the laboratory model of AO that is being built at the Udaipur Solar Observatory (USO), India.

  19. Stochastic BER estimation for coherent QPSK transmission systems with digital carrier phase recovery.

    PubMed

    Zhang, Fan; Gao, Yan; Luo, Yazhi; Chen, Zhangyuan; Xu, Anshi

    2010-04-26

    We propose a stochastic bit error ratio estimation approach based on a statistical analysis of the retrieved signal phase for coherent optical QPSK systems with digital carrier phase recovery. A family of the generalized exponential function is applied to fit the probability density function of the signal samples. The method provides reasonable performance estimation in presence of both linear and nonlinear transmission impairments while reduces the computational intensity greatly compared to Monte Carlo simulation.

  20. Experience with synchronous and asynchronous digital control systems

    NASA Technical Reports Server (NTRS)

    Regenie, V. A.; Chacon, C. V.; Lock, W. P.

    1986-01-01

    Flight control systems have undergone a revolution since the days of simple mechanical linkages; presently the most advanced systems are full-authority, full-time digital systems controlling unstable aircraft. With the use of advanced control systems, the aerodynamic design can incorporate features that allow greater performance and fuel savings, as can be seen on the new Airbus design and advanced tactical fighter concepts. These advanced aircraft will be and are relying on the flight control system to provide the stability and handling qualities required for safe flight and to allow the pilot to control the aircraft. Various design philosophies have been proposed and followed to investigate system architectures for these advanced flight control systems. One major area of discussion is whether a multichannel digital control system should be synchronous or asynchronous. This paper addressed the flight experience at the Dryden Flight Research Facility of NASA's Ames Research Center with both synchronous and asynchronous digital flight control systems. Four different flight control systems are evaluated against criteria such as software reliability, cost increases, and schedule delays.

  1. NSTX-U Digital Coil Protection System Software Detailed Design

    SciTech Connect

    2014-06-01

    The National Spherical Torus Experiment (NSTX) currently uses a collection of analog signal processing solutions for coil protection. Part of the NSTX Upgrade (NSTX-U) entails replacing these analog systems with a software solution running on a conventional computing platform. The new Digital Coil Protection System (DCPS) will replace the old systems entirely, while also providing an extensible framework that allows adding new functionality as desired.

  2. Aided targeting system simulation evaluation

    NASA Technical Reports Server (NTRS)

    Demaio, Joe; Becker, Curtis

    1994-01-01

    Simulation research was conducted at the Crew Station Research and Development Facility on the effectiveness and ease of use of three targeting systems. A manual system required the aviator to scan a target array area with a simulated second generation forward looking infrared (FLIR) sensor, locate and categorize targets, and construct a target hand-off list. The interface between the aviator and the system was like that of an advanced scout helicopter (manual mode). Two aided systems detected and categorized targets automatically. One system used only the FLIR sensor and the second used FLIR fused with Longbow radar. The interface for both was like that of an advanced scout helicopter aided mode. Exposure time while performing the task was reduced substantially with the aided systems, with no loss of target hand-off list accuracy. The fused sensor system showed lower time to construct the target hand-off list and a slightly lower false alarm rate than the other systems. A number of issues regarding system sensitivity and criterion, and operator interface design are discussed.

  3. Comparative study of a wireless digital system and 2 PSP digital systems on proximal caries detection and pixel values.

    PubMed

    dos Anjos Pontual, Andrea; de Melo, Daniela Pita; Pontual, Maria Luiza dos Anjos; de Almeida, Solange Maria; Haiter-Neto, Francisco

    2013-01-01

    This study compared the radiographic image quality of 2 photostimulable phosphor (PSP) plate systems with a radiographic system against a complementary metal oxide silicon (CMOS) system. Using the 3 digital systems, 160 approximal surfaces were radiographed under standardized conditions. Using a 5-point scale, 6 observers scored the resulting images for the presence of caries. The presence of caries was validated histologically, and the image receptors were evaluated using receiver operating characteristic curve analysis. The digital systems were used to take radiographs of an aluminum step wedge for objective analysis with pixel density measurements. The mean pixel values were analyzed statistically using the Kruskal-Wallis test and Dunn multiple comparison test (P < 0.01). The performance of the new CMOS system was comparable to the PSP plate systems and radiographic film.

  4. The digital compensation technology system for automotive pressure sensor

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Li, Quanling; Lu, Yi; Luo, Zai

    2010-12-01

    Piezoresistive pressure sensor be made of semiconductor silicon based on Piezoresistive phenomenon, has many characteristics. But since the temperature effect of semiconductor, the performance of silicon sensor is also changed by temperature, and the pressure sensor without temperature drift can not be produced at present. This paper briefly describe the principles of sensors, the function of pressure sensor and the various types of compensation method, design the detailed digital compensation program for automotive pressure sensor. Simulation-Digital mixed signal conditioning is used in this dissertation, adopt signal conditioning chip MAX1452. AVR singlechip ATMEGA128 and other apparatus; fulfill the design of digital pressure sensor hardware circuit and singlechip hardware circuit; simultaneously design the singlechip software; Digital pressure sensor hardware circuit is used to implementing the correction and compensation of sensor; singlechip hardware circuit is used to implementing to controll the correction and compensation of pressure sensor; singlechip software is used to implementing to fulfill compensation arithmetic. In the end, it implement to measure the output of sensor, and contrast to the data of non-compensation, the outcome indicates that the compensation precision of compensated sensor output is obviously better than non-compensation sensor, not only improving the compensation precision but also increasing the stabilization of pressure sensor.

  5. The digital compensation technology system for automotive pressure sensor

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Li, Quanling; Lu, Yi; Luo, Zai

    2011-05-01

    Piezoresistive pressure sensor be made of semiconductor silicon based on Piezoresistive phenomenon, has many characteristics. But since the temperature effect of semiconductor, the performance of silicon sensor is also changed by temperature, and the pressure sensor without temperature drift can not be produced at present. This paper briefly describe the principles of sensors, the function of pressure sensor and the various types of compensation method, design the detailed digital compensation program for automotive pressure sensor. Simulation-Digital mixed signal conditioning is used in this dissertation, adopt signal conditioning chip MAX1452. AVR singlechip ATMEGA128 and other apparatus; fulfill the design of digital pressure sensor hardware circuit and singlechip hardware circuit; simultaneously design the singlechip software; Digital pressure sensor hardware circuit is used to implementing the correction and compensation of sensor; singlechip hardware circuit is used to implementing to controll the correction and compensation of pressure sensor; singlechip software is used to implementing to fulfill compensation arithmetic. In the end, it implement to measure the output of sensor, and contrast to the data of non-compensation, the outcome indicates that the compensation precision of compensated sensor output is obviously better than non-compensation sensor, not only improving the compensation precision but also increasing the stabilization of pressure sensor.

  6. Digital Libraries: The Next Generation in File System Technology.

    ERIC Educational Resources Information Center

    Bowman, Mic; Camargo, Bill

    1998-01-01

    Examines file sharing within corporations that use wide-area, distributed file systems. Applications and user interactions strongly suggest that the addition of services typically associated with digital libraries (content-based file location, strongly typed objects, representation of complex relationships between documents, and extrinsic…

  7. Evaluating Usability in a Distance Digital Systems Laboratory Class

    ERIC Educational Resources Information Center

    Kostaras, N.; Xenos, M.; Skodras, A. N.

    2011-01-01

    This paper presents the usability evaluation of a digital systems laboratory class offered to distance-learning students. It details the way in which students can participate remotely in such a laboratory, the methodology employed in the usability assessment of the laboratory infrastructure (hardware and software), and also outlines the main…

  8. Current Strategic Business Plan for the Implementation of Digital Systems.

    ERIC Educational Resources Information Center

    Library of Congress, Washington, DC. National Library Service for the Blind and Physically Handicapped.

    This document presents a current strategic business plan for the implementation of digital systems and services for the free national library program operated by the National Library Service for the Blind and Physically Handicapped, Library of Congress, its network of cooperating regional and local libraries, and the United States Postal Service.…

  9. Three-Dimensional Extension of a Digital Library Service System

    ERIC Educational Resources Information Center

    Xiao, Long

    2010-01-01

    Purpose: The paper aims to provide an overall methodology and case study for the innovation and extension of a digital library, especially the service system. Design/methodology/approach: Based on the three-dimensional structure theory of the information service industry, this paper combines a comprehensive analysis with the practical experiences…

  10. IIM Digital Library System: Consortia-Based Approach.

    ERIC Educational Resources Information Center

    Pandian, M. Paul; Jambhekar, Ashok; Karisiddappa, C. R.

    2002-01-01

    Provides a framework for the design and development of an intranet model based on a consortia approach by the Indian Institutes of Management (IIM) digital library system that will facilitate information access and use by providing a single Web-enabled window to users to their own resources and to sources in other participating institutions.…

  11. Digital system provides superregulation of nanosecond amplifier-discriminator circuit

    NASA Technical Reports Server (NTRS)

    Forges, K. G.

    1966-01-01

    Feedback system employing a digital logic comparator to detect and correct amplifier drift provides stable gain characteristics for nanosecond amplifiers used in counting applications. Additional anticoincidence logic enables application of the regulation circuit to the amplifier and discriminator while they are mounted in an operable circuit.

  12. Numerical Propulsion System Simulation Architecture

    NASA Technical Reports Server (NTRS)

    Naiman, Cynthia G.

    2004-01-01

    The Numerical Propulsion System Simulation (NPSS) is a framework for performing analysis of complex systems. Because the NPSS was developed using the object-oriented paradigm, the resulting architecture is an extensible and flexible framework that is currently being used by a diverse set of participants in government, academia, and the aerospace industry. NPSS is being used by over 15 different institutions to support rockets, hypersonics, power and propulsion, fuel cells, ground based power, and aerospace. Full system-level simulations as well as subsystems may be modeled using NPSS. The NPSS architecture enables the coupling of analyses at various levels of detail, which is called numerical zooming. The middleware used to enable zooming and distributed simulations is the Common Object Request Broker Architecture (CORBA). The NPSS Developer's Kit offers tools for the developer to generate CORBA-based components and wrap codes. The Developer's Kit enables distributed multi-fidelity and multi-discipline simulations, preserves proprietary and legacy codes, and facilitates addition of customized codes. The platforms supported are PC, Linux, HP, Sun, and SGI.

  13. F-15 digital electronic engine control system description

    NASA Technical Reports Server (NTRS)

    Myers, L. P.

    1984-01-01

    A digital electronic engine control (DEEC) was developed for use on the F100-PW-100 turbofan engine. This control system has full authority control, capable of moving all the controlled variables over their full ranges. The digital computational electronics and fault detection and accomodation logic maintains safe engine operation. A hydromechanical backup control (BUC) is an integral part of the fuel metering unit and provides gas generator control at a reduced performance level in the event of an electronics failure. The DEEC's features, hardware, and major logic diagrams are described.

  14. An intelligent simulation training system

    NASA Technical Reports Server (NTRS)

    Biegel, John E.

    1990-01-01

    The Department of Industrial Engineering at the University of Central Florida, Embry-Riddle Aeronautical University and General Electric (SCSD) have been funded by the State of Florida to build an Intelligent Simulation Training System. The objective was and is to make the system generic except for the domain expertise. Researchers accomplished this objective in their prototype. The system is modularized and therefore it is easy to make any corrections, expansions or adaptations. The funding by the state of Florida has exceeded $3 million over the past three years and through the 1990 fiscal year. UCF has expended in excess of 15 work years on the project. The project effort has been broken into three major tasks. General Electric provides the simulation. Embry-Riddle Aeronautical University provides the domain expertise. The University of Central Florida has constructed the generic part of the system which is comprised of several modules that perform the tutoring, evaluation, communication, status, etc. The generic parts of the Intelligent Simulation Training Systems (ISTS) are described.

  15. Digitized system for the inspection of steel pipes

    NASA Astrophysics Data System (ADS)

    Comuzzi, Daniel; Monti, Fernando; Nicolini, Alberto; Stickar, Pablo

    2000-05-01

    We present an industrial software system named Cerbero, the main goal of which is to take advantage of the superior capabilities of digital signal processing techniques. Cerbero collects the signals generated by the transducers (coils), digitalizes them, and performs temporal and spectral analysis in order to identify defects in the magnetic flux leakage (MFL) inspection of seamless steel pipes. Faulty operating conditions are also identified. A friendly graphic user interface allows the users to tune the system to inspect the products in agreement with the clients' specifications. Currently, the system has been implemented in five units at the Siderca manufacturing plant, three of them aimed at the detection of longitudinal cracks, and two used for transverse cracks. In this paper we describe how the system was conceived, designed, and implemented. The system opens new challenges in signal processing applied to automated manufacturing that are also discussed.

  16. Self-Timed Digital System Design

    NASA Technical Reports Server (NTRS)

    Walker, Alvernon

    2001-01-01

    A timing and control strategy that can be used to realize synchronous systems with a level of performance that approaches that of asynchronous circuits or systems was developed in this work. This approach is based upon a single-phase synchronous circuit/system architecture with a variable period clock. The handshaking signals required for asynchronous self-timed circuits are not needed. Dynamic power supply current monitoring is used to generate the timing information, that is comparable to the completion signal found in self-timed circuits; this timing information is used to modify the circuit clock period.

  17. Singular perturbations and time scales in the design of digital flight control systems

    NASA Technical Reports Server (NTRS)

    Naidu, Desineni S.; Price, Douglas B.

    1988-01-01

    The results are presented of application of the methodology of Singular Perturbations and Time Scales (SPATS) to the control of digital flight systems. A block diagonalization method is described to decouple a full order, two time (slow and fast) scale, discrete control system into reduced order slow and fast subsystems. Basic properties and numerical aspects of the method are discussed. A composite, closed-loop, suboptimal control system is constructed as the sum of the slow and fast optimal feedback controls. The application of this technique to an aircraft model shows close agreement between the exact solutions and the decoupled (or composite) solutions. The main advantage of the method is the considerable reduction in the overall computational requirements for the evaluation of optimal guidance and control laws. The significance of the results is that it can be used for real time, onboard simulation. A brief survey is also presented of digital flight systems.

  18. Preoperative Planning of Orthopedic Procedures using Digitalized Software Systems.

    PubMed

    Steinberg, Ely L; Segev, Eitan; Drexler, Michael; Ben-Tov, Tomer; Nimrod, Snir

    2016-06-01

    The progression from standard celluloid films to digitalized technology led to the development of new software programs to fulfill the needs of preoperative planning. We describe here preoperative digitalized programs and the variety of conditions for which those programs can be used to facilitate preparation for surgery. A PubMed search using the keywords "digitalized software programs," "preoperative planning" and "total joint arthroplasty" was performed for all studies regarding preoperative planning of orthopedic procedures that were published from 1989 to 2014 in English. Digitalized software programs are enabled to import and export all picture archiving communication system (PACS) files (i.e., X-rays, computerized tomograms, magnetic resonance images) from either the local working station or from any remote PACS. Two-dimension (2D) and 3D CT scans were found to be reliable tools with a high preoperative predicting accuracy for implants. The short learning curve, user-friendly features, accurate prediction of implant size, decreased implant stocks and low-cost maintenance makes digitalized software programs an attractive tool in preoperative planning of total joint replacement, fracture fixation, limb deformity repair and pediatric skeletal disorders.

  19. Preoperative Planning of Orthopedic Procedures using Digitalized Software Systems.

    PubMed

    Steinberg, Ely L; Segev, Eitan; Drexler, Michael; Ben-Tov, Tomer; Nimrod, Snir

    2016-06-01

    The progression from standard celluloid films to digitalized technology led to the development of new software programs to fulfill the needs of preoperative planning. We describe here preoperative digitalized programs and the variety of conditions for which those programs can be used to facilitate preparation for surgery. A PubMed search using the keywords "digitalized software programs," "preoperative planning" and "total joint arthroplasty" was performed for all studies regarding preoperative planning of orthopedic procedures that were published from 1989 to 2014 in English. Digitalized software programs are enabled to import and export all picture archiving communication system (PACS) files (i.e., X-rays, computerized tomograms, magnetic resonance images) from either the local working station or from any remote PACS. Two-dimension (2D) and 3D CT scans were found to be reliable tools with a high preoperative predicting accuracy for implants. The short learning curve, user-friendly features, accurate prediction of implant size, decreased implant stocks and low-cost maintenance makes digitalized software programs an attractive tool in preoperative planning of total joint replacement, fracture fixation, limb deformity repair and pediatric skeletal disorders. PMID:27468530

  20. Resource requirements for digital computations on electrooptical systems.

    PubMed

    Eshaghian, M M; Panda, D K; Kumar, V K

    1991-03-10

    In this paper we study the resource requirements of electrooptical organizations in performing digital computing tasks. We define a generic model of parallel computation using optical interconnects, called the optical model of computation (OMC). In this model, computation is performed in digital electronics and communication is performed using free space optics. Using this model we derive relationships between information transfer and computational resources in solving a given problem. To illustrate our results, we concentrate on a computationally intensive operation, 2-D digital image convolution. Irrespective of the input/output scheme and the order of computation, we show a lower bound of ?(nw) on the optical volume required for convolving a w x w kernel with an n x n image, if the input bits are given to the system only once.

  1. Digital pseudo-analogue satellite TV transmission system

    NASA Astrophysics Data System (ADS)

    Tomlinson, M.; Ward, C.; Rendle, M.

    1986-07-01

    With the advent of high-speed digital signal processing circuits, it is now practicable to transmit television signals by satellite using a variety of digitally derived modulation techniques. By using the concept of E(s)/N(0), the ratio of the energy needed to transmit each sample to the noise spectral density, several different signal formats are critically compared in the paper. It is shown that the wide bandwidths associated with high-definition television may be supported by relatively narrow transponder bandwidths through the use of signal formats using phase-modulated discrete symbols. Furthermore, the bandwidth efficiency is shown to be better than the classical technique of frequency modulation for satellite TV transmission. A digitally implemented system is described and results are given of successful satellite tests using the Eutelsat F1 satellite and the Westar V satellite.

  2. Optical/digital identification/verification system based on digital watermarking technology

    NASA Astrophysics Data System (ADS)

    Herrigel, Alexander; Voloshynovskiy, Sviatoslav V.; Hrytskiv, Zenon D.

    2000-06-01

    This paper presents a new approach for the secure integrity verification of driver licenses, passports or other analogue identification documents. The system embeds (detects) the reference number of the identification document with the DCT watermark technology in (from) the owner photo of the identification document holder. During verification the reference number is extracted and compared with the reference number printed in the identification document. The approach combines optical and digital image processing techniques. The detection system must be able to scan an analogue driver license or passport, convert the image of this document into a digital representation and then apply the watermark verification algorithm to check the payload of the embedded watermark. If the payload of the watermark is identical with the printed visual reference number of the issuer, the verification was successful and the passport or driver license has not been modified. This approach constitutes a new class of application for the watermark technology, which was originally targeted for the copyright protection of digital multimedia data. The presented approach substantially increases the security of the analogue identification documents applied in many European countries.

  3. Analysis of jitter in a digital transmission system

    NASA Astrophysics Data System (ADS)

    Ownby, Michael R.

    1986-12-01

    This work outlines a method for predicting the accumulation of timing jitter in a digital transmission system. Earlier works have concentrated on regenerative repeators or pulse-stuffing multiplexer/demultiplexers, as the sole source of jitter, without regard to the digital transmission system as a whole. Here, the timing jitter accumulation is evaluated from source to sink with almost any sequence of repeater chains, multiplexers, switches and demultiplexers in between. The basic model for the jitter accumulation are taken from earlier works, such as the 1963 paper by Bryne et al, Systematic Jitter in a Chain of Digital Repeaters and the 1972 paper by Duttweiller, Waiting Time Jitter. These models have been reworked to some degree to reflect more recent timing extraction circuitry, but are basically unchanged from their original derivations. The digital transmission system is treated as a series of jitter transfer and jitter generation components which can be analyzed sequentially. The jitter is assumed to be an additive, random process whose spectrum is peak-to-peak, unit intervals versus frequency.

  4. Six-degree-of-freedom missile simulation using the ADI AD 100 digital computer and ADSIM simulation language

    NASA Technical Reports Server (NTRS)

    Zwaanenburg, Koos

    1989-01-01

    The use of an AD 100 computer and the ADSIM language in the six-degree-of-freedom digital simulation of an air-to-ground missile is illustrated. The missile is launched from a moving platform, typically a helicopter, and is capable of striking a mobile target up to 10 kilometers away. The missile could be any tactical missile. The performance numbers of the AD 100 show that it is possible to implement a high performance missile model in a real-time simulation without the problems associated with an implementation on a general purpose computer using FORTRAN.

  5. Comparison of analog and digital transceiver systems for MR imaging.

    PubMed

    Hashimoto, Seitaro; Kose, Katsumi; Haishi, Tomoyuki

    2014-01-01

    We critically evaluated analog and digital transceivers for magnetic resonance (MR) imaging systems under identical experimental conditions to identify and compare their advantages and disadvantages. MR imaging experiments were performed using a 4.74-tesla vertical-bore superconducting magnet and a high sensitivity gradient coil probe. We acquired 3-dimensional spin echo images of a kumquat with and without using a gain-stepping scan technique to extend the dynamic range of the receiver systems. The acquired MR images clearly demonstrated nearly identical image quality for both transceiver systems, but DC and ghosting artifacts were obtained for the analog transceiver system. We therefore concluded that digital transceivers have several advantages over the analog transceivers.

  6. Comparison of analog and digital transceiver systems for MR imaging.

    PubMed

    Hashimoto, Seitaro; Kose, Katsumi; Haishi, Tomoyuki

    2014-01-01

    We critically evaluated analog and digital transceivers for magnetic resonance (MR) imaging systems under identical experimental conditions to identify and compare their advantages and disadvantages. MR imaging experiments were performed using a 4.74-tesla vertical-bore superconducting magnet and a high sensitivity gradient coil probe. We acquired 3-dimensional spin echo images of a kumquat with and without using a gain-stepping scan technique to extend the dynamic range of the receiver systems. The acquired MR images clearly demonstrated nearly identical image quality for both transceiver systems, but DC and ghosting artifacts were obtained for the analog transceiver system. We therefore concluded that digital transceivers have several advantages over the analog transceivers. PMID:25167877

  7. A Timer for Synchronous Digital Systems

    NASA Technical Reports Server (NTRS)

    McKenney, Elizabeth; Irwin, Philip

    2003-01-01

    The Real-Time Interferometer Control Systems Testbed (RICST) timing board is a VersaModule Eurocard (VME)-based board that can generate up to 16 simultaneous, phase-locked timing signals at a rate defined by the user. It can also generate all seven VME interrupt requests (IRQs). The RICST timing board is suitable mainly for robotic, aerospace, and real-time applications. Several circuit boards on the market are capable of generating periodic IRQs. Most are associated with Global Positioning System (GPS) receivers and Inter Range Instrumentation Group (IRIG) time-code generators, whereas this board uses either an internal VME clock or an externally generated clock signal to synchronize multiple components of the system. The primary advantage of this board is that there is no discernible jitter in the output clock waveforms because the signals are divided down from a high-frequency clock signal instead of being phase-locked from a lower frequency. The primary disadvantage to this board, relative to other periodic-IRQ-generating boards, is that it is more difficult to synchronize the system to wall clock time.

  8. Intermittent/transient faults in digital systems

    NASA Technical Reports Server (NTRS)

    Masson, G. M.; Glazer, R. E.

    1982-01-01

    Containment set techniques are applied to 8085 microprocessor controllers so as to transform a typical control system into a slightly modified version, shown to be crashproof: after the departure of the intermittent/transient fault, return to one proper control algorithm is assured, assuming no permanent faults occur.

  9. Design of a modular digital computer system

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A design tradeoff study is reported for a modular spaceborne computer system that is responsive to many mission types and phases. The computer uses redundancy to maximize reliability, and multiprocessing to maximize processing capacity. Fault detection and recovery features provide optimal reliability.

  10. The simulation of piano string vibration: from physical models to finite difference schemes and digital waveguides.

    PubMed

    Bensa, Julien; Bilbao, Stefan; Kronland-Martinet, Richard; Smith, Julius O

    2003-08-01

    A model of transverse piano string vibration, second order in time, which models frequency-dependent loss and dispersion effects is presented here. This model has many desirable properties, in particular that it can be written as a well-posed initial-boundary value problem (permitting stable finite difference schemes) and that it may be directly related to a digital waveguide model, a digital filter-based algorithm which can be used for musical sound synthesis. Techniques for the extraction of model parameters from experimental data over the full range of the grand piano are discussed, as is the link between the model parameters and the filter responses in a digital waveguide. Simulations are performed. Finally, the waveguide model is extended to the case of several coupled strings. PMID:12942987

  11. Propulsion System Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Tai, Jimmy C. M.; McClure, Erin K.; Mavris, Dimitri N.; Burg, Cecile

    2002-01-01

    The Aerospace Systems Design Laboratory at the School of Aerospace Engineering in Georgia Institute of Technology has developed a core competency that enables propulsion technology managers to make technology investment decisions substantiated by propulsion and airframe technology system studies. This method assists the designer/manager in selecting appropriate technology concepts while accounting for the presence of risk and uncertainty as well as interactions between disciplines. This capability is incorporated into a single design simulation system that is described in this paper. This propulsion system design environment is created with a commercially available software called iSIGHT, which is a generic computational framework, and with analysis programs for engine cycle, engine flowpath, mission, and economic analyses. iSIGHT is used to integrate these analysis tools within a single computer platform and facilitate information transfer amongst the various codes. The resulting modeling and simulation (M&S) environment in conjunction with the response surface method provides the designer/decision-maker an analytical means to examine the entire design space from either a subsystem and/or system perspective. The results of this paper will enable managers to analytically play what-if games to gain insight in to the benefits (and/or degradation) of changing engine cycle design parameters. Furthermore, the propulsion design space will be explored probabilistically to show the feasibility and viability of the propulsion system integrated with a vehicle.

  12. Progress in multirate digital control system design

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.

    1991-01-01

    A new methodology for multirate sampled-data control design based on a new generalized control law structure, two new parameter-optimization-based control law synthesis methods, and a new singular-value-based robustness analysis method are described. The control law structure can represent multirate sampled-data control laws of arbitrary structure and dynamic order, with arbitrarily prescribed sampling rates for all sensors and update rates for all processor states and actuators. The two control law synthesis methods employ numerical optimization to determine values for the control law parameters. The robustness analysis method is based on the multivariable Nyquist criterion applied to the loop transfer function for the sampling period equal to the period of repetition of the system's complete sampling/update schedule. The complete methodology is demonstrated by application to the design of a combination yaw damper and modal suppression system for a commercial aircraft.

  13. Delegating responsibility in digital systems: horton's 'who doneit?'

    SciTech Connect

    Miller, Mark S.; Donnelley, Jed; Karp, Alan H.

    2007-06-01

    Delegation is a fundamental part of human society. If digital systems are to mediate ever more of our interactions, we must be able to delegate responsibility within them. While some systems support the controlled delegation of authority, and other systems support assignment of responsibility, today we have no means for delegating responsibility, that is, delegating authority coupled with assigning responsibility for using that authority. Horton demonstrates how delegation of responsibility can be added to systems that already support delegation of authority-object-capability systems.

  14. Rotorcraft digital advanced avionics system (RODAAS) functional description

    NASA Technical Reports Server (NTRS)

    Peterson, E. M.; Bailey, J.; Mcmanus, T. J.

    1985-01-01

    A functional design of a rotorcraft digital advanced avionics system (RODAAS) to transfer the technology developed for general aviation in the Demonstration Advanced Avionics System (DAAS) program to rotorcraft operation was undertaken. The objective was to develop an integrated avionics system design that enhances rotorcraft single pilot IFR operations without increasing the required pilot training/experience by exploiting advanced technology in computers, busing, displays and integrated systems design. A key element of the avionics system is the functionally distributed architecture that has the potential for high reliability with low weight, power and cost. A functional description of the RODAAS hardware and software functions is presented.

  15. Advanced Detector and Waveform Digitizer for Water Vapor DIAL Systems

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Luck, William S., Jr.; DeYoung, Russell J.

    1998-01-01

    Measurement of atmospheric water vapor has become a major requirement for understanding moist-air processes. Differential absorption lidar (DIAL) is a technique best suited for the measurement of atmospheric water vapor. NASA Langley Research Center is continually developing improved DIAL systems. One aspect of current development is focused on the enhancement of a DIAL receiver by applying state-of-the-art technology in building a new compact detection system that will be placed directly on the DIAL receiver telescope. The newly developed detection system has the capability of being digitally interfaced with a simple personal computer, using a discrete input/output interface. This has the potential of transmitting digital data over relatively long distances instead of analog signals, which greatly reduces measurement noise. In this paper, we discuss some results from the new compact water vapor DIAL detection system which includes a silicon based avalanche photodiode (APD) detector, a 14-bit, 10-MHz waveform digitizer, a microcontroller and other auxiliary electronics. All of which are contained on a small printed-circuit-board. This will significantly reduce the weight and volume over the current CAMAC system and eventually will be used in a water vapor DIAL system on an unpiloted atmospheric vehicle (UAV) aircraft, or alternatively on an orbiting spacecraft.

  16. Plant Modernization with Digital Reactor Protection System Safety System Upgrades at US Nuclear Power Stations

    SciTech Connect

    Heckle, Wm. Lloyd; Bolian, Tricia W.

    2006-07-01

    As the current fleet of nuclear power plants in the US reaches 25+ years of operation, obsolescence is driving many utilities to implement upgrades to both their safety and non-safety-related Instrumentation and Control (I and C) Systems. Digital technology is the predominant replacement technology for these upgrades. Within the last 15 years, digital control systems have been deployed in non-safety- related control applications at many utilities. In addition, a few utilities have replaced small safety-related systems utilizing digital technology. These systems have shown digital technology to be robust, reliable and simpler to maintain. Based upon this success, acceptance of digital technology has gained momentum with both utilities and regulatory agencies. Today, in an effort to extend the operating lives of their nuclear stations and resolve obsolescence of critical components, utilities are now pursuing digital technology for replacement of their primary safety systems. AREVA is leading this effort in the United States with the first significant digital upgrade of a major safety system. AREVA has previously completed upgrades to safety-related control systems emergency diesel engine controls and governor control systems for a hydro station which serves as the emergency power source for a nuclear station. Currently, AREVA is implementing the replacement of both the Reactor Protection System (RPS) and the Engineered Safety Features Actuation System (ESFAS) on all three units at a US PWR site. (authors)

  17. An automated digital imaging system for environmental monitoring applications

    USGS Publications Warehouse

    Bogle, Rian; Velasco, Miguel; Vogel, John

    2013-01-01

    Recent improvements in the affordability and availability of high-resolution digital cameras, data loggers, embedded computers, and radio/cellular modems have advanced the development of sophisticated automated systems for remote imaging. Researchers have successfully placed and operated automated digital cameras in remote locations and in extremes of temperature and humidity, ranging from the islands of the South Pacific to the Mojave Desert and the Grand Canyon. With the integration of environmental sensors, these automated systems are able to respond to local conditions and modify their imaging regimes as needed. In this report we describe in detail the design of one type of automated imaging system developed by our group. It is easily replicated, low-cost, highly robust, and is a stand-alone automated camera designed to be placed in remote locations, without wireless connectivity.

  18. Design of digital hardware system for pulse signals.

    PubMed

    Lee, J; Kim, J; Lee, M

    2001-12-01

    In this study, we have developed the digital hardware system which performs signal processing necessary for the filtering to eliminate noises by inputting pulse wave signals from the sensor group. With a view to obtain clinically effective information, we analyzed structural elements of pulse waveform and, thus, conducted a systematic classification. What is more, we performed the modeling of the digital filter by using the Steiglitz-McBride iteration method in order to get the same results with output signals coming out of an galvanometer of analog type of existing Pulse diagnosis system with input signals entering into galvanometer and coming out of the amp group of the Pulse diagnosis system. PMID:11708398

  19. A polarized digital shearing speckle pattern interferometry system based on temporal wavelet transformation.

    PubMed

    Feng, Ziang; Gao, Zhan; Zhang, Xiaoqiong; Wang, Shengjia; Yang, Dong; Yuan, Hao; Qin, Jie

    2015-09-01

    Digital shearing speckle pattern interferometry (DSSPI) has been recognized as a practical tool in testing strain. The DSSPI system which is based on temporal analysis is attractive because of its ability to measure strain dynamically. In this paper, such a DSSPI system with Wollaston prism has been built. The principles and system arrangement are described and the preliminary experimental result of the displacement-derivative test of an aluminum plate is shown with the wavelet transformation method and the Fourier transformation method. The simulations have been conducted with the finite element method. The comparison of the results shows that quantitative measurement of displacement-derivative has been realized.

  20. A polarized digital shearing speckle pattern interferometry system based on temporal wavelet transformation.

    PubMed

    Feng, Ziang; Gao, Zhan; Zhang, Xiaoqiong; Wang, Shengjia; Yang, Dong; Yuan, Hao; Qin, Jie

    2015-09-01

    Digital shearing speckle pattern interferometry (DSSPI) has been recognized as a practical tool in testing strain. The DSSPI system which is based on temporal analysis is attractive because of its ability to measure strain dynamically. In this paper, such a DSSPI system with Wollaston prism has been built. The principles and system arrangement are described and the preliminary experimental result of the displacement-derivative test of an aluminum plate is shown with the wavelet transformation method and the Fourier transformation method. The simulations have been conducted with the finite element method. The comparison of the results shows that quantitative measurement of displacement-derivative has been realized. PMID:26429424

  1. Analytical stability and simulation response study for a coupled two-body system

    NASA Technical Reports Server (NTRS)

    Tao, K. M.; Roberts, J. R.

    1975-01-01

    An analytical stability study and a digital simulation response study of two connected rigid bodies are documented. Relative rotation of the bodies at the connection is allowed, thereby providing a model suitable for studying system stability and response during a soft-dock regime. Provisions are made of a docking port axes alignment torque and a despin torque capability for encountering spinning payloads. Although the stability analysis is based on linearized equations, the digital simulation is based on nonlinear models.

  2. Analog and digital systems of imaging in roentgenodiagnostics.

    PubMed

    Oborska-Kumaszyńska, Dominika; Wiśniewska-Kubka, Sylwia

    2010-04-01

    In the recent years, we have been witnessing a very dynamic development of diagnostic methods of imaging. In contemporary radiology, the carrier of the diagnostic information is the image, obtained as a result of an X-ray beam transmitted through the patient's body, with modulation of intensity, and processing of data collected by the detector. Depending on the diagnostic method used, signals can be detected with analog (x-ray film) or digital systems (CR, DR and DDR). Each of these methods of image acquisition, due to its own technological solutions, determines a different quality of imaging (diagnostic data). The introduction of digital image receptors, instead of conventional SF systems, increased the patient dose, as a result of a gradually increasing exposure. This followed from the fact that in digital systems, the increased radiation dose reduces image noise and improves image quality, and that is owing to the data capacity of these systems (impossible in SF systems with a limited data capacity of the image detector). The availability of the multitude of imaging systems, each characterized by disparate qualitative and quantitative parameters, implies the problem of evaluation and enforcement of a proper efficiency from manufacturers of these systems.At the same time, there is a legal problem present in our country, i.e. the lack of laws and regulations regarding standards of the scope of quality control (parameters) and measurement methodology for the systems of digital image acquisition. In the European countries, the scope and standards of control are regulated by the manufacturers and European Guidelines, whereas in the United States, AAPM Reports have been introduced, that specifically describe methods of tests performance, their frequency, as well as target values and limits. This paper is a review of both, the scope of quality control parameters of image detectors in analog and digital systems of imaging, and the measurement methodology. The parameters

  3. Analog and digital systems of imaging in roentgenodiagnostics

    PubMed Central

    Oborska-Kumaszyńska, Dominika; Wiśniewska-Kubka, Sylwia

    2010-01-01

    Summary In the recent years, we have been witnessing a very dynamic development of diagnostic methods of imaging. In contemporary radiology, the carrier of the diagnostic information is the image, obtained as a result of an X-ray beam transmitted through the patient’s body, with modulation of intensity, and processing of data collected by the detector. Depending on the diagnostic method used, signals can be detected with analog (x-ray film) or digital systems (CR, DR and DDR). Each of these methods of image acquisition, due to its own technological solutions, determines a different quality of imaging (diagnostic data). The introduction of digital image receptors, instead of conventional SF systems, increased the patient dose, as a result of a gradually increasing exposure. This followed from the fact that in digital systems, the increased radiation dose reduces image noise and improves image quality, and that is owing to the data capacity of these systems (impossible in SF systems with a limited data capacity of the image detector). The availability of the multitude of imaging systems, each characterized by disparate qualitative and quantitative parameters, implies the problem of evaluation and enforcement of a proper efficiency from manufacturers of these systems. At the same time, there is a legal problem present in our country, i.e. the lack of laws and regulations regarding standards of the scope of quality control (parameters) and measurement methodology for the systems of digital image acquisition. In the European countries, the scope and standards of control are regulated by the manufacturers and European Guidelines, whereas in the United States, AAPM Reports have been introduced, that specifically describe methods of tests performance, their frequency, as well as target values and limits. This paper is a review of both, the scope of quality control parameters of image detectors in analog and digital systems of imaging, and the measurement methodology. The

  4. Simulating total-dose and dose-rate effects on digital microelectronics timing delays using VHDL

    SciTech Connect

    Brothers, C.P. Jr.; Pugh, R.D.

    1995-12-01

    This paper describes a fast timing simulator based on Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL) for simulating the timing of digital microelectronics in pre-irradiation, total dose, and dose-rate radiation environments. The goal of this research is the rapid and accurate timing simulation of radiation-hardened microelectronic circuits before, during, and after exposure to ionizing radiation. The results of this research effort were the development of VHDL compatible models capable of rapid and accurate simulation of the effect of radiation on the timing performance of microelectronic circuits. The effects of radiation for total dose at 1 Mrad(Si) and dose rates up to 2 {times} 10{sup 12} rads(Si) per second were modeled for a variety of Separation by IMplantion of OXygen (SIMOX) circuits. In all cases tested, the VHDL simulations ran at least 600 times faster than SPICE while maintaining a timing accuracy to within 15% of SPICE values.

  5. 76 FR 13436 - NIJ Request for Comments on Draft Vehicular Digital Multimedia Evidence Recording System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    ... Office of Justice Programs NIJ Request for Comments on Draft Vehicular Digital Multimedia Evidence... Digital Multimedia Evidence Recording System Selection and Application Guide AGENCY: National Institute of... Evidence Recording System Certification Program Requirements for Law Enforcement'' ``Law...

  6. 76 FR 27355 - Law Enforcement Vehicular Digital Multimedia Evidence Recording System Selection and Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Office of Justice Programs Law Enforcement Vehicular Digital Multimedia Evidence Recording System Selection... public, the ``Law Enforcement Vehicular Digital Multimedia Evidence Recording System Selection...

  7. 75 FR 78269 - Vehicular Digital Multimedia Evidence Recording System (VDMERS) Standard for Law Enforcement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Office of Justice Programs Vehicular Digital Multimedia Evidence Recording System (VDMERS) Standard for Law... the general public the draft ``Vehicular Digital Multimedia Evidence Recording System Standard for...

  8. Digital Global Orbit Feedback System Developing In SRRC

    NASA Astrophysics Data System (ADS)

    Kuo, C. H.; Lin, K. K.; Chen, Jenny; Chen, J. S.; Wang, C. J.; Chen, C. S.; Hsu, K. T.

    1997-05-01

    The digital global orbit feedback system for the storage ring of SRRC has been upgraded in terms of its feedback bandwidth extension by increasing its data acquisition sampling rate and compensating eddy current effect of vacuum chamber with filter. This orbit feedback system has been applied incorporate with the insertion devices operation, such as W20 wiggler and APU undulator, in order to eliminate beam orbit disturbance. Applying this system to suppress orbit drift during energy ramping has also shown to be effective. Performance of this upgraded system will be presented in this report.

  9. Digital Full-Scope Simulation of a Conventional Nuclear Power Plant Control Room, Phase 2: Installation of a Reconfigurable Simulator to Support Nuclear Plant Sustainability

    SciTech Connect

    Ronald L. Boring; Vivek Agarwal; Kirk Fitzgerald; Jacques Hugo; Bruce Hallbert

    2013-03-01

    The U.S. Department of Energy’s Light Water Reactor Sustainability program has developed a control room simulator in support of control room modernization at nuclear power plants in the U.S. This report highlights the recent completion of this reconfigurable, full-scale, full-scope control room simulator buildout at the Idaho National Laboratory. The simulator is fully reconfigurable, meaning it supports multiple plant models developed by different simulator vendors. The simulator is full-scale, using glasstop virtual panels to display the analog control boards found at current plants. The present installation features 15 glasstop panels, uniquely achieving a complete control room representation. The simulator is also full-scope, meaning it uses the same plant models used for training simulators at actual plants. Unlike in the plant training simulators, the deployment on glasstop panels allows a high degree of customization of the panels, allowing the simulator to be used for research on the design of new digital control systems for control room modernization. This report includes separate sections discussing the glasstop panels, their layout to mimic control rooms at actual plants, technical details on creating a multi-plant and multi-vendor reconfigurable simulator, and current efforts to support control room modernization at U.S. utilities. The glasstop simulator provides an ideal testbed for prototyping and validating new control room concepts. Equally importantly, it is helping create a standardized and vetted human factors engineering process that can be used across the nuclear industry to ensure control room upgrades maintain and even improve current reliability and safety.

  10. Clock distribution system for digital computers

    DOEpatents

    Wyman, Robert H.; Loomis, Jr., Herschel H.

    1981-01-01

    Apparatus for eliminating, in each clock distribution amplifier of a clock distribution system, sequential pulse catch-up error due to one pulse "overtaking" a prior clock pulse. The apparatus includes timing means to produce a periodic electromagnetic signal with a fundamental frequency having a fundamental frequency component V'.sub.01 (t); an array of N signal characteristic detector means, with detector means No. 1 receiving the timing means signal and producing a change-of-state signal V.sub.1 (t) in response to receipt of a signal above a predetermined threshold; N substantially identical filter means, one filter means being operatively associated with each detector means, for receiving the change-of-state signal V.sub.n (t) and producing a modified change-of-state signal V'.sub.n (t) (n=1, . . . , N) having a fundamental frequency component that is substantially proportional to V'.sub.01 (t-.theta..sub.n (t) with a cumulative phase shift .theta..sub.n (t) having a time derivative that may be made uniformly and arbitrarily small; and with the detector means n+1 (1.ltoreq.n

  11. Digital photofinishing system based on liquid crystal on silicon

    NASA Astrophysics Data System (ADS)

    Zheng, Minmin; Yan, Huimin; Zhang, Xiuda; Du, Yanli

    2006-01-01

    As the digital camera user base grows, so does the demand for digital imaging services. A new digital photo finishing system based on Liquid Crystal On Silicon (LCOS) is presented. The LCOS panel motherboard is made up of CMOS chip. Three individual streams of light (red, green, blue) are directed to corresponding Polarization Beam Spliter (PBS) to make the S polarization beam arrive at LCOS panel. When the Liquid appears light, the S polarization beam is changed to P polarization beam and reflected to pass through Polarization Beam Spliter. Compared with Thin Film Transistor-Liquid Crystal Display (TFT-LCD), LCOS has many merits including high resolution, high contrast, wide viewing angle, low cost and so on. In this work, we focus on the way in which the images will be displayed on LCOS. A liquid crystal on silicon microdisplay driver circuit for digital photo finishing system has been designed and fabricated using BRILLIAN microdisplay driver lite(MDD-LITE) ASIC and LCOS SXGA (1280×1024 pixel) with a 0.78"(20mm) diagonal active matrix reflective mode LCD. The driver includes a control circuit, which presents serial data, serial clock , write protect signals and control signals for LED, and a mixed circuit which implements RGB signal to input the LCOS. According to a minimum error sum of squares algorithm, we find a minimum offset and then shift RGB optical intensity vs voltage curves right and left to make these three curves almost coincide with each other. The design had great application in the digital photo finishing.

  12. Hardware-in-the-loop tow missile system simulator

    SciTech Connect

    Waldman, G.S.; Wootton, J.R.; Hobson, G.L.; Holder, D.L.

    1993-07-06

    A missile system simulator is described for use in training people for target acquisition, missile launch, and missile guidance under simulated battlefield conditions comprising: simulating means for producing a digital signal representing a simulated battlefield environment including at least one target movable therewithin, the simulating means generating an infrared map representing the field-of-view and the target; interface means for converting said digital signals to an infrared image; missile system hardware including the missile acquisition, tracking, and guidance portions thereof, said hardware sensing the infrared image to determine the location of the target in a field-of-view; and, image means for generating an infrared image of a missile launched at the target and guided thereto, the image means imposing the missile image onto the field-of-view for the missile hardware to acquire the image of the missile in addition to that of the target, and to generate guidance signals to guide the missile image to the target image, wherein the interfacing means is responsive to a guidance signal from the hardware to simulate, in real-time, the response of the missile to the guidance signal, the image means including a blackbody, laser means for irradiating the blackbody to heat it to a temperature at which it emits infrared radiation, and optic means for integrating the radiant image produced by heating the blackbody into the infrared map.

  13. Method for auto-alignment of digital optical phase conjugation systems based on digital propagation.

    PubMed

    Jang, Mooseok; Ruan, Haowen; Zhou, Haojiang; Judkewitz, Benjamin; Yang, Changhuei

    2014-06-16

    Optical phase conjugation (OPC) has enabled many optical applications such as aberration correction and image transmission through fiber. In recent years, implementation of digital optical phase conjugation (DOPC) has opened up the possibility of its use in biomedical optics (e.g. deep-tissue optical focusing) due to its ability to provide greater-than-unity OPC reflectivity (the power ratio of the phase conjugated beam and input beam to the OPC system) and its flexibility to accommodate additional wavefront manipulations. However, the requirement for precise (pixel-to-pixel matching) alignment of the wavefront sensor and the spatial light modulator (SLM) limits the practical usability of DOPC systems. Here, we report a method for auto-alignment of a DOPC system by which the misalignment between the sensor and the SLM is auto-corrected through digital light propagation. With this method, we were able to accomplish OPC playback with a DOPC system with gross sensor-SLM misalignment by an axial displacement of up to~1.5 cm, rotation and tip/tilt of ~5° and in-plane displacement of ~5 mm (dependent on the physical size of the sensor and the SLM). Our auto-alignment method robustly achieved a DOPC playback peak-to-background ratio (PBR) corresponding to more than ~30 % of the theoretical maximum. As an additional advantage, the auto-alignment procedure can be easily performed at will and, as such, allows us to correct for small mechanical drifts within the DOPC systems, thus overcoming a previously major DOPC system vulnerability. We believe that this reported method for implementing robust DOPC systems will broaden the practical utility of DOPC systems.

  14. Method for auto-alignment of digital optical phase conjugation systems based on digital propagation.

    PubMed

    Jang, Mooseok; Ruan, Haowen; Zhou, Haojiang; Judkewitz, Benjamin; Yang, Changhuei

    2014-06-16

    Optical phase conjugation (OPC) has enabled many optical applications such as aberration correction and image transmission through fiber. In recent years, implementation of digital optical phase conjugation (DOPC) has opened up the possibility of its use in biomedical optics (e.g. deep-tissue optical focusing) due to its ability to provide greater-than-unity OPC reflectivity (the power ratio of the phase conjugated beam and input beam to the OPC system) and its flexibility to accommodate additional wavefront manipulations. However, the requirement for precise (pixel-to-pixel matching) alignment of the wavefront sensor and the spatial light modulator (SLM) limits the practical usability of DOPC systems. Here, we report a method for auto-alignment of a DOPC system by which the misalignment between the sensor and the SLM is auto-corrected through digital light propagation. With this method, we were able to accomplish OPC playback with a DOPC system with gross sensor-SLM misalignment by an axial displacement of up to~1.5 cm, rotation and tip/tilt of ~5° and in-plane displacement of ~5 mm (dependent on the physical size of the sensor and the SLM). Our auto-alignment method robustly achieved a DOPC playback peak-to-background ratio (PBR) corresponding to more than ~30 % of the theoretical maximum. As an additional advantage, the auto-alignment procedure can be easily performed at will and, as such, allows us to correct for small mechanical drifts within the DOPC systems, thus overcoming a previously major DOPC system vulnerability. We believe that this reported method for implementing robust DOPC systems will broaden the practical utility of DOPC systems. PMID:24977504

  15. Digital image database processing to simulate image formation in ideal lighting conditions of the human eye

    NASA Astrophysics Data System (ADS)

    Castañeda-Santos, Jessica; Santiago-Alvarado, Agustin; Cruz-Félix, Angel S.; Hernández-Méndez, Arturo

    2015-09-01

    The pupil size of the human eye has a large effect in the image quality due to inherent aberrations. Several studies have been performed to calculate its size relative to the luminance as well as considering other factors, i.e., age, size of the adapting field and mono and binocular vision. Moreover, ideal lighting conditions are known, but software suited to our specific requirements, low cost and low computational consumption, in order to simulate radiation adaptation and image formation in the retina with ideal lighting conditions has not yet been developed. In this work, a database is created consisting of 70 photographs corresponding to the same scene with a fixed target at different times of the day. By using this database, characteristics of the photographs are obtained by measuring the luminance average initial threshold value of each photograph by means of an image histogram. Also, we present the implementation of a digital filter for both, image processing on the threshold values of our database and generating output images with the threshold values reported for the human eye in ideal cases. Some potential applications for this kind of filters may be used in artificial vision systems.

  16. Simulation of linear mechanical systems

    NASA Technical Reports Server (NTRS)

    Sirlin, S. W.

    1993-01-01

    A dynamics and controls analyst is typically presented with a structural dynamics model and must perform various input/output tests and design control laws. The required time/frequency simulations need to be done many times as models change and control designs evolve. This paper examines some simple ways that open and closed loop frequency and time domain simulations can be done using the special structure of the system equations usually available. Routines were developed to run under Pro-Matlab in a mixture of the Pro-Matlab interpreter and FORTRAN (using the .mex facility). These routines are often orders of magnitude faster than trying the typical 'brute force' approach of using built-in Pro-Matlab routines such as bode. This makes the analyst's job easier since not only does an individual run take less time, but much larger models can be attacked, often allowing the whole model reduction step to be eliminated.

  17. A tone-aided dual vestigial sideband system for digital communications on fading channels

    NASA Technical Reports Server (NTRS)

    Hladik, Stephen M.; Saulnier, Gary J.; Rafferty, William

    1989-01-01

    A spectrally efficient tone-aided dual vestigial sideband (TA/DVSB) system for digital data communications on fading channels is presented and described analytically. This PSK (phase-shift-keying) system incorporates a feed-forward, tone-aided demodulation technique to compensate for Doppler frequency shift and channel- induced, multipath fading. In contrast to other tone-in-band-type systems, receiver synchronization is derived from the complete data VSBs. Simulation results for the Rician fading channel are presented. These results demonstrate the receiver's ability to mitigate performance degradation due to fading and to obtain proper data carrier synchronization, suggesting that the proposed TA/DVSB system has promise for this application. Simulated BER (bit-error rate) data indicate that the TA/DVSB system effectively alleviates the channel distortions of the land mobile satellite application.

  18. Digital tripwire: a small automated human detection system

    NASA Astrophysics Data System (ADS)

    Fischer, Amber D.; Redd, Emmett; Younger, A. Steven

    2009-05-01

    A low cost, lightweight, easily deployable imaging sensor that can dependably discriminate threats from other activities within its field of view and, only then, alert the distant duty officer by transmitting a visual confirmation of the threat would provide a valuable asset to modern defense. At present, current solutions suffer from a multitude of deficiencies - size, cost, power endurance, but most notably, an inability to assess an image and conclude that it contains a threat. The human attention span cannot maintain critical surveillance over banks of displays constantly conveying such images from the field. DigitalTripwire is a small, self-contained, automated human-detection system capable of running for 1-5 days on two AA batteries. To achieve such long endurance, the DigitalTripwire system utilizes an FPGA designed with sleep functionality. The system uses robust vision algorithms, such as a partially unsupervised innovative backgroundmodeling algorithm, which employ several data reduction strategies to operate in real-time, and achieve high detection rates. When it detects human activity, either mounted or dismounted, it sends an alert including images to notify the command center. In this paper, we describe the hardware and software design of the DigitalTripwire system. In addition, we provide detection and false alarm rates across several challenging data sets demonstrating the performance of the vision algorithms in autonomously analyzing the video stream and classifying moving objects into four primary categories - dismounted human, vehicle, non-human, or unknown. Performance results across several challenging data sets are provided.

  19. Digital filtering for data compression in telemetry systems

    NASA Astrophysics Data System (ADS)

    Bell, R. M.

    There are many obstacles to using data compression in a telemetry system. Non-linear quantization is often too lossy, and the data is too highly structured to make variable-length entropy codes practical. This paper describes a lossless telemetry data compression system that was built using digital FIR filters. The method of compression takes advantage of the fact that the optimal Nyquist sampling rate is rarely achievable due to two factors: (1) Sensor/transducers are not bandlimited to the frequencies of interest; and (2) Accurate, high-order analog filters are not available to perform effective band limiting and prevent aliasing. Real-time digital filtering can enhance the performance of a typical sampling system so that it approaches Nyquist sampling rates, effectively compressing the amount of data and reducing transmission bandwidth. The system that was built reduced the sampling rate of 14 high-frequency vibration channels by a factor of two, and reduced the bandwidth of the-data link from 1.8 Mbps to 1.28 Mbps. The entire circuit uses seven function-specific, digital-filter DSP's operating in parallel (two 128-tap FIR filters can be implemented on each Motorola DSP56200), one EPROM and a Programmable Logic Device as the controller.

  20. Digital colour management system for colour parameters reconstruction

    NASA Astrophysics Data System (ADS)

    Grudzinski, Karol; Lasmanowicz, Piotr; Assis, Lucas M. N.; Pawlicka, Agnieszka; Januszko, Adam

    2013-10-01

    Digital Colour Management System (DCMS) and its application to new adaptive camouflage system are presented in this paper. The DCMS is a digital colour rendering method which would allow for transformation of a real image into a set of colour pixels displayed on a computer monitor. Consequently, it can analyse pixels' colour which comprise images of the environment such as desert, semi-desert, jungle, farmland or rocky mountain in order to prepare an adaptive camouflage pattern most suited for the terrain. This system is described in present work as well as the use the subtractive colours mixing method to construct the real time colour changing electrochromic window/pixel (ECD) for camouflage purpose. The ECD with glass/ITO/Prussian Blue(PB)/electrolyte/CeO2-TiO2/ITO/glass configuration was assembled and characterized. The ECD switched between green and yellow after +/-1.5 V application and the colours have been controlled by Digital Colour Management System and described by CIE LAB parameters.

  1. Multimodal digital color imaging system for facial skin lesion analysis

    NASA Astrophysics Data System (ADS)

    Bae, Youngwoo; Lee, Youn-Heum; Jung, Byungjo

    2008-02-01

    In dermatology, various digital imaging modalities have been used as an important tool to quantitatively evaluate the treatment effect of skin lesions. Cross-polarization color image was used to evaluate skin chromophores (melanin and hemoglobin) information and parallel-polarization image to evaluate skin texture information. In addition, UV-A induced fluorescent image has been widely used to evaluate various skin conditions such as sebum, keratosis, sun damages, and vitiligo. In order to maximize the evaluation efficacy of various skin lesions, it is necessary to integrate various imaging modalities into an imaging system. In this study, we propose a multimodal digital color imaging system, which provides four different digital color images of standard color image, parallel and cross-polarization color image, and UV-A induced fluorescent color image. Herein, we describe the imaging system and present the examples of image analysis. By analyzing the color information and morphological features of facial skin lesions, we are able to comparably and simultaneously evaluate various skin lesions. In conclusion, we are sure that the multimodal color imaging system can be utilized as an important assistant tool in dermatology.

  2. Digital filtering for data compression in telemetry systems

    SciTech Connect

    Bell, R.M.

    1994-08-01

    There are many obstacles to using data compression in a telemetry system. Non-linear quantization is often too lossy, and the data is too highly structured to make variable-length entropy codes practical. This paper describes a lossless telemetry data compression system that was built using digital FIR filters. The method of compression takes advantage of the fact that the optimal Nyquist sampling rate is rarely achievable due to two factors: (1) Sensor/transducers are not bandlimited to the frequencies of interest, and (2) Accurate, high-order analog filters are not available to perform effective band limiting and prevent aliasing. Real-time digital filtering can enhance the performance of a typical sampling system so that it approaches Nyquist sampling rates, effectively compressing the amount of data and reducing transmission bandwidth. The system that was built reduced the sampling rate of 14 high-frequency vibration channels by a factor of two, and reduced the bandwidth of the-data link from 1.8 Mbps to 1.28 Mbps. The entire circuit uses seven function-specific, digital-filter DSP`s operating in parallel (two 128-tap FIR filters can be implemented on each Motorola DSP56200), one EPROM and a Programmable Logic Device as the controller.

  3. Clinical performance evaluation of the prototype digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kim, H.; Park, H.; Choi, J.; Choi, Y.

    2012-03-01

    The rapid development and clinical use of digital mammography in the past decade has made possible the development of digital breast tomosynthesis (DBT), which can overcome the limitation of conventional mammography and improve the specificity of mammography with improved marginal visibility of lesion and early breast cancer detection, especially for women with dense breast. The purpose of this study is to characterize the physical properties of DBT system and to optimize the exposure condition using effective modulation transfer function (eMTF), effective noise power spectrum (eNPS), and effective detective quantum efficiency (eDQE). The first generation KERI prototype digital tomosyntesis system for breast imaging using CMOS flat panel detector was used in this study. It was found that the spatial frequency dependent metrics depend on both the inherent properties of the detector and imaging geometry including breast thickness. For thicker breast, eDQE decreases as scatter fraction increases at fixed tube voltage. Moreover, eMTF shows no significant difference as changing tube voltage while eDQE at 27 kVp is relatively degraded. Consequently, the quantitative evaluation of the DBT system with different exposure condition and breast thickness should be fully considered before building the system and application in clinical hospital.

  4. Designing power system simulators for the smart grid: combining controls, communications, and electro-mechanical dynamics

    SciTech Connect

    Nutaro, James J

    2011-01-01

    Open source software has a leading role in research on simulation technology for electrical power systems. Research simulators demonstrate new features for which there is nascent but growing demand not yet provided for by commercial simulators. Of particular interest is the inclusion of models of software-intensive and communication-intensive controls in simulations of power system transients. This paper describes two features of the ORNL power system simulator that help it meet this need. First is its use of discrete event simulation for all aspects of the model: control, communication, and electro-mechanical dynamics. Second is an interoperability interface that enables the ORNL power system simulator to be integrated with existing, discrete event simulators of digital communication systems. The paper concludes with a brief discussion of how these aspects of the ORNL power system simulator might be inserted into production-grade simulation tools.

  5. Digital computer simulation model of the Englishtown aquifer in the northern coastal plain of New Jersey

    USGS Publications Warehouse

    Nichols, W.D.

    1977-01-01

    Continued decline of water levels in the Englishtown aquifer, in New Jersey, has caused considerable concern regarding the ability of the aquifer to meet future yield demands. A detailed study of the capability of the aquifer to yield water entailed the use of a digital computer simulation model to evaluate aquifer and confining layer coefficients and to test alternative concepts of the hydrodynamics of the flow system. The modeled area includes about 750 square miles of the northern Coastal Plain of New Jersey and encompasses all the major centers of pumping from the Englishtown aquifer. The simulation model was calibrated by matching computed declines with historical water-level declines over the 12-year period, 1959-70. The volume of transient and steady leakage into the Englishtown aquifer from and through the adjacent confining layers equaled more than 90 percent of the total volume of water withdrawn from the aquifer between 1959 and 1970. The analytical estimate of transient leakage indicates that about 60 percent of the water withdrawn from the Englishtown between 1959 and 1970 was replaced by water released from storage in the adjacent confining beds. An additional 34 percent of the withdrawal over this time period was supported by steady leakage through the overlying confining bed from the Mount Laurel aquifer. Of the more than 30 billion gallons withdrawn from the aquifer over the 12-year period, about 2 billion gallons were obtained from storage in the aquifer. The values of aquifer and confining-layer coefficients used in the model are nearly the same as the average values obtained from field and laboratory data. (Woodard-USGS)

  6. The fit of crowns produced using digital impression systems.

    PubMed

    Vennerstrom, Micael; Fakhary, Mobin; Von Steyern, Per Vult

    2014-01-01

    Compare the marginal and internal fit of crowns manufactured using four different digital impression systems with crowns manufactured using conventional impression technique, that served as a control group. Fifty all-ceramic crowns were fabricated using 50 standardized dies divided into five groups, each group representing one impression system. Each crown was cemented onto its respective model and sectioned into four segments.The marginal and internal fit were measured at 8 predefined points. A total of 1567 measurements were made, statistically analyzed and compared with crowns fabricated using the five systems. The following was found: (1) No significant difference was found with regard to mar ginal gap when comparing the control group to any of the digital systems. (2) Lava™ had smaller marginal gaps than CEREC® and iTero®, (3) CEREC and Lava had smaller gaps in the chamfer compared to iTero and the control, (4) E4D® showed smaller gaps than CEREC at measuring points 4-8 and CEREC a smaller gap at point 2, (5) Lava showed smaller gaps than CEREC at measuring points 1,3 and 5-8. (6) Lava had smaller gaps than iTero at measuring points 1-4,7 and 8. All differences presented were significant. In conclusions, crowns manufactured using digital impressions present a marginal and internal fit equal to, or better than, crowns made using a conventional impression method.The marginal and internal fit of reconstructions made using digital impression techniques could improve with a lower initial setting of the spacer.

  7. Digital subcarrier multiplexing for fiber nonlinearity mitigation in coherent optical communication systems.

    PubMed

    Qiu, Meng; Zhuge, Qunbi; Chagnon, Mathieu; Gao, Yuliang; Xu, Xian; Morsy-Osman, Mohamed; Plant, David V

    2014-07-28

    In this work we experimentally investigate the improved intra-channel fiber nonlinearity tolerance of digital subcarrier multiplexed (SCM) signals in a single-channel coherent optical transmission system. The digital signal processing (DSP) for the generation and reception of the SCM signals is described. We show experimentally that the SCM signal with a nearly-optimum number of subcarriers can extend the maximum reach by 23% in a 24 GBaud DP-QPSK transmission with a BER threshold of 3.8 × 10(-3) and by 8% in a 24 GBaud DP-16-QAM transmission with a BER threshold of 2 × 10(-2). Moreover, we show by simulations that the improved performance of SCM signals is observed over a wide range of baud rates, further indicating the merits of SCM signals in baud-rate flexible agile transmissions and future high-speed optical transport systems.

  8. 78 FR 29392 - Embedded Digital Devices in Safety-Related Systems, Systems Important to Safety, and Items Relied...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-20

    ... COMMISSION Embedded Digital Devices in Safety-Related Systems, Systems Important to Safety, and Items Relied... Regulatory Issue Summary (RIS) 2013-XX, ``Embedded Digital Devices in Safety-Related Systems, Systems... Draft Regulatory Issue Summary (RIS) 2013-XX, ``Embedded Digital Devices in Safety-Related...

  9. Practical system for generating digital mixed reality video holograms.

    PubMed

    Song, Joongseok; Kim, Changseob; Park, Hanhoon; Park, Jong-Il

    2016-07-10

    We propose a practical system that can effectively mix the depth data of real and virtual objects by using a Z buffer and can quickly generate digital mixed reality video holograms by using multiple graphic processing units (GPUs). In an experiment, we verify that real objects and virtual objects can be merged naturally in free viewing angles, and the occlusion problem is well handled. Furthermore, we demonstrate that the proposed system can generate mixed reality video holograms at 7.6 frames per second. Finally, the system performance is objectively verified by users' subjective evaluations. PMID:27409312

  10. Ideal state reconstructor for deterministic digital control systems

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.

    1989-01-01

    A state reconstructor for deterministic digital systems is presented which is ideal in the following sense: if the plant parameters are known exactly, the output of the state reconstructor will exactly equal the true state of the plant, not just approximate it. Furthermore, this ideal state reconstructor adds no additional states or eigenvalues to the system. Nor does it affect the plant equation for the system in any way; it affects only the measurement equation. While there are countless ways of choosing the ideal state reconstructor parameters, two distinct methods are described here. An example is presented which illustrates the procedures to completely design the ideal state reconstructor using both methods.

  11. Full-scale system impact analysis: Digital document storage project

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The Digital Document Storage Full Scale System can provide cost effective electronic document storage, retrieval, hard copy reproduction, and remote access for users of NASA Technical Reports. The desired functionality of the DDS system is highly dependent on the assumed requirements for remote access used in this Impact Analysis. It is highly recommended that NASA proceed with a phased, communications requirement analysis to ensure that adequate communications service can be supplied at a reasonable cost in order to validate recent working assumptions upon which the success of the DDS Full Scale System is dependent.

  12. Smart Antenna UKM Testbed for Digital Beamforming System

    NASA Astrophysics Data System (ADS)

    Islam, Mohammad Tariqul; Misran, Norbahiah; Yatim, Baharudin

    2009-12-01

    A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH) array antenna and software reconfigurable digital beamforming system (DBS). The antenna is developed based on using the novel LIEH microstrip patch element design arranged into [InlineEquation not available: see fulltext.] uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance [InlineEquation not available: see fulltext.] floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88-2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.

  13. Building a cost efficient digital radiography system for educational purposes

    NASA Astrophysics Data System (ADS)

    Brown, Chris

    Due to the growing need for Medical Physicists, many universities are implementing a Medical Physics program into their academic catalog. To help establish a new program, feasible equipment may be needed to help academic departments provide a hands-on experience for students and help teach the basic concepts of Medical Physics. For example, clinical Digital Radiography Systems (DRS) are used to help teach the basic concepts of digital imaging. However, such systems can cost in excess of 100,000, creating a financial obstacle that will be difficult to overcome. Hence, the development of a cost efficient digital radiography system may be desired in order to eliminate the financial obstacle and give students a hands-on learning experience. This DRS uses three main components to develop an image, an x-ray source, an intensifying plate, and a charge-coupled device (CCD) camera. All three components are housed in a lead-lined box. The purpose of this project is to find the limitations of our DRS and compare the price between our DRS and commercially available DRSs. At optimal settings, a SNR of 25 is shown across the intensifying screen that can identify objects as small as 0.42mm. A Contrast-detail phantom shows the ability to decipher the varying thickness of foam rubber squares. The total cost of our DRS comes to 17,000.00, a fractional price tag compared to a commercially available DRS.

  14. Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits

    PubMed Central

    Chiesa, Alessandro; Santini, Paolo; Gerace, Dario; Raftery, James; Houck, Andrew A.; Carretta, Stefano

    2015-01-01

    Resolving quantum many-body problems represents one of the greatest challenges in physics and physical chemistry, due to the prohibitively large computational resources that would be required by using classical computers. A solution has been foreseen by directly simulating the time evolution through sequences of quantum gates applied to arrays of qubits, i.e. by implementing a digital quantum simulator. Superconducting circuits and resonators are emerging as an extremely promising platform for quantum computation architectures, but a digital quantum simulator proposal that is straightforwardly scalable, universal, and realizable with state-of-the-art technology is presently lacking. Here we propose a viable scheme to implement a universal quantum simulator with hybrid spin-photon qubits in an array of superconducting resonators, which is intrinsically scalable and allows for local control. As representative examples we consider the transverse-field Ising model, a spin-1 Hamiltonian, and the two-dimensional Hubbard model and we numerically simulate the scheme by including the main sources of decoherence. PMID:26563516

  15. Digitalized Design of Extraforaminal Lumbar Interbody Fusion: A Computer-Based Simulation and Cadaveric Study

    PubMed Central

    Yang, Mingjie; Zeng, Cheng; Guo, Song; Pan, Jie; Han, Yingchao; Li, Zeqing; Li, Lijun; Tan, Jun

    2014-01-01

    Purpose This study aims to investigate the feasibility of a novel lumbar approach named extraforaminal lumbar interbody fusion (ELIF), a newly emerging minimally invasive technique for treating degenerative lumbar disorders, using a digitalized simulation and a cadaveric study. Methods The ELIF surgical procedure was simulated using the Mimics surgical simulator and included dissection of the superior articular process, dilation of the vertebral foramen, and placement of pedicle screws and a cage. ELIF anatomical measures were documented using a digitalized technique and subsequently validated on fresh cadavers. Results The use of the Mimics allowed for the vivid simulation of ELIF surgical procedures, while the cadaveric study proved the feasibility of this novel approach. ELIF had a relatively lateral access approach that was located 8–9 cm lateral to the median line with an access depth of approximately 9 cm through the intermuscular space. Dissection of the superior articular processes could fully expose the target intervertebral discs and facilitate a more inclined placement of the pedicle screws and cage with robust enhancement. Conclusions According to the computer-based simulation and cadaveric study, it is feasible to perform ELIF. Further research including biomechanical study is needed to prove ELIF has a superior ability to preserve the posterior tension bands of the spinal column, with similar effects on spinal decompression, fixation, and fusion, and if it can enhance post-fusion spinal stability and expedites postoperative recovery. PMID:25157907

  16. Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits.

    PubMed

    Chiesa, Alessandro; Santini, Paolo; Gerace, Dario; Raftery, James; Houck, Andrew A; Carretta, Stefano

    2015-01-01

    Resolving quantum many-body problems represents one of the greatest challenges in physics and physical chemistry, due to the prohibitively large computational resources that would be required by using classical computers. A solution has been foreseen by directly simulating the time evolution through sequences of quantum gates applied to arrays of qubits, i.e. by implementing a digital quantum simulator. Superconducting circuits and resonators are emerging as an extremely promising platform for quantum computation architectures, but a digital quantum simulator proposal that is straightforwardly scalable, universal, and realizable with state-of-the-art technology is presently lacking. Here we propose a viable scheme to implement a universal quantum simulator with hybrid spin-photon qubits in an array of superconducting resonators, which is intrinsically scalable and allows for local control. As representative examples we consider the transverse-field Ising model, a spin-1 Hamiltonian, and the two-dimensional Hubbard model and we numerically simulate the scheme by including the main sources of decoherence.

  17. Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits

    NASA Astrophysics Data System (ADS)

    Chiesa, Alessandro; Santini, Paolo; Gerace, Dario; Raftery, James; Houck, Andrew A.; Carretta, Stefano

    2015-11-01

    Resolving quantum many-body problems represents one of the greatest challenges in physics and physical chemistry, due to the prohibitively large computational resources that would be required by using classical computers. A solution has been foreseen by directly simulating the time evolution through sequences of quantum gates applied to arrays of qubits, i.e. by implementing a digital quantum simulator. Superconducting circuits and resonators are emerging as an extremely promising platform for quantum computation architectures, but a digital quantum simulator proposal that is straightforwardly scalable, universal, and realizable with state-of-the-art technology is presently lacking. Here we propose a viable scheme to implement a universal quantum simulator with hybrid spin-photon qubits in an array of superconducting resonators, which is intrinsically scalable and allows for local control. As representative examples we consider the transverse-field Ising model, a spin-1 Hamiltonian, and the two-dimensional Hubbard model and we numerically simulate the scheme by including the main sources of decoherence.

  18. Versatile all-digital time interval measuring system

    NASA Astrophysics Data System (ADS)

    Vyhlidal, David; Cech, Miroslav

    2011-06-01

    This paper describes a design and performance of a versatile all-digital time interval measuring system. The measurement method is based on an interpolation principle. In this principle the time interval is first roughly digitized by a coarse counter driven by a high stability reference clock and the fractions between the clock periods are measured by two Time-to-Digital Converter chips TDC-GPX manufactured by Acam messelectronic. Control circuits allow programmable customization of the system to satisfy many applications such as laser range finding, event counting, or time-of-flight measurements in various physics experiments. The system has two reference clocks inputs and two independent channels for measuring start and stop events. Only one 40 MHz reference is required for the measurement. The second reference can be, for example, 1 PPS (Pulse per Second) signal from a GPS (Global Positioning System) to time tag events. Time intervals are measured using the highest resolution mode of the TDC-GPX chips. The resolution of each chip is software programmable and is PLL (Phase Locked Loop) stabilized against temperature and voltage variations. The system can achieve a timing resolution better than 15 ps rms with up to 90 kHz repetition rate. The time interval measurement range is from 0 ps up to 1 second. The power consumption of the whole system is 18 W including an embedded computer board and an LCD (Liquid Crystal Display) screen. The embedded computer controls the whole system, collects and evaluates measurement data and with the display provides a user interface. The system is implemented using commercially available components.

  19. The application of virtual reality systems as a support of digital manufacturing and logistics

    NASA Astrophysics Data System (ADS)

    Golda, G.; Kampa, A.; Paprocka, I.

    2016-08-01

    Modern trends in development of computer aided techniques are heading toward the integration of design competitive products and so-called "digital manufacturing and logistics", supported by computer simulation software. All phases of product lifecycle: starting from design of a new product, through planning and control of manufacturing, assembly, internal logistics and repairs, quality control, distribution to customers and after-sale service, up to its recycling or utilization should be aided and managed by advanced packages of product lifecycle management software. Important problems for providing the efficient flow of materials in supply chain management of whole product lifecycle, using computer simulation will be described on that paper. Authors will pay attention to the processes of acquiring relevant information and correct data, necessary for virtual modeling and computer simulation of integrated manufacturing and logistics systems. The article describes possibilities of use an applications of virtual reality software for modeling and simulation the production and logistics processes in enterprise in different aspects of product lifecycle management. The authors demonstrate effective method of creating computer simulations for digital manufacturing and logistics and show modeled and programmed examples and solutions. They pay attention to development trends and show options of the applications that go beyond enterprise.

  20. Electronic system for digital acquisition of rotational panoramic radiographs

    SciTech Connect

    McDavid, W.D.; Dove, S.B.; Welander, U.; Tronje, G. )

    1991-04-01

    A prototype system for digital panoramic imaging of the maxillofacial complex has been developed. In this system x-ray film is replaced by an electronic sensor that delivers the image information to a computer for storage in digital format. The images, which are similar to conventional panoramic radiographs, are displayed on a high-resolution video monitor and may be stored on optical disk for future use. Hard-copy output is also available. The present prototype system has been installed on an Orthopantomograph model OP10 panoramic x-ray machine is programmed for operation with this machine, but in principle the system can be installed on any such device. The system may be incorporated into the design of future panoramic x-ray systems or may be used to retrofit panoramic x-ray systems now using photographic film to record the radiographic image. Greater sensitivity of electronic sensors should make possible a reduction of x-ray dose to the patient, compared with film-based systems.

  1. Effective DQE (eDQE) and speed of digital radiographic systems: An experimental methodology

    PubMed Central

    Samei, Ehsan; Ranger, Nicole T.; MacKenzie, Alistair; Honey, Ian D.; Dobbins, James T.; Ravin, Carl E.

    2009-01-01

    Prior studies on performance evaluation of digital radiographic systems have primarily focused on the assessment of the detector performance alone. However, the clinical performance of such systems is also substantially impacted by magnification, focal spot blur, the presence of scattered radiation, and the presence of an antiscatter grid. The purpose of this study is to evaluate an experimental methodology to assess the performance of a digital radiographic system, including those attributes, and to propose a new metric, effective detective quantum efficiency (eDQE), a candidate for defining the efficiency or speed of digital radiographic imaging systems. The study employed a geometric phantom simulating the attenuation and scatter properties of the adult human thorax and a representative indirect flat-panel-based clinical digital radiographic imaging system. The noise power spectrum (NPS) was derived from images of the phantom acquired at three exposure levels spanning the operating range of the clinical system. The modulation transfer function (MTF) was measured using an edge device positioned at the surface of the phantom, facing the x-ray source. Scatter measurements were made using a beam stop technique. The eDQE was then computed from these measurements, along with measures of phantom attenuation and x-ray flux. The MTF results showed notable impact from the focal spot blur, while the NPS depicted a large component of structured noise resulting from use of an antiscatter grid. The eDQE was found to be an order of magnitude lower than the conventional DQE. At 120 kVp, eDQE(0) was in the 8%–9% range, fivefold lower than DQE(0) at the same technique. The eDQE method yielded reproducible estimates of the system performance in a clinically relevant context by quantifying the inherent speed of the system, that is, the actual signal to noise ratio that would be measured under clinical operating conditions. PMID:19746814

  2. Insights Gained for Updating an Analog I&C System to a Digital System

    SciTech Connect

    Adams, A.; Carte, N.; Hardesty, Duane; Hardin, LeRoy A; Wilson, Thomas L

    2012-01-01

    Licensees at both Nuclear Power Plants (NPPs) and Non-Power Reactors (NPRs) are increasing their use of state-of-the-art digital technology in instrumentation and control (I&C) systems because digital systems offer improved reactor control, information processing, and information storage over analog. Digital I&C systems can range from experimental systems for reactor control research (at NPRs), to measurement and display systems, to complete reactor console replacements. Because of the increasing difficulty in finding spare parts for their original analog I&C systems, many licensees have begun or have plans to upgrade, refurbish, or replace their old analog I&C systems with digital systems. The perception is that upgrading to a digital I&C system will solve all of a facility s obsolescence problems. However, licensees need to be aware of several issues associated with upgrading to a digital system including obsolescence of the digital system (hardware and software) because of the short product life cycle and the associated cost to acquire, store, and maintain a long-term supply of spare parts. Configuration management and cyber security are also vitally important for any upgrade. Further, it must be recognized that the introduction of software and microprocessors could create new failure mechanisms, such as software errors and increased susceptibility to electromagnetic interference. In fact, experience has shown that these failure mechanisms may cause the reactor to malfunction in a way not previously considered. Thus, a conversion from analog to digital I&C systems solves some problems while potentially introducing others. Recognition of the additional risks coupled with good design, engineering, review, and testing can identify and minimize these risks.

  3. Development of a remote digital augmentation system and application to a remotely piloted research vehicle

    NASA Technical Reports Server (NTRS)

    Edwards, J. W.; Deets, D. A.

    1975-01-01

    A cost-effective approach to flight testing advanced control concepts with remotely piloted vehicles is described. The approach utilizes a ground based digital computer coupled to the remotely piloted vehicle's motion sensors and control surface actuators through telemetry links to provide high bandwidth feedback control. The system was applied to the control of an unmanned 3/8-scale model of the F-15 airplane. The model was remotely augmented; that is, the F-15 mechanical and control augmentation flight control systems were simulated by the ground-based computer, rather than being in the vehicle itself. The results of flight tests of the model at high angles of attack are discussed.

  4. Performance improvements of a highly integrated digital electronic control system for an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Putnam, T. W.; Burcham, F. W., Jr.; Andries, M. G.; Kelly, J. B.

    1985-01-01

    The NASA highly integrated digital electronic control (HIDEC) program is structured to conduct flight research into the benefits of integrating an aircraft flight control system with the engine control system. A brief description of the HIDEC system installed on an F-15 aircraft is provided. The adaptive engine control system (ADECS) mode is described in detail, together with simulation results and analyses that show the significant excess thrust improvements achievable with the ADECS mode. It was found that this increased thrust capability is accompanied by reduced fan stall margin and can be realized during flight conditions where engine face distortion is low. The results of analyses and simulations also show that engine thrust response is improved and that fuel consumption can be reduced. Although the performance benefits that accrue because of airframe and engine control integration are being demonstrated on an F-15 aircraft, the principles are applicable to advanced aircraft such as the advanced tactical fighter and advanced tactical aircraft.

  5. Simulation System Fidelity Assessment at the Vertical Motion Simulator

    NASA Technical Reports Server (NTRS)

    Beard, Steven D.; Reardon, Scott E.; Tobias, Eric L.; Aponso, Bimal L.

    2013-01-01

    Fidelity is a word that is often used but rarely understood when talking about groundbased simulation. Assessing the cueing fidelity of a ground based flight simulator requires a comparison to actual flight data either directly or indirectly. Two experiments were conducted at the Vertical Motion Simulator using the GenHel UH-60A Black Hawk helicopter math model that was directly compared to flight data. Prior to the experiment the simulator s motion and visual system frequency responses were measured, the aircraft math model was adjusted to account for the simulator motion system delays, and the motion system gains and washouts were tuned for the individual tasks. The tuned motion system fidelity was then assessed against the modified Sinacori criteria. The first experiments showed similar handling qualities ratings (HQRs) to actual flight for a bob-up and sidestep maneuvers. The second experiment showed equivalent HQRs between flight and simulation for the ADS33 slalom maneuver for the two pilot participants. The ADS33 vertical maneuver HQRs were mixed with one pilot rating the flight and simulation the same while the second pilot rated the simulation worse. In addition to recording HQRs on the second experiment, an experimental Simulation Fidelity Rating (SFR) scale developed by the University of Liverpool was tested for applicability to engineering simulators. A discussion of the SFR scale for use on the Vertical Motion Simulator is included in this paper.

  6. A computer simulation study comparing lesion detection accuracy with digital mammography, breast tomosynthesis, and cone-beam CT breast imaging

    SciTech Connect

    Gong Xing; Glick, Stephen J.; Liu, Bob; Vedula, Aruna A.; Thacker, Samta

    2006-04-15

    Although conventional mammography is currently the best modality to detect early breast cancer, it is limited in that the recorded image represents the superposition of a three-dimensional (3D) object onto a 2D plane. Recently, two promising approaches for 3D volumetric breast imaging have been proposed, breast tomosynthesis (BT) and CT breast imaging (CTBI). To investigate possible improvements in lesion detection accuracy with either breast tomosynthesis or CT breast imaging as compared to digital mammography (DM), a computer simulation study was conducted using simulated lesions embedded into a structured 3D breast model. The computer simulation realistically modeled x-ray transport through a breast model, as well as the signal and noise propagation through a CsI based flat-panel imager. Polyenergetic x-ray spectra of Mo/Mo 28 kVp for digital mammography, Mo/Rh 28 kVp for BT, and W/Ce 50 kVp for CTBI were modeled. For the CTBI simulation, the intensity of the x-ray spectra for each projection view was determined so as to provide a total average glandular dose of 4 mGy, which is approximately equivalent to that given in conventional two-view screening mammography. The same total dose was modeled for both the DM and BT simulations. Irregular lesions were simulated by using a stochastic growth algorithm providing lesions with an effective diameter of 5 mm. Breast tissue was simulated by generating an ensemble of backgrounds with a power law spectrum, with the composition of 50% fibroglandular and 50% adipose tissue. To evaluate lesion detection accuracy, a receiver operating characteristic (ROC) study was performed with five observers reading an ensemble of images for each case. The average area under the ROC curves (A{sub z}) was 0.76 for DM, 0.93 for BT, and 0.94 for CTBI. Results indicated that for the same dose, a 5 mm lesion embedded in a structured breast phantom was detected by the two volumetric breast imaging systems, BT and CTBI, with statistically

  7. Eliciting Parents' Individual Requirements for an Inclusive Digital School System.

    PubMed

    Eftring, Håkan; Rassmus-Gröhn, Kirsten; Hedvall, Per-Olof

    2016-01-01

    Parents often have a busy time sorting out their life puzzles, including getting information about their children's activities in school. More and more communication between teachers and parents take place via digital school systems. It can be hard for parents to find the information they are looking for and the teacher decides when information is sent and what communication method to use. All parents, but especially parents with disabilities, might have individual preferences on how to receive information and how to adapt meetings at school. In this paper we present a project where we involved parents and teachers in focus groups, an idea workshop and iterative user trials of a digital prototype. The goal was to elicit parents' individual requirements for an inclusive digital school system, where they can store their individual preferences about how and when to receive information from school and what requirements they have on meetings at school. Preliminary results show that we managed to create open and focused discussions among parents and teachers. The parents reacted very positively on an onboarding page with the possibility to quickly and easily enter preferences after their first log in, but more work needs to be done on how preferences are categorized on the onboarding page. Finally, parents need to get clear feedback from teachers and school when they have entered or updated preferences, so they can trust that their preferences will be met. PMID:27534306

  8. An operations manual for the digital data system

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.

    1988-01-01

    The Digital Data System (DDS) was designed to incorporate the analog-to-digital conversion process into the initial data acquisition stage and to store the data in a digital format. This conversion is done as part of the acquisition process. Consequently, the data are ready to be analyzed as soon as the test is completed. This capability permits the researcher to alter test parameters during the course of the experiment based on the information acquired in a prior portion of the test. The DDS is currently able to simultaneously acquire up to 10 channels of data. The purpose of this document is fourfold: (1) to describe the capabilities of the hardware in sufficient detail to allow the reader to determine whether the DDS is the optimum system for a particular experiment; (2) to present some of the more significant software developed to provide analyses within a short time of the completion of data acquisition; (3) to provide the reader with sample runs of major software routines to demonstrate their convenience and simple usage; and (4) a portion of the document is used to describe software which uses an FFT-box to provide a means of comparison against which the DDS can be checked.

  9. Eliciting Parents' Individual Requirements for an Inclusive Digital School System.

    PubMed

    Eftring, Håkan; Rassmus-Gröhn, Kirsten; Hedvall, Per-Olof

    2016-01-01

    Parents often have a busy time sorting out their life puzzles, including getting information about their children's activities in school. More and more communication between teachers and parents take place via digital school systems. It can be hard for parents to find the information they are looking for and the teacher decides when information is sent and what communication method to use. All parents, but especially parents with disabilities, might have individual preferences on how to receive information and how to adapt meetings at school. In this paper we present a project where we involved parents and teachers in focus groups, an idea workshop and iterative user trials of a digital prototype. The goal was to elicit parents' individual requirements for an inclusive digital school system, where they can store their individual preferences about how and when to receive information from school and what requirements they have on meetings at school. Preliminary results show that we managed to create open and focused discussions among parents and teachers. The parents reacted very positively on an onboarding page with the possibility to quickly and easily enter preferences after their first log in, but more work needs to be done on how preferences are categorized on the onboarding page. Finally, parents need to get clear feedback from teachers and school when they have entered or updated preferences, so they can trust that their preferences will be met.

  10. Digital simulation of staining in histopathology multispectral images: enhancement and linear transformation of spectral transmittance.

    PubMed

    Bautista, Pinky A; Yagi, Yukako

    2012-05-01

    Hematoxylin and eosin (H&E) stain is currently the most popular for routine histopathology staining. Special and/or immuno-histochemical (IHC) staining is often requested to further corroborate the initial diagnosis on H&E stained tissue sections. Digital simulation of staining (or digital staining) can be a very valuable tool to produce the desired stained images from the H&E stained tissue sections instantaneously. We present an approach to digital staining of histopathology multispectral images by combining the effects of spectral enhancement and spectral transformation. Spectral enhancement is accomplished by shifting the N-band original spectrum of the multispectral pixel with the weighted difference between the pixel's original and estimated spectrum; the spectrum is estimated using M < N principal component (PC) vectors. The pixel's enhanced spectrum is transformed to the spectral configuration associated to its reaction to a specific stain by utilizing an N × N transformation matrix, which is derived through application of least mean squares method to the enhanced and target spectral transmittance samples of the different tissue components found in the image. Results of our experiments on the digital conversion of an H&E stained multispectral image to its Masson's trichrome stained equivalent show the viability of the method.

  11. Digital simulation of staining in histopathology multispectral images: enhancement and linear transformation of spectral transmittance

    NASA Astrophysics Data System (ADS)

    Bautista, Pinky A.; Yagi, Yukako

    2012-05-01

    Hematoxylin and eosin (H&E) stain is currently the most popular for routine histopathology staining. Special and/or immuno-histochemical (IHC) staining is often requested to further corroborate the initial diagnosis on H&E stained tissue sections. Digital simulation of staining (or digital staining) can be a very valuable tool to produce the desired stained images from the H&E stained tissue sections instantaneously. We present an approach to digital staining of histopathology multispectral images by combining the effects of spectral enhancement and spectral transformation. Spectral enhancement is accomplished by shifting the N-band original spectrum of the multispectral pixel with the weighted difference between the pixel's original and estimated spectrum; the spectrum is estimated using M < N principal component (PC) vectors. The pixel's enhanced spectrum is transformed to the spectral configuration associated to its reaction to a specific stain by utilizing an N × N transformation matrix, which is derived through application of least mean squares method to the enhanced and target spectral transmittance samples of the different tissue components found in the image. Results of our experiments on the digital conversion of an H&E stained multispectral image to its Masson's trichrome stained equivalent show the viability of the method.

  12. Digital simulation of staining in histopathology multispectral images: enhancement and linear transformation of spectral transmittance.

    PubMed

    Bautista, Pinky A; Yagi, Yukako

    2012-05-01

    Hematoxylin and eosin (H&E) stain is currently the most popular for routine histopathology staining. Special and/or immuno-histochemical (IHC) staining is often requested to further corroborate the initial diagnosis on H&E stained tissue sections. Digital simulation of staining (or digital staining) can be a very valuable tool to produce the desired stained images from the H&E stained tissue sections instantaneously. We present an approach to digital staining of histopathology multispectral images by combining the effects of spectral enhancement and spectral transformation. Spectral enhancement is accomplished by shifting the N-band original spectrum of the multispectral pixel with the weighted difference between the pixel's original and estimated spectrum; the spectrum is estimated using M < N principal component (PC) vectors. The pixel's enhanced spectrum is transformed to the spectral configuration associated to its reaction to a specific stain by utilizing an N × N transformation matrix, which is derived through application of least mean squares method to the enhanced and target spectral transmittance samples of the different tissue components found in the image. Results of our experiments on the digital conversion of an H&E stained multispectral image to its Masson's trichrome stained equivalent show the viability of the method. PMID:22612136

  13. Digital broadcasting systems - A new frontier for satellite communications

    NASA Astrophysics Data System (ADS)

    de Gaudenzi, R.; Elia, C.; Viola, R.

    A new concept is introduced, the digital direct satellite broadcasting system, which provides unprecedented flexibility by allowing a large number of audio-visual services to be carried and is suitable for both business applications and entertainment. This concept assumes an information rate of 40 Mbit/s, which is compatible with practically all current transponders. The rate of 40 Mbit/s allows up to four multiplexed TV channels, or one digital high-definition television signal if advances in source coding techniques are taken into account. It is shown, by means of a link-budget analysis, how a medium-power, direct-to-home TV satellite can provide audio-visual services to operators furnished with a 60 cm dish antenna.

  14. Digital Image Encryption Scheme Based on Multiple Chaotic Systems

    NASA Astrophysics Data System (ADS)

    Abd El-Latif, Ahmed A.; Li, Li; Zhang, Tiejun; Wang, Ning; Song, Xianhua; Niu, Xiamu

    2012-06-01

    Image encryption is a challenging task due to the significant level of sophistication achieved by forgerers and other cybercriminals. Advanced encryption methods for secure transmission, storage, and retrieval of digital images are increasingly needed for a number of military, medical, homeland security, and other applications. In this paper, we introduce a new digital image encryption algorithm. The new algorithm employs multiple chaotic systems and cryptographic primitive operations within the encryption process, which are efficiently implemented on modern processors, and adopts round keys for encryption using a chaotic map. Experiments conducted show that the proposed algorithm possesses robust security features such as fairly uniform distribution, high sensitivity to both keys and plainimages, almost ideal entropy, and the ability to highly de-correlate adjacent pixels in the cipherimages. Furthermore, it has a large key space, which greatly increases its security for image encryption applications.

  15. Interactive display system having a digital micromirror imaging device

    DOEpatents

    Veligdan, James T.; DeSanto, Leonard; Kaull, Lisa; Brewster, Calvin

    2006-04-11

    A display system includes a waveguide optical panel having an inlet face and an opposite outlet face. A projector cooperates with a digital imaging device, e.g. a digital micromirror imaging device, for projecting an image through the panel for display on the outlet face. The imaging device includes an array of mirrors tiltable between opposite display and divert positions. The display positions reflect an image light beam from the projector through the panel for display on the outlet face. The divert positions divert the image light beam away from the panel, and are additionally used for reflecting a probe light beam through the panel toward the outlet face. Covering a spot on the panel, e.g. with a finger, reflects the probe light beam back through the panel toward the inlet face for detection thereat and providing interactive capability.

  16. Ground-target detection system for digital video database

    NASA Astrophysics Data System (ADS)

    Liang, Yiqing; Huang, Jeffrey R.; Wolf, Wayne H.; Liu, Bede

    1998-07-01

    As more and more visual information is available on video, information indexing and retrieval of digital video data is becoming important. A digital video database embedded with visual information processing using image analysis and image understanding techniques such as automated target detection, classification, and identification can provide query results of higher quality. We address in this paper a robust digital video database system within which a target detection module is implemented and applied onto the keyframe images extracted by our digital library system. The tasks and application scenarios under consideration involve indexing video with information about detection and verification of artificial objects that exist in video scenes. Based on the scenario that the video sequences are acquired by an onboard camera mounted on Predator unmanned aircraft, we demonstrate how an incoming video stream is structured into different levels -- video program level, scene level, shot level, and object level, based on the analysis of video contents using global imagery information. We then consider that the keyframe representation is most appropriate for video processing and it holds the property that can be used as the input for our detection module. As a result, video processing becomes feasible in terms of decreased computational resources spent and increased confidence in the (detection) decisions reached. The architecture we proposed can respond to the query of whether artificial structures and suspected combat vehicles are detected. The architecture for ground detection takes advantage of the image understanding paradigm and it involves different methods to locate and identify the artificial object rather than nature background such as tree, grass, and cloud. Edge detection, morphological transformation, line and parallel line detection using Hough transform applied on key frame images at video shot level are introduced in our detection module. This function can

  17. Design and manufacture of a toroidal-type SMES for combination with real-time digital simulator (RTDS)

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-min; Kim, A.-Rong; Park, Minwon; Yu, In-Keun; Eom, Bum-Yong; Sim, Kidoek; Kim, Seok-Ho; Sohn, Myung-Hwan; Kim, Hae-Jong; Bae, Joon-Han; Seong, Ki-Cheol

    2011-06-01

    The authors designed and manufactured a toroidal-type superconducting magnetic energy storage (SMES) system. The toroidal-type SMES was designed using a 3D CAD program. The toroidal-type magnet consists of 30 double pancake coils (DPCs). The single pancake coils (SPCs), which constitute the double pancake coils, are arranged at an angle of 6° from each other, based on the central axis of the toroidal-type magnet. The cooling method used for the toroidal-type SMES is the conduction cooling type. When the cooling method for the toroidal-type SMES was designed, the two-stage Gifford-McMahon (GM) refrigerator was considered. The Bi-2223 HTS wire, which was made by soldering brass on both sides of the superconductor, is used for the magnet winding. Finally, the authors connected the toroidal-type SMES to a real-time digital simulator (RSCAD/RTDS) to simulate voltage sag compensation in a power utility.

  18. Infrared spectrometry studies: Spectral digital data acquisition system (1971 version)

    NASA Technical Reports Server (NTRS)

    Lu, L.; Lyon, R. J. P.

    1971-01-01

    The construction of the Stanford Spectral Digital Data Acquisition System is described. The objective of the system is to record both the spectral distribution of incoming radiation from the rock samples measured by the spectroradiometer (Exotech Model 10-34 Circular Variable Filter Infrared Spectroradiometer) together with other weather information. This system is designed for both laboratory and field measurement programs. The multichannel inputs (8 channels) of the system are as follows: Ch 1 the Spectro-radiometer, Ch 2 the radiometer (PRT-5), and Ch 3 to Ch 8 for the weather information. The system records data from channel 1 and channel 2 alternately for 48 times, before a fast sweep across the six weather channels, to form a single scan in the scan counter. The operation is illustrated in a block diagram, and the theory of operation is described. The outputs are written on a 7-track magnetic tape with IBM compatible form. The format of the tape and the playback computer programs are included. The micro-pac digital modules and a CIPHER model 70 tape recorder (Cipher Data Products) are used. One of the major characteristics of this system is that it is externally clocked by the spectroradiometer instead of taking data at intervals of various wavelengths by using internal-clocking.

  19. Implementation of real-time digital endoscopic image processing system

    NASA Astrophysics Data System (ADS)

    Song, Chul Gyu; Lee, Young Mook; Lee, Sang Min; Kim, Won Ky; Lee, Jae Ho; Lee, Myoung Ho

    1997-10-01

    Endoscopy has become a crucial diagnostic and therapeutic procedure in clinical areas. Over the past four years, we have developed a computerized system to record and store clinical data pertaining to endoscopic surgery of laparascopic cholecystectomy, pelviscopic endometriosis, and surgical arthroscopy. In this study, we developed a computer system, which is composed of a frame grabber, a sound board, a VCR control board, a LAN card and EDMS. Also, computer system controls peripheral instruments such as a color video printer, a video cassette recorder, and endoscopic input/output signals. Digital endoscopic data management system is based on open architecture and a set of widely available industry standards; namely Microsoft Windows as an operating system, TCP/IP as a network protocol and a time sequential database that handles both images and speech. For the purpose of data storage, we used MOD and CD- R. Digital endoscopic system was designed to be able to store, recreate, change, and compress signals and medical images. Computerized endoscopy enables us to generate and manipulate the original visual document, making it accessible to a virtually unlimited number of physicians.

  20. Digital system for dynamic turbine engine blade displacement measurements

    NASA Technical Reports Server (NTRS)

    Kiraly, L. J.

    1979-01-01

    An instrumentation concept for measuring blade tip displacements which employs optical probes and an array of micro-computers is presented. The system represents a hitherto unknown instrumentation capability for the acquisition and direct digitization of deflection data concurrently from all of the blade tips of an operational engine rotor undergoing flutter or forced vibration. System measurements are made using optical transducers which are fixed to the case. Measurements made in this way are the equivalent of those obtained by placing three surface-normal displacement transducers at three positions on each blade of an operational rotor.

  1. Airborne digital holographic system for cloud particle measurements.

    PubMed

    Fugal, Jacob P; Shaw, Raymond A; Saw, Ewe Wei; Sergeyev, Aleksandr V

    2004-11-10

    An in-line holographic system for in situ detection of atmospheric cloud particles [Holographic Detector for Clouds (HOLODEC)] has been developed and flown on the National Center for Atmospheric Research C-130 research aircraft. Clear holograms are obtained in daylight conditions at typical aircraft speeds of 100 m s(-1). The instrument is fully digital and is interfaced to a control and data-acquisition system in the aircraft via optical fiber. It is operable at temperatures of less than -30 degrees C and at typical cloud humidities. Preliminary data from the experiment show its utility for studies of the three-dimensional spatial distribution of cloud particles and ice crystal shapes.

  2. Digital electromagnetic telemetry system for studying behaviour of decapod crustaceans.

    PubMed

    Smith; Collins; Jensen

    2000-05-01

    1 year and the receiving system batteries are replaced by divers at intervals of up to 4 weeks. In field tests, crab (Cancer pagurus L.) and lobster (Homarus gammarus (L.)) activity was monitored at an artificial reef for 14 months. Examples of the type of information acquired are presented to illustrate the capabilities of the system and potential applications are discussed. Limitations of digital electromagnetic telemetry stem mainly from the short range of detection, the need for cables on the seabed and the size and shape of the transmitting tag. PMID:10742505

  3. Modern digital flight control system design for VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Broussard, J. R.; Berry, P. W.; Stengel, R. F.

    1979-01-01

    Methods for and results from the design and evaluation of a digital flight control system (DFCS) for a CH-47B helicopter are presented. The DFCS employed proportional-integral control logic to provide rapid, precise response to automatic or manual guidance commands while following conventional or spiral-descent approach paths. It contained altitude- and velocity-command modes, and it adapted to varying flight conditions through gain scheduling. Extensive use was made of linear systems analysis techniques. The DFCS was designed, using linear-optimal estimation and control theory, and the effects of gain scheduling are assessed by examination of closed-loop eigenvalues and time responses.

  4. Simulation of the High Performance Time to Digital Converter for the ATLAS Muon Spectrometer trigger upgrade

    NASA Astrophysics Data System (ADS)

    Meng, X. T.; Levin, D. S.; Chapman, J. W.; Zhou, B.

    2016-09-01

    The ATLAS Muon Spectrometer endcap thin-Resistive Plate Chamber trigger project compliments the New Small Wheel endcap Phase-1 upgrade for higher luminosity LHC operation. These new trigger chambers, located in a high rate region of ATLAS, will improve overall trigger acceptance and reduce the fake muon trigger incidence. These chambers must generate a low level muon trigger to be delivered to a remote high level processor within a stringent latency requirement of 43 bunch crossings (1075 ns). To help meet this requirement the High Performance Time to Digital Converter (HPTDC), a multi-channel ASIC designed by CERN Microelectronics group, has been proposed for the digitization of the fast front end detector signals. This paper investigates the HPTDC performance in the context of the overall muon trigger latency, employing detailed behavioral Verilog simulations in which the latency in triggerless mode is measured for a range of configurations and under realistic hit rate conditions. The simulation results show that various HPTDC operational configurations, including leading edge and pair measurement modes can provide high efficiency (>98%) to capture and digitize hits within a time interval satisfying the Phase-1 latency tolerance.

  5. Simulation of film media in motion picture production using a digital still camera

    NASA Astrophysics Data System (ADS)

    Bakke, Arne M.; Hardeberg, Jon Y.; Paul, Steffen

    2009-01-01

    The introduction of digital intermediate workflow in movie production has made visualization of the final image on the film set increasingly important. Images that have been color corrected on the set can also serve as a basis for color grading in the laboratory. In this paper we suggest and evaluate an approach that has been used to simulate the appearance of different film stocks. The GretagMacbeth Digital ColorChecker was captured using both a Canon EOS 20D camera as well as an analog camera. The film was scanned using an Arri film scanner. The images of the color chart were then used to perform a colorimetric characterization of these devices using models based on polynomial regression. By using the reverse model of the digital camera and the forward model of the analog film chain, the output of the film scanner was simulated. We also constructed a direct transformation using regression on the RGB values of the two devices. A different color chart was then used as a test set to evaluate the accuracy of the transformations, where the indirect model was found to provide the required performance for our purpose without compromising the flexibility of having an independent profile for each device.

  6. 77 FR 50727 - Configuration Management Plans for Digital Computer Software Used in Safety Systems of Nuclear...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... COMMISSION Configuration Management Plans for Digital Computer Software Used in Safety Systems of Nuclear... draft regulatory guide (DG), DG-1206, ``Configuration Management Plan for Digital Computer Software Used... Digital Computer Software Used in Safety Systems of Nuclear Power Plants'' is temporarily identified...

  7. Using Digital Globes to Explore the Deep Sea and Advance Public Literacy in Earth System Science

    ERIC Educational Resources Information Center

    Beaulieu, Stace E.; Emery, Emery; Brickley, Annette; Spargo, Abbey; Patterson, Kathleen; Joyce, Katherine; Silva, Tim; Madin, Katherine

    2015-01-01

    Digital globes are new technologies increasingly used in informal and formal education to display global datasets and show connections among Earth systems. But how effective are digital globes in advancing public literacy in Earth system science? We addressed this question by developing new content for digital globes with the intent to educate and…

  8. Stability and performance analysis of a jump linear control system subject to digital upsets

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Sun, Hui; Ma, Zhen-Yang

    2015-04-01

    This paper focuses on the methodology analysis for the stability and the corresponding tracking performance of a closed-loop digital jump linear control system with a stochastic switching signal. The method is applied to a flight control system. A distributed recoverable platform is implemented on the flight control system and subject to independent digital upsets. The upset processes are used to stimulate electromagnetic environments. Specifically, the paper presents the scenarios that the upset process is directly injected into the distributed flight control system, which is modeled by independent Markov upset processes and independent and identically distributed (IID) processes. A theoretical performance analysis and simulation modelling are both presented in detail for a more complete independent digital upset injection. The specific examples are proposed to verify the methodology of tracking performance analysis. The general analyses for different configurations are also proposed. Comparisons among different configurations are conducted to demonstrate the availability and the characteristics of the design. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61403395), the Natural Science Foundation of Tianjin, China (Grant No. 13JCYBJC39000), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Tianjin Key Laboratory of Civil Aircraft Airworthiness and Maintenance in Civil Aviation of China (Grant No. 104003020106), and the Fund for Scholars of Civil Aviation University of China (Grant No. 2012QD21x).

  9. Knowledge-based system for computer-aided process planning of laser sensor 3D digitizing

    NASA Astrophysics Data System (ADS)

    Bernard, Alain; Davillerd, Stephane; Sidot, Benoit

    1999-11-01

    This paper introduces some results of a research work carried out on the automation of digitizing process of complex part using a precision 3D-laser sensor. Indeed, most of the operations are generally still manual to perform digitalization. In fact, redundancies, lacks or forgetting in point acquisition are possible. Moreover, digitization time of a part, i.e. immobilization of the machine, is thus not optimized overall. So, it is important, for time- compression during product development, to minimize time consuming of reverse engineering step. A new way to scan automatically a complex 3D part is presented to order to measure and to compare the acquired data with the reference CAD model. After introducing digitization, the environment used for the experiments is presented, based on a CMM machine and a plane laser sensor. Then the proposed strategy is introduced for the adaptation of this environment to a robotic CAD software in order to be able to simulate and validate 3D-laser-scanning paths. The CAPP (Computer Aided Process Planning) system used for the automatic generation of the laser scanning process is also presented.

  10. Studies and simulations of the DigiCipher system

    NASA Technical Reports Server (NTRS)

    Sayood, K.; Chen, Y. C.; Kipp, G.

    1993-01-01

    During this period the development of simulators for the various high definition television (HDTV) systems proposed to the FCC was continued. The FCC has indicated that it wants the various proposers to collaborate on a single system. Based on all available information this system will look very much like the advanced digital television (ADTV) system with major contributions only from the DigiCipher system. The results of our simulations of the DigiCipher system are described. This simulator was tested using test sequences from the MPEG committee. The results are extrapolated to HDTV video sequences. Once again, some caveats are in order. The sequences used for testing the simulator and generating the results are those used for testing the MPEG algorithm. The sequences are of much lower resolution than the HDTV sequences would be, and therefore the extrapolations are not totally accurate. One would expect to get significantly higher compression in terms of bits per pixel with sequences that are of higher resolution. However, the simulator itself is a valid one, and should HDTV sequences become available, they could be used directly with the simulator. A brief overview of the DigiCipher system is given. Some coding results obtained using the simulator are looked at. These results are compared to those obtained using the ADTV system. These results are evaluated in the context of the CCSDS specifications and make some suggestions as to how the DigiCipher system could be implemented in the NASA network. Simulations such as the ones reported can be biased depending on the particular source sequence used. In order to get more complete information about the system one needs to obtain a reasonable set of models which mirror the various kinds of sources encountered during video coding. A set of models which can be used to effectively model the various possible scenarios is provided. As this is somewhat tangential to the other work reported, the results are included as an

  11. Experience with a proposed teleradiology system for digital mammography

    NASA Astrophysics Data System (ADS)

    Saulnier, Emilie T.; Mitchell, Robert J.; Abdel-Malek, Aiman A.; Dudding, Kathryn E.

    1995-05-01

    Teleradiology offers significant improvement in efficiency and effectiveness over current practices in traditional film/screen-based diagnosis. In the context of digital mammography, the increasing number of women who need to be screened for breast cancer, including those in remote rural regions, make the advantages of teleradiology especially attractive for digital mammography. At the same time, the size and resolution of digital mammograms are among the most challenging to support in a cost effective teleradiology system. This paper describes a teleradiology architecture developed for use with digital mammography by GE Corporate Research and Development in collaboration with Massachusetts General Hospital under National Cancer Institute (NCI/NIH) grant number R01 CA60246-01. Experience with a testbed prototype is described. The telemammography architecture is intended to consist of a main mammography diagnostic site serving several remote screening sites. As patient exams become available, they are forwarded by an image server to the diagnostic site over a WAN communications link. A radiologist at the diagnostic site views a patient exam as it arrives, interprets it, and then relays a report back to the technician at the remote site. A secondary future scenario consists of mobile units which forward images to a remote site, which then forwards them to the main diagnostic site. The testbed architecture is based on the Digital Imaging and Communications in Medicine (DICOM) standard, created by the American College of Radiology (ACR) and National Electrical Manufacturers Association (NEMA). A specification of vendor-independent data formats and data transfer services for digital medical images, DICOM specifies a protocol suite starting at the application layer downward, including the TCP/IP layers. The current DICOM definition does not provide an information element that is specifically tailored to mammography, so we have used the DICOM secondary capture data format

  12. A novel proposal of GPON-oriented fiber grating sensing data digitalization system for remote sensing network

    NASA Astrophysics Data System (ADS)

    Wang, Yubao; Zhu, Zhaohui; Wang, Lu; Bai, Jian

    2016-05-01

    A novel GPON-oriented sensing data digitalization system is proposed to achieve remote monitoring of fiber grating sensing networks utilizing existing optical communication networks in some harsh environments. In which, Quick digitalization of sensing information obtained from the reflected lightwaves by fiber Bragg grating (FBG) sensor is realized, and a novel frame format of sensor signal is designed to suit for public transport so as to facilitate sensor monitoring center to receive and analyze the sensor data. The delay effect, identification method of the sensor data, and various interference factors which influence the sensor data to be correctly received are analyzed. The system simulation is carried out with OptiSystem/Matlab co-simulation approach. The theoretical analysis and simulation results verify the feasibility of the integration of the sensor network and communication network.

  13. Flight tests of the Digital Integrated Automatic Landing System (DIALS)

    NASA Technical Reports Server (NTRS)

    Halyo, N.

    1984-01-01

    The design, development, implementation and flight tests of the Digital Integrated Automatic Landing System (DIALS) are discussed. The system was implemented and flight tested on the Transport Systems Research Vehicle (TSRV), a Boeing 737-100. The design uses modern optimal control methods. The direct digital design obtained uses a 10 Hz rate for the sampling of sensors and the control commands. The basic structure of the control law consists of a steady state Kalman filter followed by a control gain matrix. The sensor information used includes Microwave Landing System (MLS) position, attitude, calibrated airspeed, and body accelerations. The phases of the final approach considered are localized and steep glideslope capture (which may be performed simultaneously or independently), localizer and glideslope track, crab/decrab, and flare to touchdown. The system can capture, track, and flare from conventional, as well as steep, glideslopes ranging from 2.5 deg to 5.5 deg. All of the modes of the control law including the Kalman filters were implemented on the TSRV flight computers which use fixed point arithmetic with 16 bit words. The implementation considerations are described as well as an analysis of the flight test results.

  14. Reference manual for the Langley Research Center flight simulation computing system

    NASA Technical Reports Server (NTRS)

    Cleveland, J. I., II; Crawford, D. J.; Rowell, L. F.

    1978-01-01

    The researchers at the Langley Research Center Flight Simulation Computing System are provided with an advanced real-time digital simulation capability. This capability is controlled at the user interface level by the Real Time Simulation Supervisor. The Supervisor is a group of subprograms loaded with a simulation application program. The Supervisor provides the interface between the application program and the operating system, and coordinates input and output to and from the simulation hardware. The Supervisor also performs various utility functions as required by a simulation application program.

  15. Automatic exposure control for a slot scanning full field digital mammography system

    SciTech Connect

    Elbakri, Idris A.; Lakshminarayanan, A.V.; Tesic, Mike M.

    2005-09-15

    Automatic exposure control (AEC) is an important feature in mammography. It enables consistently optimal image exposure despite variations in tissue density and thickness, and user skill level. Full field digital mammography systems cannot employ conventional AEC methods because digital receptors fully absorb the x-ray beam. In this paper we describe an AEC procedure for slot scanning mammography. With slot scanning detectors, our approach uses a fast low-resolution and low-exposure prescan to acquire an image of the breast. Tube potential depends on breast thickness, and the prescan histogram provides the necessary information to calculate the required tube current. We validate our approach with simulated prescan images and phantom measurements. We achieve accurate exposure tracking with thickness and density, and expect this method of AEC to reduce retakes and improve workflow.

  16. Rain-fade simulation and power augmentation for satellite communication systems

    NASA Technical Reports Server (NTRS)

    Shalkhauser, Kurt A.; Nagy, Lawrence A.; Svoboda, James S.

    1990-01-01

    The design and implementation of an automated rain-fade simulation and power augmentation system is presented. The system experimentally simulates and measures the effects of radiofrequency power fade on a 20 GHz communication link using a multimode travelling wave tube amplifier for loss compensation. Precision, computer-controlled attenuators are used in the fade simulation. Test plans for analog and digital testing are discussed.

  17. Time Projection Chamber digitizer test system using a microcomputer

    SciTech Connect

    Nunnally, C.

    1980-10-01

    A small computer system for testing digitizers, control cards, and backplanes was developed at the Lawrence Berkeley Lab to be used in the Time Projection Chamber (TPC) Detector. The objective of this development was to provide a low cost test system for fast debugging, maintenance, a quality control by outside vendors who fabricated these units as well as Laboratory personnel. When the system was delivered to the vendors, it consisted of the computer programming and documentation necessary to do a complete checkout of approximately 20,000 signal channels. To obtain this low cost system (totaling $1400) a commercial microcomputer with 16K of memory and a printer (40 characters per line, 30 characters per second) were selected. This paper describes the overall test system and programming features including the linking capabilities of the debug program. It also describes the various interfacing techniques that were used to obtain hardcopies.

  18. Reverse Conversion Schemes for Signed-Digit Number Systems: A Survey

    NASA Astrophysics Data System (ADS)

    Chakraborty, Madhu Sudan

    2016-06-01

    Although signed-digit number systems have received a considerable attention, the transformation of signed-digit numbers back into the conventional forms, known as reverse conversion, is still a performance bottleneck of signed-digit arithmetic. In this paper, a literature survey of reverse conversion schemes for signed-digit number systems is performed on the basis of the articles published from recognized platforms for the past few decades. The survey reveals some specific problems of this field, which need further investigations.

  19. Design of a high-speed digital processing element for parallel simulation

    NASA Technical Reports Server (NTRS)

    Milner, E. J.; Cwynar, D. S.

    1983-01-01

    A prototype of a custom designed computer to be used as a processing element in a multiprocessor based jet engine simulator is described. The purpose of the custom design was to give the computer the speed and versatility required to simulate a jet engine in real time. Real time simulations are needed for closed loop testing of digital electronic engine controls. The prototype computer has a microcycle time of 133 nanoseconds. This speed was achieved by: prefetching the next instruction while the current one is executing, transporting data using high speed data busses, and using state of the art components such as a very large scale integration (VLSI) multiplier. Included are discussions of processing element requirements, design philosophy, the architecture of the custom designed processing element, the comprehensive instruction set, the diagnostic support software, and the development status of the custom design.

  20. Evaporating droplet hologram simulation for digital in-line holography setup with divergent beam.

    PubMed

    Méès, Loïc; Grosjean, Nathalie; Chareyron, Delphine; Marié, Jean-Louis; Seifi, Mozhdeh; Fournier, Corinne

    2013-10-01

    Generalized Lorenz-Mie theory (GLMT) for a multilayered sphere is used to simulate holograms produced by evaporating spherical droplets with refractive index gradient in the surrounding air/vapor mixture. Simulated holograms provide a physical interpretation of experimental holograms produced by evaporating Diethyl Ether droplets with diameter in the order of 50 μm and recorded in a digital in-line holography configuration with a divergent beam. Refractive index gradients in the surrounding medium lead to a modification of the center part of the droplet holograms, where the first fringe is unusually bright. GLMT simulations reproduce this modification well, assuming an exponential decay of the refractive index from the droplet surface to infinity. The diverging beam effect is also considered. In both evaporating and nonevaporating cases, an equivalence is found between Gaussian beam and plane wave illuminations, simply based on a magnification ratio to be applied to the droplets' parameters.

  1. A digital model for simulation of ground-water hydrology in the Houston area, Texas

    USGS Publications Warehouse

    Meyer, Walter R.; Carr, Jerry E.

    1979-01-01

    This report documents the construction and calibration of a digital model for the simulation of hydrologic conditions in the Chicot and Evangeline aquifers in the Houston area of southeastern Texas. The model is a five-layer finite-difference model, with a grid pattern of 63 x 67 nodes representing an area of 27,000 square miles, for simulation of three- dimensional ground-water flow. The hydrologic properties and processes modeled were ground-water withdrawals, transmissivities, storage coefficients of the aquifers and clays, quantity of water derived from storage in the clays, and vertical hydraulic conductivity and vertical leakage. The model, which simulates water-level declines, changes in storage in the clay layers, and land-surface subsidence, was calibrated by use of historical records from 1890 to 1975. It is very sensitive to variations in transmissivities and to variations in water-table and artesian storage. It is less sensitive to variations in clay storage.

  2. Application of digital computer APU modeling techniques to control system design.

    NASA Technical Reports Server (NTRS)

    Bailey, D. A.; Burriss, W. L.

    1973-01-01

    Study of the required controls for a H2-O2 auxiliary power unit (APU) technology program for the Space Shuttle. A steady-state system digital computer program was prepared and used to optimize initial system design. Analytical models of each system component were included. The program was used to solve a nineteen-dimensional problem, and then time-dependent differential equations were added to the computer program to simulate transient APU system and control. Some system parameters were considered quasi-steady-state, and others were treated as differential variables. The dynamic control analysis proceeded from initial ideal control modeling (which considered one control function and assumed the others to be ideal), stepwise through the system (adding control functions), until all of the control functions and their interactions were considered. In this way, the adequacy of the final control design over the required wide range of APU operating conditions was established.

  3. CASINO: A Small System Simulator

    ERIC Educational Resources Information Center

    Christensen, Borge

    1978-01-01

    This article is a tutorial on writing a simulator--the example used is a casino. The nontechnical, step by step approach is designed to enable even non-programmers to understand the design of such a simulation. (Author)

  4. Detection of simulated microcalcifications in digital mammography: effects of quantum and anatomic noises: preliminary study

    NASA Astrophysics Data System (ADS)

    Lai, Chao-Jen; Liu, Xinming; You, Zhicheng; Shen, Youtao; Zhong, Yuncheng; Chen, Lingyun; Han, Tao; Ge, Shuaiping; Yi, Ying; Geiser, William R.; Flores, David; Whitman, Gary J.; Yang, Wei T.; Shaw, Chris C.

    2010-04-01

    To study the effects of overlapping anatomy on microcalcification detection at various incident exposure levels. Images of an anthropomorphic breast phantom (RMI 169) overlapping with simulated microcalcifications ranging from 150 to 212 μm in size placed in two breast density regions, fatty and heterogeneously dense, were acquired with an a-Si/a-Se flat panel based digital mammography system (Selenia) operated with Mo-Mo target/filter combination at 28 kVp. The mammograms were exposed with 20, 30, 40, 60, 80, 120, 160, 240 and 325 mAs for varying the exposure level. A 4-AFC study was performed for evaluation of the detection performance. Four 400×400-pixel images were displayed as 2×2 array on a LCD flat panel based review workstation. One of the four images contained a cluster of five microcalcifications and was randomly placed in one of the four quadrants. A physicist was asked to select the image containing the microcalcifications and to report the number of visible microcalcifications. The fraction of correct responses was computed with two different criteria: (1) the selected images contained one or more microcalcifications, and (2) the selected images contained 4 or 5 visible microcalcifications. The statistical significance of the differences in fractions for different exposure levels and regions was evaluated. The results showed that, if visibility of one or more microcalcifications is required, the fractions of correct responses were 1 for all size groups and most exposure levels in both fatty and heterogeneously dense regions. If a visibility of 80% or more of the microcalcifications was required, the fractions of correct responses significantly decreased in both regions. The results indicated that microcalcification detection in the fatty region appeared to be mainly limited by the quantum noise, and that in the heterogeneously dense region may be limited by both the anatomic noise and the quantum noise.

  5. DDS: The Dental Diagnostic Simulation System.

    ERIC Educational Resources Information Center

    Tira, Daniel E.

    The Dental Diagnostic Simulation (DDS) System provides an alternative to simulation systems which represent diagnostic case studies of relatively limited scope. It may be used to generate simulated case studies in all of the dental specialty areas with case materials progressing through the gamut of the diagnostic process. The generation of a…

  6. A Real-Time Digital Cardiac Mapping System

    PubMed Central

    Francis, Robert J.; Parson, Ian; Vranesic, Zvonko G.

    1984-01-01

    A digital cardiac mapping system that provides a real-time display of ventricular activation is described. The proposed system is based on a hardware preprocessor that performs activation analysis in real-time, and a microcomputer host that produces an immediate and interactive animation of the cardiac activation sequence. The design of a prototype implementation of the system is presented. The preprocessor is capable of analysing cardiac electrograms to determine local activation times, with a temporal resolution of 1 ms, at 256 electrode sites. The prototype system provides on-line storage of local activation times for one half hour. The display features, which include forward and reverse animation, slow motion, different map formats, event marking and event search, are controlled by an interactive user interface.

  7. More on exact state reconstruction in deterministic digital control systems

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.

    1988-01-01

    Presented is a special form of the Ideal State Reconstructor for deterministic digital control systems which is simpler to implement than the most general form. The Ideal State Reconstructor is so named because, if the plant parameters are known exactly, its output will exactly equal, not just approximate, the true state of the plant and accomplish this without any knowledge of the plant's initial state. Besides this, it adds no new states or eigenvalues to the system. Nor does it affect the plant equation for the system in any way; it affects the measurement equation only. It is characterized by the fact that discrete measurements are generated every T/N seconds and input into a multi-input/multi-output moving-average (MA) process. The output of this process is sampled every T seconds and utilized in reconstructing the state of the system.

  8. A machine vision system for the calibration of digital thermometers

    NASA Astrophysics Data System (ADS)

    Vázquez-Fernández, Esteban; Dacal-Nieto, Angel; González-Jorge, Higinio; Martín, Fernando; Formella, Arno; Alvarez-Valado, Victor

    2009-06-01

    Automation is a key point in many industrial tasks such as calibration and metrology. In this context, machine vision has shown to be a useful tool for automation support, especially when there is no other option available. A system for the calibration of portable measurement devices has been developed. The system uses machine vision to obtain the numerical values shown by displays. A new approach based on human perception of digits, which works in parallel with other more classical classifiers, has been created. The results show the benefits of the system in terms of its usability and robustness, obtaining a success rate higher than 99% in display recognition. The system saves time and effort, and offers the possibility of scheduling calibration tasks without excessive attention by the laboratory technicians.

  9. The engineering design integration (EDIN) system. [digital computer program complex

    NASA Technical Reports Server (NTRS)

    Glatt, C. R.; Hirsch, G. N.; Alford, G. E.; Colquitt, W. N.; Reiners, S. J.

    1974-01-01

    A digital computer program complex for the evaluation of aerospace vehicle preliminary designs is described. The system consists of a Univac 1100 series computer and peripherals using the Exec 8 operating system, a set of demand access terminals of the alphanumeric and graphics types, and a library of independent computer programs. Modification of the partial run streams, data base maintenance and construction, and control of program sequencing are provided by a data manipulation program called the DLG processor. The executive control of library program execution is performed by the Univac Exec 8 operating system through a user established run stream. A combination of demand and batch operations is employed in the evaluation of preliminary designs. Applications accomplished with the EDIN system are described.

  10. Integrated source and channel encoded digital communications system design study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.

    1974-01-01

    Studies on the digital communication system for the direct communication links from ground to space shuttle and the links involving the Tracking and Data Relay Satellite (TDRS). Three main tasks were performed:(1) Channel encoding/decoding parameter optimization for forward and reverse TDRS links,(2)integration of command encoding/decoding and channel encoding/decoding; and (3) modulation coding interface study. The general communication environment is presented to provide the necessary background for the tasks and to provide an understanding of the implications of the results of the studies.

  11. Methods and systems for detecting abnormal digital traffic

    DOEpatents

    Goranson, Craig A [Kennewick, WA; Burnette, John R [Kennewick, WA

    2011-03-22

    Aspects of the present invention encompass methods and systems for detecting abnormal digital traffic by assigning characterizations of network behaviors according to knowledge nodes and calculating a confidence value based on the characterizations from at least one knowledge node and on weighting factors associated with the knowledge nodes. The knowledge nodes include a characterization model based on prior network information. At least one of the knowledge nodes should not be based on fixed thresholds or signatures. The confidence value includes a quantification of the degree of confidence that the network behaviors constitute abnormal network traffic.

  12. Space shuttle visual simulation system design study

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A recommendation and a specification for the visual simulation system design for the space shuttle mission simulator are presented. A recommended visual system is described which most nearly meets the visual design requirements. The cost analysis of the recommended system covering design, development, manufacturing, and installation is reported. Four alternate systems are analyzed.

  13. Dose assessment in contrast enhanced digital mammography using simple phantoms simulating standard model breasts

    NASA Astrophysics Data System (ADS)

    Bouwman, R. W.; van Engen, R. E.; Young, K. C.; Veldkamp, W. J. H.; Dance, D. R.

    2015-01-01

    Slabs of polymethyl methacrylate (PMMA) or a combination of PMMA and polyethylene (PE) slabs are used to simulate standard model breasts for the evaluation of the average glandular dose (AGD) in digital mammography (DM) and digital breast tomosynthesis (DBT). These phantoms are optimized for the energy spectra used in DM and DBT, which normally have a lower average energy than used in contrast enhanced digital mammography (CEDM). In this study we have investigated whether these phantoms can be used for the evaluation of AGD with the high energy x-ray spectra used in CEDM. For this purpose the calculated values of the incident air kerma for dosimetry phantoms and standard model breasts were compared in a zero degree projection with the use of an anti scatter grid. It was found that the difference in incident air kerma compared to standard model breasts ranges between -10% to +4% for PMMA slabs and between 6% and 15% for PMMA-PE slabs. The estimated systematic error in the measured AGD for both sets of phantoms were considered to be sufficiently small for the evaluation of AGD in quality control procedures for CEDM. However, the systematic error can be substantial if AGD values from different phantoms are compared.

  14. 47 CFR 74.795 - Digital low power TV and TV translator transmission system facilities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Digital low power TV and TV translator... DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.795 Digital low power TV and TV translator transmission system facilities. (a) A digital low power TV or TV translator station shall...

  15. 47 CFR 74.795 - Digital low power TV and TV translator transmission system facilities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Digital low power TV and TV translator... DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.795 Digital low power TV and TV translator transmission system facilities. (a) A digital low power TV or TV translator station shall...

  16. 47 CFR 74.795 - Digital low power TV and TV translator transmission system facilities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Digital low power TV and TV translator... DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.795 Digital low power TV and TV translator transmission system facilities. (a) A digital low power TV or TV translator station shall...

  17. Utilization of KSC Present Broadband Communications Data System For Digital Video Services

    NASA Technical Reports Server (NTRS)

    Andrawis, Alfred S.

    2001-01-01

    This report covers a visibility study of utilizing present KSC broadband communications data system (BCDS) for digital video services. Digital video services include compressed digital TV delivery and video-on-demand. Furthermore, the study examines the possibility of providing interactive video on demand to desktop personal computers via KSC computer network.

  18. Utilization of KSC Present Broadband Communications Data System for Digital Video Services

    NASA Technical Reports Server (NTRS)

    Andrawis, Alfred S.

    2002-01-01

    This report covers a visibility study of utilizing present KSC broadband communications data system (BCDS) for digital video services. Digital video services include compressed digital TV delivery and video-on-demand. Furthermore, the study examines the possibility of providing interactive video on demand to desktop personal computers via KSC computer network.

  19. 47 CFR 74.795 - Digital low power TV and TV translator transmission system facilities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Digital low power TV and TV translator... DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.795 Digital low power TV and TV translator transmission system facilities. (a) A digital low power TV or TV translator station shall...

  20. Semantically Enriching the Search System of a Music Digital Library

    NASA Astrophysics Data System (ADS)

    de Juan, Paloma; Iglesias, Carlos

    Traditional search systems are usually based on keywords, a very simple and convenient mechanism to express a need for information. This is the most popular way of searching the Web, although it is not always an easy task to accurately summarize a natural language query in a few keywords. Working with keywords means losing the context, which is the only thing that can help us deal with ambiguity. This is the biggest problem of keyword-based systems. Semantic Web technologies seem a perfect solution to this problem, since they make it possible to represent the semantics of a given domain. In this chapter, we present three projects, Harmos, Semusici and Cantiga, whose aim is to provide access to a music digital library. We will describe two search systems, a traditional one and a semantic one, developed in the context of these projects and compare them in terms of usability and effectiveness.