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Sample records for direct digital control

  1. Direct Digital Control Study.

    DTIC Science & Technology

    1985-02-01

    please attach additional pages to answer this question. 6. What is the "rule of thumb" used to calculate the number of DDC control loops and 1/0 points...I ’ : ’ ~ 2’, . Vkt ; .nw]i.<[[I’ S, ,ten,m Service Company would like to receive a copy of i I ication. Should additional information be required

  2. Direct Digital Control Liquid Level Experiment.

    ERIC Educational Resources Information Center

    Adb-El-Bary, M. F.

    1983-01-01

    Describes an experiment to give students exposure to digital control widely used in industry but not given much attention in most undergraduate process control curricula. Students write their own control programs and experimentally determine the transfer functions for all system components. Also describes experimental apparatus used in the…

  3. Numerically Controlled Phase Locked Loop Using Direct Digital Synthesizer

    SciTech Connect

    Pei, Alex

    1993-04-13

    A direct digital synthesizer is a highly stable digitally controlled frequency generator that outputs high spectrum purity rf signals. Because of the all digital design, it is immune to various environmental disturbances that plague conventional LC based VCOs. As a result, a PLL based on DDS can achieve high spectrum purity with very narrow tracking bandwidth.

  4. Direct drive digital servo press with high parallel control

    NASA Astrophysics Data System (ADS)

    Murata, Chikara; Yabe, Jun; Endou, Junichi; Hasegawa, Kiyoshi

    2013-12-01

    Direct drive digital servo press has been developed as the university-industry joint research and development since 1998. On the basis of this result, 4-axes direct drive digital servo press has been developed and in the market on April of 2002. This servo press is composed of 1 slide supported by 4 ball screws and each axis has linearscale measuring the position of each axis with high accuracy less than μm order level. Each axis is controlled independently by servo motor and feedback system. This system can keep high level parallelism and high accuracy even with high eccentric load. Furthermore the 'full stroke full power' is obtained by using ball screws. Using these features, new various types of press forming and stamping have been obtained by development and production. The new stamping and forming methods are introduced and 'manufacturing' need strategy of press forming with high added value and also the future direction of press forming are also introduced.

  5. Direct digital control of air washer cooling system

    SciTech Connect

    Elben, T.; Roseblock, R.; Lawler, R.; McCord, J.

    1990-01-01

    The purpose of this project was to make a practical evaluation of using new technology to extend the life of obsolete HVAC mechanical equipment. The specific exercises in this project involved the application of software driven control algorithms to operate and manage open loop air washer cooling systems in the air handling units located in the Municipal Auditorium in Kansas City, Missouri. The specific opportunity evaluated in this project involved eight air handling units at the Municipal Auditorium. The air handling systems utilize outdated air washer cooling systems that provide air conditioning and dehumidification to the areas they serve. We utilized direct digital control to assume total control of the operation of the air handling units. We also found it necessary to upgrade some components of the air handling units in order to allow the new control applications to execute their functions. This report describes the plan used to execute the project and the results. 20 tabs.

  6. 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.

  7. Randomized controlled trial comparing direct intraoral digitization and extraoral digitization after impression taking.

    PubMed

    Quaas, Sebastian; Loos, René; Rudolph, Heike; Luthardt, Ralph G

    2015-01-01

    This study aimed to evaluate the correspondence of intraoral digitization (ID) with extraoral digitization (ED) after impression taking. One-stage putty-and wash impressions and ID were carried out in a randomized order for 10 subjects. The impressions were used to make casts, which were then subjected to ED. ID datasets were aligned to create computer-aided design reference models. Deviations between ID and ED were calculated. The mean positive and negative deviations were 37.7 and -48.4 µm, respectively, for one quadrant. The results showed that the ID system is well suited for the acquisition of single-tooth restorations and is of limited suitability for the acquisition of small multiple unit restorations.

  8. Direct current pulse train actuation to enhance droplet control in digital microfluidics

    NASA Astrophysics Data System (ADS)

    Murran, Miguel A.; Najjaran, Homayoun

    2012-10-01

    The effective operation of a digital microfluidic (DMF) device depends on its ability to actuate droplets. Pulse width modulation of actuating signals (DC pulse train actuation) is proposed as a practical digital implementation and enhanced droplet manipulation technique. Experimental and simulation results demonstrate the efficacy of droplet incremental displacement and velocity control by modulating the width of each actuation pulse. This will in turn enable the control of the non-linear droplet transport dynamics to minimize droplet position overshoot, deformation, and fragmentation. As a result, DCPT actuation offers unparalleled control over droplet position and speed in DMF devices.

  9. Direct to Digital Holography

    SciTech Connect

    Bingham, P.R.; Tobin, K.W.

    2003-06-15

    In this CRADA, Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, development of the first prototype named the Visible Alpha Tool (VAT) that uses visible spectrum illumination of 532 nm, assist in design of second prototype tool named the DUV Alpha Tool (DAT) using deep UV (266 nm) illumination, and continuing support of nLine in the development of higher throughput commercial tools.

  10. Direct to Digital Holography

    SciTech Connect

    Bingham, P.R.; Tobin, K.W.

    2002-06-15

    In this CRADA, Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, testing of DDH for detection of defects in High Aspect Ratio (HAR) structures, development of image processing techniques to enhance detection capabilities through the use of both phase and intensity, and development of methods for autofocus on the DDH tools.

  11. Direct to Digital Holography

    SciTech Connect

    Bingham, P.R.; Tobin, K.W.

    2007-09-30

    In this Cooperative Research and Development Agreement (CRADA), Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, testing of DDH for detection of defects in High Aspect Ratio (HAR) structures, development of image processing techniques to enhance detection capabilities through the use of both phase and intensity, and development of methods for autofocus on the DDH tools.

  12. Doses under automatic exposure control (AEC) for direct digital radiographic (DDR) X-ray systems.

    PubMed

    Bowden, Louise; Faulkner, Ronan; Clancy, Conor; Gallagher, Aoife; Devine, Mark; Gorman, Dermot; O'Reilly, Geraldine; Dowling, Anita

    2011-09-01

    Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.

  13. Digital signal processing and control and estimation theory -- Points of tangency, area of intersection, and parallel directions

    NASA Technical Reports Server (NTRS)

    Willsky, A. S.

    1976-01-01

    A number of current research directions in the fields of digital signal processing and modern control and estimation theory were studied. Topics such as stability theory, linear prediction and parameter identification, system analysis and implementation, two-dimensional filtering, decentralized control and estimation, image processing, and nonlinear system theory were examined in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the two disciplines. An extensive bibliography is included.

  14. Reconfigurable multivariable control law for commercial airplane using a direct digital output feedback design

    NASA Technical Reports Server (NTRS)

    Ostroff, A. J.; Hueschen, R. M.

    1984-01-01

    The ability of a pilot to reconfigure the control surfaces on an airplane after a failure, allowing the airplane to recover to a safe condition for landing, becomes more difficult with increasing airplane complexity. Techniques are needed to stabilize and control the airplane immediately after a failure, allowing the pilot time to make longer range decisions. This paper shows a design of a discrete multivariable control law using four controls for the longitudinal channel of a B-737. Single control element failures are allowed in three of the four controls. The four controls design and failure cases are analyzed by means of a digital airplane simulation, with regard to tracking capability and ability to overcome severe windshear and turbulence during the aproach and landing phase of flight.

  15. Demand Controlled Economizer Cycles: A Direct Digital Control Scheme for Heating, Ventilating, and Air Conditioning Systems,

    DTIC Science & Technology

    1984-05-01

    includes a heating coil and thermostatic control to maintain the air in this path at an elevated temperature, typically around 80 degrees Farenheit (80 F...1238 Aug 1 1236 1237 52 1074 1126 50 1033 1083 Sep 8 8 5W 862 7T 600 678 75 603 7r Oct 51 400 451 119 204 323 115 207 322 ov 64 123 287 187 71 258

  16. Digital numerically controlled oscillator

    NASA Technical Reports Server (NTRS)

    Cellier, A.; Huey, D. C.; Ma, L. N. (Inventor)

    1980-01-01

    The frequency and phase of an output signal from an oscillator circuit are controlled with accuracy by a digital input word. Positive and negative alterations in output frequency are both provided for by translating all values of input words so that they are positive. The oscillator reference frequency is corrected only in one direction, by adding phase to the output frequency of the oscillator. The input control word is translated to a single algebraic sign and the digital 1 is added thereto. The translated input control word is then accumulated. A reference clock signal having a frequency at an integer multiple of the desired frequency of the output signal is generated. The accumulated control word is then compared with a threshold level. The output signal is adjusted in a single direction by dividing the frequency of the reference clock signal by a first integer or by an integer different from the first integer.

  17. 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.

  18. Rewritable digital data storage in live cells via engineered control of recombination directionality

    PubMed Central

    Bonnet, Jerome; Subsoontorn, Pakpoom; Endy, Drew

    2012-01-01

    The use of synthetic biological systems in research, healthcare, and manufacturing often requires autonomous history-dependent behavior and therefore some form of engineered biological memory. For example, the study or reprogramming of aging, cancer, or development would benefit from genetically encoded counters capable of recording up to several hundred cell division or differentiation events. Although genetic material itself provides a natural data storage medium, tools that allow researchers to reliably and reversibly write information to DNA in vivo are lacking. Here, we demonstrate a rewriteable recombinase addressable data (RAD) module that reliably stores digital information within a chromosome. RAD modules use serine integrase and excisionase functions adapted from bacteriophage to invert and restore specific DNA sequences. Our core RAD memory element is capable of passive information storage in the absence of heterologous gene expression for over 100 cell divisions and can be switched repeatedly without performance degradation, as is required to support combinatorial data storage. We also demonstrate how programmed stochasticity in RAD system performance arising from bidirectional recombination can be achieved and tuned by varying the synthesis and degradation rates of recombinase proteins. The serine recombinase functions used here do not require cell-specific cofactors and should be useful in extending computing and control methods to the study and engineering of many biological systems. PMID:22615351

  19. Users Guide to Direct Digital Control of Heating, Ventilating, and Air Conditioning Equipment,

    DTIC Science & Technology

    1985-01-01

    feet downstream from the damper. For most HVAC applications, PI control is an adequate control technique. A more detailed description of PID control is...dectricityU nt Figure 13. Comparison of energy consumption of two HVAC Systems with PI Control . (Ref 2) 26 Conventional Built-up Control System, Control

  20. Precision digital control systems

    NASA Astrophysics Data System (ADS)

    Vyskub, V. G.; Rozov, B. S.; Savelev, V. I.

    This book is concerned with the characteristics of digital control systems of great accuracy. A classification of such systems is considered along with aspects of stabilization, programmable control applications, digital tracking systems and servomechanisms, and precision systems for the control of a scanning laser beam. Other topics explored are related to systems of proportional control, linear devices and methods for increasing precision, approaches for further decreasing the response time in the case of high-speed operation, possibilities for the implementation of a logical control law, and methods for the study of precision digital control systems. A description is presented of precision automatic control systems which make use of electronic computers, taking into account the existing possibilities for an employment of computers in automatic control systems, approaches and studies required for including a computer in such control systems, and an analysis of the structure of automatic control systems with computers. Attention is also given to functional blocks in the considered systems.

  1. Direct Digital Boiler Control Systems for the Navy Small Boiler Equipment.

    DTIC Science & Technology

    1983-02-01

    codes , parity and dropout checks, check sums, high level data link control (HDLC) and keyboard response checking. 3. Display types-Typical are overview...Distributed Control can be cost-effective for as few as 8 control loops. Operator Mini-Station: Video Display The high scan-rate CRT otters a corn... high ana "* low alarm limits, the configurationfication-automatic ("A") or manual data than a Group Display (and is re- code and the filter time

  2. Direct digital conversion detector technology

    NASA Astrophysics Data System (ADS)

    Mandl, William J.; Fedors, Richard

    1995-06-01

    Future imaging sensors for the aerospace and commercial video markets will depend on low cost, high speed analog-to-digital (A/D) conversion to efficiently process optical detector signals. Current A/D methods place a heavy burden on system resources, increase noise, and limit the throughput. This paper describes a unique method for incorporating A/D conversion right on the focal plane array. This concept is based on Sigma-Delta sampling, and makes optimum use of the active detector real estate. Combined with modern digital signal processors, such devices will significantly increase data rates off the focal plane. Early conversion to digital format will also decrease the signal susceptibility to noise, lowering the communications bit error rate. Computer modeling of this concept is described, along with results from several simulation runs. A potential application for direct digital conversion is also reviewed. Future uses for this technology could range from scientific instruments to remote sensors, telecommunications gear, medical diagnostic tools, and consumer products.

  3. Digital Control For Remote Manipulators

    NASA Technical Reports Server (NTRS)

    Bejczy, Antal K.; Dotson, Ronald S.

    1987-01-01

    Multiple microprocessors enable large separations between controllers and manipulators. Controller for remote manipulator requires no direct mechanical connection between slave arm and master arm moved by human operator. Employs two-way digital data transmission rather than mechanical linkage between master and slave. Manipulator a considerable distance from operator. Software for controller distributed between master and slave locations. Organized into modules. Hardware and software for system demonstrated in laboratory model.

  4. Programmable Digital Controller

    NASA Technical Reports Server (NTRS)

    Wassick, Gregory J.

    2012-01-01

    An existing three-channel analog servo loop controller has been redesigned for piezoelectric-transducer-based (PZT-based) etalon control applications to a digital servo loop controller. This change offers several improvements over the previous analog controller, including software control over proportional-integral-derivative (PID) parameters, inclusion of other data of interest such as temperature and pressure in the control laws, improved ability to compensate for PZT hysteresis and mechanical mount fluctuations, ability to provide pre-programmed scanning and stepping routines, improved user interface, expanded data acquisition, and reduced size, weight, and power.

  5. Direct qualification of digital components

    SciTech Connect

    Lawrence, J. D., LLNL

    1998-07-08

    Existing methods for qualifying digital system software for use in safety critical systems are expensive and are based on inferences that are of doubtful validity. This report on work-in-progress describes a new approach to qualifying a class of small safety systems that can meet a number of design restrictions, where the restrictions are carefully crafted to permit safety qualification to be determined by means of static analysis of the software combined with a limited amount of testing. This approach differs from attempts to qualify unrestricted programs in the general case. Work that has been accomplished towards this goal is discussed in summary terms. The technique relies on transforming a program into a form of directed graph known as a flowgraph. Existing testing theory is used, sometimes with minor modifications, to derive a set of design restrictions that permit reasoning about safety properties of the program, based on analysis and limited testing. Future work required to complete the research is outlined.

  6. 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.

  7. Digital Optical Control System

    NASA Astrophysics Data System (ADS)

    Jordan, David H.; Tipton, Charles A.; Christmann, Charles E.; Hochhausler, Nils P.

    1988-09-01

    We describe the digital optical control system (DOGS), a state-of-the-art controller for electrical feedback in an optical system. The need for a versatile optical controller arose from a number of unique experiments being performed by the Air Force Weapons Laboratory. These experiments use similar detectors and actuator-controlled mirrors, but the control requirements vary greatly. The experiments have in common a requirement for parallel control systems. The DOGS satisfies these needs by allowing several control systems to occupy a single chassis with one master controller. The architecture was designed to allow upward compatibility with future configurations. Combinations of off-the-shelf and custom boards are configured to meet the requirements of each experiment. The configuration described here was used to control piston error to X/80 at a wavelength of 0.51 Am. A peak sample rate of 8 kHz, yielding a closed loop bandwidth of 800 Hz, was achieved.

  8. Research in digital adaptive flight controllers

    NASA Technical Reports Server (NTRS)

    Kaufman, H.

    1976-01-01

    A design study of adaptive control logic suitable for implementation in modern airborne digital flight computers was conducted. Both explicit controllers which directly utilize parameter identification and implicit controllers which do not require identification were considered. Extensive analytical and simulation efforts resulted in the recommendation of two explicit digital adaptive flight controllers. Interface weighted least squares estimation procedures with control logic were developed using either optimal regulator theory or with control logic based upon single stage performance indices.

  9. 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.

  10. Directions for Defense Digital Libraries.

    ERIC Educational Resources Information Center

    Larsen, Ronald L.

    1998-01-01

    Describes directions, challenges, and objectives of the information management program of the United States Defense Advanced Research Projects Agency (DARPA). The program envisions the rigor and organization normally associated with a research library to be virtually rendered and extended in the networked world of distributed information. (AEF)

  11. Directions for Defense Digital Libraries.

    ERIC Educational Resources Information Center

    Larsen, Ronald L.

    1998-01-01

    Describes directions, challenges, and objectives of the information management program of the United States Defense Advanced Research Projects Agency (DARPA). The program envisions the rigor and organization normally associated with a research library to be virtually rendered and extended in the networked world of distributed information. (AEF)

  12. Cyber Enabled Direct Digital Manufacturing

    DTIC Science & Technology

    2015-05-15

    binary file formats , it is difficult or impossible for operators and modelers to determine how a part was actually produced. Without essential process...open-access AMSF file format (Nassar and Reutzel, 2013) to enable automatic specification and extraction of processing parameters for a variety of...Using the established AMSF file format ,, the authors have developed and demonstrated two approaches for direct integration of AM processes with

  13. Digital Fire Control Systems Support

    DTIC Science & Technology

    2012-09-27

    Systems ( DFCS ) for the M119A2 and M777A2. The DFCS is a fully integrated digital fire control system that has weapon platform application to the...Lightweight 155 mm (LW155) Towed Howitzer and the M119A2 Lightweight 105mm Towed Howitzer. 15. SUBJECT TERMS Digital Fire Control Systems ( DFCS ) 16...Joint Lightweight 155, has been tasked to develop and maintain the Digital Fire Control Systems ( DFCS ) for the M119A2 and M777A2. The DFCS is a fully

  14. Digital control of HVDC converters

    SciTech Connect

    Pilotto, L.A.S.; Roitman, M.; Alves, J.E.R.

    1989-05-01

    This paper presents the project of a completely digital HVDC converter controller based on a 16-bit microcomputer. It was decided to achieve as much as possible by software in order to minimize functions performed by external hardware. The presented design comprises software programmed functions such as a PID current control amplifier, voltage dependent current order limiters and an alpha-minimum symmetrization unit, among others. HVDC control principles are briefly reviewed and a detailed description of both the hardware and software structure of the controller is presented. The digital controller was implemented in an HVDC simulator and several dynamic performance tests demonstrated the efficiency of the proposed methodology.

  15. Full-field direct digital telemammography: preliminary

    NASA Astrophysics Data System (ADS)

    Lou, Shyhliang A.; Sickles, Edward A.; Huang, H. K.; Cao, Fei; Hoogstrate, David R.; Jahangiri, Mohammad I.

    1997-05-01

    Full-field direct digital mammography has many advantages over the conventional film/screen imaging detector. Among these are larger dynamic range, lower scattering noise, and the possibility of using it for telemammography applications to alleviate the shortage of expert mammographers. We are in the process of developing a full-field direct digital telemammography imaging chain to investigate its usefulness for telediagnosis, teleconsultation, and telemanagement. This paper describes the first phase of a three-year research program to set up a full-field direct digital mammography (FFDDM) imaging chain at the Breast Imaging Section connecting the University of California, San Francisco Medical Center and the Mt. Zion Hospital in the San Francisco Bay area. The chain consists of two FFDDM system, and two 2,500 line two-monitor workstations. An OC-3 155 Mbits/sec asynchronous transfer mode (ATM) communication network is used to connect the FFDDM and the two workstations. The FFDDM is based on a slot scan CCD detector which can image a full breast with 3,100 X 3,870 pixels, and produce a direct digital image with 50 micron pixel size. Preliminary results of the FFDDM demonstrate that it has a greater dynamic range and lower detector noise than that of a film-screen detector, and that the scattered radiation is reduced without using a grid. However, the spatial resolution is less than that of the conventional screen/film system. The 2K workstation can display simultaneously any two or four full-view mammographic images by either scrolling or subsampling on the two monitors. Display of an image takes about 1.5 seconds from the RAID disks. The ATM can transmit a 32 Mbyte digital mammogram from the FFDDM to the workstation in 3-4 seconds.

  16. Digitally controlled distributed phase shifter

    DOEpatents

    Hietala, Vincent M.; Kravitz, Stanley H.; Vawter, Gregory A.

    1993-01-01

    A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one or two discrete bias voltages. The application of the discrete bias voltages changes the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

  17. Digitally controlled distributed phase shifter

    DOEpatents

    Hietala, V.M.; Kravitz, S.H.; Vawter, G.A.

    1993-08-17

    A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one or two discrete bias voltages. The application of the discrete bias voltages changes the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

  18. Digitally controlled distributed phase shifter

    SciTech Connect

    Hietala, V.M.; Kravitz, S.H.; Vawter, G.A.

    1992-12-31

    A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one of two discrete bias voltages. The application of the discrete bias voltages change the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

  19. Direct-to-digital holography and holovision

    DOEpatents

    Thomas, Clarence E.; Baylor, Larry R.; Hanson, Gregory R.; Rasmussen, David A.; Voelkl, Edgar; Castracane, James; Simkulet, Michelle; Clow, Lawrence

    2000-01-01

    Systems and methods for direct-to-digital holography are described. An apparatus includes a laser; a beamsplitter optically coupled to the laser; a reference beam mirror optically coupled to the beamsplitter; an object optically coupled to the beamsplitter, a focusing lens optically coupled to both the reference beam mirror and the object; and a digital recorder optically coupled to the focusing lens. A reference beam is incident upon the reference beam mirror at a non-normal angle, and the reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form an image. The systems and methods provide advantages in that computer assisted holographic measurements can be made.

  20. Image rejects in general direct digital radiography

    PubMed Central

    Rosanowsky, Tine Blomberg; Jensen, Camilla; Wah, Kenneth Hong Ching

    2015-01-01

    Background The number of rejected images is an indicator of image quality and unnecessary imaging at a radiology department. Image reject analysis was frequent in the film era, but comparably few and small studies have been published after converting to digital radiography. One reason may be a belief that rejects have been eliminated with digitalization. Purpose To measure the extension of deleted images in direct digital radiography (DR), in order to assess the rates of rejects and unnecessary imaging and to analyze reasons for deletions, in order to improve the radiological services. Material and Methods All exposed images at two direct digital laboratories at a hospital in Norway were reviewed in January 2014. Type of examination, number of exposed images, and number of deleted images were registered. Each deleted image was analyzed separately and the reason for deleting the image was recorded. Results Out of 5417 exposed images, 596 were deleted, giving a deletion rate of 11%. A total of 51.3% were deleted due to positioning errors and 31.0% due to error in centering. The examinations with the highest percentage of deleted images were the knee, hip, and ankle, 20.6%, 18.5%, and 13.8% respectively. Conclusion The reject rate is at least as high as the deletion rate and is comparable with previous film-based imaging systems. The reasons for rejection are quite different in digital systems. This falsifies the hypothesis that digitalization would eliminates rejects. A deleted image does not contribute to diagnostics, and therefore is an unnecessary image. Hence, the high rates of deleted images have implications for management, training, education, as well as for quality. PMID:26500784

  1. Image rejects in general direct digital radiography.

    PubMed

    Hofmann, Bjørn; Rosanowsky, Tine Blomberg; Jensen, Camilla; Wah, Kenneth Hong Ching

    2015-10-01

    The number of rejected images is an indicator of image quality and unnecessary imaging at a radiology department. Image reject analysis was frequent in the film era, but comparably few and small studies have been published after converting to digital radiography. One reason may be a belief that rejects have been eliminated with digitalization. To measure the extension of deleted images in direct digital radiography (DR), in order to assess the rates of rejects and unnecessary imaging and to analyze reasons for deletions, in order to improve the radiological services. All exposed images at two direct digital laboratories at a hospital in Norway were reviewed in January 2014. Type of examination, number of exposed images, and number of deleted images were registered. Each deleted image was analyzed separately and the reason for deleting the image was recorded. Out of 5417 exposed images, 596 were deleted, giving a deletion rate of 11%. A total of 51.3% were deleted due to positioning errors and 31.0% due to error in centering. The examinations with the highest percentage of deleted images were the knee, hip, and ankle, 20.6%, 18.5%, and 13.8% respectively. The reject rate is at least as high as the deletion rate and is comparable with previous film-based imaging systems. The reasons for rejection are quite different in digital systems. This falsifies the hypothesis that digitalization would eliminates rejects. A deleted image does not contribute to diagnostics, and therefore is an unnecessary image. Hence, the high rates of deleted images have implications for management, training, education, as well as for quality.

  2. Space Digital Controller for Improved Motor Control

    NASA Astrophysics Data System (ADS)

    Alves-Nunes, Samuel; Daras, Gaetan; Dehez, Bruno; Maillard, Christophe; Bekemans, Marc; Michel, Raymond

    2014-08-01

    Performing digital motor control into space equipment is a new challenge. The new DPC (Digital Programmable Controller) is the first chip that we can use as a micro-controller, allowing us to drive motors with digital control schemes. In this paper, the digital control of hybrid stepper motors is considered. This kind of motor is used for solar array rotation and antenna actuation. New digital control technology brings a lot of advantages, allowing an important reduction of thermal losses inside the motor, and a reduction of thermal constraints on power drive electronic components. The opportunity to drive motors with a digital controller also brings many new functionalities like post-failure torque analysis, micro- vibrations and cogging torque reduction, or electro- mechanical damping of solar array oscillations. To evaluate the performance of the system, Field-Oriented Control (FOC) is implemented on a hybrid stepper motor. A test-bench, made of an active load, has been made to emulate the mechanical behaviour of the solar array, by the use of a torsionally-compliant model. The experimental results show that we can drastically reduce electrical power consumption, compared with the currently used open-loop control scheme.

  3. All digital pulsewidth control loop

    NASA Astrophysics Data System (ADS)

    Huang, Hong-Yi; Jan, Shiun-Dian; Pu, Ruei-Iun

    2013-03-01

    This work presents an all-digital pulsewidth control loop (ADPWCL). The proposed system accepts a wide range of input duty cycles and performs a fast correction to the target output pulsewidth. An all-digital delay-locked loop (DLL) with fast locking time using a simplified time to digital converter and a new differential two-step delay element is proposed. The area of the delay element is much smaller than that in conventional designs, while having the same delay range. A test chip is verified in a 0.18-µm CMOS process. The measured duty cycle ranges from 4% to 98% with 7-bit resolution.

  4. Demonstration of thermal control, microstructure control, defect mitigation and process parameter database generation for Ti-6Al-4V Direct Digital Manufacturing - Understanding defect mitigation and process parameter database generation for direct digital manufacturing

    SciTech Connect

    Dehoff, Ryan R.; Sridharan, Niyanth; Dinwiddie, Ralph; Robson, Alan; Jordan, Brian; Chaudhary, Anil; Babu, Sudarsanam Suresh

    2015-09-01

    Researchers from Manufacturing Demonstration Facility (MDF) at Oak Ridge National Laboratory (ORNL) worked with Applied Optimization (AO) to understand and evaluate the propensity for defect formation in builds manufactured using DM3D-POM laser direct metal deposition. The main aim of this collaboration was to understand the character of powder jet behavior as a function of the nozzle parameters such as cover gas, carrier gas, and shaping gas. In order to evaluate the sensitivities of the parameters used in model, various experiments were performed with in-situ monitoring of the powder stream characteristics using a high speed camera. A wide variety of conditions while keeping the hopper motor rpm constant, including laser power and travel speed were explored. The cross sections of the deposits were characterized using optical microscopy.

  5. Reject analysis in direct digital radiography.

    PubMed

    Andersen, Eivind Richter; Jorde, Jannike; Taoussi, Nadia; Yaqoob, Sadia Halima; Konst, Bente; Seierstad, Therese

    2012-03-01

    Reject analysis can be used as a quality indicator, and is an important tool in localizing areas where optimization is required. Reducing number of rejects is important yielding reduced patient exposure and increased cost-effectiveness. To determine rejection rates and causes in direct digital radiography. Data were collected during a three-month period in spring 2010 at two direct digital laboratories in Norway. All X-ray examinations, types, numbers, and reasons for rejections were obtained using automatic reject analysis software. Thirteen causes for rejection could be selected. Out of the 27,284 acquired images, 3206 were rejected, yielding an overall rejection rate of 12%. Highest rejection rates were found for examination of knees, shoulders, and wrist. In all, 77% of the rejected images arose from positioning errors. An overall rejection rate of 12% indicates a need for optimizing radiographic practice in the department.

  6. 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.

  7. Digital Controller For Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Tarver, D. Kent

    1989-01-01

    Acoustic driver digitally controls sound fields along three axes. Allows computerized acoustic levitation and manipulation of small objects for such purposes as containerless processing and nuclear-fusion power experiments. Also used for controlling motion of vibration-testing tables in three dimensions.

  8. Polaroid Graphics Imaging Direct Digital Color Proofing

    NASA Astrophysics Data System (ADS)

    King, Patrick F.

    1989-04-01

    Good morning ladies and gentlemen. I represent Polaroid Graphics Imaging, a wholly owned subsidiary of the Polaroid Corporation. We wish to thank Ken Cloud and the SPIE for the opportunity to speak today. Several criterion are fundamental in the role for Direct Digital Color Proofing (DDCP), First, the DDCP must represent a first generation hardcopy of the exact color information in the production stream. If must, as it's name suggests be an exact, proof (hence the name direct) of the electronic or digital information which would otherwise be directed toward film working. It is after all the most critical means to evaluate the quality of whatever pagination, scanner or color work which has gone be for it. Second, the DDCP must represent an opportunity. That opportunity is to reconvene the production stream and move to film making, optical or magnetic storage, or satellite transmission with the confidence that the DDCP is identical to some conventional counterpart. In the case of film it must match a conventional proof and press sheet, dot for dot. Otherwise it is merely an exercise in interpretation. For magnetic or optical storage and satellite transmission there must be assurance that at any opportunity either a duplicate DDCP or a conventional film/proof could reproduce earlier results. Finally as the printed product is the final goal and direct to press is evolving in direct to plate and direct to gravure printing the DDCP must share the half toner lineage of these products. Thirdly and hardly least, the whole purpose for DDCP is increased productivity. However, our industry struggles to maintain individuality and variety. Somehow DDCP must balance these forces.

  9. Personalized direct marketing using digital publishing

    NASA Astrophysics Data System (ADS)

    Kutty, Cheeniyil L.; Prabhakaran, Jayasree K.

    2006-02-01

    In today's cost-conscious business climate, marketing and customer service decision makers are increasingly concerned with how to increase customer response and retention rates. Companies spend large amounts of money on Customer Relationship Management (CRM) solutions and data acquisition but they don't know how to use the information stored in these systems to improve the effectiveness of their direct marketing campaigns. By leveraging the customer information they already have, companies can create personalized, printed direct mail programs that generate high response rates, greater returns, and stronger customer loyalty, while gaining a significant edge over their competitors. To reach the promised land of one-to-one direct marketing (personalized direct marketing - PDM), companies need an end-to-end solution for creating, managing, printing, and distributing personalized direct mail "on demand." Having access to digital printing is just one piece of the solution. A more complete approach includes leveraging personalization technology into a useful direct marketing tool that provides true one-to-one marketing, allowing variable images and text in a personalized direct mail. This paper discusses integration of CRM with a Print-on-Demand solution so as to create truly personalized printed marketing campaigns for one or many individuals based on the profile information, preferences and purchase history stored in the CRM.

  10. Digitally controlled sonars

    NASA Technical Reports Server (NTRS)

    Hansen, G. R.

    1983-01-01

    Sonars are usually designed and constructed as stand alone instruments. That is, all elements or subsystems of the sonar are provided: power conditioning, displays, intercommunications, control, receiver, transmitter, and transducer. The sonars which are a part of the Advanced Ocean Test Development Platform (AOTDP) represent a departure from this manner of implementation and are configured more like an instrumentation system. Only the transducer, transmitter, and receiver which are unique to a particular sonar function; Up, Down, Side Scan, exist as separable subsystems. The remaining functions are reserved to the AOTDP and serve all sonars and other instrumentation in a shared manner. The organization and functions of the common AOTDP elements were described and then the interface with the sonars discussed. The techniques for software control of the sonar parameters were explained followed by the details of the realization of the sonar functions and some discussion of the performance of the side scan sonars.

  11. Digitally controlled sonars

    NASA Technical Reports Server (NTRS)

    Hansen, G. R.

    1983-01-01

    Sonars are usually designed and constructed as stand alone instruments. That is, all elements or subsystems of the sonar are provided: power conditioning, displays, intercommunications, control, receiver, transmitter, and transducer. The sonars which are a part of the Advanced Ocean Test Development Platform (AOTDP) represent a departure from this manner of implementation and are configured more like an instrumentation system. Only the transducer, transmitter, and receiver which are unique to a particular sonar function; Up, Down, Side Scan, exist as separable subsystems. The remaining functions are reserved to the AOTDP and serve all sonars and other instrumentation in a shared manner. The organization and functions of the common AOTDP elements were described and then the interface with the sonars discussed. The techniques for software control of the sonar parameters were explained followed by the details of the realization of the sonar functions and some discussion of the performance of the side scan sonars.

  12. Application of QC_DR software for acceptance testing and routine quality control of direct digital radiography systems: initial experiences using the Italian Association of Physicist in Medicine quality control protocol.

    PubMed

    Nitrosi, Andrea; Bertolini, Marco; Borasi, Giovanni; Botti, Andrea; Barani, Adriana; Rivetti, Stefano; Pierotti, Luisa

    2009-12-01

    Ideally, medical x-ray imaging systems should be designed to deliver maximum image quality at an acceptable radiation risk to the patient. Quality assurance procedures are employed to ensure that these standards are maintained. A quality control protocol for direct digital radiography (DDR) systems is described and discussed. Software to automatically process and analyze the required images was developed. In this paper, the initial results obtained on equipment of different DDR manufacturers were reported. The protocol was developed to highlight even small discrepancies in standard operating performance.

  13. Digital electronic engine control history

    NASA Technical Reports Server (NTRS)

    Putnam, T. W.

    1984-01-01

    Full authority digital electronic engine controls (DEECs) were studied, developed, and ground tested because of projected benefits in operability, improved performance, reduced maintenance, improved reliability, and lower life cycle costs. The issues of operability and improved performance, however, are assessed in a flight test program. The DEEC on a F100 engine in an F-15 aircraft was demonstrated and evaluated. The events leading to the flight test program are chronicled and important management and technical results are identified.

  14. Centralized digital control of accelerators

    SciTech Connect

    Melen, R.E.

    1983-09-01

    In contrasting the title of this paper with a second paper to be presented at this conference entitled Distributed Digital Control of Accelerators, a potential reader might be led to believe that this paper will focus on systems whose computing intelligence is centered in one or more computers in a centralized location. Instead, this paper will describe the architectural evolution of SLAC's computer based accelerator control systems with respect to the distribution of their intelligence. However, the use of the word centralized in the title is appropriate because these systems are based on the use of centralized large and computationally powerful processors that are typically supported by networks of smaller distributed processors.

  15. Digital Controller For Emergency Beacon

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    1990-01-01

    Prototype digital controller intended for use in 406-MHz emergency beacon. Undergoing development according to international specifications, 406-MHz emergency beacon system includes satellites providing worldwide monitoring of beacons, with Doppler tracking to locate each beacon within 5 km. Controller turns beacon on and off and generates binary codes identifying source (e.g., ship, aircraft, person, or vehicle on land). Codes transmitted by phase modulation. Knowing code, monitor attempts to communicate with user, monitor uses code information to dispatch rescue team appropriate to type and locations of carrier.

  16. Digital adaptive flight controller development

    NASA Technical Reports Server (NTRS)

    Kaufman, H.; Alag, G.; Berry, P.; Kotob, S.

    1974-01-01

    A design study of adaptive control logic suitable for implementation in modern airborne digital flight computers was conducted. Two designs are described for an example aircraft. Each of these designs uses a weighted least squares procedure to identify parameters defining the dynamics of the aircraft. The two designs differ in the way in which control law parameters are determined. One uses the solution of an optimal linear regulator problem to determine these parameters while the other uses a procedure called single stage optimization. Extensive simulation results and analysis leading to the designs are presented.

  17. Digital electrospray for controlled deposition.

    PubMed

    Deng, Weiwei; Waits, C Mike; Gomez, Alessandro

    2010-03-01

    Many novel functional structures are now fabricated by controlled deposition as a maskless, bottom-up fabrication technique. These applications require rapid and precise deposition of minute amounts of solutions/suspensions or their ultimate particle products in predefined patterns. The electrospray is a promising alternative to the commonly used inkjet printing because it can easily handle highly viscous liquid, avoid high shear rates, and has low risk of clogging. We demonstrate a proof-of-concept digital electrospray. This system consists of a 61-nozzle array microfabricated in silicon and a 61-element digital extractor fabricated using flexible polyimide substrates. "Digital" refers to the state of each electrospray source that can be tuned either on or off independently and responsively. We showed a resolution of 675 mum and a response frequency up to 100 Hz. With similar design and industry standard fabrication procedures, it is feasible to scale up the system to O(1000) sources with spatial resolution better than 250 mum and a O(kHz) response frequency. The latter is controlled by the viscous damping time.

  18. Optimal digital redesign of cascaded analogue controllers

    NASA Technical Reports Server (NTRS)

    Shieh, L. S.; Decrocq, B. B.; Zhang, J. L.

    1991-01-01

    This paper presents a new, optimal digital redesign technique for finding an optimal cascaded digital controller from the given continuous-time counterpart by minimizing a quadratic performance index. The control gains can be obtained by solving a set of Liapunov equations. The developed optimal cascaded digital controller enables the state and/or outputs of the digitally controlled closed-loop sampled-data system to optimally match those of the original continuous-time closed-loop system at any instant between sampling periods. The developed control law can be implemented using inexpensive and reliable digital electronics with a relatively long sampling period.

  19. Aircraft digital control design methods

    NASA Technical Reports Server (NTRS)

    Powell, J. D.; Parsons, E.; Tashker, M. G.

    1976-01-01

    Variations in design methods for aircraft digital flight control are evaluated and compared. The methods fall into two categories; those where the design is done in the continuous domain (or s plane) and those where the design is done in the discrete domain (or z plane). Design method fidelity is evaluated by examining closed loop root movement and the frequency response of the discretely controlled continuous aircraft. It was found that all methods provided acceptable performance for sample rates greater than 10 cps except the uncompensated s plane design method which was acceptable above 20 cps. A design procedure based on optimal control methods was proposed that provided the best fidelity at very slow sample rates and required no design iterations for changing sample rates.

  20. Highly integrated digital electronic control: Digital flight control, aircraft model identification, and adaptive engine control

    NASA Technical Reports Server (NTRS)

    Baer-Riedhart, Jennifer L.; Landy, Robert J.

    1987-01-01

    The highly integrated digital electronic control (HIDEC) program at NASA Ames Research Center, Dryden Flight Research Facility is a multiphase flight research program to quantify the benefits of promising integrated control systems. McDonnell Aircraft Company is the prime contractor, with United Technologies Pratt and Whitney Aircraft, and Lear Siegler Incorporated as major subcontractors. The NASA F-15A testbed aircraft was modified by the HIDEC program by installing a digital electronic flight control system (DEFCS) and replacing the standard F100 (Arab 3) engines with F100 engine model derivative (EMD) engines equipped with digital electronic engine controls (DEEC), and integrating the DEEC's and DEFCS. The modified aircraft provides the capability for testing many integrated control modes involving the flight controls, engine controls, and inlet controls. This paper focuses on the first two phases of the HIDEC program, which are the digital flight control system/aircraft model identification (DEFCS/AMI) phase and the adaptive engine control system (ADECS) phase.

  1. Digital signal processing control of induction machine`s torque and stator flux utilizing the direct stator flux field orientation method

    SciTech Connect

    Seiz, Julie Burger

    1997-04-01

    This paper presents a review of the Direct Stator Flux Field Orientation control method. This method can be used to control an induction motor`s torque and flux directly and is the application of interest for this thesis. This control method is implemented without the traditional feedback loops and associated hardware. Predictions are made, by mathematical calculations, of the stator voltage vector. The voltage vector is determined twice a switching period. The switching period is fixed throughout the analysis. The three phase inverter duty cycle necessary to control the torque and flux of the induction machine is determined by the voltage space vector Pulse Width Modulation (PWM) technique. Transient performance of either the flux or torque requires an alternate modulation scheme which is also addressed in this thesis. A block diagram of this closed loop system is provided. 22 figs., 7 tabs.

  2. Thermal Modeling of Direct Digital Melt-Deposition Processes

    NASA Astrophysics Data System (ADS)

    Cooper, K. P.; Lambrakos, S. G.

    2011-02-01

    Additive manufacturing involves creating three-dimensional (3D) objects by depositing materials layer-by-layer. The freeform nature of the method permits the production of components with complex geometry. Deposition processes provide one more capability, which is the addition of multiple materials in a discrete manner to create "heterogeneous" objects with locally controlled composition and microstructure. The result is direct digital manufacturing (DDM) by which dissimilar materials are added voxel-by-voxel (a voxel is volumetric pixel) following a predetermined tool-path. A typical example is functionally gradient material such as a gear with a tough core and a wear-resistant surface. The inherent complexity of DDM processes is such that process modeling based on direct physics-based theory is difficult, especially due to a lack of temperature-dependent thermophysical properties and particularly when dealing with melt-deposition processes. In order to overcome this difficulty, an inverse problem approach is proposed for the development of thermal models that can represent multi-material, direct digital melt deposition. This approach is based on the construction of a numerical-algorithmic framework for modeling anisotropic diffusivity such as that which would occur during energy deposition within a heterogeneous workpiece. This framework consists of path-weighted integral formulations of heat diffusion according to spatial variations in material composition and requires consideration of parameter sensitivity issues.

  3. Estimation of Laminar Burning Velocities by Direct Digital Photography

    ERIC Educational Resources Information Center

    Uske, J.; Barat, R.

    2004-01-01

    The Bunsen burner flame, which is the most common flame in the laboratory, can be easily studied for its dynamics because of modern, economical digital technology available to student laboratories. Direct digital photography of Bunsen flames is used to obtain laminar burning velocities of selected gaseous hydrocarbon/air flames.

  4. Estimation of Laminar Burning Velocities by Direct Digital Photography

    ERIC Educational Resources Information Center

    Uske, J.; Barat, R.

    2004-01-01

    The Bunsen burner flame, which is the most common flame in the laboratory, can be easily studied for its dynamics because of modern, economical digital technology available to student laboratories. Direct digital photography of Bunsen flames is used to obtain laminar burning velocities of selected gaseous hydrocarbon/air flames.

  5. Army/NASA small turboshaft engine digital controls research program

    NASA Technical Reports Server (NTRS)

    Sellers, J. F.; Baez, A. N.

    1981-01-01

    The emphasis of a program to conduct digital controls research for small turboshaft engines is on engine test evaluation of advanced control logic using a flexible microprocessor based digital control system designed specifically for research on advanced control logic. Control software is stored in programmable memory. New control algorithms may be stored in a floppy disk and loaded directly into memory. This feature facilitates comparative evaluation of different advanced control modes. The central processor in the digital control is an Intel 8086 16 bit microprocessor. Control software is programmed in assembly language. Software checkout is accomplished prior to engine test by connecting the digital control to a real time hybrid computer simulation of the engine. The engine currently installed in the facility has a hydromechanical control modified to allow electrohydraulic fuel metering and VG actuation by the digital control. Simulation results are presented which show that the modern control reduces the transient rotor speed droop caused by unanticipated load changes such as cyclic pitch or wind gust transients.

  6. Digital sound service for direct broadcasting satellites

    NASA Astrophysics Data System (ADS)

    Treytl, D.

    A 16 channel (4 phase (CPSK), or 12 channel (2 phase CPSK) digital sound link for the TV Sat satellite is proposed. Small parabolic antennas suitable for sound and TV broadcasts assure reception. A specially developed tuner allows the user to select either a given program from 1 of 16, or 1 of 8 types of program, e.g., sport or opera. Tests with OTS satellite and a cable distribution network prove the feasibility of the proposal. Encoding, transmission, signal modulation and links are outlined. Equipment is described.

  7. Digit Ratio Predicts Sense of Direction in Women

    PubMed Central

    Chai, Xiaoqian J.; Jacobs, Lucia F.

    2012-01-01

    The relative length of the second-to-fourth digits (2D:4D) has been linked with prenatal androgen in humans. The 2D:4D is sexually dimorphic, with lower values in males than females, and appears to correlate with diverse measures of behavior. However, the relationship between digit ratio and cognition, and spatial cognition in particular, has produced mixed results. In the present study, we hypothesized that spatial tasks separating cue conditions that either favored female or male strategies would examine this structure-function correlation with greater precision. Previous work suggests that males are better in the use of directional cues than females. In the present study, participants learned a target location in a virtual landscape environment, in conditions that contained either all directional (i.e., distant or compass bearing) cues, or all positional (i.e., local, small objects) cues. After a short delay, participants navigated back to the target location from a novel starting location. Males had higher accuracy in initial search direction than females in environments with all directional cues. Lower digit ratio was correlated with higher accuracy of initial search direction in females in environments with all directional cues. Mental rotation scores did not correlate with digit ratio in either males or females. These results demonstrate for the first time that a sex difference in the use of directional cues, i.e., the sense of direction, is associated with more male-like digit ratio. PMID:22393451

  8. Relationships between digital signal processing and control and estimation theory

    NASA Technical Reports Server (NTRS)

    Willsky, A. S.

    1978-01-01

    Research directions in the fields of digital signal processing and modern control and estimation theory are discussed. Stability theory, linear prediction and parameter identification, system synthesis and implementation, two-dimensional filtering, decentralized control and estimation, and image processing are considered in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the disciplines.

  9. Directions in propulsion control

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.

    1990-01-01

    Discussed here is research at NASA Lewis in the area of propulsion controls as driven by trends in advanced aircraft. The objective of the Lewis program is to develop the technology for advanced reliable propulsion control systems and to integrate the propulsion control with the flight control for optimal full-system control.

  10. A direct current superconducting quantum interference device gradiometer with a digital signal processor controlled flux-locked loop and comparison with a conventional analog feedback scheme

    SciTech Connect

    Kung, P.J.; Bracht, R.R.; Flynn, E.R.; Lewis, P.S.

    1996-01-01

    A double-washer dc superconducting quantum interference device (SQUID) gradiometer with a flux-locked loop (FLL) based on a digital signal processor (DSP) has been developed for biomagnetic applications. All of the analog electronics in the conventional FLL are replaced and implemented by the DSP except for the low-noise field-effect transistor preamplifier at the front end of the signal recovery components. The DSP performs the signal demodulation by synchronously sampling the recovered signals and applying the appropriate full wave rectification. The signals are then integrated, filtered, and applied to the output. At 4.2 K, the white flux noise of the gradiometer measured in a DSP FLL mode is about 4{mu}{phi}{sub 0}/{radical}Hz and the noise at 1 Hz is 13 {mu}{phi}{sub 0}/{radical}Hz. The corresponding noise levels in the gradiometer operated by the conventional FLL are 1.8 and 3{mu}{phi}{sub 0}/{radical}Hz. The poorer system performance in the DSP FLL compared to the analog FLL is mainly caused by the ambient field noise and interference signals picked up through the connecting cables. Additional noise is also added to the overall noise floor by the instruments employed in the DSP system in the present prototype setup. Further improvement in the noise characteristics and the dynamic behavior of the DSP SQUID gradiometer is expected when a better configuration of DSP with the associated I/O devices is implemented. Additional improvements of the DSP programs are expected by incorporating higher-order integration, adaptive control, and noise reduction schemes. {copyright} {ital 1996 American Institute of Physics.}

  11. 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.

  12. Direct digital RF synthesis and modulation for MSAT mobile applications

    NASA Technical Reports Server (NTRS)

    Crozier, Stewart; Datta, Ravi; Sydor, John

    1993-01-01

    A practical method of performing direct digital RF synthesis using the Hilbert transform single sideband (SSB) technique is described. It is also shown that amplitude and phase modulation can be achieved directly at L-band with frequency stability and spurii performance exceeding stringent MSAT system requirements.

  13. Evaluating Multi-Input/Multi-Output Digital Control Systems

    NASA Technical Reports Server (NTRS)

    Pototzky, Anthony S.; Wieseman, Carol D.; Hoadley, Sherwood T.; Mukhopadhyay, Vivek

    1994-01-01

    Controller-performance-evaluation (CPE) methodology for multi-input/multi-output (MIMO) digital control systems developed. Procedures identify potentially destabilizing controllers and confirm satisfactory performance of stabilizing ones. Methodology generic and used in many types of multi-loop digital-controller applications, including digital flight-control systems, digitally controlled spacecraft structures, and actively controlled wind-tunnel models. Also applicable to other complex, highly dynamic digital controllers, such as those in high-performance robot systems.

  14. Digitally Controlled Slot Coupled Patch Array

    NASA Technical Reports Server (NTRS)

    D'Arista, Thomas; Pauly, Jerry

    2010-01-01

    A four-element array conformed to a singly curved conducting surface has been demonstrated to provide 2 dB axial ratio of 14 percent, while maintaining VSWR (voltage standing wave ratio) of 2:1 and gain of 13 dBiC. The array is digitally controlled and can be scanned with the LMS Adaptive Algorithm using the power spectrum as the objective, as well as the Direction of Arrival (DoA) of the beam to set the amplitude of the power spectrum. The total height of the array above the conducting surface is 1.5 inches (3.8 cm). A uniquely configured microstrip-coupled aperture over a conducting surface produced supergain characteristics, achieving 12.5 dBiC across the 2-to-2.13- GHz and 2.2-to-2.3-GHz frequency bands. This design is optimized to retain VSWR and axial ratio across the band as well. The four elements are uniquely configured with respect to one another for performance enhancement, and the appropriate phase excitation to each element for scan can be found either by analytical beam synthesis using the genetic algorithm with the measured or simulated far field radiation pattern, or an adaptive algorithm implemented with the digitized signal. The commercially available tuners and field-programmable gate array (FPGA) boards utilized required precise phase coherent configuration control, and with custom code developed by Nokomis, Inc., were shown to be fully functional in a two-channel configuration controlled by FPGA boards. A four-channel tuner configuration and oscilloscope configuration were also demonstrated although algorithm post-processing was required.

  15. The Direct Digital Modulation of Traveling Wave Tubes

    NASA Technical Reports Server (NTRS)

    Radhamohan, Ranjan S.

    2004-01-01

    direct digital modulation of a TWT removes the need for a separate amplitude modulation device. Instead, different levels of gain are achieved by varying the electron beam current. The lower the current, the less kinetic energy is available to be transferred to the signal. To vary the current, a grid is placed in-between the electron gun and the slow wave circuit. By changing the voltage across the grid, the electron beam current can be controlled. Grid technology has mostly been used in pulse applications such as radar, where only two voltage states are necessary. For direct digital modulation, however, a continuous range of voltages is required.

  16. The Direct Digital Modulation of Traveling Wave Tubes

    NASA Technical Reports Server (NTRS)

    Radhamohan, Ranjan S.

    2004-01-01

    direct digital modulation of a TWT removes the need for a separate amplitude modulation device. Instead, different levels of gain are achieved by varying the electron beam current. The lower the current, the less kinetic energy is available to be transferred to the signal. To vary the current, a grid is placed in-between the electron gun and the slow wave circuit. By changing the voltage across the grid, the electron beam current can be controlled. Grid technology has mostly been used in pulse applications such as radar, where only two voltage states are necessary. For direct digital modulation, however, a continuous range of voltages is required.

  17. Fabrication and test of digital output interface devices for gas turbine electronic controls

    NASA Technical Reports Server (NTRS)

    Newirth, D. M.; Koenig, E. W.

    1978-01-01

    A program was conducted to develop an innovative digital output interface device, a digital effector with optical feedback of the fuel metering valve position, for future electronic controls for gas turbine engines. A digital effector (on-off solenoids driven directly by on-off signals from a digital electronic controller) with optical position feedback was fabricated, coupled with the fuel metering valve, and tested under simulated engine operating conditions. The testing indicated that a digital effector with optical position feedback is a suitable candidate, with proper development for future digital electronic gas turbine controls. The testing also identified several problem areas which would have to be overcome in a final production configuration.

  18. Improving Hypertension Control and Patient Engagement Using Digital Tools.

    PubMed

    Milani, Richard V; Lavie, Carl J; Bober, Robert M; Milani, Alexander R; Ventura, Hector O

    2017-01-01

    Hypertension is present in 30% of the adult US population and is a major contributor to cardiovascular disease. The established office-based approach yields only 50% blood pressure control rates and low levels of patient engagement. Available home technology now provides accurate, reliable data that can be transmitted directly to the electronic medical record. We evaluated blood pressure control in 156 patients with uncontrolled hypertension enrolled into a home-based digital-medicine blood pressure program and compared them with 400 patients (matched to age, sex, body mass index, and blood pressure) in a usual-care group after 90 days. Digital-medicine patients completed questionnaires online, were asked to submit at least one blood pressure reading/week, and received medication management and lifestyle recommendations via a clinical pharmacist and a health coach. Blood pressure units were commercially available that transmitted data directly to the electronic medical record. Digital-medicine patients averaged 4.2 blood pressure readings per week. At 90 days, 71% of digital-medicine vs 31% of usual-care patients had achieved target blood pressure control. Mean decrease in systolic/diastolic blood pressure was 14/5 mm Hg in digital medicine, vs 4/2 mm Hg in usual care (P < .001). Excess sodium consumption decreased from 32% to 8% in the digital-medicine group (P = .004). Mean patient activation increased from 41.9 to 44.1 (P = .008), and the percentage of patients with low patient activation decreased from 15% to 6% (P = .03) in the digital-medicine group. A digital hypertension program is feasible and associated with significant improvement in blood pressure control rates and lifestyle change. Utilization of a virtual health intervention using connected devices improves patient activation and is well accepted by patients.

  19. Digital Control Of A Telescope In An Airplane

    NASA Technical Reports Server (NTRS)

    Mccormack, Ann C.; Snyder, Philip K.

    1991-01-01

    Options for design of aim-stabilizing system analyzed. Report discusses feasibility of digital control system stabilizing aim of 30-in. telescope aboard NASA C141 airplane known as Kuiper Atmospheric Observatory. Proposed digital compensator consists of input analog-to-digital converter, digital controller processor, and output digital-to-analog converter.

  20. 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.

  1. Designing Digital Control Systems With Averaged Measurements

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.; Beale, Guy O.

    1990-01-01

    Rational criteria represent improvement over "cut-and-try" approach. Recent development in theory of control systems yields improvements in mathematical modeling and design of digital feedback controllers using time-averaged measurements. By using one of new formulations for systems with time-averaged measurements, designer takes averaging effect into account when modeling plant, eliminating need to iterate design and simulation phases.

  2. GMA200 ATEGG Digital Controls Demonstration.

    DTIC Science & Technology

    1979-10-01

    Technologyi Demonstrator Variable Cycle Engines Digital Controls Control Modes Turbine Engine Controls Signal Synthesis 20 A 8STRACI ’CantInue -n r.ct...Turbine Outlet Temperature TX Temperature at Station Location X UTC Universal Test Console VCE Variable Cycle Engine VG Variable Geometry W Flow WA...Definition of engine control variables - ATEGG is a variaole cycle engine with a multi-input, multi-output structure. The multi-input part of tna

  3. Reorienting Self-Directed Learning for the Creative Digital Era

    ERIC Educational Resources Information Center

    Karakas, Fahri; Manisaligil, Alperen

    2012-01-01

    Purpose: The purpose of this paper is to identify the new role that human resource developers play in the globally connected workplace. Towards that end, this paper explores the changing landscape of self-directed learning (SDL) within the digital ecosystem based on the concept of World 2.0. Design/methodology/approach: This paper reviews and…

  4. Reorienting Self-Directed Learning for the Creative Digital Era

    ERIC Educational Resources Information Center

    Karakas, Fahri; Manisaligil, Alperen

    2012-01-01

    Purpose: The purpose of this paper is to identify the new role that human resource developers play in the globally connected workplace. Towards that end, this paper explores the changing landscape of self-directed learning (SDL) within the digital ecosystem based on the concept of World 2.0. Design/methodology/approach: This paper reviews and…

  5. Digital Control System for An On-Borad Oxygen Generator

    DTIC Science & Technology

    1980-12-01

    pecple who contributed to the success of this thesis. They include the following: Major Borky, my thesis advisor; the entire staff of the Electrical ...System with [xternal 1c;:-ory and Expander- ...... 28 11 Analog to Digital Converter ----.------------------------ 29 12 Control System with Bus Gate, RDC...directional ports which can be used for input or output and an eight bit, bi- directional bus which is used for the memory (Ref 5:2-4). The MPU also

  6. Digital system identification and its application to digital flight control

    NASA Technical Reports Server (NTRS)

    Kotob, S.; Kaufman, H.

    1974-01-01

    On-line system identification of linear discrete systems for implementation in a digital adaptive flight controller is considered by the conventional extended Kalman filter and a decoupling process in which the linear state estimation problem and the linear parameter identification problem are each treated separately and alternately. Input requirements for parameter identifiability are established using the standard conditions of observability for a time variant system. Experimental results for simulated linearized lateral aircraft motion are included along with the effect of different initialization and updating procedures for the priming trajectory used by the filter.

  7. Effective dose from direct and indirect digital panoramic units.

    PubMed

    Lee, Gun-Sun; Kim, Jin-Soo; Seo, Yo-Seob; Kim, Jae-Duk

    2013-06-01

    This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. The effective doses of the 4 digital panoramic units ranged between 8.9 µSv and 37.8 µSv. By using the head phantom, the effective doses from the direct digital panoramic units (37.8 µSv, 27.6 µSv) were higher than those from the indirect units (8.9 µSv, 15.9 µSv). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom.

  8. Effective dose from direct and indirect digital panoramic units

    PubMed Central

    Lee, Gun-Sun; Kim, Jin-Soo; Seo, Yo-Seob

    2013-01-01

    Purpose This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. Materials and Methods Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. Results The effective doses of the 4 digital panoramic units ranged between 8.9 µSv and 37.8 µSv. By using the head phantom, the effective doses from the direct digital panoramic units (37.8 µSv, 27.6 µSv) were higher than those from the indirect units (8.9 µSv, 15.9 µSv). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. Conclusion To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom. PMID:23807930

  9. SSME digital control design characteristics

    NASA Technical Reports Server (NTRS)

    Mitchell, W. T.; Searle, R. F.

    1985-01-01

    To protect against a latent programming error (software fault) existing in an untried branch combination that would render the space shuttle out of control in a critical flight phase, the Backup Flight System (BFS) was chartered to provide a safety alternative. The BFS is designed to operate in critical flight phases (ascent and descent) by monitoring the activities of the space shuttle flight subsystems that are under control of the primary flight software (PFS) (e.g., navigation, crew interface, propulsion), then, upon manual command by the flightcrew, to assume control of the space shuttle and deliver it to a noncritical flight condition (safe orbit or touchdown). The problems associated with the selection of the PFS/BFS system architecture, the internal BFS architecture, the fault tolerant software mechanisms, and the long term BFS utility are discussed.

  10. Automatic Exposure Control Device for Digital Mammography

    DTIC Science & Technology

    2004-08-01

    developing innovative approaches for controlling DM exposures. These approaches entail using the digital detector and an artificial neural network to...of interest that determine the exposure parameters for the fully exposed image; and (2) to use an artificial neural network to select exposure

  11. Automatic Exposure Control Device for Digital Mammography

    DTIC Science & Technology

    2001-08-01

    developing innovative approaches for controlling DM exposures. These approaches entail using the digital detector and an artificial neural network to...34 regions of interest that determine the exposure parameters for the fully exposed image; and (2) to use an artificial neural network to select exposure

  12. Digital control of highly augmented combat rotorcraft

    NASA Technical Reports Server (NTRS)

    Tischler, Mark B.

    1987-01-01

    Proposed concepts for the next generation of combat helicopters are to be embodied in a complex, highly maneuverable, multiroled vehicle with avionics systems. Single pilot and nap-of-the-Earth operations require handling qualities which minimize the involvement of the pilot in basic stabilization tasks. To meet these requirements will demand a full authority, high-gain, multimode, multiply-redundant, digital flight-control system. The gap between these requirements and current low-authority, low-bandwidth operational rotorcraft flight-control technology is considerable. This research aims at smoothing the transition between current technology and advanced concept requirements. The state of the art of high-bandwidth digital flight-control systems are reviewed; areas of specific concern for flight-control systems of modern combat are exposed; and the important concepts are illustrated in design and analysis of high-gain, digital systems with a detailed case study involving a current rotorcraft system. Approximate and exact methods are explained and illustrated for treating the important concerns which are unique to digital systems.

  13. Digital electronic engine control F-15 overview

    NASA Technical Reports Server (NTRS)

    Kock, B.

    1984-01-01

    A flight test evaluation of the digital elctronic engine control (DEEC) system was conducted. An overview of the flight program is presented. The roles of the participating parties, the system, and the flight program objectives are described. The test program approach is discussed, and the engine performance benefits are summarized. A description of the follow-on programs is included.

  14. Aircraft digital flight control technical review

    NASA Technical Reports Server (NTRS)

    Davenport, Otha B.; Leggett, David B.

    1993-01-01

    The Aircraft Digital Flight Control Technical Review was initiated by two pilot induced oscillation (PIO) incidents in the spring and summer of 1992. Maj. Gen. Franklin (PEO) wondered why the Air Force development process for digital flight control systems was not preventing PIO problems. Consequently, a technical review team was formed to examine the development process and determine why PIO problems continued to occur. The team was also to identify the 'best practices' used in the various programs. The charter of the team was to focus on the PIO problem, assess the current development process, and document the 'best practices.' The team reviewed all major USAF aircraft programs with digital flight controls, specifically, the F-15E, F-16C/D, F-22, F-111, C-17, and B-2. The team interviewed contractor, System Program Office (SPO), and Combined Test Force (CTF) personnel on these programs. The team also went to NAS Patuxent River to interview USN personnel about the F/A-18 program. The team also reviewed experimental USAF and NASA systems with digital flight control systems: X-29, X-31, F-15 STOL and Maneuver Technology Demonstrator (SMTD), and the Variable In-Flight Stability Test Aircraft (VISTA). The team also discussed the problem with other experts in the field including Ralph Smith and personnel from Calspan. The major conclusions and recommendations from the review are presented.

  15. 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.

  16. Decentralized digital adaptive control of robot motion

    NASA Technical Reports Server (NTRS)

    Tarokh, M.

    1990-01-01

    A decentralized model reference adaptive scheme is developed for digital control of robot manipulators. The adaptation laws are derived using hyperstability theory, which guarantees asymptotic trajectory tracking despite gross robot parameter variations. The control scheme has a decentralized structure in the sense that each local controller receives only its joint angle measurement to produce its joint torque. The independent joint controllers have simple structures and can be programmed using a very simple and computationally fast algorithm. As a result, the scheme is suitable for real-time motion control.

  17. Digital gate pulse generator for cycloconverter control

    DOEpatents

    Klein, Frederick F.; Mutone, Gioacchino A.

    1989-01-01

    The present invention provides a digital gate pulse generator which controls the output of a cycloconverter used for electrical power conversion applications by determining the timing and delivery of the firing pulses to the switching devices in the cycloconverter. Previous gate pulse generators have been built with largely analog or discrete digital circuitry which require many precision components and periodic adjustment. The gate pulse generator of the present invention utilizes digital techniques and a predetermined series of values to develop the necessary timing signals for firing the switching device. Each timing signal is compared with a reference signal to determine the exact firing time. The present invention is significantly more compact than previous gate pulse generators, responds quickly to changes in the output demand and requires only one precision component and no adjustments.

  18. Advanced Digital Controller Development Program, Task I.

    DTIC Science & Technology

    1982-07-01

    The control will not allow more than 60*F overshoot above the specified steady-state turbine outlet gas temperature limit. Transient temperature...AD-A129 269 ADVANCED DIGITAL CONTROLLER DEVELOPMENT PROGRAM TASK 1 1/1 ()GENERAL MOTORS CORP INDIANAPOLIS IN DETROIT DIESEL ALLISON D0. d H HUNTER JL... Diesel Allison Division of General Motors Corporation P.O. Box 894 Indianapolis, Indiana 46206 July 1982 Interim Report for Period 1 September 1979-30

  19. AN INVESTIGATION OF A DIGITAL BEARING COMPUTER FOR A SMALL APERATURE RADIO DIRECTION FINDING SYSTEM.

    DTIC Science & Technology

    DIRECTION FINDING , RADIO EQUIPMENT), (*RADIO EQUIPMENT, DIRECTION FINDING ), (*DIGITAL COMPUTERS, NAVIGATION COMPUTERS), (*NAVIGATION COMPUTERS... DIRECTION FINDING ), RADIO WAVES, ANGLE OF ARRIVAL, RADIOFREQUENCY POWER, MULTIPATH TRANSMISSION, PHASE MEASUREMENT

  20. 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

  1. 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.

  2. F-8C digital CCV flight control laws

    NASA Technical Reports Server (NTRS)

    Hartmann, G. L.; Hauge, J. A.; Hendrick, R. C.

    1976-01-01

    A set of digital flight control laws were designed for the NASA F-8C digital fly-by-wire aircraft. The control laws emphasize Control Configured Vehicle (CCV) benefits. Specific pitch axis objectives were improved handling qualities, angle-of-attack limiting, gust alleviation, drag reduction in steady and maneuvering flight, and a capability to fly with reduced static stability. The lateral-directional design objectives were improved Dutch roll damping and turn coordination over a wide range in angle-of-attack. An overall program objective was to explore the use of modern control design methodilogy to achieve these specific CCV benefits. Tests for verifying system integrity, an experimental design for handling qualities evaluation, and recommended flight test investigations were specified.

  3. Off-axis illumination direct-to-digital holography

    DOEpatents

    Thomas, Clarence E.; Price, Jeffery R.; Voelkl, Edgar; Hanson, Gregory R.

    2004-06-08

    Systems and methods are described for off-axis illumination direct-to-digital holography. A method of recording an off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis, includes: reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object at an angle with respect to an optical axis defined by a focusing lens; focusing the reference beam and the object beam at a focal plane of a digital recorder to form the off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; digitally recording the off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; Fourier analyzing the recorded off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes by transforming axes of the recorded off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes in Fourier space to sit on top of a heterodyne carrier frequency defined as an angle between the reference beam and the object beam; applying a digital filter to cut off signals around an original origin; and then performing an inverse Fourier transform.

  4. Recording multiple spatially-heterodyned direct to digital holograms in one digital image

    DOEpatents

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN

    2008-03-25

    Systems and methods are described for recording multiple spatially-heterodyned direct to digital holograms in one digital image. A method includes digitally recording, at a first reference beam-object beam angle, a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram to sit on top of a first spatial-heterodyne carrier frequency defined by the first reference beam-object beam angle; digitally recording, at a second reference beam-object beam angle, a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram to sit on top of a second spatial-heterodyne carrier frequency defined by the second reference beam-object beam angle; applying a first digital filter to cut off signals around the first original origin and define a first result; performing a first inverse Fourier transform on the first result; applying a second digital filter to cut off signals around the second original origin and define a second result; and performing a second inverse Fourier transform on the second result, wherein the first reference beam-object beam angle is not equal to the second reference beam-object beam angle and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  5. Digital LLRF controller for NICA booster

    NASA Astrophysics Data System (ADS)

    Fatkin, G. A.; Batrakov, A. M.; Ilyin, I. V.; Vasilyev, M. Yu.

    2016-10-01

    The digital LLRF controller based on embedded microcontroller for the booster of the Dubna superconducting accelerator complex NICA is presented. It allows setting the frequency in accordance with the magnetic field value in the 0.5-5 MHz range with an inaccuracy ± 110 Hz. A novel method of frequency calculation based on the derivative is proposed. The specialized tester module allows tuning up and checking the RF system during comissioning and operation.

  6. Technology research for digital flight control

    NASA Technical Reports Server (NTRS)

    Carestia, R. A.

    1983-01-01

    The use of advanced digital systems for flight control and guidance for a specific mission is investigated. The research areas include advanced electronic system architectures, tests with the global positioning system (GPS) in a helicopter, and advanced integrated systems concept for rotorcraft. Emphasis is on a search and rescue mission, differential global positioning systems to provide a data base of performance information for navigation, and a study to determine the present usage and trends of microcomputers and microcomputer components in the avionics industries.

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

    NASA Technical Reports Server (NTRS)

    Phillips, C. L.; Vallely, D. P.

    1978-01-01

    This paper considers digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. A quantization error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. The program can be integrated into existing digital simulations of a system.

  8. Direct digital manufacturing of autonomous centrifugal microfluidic device

    NASA Astrophysics Data System (ADS)

    Ukita, Yoshiaki; Takamura, Yuzuru; Utsumi, Yuichi

    2016-06-01

    This paper presents strategies that attempt to solve two key problems facing the commercialization of microfluidics: cost reduction in microfluidic chip manufacturing and microfluidic device driver development. To reduce the cost of microfluidic chip manufacturing, we propose to use of three-dimensional (3D) printers for direct digital manufacturing (DDM). An evaluation of 3D micro-scale structure printing using several 3D printers is reported, and some of the technical issues to be addressed in the future are suggested. To evaluate micro-scale printing, three types of 3D printers, with the ability to print structures on the scale of several hundred meters, were selected by first screening six 3D printers. Line and space patterns with line widths of 100-500 µm and an aspect ratio of one were printed and evaluated. The estimated critical dimension was around 200 µm. The manufacturing of a monolithic microfluidic chip with embedded channels was also demonstrated. Monolithic microfluidic chips with embedded microchannels having 500 × 500 and 250 × 250 µm2 cross sections and 2-20 mm lengths were printed, and the fidelity of the channel shape, residual supporting material, and flow of liquid water were evaluated. The liquid flow evaluation showed that liquid water could flow through all of the microchannels with the 500 × 500 µm2 cross section, whereas this was not possible through some of the channels with the 250 × 250 µm2 cross section because of the residual resin or supporting material. To reduce the device-driver cost, we propose to use of the centrifugal microfluidic concept. An autonomous microfluidic device that could implement sequential flow control under a steadily rotating condition was printed. Four-step flow injection under a steadily rotating condition at 1500 rpm was successfully demonstrated without any external triggering such as changing the rotational speed.

  9. A direct digital synthesis chirped pulse Fourier transform microwave spectrometer.

    PubMed

    Finneran, Ian A; Holland, Daniel B; Carroll, P Brandon; Blake, Geoffrey A

    2013-08-01

    Chirped pulse Fourier transform microwave (CP-FTMW) spectrometers have become the instrument of choice for acquiring rotational spectra, due to their high sensitivity, fast acquisition rate, and large bandwidth. Here we present the design and capabilities of a recently constructed CP-FTMW spectrometer using direct digital synthesis (DDS) as a new method for chirped pulse generation, through both a suite of extensive microwave characterizations and deep averaging of the 10-14 GHz spectrum of jet-cooled acetone. The use of DDS is more suited for in situ applications of CP-FTMW spectroscopy, as it reduces the size, weight, and power consumption of the chirp generation segment of the spectrometer all by more than an order of magnitude, while matching the performance of traditional designs. The performance of the instrument was further improved by the use of a high speed digitizer with dedicated signal averaging electronics, which facilitates a data acquisition rate of 2.1 kHz.

  10. 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.

  11. Error-control techniques for digital communication

    NASA Astrophysics Data System (ADS)

    Michelson, A. M.; Levesque, A. H.

    The reliable transmission of digital information is discussed, taking into account the communication system design problem, the elements of a digital communication system, important channel models, information theory and channel capacity, modulation performance on the AWGN channel, and combined modulation and coding for efficient signal design. Other topics studied are related to fundamental and simple block codes, the algebra of linear block codes, binary cyclic codes and BCH codes, decoding techniques for binary BCH codes, nonbinary BCH codes and Reed-Solomon codes, the performance of linear block codes with bounded-distance decoding an introduction to convolutional codes, maximum likelihood decoding of convolutional codes, sequential decoding, and applications of error-control coding. Attention is given to groups, fields, vector spaces, binary linear block codes, the parity-check matrix revisited, dual codes, Hamming distance and the weight distribution, code geometry and error-correction capability, and the representations of finite fields.

  12. Digitally controlled twelve-pulse firing generator

    SciTech Connect

    Berde, D.; Ferrara, A.A.

    1981-01-01

    Control System Studies for the Tokamak Fusion Test Reactor (TFTR) indicate that accurate thyristor firing in the AC-to-DC conversion system is required in order to achieve good regulation of the various field currents. Rapid update and exact firing angle control are required to avoid instabilities, large eddy currents, or parasitic oscillations. The Prototype Firing Generator was designed to satisfy these requirements. To achieve the required /plus or minus/0.77/degree/firing accuracy, a three-phase-locked loop reference was designed; otherwise, the Firing Generator employs digital circuitry. The unit, housed in a standard CAMAC crate, operates under microcomputer control. Functions are performed under program control, which resides in nonvolatile read-only memory. Communication with CICADA control system is provided via an 11-bit parallel interface.

  13. IDSAC-IUCAA digital sampler array controller

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Sabyasachi; Chordia, Pravin; Ramaprakash, A. N.; Burse, Mahesh P.; Joshi, Bhushan; Chillal, Kalpesh

    2016-07-01

    In order to run the large format detector arrays and mosaics that are required by most astronomical instruments, readout electronic controllers are required which can process multiple CCD outputs simultaneously at high speeds and low noise levels. These CCD controllers need to be modular and configurable, should be able to run multiple detector types to cater to a wide variety of requirements. IUCAA Digital Sampler Array Controller (IDSAC), is a generic CCD Controller based on a fully scalable architecture which is adequately flexible and powerful enough to control a wide variety of detectors used in ground based astronomy. The controller has a modular backplane architecture that consists of Single Board Controller Cards (SBCs) and can control up to 5 CCDs (mosaic or independent). Each Single Board Controller (SBC) has all the resources to a run Single large format CCD having up to four outputs. All SBCs are identical and are easily interchangeable without needing any reconfiguration. A four channel video processor on each SBC can process up to four output CCDs with or without dummy outputs at 0.5 Megapixels/Sec/Channel with 16 bit resolution. Each SBC has a USB 2.0 interface which can be connected to a host computer via optional USB to Fibre converters. The SBC uses a reconfigurable hardware (FPGA) as a Master Controller. IDSAC offers Digital Correlated Double Sampling (DCDS) to eliminate thermal kTC noise. CDS performed in Digital domain (DCDS) has several advantages over its analog counterpart, such as - less electronics, faster readout and easier post processing. It is also flexible with sampling rate and pixel throughput while maintaining the core circuit topology intact. Noise characterization of the IDSAC CDS signal chain has been performed by analytical modelling and practical measurements. Various types of noise such as white, pink, power supply, bias etc. has been considered while creating an analytical noise model tool to predict noise of a controller

  14. Droplet position control in digital microfluidic systems.

    PubMed

    Bhattacharjee, Biddut; Najjaran, Homayoun

    2010-02-01

    Research on so called digital microfluidic systems (DMS) capable of manipulating individual microdroplets on a cell-based structure has enormously increased in the past few years, mainly due to the demand of the technology-dependent biomedical applications. Significant research in this area has been related to the simulation and modeling of droplet motion, demonstration of different drop actuation techniques on laboratory-scale prototypes, and droplet routing and scheduling for more efficient assay procedures. This paper introduces the basics of the control analysis and design of a DMS, which is a relatively unexplored area in digital microfluidics. This paper starts with a discussion on a simplified dynamic model of droplet motion in a planar array of cells, and continues with more complicated dynamic models that are necessary to realize the structure of an appropriate closed-loop control system for the DMS. The control analysis and design includes both the transient and steady-state responses of the DMS under external driving forces. The proposed control analysis and design approach is implemented into SIMULINK models to demonstrate the performance of the DMS through simulation using the system parameters previously reported in the literature.

  15. Digital system accurately controls velocity of electromechanical drive

    NASA Technical Reports Server (NTRS)

    Nichols, G. B.

    1965-01-01

    Digital circuit accurately regulates electromechanical drive mechanism velocity. The gain and phase characteristics of digital circuits are relatively unimportant. Control accuracy depends only on the stability of the input signal frequency.

  16. Dynamic verification of a digital flight control system.

    NASA Technical Reports Server (NTRS)

    Nabers, J. P., Jr.; Bowman, J. D.

    1972-01-01

    Development of a digital control system dynamic variation technique which accounts for the limitation of available frequency response analyzers. Digital control system theory is briefly reviewed, and generation of the necessary theoretical frequency responses is discussed. Results of the dynamic verification of a digital control system for a Saturn V launch vehicle are presented, and attention is given to the limitations of this technique along with its applicability to other types of digital control systems. A technique for performing open-loop frequency response analyses of a flight program implemented in a 'flight-type' digital computer and interface hardware with vehicle dynamics simulated on an analog computer is described.

  17. The effects of lightning on digital flight control systems

    NASA Technical Reports Server (NTRS)

    Plumer, J. A.; Malloy, W. A.; Craft, J. B.

    1976-01-01

    Present practices in lightning protection of aircraft deal primarily with the direct effects of lightning, such as structural damage and ignition of fuel vapors. There is increasing evidence of troublesome electromagnetic effects, however, in aircraft employing solid-state microelectronics in critical navigation, instrumentation and control functions. The potential impact of these indirect effects on critical systems such as digital fly by wire (DFBW) flight controls was studied. The results indicate a need for positive steps to be taken during the design of future fly by wire systems to minimize the possibility of hazardous effects from lightning.

  18. Multifunction audio digitizer. [producing direct delta and pulse code modulation

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    An illustrative embodiment of the invention includes apparatus which simultaneously produces both direct delta modulation and pulse code modulation. An input signal, after amplification, is supplied to a window comparator which supplies a polarity control signal to gate the output of a clock to the appropriate input of a binary up-down counter. The control signals provide direct delta modulation while the up-down counter output provides pulse code modulation.

  19. An Inexpensive Digital Gradient Controller for HPLC.

    ERIC Educational Resources Information Center

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  20. An Inexpensive Digital Gradient Controller for HPLC.

    ERIC Educational Resources Information Center

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  1. Components for digitally controlled aircraft engines

    NASA Technical Reports Server (NTRS)

    Meador, J. D.

    1981-01-01

    Control system components suitable for use in digital electronic control systems are defined. Compressor geometry actuation concepts and fuel handling system concepts suitable for use in large high performance turbofan/turbojet engines are included. Eight conceptual system designs were formulated for the actuation of the compressor geometry. Six conceptual system designs were formulated for the engine fuel handling system. Assessment criteria and weighting factors were established and trade studies performed on their candidate systems to establish the relative merits of the various concepts. Fuel pumping and metering systems for small turboshaft engines were also studied. Seven conceptual designs were formulated, and trade studies performed. A simplified bypassing fuel metering scheme was selected and a preliminary design defined.

  2. Space shuttle digital flight control system

    NASA Technical Reports Server (NTRS)

    Minott, G. M.; Peller, J. B.; Cox, K. J.

    1976-01-01

    The space shuttle digital, fly by wire, flight control system presents an interesting challenge in avionics system design. In residence in each of four redundant general purpose computers at lift off are the guidance, navigation, and control algorithms for the entire flight. The mission is divided into several flight segments: first stage ascent, second stage ascent; abort to launch site, abort once around; on orbit operations, entry, terminal area energy management; and approach and landing. The FCS is complicated in that it must perform the functions to fly the shuttle as a boost vehicle, as a spacecraft, as a reentry vehicle, and as a conventional aircraft. The crew is provided with both manual and automatic modes of operations in all flight phases including touchdown and rollout.

  3. Optimal digital redesign of continuous-time controllers

    NASA Technical Reports Server (NTRS)

    Shieh, Leang S.; Zhang, Jian L.; Coleman, Norman P.

    1991-01-01

    This paper proposes a new optimal digital redesign technique for finding a dynamic digital control law from the available analog counterpart and simultaneously minimizing a quadratic performance index. The proposed technique can be applied to a system with a more general class of reference inputs, and the developed digital regulator can be implemented using low cost microcomputers.

  4. Digital adaptive control of a VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Reid, G. F.

    1976-01-01

    A technique has been developed for calculating feedback and feedforward gain matrices that stabilize a VTOL aircraft while enabling it to track input commands of forward and vertical velocity. Leverrier's algorithm is used in a procedure for determining a set of state variable, feedback gains that force the closed loop poles and zeroes of one pilot input transfer function to be at preselected positions in the s plane. This set of feedback gains is then used to calculate the feedback and feedforward gains for the velocity command controller. The method is computationally attractive since the gains are determined by solving systems of linear, simultaneous equations. Responses obtained using a digital simulation of the longitudinal dynamics of the CH-47 helicopter are presented.

  5. Digital Control of Flight Simulator Motion Base Actuator.

    DTIC Science & Technology

    1984-01-01

    SYNTHESIS 3.1 Basic Considerations As a starting point for digital controller design a proportional plus integral ( PI ) control law of the form - V(s...on closed loop stability arising from digital realization of the PI control law, computational time delay and sampling have to be taken into

  6. Digital Camera Control for Faster Inspection

    NASA Technical Reports Server (NTRS)

    Brown, Katharine; Siekierski, James D.; Mangieri, Mark L.; Dekome, Kent; Cobarruvias, John; Piplani, Perry J.; Busa, Joel

    2009-01-01

    Digital Camera Control Software (DCCS) is a computer program for controlling a boom and a boom-mounted camera used to inspect the external surface of a space shuttle in orbit around the Earth. Running in a laptop computer in the space-shuttle crew cabin, DCCS commands integrated displays and controls. By means of a simple one-button command, a crewmember can view low- resolution images to quickly spot problem areas and can then cause a rapid transition to high- resolution images. The crewmember can command that camera settings apply to a specific small area of interest within the field of view of the camera so as to maximize image quality within that area. DCCS also provides critical high-resolution images to a ground screening team, which analyzes the images to assess damage (if any); in so doing, DCCS enables the team to clear initially suspect areas more quickly than would otherwise be possible and further saves time by minimizing the probability of re-imaging of areas already inspected. On the basis of experience with a previous version (2.0) of the software, the present version (3.0) incorporates a number of advanced imaging features that optimize crewmember capability and efficiency.

  7. Directional control of radiant heat

    NASA Technical Reports Server (NTRS)

    Howell, J. R.; Perlmutter, M.

    1970-01-01

    Surface with grooves having flat bases gives directional emissivities and absorptivities that can be made to approximate a perfect directional surface. Radiant energy can then be transferred in desired directions.

  8. Digital Quantification of miRNA directly in plasma using Integrated Comprehensive Droplet Digital Detection

    PubMed Central

    Zhang, Kaixiang; Kang, Dong-Ku; Ali, M. Monsur; Liu, Linan; Labanieh, Louai; Lu, Mengrou; Riazifar, Hamidreza; Nguyen, Thi N.; Zell, Jason A.; Digman, Michelle A.; Gratton, Enrico

    2015-01-01

    Quantification of miRNAs in blood can be potentially used for early disease detection, surveillance monitoring and drug response evaluation. However, quantitative and robust measurement of miRNAs in blood is still a major challenge in large part due to their low concentration and complicated sample preparation processes typically required in conventional assays. Here, we present the ‘Integrated Comprehensive Droplet Digital Detection’ (IC 3D) system where the plasma sample containing target miRNAs is encapsulated into microdroplets, enzymatically amplified and digitally counted using a novel, high-throughput 3D particle counter. Using Let-7a as a target, we demonstrate that IC 3D can specifically quantify target miRNA directly from blood plasma at extremely low concentrations ranging from 10s to 10,000 copies/mL in ≤ 3 hours without the need for sample processing such as RNA extraction. Using this new tool, we demonstrate that target miRNA content in colon cancer patient blood is significantly higher than that in healthy donor samples. Our IC 3D system has the potential to introduce a new paradigm for rapid, sensitive and specific detection of low-abundance biomarkers in biological samples with minimal sample processing. PMID:26387763

  9. Digital quantification of miRNA directly in plasma using integrated comprehensive droplet digital detection.

    PubMed

    Zhang, Kaixiang; Kang, Dong-Ku; Ali, M Monsur; Liu, Linan; Labanieh, Louai; Lu, Mengrou; Riazifar, Hamidreza; Nguyen, Thi N; Zell, Jason A; Digman, Michelle A; Gratton, Enrico; Li, Jinghong; Zhao, Weian

    2015-11-07

    Quantification of miRNAs in blood can be potentially used for early disease detection, surveillance monitoring and drug response evaluation. However, quantitative and robust measurement of miRNAs in blood is still a major challenge in large part due to their low concentration and complicated sample preparation processes typically required in conventional assays. Here, we present the 'Integrated Comprehensive Droplet Digital Detection' (IC 3D) system where the plasma sample containing target miRNAs is encapsulated into microdroplets, enzymatically amplified and digitally counted using a novel, high-throughput 3D particle counter. Using Let-7a as a target, we demonstrate that IC 3D can specifically quantify target miRNA directly from blood plasma at extremely low concentrations ranging from 10s to 10 000 copies per mL in ≤3 hours without the need for sample processing such as RNA extraction. Using this new tool, we demonstrate that target miRNA content in colon cancer patient blood is significantly higher than that in healthy donor samples. Our IC 3D system has the potential to introduce a new paradigm for rapid, sensitive and specific detection of low-abundance biomarkers in biological samples with minimal sample processing.

  10. Digital Technology Use by the Students and English Teachers and Self-Directed Language Learning

    ERIC Educational Resources Information Center

    Sert, Nehir; Boynuegri, Ebru

    2017-01-01

    The digital era is a new challenge for teachers. While children get acquainted with the digital technology before the age of six, teachers, who have encountered with the digital world at a later time in their lives, struggle with it. Self-directed learning, which is crucial for lifelong learning, can be enhanced by the use technology particularly…

  11. A digital controlled solar array regulator employing the charge control

    SciTech Connect

    Cho, Y.J.; Cho, B.H.

    1997-12-31

    A microprocessor controlled SAR system is presented. The inner analog loops employing the charge current control scheme continuously regulate the solar array output power according to the reference value generated by the ECU. The ECU consists of the peak power tracking and the battery charge current regulation algorithm. Modeling, analysis and a design procedure of the inner loops and the system loop are presented taking into account of interaction between the inner analog loops and the outer digital loops. Utilizing the inherent characteristics of the inner voltage and current loop, the system dynamic performance and stability can be optimized up to the speed limit of the microprocessor.

  12. Software Defined Radio (SDR) and Direct Digital Synthesizer (DDS) for NMR/MRI instruments at low-field.

    PubMed

    Asfour, Aktham; Raoof, Kosai; Yonnet, Jean-Paul

    2013-11-27

    A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital Synthesizer (DDS) for pulse generation, a Software Defined Radio (SDR) for a digital receiving of NMR signals and a Digital Signal Processor (DSP) for system control and for the generation of the gradient signals (pulse programmer). The SDR includes a direct analog-to-digital conversion and a Digital Down Conversion (digital quadrature demodulation, decimation filtering, processing gain…). The various aspects of the concept and of the realization are addressed with some details. These include both hardware design and software considerations. One of the underlying ideas is to enable such NMR systems to "enjoy" from existing advanced technology that have been realized in other research areas, especially in telecommunication domain. Another goal is to make these systems easy to build and replicate so as to help research groups in realizing dedicated NMR desktops for a large palette of new applications. We also would like to give readers an idea of the current trends in this field. The performances of the developed electronics are discussed throughout the paper. First FID (Free Induction Decay) signals are also presented. Some development perspectives of our work in the area of low-field NMR/MRI will be finally addressed.

  13. Software Defined Radio (SDR) and Direct Digital Synthesizer (DDS) for NMR/MRI Instruments at Low-Field

    PubMed Central

    Asfour, Aktham; Raoof, Kosai; Yonnet, Jean-Paul

    2013-01-01

    A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital Synthesizer (DDS) for pulse generation, a Software Defined Radio (SDR) for a digital receiving of NMR signals and a Digital Signal Processor (DSP) for system control and for the generation of the gradient signals (pulse programmer). The SDR includes a direct analog-to-digital conversion and a Digital Down Conversion (digital quadrature demodulation, decimation filtering, processing gain…). The various aspects of the concept and of the realization are addressed with some details. These include both hardware design and software considerations. One of the underlying ideas is to enable such NMR systems to “enjoy” from existing advanced technology that have been realized in other research areas, especially in telecommunication domain. Another goal is to make these systems easy to build and replicate so as to help research groups in realizing dedicated NMR desktops for a large palette of new applications. We also would like to give readers an idea of the current trends in this field. The performances of the developed electronics are discussed throughout the paper. First FID (Free Induction Decay) signals are also presented. Some development perspectives of our work in the area of low-field NMR/MRI will be finally addressed. PMID:24287540

  14. Digital control of magnetic bearings supporting a multimass flexible rotor

    NASA Technical Reports Server (NTRS)

    Keith, F. J.; Williams, R. D.; Allaire, P. E.; Schafer, R. M.

    1993-01-01

    The characteristics of magnetic bearings used to support a three mass flexible rotor operated at speeds up to 14,000 RPM are discussed. The magnetic components of the bearing are of a type reported in the literature previously, but the earlier analog controls were replaced by digital ones. Analog-to-digital and digital-to-analog converters and digital control software were installed in an AT&T PC. This PC-based digital controller was used to operate one of the magnetic bearings on the test rig. Basic proportional-derivative control was applied to the bearings, and the bearing stiffness and damping characteristics were evaluated. Particular attention is paid to the frequency dependent behavior of the stiffness and damping properties, and comparisons are made between the actual controllers and ideal proportional-derivative control.

  15. What can formal methods offer to digital flight control systems design

    NASA Technical Reports Server (NTRS)

    Good, Donald I.

    1990-01-01

    Formal methods research begins to produce methods which will enable mathematic modeling of the physical behavior of digital hardware and software systems. The development of these methods directly supports the NASA mission of increasing the scope and effectiveness of flight system modeling capabilities. The conventional, continuous mathematics that is used extensively in modeling flight systems is not adequate for accurate modeling of digital systems. Therefore, the current practice of digital flight control system design has not had the benefits of extensive mathematical modeling which are common in other parts of flight system engineering. Formal methods research shows that by using discrete mathematics, very accurate modeling of digital systems is possible. These discrete modeling methods will bring the traditional benefits of modeling to digital hardware and hardware design. Sound reasoning about accurate mathematical models of flight control systems can be an important part of reducing risk of unsafe flight control.

  16. Event-Triggered Distributed Average Consensus Over Directed Digital Networks With Limited Communication Bandwidth.

    PubMed

    Li, Huaqing; Chen, Guo; Huang, Tingwen; Dong, Zhaoyang; Zhu, Wei; Gao, Lan

    2016-12-01

    In this paper, we consider the event-triggered distributed average-consensus of discrete-time first-order multiagent systems with limited communication data rate and general directed network topology. In the framework of digital communication network, each agent has a real-valued state but can only exchange finite-bit binary symbolic data sequence with its neighborhood agents at each time step due to the digital communication channels with energy constraints. Novel event-triggered dynamic encoder and decoder for each agent are designed, based on which a distributed control algorithm is proposed. A scheme that selects the number of channel quantization level (number of bits) at each time step is developed, under which all the quantizers in the network are never saturated. The convergence rate of consensus is explicitly characterized, which is related to the scale of network, the maximum degree of nodes, the network structure, the scaling function, the quantization interval, the initial states of agents, the control gain and the event gain. It is also found that under the designed event-triggered protocol, by selecting suitable parameters, for any directed digital network containing a spanning tree, the distributed average consensus can be always achieved with an exponential convergence rate based on merely one bit information exchange between each pair of adjacent agents at each time step. Two simulation examples are provided to illustrate the feasibility of presented protocol and the correctness of the theoretical results.

  17. 47 CFR 97.221 - Automatically controlled digital station.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Automatically controlled digital station. 97.221 Section 97.221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Special Operations § 97.221 Automatically controlled digital...

  18. 47 CFR 97.221 - Automatically controlled digital station.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Automatically controlled digital station. 97.221 Section 97.221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Special Operations § 97.221 Automatically controlled digital...

  19. 47 CFR 97.221 - Automatically controlled digital station.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Automatically controlled digital station. 97.221 Section 97.221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Special Operations § 97.221 Automatically controlled digital...

  20. 47 CFR 97.221 - Automatically controlled digital station.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Automatically controlled digital station. 97.221 Section 97.221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Special Operations § 97.221 Automatically controlled digital...

  1. 47 CFR 97.221 - Automatically controlled digital station.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Automatically controlled digital station. 97.221 Section 97.221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Special Operations § 97.221 Automatically controlled digital...

  2. COSPAS/SARSAT 406-MHz emergency beacon digital controller

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    1988-01-01

    The digital control portion of a low-cost 406-MHz COSPAS/SARSAT emergency beacon has been designed and breadboarded at the NASA Lewis Research Center. This report discusses the requirements and design tradeoffs of the digital controller and describes the hardware and software design, which is available only to United States citizens and companies.

  3. A Study of Direct Digital Manufactured RF/Microwave Packaging

    NASA Astrophysics Data System (ADS)

    Stratton, John W. I.

    Various facets of direct digital manufactured (DDM) microwave packages are studied. The rippled surface inherent in fused deposition modeling (FDM) fabricated geometries is modeled in Ansoft HFSS, and its effect on the performance of microstrip transmission lines is assessed via simulation and measurement. The thermal response of DDM microstrip transmission lines is analyzed over a range of RF input powers, and linearity is confirmed over that range. Two IC packages are embedded into DDM printed circuit boards, and their performance is analyzed. The first is a low power RF switch, and the second is an RF front end device that includes a low noise amplifier (LNA) and a power amplifier (PA). The RF switch is shown to perform well, as compared to a layout designed for a Rogers 4003C microwave laminate substrate. The LNA performs within datasheet specifications. The power amplifier generates substantial heat, so a thermal management attempt is described. Finally, a capacitively loaded 6dB Wilkinson power divider is designed and fabricated using DDM techniques and materials. Its performance is analyzed and compared to simulation. The device is shown to compare favorably to a similar device fabricated on a Rogers 4003C microwave laminate using traditional printed circuit board techniques.

  4. Digital Flight Control System for Tactical Fighter. Volume 1. Digital Flight Control System Analysis

    DTIC Science & Technology

    1974-06-01

    30 34 34 37 38 41 45 47 47 53 55 5fi 5 « (il R4 G7 * ..it hv^irWMiM MraiMtMiaiiMiflMaiMifliarii^^MMiyiiJ ■.pi.miwwuiwi.iiii.iii, mm...the Digital Control Software System 5 (DIGIKON) 3 Control and Computational Requirements 7 4 Interactive Analysis, Design, and Performance...Evaluation 7 in the s-Plane 5 Interactive Analysis, Design, and Performance Evaluation 8 in the s-z Plane 6 Interactive Analysis, Design, and Performance

  5. Digital control of the Kuiper Airborne Observatory telescope

    NASA Technical Reports Server (NTRS)

    Mccormack, Ann C.; Snyder, Philip K.

    1989-01-01

    The feasibility of using a digital controller to stabilize a telescope mounted in an airplane is investigated. The telescope is a 30 in. infrared telescope mounted aboard a NASA C-141 aircraft known as the Kuiper Airborne Observatory. Current efforts to refurbish the 14-year-old compensation system have led to considering a digital controller. A typical digital controller is modeled and added into the telescope system model. This model is simulated on a computer to generate the Bode plots and time responses which determine system stability and performance parameters. Important aspects of digital control system hardware are discussed. A summary of the findings shows that a digital control system would result in satisfactory telescope performance.

  6. Digital Flight Control System Redundancy Study

    DTIC Science & Technology

    1974-07-01

    microseconds to transfer the data to a memory location on DMA, 2 274 4P4 275 or to an accumulator if under program control. While it is possible, in principle ...March, 1973, to May, 1974, by the Flight Systems Division of The Bendix Corporation, Teterboro, New Jersey under Air Force Contract No. 333615-73-C...3035 AFFDL. The work was administered under the direction of the Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Ohio, 45433, by

  7. How Digital Scaffolds in Games Direct Problem-Solving Behaviors

    ERIC Educational Resources Information Center

    Sun, Chuen-Tsai; Wang, Dai-Yi; Chan, Hui-Ling

    2011-01-01

    Digital systems offer computational power and instant feedback. Game designers are using these features to create scaffolding tools to reduce player frustration. However, researchers are finding some unexpected effects of scaffolding on strategy development and problem-solving behaviors. We used a digital Sudoku game named "Professor Sudoku" to…

  8. Note: Directly measuring the direct digital synthesizer frequency chirp-rate for an atom interferometer.

    PubMed

    Tao, Juan-Juan; Zhou, Min-Kang; Zhang, Qiao-Zhen; Cui, Jia-Feng; Duan, Xiao-Chun; Shao, Cheng-Gang; Hu, Zhong-Kun

    2015-09-01

    During gravity measurements with Raman type atom interferometry, the frequency of the laser used to drive Raman transition is scanned by chirping the frequency of a direct digital synthesizer (DDS), and the local gravity is determined by precisely measuring the chip rate α of DDS. We present an effective method that can directly evaluate the frequency chirp rate stability of our DDS. By mixing a pair of synchronous linear sweeping signals, the chirp rate fluctuation is precisely measured with a frequency counter. The measurement result shows that the relative α instability can reach 5.7 × 10(-11) in 1 s, which is neglectable in a 10(-9) g level atom interferometry gravimeter.

  9. Note: Directly measuring the direct digital synthesizer frequency chirp-rate for an atom interferometer

    SciTech Connect

    Tao, Juan-Juan; Zhou, Min-Kang E-mail: zmk@hust.edu.cn; Zhang, Qiao-Zhen; Cui, Jia-Feng; Duan, Xiao-Chun; Shao, Cheng-Gang; Hu, Zhong-Kun E-mail: zmk@hust.edu.cn

    2015-09-15

    During gravity measurements with Raman type atom interferometry, the frequency of the laser used to drive Raman transition is scanned by chirping the frequency of a direct digital synthesizer (DDS), and the local gravity is determined by precisely measuring the chip rate α of DDS. We present an effective method that can directly evaluate the frequency chirp rate stability of our DDS. By mixing a pair of synchronous linear sweeping signals, the chirp rate fluctuation is precisely measured with a frequency counter. The measurement result shows that the relative α instability can reach 5.7 × 10{sup −11} in 1 s, which is neglectable in a 10{sup −9} g level atom interferometry gravimeter.

  10. Airborne Digital Sensor System and GPS-aided inertial technology for direct geopositioning in rough terrain

    USGS Publications Warehouse

    Sanchez, Richard D.

    2004-01-01

    High-resolution airborne digital cameras with onboard data collection based on the Global Positioning System (GPS) and inertial navigation systems (INS) technology may offer a real-time means to gather accurate topographic map information by reducing ground control and eliminating aerial triangulation. Past evaluations of this integrated system over relatively flat terrain have proven successful. The author uses Emerge Digital Sensor System (DSS) combined with Applanix Corporation?s Position and Orientation Solutions for Direct Georeferencing to examine the positional mapping accuracy in rough terrain. The positional accuracy documented in this study did not meet large-scale mapping requirements owing to an apparent system mechanical failure. Nonetheless, the findings yield important information on a new approach for mapping in Antarctica and other remote or inaccessible areas of the world.

  11. A digital control system for high level acoustic noise generation

    NASA Technical Reports Server (NTRS)

    Lee, John P.; Bosco, Jerry H.

    1986-01-01

    As part of the modernization of the Acoustic Test Facility at Lockheed Missiles and Space Company, Sunnyvale, a digital acoustic control system was designed and built. The requirements imposed by Lockheed on the control system and the degree to which those requirements were met are discussed. Acceptance test results as well as some of the features of the digital control system not found in traditional manual control systems are discussed.

  12. The effects of lightning on digital flight control systems

    NASA Technical Reports Server (NTRS)

    Plumer, J. A.; Malloy, W. A.; Craft, J. B.

    1975-01-01

    Present practices in lightning protection of aircraft deal primarily with the direct effects of lightning, such as structural damage and ignition of fuel vapors. There is increasing evidence of troublesome electromagnetic effects, however, in aircraft employing solid-state microelectronics in critical navigation, instrumentation and control functions. The potential impact of these indirect effects on critical systems such as digital fly-by-wire (DFBW) flight controls has been studied by several recent research programs, including an experimental study of lightning-induced voltages in the NASA F8 DFBW airplane. The results indicate a need for positive steps to be taken during the design of future fly-by-wire systems to minimize the possibility of hazardous effects from lightning.

  13. Digit forces bias sensorimotor transformations underlying control of fingertip position.

    PubMed

    Shibata, Daisuke; Kappers, Astrid M L; Santello, Marco

    2014-01-01

    Humans are able to modulate digit forces as a function of position despite changes in digit placement that might occur from trial to trial or when changing grip type for object manipulation. Although this phenomenon is likely to rely on sensing the position of the digits relative to each other and the object, the underlying mechanisms remain unclear. To address this question, we asked subjects (n = 30) to match perceived vertical distance between the center of pressure (CoP) of the thumb and index finger pads (dy ) of the right hand ("reference" hand) using the same hand ("test" hand). The digits of reference hand were passively placed collinearly (dy = 0 mm). Subjects were then asked to exert different combinations of normal and tangential digit forces (Fn and Ftan , respectively) using the reference hand and then match the memorized dy using the test hand. The reference hand exerted Ftan of thumb and index finger in either same or opposite direction. We hypothesized that, when the tangential forces of the digits are produced in opposite directions, matching error (1) would be biased toward the directions of the tangential forces; and (2) would be greater when the remembered relative contact points are matched with negligible digit force production. For the test hand, digit forces were either negligible (0.5-1 N, 0 ± 0.25 N; Experiment 1) or the same as those exerted by the reference hand (Experiment 2).Matching error was biased towards the direction of digit tangential forces: thumb CoP was placed higher than the index finger CoP when thumb and index finger Ftan were directed upward and downward, respectively, and vice versa (p < 0.001). However, matching error was not dependent on whether the reference and test hand exerted similar or different forces. We propose that the expected sensory consequence of motor commands for tangential forces in opposite directions overrides estimation of fingertip position through haptic sensory feedback.

  14. Digit forces bias sensorimotor transformations underlying control of fingertip position

    PubMed Central

    Shibata, Daisuke; Kappers, Astrid M. L.; Santello, Marco

    2014-01-01

    Humans are able to modulate digit forces as a function of position despite changes in digit placement that might occur from trial to trial or when changing grip type for object manipulation. Although this phenomenon is likely to rely on sensing the position of the digits relative to each other and the object, the underlying mechanisms remain unclear. To address this question, we asked subjects (n = 30) to match perceived vertical distance between the center of pressure (CoP) of the thumb and index finger pads (dy) of the right hand (“reference” hand) using the same hand (“test” hand). The digits of reference hand were passively placed collinearly (dy = 0 mm). Subjects were then asked to exert different combinations of normal and tangential digit forces (Fn and Ftan, respectively) using the reference hand and then match the memorized dy using the test hand. The reference hand exerted Ftan of thumb and index finger in either same or opposite direction. We hypothesized that, when the tangential forces of the digits are produced in opposite directions, matching error (1) would be biased toward the directions of the tangential forces; and (2) would be greater when the remembered relative contact points are matched with negligible digit force production. For the test hand, digit forces were either negligible (0.5–1 N, 0 ± 0.25 N; Experiment 1) or the same as those exerted by the reference hand (Experiment 2).Matching error was biased towards the direction of digit tangential forces: thumb CoP was placed higher than the index finger CoP when thumb and index finger Ftan were directed upward and downward, respectively, and vice versa (p < 0.001). However, matching error was not dependent on whether the reference and test hand exerted similar or different forces. We propose that the expected sensory consequence of motor commands for tangential forces in opposite directions overrides estimation of fingertip position through haptic sensory feedback. PMID:25136304

  15. REVIEW OF NRC APPROVED DIGITAL CONTROL SYSTEMS ANALYSIS

    SciTech Connect

    D.W. Markman

    1999-09-17

    Preliminary design concepts for the proposed Subsurface Repository at Yucca Mountain indicate extensive reliance on modern, computer-based, digital control technologies. The purpose of this analysis is to investigate the degree to which the U. S. Nuclear Regulatory Commission (NRC) has accepted and approved the use of digital control technology for safety-related applications within the nuclear power industry. This analysis reviews cases of existing digitally-based control systems that have been approved by the NRC. These cases can serve as precedence for using similar types of digitally-based control technologies within the Subsurface Repository. While it is anticipated that the Yucca Mountain Project (YMP) will not contain control systems as complex as those required for a nuclear power plant, the review of these existing NRC approved applications will provide the YMP with valuable insight into the NRCs review process and design expectations for safety-related digital control systems. According to the YMP Compliance Program Guidance, portions of various NUREGS, Regulatory Guidelines, and nuclear IEEE standards the nuclear power plant safety related concept would be applied to some of the designs on a case-by-case basis. This analysis will consider key design methods, capabilities, successes, and important limitations or problems of selected control systems that have been approved for use in the Nuclear Power industry. An additional purpose of this analysis is to provide background information in support of further development of design criteria for the YMP. The scope and primary objectives of this analysis are to: (1) Identify and research the extent and precedence of digital control and remotely operated systems approved by the NRC for the nuclear power industry. Help provide a basis for using and relying on digital technologies for nuclear related safety critical applications. (2) Identify the basic control architecture and methods of key digital control

  16. Direct Observation of Two Proton Radioactivity Using Digital Photography

    SciTech Connect

    Rykaczewski, Krzysztof Piotr; Pfutzner, M.; Dominik, Wojciech; Janas, Z.; Miernik, K.; Bingham, C. R.; Czyrkowski, Henryk; Cwiok, Mikolaj; Darby, Iain; Dabrowski, Ryszard; Ginter, T. N.; Grzywacz, Robert Kazimierz; Karny, M.; Korgul, A.; Kusmierz, Waldemar; Liddick, Sean; Rajabali, Mustafa; Stolz, A.

    2007-01-01

    Recently the observation of a new type of spontaneous radioactive decay has been claimed in which two protons are simultaneously ejected by an atomic nucleus from the ground state1,2,3. Experimental data obtained for the extremely neutron-deficient nuclei 45Fe and 54Zn, were interpreted as the first evidence of such a decay mode which has been sought since 1960.4 However, the technique applied in those studies allowed only measurements of the decay time and the total energy released. Particles emitted in the decay were not identified and the conclusions had to be supported by theoretical arguments. Here we show for the first time, directly and unambiguously, that 45Fe indeed disintegrates by two-proton decay. Furthermore, we demonstrate that the decay branch of this isotope leads to various particle emission channels including two-proton and three-proton emission. To achieve this result we have developed a new type of detector V the Optical Time Projection Chamber (OTPC) in which digital photography is applied to nuclear physics for the first time. The detector records images of tracks from charged particles, allowing for their unambiguous identification and the reconstruction of decay events in three dimensions. This new and simple technique provides a powerful method to identify exotic decay channels involving emission of charged particles. It is expected that further studies with the OTPC device will yield important information on nuclei located at and beyond the proton drip-line, thus providing new material for testing and improving models of very unstable atomic nuclei.

  17. Research study on IPS digital controller design

    NASA Technical Reports Server (NTRS)

    Kuo, B. C.; Folkerts, C.

    1976-01-01

    The performance is investigated of the simplified continuous-data model of the Instrument Pointing System (IPS). Although the ultimate objective is to study the digital model of the system, knowledge on the performance of the continuous-data model is important in the sense that the characteristics of the digital system should approach those of the continuous-data system as the sampling period approaches zero.

  18. Digital Controller For Laser-Beam-Steering Subsystem

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon

    1995-01-01

    Report presents additional information about proposed apparatus described in "Beam-Steering Subsystem for Laser Communication" (NPO-19069). Discusses design of digital beam-steering control subsystem and, in particular, that part of design pertaining to digital compensation for frequency response of steering mirror.

  19. Implementation of Adaptive Digital Controllers on Programmable Logic Devices

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; King, Kenneth D.; Smith, Keary J.; Monenegro, Justino (Technical Monitor)

    2002-01-01

    Much has been made of the capabilities of FPGA's (Field Programmable Gate Arrays) in the hardware implementation of fast digital signal processing. Such capability also makes an FPGA a suitable platform for the digital implementation of closed loop controllers. Other researchers have implemented a variety of closed-loop digital controllers on FPGA's. Some of these controllers include the widely used proportional-integral-derivative (PID) controller, state space controllers, neural network and fuzzy logic based controllers. There are myriad advantages to utilizing an FPGA for discrete-time control functions which include the capability for reconfiguration when SRAM-based FPGA's are employed, fast parallel implementation of multiple control loops and implementations that can meet space level radiation tolerance requirements in a compact form-factor. Generally, a software implementation on a DSP (Digital Signal Processor) or microcontroller is used to implement digital controllers. At Marshall Space Flight Center, the Control Electronics Group has been studying adaptive discrete-time control of motor driven actuator systems using digital signal processor (DSP) devices. While small form factor, commercial DSP devices are now available with event capture, data conversion, pulse width modulated (PWM) outputs and communication peripherals, these devices are not currently available in designs and packages which meet space level radiation requirements. In general, very few DSP devices are produced that are designed to meet any level of radiation tolerance or hardness. The goal of this effort is to create a fully digital, flight ready controller design that utilizes an FPGA for implementation of signal conditioning for control feedback signals, generation of commands to the controlled system, and hardware insertion of adaptive control algorithm approaches. An alternative is required for compact implementation of such functionality to withstand the harsh environment

  20. Digital control of high-intensity acoustic testing

    NASA Technical Reports Server (NTRS)

    Slusser, R. A.

    1975-01-01

    To eliminate previous system instabilities and control high-intensity acoustic tests, a digital control vibration test system is modified by a software change. Three systems for the control of acoustic testing are compared: a hybrid digital/analog system, a digital vibration system, and the same digital vibration system modified by a software change to allow acoustic testing. It is shown that the hybrid system and the modified vibration system exhibit almost equal performance, although the hybrid system performs testing twice as fast. The development of a specialized acoustic test control system is justified since it costs far less than the general-purpose vibration control system. However, the latter is much easier to set up for a test, which is important in preventing overtesting of valuable spacecraft components.

  1. 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.

  2. High-side Digitally Current Controlled Biphasic Bipolar Microstimulator

    PubMed Central

    Hanson, Timothy L.; Ómarsson, Björn; O'Doherty, Joseph E.; Peikon, Ian D.; Lebedev, Mikhail; Nicolelis, Miguel AL.

    2012-01-01

    Electrical stimulation of nervous tissue has been extensively used as both a tool in experimental neuroscience research and as a method for restoring of neural functions in patients suffering from sensory and motor disabilities. In the central nervous system, intracortical microstimulation (ICMS) has been shown to be an effective method for inducing or biasing perception, including visual and tactile sensation. ICMS also holds promise for enabling brain-machine-brain interfaces (BMBIs) by directly writing information into the brain. Here we detail the design of a high-side, digitally current-controlled biphasic, bipolar microstimulator, and describe the validation of the device in vivo. As many applications of this technique, including BMBIs, require recording as well as stimulation, we pay careful attention to isolation of the stimulus channels and parasitic current injection. With the realized device and standard recording hardware - without active artifact rejection - we are able to observe stimulus artifacts of less than 2 ms in duration. PMID:22328184

  3. High-side digitally current controlled biphasic bipolar microstimulator.

    PubMed

    Hanson, Timothy L; Ómarsson, Björn; O'Doherty, Joseph E; Peikon, Ian D; Lebedev, Mikhail A; Nicolelis, Miguel A L

    2012-05-01

    Electrical stimulation of nervous tissue has been extensively used as both a tool in experimental neuroscience research and as a method for restoring of neural functions in patients suffering from sensory and motor disabilities. In the central nervous system, intracortical microstimulation (ICMS) has been shown to be an effective method for inducing or biasing perception, including visual and tactile sensation. ICMS also holds promise for enabling brain-machine-brain interfaces (BMBIs) by directly writing information into the brain. Here we detail the design of a high-side, digitally current-controlled biphasic, bipolar microstimulator, and describe the validation of the device in vivo. As many applications of this technique, including BMBIs, require recording as well as stimulation, we pay careful attention to isolation of the stimulus channels and parasitic current injection. With the realized device and standard recording hardware-without active artifact rejection-we are able to observe stimulus artifacts of less than 2 ms in duration.

  4. 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.

  5. Trends in software reliability for digital flight control

    NASA Technical Reports Server (NTRS)

    Hecht, H.; Hecht, M.

    1983-01-01

    Software error data of major recent Digital Flight Control Systems Development Programs. The report summarizes the data, compare these data with similar data from previous surveys and identifies trends and disciplines to improve software reliability.

  6. 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.

  7. 76 FR 62642 - Digital Broadcast Television Redistribution Control; Corrections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-11

    ... From the Federal Register Online via the Government Publishing Office ] FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Digital Broadcast Television Redistribution Control; Corrections AGENCY: Federal Communications Commission. ACTION: Technical amendment. SUMMARY: The Federal Communications Commission (FCC)...

  8. 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.

  9. Apparatus for direct-to-digital spatially-heterodyned holography

    DOEpatents

    Thomas, Clarence E.; Hanson, Gregory R.

    2006-12-12

    An apparatus operable to record a spatially low-frequency heterodyne hologram including spatially heterodyne fringes for Fourier analysis includes: a laser; a beamsplitter optically coupled to the laser; an object optically coupled to the beamsplitter; a focusing lens optically coupled to both the beamsplitter and the object; a digital recorder optically coupled to the focusing lens; and a computer that performs a Fourier transform, applies a digital filter, and performs an inverse Fourier transform. A reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form a spatially low-frequency heterodyne hologram including spatially heterodyne fringes for Fourier analysis which is recorded by the digital recorder, and the computer transforms the recorded spatially low-frequency heterodyne hologram including spatially heterodyne fringes and shifts axes in Fourier space to sit on top of a heterodyne carrier frequency defined by an angle between the reference beam and the object beam and cuts off signals around an original origin before performing the inverse Fourier transform.

  10. Implementation of Adaptive Digital Controllers on Programmable Logic Devices

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; King, Kenneth D.; Smith, Keary J.; Ormsby, John (Technical Monitor)

    2002-01-01

    Much has been made of the capabilities of FPGA's (Field Programmable Gate Arrays) in the hardware implementation of fast digital signal processing (DSP) functions. Such capability also makes and FPGA a suitable platform for the digital implementation of closed loop controllers. There are myriad advantages to utilizing an FPGA for discrete-time control functions which include the capability for reconfiguration when SRAM- based FPGA's are employed, fast parallel implementation of multiple control loops and implementations that can meet space level radiation tolerance in a compact form-factor. Other researchers have presented the notion that a second order digital filter with proportional-integral-derivative (PID) control functionality can be implemented in an FPGA. At Marshall Space Flight Center, the Control Electronics Group has been studying adaptive discrete-time control of motor driven actuator systems using digital signal processor (DSF) devices. Our goal is to create a fully digital, flight ready controller design that utilizes an FPGA for implementation of signal conditioning for control feedback signals, generation of commands to the controlled system, and hardware insertion of adaptive control algorithm approaches. While small form factor, commercial DSP devices are now available with event capture, data conversion, pulse width modulated outputs and communication peripherals, these devices are not currently available in designs and packages which meet space level radiation requirements. Meeting our goals requires alternative compact implementation of such functionality to withstand the harsh environment encountered on spacecraft. Radiation tolerant FPGA's are a feasible option for reaching these goals.

  11. Implementation of Adaptive Digital Controllers on Programmable Logic Devices

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; King, Kenneth D.; Smith, Keary J.; Ormsby, John (Technical Monitor)

    2002-01-01

    Much has been made of the capabilities of FPGA's (Field Programmable Gate Arrays) in the hardware implementation of fast digital signal processing (DSP) functions. Such capability also makes and FPGA a suitable platform for the digital implementation of closed loop controllers. There are myriad advantages to utilizing an FPGA for discrete-time control functions which include the capability for reconfiguration when SRAM- based FPGA's are employed, fast parallel implementation of multiple control loops and implementations that can meet space level radiation tolerance in a compact form-factor. Other researchers have presented the notion that a second order digital filter with proportional-integral-derivative (PID) control functionality can be implemented in an FPGA. At Marshall Space Flight Center, the Control Electronics Group has been studying adaptive discrete-time control of motor driven actuator systems using digital signal processor (DSF) devices. Our goal is to create a fully digital, flight ready controller design that utilizes an FPGA for implementation of signal conditioning for control feedback signals, generation of commands to the controlled system, and hardware insertion of adaptive control algorithm approaches. While small form factor, commercial DSP devices are now available with event capture, data conversion, pulse width modulated outputs and communication peripherals, these devices are not currently available in designs and packages which meet space level radiation requirements. Meeting our goals requires alternative compact implementation of such functionality to withstand the harsh environment encountered on spacecraft. Radiation tolerant FPGA's are a feasible option for reaching these goals.

  12. Implementation of Adaptive Digital Controllers on Programmable Logic Devices

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; King, Kenneth D.; Smith, Keary J.; Montenegro, Justino (Technical Monitor)

    2002-01-01

    Much has been made of the capabilities of Field Programmable Gate Arrays (FPGA's) in the hardware implementation of fast digital signal processing functions. Such capability also makes an FPGA a suitable platform for the digital implementation of closed loop controllers. Other researchers have implemented a variety of closed-loop digital controllers on FPGA's. Some of these controllers include the widely used Proportional-Integral-Derivative (PID) controller, state space controllers, neural network and fuzzy logic based controllers. There are myriad advantages to utilizing an FPGA for discrete-time control functions which include the capability for reconfiguration when SRAM- based FPGA's are employed, fast parallel implementation of multiple control loops and implementations that can meet space level radiation tolerance requirements in a compact form-factor. Generally, a software implementation on a Digital Signal Processor (DSP) device or microcontroller is used to implement digital controllers. At Marshall Space Flight Center, the Control Electronics Group has been studying adaptive discrete-time control of motor driven actuator systems using DSP devices. While small form factor, commercial DSP devices are now available with event capture, data conversion, Pulse Width Modulated (PWM) outputs and communication peripherals, these devices are not currently available in designs and packages which meet space level radiation requirements. In general, very few DSP devices are produced that are designed to meet any level of radiation tolerance or hardness. An alternative is required for compact implementation of such functionality to withstand the harsh environment encountered on spacemap. The goal of this effort is to create a fully digital, flight ready controller design that utilizes an FPGA for implementation of signal conditioning for control feedback signals, generation of commands to the controlled system, and hardware insertion of adaptive-control algorithm

  13. Direct Adaptive Control Of An Industrial Robot

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Lee, Thomas; Delpech, Michel

    1992-01-01

    Decentralized direct adaptive control scheme for six-jointed industrial robot eliminates part of overall computational burden imposed by centralized controller and degrades performance of robot by reducing sampling rate. Control and controller-adaptation laws based on observed performance of manipulator: no need to model dynamics of robot. Adaptive controllers cope with uncertainties and variations in robot and payload.

  14. The design of digital-adaptive controllers for VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Stengel, R. F.; Broussard, J. R.; Berry, P. W.

    1976-01-01

    Design procedures for VTOL automatic control systems have been developed and are presented. Using linear-optimal estimation and control techniques as a starting point, digital-adaptive control laws have been designed for the VALT Research Aircraft, a tandem-rotor helicopter which is equipped for fully automatic flight in terminal area operations. These control laws are designed to interface with velocity-command and attitude-command guidance logic, which could be used in short-haul VTOL operations. Developments reported here include new algorithms for designing non-zero-set-point digital regulators, design procedures for rate-limited systems, and algorithms for dynamic control trim setting.

  15. Pilot opinions of sampling effects in lateral-directional control

    NASA Technical Reports Server (NTRS)

    Stengel, R. F.; Miller, G. E.

    1982-01-01

    Flight experiments with a microprocessor control system were conducted to determine the effects of variations in sampling parameters on several pilots' opinions of lateral-directional flying qualities. Princeton's variable-response research aircraft (VRA), which is equipped with a microprocessor based digital flight control system (Micro-DFCS), was the test vehicle. Two U.S. Navy pilots evaluated the effects of sampling rate, quantization, and pure time delay during tracking, approach, and landing. Aircraft carrier approach tasks were conducted using a Navy approach mirror. Acquisition and tracking of fixed objects on the ground provided additional information related to the Navy misson. The longitudinal controls were implemented with analog electronics, while the lateral-directional pilot inputs (stick and rudder) were fed to the Micro-DFCS, which commanded the ailerons and rudder. The conceptual relationship between the evaluation pilot's lateral-directional inputs, the flight computer, and the aircraft are illustrated.

  16. Active flutter suppression using optical output feedback digital controllers

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A method for synthesizing digital active flutter suppression controllers using the concept of optimal output feedback is presented. A convergent algorithm is employed to determine constrained control law parameters that minimize an infinite time discrete quadratic performance index. Low order compensator dynamics are included in the control law and the compensator parameters are computed along with the output feedback gain as part of the optimization process. An input noise adjustment procedure is used to improve the stability margins of the digital active flutter controller. Sample rate variation, prefilter pole variation, control structure variation and gain scheduling are discussed. A digital control law which accommodates computation delay can stabilize the wing with reasonable rms performance and adequate stability margins.

  17. Digital adaptive control laws for the F-8

    NASA Technical Reports Server (NTRS)

    Hartmann, G. L.; Harvey, C. A.

    1976-01-01

    NASA is conducting a flight control research program in digital fly-by-wire technology using a modified F-8C aircraft. The first phase of this program used Apollo hardware to demonstrate the practicality of digital fly-by-wire in an actual test vehicle. For the second phase, conventional aircraft sensors and a large floating point digital computer are being utilized to test advanced control laws and redundancy concepts. As part of NASA's research in digital fly-by-wire technology, Honeywell developed digital adaptive flight control laws for flight test in the F-8C. Adaptation of the control laws was to be based on information sensed from conventional aircraft sensors excluding air data. The control laws were constrained to use only existing elevator, rudder, and ailerons as control effectors, each powered by existing actuators. Three adaptive control laws were successfully designed using maximum likelihood estimation, a Liapunov stable model tracker and a self-excited limit cycle concept. The maximum likelihood estimation design was selected as the most promising because of its capability to identify more than surface effectiveness parameters. The adaptive concepts, the control laws and comparisons of predicted performance are described.

  18. Prophylactic digitalization fails to control dysrhythmia in thoracic esophageal operations.

    PubMed

    Ritchie, A J; Tolan, M; Whiteside, M; McGuigan, J A; Gibbons, J R

    1993-01-01

    A prospective, controlled, randomized study of 80 patients undergoing esophageal operations was undertaken, in which one group of patients was given digoxin and the other was not. The incidence of cardiac dysrhythmia was compared in each group. Twenty-six patients underwent operation for benign disease. Equal numbers were digitalized or not and no dysrhythmias occurred. Fifty-four patients underwent operation for malignant disease. Of 26 in the group digitalized, 12 suffered dysrhythmia (46%). Of 28 not digitalized, 9 suffered dysrhythmia (32%). Overall, 39% of patients with malignant disease suffered a dysrhythmia compared with none with benign disease (p < 0.002 by chi 2).

  19. Integrated low power digital gyro control electronics

    NASA Technical Reports Server (NTRS)

    M'Closkey, Robert (Inventor); Challoner, A. Dorian (Inventor); Grayver, Eugene (Inventor); Hayworth, Ken J. (Inventor)

    2005-01-01

    Embodiments of the invention generally encompass a digital, application specific integrated circuit (ASIC) has been designed to perform excitation of a selected mode within a vibratory rate gyroscope, damping, or force-rebalance, of other modes within the sensor, and signal demodulation of the in-phase and quadrature components of the signal containing the angular rate information. The ASIC filters dedicated to each channel may be individually programmed to accommodate different rate sensor designs/technology or variations within the same class of sensors. The ASIC architecture employs a low-power design, making the ASIC, particularly suitable for use in power-sensitive applications.

  20. Direct Optimal Control of Duffing Dynamics

    NASA Technical Reports Server (NTRS)

    Oz, Hayrani; Ramsey, John K.

    2002-01-01

    The "direct control method" is a novel concept that is an attractive alternative and competitor to the differential-equation-based methods. The direct method is equally well applicable to nonlinear, linear, time-varying, and time-invariant systems. For all such systems, the method yields explicit closed-form control laws based on minimization of a quadratic control performance measure. We present an application of the direct method to the dynamics and optimal control of the Duffing system where the control performance measure is not restricted to a quadratic form and hence may include a quartic energy term. The results we present in this report also constitute further generalizations of our earlier work in "direct optimal control methodology." The approach is demonstrated for the optimal control of the Duffing equation with a softening nonlinear stiffness.

  1. [Image quality and detection performance of a direct digital radiography system].

    PubMed

    Ideguchi, Tadamitsu; Matsuda, Katsuhiko; Himuro, Kazuhiko; Kuwahara, Rie; Miyazaki, Hidetsune; Hazeyama, Hiroyuki; Kumazawa, Seiji; Kawaji, Yasuyuki; Yoshida, Akira; Matsumoto, Masao; Higashida, Yoshiharu

    2006-03-20

    The physical characteristics of a direct amorphous Selenium (a-Se) digital fluoroscopy and radiography system were investigated. Pre-sampled modulation transfer functions (MTF) were measured using a slit method. Noise power spectra were determined for different input exposures by fast Fourier transform of uniformly exposed samples. The MTFs of direct digital radiography systems showed significantly higher values than those of indirect digital radiography and screen-film systems. The direct digital radiography systems showed higher noise levels compared with those of indirect systems under roughly the same exposure conditions. Contrast-detail analysis was performed to compare detection by direct digital radiography systems with that of the screen-film (FUJI HG-M2/UR2) systems. The average contrast-detail curves of digital and film images were obtained from the results of observation. Image quality figures (IQF) were also calculated from the individual observer performance tests. The results indicated that digital contrast-detail curves and IQF are, on average, are equal those of the screen-film system.

  2. Velocity vector control system augmented with direct lift control

    NASA Technical Reports Server (NTRS)

    Tisdale, H. F., Sr.; Kelly, W. W. (Inventor)

    1981-01-01

    A pilot-controlled stability control system that employs direct lift control (spoiler control) with elevator control to control the flight path angle of an aircraft is described. A computer on the aircraft generates an elevator control signal and a spoiler control signal, using a pilot-controlled pitch control signal and pitch rate, vertical velocity, roll angle, groundspeed, engine pressure ratio and vertical acceleration signals which are generated on the aircraft. The direct lift control by the aircraft spoilers improves the response of the aircraft flight path angle and provides short term flight path stabilization against environmental disturbances.

  3. Fault tolerant programmable digital attitude control electronics study

    NASA Technical Reports Server (NTRS)

    Sorensen, A. A.

    1974-01-01

    The attitude control electronics mechanization study to develop a fault tolerant autonomous concept for a three axis system is reported. Programmable digital electronics are compared to general purpose digital computers. The requirements, constraints, and tradeoffs are discussed. It is concluded that: (1) general fault tolerance can be achieved relatively economically, (2) recovery times of less than one second can be obtained, (3) the number of faulty behavior patterns must be limited, and (4) adjoined processes are the best indicators of faulty operation.

  4. Developments in Digital Addressable Lighting Control

    NASA Astrophysics Data System (ADS)

    Moeck, Martin

    In DALI control, a small built-in chip acts as the de-central controller in the ballast. DALI complies with an open source protocol based on standard IEC60929. One small controller controls up to 64 ballasts. Today, manufacturers are adding more devices, such as sensors, blind motor controllers, and switches. Recently, web browser based remote control was developed for the DALI Lighting Laboratory at Pennsylvania State University. This paper reports on first experiences with advanced DALI features.

  5. Using a digital signal processor as a data stream controller for digital subtraction angiography

    SciTech Connect

    Meng, J.D.; Katz, J.E.

    1991-10-01

    High speed, flexibility, and good arithmetic abilities make digital signal processors (DSP) a good choice as input/output controllers for real time applications. The DSP can be made to pre-process data in real time to reduce data volume, to open early windows on what is being acquired and to implement local servo loops. We present an example of a DSP as an input/output controller for a digital subtraction angiographic imaging system. The DSP pre-processes the raw data, reducing data volume by a factor of two, and is potentially capable of producing real-time subtracted images for immediate display.

  6. Stabilization of a Digitally Controlled Active-Isolation System,

    DTIC Science & Technology

    1991-04-01

    Title: 5. FUNDING NUMBERS Stabilization of a Digitally Controlled Active-Isolation P.E. #61153N System Task #RRO11-08-42 W.U. #59-0582-0-0 6"AUTHOR(S...s. E. Forsythe, Code 5930 Assession #DNA580-030 M. D. McCollum, Code 5976 A. D. McCleary, Code 5977 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES...Maximum 200 words) Digital control techniques have proved beneficial in many control applications because they are flexible and lend themselves to adaptive

  7. Pixel resolution control in numerical reconstruction of digital holography.

    PubMed

    Yu, Lingfeng; Kim, Myung K

    2006-04-01

    A new method for resolution control in numerical reconstruction of digital holography is proposed. The wave field on a tilted or vertical plane can be reconstructed without being subject to the minimum object-to-hologram distance requirement, and the pixel resolution can be easily controlled by adjusting the position of a transitional plane. The proposed method solves the problem of pixel resolution control for small object-to-hologram distances and is especially useful for multicolor, multiwavelength digital holography and metrological applications. Experimental results are presented to verify the idea.

  8. MAS2-8 radar and digital control unit

    NASA Technical Reports Server (NTRS)

    Oberg, J. M.; Ulaby, F. T.

    1974-01-01

    The design of the MAS 2-8 (2 to 8 GHz microwave-active spectrometer), a ground-based sensor system, is presented. A major modification in 1974 to the MAS 2-8, that of a control subsystem to automate the data-taking operation, is the prime focus. The digital control unit automatically changes all system parameters except FM rate and records the return signal on paper tape. The overall system operation and a detailed discussion of the design and operation of the digital control unit are presented.

  9. 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.

  10. Digital robust control law synthesis using constrained optimization

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivekananda

    1989-01-01

    Development of digital robust control laws for active control of high performance flexible aircraft and large space structures is a research area of significant practical importance. The flexible system is typically modeled by a large order state space system of equations in order to accurately represent the dynamics. The active control law must satisy multiple conflicting design requirements and maintain certain stability margins, yet should be simple enough to be implementable on an onboard digital computer. Described here is an application of a generic digital control law synthesis procedure for such a system, using optimal control theory and constrained optimization technique. A linear quadratic Gaussian type cost function is minimized by updating the free parameters of the digital control law, while trying to satisfy a set of constraints on the design loads, responses and stability margins. Analytical expressions for the gradients of the cost function and the constraints with respect to the control law design variables are used to facilitate rapid numerical convergence. These gradients can be used for sensitivity study and may be integrated into a simultaneous structure and control optimization scheme.

  11. Wavelength-Division Multiplexing Of Avionic Digital Control Signals

    NASA Technical Reports Server (NTRS)

    Patterson, James D.; Palumbo, Daniel L.

    1993-01-01

    Proposed wavelength-division multiplexing optoelectronic system aboard aircraft transmits digital control signals from central flight-control computer via optical fibers to multiple distributed processors, actuators, and sensors. In comparison with serial TDM communication systems, this system offers potentially higher data throughput, greater tolerance to transient induced faults, and lower bit-error rates. Also immune to electromagnetic interference at suboptical frequencies.

  12. Direct write of microlens array using digital projection photopolymerization

    SciTech Connect

    Lu Yi; Chen Shaochen

    2008-01-28

    Microlens array is a key element in the field of information processing, optoelectronics, and integrated optics. Many existing fabrication processes remain expensive and complicated even though relatively low-cost replication processes have been developed. Here, we demonstrate the fabrication of microlens arrays through projection photopolymerization using a digital micromirror device (DMD) as a dynamic photomask. The DMD projects grayscale images, which are designed in a computer, onto a photocurable resin. The resin is then solidified with its thickness determined by a grayscale ultraviolet light and exposure time. Therefore, various geometries can be formed in a single-step, massively parallel fashion. We present microlens arrays made of acrylate-based polymer precursor. The physical and optical characteristics of the resulting lenses suggest that this fabrication technique is potentially suitable for applications in integrated optics.

  13. A Digital Self Excited Loop for Accelerating Cavity Field Control

    SciTech Connect

    Curt Hovater; Trent Allison; Jean Delayen; John Musson; Tomasz Plawski

    2007-06-22

    We have developed a digital process that emulates an analog oscillator and ultimately a self excited loop (SEL) for field control. The SEL, in its analog form, has been used for many years for accelerating cavity field control. In essence the SEL uses the cavity as a resonant circuit -- much like a resonant (tank) circuit is used to build an oscillator. An oscillating resonant circuit can be forced to oscillate at different, but close, frequencies to resonance by applying a phase shift in the feedback path. This allows the circuit to be phased-locked to a master reference, which is crucial for multiple cavity accelerators. For phase and amplitude control the SEL must be forced to the master reference frequency, and feedback provided for in both dimensions. The novelty of this design is in the way digital signal processing (DSP) is structured to emulate an analog system. While the digital signal processing elements are not new, to our knowledge this is the first time that the digital SEL concept has been designed and demonstrated. This paper reports on the progress of the design and implementation of the digital SEL for field control of superconducting accelerating cavities.

  14. Digital Command Augmentation for Lateral-Directional Aircraft Dynamics.

    DTIC Science & Technology

    1981-05-01

    desired for the short final segment of the approach. In summary, a Micro-DFCS, using modern control theory, was found to be a highly satisfactory...concepts to be put into practive are used. Type 0 controllers * with control rate restraint and equivalent Type 1 controllers for lateral...afforded through the use of sampled-data regulator theory. 1.4 ORGANIZATION OF THESIS This thesis is divided into five chapters and four appendices

  15. Digital control of high-intensity acoustic testing. [for spacecraft

    NASA Technical Reports Server (NTRS)

    Slusser, R. A.

    1975-01-01

    Three systems for the control of acoustic testing are compared: a hybrid digital/analog system, a digital vibration system, and the same digital vibration system modified by a software change. The hybrid system was constructed to control the 1/3-octaves from 50 to 1000 Hz. The vibration system was equipped with programs for sine and random vibration tests, shock analysis and synthesis, and signal analysis. For the modified vibration system, the random-vibration control program of the unmodified unit was changed so that acoustic tests could be performed. The performance of the three systems is compared by conducting probability-density and time-history analyses of the proposed test spectrum for the Mariner Jupiter/Saturn 1977 program. The results of the analyses show that the hybrid and modified vibration systems perform almost equally, but the modified vibration system is easier to use and produces better test documentation.

  16. 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.

  17. Simulink-aided Design and Implementation of Sensorless BLDC Motor Digital Control System

    NASA Astrophysics Data System (ADS)

    Zhilenkov, A. A.; Tsvetkov, Y. N.; Chistov, V. B.; Nyrkov, A. P.; Sokolov, S. S.

    2017-07-01

    The paper describes the process of creating of brushless direct current motor’s digital control system. The target motor has no speed sensor, so back-EMF method is used for commutation control. Authors show how to model the control system in MatLab/Simulink and to test it onboard STM32F4 microcontroller.This technology allows to create the most flexible system, which will control possible with a personal computer by communication lines. It is possible to examine the signals in the circuit of the actuator without any external measuring instruments - testers, oscilloscopes, etc. - and output waveforms and measured values of signals directly on the host PC.

  18. Direct Digital Synthesis Chirped Pulse Microwave Spectrometers for the Classroom and Research

    NASA Astrophysics Data System (ADS)

    Blake, Geoffrey; Carroll, Brandon; Finneran, Ian A.

    2015-06-01

    By combining the rapid development in direct digital synthesis circuitry and Field Programmable Gate Arrays (FPGAs) coupled to fast A/D samplers, it is possible to construct high performance chirped pulse microwave spectrometers suitable for gas-phase rotational spectroscopy experiments in undergraduate physical chemistry labs as well as graduate level research. The technology is highly tailorable, and sufficiently robust that extensive experimentation is feasible in the teaching environment. The time domain nature of the experiment has strong ties to concepts in Nuclear Magnetic Resonance (NMR) widely discussed in undergraduate curricula, and the software environment for the instrument control and spectral assignment can be integrated with ab initio quantum chemistry predictions of molecular structure and dynamics.

  19. Stress testing of digital flight-control system software

    NASA Technical Reports Server (NTRS)

    Rajan, N.; Defeo, P. V.; Saito, J.

    1983-01-01

    A technique for dynamically testing digital flight-control system software on a module-by-module basis is described. Each test module is repetitively executed faster than real-time with an exhaustive input sequence. Outputs of the test module are compared with outputs generated by an alternate, simpler implementation for the same input data. Discrepancies between the two sets of output indicate the possible presence of a software error. The results of an implementation of this technique in the Digital Flight-Control System Software Verification Laboratory are discussed.

  20. Evaluation of a high response electrohydraulic digital control valve

    NASA Technical Reports Server (NTRS)

    Anderson, R. L.

    1973-01-01

    The application is described of a digital control valve on an electrohydraulic servo actuator. The digital control problem is discussed in general as well as the design and evaluation of a breadboard actuator. The evaluation revealed a number of problems associated with matching the valve to a hydraulic load. The problems were related to lost motion resulting from bulk modulus and leakage. These problems were effectively minimized in the breadboard actuator by maintaining a 1000 psi back pressure on the valve circuit and thereby improving the effective bulk modulus.

  1. Direct Measurement of Mammographic X-Ray Spectra with a Digital CdTe Detection System

    PubMed Central

    Abbene, Leonardo; Gerardi, Gaetano; Principato, Fabio; Sordo, Stefano Del; Raso, Giuseppe

    2012-01-01

    In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate X-ray spectroscopy in mammography (1–30 keV). The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography. PMID:22969406

  2. Real Time Digital Control of a Magnetostrictive Actuator

    NASA Technical Reports Server (NTRS)

    Zrostlik, Rick L.; Hall, David L.; Flatau, Alison B.

    1996-01-01

    The use of the magnetostrictive material Terfenol-D as a motion source in active vibration control (AVC) systems are being studied. Currently it is of limited use due to the nonlinear nature of the strain versus magnetization curve and the magnetic hysteresis in the Terfenol-D. One manifestation of these nonlinearities is waveform distortion in the output velocity of the transducer. For Terfenol-D to be used in ever greater numbers of AVC systems, these nonlinearities must be addressed. In this study the nonlinearities are treated as disturbances to a linear system. The acceleration output is used in simple analog and digital feedback control schemes to improve linearity of the transducer. In addition, the use of a Terfenol-D actuator in an AVC system is verified. Both analog and digital controllers are implemented and results compared. A cantilever beam system is considered for AVC applications. The second thrust of this presentation is the reduction of harmonic distortions. Two conclusions can be reached from this work. One, the linearization of Terfenol-D transducers is possible with the use of feedback controllers, both digital and analog. Second, Terfenol-D is a viable motion source in active vibration control systems utilizing either analog or digital controllers.

  3. Digital control of diode laser for atmospheric spectroscopy

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Rutledge, C. W. (Inventor)

    1985-01-01

    A system is described for remote absorption spectroscopy of trace species using a diode laser tunable over a useful spectral region of 50 to 200 cm(-1) by control of diode laser temperature over range from 15 K to 100 K, and tunable over a smaller region of typically 0.1 to 10 cm(-1) by control of the diode laser current over a range from 0 to 2 amps. Diode laser temperature and current set points are transmitted to the instrument in digital form and stored in memory for retrieval under control of a microprocessor during measurements. The laser diode current is determined by a digital to analog converter through a field effect transistor for a high degree of ambient temperature stability, while the laser diode temperature is determined by set points entered into a digital to analog converter under control of the microprocessor. Temperature of the laser diode is sensed by a sensor diode to provide negative feedback to the temperature control circuit that responds to the temperature control digital to analog converter.

  4. Real Time Digital Control of a Magnetostrictive Actuator

    NASA Technical Reports Server (NTRS)

    Zrostlik, Rick L.; Hall, David L.; Flatau, Alison B.

    1996-01-01

    The use of the magnetostrictive material Terfenol-D as a motion source in active vibration control (AVC) systems are being studied. Currently it is of limited use due to the nonlinear nature of the strain versus magnetization curve and the magnetic hysteresis in the Terfenol-D. One manifestation of these nonlinearities is waveform distortion in the output velocity of the transducer. For Terfenol-D to be used in ever greater numbers of AVC systems, these nonlinearities must be addressed. In this study the nonlinearities are treated as disturbances to a linear system. The acceleration output is used in simple analog and digital feedback control schemes to improve linearity of the transducer. In addition, the use of a Terfenol-D actuator in an AVC system is verified. Both analog and digital controllers are implemented and results compared. A cantilever beam system is considered for AVC applications. The second thrust of this presentation is the reduction of harmonic distortions. Two conclusions can be reached from this work. One, the linearization of Terfenol-D transducers is possible with the use of feedback controllers, both digital and analog. Second, Terfenol-D is a viable motion source in active vibration control systems utilizing either analog or digital controllers.

  5. Digital regulation of a phase controlled power converter

    SciTech Connect

    Schultheiss, C.; Haque, T.

    1995-12-01

    The Relativistic Heavy Ion Collider, now in construction at Brookhaven National Laboratory, will use phase controlled power converters for the main dipole and quadrupole magnet strings. The rectifiers in these power supplies will be controlled by a digital regulator based on the TI 320C30 Digital Signal Processor (DSP). The DSP implements the current loop, the voltage loop, and a system to actively reduce the sub-harmonic ripple components. Digital firing circuits consisting of a phase locked lop and counters are used to fire the SCRs. Corrections for the sub-harmonic reduction are calculated by the DSP and stored in registers in the firing circuit. These corrections are added in hardware, to the over-all firing count provided by the DSP. the resultant count is compared to a reference counter to fire the SCRs. This combination of a digital control system and the digital firing circuits allows the correction of the sub-harmonics in a real-time sense. A prototype of the regulator has been constructed, and the preliminary testing indicates a sub-harmonic reduction of 60 dB.

  6. Digital Control and Identification of Distributed Systems.

    DTIC Science & Technology

    1990-08-14

    for example, problems in which a Schrodinger equation is coupled with a diffusion equation . In this paper, we are particularly interested in second...control of systems represented by partial differential equations , and adaptive control and tracking problems for flexible structures and manipulators...and functional differential equations . The primary class of applications is large flexible space structures. Papers dealing mainly with approximation

  7. HVDC control system based on parallel digital signal processors

    SciTech Connect

    Maharsi, Y.; Do, V.Q.; Sood, V.K.; Casoria, S.; Belanger, J.

    1995-05-01

    A numerical HVDC control system operating in real time has been developed for a simulator to be used for operator training. The control system, implemented with digital signal processors (DSPs), consists of typical HVDC control functions such as the synchronizing unit, the regulation unit, the protection unit, the firing unit, the tap changer and the reactive power regulation unit. Results from the steady-state and the transient performance validation tests carried out on the IREQ power system simulator are provided.

  8. The design of multirate digital control systems

    NASA Technical Reports Server (NTRS)

    Berg, M. C.

    1986-01-01

    The successive loop closures synthesis method is the only method for multirate (MR) synthesis in common use. A new method for MR synthesis is introduced which requires a gradient-search solution to a constrained optimization problem. Some advantages of this method are that the control laws for all control loops are synthesized simultaneously, taking full advantage of all cross-coupling effects, and that simple, low-order compensator structures are easily accomodated. The algorithm and associated computer program for solving the constrained optimization problem are described. The successive loop closures , optimal control, and constrained optimization synthesis methods are applied to two example design problems. A series of compensator pairs are synthesized for each example problem. The succesive loop closure, optimal control, and constrained optimization synthesis methods are compared, in the context of the two design problems.

  9. Direct adaptive control of a PUMA 560 industrial robot

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Lee, Thomas; Delpech, Michel

    1989-01-01

    The implementation and experimental validation of a new direct adaptive control scheme on a PUMA 560 industrial robot is described. The testbed facility consists of a Unimation PUMA 560 six-jointed robot and controller, and a DEC MicroVAX II computer which hosts the Robot Control C Library software. The control algorithm is implemented on the MicroVAX which acts as a digital controller for the PUMA robot, and the Unimation controller is effectively bypassed and used merely as an I/O device to interface the MicroVAX to the joint motors. The control algorithm for each robot joint consists of an auxiliary signal generated by a constant-gain Proportional plus Integral plus Derivative (PID) controller, and an adaptive position-velocity (PD) feedback controller with adjustable gains. The adaptive independent joint controllers compensate for the inter-joint couplings and achieve accurate trajectory tracking without the need for the complex dynamic model and parameter values of the robot. Extensive experimental results on PUMA joint control are presented to confirm the feasibility of the proposed scheme, in spite of strong interactions between joint motions. Experimental results validate the capabilities of the proposed control scheme. The control scheme is extremely simple and computationally very fast for concurrent processing with high sampling rates.

  10. 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.

  11. Conversion of a servomanipulator from analog to digital control

    SciTech Connect

    Killough, S.M.; Martin, H.L.; Hamel, W.R.

    1986-01-01

    Oak Ridge National Laboratory (ORNL) has developed expertise in computer control of force-reflecting master/slave servomanipulators as a result of research for the Consolidated Fuel Reprocessing Program. These computer control capabilities have been applied to a commercially available servomanipulator, the TeleOperator Systems SM-229. All of the servo drive and control circuitry has been replaced with commercially available digital controls and amplifiers, and a customer software - package has been developed at ORNL. This conversion to digital computer control resulted in significant improvements in force-reflection characteristics, ease of operation, diagnostic capabilities, indexing features, and potential increased reliability. The system will be used at the Tokamak Fusion Test Reactor at the Princeton Plasma Physics Laboratory (PPPL) for maintenance demonstrations.

  12. Digitally Controlled High Availability Power Supply

    SciTech Connect

    MacNair, David; /SLAC

    2008-09-25

    This paper reports the design and test results on novel topology, high-efficiency, and low operating temperature, 1,320-watt power modules for high availability power supplies. The modules permit parallel operation for N+1 redundancy with hot swap capability. An embedded DSP provides intelligent start-up and shutdown, output regulation, general control and fault detection. PWM modules in the DSP drive the FET switches at 20 to 100 kHz. The DSP also ensures current sharing between modules, synchronized switching, and soft start up for hot swapping. The module voltage and current have dedicated ADCs (>200 kS/sec) to provide pulse-by-pulse output control. A Dual CAN bus interface provides for low cost redundant control paths. Over-rated module components provide high reliability and high efficiency at full load. Low on-resistance FETs replace conventional diodes in the buck regulator. Saturable inductors limit the FET reverse diode current during switching. The modules operate in a two-quadrant mode, allowing bipolar output from complimentary module groups. Controllable, low resistance FETs at the input and output provide fault isolation and allow module hot swapping.

  13. 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).

  14. Digital Controller For Laser-Beam-Steering Subsystem: Part 2

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Voisinet, Leeann

    1995-01-01

    A report presents additional information about laser-beam-steering apparatus described in "Digital Controller for Laser-Beam-Steering Subsystem" (NPO-19193) and "More About Beam-Steering Subsystem for Laser Communication" (NPO-19381). Reiterates basic principles of operation of beam-steering subsystem, with emphasis on modes of operation, basic design concepts, and initial experiments on partial prototype of apparatus.

  15. 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.

  16. Digital Plasma Control System for Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Ferrara, M.; Wolfe, S.; Stillerman, J.; Fredian, T.; Hutchinson, I.

    2004-11-01

    A digital plasma control system (DPCS) has been designed to replace the present C-Mod system, which is based on hybrid analog-digital computer. The initial implementation of DPCS comprises two 64 channel, 16 bit, low-latency cPCI digitizers, each with 16 analog outputs, controlled by a rack-mounted single-processor Linux server, which also serves as the compute engine. A prototype system employing three older 32 channel digitizers was tested during the 2003-04 campaign. The hybrid's linear PID feedback system was emulated by IDL code executing a synchronous loop, using the same target waveforms and control parameters. Reliable real-time operation was accomplished under a standard Linux OS (RH9) by locking memory and disabling interrupts during the plasma pulse. The DPCS-computed outputs agreed to within a few percent with those produced by the hybrid system, except for discrepancies due to offsets and non-ideal behavior of the hybrid circuitry. The system operated reliably, with no sample loss, at more than twice the 10kHz design specification, providing extra time for implementing more advanced control algorithms. The code is fault-tolerant and produces consistent output waveforms even with 10% sample loss.

  17. Digital Controller For Laser-Beam-Steering Subsystem: Part 2

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Voisinet, Leeann

    1995-01-01

    A report presents additional information about laser-beam-steering apparatus described in "Digital Controller for Laser-Beam-Steering Subsystem" (NPO-19193) and "More About Beam-Steering Subsystem for Laser Communication" (NPO-19381). Reiterates basic principles of operation of beam-steering subsystem, with emphasis on modes of operation, basic design concepts, and initial experiments on partial prototype of apparatus.

  18. 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.

  19. Converting the Active Digital Controller for Use in Two Tests

    NASA Technical Reports Server (NTRS)

    Wright, Robert G.

    1995-01-01

    The Active Digital Controller is a system used to control the various functions of wind tunnel models. It has the capability of digitizing and saving of up to sixty-four channels of analog data. It can output up to 16 channels of analog command signals. In addition to its use as a general controller, it can run up to two distinct control laws. All of this is done at a regulated speed of two hundred hertz. The Active Digital Controller (ADC) was modified for use in the Actively Controlled Response of Buffet Affected Tails (ACROBAT) tests and for side-wall pressure data acquisition. The changes included general maintenance and updating of the controller as well as setting up special modes of operation. The ACROBAT tests required that two sets of output signals be available. The pressure data acquisition needed a sampling rate of four hundred hertz, twice the standard ADC rate. These modifications were carried out and the ADC was used during the ACROBAT wind tunnel entry.

  20. Direct adaptive impedance control of manipulators

    NASA Technical Reports Server (NTRS)

    Colbaugh, R.; Seraji, H.; Glass, K.

    1991-01-01

    An adaptive scheme for controlling the end-effector impedance of robot manipulators is presented. The proposed control system consists of three subsystems: a simple filter which characterizes the desired dynamic relationship between the end-effector position error and the end-effector/environment contact force, an adaptive controller which produces the Cartesian-space control input required to provide this desired dynamic relationship, and an algorithm for mapping the Cartesian-space control input to a physically realizable joint-space control torque. The controller does not require knowledge of either the structure or the parameter values of the robot dynamics, and it is implemented without calculation of the robot inverse kinematic transformation. As a result, the scheme represents a very general and computationally efficient approach to controlling the impedance of both nonredundant and redundant manipulators. Furthermore, the method can be applied directly to trajectory tracking in free-space motion by removing the impedance filter.

  1. Digital electronic engine control fault detection and accommodation flight evaluation

    NASA Technical Reports Server (NTRS)

    Baer-Ruedhart, J. L.

    1984-01-01

    The capabilities and performance of various fault detection and accommodation (FDA) schemes in existing and projected engine control systems were investigated. Flight tests of the digital electronic engine control (DEEC) in an F-15 aircraft show discrepancies between flight results and predictions based on simulation and altitude testing. The FDA methodology and logic in the DEEC system, and the results of the flight failures which occurred to date are described.

  2. Modelling and designing digital control systems with averaged measurements

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.; Beale, Guy O.

    1988-01-01

    An account is given of the control systems engineering methods applicable to the design of digital feedback controllers for aerospace deterministic systems in which the output, rather than being an instantaneous measure of the system at the sampling instants, instead represents an average measure of the system over the time interval between samples. The averaging effect can be included during the modeling of the plant, thereby obviating the iteration of design/simulation phases.

  3. Digitally Controlled High Availability Power Supply

    SciTech Connect

    MacNair, David; /SLAC

    2009-05-07

    This paper will report on the test results of a prototype 1320 watt power module for a high availability power supply. The module will allow parallel operation for N+1 redundancy with hot swap capability. The two quadrant output of each module allows pairs of modules to provide a 4 quadrant (bipolar) operation. Each module employs a novel 4 FET buck regulator arranged in a bridge configuration. Each side of the bridge alternately conducts through a small saturable ferrite that limits the reverse current in the FET body diode during turn off. This allows hard switching of the FETs with low switching losses. The module is designed with over-rated components to provide high reliability and better then 97% efficiency at full load. The modules use a Microchip DSP for control, monitoring, and fault detection. The switching FETS are driven by PWM modules in the DSP at 60 KHz. A Dual CAN bus interface provides for low cost redundant control paths. The DSP will also provide current sharing between modules, synchronized switching, and soft start up for hot swapping. The input and output of each module have low resistance FETs to allow hot swapping and isolation of faulted units.

  4. Calibrating automatic exposure control devices for digital radiography.

    PubMed

    Doyle, P; Martin, C J

    2006-11-07

    The energy responses of digital radiography detectors differ from those of screen-film systems. To provide a consistent level of image quality at different tube potentials automatic exposure control (AEC) devices must be calibrated to suit the energy response of the image receptor with which they are intended for use. AEC calibration for digital radiography systems requires an alternative parameter to optical density, ideally one related to the quality of a digital image. Energy responses of computed radiography (CR) and indirect digital radiography (IDR) image receptors have been calculated, and compared with those for screen-film systems. Practical assessments of the relative sensitivities of a CR detector made using the detector dose indicator (DDI), pixel value and signal-to-noise ratio showed similar variations with tube potential. The DDI has been used to determine the correct kV compensation curve required to calibrate the AECs for the loss in detector sensitivity with tube potential. AECs are set up relative to a predetermined air kerma incident on the detector at 80 kV for CR and IDR systems using this curve and the method used is described. Factors influencing the calibration of AECs for digital radiography including techniques, types of phantom and contributions from scatter are reviewed, and practical methods recommended for use.

  5. Digital Command Augmentation for Lateral-Directional Aircraft Dynamics.

    DTIC Science & Technology

    1981-05-01

    process. * The pilot is not aware of the sampled nature of the control system at a sampling rate of 10 sps. No performance degradation is noted in the...solution, Ax(t). It is because the above assumptions are not realis- tic situations , that is, disturbances are present and F and G are im- precisely...A_’* -SIAL* + St 2 Ad (2.3-35) 6u*= -8! 1 A"* + S2A2 1 (2.3-36) and t *= Ap*(T) dT (2.3-37) 0 which can be approximated in the discrete-time case as

  6. Digital active control law synthesis for aeroservoelastic systems

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivekananda

    1988-01-01

    This paper presents a formulation for synthesis of digital active control laws for aeroservoelastic systems, which are typically modeled by large order equations in order to accurately represent the rigid and flexible body modes, unsteady aerodynamic forces, actuator dynamics, and gust spectra. The control law is expected to satisfy multiple design requirements on the dynamic loads, responses, actuator deflection and rate limitations, as well as maintain certain stability margins, yet should be simple enough to be implemented by an onboard digital microprocessor. The synthesis procedure minimizes a linear quadratic Gaussian type cost function, by updating selected free parameters of the control law, while satisfying a set of inequality constraints on the design loads, responses and stability margins. A stable classical control law or an estimator based full or reduced order control law can be used as an initial design starting point. The gradients of the cost function and the constraints, with respect to the digital control law design variables are derived analytically, to facilitate rapid convergence. Selected design responses can be treated as constraints instead of lumping them into the cost function, in order to satisfy individual root-mean-square load and response limitations. Constraints are also imposed on the minimum singular value requirements for stability robustness improvement.

  7. Digital frequency control of satellite frequency standards. [Defense Navigation Satellites

    NASA Technical Reports Server (NTRS)

    Nichols, S. A.

    1973-01-01

    In the Frequency and Time Standard Development Program of the TIMATION System, a new miniaturized rubidium vapor frequency standard has been tested and analyzed for possible use on the TIMATION 3A launch, as part of the Defense Navigation Satellite Development Program. The design and construction of a digital frequency control was required to remotely control this rubidium vapor frequency standard as well as the quartz oscillator in current use. This control must be capable of accepting commands from a satellite telemetry system, verify that the correct commands have been sent and control the frequency to the requirements of the system. Several modifications must be performed to the rubidium vapor frequency standard to allow it to be compatible with the digital frequency control. These include the addition of a varactor to voltage tune the coarse range of the flywheel oscillator, and a modification to supply the C field current externally. The digital frequency control for the rubidium vapor frequency standard has been successfully tested in prototype form.

  8. Digital tracking and control of retinal images

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Jerath, Maya R.; Rylander, Henry G., III; Welch, Ashley J.

    1993-06-01

    Laser induced retinal lesions are used to treat a variety of eye diseases such as diabetic retinopathy and retinal detachment. An instrumentation system has been developed to track a specific lesion coordinate on the retinal surface and provide corrective signals to maintain laser position on the coordinate. High resolution retinal images are acquired via a CCD camera coupled to a fundus camera and video frame grabber. Optical filtering and histogram modification are used to enhance the retinal vessel network against the lighter retinal background. Six distinct retinal landmarks are tracked on the high contrast image obtained from the frame grabber using two-dimensional blood vessel templates. The frame grabber is hosted on a 486 PC. The PC performs correction signal calculations using an exhaustive search on selected image portions. An X and Y laser correction signal is derived from the landmark tracking information and provided to a pair of galvanometer steered mirrors via a data acquisition and control subsystem. This subsystem also responds to patient inputs and the system monitoring lesion growth. This paper begins with an overview of the robotic laser system design followed by implementation and testing of a development system for proof of concept. The paper concludes with specifications for a real time system.

  9. Optical design of a digitally spectrum-controllable light source

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Ma, Suodong; Shen, Weimin

    2014-11-01

    Spectrum-controllable light sources are able to generate desired spectrums as specific requirements, which have attracted huge interesting in many fields, e.g. life science, machine vision, defense-related science and technology. A controllable light source in the range from 0.38 to 0.78 μm, which is based on a Digital Micromirror Device (DMD) and an Offner dispersion configuration with a convex grating, is proposed in this paper. Due to its fast speed, high fidelity and simplicity with all spherical elements, the Offner relay is chosen as the dispersion structure compared with other existing spectroscopic configurations. The DMD located on the spectral image plane of the dispersion configuration is used to choose spectral channels according to the desired spectral radiance distribution through modulating micromirrors. The optical system of the proposed digitally spectrum-controllable light source is designed and further simulated by Zemax.

  10. Sens-A-Ray. A new system for direct digital intraoral radiography.

    PubMed

    Nelvig, P; Wing, K; Welander, U

    1992-12-01

    A new system for direct digital intraoral radiography, Sens-A-Ray, is presented. This system is based on a detector with a charge-coupled device that was designed especially for direct exposure to x-ray radiation. The system also includes interface electronics and an IBM AT-compatible personal computer with a digital I/O with frame memory, a super VGA graphics board, a high-resolution monitor, and software for the exposure, capture, storage, and enhancement of images. An external optical mass storage device is used for permanent storage of images in digital format. A video printer may be used to create hard copies. The system produces radiographic images at a significantly lower exposure than required for E-speed intraoral film. Applications of the system are exemplified, and its basic properties are discussed.

  11. Covert digital manipulation of vocal emotion alter speakers' emotional states in a congruent direction.

    PubMed

    Aucouturier, Jean-Julien; Johansson, Petter; Hall, Lars; Segnini, Rodrigo; Mercadié, Lolita; Watanabe, Katsumi

    2016-01-26

    Research has shown that people often exert control over their emotions. By modulating expressions, reappraising feelings, and redirecting attention, they can regulate their emotional experience. These findings have contributed to a blurring of the traditional boundaries between cognitive and emotional processes, and it has been suggested that emotional signals are produced in a goal-directed way and monitored for errors like other intentional actions. However, this interesting possibility has never been experimentally tested. To this end, we created a digital audio platform to covertly modify the emotional tone of participants' voices while they talked in the direction of happiness, sadness, or fear. The result showed that the audio transformations were being perceived as natural examples of the intended emotions, but the great majority of the participants, nevertheless, remained unaware that their own voices were being manipulated. This finding indicates that people are not continuously monitoring their own voice to make sure that it meets a predetermined emotional target. Instead, as a consequence of listening to their altered voices, the emotional state of the participants changed in congruence with the emotion portrayed, which was measured by both self-report and skin conductance level. This change is the first evidence, to our knowledge, of peripheral feedback effects on emotional experience in the auditory domain. As such, our result reinforces the wider framework of self-perception theory: that we often use the same inferential strategies to understand ourselves as those that we use to understand others.

  12. Covert digital manipulation of vocal emotion alter speakers’ emotional states in a congruent direction

    PubMed Central

    Johansson, Petter; Hall, Lars; Segnini, Rodrigo; Mercadié, Lolita; Watanabe, Katsumi

    2016-01-01

    Research has shown that people often exert control over their emotions. By modulating expressions, reappraising feelings, and redirecting attention, they can regulate their emotional experience. These findings have contributed to a blurring of the traditional boundaries between cognitive and emotional processes, and it has been suggested that emotional signals are produced in a goal-directed way and monitored for errors like other intentional actions. However, this interesting possibility has never been experimentally tested. To this end, we created a digital audio platform to covertly modify the emotional tone of participants’ voices while they talked in the direction of happiness, sadness, or fear. The result showed that the audio transformations were being perceived as natural examples of the intended emotions, but the great majority of the participants, nevertheless, remained unaware that their own voices were being manipulated. This finding indicates that people are not continuously monitoring their own voice to make sure that it meets a predetermined emotional target. Instead, as a consequence of listening to their altered voices, the emotional state of the participants changed in congruence with the emotion portrayed, which was measured by both self-report and skin conductance level. This change is the first evidence, to our knowledge, of peripheral feedback effects on emotional experience in the auditory domain. As such, our result reinforces the wider framework of self-perception theory: that we often use the same inferential strategies to understand ourselves as those that we use to understand others. PMID:26755584

  13. Non-uniform sampling strategies for digital control

    NASA Astrophysics Data System (ADS)

    Khan, Samir; Goodall, Roger M.; Dixon, Roger

    2013-12-01

    Most conventional control algorithms cause numerical problems where data is collected at sampling rates that are substantially higher than the dynamics of the equivalent continuous-time operation that is being implemented. This is of relevant interest in applications of digital control, in which high sample rates are routinely dictated by the system stability requirements rather than the signal processing needs. Digital control systems exhibit bandwidth limitations enforced by their closed-loop frequency requirements that demand very high sample rates. Considerable recent progress in reducing sample frequency requirements has been made through the use of non-uniform sampling schemes, so called alias-free signal processing. The approach prompts the simplification of complex systems and consequently enhances the numerical conditioning of the implementation algorithms that otherwise would require very high uniform sample rates. However, the control communities have not yet investigated the use of intentional non-uniform sampling. The purpose of this article is to address some algorithmic issues when using such regimes for digital control.

  14. 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.

  15. Direct method for video-based navigation using a digital terrain map.

    PubMed

    Lerner, Ronen; Rivlin, Ehud

    2011-02-01

    A novel vision-based navigation algorithm is proposed. The gray levels of two images, together with a Digital Terrain Map (DTM), are directly utilized to define constraints on the navigation parameters. The feasibility of the algorithm is examined both under a simulated environment and using real flight data.

  16. Fast digital zooming system using directionally adaptive image interpolation and restoration.

    PubMed

    Kang, Wonseok; Jeon, Jaehwan; Yu, Soohwan; Paik, Joonki

    2014-01-01

    This paper presents a fast digital zooming system for mobile consumer cameras using directionally adaptive image interpolation and restoration methods. The proposed interpolation algorithm performs edge refinement along the initially estimated edge orientation using directionally steerable filters. Either the directionally weighted linear or adaptive cubic-spline interpolation filter is then selectively used according to the refined edge orientation for removing jagged artifacts in the slanted edge region. A novel image restoration algorithm is also presented for removing blurring artifacts caused by the linear or cubic-spline interpolation using the directionally adaptive truncated constrained least squares (TCLS) filter. Both proposed steerable filter-based interpolation and the TCLS-based restoration filters have a finite impulse response (FIR) structure for real time processing in an image signal processing (ISP) chain. Experimental results show that the proposed digital zooming system provides high-quality magnified images with FIR filter-based fast computational structure.

  17. Wet runways. [aircraft landing and directional control

    NASA Technical Reports Server (NTRS)

    Horne, W. B.

    1975-01-01

    Aircraft stopping and directional control performance on wet runways is discussed. The major elements affecting tire/ground traction developed by jet transport aircraft are identified and described in terms of atmospheric, pavement, tire, aircraft system and pilot performance factors or parameters. Research results are summarized, and means for improving or restoring tire traction/aircraft performance on wet runways are discussed.

  18. The Role of Controlled Vocabularies in Digital Archiving

    NASA Astrophysics Data System (ADS)

    Miller, S.; Clark, P. D.; Neiswender, C.

    2006-12-01

    Over the years, and across projects and disciplines, there is an unfortunate tendency for descriptive terminology to wander. Some of the variation is due to evolution in sensor technology, but some may be due to odd abbreviations, typographical errors on rolling decks, institutional practices, or a momentary inspiration to use a new term. As a consequence, we now face challenges in searching digital collections, and in designing re-usable tools that can be applied to multiple institutions. Practical experience with the SIOExplorer Digital Library of 700 SIO cruises has allowed us to develop techniques to assess variations in metadata values across collections of more than 100,000 digital objects, including datasets, documents and images spanning more than 50 years. The assessment helps to guide the development of controlled vocabularies, which in turn can be used to enable automatic detection of metadata errors, and in some cases automatic correction. Controlled vocabularies are playing an essential role in extending the technology to the collections of the Woods Hole Oceanographic Institution, including cruises, Alvin dives and ROV operations. Examples include the names of chief scientists, port names, operational areas, science themes, image types, sample types, data types, and processing steps. Controlled vocabularies underlie an emerging set of tools that support web user interfaces, large-scale automatic harvesting of metadata and data, project status assessment, workflow management and overall quality control. They are a key resource for user upload code in the IODP Site Survey Data Bank, prompting and enforcing appropriate metadata values for ocean drilling proposal support data. Compared to previous generations of hard-wired code, the access to controlled vocabularies allows a project to evolve with flexibility, and the code to be ported from one project to another. These efforts are supported by a Digital Archiving award from the Library of Congress and

  19. Comparison of Two Methods of Obtaining Digital Orthodontic Models: Direct vs. Indirect

    DTIC Science & Technology

    2013-05-17

    either a traditional impression or a digital impression taken directly from the dentition . Various manufacturers developed model scanning devices...main advantage to direct intraoral scanning of the dentition is the obvious elimination of potential error that is inherent in creating an impression...of the maxillary and mandibular dentition and associated bite registration. We attempted to reduce the amount of potential error in several ways

  20. Quantum secure direct communication of digital and analog signals using continuum coherent states

    NASA Astrophysics Data System (ADS)

    Guerra, Antônio Geovan de Araújo Holanda; Rios, Francisco Franklin Sousa; Ramos, Rubens Viana

    2016-11-01

    In this work, we present optical schemes for secure direct quantum communication of digital and analog signals using continuum coherent states and frequency-dependent phase modulation. The main advantages of the proposed schemes are that they do not use entangled states and they can be implemented with today technology. The theory of quantum interference of continuum coherent state is described, and the optical setups for secure direct communication are presented and their securities are discussed.

  1. Effect of image compression of direct digital lateral cephalograms on the identification of cephalometric points

    PubMed Central

    Saghaie, Sima; Ghaffari, Roshanak

    2014-01-01

    Background: With increase of digital imaging, the need for storage space and transmission speed also increases. Compressed images need less storage space and decrease the transmission time. However, compression could compromise image quality. The aim of this study was to evaluate the influence of image compression on the identification of cephalometric points on direct digital lateral cephalogram images, compared with the digital imaging and communications in medicine (DICOM) format. Materials and Methods: In this analytical-descriptive study, 19 direct digital lateral cephalograms saved in DICOM format were used. They were converted to joint photographic experts group (JPEG) 2000 format with quality factors 85, 75, and 60 adding up to 76 images (DICOM, JPEG 85, 75, and 60). The images were randomized and eight cephalometric points were identified on each image by a professional, using the x-y coordinate system. Analysis of variance (ANOVA) was applied to investigate if there was a statistically significant difference in the location of cephalometric points between each group of images. All tests were applied at a significance level of 5%. Results: The results did not demonstrate any statistically significant difference in the identification of the eight cephalometric points between the DICOM images and the JPEG2000 quality factors 85, 75, and 60. Conclusion: JPEG2000 images of lateral cephalograms with quality factors 85, 75, and 60 did not demonstrate any alterations in the identification of cephalometric points compared with the DICOM format. JPEG2000 is a reliable file format for the compression of digital lateral cephalograms. PMID:24688556

  2. Faster processing of multiple spatially-heterodyned direct to digital holograms

    DOEpatents

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN

    2008-09-09

    Systems and methods are described for faster processing of multiple spatially-heterodyned direct to digital holograms. A method includes of obtaining multiple spatially-heterodyned holograms, includes: digitally recording a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; digitally recording a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first object beam; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam; and applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result, wherein digitally recording the first spatially-heterodyned hologram is completed before digitally recording the second spatially-heterodyned hologram and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  3. Faster processing of multiple spatially-heterodyned direct to digital holograms

    DOEpatents

    Hanson, Gregory R.; Bingham, Philip R.

    2006-10-03

    Systems and methods are described for faster processing of multiple spatially-heterodyned direct to digital holograms. A method includes of obtaining multiple spatially-heterodyned holograms, includes: digitally recording a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; digitally recording a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first, object beam; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam; and applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result, wherein digitally recording the first spatially-heterodyned hologram is completed before digitally recording the second spatially-heterodyned hologram and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  4. Study for incorporating time-synchronized approach control into the CH-47/VALT digital navigation system

    NASA Technical Reports Server (NTRS)

    Mcconnell, W. J., Jr.

    1979-01-01

    Techniques for obtaining time synchronized (4D) approach control in the VALT research helicopter is described. Various 4D concepts and their compatibility with the existing VALT digital computer navigation and guidance system hardware and software are examined. Modifications to various techniques were investigated in order to take advantage of the unique operating characteristics of the helicopter in the terminal area. A 4D system is proposed, combining the direct to maneuver with the existing VALT curved path generation capability.

  5. 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.

  6. System for controllable magnetic measurement with direct field determination

    NASA Astrophysics Data System (ADS)

    Stupakov, O.

    2012-02-01

    This work describes a specially designed setup for magnetic hysteresis and Barkhausen noise measurements. The setup combines two main elements: an improved fast algorithm to control the waveform of magnetic induction and simultaneous direct determination of the magnetic field. The digital feedback algorithm uses only the previous measurement cycle to correct the magnetization voltage without any additional correlation parameter; it usually converges after several tens of cycles. The magnetic field is measured at the sample surface using a vertically mounted array of sensitive Hall sensors. Linear extrapolation of the tangential field profile to the sample surface determines the true waveform of the magnetic field. This unique combination of physically based control for both parameters of the magnetization process provides stable and reliable results, which are independent of a specified experimental configuration. This is illustrated for the industrially attractive measurements of non-oriented electrical steels with a 50 Hz sinusoidal induction waveform.

  7. Digital control of magnetic bearings in a cryogenic cooler

    NASA Technical Reports Server (NTRS)

    Feeley, J.; Law, A.; Lind, F.

    1990-01-01

    This paper describes the design of a digital control system for control of magnetic bearings used in a spaceborne cryogenic cooler. The cooler was developed by Philips Laboratories for the NASA Goddard Space Flight Center. Six magnetic bearing assemblies are used to levitate the piston, displacer, and counter-balance of the cooler. The piston and displacer are driven by linear motors in accordance with Stirling cycle thermodynamic principles to produce the desired cooling effect. The counter-balance is driven by a third linear motor to cancel motion induced forces that would otherwise be transmitted to the spacecraft. An analog control system is currently used for bearing control. The purpose of this project is to investigate the possibilities for improved performance using digital control. Areas for potential improvement include transient and steady state control characteristics, robustness, reliability, adaptability, alternate control modes, size, weight, and cost. The present control system is targeted for the Intel 80196 microcontroller family. The eventual introduction of application specific integrated circuit (ASIC) technology to this problem may produce a unique and elegant solution both here and in related industrial problems.

  8. Environment and health: Probes and sensors for environment digital control

    NASA Astrophysics Data System (ADS)

    Schettini, Chiara

    2014-05-01

    The idea of studying the environment using New Technologies (NT) came from a MIUR (Ministry of Education of the Italian Government) notice that allocated funds for the realization of innovative school science projects. The "Environment and Health" project uses probes and sensors for digital control of environment (water, air and soil). The working group was composed of 4 Science teachers from 'Liceo Statale G. Mazzini ', under the coordination of teacher Chiara Schettini. The Didactic Section of Naples City of Sciences helped the teachers in developing the project and it organized a refresher course for them on the utilization of digital control sensors. The project connects Environment and Technology because the study of the natural aspects and the analysis of the chemical-physical parameters give students and teachers skills for studying the environment based on the utilization of NT in computing data elaboration. During the practical project, samples of air, water and soil are gathered in different contexts. Sample analysis was done in the school's scientific laboratory with digitally controlled sensors. The data are elaborated with specific software and the results have been written in a booklet and in a computing database. During the first year, the project involved 6 school classes (age of the students 14—15 years), under the coordination of Science teachers. The project aims are: 1) making students more aware about environmental matters 2) achieving basic skills for evaluating air, water and soil quality. 3) achieving strong skills for the utilization of digitally controlled sensors. 4) achieving computing skills for elaborating and presenting data. The project aims to develop a large environmental conscience and the need of a ' good ' environment for defending our health. Moreover it would increase the importance of NT as an instrument of knowledge.

  9. Digital Estimation and Control for Air Refueling Rendezvous.

    DTIC Science & Technology

    1982-12-01

    in earnest. Suddenly, C-141 flight crews had to develop expertise in an area in which they had virtually no experience - air refueling. The...reduced up to 47%. vii DIGITAL ESTIMATION AND CONTROL FOR AIR REFUELING RENDEZVOUS I Introduction Certainly, in- flight refueling is a vital element...military responses to a perceived threat anywhere in the world. Of course the great advantage of in- flight refueling is that it eliminates the need

  10. A Flight Investigation of Digital Control Using Microprocessor Technology.

    DTIC Science & Technology

    1979-06-01

    DISPLAYS COTOSE IRF MOTIONS I I T EALATIONl PILOT FEPERIANTAL. Figure 3-2. Overview of the VRA/Micro- DFCS System. mechanical linkage connecting to the...April 1979 CELEC T E D 1 .... 3 OCT 23 1980 DISTRIBUTIOD Sor . D : - U Approved for public . Distribution Uniirnitcd - UNC LASS SECURITY CLASSIFICATION...CLASSIFICATION OF Ywl PAGE(IWhen Data Enterod) ABSTRACT A microprocessor-based digital flight control system (Micro- DFCS ) is implemented in Princeton’s

  11. Simultaneous dual directional strain measurement using spatial phase-shift digital shearography

    NASA Astrophysics Data System (ADS)

    Wang, Yonghong; Gao, Xinya; Xie, Xin; Wu, Sijing; Liu, Yingxue; Yang, Lianxiang

    2016-12-01

    This paper presents a Dual Directional Sheared Spatial Phase-Shift Digital Shearography (DDS-SPS-DS) system for simultaneous measurement of strains/displacement derivative in two directions. Two Michelson Interferometers are used as the shearing device to create two shearograms, one in the x-shearing direction and one in the y-shearing direction, which are recorded by a single CCD camera. Two lasers with different wavelengths are used for illumination, and corresponding band pass filters are applied in front of each Michelson Interferometer to avoid cross-interference between the two shearing direction channels. Two perpendicular shearing directions in the two measurement channels introduce two different spatial frequency carriers whose spectrums are orientated in different directions after Fourier Transform. Phase maps of the recorded two shearograms can be obtained by applying a windowed inverse Fourier transform, which enables simultaneous measurement of dual directional strains/displacement derivatives. The new system is well suited for nondestructive testing and strain measurement with a continuous or dynamic load. The capability of the dual directional spatial phase-shift digital shearography system is described by theoretical discussions as well as experiments.

  12. 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.

  13. Doses measured using AEC on direct digital radiographic (DDR) X-rays systems: updated results with an RP 162 perspective.

    PubMed

    Bowden, L; Faulkner, R; Gallagher, A; O'Connor, U; Walsh, C; Dowling, A; O'Reilly, G

    2013-02-01

    As digital technology in diagnostic radiology systems becomes more prevalent, there is a need to provide comparative dose information for these new systems. This is needed in particular for testing the automatic exposure control (AEC) devices on direct digital radiography (DDR) systems as there is no consensus on the receptor dose level in the current guidelines. The new European Commission RP 162 document sets the suspension level for the 'verification of kerma at receptor entrance in computed radiography and DDR systems under AEC' as ≥10 µGy. This document also notes that alternate methodologies are acceptable, and may require adjustment in the suspension level if used. This study provides a range of typical doses under AEC for DDR systems, for a variety measurement methodologies, including that described in RP 162.

  14. Content-based fused off-axis object illumination direct-to-digital holography

    DOEpatents

    Price, Jeffery R.

    2006-05-02

    Systems and methods are described for content-based fused off-axis illumination direct-to-digital holography. A method includes calculating an illumination angle with respect to an optical axis defined by a focusing lens as a function of data representing a Fourier analyzed spatially heterodyne hologram; reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object the object beam incident upon the object at the illumination angle; focusing the reference beam and the object beam at a focal plane of a digital recorder to from the content-based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording the content based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.

  15. Digital EPR with an arbitrary waveform generator and direct detection at the carrier frequency.

    PubMed

    Tseitlin, Mark; Quine, Richard W; Rinard, George A; Eaton, Sandra S; Eaton, Gareth R

    2011-12-01

    A digital EPR spectrometer was constructed by replacing the traditional bridge with an arbitrary waveform generator (AWG) to produce excitation patterns and a high-speed digitizer for direct detection of the spin system response at the carrier frequency. Digital down-conversion produced baseband signals in quadrature with very precise orthogonality. Real-time resonator tuning was performed by monitoring the Fourier transforms of signals reflected from the resonator during frequency sweeps generated by the AWG. The capabilities of the system were demonstrated by rapid magnetic field scans at 256 MHz carrier frequency, and FID and spin echo experiments at 1 and 10 GHz carrier frequencies. For the rapid scan experiments the leakage through a cross-loop resonator was compensated by adjusting the amplitude and phase of a sinusoid at the carrier frequency that was generated with another AWG channel.

  16. A digital computer propulsion control facility: Description of capabilities and summary of experimental program results

    NASA Technical Reports Server (NTRS)

    Zeller, J. R.; Arpasi, D. J.; Lehtinen, B.

    1976-01-01

    Flight weight digital computers are being used today to carry out many of the propulsion system control functions previously delegated exclusively to hydromechanical controllers. An operational digital computer facility for propulsion control mode studies has been used successfully in several experimental programs. This paper describes the system and some of the results concerned with engine control, inlet control, and inlet engine integrated control. Analytical designs for the digital propulsion control modes include both classical and modern/optimal techniques.

  17. Controller-independent bidirectional quantum direct communication

    NASA Astrophysics Data System (ADS)

    Mohapatra, Amit Kumar; Balakrishnan, S.

    2017-06-01

    Recently, Chang et al. (Quantum Inf Process 14:3515-3522, 2015) proposed a controlled bidirectional quantum direct communication protocol using Bell states. In this work, the significance of Bell states, which are being used as initial states in Chang et al. protocol, is elucidated. The possibility of preparing initial state based on the secret message of the communicants is explored. In doing so, the controller-independent bidirectional quantum direct communication protocol has evolved naturally. It is shown that any communicant cannot read the secret message without knowing the initial states generated by the other communicant. Further, intercept-and-resend attack and information leakage can be avoided. The proposed protocol is like a conversion between two persons without the help of any third person with high-level security.

  18. Trending now: future directions in digital media for the public health sector.

    PubMed

    Burke-Garcia, Amelia; Scally, Gabriel

    2014-12-01

    Digital media usage is expanding enormously and is starting to be used as a public health intervention and communication tool. It has an ability to increase the reach of public health research and communication, as well as drive measurable behaviour change. But there is an absence of both deep and wide understanding of the opportunities within digital media, i.e. most people think only of Facebook and Twitter when they think of social media; smart, strategic planning for its widespread use is not common practice and rigorous evaluative studies of its effectiveness are few and far between. This paper analyses the published literature on this topic and identifies the top 10 directions that use of digital media is likely to take in the medium term. The analysis strongly supports the position that digital media needs to be taken seriously as a vehicle for public health activity in its own right and not merely as an adjunct to other campaigns. Digital media will continue to develop and move from being an add-on to existing activity to being the major vehicle for significant elements of research, data collection and advocacy. It is important that public health leaders fully understand and engage in its development and use. © The Author 2014. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. for permissions, please e-mail: journals.permissions@oup.com.

  19. Direct elicitation of template concentration from quantification cycle (Cq) distributions in digital PCR

    PubMed Central

    Mojtahedi, Mitra; Fouquier d'Hérouël, Aymeric; Huang, Sui

    2014-01-01

    Digital PCR (dPCR) exploits limiting dilution of a template into an array of PCR reactions. From this array the number of reactions that contain at least one (as opposed to zero) initial template is determined, allowing inferring the original template concentration. Here we present a novel protocol to efficiently infer the concentration of a sample and its optimal dilution for dPCR from few targeted qPCR assays. By taking advantage of the real-time amplification feature of qPCR as opposed to relying on endpoint PCR assessment as in standard dPCR prior knowledge of template concentration is not necessary. This eliminates the need for serial dilutions in a separate titration and reduces the number of necessary reactions. We describe the theory underlying our approach and discuss experimental moments that contribute to uncertainty. We present data from a controlled experiment where the initial template concentration is known as proof of principle and apply our method on directly monitoring transcript level change during cell differentiation as well as gauging amplicon numbers in cDNA samples after pre-amplification. PMID:25104023

  20. High-Resolution Synthesizable Digitally-Controlled Delay Lines

    NASA Astrophysics Data System (ADS)

    Giordano, R.; Ameli, F.; Bifulco, P.; Bocci, V.; Cadeddu, S.; Izzo, V.; Lai, A.; Mastroianni, S.; Aloisio, A.

    2015-12-01

    Digitally-controlled delay lines (DCDLs) play a key role in timing distribution for trigger and data acquisition systems (TDAQ) of high energy Physics (HEP), where it is often necessary to add an open-loop fine-grained programmable phase delay to distributed clocks and/or data lines. In this work, we present the performance of DCDLs implemented according to an all-digital novel architecture. The architecture is completely technology-independent, it is described by means of a hardware description language and it can be placed and routed with automatic tools. Our solution is aimed at being used as a synthesizable block in FPGAs, as a proof-of-concept we implemented a prototype in a Xilinx Kintex-7 FPGA. We discuss the measured performance of the implemented delay line in terms of delay range, resolution and linearity. The logic utilization of the delay lines is also presented in the view of a scalable implementation.

  1. Recognition of one-, two-, and three-pair dichotic digits under free and directed recall.

    PubMed

    Strouse, A; Wilson, R H

    1999-01-01

    A one-, two-, and three-pair dichotic digit test was administered to 180 subjects (20-79 years) with varying degrees of hearing sensitivity. The test was carried out under free- and directed-recall response conditions. The results indicated that recognition performance decreased as a function of increasing age. Statistical analysis using analysis of covariance indicated that differences in performance between age groups were not owing to differences in hearing sensitivity. Thus, with the effects of hearing sensitivity removed, age alone accounted for a significant portion of the variability in the data among age groups. Normative data for the free-recall condition are reported for the two lists of randomly interleaved one-, two-, and three-pair digits included on the Tonal and Speech Materials for Auditory Perceptual Assessment, Disc 2.0 (1998) compact disc. A comparison of performance in free- and directed-recall conditions indicated three patterns of results. First, 58 percent of the subjects had normal recognition performance for one-, two-, and three-pair digits under both recall conditions. Second, 39 percent of the subjects had a deficit in the free-recall condition, with normal performance in the directed-recall condition, which was interpreted as representing primarily a cognitive problem. Third, the remaining 3 percent of the subjects showed a deficit in both free- and directed-recall conditions, which was attributed primarily to an auditory problem.

  2. Feasibility of direct digital sampling for diffuse optical frequency domain spectroscopy in tissue

    NASA Astrophysics Data System (ADS)

    Roblyer, Darren; O'Sullivan, Thomas D.; Warren, Robert V.; Tromberg, Bruce J.

    2013-04-01

    Frequency domain optical spectroscopy in the diffusive regime is currently being investigated for biomedical applications including tumor detection, therapy monitoring, exercise metabolism and others. Analog homodyne or heterodyne detection of sinusoidally modulated signals has been the predominant method for measuring phase and amplitude of photon density waves that have traversed through tissue. Here we demonstrate the feasibility of utilizing direct digital sampling of modulated signals using a 3.6 gigasample/second 12 bit analog to digital converter. Digitally synthesized modulated signals between 50 MHz and 400 MHz were measured on tissue-simulating phantoms at six near-infrared wavelengths. An amplitude and phase precision of 1% and 0.6° were achieved during drift tests. Amplitude, phase, scattering and absorption values were compared with a well-characterized network analyzer-based diffuse optical device. Optical properties measured with both systems were within 3.6% for absorption and 2.8% for scattering over a range of biologically relevant values. Direct digital sampling represents a viable method for frequency domain diffuse optical spectroscopy and has the potential to reduce system complexity, size and cost.

  3. Feasibility of Direct Digital Sampling for Diffuse Optical Frequency Domain Spectroscopy in Tissue.

    PubMed

    Roblyer, Darren; O'Sullivan, Thomas D; Warren, Robert V; Tromberg, Bruce

    2013-04-01

    Frequency domain optical spectroscopy in the diffusive regime is currently being investigated for biomedical applications including tumor detection, therapy monitoring, exercise metabolism, and others. Analog homodyne or heterodyne detection of sinusoidally modulated signals have been the predominant method for measuring phase and amplitude of photon density waves that have traversed through tissue. Here we demonstrate the feasibility of utilizing direct digital sampling of modulated signals using a 3.6 Gigasample/second 12 bit Analog to Digital Converter. Digitally synthesized modulated signals between 50MHz and 400MHz were measured on tissue simulating phantoms at six near-infrared wavelengths. An amplitude and phase precision of 1% and 0.6 degrees were achieved during drift tests. Amplitude, phase, scattering and absorption values were compared with a well-characterized network analyzer based diffuse optical device. Measured optical properties measured with both systems were within 3.6% for absorption and 2.8% for scattering over a range of biologically relevant values. Direct digital sampling represents a viable method for frequency domain diffuse optical spectroscopy and has the potential to reduce system complexity, size, and cost.

  4. Digital Signal Processing and Control for the Study of Gene Networks

    NASA Astrophysics Data System (ADS)

    Shin, Yong-Jun

    2016-04-01

    Thanks to the digital revolution, digital signal processing and control has been widely used in many areas of science and engineering today. It provides practical and powerful tools to model, simulate, analyze, design, measure, and control complex and dynamic systems such as robots and aircrafts. Gene networks are also complex dynamic systems which can be studied via digital signal processing and control. Unlike conventional computational methods, this approach is capable of not only modeling but also controlling gene networks since the experimental environment is mostly digital today. The overall aim of this article is to introduce digital signal processing and control as a useful tool for the study of gene networks.

  5. Digital Signal Processing and Control for the Study of Gene Networks

    PubMed Central

    Shin, Yong-Jun

    2016-01-01

    Thanks to the digital revolution, digital signal processing and control has been widely used in many areas of science and engineering today. It provides practical and powerful tools to model, simulate, analyze, design, measure, and control complex and dynamic systems such as robots and aircrafts. Gene networks are also complex dynamic systems which can be studied via digital signal processing and control. Unlike conventional computational methods, this approach is capable of not only modeling but also controlling gene networks since the experimental environment is mostly digital today. The overall aim of this article is to introduce digital signal processing and control as a useful tool for the study of gene networks. PMID:27102828

  6. Digital Signal Processing and Control for the Study of Gene Networks.

    PubMed

    Shin, Yong-Jun

    2016-04-22

    Thanks to the digital revolution, digital signal processing and control has been widely used in many areas of science and engineering today. It provides practical and powerful tools to model, simulate, analyze, design, measure, and control complex and dynamic systems such as robots and aircrafts. Gene networks are also complex dynamic systems which can be studied via digital signal processing and control. Unlike conventional computational methods, this approach is capable of not only modeling but also controlling gene networks since the experimental environment is mostly digital today. The overall aim of this article is to introduce digital signal processing and control as a useful tool for the study of gene networks.

  7. Propulsion control experience used in the Highly Integrated Digital Electronic Control (HIDEC) program

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    The highly integrated digital electronic control (HIDEC) program will integrate the propulsion and flight control systems on an F-15 airplane at NASA Ames Research Center's Dryden Flight Research Facility. Ames-Dryden has conducted several propulsion control programs that have contributed to the HIDEC program. The digital electronic engine control (DEEC) flight evaluation investigated the performance and operability of the F100 engine equipped with a full-authority digital electronic control system. Investigations of nozzle instability, fault detection and accommodation, and augmentor transient capability provided important information for the HIDEC program. The F100 engine model derivative (EMD) was also flown in the F-15 airplane, and airplane performance was significantly improved. A throttle response problem was found and solved with a software fix to the control logic. For the HIDEC program, the F100 EMD engines equipped with DEEC controls will be integrated with the digital flight control system. The control modes to be implemented are an integrated flightpath management mode and an integrated adaptive engine control system mode. The engine control experience that will be used in the HIDEC program is discussed.

  8. An Evidence-Based Systematic Review of Directional Microphones and Digital Noise Reduction Hearing Aids in School-Age Children With Hearing Loss

    PubMed Central

    McCreery, Ryan W.; Venediktov, Rebecca A.; Coleman, Jaumeiko J.; Leech, Hillary M.

    2013-01-01

    Purpose The purpose of this evidence-based systematic review was to evaluate the efficacy of digital noise reduction and directional microphones for outcome measures of audibility, speech recognition, speech and language, and self- or parent-report in pediatric hearing aid users. Method The authors searched 26 databases for experimental studies published after 1980 addressing one or more clinical questions and meeting all inclusion criteria. The authors evaluated studies for methodological quality and reported or calculated p values and effect sizes when possible. Results A systematic search of the literature resulted in the inclusion of 4 digital noise reduction and 7 directional microphone studies (in 9 journal articles) that addressed speech recognition, speech and language, and/or self-or parent-report outcomes. No digital noise reduction or directional microphone studies addressed audibility outcomes. Conclusions On the basis of a moderate level of evidence, digital noise reduction was not found to improve or degrade speech understanding. Additional research is needed before conclusions can be drawn regarding the impact of digital noise reduction on important speech, language, hearing, and satisfaction outcomes. Moderate evidence also indicates that directional microphones resulted in improved speech recognition in controlled optimal settings; however, additional research is needed to determine the effectiveness of directional microphones in actual everyday listening environments. PMID:22858614

  9. An evidence-based systematic review of directional microphones and digital noise reduction hearing aids in school-age children with hearing loss.

    PubMed

    McCreery, Ryan W; Venediktov, Rebecca A; Coleman, Jaumeiko J; Leech, Hillary M

    2012-12-01

    The purpose of this evidence-based systematic review was to evaluate the efficacy of digital noise reduction and directional microphones for outcome measures of audibility, speech recognition, speech and language, and self- or parent-report in pediatric hearing aid users. The authors searched 26 databases for experimental studies published after 1980 addressing one or more clinical questions and meeting all inclusion criteria. The authors evaluated studies for methodological quality and reported or calculated p values and effect sizes when possible. A systematic search of the literature resulted in the inclusion of 4 digital noise reduction and 7 directional microphone studies (in 9 journal articles) that addressed speech recognition, speech and language, and/or self- or parent-report outcomes. No digital noise reduction or directional microphone studies addressed audibility outcomes. On the basis of a moderate level of evidence, digital noise reduction was not found to improve or degrade speech understanding. Additional research is needed before conclusions can be drawn regarding the impact of digital noise reduction on important speech, language, hearing, and satisfaction outcomes. Moderate evidence also indicates that directional microphones resulted in improved speech recognition in controlled optimal settings; however, additional research is needed to determine the effectiveness of directional microphones in actual everyday listening environments.

  10. Controlling Directed Protein Interaction Networks in Cancer.

    PubMed

    Kanhaiya, Krishna; Czeizler, Eugen; Gratie, Cristian; Petre, Ion

    2017-09-04

    Control theory is a well-established approach in network science, with applications in bio-medicine and cancer research. We build on recent results for structural controllability of directed networks, which identifies a set of driver nodes able to control an a-priori defined part of the network. We develop a novel and efficient approach for the (targeted) structural controllability of cancer networks and demonstrate it for the analysis of breast, pancreatic, and ovarian cancer. We build in each case a protein-protein interaction network and focus on the survivability-essential proteins specific to each cancer type. We show that these essential proteins are efficiently controllable from a relatively small computable set of driver nodes. Moreover, we adjust the method to find the driver nodes among FDA-approved drug-target nodes. We find that, while many of the drugs acting on the driver nodes are part of known cancer therapies, some of them are not used for the cancer types analyzed here; some drug-target driver nodes identified by our algorithms are not known to be used in any cancer therapy. Overall we show that a better understanding of the control dynamics of cancer through computational modelling can pave the way for new efficient therapeutic approaches and personalized medicine.

  11. Radiographic determination of canal length direct digital radiography versus conventional radiography.

    PubMed

    Hedrick, R T; Dove, S B; Peters, D D; McDavid, W D

    1994-07-01

    This research compared the length determination images produced by Trophy and Regam direct digital radiographic systems with conventional E-speed radiographs. Size #15 K files were placed in the canals of 19 teeth of cadaver specimens and radiographed in a geometrically standardized bench device. Three evaluators estimated the length adjustment necessary to position the file at the apex. The mean estimated adjustment lengths were compared with the true, anatomically determined adjustment lengths. Statistical analysis with analysis of variance and the Student-Newman-Keuls test indicated no significant difference between direct digital thermal print images and conventional radiographs (p > 0.10). Length adjustment estimates with conventional radiographs were significantly more accurate than Regam high-resolution computer monitor images (p < 0.01). Additionally, it was determined that length adjustment estimates were significantly more accurate when the file was placed short of the apex (p < 0.001). The clinical relevance of these differences is discussed.

  12. The average direct current offset values for small digital audio recorders in an acoustically consistent environment.

    PubMed

    Koenig, Bruce E; Lacey, Douglas S

    2014-07-01

    In this research project, nine small digital audio recorders were tested using five sets of 30-min recordings at all available recording modes, with consistent audio material, identical source and microphone locations, and identical acoustic environments. The averaged direct current (DC) offset values and standard deviations were measured for 30-sec and 1-, 2-, 3-, 6-, 10-, 15-, and 30-min segments. The research found an inverse association between segment lengths and the standard deviation values and that lengths beyond 30 min may not meaningfully reduce the standard deviation values. This research supports previous studies indicating that measured averaged DC offsets should only be used for exclusionary purposes in authenticity analyses and exhibit consistent values when the general acoustic environment and microphone/recorder configurations were held constant. Measured average DC offset values from exemplar recorders may not be directly comparable to those of submitted digital audio recordings without exactly duplicating the acoustic environment and microphone/recorder configurations.

  13. A digital receiver module with direct data acquisition for magnetic resonance imaging systems.

    PubMed

    Tang, Weinan; Sun, Hongyu; Wang, Weimin

    2012-10-01

    A digital receiver module for magnetic resonance imaging (MRI) with detailed hardware implementations is presented. The module is based on a direct sampling scheme using the latest mixed-signal circuit design techniques. A single field-programmable gate array chip is employed to perform software-based digital down conversion for radio frequency signals. The modular architecture of the receiver allows multiple acquisition channels to be implemented on a highly integrated printed circuit board. To maintain the phase coherence of the receiver and the exciter in the context of direct sampling, an effective phase synchronization method was proposed to achieve a phase deviation as small as 0.09°. The performance of the described receiver module was verified in the experiments for both low- and high-field (0.5 T and 1.5 T) MRI scanners and was compared to a modern commercial MRI receiver system.

  14. Digital feedwater and recirculation flow control for GPUN Oyster Creek

    SciTech Connect

    Burjorjee, D. ); Gan, B. )

    1992-01-01

    This paper describes the digital system for feedwater and recirculation control that GPU Nuclear will be installing at Oyster Creek during its next outage - expected circa December 1992. The replacement was motivated by considerations of reliability and obsolescence - the analog equipment was aging and reaching the end of its useful life. The new system uses Atomic Energy of Canada Ltd.'s software platform running on dual, redundant, industrial-grade 386 computers with opto-isolated field input/output (I/O) accessed through a parallel bus. The feedwater controller controls three main feed regulating valves, two low flow regulating valves, and two block valves. The recirculation controller drives the five scoop positioners of the hydraulic couplers. The system also drives contacts that lock up the actuators on detecting an open circuit in their current loops.

  15. A comparison of digital flight control design methods

    NASA Technical Reports Server (NTRS)

    Powell, J. D.; Parsons, E.; Tashker, M. G.

    1976-01-01

    Many variations in design methods for aircraft digital flight control have been proposed in the literature. In general, the methods fall into two categories: those where the design is done in the continuous domain (or s-plane), and those where the design is done in the discrete domain (or z-plane). This paper evaluates several variations of each category and compares them for various flight control modes of the Langley TCV Boeing 737 aircraft. Design method fidelity is evaluated by examining closed loop root movement and the frequency response of the discretely controlled continuous aircraft. It was found that all methods provided acceptable performance for sample rates greater than 10 cps except the 'uncompensated s-plane design' method which was acceptable above 20 cps. A design procedure based on optimal control methods was proposed that provided the best fidelity at very slow sample rates and required no design iterations for changing sample rates.

  16. Nonlinear and Digital Man-machine Control Systems Modeling

    NASA Technical Reports Server (NTRS)

    Mekel, R.

    1972-01-01

    An adaptive modeling technique is examined by which controllers can be synthesized to provide corrective dynamics to a human operator's mathematical model in closed loop control systems. The technique utilizes a class of Liapunov functions formulated for this purpose, Liapunov's stability criterion and a model-reference system configuration. The Liapunov function is formulated to posses variable characteristics to take into consideration the identification dynamics. The time derivative of the Liapunov function generate the identification and control laws for the mathematical model system. These laws permit the realization of a controller which updates the human operator's mathematical model parameters so that model and human operator produce the same response when subjected to the same stimulus. A very useful feature is the development of a digital computer program which is easily implemented and modified concurrent with experimentation. The program permits the modeling process to interact with the experimentation process in a mutually beneficial way.

  17. Digital adaptive controllers for VTOL vehicles. Volume 1: Concept evaluation

    NASA Technical Reports Server (NTRS)

    Hartmann, G. L.; Stein, G.; Pratt, S. G.

    1979-01-01

    A digital self-adaptive flight control system was developed for flight test in the VTOL approach and landing technology (VALT) research aircraft (a modified CH-47 helicopter). The control laws accept commands from an automatic on-board guidance system. The primary objective of the control laws is to provide good command-following with a minimum cross-axis response. Three attitudes and vertical velocity are separately commanded. Adaptation of the control laws is based on information from rate and attitude gyros and a vertical velocity measurement. The final design resulted from a comparison of two different adaptive concepts--one based on explicit parameter estimates from a real-time maximum-likelihood estimation algorithm, the other based on an implicit model reference adaptive system. The two designs were compared on the basis of performance and complexity.

  18. 47 CFR 76.1909 - Redistribution control of unencrypted digital terrestrial broadcast content.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Redistribution control of unencrypted digital... Redistribution control of unencrypted digital terrestrial broadcast content. (a) For the purposes of this section, the terms unencrypted digital terrestrial broadcast content, EIT, PMT, broadcast flag, covered...

  19. 47 CFR 76.1909 - Redistribution control of unencrypted digital terrestrial broadcast content.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Redistribution control of unencrypted digital... Redistribution control of unencrypted digital terrestrial broadcast content. (a) For the purposes of this section, the terms unencrypted digital terrestrial broadcast content, EIT, PMT, broadcast flag, covered...

  20. 47 CFR 76.1909 - Redistribution control of unencrypted digital terrestrial broadcast content.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Redistribution control of unencrypted digital... Redistribution control of unencrypted digital terrestrial broadcast content. (a) For the purposes of this section, the terms unencrypted digital terrestrial broadcast content, EIT, PMT, broadcast flag, covered...

  1. 47 CFR 76.1909 - Redistribution control of unencrypted digital terrestrial broadcast content.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Redistribution control of unencrypted digital... Redistribution control of unencrypted digital terrestrial broadcast content. (a) For the purposes of this section, the terms unencrypted digital terrestrial broadcast content, EIT, PMT, broadcast flag, covered...

  2. Migration of Older to New Digital Control Systems in Nuclear Power Plant Main Control Rooms

    SciTech Connect

    Kovesdi, Casey Robert; Joe, Jeffrey Clark

    2016-04-01

    The United States (U.S.) Department of Energy (DOE) Office of Nuclear Energy (NE) has the primary mission to advance nuclear power by resolving socio-technical issues through research and development (R&D). One DOE-NE activity supporting this mission is the Light Water Reactor Sustainability (LWRS) program. LWRS has the overall objective to sustain the operation of existing commercial nuclear power plants (NPPs) through conducting R&D across multiple “pathways,” or R&D focus areas. The Advanced Instrumentation, Information, and Control (II&C) Systems Technologies pathway conducts targeted R&D to address aging and reliability concerns with the legacy instrumentation and control (I&C) and related information systems in operating U.S. NPPs. This work involves (1) ensuring that legacy analog II&C systems are not life-limiting issues for the LWR fleet, and (2) implementing digital II&C technology in a manner that enables broad innovation and business improvement in the NPP operating model. Under the LWRS Advanced II&C pathway, Human Factors experts at Idaho National Laboratory (INL) have been conducting R&D in support of NPP main control room (MCR) modernization activities. Work in prior years has focused on migrating analog I&C systems to new digital I&C systems (). In fiscal year 2016 (FY16), one new focus area for this research is migrating older digital I&C systems to new and advanced digital I&C systems. This report summarizes a plan for conducting a digital-to-digital migration of a legacy digital I&C system to a new digital I&C system in support of control room modernization activities.

  3. A task-based quality control metric for digital mammography

    NASA Astrophysics Data System (ADS)

    Maki Bloomquist, A. K.; Mainprize, J. G.; Mawdsley, G. E.; Yaffe, M. J.

    2014-11-01

    A reader study was conducted to tune the parameters of an observer model used to predict the detectability index (dʹ ) of test objects as a task-based quality control (QC) metric for digital mammography. A simple test phantom was imaged to measure the model parameters, namely, noise power spectrum, modulation transfer function and test-object contrast. These are then used in a non-prewhitening observer model, incorporating an eye-filter and internal noise, to predict dʹ. The model was tuned by measuring dʹ of discs in a four-alternative forced choice reader study. For each disc diameter, dʹ was used to estimate the threshold thicknesses for detectability. Data were obtained for six types of digital mammography systems using varying detector technologies and x-ray spectra. A strong correlation was found between measured and modeled values of dʹ, with Pearson correlation coefficient of 0.96. Repeated measurements from separate images of the test phantom show an average coefficient of variation in dʹ for different systems between 0.07 and 0.10. Standard deviations in the threshold thickness ranged between 0.001 and 0.017 mm. The model is robust and the results are relatively system independent, suggesting that observer model dʹ shows promise as a cross platform QC metric for digital mammography.

  4. A task-based quality control metric for digital mammography.

    PubMed

    Bloomquist, A K Maki; Mainprize, J G; Mawdsley, G E; Yaffe, M J

    2014-11-07

    A reader study was conducted to tune the parameters of an observer model used to predict the detectability index (dʹ ) of test objects as a task-based quality control (QC) metric for digital mammography. A simple test phantom was imaged to measure the model parameters, namely, noise power spectrum,modulation transfer function and test-object contrast. These are then used ina non-prewhitening observer model, incorporating an eye-filter and internal noise, to predict dʹ. The model was tuned by measuring dʹ of discs in a four-alternative forced choice reader study. For each disc diameter, dʹ was used to estimate the threshold thicknesses for detectability. Data were obtained for six types of digital mammography systems using varying detector technologies and x-ray spectra. A strong correlation was found between measured and modeled values of dʹ, with Pearson correlation coefficient of 0.96. Repeated measurements from separate images of the test phantom show an average coefficient of variation in dʹ for different systems between 0.07 and 0.10. Standard deviations in the threshold thickness ranged between 0.001 and 0.017 mm. The model is robust and the results are relatively system independent, suggesting that observer model dʹ shows promise as a cross platform QC metric for digital mammography.

  5. 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.

  6. Digital redesign of anti-wind-up controller for cascaded analog system.

    PubMed

    Chen, Y S; Tsai, J S H; Shieh, L S; Moussighi, M M

    2003-01-01

    The cascaded conventional anti-wind-up (CAW) design method for integral controller is discussed. Then, the prediction-based digital redesign methodology is utilized to find the new pulse amplitude modulated (PAM) digital controller for effective digital control of the analog plant with input saturation constraint. The desired digital controller is determined from existing or pre-designed CAW analog controller. The proposed method provides a novel methodology for indirect digital design of a continuous-time unity output-feedback system with a cascaded analog controller as in the case of PID controllers for industrial control processes with the presence of actuator saturations. It enables us to implement an existing or pre-designed cascaded CAW analog controller via a digital controller effectively.

  7. Innovation & evaluation of tangible direct manipulation digital drawing pens for children.

    PubMed

    Lee, Tai-Hua; Wu, Fong-Gong; Chen, Huei-Tsz

    2017-04-01

    Focusing on the theme of direct manipulation, in this study, we proposed a new and innovative tangible user interface (TUI) design concept for a manipulative digital drawing pen. Based on interviews with focus groups brainstorming and experts and the results of a field survey, we selected the most suitable tangible user interface for children between 4 and 7 years of age. Using the new tangible user interface, children could choose between the brush tools after touching and feeling the various patterns. The thickness of the brush could be adjusted by changing the tilt angle. In a subsequent experimental process we compared the differences in performance and subjective user satisfaction. A total of sixteen children, aged 4-7 years participated in the experiment. Two operating system experiments (the new designed tangible digital drawing pen and traditional visual interface-icon-clicking digital drawing pens) were performed at random and in turns. We assessed their manipulation performance, accuracy, brush stroke richness and subjective evaluations. During the experimental process we found that operating functions using the direct manipulation method, and adding shapes and semantic models to explain the purpose of each function, enabled the children to perform stroke switches relatively smoothly. By using direct manipulation digital pens, the children could improve their stroke-switching performance for digital drawing. Additionally, by using various patterns to represent different brushes or tools, the children were able to make selections using their sense of touch, thereby reducing the time required to move along the drawing pens and select icons (The significant differences (p = 0.000, p < 0.01) existed in the manipulation times for drawing thick lines using the crayon function of the two (new and old) drawing pens (new 5.8750 < old 10.7500)). The addition of direct manipulation movements to drawing operations enhanced the drawing results, thereby

  8. Short radius drilling system improves directional control

    SciTech Connect

    Leazer, C.

    1995-08-01

    Horizontal drilling capabilities and applications have been dramatically increased with development of Becfield Drilling Services` Short Radius Horizontal Drilling System utilizing the Articulated Downhole Drilling Motor (ADM). The system gives precise directional control, predictability , and reliability not previously available in short-radius operations. Because of the unique, patented design of the ADM, the short-radius system can be rotated during lateral drilling operations. This is a significant development in short-radius horizontal drilling technology. This paper reviews the design and operation of this equipment.

  9. Anticipatory planning and control of grasp positions and forces for dexterous two-digit manipulation.

    PubMed

    Fu, Qiushi; Zhang, Wei; Santello, Marco

    2010-07-07

    Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the CNS could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate digit placement for optimal force distribution and digit forces as a function of variable digit positions. All subjects learned to minimize object roll within the first three trials, and the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics.

  10. Utilization of a digital method to determine the rotation direction in incremental photoelectric encoder

    NASA Astrophysics Data System (ADS)

    Li, Yousheng

    2010-10-01

    The principles of incremental photoelectric encoders are: When a encoder disk rotates, (1)it will produce the pulse signal proportional to the angle; (2) it will also produce the sensing signal of identifying the rotation direction. The way that the existing incremental photoelectric encoders determine the rotation direction is: one encoder disk has 3 code channels: 'A', 'B' and 'Z'. On both 'A' and 'B' code channels, there are a number of evenly distributed grid holes, and they have the same cycle, but with one quarter cycle difference in phase between channel 'A' and 'B'. When disk rotates clockwise, signal phase from 'A' channel is a quarter cycle ahead of that from 'B'; Similarly, when disk rotates counterclockwise, 'B' signal phase will be a quarter cycle ahead of 'A'. Based on the above phenomena, a circuit can identify the rotation direction, which is known as 'Kam-Phase Method'. The mechanism of the new direction recognition method is: When the encoder disk rotates , it continuously generates three kinds of state binary information sequentially. These three states are defined as state 1, state 2, state 3. While rotating clockwise, the state changes in the order of state 1, state 2, state 3, state 1.....; While rotating counterclockwise, the state changes in the sequence of state 1, state 3, state 2, state 1..... The new theory differentiate the digitized state changing sequence between the clockwise and counter clockwise to determine the rotation direction.This method is called as 'Digital Method'. The advantages of applying the digital method for the rotation direction determination in incremental photoelectric encoder are: the code channel structure is simpler and there is no accumulative errors and so on.

  11. Improving the digital workflow: direct transfer from patient to virtual articulator.

    PubMed

    Solaberrieta, Eneko; Minguez, Rikardo; Etxaniz, Olatz; Barrenetxea, Lander

    2013-01-01

    When designing a custom-made dental restoration, using a digital workflow represents an important advance over mechanical tools such as facebows or mechanical articulators. When using virtual scanning procedures, there is a direct transfer from the patient to the articulator. This paper presents a novel methodology to design custom-made restorations. This new approach permits the transfer of all data directly from the patient to the virtual articulator, always taking into account the kinematics of the mandible. Rapid further developments can be expected in the near future.

  12. Holographic digital microscopy in on-line process control

    NASA Astrophysics Data System (ADS)

    Osanlou, Ardeshir

    2011-09-01

    This article investigates the feasibility of real-time three-dimensional imaging of microscopic objects within various emulsions while being produced in specialized production vessels. The study is particularly relevant to on-line process monitoring and control in chemical, pharmaceutical, food, cleaning, and personal hygiene industries. Such processes are often dynamic and the materials cannot be measured once removed from the production vessel. The technique reported here is applicable to three-dimensional characterization analyses on stirred fluids in small reaction vessels. Relatively expensive pulsed lasers have been avoided through the careful control of the speed of the moving fluid in relation to the speed of the camera exposure and the wavelength of the continuous wave laser used. The ultimate aim of the project is to introduce a fully robust and compact digital holographic microscope as a process control tool in a full size specialized production vessel.

  13. Gimballing magnetic bearing reaction wheel with digital controller

    NASA Astrophysics Data System (ADS)

    Gerlach, Bernd; Ehinger, Markus; Raue, Hans Knut; Seiler, René

    2005-07-01

    Magnetic bearing reaction wheels provide a number of interesting advantages over ball bearing wheels. They allow high-speed operation with minimum loss torque and generate substantially less micro-vibrations. However, they require dedicated, demanding control electronics. A conroller based on a Digital Signal Processor has been developed. The controller was tested with an 87 Nms wheel prototype equipped with a magnetic bearing allowing active control in five axes. The wheel provides low-noise operation from 0 to 8000 rpm with a rotor gimballing capability of up to ±1.7°. The paper reviews the design principles and presents relevant test results, e.g. regarding the active suppression of micro-vibrations.

  14. Selection of sampling rate for digital control of aircrafts

    NASA Technical Reports Server (NTRS)

    Katz, P.; Powell, J. D.

    1974-01-01

    The considerations in selecting the sample rates for digital control of aircrafts are identified and evaluated using the optimal discrete method. A high performance aircraft model which includes a bending mode and wind gusts was studied. The following factors which influence the selection of the sampling rates were identified: (1) the time and roughness response to control inputs; (2) the response to external disturbances; and (3) the sensitivity to variations of parameters. It was found that the time response to a control input and the response to external disturbances limit the selection of the sampling rate. The optimal discrete regulator, the steady state Kalman filter, and the mean response to external disturbances are calculated.

  15. Direct brain control and communication in paralysis.

    PubMed

    Birbaumer, Niels; Gallegos-Ayala, Guillermo; Wildgruber, Moritz; Silvoni, Stefano; Soekadar, Surjo R

    2014-01-01

    Despite considerable growth in the field of brain-computer or brain-machine interface (BCI/BMI) research reflected in several hundred publications each year, little progress was made to enable patients in complete locked-in state (CLIS) to reliably communicate using their brain activity. Independent of the invasiveness of the BCI systems tested, no sustained direct brain control and communication was demonstrated in a patient in CLIS so far. This suggested a more fundamental theoretical problem of learning and attention in brain communication with BCI/BMI, formulated in the extinction-of-thought hypothesis. While operant conditioning and goal-directed thinking seems impaired in complete paralysis, classical conditioning of brain responses might represent the only alternative. First experimental studies in CLIS using semantic conditioning support this assumption. Evidence that quality-of-life in locked-in-state is not as limited and poor as generally believed draise doubts that "patient wills" or "advanced directives"signed long-before the locked-in-state are useful. On the contrary, they might be used as an excuse to shorten anticipated long periods of care for these patients avoiding associated financial and social burdens. Current state and availability of BCI/BMI systems urge a broader societal discourse on the pressing ethical challenges associated with the advancements in neurotechnology and BCI/BMI research.

  16. Environmental controls: Market incentives v. direct regulation

    SciTech Connect

    Kosobud, R.F.; Atallah, D.S.

    1996-12-31

    Cap-and-trade environmental markets, where the commodities are tradable pollution rights, are being introduced in several closely watched applications as a potentially more cost-effective way of cleaning up the environment than direct or command-and-control (CAC) regulation. In this study, we examine the evidence on control cost savings provided by price and transactions data from the first few years of activity in two markets designed to reduce atmospheric pollution. Some observers of both markets have argued that prices for tradable permits lower than expected, and transactions fewer than expected, are evidence that the markets are not achieving the hoped for savings. It was found, on the contrary, that observed prices point toward more flexible and improved pollution control choices and that the number of transactions has been steadily increasing as market incentives are incorporated into enterprise decisions. These new markets during their first few years are generating, according to our estimates, control cost savings in the neighborhood of one to two billion dollars annually. However, there is evidence that the markets have not yet reached their full potential. In the course of this study, several obstacles to market performance were found that are worthy of attention by policy makers. 13 refs., 4 figs., 1 tab.

  17. 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).

  18. Field-programmable beam reconfiguring based on digitally-controlled coding metasurface

    PubMed Central

    Wan, Xiang; Qi, Mei Qing; Chen, Tian Yi; Cui, Tie Jun

    2016-01-01

    Digital phase shifters have been applied in traditional phased array antennas to realize beam steering. However, the phase shifter deals with the phase of the induced current; hence, it has to be in the path of each element of the antenna array, making the phased array antennas very expensive. Metamaterials and/or metasurfaces enable the direct modulation of electromagnetic waves by designing subwavelength structures, which opens a new way to control the beam scanning. Here, we present a direct digital mechanism to control the scattered electromagnetic waves using coding metasurface, in which each unit cell loads a pin diode to produce binary coding states of “1” and “0”. Through data lines, the instant communications are established between the coding metasurface and the internal memory of field-programmable gate arrays (FPGA). Thus, we realize the digital modulation of electromagnetic waves, from which we present the field-programmable reflective antenna with good measurement performance. The proposed mechanism and functional device have great application potential in new-concept radar and communication systems. PMID:26861110

  19. Field-programmable beam reconfiguring based on digitally-controlled coding metasurface

    NASA Astrophysics Data System (ADS)

    Wan, Xiang; Qi, Mei Qing; Chen, Tian Yi; Cui, Tie Jun

    2016-02-01

    Digital phase shifters have been applied in traditional phased array antennas to realize beam steering. However, the phase shifter deals with the phase of the induced current; hence, it has to be in the path of each element of the antenna array, making the phased array antennas very expensive. Metamaterials and/or metasurfaces enable the direct modulation of electromagnetic waves by designing subwavelength structures, which opens a new way to control the beam scanning. Here, we present a direct digital mechanism to control the scattered electromagnetic waves using coding metasurface, in which each unit cell loads a pin diode to produce binary coding states of “1” and “0”. Through data lines, the instant communications are established between the coding metasurface and the internal memory of field-programmable gate arrays (FPGA). Thus, we realize the digital modulation of electromagnetic waves, from which we present the field-programmable reflective antenna with good measurement performance. The proposed mechanism and functional device have great application potential in new-concept radar and communication systems.

  20. Digital Control Technologies for Modular DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Button, Robert M.; Kascak, Peter E.; Lebron-Velilla, Ramon

    2002-01-01

    Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.

  1. Crystal Phase Quantum Well Emission with Digital Control.

    PubMed

    Assali, S; Lähnemann, J; Vu, T T T; Jöns, K D; Gagliano, L; Verheijen, M A; Akopian, N; Bakkers, E P A M; Haverkort, J E M

    2017-09-18

    One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc-blende (ZB) and wurtzite (WZ) phases. Such a crystal phase switching results in the formation of crystal phase quantum wells (CPQWs) and quantum dots (CPQDs). For GaP CPQWs, the inherent electric fields due to the discontinuity of the spontaneous polarization at the WZ/ZB junctions lead to the confinement of both types of charge carriers at the opposite interfaces of the WZ/ZB/WZ structure. This confinement leads to a novel type of transition across a ZB flat plate barrier. Here, we show digital tuning of the visible emission of WZ/ZB/WZ CPQWs in a GaP nanowire by changing the thickness of the ZB barrier. The energy spacing between the sharp emission lines is uniform and is defined by the addition of single ZB monolayers. The controlled growth of identical quantum wells with atomically flat interfaces at predefined positions featuring digitally tunable discrete emission energies may provide a new route to further advance entangled photons in solid state quantum systems.

  2. Digital flight control software design requirements. [for space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The objective of the integrated digital flight control system is to provide rotational and translational control of the space shuttle orbiter in all phases of flight: from launch ascent through orbit to entry and touchdown, and during powered horizontal flights. The program provides a versatile control system structure while maintaining uniform communications with other programs, sensors, and control effects by using an executive routine/function subroutine format. The program reads all external variables at a single point, copies them into its dedicated storage, and then calls the required subroutines in the proper sequence. As a result, the flight control program is largely independent of other programs in the GN and C computer complex and is equally insensitive to the characteristics of the processor configuration. The integrated structure of the control system and the DFCS executive routine which embodies that structure are described. The specific estimation and control algorithms used in the various mission phases are shown. Attitude maneuver routines that interface with the DFCS are also described.

  3. Integrated Digital Flight Control System for the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The objectives of the integrated digital flight control system (DFCS) is to provide rotational and translational control of the space shuttle orbiter in all phases of flight: from launch ascent through orbit to entry and touchdown, and during powered horizontal flights. The program provides a versatile control system structure while maintaining uniform communications with other programs, sensors, and control effectors by using an executive routine/functional subroutine format. The program reads all external variables at a single point, copies them into its dedicated storage, and then calls the required subroutines in the proper sequence. As a result, the flight control program is largely independent of other programs in the computer complex and is equally insensitive to characteristics of the processor configuration. The integrated structure is described of the control system and the DFCS executive routine which embodies that structure. The input and output, including jet selection are included. Specific estimation and control algorithm are shown for the various mission phases: cruise (including horizontal powered flight), entry, on-orbit, and boost. Attitude maneuver routines that interface with the DFCS are included.

  4. Digital radiography system using a new direct-detection flat panel detector and its system performance

    NASA Astrophysics Data System (ADS)

    Park, Jong-Hwan; Kang, Won-Suk; Shin, Byung-Su; Kang, Hyun-Seung

    2009-02-01

    We developed a digital radiography (DR) system using a new amorphous selenium (a-Se) based direct-detection flatpanel detector which has a pixel pitch of 0.168mm, a fill factor of 83%, and a total active imaging area is 17"×17". Our new system consists of an X-ray generator, two flat-panel detectors, an X-ray tube, a bucky stand, a bucky table, a control box, an image processing unit and another component. The performance of this imaging system has been measured and compared with that of our previous system used an a-Se based flat-panel detector, however, which has a pixel pitch of 0.139mm, a fill factor of 82% and a total active imaging area of 14"×17". In order to evaluate the system performance quantitatively, the modulation transfer function (MTF), detective quantum efficiency (DQE) and noise power spectrum (NPS) were measured. At 3.0 lp./mm, the measured MTF was 56%, and DQE were 25% approximately for a new flat-panel detector. In case of the previously used flat-panel detector, the MTF and DQE at 3.0 lp./mm were 75% and 12%, respectively. The MTF of a new flat-panel detector was lower than that of a previous detector, however DQE of a new detector was higher than that of a previous detector at whole spatial frequency region. In conclusion, our new DR system is capable of providing good image quality in aspect of the physical characteristics although the MTF is relatively lower than previously developed system.

  5. A quality control system for digital elevation data

    NASA Astrophysics Data System (ADS)

    Knudsen, Thomas; Kokkendorf, Simon; Flatman, Andrew; Nielsen, Thorbjørn; Rosenkranz, Brigitte; Keller, Kristian

    2015-04-01

    In connection with the introduction of a new version of the Danish national coverage Digital Elevation Model (DK-DEM), the Danish Geodata Agency has developed a comprehensive quality control (QC) and metadata production (MP) system for LiDAR point cloud data. The architecture of the system reflects its origin in a national mapping organization where raw data deliveries are typically outsourced to external suppliers. It also reflects a design decision of aiming at, whenever conceivable, doing full spatial coverage tests, rather than scattered sample checks. Hence, the QC procedure is split in two phases: A reception phase and an acceptance phase. The primary aim of the reception phase is to do a quick assessment of things that can typically go wrong, and which are relatively simple to check: Data coverage, data density, strip adjustment. If a data delivery passes the reception phase, the QC continues with the acceptance phase, which checks five different aspects of the point cloud data: Vertical accuracy Vertical precision Horizontal accuracy Horizontal precision Point classification correctness The vertical descriptors are comparatively simple to measure: The vertical accuracy is checked by direct comparison with previously surveyed patches. The vertical precision is derived from the observed variance on well defined flat surface patches. These patches are automatically derived from the road centerlines registered in FOT, the official Danish map data base. The horizontal descriptors are less straightforward to measure, since potential reference material for direct comparison is typically expected to be less accurate than the LiDAR data. The solution selected is to compare photogrammetrically derived roof centerlines from FOT with LiDAR derived roof centerlines. These are constructed by taking the 3D Hough transform of a point cloud patch defined by the photogrammetrical roof polygon. The LiDAR derived roof centerline is then the intersection line of the two primary

  6. Direct Digital Control of HVAC (Heating, Ventilating, and Air Conditioning).

    DTIC Science & Technology

    1985-01-01

    temperature sensors . The preferred humidity sensor is the modern thin - film solid state device. Pressure sensors are usually based on a...systems have an electrical output. The temperature sensors are usually one 28 of three types: thermistor , resistance- temperature devices (RTDs), or... thin - film capacitive type. Pressure sensors . Pressure sensors are used in HVAC systems in several applications, the most common being

  7. Antenna Digital Control for the Directed Mirror Antenna Radar (DMAR).

    DTIC Science & Technology

    1983-02-15

    increased . However, at present non linear gain is set to zero. The desired angular rate is also fed along a feed forward path through the gain Cvff and...amplitudes of the sinewaves into both axes were increased to 5 degrees. Tests 16 was the same as Test 15 except that the rate for the conical scan was...centered on the "dish’ but is located just behind it. Encoders and tachometers located on each of the gimbals measure angle and angular rate . Motion of the

  8. Worldwide survey of direct-to-listener digital audio delivery systems development since WARC-1992

    NASA Technical Reports Server (NTRS)

    Messer, Dion D.

    1993-01-01

    Each country was allocated frequency band(s) for direct-to-listener digital audio broadcasting at WARC-92. These allocations were near 1500, 2300, and 2600 MHz. In addition, some countries are encouraging the development of digital audio broadcasting services for terrestrial delivery only in the VHF bands (at frequencies from roughly 50 to 300 MHz) and in the medium-wave broadcasting band (AM band) (from roughly 0.5 to 1.7 MHz). The development activity increase was explosive. Current development, as of February 1993, as it is known to the author is summarized. The information given includes the following characteristics, as appropriate, for each planned system: coverage areas, audio quality, number of audio channels, delivery via satellite/terrestrial or both, carrier frequency bands, modulation methods, source coding, and channel coding. Most proponents claim that they will be operational in 3 or 4 years.

  9. Grid artifact reduction for direct digital radiography detectors based on rotated stationary grids with homomorphic filtering

    SciTech Connect

    Kim, Dong Sik; Lee, Sanggyun

    2013-06-15

    Purpose: Grid artifacts are caused when using the antiscatter grid in obtaining digital x-ray images. In this paper, research on grid artifact reduction techniques is conducted especially for the direct detectors, which are based on amorphous selenium. Methods: In order to analyze and reduce the grid artifacts, the authors consider a multiplicative grid image model and propose a homomorphic filtering technique. For minimal damage due to filters, which are used to suppress the grid artifacts, rotated grids with respect to the sampling direction are employed, and min-max optimization problems for searching optimal grid frequencies and angles for given sampling frequencies are established. The authors then propose algorithms for the grid artifact reduction based on the band-stop filters as well as low-pass filters. Results: The proposed algorithms are experimentally tested for digital x-ray images, which are obtained from direct detectors with the rotated grids, and are compared with other algorithms. It is shown that the proposed algorithms can successfully reduce the grid artifacts for direct detectors. Conclusions: By employing the homomorphic filtering technique, the authors can considerably suppress the strong grid artifacts with relatively narrow-bandwidth filters compared to the normal filtering case. Using rotated grids also significantly reduces the ringing artifact. Furthermore, for specific grid frequencies and angles, the authors can use simple homomorphic low-pass filters in the spatial domain, and thus alleviate the grid artifacts with very low implementation complexity.

  10. Impact of Smoke Exposure on Digital Instrumentation and Control

    SciTech Connect

    Tanaka, Tina J.; Nowlen, Steven P.; Korsah, Kofi; Wood, Richard T.; Antonescu, Christina E.

    2003-08-15

    Smoke can cause interruptions and upsets in active electronics. Because nuclear power plants are replacing analog with digital instrumentation and control systems, qualification guidelines for new systems are being reviewed for severe environments such as smoke and electromagnetic interference. Active digital systems, individual components, and active circuits have been exposed to smoke in a program sponsored by the U.S. Nuclear Regulatory Commission. The circuits and systems were all monitored during the smoke exposure, indicating any immediate effects of the smoke. The results of previous smoke exposure studies have been reported in various publications. The major immediate effect of smoke has been to increase leakage currents and to cause momentary upsets and failures in digital systems. This paper presents new results from conformal coatings, memory chips, and hard drive tests.The best conformal coatings were found to be polyurethane, parylene, and acrylic (when applied by dipping). Conformal coatings can reduce smoke-induced leakage currents and protect against metal loss through corrosion. However conformal coatings are typically flammable, so they do increase material flammability. Some of the low-voltage biased memory chips failed during a combination of high smoke and high humidity. Typically, smoke along with heat and humidity is expected during fire, rather than smoke alone. Thus, due to high sensitivity of digital circuits to heat and humidity, it is hypothesized that the impact of smoke may be secondary.Low-voltage (3.3-V) static random-access memory (SRAMs) were found to be the most vulnerable to smoke. Higher bias voltages decrease the likelihood of failure. Erasable programmable read-only memory (EPROMs) and nonvolatile SRAMs were very smoke tolerant. Failures of the SRAMs occurred when two conditions were present: high density of smoke and high humidity. As the high humidity was present for only part of the test, the failures were intermittent. All

  11. An implementable digital adaptive flight controller designed using stabilized single stage algorithms

    NASA Technical Reports Server (NTRS)

    Kaufman, H.; Alag, G.

    1975-01-01

    Simple mechanical linkages have not solved the many control problems associated with high performance aircraft maneuvering throughout a wide flight envelope. One procedure for retaining uniform handling qualities over such an envelope is to implement a digital adaptive controller. Towards such an implementation an explicit adaptive controller which makes direct use of on-line parameter identification, has been developed and applied to both linearized and nonlinear equations of motion for a typical fighter aircraft. This controller is composed of an on-line weighted least squares parameter identifier, a Kalman state filter, and a model following control law designed using single stage performance indices. Simulation experiments with realistic measurement noise indicate that the proposed adaptive system has the potential for on-board implementation.

  12. Stand-alone digital data storage control system including user control interface

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth D. (Inventor); Gray, David L. (Inventor)

    1994-01-01

    A storage control system includes an apparatus and method for user control of a storage interface to operate a storage medium to store data obtained by a real-time data acquisition system. Digital data received in serial format from the data acquisition system is first converted to a parallel format and then provided to the storage interface. The operation of the storage interface is controlled in accordance with instructions based on user control input from a user. Also, a user status output is displayed in accordance with storage data obtained from the storage interface. By allowing the user to control and monitor the operation of the storage interface, a stand-alone, user-controllable data storage system is provided for storing the digital data obtained by a real-time data acquisition system.

  13. Azopolymer photopatterning for directional control of angiogenesis.

    PubMed

    Fedele, Chiara; De Gregorio, Maria; Netti, Paolo A; Cavalli, Silvia; Attanasio, Chiara

    2017-09-18

    Understanding cellular behavior in response to microenvironmental stimuli is central to tissue engineering. An increasing number of reports emphasize the high sensitivity of cells to the physical characteristics of the surrounding milieu and in particular, topographical cues. In this work, we investigated the influence of dynamic topographic signal presentation on sprout formation and the possibility to obtain a space-time control over sprouting directionality without growth factors, in order to investigate the contribution of just topography in the angiogenic process. To test our hypothesis, we employed a 3D angiogenesis assay based on the use of spheroids derived from human umbilical vein endothelial cells (HUVECs). We then modulated the in situ presentation of topographical cues during early-stage angiogenesis through real-time photopatterning of an azobenzene-containing polymer, poly (Disperse Red 1 methacrylate) (pDR1m). Pattern inscription on the polymer surface was made using the focused laser of a confocal microscope. We demonstrate that during early-stage angiogenesis, sprouts followed the pattern direction, while spheroid cores acquired a polarized shape. These findings confirmed that sprout directionality was influenced by the photo-inscribed pattern, probably through contact guidance of leader cells, thus validating the proposed platform as a valuable tool for understanding complex processes involved in cell-topography interactions in multicellular systems. The complex relationship between endothelial cells and the surrounding environment that leads to formation of a newly formed vascular network during tissue repair is currently unknown. We have developed an innovative in vitro platform to study these mechanisms in a space and time controlled fashion simulating what happens during regeneration. In particular, we combine a "smart" surface, namely a polymer film, with a three-dimensional living cell aggregate. The polymer is activated by light through

  14. Spacecraft attitude control using direct model reference adaptive control

    NASA Astrophysics Data System (ADS)

    Harvey, Seth A.

    This research began in the summer of 2006. During that summer a method was developed to estimate the gravity gradient as well as the nadir vector of a Plug-and-Play [PNP] satellite. This was done based on the assumptions that there were perturbations in the satellite model that kept the satellite from knowing this information a priori. An indirect adaptive estimation scheme was used to accomplish this goal. However it is impractical to do this for each perturbation in the plant. By the very nature of PNP Satellites, there could be errors in among other things, reaction wheel mounting/orientation, star tracker location/orientation, satellite center of mass (COM), and payload location/orientation. An adaptive scheme to estimate each error is not efficient and ultimately is not the goal. The goal is to accurately control the satellite despite the numerous and possibly large errors inherent in PNP Satellite models. Instead of using indirect adaptive methods to gain precise knowledge of the plant, direct adaptive control methods will be used to overcome the errors of the plant and gain precise control of the satellite. One way of overcoming the inaccuracies of the model is to assume the spacecraft dynamics are largely unknown. A shift in philosophy was then taken from indirect adaptive methods to direct methods. Direct Reference and Model Reference Adaptive Controller [DRAC & DMRAC] are then developed that will precisely and robustly control the attitude of a PNP satellite. The benefits demonstrated by the DMRAC methodologies extend well past plug and play satellites and could be utilized in any space application.

  15. Quality control measurements for digital x-ray detectors.

    PubMed

    Marshall, N W; Mackenzie, A; Honey, I D

    2011-02-21

    This paper describes a digital radiography (DR) quality control protocol for DR detectors from the forthcoming report from the Institute of Physics and Engineering in Medicine (IPEM). The protocol was applied to a group of six identical caesium iodide (CsI) digital x-ray detectors to assess reproducibility of methods, while four further detectors were assessed to examine the wider applicability. Twelve images with minimal spatial frequency processing are required, from which the detector response, lag, modulation transfer function (MTF), normalized noise power spectrum (NNPS) and threshold contrast-detail (c-d) detectability are calculated. The x-ray spectrum used was 70 kV and 1 mm added copper filtration, with a target detector air kerma of 2.5 µGy for the NNPS and c-d results. In order to compare detector performance with previous imaging technology, c-d data from four screen/film systems were also acquired, at a target optical density of 1.5 and an average detector air kerma of 2.56 µGy. The DR detector images were typically acquired in 20 min, with a further 45 min required for image transfer and analysis. The average spatial frequency for the 50% point of the MTF for six identical detectors was 1.29 mm(-1) ± 0.05 (3.9% coefficient of variation (cov)). The air kerma set for the six systems was 2.57 µGy ± 0.13 (5.0% cov) and the NNPS at this air kerma was 1.42 × 10(-5) mm(2) (6.5% cov). The detective quantum efficiency (DQE) measured for the six identical detectors was 0.60 at 0.5 mm(-1), with a maximum cov of 10% at 2.9 mm(-1), while the average DQE was 0.56 at 0.5 mm(-1) for three CsI detectors from three different manufacturers. Comparable c-d performance was found for these detectors (5.9% cov) with an average threshold contrast of 0.46% for 11 mm circular discs. The average threshold contrast for the S/F systems was 0.70% at 11 mm, indicating superior imaging performance for the digital systems. The protocol was found to be quick, reproducible and

  16. Quality control measurements for digital x-ray detectors

    NASA Astrophysics Data System (ADS)

    Marshall, N. W.; Mackenzie, A.; Honey, I. D.

    2011-02-01

    This paper describes a digital radiography (DR) quality control protocol for DR detectors from the forthcoming report from the Institute of Physics and Engineering in Medicine (IPEM). The protocol was applied to a group of six identical caesium iodide (CsI) digital x-ray detectors to assess reproducibility of methods, while four further detectors were assessed to examine the wider applicability. Twelve images with minimal spatial frequency processing are required, from which the detector response, lag, modulation transfer function (MTF), normalized noise power spectrum (NNPS) and threshold contrast-detail (c-d) detectability are calculated. The x-ray spectrum used was 70 kV and 1 mm added copper filtration, with a target detector air kerma of 2.5 µGy for the NNPS and c-d results. In order to compare detector performance with previous imaging technology, c-d data from four screen/film systems were also acquired, at a target optical density of 1.5 and an average detector air kerma of 2.56 µGy. The DR detector images were typically acquired in 20 min, with a further 45 min required for image transfer and analysis. The average spatial frequency for the 50% point of the MTF for six identical detectors was 1.29 mm-1 ± 0.05 (3.9% coefficient of variation (cov)). The air kerma set for the six systems was 2.57 µGy ± 0.13 (5.0% cov) and the NNPS at this air kerma was 1.42 × 10-5 mm2 (6.5% cov). The detective quantum efficiency (DQE) measured for the six identical detectors was 0.60 at 0.5 mm-1, with a maximum cov of 10% at 2.9 mm-1, while the average DQE was 0.56 at 0.5 mm-1 for three CsI detectors from three different manufacturers. Comparable c-d performance was found for these detectors (5.9% cov) with an average threshold contrast of 0.46% for 11 mm circular discs. The average threshold contrast for the S/F systems was 0.70% at 11 mm, indicating superior imaging performance for the digital systems. The protocol was found to be quick, reproducible and gave an in

  17. Formulation of a strategy for monitoring control integrity in critical digital control systems

    NASA Technical Reports Server (NTRS)

    Belcastro, Celeste M.; Fischl, Robert; Kam, Moshe

    1991-01-01

    Advanced aircraft will require flight critical computer systems for stability augmentation as well as guidance and control that must perform reliably in adverse, as well as nominal, operating environments. Digital system upset is a functional error mode that can occur in electromagnetically harsh environments, involves no component damage, can occur simultaneously in all channels of a redundant control computer, and is software dependent. A strategy is presented for dynamic upset detection to be used in the evaluation of critical digital controllers during the design and/or validation phases of development. Critical controllers must be able to be used in adverse environments that result from disturbances caused by an electromagnetic source such as lightning, high intensity radiated field (HIRF), and nuclear electromagnetic pulses (NEMP). The upset detection strategy presented provides dynamic monitoring of a given control computer for degraded functional integrity that can result from redundancy management errors and control command calculation error that could occur in an electromagnetically harsh operating environment. The use is discussed of Kalman filtering, data fusion, and decision theory in monitoring a given digital controller for control calculation errors, redundancy management errors, and control effectiveness.

  18. Performances improvements and torque ripple minimization for VSI fed induction machine with direct control torque.

    PubMed

    Abdelli, R; Rekioua, D; Rekioua, T

    2011-04-01

    This paper describes a torque ripple reduction technique with constant switching frequency for direct torque control (DTC) of an induction motor (IM). This method enables a minimum torque ripple control. In order to obtain a constant switching frequency and hence a torque ripple reduction, we propose a control technique for IM. It consists of controlling directly the electromagnetic torque by using a modulated hysteresis controller. The design methodology is based on space vector modulation (SVM) of electrical machines with digital vector control. MATLAB simulations supported with experimental study are used. The simulation and experimental results of this proposed algorithm show an adequate dynamic to IM; however, the research can be extended to include synchronous motors as well. The implementation of the proposed algorithm is described. It doesn't require any PI controller in the torque control loop. The hardware inverter is controlled digitally using a Texas Instruments TMS320F240 digital signal processor (DSP) with composed C codes for generating the required references. The results obtained from simulation and experiments confirmed the feasibility of the proposed strategy compared to the conventional one.

  19. Applying Human Factors Evaluation and Design Guidance to a Nuclear Power Plant Digital Control System

    SciTech Connect

    Thomas Ulrich; Ronald Boring; William Phoenix; Emily Dehority; Tim Whiting; Jonathan Morrell; Rhett Backstrom

    2012-08-01

    The United States (U.S.) nuclear industry, like similar process control industries, has moved toward upgrading its control rooms. The upgraded control rooms typically feature digital control system (DCS) displays embedded in the panels. These displays gather information from the system and represent that information on a single display surface. In this manner, the DCS combines many previously separate analog indicators and controls into a single digital display, whereby the operators can toggle between multiple windows to monitor and control different aspects of the plant. The design of the DCS depends on the function of the system it monitors, but revolves around presenting the information most germane to an operator at any point in time. DCSs require a carefully designed human system interface. This report centers on redesigning existing DCS displays for an example chemical volume control system (CVCS) at a U.S. nuclear power plant. The crucial nature of the CVCS, which controls coolant levels and boration in the primary system, requires a thorough human factors evaluation of its supporting DCS. The initial digital controls being developed for the DCSs tend to directly mimic the former analog controls. There are, however, unique operator interactions with a digital vs. analog interface, and the differences have not always been carefully factored in the translation of an analog interface to a replacement DCS. To ensure safety, efficiency, and usability of the emerging DCSs, a human factors usability evaluation was conducted on a CVCS DCS currently being used and refined at an existing U.S. nuclear power plant. Subject matter experts from process control engineering, software development, and human factors evaluated the DCS displays to document potential usability issues and propose design recommendations. The evaluation yielded 167 potential usability issues with the DCS. These issues should not be considered operator performance problems but rather opportunities

  20. A radio-frequency source using direct digital synthesis and field programmable gate array for nuclear magnetic resonance.

    PubMed

    Liang, Xiao; Weimin, Wang

    2009-12-01

    A radio-frequency (rf) source for nuclear magnetic resonance (NMR) is described. With the application of direct digital synthesis (DDS), the rf source has the ability to yield rf pulses with short switching time and high resolution in frequency and phase. To facilitate the generation of a soft pulse, a field programmable gate array (FPGA) cooperating with a pulse programmer is used as the auxiliary controller of the DDS chip. Triggered by the pulse programmer, the FPGA automatically controls the DDS to generate soft pulse according to predefined parameters, and the operation mode of the pulse programmer is optimized. The rf source is suitable for being used as transmitter in low-field (<1 T) NMR applications, for example, magnetic resonance imaging and relaxation measurement. As a compact and low-cost module, the rf source is of general use for constructing low-field NMR spectrometer.

  1. A novel approach for using polyphase filter bank in directly digital RF conversion from RF to baseband

    NASA Astrophysics Data System (ADS)

    Zhang, Deying; Jiang, Qin; Ahmed, Mohiuddin

    2012-05-01

    Software defined radio (SDR) hardware platform is in high demand for ultra-wideband digital EW receiver to carry out different mission requirements. Due to the limitations of current Analog-to-Digital conversion (ADC) techniques, the ideal receiver structure of SDR, with digital RF frequency conversion, cannot be achieved. In this article, a new channelization technique called ADC polyphase fast Fourier transformation (ADC PFFT) filter bank channelization is demonstrated. The key concept is to separate the speed at which the two functional units of an ADC - the sample and hold and the quantizer - operate. The sample and hold unit operates at the sampling frequency fs and the quantizer (the speed limiting factor in ADCs) can operate at a much slower rate, fs/M, where M is the decimation factor for digital filter bank. By integrated this ADC PFFT technique in ultra-wideband digital channelized EW receivers, directly digital RF down conversion can be achieved. With the ADC PFFT channelization for RF down conversion and polyphase FFT channelization for IF down conversion, 2-18 GHz frequency coverage can be accomplished in such ultra-wideband digital channelized EW receivers without the requirement of EW receivers being time-shared among outputs from many subbands due to bandwidth limitation in digital IF channelized EW receivers. Because the frequency down conversion from RF to BB are all processed digitally, issues such as image rejection and I/Q imbalance due to analog mixing will be eliminated in the ultrawideband digital channelized EW receivers.

  2. Self-Diagnostics Digitally Controlled Pacemaker/Defibrillators: A Design Plan for Incorporating Diagnostics and Digital Control in the schema of a Pacemaker/Defibrillator Design

    DTIC Science & Technology

    2005-09-01

    This research addresses the need for a pacemaker/ defibrillator that could perform an automatic system self-diagnostics check to assure operational...architecture of a system to store and retrieve digital/wireless communication information from a pacemaker/ defibrillator , or other device, and to alert medical...Digitally Controlled Pacemaker/ Defibrillator Device. Applications of the SDDCPDD design concept for military missions are explored.

  3. Evaluation of a digital dispenser for direct curve dilutions in a vaccine potency assay.

    PubMed

    Roselle, Christopher; Whitehouse, Dana; Follmer, Thy; Ansbro, Fran; Bouaraphan, Silikhone; Guan, Liming; Wang, Sha-Ke; Shank-Retzlaff, Mary; Verch, Thorsten

    2017-03-01

    Dilutions are a common source of analytical error, both in terms of accuracy and precision, and a common source of analyst mistakes. When serial dilutions are used, errors compound, even when employing laboratory automation. Direct point dilutions instead of serial dilutions can reduce error but is often impractical as they require either large diluent volumes or very small sample volumes when performed with traditional liquid handling equipment. We evaluated preparation of dilution curves using a picoliter digital dispenser, the HP, Inc. / TECAN D300 which is capable of accurately delivering picoliter volumes directly into sample wells filled with assay diluent. Dilution linearity and variability of the direct dilutions were similar to or less than those generated with a traditional liquid handler as measured using a fluorophore assay and an ELISA used to measure vaccine potency. Minimum concentrations for detergent in the dispensed sample were identified but no correlation with detergent characteristics was observed. The tolerance to protein in the sample was evaluated as well with up to 5% BSA having no impact on dispense linearity and precision. We found the digital dispenser to reduce automation complexity while maintaining or improving assay performance in addition to facilitating complex plate lay-outs.

  4. Design and Evaluation of a Digital Flight Control System for the FROG Unmanned Aerial Vehicle

    DTIC Science & Technology

    2001-09-01

    DIGITAL FLIGHT CONTROL SYSTEM FOR THE FROG UNMANNED AERIAL VEHICLE by Christopher H. Flood September 2001 Thesis Advisor: Isaac I. Kaminer...Subtitle Design and Evaluation of a Digital Flight Control System for the FROG Unmanned Aerial Vehicle Contract Number Grant Number Program Element...REPORT TYPE AND DATES COVERED Aeronautical Engineers Thesis 4. TITLE AND SUBTITLE: Design and Evaluation of a Digital Flight Control System for

  5. Acquisition and replay systems for direct-to-digital holography and holovision

    DOEpatents

    Thomas, Clarence E.; Hanson, Gregory R.

    2003-02-25

    Improvements to the acquisition and replay systems for direct-to-digital holography and holovision are described. A method of recording an off-axis hologram includes: splitting a laser beam into an object beam and a reference beam; reflecting the reference beam from a reference beam mirror; reflecting the object beam from an illumination beamsplitter; passing the object beam through an objective lens; reflecting the object beam from an object; focusing the reference beam and the object beam at a focal plane of a digital recorder to form an off-axis hologram; digitally recording the off-axis hologram; and transforming the off-axis hologram in accordance with a Fourier transform to obtain a set of results. A method of writing an off-axis hologram includes: passing a laser beam through a spatial light modulator; and focusing the laser beam at a focal plane of a photorefractive crystal to impose a holographic diffraction grating pattern on the photorefractive crystal. A method of replaying an off-axis hologram includes: illuminating a photorefractive crystal having a holographic diffraction grating with a replay beam.

  6. Direct to Implant Reconstruction in Nipple Sparing Mastectomy: Patient Selection by Preoperative Digital Mammogram

    PubMed Central

    Angrigiani, Claudio H.; Hammond, Dennis C.; Nava, Maurizio B.; Gonzalez, Eduardo G.; Dorr, Julio C.; Gercovich, Gustavo F.; Rocco, Nicola; Rostagno, Roman L.

    2017-01-01

    Background: Digital mammography clearly distinguishes gland tissue density from the overlying nonglandular breast tissue coverage, which corresponds to the existing tissue between the skin and the superficial layer of the fascia superficialis surrounding the gland (i.e., dermis and subcutaneous fat). Preoperative digital imaging can determine the thickness of this breast tissue coverage, thus facilitating planning and reducing the rate of necrotic complications after direct to implant (DTI) reconstruction in nipple sparing mastectomy (NSM). Methods: Thirty NSMs in 22 patients with type 3 tissue coverage (subcutaneous tissue thickness of 2 cm or more) were selected for DTI reconstruction after NSM to evaluate immediate skin flap/nipple areola complex ischemic complications and patient satisfaction. Results: We experienced no wound healing problems or ischemic complications immediately after surgery in our population. Only 1 seroma was observed as a short-term complication. Quality of life and patients’ satisfaction level were optimal at 3 and 6 months follow-up, respectively. The aesthetic results have been evaluated as good/excellent in all cases. Conclusions: DTI immediate reconstruction with silicone implants following NSM appears to be a safe option in selected cases with enough tissue coverage, also providing a high level of patient satisfaction. The possibility of selecting cases for this procedure according to the preoperative digital mammogram showing more than 2 cm of superficial tissues thickness may help reducing the risk of immediate ischemic complications. PMID:28740781

  7. Optimized setup for integral refractive index direct determination applying digital holographic microscopy by reflection and transmission

    NASA Astrophysics Data System (ADS)

    Frómeta, M.; Moreno, G.; Ricardo, J.; Arias, Y.; Muramatsu, M.; Gomes, L. F.; Palácios, G.; Palácios, F.; Velázquez, H.; Valin, J. L.; Ramirez Q, L.

    2017-03-01

    In this paper the integral refractive index of a microscopic sample was directly measured by applying Digital Holographic Microscopy (DHM) capturing transmission and reflection holograms simultaneously, of the same sample's region, using Mach-Zehnder and Michelson micro interferometers for transmission and reflection holograms capture and modeling the 3D sample in a medium of known refractive index nm. The system was calibrated using standard polystyrene sphere immersed in water with known diameter and refractive index, and the method was applied for erythrocyte integral refractive index determination. The results are in accordance with predicted, the measurements error of the order of ± 0.005 in absolute values.

  8. Complex object wave direct extraction method in off-axis digital holography.

    PubMed

    Kim, Daesuk; Magnusson, Robert; Jin, Moonseob; Lee, Jaejong; Chegal, Won

    2013-02-11

    Off-axis digital holography generally uses a 2D-FFT based spatial filtering method to extract the complex object wave from an off-axis hologram. In this paper, we describe a novel single exposure complex object wave extraction method which can provide a faster solution than the FFT based spatial filtering approach while maintaining the reconstructed phase image quality. And also, we show that the proposed direct filtering scheme can provide more robust filtering capability to the off-axis spatial carrier frequency variation than the spatial filtering method.

  9. Direct to Digital Holography for Semiconductor Wafer Defect Detection and Review

    SciTech Connect

    ThomasJr., C. E.; Bahm, Tracy M.; Baylor, Larry R; Bingham, Philip R.; Burns, Steven W.; Chidley, Matthew D; Dai, Xiaolong; Delahanty, Robert J.; Doti, Christopher J.; El-Khashab, Ayman; Fisher, Robert L.; Gilbert, Judd M.; Cui, Hongtao; Goddard Jr, James Samuel; Hanson, Gregory R; Hickson, Joel D.; Hunt, Martin A.; Hylton, Kathy W; John, George C.; Jones, Michael L.; McDonald, Kenneth R.; Mayo, Michael W.; McMackin, Ian; Patek, David; Price, John H.; Rasmussen, David A; Schaefer, Louis J.; Scheidt, Thomas R.; Schulze, Mark A.; Schumaker, Philip D.; Shen, Bichuan; Smith, Randall G.; Su, Allen N.; Tobin Jr, Kenneth William; Usry, William R.; Voelkl, Edgar; Weber, Karsten S.; Jones, Paul G.; Owen, Robert W.

    2002-01-01

    A method for recording true holograms (not holographic interferometry) directly to a digital video medium in a single image has been invented. This technology makes the amplitude and phase for every pixel of the target object wave available. Since phase is proportional to wavelength, this makes high-resolution metrology an implicit part of the holographic recording. Measurements of phase can be made to one hundredth or even one thousandth of a wavelength, so the technology is attractive for finding defects on semiconductor wafers, where feature sizes are now smaller than the wavelength of even deep ultra-violet light.

  10. Digital phase-locked-loop speed sensor for accuracy improvement in analog speed controls. [feedback control and integrated circuits

    NASA Technical Reports Server (NTRS)

    Birchenough, A. G.

    1975-01-01

    A digital speed control that can be combined with a proportional analog controller is described. The stability and transient response of the analog controller were retained and combined with the long-term accuracy of a crystal-controlled integral controller. A relatively simple circuit was developed by using phase-locked-loop techniques and total error storage. The integral digital controller will maintain speed control accuracy equal to that of the crystal reference oscillator.

  11. Effect of clock jitter on plasma density measurements relying on direct digital demodulation techniques

    NASA Astrophysics Data System (ADS)

    Hamming, B. W.; Colio, R. A.; Finkenthal, D. F.; van Zeeland, M. A.; Deterly, T. M.

    2011-10-01

    Real-time measurement of plasma density is essential to effective closed-loop plasma control systems in fusion-type reactors. The DIII-D tokamak currently employs a Michelson-type interferometer in combination with heterodyned lasers to make real-time density measurements utilizing embedded digital signal processing (DSP) techniques. This technique relies on high-speed analog-to-digital converters clocking at four times the 40 MHz reference frequency, and clock jitter becomes a critical source of noise in the measurement indistinguishable from phase noise of the interferometer signals. We present a study of the effect of clock jitter on system noise and recommendations for improvement. Work supported in part by US DOE under DE-FC02-04ER54698 and the National Undergraduate Fellowship in Fusion Science and Engineering.

  12. Usability evaluation of remote controllers for digital television receivers

    NASA Astrophysics Data System (ADS)

    Komine, Kazuteru; Hiruma, Nobuyuki; Ishihara, Tatsuya; Makino, Eiji; Tsuda, Takao; Ito, Takayuki; Isono, Haruo

    2000-06-01

    In order to develop a useful and ergonomically attractive remote controller for ISDB (Integrated Services Digital Broadcasting), which will begin very soon in Japan, we performed experiments with elderly and young subjects to evaluate the usability and the training effects of four types of remote controller: a button type, a trackball, a touch panel and a voice recognition system. We set the subjects the task of selecting an icon on a HDTV monitor as quickly and as accurately as possible using each remote controller. Semantic differential and ranked order questionnaire surveys were also conducted, and these results were analyzed statistically. The results showed that the trackball type was the most preferred, with no major differences in preference among the other three types especially for elderly subjects. From the analyses of the questionnaire surveys and operation time, we conclude that the reasons for the rankings obtained are as follows: Users preferred devices which they could operate without having to look down; Users preferred devices with which there was a significant learning effect in a relatively short period. It is considered that these are necessary conditions for an ergonomically attractive remote controller which users will want to use.

  13. 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.

  14. Markov reliability models for digital flight control systems

    NASA Technical Reports Server (NTRS)

    Mcgough, John; Reibman, Andrew; Trivedi, Kishor

    1989-01-01

    The reliability of digital flight control systems can often be accurately predicted using Markov chain models. The cost of numerical solution depends on a model's size and stiffness. Acyclic Markov models, a useful special case, are particularly amenable to efficient numerical solution. Even in the general case, instantaneous coverage approximation allows the reduction of some cyclic models to more readily solvable acyclic models. After considering the solution of single-phase models, the discussion is extended to phased-mission models. Phased-mission reliability models are classified based on the state restoration behavior that occurs between mission phases. As an economical approach for the solution of such models, the mean failure rate solution method is introduced. A numerical example is used to show the influence of fault-model parameters and interphase behavior on system unreliability.

  15. Review of innovations in digital health technology to promote weight control.

    PubMed

    Thomas, J Graham; Bond, Dale S

    2014-01-01

    Advances in technology have contributed to the obesity epidemic and worsened health by reducing opportunities for physical activity and by the proliferation of inexpensive calorie-dense foods. However, much of the same technology can be used to counter these troublesome trends by fostering the development and maintenance of healthy eating and physical activity habits. In contrast to intensive face-to-face treatments, technology-based interventions also have the potential to reach large numbers of individuals at low cost. The purpose of this review is to discuss studies in which digital technology has been used for behavioral weight control, report on advances in consumer technology that are widely adopted but insufficiently tested, and explore potential future directions for both. Web-based, mobile (eg, smartphone), virtual reality, and gaming technologies are the focus of discussion. The best evidence exists to support the use of digital technology for self-monitoring of weight-related behaviors and outcomes. However, studies are underway that will provide additional, important information regarding how best to apply digital technology for behavioral weight control.

  16. A Digital Motion Control System for Large Telescopes

    NASA Astrophysics Data System (ADS)

    Hunter, T. R.; Wilson, R. W.; Kimberk, R.; Leiker, P. S.

    2001-05-01

    We have designed and programmed a digital motion control system for large telescopes, in particular, the 6-meter antennas of the Submillimeter Array on Mauna Kea. The system consists of a single robust, high-reliability microcontroller board which implements a two-axis velocity servo while monitoring and responding to critical safety parameters. Excellent tracking performance has been achieved with this system (0.3 arcsecond RMS at sidereal rate). The 24x24 centimeter four-layer printed circuit board contains a multitude of hardware devices: 40 digital inputs (for limit switches and fault indicators), 32 digital outputs (to enable/disable motor amplifiers and brakes), a quad 22-bit ADC (to read the motor tachometers), four 16-bit DACs (that provide torque signals to the motor amplifiers), a 32-LED status panel, a serial port to the LynxOS PowerPC antenna computer (RS422/460kbps), a serial port to the Palm Vx handpaddle (RS232/115kbps), and serial links to the low-resolution absolute encoders on the azimuth and elevation axes. Each section of the board employs independent ground planes and power supplies, with optical isolation on all I/O channels. The processor is an Intel 80C196KC 16-bit microcontroller running at 20MHz on an 8-bit bus. This processor executes an interrupt-driven, scheduler-based software system written in C and assembled into an EPROM with user-accessible variables stored in NVSRAM. Under normal operation, velocity update requests arrive at 100Hz from the position-loop servo process running independently on the antenna computer. A variety of telescope safety checks are performed at 279Hz including routine servicing of a 6 millisecond watchdog timer. Additional ADCs onboard the microcontroller monitor the winding temperature and current in the brushless three-phase drive motors. The PID servo gains can be dynamically changed in software. Calibration factors and software filters can be applied to the tachometer readings prior to the application of

  17. The Digital Motion Control System for the Submillimeter Array Antennas

    NASA Astrophysics Data System (ADS)

    Hunter, T. R.; Wilson, R. W.; Kimberk, R.; Leiker, P. S.; Patel, N. A.; Blundell, R.; Christensen, R. D.; Diven, A. R.; Maute, J.; Plante, R. J.; Riddle, P.; Young, K. H.

    2013-09-01

    We describe the design and performance of the digital servo and motion control system for the 6-meter parabolic antennas of the Submillimeter Array (SMA) on Mauna Kea, Hawaii. The system is divided into three nested layers operating at a different, appropriate bandwidth. (1) A rack-mounted, real-time Unix system runs the position loop which reads the high resolution azimuth and elevation encoders and sends velocity and acceleration commands at 100 Hz to a custom-designed servo control board (SCB). (2) The microcontroller-based SCB reads the motor axis tachometers and implements the velocity loop by sending torque commands to the motor amplifiers at 558 Hz. (3) The motor amplifiers implement the torque loop by monitoring and sending current to the three-phase brushless drive motors at 20 kHz. The velocity loop uses a traditional proportional-integral-derivative (PID) control algorithm, while the position loop uses only a proportional term and implements a command shaper based on the Gauss error function. Calibration factors and software filters are applied to the tachometer feedback prior to the application of the servo gains in the torque computations. All of these parameters are remotely adjustable in the software. The three layers of the control system monitor each other and are capable of shutting down the system safely if a failure or anomaly occurs. The Unix system continuously relays the antenna status to the central observatory computer via reflective memory. In each antenna, a Palm Vx hand controller displays the complete system status and allows full local control of the drives in an intuitive touchscreen user interface. The hand controller can also be connected outside the cabin, a major convenience during the frequent reconfigurations of the interferometer. Excellent tracking performance ( 0.3‧‧ rms) is achieved with this system. It has been in reliable operation on 8 antennas for over 10 years and has required minimal maintenance.

  18. Integument pattern formation involves genetic and epigenetic controls: feather arrays simulated by digital hormone models.

    PubMed

    Jiang, Ting-Xin; Widelitz, Randall B; Shen, Wei-Min; Will, Peter; Wu, Da-Yu; Lin, Chih-Min; Jung, Han-Sung; Chuong, Cheng-Ming

    2004-01-01

    Pattern formation is a fundamental morphogenetic process. Models based on genetic and epigenetic control have been proposed but remain controversial. Here we use feather morphogenesis for further evaluation. Adhesion molecules and/or signaling molecules were first expressed homogenously in feather tracts (restrictive mode, appear earlier) or directly in bud or inter-bud regions ( de novo mode, appear later). They either activate or inhibit bud formation, but paradoxically colocalize in the bud. Using feather bud reconstitution, we showed that completely dissociated cells can reform periodic patterns without reference to previous positional codes. The patterning process has the characteristics of being self-organizing, dynamic and plastic. The final pattern is an equilibrium state reached by competition, and the number and size of buds can be altered based on cell number and activator/inhibitor ratio, respectively. We developed a Digital Hormone Model which consists of (1) competent cells without identity that move randomly in a space, (2) extracellular signaling hormones which diffuse by a reaction-diffusion mechanism and activate or inhibit cell adhesion, and (3) cells which respond with topological stochastic actions manifested as changes in cell adhesion. Based on probability, the results are cell clusters arranged in dots or stripes. Thus genetic control provides combinational molecular information which defines the properties of the cells but not the final pattern. Epigenetic control governs interactions among cells and their environment based on physical-chemical rules (such as those described in the Digital Hormone Model). Complex integument patterning is the sum of these two components of control and that is why integument patterns are usually similar but non-identical. These principles may be shared by other pattern formation processes such as barb ridge formation, fingerprints, pigmentation patterning, etc. The Digital Hormone Model can also be applied to

  19. Integument pattern formation involves genetic and epigenetic controls: feather arrays simulated by digital hormone models

    PubMed Central

    Jiang, Ting-Xin; Widelitz, Randall B.; Shen, Wei-Min; Will, Peter; Wu, Da-Yu; Lin, Chih-Min; Jung, Han-Sung; Chuong, Cheng-Ming

    2015-01-01

    Pattern formation is a fundamental morphogenetic process. Models based on genetic and epigenetic control have been proposed but remain controversial. Here we use feather morphogenesis for further evaluation. Adhesion molecules and/or signaling molecules were first expressed homogenously in feather tracts (restrictive mode, appear earlier) or directly in bud or inter-bud regions (de novo mode, appear later). They either activate or inhibit bud formation, but paradoxically co-localize in the bud. Using feather bud reconstitution, we showed that completely dissociated cells can reform periodic patterns without reference to previous positional codes. The patterning process has the characteristics of being self-organizing, dynamic and plastic. The final pattern is an equilibrium state reached by competition, and the number and size of buds can be altered based on cell number and activator/inhibitor ratio, respectively. We developed a Digital Hormone Model which consists of (1) competent cells without identity that move randomly in a space, (2) extracellular signaling hormones which diffuse by a reaction-diffusion mechanism and activate or inhibit cell adhesion, and (3) cells which respond with topological stochastic actions manifested as changes in cell adhesion. Based on probability, the results are cell clusters arranged in dots or stripes. Thus genetic control provides combinational molecular information which defines the properties of the cells but not the final pattern. Epigenetic control governs interactions among cells and their environment based on physical-chemical rules (such as those described in the Digital Hormone Model). Complex integument patterning is the sum of these two components of control and that is why integument patterns are usually similar but non-identical. These principles may be shared by other pattern formation processes such as barb ridge formation, fingerprints, pigmentation patterning, etc. The Digital Hormone Model can also be applied to

  20. Comparisons of jitter, shimmer, and signal-to-noise ratio from directly digitized versus taped voice samples.

    PubMed

    Gelfer, M P; Fendel, D M

    1995-12-01

    The purpose of this study was to compare jitter, shimmer, and signal-to-noise ratio (SNR) measures obtained from tape-recorded samples with the same measures made on directly digitized voice samples, with use of the CSpeech acoustic analysis program. Subjects included 30 young women who phonated the vowel /a/ at a comfortable pitch and loudness level. Voice samples were simultaneously recorded and digitized, and the resulting perturbation measures for the two conditions were compared. Results indicated that there were small but statistically significant differences between percent jitter, percent shimmer, and SNR calculated from taped samples compared with the same measures calculated from directly digitized samples. It was concluded that direct digitization for clinical measures of vocal perturbation was most desirable, but that taped samples could be used, if necessary, with some caution.

  1. Directional MTF measurement using sphere phantoms for a digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Lee, Changwoo; Baek, Jongduk

    2015-03-01

    The digital breast tomosynthesis (DBT) has been widely used as a diagnosis imaging modality of breast cancer because of potential for structure noise reduction, better detectability, and less breast compression. Since 3D modulation transfer function (MTF) is one of the quantitative metrics to assess the spatial resolution of medical imaging systems, it is very important to measure 3D MTF of the DBT system to evaluate the resolution performance. In order to do that, Samei et al. used sphere phantoms and applied Thornton's method to the DBT system. However, due to the limitation of Thornton's method, the low frequency drop, caused by the limited data acquisition angle and reconstruction filters, was not measured correctly. To overcome this limitation, we propose a Richardson-Lucy (RL) deconvolution based estimation method to measure the directional MTF. We reconstructed point and sphere objects using FDK algorithm within a 40⁰ data acquisition angle. The ideal 3D MTF is obtained by taking Fourier transform of the reconstructed point object, and three directions (i.e., fx-direction, fy-direction, and fxy-direction) of the ideal 3D MTF are used as a reference. To estimate the directional MTF, the plane integrals of the reconstructed and ideal sphere object were calculated and used to estimate the directional PSF using RL deconvolution technique. Finally, the directional MTF was calculated by taking Fourier transform of the estimated PSF. Compared to the previous method, the proposed method showed a good agreement with the ideal directional MTF, especially at low frequency regions.

  2. Digital control of working fluid flow rate for an OTEC plant

    SciTech Connect

    Nakamura, M.; Egashira, N.; Uehara, H.

    1986-05-01

    The role of control in operating an OTEC plant efficiently is of great importance. This paper describes digital control of working fluid rate based on an adaptive control theory for the ''Imari2'' OTEC plant at Saga University. Provisions have been made for linkage between the software of the adaptive control theory and the hardware of the OTEC plant. The authors can obtain satisfactory control performance using this digital control system.

  3. Hardware Implementation of 32-Bit High-Speed Direct Digital Frequency Synthesizer

    PubMed Central

    Ibrahim, Salah Hasan; Ali, Sawal Hamid Md.; Islam, Md. Shabiul

    2014-01-01

    The design and implementation of a high-speed direct digital frequency synthesizer are presented. A modified Brent-Kung parallel adder is combined with pipelining technique to improve the speed of the system. A gated clock technique is proposed to reduce the number of registers in the phase accumulator design. The quarter wave symmetry technique is used to store only one quarter of the sine wave. The ROM lookup table (LUT) is partitioned into three 4-bit sub-ROMs based on angular decomposition technique and trigonometric identity. Exploiting the advantages of sine-cosine symmetrical attributes together with XOR logic gates, one sub-ROM block can be removed from the design. These techniques, compressed the ROM into 368 bits. The ROM compressed ratio is 534.2 : 1, with only two adders, two multipliers, and XOR-gates with high frequency resolution of 0.029 Hz. These techniques make the direct digital frequency synthesizer an attractive candidate for wireless communication applications. PMID:24991635

  4. Hardware implementation of 32-bit high-speed direct digital frequency synthesizer.

    PubMed

    Ibrahim, Salah Hasan; Ali, Sawal Hamid Md; Islam, Md Shabiul

    2014-01-01

    The design and implementation of a high-speed direct digital frequency synthesizer are presented. A modified Brent-Kung parallel adder is combined with pipelining technique to improve the speed of the system. A gated clock technique is proposed to reduce the number of registers in the phase accumulator design. The quarter wave symmetry technique is used to store only one quarter of the sine wave. The ROM lookup table (LUT) is partitioned into three 4-bit sub-ROMs based on angular decomposition technique and trigonometric identity. Exploiting the advantages of sine-cosine symmetrical attributes together with XOR logic gates, one sub-ROM block can be removed from the design. These techniques, compressed the ROM into 368 bits. The ROM compressed ratio is 534.2:1, with only two adders, two multipliers, and XOR-gates with high frequency resolution of 0.029 Hz. These techniques make the direct digital frequency synthesizer an attractive candidate for wireless communication applications.

  5. [Therapeutic instrument for brain circulation function on the basis of direct digital synthesis technology].

    PubMed

    Li, Qiang; Gan, Minliang

    2005-02-01

    Electricity can stimulate cerebral fastigial nucleus to increase regional cerebral blood flow (rCBF) and narrow the volume of infarct, therefore its effect on ischemic brain disorder may be helpful. The therapeutic instrument for brain circulation function based on direct digital synthesis (DDS) technology uses the domestic newest scientific findings and others in foreign countries. Adopting the DDS technology directly, it institutes safe and efficacious treatment. Through pasting the electrodes on body surface, the non-invasive instrument introduces electric current to cerebral fastigial nucleus (FN) and hence it improves the state of brain blood supply and nerve conduction, increases cerebral blood flow, reduces the number of necrotic neurons in the district of penumbra, and mitigates brain edema. Consequently, it improves the function of brain circulation.

  6. Computer aided design of digital controller for radial active magnetic bearings

    NASA Technical Reports Server (NTRS)

    Cai, Zhong; Shen, Zupei; Zhang, Zuming; Zhao, Hongbin

    1992-01-01

    A five degree of freedom Active Magnetic Bearing (AMB) system is developed which is controlled by digital controllers. The model of the radial AMB system is linearized and the state equation is derived. Based on the state variables feedback theory, digital controllers are designed. The performance of the controllers are evaluated according to experimental results. The Computer Aided Design (CAD) method is used to design controllers for magnetic bearings. The controllers are implemented with a digital signal processing (DSP) system. The control algorithms are realized with real-time programs. It is very easy to change the controller by changing or modifying the programs. In order to identify the dynamic parameters of the controlled magnetic system, a special experiment was carried out. Also, the online Recursive Least Squares (RLS) parameter identification method is studied. It can be realized with the digital controllers. Online parameter identification is essential for the realization of an adaptive controller.

  7. Challenges and implementation aspects of switched-mode power supplies with digital control for automotive applications

    NASA Astrophysics Data System (ADS)

    Quenzer-Hohmuth, Samuel; Rosahl, Thoralf; Ritzmann, Steffen; Wicht, Bernhard

    2016-09-01

    Switched-mode power supplies (SMPS) convert an input DC-voltage into a higher or lower output voltage. In automotive, analog control is mostly used in order to keep the required output voltages constant and resistant to disturbances. The design of robust analog control for SMPS faces parameter variations of integrated and external passive components. Using digital control, parameter variations can be eliminated and the required area for the integrated circuit can be reduced at the same time. Digital control design bears challenges like the prevention of limit cycle oscillations and controller-wind-up. This paper reviews how to prevent these effects. Digital control loops introduce new sources for dead times in the control loop, for example the latency of the analog-to-digital-converter (ADC). Dead times have negative influence on the stability of the control loop, because they lead to phase delays. Consequently, low latency is one of the key requirements for analog-to-digital-converters in digitally controlled SMPS. Exploiting the example of a 500 kHz-buck converter with a crossover frequency of 70 kHz, this paper shows that the 5 µs-latency of a ΔΣ-analog-to-digital-converter leads to a reduction in phase margin of 126°. The latency is less critical for boost converters because of their inherent lower crossover frequencies. Finally, the paper shows a comparison between analog and digital control of SMPS with regard to chip area and test costs.

  8. Secure digital content control and distribution through the Internet

    NASA Astrophysics Data System (ADS)

    Xu, Changsheng; Wu, Jiankang

    1999-12-01

    This paper present a method to distribute the security key used to encrypt digital content by embedding the security key as a watermark into a digital sample that is appended to the encrypted digital content. The security key embedded into the sample is imperceptible and can not be detected by attackers. To play or read digital content, a portable device will extract the security key from the sample, then use the detected key to decrypt the encrypted content. This paper also present a method to generate and transfer right between clearing hose and portable device and between two portable devices. In order to prevent digital content from being illegally used, authentication, and verification between clearing house and portable device and between two portable devices are employed. The right information is tamper-resistent when it is transferred to portable devices. This method can maximally protect the usage of digital contents even if the portable device is breached.

  9. Evaluation of automatic exposure control options in digital mammography.

    PubMed

    Zhou, Yifang; Scott, Alexander; Allahverdian, Janet; Frankel, Steve

    2014-01-01

    To quantify the trade-offs of dose and image quality among pre-loaded automatic exposure control (AEC) options in digital mammography, two AEC tables from the Hologic Selenia digital mammography system were compared: the default AEC "table 0" and AEC "table 1". Realistically-shaped phantoms consisting of tissue-equivalent material of various thicknesses (4.5 cm-7 cm) were imaged to obtain a figure of merit (FOM), the squared contrast-to-noise ratio per mean glandular dose. To relate the results to pathological findings and to evaluate the overall performance, the measured contrast-to-noise ratios were applied to simulated lesions on the anthropomorphic breast phantom images, producing various lesion configurations which were blindly scored. It was found that the AEC table 1 improves the low contrast FOM by 11% to 20% for the breast thicknesses of 4.5-6 cm. However, for the 7 cm thick breast, the AEC table 1 decreases the low contrast FOM by 17%. For microcalcifications, the AEC table 1 improves the FOM slightly for the breast thicknesses of 4.5--6 cm and decreases it by 18% at a thickness of 7 cm. The lesion simulation showed enhanced contrast due to the AEC table 1 for the breast thicknesses of 5 cm, 6 cm, and 7 cm, but the enhancement gradually reduces as the thickness increases. The lesion reading showed that the microcalcification detection was scored significantly higher from the AEC table 1 for the thicknesses 5 cm, 6 cm, and 7 cm. The corresponding improvement of mass detection scores was also observed but not consistently significant over the thickness range.

  10. NOx Sensor for Direct Injection Emission Control

    SciTech Connect

    Betteridge, William J

    2006-02-28

    The Electricore/Delphi team continues to leverage the electrochemical planar sensor technology that has produced stoichiometric planar and wide range oxygen sensors as the basis for development of a NOx sensor. Zirconia cell technology with an integrated heater will provide the foundation for the sensor structure. Proven materials and packaging technology will help to ensure a cost-effective approach to the manufacture of this sensor. The electronics technique and interface is considered to be an area where new strategies need to be employed to produce higher S/N ratios of the NOx signal with emphasis on signal stability over time for robustness and durability Both continuous mode and pulse mode control techniques are being evaluated. Packaging the electronics requires careful design and circuit partitioning so that only the necessary signal conditioning electronics are coupled directly in the wiring harness, while the remainder is situated within the ECM for durability and costs reasons. This task continues to be on hold due to the limitation that the definition of the interface electronics was unavailable until very late in the project. The sense element is based on the amperometric method utilizing integrated alumina and zirconia ceramics. Precious metal electrodes are used to form the integrated heater, the cell electrodes and leads. Inside the actual sense cell structure, it is first necessary to separate NOx from the remaining oxygen constituents of the exhaust, without reducing the NOx. Once separated, the NOx will be measured using a measurement cell. Development or test coupons have been used to facilitate material selection and refinement, cell, diffusion barrier, and chamber development. The sense element currently requires elaborate interconnections. To facilitate a robust durable connection, mechanical and metallurgical connections are under investigation. Materials and process refinements continue to play an important role in the development of the

  11. 49 CFR 30.9 - Citizenship: Direct or indirect control.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Citizenship: Direct or indirect control. 30.9... Citizenship: Direct or indirect control. A contractor, subcontractor, or person providing a service shall be considered to be a citizen or national of a foreign country, or controlled directly or indirectly by...

  12. Note: A high-frequency signal generator based on direct digital synthesizer and field-programmable gate array.

    PubMed

    Du, Yuanbo; Li, Wenbing; Ge, Yapeng; Li, Hui; Deng, Ke; Lu, Zehuang

    2017-09-01

    A high-frequency signal generator based on direct digital synthesizer (DDS) and field-programmable gate array (FPGA) is presented. The FPGA provides the controlling time sequence for the DDS, which has a highest output frequency of 1.4 GHz and a frequency resolution of 190 pHz. At an output frequency of 1.2 GHz, the measured phase noise, including the contribution of the reference clock, is -65 dBc/Hz@1 Hz, while the intrinsic phase noise is -82 dBc/Hz@1 Hz. Time delay of the DDS is measured to be less than 150 ns. The signal generator is used to drive an acousto-optic modulator, and the rise time due to the whole link is 24 ns. The developed signal generator can be used in many precision measurement experiments in the fields of atomic, molecular, and optical physics.

  13. Note: A high-frequency signal generator based on direct digital synthesizer and field-programmable gate array

    NASA Astrophysics Data System (ADS)

    Du, Yuanbo; Li, Wenbing; Ge, Yapeng; Li, Hui; Deng, Ke; Lu, Zehuang

    2017-09-01

    A high-frequency signal generator based on direct digital synthesizer (DDS) and field-programmable gate array (FPGA) is presented. The FPGA provides the controlling time sequence for the DDS, which has a highest output frequency of 1.4 GHz and a frequency resolution of 190 pHz. At an output frequency of 1.2 GHz, the measured phase noise, including the contribution of the reference clock, is -65 dBc/Hz@1 Hz, while the intrinsic phase noise is -82 dBc/Hz@1 Hz. Time delay of the DDS is measured to be less than 150 ns. The signal generator is used to drive an acousto-optic modulator, and the rise time due to the whole link is 24 ns. The developed signal generator can be used in many precision measurement experiments in the fields of atomic, molecular, and optical physics.

  14. An Investigation of Digital Instrumentation and Control System Failure Modes

    SciTech Connect

    Korsah, Kofi; Cetiner, Mustafa Sacit; Muhlheim, Michael David; Poore III, Willis P

    2010-01-01

    A study sponsored by the Nuclear Regulatory Commission study was conducted to investigate digital instrumentation and control (DI&C) systems and module-level failure modes using a number of databases both in the nuclear and non-nuclear industries. The objectives of the study were to obtain relevant operational experience data to identify generic DI&C system failure modes and failure mechanisms, and to obtain generic insights, with the intent of using results to establish a unified framework for categorizing failure modes and mechanisms. Of the seven databases studied, the Equipment Performance Information Exchange database was found to contain the most useful data relevant to the study. Even so, the general lack of quality relative to the objectives of the study did not allow the development of a unified framework for failure modes and mechanisms of nuclear I&C systems. However, an attempt was made to characterize all the failure modes observed (i.e., without regard to the type of I&C equipment under consideration) into common categories. It was found that all the failure modes identified could be characterized as (a) detectable/preventable before failures, (b) age-related failures, (c) random failures, (d) random/sudden failures, or (e) intermittent failures. The percentage of failure modes characterized as (a) was significant, implying that a significant reduction in system failures could be achieved through improved online monitoring, exhaustive testing prior to installation, adequate configuration control or verification and validation, etc.

  15. Anticipatory Planning and Control of Grasp Positions and Forces for Dexterous Two-Digit Manipulation

    PubMed Central

    Fu, Qiushi; Zhang, Wei; Santello, Marco

    2010-01-01

    Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the Central Nervous System could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate (1) digit placement for optimal force distribution and (2) digit forces as a function of variable digit positions. While all subjects learned to minimize object roll within the first three trials, the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics. PMID:20610745

  16. A gallium-arsenide digital phase shifter for clock and control signal distribution in high-speed digital systems

    NASA Technical Reports Server (NTRS)

    Fouts, Douglas J.

    1992-01-01

    The design, implementation, testing, and applications of a gallium-arsenide digital phase shifter and fan-out buffer are described. The integrated circuit provides a method for adjusting the phase of high-speed clock and control signals in digital systems, without the need for pruning cables, multiplexing between cables of different lengths, delay lines, or similar techniques. The phase of signals distributed with the described chip can be dynamically adjusted in eight different steps of approximately 60 ps per step. The IC also serves as a fan-out buffer and provides 12 in-phase outputs. The chip is useful for distributing high-speed clock and control signals in synchronous digital systems, especially if components are distributed over a large physical area or if there is a large number of components.

  17. A gallium-arsenide digital phase shifter for clock and control signal distribution in high-speed digital systems

    NASA Technical Reports Server (NTRS)

    Fouts, Douglas J.

    1992-01-01

    The design, implementation, testing, and applications of a gallium-arsenide digital phase shifter and fan-out buffer are described. The integrated circuit provides a method for adjusting the phase of high-speed clock and control signals in digital systems, without the need for pruning cables, multiplexing between cables of different lengths, delay lines, or similar techniques. The phase of signals distributed with the described chip can be dynamically adjusted in eight different steps of approximately 60 ps per step. The IC also serves as a fan-out buffer and provides 12 in-phase outputs. The chip is useful for distributing high-speed clock and control signals in synchronous digital systems, especially if components are distributed over a large physical area or if there is a large number of components.

  18. Digital direct electron imaging of energy-filtered electron backscatter diffraction patterns

    NASA Astrophysics Data System (ADS)

    Vespucci, S.; Winkelmann, A.; Naresh-Kumar, G.; Mingard, K. P.; Maneuski, D.; Edwards, P. R.; Day, A. P.; O'Shea, V.; Trager-Cowan, C.

    2015-11-01

    Electron backscatter diffraction is a scanning electron microscopy technique used to obtain crystallographic information on materials. It allows the nondestructive mapping of crystal structure, texture, and strain with a lateral and depth resolution on the order of tens of nanometers. Electron backscatter diffraction patterns (EBSPs) are presently acquired using a detector comprising a scintillator coupled to a digital camera, and the crystallographic information obtainable is limited by the conversion of electrons to photons and then back to electrons again. In this article we will report the direct acquisition of energy-filtered EBSPs using a digital complementary metal-oxide-semiconductor hybrid pixel detector, Timepix. We show results from a range of samples with different mass and density, namely diamond, silicon, and GaN. Direct electron detection allows the acquisition of EBSPs at lower (≤5 keV) electron beam energies. This results in a reduction in the depth and lateral extension of the volume of the specimen contributing to the pattern and will lead to a significant improvement in lateral and depth resolution. Direct electron detection together with energy filtering (electrons having energy below a specific value are excluded) also leads to an improvement in spatial resolution but in addition provides an unprecedented increase in the detail in the acquired EBSPs. An increase in contrast and higher-order diffraction features are observed. In addition, excess-deficiency effects appear to be suppressed on energy filtering. This allows the fundamental physics of pattern formation to be interrogated and will enable a step change in the use of electron backscatter diffraction (EBSD) for crystal phase identification and the mapping of strain. The enhancement in the contrast in high-pass energy-filtered EBSD patterns is found to be stronger for lighter, less dense materials. The improved contrast for such materials will enable the application of the EBSD

  19. 47 CFR 73.9001 - Redistribution control of digital television broadcasts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Redistribution control of digital television broadcasts. 73.9001 Section 73.9001 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES Digital Broadcast Television Redistribution Control §...

  20. 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

  1. Digital Interface Board to Control Phase and Amplitude of Four Channels

    NASA Technical Reports Server (NTRS)

    Smith, Amy E.; Cook, Brian M.; Khan, Abdur R.; Lux, James P.

    2011-01-01

    An increasing number of parts are designed with digital control interfaces, including phase shifters and variable attenuators. When designing an antenna array in which each antenna has independent amplitude and phase control, the number of digital control lines that must be set simultaneously can grow very large. Use of a parallel interface would require separate line drivers, more parts, and thus additional failure points. A convenient form of control where single-phase shifters or attenuators could be set or the whole set could be programmed with an update rate of 100 Hz is needed to solve this problem. A digital interface board with a field-programmable gate array (FPGA) can simultaneously control an essentially arbitrary number of digital control lines with a serial command interface requiring only three wires. A small set of short, high-level commands provides a simple programming interface for an external controller. Parity bits are used to validate the control commands. Output timing is controlled within the FPGA to allow for rapid update rates of the phase shifters and attenuators. This technology has been used to set and monitor eight 5-bit control signals via a serial UART (universal asynchronous receiver/transmitter) interface. The digital interface board controls the phase and amplitude of the signals for each element in the array. A host computer running Agilent VEE sends commands via serial UART connection to a Xilinx VirtexII FPGA. The commands are decoded, and either outputs are set or telemetry data is sent back to the host computer describing the status and the current phase and amplitude settings. This technology is an integral part of a closed-loop system in which the angle of arrival of an X-band uplink signal is detected and the appropriate phase shifts are applied to the Ka-band downlink signal to electronically steer the array back in the direction of the uplink signal. It will also be used in the non-beam-steering case to compensate for

  2. Optic disc detection from normalized digital fundus images by means of a vessels' direction matched filter.

    PubMed

    Youssif, A R; Ghalwash, A Z; Ghoneim, A R

    2008-01-01

    Optic disc (OD) detection is a main step while developing automated screening systems for diabetic retinopathy. We present in this paper a method to automatically detect the position of the OD in digital retinal fundus images. The method starts by normalizing luminosity and contrast through out the image using illumination equalization and adaptive histogram equalization methods respectively. The OD detection algorithm is based on matching the expected directional pattern of the retinal blood vessels. Hence, a simple matched filter is proposed to roughly match the direction of the vessels at the OD vicinity. The retinal vessels are segmented using a simple and standard 2-D Gaussian matched filter. Consequently, a vessels direction map of the segmented retinal vessels is obtained using the same segmentation algorithm. The segmented vessels are then thinned, and filtered using local intensity, to represent finally the OD-center candidates. The difference between the proposed matched filter resized into four different sizes, and the vessels' directions at the surrounding area of each of the OD-center candidates is measured. The minimum difference provides an estimate of the OD-center coordinates. The proposed method was evaluated using a subset of the STARE project's dataset, containing 81 fundus images of both normal and diseased retinas, and initially used by literature OD detection methods. The OD-center was detected correctly in 80 out of the 81 images (98.77%). In addition, the OD-center was detected correctly in all of the 40 images (100%) using the publicly available DRIVE dataset.

  3. Exploratory Study of Rural Physicians' Self-Directed Learning Experiences in a Digital Age.

    PubMed

    Curran, Vernon; Fleet, Lisa; Simmons, Karla; Ravalia, Mohamed; Snow, Pamela

    2016-01-01

    The nature and characteristics of self-directed learning (SDL) by physicians has been transformed with the growth in digital, social, and mobile technologies (DSMTs). Although these technologies present opportunities for greater "just-in-time" information seeking, there are issues for ensuring effective and efficient usage to compliment one's repertoire for continuous learning. The purpose of this study was to explore the SDL experiences of rural physicians and the potential of DSMTs for supporting their continuing professional development (CPD). Semistructured interviews were conducted with a purposive sample of rural physicians. Interview data were transcribed verbatim and analyzed using NVivo analytical software and thematic analysis. Fourteen (N = 14) interviews were conducted and key thematic categories that emerged included key triggers, methods of undertaking SDL, barriers, and supports. Methods and resources for undertaking SDL have evolved considerably, and rural physicians report greater usage of mobile phones, tablets, and laptop computers for updating their knowledge and skills and in responding to patient questions/problems. Mobile technologies, and some social media, can serve as "triggers" in instigating SDL and a greater usage of DSMTs, particularly at "point of care," may result in higher levels of SDL. Social media is met with some scrutiny and ambivalence, mainly because of the "credibility" of information and risks associated with digital professionalism. DSMTs are growing in popularity as a key resource to support SDL for rural physicians. Mobile technologies are enabling greater "point-of-care" learning and more efficient information seeking. Effective use of DSMTs for SDL has implications for enhancing just-in-time learning and quality of care. Increasing use of DSMTs and their new effect on SDL raises the need for reflection on conceptualizations of the SDL process. The "digital age" has implications for our CPD credit systems and the roles

  4. A Digital Control Algorithm for Magnetic Suspension Systems

    NASA Technical Reports Server (NTRS)

    Britton, Thomas C.

    1996-01-01

    An ongoing program exists to investigate and develop magnetic suspension technologies and modelling techniques at NASA Langley Research Center. Presently, there is a laboratory-scale large air-gap suspension system capable of five degree-of-freedom (DOF) control that is operational and a six DOF system that is under development. Those systems levitate a cylindrical element containing a permanent magnet core above a planar array of electromagnets, which are used for levitation and control purposes. In order to evaluate various control approaches with those systems, the Generic Real-Time State-Space Controller (GRTSSC) software package was developed. That control software package allows the user to implement multiple control methods and allows for varied input/output commands. The development of the control algorithm is presented. The desired functionality of the software is discussed, including the ability to inject noise on sensor inputs and/or actuator outputs. Various limitations, common issues, and trade-offs are discussed including data format precision; the drawbacks of using either Direct Memory Access (DMA), interrupts, or program control techniques for data acquisition; and platform dependent concerns related to the portability of the software, such as memory addressing formats. Efforts to minimize overall controller loop-rate and a comparison of achievable controller sample rates are discussed. The implementation of a modular code structure is presented. The format for the controller input data file and the noise information file is presented. Controller input vector information is available for post-processing by mathematical analysis software such as MATLAB1.

  5. Learning in the Digital Age: Control or Connection?

    ERIC Educational Resources Information Center

    Van Galen, Jane

    2013-01-01

    In October 2011, 200 state school officers and legislators gathered at a hotel in San Francisco to learn how to "revolutionize" learning by "personalizing" instruction. The occasion was former Florida Gov. Jeb Bush's second annual National Summit on Education Reform. The topic was digital learning. The vision of digitally managed curriculum and…

  6. Learning in the Digital Age: Control or Connection?

    ERIC Educational Resources Information Center

    Van Galen, Jane

    2013-01-01

    In October 2011, 200 state school officers and legislators gathered at a hotel in San Francisco to learn how to "revolutionize" learning by "personalizing" instruction. The occasion was former Florida Gov. Jeb Bush's second annual National Summit on Education Reform. The topic was digital learning. The vision of digitally managed curriculum and…

  7. LQG and direct rate feedback control with model reduction on a flexible laboratory grid structure

    NASA Technical Reports Server (NTRS)

    Schamel, G. C., II; Haftka, R. T.

    1989-01-01

    This paper presents experimental and theoretical comparisons of three control laws applied to a complex laboratory structure. A reduced finite element model was generated for designing the control systems and then corrected based on measured mode shapes and frequencies. A standard time-invariant linear quadratic regulator with state estimation was investigated first. Two simple direct rate feedback control laws both guaranteeing stability were also designed using the reduced model. One minimizes the maximum control force and the other minimizes the same quadratic performance index as the linear quadratic regulator. The three control laws have comparable performance indices with the direct rate feedback designs having better spillover properties. Experimental results for all designs were obtained with digital implementation. It was shown that the performance of the control system designed on the basis of the corrected finite element model agreed better with experimental results than the performance of the control system designed on the basis of the uncorrected model.

  8. Fused off-axis object illumination direct-to-digital holography with a plurality of illumination sources

    DOEpatents

    Price, Jeffery R.; Bingham, Philip R.

    2005-11-08

    Systems and methods are described for rapid acquisition of fused off-axis illumination direct-to-digital holography. A method of recording a plurality of off-axis object illuminated spatially heterodyne holograms, each of the off-axis object illuminated spatially heterodyne holograms including spatially heterodyne fringes for Fourier analysis, includes digitally recording, with a first illumination source of an interferometer, a first off-axis object illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording, with a second illumination source of the interferometer, a second off-axis object illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.

  9. Direct Manufacturing of CubeSat Using 3-D Digital Printer and Determination of its Mechanical Properties

    DTIC Science & Technology

    2010-12-01

    mechanical properties (i.e. strength and elastic modulus) of samples fabricated from a 3-D digital printer as a function of processing parameters (2) to...geometry is brought into the 3D printer software application and rotated for the desired build orientation. The software then slices horizontal build...Arlington, VA 22203-1714 Direct Manufacturing of CubeSat Using 3-D Digital Printer and Determination of Its Mechanical Properties

  10. A firmware-defined digital direct-sampling NMR spectrometer for condensed matter physics.

    PubMed

    Pikulski, M; Shiroka, T; Ott, H-R; Mesot, J

    2014-09-01

    We report on the design and implementation of a new digital, broad-band nuclear magnetic resonance (NMR) spectrometer suitable for probing condensed matter. The spectrometer uses direct sampling in both transmission and reception. It relies on a single, commercially-available signal processing device with a user-accessible field-programmable gate array (FPGA). Its functions are defined exclusively by the FPGA firmware and the application software. Besides allowing for fast replication, flexibility, and extensibility, our software-based solution preserves the option to reuse the components for other projects. The device operates up to 400 MHz without, and up to 800 MHz with undersampling, respectively. Digital down-conversion with ±10 MHz passband is provided on the receiver side. The system supports high repetition rates and has virtually no intrinsic dead time. We describe briefly how the spectrometer integrates into the experimental setup and present test data which demonstrates that its performance is competitive with that of conventional designs.

  11. A firmware-defined digital direct-sampling NMR spectrometer for condensed matter physics

    SciTech Connect

    Pikulski, M. Shiroka, T.; Ott, H.-R.; Mesot, J.

    2014-09-15

    We report on the design and implementation of a new digital, broad-band nuclear magnetic resonance (NMR) spectrometer suitable for probing condensed matter. The spectrometer uses direct sampling in both transmission and reception. It relies on a single, commercially-available signal processing device with a user-accessible field-programmable gate array (FPGA). Its functions are defined exclusively by the FPGA firmware and the application software. Besides allowing for fast replication, flexibility, and extensibility, our software-based solution preserves the option to reuse the components for other projects. The device operates up to 400 MHz without, and up to 800 MHz with undersampling, respectively. Digital down-conversion with ±10 MHz passband is provided on the receiver side. The system supports high repetition rates and has virtually no intrinsic dead time. We describe briefly how the spectrometer integrates into the experimental setup and present test data which demonstrates that its performance is competitive with that of conventional designs.

  12. Reference-free direct digital lock-in method and apparatus

    NASA Technical Reports Server (NTRS)

    Henry, James E. (Inventor); Leonard, John A. (Inventor)

    2000-01-01

    A reference-free direct digital lock-in system (RDDL 10) has a first input coupled to a periodic electrical signal and an output for outputting an indication of a magnitude of a desired periodic signal component. The RDDL also has a second input for receiving a signal (9) that specifies a reference period value, and operates to autonomously generate a lock-in reference signal having a specified period and a phase that is adjusted to maximize a magnitude of the outputted desired periodic signal component. In an embodiment of a measurement system that includes the RDDL 10 an optical source provides a chopped light beam having wavelengths within a predetermined range of wavelengths, and the periodic electrical signal is generated by at least one photodetector that is illuminated by the chopped light beam. In this embodiment the measurement system characterizes, for at least one wavelength of light that is generated by the optical source, a spectral response of the at least one photodetector. The RDDL can operate in nonreal-time upon previously generated and stored digital equivalent values of the periodic electrical signal or signals.

  13. 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.

  14. Mars Digital Image Model 2.1 Control Network

    NASA Technical Reports Server (NTRS)

    Archinal, B. A.; Kirk, R. L.; Duxbury, T. C.; Lee, E. M.; Sucharski, R.; Cook, D.

    2003-01-01

    USGS is currently preparing a new version of its global Mars digital image mosaic, which will be known as MDIM 2.1. As part of this process we are completing a new photogrammetric solution of the global Mars control network. This is an improved version of the network established earlier by RAND and USGS personnel, as partially described previously. MDIM 2.1 will have many improvements over earlier Viking Orbiter (VO) global mosaics. Geometrically, it will be an orthoimage product, draped on Mars Orbiter Laser Altimeter (MOLA) derived topography, thus accounting properly for the commonly oblique VO imagery. Through the network being described here it will be tied to the newly defined IAU/IAG 2000 Mars coordinate system via ties to MOLA data. Thus, MDIM 2.1 will provide complete global orthorectified imagery coverage of Mars at the resolution of 1/256 deg of MDIM 2.0, and be compatible with MOLA and other products produced in the current coordinate system.

  15. A ROM-less direct digital frequency synthesizer based on hybrid polynomial approximation.

    PubMed

    Omran, Qahtan Khalaf; Islam, Mohammad Tariqul; Misran, Norbahiah; Faruque, Mohammad Rashed Iqbal

    2014-01-01

    In this paper, a novel design approach for a phase to sinusoid amplitude converter (PSAC) has been investigated. Two segments have been used to approximate the first sine quadrant. A first linear segment is used to fit the region near the zero point, while a second fourth-order parabolic segment is used to approximate the rest of the sine curve. The phase sample, where the polynomial changed, was chosen in such a way as to achieve the maximum spurious free dynamic range (SFDR). The invented direct digital frequency synthesizer (DDFS) has been encoded in VHDL and post simulation was carried out. The synthesized architecture exhibits a promising result of 90 dBc SFDR. The targeted structure is expected to show advantages for perceptible reduction of hardware resources and power consumption as well as high clock speeds.

  16. A ROM-Less Direct Digital Frequency Synthesizer Based on Hybrid Polynomial Approximation

    PubMed Central

    Omran, Qahtan Khalaf; Islam, Mohammad Tariqul; Misran, Norbahiah; Faruque, Mohammad Rashed Iqbal

    2014-01-01

    In this paper, a novel design approach for a phase to sinusoid amplitude converter (PSAC) has been investigated. Two segments have been used to approximate the first sine quadrant. A first linear segment is used to fit the region near the zero point, while a second fourth-order parabolic segment is used to approximate the rest of the sine curve. The phase sample, where the polynomial changed, was chosen in such a way as to achieve the maximum spurious free dynamic range (SFDR). The invented direct digital frequency synthesizer (DDFS) has been encoded in VHDL and post simulation was carried out. The synthesized architecture exhibits a promising result of 90 dBc SFDR. The targeted structure is expected to show advantages for perceptible reduction of hardware resources and power consumption as well as high clock speeds. PMID:24892092

  17. Infrared Femtosecond Laser Direct-Writing Digital Volume Gratings in Fused Silica

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Li, Yu-Hua; Lu, Pei-Xiang

    2010-04-01

    We demonstrate that digital volume gratings can be fabricated in fused silica glass conveniently by direct femtosecond laser writing. The diffraction efficiencies of volume gratings can be essentially modulated by simply stacking and offsetting the unit structure. A series of volume gratings, which have the pitches of 5 μm and the size of 1 mm × 1 mm, have been fabricated with the writing speed of 500 μm/s, with which the processing period of each grating layer could be reduced to several minutes with a 1-kHz femtosecond laser system. Results show that the power spectrum of the diffracted waves of the volume gratings are dependent on the layer gap and layer offsetting.

  18. Digital baseband predistortion for SSII cancellation in EAM-based direct-detection OFDM systems

    NASA Astrophysics Data System (ADS)

    Yang, Pengfei; Shi, Hu; Chen, Xue

    2017-01-01

    To increase the available bandwidth of electro-absorption modulator (EAM)-based direct-detection orthogonal frequency division multiplexing (DD-OFDM) systems, which suffers from dispersion- and chirp-induced power fading, the multiband subcarrier allocation scheme and adaptive modulation formats are adopted. However, the subcarrier-to-subcarrier intermixing interference (SSII) would degrade signal-to-noise ratio on the increased bandwidth and become a bottleneck of the multiband systems. In this paper, a novel digital baseband predistortion is proposed to minimize the penalty of SSII. The experimental results show that a 30 Gbps EAM-based DD-OFDM system with the proposed technique could improve 3 dB receiver sensitivity compared with the system without the technique over 100 km long single mode fiber transmission and only decreases 1.0 dB in comparison with the back-to-back situation.

  19. Independent control of human finger-tip forces at individual digits during precision lifting.

    PubMed Central

    Edin, B B; Westling, G; Johansson, R S

    1992-01-01

    1. Subjects lifted an object with two parallel vertical grip surfaces and a low centre of gravity using the precision grip between the tips of the thumb and index finger. The friction between the object and the digits was varied independently at each digit by changing the contact surfaces between lifts. 2. With equal frictional conditions at the two grip surfaces, the finger-tip forces were about equal at the two digits, i.e. similar vertical lifting forces and grip forces were used. With different frictions, the digit touching the most slippery surface exerted less vertical lifting force than the digit in contact with the rougher surface. Thus, the safety margins against slips were similar at the two digits whether they made contact with surfaces of similar or different friction. 3. During digital nerve block, large and variable safety margins were employed, i.e. the finger-tip forces did not reflect the surface conditions. Slips occurred more frequently than under normal conditions (14% of all trials with nerve block, <5% during normal conditions), and they only occasionally elicited compensatory adjustments of the finger-tip forces and then at prolonged latencies. 4. The partitioning of the vertical lifting force between the digits was thus dependent on digital afferent inputs and resulted from active automatic regulation and not just from the mechanics of the task. 5. The safety margin employed at a particular digit was mainly determined by the frictional conditions encountered by the digit, and to a lesser degree by the surface condition at the same digit in the previous lift (anticipatory control), but was barely influenced by the surface condition at the other digit. 6. It was concluded that the finger-tip forces were independently controlled for each digit according to a 'non-slip strategy'. The findings suggest that the force distribution among the digits represents a digit-specific lower-level neural control establishing a stable grasp. This control

  20. Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface

    NASA Astrophysics Data System (ADS)

    Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

    2017-02-01

    Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements “00”, “01”, “10”, and “11”, respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source.

  1. Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface.

    PubMed

    Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

    2017-02-08

    Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements "00", "01", "10", and "11", respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source.

  2. Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface

    PubMed Central

    Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

    2017-01-01

    Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements “00”, “01”, “10”, and “11”, respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source. PMID:28176870

  3. Early experience with digital advance care planning and directives, a novel consumer-driven program

    PubMed Central

    Yang, Zhiyong; Spivey, Christy; Boardman, Bonnie; Courtney, Maureen

    2016-01-01

    Barriers to traditional advance care planning (ACP) and advance directive (AD) creation have limited the promise of ACP/AD for individuals and families, the healthcare team, and society. Our objectives were to determine the results of a digital ACP/AD through which consumers create, store, locate, and retrieve their ACP/AD at no charge and with minimal physician involvement, and the ACP/AD can be integrated into the electronic health record. The authors chose 900 users of MyDirectives, a digital ACP/AD tool, to achieve proportional representation of all 50 states by population size and then reviewed their responses. The 900 participants had an average age of 50.8 years (SD = 16.6); 84% of the men and 91% of the women were in self-reported good health when signing their ADs. Among the respondents, 94% wanted their physicians to consult a supportive and palliative care team if they were seriously ill; nearly 85% preferred cessation of life-sustaining treatments during their final days; 76% preferred to spend their final days at home or in a hospice; and 70% would accept attempted cardiopulmonary resuscitation in limited circumstances. Most respondents wanted an autopsy under certain conditions, and 62% wished to donate their organs. In conclusion, analysis of early experience with this ACP/AD platform demonstrates that individuals of different ages and conditions can engage in an interrogatory process about values, develop ADs that are more nuanced than traditional paper-based ADs in reflecting those values, and easily make changes to their ADs. Online ADs have the potential to remove barriers to ACP/AD and thus further improve patient-centered end-of-life care. PMID:27365867

  4. Digit Position and Forces Covary during Anticipatory Control of Whole-Hand Manipulation.

    PubMed

    Marneweck, Michelle; Lee-Miller, Trevor; Santello, Marco; Gordon, Andrew M

    2016-01-01

    Theoretical perspectives on anticipatory planning of object manipulation have traditionally been informed by studies that have investigated kinematics (hand shaping and digit position) and kinetics (forces) in isolation. This poses limitations on our understanding of the integration of such domains, which have recently been shown to be strongly interdependent. Specifically, recent studies revealed strong covariation of digit position and load force during the loading phase of two-digit grasping. Here, we determined whether such digit force-position covariation is a general feature of grasping. We investigated the coordination of digit position and forces during five-digit whole-hand manipulation of an object with a variable mass distribution. Subjects were instructed to prevent object roll during the lift. As found in precision grasping, there was strong trial-to-trial covariation of digit position and force. This suggests that the natural variation of digit position that is compensated for by trial-to-trial variation in digit forces is a fundamental feature of grasp control, and not only specific to precision grasp. However, a main difference with precision grasping was that modulation of digit position to the object's mass distribution was driven predominantly by the thumb, with little to no modulation of finger position. Modulation of thumb position rather than fingers is likely due to its greater range of motion and therefore adaptability to object properties. Our results underscore the flexibility of the central nervous system in implementing a range of solutions along the digit force-to-position continuum for dexterous manipulation.

  5. Fuzzy Control for Omni-Directional Vehicle with Ball Wheels

    NASA Astrophysics Data System (ADS)

    Iida, Kenichi; Mori, Taichi; Yasuno, Takashi

    In this paper, motion control for omni-directional vehicle with ball wheels is considered. The proposed omni-directional vehicle has two ball wheels, and the actuators are arranged to X-direction and Y-direction in ball wheel. Hence, omni-directional vehicle has the ability to move in arbitrary speed and direction, and has also the ability to turn around the place. The proposed control system consists of the fixed gain feedback controllers and self tuning fuzzy controllers. To achieve improvement of responses, rules of fuzzy controller are automatically adjusted by a tuning law. To achieve improvement of mobility, the optical mouse sensor is installed on omni-directional vehicle for self-localization. The experimental results demonstrate the effectiveness of the proposed system for improvement of the movement performance of the omni-directional vehicle.

  6. Digitally Controlled Four Harmonic Buncher for FSU LINAC

    NASA Astrophysics Data System (ADS)

    Moerland, Daniel S.; Wiedenhoever, Ingo; Baby, Lagy T.; Caussyn, David; Spingler, David

    2012-03-01

    Florida State University's John D. Fox Superconducting Accelerator Laboratory is operating a Tandem-Linac system for heavy ion beams at energies of 5-10 MeV/u. Recently, the accelerator has been used as the driver for the radioactive beam facility RESOLUT, which poses new demands on its high-intensity performance and time-resolution. These demands motivated us to optimize the RF bunching system and to switch the bunch frequency from 48.5 to 12.125 MHz. We installed a four-harmonic resonant transformer to create 3-4 kV potential oscillations across a pair of wire-mesh grids. This setup is modulating the energy of the beam injected into the tandem accelerator, with the aim to create short bunches of beam particles. Asawtooth-like wave-form is created using the Fourier series method, by combining the basis sinusoidal wave of 12.125MHz and its 3 higher order harmonics, in a manner similar to the systems used at ATLAS [1] and other RF-accelerators. A new aspect of our setup is the use of a digital 1GHz function generator, which allows us to optimize and stabilize the synthesized waveform. The control system was realized using labview and integrated into the recently updated controls of the accelerator. We characterize the bunching quality achievedand discuss the optimization of the bunching wave-form. The bunching system has been successfully used in a number of Linac-experiments performed during 2011.[4pt][1] S. Sharamentov, J. Bogaty, B.E. Clifft, R. Pardo, UPGRADE OF THE ATLAS POSITIVE ION INJECTOR BUNCHING SYSTEM, Proceedings of 2005 Particle Accelerator Conference, Knoxville, Tennessee

  7. Cease Remembering: Control Processes in Directed Forgetting

    ERIC Educational Resources Information Center

    Hourihan, Kathleen L.; Taylor, Tracy L.

    2006-01-01

    On the premise that committing a word to memory is a type of covert action capable of being stopped, this study merged an item-method directed forgetting paradigm with a stop signal paradigm. The primary dependent measure was immediate recall. Indicating that participants were able to countermand the default instruction to remember, there was an…

  8. Programmable controlled mode-locked fiber laser using a digital micromirror device.

    PubMed

    Liu, Wu; Fan, Jintao; Xie, Chen; Song, Youjian; Gu, Chenlin; Chai, Lu; Wang, Chingyue; Hu, Minglie

    2017-05-15

    A digital micromirror device (DMD)-based arbitrary spectrum amplitude shaper is incorporated into a large-mode-area photonic crystal fiber laser cavity. The shaper acts as an in-cavity programmable filter and provides large tunable dispersion from normal to anomalous. As a result, mode-locking is achieved in different dispersion regimes with watt-level high output power. By programming different filter profiles on the DMD, the laser generates femtosecond pulse with a tunable central wavelength and controllable bandwidth. Under conditions of suitable cavity dispersion and pump power, design-shaped spectra are directly obtained by varying the amplitude transfer function of the filter. The results show the versatility of the DMD-based in-cavity filter for flexible control of the pulse dynamics in a mode-locked fiber laser.

  9. 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.

  10. Digital Position Control Algorithms For An SCR-DC Motor Drive

    NASA Astrophysics Data System (ADS)

    Farooq, M.; Plant, B. J.; Winfield, D. N.

    1987-10-01

    Two algorithms for the digital control of position of a three phase SCR controlled DC motor are compared. The digital control is novel in that the sampling period is variable and depends on the firing angles of the SCR's. While the algorithms are not new, their use with a variable sampling period in this application is. Performance is assessed through both simulation on a digital computer of the controlled motor and an implementation on a microprocessor based bench model. Both algorithms give equivalent performance in terms of step response to position commands.

  11. Image quality of a prototype direct conversion detector for digital mammography

    NASA Astrophysics Data System (ADS)

    Mainprize, James G.; Ford, Nancy L.; Yin, Shi; Tumer, Tumay O.; Yaffe, Martin J.

    1999-05-01

    A digital mammography system in which the x-ray sensitive device is a solid-state direct conversion detector is under development. This detector is a 1 mm thick silicon photodiode array hybridized to a CCD read-out, with a 50 micrometer pixel pitch. The detector is designed to be used in a slot-scanned system using time-delay integration (TDI) for signal acquisition. To handle the large signal generated in the photodiode, a novel read-out technique was used, in which charge was integrated 'on-chip' over a small number of rows, and the output of each of these sections was digitally summed 'off-chip' to produce the total integrated signal for each pixel in the image. This two-stage integration process not only allows easy acquisition of large signals, it effectively increases bit depth from 12 bits (for a single section) to approximately 16 (for the total integrated signal). The image quality of the device has been measured and compared to predictions based on cascaded linear systems theory. The resolution of the new detector was determined from the modulation transfer function (MTF) which was obtained from over-sampled edge spread functions (ESF). The ESF was measured in both the scan and slot directions from four repeated images of a tantalum edge. Noise power spectra (NPS) were determined from 40 repeated flat-field images at each of several x-ray exposures. By combining the MTF and NPS measurements, the detective quantum efficiency (DQE) was also determined. The MTF in the non-scanned direction was found to greater than 20% at 10 mm-1 and slightly lower in the scanned direction (approximately equals 10% at 10 mm-1). In all cases, the DQE was at least comparable to film-screen mammography receptors. The DQE at 120 mR detector exposure at zero spatial frequency ranged from 0.4 to 0.6 depending on the sample tested. Electronic noise was fairly low, contributing to less than plus or minus 7 ADU (out of a possible 98304 ADU). Future work will involve re-designing the

  12. Controlled Bidirectional Quantum Secure Direct Communication

    PubMed Central

    Chou, Yao-Hsin; Lin, Yu-Ting; Zeng, Guo-Jyun; Lin, Fang-Jhu; Chen, Chi-Yuan

    2014-01-01

    We propose a novel protocol for controlled bidirectional quantum secure communication based on a nonlocal swap gate scheme. Our proposed protocol would be applied to a system in which a controller (supervisor/Charlie) controls the bidirectional communication with quantum information or secret messages between legitimate users (Alice and Bob). In this system, the legitimate users must obtain permission from the controller in order to exchange their respective quantum information or secret messages simultaneously; the controller is unable to obtain any quantum information or secret messages from the decoding process. Moreover, the presence of the controller also avoids the problem of one legitimate user receiving the quantum information or secret message before the other, and then refusing to help the other user decode the quantum information or secret message. Our proposed protocol is aimed at protecting against external and participant attacks on such a system, and the cost of transmitting quantum bits using our protocol is less than that achieved in other studies. Based on the nonlocal swap gate scheme, the legitimate users exchange their quantum information or secret messages without transmission in a public channel, thus protecting against eavesdroppers stealing the secret messages. PMID:25006596

  13. Controlled bidirectional quantum secure direct communication.

    PubMed

    Chou, Yao-Hsin; Lin, Yu-Ting; Zeng, Guo-Jyun; Lin, Fang-Jhu; Chen, Chi-Yuan

    2014-01-01

    We propose a novel protocol for controlled bidirectional quantum secure communication based on a nonlocal swap gate scheme. Our proposed protocol would be applied to a system in which a controller (supervisor/Charlie) controls the bidirectional communication with quantum information or secret messages between legitimate users (Alice and Bob). In this system, the legitimate users must obtain permission from the controller in order to exchange their respective quantum information or secret messages simultaneously; the controller is unable to obtain any quantum information or secret messages from the decoding process. Moreover, the presence of the controller also avoids the problem of one legitimate user receiving the quantum information or secret message before the other, and then refusing to help the other user decode the quantum information or secret message. Our proposed protocol is aimed at protecting against external and participant attacks on such a system, and the cost of transmitting quantum bits using our protocol is less than that achieved in other studies. Based on the nonlocal swap gate scheme, the legitimate users exchange their quantum information or secret messages without transmission in a public channel, thus protecting against eavesdroppers stealing the secret messages.

  14. CELSS system control: issues, methods, and directions.

    PubMed

    Blackwell, C C; Blackwell, A L

    1992-01-01

    In the general control perspective, the CELSS concept implies a very complex system and presents challenges at every level. These challenges are generated by: (1) the prospect that the system will be inherently unstable, (2) the prospective difficulty of establishing an adequate mathematical model of the system for the purpose of control law synthesis (dimensionality is high, and the dynamics and interactive processes of some of the subsystems are not understood well), (3) assuring control law robustness (assuring that the resulting control law(s) will be effective over the domain of the specified uncertainties), (4) hardware realization of the control law, (5) hardware system robustness ("fault tolerance") and (6) achieving the logistics of the automation (or "management") aspects of the problem. A suggested organization of the problem, a sketch of the issues related to perceived difficulties, a commentary/evaluation of the issues, a review of methods available to address the issues, and a suggested strategy to address the broad CELSS systems control problem are presented.

  15. Simplified Key Management for Digital Access Control of Information Objects

    DTIC Science & Technology

    2016-07-02

    encrypting large numbers of information assets. Often, grouping and segmenting objects by type is done to reduce the number of keys needed and hence...recording [2]. The advent of digital media and analog/digital conversion technologies, especially those that are usable on mass- market general...Dean Takahashi, “With online sales growing, video game market to hit $81B by 2016 (exclusive),” 2011. http://venturebeat.com/2011/09/07/with-online

  16. Digital controller design: Analysis of the annular suspension pointing system. [analog controllers with feedback

    NASA Technical Reports Server (NTRS)

    Kuo, B. C.

    1978-01-01

    The analog controllers of the annular suspension pointing system are designed for control of the chi, phi sub 1, and phi sub 2 bandwidth dynamics through decoupling and pole placement. Since it is virtually impossible to find an equivalent bandwidth of the overall system and establish a general eigenvalue requirement for the system, the subsystem dynamics are decoupled through state feedback and the poles are placed simultaneously to realize the desired bandwidths for the three system components. Decoupling and pole placement are also used to design the closed-loop digital system through approximation.

  17. Directions for rf-controlled intelligent microvalve

    NASA Astrophysics Data System (ADS)

    Enderling, Stefan; Varadan, Vijay K.; Abbott, Derek

    2001-03-01

    In this paper, we consider the novel concept of a Radio Frequency (RF) controllable microvalve for different medical applications. Wireless communication via a Surface Acoustic Wave Identification-mark (SAW ID-tag) is used to control, drive and locate the microvalve inside the human body. The energy required for these functions is provided by RF pulses, which are transmitted to the valve and back by a reader/transmitter system outside of the body. These RF bursts are converted into Surface Acoustic Waves (SAWs), which propagate along the piezoelectric actuator material of the microvalve. These waves cause deflections, which are employed to open and close the microvalve. We identified five important areas of application of the microvalve in biomedicine: 1) fertility control; 2) artificial venous valves; 3) flow cytometry; 4) drug delivery and 5) DNA mapping.

  18. Field Programmable Gate Array for Implementation of Redundant Advanced Digital Feedback Control

    NASA Technical Reports Server (NTRS)

    King, K. D.

    2003-01-01

    The goal of this effort was to develop a digital motor controller using field programmable gate arrays (FPGAs). This is a more rugged approach than a conventional microprocessor digital controller. FPGAs typically have higher radiation (rad) tolerance than both the microprocessor and memory required for a conventional digital controller. Furthermore, FPGAs can typically operate at higher speeds. (While speed is usually not an issue for motor controllers, it can be for other system controllers.) Other than motor power, only a 3.3-V digital power supply was used in the controller; no analog bias supplies were used. Since most of the circuit was implemented in the FPGA, no additional parts were needed other than the power transistors to drive the motor. The benefits that FPGAs provide over conventional designs-lower power and fewer parts-allow for smaller packaging and reduced weight and cost.

  19. Toward direct light-to-digital conversion using a pulse-driven hybrid MOS-PN photodetector.

    PubMed

    Sallin, Denis; Koukab, Adil; Kayal, Maher

    2015-02-15

    In this Letter, a direct light-to-digital converter based on an MOS-PN photodetector driven by pulsed voltage is presented. The objective is to avoid any analog-to-digital or time-to-digital conversion and, thereby, to pave the way for a new generation of fully digital imaging sensors with reduced complexity, area, and power consumption. Moreover, the pulsed voltage operation allows for a significant reduction of the dark level. The concept is validated by a theoretical study and TCAD simulations. A first prototype fabricated in 0.18 μm CMOS technology is presented. The experimental results under various light conditions show that the pulsed voltage improves the light sensitivity by several orders of magnitude.

  20. Windmill with direction-controlled feathering

    SciTech Connect

    Weiss, H. G.

    1984-10-02

    A windmill employs a separate wind vane pivotably mounted on the chassis of the windmill. An internal sensor detects the relative angle between the wind vane and the windmill and activates the pitch-control mechanism of the windmill to feather the windmill blades whenever the angle exceeds a predetermined maximum.

  1. 47 CFR 76.1909 - Redistribution control of unencrypted digital terrestrial broadcast content.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... terrestrial broadcast content. 76.1909 Section 76.1909 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... Redistribution control of unencrypted digital terrestrial broadcast content. (a) For the purposes of this section, the terms unencrypted digital terrestrial broadcast content, EIT, PMT, broadcast flag, covered...

  2. Learner-Controlled Scaffolding Linked to Open-Ended Problems in a Digital Learning Environment

    ERIC Educational Resources Information Center

    Edson, Alden Jack

    2017-01-01

    This exploratory study reports on how students activated learner-controlled scaffolding and navigated through sequences of connected problems in a digital learning environment. A design experiment was completed to (re)design, iteratively develop, test, and evaluate a digital version of an instructional unit focusing on binomial distributions and…

  3. Software for the ’Elektronika K-200’ Control Digital Computer,

    DTIC Science & Technology

    The software described in this article has been developed for a specific digital computer. However, it is the opinion of the authors that the group...of principles which form its basis may also be applied in the development of software for other control digital computers.

  4. Analysis and design of digital output interface devices for gas turbine electronic controls

    NASA Technical Reports Server (NTRS)

    Newirth, D. M.; Koenig, E. W.

    1976-01-01

    A trade study was performed on twenty-one digital output interface schemes for gas turbine electronic controls to select the most promising scheme based on criteria of reliability, performance, cost, and sampling requirements. The most promising scheme, a digital effector with optical feedback of the fuel metering valve position, was designed.

  5. Design of active controls for the NASA F-8 digital fly-by-wire airplane

    NASA Technical Reports Server (NTRS)

    Gera, J.

    1976-01-01

    The design of a set of control laws for the NASA F-8 digital fly by wire research airplane is described. These control laws implement several active controls functions: maneuver load control, ride smoothing and departure boundary limiting. The criteria and methods which were used in the design of the control laws are also included. Results of linear analyses and nonlinear simulation are summarized.

  6. Digital Direct-to-Consumer Advertising: A Perfect Storm of Rapid Evolution and Stagnant Regulation

    PubMed Central

    Mackey, Tim K.

    2016-01-01

    The adoption and use of digital forms of direct-to-consumer advertising (also known as "eDTCA") is on the rise. At the same time, the universe of eDTCA is expanding, as technology on Internet-based platforms continues to evolve, from static websites, to social media, and nearly ubiquitous use of mobile devices. However, little is known about how this unique form of pharmaceutical marketing impacts consumer behavior, public health, and overall healthcare utilization. The study by Kim analyzing US Food and Drug Administration (FDA) notices of violations (NOVs) and warning letters regarding online promotional activities takes us in the right direction, but study results raise as many questions as it does answers. Chief among these are unanswered concerns about the unique regulatory challenges posed by the "disruptive" qualities of eDTCA, and whether regulators have sufficient resources and oversight powers to proactively address potential violations. Further, the globalization of eDTCA via borderless Internet-based technologies raises larger concerns about the potential global impact of this form of health marketing unique to only the United States and New Zealand. Collectively, these challenges make it unlikely that regulatory science will be able to keep apace with the continued rapid evolution of eDTCA unless more creative policy solutions are explored. PMID:27239871

  7. A fuzzy logic sliding mode controlled electronic differential for a direct wheel drive EV

    NASA Astrophysics Data System (ADS)

    Ozkop, Emre; Altas, Ismail H.; Okumus, H. Ibrahim; Sharaf, Adel M.

    2015-11-01

    In this study, a direct wheel drive electric vehicle based on an electronic differential system with a fuzzy logic sliding mode controller (FLSMC) is studied. The conventional sliding surface is modified using a fuzzy rule base to obtain fuzzy dynamic sliding surfaces by changing its slopes using the global error and its derivative in a fuzzy logic inference system. The controller is compared with proportional-integral-derivative (PID) and sliding mode controllers (SMCs), which are usually preferred to be used in industry. The proposed controller provides robustness and flexibility to direct wheel drive electric vehicles. The fuzzy logic sliding mode controller, electronic differential system and the overall electrical vehicle mechanism are modelled and digitally simulated by using the Matlab software. Simulation results show that the system with FLSMC has better efficiency and performance compared to those of PID and SMCs.

  8. Direct digital lateral cephalometry: the effects of JPEG compression on image quality.

    PubMed

    Wenger, N A; Tewson, D H T K; McDonald, F

    2006-07-01

    This study used an aluminium test object to assess the effect of the Joint Photographics Expert Group (JPEG) compression algorithm, on direct digital cephalometric image quality. The aluminium block of 15 steps, with 20 holes in each step was radiographed in a Planmeca Proline 2002 digital cephalometric machine with Dimaxis2 software. Six different JPEG compression ratios were used to capture the cephalometric images. These ratios were 60%, 70%, 80%, 90%, TOP QUALITY JPEG (TQJPEG 98%) and TIFF (uncompressed). The images were taken at 68 kV and 12 mA with a 7 s exposure. Six experienced observers viewed the monitor displayed images, which were presented randomly. This was repeated one month later. The number of holes detected by each observer was plotted against each compression ratio. Intra-observer and inter-observer reproducibility was calculated using the Mann-Whitney U-test. Differences between the compression ratios were assessed using a Kruskal-Wallis one-way analysis of variance. When comparing intra-observer reproducibility, it was found that there were only four of 36 comparisons that showed a statistically significant difference (Observer 1: 60% (P=0.004), TQJPEG (P=0.019); Observer 2: TIFF (P=0.005); Observer 3: 90% (P=0.007)). Statistically, there was no significant difference with inter-observer reproducibility. There was no statistically significant difference between the image quality obtained from each compression ratio. The results showed that JPEG compression does not have any effect on the perceptibility of landmarks in the aluminium test object used in this study.

  9. Digital Game Playing and Direct and Indirect Aggression in Early Adolescence: The Roles of Age, Social Intelligence, and Parent-Child Communication

    ERIC Educational Resources Information Center

    Wallenius, Marjut; Punamaki, Raija-Leena; Rimpela, Arja

    2007-01-01

    The roles of age, social intelligence and parent-child communication in moderating the association between digital game playing and direct and indirect aggression were examined in 478 Finnish 10- and 13-year-old schoolchildren based on self-reports. The results confirmed that digital game violence was directly associated with direct aggression,…

  10. Digital Game Playing and Direct and Indirect Aggression in Early Adolescence: The Roles of Age, Social Intelligence, and Parent-Child Communication

    ERIC Educational Resources Information Center

    Wallenius, Marjut; Punamaki, Raija-Leena; Rimpela, Arja

    2007-01-01

    The roles of age, social intelligence and parent-child communication in moderating the association between digital game playing and direct and indirect aggression were examined in 478 Finnish 10- and 13-year-old schoolchildren based on self-reports. The results confirmed that digital game violence was directly associated with direct aggression,…

  11. Digital controller for the Wave Propagation Laboratory's VHF and UHF wind-profiling radars

    NASA Astrophysics Data System (ADS)

    Moran, K.

    1984-09-01

    Principles are described for operation of a digital system that is used to control the operations of a multiple beam stratospheric-tropospheric (ST) radar system. The digital system, referred to as the radar controller, contains the digital logic for generating the necessary pulse sequences for modulation of the radar transmitter, gating the radar's receiver channels, and sequencing the antenna beams. The radar controller also performs digital-to-analog conversion and coherent averaging of the receiver necessary for signal detection in ST radars. The radar controller is controlled internally by a Z80 microprocessor, and the entire system functions as a peripheral device to a host minicomputer. Block diagrams and detailed circuit schematics for all the custom designed electronics are included.

  12. Discussion on software aging management of nuclear power plant safety digital control system.

    PubMed

    Liang, Huihui; Gu, Pengfei; Tang, Jianzhong; Chen, Weihua; Gao, Feng

    2016-01-01

    Managing the aging of digital control systems ensures that nuclear power plant systems are in adequate safety margins during their life cycles. Software is a core component in the execution of control logic and differs between digital and analog control systems. The hardware aging management for the digital control system is similar to that for the analog system, which has matured over decades of study. However, software aging management is still in the exploratory stage. Software aging evaluation is critical given the higher reliability and safety requirements of nuclear power plants. To ensure effective inputs for reliability assessment, this paper provides the required software aging information during the life cycle. Moreover, the software aging management scheme for safety digital control system is proposed on the basis of collected aging information.

  13. Advanced Technology Direction and Control Communications Systems

    DTIC Science & Technology

    1979-07-16

    WORK UN4IT NUMBERS The MITRE Corporation ’ 1820 flolley Madison Blvd. Work Unit 2214G McLean, VJ rginia 22102 Ii. CONTROLLING OFFICE NAME AND ADDRESS...Satellite communications using low power technique. A spread spectrum system being developed by The MITRE Corporation for the Maritime Commission. vI I,: I...300-3000 MHz; SHF (super high frequency), 3-30 GHz; EHF (extra high frequency), 30-300 GHz. 3-3 The MITRE Corporation prepared a survey of

  14. Direct transient stability assessment with excitation control

    SciTech Connect

    Fouad, A.A.; Vittal, V.; Ni, Y.X.; Pota, H.R.; Nodehi, K.; Zein-Eldin, H.M.; Vaahedi, E.; Kim

    1989-02-01

    Recently the authors incorporated the effect of excitation control on the transient energy of a multi-machine power system during the first swing. The models used are: the generator represented by the two-axis model and the exciter represented by one gain, one time constant and one limiter. In this paper the parameters of the newly developed transient energy function, which assumes a constant average internal EMF, are computed. The critical value of this transient energy is determined and its use in transient stability assessment is investigated. A procedure for transient stability assessment using the new energy function has been developed and successfully applied to fault disturbances in two test networks.

  15. Coordination between digit forces and positions: interactions between anticipatory and feedback control.

    PubMed

    Fu, Qiushi; Santello, Marco

    2014-04-01

    Humans adjust digit forces to compensate for trial-to-trial variability in digit placement during object manipulation, but the underlying control mechanisms remain to be determined. We hypothesized that such digit position/force coordination was achieved by both visually guided feed-forward planning and haptic-based feedback control. The question arises about the time course of the interaction between these two mechanisms. This was tested with a task in which subjects generated torque (± 70 N·mm) on a virtual object to control a cursor moving to target positions to catch a falling ball, using a virtual reality environment and haptic devices. The width of the virtual object was varied between large (L) and small (S). These object widths result in significantly different horizontal digit relative positions and require different digit forces to exert the same task torque. After training, subjects were tested with random sequences of L and S widths with or without visual information about object width. We found that visual cues allowed subjects to plan manipulation forces before contact. In contrast, when visual cues were not available to predict digit positions, subjects implemented a "default" digit force plan that was corrected after digit contact to eventually accomplish the task. The time course of digit forces revealed that force development was delayed in the absence of visual cues. Specifically, the appropriate digit force adjustments were made 250-300 ms after initial object contact. This result supports our hypothesis and further reveals that haptic feedback alone is sufficient to implement digit force-position coordination.

  16. A comparative cost analysis of digital fundus imaging and direct fundus examination for assessment of diabetic retinopathy.

    PubMed

    Gomez-Ulla, Francisco; Alonso, Florentina; Aibar, Beatriz; Gonzalez, Francisco

    2008-11-01

    The objective of this study was to compare the cost between two procedures for fundus examination in patients with diabetes. In our setting, two alternatives for fundus examination are available for patients with diabetes. In the first alternative, a digital image is taken with a nonmydriatic fundus camera when the patient is at the endocrinology consultation, and the image is then examined by an ophthalmologist. In the second alternative, a direct fundus examination is made by an ophthalmologist. We calculated the costs of both procedures from both Public Healthcare System (PHS) and patient perspectives using the official scales to compute personnel, consumables, capital cost of equipment, travel expenses, and time loss of the patient caused by attending the consultation. The first alternative (digital fundus image) required 2.69, 0.03, and 1.62 Euros per patient for personnel, consumables, and capital cost of the equipment, respectively. A direct fundus examination was needed in 31% of patients that had an additional cost of 0.97 Euros per patient for the PHS plus 14.97 Euros per patient because of travel cost and loss of income. The second alternative (direct fundus examination) required 2.69, 0.11, and 0.33 Euros per patient for personnel, consumables, and capital cost, respectively. All patients in this second alternative had to attend a consultation that implied travel and loss of income costs. Attending a consultation represented a cost of 48.29 Euros per patient. From the PHS perspective, direct fundus examination is less costly than using digital fundus images. The higher cost of the digital fundus option is a consequence of the higher capital costs required by the equipment needed to obtain the digital image. However, from a global perspective, the digital image alternative is more convenient because the travel cost and loss of income of the patient are lower.

  17. The use of minimum order state observers in digital flight-control systems.

    NASA Technical Reports Server (NTRS)

    Montgomery, R. C.; Hatch, H. G., Jr.

    1972-01-01

    This paper deals with the problem of selecting the 'arbitrary' design parameters of digital state observers when they are being used as a part of a digital flight-control system. A cost index is developed which indicates the output noise caused by input quantization due to analog-to-digital conversion. The cost index assumes that the input quantization error is uniformly distributed over the least-significant-bit of the conversion. Formulas relating the cost index to the observer design parameters are presented. The cost index is minimized with respect to the design parameters using a conjugate gradient algorithm. An example of the theory is presented in which a digital observer is designed so that a satisfactory digital flight-control system is obtained starting from an unacceptable one.

  18. Direct Pattern Control Halftoning of Neugebauer Primaries.

    PubMed

    Morovic, Peter; Morovic, Jan; Gondek, Jay; Ulichney, Robert

    2017-09-01

    Halftoning is a key stage of any printing image processing pipeline. With colorant-channel approaches, a key challenge for matrix-based halftoning is the co-optimization of the matrices used for individual colorants, which becomes increasingly complex and over-constrained as the number of colorants increases. Both choices of screen angles (in clustered-dot cases) or structures, and control over how individual matrices relate to each other and result in over-versus side-by-side printing of the colorants, impose challenging restrictions. The solution presented in this paper relies on the benefits of a halftone area Neugebauer separation pipeline, where local Neugebauer Primary use is specified at each pixel and where halftoning can be performed using a single matrix, regardless of the number of colorants. The provably complete plane dependence of the resulting halftones will be presented among the solution's benefits.

  19. Use of digital ciné-fluoroscopy and catheter-directed techniques to improve and simplify standard vascular procedures.

    PubMed

    Wain, R A; Veith, F J

    1999-06-01

    Digital ciné-fluoroscopy and catheter-directed treatments have become indispensable tools in the armamentarium of surgeons performing vascular procedures. These new technologies not only improve and simplify the performance of standard vascular operations but also allow surgeons to perform a wide range of interventions previously unavailable in the operating room.

  20. A digitally controlled power amplifier with neutralization capacitors for Zigbee™ applications

    NASA Astrophysics Data System (ADS)

    Fei, Jia; Shengxi, Diao; Xuejuan, Zhang; Zhongqian, Fu; Fujiang, Lin

    2012-12-01

    This paper presents a single chip CMOS power amplifier with neutralization capacitors for Zigbee™ system according to IEEE 802.15.4. A novel structure with digital interface is adopted, which allows the output power of a PA to be controlled by baseband signal directly, so there is no need for DAC. The neutralization capacitors will increase reverse isolation. The chip is implemented in SMIC 0.18 μm CMOS technology. Measurement shows that the proposed power amplifier has a 13.5 dB power gain, 3.48 dBm output power and 35.1% PAE at P1dB point. The core area is 0.73 × 0.55 mm2.

  1. Directional control-response compatibility of joystick steered shuttle cars.

    PubMed

    Burgess-Limerick, Robin; Zupanc, Christine M; Wallis, Guy

    2012-01-01

    Shuttle cars are an unusual class of vehicle operated in underground coal mines, sometimes in close proximity to pedestrians and steering errors may have very serious consequences. A directional control-response incompatibility has previously been described in shuttle cars which are controlled using a steering wheel oriented perpendicular to the direction of travel. Some other shuttle car operators are seated perpendicular to the direction of travel and steer the car via a seat mounted joystick. A virtual simulation was utilised to determine whether the steering arrangement in these vehicles maintains directional control-response compatibility. Twenty-four participants were randomly assigned to either a condition corresponding to this design (consistent direction), or a condition in which the directional steering response was reversed while driving in-bye (visual field compatible). Significantly less accurate steering performance was exhibited by the consistent direction group during the in-bye trials only. Shuttle cars which provide the joystick steering mechanism described here require operators to accommodate alternating compatible and incompatible directional control-response relationships with each change of car direction. A virtual simulation of an underground coal shuttle car demonstrates that the design incorporates a directional control-response incompatibility when driving the vehicle in one direction. This design increases the probability of operator error, with potential adverse safety and productivity consequences.

  2. A technique of direct tracing for recording digital range of motion.

    PubMed

    Macionis, Valdas

    2008-04-01

    This report describes a technique for recording range of motion of digital joints. The technique involves tracing digital outlines with an angled marker on a sheet of paper attached to a special interray pad. A complete dorsal silhouette of the entire ray can be obtained by mounting the pad and the paper astride the palm parallel to the ray of the digit being evaluated. Fabrication and use of the equipment is described. This silhouetting system could be an alternative to wire tracing in visualizing tendencies of dynamics of digital range of motion.

  3. Collaborative Corrections with Spelling Control: Digital Resources and Peer Assistance

    ERIC Educational Resources Information Center

    Cekaite, Asta

    2009-01-01

    The present study has explored how pairs of students deployed digital tools (spelling software) as resources in spontaneously occurring corrections of spelling errors. Drawing on the sociocultural theory of learning and ethnomethodological (Conversation Analytic) insights into social interaction, it has identified a range of consistent practices…

  4. Optimization of Control Processes of Digital Electrical Drive Systems

    NASA Astrophysics Data System (ADS)

    Dochviri, J.

    2010-01-01

    The aim of the work is solution of the problems associated with synthesis of the digital speed regulators both for DC and AC thyristor electrical drives. The investigation is realized based on the parameters of continuous technological equipment (e.g. paper-making machine) by taking into account elastic transmission links of the drive systems. Appropriate frequency characteristics and transient processes are described.

  5. 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.

  6. 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

  7. Optical control of the emission direction of a quantum dot

    SciTech Connect

    Luxmoore, I. J.; Wasley, N. A.; Fox, A. M.; Skolnick, M. S.; Ramsay, A. J.; Thijssen, A. C. T.; Oulton, R.; Hugues, M.

    2013-12-09

    Using the helicity of a non-resonant excitation laser, control over the emission direction of an InAs/GaAs quantum dot is demonstrated. The quantum dot is located off-center in a crossed-waveguide structure, such that photons of opposite circular polarization are emitted into opposite waveguide directions. By preferentially exciting spin-polarized excitons, the direction of emission can therefore be controlled. The directional control is quantified by using the ratio of the intensity of the light coupled into the two waveguides, which reaches a maximum of ±35%.

  8. Directional control-response relationships for mining equipment.

    PubMed

    Burgess-Limerick, R; Krupenia, V; Wallis, G; Pratim-Bannerjee, A; Steiner, L

    2010-06-01

    A variety of directional control-response relationships are currently found in mining equipment. Two experiments were conducted in a virtual environment to determine optimal direction control-response relationships in a wide variety of circumstances. Direction errors were measured as a function of control orientation (horizontal or vertical), location (left, front, right) and directional control-response relationships. The results confirm that the principles of consistent direction and visual field compatibility are applicable to the majority of situations. An exception is that fewer direction errors were observed when an upward movement of a horizontal lever or movement of a vertical lever away from the participants caused extension (lengthening) of the controlled device, regardless of whether the direction of movement of the control is consistent with the direction in which the extension occurs. Further, both the control of slew by horizontally oriented controls and the control of device movements in a frontal plane by the perpendicular movements of vertical levers were associated with relatively high rates of directional errors, regardless of the directional control-response relationship, and these situations should be avoided. STATEMENT OF RELEVANCE: The results are particularly applicable to the design of mining equipment such as drilling and bolting machines, and have been incorporated into MDG35.1 Guideline for bolting & drilling plant in mines (Industry & Investment NSW, 2010). The results are also relevant to the design of any equipment where vertical or horizontal levers are used to control the movement of equipment appendages, e.g. cranes mounted to mobile equipment and the like.

  9. Digitally Controllable Current Amplifier and Current Conveyors in Practical Application of Controllable Frequency Filter

    NASA Astrophysics Data System (ADS)

    Polak, Josef; Jerabek, Jan; Langhammer, Lukas; Sotner, Roman; Dvorak, Jan; Panek, David

    2016-07-01

    This paper presents the simulations results in comparison with the measured results of the practical realization of the multifunctional second order frequency filter with a Digitally Adjustable Current Amplifier (DACA) and two Dual-Output Controllable Current Conveyors (CCCII +/-). This filter is designed for use in current mode. The filter was designed of the single input multiple outputs (SIMO) type, therefore it has only one input and three outputs with individual filtering functions. DACA element used in a newly proposed circuit is present in form of an integrated chip and the current conveyors are implemented using the Universal Current Conveyor (UCC) chip with designation UCC-N1B. Proposed frequency filter enables independent control of the pole frequency using parameters of two current conveyors and also independent control of the quality factor by change of a current gain of DACA.

  10. Ongoing quality control in digital radiography: Report of AAPM Imaging Physics Committee Task Group 151

    SciTech Connect

    Jones, A. Kyle Geiser, William; Heintz, Philip; Goldman, Lee; Jerjian, Khachig; Martin, Melissa; Peck, Donald; Pfeiffer, Douglas; Ranger, Nicole; Yorkston, John

    2015-11-15

    Quality control (QC) in medical imaging is an ongoing process and not just a series of infrequent evaluations of medical imaging equipment. The QC process involves designing and implementing a QC program, collecting and analyzing data, investigating results that are outside the acceptance levels for the QC program, and taking corrective action to bring these results back to an acceptable level. The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and the qualified medical physicist (QMP). The QMP performs detailed equipment evaluations and helps with oversight of the QC program, the radiologic technologist is responsible for the day-to-day operation of the QC program. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature. The charge of this task group was to recommend consistency tests designed to be performed by a medical physicist or a radiologic technologist under the direction of a medical physicist to identify problems with an imaging system that need further evaluation by a medical physicist, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of this final report is the ongoing QC process, including rejected image analysis, exposure analysis, and artifact identification. These QC tasks are vital for the optimal operation of a department performing digital radiography.

  11. Ongoing quality control in digital radiography: Report of AAPM Imaging Physics Committee Task Group 151.

    PubMed

    Jones, A Kyle; Heintz, Philip; Geiser, William; Goldman, Lee; Jerjian, Khachig; Martin, Melissa; Peck, Donald; Pfeiffer, Douglas; Ranger, Nicole; Yorkston, John

    2015-11-01

    Quality control (QC) in medical imaging is an ongoing process and not just a series of infrequent evaluations of medical imaging equipment. The QC process involves designing and implementing a QC program, collecting and analyzing data, investigating results that are outside the acceptance levels for the QC program, and taking corrective action to bring these results back to an acceptable level. The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and the qualified medical physicist (QMP). The QMP performs detailed equipment evaluations and helps with oversight of the QC program, the radiologic technologist is responsible for the day-to-day operation of the QC program. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature. The charge of this task group was to recommend consistency tests designed to be performed by a medical physicist or a radiologic technologist under the direction of a medical physicist to identify problems with an imaging system that need further evaluation by a medical physicist, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of this final report is the ongoing QC process, including rejected image analysis, exposure analysis, and artifact identification. These QC tasks are vital for the optimal operation of a department performing digital radiography.

  12. Digital low level rf control system with four different intermediate frequencies for the International Linear Collider

    NASA Astrophysics Data System (ADS)

    Wibowo, Sigit Basuki; Matsumoto, Toshihiro; Michizono, Shinichiro; Miura, Takako; Qiu, Feng; Liu, Na

    2017-09-01

    A field programmable gate array-based digital low level rf (LLRF) control system will be used in the International Linear Collider (ILC) in order to satisfy the rf stability requirements. The digital LLRF control system with four different intermediate frequencies has been developed to decrease the required number of analog-to-digital converters in this system. The proof of concept of this technique was demonstrated at the Superconducting RF Test Facility in the High Energy Accelerator Research Organization, Japan. The amplitude and phase stability has fulfilled the ILC requirements.

  13. Digital servo control of random sound test excitation. [in reverberant acoustic chamber

    NASA Technical Reports Server (NTRS)

    Nakich, R. B. (Inventor)

    1974-01-01

    A digital servocontrol system for random noise excitation of a test object in a reverberant acoustic chamber employs a plurality of sensors spaced in the sound field to produce signals in separate channels which are decorrelated and averaged. The average signal is divided into a plurality of adjacent frequency bands cyclically sampled by a time division multiplex system, converted into digital form, and compared to a predetermined spectrum value stored in digital form. The results of the comparisons are used to control a time-shared up-down counter to develop gain control signals for the respective frequency bands in the spectrum of random sound energy picked up by the microphones.

  14. Direct To Digital Holography For High Aspect Ratio Inspection of Semiconductor Wafers

    NASA Astrophysics Data System (ADS)

    Thomas, C. E. (Tommy); Hunt, Martin A.; Bahm, Tracy M.; Baylor, Larry R.; Bingham, Philip R.; Chidley, Matthew D.; Dai, Xiaolong; Delahanty, Robert J.; El-Khashab, Ayman; Gilbert, Judd M.; Goddard, James S.; Hanson, Gregory R.; Hickson, Joel D.; Hylton, Kathy W.; John, George C.; Jones, Michael L.; Mayo, Michael W.; Marek, Christopher; Price, John H.; Rasmussen, David A.; Schaefer, Louis J.; Schulze, Mark A.; Shen, Bichuan; Smith, Randall G.; Su, Allen N.; Tobin, Kenneth W.; Usry, William R.; Voelkl, Edgar; Weber, Karsten S.; Owen, Robert W.

    2003-09-01

    Direct to Digital Holography (DDH) has been developed as a semiconductor wafer inspection tool and in particular as a tool for seeing defects in high aspect ratio (HAR) structures on semiconductor wafers and also for seeing partial-height defects. While the tool works very well for general wafer inspection, it has unusual capabilities for high aspect ratio inspection (HARI) and for detecting thin residual film defects (partial height defects). Inspection of HAR structures is rated as one of the highest unmet priorities of the member companies of International SEMATECH, and finding residual thin film defects (in some cases called "stringers") is also a very difficult challenge. The capabilities that make DDH unusually sensitive include: 1) the capture of the whole wave—both the classical amplitude captured by traditional optical systems, and the phase of the wave, with phase potentially measured to ˜1/1000'th of a wavelength or ˜2 to 3 Angstroms for a deep ultra-violet (DUV) laser; 2) heterodyne detection—this allows it to capture very low signal levels; and 3) a head-on geometry using a collimated laser beam that allows best penetration of HAR structures. The basic features and methods of this patented technology are presented, along with simple calculations of signal strength and expected noise levels for various circumstances. Full-wave numerical calculations of electromagnetic field penetration into HAR contacts and experimental results from various wafer types and structures are also presented.

  15. Direct-to-digital holography reduction of reference hologram noise and fourier space smearing

    DOEpatents

    Voelkl, Edgar

    2006-06-27

    Systems and methods are described for reduction of reference hologram noise and reduction of Fourier space smearing, especially in the context of direct-to-digital holography (off-axis interferometry). A method of reducing reference hologram noise includes: recording a plurality of reference holograms; processing the plurality of reference holograms into a corresponding plurality of reference image waves; and transforming the corresponding plurality of reference image waves into a reduced noise reference image wave. A method of reducing smearing in Fourier space includes: recording a plurality of reference holograms; processing the plurality of reference holograms into a corresponding plurality of reference complex image waves; transforming the corresponding plurality of reference image waves into a reduced noise reference complex image wave; recording a hologram of an object; processing the hologram of the object into an object complex image wave; and dividing the complex image wave of the object by the reduced noise reference complex image wave to obtain a reduced smearing object complex image wave.

  16. DNA nanomechanics allows direct digital detection of complementary DNA and microRNA targets.

    PubMed

    Husale, Sudhir; Persson, Henrik H J; Sahin, Ozgur

    2009-12-24

    Techniques to detect and quantify DNA and RNA molecules in biological samples have had a central role in genomics research. Over the past decade, several techniques have been developed to improve detection performance and reduce the cost of genetic analysis. In particular, significant advances in label-free methods have been reported. Yet detection of DNA molecules at concentrations below the femtomolar level requires amplified detection schemes. Here we report a unique nanomechanical response of hybridized DNA and RNA molecules that serves as an intrinsic molecular label. Nanomechanical measurements on a microarray surface have sufficient background signal rejection to allow direct detection and counting of hybridized molecules. The digital response of the sensor provides a large dynamic range that is critical for gene expression profiling. We have measured differential expressions of microRNAs in tumour samples; such measurements have been shown to help discriminate between the tissue origins of metastatic tumours. Two hundred picograms of total RNA is found to be sufficient for this analysis. In addition, the limit of detection in pure samples is found to be one attomolar. These results suggest that nanomechanical read-out of microarrays promises attomolar-level sensitivity and large dynamic range for the analysis of gene expression, while eliminating biochemical manipulations, amplification and labelling.

  17. Index to ring digit ratio in Saudi Arabia at Almadinah Almonawarah province: a direct and indirect measurement study

    PubMed Central

    Almasry, Shaima M; El Domiaty, Magda A; Algaidi, Sami A; Elbastawisy, Yasser M; Safwat, Maha D

    2011-01-01

    The digit ratio, or the relative lengths, of the 2nd and 4th digits (2D : 4D) shows a sex difference, with males tending to have lower values in comparison with females. This sex differences arises early in the fetus and may result from the effects of prenatal testosterone and estrogen on the relative growth rate of the 2nd and 4th digits. This study aimed to estimate finger lengths and the 2D : 4D ratios for the first time in Saudi Arabian subjects using direct and indirect measurements, and to evaluate the correlations between both indirect and direct 2D : 4D with adult testosterone and various sexually dimorphic physical traits. The results revealed the following: (i) mean 2D : 4D in Saudi Arabian samples varied from 0.96 to 0.99; (ii) mean 2D : 4D was lower for indirect compared to direct 2D : 4D; (iii) sex differences in indirect 2D : 4D were higher than in direct 2D : 4D measurements; (iv) there were no significant correlations between indirect or direct 2D : 4D and testosterone level; (v) there were four significant correlations between direct 2D : 4D and body size traits but no significant correlations between indirect 2D : 4D and body size. PMID:21044064

  18. Apollo experience report: Guidance and control systems - Digital autopilot design development

    NASA Technical Reports Server (NTRS)

    Peters, W. H.; Cox, K. J.

    1973-01-01

    The development of the Apollo digital autopilots (the primary attitude control systems that were used for all phases of the lunar landing mission) is summarized. This report includes design requirements, design constraints, and design philosophy. The development-process functions and the essential information flow paths are identified. Specific problem areas that existed during the development are included. A discussion is also presented on the benefits inherent in mechanizing attitude-controller logic and dynamic compensation in a digital computer.

  19. Modular system for data acquisition and control of experiments with digital output

    NASA Astrophysics Data System (ADS)

    Calabria, Mauro F.; Deza, Roberto R.

    2010-11-01

    In the present work, the design of an efficient, modular, and scalable data acquisition and control system is described. It consists of an array of microcontrollers and memories, which feed a single concentrating unit whose information can be accessed by means of a universal series bus (USB) interface to be processed later on. Signal levels can be controlled through a set of digital potentiometers. This system is ideal for experiments with a large number of digital outputs.

  20. An efficient assignment of drainage direction over flat surfaces in raster digital elevation models

    NASA Astrophysics Data System (ADS)

    Barnes, Richard; Lehman, Clarence; Mulla, David

    2014-01-01

    In processing raster digital elevation models (DEMs) it is often necessary to assign drainage directions over flats-that is, over regions with no local elevation gradient. This paper presents an approach to drainage direction assignment which is not restricted by a flat's shape, number of outlets, or surrounding topography. Flow is modeled by superimposing a gradient away from higher terrain with a gradient towards lower terrain resulting in a drainage field exhibiting flow convergence, an improvement over methods which produce regions of parallel flow. This approach builds on previous work by Garbrecht and Martz (1997), but presents several important improvements. The improved algorithm guarantees that flats are only resolved if they have outlets. The algorithm does not require iterative application; a single pass is sufficient to resolve all flats. The algorithm presents a clear strategy for identifying flats and their boundaries. The algorithm is not susceptible to loss of floating-point precision. Furthermore, the algorithm is efficient, operating in O(N) time whereas the older algorithm operates in O(N) time. In testing, the improved algorithm ran 6.5 times faster than the old for a 100×100 cell flat and 69 times faster for a 700×700 cell flat. In tests on actual DEMs, the improved algorithm finished its processing 38-110 times sooner while running on a single processor than a parallel implementation of the old algorithm did while running on 16 processors. The improved algorithm is an optimal, accurate, easy-to-implement drop-in replacement for the original. Pseudocode is provided in the paper and working source code is provided in the Supplemental Materials.

  1. Error control for reliable digital data transmission and storage systems

    NASA Technical Reports Server (NTRS)

    Costello, D. J., Jr.; Deng, R. H.

    1985-01-01

    A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. In this paper we present some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative alorithm to find the error locator polynomial. Two codes are considered: (1) a d sub min = 4 single-byte-error-correcting (SBEC), double-byte-error-detecting (DBED) RS code; and (2) a d sub min = 6 double-byte-error-correcting (DBEC), triple-byte-error-detecting (TBED) RS code.

  2. Development of a digital guidance and control law for steep approach automatic landings using modern control techniques

    NASA Technical Reports Server (NTRS)

    Halyo, N.

    1979-01-01

    The development of a digital automatic control law for a small jet transport to perform a steep final approach in automatic landings is reported along with the development of a steady-state Kalman filter used to provide smooth estimates to the control law. The control law performs the functions of localizer and glides capture, localizer and glideslope track, decrab, and place. The control law uses the microwave landing system position data, and aircraft body-mounted accelerators, attitude and attitude rate information. The results obtained from a digital simulation of the aircraft dynamics, wind conditions, and sensor noises using the control law and filter developed are described.

  3. A satellite digital controller or 'play that PID tune again, Sam'. [Position, Integral, Derivative feedback control algorithm for design strategy

    NASA Technical Reports Server (NTRS)

    Seltzer, S. M.

    1976-01-01

    The problem discussed is to design a digital controller for a typical satellite. The controlled plant is considered to be a rigid body acting in a plane. The controller is assumed to be a digital computer which, when combined with the proposed control algorithm, can be represented as a sampled-data system. The objective is to present a design strategy and technique for selecting numerical values for the control gains (assuming position, integral, and derivative feedback) and the sample rate. The technique is based on the parameter plane method and requires that the system be amenable to z-transform analysis.

  4. A satellite digital controller or 'play that PID tune again, Sam'. [Position, Integral, Derivative feedback control algorithm for design strategy

    NASA Technical Reports Server (NTRS)

    Seltzer, S. M.

    1976-01-01

    The problem discussed is to design a digital controller for a typical satellite. The controlled plant is considered to be a rigid body acting in a plane. The controller is assumed to be a digital computer which, when combined with the proposed control algorithm, can be represented as a sampled-data system. The objective is to present a design strategy and technique for selecting numerical values for the control gains (assuming position, integral, and derivative feedback) and the sample rate. The technique is based on the parameter plane method and requires that the system be amenable to z-transform analysis.

  5. Low-to-Medium Power Single Chip Digital Controlled DC-DC Regulator for Point-of-Load Applications

    NASA Technical Reports Server (NTRS)

    Adell, Philippe C. (Inventor); Bakkaloglu, Bertan (Inventor); Vermeire, Bert (Inventor); Liu, Tao (Inventor)

    2015-01-01

    A DC-DC converter for generating a DC output voltage includes: a digitally controlled pulse width modulator (DPWM) for controlling a switching power stage to supply a varying voltage to an inductor; and a digital voltage feedback circuit for controlling the DPWM in accordance with a feedback voltage corresponding to the DC output voltage, the digital voltage feedback circuit including: a first voltage controlled oscillator for converting the feedback voltage into a first frequency signal and to supply the first frequency signal to a first frequency discriminator; a second voltage controlled oscillator for converting a reference voltage into a second frequency signal and to supply the second frequency signal to a second frequency discriminator; a digital comparator for comparing digital outputs of the first and second frequency discriminators and for outputting a digital feedback signal; and a controller for controlling the DPWM in accordance with the digital feedback signal.

  6. Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Flight evaluation in an F-15 aircraft by digital electronic engine control (DEEC) was investigated. Topics discussed include: system description, F100 engine tests, effects of inlet distortion on static pressure probe, flight tests, digital electronic engine control fault detection and accommodation flight evaluation, flight evaluation of a hydromechanical backup control, augmentor transient capability of an F100 engine, investigation of nozzle instability, real time in flight thrust calculation, and control technology for future aircraft propulsion systems. It is shown that the DEEC system is a powerful and flexible controller for the F100 engine.

  7. Digital mental health and intellectual disabilities: state of the evidence and future directions.

    PubMed

    Sheehan, Rory; Hassiotis, Angela

    2017-09-25

    The use of digital technologies in the management of mental illness, and more generally in the promotion of well-being and mental health, has received much recent attention and is a focus of current health policy. We conducted a narrative review to explore the opportunities and risks of digital technologies in mental healthcare specifically for people with intellectual disability, a sometimes marginalised and socially excluded group. The scope of digital mental health is vast and the promise of cheaper and more effective interventions delivered digitally is attractive. People with intellectual disability experience high rates of mental illness and could benefit from the development of novel therapies, yet seem to have been relatively neglected in the discourse around digital mental health and are often excluded from the development and implementation of new interventions. People with intellectual disability encounter several barriers to fully embracing digital technology, which may be overcome with appropriate support and adaptations. A small, but growing, literature attests to the value of incorporating digital technologies into the lives of people with intellectual disability, not only for promoting health but also for enhancing educational, vocational and leisure opportunities. Clearly further evidence is needed to establish the safety and clinical efficacy of digital mental health interventions for people with and without intellectual disability. A digital inclusion strategy that explicitly addresses the needs of people with intellectual disability would ensure that all can share the benefits of the digital world. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  8. Digitally controlled fault-tolerant multiwavelength programmable fiber-optic attenuator using a two-dimensional digital micromirror device.

    PubMed

    Riza, N A; Sumriddetchkajorn, S

    1999-03-01

    A digitally controlled multiwavelength variable fiber-optic attenuator using a two-dimensional digital micromirror device (DMD) is introduced. The results from an experimental four-wavelength (i.e., 1546.92, 1548.52, 1550.12, and 1551.72 nm) proof-of-concept attenuator indicate a 26-dB dynamic range and 11-bit resolution. The measured attenuator average coherent optical cross talk per wavelength channel is -38 dB , limited by the additive noise resulting from the nonideal isolation of the optical circulator and the attenuator module. The average optical loss for our experimental attenuator is 15 dB and is limited mainly by the visible-mode DMD that is used as a 1550-nm infrared window device. Our theoretical estimate of a <8-dB loss optimized attenuator can be used for equalization in multiwavelength fiber-optic communications with as many as 108 wavelengths.

  9. Test and control computer user's guide for a digital beam former test system

    NASA Technical Reports Server (NTRS)

    Alexovich, Robert E.; Mallasch, Paul G.

    1992-01-01

    A Digital Beam Former Test System was developed to determine the effects of noise, interferers and distortions, and digital implementations of beam forming as applied to the Tracking and Data Relay Satellite 2 (TDRS 2) architectures. The investigation of digital beam forming with application to TDRS 2 architectures, as described in TDRS 2 advanced concept design studies, was conducted by the NASA/Lewis Research Center for NASA/Goddard Space Flight Center. A Test and Control Computer (TCC) was used as the main controlling element of the digital Beam Former Test System. The Test and Control Computer User's Guide for a Digital Beam Former Test System provides an organized description of the Digital Beam Former Test System commands. It is written for users who wish to conduct tests of the Digital Beam forming Test processor using the TCC. The document describes the function, use, and syntax of the TCC commands available to the user while summarizing and demonstrating the use of the commands wtihin DOS batch files.

  10. Digital TV-echelle spectrograph for simultaneous multielemental analysis using microcomputer control

    SciTech Connect

    Davidson, J.B.; Case, A.L.

    1980-12-01

    A digital TV-echelle spectrograph with microcomputer control was developed for simultaneous multielemental analysis. The optical system is a commercially available unit originally equipped for film and photomultiplier (single element) readout. The film port was adapted for the intensifier camera. The camera output is digitized and stored in a microcomputer-controlled, 512 x 512 x 12 bit memory and image processor. Multiple spectra over the range of 200 to 800 nm are recorded in a single exposure. Spectra lasting from nanoseconds to seconds are digitized and stored in 0.033 s and displayed on a TV monitor. An inexpensive microcomputer controls the exposure, reads and displays the intensity of predetermined spectral lines, and calculates wavelengths of unknown lines. The digital addresses of unknown lines are determined by superimposing a cursor on the TV display. The microcomputer also writes into memory wavelength fiducial marks for alignment of the TV camera.

  11. Tremor suppression using functional electrical stimulation: a comparison between digital and analog controllers.

    PubMed

    Gillard, D M; Cameron, T; Prochazka, A; Gauthier, M J

    1999-09-01

    In this study, we compared digital and analog versions of a functional electrical stimulator designed to suppress tremor. The device was based on a closed-loop control system designed to attenuate movements in the tremor frequency range, without significantly affecting slower, voluntary movements. Testing of the digital filter was done on three patients with Parkinsonian tremor and the results compared to those of a functional electrical stimulation device based on an analog filter evaluated in a previous study. Additional testing of both the analog and digital filters was done on three subjects with no neurological impairment performing tremor-like movements and slow voluntary movements. We found that the digital controller provided a mean attenuation of 84%, compared to 65% for the analog controller.

  12. The digital implementation of control compensators: The coefficient wordlength issue

    NASA Technical Reports Server (NTRS)

    Moroney, P.; Willsky, A. S.; Houpt, P. K.

    1979-01-01

    There exists a number of mathematical procedures for designing discrete-time compensators. However, the digital implementation of these designs, with a microprocessor for example, has not received nearly as thorough an investigation. The finite-precision nature of the digital hardware makes it necessary to choose an algorithm (computational structure) that will perform 'well-enough' with regard to the initial objectives of the design. This paper describes a procedure for estimating the required fixed-point coefficient wordlength for any given computational structure for the implementation of a single-input single-output LOG design. The results are compared to the actual number of bits necessary to achieve a specified performance index.

  13. Digit Position and Forces Covary during Anticipatory Control of Whole-Hand Manipulation

    PubMed Central

    Marneweck, Michelle; Lee-Miller, Trevor; Santello, Marco; Gordon, Andrew M.

    2016-01-01

    Theoretical perspectives on anticipatory planning of object manipulation have traditionally been informed by studies that have investigated kinematics (hand shaping and digit position) and kinetics (forces) in isolation. This poses limitations on our understanding of the integration of such domains, which have recently been shown to be strongly interdependent. Specifically, recent studies revealed strong covariation of digit position and load force during the loading phase of two-digit grasping. Here, we determined whether such digit force-position covariation is a general feature of grasping. We investigated the coordination of digit position and forces during five-digit whole-hand manipulation of an object with a variable mass distribution. Subjects were instructed to prevent object roll during the lift. As found in precision grasping, there was strong trial-to-trial covariation of digit position and force. This suggests that the natural variation of digit position that is compensated for by trial-to-trial variation in digit forces is a fundamental feature of grasp control, and not only specific to precision grasp. However, a main difference with precision grasping was that modulation of digit position to the object’s mass distribution was driven predominantly by the thumb, with little to no modulation of finger position. Modulation of thumb position rather than fingers is likely due to its greater range of motion and therefore adaptability to object properties. Our results underscore the flexibility of the central nervous system in implementing a range of solutions along the digit force-to-position continuum for dexterous manipulation. PMID:27695406

  14. Fully digital controlled A.C. servo engraving machine based on DEC4DA

    NASA Astrophysics Data System (ADS)

    Shu, Zhibing; Chen, Xianfeng; Zhang, Hairong; Huang, Yiqun; Yan, Caizhong

    2005-12-01

    A novel engraving machine (NUT-1A) is presented, in which fully digital controlled AC system based on DEC4DA was used to improve the machining precision and sensitivity. This engraving machine was constructed around AC servo motor with encoder, controlled by a servo motor control card - DEC4DA. As the upper unit of AC servo motor, DEC4DA was a numerical control generator, which received pulses form CPU by ISA bus, and these pulses were amplified and converted to drive AC servo actuator. This novel engraving machine can achieve a higher positioning accuracy of +/-0.01mm and positioning repetition of +/-0.005mm, and its resolution is 0.001mm/0.0001mm. Moreover, because of multi-closed loops were used in the system, the steady and transient performances are more excellent. This system ensures a much quicker current regulation in closed-loop operation, of acceleration and braking in both directions, as well as stable speed characteristics. Amplifier boards are protected against excessive current, excessive temperature and short circuiting of the motor supply cables.

  15. A Nonlinear Digital Control Solution for a DC/DC Power Converter

    NASA Technical Reports Server (NTRS)

    Zhu, Minshao

    2002-01-01

    A digital Nonlinear Proportional-Integral-Derivative (NPID) control algorithm was proposed to control a 1-kW, PWM, DC/DC, switching power converter. The NPID methodology is introduced and a practical hardware control solution is obtained. The design of the controller was completed using Matlab (trademark) Simulink, while the hardware-in-the-loop testing was performed using both the dSPACE (trademark) rapid prototyping system, and a stand-alone Texas Instruments (trademark) Digital Signal Processor (DSP)-based system. The final Nonlinear digital control algorithm was implemented and tested using the ED408043-1 Westinghouse DC-DC switching power converter. The NPID test results are discussed and compared to the results of a standard Proportional-Integral (PI) controller.

  16. Development and flight test experiences with a flight-crucial digital control system

    NASA Technical Reports Server (NTRS)

    Mackall, Dale A.

    1988-01-01

    Engineers and scientists in the advanced fighter technology integration (AFTI) F-16 program investigated the integration of emerging technologies into an advanced fighter aircraft. AFTI's three major technologies included: flight-crucial digital control, decoupled aircraft flight control, and integration of avionics, flight control, and pilot displays. In addition to investigating improvements in fighter performance, researchers studied the generic problems confronting the designers of highly integrated flight-crucial digital control. An overview is provided of both the advantages and problems of integration digital control systems. Also, an examination of the specification, design, qualification, and flight test life-cycle phase is provided. An overview is given of the fault-tolerant design, multimoded decoupled flight control laws, and integrated avionics design. The approach to qualifying the software and system designs is discussed, and the effects of design choices on system qualification are highlighted.

  17. A Nonlinear Digital Control Solution for a DC/DC Power Converter

    NASA Astrophysics Data System (ADS)

    Zhu, Minshao

    2002-02-01

    A digital Nonlinear Proportional-Integral-Derivative (NPID) control algorithm was proposed to control a 1-kW, PWM, DC/DC, switching power converter. The NPID methodology is introduced and a practical hardware control solution is obtained. The design of the controller was completed using Matlab (trademark) Simulink, while the hardware-in-the-loop testing was performed using both the dSPACE (trademark) rapid prototyping system, and a stand-alone Texas Instruments (trademark) Digital Signal Processor (DSP)-based system. The final Nonlinear digital control algorithm was implemented and tested using the ED408043-1 Westinghouse DC-DC switching power converter. The NPID test results are discussed and compared to the results of a standard Proportional-Integral (PI) controller.

  18. Network device interface for digitally interfacing data channels to a controller via a network

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

    2006-01-01

    The present invention provides a network device interface and method for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is then converted into digital signals and transmitted back to the controller. In one embodiment, the bus controller sends commands and data a defined bit rate, and the network device interface senses this bit rate and sends data back to the bus controller using the defined bit rate.

  19. Demonstrative fractional order - PID controller based DC motor drive on digital platform.

    PubMed

    Khubalkar, Swapnil W; Junghare, Anjali S; Aware, Mohan V; Chopade, Amit S; Das, Shantanu

    2017-09-21

    In industrial drives applications, fractional order controllers can exhibit phenomenal impact due to realization through digital implementation. Digital fractional order controllers have created wide scope as it possess the inherent advantages like robustness against the plant parameter variation. This paper provides brief design procedure of fractional order proportional-integral-derivative (FO-PID) controller through the indirect approach of approximation using constant phase technique. The new modified dynamic particle swarm optimization (IdPSO) technique is proposed to find controller parameters. The FO-PID controller is implemented using floating point digital signal processor. The building blocks are designed and assembled with all peripheral components for the 1.5kW industrial DC motor drive. The robust operation for parametric variation is ascertained by testing the controller with two separately excited DC motors with the same rating but different parameters. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  20. Backup control airstart performance on a digital electronic engine control-equipped F100-engine

    NASA Technical Reports Server (NTRS)

    Johnson, J. B.

    1984-01-01

    The air start capability of a backup control (BUC) was tested for a digital electronic engine control (DEEC) equipped F100 engine, which was installed in an F-15 aircraft. Two air start schedules were tested. Using the group 1 start schedule, based on a 40 sec timer, an air speed of 300 knots was required to ensure successful 40 and 25% BUC mode spooldown airstarts. If core rotor speed (N2) was less than 40% a stall would occur when the start bleed closed, 40 sec after initiation of the air start. All jet fuel starter (JFS) assisted air starts were successful with the group 1 start schedule. For the group 2 schedule, the time between pressurization and start bleed closure ranged between 50 sec and 72 sec. Idle rps was lower than the desired 65% for air starts at higher altitudes and lower air speeds.

  1. Tailoring automatic exposure control toward constant detectability in digital mammography.

    PubMed

    Salvagnini, Elena; Bosmans, Hilde; Struelens, Lara; Marshall, Nicholas W

    2015-07-01

    The automatic exposure control (AEC) modes of most full field digital mammography (FFDM) systems are set up to hold pixel value (PV) constant as breast thickness changes. This paper proposes an alternative AEC mode, set up to maintain some minimum detectability level, with the ultimate goal of improving object detectability at larger breast thicknesses. The default "opdose" AEC mode of a Siemens MAMMOMAT Inspiration FFDM system was assessed using poly(methyl methacrylate) (PMMA) of thickness 20, 30, 40, 50, 60, and 70 mm to find the tube voltage and anode/filter combination programmed for each thickness; these beam quality settings were used for the modified AEC mode. Detectability index (d'), in terms of a non-prewhitened model observer with eye filter, was then calculated as a function of tube current-time product (mAs) for each thickness. A modified AEC could then be designed in which detectability never fell below some minimum setting for any thickness in the operating range. In this study, the value was chosen such that the system met the achievable threshold gold thickness (Tt) in the European guidelines for the 0.1 mm diameter disc (i.e., Tt ≤ 1.10 μm gold). The default and modified AEC modes were compared in terms of contrast-detail performance (Tt), calculated detectability (d'), signal-difference-to-noise ratio (SDNR), and mean glandular dose (MGD). The influence of a structured background on object detectability for both AEC modes was examined using a CIRS BR3D phantom. Computer-based CDMAM reading was used for the homogeneous case, while the images with the BR3D background were scored by human observers. The default opdose AEC mode maintained PV constant as PMMA thickness increased, leading to a reduction in SDNR for the homogeneous background 39% and d' 37% in going from 20 to 70 mm; introduction of the structured BR3D plate changed these figures to 22% (SDNR) and 6% (d'), respectively. Threshold gold thickness (0.1 mm diameter disc) for the default

  2. Tailoring automatic exposure control toward constant detectability in digital mammography

    SciTech Connect

    Salvagnini, Elena; Bosmans, Hilde; Struelens, Lara; Marshall, Nicholas W.

    2015-07-15

    Purpose: The automatic exposure control (AEC) modes of most full field digital mammography (FFDM) systems are set up to hold pixel value (PV) constant as breast thickness changes. This paper proposes an alternative AEC mode, set up to maintain some minimum detectability level, with the ultimate goal of improving object detectability at larger breast thicknesses. Methods: The default “OPDOSE” AEC mode of a Siemens MAMMOMAT Inspiration FFDM system was assessed using poly(methyl methacrylate) (PMMA) of thickness 20, 30, 40, 50, 60, and 70 mm to find the tube voltage and anode/filter combination programmed for each thickness; these beam quality settings were used for the modified AEC mode. Detectability index (d′), in terms of a non-prewhitened model observer with eye filter, was then calculated as a function of tube current-time product (mAs) for each thickness. A modified AEC could then be designed in which detectability never fell below some minimum setting for any thickness in the operating range. In this study, the value was chosen such that the system met the achievable threshold gold thickness (T{sub t}) in the European guidelines for the 0.1 mm diameter disc (i.e., T{sub t} ≤ 1.10 μm gold). The default and modified AEC modes were compared in terms of contrast-detail performance (T{sub t}), calculated detectability (d′), signal-difference-to-noise ratio (SDNR), and mean glandular dose (MGD). The influence of a structured background on object detectability for both AEC modes was examined using a CIRS BR3D phantom. Computer-based CDMAM reading was used for the homogeneous case, while the images with the BR3D background were scored by human observers. Results: The default OPDOSE AEC mode maintained PV constant as PMMA thickness increased, leading to a reduction in SDNR for the homogeneous background 39% and d′ 37% in going from 20 to 70 mm; introduction of the structured BR3D plate changed these figures to 22% (SDNR) and 6% (d′), respectively

  3. Goal-direction and top-down control.

    PubMed

    Buschman, Timothy J; Miller, Earl K

    2014-11-05

    We review the neural mechanisms that support top-down control of behaviour and suggest that goal-directed behaviour uses two systems that work in concert. A basal ganglia-centred system quickly learns simple, fixed goal-directed behaviours while a prefrontal cortex-centred system gradually learns more complex (abstract or long-term) goal-directed behaviours. Interactions between these two systems allow top-down control mechanisms to learn how to direct behaviour towards a goal but also how to guide behaviour when faced with a novel situation.

  4. Goal-direction and top-down control

    PubMed Central

    Buschman, Timothy J.; Miller, Earl K.

    2014-01-01

    We review the neural mechanisms that support top-down control of behaviour and suggest that goal-directed behaviour uses two systems that work in concert. A basal ganglia-centred system quickly learns simple, fixed goal-directed behaviours while a prefrontal cortex-centred system gradually learns more complex (abstract or long-term) goal-directed behaviours. Interactions between these two systems allow top-down control mechanisms to learn how to direct behaviour towards a goal but also how to guide behaviour when faced with a novel situation. PMID:25267814

  5. Seminar on Understanding Digital Control and Analysis in Vibration Test Systems

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The advantages of the digital methods over the analog vibration methods are demonstrated. The following topics are covered: (1) methods of computer-controlled random vibration and reverberation acoustic testing, (2) methods of computer-controlled sinewave vibration testing, and (3) methods of computer-controlled shock testing. General algorithms are described in the form of block diagrams and flow diagrams.

  6. Digital generation and control of Hermite-Gaussian modes with an amplitude digital micromirror device

    NASA Astrophysics Data System (ADS)

    Ren, Yu-Xuan; Fang, Zhao-Xiang; Gong, Lei; Huang, Kun; Chen, Yue; Lu, Rong-De

    2015-12-01

    Hermite-Gaussian (HG) mode, as one of the fundamental transverse electromagnetic modes, has significant advantages in various applications including quantum entanglement, guidance of ultracold atoms and particle acceleration, some of which require complex manipulation (such as dynamic creation and arbitrary three-dimensional spatial transformation with challenges) over HG modes. We report the dynamic creation of a transversely rotated HG mode along its propagating axis with the help of a fast amplitude digital micromirror device (DMD) and a binary encoding technique. Furthermore, this mechanism can also realize the dynamic deformation from a traditional HG beam to a vortex HG beam, which provides a deep insight into the detailed formation of optical vortex singularity in a light beam and would benefit across singular optics and optical manipulation.

  7. Adaptive Fuzzy Control of a Direct Drive Motor

    NASA Technical Reports Server (NTRS)

    Medina, E.; Kim, Y. T.; Akbaradeh-T., M. -R.

    1997-01-01

    This paper presents a state feedback adaptive control method for position and velocity control of a direct drive motor. The proposed control scheme allows for integrating heuristic knowledge with mathematical knowledge of a system. It performs well even when mathematical model of the system is poorly understood. The controller consists of an adaptive fuzzy controller and a supervisory controller. The supervisory controller requires only knowledge of the upper bound and lower bound of the system parameters. The fuzzy controller is based on fuzzy basis functions and states of the system. The adaptation law is derived based on the Lyapunov function which ensures that the state of the system asymptotically approaches zero. The proposed controller is applied to a direct drive motor with payload and parameter uncertainty, and the effectiveness is verified by simulation results.

  8. Adaptive Fuzzy Control of a Direct Drive Motor: Experimental Aspects

    NASA Technical Reports Server (NTRS)

    Medina, E.; Akbarzadeh-T, M.-R.; Kim, Y. T.

    1998-01-01

    This paper presents a state feedback adaptive control method for position and velocity control of a direct drive motor. The proposed control scheme allows for integrating heuristic knowledge with mathematical knowledge of a system. It performs well even when mathematical model of the system is poorly understood. The controller consists of an adaptive fuzzy controller and a supervisory controller. The supervisory controller requires only knowledge of the upper bound and lower bound of the system parameters. The fuzzy controller is based on fuzzy basis functions and states of the system. The adaptation law is derived based on the Lyapunov function which ensures that the state of the system asymptotically approaches zero. The proposed controller is applied to a direct drive motor with payload and parameter uncertainty, and the effectiveness is experimentally verified. The real-time performance is compared with simulation results.

  9. Description directed control: its implications for natural language generation

    SciTech Connect

    Mcdonald, D.D.

    1983-01-01

    This paper proposes a very specifically constrained virtual machine design for goal-directed natural language generation based on a refinement of the technique of data-directed control that the author has termed description-directed control. Important psycholinguistic properties of generation follow inescapably from the use of this control technique, including: efficient runtimes, bounded lookahead, indelible decisions, incremental production of the text, and inescapable adherence to gramaticality. The technique also provides a possible explanation for some well-known universal constraints, though this cannot be confirmed without further empirical investigation. 29 references.

  10. 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.

  11. Development of the HIDEC inlet integration mode. [Highly Integrated Digital Electronic Control

    NASA Technical Reports Server (NTRS)

    Chisholm, J. D.; Nobbs, S. G.; Stewart, J. F.

    1990-01-01

    The Highly Integrated Digital Electronic Control (HIDEC) development program conducted at NASA-Ames/Dryden will use an F-15 test aircraft for flight demonstration. An account is presently given of the HIDEC Inlet Integration mode's design concept, control law, and test aircraft implementation, with a view to its performance benefits. The enhancement of performance is a function of the use of Digital Electronic Engine Control corrected engine airflow computations to improve the scheduling of inlet ramp positions in real time; excess thrust can thereby be increased by 13 percent at Mach 2.3 and 40,000 ft. Aircraft supportability is also improved through the obviation of inlet controllers.

  12. Theoretical analysis of a pressure setting and control system with PWM direction control valve

    NASA Astrophysics Data System (ADS)

    Avram, M.; Duminică, D.; Cartal, L. A.

    2016-08-01

    The paper tackles theoretical aspects concerning an original automated system that sets and controls the pressure inside a tank chamber of fixed volume. The structure of the system integrates an original device developed and designed by the authors. The device digitally controls the one way flow of the working fluid using pulse width modulation, allowing the free flow in the other way. The purpose of this research stage was the theoretical establishing of the variation law of the pressure inside the controlled chamber.

  13. Design and flight testing of a digital optimal control general aviation autopilot

    NASA Technical Reports Server (NTRS)

    Broussard, J. R.; Downing, D. R.; Bryant, W. H.

    1982-01-01

    This paper presents the designs of Proportional-Integral-Filter (PIF) autopilots for a General Aviation (NAVION) aircraft. The PIF autopilots use modern control theory to determine heading select and altitude select and hold autopilot modes. The PIF control law uses typical General Aviation sensors for state feedback; command error integration for command tracking; digital complimentary filtering and analog prefiltering for sensor noise suppression; a control filter for computation delay accommodation; and the incremental form to eliminate trim values in implementation. Theoretical developments for the control law are described which combine the sampled-data regulator with command generator tracking for use as a digital flight control system. The digital PIF autopilots are evaluated using closed-loop eigenvalues and simulations. Successful flight test results for the PIF autopilots are presented for different turbulence conditions and quadratic weights.

  14. Network device interface for digitally interfacing data channels to a controller via a network

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

    2006-01-01

    The present invention provides a network device interface and method for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is then converted by the network device interface into digital signals and transmitted back to the controller. In one advantageous embodiment, the network device interface is a state machine, such as an ASIC, that operates independent of a processor in communicating with the bus controller and data channels.

  15. Network device interface for digitally interfacing data channels to a controller via a network

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

    2007-01-01

    The present invention provides a network device interface and method for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is converted into digital signals and transmitted to the controller. In some embodiments, network device interfaces associated with different data channels coordinate communications with the other interfaces based on either a transition in a command message sent by the bus controller or a synchronous clock signal.

  16. Network device interface for digitally interfacing data channels to a controller via a network

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

    2009-01-01

    A communications system and method are provided for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is converted into digital signals and transmitted to the controller. Network device interfaces associated with different data channels can coordinate communications with the other interfaces based on either a transition in a command message sent by the bus controller or a synchronous clock signal.

  17. Direct Digital Manufacturing of Integrated Naval Systems Using Ultrasonic Consolidation, Support Material Deposition and Direct Write Technologies

    DTIC Science & Technology

    2012-02-17

    with an integrated " tool changer " capable of interchangeably using a "direct write tool " for electronic material deposition, a "material extrusion head...Pump Fig. 26. The nScrypt direct write "Smart Pump" system (www.nscryptinc.com) Direct Write Deposition & CNC Milling Flexible FDM Machine Heated...oflntegrated Naval Systems Using Ultrasonic Consolidation, Support Material Deposition and Direct Write Technologies 5a. CONTRACT NUMBER N00014-07-1-0633

  18. Validation of MTF measurement for digital mammography quality control

    SciTech Connect

    Carton, Ann-Katherine; Vandenbroucke, Dirk; Struye, Luc; Maidment, Andrew D.A.; Kao, Y.-H.; Albert, Michael; Bosmans, Hilde; Marchal, Guy

    2005-06-15

    The modulation transfer function (MTF) describes the spatial resolution properties of imaging systems. In this work, the accuracy of our implementation of the edge method for calculating the presampled MTF was examined. Synthetic edge images with known MTF were used as gold standards for determining the robustness of the edge method. These images simulated realistic data from clinical digital mammography systems, and contained intrinsic system factors that could affect the MTF accuracy, such as noise, scatter, and flat-field nonuniformities. Our algorithm is not influenced by detector dose variations for MTF accuracy up to 1/2 the sampling frequency. We investigated several methods for noise reduction, including truncating the supersampled line spread function (LSF), windowing the LSF, applying a local exponential fit to the LSF, and applying a monotonic constraint to the supersampled edge spread function. Only the monotonic constraint did not introduce a systematic error; the other methods could result in MTF underestimation. Overall, our edge method consistently computed MTFs which were in good agreement with the true MTF. The edge method was then applied to images from a commercial storage-phosphor based digital mammography system. The calculated MTF was affected by the size (sides of 2.5, 5, or 10 cm) and the composition (lead or tungsten) of the edge device. However, the effects on the MTF were observed only with regard to the low frequency drop (LFD). Scatter nonuniformity was dependent on edge size, and could lead to slight underestimation of LFD. Nevertheless, this negative effect could be minimized by using an edge of 5 cm or larger. An edge composed of lead is susceptible to L-fluorescence, which causes overestimation of the LFD. The results of this work are intended to underline the need for clear guidelines if the MTF is to be given a more crucial role in acceptance tests and routine assessment of digital mammography systems: the MTF algorithm and edge

  19. Validation of MTF measurement for digital mammography quality control.

    PubMed

    Carton, Ann-Katherine; Vandenbroucke, Dirk; Struye, Luc; Maidment, Andrew D A; Kao, Yen-Hong; Albert, Michael; Bosmans, Hilde; Marchal, Guy

    2005-06-01

    The modulation transfer function (MTF) describes the spatial resolution properties of imaging systems. In this work, the accuracy of our implementation of the edge method for calculating the presampled MTF was examined. Synthetic edge images with known MTF were used as gold standards for determining the robustness of the edge method. These images simulated realistic data from clinical digital mammography systems, and contained intrinsic system factors that could affect the MTF accuracy, such as noise, scatter, and flat-field nonuniformities. Our algorithm is not influenced by detector dose variations for MTF accuracy up to 1/2 the sampling frequency. We investigated several methods for noise reduction, including truncating the supersampled line spread function (LSF), windowing the LSF, applying a local exponential fit to the LSF, and applying a monotonic constraint to the supersampled edge spread function. Only the monotonic constraint did not introduce a systematic error; the other methods could result in MTF underestimation. Overall, our edge method consistently computed MTFs which were in good agreement with the true MTF. The edge method was then applied to images from a commercial storage-phosphor based digital mammography system. The calculated MTF was affected by the size (sides of 2.5, 5, or 10 cm) and the composition (lead or tungsten) of the edge device. However, the effects on the MTF were observed only with regard to the low frequency drop (LFD). Scatter nonuniformity was dependent on edge size, and could lead to slight underestimation of LFD. Nevertheless, this negative effect could be minimized by using an edge of 5 cm or larger. An edge composed of lead is susceptible to L-fluorescence, which causes overestimation of the LFD. The results of this work are intended to underline the need for clear guidelines if the MTF is to be given a more crucial role in acceptance tests and routine assessment of digital mammography systems: the MTF algorithm and edge

  20. Guidance, Navigation and Control Digital Emulation Technology Laboratory

    NASA Astrophysics Data System (ADS)

    Alford, Cecil O.; Chamdani, J. I.; Huang, T. C.; Kubota, T.; Ghannadian, F.

    1994-09-01

    The contract began with seven tasks: (1) Digital Emulation Facility; (2) FPA Seeker Emulator Development; (3) Special Studies; (4) Software Development; (5) Automated Input; (6) PFP Technology; and (7) GN and C Processor Development. These tasks were developed through the first two years of the contract when virtually all funding was removed. Two additional tasks have been developed since the funding cut. The first was a speed test on the rad-hard FPU chip developed by Harris. A summary of this testing and the associated report is given in Section 2. The second task is the development of an FPA Test System.

  1. A monitor for the laboratory evaluation of control integrity in digital control systems operating in harsh electromagnetic environments

    NASA Technical Reports Server (NTRS)

    Belcastro, Celeste M.; Fischl, Robert; Kam, Moshe

    1992-01-01

    This paper presents a strategy for dynamically monitoring digital controllers in the laboratory for susceptibility to electromagnetic disturbances that compromise control integrity. The integrity of digital control systems operating in harsh electromagnetic environments can be compromised by upsets caused by induced transient electrical signals. Digital system upset is a functional error mode that involves no component damage, can occur simultaneously in all channels of a redundant control computer, and is software dependent. The motivation for this work is the need to develop tools and techniques that can be used in the laboratory to validate and/or certify critical aircraft controllers operating in electromagnetically adverse environments that result from lightning, high-intensity radiated fields (HIRF), and nuclear electromagnetic pulses (NEMP). The detection strategy presented in this paper provides dynamic monitoring of a given control computer for degraded functional integrity resulting from redundancy management errors, control calculation errors, and control correctness/effectiveness errors. In particular, this paper discusses the use of Kalman filtering, data fusion, and statistical decision theory in monitoring a given digital controller for control calculation errors.

  2. Impaired goal-directed behavioural control in human impulsivity

    PubMed Central

    Hogarth, Lee; Chase, Henry W.; Baess, Kathleen

    2010-01-01

    Two dissociable learning processes underlie instrumental behaviour. Whereas goal-directed behaviour is controlled by knowledge of the consequences, habitual behaviour is elicited directly by antecedent Pavlovian stimuli without knowledge of the consequences. Predominance of habitual control is thought to underlie psychopathological conditions associated with corticostriatal abnormalities, such as impulsivity and drug dependence. To explore this claim, smokers were assessed for nicotine dependence, impulsivity, and capacity for goal-directed control over instrumental performance in an outcome devaluation procedure. Reduced goal-directed control was selectively associated with the Motor Impulsivity factor of Barrett's Impulsivity Scale (BIS), which reflects propensity for action without thought. These data support the claim that human impulsivity is marked by impaired use of causal knowledge to make adaptive decisions. The predominance of habit learning may play a role in psychopathological conditions that are associated with trait impulsivity. PMID:21077008

  3. A digital control system for external magnetohydrodynamic modes in tokamak plasmas

    SciTech Connect

    Hanson, J. M.; Klein, A. J.; Mauel, M. E.; Maurer, D. A.; Navratil, G. A.; Pedersen, T. Sunn

    2009-04-15

    A feedback system for controlling external, long-wavelength magnetohydrodynamic activity is described. The system is comprised of a network of localized magnetic pickup and control coils driven by four independent, low-latency field-programable gate array controllers. The control algorithm incorporates digital spatial filtering to resolve low mode number activity, temporal filtering to correct for frequency-dependent amplitude and phase transfer effects in the control hardware, and a Kalman filter to distinguish the unstable plasma mode from noise.

  4. A digital control system for external magnetohydrodynamic modes in tokamak plasmas.

    PubMed

    Hanson, J M; Klein, A J; Mauel, M E; Maurer, D A; Navratil, G A; Pedersen, T Sunn

    2009-04-01

    A feedback system for controlling external, long-wavelength magnetohydrodynamic activity is described. The system is comprised of a network of localized magnetic pickup and control coils driven by four independent, low-latency field-programable gate array controllers. The control algorithm incorporates digital spatial filtering to resolve low mode number activity, temporal filtering to correct for frequency-dependent amplitude and phase transfer effects in the control hardware, and a Kalman filter to distinguish the unstable plasma mode from noise.

  5. Report on Disclosure Issues Related to the Use of Copy Control and Digital Rights Management Technologies. OECD Digital Economy Papers, No. 115

    ERIC Educational Resources Information Center

    OECD Publishing (NJ1), 2006

    2006-01-01

    This report analyses the disclosure issues raised by technically-imposed restrictions on the use of digital content. It focuses on the application of copy control and digital rights management technologies in three areas: copy-protected CDs; online music, and DVD regional coding. In each of these areas, the report examines the kinds of…

  6. Adaptive control of waveguide modes using a directional coupler.

    PubMed

    Lu, Peng; Shipton, Matthew; Wang, Anbo; Xu, Yong

    2014-08-25

    Using adaptive optics (AO) and a directional coupler, we demonstrate adaptive control of linearly polarized (LP) modes in a two mode fiber. The AO feedback is provided by the coupling ratio of the directional coupler, and does not depend on the spatial profiles of optical field distributions. As a proof of concept demonstration, this work confirms the feasibility of using AO and all fiber devices to control the waveguide modes in a multimode network in a quasi-distributed manner.

  7. Apparatus for externally controlled closed-loop feedback digital epitaxy

    DOEpatents

    Eres, Djula; Sharp, Jeffrey W.

    1996-01-01

    A method and apparatus for digital epitaxy. The apparatus includes a pulsed gas delivery assembly that supplies gaseous material to a substrate to form an adsorption layer of the gaseous material on the substrate. Structure is provided for measuring the isothermal desorption spectrum of the growth surface to monitor the active sites which are available for adsorption. The vacuum chamber housing the substrate facilitates evacuation of the gaseous material from the area adjacent the substrate following exposure. In use, digital epitaxy is achieved by exposing a substrate to a pulse of gaseous material to form an adsorption layer of the material on the substrate. The active sites on the substrate are monitored during the formation of the adsorption layer to determine if all the active sites have been filled. Once the active sites have been filled on the growth surface of the substrate, the pulse of gaseous material is terminated. The unreacted portion of the gas pulse is evacuated by continuous pumping. Subsequently, a second pulse is applied when availability of active sites is determined by studying the isothermal desorption spectrum. These steps are repeated until a thin film of sufficient thickness is produced.

  8. Apparatus for externally controlled closed-loop feedback digital epitaxy

    DOEpatents

    Eres, D.; Sharp, J.W.

    1996-07-30

    A method and apparatus for digital epitaxy are disclosed. The apparatus includes a pulsed gas delivery assembly that supplies gaseous material to a substrate to form an adsorption layer of the gaseous material on the substrate. Structure is provided for measuring the isothermal desorption spectrum of the growth surface to monitor the active sites which are available for adsorption. The vacuum chamber housing the substrate facilitates evacuation of the gaseous material from the area adjacent the substrate following exposure. In use, digital epitaxy is achieved by exposing a substrate to a pulse of gaseous material to form an adsorption layer of the material on the substrate. The active sites on the substrate are monitored during the formation of the adsorption layer to determine if all the active sites have been filled. Once the active sites have been filled on the growth surface of the substrate, the pulse of gaseous material is terminated. The unreacted portion of the gas pulse is evacuated by continuous pumping. Subsequently, a second pulse is applied when availability of active sites is determined by studying the isothermal desorption spectrum. These steps are repeated until a thin film of sufficient thickness is produced. 5 figs.

  9. Expansion of flight simulator capability for study and solution of aircraft directional control problems on runways

    NASA Technical Reports Server (NTRS)

    Kibbee, G. W.

    1978-01-01

    The development, evaluation, and evaluation results of a DC-9-10 runway directional control simulator are described. An existing wide bodied flight simulator was modified to this aircraft configuration. The simulator was structured to use either two of antiskid simulations; (1) an analog mechanization that used aircraft hardware; or (2) a digital software simulation. After the simulation was developed it was evaluated by 14 pilots who made 818 simulated flights. These evaluations involved landings, rejected takeoffs, and various ground maneuvers. Qualitatively most pilots evaluated the simulator as realistic with good potential especially for pilot training for adverse runway conditions.

  10. [Investigation of quality control and average glandular dose and image quality in digital mammography in Hokkaido].

    PubMed

    Kurowarabi, Kunio; Abe, Hiroko; Horita, Hiroshi; Kaneta, Kazuyuki

    2011-01-01

    A questionnaire survey about mammography in Hokkaido was mailed to 121 facilities from August to September 2009. We surveyed the conditions of digital mammography with regard to quality control (QC) and average glandular dose at 79 facilities in Hokkaido in 2009, and the results of the survey were compared with those of 2004. We found that digital mammography techniques were widely used across Hokkaido and that computed radiography (CR) systems were quite widespread, with 70% of facilities having them. The average glandular dose ranged from 1.04 to 2.3 mGy (mean: 1.73 mGy) for digital equipment. The results revealed several problems. Although the use of 1-, 2-, and 3-megapixel (MP) liquid crystal displays (LCDs) was not uncommon, 5-MP LCDs were used in most cases when reading digital mammograms. Facilities that have mammography equipment are unlikely to have quality control instruments for mammography. Although daily QC is performed in most facilities, further quality control for digital mammography should be developed, including that for monitors. In a second study, we evaluated the 1 Shot Phantom M Plus (1 Shot Phantom), which enables objective evaluation by providing for one physical measurement rather than a subjective visual analysis. The results indicated that the 1 Shot Phantom was very useful for digital mammography systems in daily QC testing because it enabled objectivity.

  11. Controlled direct and mediated effects: definition, identification and bounds

    PubMed Central

    VanderWeele, Tyler J.

    2014-01-01

    Results are given which provide bounds for controlled direct effects when the no-unmeasured-confounding assumptions required for the identification of these effects do not hold. Previous results concerning bounds for controlled direct effects rely on monotonicity relationships between the treatment, mediator and the outcome themselves; the results presented in this paper instead assume that monotonicity relationships hold between the unmeasured confounding variable or variables and the treatment, mediator and outcome. Whereas prior results give bounds that contain the null hypothesis of no direct effect, the results presented here will in many instances yield bounds that do not contain the null hypothesis of no direct effect. For contexts in which a set of variables intercepts all paths between a treatment and an outcome, it is possible to provide a definition for a controlled mediated effect. We discuss the identification of these controlled mediated effects; the bounds for controlled direct effects are applicable also to controlled mediated effects. An example is given to illustrate how the results in the paper can be used to draw inferences about direct and mediated effects in the presence of unmeasured confounding variables. PMID:25309023

  12. The role of intrinsic factors in control of arm movement direction: implications from directional preferences.

    PubMed

    Dounskaia, Natalia; Goble, Jacob A; Wang, Wanyue

    2011-03-01

    The role of extrinsic and intrinsic factors in control of arm movement direction remains under debate. We addressed this question by investigating preferences in selection of movement direction and whether factors causing these preferences have extrinsic or intrinsic nature. An unconstrained free-stroke drawing task was used during which participants produced straight strokes on a horizontal table, choosing the direction and the beginning and end of each stroke arbitrarily. The variation of the initial arm postures across strokes provided a possibility to distinguish between the extrinsic and intrinsic origins of directional biases. Although participants were encouraged to produce strokes equally in all directions, each participant demonstrated preferences for some directions over the others. However, the preferred directions were not consistent across participants, suggesting no directional preferences in extrinsic space. Consistent biases toward certain directions were revealed in intrinsic space representing initial arm postures. Factors contributing to the revealed preferences were analyzed within the optimal control framework. The major bias was explained by a tendency predicted by the leading joint hypothesis (LJH) to minimize active interference with interaction torque generated by shoulder motion at the elbow. Some minor biases may represent movements of minimal inertial resistance or maximal kinematic manipulability. These results support a crucial role of intrinsic factors in control of the movement direction of the arm. Based on the LJH interpretation of the major bias, we hypothesize that the dominant tendency was to minimize neural effort for control of arm intersegmental dynamics. Possible organization of neural processes underlying optimal selection of movement direction is discussed.

  13. Flight evaluation of a digital electronic engine control system in an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Myers, L. P.; Mackall, K. G.; Burcham, F. W., Jr.; Walter, W. A.

    1982-01-01

    Benefits provided by a full-authority digital engine control are related to improvements in engine efficiency, performance, and operations. An additional benefit is the capability of detecting and accommodating failures in real time and providing engine-health diagnostics. The digital electronic engine control (DEEC), is a full-authority digital engine control developed for the F100-PW-100 turbofan engine. The DEEC has been flight tested on an F-15 aircraft. The flight tests had the objective to evaluate the DEEC hardware and software over the F-15 flight envelope. A description is presented of the results of the flight tests, which consisted of nonaugmented and augmented throttle transients, airstarts, and backup control operations. The aircraft, engine, DEEC system, and data acquisition and reduction system are discussed.

  14. Flight evaluation of modifications to a digital electronic engine control system in an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Burcham, F. W., Jr.; Myers, L. P.; Zeller, J. R.

    1983-01-01

    The third phase of a flight evaluation of a digital electronic engine control system in an F-15 has recently been completed. It was found that digital electronic engine control software logic changes and augmentor hardware improvements resulted in significant improvements in engine operation. For intermediate to maximum power throttle transients, an increase in altitude capability of up to 8000 ft was found, and for idle to maximum transients, an increase of up to 4000 ft was found. A nozzle instability noted in earlier flight testing was investigated on a test engine at NASA Lewis Research Center, a digital electronic engine control software logic change was developed and evaluated, and no instability occurred in the Phase 3 flight evaluation. The backup control airstart modification was evaluated, and gave an improvement of airstart capability by reducing the minimum airspeed for successful airstarts by 50 to 75 knots.

  15. Network device interface for digitally interfacing data channels to a controller via a network

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

    2005-01-01

    The present invention provides a network device interface and method for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is then converted by the network device interface into digital signals and transmitted back to the controller. In one advantageous embodiment, the network device interface uses a specialized protocol for communicating across the network bus that uses a low-level instruction set and has low overhead for data communication.

  16. Network device interface for digitally interfacing data channels to a controller via a network

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

    2004-01-01

    The present invention provides a network device interface and method for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is then converted by the network device interface into digital signals and transmitted back to the controller. In one advantageous embodiment, the network device interface uses a specialized protocol for communicating across the network bus that uses a low-level instruction set and has low overhead for data communication.

  17. Flight evaluation of modifications to a digital electronic engine control system in an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Burcham, F. W., Jr.; Myers, L. P.; Zeller, J. R.

    1983-01-01

    The third phase of a flight evaluation of a digital electronic engine control system in an F-15 has recently been completed. It was found that digital electronic engine control software logic changes and augmentor hardware improvements resulted in significant improvements in engine operation. For intermediate to maximum power throttle transients, an increase in altitude capability of up to 8000 ft was found, and for idle to maximum transients, an increase of up to 4000 ft was found. A nozzle instability noted in earlier flight testing was investigated on a test engine at NASA Lewis Research Center, a digital electronic engine control software logic change was developed and evaluated, and no instability occurred in the Phase 3 flight evaluation. The backup control airstart modification was evaluated, and gave an improvement of airstart capability by reducing the minimum airspeed for successful airstarts by 50 to 75 knots.

  18. Digital controller for a Baum folding machine. [providing automatic counting and machine shutoff

    NASA Technical Reports Server (NTRS)

    Bryant, W. H. (Inventor)

    1974-01-01

    A digital controller for controlling the operation of a folding machine enables automatic folding of a desired number of sheets responsive to entry of that number into a selector. The controller includes three decade counter stages for corresponding rows of units, tens and hundreds push buttons. Each stage including a decimal-to-BCD encoder, a buffer register, and a digital or binary counter. The BCD representation of the selected count for each digit is loaded into the respective decade down counters. Pulses generated by a sensor and associated circuitry are used to decrease the count in the decade counters. When the content of the decade counter reaches either 0 or 1, a solenoid control valve is actuated which interrupts operation of the machine. A repeat switch, when actuated, prevents clearing of the buffer registers so that multiple groups of the same number of sheets can be folded without reentering the number into the selector.

  19. Flight evaluation of a digital electronic engine control system in an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Myers, L. P.; Mackall, K. G.; Burcham, F. W., Jr.; Walter, W. A.

    1982-01-01

    Benefits provided by a full-authority digital engine control are related to improvements in engine efficiency, performance, and operations. An additional benefit is the capability of detecting and accommodating failures in real time and providing engine-health diagnostics. The digital electronic engine control (DEEC), is a full-authority digital engine control developed for the F100-PW-100 turbofan engine. The DEEC has been flight tested on an F-15 aircraft. The flight tests had the objective to evaluate the DEEC hardware and software over the F-15 flight envelope. A description is presented of the results of the flight tests, which consisted of nonaugmented and augmented throttle transients, airstarts, and backup control operations. The aircraft, engine, DEEC system, and data acquisition and reduction system are discussed.

  20. Direct Fault Tolerant RLV Altitude Control: A Singular Perturbation Approach

    NASA Technical Reports Server (NTRS)

    Zhu, J. J.; Lawrence, D. A.; Fisher, J.; Shtessel, Y. B.; Hodel, A. S.; Lu, P.; Jackson, Scott (Technical Monitor)

    2002-01-01

    In this paper, we present a direct fault tolerant control (DFTC) technique, where by "direct" we mean that no explicit fault identification is used. The technique will be presented for the attitude controller (autopilot) for a reusable launch vehicle (RLV), although in principle it can be applied to many other applications. Any partial or complete failure of control actuators and effectors will be inferred from saturation of one or more commanded control signals generated by the controller. The saturation causes a reduction in the effective gain, or bandwidth of the feedback loop, which can be modeled as an increase in singular perturbation in the loop. In order to maintain stability, the bandwidth of the nominal (reduced-order) system will be reduced proportionally according to the singular perturbation theory. The presented DFTC technique automatically handles momentary saturations and integrator windup caused by excessive disturbances, guidance command or dispersions under normal vehicle conditions. For multi-input, multi-output (MIMO) systems with redundant control effectors, such as the RLV attitude control system, an algorithm is presented for determining the direction of bandwidth cutback using the method of minimum-time optimal control with constrained control in order to maintain the best performance that is possible with the reduced control authority. Other bandwidth cutback logic, such as one that preserves the commanded direction of the bandwidth or favors a preferred direction when the commanded direction cannot be achieved, is also discussed. In this extended abstract, a simplistic example is proved to demonstrate the idea. In the final paper, test results on the high fidelity 6-DOF X-33 model with severe dispersions will be presented.