Science.gov

Sample records for passive system failure

  1. Reliable Mixed H∞ and Passivity-Based Control for Fuzzy Markovian Switching Systems With Probabilistic Time Delays and Actuator Failures.

    PubMed

    Sakthivel, Rathinasamy; Selvi, Subramaniam; Mathiyalagan, Kalidass; Shi, Peng

    2015-12-01

    This paper is concerned with the problem of reliable mixed H ∞ and passivity-based control for a class of stochastic Takagi-Sugeno (TS) fuzzy systems with Markovian switching and probabilistic time varying delays. Different from the existing works, the H∞ and passivity control problem with probabilistic occurrence of time-varying delays and actuator failures is considered in a unified framework, which is more general in some practical situations. The main aim of this paper is to design a reliable mixed H∞ and passivity-based controller such that the stochastic TS fuzzy system with Markovian switching is stochastically stable with a prescribed mixed H∞ and passivity performance level γ > 0 . Based on the Lyapunov-Krasovskii functional (LKF) involving lower and upper bound of probabilistic time delay and convex combination technique, a new set of delay-dependent sufficient condition in terms of linear matrix inequalities (LMIs) is established for obtaining the required result. Finally, a numerical example based on the modified truck-trailer model is given to demonstrate the effectiveness and applicability of the proposed design techniques.

  2. Passive propellant system

    NASA Technical Reports Server (NTRS)

    Hess, D. A.; Regnier, W. W.; Jacobs, V. L. (Inventor)

    1979-01-01

    A passive propellant acquisition and feed system is disclosed which acquires and feeds gas-free propellant in low or zero-g environments during orbital maneuvers and retains this propellant under high axially directed acceleration such as may be experienced during launch of a space vehicle and orbit-to-orbit transfer is described. The propellant system includes a dual compartment propellant tank with independent surface tension acquisition channels in each compartment to provide gas-free flow of pressurized liquid propellant from one compartment to the other in one direction only.

  3. Passive magnetic bearing system

    DOEpatents

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  4. Passive containment cooling system

    DOEpatents

    Billig, Paul F.; Cooke, Franklin E.; Fitch, James R.

    1994-01-01

    A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA.

  5. Passive containment cooling system

    DOEpatents

    Billig, P.F.; Cooke, F.E.; Fitch, J.R.

    1994-01-25

    A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA. 1 figure.

  6. Temperature initiated passive cooling system

    DOEpatents

    Forsberg, C.W.

    1994-11-01

    A passive cooling system for cooling an enclosure only when the enclosure temperature exceeds a maximum standby temperature comprises a passive heat transfer loop containing heat transfer fluid having a particular thermodynamic critical point temperature just above the maximum standby temperature. An upper portion of the heat transfer loop is insulated to prevent two phase operation below the maximum standby temperature. 1 fig.

  7. Temperature initiated passive cooling system

    DOEpatents

    Forsberg, Charles W.

    1994-01-01

    A passive cooling system for cooling an enclosure only when the enclosure temperature exceeds a maximum standby temperature comprises a passive heat transfer loop containing heat transfer fluid having a particular thermodynamic critical point temperature just above the maximum standby temperature. An upper portion of the heat transfer loop is insulated to prevent two phase operation below the maximum standby temperature.

  8. An approach for assessing ALWR passive safety system reliability

    SciTech Connect

    Hake, T M

    1991-01-01

    Many advanced light water reactor designs incorporate passive rather than active safety features for front-line accident response. A method for evaluating the reliability of these passive systems in the context of probabilistic risk assessment has been developed at Sandia National Laboratories. This method addresses both the component (e.g. valve) failure aspect of passive system failure, and uncertainties in system success criteria arising from uncertainties in the system's underlying physical processes. These processes provide the system's driving force; examples are natural circulation and gravity-induced injection. This paper describes the method, and provides some preliminary results of application of the approach to the Westinghouse AP600 design.

  9. Heart failure decreases passive tension generation of rat diaphragm fibers.

    PubMed

    van Hees, H W H; Ottenheijm, C A C; Granzier, H L; Dekhuijzen, P N R; Heunks, L M A

    2010-06-11

    Diaphragm dysfunction is well-known to limit quality of life and prognosis of patients with heart failure (HF), but its underlying mechanisms are not well understood. In an animal model for HF we recently showed that impaired diaphragm contractility arises at the single fiber level and is associated with sarcomeric injuries. For optimal muscle function and sarcomeric stability passive elastic structures, like titin, are indispensable. The current study aimed to investigate if impaired passive elasticity contributes to diaphragm dysfunction in rats with heart failure. Skinned muscle fibers were isolated from the diaphragm and soleus of rats with chronic HF, induced by left coronary artery ligation and of sham-operated rats. Passive tension-length relationships were determined by applying segmental extension tests. Immunofluorescence was performed on muscle cryosections using antibodies (T12) against a titin epitope near the Z-line. Titin content was determined by SDS-agarose-gel electrophoresis. Titin's mobility on gel was studied to detect changes in titin size. Passive tension generation upon stretch was significantly reduced (>35%) in HF diaphragm fibers compared to sham. Immunostaining intensities against titin were reduced in diaphragm cryosections of HF rats compared to sham. Soleus fibers from HF and sham rats did not display differences, neither in passive tension nor in immunostaining. No differences in titin's size were detected in HF and sham diaphragm. Titin content, however, was significantly reduced ( approximately 25%) in HF diaphragm. We conclude that in the diaphragm of HF rats, passive elasticity is impaired, mainly resulting from titin loss. Copyright (c) 2008 Elsevier Ireland Ltd. All rights reserved.

  10. Passive solar heating system

    NASA Astrophysics Data System (ADS)

    Mingenbach, W.

    1981-08-01

    The Toas State Office Building is a single-story office building in New Mexico which incorporates passive collection and storage of solar energy along with natural lighting for general illumination. The building is oriented to take advantage of early morning sunlight and is designed to supply 70% of the heating load by solar heat. The site is equipped with clerestory windows, totaling 2695 square feet, 296 square feet of south facing windows, and east and west window scoops totaling 218 square feet. The collected solar energy is stored in 14,080 gallons of water contained in drums located in the clerestory area, as well as in the masonry construction mass. Auxiliary heat is provided via electric strips in the supply ducts. Movable, insulated shutters are provided to reduce the loss from the clerestory window area at night. The project is described with pictures and diagrams of the final installation provided. An updated performance data report is included, and functional problems, general comments, maintenance and refurbishment recommendations are discussed.

  11. Integration of Passive System Reliability in PSA Studies

    SciTech Connect

    Burgazzi, Luciano; Marques, Michel

    2006-07-01

    The treatment of passive safety systems within the probabilistic safety assessment models is a difficult and challenging task. The main concern arises from the nature of the passive systems whose predominant operating principles are based on physical phenomena rather than on active components. The present study provides a consistent approach for the integration of passive safety systems into fault tree and event tree based Probabilistic Safety Assessment (PSA) model of accident sequences, in the fashion of and in combination with a front line system or a human action. With reference to the thermal-hydraulic passive systems (e.g. natural circulation systems), in addition to the component failures (i.e. mechanical and electrical faults), the impairment of the physical principle upon which the system relies, deserves special consideration. This makes the relative assessment process different as regards the system model commonly adopted in the fault tree approach (i.e. exponential failure model). For the thermal-hydraulic passive system, since the failure process is driven mainly by the occurrence of the phenomenological failure modes, each pertinent basic event will be characterized by defined critical parameters (e.g. non-condensable fraction) that are expected to drive the failure mechanisms. An application of this approach is presented, with reference to a system designed for decay heat removal of advanced Light Water Reactors, relying on natural circulation and provided with a heat exchanger immersed in a cooling pool, acting as heat sink, and connected to the pressure vessel via steam and condensate lines. (authors)

  12. Passive compact molten salt reactor (PCMSR), modular thermal breeder reactor with totally passive safety system

    NASA Astrophysics Data System (ADS)

    Harto, Andang Widi

    2012-06-01

    Design Study Passive Compact Molten Salt Reactor (PCMSR) with totally passive safety system has been performed. The term of Compact in the PCMSR name means that the reactor system is designed to have relatively small volume per unit power output by using modular and integral concept. In term of modular, the reactor system consists of three modules, i.e. reactor module, turbine module and fuel management module. The reactor module is an integral design that consists of reactor, primary and intermediate heat exchangers and passive post shutdown cooling system. The turbine module is an integral design of a multi heating, multi cooling, regenerative gas turbine. The fuel management module consists of all equipments related to fuel preparation, fuel reprocessing and radioactive handling. The preliminary calculations show that the PCMSR has negative temperature and void reactivity coefficient, passive shutdown characteristic related to fuel pump failure and possibility of using natural circulation for post shutdown cooling system.

  13. Passive compact molten salt reactor (PCMSR), modular thermal breeder reactor with totally passive safety system

    SciTech Connect

    Harto, Andang Widi

    2012-06-06

    Design Study Passive Compact Molten Salt Reactor (PCMSR) with totally passive safety system has been performed. The term of Compact in the PCMSR name means that the reactor system is designed to have relatively small volume per unit power output by using modular and integral concept. In term of modular, the reactor system consists of three modules, i.e. reactor module, turbine module and fuel management module. The reactor module is an integral design that consists of reactor, primary and intermediate heat exchangers and passive post shutdown cooling system. The turbine module is an integral design of a multi heating, multi cooling, regenerative gas turbine. The fuel management module consists of all equipments related to fuel preparation, fuel reprocessing and radioactive handling. The preliminary calculations show that the PCMSR has negative temperature and void reactivity coefficient, passive shutdown characteristic related to fuel pump failure and possibility of using natural circulation for post shutdown cooling system.

  14. Passive intrusion detection system

    NASA Technical Reports Server (NTRS)

    Laue, E. G. (Inventor)

    1980-01-01

    An intrusion detection system is described in which crystal oscillators are used to provide a frequency which varies as a function of fluctuations of a particular environmental property of the atmosphere, e.g., humidity, in the protected volume. The system is based on the discovery that the frequency of an oscillator whose crystal is humidity sensitive, varies at a frequency or rate which is within a known frequency band, due to the entry of an intruder into the protected volume. The variable frequency is converted into a voltage which is then filtered by a filtering arrangement which permits only voltage variations at frequencies within the known frequency band to activate an alarm, while inhibiting the alarm activation when the voltage frequency is below or above the known frequency band.

  15. Passive containment cooling system

    DOEpatents

    Conway, Lawrence E.; Stewart, William A.

    1991-01-01

    A containment cooling system utilizes a naturally induced air flow and a gravity flow of water over the containment shell which encloses a reactor core to cool reactor core decay heat in two stages. When core decay heat is greatest, the water and air flow combine to provide adequate evaporative cooling as heat from within the containment is transferred to the water flowing over the same. The water is heated by heat transfer and then evaporated and removed by the air flow. After an initial period of about three to four days when core decay heat is greatest, air flow alone is sufficient to cool the containment.

  16. Ampoule Failure System

    NASA Technical Reports Server (NTRS)

    Watring, Dale A. (Inventor); Johnson, Martin L. (Inventor)

    1996-01-01

    An ampoule failure system for use in material processing furnaces comprising a containment cartridge and an ampoule failure sensor. The containment cartridge contains an ampoule of toxic material therein and is positioned within a furnace for processing. An ampoule failure probe is positioned in the containment cartridge adjacent the ampoule for detecting a potential harmful release of toxic material therefrom during processing. The failure probe is spaced a predetermined distance from the ampoule and is chemically chosen so as to undergo a timely chemical reaction with the toxic material upon the harmful release thereof. The ampoule failure system further comprises a data acquisition system which is positioned externally of the furnace and is electrically connected to the ampoule failure probe so as to form a communicating electrical circuit. The data acquisition system includes an automatic shutdown device for shutting down the furnace upon the harmful release of toxic material. It also includes a resistance measuring device for measuring the resistance of the failure probe during processing. The chemical reaction causes a step increase in resistance of the failure probe whereupon the automatic shutdown device will responsively shut down the furnace.

  17. Modular passive solar heating system

    SciTech Connect

    Hunter, B.D.

    1985-03-19

    A modular passive solar energy storage system comprises a plurality of heat tubes which are arranged to form a flat plate solar collector and are releasably connected to a water reservoir by, and are part of, double-walled heat exchangers which penetrate to the water reservoir and enhance the heat transfer characteristics between the collector and the reservoir. The flat plate collector-heat exchanger disassembly, the collector housing, and the reservoir are integrated into a relatively light weight, unitary structural system in which the reservoir is a primary structural element. In addition to light weight, the system features high efficiency and ease of assembly and maintenance.

  18. Results of a Demonstration Assessment of Passive System Reliability Utilizing the Reliability Method for Passive Systems (RMPS)

    SciTech Connect

    Bucknor, Matthew; Grabaskas, David; Brunett, Acacia; Grelle, Austin

    2015-04-26

    Advanced small modular reactor designs include many advantageous design features such as passively driven safety systems that are arguably more reliable and cost effective relative to conventional active systems. Despite their attractiveness, a reliability assessment of passive systems can be difficult using conventional reliability methods due to the nature of passive systems. Simple deviations in boundary conditions can induce functional failures in a passive system, and intermediate or unexpected operating modes can also occur. As part of an ongoing project, Argonne National Laboratory is investigating various methodologies to address passive system reliability. The Reliability Method for Passive Systems (RMPS), a systematic approach for examining reliability, is one technique chosen for this analysis. This methodology is combined with the Risk-Informed Safety Margin Characterization (RISMC) approach to assess the reliability of a passive system and the impact of its associated uncertainties. For this demonstration problem, an integrated plant model of an advanced small modular pool-type sodium fast reactor with a passive reactor cavity cooling system is subjected to a station blackout using RELAP5-3D. This paper discusses important aspects of the reliability assessment, including deployment of the methodology, the uncertainty identification and quantification process, and identification of key risk metrics.

  19. Passive Tracking System and Method

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor); Chen, Henry A. (Inventor); Phan, Chau T. (Inventor); Bourgeois, Brian A. (Inventor); Dusl, Jon (Inventor); Hill, Brent W. (Inventor)

    2003-01-01

    Systems and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes an antenna array with three antenna elements, which preferably are patch antenna elements spaced apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

  20. Passive Tracking System and Method

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor); Chen, Henry A. (Inventor); Phan, Chau T. (Inventor); Bourgeois, Brian A. (Inventor); Dusl, John (Inventor); Hill, Brent W. (Inventor)

    2005-01-01

    System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes antenna array with three antenna elements, which preferably are patch antenna elements placed apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

  1. Passive environmental temperature control system

    DOEpatents

    Corliss, John M.; Stickford, George H.

    1981-01-01

    Passive environmental heating and cooling systems are described, which utilize heat pipes to transmit heat to or from a thermal reservoir. In a solar heating system, a heat pipe is utilized to carry heat from a solar heat absorber plate that receives sunlight, through a thermal insulation barrier, to a heat storage wall, with the outer end of the pipe which is in contact with the solar absorber being lower than the inner end. The inclining of the heat pipe assures that the portion of working fluid, such as Freon, which is in a liquid phase will fall by gravity to the outer end of the pipe, thereby assuring diode action that prevents the reverse transfer of heat from the reservoir to the outside on cool nights. In a cooling system, the outer end of the pipe which connects to a heat dissipator, is higher than the inner end that is coupled to a cold reservoir, to allow heat transfer only out of the reservoir to the heat dissipator, and not in the reverse direction.

  2. Strong local passivity in finite quantum systems.

    PubMed

    Frey, Michael; Funo, Ken; Hotta, Masahiro

    2014-07-01

    Passive states of quantum systems are states from which no system energy can be extracted by any cyclic (unitary) process. Gibbs states of all temperatures are passive. Strong local (SL) passive states are defined to allow any general quantum operation, but the operation is required to be local, being applied only to a specific subsystem. Any mixture of eigenstates in a system-dependent neighborhood of a nondegenerate entangled ground state is found to be SL passive. In particular, Gibbs states are SL passive with respect to a subsystem only at or below a critical system-dependent temperature. SL passivity is associated in many-body systems with the presence of ground state entanglement in a way suggestive of collective quantum phenomena such as quantum phase transitions, superconductivity, and the quantum Hall effect. The presence of SL passivity is detailed for some simple spin systems where it is found that SL passivity is neither confined to systems of only a few particles nor limited to the near vicinity of the ground state.

  3. Solar passive systems for buildings

    NASA Astrophysics Data System (ADS)

    1980-03-01

    A survey is provided of what is known about the design of solar passive buildings. A systematic presentation is given of proven concepts with suitable illustrations. It is intended as a general guide for architects, designers and other building practitioners. Topics include the various concepts of solar passive heating and cooling, design factors such as location, climate, microclimate, form; building metabolism, thermal and visual comfort; location and form of illumination; and natural cooling via wind towers and cisterns.

  4. Statistical theory of passive location systems

    NASA Astrophysics Data System (ADS)

    Torrieri, D. J.

    1984-03-01

    A derivation of the principal algorithms and an analysis of the performance of the two most important passive location systems for stationary transmitters, hyperbolic location systems and direction-finding location systems, are presented. The concentration ellipse, the circular error probability, and the geometric dilution of precision are defined and related to the location-system and received-signal characteristics. Doppler and other passive location systems are briefly discussed.

  5. A Passive System Reliability Analysis for a Station Blackout

    SciTech Connect

    Brunett, Acacia; Bucknor, Matthew; Grabaskas, David; Sofu, Tanju; Grelle, Austin

    2015-05-03

    The latest iterations of advanced reactor designs have included increased reliance on passive safety systems to maintain plant integrity during unplanned sequences. While these systems are advantageous in reducing the reliance on human intervention and availability of power, the phenomenological foundations on which these systems are built require a novel approach to a reliability assessment. Passive systems possess the unique ability to fail functionally without failing physically, a result of their explicit dependency on existing boundary conditions that drive their operating mode and capacity. Argonne National Laboratory is performing ongoing analyses that demonstrate various methodologies for the characterization of passive system reliability within a probabilistic framework. Two reliability analysis techniques are utilized in this work. The first approach, the Reliability Method for Passive Systems, provides a mechanistic technique employing deterministic models and conventional static event trees. The second approach, a simulation-based technique, utilizes discrete dynamic event trees to treat time- dependent phenomena during scenario evolution. For this demonstration analysis, both reliability assessment techniques are used to analyze an extended station blackout in a pool-type sodium fast reactor (SFR) coupled with a reactor cavity cooling system (RCCS). This work demonstrates the entire process of a passive system reliability analysis, including identification of important parameters and failure metrics, treatment of uncertainties and analysis of results.

  6. System and method for floating-substrate passive voltage contrast

    DOEpatents

    Jenkins, Mark W [Albuquerque, NM; Cole, Jr., Edward I.; Tangyunyong, Paiboon [Albuquerque, NM; Soden, Jerry M [Placitas, NM; Walraven, Jeremy A [Albuquerque, NM; Pimentel, Alejandro A [Albuquerque, NM

    2009-04-28

    A passive voltage contrast (PVC) system and method are disclosed for analyzing ICs to locate defects and failure mechanisms. During analysis a device side of a semiconductor die containing the IC is maintained in an electrically-floating condition without any ground electrical connection while a charged particle beam is scanned over the device side. Secondary particle emission from the device side of the IC is detected to form an image of device features, including electrical vias connected to transistor gates or to other structures in the IC. A difference in image contrast allows the defects or failure mechanisms be pinpointed. Varying the scan rate can, in some instances, produce an image reversal to facilitate precisely locating the defects or failure mechanisms in the IC. The system and method are useful for failure analysis of ICs formed on substrates (e.g. bulk semiconductor substrates and SOI substrates) and other types of structures.

  7. The REPAS Study: Reliability Evaluation of Passive Safety Systems

    SciTech Connect

    Ricotti, M.E.; Bianchi, F.; Burgazzi, L.; D'Auria, F.; Galassi, G.

    2002-07-01

    The strategy of approach to the problem moves from the consideration that a passive system should be theoretically more reliable than an active one. In fact it does not need any external input or energy to operate and it relies only upon natural physical laws (e.g. gravity, natural circulation, internally stored energy, etc.) and/or 'intelligent' use of the energy inherently available in the system (e.g. chemical reaction, decay heat, etc.). Nevertheless the passive system may fail its mission not only as a consequence of classical mechanical failure of components, but also for deviation from the expected behaviour, due to physical phenomena mainly related to thermal-hydraulics or due to different boundary and initial conditions. The main sources of physical failure are identified and a probability of occurrence is assigned. The reliability analysis is performed on a passive system which operates in two-phase, natural circulation. The selected system is a loop including a heat source and a heat sink where the condensation occurs. The system behavior under different configurations has been simulated via best-estimate code (Relap5 mod3.2). The results are shown and can be treated in such a way to give qualitative and quantitative information on the system reliability. Main routes of development of the methodology are also depicted. (authors)

  8. Passive Cooling System for a Vehicle

    DOEpatents

    Hendricks, T. J.; Thoensen, T.

    2005-11-15

    A passive cooling system for a vehicle (114) transfers heat from an overheated internal component, for example, an instrument panel (100), to an external portion (116) of the vehicle (114), for example, a side body panel (126). The passive cooling system includes one or more heat pipes (112) having an evaporator section (118) embedded in the overheated internal component and a condenser section (120) at the external portion (116) of the vehicle (114). The evaporator (118) and condenser (120) sections are in fluid communication. The passive cooling system may also include a thermally conductive film (140) for thermally connecting the evaporator sections (118) of the heat pipes (112) to each other and to the instrument panel (100).

  9. Passive cooling system for a vehicle

    DOEpatents

    Hendricks, Terry Joseph; Thoensen, Thomas

    2005-11-15

    A passive cooling system for a vehicle (114) transfers heat from an overheated internal component, for example, an instrument panel (100), to an external portion (116) of the vehicle (114), for example, a side body panel (126). The passive cooling system includes one or more heat pipes (112) having an evaporator section (118) embedded in the overheated internal component and a condenser section (120) at the external portion (116) of the vehicle (114). The evaporator (118) and condenser (120) sections are in fluid communication. The passive cooling system may also include a thermally conductive film (140) for thermally connecting the evaporator sections (118) of the heat pipes (112) to each other and to the instrument panel (100).

  10. PCM Passive Cooling System Containing Active Subsystems

    NASA Technical Reports Server (NTRS)

    Blanding, David E.; Bass, David I.

    2005-01-01

    A multistage system has been proposed for cooling a circulating fluid that is subject to intermittent intense heating. The system would be both flexible and redundant in that it could operate in a basic passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a second cooling subsystem that could be active, passive, or a combination of both. This flexibility and redundancy, in combination with the passive nature of at least one of the modes of operation, would make the system more reliable, relative to a conventional cooling system. The system would include a tube-in-shell heat exchanger, within which the space between the tubes would be filled with a phase-change material (PCM). The circulating hot fluid would flow along the tubes in the heat exchanger. In the basic passive mode of operation, heat would be conducted from the hot fluid into the PCM, wherein the heat would be stored temporarily by virtue of the phase change.

  11. Inherently safe passive gas monitoring system

    DOEpatents

    Cordaro, Joseph V.; Bellamy, John Stephen; Shuler, James M.; Shull, Davis J.; Leduc, Daniel R.

    2016-09-06

    Generally, the present disclosure is directed to gas monitoring systems that use inductive power transfer to safely power an electrically passive device included within a nuclear material storage container. In particular, the electrically passive device can include an inductive power receiver for receiving inductive power transfer through a wall of the nuclear material storage container. The power received by the inductive power receiver can be used to power one or more sensors included in the device. Thus, the device is not required to include active power generation components such as, for example, a battery, that increase the risk of a spark igniting flammable gases within the container.

  12. Passive wireless ultrasonic transducer systems

    NASA Astrophysics Data System (ADS)

    Zhong, C. H.; Croxford, A. J.; Wilcox, P. D.

    2014-02-01

    Inductive coupling and capacitive coupling both offer simple solutions to wirelessly probe ultrasonic transducers. This paper investigates the theory and feasibility of such system in the context of non-destructive evaluation (NDE) applications. Firstly, the physical principles and construction of an inductively coupled transducer system (ICTS) and a capacitively coupled transducer system (CCTS) are introduced. Then the development of a transmission line model with the measured impedance of a bonded piezoelectric ceramic disc representing a sensor attached to an arbitrary solid substrate for both systems is described. The models are validated experimentally. Several applications of CCTS are presented, such CCTS for the underwater and through-composite testing.

  13. Passive safety injection system using borated water

    SciTech Connect

    Conway, Lawrence E.; Schulz, Terry L.

    1993-01-01

    A passive safety injection system relies on differences in water density to induce natural circulatory flow patterns which help maintain prescribed concentrations of boric acid in borated water, and prevents boron from accumulating in the reactor vessel and possibly preventing heat transfer.

  14. 9 CFR 113.499 - Products for treatment of failure of passive transfer.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARD REQUIREMENTS Antibody Products § 113.499 Products for treatment of failure of passive transfer. A... antibody origin. A product for oral administration shall not be recommended for use in animals more than 24...) Antibody functionality. Prior to licensure, the prospective licensee shall perform a neutralization study...

  15. 9 CFR 113.499 - Products for treatment of failure of passive transfer.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARD REQUIREMENTS Antibody Products § 113.499 Products for treatment of failure of passive transfer. A... antibody origin. A product for oral administration shall not be recommended for use in animals more than 24...) Antibody functionality. Prior to licensure, the prospective licensee shall perform a neutralization study...

  16. 9 CFR 113.499 - Products for treatment of failure of passive transfer.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARD REQUIREMENTS Antibody Products § 113.499 Products for treatment of failure of passive transfer. A... antibody origin. A product for oral administration shall not be recommended for use in animals more than 24...) Antibody functionality. Prior to licensure, the prospective licensee shall perform a neutralization study...

  17. 9 CFR 113.499 - Products for treatment of failure of passive transfer.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARD REQUIREMENTS Antibody Products § 113.499 Products for treatment of failure of passive transfer. A... antibody origin. A product for oral administration shall not be recommended for use in animals more than 24...) Antibody functionality. Prior to licensure, the prospective licensee shall perform a neutralization...

  18. Passive dynamic controllers for nonlinear mechanical systems

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.

    1991-01-01

    A methodology for model-independant controller design for controlling large angular motion of multi-body dynamic systems is outlined. The controlled system may consist of rigid and flexible components that undergo large rigid body motion and small elastic deformations. Control forces/torques are applied to drive the system and at the same time suppress the vibration due to flexibility of the components. The proposed controller consists of passive second-order systems which may be designed with little knowledge of the system parameter, even if the controlled system is nonlinear. Under rather general assumptions, the passive design assures that the closed loop system has guaranteed stability properties. Unlike positive real controller design, stabilization can be accomplished without direct velocity feedback. In addition, the second-order passive design allows dynamic feedback controllers with considerable freedom to tune for desired system response, and to avoid actuator saturation. After developing the basic mathematical formulation of the design methodology, simulation results are presented to illustrate the proposed approach to a flexible six-degree-of-freedom manipulator.

  19. Diastolic heart failure--abnormalities in active relaxation and passive stiffness of the left ventricle.

    PubMed

    Zile, Michael R; Baicu, Catalin F; Gaasch, William H

    2004-05-06

    Patients with signs and symptoms of heart failure and a normal left ventricular ejection fraction are said to have diastolic heart failure. It has traditionally been thought that the pathophysiological cause of heart failure in these patients is an abnormality in the diastolic properties of the left ventricle; however, this hypothesis remains largely unproven. We prospectively identified 47 patients who met the diagnostic criteria for definite diastolic heart failure; all the patients had signs and symptoms of heart failure, a normal ejection fraction, and an increased left ventricular end-diastolic pressure. Ten patients who had no evidence of cardiovascular disease served as controls. Left ventricular diastolic function was assessed by means of cardiac catheterization and echocardiography. The patients with diastolic heart failure had abnormal left ventricular relaxation and increased left ventricular chamber stiffness. The mean (+/-SD) time constant for the isovolumic-pressure decline (tau) was longer in the group with diastolic heart failure than in the control group (59+/-14 msec vs. 35+/-10 msec, P=0.01). The diastolic pressure-volume relation was shifted up and to the left in the patients with diastolic heart failure as compared with the controls. The corrected left ventricular passive-stiffness constant was significantly higher in the group with diastolic heart failure than in the control group (0.03+/-0.01 vs. 0.01+/-0.01, P<0.001). Patients with heart failure and a normal ejection fraction have significant abnormalities in active relaxation and passive stiffness. In these patients, the pathophysiological cause of elevated diastolic pressures and heart failure is abnormal diastolic function. Copyright 2004 Massachusetts Medical Society

  20. Passive Fetal Heart Monitoring System

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Mowrey, Dennis L. (Inventor)

    2003-01-01

    A fetal heart monitoring system and method for detecting and processing acoustic fetal heart signals transmitted by different signal transmission modes. One signal transmission mode, the direct contact mode, occurs in a first frequency band when the fetus is in direct contact with the maternal abdominal wall. Another signal transmission mode, the fluid propagation mode, occurs in a second frequency band when the fetus is in a recessed position with no direct contact with the maternal abdominal wall. The second frequency band is relatively higher than the first frequency band. The fetal heart monitoring system and method detect and process acoustic fetal heart signals that are in the first frequency band and in the second frequency band.

  1. Passive Fetal Heart Monitoring System

    NASA Technical Reports Server (NTRS)

    Bryant, Timothy D. (Inventor); Wynkoop, Mark W. (Inventor); Holloway, Nancy M. H. (Inventor); Zuckerwar, Allan J. (Inventor)

    2004-01-01

    A fetal heart monitoring system preferably comprising a backing plate having a generally concave front surface and a generally convex back surface, and at least one sensor element attached to the concave front surface for acquiring acoustic fetal heart signals produced by a fetus within a body. The sensor element has a shape that conforms to the generally concave back surface of the backing plate. In one embodiment, the at least one sensor element comprises an inner sensor, and a plurality of outer sensors surrounding the inner sensor. The fetal heart monitoring system can further comprise a web belt, and a web belt guide movably attached to the web belt. The web belt guide being is to the convex back surface of the backing plate.

  2. Passive Microwave Power Distribution Systems.

    DTIC Science & Technology

    wavelength by switching a reciprocal latching ferrite phase shifter in the stub, in response to termination of microwave power from one of the feed tubes....A standby microwave transmitter power amplifier tube is switched into a microwave power distribution system for a phased array in microseconds when...after the switching is completed, the switching being accomplished by changing electrical length of a quarter-wavelength waveguide stub to one-half

  3. Passively damped vibration welding system and method

    DOEpatents

    Tan, Chin-An; Kang, Bongsu; Cai, Wayne W.; Wu, Tao

    2013-04-02

    A vibration welding system includes a controller, welding horn, an anvil, and a passive damping mechanism (PDM). The controller generates an input signal having a calibrated frequency. The horn vibrates in a desirable first direction at the calibrated frequency in response to the input signal to form a weld in a work piece. The PDM is positioned with respect to the system, and substantially damps or attenuates vibration in an undesirable second direction. A method includes connecting the PDM having calibrated properties and a natural frequency to an anvil of an ultrasonic welding system. Then, an input signal is generated using a weld controller. The method includes vibrating a welding horn in a desirable direction in response to the input signal, and passively damping vibration in an undesirable direction using the PDM.

  4. Performance of passive terahertz imaging system

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Zhao, Guozhong

    2016-11-01

    Terahertz (THz) radiation has the higher penetration to clothing, cardboard boxes, plastic packaging materials and other similar dielectrics. Its lower photon energy compared with X-rays make the detected material and the human being to be not destroyed. THz application in field of security are developed by many countries. In this research, we present a multiband of passive terahertz imaging by the thermal radiation measurement. The Noise Equivalent Temperature Difference(NETD) is obtained. The result shows that NETD of the passive imaging system is 0.8K at 94 GHz, and 1.5K at 250GHz. We found that the main source of noise is the noise from detection circuit. Finally, the improvement methods of detecting sensitivity are analyzed and discussed.

  5. Passive sensor systems for nuclear material monitoring

    SciTech Connect

    Simpson, M.L.; Boatner, L.A.; Holcomb, D.E.; McElhaney, S.A.; Mihalczo, J.T.; Muhs, J.D.; Roberts, M.R.; Hill, N.W.

    1993-09-01

    Passive fiber optic sensor systems capable of confirming the presence of special nuclear materials in storage or process facilities are being developed at Oak Ridge National Laboratory (ORNL). These sensors provide completely passive, remote measurement capability. No power supplies, amplifiers, or other active components that could degrade system reliability are required at the sensor location. ORNL, through its research programs in scintillator materials, has developed a variety of materials for use in alpha-, beta-, gamma-, and neutron-sensitive scintillator detectors. In addition to sensors for measuring radiation flux, new sensor materials have been developed which are capable of measuring weight, temperature, and source location. An example of a passive sensor for temperature measurement is the combination of a thermophosphor (e.g., rare-earth activated Y{sub 2}O{sub 3}) with {sup 6}LiF (95% {sup 6}Li). This combination results in a new class of scintillators for thermal neutrons that absorb energy from the radiation particles and remit the energy as a light pulse, the decay rate of which, over a specified temperature range, is temperature dependent. Other passive sensors being developed include pressure-sensitive triboluminescent materials, weight-sensitive silicone rubber fibers, scintillating fibers, and other materials for gamma and neutron detection. The light from the scintillator materials of each sensor would be sent through optical fibers to a monitoring station, where the attribute quantity could be measured and compared with previously recorded emission levels. Confirmatory measurement applications of these technologies are being evaluated to reduce the effort, costs, and employee exposures associated with inventorying stockpiles of highly enriched uranium at the Oak Ridge Y-12 Plant.

  6. Self-protection scheme against failures of distributed fiber links in an Ethernet passive optical network

    NASA Astrophysics Data System (ADS)

    Chen, Jiajia; Chen, Biao; He, Sailing

    2006-09-01

    A novel self-protection scheme for an Ethernet passive optical network is introduced and studied at both the physical and the media access control layers. The scheme is simple and fast and can provide 1:1 protection and automatic traffic restoration against the fiber link failure between a remote node (RN) and any optical network unit (ONU). Simulation results show that fiber failure does not degrade the transmission performance, and the restoration time depends mainly on the switch time of the physical layer. Our protection scheme saves many long fibers, does not influence other normal ONUs, and requires no active device in the RN.

  7. On interconnected systems, passivity and some generalisations

    NASA Astrophysics Data System (ADS)

    Ordóñez-Hurtado, Rodrigo H.; Griggs, Wynita M.; Shorten, Robert N.

    2013-12-01

    A sufficient condition for the stability of large-scale interconnections of N linear time-variant systems is presented. Such a condition represents important extensions to passivity criteria and ensures stability by means of the existence of a positive definite (full-block) matrix P which is a common solution to Lyapunov equations involving a diagonal stacking of the N systems and the interconnection structure matrix. An experimental methodology for the verification of the sufficient condition also is proposed, based on evolutionary computation techniques. Applications of the new stability results are provided through illustrative examples, which are developed using particle swarm optimisation and genetic algorithms.

  8. Experimental and analytical studies of passive shutdown heat removal systems

    SciTech Connect

    Pedersen, D.; Tessier, J.; Heineman, J.; Stewart, R.; Anderson, T.; August, C.; Chawla, T.; Cheung, F.B.; Despe, O.; Haupt, H.J.

    1987-01-01

    Using a naturally circulating air stream to remove shutdown decay heat from a nuclear reactor vessel is a key feature of advanced liquid metal reactor (LMR) concepts developed by potential vendors selected by the Department of Energy. General Electric and Rockwell International continue to develop innovative design concepts aimed at improving safety, lowering plant costs, simplifying plant operation, reducing construction times, and most of all, enhancing plant licensability. The reactor program at Argonne National Laboratory (ANL) provides technical support to both organizations. The method of shutdown heat removal proposed employs a totally passive cooling system that rejects heat from the reactor by radiation and natural convection to air. The system is inherently reliable since it is not subject failure modes associated with active decay cooling systems. The system is designed to assure adequate cooling of the reactor under abnormal operating conditions associated with loss of heat removal through other heat transport paths.

  9. Optical passive athermalization for infrared zoom system

    NASA Astrophysics Data System (ADS)

    Li, Shenghui; Yang, Changcheng; Zheng, Jia; Lan, Ning; Xiong, Tao; Li, Yong

    2007-12-01

    In an infrared zoom system, it is difficult to obtain the best thermal compensation for all effective focal length (EFL) simultaneously by moving a single lens group. According to the principle of optical passive athermalization, the equations of focal length, achromatization and athermalization of both long and short EFL are established respectively. By analyzing the thermal aberration value relations between long EFL and short EFL, the thermal aberration values of the switching groups for short EFL athermalization are calculated. Firstly, the athermalization of long EFL is designed. Then through reasonable optical materials matching of the switching groups, the short EFL achieves athermalization as well. In this paper, a re-imaging switching zoom system is designed. It has a relative aperture of f/4.0, 100% cold shield efficiency, the EFL of 180mm/30mm at 3.7-4.8μm. The long EFL includes four refractive elements and one hybrid refractive/diffractive element. The switching groups of short EFL have two types, one is composed of four refractive elements, and the other is composed of two refractive elements and one hybrid refractive/diffractive element. Both of the short EFL achieve athermalization. With the aluminum materials of system structures, the zoom system achieves optical passive athermalization. It has the diffraction limited image quality and stable image plane from -30°C to 70°C.

  10. Failure detection system risk reduction assessment

    NASA Technical Reports Server (NTRS)

    Aguilar, Robert B. (Inventor); Huang, Zhaofeng (Inventor)

    2012-01-01

    A process includes determining a probability of a failure mode of a system being analyzed reaching a failure limit as a function of time to failure limit, determining a probability of a mitigation of the failure mode as a function of a time to failure limit, and quantifying a risk reduction based on the probability of the failure mode reaching the failure limit and the probability of the mitigation.

  11. Passive Accelerometer System Measurements on MIR

    NASA Technical Reports Server (NTRS)

    Alexander, J. Iwan D.

    1997-01-01

    The Passive Accelerometer System (PAS) is a simple moving ball accelerometer capable of measuring the small magnitude steady relative acceleration that occurs in a low earth orbit spacecraft due to atmospheric drag and the earth's gravity gradient. The acceleration is measured by recording the average velocity of the spherical ball over a suitable time increment. A modified form of Stokes law is used to convert the average velocity into an acceleration. PAS was used to measure acceleration on the MIR space station and on the first United States Microgravity Laboratory (USML-1). The PAS measurement on MIR revealed remarkably low acceleration levels in the SPEKTR module.

  12. Passive injection control for microfluidic systems

    DOEpatents

    Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

    2004-12-21

    Apparatus for eliminating siphoning, "dead" regions, and fluid concentration gradients in microscale analytical devices. In its most basic embodiment, the present invention affords passive injection control for both electric field-driven and pressure-driven systems by providing additional fluid flow channels or auxiliary channels disposed on either side of a sample separation column. The auxiliary channels are sized such that volumetric fluid flow rate through these channels, while sufficient to move the sample away from the sample injection region in a timely fashion, is less than that through the sample separation channel or chromatograph.

  13. Passive millimeter-wave imaging polarimeter system

    NASA Astrophysics Data System (ADS)

    Persons, Christopher M.; Martin, Christopher A.; Jones, Michael W.; Kolinko, Vladimir; Lovberg, John A.

    2009-05-01

    The Army has identified a need to rapidly identify, map, and classify natural and manmade features to aid situational awareness as well as mission and tactical planning. To address these needs, Digital Fusion and Trex Enterprises have designed a full Stokes, passive MMW imaging polarimeter that is capable of being deployed on an unmanned aerial vehicle. Results of a detailed trade study are presented, where an architecture, waveband and target platform are selected. The selected architecture is a pushbroom phased-array system, which allows the system to collect a wide fieldof- view image with minimal components and weight. W band is chosen as a trade-off between spatial resolution, weather penetration, and component availability. The trade study considers several unmanned aerial system (UAS) platforms that are capable of low-level flight and that can support the MMW antenna. The utility of the passive Stokes imager is demonstrated through W band phenomenology data collections at horizontal and vertical polarization using a variety of natural and manmade materials. The concept design is detailed, along with hardware and procedures for both radiometric and polarimetric calibration. Finally, a scaled version of the concept design is presented, which is being fabricated for an upcoming demonstration on a small, manned aircraft.

  14. Muscle size explains low passive skeletal muscle force in heart failure patients

    PubMed Central

    Maiorana, Andrew J.; Naylor, Louise H.; Dembo, Lawrence G.; Lloyd, David G.; Green, Daniel J.; Rubenson, Jonas

    2016-01-01

    Background Alterations in skeletal muscle function and architecture have been linked to the compromised exercise capacity characterizing chronic heart failure (CHF). However, how passive skeletal muscle force is affected in CHF is not clear. Understanding passive force characteristics in CHF can help further elucidate the extent to which altered contractile properties and/or architecture might affect muscle and locomotor function. Therefore, the aim of this study was to investigate passive force in a single muscle for which non-invasive measures of muscle size and estimates of fiber force are possible, the soleus (SOL), both in CHF patients and age- and physical activity-matched control participants. Methods Passive SOL muscle force and size were obtained by means of a novel approach combining experimental data (dynamometry, electromyography, ultrasound imaging) with a musculoskeletal model. Results We found reduced passive SOL forces (∼30%) (at the same relative levels of muscle stretch) in CHF vs. healthy individuals. This difference was eliminated when force was normalized by physiological cross sectional area, indicating that reduced force output may be most strongly associated with muscle size. Nevertheless, passive force was significantly higher in CHF at a given absolute muscle length (non length-normalized) and likely explained by the shorter muscle slack lengths and optimal muscle lengths measured in CHF compared to the control participants. This later factor may lead to altered performance of the SOL in functional tasks such gait. Discussion These findings suggest introducing exercise rehabilitation targeting muscle hypertrophy and, specifically for the calf muscles, exercise that promotes muscle lengthening. PMID:27672504

  15. System response in passively phased fiber amplifier arrays

    NASA Astrophysics Data System (ADS)

    Shakir, Sami A.; Culver, Bill; Nelson, Burke; Starcher, Yuji; Bates, George M.; Hedrick, Jerry W., Jr.

    2008-08-01

    System temporal response in passively phased fiber amplifier arrays dictates how fast a passively phased system can correct for phase fluctuations due to thermal and mechanical effects. The system response time was measured by employing a variable-speed mechanical chopper in the feedback loop of a passively phased system then measuring the on-axis output intensity of the system as a function of time. Observed relaxation oscillations are compared to theory. The system response time was measured to be about 20 μsec. We also find that passive phasing improved the system's beam stability and extraction efficiency.

  16. New passive solar cooking system. Final report

    SciTech Connect

    Schlussler, L.

    1981-11-01

    The development of a solar cooking system which uses a phase change process to passively transfer heat from a collector to a cooker is presented. In the design of this cooking system steam is produced in the collector and then is used as the heat transfer fluid in the cooker. The most efficient use of the system is to heat food directly by condensing the steam onto the food, whereas a heat exchanger is necessary to heat an oven or a frying pan. A pressure cooker was successfully built and tested using the steam from the collector. Brief discussions on the collector design and performance, and heat storage phase change materials are provided. (BCS)

  17. Asymptotic Stability of Interconnected Passive Non-Linear Systems

    NASA Technical Reports Server (NTRS)

    Isidori, A.; Joshi, S. M.; Kelkar, A. G.

    1999-01-01

    This paper addresses the problem of stabilization of a class of internally passive non-linear time-invariant dynamic systems. A class of non-linear marginally strictly passive (MSP) systems is defined, which is less restrictive than input-strictly passive systems. It is shown that the interconnection of a non-linear passive system and a non-linear MSP system is globally asymptotically stable. The result generalizes and weakens the conditions of the passivity theorem, which requires one of the systems to be input-strictly passive. In the case of linear time-invariant systems, it is shown that the MSP property is equivalent to the marginally strictly positive real (MSPR) property, which is much simpler to check.

  18. Incremental Passivity and Incremental Passivity-Based Output Regulation for Switched Discrete-Time Systems.

    PubMed

    Jiao Li; Jun Zhao

    2017-05-01

    This paper investigates incremental passivity and output regulation for switched discrete-time systems. We develop the results in two parts. First of all, a concept of incremental passivity is proposed to describe the overall incremental passivity property of a switched discrete-time system in the absence of the classic incremental passivity property of the subsystems. A condition for incremental passivity is given. A certain negative output feedback is designed to produce asymptotic stability. Incremental passivity is shown to be preserved under feedback interconnection. The second part of this paper is concerned with an application of the incremental passivity theory to the output regulation problem for switched discrete-time systems. The key idea is to construct a switched internal model with incremental passivity, which closely links the solvability of the output regulation problem. A characteristic of the switched internal model is that it does not necessarily switch synchronously with the controlled plant, which greatly increases the freedom of design. Once such a switched internal model is established, the output regulation problem is then solved by construction of the feedback interconnection between the controlled plant and the switched internal model. The main usefulness of the strategy is to get rid of the solvability of the output regulation problem for the subsystems.

  19. Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event

    SciTech Connect

    Bucknor, Matthew D.; Grabaskas, David; Brunett, Acacia J.; Grelle, Austin

    2016-01-01

    Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended due to deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Centering on an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive reactor cavity cooling system following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. While this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability for the reactor cavity cooling system (and the reactor system in general) to the postulated transient event.

  20. Performance of the PBX-M passive plate stabilization system

    SciTech Connect

    Kugel, H.W.; Bell, R.; Bernabei, S.

    1994-02-01

    The PBX-M passive plate stabilization system provides significant stabilization of long-wavelength external kink modes, the slowing of vertical instability growth rates, and the amelioration of disruption characteristics. The passive plate stabilization system has allowed the use of LHCD and IBW to induce current density and pressure profile modifications, and m = 1 divertor biasing for modifying edge plasma transport. Improvements in the passive plate system insulators and support structures have provided reliable operation. Impurity influxes with the close-fitting passive plates are low. Solid target boronization is applied routinely to reduce conditioning time and maintain clean conditions.

  1. Passive ALWR requirements to prevent containment failure. Advanced Reactor Severe Accident Program

    SciTech Connect

    Additon, S.L.; Blanchard, D.P.; Leaver, D.E.; Persinko, D. |

    1991-12-01

    The purpose of this report is to document a systematic evaluation of the Passive Advanced Light Water Reactor (ALWR) design requirements which address severe accident mitigation. This evaluation was performed concurrent with completion of the ALWR Requirements Document to assure the adequacy of these mitigation requirements. The passive plant approach to containment integrity assurance reflects an expansion of the approach established earlier for evolutionary ALWRs. The report identifies containment challenges that might occur coincident with or result from a core damage event, compiles the set of passive ALWR design requirements which addresses each challenge, and evaluates each set of requirements on an integrated basis to confirm that the requirements provide substantial assurance that coincident core damage and containment failure are precluded. Based on past PRAs, a review of pertinent safety functions, severe accident analyses, current regulatory requirements, and reviews by ALWR design personnel, twenty-three (23) potential containment challenges were identified. The report concludes that the relevant ALWR requirements severe to limit the likelihood and magnitude of the challenges, and to assure the capability of the containment to accommodate all challenges which remain potentially risk-significant.

  2. Passive ALWR requirements to prevent containment failure. [Advanced light water reactors

    SciTech Connect

    Additon, S.L.; Blanchard, D.P.; Leaver, D.E.; Persinko, D. TENERA, L.P., Bethesda, MD )

    1991-12-01

    The purpose of this report is to document a systematic evaluation of the Passive Advanced Light Water Reactor (ALWR) design requirements which address severe accident mitigation. This evaluation was performed concurrent with completion of the ALWR Requirements Document to assure the adequacy of these mitigation requirements. The passive plant approach to containment integrity assurance reflects an expansion of the approach established earlier for evolutionary ALWRs. The report identifies containment challenges that might occur coincident with or result from a core damage event, compiles the set of passive ALWR design requirements which addresses each challenge, and evaluates each set of requirements on an integrated basis to confirm that the requirements provide substantial assurance that coincident core damage and containment failure are precluded. Based on past PRAs, a review of pertinent safety functions, severe accident analyses, current regulatory requirements, and reviews by ALWR design personnel, twenty-three (23) potential containment challenges were identified. The report concludes that the relevant ALWR requirements severe to limit the likelihood and magnitude of the challenges, and to assure the capability of the containment to accommodate all challenges which remain potentially risk-significant.

  3. Liquid metal cooled nuclear reactors with passive cooling system

    DOEpatents

    Hunsbedt, Anstein; Fanning, Alan W.

    1991-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of cooling medium flow circuits which cooperate to remove and carry heat away from the fuel core upon loss of the normal cooling flow circuit to areas external thereto.

  4. Passive recirculation in the National Launch System's fuel feedlines

    NASA Technical Reports Server (NTRS)

    Wilson, W. R.; Holt, K. A.

    1993-01-01

    This report contains the passive recirculation tests on the fuel feedline of the National Launch System (NLS). The majority of testing was performed in February 1992, at the National Institute of Standards and Technology in Boulder, CO. The primary objective was to characterize passive recirculation in the NLS fuel feedline. The objective was met by observing the passive recirculation in a one-fifth scale model of the feedline with clear glass sections. The testing was recorded on video tape and with photographs. A description of the testing apparatus and support equipment is included. The experiment indicates that passive recirculation was occurring; higher angles from the horizontal transfer more heat.

  5. Structural system reliability under multiple failure modes

    NASA Technical Reports Server (NTRS)

    Mahadevan, S.; Chamis, C. C.

    1993-01-01

    This paper describes a computational method for system reliability estimation of propulsion structures. The failure domain of the entire structural system is computed through the union of failure regions for various critical system failure modes. The effect of non-critical progressive damage is incorporated through structural reanalysis, resulting in the construction of several linear segments to approximately cover the system failure domain. An adaptive damage imposition scheme is outlined for the sake of computational efficiency. The proposed method is used to construct the system survival cdf (cumulative distribution function) of a two-rotor system.

  6. Passive cooling safety system for liquid metal cooled nuclear reactors

    DOEpatents

    Hunsbedt, Anstein; Boardman, Charles E.; Hui, Marvin M.; Berglund, Robert C.

    1991-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

  7. Indirect passive cooling system for liquid metal cooled nuclear reactors

    DOEpatents

    Hunsbedt, Anstein; Boardman, Charles E.

    1990-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

  8. Passive solar systems performance under conditions in Bulgaria

    SciTech Connect

    Lekov, A B; Balcomb, J D

    1989-12-01

    This paper presents energy performance of 12 passive solar systems for three climatically different zones of Bulgaria. The results are compared with a base-case residential house that has a design typical for these areas. The different passive solar systems are compared on the basis of the percentage of solar savings and the yield, which is the annual net benefit of adding the passive solar system. The analyses are provided based on monthly meteorological data, and the method used for calculations is the Solar Load Ratio. Recommendations for Bulgarian conditions are given. 5 refs., 4 figs., 1 tab.

  9. On the Passivity of Hysteretic Systems with Double Hysteretic Loops

    PubMed Central

    Pozo, Francesc; Zapateiro, Mauricio

    2015-01-01

    The Bouc–Wen hysteresis model is widely employed to mathematically represent the dynamical behavior of several physical devices, materials and systems such as magnetorheological dampers, lanthanide zirconium or aluminum oxides, mechanical structures or biomedical systems. However, these mathematical models must account for different properties such as the bounded-input bounded-output stability, asymptotic motion, thermodynamic admissibility or passivity in order to be physically consistent with the systems they represent. The passivity of a system is related to energy dissipation. More precisely, a system is passive if it does not generate energy but only dissipates it. The objective of this paper is to prove that two different double-loop Bouc–Wen models are passive under a particular set of model parameters. PMID:28793719

  10. High spatial resolution passive microwave sounding systems

    NASA Technical Reports Server (NTRS)

    Staelin, D. H.; Rosenkranz, P. W.; Bonanni, P. G.; Gasiewski, A. W.

    1986-01-01

    Two extensive series of flights aboard the ER-2 aircraft were conducted with the MIT 118 GHz imaging spectrometer together with a 53.6 GHz nadir channel and a TV camera record of the mission. Other microwave sensors, including a 183 GHz imaging spectrometer were flown simultaneously by other research groups. Work also continued on evaluating the impact of high-resolution passive microwave soundings upon numerical weather prediction models.

  11. Passive Hearing Protection Systems and Their Performance

    DTIC Science & Technology

    2005-06-01

    However, these coustic energy. Additionally, earcups and earcushions offer a t often is not flat in the region in which the earcup contacts the he...to provide personnel with personal hearing protection. This protection may be in the form of either an earplug that occludes the ear canal or a ...circumaural protector that inserts a barrier between the ambient noise and the ear. For both devices the level of passive protection provided changes

  12. Functional Safety of Hybrid Laser Safety Systems - How can a Combination between Passive and Active Components Prevent Accidents?

    NASA Astrophysics Data System (ADS)

    Lugauer, F. P.; Stiehl, T. H.; Zaeh, M. F.

    Modern laser systems are widely used in industry due to their excellent flexibility and high beam intensities. This leads to an increased hazard potential, because conventional laser safety barriers only offer a short protection time when illuminated with high laser powers. For that reason active systems are used more and more to prevent accidents with laser machines. These systems must fulfil the requirements of functional safety, e.g. according to IEC 61508, which causes high costs. The safety provided by common passive barriers is usually unconsidered in this context. In the presented approach, active and passive systems are evaluated from a holistic perspective. To assess the functional safety of hybrid safety systems, the failure probability of passive barriers is analysed and added to the failure probability of the active system.

  13. Failure of Real-time Passive Notification about Radiation Exposure to Influence Physician Ordering Behavior.

    PubMed

    Polen, Lauren A; Rossi, Jennifer K; Berg, Cameron K; Balise, Raymond R; Herfkens, Robert J; Auerbach, Paul S

    2016-07-15

    Objectives  To determine whether real-time passive notification of patient radiation exposure via a computerized physician order entry system would alter the number of computed tomography scans ordered by physicians in the Emergency Department (ED) setting. Methods  When a practitioner ordered a computed tomography scan, a passive notification was immediately and prominently displayed via the computerized physician order entry system. The notification stated the following: the amount of estimated radiation in millisieverts (mSv), the equivalent number of single-view chest radiographs, and equivalent days of average environmental background radiation to which a patient during a specific computed tomography scan would be exposed. The primary outcome was changed in the number of computed tomography scans ordered when comparing data collected before and after the addition of the notification. Results  Before the dosimetry notification ("intervention") was instituted, 1,747 computed tomography scans were performed on patients during 11,709 Emergency Department visits (14.9% computed tomography scan rate). After the intervention had been instituted, 1,827 computed tomography scans were performed on patients during 11,582 Emergency Department patient visits (15.8% computed tomography scan rate). No statistically significant difference was found for all chief complaints combined (p = 0.17), or for any individual chief complaint, between the number of computed tomography scans performed on Emergency Department patients before versus after the intervention. Conclusions  Passive real-time notification of patient radiation exposure displayed in a computerized physician order entry system at the time of computed tomography scan ordering in the Emergency Department did not significantly change the number of ordered scans.

  14. Failure of Real-time Passive Notification about Radiation Exposure to Influence Physician Ordering Behavior

    PubMed Central

    Polen, Lauren A; Rossi, Jennifer K; Berg, Cameron K; Balise, Raymond R; Herfkens, Robert J

    2016-01-01

    Objectives  To determine whether real-time passive notification of patient radiation exposure via a computerized physician order entry system would alter the number of computed tomography scans ordered by physicians in the Emergency Department (ED) setting. Methods  When a practitioner ordered a computed tomography scan, a passive notification was immediately and prominently displayed via the computerized physician order entry system. The notification stated the following: the amount of estimated radiation in millisieverts (mSv), the equivalent number of single-view chest radiographs, and equivalent days of average environmental background radiation to which a patient during a specific computed tomography scan would be exposed. The primary outcome was changed in the number of computed tomography scans ordered when comparing data collected before and after the addition of the notification. Results  Before the dosimetry notification (“intervention”) was instituted, 1,747 computed tomography scans were performed on patients during 11,709 Emergency Department visits (14.9% computed tomography scan rate). After the intervention had been instituted, 1,827 computed tomography scans were performed on patients during 11,582 Emergency Department patient visits (15.8% computed tomography scan rate). No statistically significant difference was found for all chief complaints combined (p = 0.17), or for any individual chief complaint, between the number of computed tomography scans performed on Emergency Department patients before versus after the intervention. Conclusions  Passive real-time notification of patient radiation exposure displayed in a computerized physician order entry system at the time of computed tomography scan ordering in the Emergency Department did not significantly change the number of ordered scans.  PMID:27570716

  15. The Failure Analysis in Traction Power System

    NASA Astrophysics Data System (ADS)

    Kim, Hyungchul; Heo, Guk-bum; Lee, Hyungwoo; Kim, Dong Jin; Kim, Jin O.

    2008-10-01

    This paper presents a failure analysis of traction power systems. The electric railway consists of traction power systems, various vehicles, operating equipment, track, overhead line and electric equipment. It is a fundamental function of traction power systems that they supply customers with acceptable reliability and high quality power. Perhaps the most commonly used reliability assessment for railway systems has been the failure analysis of the traction signal system. The reliability assessment of traction power systems has also been an indispensable issue for reliability assessment. This paper deals with the classification of railway accidents caused by electrification problems, the estimation of failure rate in power equipments and failure analysis using fault trees. In study cases, the fault tree method for failure analysis is applied to railway substations in South Korea.

  16. Passive integral solar heat collector system

    SciTech Connect

    Feldman Jr., K. T.

    1985-04-30

    The present invention relates to an improved apparatus for collecting, absorbing, transferring, and storing solar heat energy, economically and passively, without pumps or electric power. The apparatus comprises a solar collector with a flat finned heat pipe absorber and an attached integral insulated storage tank with a double wall heat exchanger. The absorber, made of one or more slightly tilted gravity assisted heat pipes with flat absorber fins, absorbs and transfers solar heat by evaporation, vapor transport, and condensation to the slightly elevated heat storage tank. The one or more heat pipes turn on when the sun is shining and turn off automatically when the sun is not shining.

  17. Passive cooling system for nuclear reactor containment structure

    DOEpatents

    Gou, Perng-Fei; Wade, Gentry E.

    1989-01-01

    A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

  18. Natural circulating passive cooling system for nuclear reactor containment structure

    DOEpatents

    Gou, Perng-Fei; Wade, Gentry E.

    1990-01-01

    A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

  19. Time-to-impact estimation in passive missile warning systems

    NASA Astrophysics Data System (ADS)

    Şahıngıl, Mehmet Cihan

    2017-05-01

    A missile warning system can detect the incoming missile threat(s) and automatically cue the other Electronic Attack (EA) systems in the suit, such as Directed Infrared Counter Measure (DIRCM) system and/or Counter Measure Dispensing System (CMDS). Most missile warning systems are currently based on passive sensor technology operating in either Solar Blind Ultraviolet (SBUV) or Midwave Infrared (MWIR) bands on which there is an intensive emission from the exhaust plume of the threatening missile. Although passive missile warning systems have some clear advantages over pulse-Doppler radar (PDR) based active missile warning systems, they show poorer performance in terms of time-to-impact (TTI) estimation which is critical for optimizing the countermeasures and also "passive kill assessment". In this paper, we consider this problem, namely, TTI estimation from passive measurements and present a TTI estimation scheme which can be used in passive missile warning systems. Our problem formulation is based on Extended Kalman Filter (EKF). The algorithm uses the area parameter of the threat plume which is derived from the used image frame.

  20. Reversal of chronic molecular and cellular abnormalities due to heart failure by passive mechanical ventricular containment.

    PubMed

    Sabbah, Hani N; Sharov, Victor G; Gupta, Ramesh C; Mishra, Sudhish; Rastogi, Sharad; Undrovinas, Albertas I; Chaudhry, Pervaiz A; Todor, Anastassia; Mishima, Takayuki; Tanhehco, Elaine J; Suzuki, George

    2003-11-28

    Passive mechanical containment of failing left ventricle (LV) with the Acorn Cardiac Support Device (CSD) was shown to prevent progressive LV dilation in dogs with heart failure (HF) and increase ejection fraction. To examine possible mechanisms for improved LV function with the CSD, we examined the effect of CSD therapy on the expression of cardiac stretch response proteins, myocyte hypertrophy, sarcoplasmic reticulum Ca2+-ATPase activity and uptake, and mRNA gene expression for myosin heavy chain (MHC) isoforms. HF was produced in 12 dogs by intracoronary microembolization. Six dogs were implanted with the CSD and 6 served as concurrent controls. LV tissue from 6 normal dogs was used for comparison. Compared with normal dogs, untreated HF dogs showed reduced cardiomyocyte contraction and relaxation, upregulation of stretch response proteins (p21ras, c-fos, and p38 alpha/beta mitogen-activated protein kinase), increased myocyte hypertrophy, reduced SERCA2a activity with unchanged affinity for calcium, reduced proportion of mRNA gene expression for alpha-MHC, and increased proportion of beta-MHC. Therapy with the CSD was associated with improved cardiomyocyte contraction and relaxation, downregulation of stretch response proteins, attenuation of cardiomyocyte hypertrophy, increased affinity of the pump for calcium, and restoration of alpha- and beta-MHC isoforms ratio. The results suggest that preventing LV dilation and stretch with the CSD promotes downregulation of stretch response proteins, attenuates myocyte hypertrophy and improves SR calcium cycling. These data offer possible mechanisms for improvement of LV function after CSD therapy.

  1. Probabilistic Analysis of Passive Safety System Reliability in Advanced Small Modular Reactors: Methodologies and Lessons Learned

    SciTech Connect

    Grabaskas, David; Bucknor, Matthew; Brunett, Acacia; Grelle, Austin

    2015-06-28

    Many advanced small modular reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended due to deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize with a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper describes the most promising options: mechanistic techniques, which share qualities with conventional probabilistic methods, and simulation-based techniques, which explicitly account for time-dependent processes. The primary intention of this paper is to describe the strengths and weaknesses of each methodology and highlight the lessons learned while applying the two techniques while providing high-level results. This includes the global benefits and deficiencies of the methods and practical problems encountered during the implementation of each technique.

  2. Prevalence of failure of passive transfer of immunity in newborn heifer calves and associated management practices on US dairy operations.

    PubMed

    Beam, A L; Lombard, J E; Kopral, C A; Garber, L P; Winter, A L; Hicks, J A; Schlater, J L

    2009-08-01

    Failure of passive transfer of immunity (FPT) in dairy replacement calves has been linked to increased neonatal morbidity and mortality and long-term decreases in productivity. The purpose of this study was to estimate the prevalence of FPT in US dairy heifer calves in 2007 and to use nationally representative data to investigate associations of FPT with colostrum and calf management practices. A cross-sectional study was conducted by the USDA's National Animal Health Monitoring System between January and August 2007. Producers from 394 operations in 17 states completed survey questions about colostrum and calf management practices, and serum samples were collected from 1,816 healthy heifer calves on those operations. Serum immunoglobulin G (IgG) levels were determined by radial immunodiffusion, and calves were classified as having FPT if the IgG concentration was less than 10 mg/mL. To investigate associations between FPT and management practices, a multivariable analysis was completed using a weighted logistic regression model. The estimated prevalence of FPT in US dairy heifer calves was 19.2%. The odds of FPT were higher for calves on operations that pooled colostrum [odds ratio (OR = 2.2)], allowed nursing (OR = 2.4), or hand fed colostrum more than 4 h after birth (OR = 2.7). The odds of FPT were also higher for calves on operations that did not provide a source of heat during cold weather for calves experiencing a dystocia (OR = 1.6), would not seek veterinary assistance when unable to correctly position a calf for delivery (OR = 2.6), or did not routinely monitor serum proteins in calves as a measure of passive transfer (OR = 13.8). The prevalence of FPT in dairy heifer calves has decreased in the last 15 yr, so progress has been made in this important area of calf management. This study identified several management practices associated with FPT that could be targeted for educational campaigns or further research.

  3. The Development of a Demonstration Passive System Reliability Assessment

    SciTech Connect

    Bucknor, Matthew; Grabaskas, David; Brunett, Acacia

    2014-06-22

    In this paper, the details of the development of a demonstration problem to assess the reliability of a passive safety system are presented. An advanced small modular reactor (advSMR) design, which is a pool-type sodium fast reactor (SFR) coupled with a passive reactor cavity cooling system (RCCS) is described. The RELAP5-3D models of the advSMR and RCCS that will be used to simulate a long-term station blackout (SBO) accident scenario are presented. Proposed benchmarking techniques for both the reactor and the RCCS are discussed, which includes utilization of experimental results from the Natural convection Shutdown heat removal Test Facility (NSTF) at the Argonne National Laboratory. Details of how mechanistic methods, specifically the Reliability Method for Passive Systems (RMPS) approach, will be utilized to determine passive system reliability are presented. The results of this mechanistic analysis will ultimately be compared to results from dynamic methods in future work. This work is part of an ongoing project at Argonne to demonstrate methodologies for assessing passive system reliability.

  4. Socks for the dilated heart. Does passive cardiomyoplasty have a role in long-term care for heart failure patients?

    PubMed

    Gummert, J F; Rahmel, A; Bossert, T; Mohr, F W

    2004-11-01

    Dynamic cardiomyoplasty has been performed in over 1000 patients worldwide but due to limited success the procedure was never been adopted as an alternative approach for the surgical therapy of heart failure. However, observations in these patients showed that the nonstimulated or fibrotic transformed latissimus dorsi by itself led to an improvement of heart failure symptoms. These findings stimulated animal experiments with so-called passive cardiomyoplasty devices. In several animal models, the progression of heart failure could be stopped, and even reversed remodeling could be demonstrated. Several different devices have been developed and tested in animal models. The Acorn CorCap has already passed a successful clinical feasibility study. However, the final evaluation of two multicenter trials has to be awaited to assess the future role of this device in the treatment of heart failure.

  5. Production systems need negation as failure

    SciTech Connect

    Phan Minh Dung; Mancarella, P.

    1996-12-31

    We study action rule based systems with two forms of negation, namely classical negation and {open_quotes}negation as failure to find a course of actions{close_quotes}. We show by several examples that adding negation as failure to such systems increase their expressiveness, in the sense that real life problems can be represented in a natural and simple way. Then, we address the problem of providing a formal declarative semantics to these extended systems, by adopting an argumentation based approach, which has been shown to be a simple unifying framework for understanding the declarative semantics of various nonmonotonic formalisms. In this way, we naturally define the grounded (well-founded), stable and preferred semantics for production systems with negation as failure. Next, we characterize the class of stratified production systems, which enjoy the properties that the above mentioned semantics coincide and that negation as failure can be computed by a simple bottom-up operator.

  6. Humanized mouse model of mast cell-mediated passive cutaneous anaphylaxis and passive systemic anaphylaxis.

    PubMed

    Bryce, Paul J; Falahati, Rustom; Kenney, Laurie L; Leung, John; Bebbington, Christopher; Tomasevic, Nenad; Krier, Rebecca A; Hsu, Chia-Lin; Shultz, Leonard D; Greiner, Dale L; Brehm, Michael A

    2016-09-01

    Mast cells are a critical component of allergic responses in humans, and animal models that allow the in vivo investigation of their contribution to allergy and evaluation of new human-specific therapeutics are urgently needed. To develop a new humanized mouse model that supports human mast cell engraftment and human IgE-dependent allergic responses. This model is based on the NOD-scid IL2rg(null)SCF/GM-CSF/IL3 (NSG-SGM3) strain of mice engrafted with human thymus, liver, and hematopoietic stem cells (termed Bone marrow, Liver, Thymus [BLT]). Large numbers of human mast cells develop in NSG-SGM3 BLT mice and populate the immune system, peritoneal cavity, and peripheral tissues. The human mast cells in NSG-SGM3 BLT mice are phenotypically similar to primary human mast cells and express CD117, tryptase, and FcεRI. These mast cells undergo degranulation in an IgE-dependent and -independent manner, and can be readily cultured in vitro for additional studies. Intradermal priming of engrafted NSG-SGM3 mice with a chimeric IgE containing human constant regions resulted in the development of a robust passive cutaneous anaphylaxis response. Moreover, we describe the first report of a human mast cell antigen-dependent passive systemic anaphylaxis response in primed mice. NSG-SGM3 BLT mice provide a readily available source of human mast cells for investigation of mast cell biology and a preclinical model of passive cutaneous anaphylaxis and passive systemic anaphylaxis that can be used to investigate the pathogenesis of human allergic responses and to test new therapeutics before their advancement to the clinic. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  7. Development of a portable passive-acoustic bedload monitoring system

    USDA-ARS?s Scientific Manuscript database

    A hydrophone-based passive acoustic bedload-monitoring system was designed, tested and deployed by researchers at the University of Mississippi and the National Sedimentation Laboratory in Oxford, MS. The hydrophone system was designed to be easily deployed and operated by non-experts. In addition, ...

  8. The Mechanoreflex and Hemodynamic Response to Passive Leg Movement in Heart Failure

    PubMed Central

    Ives, Stephen J.; Amann, Markus; Venturelli, Massimo; Witman, Melissa A. H.; Groot, H. Jonathan; Wray, D. Walter; Morgan, David E.; Stehlik, Josef; Richardson, Russell S.

    2015-01-01

    Background Sensitization of mechanosensitive afferents, which contribute to the exercise pressor reflex (EPR) has been recognized as a characteristic of patients with heart failure (HF), however, the hemodynamic implications of this hypersensitivity are unclear. Objectives The present study utilized passive leg movement (PLM) and intrathecal injection of fentanyl to blunt the afferent portion of this reflex arc to better understand the role of the mechanoreflex on central and peripheral hemodynamics in HF. Methods Femoral blood flow (FBF), mean arterial pressure (MAP), femoral vascular conductance (FVC), heart rate (HR), stroke volume (SV), cardiac output (CO), ventilation (VE), and muscle oxygenation of the vastus lateralis, were assessed in 10 NYHA class II HF patients at baseline and during 3-min of PLM both with fentanyl and without (control). Results Fentanyl had no effect on baseline measures, but increased (p<0.05, control vs. fentanyl) the peak PLM-induced change in FBF (493±155 vs. 804±198 ΔmL/min), and FVC (4.7±2 vs. 8.5±3 ΔmL/min/mmHg), while norepinephrine spillover (103±19 vs. 58±17 %Δ), and retrograde FBF (371±115 vs. 260±68 ΔmL/min) tended to be reduced (p<0.10). Additionally, fentanyl administration resulted in greater PLM-induced increases in muscle oxygenation, suggestive of increased microvascular perfusion. Fentanyl had no effect on the VE, MAP, HR, SV, or CO response to PLM. Conclusions Although movement-induced central hemodynamics were unchanged by afferent blockade, peripheral hemodynamic responses were significantly enhanced. Thus, in patients with HF a heightened mechanoreflex appears to augment peripheral sympathetic vasoconstriction in response to movement, a phenomenon that may contribute to exercise intolerance in this population. PMID:26418560

  9. Role of passive remote sensors. Sensor System Panel report

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Capabilities of present passive systems are described and the development of passive remote sensing systems for the more abundant tropospheric trace species is recommended. The combination of nadir-viewing spectrometers and solar occultation for tropospheric measurement of those gases having large stratospheric burdens is discussed. Development of a nadir-viewing instrument capable of obtaining continuous spectra in narrower bands is recommended. Gas filter radiometers for species specific measurements and development of a spectral survey instrument are discussed. Further development of aerosol retrieval algorithms, including polarization techniques, for obtaining aerosol thickness and size distributions is advised. Recommendations of specific investigations to be pursued are presented.

  10. Valve system incorporating single failure protection logic

    DOEpatents

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  11. Large-scale smart passive system for civil engineering applications

    NASA Astrophysics Data System (ADS)

    Jung, Hyung-Jo; Jang, Dong-Doo; Lee, Heon-Jae; Cho, Sang-Won

    2008-03-01

    The smart passive system consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) part has been recently proposed. An EMI part can generate the input current for an MR damper from vibration of a structure according to Faraday's law of electromagnetic induction. The control performance of the smart passive system has been demonstrated mainly by numerical simulations. It was verified from the numerical results that the system could be effective to reduce the structural responses in the cases of civil engineering structures such as buildings and bridges. On the other hand, the experimental validation of the system is not sufficiently conducted yet. In this paper, the feasibility of the smart passive system to real-scale structures is investigated. To do this, the large-scale smart passive system is designed, manufactured, and tested. The system consists of the large-capacity MR damper, which has a maximum force level of approximately +/-10,000N, a maximum stroke level of +/-35mm and the maximum current level of 3 A, and the large-scale EMI part, which is designed to generate sufficient induced current for the damper. The applicability of the smart passive system to large real-scale structures is examined through a series of shaking table tests. The magnitudes of the induced current of the EMI part with various sinusoidal excitation inputs are measured. According to the test results, the large-scale EMI part shows the possibility that it could generate the sufficient current or power for changing the damping characteristics of the large-capacity MR damper.

  12. Passive vapor transport solar heating systems

    SciTech Connect

    Hedstrom, J.C.; Neeper, D.A.

    1985-01-01

    In the systems under consideration, refrigerant is evaporated in a solar collector and condensed in thermal storage for space or water heating located within the building at a level below that of the collector. Condensed liquid is lifted to an accumulator above the collector by the vapor pressure generated in the collector. Tests of two systems are described, and it is concluded that one of these systems offers distinct advantages.

  13. Accommodating Actuator Failures in Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Hess, R. A.; Siwakosit, W.; Chung, J.

    1998-01-01

    A technique for the design of flight control systems that can accommodate a set of actuator failures is presented. As employed herein, an actuator failure is defined as any change in the parametric model of the actuator which can adversely affect actuator performance. The technique is based upon the formulation of a fixed feedback topology which ensures at least stability in the presence of the failures in the set. The fixed compensation is obtained from a loop-shaping design procedure similar to Quantitative Feedback Theory and provides stability robustness in the presence of uncertainty in the vehicle dynamics caused by the failures. System adaptation to improve performance after actuator failure(s) occurs through a static gain adjustment in the compensator followed by modification of the system prefilter. Precise identification of the vehicle dynamics is unnecessary. Application to a single-input, single-output design using a simplified model of the longitudinal dynamics of the NASA High Angle of Attack Research Vehicle is discussed. Non-real time simulations of the system including a model of the pilot demonstrate the effectiveness and limitations of the approach.

  14. Research Relative to High Spatial Resolution Passive Microwave Sounding Systems

    NASA Technical Reports Server (NTRS)

    Staelin, D. H.; Rosenkranz, P. W.

    1984-01-01

    Methods to obtain high resolution passive microwave weather observations, and understanding of their probable impact on numerical weather prediction accuracy were investigated. The development of synthetic aperture concepts for geosynchronous passive microwave sounders were studied. The effects of clouds, precipitation, surface phenomena, and atmospheric thermal fine structure on a scale of several kilometers were examined. High resolution passive microwave sounders (e.g., AMSU) with an increased number of channels will produce initialization data for numerical weather prediction (NWP) models with both increased spatial resolution and coverage. The development of statistical models for error growth in high resolution primitive equation NWP models which permit the consequences of various observing system alternatives, including sensors and assimilation times and procedures is discussed. A high resolution three dimensional primitive equation NWP model to determine parameters in an error growth model similar to that formulated by Lorenz, but with more degrees of freedom is utilized.

  15. Passive dynamic controllers for non-linear mechanical systems

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.

    1992-01-01

    The objective is to develop active model-independent controllers for slewing and vibration control of nonlinear multibody flexible systems, including flexible robots. The topics are presented in viewgraph form and include: passive stabilization; work-energy rate principle; Liapunov theory; displacement feedback; dynamic controller; displacement and acceleration feedback; velocity feedback; displacement feedback; physical interaction; a 6-DOF robot; and simulation results.

  16. Cooling-load implications for residential passive solar heating systems

    NASA Astrophysics Data System (ADS)

    Jones, R. W.; McFarland, R. D.

    1983-11-01

    The quantification of cooling loads in residential buildings, particularly buildings with passive solar heating systems, is described, along with the computer simulation model used for calculating cooling loads. A sample of interim results is also presented. The objective of the research is to develop a simple analysis method, useful early in the design, to estimate the annual cooling energy requirement of a given building.

  17. Design of short-range terahertz wave passive detecting system

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Lou, Guowei; Zhu, Li; Qian, Songsong; Li, Ting

    2016-09-01

    Based on the study of radiation and transmission characteristics on THz waveband, a short-range passive detecting system is designed. The scheme originated from microwave passive detecting system. A prototype was developed following the design of key components including antennas and a harmonic mixer. The system operated at 0.36 THz. A dual-beam Cassegrain antenna was adopted for receiving signals which radiated by object and background. Local oscillator signal was generated by frequency multiplication. Harmonic mixing is adopted for reducing local oscillator signal frequency required by half. Superheterodyne technology is employed for signal acquisition. The system implemented easily. Tests and measurements were taken, which showed that the scheme was feasible and the performance of the prototype system met the design requirements.

  18. Passive dynamic controllers for non-linear mechanical systems

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.

    1991-01-01

    A methodology for model-independent controller design for controlling large angular motion of multi-body dynamic systems is outlined.The controlled system may consist of rigid and flexible components that undergo large rigid body motion and small elastic deformations. Control forces/torques are applied to drive the system, and at the same time suppress the vibrations due to flexibility of the components. The proposed controller consists of passive second-order systems which may be designed with little knowledge of the system parameters, even if the controlled system is non-linear. Under rather general assumptions, the passive design assures that the closed loop system has guaranteed stability properties. Unlike positive real controller design, stabilization can be accomplished without direct velocity feedback. In addition, the second-order passive design allows dynamic feedback controllers with considerable freedom to tune for desired system response, and to avoid actuator saturation. After developing the basic mathematical formulation of the design methodology, simulation results are presented to illustrate the proposed approach applied to a flexible six-degree-of-freedom manipulator.

  19. Passive dynamic controllers for non-linear mechanical systems

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.

    1991-01-01

    A methodology for model-independent controller design for controlling large angular motion of multi-body dynamic systems is outlined.The controlled system may consist of rigid and flexible components that undergo large rigid body motion and small elastic deformations. Control forces/torques are applied to drive the system, and at the same time suppress the vibrations due to flexibility of the components. The proposed controller consists of passive second-order systems which may be designed with little knowledge of the system parameters, even if the controlled system is non-linear. Under rather general assumptions, the passive design assures that the closed loop system has guaranteed stability properties. Unlike positive real controller design, stabilization can be accomplished without direct velocity feedback. In addition, the second-order passive design allows dynamic feedback controllers with considerable freedom to tune for desired system response, and to avoid actuator saturation. After developing the basic mathematical formulation of the design methodology, simulation results are presented to illustrate the proposed approach applied to a flexible six-degree-of-freedom manipulator.

  20. Forewarning of Failure in Complex Systems

    SciTech Connect

    Abercrombie, Robert K; Hively, Lee M; Prowell, Stacy J; Schlicher, Bob G; Sheldon, Frederick T

    2011-01-01

    As the critical infrastructures of the United States have become more and more dependent on public and private networks, the potential for widespread national impact resulting from disruption or failure of these networks has also increased. Securing the nation s critical infrastructures requires protecting not only their physical systems but, just as important, the cyber portions of the systems on which they rely. A failure is inclusive of random events, design flaws, and instabilities caused by cyber (and/or physical) attack. One such domain is failure in critical equipment. A second is aging bridges. We discuss the workings of such a system in the context of the necessary sensors, command and control and data collection as well as the cyber security efforts that would support this system. Their application and the implications of this computing architecture are also discussed, with respect to our nation s aging infrastructure.

  1. Modeling of High Capacity Passive Cooling System

    DTIC Science & Technology

    2009-03-01

    Cooling System Case Number: AOARD-084029 Contract Number: FA4869-08- 1 -4029 Award Period: 06 March 2008 to 06 March 2009 Report Documentation...Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including...failing to comply with a collection of information if it does not display a currently valid OMB control number. 1 . REPORT DATE 28 OCT 2009 2. REPORT

  2. Robust Stabilization of a Class of passive Nonlinear Systems

    NASA Technical Reports Server (NTRS)

    Joshi, Suresh M.; Kelkar, Atul G.

    1996-01-01

    The problem of feedback stabilization is considered for a class of nonlinear, finite dimensional, time invariant passive systems that are affine in control. Using extensions of the Kalman-Yakubovch lemma, it is shown that such systems can be stabilized by a class of finite demensional, linear, time-invariant controllers which are strictly positive real in the weak or marginal sense. The stability holds regardless of model uncertainties, and is therefore, robust.

  3. Development of Passive Diver Thermal Protection System

    DTIC Science & Technology

    1983-05-01

    underwater swims .,(- /A *vi t S/N 01 2- IFP- 014- 6401 SUCURITY CLAWFIICATIO" OFr TNIS PAQUIP10t1 DW BOOV04• I ~~~/ / ", NCSC TM 378-83 SUMMARY Cold water...independent suit inflation source, inflation hoses, a Diver Urine Collection System (DUCS) for long duration missions, fin guards to prevent loss of swim ...dry suits were tested for comparative mobility by the Department of Kinesiology , University of California, Los Angeles. 3 Experienced divers evaluated

  4. Passive shut-down heat removal system

    DOEpatents

    Hundal, Rolv; Sharbaugh, John E.

    1988-01-01

    An improved shut-down heat removal system for a liquid metal nuclear reactor of the type having a vessel for holding hot and cold pools of liquid sodium is disclosed herein. Generally, the improved system comprises a redan or barrier within the reactor vessel which allows an auxiliary heat exchanger to become immersed in liquid sodium from the hot pool whenever the reactor pump fails to generate a metal-circulating pressure differential between the hot and cold pools of sodium. This redan also defines an alternative circulation path between the hot and cold pools of sodium in order to equilibrate the distribution of the decay heat from the reactor core. The invention may take the form of a redan or barrier that circumscribes the inner wall of the reactor vessel, thereby defining an annular space therebetween. In this embodiment, the bottom of the annular space communicates with the cold pool of sodium, and the auxiliary heat exchanger is placed in this annular space just above the drawn-down level that the liquid sodium assumes during normal operating conditions. Alternatively, the redan of the invention may include a pair of vertically oriented, concentrically disposed standpipes having a piston member disposed between them that operates somewhat like a pressure-sensitive valve. In both embodiments, the cessation of the pressure differential that is normally created by the reactor pump causes the auxiliary heat exchanger to be immersed in liquid sodium from the hot pool. Additionally, the redan in both embodiments forms a circulation flow path between the hot and cold pools so that the decay heat from the nuclear core is uniformly distributed within the vessel.

  5. Active and passive calcium transport systems in plant cells

    SciTech Connect

    Sze, H.

    1990-01-01

    The ability to change cytoplasmic Ca{sup 2+} levels ((Ca{sup 2+})) by cells has made this cation a key regulator of many biological processes. Cytoplasmic (Ca{sup 2+}) is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic (Ca{sup 2+}) and active Ca{sup 2+} transport systems that lower cytosolic (Ca{sup 2+}). The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells. 10 figs., 2 tabs.

  6. Active and passive calcium transport systems in plant cells

    SciTech Connect

    Sze, H.

    1991-01-01

    The ability to change cytoplasmic Ca{sup 2+} levels ((Ca{sup 2+})) by cells has made this cation a key regulator of many biological processes. Cytoplasmic (Ca{sup 2+}) is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic (Ca{sup 2+}) and active Ca{sup 2+} transport systems that lower cytosolic (Ca{sup 2+}). The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells.

  7. Passive, achromatic, nearly isochronous bending system

    DOEpatents

    Douglas, David R.; Yunn, Byung C.

    2004-05-18

    A particle beam bending system having a geometry that applies active bending only beyond the chord of the orbit for any momentum component. Using this bending configuration, all momentum components emerge dispersed in position only; all trajectories are parallel by construction. Combining a pair of such bends with reflective symmetry produces a bend cell that is, by construction, achromatic to all orders. By the particular choice of 45.degree. individual bends, a pair of such achromats can be used as the basis of a 180.degree. recirculation arc. Other rational fractions of a full 180.degree. bend serve equally well (e.g., 2 bends/cell.times.90.degree./bend.times.1 cell /arc; 2 bends/cell.times.30.degree./bend.times.3 cells/arc, etc), as do combinations of multiple bending numerologies (e.g., 2 bends/cell.times.22.5.degree./bend.times.2 cells+2 bends/cell.times.45.degree./bend.times.1 cell). By the choice of entry pole face rotation of the first magnet and exit pole face rotation of the second magnet (with a value to be determined from the particular beam stability requirements imposed by the choice of bending angle and beam properties to be used in any particular application), desirable focusing properties can be introduced and beam stability can be insured.

  8. Antenna array geometry optimization for a passive coherent localisation system

    NASA Astrophysics Data System (ADS)

    Knott, Peter; Kuschel, Heiner; O'Hagan, Daniel

    2012-11-01

    Passive Coherent Localisation (PCL), also known as Passive Radar, making use of RF sources of opportunity such as Radio or TV Broadcasting Stations, Cellular Phone Network Base Stations, etc. is an advancing technology for covert operation because no active radar transmitter is required. It is also an attractive addition to existing active radar stations because it has the potential to discover low-flying and low-observable targets. The CORA (Covert Radar) experimental passive radar system currently developed at Fraunhofer-FHR features a multi-channel digital radar receiver and a circular antenna array with separate elements for the VHF- and the UHF-range and is used to exploit alternatively Digital Audio (DAB) or Video Broadcasting (DVB-T) signals. For an extension of the system, a wideband antenna array is being designed for which a new discone antenna element has been developed covering the full DVB-T frequency range. The present paper describes the outline of the system and the numerical modelling and optimisation methods applied to solve the complex task of antenna array design: Electromagnetic full wave analysis is required for the parametric design of the antenna elements while combinatorial optimization methods are applied to find the best array positions and excitation coefficients for a regular omni-directional antenna performance. The different steps are combined in an iterative loop until the optimum array layout is found. Simulation and experimental results for the current system will be shown.

  9. Thoracoscopic surgery support system using passive RFID marker.

    PubMed

    Takahata, Hiromi; Kojima, Fumitsugu; Okada, Minoru; Sugiura, Tadao; Sato, Toshihiko; Oshiro, Osamu

    2012-01-01

    This paper proposes a RFID based thoracoscopic surgery support system, which is capable of marking a tumor inside organ tissue. The marker composed of small RFID-tags is implanted in the vicinity of tumor found in the endoscopy test. In the thoracoscopic surgery operation for removing the tumor, an RFID detector determines the accurate position of the implanted RFID-tag markers by measuring the strength of the signal emitted from the target tag. Due to limitation in the size of RFID-tag, the proposed system employs a passive RFID. To activate the passive tag implanted in the organ tissue, this paper designs a saddle-shape efficient power supply antenna. A sensitive and frequency-selective receiver is then designed for detecting the weak signal from the tag. The feasibility test confirms that the proposed method is capable of determining the accurate location of RFID tags implanted in the patient's organ tissue.

  10. Passive vibration isolation for long range aerial reconnaissance systems

    NASA Astrophysics Data System (ADS)

    Otoole, J.

    1980-01-01

    The paper discusses an approach to the design of a passive isolation system for a high-altitude, long-range oblique reconnaissance camera which works in conjunction with the active, gyro-stabilized system to attenuate a broad spectrum of vibratory inputs. The proposed design provides an elastic suspension system with minimum damping forces and a damping system which controls the excursions of the camera in the resonant region of disturbance; it has both spring and damping forces in complete balance about the center of gravity of the camera. Mathematical equations and definition in support of the proposed approach are presented together with some pertinent data.

  11. Comparison of motion and stereo methods in passive ranging systems

    NASA Technical Reports Server (NTRS)

    Sridhar, Banavar; Suorsa, Raymond

    1991-01-01

    The authors compare the estimates in passive ranging systems using motion and stereo approaches. It is shown that an integrated approach is necessary to provide better range estimates over a field-of-view (FOV) of interest in helicopter flight. The recursive approach for processing a sequence of stereo images, described together with a recursive motion algorithm (RMA), provides the basis for an integrated method to provide more accurate range information. Results based on motion sequences of stereo images are presented.

  12. Passive optical computerized tracking system with graphic replay

    NASA Astrophysics Data System (ADS)

    Johnston, Donald R.

    1993-01-01

    The system has been designed for instant sports replay. The passive unit utilizes two video cameras, an image processor, and a graphics computer to track the baseball pitch and provide an instant graphic replay of the pitch, showing the ball's trajectory, speed, and movement. Shown on the 1991 World Series, it has applications for both team training and game broadcasting as well as other sports.

  13. Commutation failures in HVDC transmission systems

    SciTech Connect

    Thio, C.V.; Davies, J.B.; Kent, K.L.

    1996-04-01

    This paper provides a formulation for the initiation or onset mechanism of commutation failures in line-commutated thyristor converters, assuming infinite (zero impedance) ac systems. A theoretical development and a parametric analysis is given. Theory validation by simulation and comparison to actual field experience data is also given.

  14. Exclusion: Failed Children or Systems Failure?

    ERIC Educational Resources Information Center

    Parfrey, Vanessa

    1994-01-01

    Using accelerating exclusion rates from one British local education authority shows that some children--particularly certain adolescents--are becoming scapegoats of systemic failure. By being excluded, these children are deprived of their rights to education and proper attention to their emotional and behavioral needs. Responsible parties must…

  15. [Remote passive sensing of aeroengine exhausts using FTIR system].

    PubMed

    Xia, Qing; Zuo, Hong-Fu; Li, Shao-Cheng; Wen, Zhen-Hua; Li, Yao-Hua

    2009-03-01

    The traditional method of measuring the aeroengine exhausts is intrusive gas sampling analysis techniques. The disadvantages of the techniques include complex system, difficult operation, high costs and potential danger because of back-pressure effects. The non-intrusive methods have the potential to overcome these problems. So the remote FTIR passive sensing is applied to monitor aeroengine exhausts and determine the concentration of the exhausts gases of aeroengines. The principle of FTIR remote passive sensing is discussed. The model algorithm for the calibration of FTIR system, the radiance power distribution and gas concentration are introduced. TENSOR27 FTIR-system was used to measure the spectra of infrared radiation emitted by the hot gases of exhausts in a test rig. The emission spectra of exhausts were obtained under different thrusts. By analyzing the spectra, the concentrations of CO2, CO and NO concentration were calculated under 4 thrusts. Researches on the determination of concentration of the exhausts gases of aeroengines by using the remote FTIR sensing are still in early stage in the domestic aeronautics field. The results of the spectra and concentration in the aeroengine test are published for the first time. It is shown that the remote FTIR passive sensing techniques have a great future in monitoring the hot gas of the aeroengines exhausts.

  16. Causes of catastrophic failure in complex systems

    NASA Astrophysics Data System (ADS)

    Thomas, David A.

    2010-08-01

    Root causes of mission critical failures and major cost and schedule overruns in complex systems and programs are studied through the post-mortem analyses compiled for several examples, including the Hubble Space Telescope, the Challenger and Columbia Shuttle accidents, and the Three Mile Island nuclear power plant accident. The roles of organizational complexity, cognitive biases in decision making, the display of quantitative data, and cost and schedule pressure are all considered. Recommendations for mitigating the risk of similar failures in future programs are also provided.

  17. Monocular Passive Ranging by an Optical System with Band Pass Filtering

    DTIC Science & Technology

    2010-03-01

    MONOCULAR PASSIVE RANGING BY AN OPTICAL SYSTEM WITH BAND PASS FILTERING THESIS Joel R...GAP/ENP/10-M01 MONOCULAR PASSIVE RANGING BY AN OPTICAL SYSTEM WITH BAND PASS FILTERING THESIS Presented to the Faculty Department of...March 2010 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GAP/ENP/10-M01 MONOCULAR PASSIVE RANGING BY AN OPTICAL SYSTEM WITH BAND

  18. Pyrotechnic system failures: Causes and prevention

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.

    1988-01-01

    Although pyrotechnics have successfully accomplished many critical mechanical spacecraft functions, such as ignition, severance, jettisoning and valving (excluding propulsion), failures continue to occur. Provided is a listing of 84 failures of pyrotechnic hardware with completed design over a 23-year period, compiled informally by experts from every NASA Center, as well as the Air Force Space Division and the Naval Surface Warfare Center. Analyses are presented as to when and where these failures occurred, their technical source or cause, followed by the reasons why and how these kinds of failures persist. The major contributor is a fundamental lack of understanding of the functional mechanisms of pyrotechnic devices and systems, followed by not recognizing pyrotechnics as an engineering technology, insufficient manpower with hands-on experience, too few test facilities, and inadequate guidelines and specifications for design, development, qualification and acceptance. Recommendations are made on both a managerial and technical basis to prevent failures, increase reliability, improve existing and future designs, and develop the technology to meet future requirements.

  19. A PROPOSED METHOD FOR ESTIMATING FAILURE RATES OF DEGRADED PASSIVE COMPONENTS IN THE NRC SIGNIFICANCE DETERMINATION PROCESS

    SciTech Connect

    Unwin, Stephen D.; Johnson, Kenneth I.; Ivans, William J.; Lowry, Peter P.

    2013-11-01

    This paper outlines a methodology for estimation of the incremental core damage frequency associated with the degradation of passive components with a view to its application in the US Nuclear Regulatory Commission's significance determination process. The method involves use of simplified physics-based models of materials degradation and the probabilistic comparison of transient loads with deteriorating system capacities.

  20. A passive gust alleviation system for a light aircraft

    NASA Technical Reports Server (NTRS)

    Roesch, P.; Harlan, R. B.

    1975-01-01

    A passive aeromechanical gust alleviation system was examined for application to a Cessna 172. The system employs small auxiliary wings to sense changes in angle of attack and to drive the wing flaps to compensate the resulting incremental lift. The flaps also can be spring loaded to neutralize the effects of variations in dynamic pressure. Conditions for gust alleviation are developed and shown to introduce marginal stability if both vertical and horizontal gusts are compensated. Satisfactory behavior is realized if only vertical gusts are absorbed; however, elevator control is effectively negated by the system. Techniques to couple the elevator and flaps are demonstrated to restore full controllability without sacrifice of gust alleviation.

  1. A passive gust alleviation system for light aircraft

    NASA Technical Reports Server (NTRS)

    Roesch, P.; Harlan, R. B.

    1974-01-01

    A passive aeromechanical gust alleviation system has been examined for application to a Cessna 172. The system employs small auxiliary wings to sense changes in angle of attack and to drive the wing flaps to compensate the resulting incremental lift. The flaps also can be spring loaded to neutralize the effects of variations in dynamic pressure. Conditions for gust alleviation are developed and shown to introduce marginal stability if both vertical and horizontal gusts are compensated. Satisfactory behavior is realized if only vertical gusts are absorbed; however, elevator control is effectively negated by the system. Techniques to couple the elevator and flaps are demonstrated to restore full controllability without sacrifice of gust alleviation.

  2. Evaluation of a passive stack radon mitigation system

    SciTech Connect

    Johns, M.R.; Hintenlang, D.E.

    1996-06-01

    A builder in the Gainesville area wants to incorporate passive radon mitigation in the houses he builds. He has designed and constructed three passive stack systems. This paper presents the performance evaluation of these systems in three houses. The systems consist of a horizontal and vertical component. The horizontal component consists of a 4 inch diameter perforated PVC pipe laid inside a bed of 3/4 inch limerock under the concrete slab. The vertical component is a PVC pipe connected into the horizontal pipe running inside an interior wall into the attic. Each house has a slightly different geometry for the horizontal component. In house number one, the rock bed runs across the length of the foundation and is open to the outdoor air on both ends. In house number two, the rock bed runs in a U-shape two-thirds the length of the foundation and has only one end open to the outdoor air. In house number three, the rock bed runs two-thirds the length of the foundation. The vertical stack is connected at one end and the other end is open to the outdoor air. The systems were evaluated under several configurations. Two of the configurations evaluated were all openings either open or closed. The initial data taken with the system in different configurations indicated the system had little impact on the indoor radon concentration. The average radon concentration remained approximately 4.7{+-}0.6 pCi L{sup -1}, even with all openings closed. The system was then modified to extend the stack pipe through the attic and out the roof. The average concentration dropped to 3.9{+-}0.5 pCi L{sup -1}. These passive systems do not significantly decrease the indoor radon concentration. However, in homes with moderate levels of radon, some reduction in radon concentration can be expected.

  3. A review of the methods for passive solar systems analysis

    NASA Astrophysics Data System (ADS)

    Allan, A. P.; Transmeir, G. D.

    1980-06-01

    Due to recent needs expressed by the Air Force, a review and evaluation of the methods of analysis for passive solar energy systems was conducted. The methods of analysis evaluated were those that could be worked without the use of computers or programmable calculators. A selection model was designed to systematically and objectively evaluate the methods. The selection model was a variation of a scoring model and based on six criteria. The criteria were: performance, economics, flexibility, implementation, usability, and computing devices. Of the methods evaluated, the Passive Solar Design Handbook was the recommended method of analysis to be used in the Air Force. The method was written by the Los Alamos Scientific Laboratory for the Department of Energy. This method was comprehensive yet simple to use and understand.

  4. Study of Natural Convection Passive Cooling System for Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Abdillah, Habibi; Saputra, Geby; Novitrian; Permana, Sidik

    2017-07-01

    Fukushima nuclear reactor accident occurred due to the reactor cooling pumps and followed by all emergencies cooling systems could not work. Therefore, the system which has a passive safety system that rely on natural laws such as natural convection passive cooling system. In natural convection, the cooling material can flow due to the different density of the material due to the temperature difference. To analyze such investigation, a simple apparatus was set up and explains the study of natural convection in a vertical closed-loop system. It was set up that, in the closed loop, there is a heater at the bottom which is representing heat source system from the reactor core and cooler at the top which is showing the cooling system performance in room temperature to make a temperature difference for convection process. The study aims to find some loop configurations and some natural convection performances that can produce an optimum flow of cooling process. The study was done and focused on experimental approach and simulation. The obtained results are showing and analyzing in temperature profile data and the speed of coolant flow at some point on the closed-loop system.

  5. Passive Wireless Hermetic Environment Monitoring System for Spray Painting Workshop

    PubMed Central

    Wang, Lifeng; Ma, Jingjing; Huang, Yan; Tang, Dan; Huang, Qing-An

    2016-01-01

    Passive wireless sensors have the advantages of operating without a power supply and remote sensing capability. Hence, they are very suitable for some harsh environments, such as hermetic environments, rotating parts, or very high temperature environments. The spray painting workshop is such a harsh environment, containing a large amount of flammable paint mist and organic gas. Aiming at this special environment of spray painting workshop, a passive wireless hermetic environment monitoring system was designed, fabricated, and demonstrated. The proposed system is composed of a transponder and a reader, and the circuit design of each part is given in detail in this paper. The power and the data transmission between the transponder and the reader are realized by the inductive coupling mechanism. Utilizing the back scatter modulation and channel multiplexing, the frequency signals generated by three different environmental sensors—together with their interfaces in the transponder—are wirelessly read out by the reader. Because of the harsh environment of the spray painting room, the package of the monitoring system is quite important. Three different kinds of filter films for the system package were compared. The experimental results show that the composite filter film aluminum anodic oxide/polytetrafluoroethylene (AAO/PTFE) has the best performance. After fabrication, the measured temperature, humidity, and pressure sensitivities were measured and found to be 180 Hz/°C in the range of 0~60 °C, 100 Hz/%RH in the range of 15~95 %RH, and 42 Hz/hPa in the range of 600~1100 hPa, respectively. Additionally, the remote sensing distance of the monitoring system reaches 4 cm. Finally, the passive wireless hermetic environment monitoring system was installed on the glass wall of the spray painting workshop and was successfully demonstrated. PMID:27490546

  6. Passive Wireless Hermetic Environment Monitoring System for Spray Painting Workshop.

    PubMed

    Wang, Lifeng; Ma, Jingjing; Huang, Yan; Tang, Dan; Huang, Qing-An

    2016-08-01

    Passive wireless sensors have the advantages of operating without a power supply and remote sensing capability. Hence, they are very suitable for some harsh environments, such as hermetic environments, rotating parts, or very high temperature environments. The spray painting workshop is such a harsh environment, containing a large amount of flammable paint mist and organic gas. Aiming at this special environment of spray painting workshop, a passive wireless hermetic environment monitoring system was designed, fabricated, and demonstrated. The proposed system is composed of a transponder and a reader, and the circuit design of each part is given in detail in this paper. The power and the data transmission between the transponder and the reader are realized by the inductive coupling mechanism. Utilizing the back scatter modulation and channel multiplexing, the frequency signals generated by three different environmental sensors-together with their interfaces in the transponder-are wirelessly read out by the reader. Because of the harsh environment of the spray painting room, the package of the monitoring system is quite important. Three different kinds of filter films for the system package were compared. The experimental results show that the composite filter film aluminum anodic oxide/polytetrafluoroethylene (AAO/PTFE) has the best performance. After fabrication, the measured temperature, humidity, and pressure sensitivities were measured and found to be 180 Hz/°C in the range of 0~60 °C, 100 Hz/%RH in the range of 15~95 %RH, and 42 Hz/hPa in the range of 600~1100 hPa, respectively. Additionally, the remote sensing distance of the monitoring system reaches 4 cm. Finally, the passive wireless hermetic environment monitoring system was installed on the glass wall of the spray painting workshop and was successfully demonstrated.

  7. Passive Magnetic Attitude Control System for the Munin Nanosatellite

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, M. Yu.; Penkov, V. I.

    2002-03-01

    The instrumental and applied problems related to the design of a passive magnetic attitude control system for the Munin nanosatellite are considered. The system is constructed from a strong permanent magnet and a set of hysteresis rods. These rods are made of magnetically soft material using a special technology, and they allow us to support the satellite orientation with respect to the local magnetic field vector with a given accuracy and time response. By using asymptotic and numerical methods, we investigate the satellite dynamics for different models of hysteresis. The issues concerning the arrangement of the rods and their interaction with the fields of permanent magnets mounted onboard the satellite are discussed.

  8. Evaluation of the NucleDyne Passive Containment System

    SciTech Connect

    Leininger, W. J.; Coleman, J. H.; Merrell, W. W.

    1981-04-01

    This reports contains: (1) an evaluation by Gilbert/Commonwealth (G/C) of the NucleDyne passive Containment System (PCS) as that conceptual design is applied to a Westinghouse, two loop, Pressurized Water Reactor; (2) an evaluation by Westinghouse of two questions about the impact of the PCS on the Nuclear Steam Supply System (NSSS), which were posed by G/C and best answered by an NSSS vendor; and (3) replies to both the Gilbert/Commonwealth report and the Westinghoue report by NucleDyne Engineering Corporation.

  9. CMR Shuffler System: Passive Mode Calibration and Certification Report

    SciTech Connect

    Frame, Katherine C.; Gomez, Cipriano D.; Salazar, William R.; Mayo, Douglas R.; Vigil, Georgiana M.; Crooks, William J.; Stange, Sy

    2012-07-20

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. As debris is removed from the vessels, material will be placed in waste drums. Far-field gamma ray assay will be used to determine when a drum is nearing a {sup 239}Pu equivalent mass of less than 200 g. The drum will then be assayed using a waste drum shuffler operated in passive mode using a neutron coincidence counting method for accountability. This report focuses on the testing and calibration of the CMR waste drum shuffler in passive mode operation. Initial testing was performed to confirm previously accepted measurement parameters. The system was then calibrated using a set of weapons grade Pu (WGPu, {sup 239}Pu > 93%) oxide standards placed inside a 55 gallon drum. The calibration data ranges from Pu mass of 0.5 g to 188.9 g. The CMR waste drum shuffler has been tested and calibrated in passive mode in preparation for safeguards accountability measurements of waste drums containing material removed from CVs for the CVD project.

  10. The East Pacific Rise: An Active Not Passive Spreading System

    NASA Astrophysics Data System (ADS)

    Rowley, D. B.; Rowan, C. J.; Forte, A. M.; Moucha, R.; Grand, S. P.; Simmons, N. A.

    2011-12-01

    Traditional plate tectonic interpretations of mid-oceanic ridges regard spreading as an entirely passive phenomenon. From this one would assume that the oceanic ridges will move over the mantle in response to the geodynamics of the diverging plates, and do not remain fixed spatially over any protracted period of time. An analysis of the kinematics of ridge motions in the Indo-Atlantic hotspot frame of reference since 83 Ma generally supports this view, with the notable exception of the East Pacific Rise (EPR). The Pacific-Nazca/Farallon segment of the EPR north of Easter Island (27°S) is oriented essentially N-S, and has produced more than 9500km of E-W spreading in the past 80 Ma, making it the dominant ridge in the world's plate system over this interval of time. Yet despite the large amount of E-W divergence, the spreading center has maintained its longitudinal position to within <±250 km of the current ridge axis. Global mantle convective flow modeling indicates that the EPR, unlike any other extensive segment of the mid-oceanic ridge system, is underlain by an active upwelling system extending from the core-mantle boundary to the surface. We suggest that the lack of E-W motion of the EPR apparent from the kinematics is a consequence of these mantle dynamics; this ridge is thus not behaving as a passive plate boundary, but is actively and directly linked to, and controlled by, whole mantle upwelling. This observation overturns the notion that ridges are always entirely passive features of the plate system. Subduction of the northern EPR beneath western North America has thus resulted in the overriding of an active upwelling system that has contributed significantly to the evolution of Basin and Range kinematics and superimposed dynamics, including significant contributions from dynamic topography.

  11. Precision analysis of passive BD aided pseudolites positioning system

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoming; Zhao, Yan

    2007-11-01

    In recent years BD (BeiDou positioning system), an active satellite navigation system, has been widely applied in geodetic survey, precise engineering survey and GNC (guide, navigation and control system) of weapons because of its reliability and availability. However, it has several problems on the accuracy, anti-interference and active-positioning. A passive BD aided pseudolites positioning system is introduced in details in this paper. The configuration and the operating principle of system are presented. In analyzing the precision of location, one of the crucial aspects to be studied is how to determine the arrangement of the pseudolites to get the good GDOP, which is discussed in the different arrangements of the pseudolites in this paper. The simulation results show that the VDOP (vertical dilution of precision) of BD is improved due to introducing the pseudolites. The experiments indicate the validity of the methods and the improvement of the positioning precision in the BD aided pseudolite system.

  12. Anti-collision radio-frequency identification system using passive SAW tags

    NASA Astrophysics Data System (ADS)

    Sorokin, A. V.; Shepeta, A. P.

    2017-06-01

    Modern multi sensor systems should have high operating speed and resistance to climate impacts. Radiofrequency systems use passive SAW tags for identification items and vehicles. These tags find application in industry, traffic remote control systems, and railway remote traffic control systems for identification and speed measuring. However, collision of the passive SAW RFID tags hinders development passive RFID SAW technology in Industry. The collision problem for passive SAW tags leads for incorrect identification and encoding each tag. In our researching, we suggest approach for identification of several passive SAW tags in collision case.

  13. Failure mechanisms of thermal barrier systems

    NASA Astrophysics Data System (ADS)

    Xu, Tao

    Thermal barrier coatings (TBCs) are widely used in turbines for propulsion and power generation. The benefit results from their ability to sustain high thermal gradients in the presence of adequate backside cooling. Lowering the temperature of the metal substrate prolongs the life of the component: whether from environmental attack, creep rupture, or fatigue. Thermal barrier systems exhibit multiple failure mechanisms, depends on the deposition methods of the TBCs, chemical composition of the bond coats, and their working environments. Some of the most prevalent are studied in this thesis. There are two types of thermal barrier systems based on the chemical composition of the bond coats: Pt-aluminide and NiCoCrAlY bond coats. Ratcheting happens the most in the systems with Pt-aluminide bond coats; while edge delamination is considered a possible failure mechanism for the systems with NiCoCrAlY bond coats. Ratcheting is motivated by displacement instability in the thermally grown oxide (TGO). Interactions between cracks induced in TBCs upon thermal cycling have been calculated. Cracks that converge from neighboring imperfections exhibit a minimum energy release rate prior to coalescence. Equating this minimum to the toughness of the TBC provides a criterion for coalescence and failure. Imposing this criterion allows the change in crack length upon cycling and the number of cycles to failure to be ascertained. This simulation capability is used to explore various influences on durability. Samples with NiCoCrAlY bond coat are studied after subjected to thermal cycling in a burner rig. In each case, a dominant delamination has been identified, that extends primarily along the interface between the TGO and the bond coat. Calculations of the delamination energy release rate, upon comparison with the interface toughness, reveals a critical TGO thickness, (h tgo)c ≈ 3mum, comparable to that found experimentally.

  14. A novel readout system for wireless passive pressure sensors

    NASA Astrophysics Data System (ADS)

    Zhang, Huixin; Hong, Yingping; Ge, Binger; Liang, Ting; Xiong, Jijun

    2014-03-01

    This paper presents a novel readout system for wireless passive pressure sensors based on the inductively coupled inductor and cavity (LC) resonant circuits. The proposed system consists of a reader antenna inductively coupled to the sensor circuit, a readout circuit, and a personal computer (PC) post processing unit. The readout circuit generates a voltage signal representing the sensor's capacitance. The frequency of the reader antenna driving signal is a constant, which is equal to the sensor's resonant frequency at zero pressure. Based on mechanical and electrical modeling, the pressure sensor design based on the high temperature co-fired ceramic (HTCC) technology is conducted and discussed. The functionality and accuracy of the readout system are tested with a voltage-capacitance measurement system and demonstrated in a realistic pressure measurement environment, so that the overall performance and the feasibility of the readout system are proved.

  15. Electrostatic stabilizer for a passive magnetic bearing system

    DOEpatents

    Post, Richard F

    2016-10-11

    Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

  16. Electrostatic stabilizer for a passive magnetic bearing system

    SciTech Connect

    Post, Richard F.

    2015-11-24

    Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

  17. Virtual Passive Controller for Robot Systems Using Joint Torque Sensors

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.; Juang, Jer-Nan

    1997-01-01

    This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented on several joints of a laboratory robot. The controller showed good stability robustness to system parameter error and to the exclusion of nonlinear dynamic effects on the joints. The controller enhanced position tracking performance and, in the absence of position control, dissipated joint energy.

  18. Highly sensitive passive radio frequency identification based sensor systems.

    PubMed

    Wissenwasser, J; Vellekoop, M; Heer, R

    2010-02-01

    A novel platform for sensor applications based on radio frequency (rf) identification technology, where passive tags are powered by the rf-field of a reader, is presented. The sophisticated energy harvesting system of the tag enables a blanking of the rf-field for a defined period, while supplying the tag electronics with a highly stable voltage and a power of 25 mW for 100 ms. During this time, span measurements can be performed without interferences of the rf-field. The presented tags work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions as well as in harsh environments.

  19. Highly sensitive passive radio frequency identification based sensor systems

    NASA Astrophysics Data System (ADS)

    Wissenwasser, J.; Vellekoop, M.; Heer, R.

    2010-02-01

    A novel platform for sensor applications based on radio frequency (rf) identification technology, where passive tags are powered by the rf-field of a reader, is presented. The sophisticated energy harvesting system of the tag enables a blanking of the rf-field for a defined period, while supplying the tag electronics with a highly stable voltage and a power of 25 mW for 100 ms. During this time, span measurements can be performed without interferences of the rf-field. The presented tags work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions as well as in harsh environments.

  20. Solar passive ceiling system. Final report. [Passive solar heating system with venetian blind reflectors and latent heat storage in ceiling

    SciTech Connect

    Schneider, A.R.

    1980-01-01

    The construction of a 1200 square foot building, with full basement, built to be used as a branch library in a rural area is described. The primary heating source is a passive solar system consisting of a south facing window system. The system consists of: a set of windows located in the south facing wall only, composed of double glazed units; a set of reflectors mounted in each window which reflects sunlight up to the ceiling (the reflectors are similar to venetian blinds); a storage area in the ceiling which absorbs the heat from the reflected sunlight and stores it in foil salt pouches laid in the ceiling; and an automated curtain which automatically covers and uncovers the south facing window system. The system is totally passive and uses no blowers, pumps or other active types of heat distribution equipment. The building contains a basement which is normally not heated, and the north facing wall is bermed four feet high around the north side.

  1. Design and performance verification of a passive propellant management system

    NASA Technical Reports Server (NTRS)

    Hess, D. A.; Regnier, W. W.

    1978-01-01

    This paper describes the design and verification testing of a reusable passive propellant management system. The system was designed to acquire propellant in low- or zero-g environments and also retain this propellant under high axially directed accelerations that may be experienced during launch and orbit-to-orbit transfer. The system design requirements were established to satisfy generally the requirements for a large number of potential NASA and military applications, such as orbit-to-orbit shuttles and satellite vehicles. The resulting concept was a multicompartmented tank with independent surface tension acquisition channels in each compartment. The tank was designed to provide a minimum expulsion efficiency of 98 percent when subjected to the simultaneous conditions of acceleration, vibration, and outflow. The system design has the unique capability to demonstrate low-g performance in a 1-g test environment, and the test program summarized was structured around this capability.

  2. Passive vs. Parachute System Architecture for Robotic Sample Return Vehicles

    NASA Technical Reports Server (NTRS)

    Maddock, Robert W.; Henning, Allen B.; Samareh, Jamshid A.

    2016-01-01

    The Multi-Mission Earth Entry Vehicle (MMEEV) is a flexible vehicle concept based on the Mars Sample Return (MSR) EEV design which can be used in the preliminary sample return mission study phase to parametrically investigate any trade space of interest to determine the best entry vehicle design approach for that particular mission concept. In addition to the trade space dimensions often considered (e.g. entry conditions, payload size and mass, vehicle size, etc.), the MMEEV trade space considers whether it might be more beneficial for the vehicle to utilize a parachute system during descent/landing or to be fully passive (i.e. not use a parachute). In order to evaluate this trade space dimension, a simplified parachute system model has been developed based on inputs such as vehicle size/mass, payload size/mass and landing requirements. This model works in conjunction with analytical approximations of a mission trade space dataset provided by the MMEEV System Analysis for Planetary EDL (M-SAPE) tool to help quantify the differences between an active (with parachute) and a passive (no parachute) vehicle concept.

  3. Mathematics of Failures in Complex Systems: Characterization and Mitigation of Service Failures in Complex Dynamic Systems

    DTIC Science & Technology

    2007-06-30

    equivalently , the 3nite-state machine Fig. 2 can be started from any arbitrary state corresponding to no speci3c initial condition.) While the time...University Research Initiative (MURI) Project Characterization and Mitigation of Failures in Complex Dynamical Systems Principal Investigator: Professor...Failure (CSF) Multidisciplinary University Research Initiative (MURI) project has been to formulate and disseminate a knowledge base of science and

  4. Operation of passive membrane systems for drinking water treatment.

    PubMed

    Oka, P A; Khadem, N; Bérubé, P R

    2017-05-15

    The widespread adoption of submerged hollow fibre ultrafiltration (UF) for drinking water treatment is currently hindered by the complexity and cost of these membrane systems, especially in small/remote communities. Most of the complexity is associated with auxiliary fouling control measures, which include backwashing, air sparging and chemical cleaning. Recent studies have demonstrated that sustained operation without fouling control measures is possible, but little is known regarding the conditions under which extended operation can be sustained with minimal to no fouling control measures. The present study investigated the contribution of different auxiliary fouling control measures to the permeability that can be sustained, with the intent of minimizing the mechanical and operational complexity of submerged hollow fiber UF membrane systems while maximizing their throughput capacity. Sustained conditions could be achieved without backwashing, air sparging or chemical cleaning (i.e. passive operation), indicating that these fouling control measures can be eliminated, substantially simplifying the mechanical and operational complexity of submerged hollow fiber UF systems. The adoption of hydrostatic pressure (i.e. gravity) to provide the driving force for permeation further reduced the system complexity. Approximately 50% of the organic material in the raw water was removed during treatment. The sustained passive operation and effective removal of organic material was likely due to the microbial community that established itself on the membrane surface. The permeability that could be sustained was however only approximately 20% of that which can be maintained with fouling control measures. Retaining a small amount of air sparging (i.e. a few minutes daily) and incorporating a daily 1-h relaxation (i.e. permeate flux interruption) period prior to sparging more than doubled the permeability that could be sustained. Neither the approach used to interrupt the permeate

  5. Rate of change in cerebral oxygenation and blood pressure in response to passive changes in posture: a comparison between pure autonomic failure patients and controls.

    PubMed

    Tachtsidis, Ilias; Elwell, Clare E; Leung, Terence S; Bleasdale-Barr, Katharine; Hunt, Katharine; Toms, Nathan; Smith, Martin; Mathias, Christopher J; Delpy, David T

    2005-01-01

    The cardiovascular and cerebrovascular responses to head-up postural change are compromised in pure autonomic failure (PAF) patients because of sympathetic denervation. The aim of this study was to characterize the rate of change of systemic mean blood pressure (MBP) and cerebral haemodynamics in response to passive posture changes. Nine PAF patients and 9 age-matched controls took part in this study. MBP and oxy- (O2Hb), deoxy-haemoglobin (HHb), and tissue oxygenation index (TOI) on the forehead were continuously monitored non-invasively using the Portapres and near-infrared spectroscopy (NIRS), respectively. From visual inspection of the haemoglobin difference signal (Hb(diff) = O2Hb-HHb), seven distinct phases were marked (1: supine, 2: start passive tilt, 3: head up to 60 degrees degrees, 4: end of tilt, 5: tilt reversal, 6: return to supine, 7: rest); the same time points were used for all of the other signals. For each phase, the slope was calculated using a linear regression algorithm. Significant differences were found between PAF patients and controls in the Hb(diff) slope magnitudes for phases 3 (P < .05) and 5 (P = .01), and the duration of phase 2 (P < .05). MBP slope magnitudes showed significant differences for phases 2 (P < .01) and 5 (P < .01). These differences in the rate of change suggest differences in blood vessel resistance related to sympathetic activation.

  6. Integrated Circuit Failure Analysis Hypertext Help System

    SciTech Connect

    Henderson, Christopher L.; Barton, Daniel L.; Campbell, Ann N.; Cole, Edward I; Mikawa, Russell E.; Peterson, Kenneth A.; Rife, James L.; Soden, Jerry M.

    1995-02-23

    This software assists a failure analyst performing failure analysis on integrated circuits. The software can also be used to train inexperienced failure analysts. The software also provides a method for storing information and making it easily available to experienced failure analysts.

  7. LDEF electronic systems: Successes, failures, and lessons

    NASA Technical Reports Server (NTRS)

    Miller, Emmett; Porter, Dave; Smith, Dave; Brooks, Larry; Levorsen, Joe; Mulkey, Owen

    1991-01-01

    Following the Long Duration Exposure Facility (LDEF) retrieval, the Systems Special Investigation Group (SIG) participated in an extensive series of tests of various electronic systems, including the NASA provided data and initiate systems, and some experiment systems. Overall, these were found to have performed remarkably well, even though most were designed and tested under limited budgets and used at least some nonspace qualified components. However, several anomalies were observed, including a few which resulted in some loss of data. The postflight test program objectives, observations, and lessons learned from these examinations are discussed. All analyses are not yet complete, but observations to date will be summarized, including the Boeing experiment component studies and failure analysis results related to the Interstellar Gas Experiment. Based upon these observations, suggestions for avoiding similar problems on future programs are presented.

  8. Passive cooling system for liquid metal cooled nuclear reactors with backup coolant flow path

    DOEpatents

    Hunsbedt, Anstein; Boardman, Charles E.

    1993-01-01

    A liquid metal cooled nuclear fission reactor plant having a passive auxiliary safety cooling system for removing residual heat resulting from fuel decay during reactor shutdown, or heat produced during a mishap. This reactor plant is enhanced by a backup or secondary passive safety cooling system which augments the primary passive auxiliary cooling system when in operation, and replaces the primary system when rendered inoperable.

  9. Passive cooling system for top entry liquid metal cooled nuclear reactors

    DOEpatents

    Boardman, Charles E.; Hunsbedt, Anstein; Hui, Marvin M.

    1992-01-01

    A liquid metal cooled nuclear fission reactor plant having a top entry loop joined satellite assembly with a passive auxiliary safety cooling system for removing residual heat resulting from fuel decay during shutdown, or heat produced during a mishap. This satellite type reactor plant is enhanced by a backup or secondary passive safety cooling system which augments the primary passive auxiliary cooling system when in operation, and replaces the primary cooling system when rendered inoperative.

  10. Adaptive-passive vibration control systems for industrial applications

    NASA Astrophysics Data System (ADS)

    Mayer, D.; Pfeiffer, T.; Vrbata, J.; Melz, T.

    2015-04-01

    Tuned vibration absorbers have become common for passive vibration reduction in many industrial applications. Lightly damped absorbers (also called neutralizers) can be used to suppress narrowband disturbances by tuning them to the excitation frequency. If the resonance is adapted in-operation, the performance of those devices can be significantly enhanced, or inertial mass can be decreased. However, the integration of actuators, sensors and control electronics into the system raises new design challenges. In this work, the development of adaptive-passive systems for vibration reduction at an industrial scale is presented. As an example, vibration reduction of a ship engine was studied in a full scale test. Simulations were used to study the feasibility and evaluate the system concept at an early stage. Several ways to adjust the resonance of the neutralizer were evaluated, including piezoelectric actuation and common mechatronic drives. Prototypes were implemented and tested. Since vibration absorbers suffer from high dynamic loads, reliability tests were used to assess the long-term behavior under operational conditions and to improve the components. It was proved that the adaptive systems are capable to withstand the mechanical loads in an industrial application. Also a control strategy had to be implemented in order to track the excitation frequency. The most mature concepts were integrated into the full scale test. An imbalance exciter was used to simulate the engine vibrations at a realistic level experimentally. The neutralizers were tested at varying excitation frequencies to evaluate the tracking capabilities of the control system. It was proved that a significant vibration reduction is possible.

  11. Stability Issues in Ambient-Temperature Passive Magnetic Bearing Systems

    SciTech Connect

    Post, R.F.

    2000-02-17

    The ambient-temperature passive magnetic bearing system developed at the Lawrence Livermore National Laboratory achieves rotor-dynamic stability by employing special combinations of levitating and stabilizing elements. These elements, energized by permanent magnet material, create the magnetic and electrodynamic forces that are required for the stable levitation of rotating systems, such as energy-storage flywheels. Stability criteria, derived from theory, describe the bearing element parameters, i.e., stiffnesses and damping coefficients, that are required both to assure stable levitation (''Earnshaw-stability''), and stability against whirl-type rotor-dynamic instabilities. The work described in this report concerns experimental measurements and computer simulations that address some critical aspects of this overall stability problem. Experimentally, a test device was built to measure the damping coefficient of dampers that employ eddy currents induced in a metallic disc. Another test device was constructed for the purpose of measuring the displacement-dependent drag coefficient of annular permanent magnet bearing elements. In the theoretical developments a computer code was written for the purpose of simulating the rotor-dynamics of our passive bearing systems. This code is capable of investigating rotor-dynamic stability effects for both small-amplitude transient displacements (i.e., those within the linear regime), and for large-amplitude displacements, where non-linear effects can become dominant. Under the latter conditions a bearing system that is stable for small-amplitude displacements may undergo a rapidly growing rotor-dynamic instability once a critical displacement is exceeded. A new result of the study was to demonstrate that stiffness anisotropy of the bearing elements (which can be designed into our bearing system) is strongly stabilizing, not only in the linear regime, but also in the non-linear regime.

  12. Passive modular gas safety system for a reactor

    SciTech Connect

    Abalin, S.S.; Isaev, I.F.; Kulakov, A.A.; Sivokon, V.P.; Udovenko, A.N.; Ionaitis, R.R.

    1994-01-01

    Reactor safety systems have developed gradually. Today in particular, auxiliary systems are being developed which are based on nontraditional operational concepts, by using gaseous neutron absorbers. The Scientific-Research and Design Institute of Power Technology (NIKIET) and the Institute of Nuclear Reactors, Kurchatov Institute Reactor Science Center (RNTs), have done preliminary development and experimental verification of separate elements of this system, in which helium is used as the absorber. This article presents a rapid passive safety system based on gaseous absorber, which is made as autonomous modules as the final stage of reactor safety. Its effectiveness is discussed by using an RBMK reactor as an example. As opposed to traditional active, systems, it does not require a functioning power supply and information signals from outside the reactors system, which makes it stable against unsanctioned actions by personnel, the influence of other systems, and also outside actions (sabotage and natural calamities which could destroy the the nuclear power plant structure). Because the gas safety system can operate instantaneously (0.1-0.3 sec), in principle, it can shut down the reactor even with fast-neutron runaway, where traditional safety systems are ineffective.

  13. Progress in passive solar energy systems. Volume 8. Part 1

    SciTech Connect

    Hayes, J.; Andrejko, D.A.

    1983-01-01

    This book presents the papers given at a conference sponsored by the US DOE, the Solar Energy Research Institute, SolarVision, Inc., and the Southern California Solar Energy Society. The topics considered at the conference included sizing solar energy systems for agricultural applications, a farm scale ethanol production plant, the EEC wind energy RandD program, the passive solar performance assessment of an earth-sheltered house, the ARCO 1 MW photovoltaic power plant, the performance of a dendritic web photovoltaic module, second generation point focused concentrators, linear fresnel lens concentrating photovoltaic collectors, photovoltaic conversion efficiency, amorphous silicon thin film solar cells, a photovoltaic system for a shopping center, photovoltaic power generation for the utility industry, spectral solar radiation, and the analysis of insolation data.

  14. Micro and nano devices in passive millimetre wave imaging systems

    NASA Astrophysics Data System (ADS)

    Appleby, R.

    2013-06-01

    The impact of micro and nano technology on millimetre wave imaging from the post war years to the present day is reviewed. In the 1950s whisker contacted diodes in mixers and vacuum tubes were used to realise both radiometers and radars but required considerable skill to realise the performance needed. Development of planar semiconductor devices such as Gunn and Schottky diodes revolutionised mixer performance and provided considerable improvement. The next major breakthrough was high frequency transistors based on gallium arsenide which were initially used at intermediate frequencies but later after further development at millimeter wave frequencies. More recently Monolithic Microwave Integrated circuits(MMICs) offer exceptional performance and the opportunity for innovative design in passive imaging systems. In the future the use of micro and nano technology will continue to drive system performance and we can expect to see integration of antennae, millimetre wave and sub millimetre wave circuits and signal processing.

  15. Active subjects of passive monitoring: responses to a passive monitoring system in low-income independent living

    PubMed Central

    BERRIDGE, CLARA

    2016-01-01

    Passive monitoring technology is beginning to be reimbursed by third-party payers in the United States of America. Given the low voluntary uptake of these technologies on the market, it is important to understand the concerns and perspectives of users, former users and non-users. In this paper, the range of ways older adults relate to passive monitoring in low-income independent-living residences is presented. This includes experiences of adoption, non-adoption, discontinuation and creative ‘misuse’. The analysis of interviews reveals three key insights. First, assumptions built into the technology about how older adults live present a problem for many users who experience unwanted disruptions and threats to their behavioural autonomy. Second, resident response is varied and challenges the dominant image of residents as passive subjects of a passive monitoring system. Third, the priorities of older adults (e.g. safety, autonomy, privacy, control, contact) are more diverse and multi-faceted than those of the housing organisation staff and family members (e.g. safety, efficiency) who drive the passive monitoring intervention. The tension between needs, desires and the daily lives of older adults and the technological solutions offered to them is made visible by their active responses, including resistance to them. This exposes the active and meaningful qualities of older adults’ decisions and practices. PMID:28239211

  16. Active subjects of passive monitoring: responses to a passive monitoring system in low-income independent living.

    PubMed

    Berridge, Clara

    2017-03-01

    Passive monitoring technology is beginning to be reimbursed by third-party payers in the United States of America. Given the low voluntary uptake of these technologies on the market, it is important to understand the concerns and perspectives of users, former users and non-users. In this paper, the range of ways older adults relate to passive monitoring in low-income independent-living residences is presented. This includes experiences of adoption, non-adoption, discontinuation and creative 'misuse'. The analysis of interviews reveals three key insights. First, assumptions built into the technology about how older adults live present a problem for many users who experience unwanted disruptions and threats to their behavioural autonomy. Second, resident response is varied and challenges the dominant image of residents as passive subjects of a passive monitoring system. Third, the priorities of older adults (e.g. safety, autonomy, privacy, control, contact) are more diverse and multi-faceted than those of the housing organisation staff and family members (e.g. safety, efficiency) who drive the passive monitoring intervention. The tension between needs, desires and the daily lives of older adults and the technological solutions offered to them is made visible by their active responses, including resistance to them. This exposes the active and meaningful qualities of older adults' decisions and practices.

  17. 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.

  18. International Space Station Passive Thermal Control System Analysis, Top Ten Lessons-Learned

    NASA Technical Reports Server (NTRS)

    Iovine, John

    2011-01-01

    The International Space Station (ISS) has been on-orbit for over 10 years, and there have been numerous technical challenges along the way from design to assembly to on-orbit anomalies and repairs. The Passive Thermal Control System (PTCS) management team has been a key player in successfully dealing with these challenges. The PTCS team performs thermal analysis in support of design and verification, launch and assembly constraints, integration, sustaining engineering, failure response, and model validation. This analysis is a significant body of work and provides a unique opportunity to compile a wealth of real world engineering and analysis knowledge and the corresponding lessons-learned. The analysis lessons encompass the full life cycle of flight hardware from design to on-orbit performance and sustaining engineering. These lessons can provide significant insight for new projects and programs. Key areas to be presented include thermal model fidelity, verification methods, analysis uncertainty, and operations support.

  19. Passive 350 GHz Video Imaging Systems for Security Applications

    NASA Astrophysics Data System (ADS)

    Heinz, E.; May, T.; Born, D.; Zieger, G.; Anders, S.; Zakosarenko, V.; Meyer, H.-G.; Schäffel, C.

    2015-10-01

    Passive submillimeter-wave imaging is a concept that has been in the focus of interest as a promising technology for personal security screening for a number of years. In contradiction to established portal-based millimeter-wave scanning techniques, it allows for scanning people from a distance in real time with high throughput and without a distinct inspection procedure. This opens up new possibilities for scanning, which directly address an urgent security need of modern societies: protecting crowds and critical infrastructure from the growing threat of individual terror attacks. Considering the low radiometric contrast of indoor scenes in the submillimeter range, this objective calls for an extremely high detector sensitivity that can only be achieved using cooled detectors. Our approach to this task is a series of passive standoff video cameras for the 350 GHz band that represent an evolving concept and a continuous development since 2007. Arrays of superconducting transition-edge sensors (TES), operated at temperatures below 1 K, are used as radiation detectors. By this means, background limited performance (BLIP) mode is achieved, providing the maximum possible signal to noise ratio. At video rates, this leads to a temperature resolution well below 1 K. The imaging system is completed by reflector optics based on free-form mirrors. For object distances of 5-25 m, a field of view up to 2 m height and a diffraction-limited spatial resolution in the order of 1-2 cm is provided. Opto-mechanical scanning systems are part of the optical setup and capable of frame rates of up to 25 frames per second.

  20. Comparison of three immunoglobulin G assays for the diagnosis of failure of passive transfer of immunity in neonatal alpacas.

    PubMed

    Pinn, Toby L; Gagliardo, Lucille F; Purdy, Steve R; Appleton, Judith A; Stokol, Tracy

    2013-01-01

    Measurement of serum immunoglobulin G (IgG) is used for the assessment of passive transfer of immunity in neonatal crias, with an IgG concentration <10 g/l being suggestive of failure of passive transfer (FPT). The purpose of the current study was to determine whether 3 commercially available immunologic assays yielded comparable results for IgG in alpacas. Serum samples from 91 alpacas were used and were stored frozen until batch analysis on the same day with the 3 assays. Immunoglobulin G was measured by radial immunodiffusion (RID) and 2 immunoturbidimetric (IT) assays (IT1, configured for automated chemistry analyzers; IT2, a point-of-care test). Median IgG concentrations were significantly different between the 3 assays, with the RID (median: 15 g/l) and IT1 (median: 16 g/l) assays, which used the same standard, yielding significantly higher IgG values than IT2 (median: 11 g/l). Results indicated a diagnostic discordance in 1-17% of samples at an IgG threshold of 10 g/l. Protein electrophoresis revealed that the RID and IT1 standard contained mostly albumin (>60%), whereas the IT2 standard consisted of beta and gamma globulins. The discrepant results between assays IT1 and IT2 were eliminated when the same standard was used (IT1: median 11 g/l; IT2: 10 g/l; n = 19 and 17, respectively). The IT1 assay had the highest precision, while the RID assay had the lowest. The results indicate that camelid IgG measurement is highly dependent on the assay standard and is not directly comparable between assays, potentially resulting in underdiagnosis of FPT in some crias.

  1. Development of 'no-reflow' phenomenon in ischemia/reperfusion injury: failure of active vasomotility and not simply passive vasoconstriction.

    PubMed

    Nanobashvili, J; Neumayer, C; Fuegl, A; Blumer, R; Prager, M; Sporn, E; Polterauer, P; Malinski, T; Huk, I

    2003-01-01

    Local blood flow failure (no-reflow phenomenon) during ischemia/reperfusion (I/R) injury may be mediated by interstitial edema formation (passive vasoconstriction) and/or microvascular spasm (active vasoconstriction). The development of the no-reflow phenomenon in the rabbit hind limb I/R model and the influence of treatment with L-arginine and/or antioxidative vitamins were investigated. Untreated rabbits were compared with those treated with L-arginine (4 mg/kg/min) or antioxidative vitamins (0.4 ml/kg) alone or in combination during hind limb I/R (2.5/2 h). Interstitial edema formation and microvessel diameter alterations were measured morphometrically. Capillary blood perfusion was measured continuously with laser Doppler flowmetry. I/R injury was expressed by interstitial edema formation (interstitial space increase by 80%), microvascular constriction (microvessel cross-sectional area decrease by 30%), and development of no-reflow phenomenon (blood flow reduction by 60%). Treatment with antioxidative vitamins alone or L-arginine alone reduced interstitial edema by 22 and 31%, consequently, while combined L-arginine/antioxidative vitamin treatment showed a more pronounced edema reduction by 40%. Treatment with only antioxidative vitamins failed to influence the development of no-reflow, although interstitial edema formation was reduced. L-Arginine treatment alone or in combination with antioxidative vitamins prevented microvascular constriction and preserved blood flow after reperfusion without development of no-reflow despite still apparent interstitial edema. Affections of active vasomotility and not merely passive changes of external pressure (i.e., interstitial edema formation) should be considered important in the development of microvascular constriction during 'no-reflow' phenomenon. Copyright 2003 S. Karger AG, Basel

  2. Reliability Analysis of Systems Subject to First-Passage Failure

    NASA Technical Reports Server (NTRS)

    Lutes, Loren D.; Sarkani, Shahram

    2009-01-01

    An obvious goal of reliability analysis is the avoidance of system failure. However, it is generally recognized that it is often not feasible to design a practical or useful system for which failure is impossible. Thus it is necessary to use techniques that estimate the likelihood of failure based on modeling the uncertainty about such items as the demands on and capacities of various elements in the system. This usually involves the use of probability theory, and a design is considered acceptable if it has a sufficiently small probability of failure. This report contains findings of analyses of systems subject to first-passage failure.

  3. System for Anomaly and Failure Detection (SAFD) system development

    NASA Technical Reports Server (NTRS)

    Oreilly, D.

    1992-01-01

    This task specified developing the hardware and software necessary to implement the System for Anomaly and Failure Detection (SAFD) algorithm, developed under Technology Test Bed (TTB) Task 21, on the TTB engine stand. This effort involved building two units; one unit to be installed in the Block II Space Shuttle Main Engine (SSME) Hardware Simulation Lab (HSL) at Marshall Space Flight Center (MSFC), and one unit to be installed at the TTB engine stand. Rocketdyne personnel from the HSL performed the task. The SAFD algorithm was developed as an improvement over the current redline system used in the Space Shuttle Main Engine Controller (SSMEC). Simulation tests and execution against previous hot fire tests demonstrated that the SAFD algorithm can detect engine failure as much as tens of seconds before the redline system recognized the failure. Although the current algorithm only operates during steady state conditions (engine not throttling), work is underway to expand the algorithm to work during transient condition.

  4. System for Anomaly and Failure Detection (SAFD) system development

    NASA Astrophysics Data System (ADS)

    Oreilly, D.

    1992-07-01

    This task specified developing the hardware and software necessary to implement the System for Anomaly and Failure Detection (SAFD) algorithm, developed under Technology Test Bed (TTB) Task 21, on the TTB engine stand. This effort involved building two units; one unit to be installed in the Block II Space Shuttle Main Engine (SSME) Hardware Simulation Lab (HSL) at Marshall Space Flight Center (MSFC), and one unit to be installed at the TTB engine stand. Rocketdyne personnel from the HSL performed the task. The SAFD algorithm was developed as an improvement over the current redline system used in the Space Shuttle Main Engine Controller (SSMEC). Simulation tests and execution against previous hot fire tests demonstrated that the SAFD algorithm can detect engine failure as much as tens of seconds before the redline system recognized the failure. Although the current algorithm only operates during steady state conditions (engine not throttling), work is underway to expand the algorithm to work during transient condition.

  5. Passivity and Dissipativity as Design and Analysis Tools for Networked Control Systems

    ERIC Educational Resources Information Center

    Yu, Han

    2012-01-01

    In this dissertation, several control problems are studied that arise when passive or dissipative systems are interconnected and controlled over a communication network. Since communication networks can impact the systems' stability and performance, there is a need to extend the results on control of passive or dissipative systems to networked…

  6. Passivity and Dissipativity as Design and Analysis Tools for Networked Control Systems

    ERIC Educational Resources Information Center

    Yu, Han

    2012-01-01

    In this dissertation, several control problems are studied that arise when passive or dissipative systems are interconnected and controlled over a communication network. Since communication networks can impact the systems' stability and performance, there is a need to extend the results on control of passive or dissipative systems to networked…

  7. System for Anomaly and Failure Detection (SAFD) system development

    NASA Technical Reports Server (NTRS)

    Oreilly, D.

    1993-01-01

    The System for Anomaly and Failure Detection (SAFD) algorithm was developed as an improvement over the current redline system used in the Space Shuttle Main Engine Controller (SSMEC). Simulation tests and execution against previous hot fire tests demonstrated that the SAFD algorithm can detect engine failures as much as tens of seconds before the redline system recognized the failure. Although the current algorithm only operates during steady state conditions (engine not throttling), work is underway to expand the algorithm to work during transient conditions. This task assignment originally specified developing a platform for executing the algorithm during hot fire tests at Technology Test Bed (TTB) and installing the SAFD algorithm on that platform. Two units were built and installed in the Hardware Simulation Lab and at the TTB in December 1991. Since that time, the task primarily entailed improvement and maintenance of the systems, additional testing to prove the feasibility of the algorithm, and support of hot fire testing. This document addresses the work done since the last report of June 1992. The work on the System for Anomaly and Failure Detection during this period included improving the platform and the algorithm, testing the algorithm against previous test data and in the Hardware Simulation Lab, installing other algorithms on the system, providing support for operations at the Technology Test Bed, and providing routine maintenance.

  8. Neural Feedback Passivity of Unknown Nonlinear Systems via Sliding Mode Technique.

    PubMed

    Yu, Wen

    2015-07-01

    Passivity method is very effective to analyze large-scale nonlinear systems with strong nonlinearities. However, when most parts of the nonlinear system are unknown, the published neural passivity methods are not suitable for feedback stability. In this brief, we propose a novel sliding mode learning algorithm and sliding mode feedback passivity control. We prove that for a wide class of unknown nonlinear systems, this neural sliding mode control can passify and stabilize them. This passivity method is validated with a simulation and real experiment tests.

  9. Synthesis of Optimal Constant-Gain Positive-Real Controllers for Passive Systems

    NASA Technical Reports Server (NTRS)

    Mao, Y.; Kelkar, A. G.; Joshi, S. M.

    1999-01-01

    This paper presents synthesis methods for the design of constant-gain positive real controllers for passive systems. The results presented in this paper, in conjunction with the previous work by the authors on passification of non-passive systems, offer a useful synthesis tool for the design of passivity-based robust controllers for non-passive systems as well. Two synthesis approaches are given for minimizing an LQ-type performance index, resulting in optimal controller gains. Two separate algorithms, one for each of these approaches, are given. The synthesis techniques are demonstrated using two numerical examples: control of a flexible structure and longitudinal control of a fighter aircraft.

  10. Synthesis of Optimal Constant-Gain Positive-Real Controllers for Passive Systems

    NASA Technical Reports Server (NTRS)

    Mao, Y.; Kelkar, A. G.; Joshi, S. M.

    1999-01-01

    This paper presents synthesis methods for the design of constant-gain positive real controllers for passive systems. The results presented in this paper, in conjunction with the previous work by the authors on passification of non-passive systems, offer a useful synthesis tool for the design of passivity-based robust controllers for non-passive systems as well. Two synthesis approaches are given for minimizing an LQ-type performance index, resulting in optimal controller gains. Two separate algorithms, one for each of these approaches, are given. The synthesis techniques are demonstrated using two numerical examples: control of a flexible structure and longitudinal control of a fighter aircraft.

  11. Failures of perception in the low-prevalence effect: Evidence from active and passive visual search.

    PubMed

    Hout, Michael C; Walenchok, Stephen C; Goldinger, Stephen D; Wolfe, Jeremy M

    2015-08-01

    In visual search, rare targets are missed disproportionately often. This low-prevalence effect (LPE) is a robust problem with demonstrable societal consequences. What is the source of the LPE? Is it a perceptual bias against rare targets or a later process, such as premature search termination or motor response errors? In 4 experiments, we examined the LPE using standard visual search (with eye tracking) and 2 variants of rapid serial visual presentation (RSVP) in which observers made present/absent decisions after sequences ended. In all experiments, observers looked for 2 target categories (teddy bear and butterfly) simultaneously. To minimize simple motor errors, caused by repetitive absent responses, we held overall target prevalence at 50%, with 1 low-prevalence and 1 high-prevalence target type. Across conditions, observers either searched for targets among other real-world objects or searched for specific bears or butterflies among within-category distractors. We report 4 main results: (a) In standard search, high-prevalence targets were found more quickly and accurately than low-prevalence targets. (b) The LPE persisted in RSVP search, even though observers never terminated search on their own. (c) Eye-tracking analyses showed that high-prevalence targets elicited better attentional guidance and faster perceptual decisions. And (d) even when observers looked directly at low-prevalence targets, they often (12%-34% of trials) failed to detect them. These results strongly argue that low-prevalence misses represent failures of perception when early search termination or motor errors are controlled.

  12. Failures of Perception in the Low-Prevalence Effect: Evidence From Active and Passive Visual Search

    PubMed Central

    Hout, Michael C.; Walenchok, Stephen C.; Goldinger, Stephen D.; Wolfe, Jeremy M.

    2017-01-01

    In visual search, rare targets are missed disproportionately often. This low-prevalence effect (LPE) is a robust problem with demonstrable societal consequences. What is the source of the LPE? Is it a perceptual bias against rare targets or a later process, such as premature search termination or motor response errors? In 4 experiments, we examined the LPE using standard visual search (with eye tracking) and 2 variants of rapid serial visual presentation (RSVP) in which observers made present/absent decisions after sequences ended. In all experiments, observers looked for 2 target categories (teddy bear and butterfly) simultaneously. To minimize simple motor errors, caused by repetitive absent responses, we held overall target prevalence at 50%, with 1 low-prevalence and 1 high-prevalence target type. Across conditions, observers either searched for targets among other real-world objects or searched for specific bears or butterflies among within-category distractors. We report 4 main results: (a) In standard search, high-prevalence targets were found more quickly and accurately than low-prevalence targets. (b) The LPE persisted in RSVP search, even though observers never terminated search on their own. (c) Eye-tracking analyses showed that high-prevalence targets elicited better attentional guidance and faster perceptual decisions. And (d) even when observers looked directly at low-prevalence targets, they often (12%–34% of trials) failed to detect them. These results strongly argue that low-prevalence misses represent failures of perception when early search termination or motor errors are controlled. PMID:25915073

  13. Optical pickup adjustment system using a passive alignment method

    NASA Astrophysics Data System (ADS)

    Abiko, Yukihiro; Yabuki, Akihiko; Koezuka, Tetsuo

    2002-03-01

    The optical pickup of a magneto-optical drive is constructed of millimeter-size optical components, including a laser diode (LD), a collimating lens (CL), a polarizing beam splitter, some kinds of prisms, and photo detectors (PD). Each component must be assembled with micrometer-order accuracy. In particular, the astigmatism, which is adjusted by changing the position of the CL, must be within 0.65 micrometers in the optical axis direction. To enable the CL position to be adjusted quantitatively, we developed an adjustment method that uses passive alignment. We estimated the astigmatism by analyzing an image of the LD, which is acquired through the CL by illuminating the LD with the polarized light. We developed an optical-pickup adjustment system using the proposed method and tested its effectiveness experimentally. The results showed that this system can be used to adjust the accuracy to within 0.65 micrometers. Because the image of the LD and the PD are acquired clearly by this system, it should be useful for not only adjusting the optical pickup but also for visually inspecting the LD and PD.

  14. Monitoring System of Railway Using Passive RFID in UHF Band

    NASA Astrophysics Data System (ADS)

    Makimura, Hidetoshi; Watanabe, Kota; Igarashi, Hajime; Waki, Hiroshi

    This paper presents a novel temperature measurement system based on passive RFID operating at UHF band for monitoring system of conventional railways. The goal of this study is to realize wireless temperature measurement using UHF-band RFID whose communication distance is several meters under the assumption that the RFID reader/writer (R/W) has 4 W EIRP. A low power temperature measurement circuit, which is vital for the above purpose, has been developed using a thermistor and comparator. The temperature measured by this sensor, ranging from zero to 80 Celsius, is shown to be in good agreement with theoretical value. The consumption power of this circuit is evaluated to be 8 μW by experiment. The sensor circuit is connected to an IC tag, which composed of a meander line antenna, whose shape has been optimized by genetic algorithm, Cockcroft-Walton circuit for booster and rectifier, and PIC for digital control. It is shown that the present wireless sensing system works well when distance between the IC tag and R/W, whose gain is 13 dBi, is set to 1 m and input power to R/W is 1 mW. From this result, the communication distance for 4 W EIRP is roughly estimated to be more than 10 m when neglecting polarization losses and other negative effects.

  15. Preliminary validation of a calf-side test for diagnosis of failure of transfer of passive immunity in dairy calves.

    PubMed

    Elsohaby, I; Keefe, G P

    2015-07-01

    The objective of this study was to evaluate the utility of an initial version of a calf-side test (ZAPvet Bovine IgG test, ZBx Corp., Toronto, ON, Canada) for diagnosis of failure of transfer of passive immunity (FTPI) in dairy calves. Blood samples (n=202) were collected from calves from 1 to 11d of age. Serum IgG concentration was determined by radial immunodiffusion (RID) assay. The mean IgG concentration was 1,764±1,035mg/dL, with a range from 133 to 5,995mg/dL. The ZAPvet Bovine IgG test was used to assess FTPI (serum IgG <1,000mg/dL) and test characteristics were calculated. The number of samples that had FTPI from the RID assay and ZAPvet test was 55 and 96 samples, resulting in a true prevalence of 27% and an apparent prevalence of 47.5%, respectively. The sensitivity, specificity, and positive and negative predictive values of the ZAPvet test were 0.82, 0.65, 0.47, and 0.91, respectively. The results of the ZAPvet test were derived from 2 observers, and the overall level of agreement between the results of the 2 observers was 84%, with a kappa value of 0.67. The ZAPvet Bovine IgG test showed good potential for further development as a cost-effective, rapid calf-side test for monitoring FTPI in dairy calves.

  16. Defense against common mode failures in protection system design

    SciTech Connect

    Wyman, R.H.; Johnson, G.L.

    1997-08-27

    The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods to cope with the concern. Common-mode failures have been a ``fact-of-life`` in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D&D)-coupled with the fact that hardware common-mode failures are often distributed in time-has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical approach to mitigating common-mode failure is needed to address these concerns. Purposeful introduction of D-in-D&D has been used as a defense against common-mode failure in reactor protection systems. At least two diverse systems are provided to mitigate any potential initiating event. Additionally, diverse displays and controls are provided to allow the operator to monitor plant status and manually initiate engineered safety features. A special form of conimon-mode failure analysis called ``defense-in-depth and diversity analysis`` has been developed to identify possible conimon-mode failure vulnerabilities in digital systems. An overview of this analysis technique is provided.

  17. Method for passive cooling liquid metal cooled nuclear reactors, and system thereof

    DOEpatents

    Hunsbedt, Anstein; Busboom, Herbert J.

    1991-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel.

  18. Fully-polarimetric passive MMW imaging systems for security applications

    NASA Astrophysics Data System (ADS)

    Peichl, Markus; Dill, Stephan; Jirousek, Matthias; Anthony, John-Walter; Süß, Helmut

    2010-10-01

    Increasing terroristic attacks raise the danger to the public and create a new and more complex dimension of threat. This evolution must and can only be combat by the application of new counter-measures like advanced imaging technologies for wide-area surveillance and the detection of concealed dangerous objects. Passive microwave remote sensing allows a daytime independent non-destructive observation and examination of the objects of interest under nearly all weather conditions. The acquisition of polarimetric object characteristics can increase the detection capability by gathering complementary object information. Over years the DLR Microwaves and Radar Institute developed several problem-orientated radiometer imaging systems covering nearly the whole frequency spectrum between 1 GHz and 100 GHz for a multitude of applications. Actually a fully-polarimetric radiometer receiver at W band is developed in order to explore the polarimetric information content of interesting objects simultaneously. Some important theoretical characteristics of polarimetric radiometry at millimeterwaves are introduced and discussed. The actual design and construction of the receiver system is outlined and first experimental imaging results are presented.

  19. Foundations for Improvements to Passive Detection Systems - Final Report

    SciTech Connect

    Labov, S E; Pleasance, L; Sokkappa, P; Craig, W; Chapline, G; Frank, M; Gronberg, J; Jernigan, J G; Johnson, S; Kammeraad, J; Lange, D; Meyer, A; Nelson, K; Pohl, B; Wright, D; Wurtz, R

    2004-10-07

    This project explores the scientific foundation and approach for improving passive detection systems for plutonium and highly enriched uranium in real applications. Sources of gamma-ray radiation of interest were chosen to represent a range of national security threats, naturally occurring radioactive materials, industrial and medical radiation sources, and natural background radiation. The gamma-ray flux emerging from these sources, which include unclassified criticality experiment configurations as surrogates for nuclear weapons, were modeled in detail. The performance of several types of gamma-ray imaging systems using Compton scattering were modeled and compared. A mechanism was created to model the combine sources and background emissions and have the simulated radiation ''scene'' impinge on a model of a detector. These modeling tools are now being used in various projects to optimize detector performance and model detector sensitivity in complex measuring environments. This study also developed several automated algorithms for isotope identification from gamma-ray spectra and compared these to each other and to algorithms already in use. Verification testing indicates that these alternative isotope identification algorithms produced less false positive and false negative results than the ''GADRAS'' algorithms currently in use. In addition to these algorithms that used binned spectra, a new approach to isotope identification using ''event mode'' analysis was developed. Finally, a technique using muons to detect nuclear material was explored.

  20. A passive wireless ultrasound pitch-catch system

    NASA Astrophysics Data System (ADS)

    Zahedi, F.; Yao, J.; Huang, H.

    2015-08-01

    This paper exploits amplitude modulation and demodulation to achieve a passive wireless ultrasound pitch-catch system consisting of a wireless interrogator and a combination of a wireless actuator and a sensor mounted on a structure. The wireless interrogator operates in two modes, i.e. the generation and sensing modes. At the generation mode, the interrogator transmits two microwave signals; one is amplitude modulated with the ultrasound excitation signal while the other is a continuous-wave carrier signal. Once received by the wireless actuator, the amplitude modulated signal is demodulated using the carrier signal to recover the ultrasound excitation signal, which is then supplied to a piezoelectric wafer actuator for ultrasound generation. Subsequently, the interrogator is switched to the sensing mode by transmitting a carrier signal with a different frequency. Once received by the wireless sensor, this carrier signal is modulated with the ultrasound sensing signal acquired by the piezoelectric wafer sensor to produce an amplitude modulated microwave signal, which can then be wirelessly transmitted and demodulated by the interrogator to recover the original ultrasound sensing signal. The principle and implementation of the wireless ultrasound pitch-catch system as well as the data processing of the wirelessly received sensing signal are described. Experiment results validating wireless ultrasound generation and sensing from a distance of 0.5 m are presented.

  1. HTS thin films: Passive microwave components and systems integration issues

    SciTech Connect

    Miranda, F.A.; Chorey, C.M.; Bhasin, K.B.

    1994-12-31

    The excellent microwave properties of the High-Temperature-Superconductors (HTS) have been amply demonstrated in the laboratory by techniques such as resonant cavity, power transmission and microstrip resonator measurements. The low loss and high Q passive structures made possible with HTS, present attractive options for applications in commercial, military and space-based systems. However, to readily insert HTS into these systems improvement is needed in such areas as repeatability in the deposition and processing of the HTS films, metal-contact formation, wire bonding, and overall film endurance to fabrication and assembly procedures. In this paper we present data compiled in our lab which illustrate many of the problems associated with these issues. Much of this data were obtained in the production of a space qualified hybrid receiver-downconverter module for the Naval Research Laboratory`s High Temperature Superconductivity Space Experiment II (HTSSE-II). Examples of variations observed in starting films and finished circuits will be presented. It is shown that under identical processing the properties of the HTS films can degrade to varying extents. Finally, we present data on ohmic contacts and factors affecting their adhesion to HTS films, strength of wire bonds made to such contacts, and aging effects.

  2. Evaluation of a fracture failure mode in the Space Shuttle hydrogen pressurization system flow control valves

    NASA Astrophysics Data System (ADS)

    Hauver, S. E.; Sueme, D. R.

    1992-07-01

    During acceptance testing of the Space Shuttle Endeavor hydrogen flow control valves, which are used in the Orbiter's fuel tank pressurization system, two of the valves experienced fracture of the poppet flange. The poppets are made of 440 C, a high strength, wear-resistant, low ductility, martensitic stainless steel. The investigation which was initiated to determine the cause of these failures is traced. All aspects of the poppet processing that may have introduced a defect were assessed. This included machining, heat treating, passivation, assembly, and test. In addition, several potential failure modes were investigated. The extensive investigation revealed no obvious cause of the failures, but did result in a recommendation for a different material application.

  3. A modeling framework for system restoration from cascading failures.

    PubMed

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  4. A Modeling Framework for System Restoration from Cascading Failures

    PubMed Central

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems. PMID:25474408

  5. Diagnosis of repeated failures in discrete event systems.

    SciTech Connect

    Garcia, H. E.; Jiang, S.; Kumar, R.; Univ. of Kentucky; Iowa State Univ.

    2002-01-01

    We introduce the notion of repeated failure diagnosability for diagnosing the occurrence of a repeated number of failures in discrete event systems. This generalizes the earlier notion of diagnosability that was used to diagnose the occurrence of a failure, but from which the information regarding the multiplicity of the occurrence of the failure could not be obtained. It is possible that in some systems the same type of failure repeats a multiple number of times. It is desirable to have a diagnoser which not only diagnoses that such a failure has occurred but also determines the number of times the failure has occurred. To aide such analysis we introduce the notions of K-diagnosability (K failures diagnosability), [1, K]-diagnosability (1 through K failures diagnosability), and [1, /spl infin/]-diagnosability (1 through /spl infin/ failures diagnosability). Here the first notion is the weakest of all three, and the earlier notion of diagnosability is the same as that of K-diagnosability or that of [1, K]-diagnosability with K=1. We give polynomial algorithms for checking these various notions of repeated failure diagnosability, and also present a procedure of polynomial complexity for the online diagnosis of repeated failures.

  6. Diagnosis of repeated/intermittent failures in discrete event systems.

    SciTech Connect

    Garcia, H. E.; Jiang, S.; Kumar, R.

    2003-04-01

    We introduce the notion of repeated failure diagnosability for diagnosing the occurrence of a repeated number of failures in discrete event systems. This generalizes the earlier notion of diagnosability that was used to diagnose the occurrence of a failure, but from which the information regarding the multiplicity of the occurrence of the failure could not be obtained. It is possible that in some systems the same type of failure repeats a multiple number of times. It is desirable to have a diagnoser which not only diagnoses that such a failure has occurred but also determines the number of times the failure has occurred. To aide such analysis we introduce the notions of K-diagnosability (K failures diagnosability), [1,K]-diagnosability (1 through K failures diagnosability), and [1,1]-diagnosability (1 through 1 failures diagnosability). Here the rst (resp., last) notion is the weakest (resp., strongest) of all three, and the earlier notion of diagnosability is the same as that of K-diagnosability or that of [1,K]- diagnosability with K = 1. We give polynomial algorithms for checking these various notions of repeated failure diagnosability, and also present a procedure of polynomial complexity for the on-line diagnosis of repeated failures.

  7. Spacecraft Parachute Recovery System Testing from a Failure Rate Perspective

    NASA Technical Reports Server (NTRS)

    Stewart, Christine E.

    2013-01-01

    Spacecraft parachute recovery systems, especially those with a parachute cluster, require testing to identify and reduce failures. This is especially important when the spacecraft in question is human-rated. Due to the recent effort to make spaceflight affordable, the importance of determining a minimum requirement for testing has increased. The number of tests required to achieve a mature design, with a relatively constant failure rate, can be estimated from a review of previous complex spacecraft recovery systems. Examination of the Apollo parachute testing and the Shuttle Solid Rocket Booster recovery chute system operation will clarify at which point in those programs the system reached maturity. This examination will also clarify the risks inherent in not performing a sufficient number of tests prior to operation with humans on-board. When looking at complex parachute systems used in spaceflight landing systems, a pattern begins to emerge regarding the need for a minimum amount of testing required to wring out the failure modes and reduce the failure rate of the parachute system to an acceptable level for human spaceflight. Not only a sufficient number of system level testing, but also the ability to update the design as failure modes are found is required to drive the failure rate of the system down to an acceptable level. In addition, sufficient data and images are necessary to identify incipient failure modes or to identify failure causes when a system failure occurs. In order to demonstrate the need for sufficient system level testing prior to an acceptable failure rate, the Apollo Earth Landing System (ELS) test program and the Shuttle Solid Rocket Booster Recovery System failure history will be examined, as well as some experiences in the Orion Capsule Parachute Assembly System will be noted.

  8. Spacecraft dynamics characterization and control system failure detection. Volume 3: Control system failure monitoring

    NASA Technical Reports Server (NTRS)

    Vanschalkwyk, Christiaan M.

    1992-01-01

    We discuss the application of Generalized Parity Relations to two experimental flexible space structures, the NASA Langley Mini-Mast and Marshall Space Flight Center ACES mast. We concentrate on the generation of residuals and make no attempt to implement the Decision Function. It should be clear from the examples that are presented whether it would be possible to detect the failure of a specific component. We derive the equations from Generalized Parity Relations. Two special cases are treated: namely, Single Sensor Parity Relations (SSPR) and Double Sensor Parity Relations (DSPR). Generalized Parity Relations for actuators are also derived. The NASA Langley Mini-Mast and the application of SSPR and DSPR to a set of displacement sensors located at the tip of the Mini-Mast are discussed. The performance of a reduced order model that includes the first five models of the mast is compared to a set of parity relations that was identified on a set of input-output data. Both time domain and frequency domain comparisons are made. The effect of the sampling period and model order on the performance of the Residual Generators are also discussed. Failure detection experiments where the sensor set consisted of two gyros and an accelerometer are presented. The effects of model order and sampling frequency are again illustrated. The detection of actuator failures is discussed. We use Generalized Parity Relations to monitor control system component failures on the ACES mast. An overview is given of the Failure Detection Filter and experimental results are discussed. Conclusions and directions for future research are given.

  9. [Passive nighttime warming (PNW) system, its design and warming effect].

    PubMed

    Chen, Jin; Yang, Fei; Zhang, Bin; Tian, Yun-lu; Dong, Wen-jun; Zhang, Wei-jian

    2010-09-01

    Based on the technique of passive nighttime warming (PNW), a convenient and energy-saving PNW facility was designed for a rice-wheat cropping system in Danyang, Jiangsu Province. The facility could guarantee 15.75 m2 effective sampling area, with a homogeneous amplitude of increased temperature, and making the nighttime canopy temperature during whole rice growth season increased averagely by 1.1 degrees C and the nighttime canopy temperature and 5 cm soil temperature during whole winter wheat growth period increased averagely by 1.3 degrees C and 0.8 degrees C, respectively. During the operation period of the facility, the variation trends of the canopy temperature and 5 cm soil temperature during the whole growth periods of rice and winter wheat in the warming plots were similar to those of the control. Though the facility slightly decreased the soil moisture content during winter wheat growth period, wheat growth was less impacted. The application of this facility in our main production areas of rice and winter wheat showed that the facility could advance the initial blossoming stages of rice and winter wheat averagely by 3 d and 5 d, respectively. In despite of the discrepancy in the warming effect among different regions and seasons, this energy-saving facility was reliable for the field research on crop responses to climate warming, when the homogeneity of increased temperature, the effective area, and the effects on crop growth period were taken into comprehensive consideration.

  10. Adaptive control of nonlinear systems with actuator failures and uncertainties

    NASA Astrophysics Data System (ADS)

    Tang, Xidong

    2005-11-01

    Actuator failures have damaging effect on the performance of control systems, leading to undesired system behavior or even instability. Actuator failures are unknown in terms of failure time instants, failure patterns, and failure parameters. For system safety and reliability, the compensation of actuator failures is of both theoretical and practical significance. This dissertation is to further the study of adaptive designs for actuator failure compensation to nonlinear systems. In this dissertation a theoretical framework for adaptive control of nonlinear systems with actuator failures and system uncertainties is established. The contributions are the development of new adaptive nonlinear control schemes to handle unknown actuator failures for convergent tracking performance, the specification of conditions as a guideline for applications and system designs, and the extension of the adaptive nonlinear control theory. In the dissertation, adaptive actuator failure compensation is studied for several classes of nonlinear systems. In particular, adaptive state feedback schemes are developed for feedback linearizable systems and parametric strict-feedback systems. Adaptive output feedback schemes are deigned for output-feedback systems and a class of systems with unknown state-dependent nonlinearities. Furthermore, adaptive designs are addressed for MIMO systems with actuator failures, based on two grouping techniques: fixed grouping and virtual grouping. Theoretical issues such as controller structures, actuation schemes, zero dynamics, observation, grouping conditions, closed-loop stability, and tracking performance are extensively investigated. For each scheme, design conditions are clarified, and detailed stability and performance analysis is presented. A variety of applications including a wing-rock model, twin otter aircraft, hypersonic aircraft, and cooperative multiple manipulators are addressed with simulation results showing the effectiveness of the

  11. Clinical outcome of calves with failure of passive transfer as diagnosed by a commercially available IgG quick test kit

    PubMed Central

    Stilwell, George; Carvalho, Rita C.

    2011-01-01

    The efficacy of an IgG quick test in detecting calves with failure of passive transfer was assessed. The test was carried out on 97 male calves, 38% of which were negative (IgG < 10 mg/mL). Morbidity and mortality due to infectious diseases were significantly higher in the negative group showing that the quick test is useful in identifying calves more susceptible to infectious disease. PMID:22043074

  12. Passivity-based sliding mode control for a polytopic stochastic differential inclusion system.

    PubMed

    Liu, Leipo; Fu, Zhumu; Song, Xiaona

    2013-11-01

    Passivity-based sliding mode control for a polytopic stochastic differential inclusion (PSDI) system is considered. A control law is designed such that the reachability of sliding motion is guaranteed. Moreover, sufficient conditions for mean square asymptotic stability and passivity of sliding mode dynamics are obtained by linear matrix inequalities (LMIs). Finally, two examples are given to illustrate the effectiveness of the proposed method.

  13. Hybrid Active/Passive Jet Engine Noise Suppression System

    NASA Technical Reports Server (NTRS)

    Parente, C. A.; Arcas, N.; Walker, B. E.; Hersh, A. S.; Rice, E. J.

    1999-01-01

    A novel adaptive segmented liner concept has been developed that employs active control elements to modify the in-duct sound field to enhance the tone-suppressing performance of passive liner elements. This could potentially allow engine designs that inherently produce more tone noise but less broadband noise, or could allow passive liner designs to more optimally address high frequency broadband noise. A proof-of-concept validation program was undertaken, consisting of the development of an adaptive segmented liner that would maximize attenuation of two radial modes in a circular or annular duct. The liner consisted of a leading active segment with dual annuli of axially spaced active Helmholtz resonators, followed by an optimized passive liner and then an array of sensing microphones. Three successively complex versions of the adaptive liner were constructed and their performances tested relative to the performance of optimized uniform passive and segmented passive liners. The salient results of the tests were: The adaptive segmented liner performed well in a high flow speed model fan inlet environment, was successfully scaled to a high sound frequency and successfully attenuated three radial modes using sensor and active resonator arrays that were designed for a two mode, lower frequency environment.

  14. Development of an adaptive failure detection and identification system for detecting aircraft control element failures

    NASA Technical Reports Server (NTRS)

    Bundick, W. Thomas

    1990-01-01

    A methodology for designing a failure detection and identification (FDI) system to detect and isolate control element failures in aircraft control systems is reviewed. An FDI system design for a modified B-737 aircraft resulting from this methodology is also reviewed, and the results of evaluating this system via simulation are presented. The FDI system performed well in a no-turbulence environment, but it experienced an unacceptable number of false alarms in atmospheric turbulence. An adaptive FDI system, which adjusts thresholds and other system parameters based on the estimated turbulence level, was developed and evaluated. The adaptive system performed well over all turbulence levels simulated, reliably detecting all but the smallest magnitude partially-missing-surface failures.

  15. Automatic patient respiration failure detection system with wireless transmission

    NASA Technical Reports Server (NTRS)

    Dimeff, J.; Pope, J. M.

    1968-01-01

    Automatic respiration failure detection system detects respiration failure in patients with a surgically implanted tracheostomy tube, and actuates an audible and/or visual alarm. The system incorporates a miniature radio transmitter so that the patient is unencumbered by wires yet can be monitored from a remote location.

  16. Lunar Module Electrical Power System Design Considerations and Failure Modes

    NASA Technical Reports Server (NTRS)

    Interbartolo, Michael

    2009-01-01

    This slide presentation reviews the design and redesign considerations of the Apollo lunar module electrical power system. Included in the work are graphics showing the lunar module power system. It describes the in-flight failures, and the lessons learned from these failures.

  17. Control system analysis for off-peak auxiliary heating of passive solar systems

    SciTech Connect

    Murray, H.S.; Melsa, J.L.; Balcomb, J.D.

    1980-01-01

    A computer simulation method is presented for the design of an electrical auxiliary energy system for passive solar heated structures. The system consists of electrical mats buried in the ground underneath the structure. Energy is stored in the ground during utility off-peak hours and released passively to the heated enclosure. An optimal control strategy is used to determine the system design parameters of depth of mat placement and minimum instaled electrical heating capacity. The optimal control applies combinations of fixed duration energy pulses to the heater, which minimize the room temperature error-squared for each day, assuming advance knowledge of the day's weather. Various realizable control schemes are investigated in an attempt to find a system that approaches the performance of the optimal control system.

  18. Extended Range Passive Wireless Tag System and Method

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor); Kennedy, Timothy F. (Inventor); Lin, Gregory Y. (Inventor)

    2013-01-01

    A passive wireless tag assembly comprises a plurality of antennas and transmission lines interconnected with circuitry and constructed and arranged in a Van Atta array or configuration to reflect an interrogator signal in the direction from where it came. The circuitry may comprise at least one surface acoustic wave (SAW)-based circuit that functions as a signal reflector and is operatively connected with an information circuit. In another embodiment, at least one delay circuit and/or at least one passive modulation circuit(s) are utilized. In yet another embodiment, antennas connected to SAW-based devices are mounted to at least one of the orthogonal surfaces of a corner reflector.

  19. Active and Passive RF Components for High-Power Systems

    SciTech Connect

    Nantista, Christopher D.

    2002-09-06

    In recent years, R&D for pulse compression and power distribution systems for the Next Linear Collider has led to the invention of many novel rf components, some of which must handle up to 600 MW of pulsed power at X-band. These include passive waveguide components, active switch designs, and non-reciprocal devices. Among the former is a class of multi-moded, highly efficient rf components based on planar geometries with overmoded rectangular ports. Multi-moding allows us, by means of input phasing, to direct power to different locations through the same waveguide. Planar symmetry allows the height to be increased to improve power handling capacity. Features that invite breakdown, such as coupling slots, irises and H-plane septa, are avoided. This class includes hybrids, directional couplers, an eight-port superhybrid/dual-mode launcher, a mode-selective extractor, mode-preserving bends, a rectangular mode converter, and mode-mixers. We are able to utilize such rectangular waveguide components in systems incorporating low-loss, circular waveguide delay lines by means of specially designed tapers that efficiently transform multiple rectangular waveguide modes into their corresponding circular waveguide modes, specifically TE10 and TE20 into circular TE11 and TE01. These extremely compact tapers can replace well-known mode converters such as the Marie type. Another component, a reflective TE01-TE02 mode converter in circular waveguide, allows us to double the delay in reflective or resonant delay lines. Ideas for multi-megawatt active components, such as switches, have also been pursued. Power-handling capacity for these is increased by making them also highly overmoded. We present a design methodology for active rf magnetic components which are suitable for pulse compression systems of future X-band linear colliders. We also present an active switch based on a PIN diode array. This component comprises an array of active elements arranged so that the electric fields

  20. 78 FR 41436 - Proposed Revision to Treatment of Non-Safety Systems for Passive Advanced Light Water Reactors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    ... COMMISSION Proposed Revision to Treatment of Non-Safety Systems for Passive Advanced Light Water Reactors... Treatment of Non-Safety Systems (RTNSS) for Passive Advanced Light Water Reactors.'' The NRC seeks public...- Safety Systems (RTNSS) for Passive Advanced Light Water Reactors.'' This area includes a revised...

  1. Component criticality in failure cascade processes of network systems.

    PubMed

    Zio, Enrico; Sansavini, Giovanni

    2011-08-01

    In this work, specific indicators are used to characterize the criticality of components in a network system with respect to their contribution to failure cascade processes. A realistic-size network is considered as reference case study. Three different models of cascading failures are analyzed, differing both on the failure load distribution logic and on the cascade triggering event. The criticality indicators are compared to classical measures of topological centrality to identify the one most characteristic of the cascade processes considered.

  2. X-framework: Space system failure analysis framework

    NASA Astrophysics Data System (ADS)

    Newman, John Steven

    Space program and space systems failures result in financial losses in the multi-hundred million dollar range every year. In addition to financial loss, space system failures may also represent the loss of opportunity, loss of critical scientific, commercial and/or national defense capabilities, as well as loss of public confidence. The need exists to improve learning and expand the scope of lessons documented and offered to the space industry project team. One of the barriers to incorporating lessons learned include the way in which space system failures are documented. Multiple classes of space system failure information are identified, ranging from "sound bite" summaries in space insurance compendia, to articles in journals, lengthy data-oriented (what happened) reports, and in some rare cases, reports that treat not only the what, but also the why. In addition there are periodically published "corporate crisis" reports, typically issued after multiple or highly visible failures that explore management roles in the failure, often within a politically oriented context. Given the general lack of consistency, it is clear that a good multi-level space system/program failure framework with analytical and predictive capability is needed. This research effort set out to develop such a model. The X-Framework (x-fw) is proposed as an innovative forensic failure analysis approach, providing a multi-level understanding of the space system failure event beginning with the proximate cause, extending to the directly related work or operational processes and upward through successive management layers. The x-fw focus is on capability and control at the process level and examines: (1) management accountability and control, (2) resource and requirement allocation, and (3) planning, analysis, and risk management at each level of management. The x-fw model provides an innovative failure analysis approach for acquiring a multi-level perspective, direct and indirect causation of

  3. On Correlated Failures in Survivable Storage Systems

    DTIC Science & Technology

    2002-05-01

    Littlewood, D.R. Miller, “Conceptual modeling of coincident failures in multiversion software”, IEEE Transactions on Software Engineering, Volume: 15 Issue...Recovery in Multiversion Software”. IEEE Transaction on Software Engineering, Vol. 16 No.3, March 1990 [Plank1997] J. Plank “A tutorial on Reed-Solomon

  4. Predicting Computer System Failures Using Support Vector Machines

    SciTech Connect

    Fulp, Errin W.; Fink, Glenn A.; Haack, Jereme N.

    2008-12-07

    Mitigating the impact of computer failure is possible if accurate failure predictions are provided. Resources, applications, and services can be scheduled around predicted failure and limit the impact. Such strategies are especially important for multi-computer systems, such as compute clusters, that experience a higher rate failure due to the large number of components. However providing accurate predictions with sufficient lead time remains a challenging problem. This paper describes a new spectrum-kernel Support Vector Machine (SVM) approach to predict failure events based on system log files. These files contain messages that represent a change of system state. While a single message in the file may not be sufficient for predicting failure, a sequence or pattern of messages may be. The approach described in this paper will use a sliding window (sub-sequence) of messages to predict the likelihood of failure. The frequency representation of the message sub-sequences observed are then used as input to the SVM that associates the messages to a class of failed or non-failed system. Experimental results using actual system log files from a Linux-based compute cluster indicate the proposed SVM approach can predict hard disk failure with an accuracy of 76% one day in advance.

  5. Control of Flexible Systems in the Presence of Failures

    NASA Technical Reports Server (NTRS)

    Magahami, Peiman G.; Cox, David E.; Bauer, Frank H. (Technical Monitor)

    2001-01-01

    Control of flexible systems under degradation or failure of sensors/actuators is considered. A Linear Matrix Inequality framework is used to synthesize H(sub infinity)-based controllers, which provide good disturbance rejection while capable of tolerating real parameter uncertainties in the system model, as well as potential degradation or failure of the control system hardware. In this approach, a one-at-a-time failure scenario is considered, wherein no more than one sensor or actuator is allowed to fail at any given time. A numerical example involving control synthesis for a two-dimensional flexible system is presented to demonstrate the feasibility of the proposed approach.

  6. Quasi-3DOF Active / Passive Hybrid Rehabilitation System for Upper Limbs: "Hybrid-PLEMO"

    NASA Astrophysics Data System (ADS)

    Kikuchi, Takehito; Furusho, Junji; Jin, Ying; Fukushima, Kazuki; Akai, Hiroki

    Many kinds of actuator-based (active type) haptic device have developed and utilized as rehabilitation robots. These systems have great advantages for rehabilitative activities, for example assistive forces and so on. However, from the view point of safety, we have room to consider utilizing brake-based (passive type) haptic devices as rehabilitation-tools. The effects and roles of active / passive force feedback for rehabilitative trainings have not been clarified yet. In this study, we have developed an active / passive switchable rehabilitation system for upper limbs (Hybrid-PLEMO) to address these questions. In this paper, we describe the force-feedback mechanism of the Hybrid-PLEMO.

  7. Testing of Passive Safety System Performance for Higher Power Advanced Reactors

    SciTech Connect

    brian G. Woods; Jose Reyes, Jr.; John Woods; John Groome; Richard Wright

    2004-12-31

    This report describes the results of NERI research on the testing of advanced passive safety performance for the Westinghouse AP1000 design. The objectives of this research were: (a) to assess the AP1000 passive safety system core cooling performance under high decay power conditions for a spectrum of breaks located at a variety of locations, (b) to compare advanced thermal hydraulic computer code predictions to the APEX high decay power test data and (c) to develop new passive safety system concepts that could be used for Generation IV higher power reactors.

  8. Prevalence and calf-level risk factors for failure of passive transfer in dairy calves in New Zealand.

    PubMed

    Cuttance, E L; Mason, W A; Laven, R A; McDermott, J; Phyn, Cvc

    2017-11-01

    AIM To determine the prevalence of failure of passive transfer (FPT) in dairy calves in New Zealand and to assess a range of potential calf-level risk factors for their association with FPT. METHOD Between July and September 2015, 107 dairy farms in nine regions across New Zealand were visited on three occasions: before 20% of cows had calved, when ∼50% of cows had calved, and when the last 10-20% of cows were calving. Farms were randomly selected from the client list of participating veterinary practices. On each farm, blood samples were collected from 10-20 calves between 24 hours and 8 days old and concentrations of total protein (TP) in serum determined. Calf identification, date of birth, dam's age and breed, details of colostrum feeding and the farmer's health assessment of the calf on arrival at the calf rearing facility were recorded. Concentrations of TP in serum ≤52 g/L were used to define FPT. RESULTS Of 3,819 calves sampled, 1,263 (33 (95% CI=31.6-34.6)%) were diagnosed with FPT, and the prevalence within farms ranged from 5-83%. Calf-level risk factors that were associated with increased odds of FPT were increasing age of dam (OR=1.12; 95% CI=1.08-1.16), calves recorded as unhealthy compared to healthy upon arrival at the calf rearing facility (OR=2.59; 95% CI=1.60-4.19), calves sampled on farms in Otago (OR=2.85; 95% CI=1.42-5.74) and Southland (OR 2.31; 95% CI=1.15-4.67) compared to the Far North, and calves sampled in the middle compared to the early calving period (OR=1.24; 95% CI=1.03-1.51). CONCLUSION On the farms visited FPT was diagnosed in one third of dairy calves. Calf-level risk factors for FPT included age of dam, health status of calf, region, and time of the calving period. Further investigations are required to establish why these are associated with increased odds of FPT. CLINICAL RELEVANCE These results provide a baseline for benchmarking, which, alongside the reported calf-level risk factors, can be used by veterinarians to

  9. Integrated Passive Biological Treatment System/ Mine Waste Technology Program Report #16

    EPA Science Inventory

    This report summarizes the results of the Mine Waste Technology Program (MWTP) Activity III, Project 16, Integrated, Passive Biological Treatment System, funded by the United States Environmental Protection Agency (EPA) and jointly administered by EPA and the United States Depar...

  10. Integrated Passive Biological Treatment System/ Mine Waste Technology Program Report #16

    EPA Science Inventory

    This report summarizes the results of the Mine Waste Technology Program (MWTP) Activity III, Project 16, Integrated, Passive Biological Treatment System, funded by the United States Environmental Protection Agency (EPA) and jointly administered by EPA and the United States Depar...

  11. Letter report seismic shutdown system failure mode and effect analysis

    SciTech Connect

    KECK, R.D.

    1999-09-01

    The Supply Ventilation System Seismic Shutdown ensures that the 234-52 building supply fans, the dry air process fans and vertical development calciner are shutdown following a seismic event. This evaluates the failure modes and determines the effects of the failure modes.

  12. Applying Systems Analysis to Program Failure in Organizations.

    ERIC Educational Resources Information Center

    Holt, Margaret E.; And Others

    1986-01-01

    Certain systems analysis techniques can be applied to examinations of program failure in continuing education to locate weaknesses in planning and implementing stages. Questions to guide an analysis and various procedures are recommended. Twelve issues that contribute to failures or discontinuations are identified. (Author/MLW)

  13. Degradation and Failure Characteristics of NPP Containment Protective Coating Systems

    SciTech Connect

    Sindelar, R.L.

    2000-12-01

    A research program to investigate the performance and potential for failure of Service Level I coating systems used in nuclear power plant containment is in progress. The research activities are aligned to address phenomena important to cause failure as identified by the industry coatings expert panel.

  14. Identification of systems failures in successful paediatric cardiac surgery.

    PubMed

    Catchpole, K R; Giddings, A E B; de Leval, M R; Peek, G J; Godden, P J; Utley, M; Gallivan, S; Hirst, G; Dale, T

    Patient safety will benefit from an approach to human error that examines systemic causes, rather than blames individuals. This study describes a direct observation methodology, based on a threat and error model, prospectively to identify types and sources of systems failures in paediatric cardiac surgery. Of substantive interest were the range, frequency and types of failures that could be identified and whether minor failures could accumulate to form more serious events, as has been the case in other industries. Check lists, notes and video recordings were employed to observe 24 successful operations. A total of 366 failures were recorded. Coordination and communication problems, equipment problems, a relaxed safety culture, patient-related problems and perfusion-related problems were most frequent, with a smaller number of skill, knowledge and decision-making failures. Longer and more risky operations were likely to generate a greater number of minor failures than shorter and lower risk operations, and in seven higher-risk cases frequently occurring minor failures accumulated to threaten the safety of the patient. Non-technical errors were more prevalent than technical errors and task threats were the most prevalent systemic source of error. Adverse events in surgery are likely to be associated with a number of recurring and prospectively identifiable errors. These may be co-incident and cumulative human errors predisposed by threats embedded in the system, rather than due to individual incompetence or negligence. Prospectively identifying and reducing these recurrent failures would lead to improved surgical standards and enhanced patient safety.

  15. 77 FR 62270 - Proposed Revision Treatment of Non-Safety Systems for Passive Advanced Light Water Reactors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-12

    ... Non-Safety Systems for Passive Advanced Light Water Reactors AGENCY: Nuclear Regulatory Commission... Systems (RTNSS) for Passive Advanced Light Water Reactors.'' The current SRP does not contain guidance on the proposed RTNSS for Passive Advance Light Water Reactors. DATES: Submit comments by November...

  16. Passive Control of Limit Cycle Oscillations in a Thermoacoustic System using Asymmetry

    DTIC Science & Technology

    2006-09-05

    Passive Control of Limit Cycle Oscillations in a Thermoacoustic System using Asymmetry Bryan Eisenhower ∗ Gregory Hagen † Andrzej Banaszuk ‡ Igor...Mezić § September 5, 2006 Abstract In this paper we investigate oscillations of a dynamical system containing passive dynamics driven by a positive...motivation of this problem is thermoacoustic dynamics in a gas turbine combustor. The spatial domain is periodic (pas- sive annular acoustics) which are

  17. The simulation of a passive solar energy system

    NASA Astrophysics Data System (ADS)

    Slate, M. P.

    1982-12-01

    A simple lumped capacitance-resistance model is used to simulate heat flow in a residential size structure heated passively by the sun. The model takes the form of an analogous electrical circuit. A computer program was written to analyse the circuit. By altering the input parameters of the program, the thermal performance of a wide variety of passive solar designs can be investigated for any geographical location. By comparing program generated data to data taken from experimental test cells in Los Alamos, New Mexico, it was found that the simulation program predicted energy use to within 4 percent of measured values. Also, the computer program predicted temperature swings to within 16 percent of measured swings. Correlation with empirical methods of calculating monthly and annual savings in fuel use for heating was poor. Using the simulation calculations as a base, the predictions of annual savings differed by as much as 76 percent.

  18. How Fast Is Your Body Motion? Determining a Sufficient Frame Rate for an Optical Motion Tracking System Using Passive Markers.

    PubMed

    Song, Min-Ho; Godøy, Rolf Inge

    2016-01-01

    This paper addresses how to determine a sufficient frame (sampling) rate for an optical motion tracking system using passive reflective markers. When using passive markers for the optical motion tracking, avoiding identity confusion between the markers becomes a problem as the speed of motion increases, necessitating a higher frame rate to avoid a failure of the motion tracking caused by marker confusions and/or dropouts. Initially, one might believe that the Nyquist-Shannon sampling rate estimated from the assumed maximal temporal variation of a motion (i.e. a sampling rate at least twice that of the maximum motion frequency) could be the complete solution to the problem. However, this paper shows that also the spatial distance between the markers should be taken into account in determining the suitable frame rate of an optical motion tracking with passive markers. In this paper, a frame rate criterion for the optical tracking using passive markers is theoretically derived and also experimentally verified using a high-quality optical motion tracking system. Both the theoretical and the experimental results showed that the minimum frame rate is proportional to the ratio between the maximum speed of the motion and the minimum spacing between markers, and may also be predicted precisely if the proportional constant is known in advance. The inverse of the proportional constant is here defined as the tracking efficiency constant and it can be easily determined with some test measurements. Moreover, this newly defined constant can provide a new way of evaluating the tracking algorithm performance of an optical tracking system.

  19. How Fast Is Your Body Motion? Determining a Sufficient Frame Rate for an Optical Motion Tracking System Using Passive Markers

    PubMed Central

    Song, Min-Ho; Godøy, Rolf Inge

    2016-01-01

    This paper addresses how to determine a sufficient frame (sampling) rate for an optical motion tracking system using passive reflective markers. When using passive markers for the optical motion tracking, avoiding identity confusion between the markers becomes a problem as the speed of motion increases, necessitating a higher frame rate to avoid a failure of the motion tracking caused by marker confusions and/or dropouts. Initially, one might believe that the Nyquist-Shannon sampling rate estimated from the assumed maximal temporal variation of a motion (i.e. a sampling rate at least twice that of the maximum motion frequency) could be the complete solution to the problem. However, this paper shows that also the spatial distance between the markers should be taken into account in determining the suitable frame rate of an optical motion tracking with passive markers. In this paper, a frame rate criterion for the optical tracking using passive markers is theoretically derived and also experimentally verified using a high-quality optical motion tracking system. Both the theoretical and the experimental results showed that the minimum frame rate is proportional to the ratio between the maximum speed of the motion and the minimum spacing between markers, and may also be predicted precisely if the proportional constant is known in advance. The inverse of the proportional constant is here defined as the tracking efficiency constant and it can be easily determined with some test measurements. Moreover, this newly defined constant can provide a new way of evaluating the tracking algorithm performance of an optical tracking system. PMID:26967900

  20. A concept of JAERI passive safety light water reactor system (JPSR)

    SciTech Connect

    Murao, Y.; Araya, F.; Iwamura, T.

    1995-09-01

    The Japan Atomic Energy Research Institute (JAERI) proposed a passive safety reactor system concept, JPSR, which was developed for reducing manpower in operation and maintenance and influence of human errors on reactor safety. In the concept the system was extremely simplified. The inherent matching nature of core generation and heat removal rate within a small volume change of the primary coolant is introduced by eliminating chemical shim and adopting in-vessel control rod drive mechanism units, a low power density core and once-through steam generators. In order to simplify the system, a large pressurizer, canned pumps, passive engineered-safety-features-system (residual heat removal system and coolant injection system) are adopted and the total system can be significantly simplified. The residual heat removal system is completely passively actuated in non-LOCAs and is also used for depressurization of the primary coolant system to actuate accumulators in small break LOCAs and reactor shutdown cooling system in normal operation. All of systems for nuclear steam supply system are built in the containment except for the air coolers as a the final heat sink of the passive residual heat removal system. Accordingly the reliability of the safety system and the normal operation system is improved, since most of residual heat removal system is always working and a heat sink for normal operation system is {open_quotes}safety class{close_quotes}. In the passive coolant injection system, depressurization of the primary cooling system by residual heat removal system initiates injection from accumulators designed for the MS-600 in medium pressure and initiates injection from the gravity driven coolant injection pool at low pressure. Analysis with RETRAN-02/MOD3 code demonstrated the capability of passive load-following, self-power-controllability, cooling and depressurization.

  1. Modeling Chemical Detection Sensitivities of Active and Passive Remote Sensing Systems

    SciTech Connect

    Scharlemann, E T

    2003-07-28

    During nearly a decade of remote sensing programs under the auspices of the U. S. Department of Energy (DOE), LLNL has developed a set of performance modeling codes--called APRS--for both Active and Passive Remote Sensing systems. These codes emphasize chemical detection sensitivity in the form of minimum detectable quantities with and without background spectral clutter and in the possible presence of other interfering chemicals. The codes have been benchmarked against data acquired in both active and passive remote sensing programs at LLNL and Los Alamos National Laboratory (LANL). The codes include, as an integral part of the performance modeling, many of the data analysis techniques developed in the DOE's active and passive remote sensing programs (e.g., ''band normalization'' for an active system, principal component analysis for a passive system).

  2. Target detection using microwave irradiances from natural sources: A passive, local and global surveillance system

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.

    1984-01-01

    Detection of metal objects on or near the Earth's surface was investigated using existing, passive, microwave sensors operating from Earth orbit. The range equations are derived from basic microwave principles and theories and the expressions are given explicitly to estimate the signal to noise ratio for detecting metal targets operating as bistatic scatterers. Actual measurements are made on a range of metal objects observed from orbit using existing passive microwave receiving systems. The details of the measurements and the results are tabulated and discussed. The advantages of a passive microwave sensor as it is applied to surveillance of metal objects as viewed from aerial platforms or from orbit, are examined.

  3. Potential Application of a Thermoelectric Generator in Passive Cooling System of Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Wang, Dongqing; Liu, Yu; Jiang, Jin; Pang, Wei; Lau, Woon Ming; Mei, Jun

    2016-12-01

    In the design of nuclear power plants, various natural circulation passive cooling systems are considered to remove residual heat from the reactor core in the event of a power loss and maintain the plant's safety. These passive systems rely on gravity differences of fluids, resulting from density differentials, rather than using an external power-driven system. Unfortunately, a major drawback of such systems is their weak driving force, which can negatively impact safety. In such systems, there is a temperature difference between the heat source and the heat sink, which potentially offers a natural platform for thermoelectric generator (TEG) applications. While a previous study designed and analyzed a TEG-based passive core cooling system, this paper considers TEG applications in other passive cooling systems of nuclear power plants, after which the concept of a TEG-based passive cooling system is proposed. In such a system, electricity is produced using the system's temperature differences through the TEG, and this electricity is used to further enhance the cooling process.

  4. Potential Application of a Thermoelectric Generator in Passive Cooling System of Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Wang, Dongqing; Liu, Yu; Jiang, Jin; Pang, Wei; Lau, Woon Ming; Mei, Jun

    2017-05-01

    In the design of nuclear power plants, various natural circulation passive cooling systems are considered to remove residual heat from the reactor core in the event of a power loss and maintain the plant's safety. These passive systems rely on gravity differences of fluids, resulting from density differentials, rather than using an external power-driven system. Unfortunately, a major drawback of such systems is their weak driving force, which can negatively impact safety. In such systems, there is a temperature difference between the heat source and the heat sink, which potentially offers a natural platform for thermoelectric generator (TEG) applications. While a previous study designed and analyzed a TEG-based passive core cooling system, this paper considers TEG applications in other passive cooling systems of nuclear power plants, after which the concept of a TEG-based passive cooling system is proposed. In such a system, electricity is produced using the system's temperature differences through the TEG, and this electricity is used to further enhance the cooling process.

  5. Utility-scale system preventive and failure-related maintenance

    SciTech Connect

    Jennings, C.; Hutchinson, P.

    1995-11-01

    This paper describes the design and performance background on PVUSA utility-scale systems at Davis and Kerman, California, and reports on a preventative and failure-related maintenance approach and costs.

  6. Drive system failure control for distributed drive electric vehicles

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Tang, Yuan; Wang, Jianfeng; Li, Yaou; Yang, Na; Liu, Yiqun

    2017-09-01

    Aiming at the failure problem of distributed electric drive vehicle, the conventional control strategy of drive system failure is designed according to the characteristics of each wheel torque independent control and the redundant configuration of the power unit. On this basis, combined with the traditional body stability control technology, the direct yaw moment control method is used. The simulation results show that the conventional control method designed of the drive system failure can effectively improve the driving condition of the vehicle. The driving stability of the vehicle is further improved after the direct yaw torque control is applied.

  7. Failure Mode Effects Analysis for an Accelerator Control System

    SciTech Connect

    Hartman, Steven M

    2009-01-01

    Failure mode effects analysis (FMEA) has been used in industry for design, manufacturing and assembly process quality control. It describes a formal approach for categorizing how a process may fail and for prioritizing failures based on their severity, frequency and likelihood of detection. Experience conducting a partial FMEA of an accelerator subsystem and its related control system will be reviewed. The applicability of the FMEA process to an operational accelerator control system will be discussed.

  8. System and Method for Calculating the Directivity Index of a Passive Acoustic Array

    DTIC Science & Technology

    2007-07-27

    DIRECTIVITY INDEX OF A PASSIVE ACOUSTIC ARRAY STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and used by or...directed to a system and method for calculating the directivity index of a passive acoustic array with directional sensors in an isotropic noise field...and to provide an efficient way to create, modify, and model any array geometry for the purposes of determining the directivity index of the array as

  9. Failure Diagnosis for the Holdup Tank System via ISFA

    SciTech Connect

    Li, Huijuan; Bragg-Sitton, Shannon; Smidts, Carol

    2016-11-01

    This paper discusses the use of the integrated system failure analysis (ISFA) technique for fault diagnosis for the holdup tank system. ISFA is a simulation-based, qualitative and integrated approach used to study fault propagation in systems containing both hardware and software subsystems. The holdup tank system consists of a tank containing a fluid whose level is controlled by an inlet valve and an outlet valve. We introduce the component and functional models of the system, quantify the main parameters and simulate possible failure-propagation paths based on the fault propagation approach, ISFA. The results show that most component failures in the holdup tank system can be identified clearly and that ISFA is viable as a technique for fault diagnosis. Since ISFA is a qualitative technique that can be used in the very early stages of system design, this case study provides indications that it can be used early to study design aspects that relate to robustness and fault tolerance.

  10. Passive-solar-cooling system concepts for small office buildings. Final report

    SciTech Connect

    Whiddon, W.I.; Hart, G.K.

    1983-02-01

    This report summarizes the efforts of a small group of building design professionals and energy analysis experts to develop passive solar cooling concepts including first cost estimates for small office buildings. Two design teams were brought together at each of two workshops held in the fall of 1982. Each team included an architect, mechanical engineer, structural engineer, and energy analysis expert. This report presents the passive cooling system concepts resulting from the workshops. It summarizes the design problems, solutions and first-cost estimates relating to each technology considered, and documents the research needs identified by the participants in attempting to implement the various technologies in an actual building design. Each design problem presented at the workshops was based on the reference (base case) small office building analyzed as part of LBL's Cooling Assessment. Chapter II summarizes the thermal performance, physical specifications and estimated first-costs of the base case design developed for this work. Chapters III - VI describe the passive cooling system concepts developed for each technology: beam daylighting; mass with night ventilation; evaporative cooling; and integrated passive cooling systems. The final Chapters, VII and VIII present the preliminary implications for economics of passive cooling technologies (based on review of the design concepts) and recommendations of workshop participants for future research in passive cooling for commercial buildings. Appendices provide backup information on each chapter as indicated.

  11. EPMOSt: an energy-efficient passive monitoring system for wireless sensor networks.

    PubMed

    Garcia, Fernando P; Andrade, Rossana M C; Oliveira, Carina T; de Souza, José Neuman

    2014-06-19

    Monitoring systems are important for debugging and analyzing Wireless Sensor Networks (WSN). In passive monitoring, a monitoring network needs to be deployed in addition to the network to be monitored, named the target network. The monitoring network captures and analyzes packets transmitted by the target network. An energy-efficient passive monitoring system is necessary when we need to monitor a WSN in a real scenario because the lifetime of the monitoring network is extended and, consequently, the target network benefits from the monitoring for a longer time. In this work, we have identified, analyzed and compared the main passive monitoring systems proposed for WSN. During our research, we did not identify any passive monitoring system for WSN that aims to reduce the energy consumption of the monitoring network. Therefore, we propose an Energy-efficient Passive MOnitoring SysTem for WSN named EPMOSt that provides monitoring information using a Simple Network Management Protocol (SNMP) agent. Thus, any management tool that supports the SNMP protocol can be integrated with this monitoring system. Experiments with real sensors were performed in several scenarios. The results obtained show the energy efficiency of the proposed monitoring system and the viability of using it to monitor WSN in real scenarios.

  12. EPMOSt: An Energy-Efficient Passive Monitoring System for Wireless Sensor Networks

    PubMed Central

    Garcia, Fernando P.; Andrade, Rossana M. C.; Oliveira, Carina T.; de Souza, José Neuman

    2014-01-01

    Monitoring systems are important for debugging and analyzing Wireless Sensor Networks (WSN). In passive monitoring, a monitoring network needs to be deployed in addition to the network to be monitored, named the target network. The monitoring network captures and analyzes packets transmitted by the target network. An energy-efficient passive monitoring system is necessary when we need to monitor a WSN in a real scenario because the lifetime of the monitoring network is extended and, consequently, the target network benefits from the monitoring for a longer time. In this work, we have identified, analyzed and compared the main passive monitoring systems proposed for WSN. During our research, we did not identify any passive monitoring system for WSN that aims to reduce the energy consumption of the monitoring network. Therefore, we propose an Energy-efficient Passive MOnitoring SysTem for WSN named EPMOSt that provides monitoring information using a Simple Network Management Protocol (SNMP) agent. Thus, any management tool that supports the SNMP protocol can be integrated with this monitoring system. Experiments with real sensors were performed in several scenarios. The results obtained show the energy efficiency of the proposed monitoring system and the viability of using it to monitor WSN in real scenarios. PMID:24949639

  13. Failure Prevention of Hydraulic System Based on Oil Contamination

    NASA Astrophysics Data System (ADS)

    Singh, M.; Lathkar, G. S.; Basu, S. K.

    2012-07-01

    Oil contamination is the major source of failure and wear of hydraulic system components. As per literature survey, approximately 70 % of hydraulic system failures are caused by oil contamination. Hence, to operate the hydraulic system reliably, the hydraulic oil should be of perfect condition. This requires a proper `Contamination Management System' which involves monitoring of various parameters like oil viscosity, oil temperature, contamination level etc. A study has been carried out on vehicle mounted hydraulically operated system used for articulation of heavy article, after making the platform levelled with outrigger cylinders. It is observed that by proper monitoring of contamination level, there is considerably increase in reliability, economy in operation and long service life. This also prevents the frequent failure of hydraulic system.

  14. SOLERAS: Photovoltaic power systems project. Module failure analysis

    NASA Astrophysics Data System (ADS)

    Huraib, F. S.; Imamura, M. S.; Salim, A. A.; Rao, N.

    1984-10-01

    The SOLERAS Photovoltaic Power System (PVPS) became operational in September 1981. The system has operated satisfactorily and has experienced very little downtime. Early in 1983 some degradation in the photovoltaic (PV) field performance was detected. A series of current voltage (I-V) tests and other analyses eventually uncovered a number of PV modules that have resulted in open circuit type failure in the four cell group, or a half module. As of August 1984, the estimated number of these defective modules in the PV field was 152. In addition, there are a total of 188 defective modules in the storage warehouse, resulting in a total of 340 modules that need repairs. At the current rate of failures (seven half modules per month), an additional 112 modules would be defective by the end of January 1986, resulting in 412 defective modules. This report presents the results of the failure analysis performed during the past several months on the open circuit modules. Background information as related to the module failures and the effects of such failures on the overall PV field power output are provided. In addition, a plan to continue the monitoring of the rate of failure and analyzing the failure mechanisms is presented.

  15. The Rush to Remediate: Long Term Performance Favors Passive Systems at SRS

    SciTech Connect

    Hoffman, D.; Cauthen, K.; Beul. R. R.

    2003-02-24

    The purpose of this paper is to describe the long-term performance of groundwater remediation systems at SRS and compare active versus passive systems. The presentation will focus on the limited effectiveness of active pump and treat systems and share the experience with more passive and natural systems such as soil vapor extraction, barometric pumping, bioremediation, and phytoremediation. Three remediation projects are presented. In each case the waste source is capped with clay or synthetic barriers; however, extensive groundwater contamination remains. The first project features the cleanup of the largest plume in the United States. The second project entails solvent and vinyl chloride remediation of groundwater beneath a hazardous waste landfill. The third project discusses tritium containment from a 160-acre radioactive waste disposal area. Special emphasis is placed on performance data from alternate technology cleanup. The goals are to share remediation data, successes and lessons learned, while making a case for passive systems use in groundwater remediation.

  16. Failure management of multiple gimbal inertial systems for space shuttle

    NASA Technical Reports Server (NTRS)

    Dove, D. W.; Mckern, R. A.

    1973-01-01

    A failure detection and isolation technique for use with four gimbaled inertial measurement units (IMU) is presented. By using simulated boost and entry shuttle trajectories with specific gimbaled IMU models, failure detection thresholds are developed based on red-line life dependent requirements and warning thresholds within the red-line thresholds based on expected worst case IMU performance. Using these trajectories, established trajectory threshold, and multiple IMU models, various failure detection and isolation techniques are evaluated for application in both powered and unpowered flight phases. The adequacy of the systems for both attitude and velocity detection methods is evaluated and recommendations for space shuttle applications are made.

  17. Passive and Active Vibrations Allow Self-Organization in Large-Scale Electromechanical Systems

    NASA Astrophysics Data System (ADS)

    Buscarino, Arturo; Fortuna, Carlo Famoso Luigi; Frasca, Mattia

    2016-06-01

    In this paper, the role of passive and active vibrations for the control of nonlinear large-scale electromechanical systems is investigated. The mathematical model of the system is discussed and detailed experimental results are shown in order to prove that coupling the effects of feedback and vibrations elicited by proper control signals makes possible to regularize imperfect uncertain large-scale systems.

  18. Active-passive hybrid piezoelectric actuators for high-precision hard disk drive servo systems

    NASA Astrophysics Data System (ADS)

    Chan, Kwong Wah; Liao, Wei-Hsin

    2006-03-01

    Positioning precision is crucial to today's increasingly high-speed, high-capacity, high data density, and miniaturized hard disk drives (HDDs). The demand for higher bandwidth servo systems that can quickly and precisely position the read/write head on a high track density becomes more pressing. Recently, the idea of applying dual-stage actuators to track servo systems has been studied. The push-pull piezoelectric actuated devices have been developed as micro actuators for fine and fast positioning, while the voice coil motor functions as a large but coarse seeking. However, the current dual-stage actuator design uses piezoelectric patches only without passive damping. In this paper, we propose a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators. The proposed actuators will improve the existing dual-stage actuators for higher precision and shock resistance, due to the incorporation of passive damping in the design. We aim to develop this hybrid servo system not only to increase speed of track seeking but also to improve precision of track following servos in HDDs. New piezoelectrically actuated suspensions with passive damping have been designed and fabricated. In order to evaluate positioning and track following performances for the dual-stage track servo systems, experimental efforts are carried out to implement the synthesized active-passive suspension structure with enhanced piezoelectric actuators using a composite nonlinear feedback controller.

  19. Building a modular robot control system using passivity and scattering theory

    SciTech Connect

    Anderson, R.J.

    1996-03-01

    This paper analyses the problems and presents solutions for building a modular robot control system. The approach requires modeling the entire robot system using multi-dimensional passive networks, breaking the system into subnetwork ``modules,`` and then discretizing the subnetworks, or n-ports, in a passivity preserving fashion. The main difficulty is the existence of ``algebraic loops`` in the discretized system. This problem is overcome by the use of scattering theory, whereby the inputs and outputs of the n-ports are mapped into wave variables before being discretized. By first segmenting the n-ports into nonlinear memoryless subnetworks and linear dynamic subnetworks and then discretizing using passivity preserving techniques such as Tustin`s method, a complete modular robot control solution is obtained.

  20. Self-powered semi-passive vibration damping system based on self-sensing approach

    NASA Astrophysics Data System (ADS)

    Shen, Hui; Zhang, Fengsheng; Ji, Hongli; Qiu, Jinhao; Bian, Yixiang

    2016-01-01

    In recent years, semi-passive vibration damping using Synchronized Switching Damping on Inductor (SSDI) technique has been intensively investigated. In this paper, a self-powered semi-passive vibration damping system based on self sensing approach is proposed and investigated. With the self-sensing technique, the same piezoelectric element can be used as a sensor and an actuator. Compared with the other self-powered SSDI approaches, this technique can not only detect switching time without lag, but also reduce the number of piezoelectric elements. Furthermore, a low-power circuit for semi-passive piezoelectric vibration control based on self-sensing technique is designed. Experimental results demonstrate that the self-sensing SSDI system has good damping performance. The performance of the self-sensing SSDI system is also compared with the externally powered system.

  1. Passive-type rehabilitation systems for upper limbs with MR fluid brake and its training software.

    PubMed

    Haraguchi, Makoto; Furusho, Junji

    2013-01-01

    It is important to construct rehabilitation system for elderly people, people who have suffered strokes, and so on. In recent years, the need for rehabilitation support systems is increasing that using force display devices. When using force display systems, it is most important to ensure safety mechanically in order to prevent operators from hurting. Conventional force display systems are active-type devices with actuators but these devices may become dangerous when going out of control. On the other hand, passive-type force display devices with only passive elements are thought to be an effective method for assuring inherent safety. In this paper, we evaluate force display ability about a 2-D passive-type force display device with fast-response MR (Magneto-Rheological) fluid brakes to apply this device to rehabilitation training.

  2. Heart failure as an autonomic nervous system dysfunction.

    PubMed

    Kishi, Takuya

    2012-03-01

    In heart failure, it has been recognized that the sympathetic nervous system (SNS) is activated and the imbalance of the activity of the SNS and vagal activity interaction occurs. The abnormal activation of the SNS leads to further worsening of heart failure. Many previous clinical and basic studies have demonstrated that the abnormal activation of the SNS is caused by the enhancement of excitatory inputs including changes in: (1) peripheral baroreceptor and chemoreceptor reflexes; (2) chemical mediators that control sympathetic outflow; and (3) central sites that integrate sympathetic outflow. In particular, the abnormalities in central SNS regulation due to the renin angiotensin system-oxidative stress axis have recently been in focus. In the treatment of heart failure, the inhibition of the activated SNS, such as with beta-blockers and/or exercise training, is important. Furthermore, many experimental studies have demonstrated that vagal stimulation has beneficial effects on heart failure, and recently several clinical studies have also demonstrated that vagal stimulation is a possible novel therapy for heart failure. In conclusion, we must recognize that heart failure is a complex syndrome with an autonomic nervous system dysfunction, and that the autonomic imbalance with the activation of the SNS and the reduction of vagal activity should be treated. Copyright © 2012 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  3. Failure analysis and modeling of a VAXcluster system

    NASA Technical Reports Server (NTRS)

    Tang, Dong; Iyer, Ravishankar K.; Subramani, Sujatha S.

    1990-01-01

    This paper discusses the results of a measurement-based analysis of real error data collected from a DEC VAXcluster multicomputer system. In addition to evaluating basic system dependability characteristics such as error and failure distributions and hazard rates for both individual machines and for the VAXcluster, reward models were developed to analyze the impact of failures on the system as a whole. The results show that more than 46 percent of all failures were due to errors in shared resources. This is despite the fact that these errors have a recovery probability greater than 0.99. The hazard rate calculations show that not only errors, but also failures occur in bursts. Approximately 40 percent of all failures occur in bursts and involved multiple machines. This result indicates that correlated failures are significant. Analysis of rewards shows that software errors have the lowest reward (0.05 vs 0.74 for disk errors). The expected reward rate (reliability measure) of the VAXcluster drops to 0.5 in 18 hours for the 7-out-of-7 model and in 80 days for the 3-out-of-7 model.

  4. Very late follow-up of a passive defibrillator lead under recall: do failure rates increase during long-term observation.

    PubMed

    Frey, Simon Martin; Sticherling, Christian; Kraus, Regula; Ammann, Peter; Kühne, Michael; Osswald, Stefan; Schaer, Beat

    2015-03-01

    The Medtronic Sprint Fidelis lead (SFL; Medtronic Inc., Minneapolis, MN, USA) has a significantly impaired long-term survival, and active fixation leads fare worse than passive leads. The goal of this study was to present data of a series of passive SFL only with very long mean follow-up of more than 6 years. Patients in whom a passive SFL was implanted in two large Swiss centers were followed. We excluded eight (5.5%) patients with a follow-up of <6 months. Patients who died or were lost during follow-up were censored at death or last device check, all others on January 31, 2014. We employed two different definitions of failure: strict = fracture with inappropriate discharge; sudden increase in impedance >1,500 or high-voltage impedance >100 Ohm; >300 nonphysiological short interventricular-intervals. Lenient = any of the above plus a linear increase in impedance >1,500 Ohm or a linear decrease in sensing to a level that treating cardiologists considered inappropriate. We included 137 patients. Age was 60 ± 12 years. Mean and median follow-up were 6.2 ± 2.1 and 6.8 (interquartile range 4.8-7.8) years. Applying the strict definition, 12 leads (8.8%) were replaced after 4.9 ± 2.4 years (range 1.2-8.1). Applying the lenient definition, 14 leads (10.2%) failed. Cumulative lead survival was 98.5% at 3, 96.9% at 4, 94.2% at 5, and 93.1% at 6 years. Leads "at risk" were: n = 122 (89%), 115 (84%), 101 (74%), and 88 (64%). In this population with passive SFLs, 5-year lead survival is impaired with 94.2% based on 74% of leads "at risk" at this time point. ©2015 Wiley Periodicals, Inc.

  5. Understanding and Exploiting Spatial Properties of System Failures on Extreme-Scale HPC Systems

    SciTech Connect

    Rogers, James H; Maxwell, Don E

    2015-01-01

    As we approach exascale, the scientific simulations are expected to experience more interruptions due to increased system failures. Designing better HPC resilience techniques requires understanding the key characteristics of system failures on these systems. While temporal properties of system failures on HPC systems have been well-investigated, there is limited understanding about the spatial characteristics of system failures and its impact on the resilience mechanisms. Therefore, we examine the spatial characteristics and behavior of system failures. We investigate the interaction between spatial and temporal characteristics of failures and its implications for system operations and resilience mechanisms on large-scale HPC systems. We show that system failures have spatial locality at different granularity in the system; study impact of different failure-types; and investigate the correlation among different failure-types. Finally, we propose a novel scheme that exploits the spatial locality in failures to improve application and system performance. Our evaluation shows that the proposed scheme significantly improves the system performance in a dynamic and production-level HPC system.

  6. Failure Time Analysis of Office System Use.

    ERIC Educational Resources Information Center

    Cooper, Michael D.

    1991-01-01

    Develops mathematical models to characterize the probability of continued use of an integrated office automation system and tests these models on longitudinal data collected from 210 individuals using the IBM Professional Office System (PROFS) at the University of California at Berkeley. Analyses using survival functions and proportional hazard…

  7. Reaction control system helium pressure regulator filter failure

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The failure analysis of the command module reaction control system helium pressure regulators revealed that the filter element end caps were bulged by the helium pressure surge during activation. Some end caps may bulge and also some wire separation may occur during command module reaction control system activations; however, system performance should not be affected. The reaction control system design is acceptable and no change in hardware, system, or activation procedures is required.

  8. Evaluation of Fuzzy Rulemaking for Expert Systems for Failure Detection

    NASA Technical Reports Server (NTRS)

    Laritz, F.; Sheridan, T. B.

    1984-01-01

    Computer aids in expert systems were proposed to diagnose failures in complex systems. It is shown that the fuzzy set theory of Zadeh offers a new perspective for modeling for humans thinking and language use. It is assumed that real expert human operators of aircraft, power plants and other systems do not think of their control tasks or failure diagnosis tasks in terms of control laws in differential equation form, but rather keep in mind a set of rules of thumb in fuzzy form. Fuzzy set experiments are described.

  9. Failure modes and effects analysis of fusion magnet systems

    SciTech Connect

    Zimmermann, M; Kazimi, M S; Siu, N O; Thome, R J

    1988-12-01

    A failure modes and consequence analysis of fusion magnet system is an important contributor towards enhancing the design by improving the reliability and reducing the risk associated with the operation of magnet systems. In the first part of this study, a failure mode analysis of a superconducting magnet system is performed. Building on the functional breakdown and the fault tree analysis of the Toroidal Field (TF) coils of the Next European Torus (NET), several subsystem levels are added and an overview of potential sources of failures in a magnet system is provided. The failure analysis is extended to the Poloidal Field (PF) magnet system. Furthermore, an extensive analysis of interactions within the fusion device caused by the operation of the PF magnets is presented in the form of an Interaction Matrix. A number of these interactions may have significant consequences for the TF magnet system particularly interactions triggered by electrical failures in the PF magnet system. In the second part of this study, two basic categories of electrical failures in the PF magnet system are examined: short circuits between the terminals of external PF coils, and faults with a constant voltage applied at external PF coil terminals. An electromagnetic model of the Compact Ignition Tokamak (CIT) is used to examine the mechanical load conditions for the PF and the TF coils resulting from these fault scenarios. It is found that shorts do not pose large threats to the PF coils. Also, the type of plasma disruption has little impact on the net forces on the PF and the TF coils. 39 refs., 30 figs., 12 tabs.

  10. Triplexer Monitor Design for Failure Detection in FTTH System

    NASA Astrophysics Data System (ADS)

    Fu, Minglei; Le, Zichun; Hu, Jinhua; Fei, Xia

    2012-09-01

    Triplexer was one of the key components in FTTH systems, which employed an analog overlay channel for video broadcasting in addition to bidirectional digital transmission. To enhance the survivability of triplexer as well as the robustness of FTTH system, a multi-ports device named triplexer monitor was designed and realized, by which failures at triplexer ports can be detected and localized. Triplexer monitor was composed of integrated circuits and its four input ports were connected with the beam splitter whose power division ratio was 95∶5. By means of detecting the sampled optical signal from the beam splitters, triplexer monitor tracked the status of the four ports in triplexer (e.g. 1310 nm, 1490 nm, 1550 nm and com ports). In this paper, the operation scenario of the triplexer monitor with external optical devices was addressed. And the integrated circuit structure of the triplexer monitor was also given. Furthermore, a failure localization algorithm was proposed, which based on the state transition diagram. In order to measure the failure detection and localization time under the circumstance of different failed ports, an experimental test-bed was built. Experiment results showed that the detection time for the failure at 1310 nm port by the triplexer monitor was less than 8.20 ms. For the failure at 1490 nm or 1550 nm port it was less than 8.20 ms and for the failure at com port it was less than 7.20 ms.

  11. Passivity-based adaptive hybrid synchronization of a new hyperchaotic system with uncertain parameters.

    PubMed

    Zhou, Xiaobing; Fan, Zhangbiao; Zhou, Dongming; Cai, Xiaomei

    2012-01-01

    We investigate the adaptive hybrid synchronization problem for a new hyperchaotic system with uncertain parameters. Based on the passivity theory and the adaptive control theory, corresponding controllers and parameter estimation update laws are proposed to achieve hybrid synchronization between two identical uncertain hyperchaotic systems with different initial values, respectively. Numerical simulation indicates that the presented methods work effectively.

  12. A New Ultra-low Frequency Passive Vertical Vibration Isolation System

    NASA Astrophysics Data System (ADS)

    Zhao, Peng-Fei; Huang, Yu-Ying; Tang, Meng-Xi

    2002-02-01

    A new ultra-low frequency passive vertical vibration isolation system is constructed by connecting the torsion spring isolator with a reverse pendulum. The theoretical analysis shows that the new system can achieve a much longer resonant period and have a smaller size than the current torsion spring isolators with the same geometric parameters.

  13. Passivity-Based Adaptive Hybrid Synchronization of a New Hyperchaotic System with Uncertain Parameters

    PubMed Central

    2012-01-01

    We investigate the adaptive hybrid synchronization problem for a new hyperchaotic system with uncertain parameters. Based on the passivity theory and the adaptive control theory, corresponding controllers and parameter estimation update laws are proposed to achieve hybrid synchronization between two identical uncertain hyperchaotic systems with different initial values, respectively. Numerical simulation indicates that the presented methods work effectively. PMID:23365538

  14. Measurement and Analysis of Failures in Computer Systems

    NASA Technical Reports Server (NTRS)

    Thakur, Anshuman

    1997-01-01

    This thesis presents a study of software failures spanning several different releases of Tandem's NonStop-UX operating system running on Tandem Integrity S2(TMR) systems. NonStop-UX is based on UNIX System V and is fully compliant with industry standards, such as the X/Open Portability Guide, the IEEE POSIX standards, and the System V Interface Definition (SVID) extensions. In addition to providing a general UNIX interface to the hardware, the operating system has built-in recovery mechanisms and audit routines that check the consistency of the kernel data structures. The analysis is based on data on software failures and repairs collected from Tandem's product report (TPR) logs for a period exceeding three years. A TPR log is created when a customer or an internal developer observes a failure in a Tandem Integrity system. This study concentrates primarily on those TPRs that report a UNIX panic that subsequently crashes the system. Approximately 200 of the TPRs fall into this category. Approximately 50% of the failures reported are from field systems, and the rest are from the testing and development sites. It has been observed by Tandem developers that fewer cases are encountered from the field than from the test centers. Thus, the data selection mechanism has introduced a slight skew.

  15. Measurement and Analysis of Failures in Computer Systems

    NASA Technical Reports Server (NTRS)

    Thakur, Anshuman

    1997-01-01

    This thesis presents a study of software failures spanning several different releases of Tandem's NonStop-UX operating system running on Tandem Integrity S2(TMR) systems. NonStop-UX is based on UNIX System V and is fully compliant with industry standards, such as the X/Open Portability Guide, the IEEE POSIX standards, and the System V Interface Definition (SVID) extensions. In addition to providing a general UNIX interface to the hardware, the operating system has built-in recovery mechanisms and audit routines that check the consistency of the kernel data structures. The analysis is based on data on software failures and repairs collected from Tandem's product report (TPR) logs for a period exceeding three years. A TPR log is created when a customer or an internal developer observes a failure in a Tandem Integrity system. This study concentrates primarily on those TPRs that report a UNIX panic that subsequently crashes the system. Approximately 200 of the TPRs fall into this category. Approximately 50% of the failures reported are from field systems, and the rest are from the testing and development sites. It has been observed by Tandem developers that fewer cases are encountered from the field than from the test centers. Thus, the data selection mechanism has introduced a slight skew.

  16. Visualizing failure effects in complex human-machine systems

    NASA Astrophysics Data System (ADS)

    Price, Jana M.; Mathur, Amit; Morley, Rebecca M.; Scalzo, Richard C.

    2001-07-01

    The ability to understand a system's behavior in both normal and failed conditions is fundamental to the design of error-tolerant systems as well as to the development of diagnostics. The System Analysis for Failure and Error Reduction (SAFER) Project seeks to provide designers with tools to visualize potential sources of error and their effects early in the design of human-machine systems. The project is based on an existing technology that provides a failure-space modeling environment, analysis capabilities for troubleshooting, and error diagnostics using design data of machine systems. The SAFER Project extends the functionality of the existing technology in two significant ways. First, by adding a model of human error probability within the tool, designers are able to estimate the probabilities of human errors and the effects that these errors may have on system components and on the entire system. Second, the visual presentation of failure-related measures and metrics has been improved through a process of user-centered design. This paper will describe the process that was used to develop the human error probability model and will present novel metrics for assessing failure within complex systems.

  17. A passive microfluidic fragmentation system for continuous fluid-particles separation

    NASA Astrophysics Data System (ADS)

    Viana, A.; Marchalot, J.; Fouillet, Y.; Digianantonio, L.; Claustre, P.; Cubizolles, M.; Achard, JL.

    2013-05-01

    We present herein a microfluidic system based on passive effects for continuously separate a diphasic fluid-particles flow. Initially developed as a portable blood fragmentation device, its ability to operate passively, on several kinds of objects - organic or inorganic - opens the way to environmental applications, such as water cleaning or analysis. This technology can be implemented as a SamplePrep system, first step of an on-site analysis protocol. In addition, its low-cost and reliable manufacturing, compact size, low weight and ease of use make this technology a possible support for the deployment of health policies in developing countries.

  18. Survivable wavelength-division multiplexing passive optical network system with centralized protection routing scheme and efficient wavelength utilization

    NASA Astrophysics Data System (ADS)

    Zhou, Zhao; Xiao, Shilin; Bi, Meihua; Qi, Tao; Li, Pingqing; Hu, Weisheng

    2013-09-01

    A survivable wavelength-division multiplexing passive optical network (WDM-PON) with centralized protection scheme and colorless optical network units is proposed. The sideband channels generated via optical carrier suppression technique are used to carry both the downstream (DS) and the upstream (US) remodulated signals for two neighboring sub-PONs. By employing alternate path routing of sideband channels, the centralized protection scheme can provide reliable protection against any failure in feed fibers, remote node, and distribution fibers. The number of extra fibers is greatly reduced, and efficient utilization of wavelength resource is achieved. The feasibility of the proposed system is verified by 10-Gb/s DS and 1.25-Gb/s US signals over 25-km single-mode fiber transmission in both working and protection modes.

  19. Factors in Management Information System Failures.

    DTIC Science & Technology

    1980-12-08

    information system project. Several areas are examined, including: (1) technology, (2) the human resource, (3) monetary allocations, and (4) the...This report surveys current literature (1970 - 1980) on factors that can adversely affect the successful completion and execution of a management

  20. Velocity Estimate Following Air Data System Failure

    DTIC Science & Technology

    2008-03-01

    Latt , Long, Altitude) Velocity (North, East, Down) Attitude (Roll, Pitch, Yaw) Body Accelerations (Nx, Ny, Nz) Body Rates (p, q, r...algorithm; however, this would be less of an issue with modern fighter aircraft which have state-of-the- art INS systems (something the Learjet did not have

  1. Computer system failure: planning disaster recovery.

    PubMed

    Poker, A M

    1996-07-01

    A disaster recovery plan (DRP) defines the scope of restoration, establishes responsibilities and lists specific actions to be taken after the disaster. Although not actually involved in a DRP or computer systems, nurse managers must understand the steps involved and identify and communicate nursing's requirements.

  2. Active-passive vibration absorber of beam-cart-seesaw system with piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Lin, J.; Huang, C. J.; Chang, Julian; Wang, S.-W.

    2010-09-01

    In contrast with fully controllable systems, a super articulated mechanical system (SAMS) is a controlled underactuated mechanical system in which the dimensions of the configuration space exceed the dimensions of the control input space. The objectives of the research are to develop a novel SAMS model which is called beam-cart-seesaw system, and renovate a novel approach for achieving a high performance active-passive piezoelectric vibration absorber for such system. The system consists of two mobile carts, which are coupled via rack and pinion mechanics to two parallel tracks mounted on pneumatic rodless cylinders. One cart carries an elastic beam, and the other cart acts as a counterbalance. One adjustable counterweight mass is also installed underneath the seesaw to serve as a passive damping mechanism to absorb impact and shock energy. The motion and control of a Bernoulli-Euler beam subjected to the modified cart/seesaw system are analyzed first. Moreover, gray relational grade is utilized to investigate the sensitivity of tuning the active proportional-integral-derivative (PID) controller to achieve desired vibration suppression performance. Consequently, it is shown that the active-passive vibration absorber can not only provide passive damping, but can also enhance the active action authority. The proposed software/hardware platform can also be profitable for the standardization of laboratory equipment, as well as for the development of entertainment tools.

  3. Number and placement of control system components considering possible failures

    NASA Technical Reports Server (NTRS)

    Carignan, C. R.; Vandervelde, W. E.

    1982-01-01

    A decision making methodology is presented which is intended to be useful in the early stages of system design, before a control system is designed in detail. The methodology accounts for the likelihood of failure among the sensors and actuators in a control system. A method to compute the degree of controllability and degree of observability of a system for a given set of actuators and sensors is also presented.

  4. Passive perception system for day/night autonomous off-road navigation

    NASA Astrophysics Data System (ADS)

    Rankin, Arturo L.; Bergh, Charles F.; Goldberg, Steven B.; Bellutta, Paolo; Huertas, Andres; Matthies, Larry H.

    2005-05-01

    Passive perception of terrain features is a vital requirement for military related unmanned autonomous vehicle operations, especially under electromagnetic signature management conditions. As a member of Team Raptor, the Jet Propulsion Laboratory developed a self-contained passive perception system under the DARPA funded PerceptOR program. An environmentally protected forward-looking sensor head was designed and fabricated in-house to straddle an off-the-shelf pan-tilt unit. The sensor head contained three color cameras for multi-baseline daytime stereo ranging, a pair of cooled mid-wave infrared cameras for nighttime stereo ranging, and supporting electronics to synchronize captured imagery. Narrow-baseline stereo provided improved range data density in cluttered terrain, while wide-baseline stereo provided more accurate ranging for operation at higher speeds in relatively open areas. The passive perception system processed stereo images and outputted over a local area network terrain maps containing elevation, terrain type, and detected hazards. A novel software architecture was designed and implemented to distribute the data processing on a 533MHz quad 7410 PowerPC single board computer under the VxWorks real-time operating system. This architecture, which is general enough to operate on N processors, has been subsequently tested on Pentium-based processors under Windows and Linux, and a Sparc based-processor under Unix. The passive perception system was operated during FY04 PerceptOR program evaluations at Fort A. P. Hill, Virginia, and Yuma Proving Ground, Arizona. This paper discusses the Team Raptor passive perception system hardware and software design, implementation, and performance, and describes a road map to faster and improved passive perception.

  5. Prevention of mechanical failures in implanted spinal cord stimulation systems.

    PubMed

    Henderson, Jaimie M; Schade, C M; Sasaki, John; Caraway, David L; Oakley, John C

    2006-07-01

    Introduction.  Spinal cord stimulation (SCS) is an effective procedure for the treatment of neuropathic extremity pain, with success rates approaching 70%. However, mechanical failures, including breakage and migration, can significantly limit the long-term effectiveness of SCS. A systematic analysis of surgical techniques was undertaken by a consensus group, coupled with extensive in vivo and in vitro biomechanical testing of system components. Methods.  A computer model based on morphometric data was used to predict movement in a standard SCS system between an anchored lead and pulse generator placed in various locations. These displacements were then used to determine a realistic range of forces exerted on components of the SCS system. Laboratory fixtures were constructed to subject leads and anchors to repetitive stresses until failure occurred. An in vivo sheep model also was used to determine system compliances and failure thresholds in a biologically realistic setting. A panel of experienced implanters then interpreted the results and related them to clinical observations. Results.  Use of a soft silastic anchor pushed through the fascia to provide a larger bend radius for the lead was associated with a time to failure 65 times longer than an anchored but unsupported lead. In addition, failures of surgical paddle leads occurred when used with an anchor, whereas without an anchor, no failures occurred to 1 million cycles. Based on these findings, the panel recommended a paramedian approach, abdominal pulse generator placement, maximizing bend radius by pushing the anchor through the fascia, and anchoring of the extension connector near the lead anchor. Discussion.  Several factors are important in longevity of SCS systems. We discovered that technical factors can make a large difference in SCS reliability and that strict attention to these "best practices" will provide the best chance for maintaining the integrity of SCS systems over the long term.

  6. Vasopressors induce passive pulmonary hypertension by blood redistribution from systemic to pulmonary circulation.

    PubMed

    Jiang, Chunling; Qian, Hong; Luo, Shuhua; Lin, Jing; Yu, Jerry; Li, Yajiao; An, Qi; Luo, Nanfu; Du, Lei

    2017-05-01

    Vasopressors are widely used in resuscitation, ventricular failure, and sepsis, and often induce pulmonary hypertension with undefined mechanisms. We hypothesize that vasopressor-induced pulmonary hypertension is caused by increased pulmonary blood volume and tested this hypothesis in dogs under general anesthesia. In normal hearts (model 1), phenylephrine (2.5 μg/kg/min) transiently increased right but decreased left cardiac output, associated with increased pulmonary blood volume (63% ± 11.8, P = 0.007) and pressures in the left atrium, pulmonary capillary, and pulmonary artery. However, the trans-pulmonary gradient and pulmonary vascular resistance remained stable. These changes were absent after decreasing blood volume or during right cardiac dysfunction to reduce pulmonary blood volume (model 2). During double-ventricle bypass (model 3), phenylephrine (1, 2.5 and 10 μg/kg/min) only slightly induced pulmonary vasoconstriction. Vasopressin (1U and 2U) dose-dependently increased pulmonary artery pressure (52 ± 8.4 and 71 ± 10.3%), but did not cause pulmonary vasoconstriction in normally beating hearts (model 1). Pulmonary artery and left atrial pressures increased during left ventricle dysfunction (model 4), and further increased after phenylephrine injection by 31 ± 5.6 and 43 ± 7.5%, respectively. In conclusion, vasopressors increased blood volume in the lung with minimal pulmonary vasoconstriction. Thus, this pulmonary hypertension is similar to the hemodynamic pattern observed in left heart diseases and is passive, due to redistribution of blood from systemic to pulmonary circulation. Understanding the underlying mechanisms may improve clinical management of patients who are taking vasopressors, especially those with coexisting heart disease.

  7. Failure mode analysis of a spacecraft power system

    SciTech Connect

    Lee, J.R.

    1995-12-31

    For the spacecraft power system`s dynamic analyses, dc/dc converters are usually modeled with a linearized model using the state space averaging technique. The linearized model can be used for small-signal ac and transient analyses. However, since the linearized model has limitations in its accuracies, certain types of transient analyses including a failure mode must be performed by using a more accurate cycle-by-cycle model. In this paper, a failure mode analysis is presented with a small-signal analysis and corresponding transient simulations.

  8. DoD Should Give More Consideration to Passive Solar Systems for New Military Family Housing.

    DTIC Science & Technology

    1982-05-17

    these evaluations appeared to pro- vide reasonable estimates of the economic viability of each system considered and were prepared in accordance...reasonable estimates of the economic viability of each system and were prepared in accordance with appropriate guidelines and criteria. With respect...cycle costing criteria that DOD must use in evaluating solar systems for military family housing. Although the economic viability of passive systems

  9. Westinghouse Small Modular Reactor passive safety system response to postulated events

    SciTech Connect

    Smith, M. C.; Wright, R. F.

    2012-07-01

    The Westinghouse Small Modular Reactor (SMR) is an 800 MWt (>225 MWe) integral pressurized water reactor. This paper is part of a series of four describing the design and safety features of the Westinghouse SMR. This paper focuses in particular upon the passive safety features and the safety system response of the Westinghouse SMR. The Westinghouse SMR design incorporates many features to minimize the effects of, and in some cases eliminates the possibility of postulated accidents. The small size of the reactor and the low power density limits the potential consequences of an accident relative to a large plant. The integral design eliminates large loop piping, which significantly reduces the flow area of postulated loss of coolant accidents (LOCAs). The Westinghouse SMR containment is a high-pressure, compact design that normally operates at a partial vacuum. This facilitates heat removal from the containment during LOCA events. The containment is submerged in water which also aides the heat removal and provides an additional radionuclide filter. The Westinghouse SMR safety system design is passive, is based largely on the passive safety systems used in the AP1000{sup R} reactor, and provides mitigation of all design basis accidents without the need for AC electrical power for a period of seven days. Frequent faults, such as reactivity insertion events and loss of power events, are protected by first shutting down the nuclear reaction by inserting control rods, then providing cold, borated water through a passive, buoyancy-driven flow. Decay heat removal is provided using a layered approach that includes the passive removal of heat by the steam drum and independent passive heat removal system that transfers heat from the primary system to the environment. Less frequent faults such as loss of coolant accidents are mitigated by passive injection of a large quantity of water that is readily available inside containment. An automatic depressurization system is used to

  10. Exponential passivity for output feedback stabilisation of nonlinear uncertain systems

    NASA Astrophysics Data System (ADS)

    Benabdallah, Amel

    2010-11-01

    In this article, we address the problem of stabilisation by output feedback for a class of uncertain systems. We consider uncertain systems with a nominal part which is affine in the control and an uncertain part which is norm bounded by a known function. We propose an output feedback such that the closed loop system is globally exponentially stable.

  11. Study of passive fuel tank inerting systems for ground combat vehicles

    NASA Astrophysics Data System (ADS)

    McCormick, Steven J.; Motzenbecker, Peter F.; Clauson, Michael J.

    1988-09-01

    Many flammable materials are carried aboard combat vehicles, including fuel, hydraulic fluid, and munitions. A fire involving any of these can lead to destruction of the vehicle and injury to the crew. Ground combat vehicles have relied on fire extinguishing systems to protect the vehicles and crew, while aircraft use passive inerting techniques as well as fire extinguishing systems. The apparent disparity between ground combat vehicles and aircraft has caused the U.S. Congress to direct the Secretary of the Army to examine the use of passive, multiple-hit, fuel tank inerting systems in tracked and wheeled vehicles. This report examines passive fuel tank inerting techniques and provides an assessment of their applicability to ground combat vehicles. The extent of the hazard posed by the combat vehicle fuel tanks has been defined. The adequacy of the technology in reducing this hazard is evaluated for each technique considered. The current technology for the suppression of fires in and from vehicle fuel tanks available to and in use by the armed services, other government agencies, the private sector, and foreign armed services has also been examined. Attention was restricted to passive systems (systems which do not require any mechanical or electrical activation) which can suppress multiple occurrences of fire. Both fuel tank fillers and systems which surround the fuel tanks were considered. A review of currently available passive fuel tank inerting technologies has shown that the majority of these techniques are not effective for ground combat vehicles considering the large antiarmor threats. A significant quantity of testing has been conducted which bears this out. An exception to this are fuel tank jackets which show great promise in improving ground combat fire survivability. Futher development work must be done before this approach can be integrated into production vehicles or retrofitted into fielded vehicles. Proper fuel system and vehicle design, in

  12. Program For Analyzing Failures In A Complex System

    NASA Technical Reports Server (NTRS)

    Mccluney, R. Kevin

    1995-01-01

    Configurable Real-Time Analysis System (CRANS) computer program provides means for representing logically interconnected items (e.g., modules of equipment in complicated system) in matrix format. Capabilities provided helpful in real-time environment (e.g., operational environment of such system), in which need for quick evaluation of results of changes or failures. Program facilitates rapid logic-tree analysis. Written in C language.

  13. Thermal System Verification and Model Validation for NASA's Cryogenic Passively Cooled James Webb Space Telescope (JWST)

    NASA Technical Reports Server (NTRS)

    Parrish, Keith; Cleveland, Paul E.; Glazer, Stu; Thompson, Shaun

    2005-01-01

    A thorough and unique thermal verification and model validation plan has been developed for NASA s James Webb Space Telescope. The JWST observatory consists of a large deployed aperture optical telescope passively cooled to below 50 Kelvin along with a suite of several instruments passively and actively cooled to below 37 Kelvin and 7 Kelvin, respectively. Passive cooling to these extremely low temperatures is made feasible by the use of a large deployed high efficiency sunshield and an orbit location a! !he L2 Lagrange pin!. Another enabling feature is the scale or size of the observatory that allows for large radiator sizes that are compatible with the expected power dissipation of the instruments and large format Mercury Cadmium Telluride (HgCdTe) detector arrays. This passive cooling concept is simple, reliable, and mission enabling when compared to the alternatives of mechanical coolers and stored cryogens. However, these same large scale observatory features, which make passive cooling viable, also prevent the typical flight configuration fully-deployed thermal balance test that is the keystone to most space missions thermal verification plan. JWST is simply too large in its deployed configuration to be properly thermal balance tested in the facilities that currently exist. This reality, when combined with a mission thermal concept with little to no flight heritage, has necessitated the need for a unique and alternative approach to thermal system verification and model validation. This paper describes the thermal verification and model validation plan that has been developed for JWST.

  14. Development of a Dehumidification System for a Passive Sampler for Determining 1,3-Butadiene.

    PubMed

    Sakurai, Kenji; Miyake, Yuichi; Amagai, Takashi

    2016-09-01

    The passive sampler is a simple device for collecting gaseous compounds. It is affected by environmental conditions such as relative humidity, but a dehumidification system (DHS) has not been developed for it. We have developed a dehumidification device for the passive sampler for determining 1,3-butadiene. It consists of a passive sampler surrounded by a DHS consisting of a basket filled with granular magnesium perchlorate as the dehumidification agent. The passive sampler consists of a porous polytetrafluoroethylene tube packed with Carboxen 1000 adsorbent. We compared the amounts of water adsorbed on the Carboxen 1000 adsorbent in the presence and in the absence of the DHS; the results showed that the DHS prevented water from entering the sampler. Volatile organic compounds that entered the sampler were collected by the Carboxen 1000 adsorbent. In the case of 1,3-butadiene, much higher amounts were collected by the passive sampler with the DHS than without it. This may be due to interference of adsorption or acceleration of 1,3-butadiene degradation by the water-soluble oxidant on the surface of the Carboxen 1000 adsorbent.

  15. Local-Level Prognostics Health Management Systems Framework for Passive AdvSMR Components. Interim Report

    SciTech Connect

    Ramuhalli, Pradeep; Roy, Surajit; Hirt, Evelyn H.; Pardini, Allan F.; Jones, Anthony M.; Deibler, John E.

    2014-09-12

    This report describes research results to date in support of the integration and demonstration of diagnostics technologies for prototypical AdvSMR passive components (to establish condition indices for monitoring) with model-based prognostics methods. The focus of the PHM methodology and algorithm development in this study is at the localized scale. Multiple localized measurements of material condition (using advanced nondestructive measurement methods), along with available measurements of the stressor environment, enhance the performance of localized diagnostics and prognostics of passive AdvSMR components and systems.

  16. The cognitive-behavioral system of leadership: cognitive antecedents of active and passive leadership behaviors

    PubMed Central

    Dóci, Edina; Stouten, Jeroen; Hofmans, Joeri

    2015-01-01

    In the present paper, we propose a cognitive-behavioral understanding of active and passive leadership. Building on core evaluations theory, we offer a model that explains the emergence of leaders’ active and passive behaviors, thereby predicting stable, inter-individual, as well as variable, intra-individual differences in both types of leadership behavior. We explain leaders’ stable behavioral tendencies by their fundamental beliefs about themselves, others, and the world (core evaluations), while their variable, momentary behaviors are explained by the leaders’ momentary appraisals of themselves, others, and the world (specific evaluations). By introducing interactions between the situation the leader enters, the leader’s beliefs, appraisals, and behavior, we propose a comprehensive system of cognitive mechanisms that underlie active and passive leadership behavior. PMID:26441721

  17. New PANDA Tests to Investigate Effects of Light Gases on Passive Safety Systems

    SciTech Connect

    Paladino, D.; Auban, O.; Candreia, P.; Huggenberger, M.; Strassberger, H.J.

    2002-07-01

    The large- scale thermal-hydraulic PANDA facility (located at PSI in Switzerland), has been used over the last few years for investigating different passive decay- heat removal systems and containment phenomena for the next generation of light water reactors (Simplified Boiling Water Reactor: SBWR; European Simplified Boiling Water Reactor: ESBWR; Siedewasserreaktor: SWR-1000). Currently, as part of the European Commission 5. EURATOM Framework Programme project 'Testing and Enhanced Modelling of Passive Evolutionary Systems Technology for Containment Cooling' (TEMPEST), a new series of tests is being planned in the PANDA facility to experimentally investigate the distribution of non-condensable gases inside the containment and their effect on the performance of the 'Passive Containment Cooling System' (PCCS). Hydrogen release caused by the metal-water reaction in the case of a postulated severe accident will be simulated in PANDA by injecting helium into the reactor pressure vessel. In order to provide suitable data for Computational Fluid Dynamic (CFD) code assessment and improvement, the instrumentation in PANDA has been upgraded for the new tests. In the present paper, a detailed discussion is given of the new PANDA tests to be performed to investigate the effects of light gas on passive safety systems. The tests are scheduled for the first half of the year 2002. (authors)

  18. ISS Expedition 18 Fluids and Combustion Facility (FCF) Combustion Integration Rack (CIR) Passive Rack Isolation System (

    NASA Image and Video Library

    2009-01-05

    ISS018-E-017796 (5 Jan. 2009) --- Astronaut Sandra Magnus, Expedition 18 flight engineer, works on the Fluids and Combustion Facility (FCF) Combustion Integration Rack (CIR) Passive Rack Isolation System (PaRIS) in the Destiny laboratory of the International Space Station.

  19. [Computer-aided implantology: Contribution of the Robodent(®) passive robotic system.

    PubMed

    Armand, S; Legac, O; Galibourg, A

    2013-08-02

    The use of the Robodent(®) passive robotic system improves the accuracy of implant placement and thus allows extending the field of indications for flapless surgical technique. Surgery can be performed with a greater operative safety and peroperative modification of the surgical protocol is possible.

  20. System design package: Maxi-therm S-101 heating module, passive heat exchanger

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This document is the specification which establishes the requirements for the design, installation, and performance of a passive heat exchanger module with auxiliary heaters for use with solar heating systems. It designates the Interim Performance Criteria applicable to the subsystem and defines any deviations. This document also includes the manufacturing instructions and required materials and parts for the Maxitherm S101 Heating Module.

  1. Passive system with tunable group velocity for propagating electrical pulses from sub- to superluminal velocities.

    PubMed

    Haché, Alain; Essiambre, Sophie

    2004-05-01

    We report an observation of tunable group velocity from sub-luminal to superluminal in a completely passive system. Electric pulses are sent along a spatially periodic conducting medium containing a punctual nonlinearity, and the resulting amplitude-dependent phase shift allows us to control dispersion and the propagation velocity at the stop band frequency.

  2. Optimization of Passive and Active Non-Linear Vibration Mounting Systems Based on Vibratory Power Transmission

    NASA Astrophysics Data System (ADS)

    Royston, T. J.; Singh, R.

    1996-07-01

    While significant non-linear behavior has been observed in many vibration mounting applications, most design studies are typically based on the concept of linear system theory in terms of force or motion transmissibility. In this paper, an improved analytical strategy is presented for the design optimization of complex, active of passive, non-linear mounting systems. This strategy is built upon the computational Galerkin method of weighted residuals, and incorporates order reduction and numerical continuation in an iterative optimization scheme. The overall dynamic characteristics of the mounting system are considered and vibratory power transmission is minimized via adjustment of mount parameters by using both passive and active means. The method is first applied through a computational example case to the optimization of basic passive and active, non-linear isolation configurations. It is found that either active control or intentionally introduced non-linearity can improve the mount's performance; but a combination of both produces the greatest benefit. Next, a novel experimental, active, non-linear isolation system is studied. The effect of non-linearity on vibratory power transmission and active control are assessed via experimental measurements and the enhanced Galerkin method. Results show how harmonic excitation can result in multiharmonic vibratory power transmission. The proposed optimization strategy offers designers some flexibility in utilizing both passive and active means in combination with linear and non-linear components for improved vibration mounts.

  3. Systems Biology Applied to Heart Failure With Normal Ejection Fraction

    PubMed Central

    Mesquita, Evandro Tinoco; Jorge, Antonio Jose Lagoeiro; de Souza, Celso Vale; Cassino, João Paulo Pedroza

    2014-01-01

    Heart failure with normal ejection fraction (HFNEF) is currently the most prevalent clinical phenotype of heart failure. However, the treatments available have shown no reduction in mortality so far. Advances in the omics sciences and techniques of high data processing used in molecular biology have enabled the development of an integrating approach to HFNEF based on systems biology. This study aimed at presenting a systems-biology-based HFNEF model using the bottom-up and top-down approaches. A literature search was conducted for studies published between 1991 and 2013 regarding HFNEF pathophysiology, its biomarkers and systems biology. A conceptual model was developed using bottom-up and top-down approaches of systems biology. The use of systems-biology approaches for HFNEF, a complex clinical syndrome, can be useful to better understand its pathophysiology and to discover new therapeutic targets. PMID:24918915

  4. Test system to simulate transient overpower LMFBR cladding failure

    SciTech Connect

    Barrus, H.G.; Feigenbutz, L.V.

    1981-01-14

    One of the HEDL programs has the objective to experimentally characterize fuel pin cladding failure due to cladding rupture or ripping. A new test system has been developed which simulates a transient mechanically-loaded fuel pin failure. In this new system the mechanical load is prototypic of a fuel pellet rapidly expanding against the cladding due to various causes such as fuel thermal expansion, fuel melting, and fuel swelling. This new test system is called the Fuel Cladding Mechanical Interaction Mandrel Loading Test (FCMI/MLT). The FCMI/MLT test system and the method used to rupture cladding specimens very rapidly to simulate a transient event are described. Also described is the automatic data acquisition and control system which is required to control the startup, operation and shutdown of the very fast tests, and needed to acquire and store large quantities of data in a short time.

  5. Key systemic and environmental risk factors for implant failure.

    PubMed

    Dawson, Dolphus R; Jasper, Samuel

    2015-01-01

    Dental implants are an important treatment option for patients interested in replacing lost or missing teeth. Although a robust body of literature has reviewed risk factors for tooth loss, the evidence for risk factors associated with dental implants is less well defined. This article focuses on key systemic risk factors relating to dental implant failure, as well as on perimucositis and peri-implantitis.

  6. 76 FR 51274 - Supplemental Nutrition Assistance Program: Major System Failures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-18

    ...; ] DEPARTMENT OF AGRICULTURE Food and Nutrition Service 7 CFR Parts 273 and 276 RIN 0584-AD98 Supplemental Nutrition Assistance Program: Major System Failures AGENCY: Food and Nutrition Service, USDA. ACTION: Proposed rule. SUMMARY: This rule proposes to amend Supplemental Nutrition Assistance Program (SNAP...

  7. Analysis of Search Failures in Document Retrieval Systems: A Review.

    ERIC Educational Resources Information Center

    Tonta, Yasar

    1992-01-01

    Discusses the concept of search failure in document retrieval systems and three effectiveness measures, precision, recall, and "fallout." Four research methods--retrieval effectiveness measures, user satisfaction measures, transaction log analysis, and critical incident technique--are examined, and findings of major studies using each of the…

  8. Syndromic surveillance for health information system failures: a feasibility study

    PubMed Central

    Ong, Mei-Sing; Magrabi, Farah; Coiera, Enrico

    2013-01-01

    Objective To explore the applicability of a syndromic surveillance method to the early detection of health information technology (HIT) system failures. Methods A syndromic surveillance system was developed to monitor a laboratory information system at a tertiary hospital. Four indices were monitored: (1) total laboratory records being created; (2) total records with missing results; (3) average serum potassium results; and (4) total duplicated tests on a patient. The goal was to detect HIT system failures causing: data loss at the record level; data loss at the field level; erroneous data; and unintended duplication of data. Time-series models of the indices were constructed, and statistical process control charts were used to detect unexpected behaviors. The ability of the models to detect HIT system failures was evaluated using simulated failures, each lasting for 24 h, with error rates ranging from 1% to 35%. Results In detecting data loss at the record level, the model achieved a sensitivity of 0.26 when the simulated error rate was 1%, while maintaining a specificity of 0.98. Detection performance improved with increasing error rates, achieving a perfect sensitivity when the error rate was 35%. In the detection of missing results, erroneous serum potassium results and unintended repetition of tests, perfect sensitivity was attained when the error rate was as small as 5%. Decreasing the error rate to 1% resulted in a drop in sensitivity to 0.65–0.85. Conclusions Syndromic surveillance methods can potentially be applied to monitor HIT systems, to facilitate the early detection of failures. PMID:23184193

  9. TECHNICAL BASIS DOCUMENT FOR VENTILATION SYSTEM FILTRATION FAILURE LEADING TO AN UNFILTERED RELEASE

    SciTech Connect

    KOZLOWSKI, S.D.

    2005-01-06

    This document analyzed three scenarios involving failures of HEPA filtration systems leading to releases from liquid waste tanks. The scenarios are failure due to high temperature (fire), overpressure (filter blowout), and unfiltered release due to filter failure, improper installation. etc.

  10. Technical basis document for ventilation system filtration failures leading to unfiltered release

    SciTech Connect

    HIMES, D.A.

    2003-03-22

    Three accident scenarios were analyzed involving failures of HEPA filtration systems leading to releases from liquid waste tanks. The scenarios are failure due to high temperature (fire), overpressure (filter blowout), and unfiltered release due to filter failure, improper installation, etc.

  11. Experimental study of a semi-passive ventilation grille with a feedback control system

    NASA Astrophysics Data System (ADS)

    D'Orazio, A.; Fontana, L.; Salata, F.

    2011-08-01

    The diffusion of window frames with low air permeability, due to the energy saving regulations, has implied in several cases the worsening of the indoor microclimate and air quality. On the other hand, air-tight window frames imply uncontrolled and too high air change rates. The mechanical ventilation not always is a practicable solution because of economic reasons and because it implies energy waste. Various Italian and European environmental and energetic laws take into consideration and promote the use of controlled natural ventilation, though this definition is not associated to well defined and tested technical solutions. An adequate solution can be achieved by using semi-passive self adjustable ventilation devices, able to ensure controlled changes of indoor air. In this paper, a semi-passive damper with a feedback control system is proposed and its behavior is investigated by means of experimental study. The presented semi-passive grille allows to control the air flow rate, injected into the room by natural or artificial pressure gradient, more effectively than the usual passive ventilation grilles made available by the present industrial production. However, since the semi-passive grille has a one-way flow, in the natural ventilation of a flat the proper functioning of the system could be ensured with a more complex configuration, with respect to the passive self-regulating grilles, able to limit the flow of fresh air in the presence of high levels of Δp; conversely, it could have widespread use in applications requiring a more accurate control of airflow in case of mechanical ventilation plants.

  12. Optimisation of concentrating solar cell systems with passive and active cooling

    NASA Astrophysics Data System (ADS)

    Blumenberg, J.

    This paper reports on solar cell systems with concentrating mirrors. With silicon-solar-cells, a concentration of the solar radiation is suitable only for missions far from the Sun. With gallium-ansenide solar-cells concentration is suitable by all means. Active cooling of solar cell systems with concentrated solar radiation does not result in improved optimum specific masses of the system against passive cooling.

  13. Combustion driven ammonia generation strategies for passive ammonia SCR system

    SciTech Connect

    Toner, Joel G.; Narayanaswamy, Kushal; Szekely, Jr., Gerald A.; Najt, Paul M.

    2016-12-06

    A method for controlling ammonia generation in an exhaust gas feedstream output from an internal combustion engine equipped with an exhaust aftertreatment system including a first aftertreatment device includes executing an ammonia generation cycle to generate ammonia on the first aftertreatment device. A desired air-fuel ratio output from the engine and entering the exhaust aftertreatment system conducive for generating ammonia on the first aftertreatment device is determined. Operation of a selected combination of a plurality of cylinders of the engine is selectively altered to achieve the desired air-fuel ratio entering the exhaust aftertreatment system.

  14. Techniques for Improving Pilot Recovery from System Failures

    NASA Technical Reports Server (NTRS)

    Pritchett, Amy R.

    2001-01-01

    This project examined the application of intelligent cockpit systems to aid air transport pilots at the tasks of reacting to in-flight system failures and of planning and then following a safe four dimensional trajectory to the runway threshold during emergencies. Two studies were conducted. The first examined pilot performance with a prototype awareness/alerting system in reacting to on-board system failures. In a full-motion, high-fidelity simulator, Army helicopter pilots were asked to fly a mission during which, without warning or briefing, 14 different failures were triggered at random times. Results suggest that the amount of information pilots require from such diagnostic systems is strongly dependent on their training; for failures they are commonly trained to react to with a procedural response, they needed only an indication of which failure to follow, while for 'un-trained' failures, they benefited from more intelligent and informative systems. Pilots were also found to over-rely on the system in conditions were it provided false or mis-leading information. In the second study, a proof-of-concept system was designed suitable for helping pilots replan their flights in emergency situations for quick, safe trajectory generation. This system is described in this report, including: the use of embedded fast-time simulation to predict the trajectory defined by a series of discrete actions; the models of aircraft and pilot dynamics required by the system; and the pilot interface. Then, results of a flight simulator evaluation with airline pilots are detailed. In 6 of 72 simulator runs, pilots were not able to establish a stable flight path on localizer and glideslope, suggesting a need for cockpit aids. However, results also suggest that, to be operationally feasible, such an aid must be capable of suggesting safe trajectories to the pilot; an aid that only verified plans entered by the pilot was found to have significantly detrimental effects on performance and

  15. Transverse-displacement stabilizer for passive magnetic bearing systems

    DOEpatents

    Post, Richard F

    2017-03-07

    The invention provides a way re-center a rotor's central longitudinal rotational axis with a desired system longitudinal axis. A pair of planar semicircular permanent magnets are pieced together to form a circle. The flux from each magnet is pointed in in opposite directions that are both parallel with the rotational axis. A stationary shorted circular winding the plane of which is perpendicular to the system longitudinal axis and the center of curvature of the circular winding is positioned on the system longitudinal axis. Upon rotation of the rotor, when a transverse displacement of the rotational axis occurs relative to the system longitudinal axis, the winding will experience a time-varying magnetic flux such that an alternating current that is proportional to the displacement will flow in the winding. Such time-varying magnetic flux will provide a force that will bring the rotor back to its centered position about the desired axis.

  16. Non-contacting "snubber bearing" for passive magnetic bearing systems

    DOEpatents

    Post, Richard F

    2017-08-22

    A new non-contacting magnetic "snubber" bearing is provided for application to rotating systems such as vehicular electromechanical battery systems subject to frequent accelerations. The design is such that in the equilibrium position the drag force of the snubber is very small (milliwatts). However in a typical case, if the rotor is displaced by as little as 2 millimeters a large restoring force is generated without any physical contact between the stationary and rotating parts of the snubber bearing.

  17. Involvement of systemic venous congestion in heart failure.

    PubMed

    Rubio Gracia, J; Sánchez Marteles, M; Pérez Calvo, J I

    2017-04-01

    Systemic venous congestion has gained significant importance in the interpretation of the pathophysiology of acute heart failure, especially in the development of renal function impairment during exacerbations. In this study, we review the concept, clinical characterisation and identification of venous congestion. We update current knowledge on its importance in the pathophysiology of acute heart failure and its involvement in the prognosis. We pay special attention to the relationship between abdominal congestion, the pulmonary interstitium as filtering membrane, inflammatory phenomena and renal function impairment in acute heart failure. Lastly, we review decongestion as a new therapeutic objective and the measures available for its assessment. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

  18. Systemic sarcoidosis complicated of acute renal failure: about 12 cases.

    PubMed

    Mahfoudhi, Madiha; Mamlouk, Habiba; Turki, Sami; Kheder, Adel

    2015-01-01

    The sarcoidosis is a systemic granulomatosis affecting most frequently the lungs and the mediastinum. An acute renal failure reveals exceptionally this disease. It's a retrospective study implicating 12 cases of sarcoidosis complicated of acute renal failure. The aim of this study is to determine epidemiological, clinical, biological and histological profile in these cases and then to indicate the interest to consider the diagnosis of sarcoidosis in cases of unexplained renal failure. Extra-renal complications, therapeutic modalities and the outcome were determined in all patients. Our series involved 12 women with an average age of 40 years. Biological investigations showed an abnormal normocalcemia in 7 cases, a hypercalcemia in 5 cases, a hypercalciuria in 10 cases and polyclonal hypergammaglobulinemia in 7 cases. An acute renal failure was found in all patients with a median creatinin of 520 umol/L. For all patients, the renal echography was normal however, the kidney biopsy showed tubulo-interstitial nephritis. The extra-renal signs highlighting pulmonary interstitial syndrome in 5 cases, a sicca syndrome in 4 cases, mediastinal lymph nodes in 2 cases, a lymphocytic alveolitis in 3 cases, an anterior granulomatous uveitis in 2 cases and a polyarthritis in 5 cases. Five patients benefited of hemodialysis. The treatment consisted of corticosteroid in all cases. The follow up was marked by complete resolution of clinical and biological signs. The diagnosis of renal sarcoidosis must be done quickly to prevent renal failure.

  19. Rocket engine failure detection using system identification techniques

    NASA Technical Reports Server (NTRS)

    Meyer, Claudia M.; Zakrajsek, June F.

    1990-01-01

    The theoretical foundation and application of two univariate failure detection algorithms to Space Shuttle Main Engine (SSME) test firing data is presented. Both algorithms were applied to data collected during steady state operation of the engine. One algorithm, the time series algorithm, is based on time series techniques and involves the computation of autoregressive models. Time series techniques have been previously applied to SSME data. The second algorithm is based on standard signal processing techniques. It consists of tracking the variations in the average signal power with time. The average signal power algorithm is a newly proposed SSME failure detection algorithm. Seven nominal test firings were used to develop failure indication thresholds for each algorithm. These thresholds were tested using four anomalous firings and one additional nominal firing. Both algorithms provided significantly earlier failure indication times than did the current redline limit system. Neither algorithm gave false failure indications for the nominal firing. The strengths and weaknesses of the two algorithms are discussed and compared. The average signal algorithm was found to have several advantages over the time series algorithm.

  20. Rocket engine failure detection using system identification techiques

    NASA Technical Reports Server (NTRS)

    Meyer, Claudia M.; Zakrajsek, June F.

    1990-01-01

    The theoretical foundation and application of two univariate failure detection algorithms to Space Shuttle Main Engine (SSME) test firing data is presented. Both algorithms were applied to data collected during steady state operation of the engine. One algorithm, the time series algorithm, is based on time series techniques and involves the computation of autoregressive models. Times series techniques have been previously applied to SSME data. The second algorithm is based on standard signal processing techniques. It consists of tracking the variations in the average signal power with time. The average signal power algorithm is a newly proposed SSME failure detection algorithm. Seven nominal test firings were used to develop failure indication thresholds for each algorithm. These thresholds were tested using four anomalous firings and one additional nominal firing. Both algorithms provided significantly earlier failure indication times than did the current redline limit system. Neither algorithm gave false failure indications for the nominal firing. The strengths and weaknesses of the two algorithms are discussed and compared. The average signal algorithm was found to have several advantages over the time series algorithm.

  1. Study on development of active-passive rehabilitation system for upper limbs: Hybrid-PLEMO

    NASA Astrophysics Data System (ADS)

    Kikuchi, T.; Jin, Y.; Fukushima, K.; Akai, H.; Furusho, J.

    2009-02-01

    In recent years, many researchers have studied the potential of using robotics technology to assist and quantify the motor functions for neuron-rehabilitation. Some kinds of haptic devices have been developed and evaluated its efficiency with clinical tests, for example, upper limb training for patients with spasticity after stroke. Active-type (motor-driven) haptic devices can realize a lot of varieties of haptics. But they basically require high-cost safety system. On the other hand, passive-type (brake-based) haptic devices have inherent safety. However, the passive robot system has strong limitation on varieties of haptics. There are not sufficient evidences to clarify how the passive/active haptics effect to the rehabilitation of motor skills. In this paper, we developed an active-passive-switchable rehabilitation system with ER clutch/brake device named "Hybrid-PLEMO" in order to address these problems. In this paper, basic structures and haptic control methods of the Hybrid-PLEMO are described.

  2. Design and performance of a passive video-rate THz system demonstrator

    NASA Astrophysics Data System (ADS)

    Luukanen, A.; Aikio, M.; Grönholm, M.; Leivo, M. M.; Mäyrä, A.; Rautiainen, A.; Toivanen, H.

    2011-05-01

    In this paper we given an overview of the design and predicted performance of a passive video-rate THz camera intended for stand-off and walk-by concealed weapons and explosives detection. The system is based on previously reported work, and it utilizes a linear array of superconducting antenna-coupled microbolometers. Our present efforts have focussed on improving the performance, stability, set-up time and cost of production of the camera. The system is designed to acquire near video frame rate (~10 Hz) passive THz imagery of objects at ~5 meters from the system, with a field-of-view of 2 m x 1 m and a spatial resolution of 1 cm. The system will be readily integrated to other security systems as it provides encrypted stream of THz imagery over conventional LAN interface that also allows for remote operation.

  3. Penstock failure detection system at the "Valsan" hydro power plant

    NASA Astrophysics Data System (ADS)

    Georgescu, A. M.; Coşoiu, C. I.; Alboiu, N.; Hlevca, D.; Tataroiu, R.; Popescu, O.

    2012-11-01

    "Valsan" is a small Hydro Power Plant, 5 MW, situated at about 160 km north of Bucharest, Romania, on the small "Valsan" river in a remote mountainous area. It is equipped with a single Francis turbine. The penstock is located in the access shaft of the HPP. "Hidroelectrica", the Romanian company that operates the HPP, was trying to implement a remote penstock failure detection system. Starting from a classic hydraulic problem, the authors of the paper derived a method for failure detection and localization on the pipe. The method assumes the existence of 2 flow meters and 2 pressure transducers at the inlet and outlet of the pressurized pipe. Calculations have to be based on experimental values measured in a permanent regime for different values of the flow rate. The method was at first tested on a pipe, in the Hydraulic Laboratory of the Technical University of Civil Engineering Bucharest. Pipe failure was modelled by opening of a valve on a tee branch of the analyzed pipe. Experimental results were found to be in good agreement with theoretical ones. The penstock of the "Valsan" HPP, was modelled in EPANET, in order to: i) test the method at a larger scale; ii) get the right flow and pressure transducers that are needed to implement it. At the request of "Hidroelectrica" a routine that computes the efficiency of the turbine was added to the monitoring software. After the system was implemented, another series of measurements were performed at the site in order to validate it. Failure was modelled by opening an existing valve on a branch of the penstock. Detection of the failure was correct and almost instantaneous, while failure location was accurate within 5% of the total penstock length.

  4. Transient Thermal Analyses of Passive Systems on SCEPTOR X-57

    NASA Technical Reports Server (NTRS)

    Chin, Jeffrey C.; Schnulo, Sydney L.; Smith, Andrew D.

    2017-01-01

    As efficiency, emissions, and noise become increasingly prominent considerations in aircraft design, turning to an electric propulsion system is a desirable solution. Achieving the intended benefits of distributed electric propulsion (DEP) requires thermally demanding high power systems, presenting a different set of challenges compared to traditional aircraft propulsion. The embedded nature of these heat sources often preclude the use of traditional thermal management systems in order to maximize performance, with less opportunity to exhaust waste heat to the surrounding environment. This paper summarizes the thermal analyses of X-57 vehicle subsystems that don't employ externally air-cooled heat sinks. The high-power battery, wires, high-lift motors, and aircraft outer surface are subjected to heat loads with stringent thermal constraints. The temperature of these components are tracked transiently, since they never reach a steady-state equilibrium. Through analysis and testing, this report demonstrates that properly characterizing the material properties is key to accurately modeling peak temperature of these systems, with less concern for spatial thermal gradients. Experimentally validated results show the thermal profile of these systems can be sufficiently estimated using reduced order approximations.

  5. Electronic systems failures and anomalies attributed to electromagnetic interference

    NASA Technical Reports Server (NTRS)

    Leach, R. D. (Editor); Alexander, M. B. (Editor)

    1995-01-01

    The effects of electromagnetic interference can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are electrically compatible is an important engineering function necessary to assure mission success. This reference publication will acquaint the reader with spacecraft electronic systems failures and anomalies caused by electromagnetic interference and will show the importance of electromagnetic compatibility activities in conjunction with space flight programs. It is also hoped that the report will illustrate that evolving electronic systems are increasingly sensitive to electromagnetic interference and that NASA personnel must continue to diligently pursue electromagnetic compatibility on space flight systems.

  6. Passive Thrust Oscillation Mitigation for the CEV Crew Pallet System

    NASA Technical Reports Server (NTRS)

    Sammons, Matthew; Powell, Cory; Pellicciotti, Joseph; Buehrle, Ralph; Johnson, Keith

    2012-01-01

    The Crew Exploration Vehicle (CEV) was intended to be the next-generation human spacecraft for the Constellation Program. The CEV Isolator Strut mechanism was designed to mitigate loads imparted to the CEV crew caused by the Thrust Oscillation (TO) phenomenon of the proposed Ares I Launch Vehicle (LV). The Isolator Strut was also designed to be compatible with Launch Abort (LA) contingencies and landing scenarios. Prototype struts were designed, built, and tested in component, sub-system, and system-level testing. The design of the strut, the results of the tests, and the conclusions and lessons learned from the program will be explored in this paper.

  7. Passive-solar directional-radiating cooling system

    DOEpatents

    Hull, John R.; Schertz, William W.

    1986-01-01

    A radiative cooling system for use with an ice-making system having a radiating surface aimed at the sky for radiating energy at one or more wavelength bands for which the atmosphere is transparent and a cover thermally isolated from the radiating surface and transparent at least to the selected wavelength or wavelengths, the thermal isolation reducing the formation of condensation on the radiating surface and/or cover and permitting the radiation to continue when the radiating surface is below the dewpoint of the atmosphere, and a housing supporting the radiating surface, cover and heat transfer means to an ice storage reservoir.

  8. Passive-solar directional-radiating cooling system

    DOEpatents

    Hull, J.R.; Schertz, W.W.

    1985-06-27

    A radiative cooling system for use with an ice-making system having a radiating surface aimed at the sky for radiating energy at one or more wavelength bands for which the atmosphere is transparent and a cover thermally isolated from the radiating surface and transparent at least to the selected wavelength or wavelengths, the thermal isolation reducing the formation of condensation on the radiating surface and/or cover and permitting the radiation to continue when the radiating surface is below the dewpoint of the atmosphere, and a housing supporting the radiating surface, cover and heat transfer means to an ice storage reservoir.

  9. Role of plant expression systems in antibody production for passive immunization.

    PubMed

    Virdi, Vikram; Depicker, Ann

    2013-01-01

    Passive immunization is a method to achieve immediate protection against infectious agents by administering pathogen-specific antibodies. It has proven to be lifesaving for many acute infections, and it is now also used for cancer treatment. Passive immunization therapies, however, are extremely expensive because they require large amounts of specific antibodies that are produced predominantly in mammalian expression systems. The cost for manufacturing plant-made antibodies is estimated to be comparatively low since plant production systems require relatively less capital investments. In addition, they are not prone to mammalian pathogens, which also eases downstream processing along with making it a safe expression system. Moreover, some of the recent developments in transient expression have enabled rapid, cGMP (current Good Manufacturing Practices) compliant manufacturing of antibodies. Whether lower production costs will be reflected in a lower market price for purified antibodies will be known when more plant-produced antibodies come to the market. Promisingly, the current molecular techniques in the field of in planta expression have enabled high-level production of a variety of antibodies in different plant organs, like roots/tubers/fruits, leaves and seeds, of a variety of plants, like potato, tobacco, maize, rice, tomato and pea, providing a very wide range of possible plant-based passive immunization therapies. For instance, the production of antibodies in edible tissues would allow for a unique, convenient, needle-less, oral passive immunization at the gastric mucosal surface. The technological advances, together with the innate capacity of plant tissues to assemble complex antibodies, will enable carving a niche in the antibody market. This non-exhaustive review aims to shed light on the role of plants as a flexible expression system for passive immunotherapy, which we envisage to progress alongside the conventional production platforms to manufacture

  10. Risk measures for power failures in transmission systems

    NASA Astrophysics Data System (ADS)

    Cassidy, Alex; Feinstein, Zachary; Nehorai, Arye

    2016-11-01

    We present a novel framework for evaluating the risk of failures in power transmission systems. We use the concept of systemic risk measures from the financial mathematics literature with models of power system failures in order to quantify the risk of the entire power system for design and comparative purposes. The proposed risk measures provide the collection of capacity vectors for the components in the system that lead to acceptable outcomes. Keys to the formulation of our measures of risk are two elements: a model of system behavior that provides the (distribution of) outcomes based on component capacities and an acceptability criterion that determines whether a (random) outcome is acceptable from an aggregated point of view. We examine the effects of altering the line capacities on energy not served under a variety of networks, flow manipulation methods, load shedding schemes, and load profiles using Monte Carlo simulations. Our results provide a quantitative comparison of the performance of these schemes, measured by the required line capacity. These results provide more complete descriptions of the risks of power failures than the previous, one-dimensional metrics.

  11. Risk measures for power failures in transmission systems.

    PubMed

    Cassidy, Alex; Feinstein, Zachary; Nehorai, Arye

    2016-11-01

    We present a novel framework for evaluating the risk of failures in power transmission systems. We use the concept of systemic risk measures from the financial mathematics literature with models of power system failures in order to quantify the risk of the entire power system for design and comparative purposes. The proposed risk measures provide the collection of capacity vectors for the components in the system that lead to acceptable outcomes. Keys to the formulation of our measures of risk are two elements: a model of system behavior that provides the (distribution of) outcomes based on component capacities and an acceptability criterion that determines whether a (random) outcome is acceptable from an aggregated point of view. We examine the effects of altering the line capacities on energy not served under a variety of networks, flow manipulation methods, load shedding schemes, and load profiles using Monte Carlo simulations. Our results provide a quantitative comparison of the performance of these schemes, measured by the required line capacity. These results provide more complete descriptions of the risks of power failures than the previous, one-dimensional metrics.

  12. Passive thermo-optic feedback for robust athermal photonic systems

    DOEpatents

    Rakich, Peter T.; Watts, Michael R.; Nielson, Gregory N.

    2015-06-23

    Thermal control devices, photonic systems and methods of stabilizing a temperature of a photonic system are provided. A thermal control device thermally coupled to a substrate includes a waveguide for receiving light, an absorption element optically coupled to the waveguide for converting the received light to heat and an optical filter. The optical filter is optically coupled to the waveguide and thermally coupled to the absorption element. An operating point of the optical filter is tuned responsive to the heat from the absorption element. When the operating point is less than a predetermined temperature, the received light is passed to the absorption element via the optical filter. When the operating point is greater than or equal to the predetermined temperature, the received light is transmitted out of the thermal control device via the optical filter, without being passed to the absorption element.

  13. Passive wireless sensor systems can recognize activites of daily living.

    PubMed

    Urwyler, Prabitha; Stucki, Reto; Muri, Rene; Mosimann, Urs P; Nef, Tobias

    2015-08-01

    The ability to determine what activity of daily living a person performs is of interest in many application domains. It is possible to determine the physical and cognitive capabilities of the elderly by inferring what activities they perform in their houses. Our primary aim was to establish a proof of concept that a wireless sensor system can monitor and record physical activity and these data can be modeled to predict activities of daily living. The secondary aim was to determine the optimal placement of the sensor boxes for detecting activities in a room. A wireless sensor system was set up in a laboratory kitchen. The ten healthy participants were requested to make tea following a defined sequence of tasks. Data were collected from the eight wireless sensor boxes placed in specific places in the test kitchen and analyzed to detect the sequences of tasks performed by the participants. These sequence of tasks were trained and tested using the Markov Model. Data analysis focused on the reliability of the system and the integrity of the collected data. The sequence of tasks were successfully recognized for all subjects and the averaged data pattern of tasks sequences between the subjects had a high correlation. Analysis of the data collected indicates that sensors placed in different locations are capable of recognizing activities, with the movement detection sensor contributing the most to detection of tasks. The central top of the room with no obstruction of view was considered to be the best location to record data for activity detection. Wireless sensor systems show much promise as easily deployable to monitor and recognize activities of daily living.

  14. Passive automatic anti-piracy defense system of ships

    NASA Astrophysics Data System (ADS)

    Szustakowski, M.; Życzkowski, M.; Ciurapiński, W.; Karol, M.; Kastek, M.; Stachowiak, R.; Markowski, P.

    2013-10-01

    The article describes the technological solution for ship self-defense against pirate attacks. The paper presents the design solutions in the field of direct physical protection. All the solutions are connected with the latest optoelectronic and microwave systems and sensors to detect, recognize and the threat posed by pirates. In particular, tests of effectiveness and the detection-range of technology demonstrator developed by a team of authors were carried out.

  15. Automatic design optimization tool for passive structural control systems

    NASA Astrophysics Data System (ADS)

    Mojolic, Cristian; Hulea, Radu; Parv, Bianca Roxana

    2017-07-01

    The present paper proposes an automatic dynamic process in order to find the parameters of the seismic isolation systems applied to large span structures. Three seismic isolation solutions are proposed for the model of the new Slatina Sport Hall. The first case uses friction pendulum system (FP), the second one uses High Damping Rubber Bearing (HDRB) and Lead Rubber Bearings, while (LRB) are used for the last case of isolation. The placement of the isolation level is at the top end of the roof supporting columns. The aim is to calculate the parameters of each isolation system so that the whole's structure first vibration periods is the one desired by the user. The model is computed with the use of SAP2000 software. In order to find the best solution for the optimization problem, an optimization process based on Genetic Algorithms (GA) has been developed in Matlab. With the use of the API (Application Programming Interface) libraries a two way link is created between the two programs in order to exchange results and link parameters. The main goal is to find the best seismic isolation method for each desired modal period so that the bending moment on the supporting columns should be minimum.

  16. Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

    PubMed

    Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

    2015-11-01

    Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Real-time passive terahertz imaging system for standoff concealed weapons imaging

    NASA Astrophysics Data System (ADS)

    Luukanen, Arttu; Grönberg, Leif; Grönholm, Markus; Lappalainen, Petteri; Leivo, Mikko; Rautiainen, Anssi; Tamminen, Aleksi; Ala-Laurinaho, Juha; Dietlein, Charles R.; Grossman, Erich N.

    2010-04-01

    The performance of stand-off imaging systems of concealed weapons in the mm-wave range remains limited by the relatively poor angular resolution using practical aperture sizes. For this reason, increasing the operating frequency of the systems is desired, but in practice is hard to realize due to the lack of affordable, low noise amplifiers well beyond 100 GHz. In this paper we present a passive terahertz imaging system which acquires passive terahertz (~200 GHz - ~1 THz) imagery near video frame rate. The system, one copy of which is built in Finland and the other in the U.S., is based on a 64 pixel linear array of superconducting antenna-coupled microbolometers operated within a commercial cryogen-free closed cycle cryocooler, and utilizes conical scanning Schmidt optics. Quantitative measurements on the imager resolution metrics (thermal, spatial and temporal) will be presented. The results from field tests at the Helsinki-Vantaa airport will be presented.

  18. Method of remote powering and detecting multiple UWB passive tags in an RFID system

    DOEpatents

    Dowla, Farid U [Castro Valley, CA; Nekoogar, Faranak [San Ramon, CA; Benzel, David M [Livermore, CA; Dallum, Gregory E [Livermore, CA; Spiridon, Alex [Palo Alto, CA

    2012-05-29

    A new Radio Frequency Identification (RFID), tracking, powering apparatus/system and method using coded Ultra-wideband (UWB) signaling is introduced. The proposed hardware and techniques disclosed herein utilize a plurality of passive UWB transponders in a field of an RFID-radar system. The radar system itself enables multiple passive tags to be remotely powered (activated) at about the same time frame via predetermined frequency UWB pulsed formats. Once such tags are in an activated state, an UWB radar transmits specific "interrogating codes" to put predetermined tags in an awakened status. Such predetermined tags can then communicate by a unique "response code" so as to be detected by an UWB system using radar methods.

  19. Passive removal of silicone oil through 23 gauge transconjunctival sutureless vitrectomy system

    PubMed Central

    Siyal, Nisar Ahmed; Hargun, Lakhani Das; Wahab, Shahid

    2016-01-01

    Objective: To study the outcomes of passive removal of silicone oil by 23 Gauge Transconjunctival Sutureless Vitrectomy System. Methods: This prospective, consecutive case series study was conducted at Ophthalmology Department Unit I, Dow University of Health Sciences, Civil Hospital Karachi from January 2011 to December 2014. Only psuedophakic eyes with silicone oil temponade were selected. Main outcome measures were intra ocular pressure, time taken for removal of silicone oil, per operative and post operative complications. Pre and post operative IOP was compared by using two-tailed paired t-test and mean values with standard deviation were computed using difference of 95% confidence interval. Chi square test was applied for correlation of different variables. P-value of less than 0.05 was considered statistically significant. Results: Out of 79 patients who underwent passive ROSO, 38 (48.1%) were males. Mean age of patients was 47.5±7.1 (sd) years. Mean time taken for passive ROSO was 7.31±2.41 (sd) minutes. Pre and post operative intra ocular pressure shows statistically significant (p=0.000) decrease in IOP. Retinal redetachment found in 13 (16.5%) cases during follow up period. Conclusion: Passive removal of silicone oil with 23 G suture less vitrectomy system is safe and effective in terms of less per operative and post operative complications. In this simple technique, there is less tissue trauma and little time consumed so it provides more comfort to patients and surgeons as well. PMID:27375708

  20. Sizing criteria for a low footprint passive mine water treatment system.

    PubMed

    Sapsford, D J; Williams, K P

    2009-02-01

    The objective of this paper is to present data from a novel vertical flow mine water treatment system, demonstrate how these data can be used to generate sizing formulae for this technology, and present a comparison between the size of system based on these formulae and those of conventionally designed passive systems. The paper focuses on passive treatment of circum-neutral ferruginous mine waters bearing up to 50 mgl(-1) of iron in either ferrous or ferric form. The Vertical Flow Reactor (VFR) operates by passing mine water down through an accreting bed of ochre, the ochre bed being responsible for the intensification of iron removal by self-filtration and/or autocatalytic iron oxidation and precipitation. Key to the design and operation of the VFR system is the decrease in permeability in this ochre bed over time. The paper demonstrates that the VFR system can remove iron at many times the 10 g/m2/day removal rate - an often employed figure for the sizing of aerobic settling ponds and wetlands. The paper demonstrates that VFRs are viable and novel passive treatment system for mine waters with a smaller footprint than conventional systems.

  1. An automatic mode-locked system for passively mode-locked fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Sha; Xu, Jun; Chen, Guoliang; Mei, Li; Yi, Bo

    2013-12-01

    This paper designs and implements one kind of automatic mode-locked system. It can adjust a passively mode-locked fiber laser to keep steady mode-locked states automatically. So the unsteadiness of traditional passively mode-locked fiber laser can be avoided. The system transforms optical signals into electrical pulse signals and sends them into MCU after processing. MCU calculates the frequency of the signals and judges the state of the output based on a quick judgment algorithm. A high-speed comparator is used to check the signals and the comparison voltage can be adjusted to improve the measuring accuracy. Then by controlling two polarization controllers at an angle of 45degrees to each other, MCU extrudes the optical fibers to change the polarization until it gets proper mode-locked output. So the system can continuously monitor the output signal and get it back to mode-locked states quickly and automatically. States of the system can be displayed on the LCD and PC. The parameters of the steady mode-locked states can be stored into an EEPROM so that the system will get into mode-locked states immediately next time. Actual experiments showed that, for a 6.238MHz passively mode-locked fiber lasers, the system can get into steady mode-locked states automatically in less than 90s after starting the system. The expected lock time can be reduced to less than 20s after follow up improvements.

  2. Degradation and failure characteristics of NPP containment protective coating systems

    SciTech Connect

    Sindelar, R.L.

    2000-03-30

    A research program to investigate the performance and potential for failure of Service Level 1 coating systems used in nuclear power plant containment is in progress. The research activities are aligned to address phenomena important to cause failure as identified by the industry coatings expert panel. The period of interest for performance covers the time from application of the coating through 40 years of service, followed by a medium-to-large break loss-of-coolant accident scenario, which is a design basis accident (DBA) scenario. The interactive program elements are discussed in this report and the application of these elements to the System 5 coating system (polyamide epoxy primer, carbon steel substrate) is used to evaluate performance.

  3. Tropospheric Passive Remote Sensing

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr. (Editor)

    1982-01-01

    The long term role of airborne/spaceborne passive remote sensing systems for tropospheric air quality research and the identification of technology advances required to improve the performance of passive remote sensing systems were discussed.

  4. Review of passive groundwater remediation systems: Lessons learned Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1997-08-01

    One of the proposed solutions for treatment of the contaminated groundwater in the Bear Creek Valley is the installation of a passive treatment system. Such a system would use a reactive media installed in a continuous trench or in a gate as part of a barrier wall and gate system. This report evaluates information on five similar systems [no information was available on two additional systems] and evaluates the shortcomings and the advantages of each. Section 5 provides a short summary of the findings and presents some recommendations on how to avoid some of the common problems encountered with the existing systems.

  5. Passive solar technology

    SciTech Connect

    Watson, D

    1981-04-01

    The present status of passive solar technology is summarized, including passive solar heating, cooling and daylighting. The key roles of the passive solar system designer and of innovation in the building industry are described. After definitions of passive design and a summary of passive design principles are given, performance and costs of passive solar technology are discussed. Passive energy design concepts or methods are then considered in the context of the overall process by which building decisions are made to achieve the integration of new techniques into conventional design. (LEW).

  6. Study of thermosiphon and radiant panel passive heating systems for metal buildings

    SciTech Connect

    Biehl, F.A.; Schnurr, N.M.; Wray, W.O.

    1983-01-01

    A study of passive-heating systems appropriate for use on metal buildings is being conducted at Los Alamos National Laboratory for the Naval Civil Engineering Laboratory, Port Hueneme, California. The systems selected for study were chosen on the basis of their appropriateness for retrofit applications, although they are also suitable for new construction: simple radiant panels that communicate directly with the building interior and a backflow thermosiphon that provides heat indirectly.

  7. Active and Passive User Trust in Sociotechnical Systems

    DTIC Science & Technology

    2015-09-28

    Fogg  et  al.,   2003;  Kim  &  Moon,  1998;  Weinstock,  Oron-­‐Gilad...human-­‐computer   interaction   domain,   the   prominence-­‐interpretation   theory   proposed   by   Fogg   (2003)   could... Fogg ,  2003).  So  the   collection  of  system  elements  that  could  potentially  affect  a  user’s  trust

  8. An intelligent control system for failure detection and controller reconfiguration

    NASA Technical Reports Server (NTRS)

    Biswas, Saroj K.

    1994-01-01

    We present an architecture of an intelligent restructurable control system to automatically detect failure of system components, assess its impact on system performance and safety, and reconfigure the controller for performance recovery. Fault detection is based on neural network associative memories and pattern classifiers, and is implemented using a multilayer feedforward network. Details of the fault detection network along with simulation results on health monitoring of a dc motor have been presented. Conceptual developments for fault assessment using an expert system and controller reconfiguration using a neural network are outlined.

  9. Pilot-scale comparison of two hybrid-passive landfill leachate treatment systems operated in a cold climate.

    PubMed

    Speer, Sean; Champagne, Pascale; Anderson, Bruce

    2012-01-01

    Hybrid-passive landfill leachate treatment systems employ active pretreatment to remove dissolved inorganic constituents and decrease the oxygen demand of the leachate prior to treatment in a passive system. In a 1-year pilot-scale study, two passive treatment systems - a peat and wood shaving biological trickle filter and a sand and gravel constructed wetland - were installed to treat leachate from the Merrick Landfill in North Bay, Ontario, Canada. Leachate was pretreated in a fixed-film aerobic reactor, which provided reductions in COD (26%), and masses of ammonia (21%), Al (69%), Ca (57%), Fe (73%) and Sr (37%). A comparison of the performance of the hybrid-passive treatment systems indicated different extents of heterotrophic nitrification; the peat and wood shaving filter removed 49% of the ammonia and nitrified 29%, while the constructed wetland removed 99% of the ammonia and nitrified 90%. Hybrid-passive landfill leachate treatment was determined to be feasible in cold climates.

  10. High-spatial-resolution passive microwave sounding systems

    NASA Technical Reports Server (NTRS)

    Staelin, David H.; Barrett, J. W.; Bonanni, Pierino Gianni; Chiarchiaro, W. J., II; Rosenkranz, P. W.

    1991-01-01

    During this period the emphasis was on the following: (1) further design, construction, and testing of the improved 54-GHz portion of the 54-118 GHz microwave temperature sounder (MTS) aircraft radiometer system in preparation for ER-2 observations in July 1991; and (2) final analysis and documentation of procedures for detecting and analyzing thermal waves in our 118-GHz MTS imagery. In addition, we have new unpublished measurements of dry-air attenuation at frequencies of 54 to 66 GHz and over a temperature range of 280K to 326K; these measurements should enable us to improve further our atmospheric transmittance models. It was further noted that the proposed SSMIS conical-scanning microwave spectrometer on the military DMSP Block 5D-3 spacecraft designed to measure stratospheric and mesospheric temperature profiles will be observing the Zeeman-split oxygen lines with sufficient spectral resolution that the changing Doppler shifts with view angle will substantially degrade the potential system performance unless remedied; this was briefly studied and documented.

  11. Chemistry and kinetics of calcite dissolution in passive treatment systems

    SciTech Connect

    Rose, A.W.

    1999-07-01

    Reaction of calcite with AMD is a key remediation process in anoxic limestone drains, (ALD), SAPS, and many wetlands, but predictions of effluent quality are currently based mainly on rules of thumb and prior experience. The PHREEQC computer program can be used to calculate the progress of this and similar reactions, and aid in understanding, design and evaluation of these systems. At pH values less than 5, calcite dissolution rates are strongly influenced by transport parameters such as flow velocity. Estimated calcite dissolution rates from ALD's and column experiments indicate little change in rate with pH, in contrast to published data for well stirred lab experiments. The dissolution rate is affected by concentration of SO{sub 4}, Fe, Al, Ca, P, and other trace solutes. The optimum contact time and sizing of ALD's will be dependent on these and possibly other parameters. Additional experiments are needed to evaluate these dependencies.

  12. High-spatial-resolution passive microwave sounding systems

    NASA Technical Reports Server (NTRS)

    Staelin, D. H.; Rosenkranz, P. W.

    1994-01-01

    The principal contributions of this combined theoretical and experimental effort were to advance and demonstrate new and more accurate techniques for sounding atmospheric temperature, humidity, and precipitation profiles at millimeter wavelengths, and to improve the scientific basis for such soundings. Some of these techniques are being incorporated in both research and operational systems. Specific results include: (1) development of the MIT Microwave Temperature Sounder (MTS), a 118-GHz eight-channel imaging spectrometer plus a switched-frequency spectrometer near 53 GHz, for use on the NASA ER-2 high-altitude aircraft, (2) conduct of ER-2 MTS missions in multiple seasons and locations in combination with other instruments, mapping with unprecedented approximately 2-km lateral resolution atmospheric temperature and precipitation profiles, atmospheric transmittances (at both zenith and nadir), frontal systems, and hurricanes, (3) ground based 118-GHz 3-D spectral images of wavelike structure within clouds passing overhead, (4) development and analysis of approaches to ground- and space-based 5-mm wavelength sounding of the upper stratosphere and mesosphere, which supported the planning of improvements to operational weather satellites, (5) development of improved multidimensional and adaptive retrieval methods for atmospheric temperature and humidity profiles, (6) development of combined nonlinear and statistical retrieval techniques for 183-GHz humidity profile retrievals, (7) development of nonlinear statistical retrieval techniques for precipitation cell-top altitudes, and (8) numerical analyses of the impact of remote sensing data on the accuracy of numerical weather predictions; a 68-km gridded model was used to study the spectral properties of error growth.

  13. Portable suction unit failure in a rural EMS system.

    PubMed

    Risavi, Brian L; Sabotchick, K J; Heile, Christopher J

    2013-08-01

    Portable suction units used by EMS personnel are utilized infrequently and often are powered by batteries. Lack of use and inspection often results in failure of the device when it is needed. The purpose of this study was to examine the incidence of portable suction unit failure in a rural EMS system and to identify the reasons for failures. A convenience sample was obtained through both random inspections by the staff of a regional EMS council and data from twice monthly checks reported by respective EMS agencies following a standard protocol for each unit. A standard protocol was used, including checking the vacuum level on each suction unit and inspecting the tubing, canister, and battery. Each inspector assessed whether the unit was capable of achieving 300 mmHg of suction within four seconds. Also, the unit was inspected for any signs of misalignment or dry rot of the gasket, kinking of suction hose, damage to the suction canister, weak/dead battery, or defective pump. Findings were recorded. Over a two-year period, 9,631 suction unit inspections were completed. There were 233 failures (2.4%) noted. The majority (126, 54.1%) were due to battery failure. Seventy-three units failed due to other reasons (not recorded, switch failure, battery not seated). Ten inspections failed due to incorrect assembly. Nineteen inspections failed due to defects with the suction canister. Five inspections failed due to kinked/disconnected suction tubing. Only a relatively small percentage of inspections of suction units revealed failures (4.6% Advanced Life Support, 8.6% Basic Life Support) using the above-stated criteria. However, given the importance of airway management and potential complications associated with airway compromise, including aspiration pneumonia, hypoxia, and hemodynamic instability, this is of concern relative to the morbidity and mortality that could be related to airway failure. Due to the relative infrequency of use and the nature of portable suction units

  14. 49 CFR 191.12 - Distribution Systems: Mechanical Fitting Failure Reports

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Distribution Systems: Mechanical Fitting Failure...-RELATED CONDITION REPORTS § 191.12 Distribution Systems: Mechanical Fitting Failure Reports Each mechanical fitting failure, as required by § 192.1009, must be submitted on a Mechanical Fitting Failure...

  15. System and method of DPF passive enhancement through powertrain torque-speed management

    DOEpatents

    Sujan, Vivek A.; Frazier, Timothy R.

    2015-11-24

    This disclosure provides a method and system for determining recommendations for vehicle operation that reduce soot production in view of a diesel particulate filter (DPF) of an exhaust aftertreatment system. Recommendations generated can reduce excessive particulate matter (PM) production during transient engine events and provide for operating conditions favorable for passive regeneration. In this way, less frequent active regeneration of the DPF is needed and/or more opportunities are provided for passive regeneration. The system and method can utilize location and terrain information to anticipate and project a window of operation in view of reducing soot production and soot loading of the DPF, or provide the operator with instruction when such opportunities are present or will soon be encountered.

  16. Active charge/passive discharge solar heating systems: Thermal analysis and performance comparisons and performance comparisons

    NASA Astrophysics Data System (ADS)

    Swisher, J.

    1981-06-01

    This type of system combines liquid-cooled solar collector panels with a massive integral storage component that passively heats the building interior by radiation and free convection. The TRNSYS simulation program is used to evaluate system performance and to provide input for the development of a simplified analysis method. This method, which provides monthly calculations of delivered solar energy, is based on Klein's Phi-bar procedure and data from hourly TRNSYS simulations. The method can be applied to systems using a floor slab, a structural wall, or a water tank as the storage component. Important design parameters include collector area and orientation, building heat loss, collector and heat exchanger efficiencies, storage capacity, and storage to room coupling. Performance simulation results are used for comparisons with active and passive solar designs.

  17. Active and passive calcium transport systems in plant cells. Progress report, May 1986--January 1991

    SciTech Connect

    Sze, H.

    1991-12-31

    The ability to change cytoplasmic Ca{sup 2+} levels ([Ca{sup 2+}]) by cells has made this cation a key regulator of many biological processes. Cytoplasmic [Ca{sup 2+}] is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic [Ca{sup 2+}] and active Ca{sup 2+} transport systems that lower cytosolic [Ca{sup 2+}]. The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells.

  18. A novel mathematical setup for fault tolerant control systems with state-dependent failure process

    NASA Astrophysics Data System (ADS)

    Chitraganti, S.; Aberkane, S.; Aubrun, C.

    2014-12-01

    In this paper, we consider a fault tolerant control system (FTCS) with state- dependent failures and provide a tractable mathematical model to handle the state-dependent failures. By assuming abrupt changes in system parameters, we use a jump process modelling of failure process and the fault detection and isolation (FDI) process. In particular, we assume that the failure rates of the failure process vary according to which set the state of the system belongs to.

  19. Performance of an active/passive hybrid solar system utilizing vapor transport

    SciTech Connect

    Hedstrom, J.C.

    1984-01-01

    Vapor-phase heat-transport systems are being tested in two of the passive test cells at Los Alamos. The systems consist of an active fin-and-tube collector and a condenser inside a water storage tank. The refrigerant, R-11, can be returned to the collector with a pump or with a self-pumping scheme. A computer model was developed to predict the behavior of the system, after which the computer was used to predict the annual performance of these systems in five cities. The report compares the measured and the predicted results as well as the system's sensitivity to several parameters.

  20. Horizontal Heat Exchanger Design and Analysis for Passive Heat Removal Systems

    SciTech Connect

    Vierow, Karen

    2005-08-29

    This report describes a three-year project to investigate the major factors of horizontal heat exchanger performance in passive containment heat removal from a light water reactor following a design basis accident LOCA (Loss of Coolant Accident). The heat exchanger studied in this work may be used in advanced and innovative reactors, in which passive heat removal systems are adopted to improve safety and reliability The application of horizontal tube-bundle condensers to passive containment heat removal is new. In order to show the feasibility of horizontal heat exchangers for passive containment cooling, the following aspects were investigated: 1. the condensation heat transfer characteristics when the incoming fluid contains noncondensable gases 2. the effectiveness of condensate draining in the horizontal orientation 3. the conditions that may lead to unstable condenser operation or highly degraded performance 4. multi-tube behavior with the associated secondary-side effects This project consisted of two experimental investigations and analytical model development for incorporation into industry safety codes such as TRAC and RELAP. A physical understanding of the flow and heat transfer phenomena was obtained and reflected in the analysis models. Two gradute students (one funded by the program) and seven undergraduate students obtained research experience as a part of this program.

  1. LWIR passive perception system for stealthy unmanned ground vehicle night operations

    NASA Astrophysics Data System (ADS)

    Lee, Daren; Rankin, Arturo; Huertas, Andres; Nash, Jeremy; Ahuja, Gaurav; Matthies, Larry

    2016-05-01

    Resupplying forward-deployed units in rugged terrain in the presence of hostile forces creates a high threat to manned air and ground vehicles. An autonomous unmanned ground vehicle (UGV) capable of navigating stealthily at night in off-road and on-road terrain could significantly increase the safety and success rate of such resupply missions for warfighters. Passive night-time perception of terrain and obstacle features is a vital requirement for such missions. As part of the ONR 30 Autonomy Team, the Jet Propulsion Laboratory developed a passive, low-cost night-time perception system under the ONR Expeditionary Maneuver Warfare and Combating Terrorism Applied Research program. Using a stereo pair of forward looking LWIR uncooled microbolometer cameras, the perception system generates disparity maps using a local window-based stereo correlator to achieve real-time performance while maintaining low power consumption. To overcome the lower signal-to-noise ratio and spatial resolution of LWIR thermal imaging technologies, a series of pre-filters were applied to the input images to increase the image contrast and stereo correlator enhancements were applied to increase the disparity density. To overcome false positives generated by mixed pixels, noisy disparities from repeated textures, and uncertainty in far range measurements, a series of consistency, multi-resolution, and temporal based post-filters were employed to improve the fidelity of the output range measurements. The stereo processing leverages multi-core processors and runs under the Robot Operating System (ROS). The night-time passive perception system was tested and evaluated on fully autonomous testbed ground vehicles at SPAWAR Systems Center Pacific (SSC Pacific) and Marine Corps Base Camp Pendleton, California. This paper describes the challenges, techniques, and experimental results of developing a passive, low-cost perception system for night-time autonomous navigation.

  2. Investigation of passive blade cyclic pitch variation using an automatic yaw control system. Final report

    SciTech Connect

    Hohenemser, K.H.; Swift, A.H.P.

    1982-08-01

    The investigation of passive cyclic pitch variation using an automatic yaw control system made use of the test equipment and of the results of an earlier study. The atmospheric test equipment consisted of a horizontal axis wind turbine with vane controlled upwind two-bladed rotor of 7.6 m (25 ft) diameter having passive cyclic pitch variation. An automatically triggered electric furl actuator prevented over-speeds and over-torques by furling the rotor which means yawing the rotor out of the winds. The atmospheric test equipment was modified to accept two alternative fully automatic yaw or furl control systems. The first system was of the active type and included a hydraulic single acting constant speed governor as it is used for aircraft propeller controls. Upon reaching the rotor speed limit, the governor delivered pressurized oil to a hydraulic furl actuator which then overcame the unfurling spring force and furled the rotor. When the rotor speed fell below the set value, the governor admitted oil flow from the hydraulic actuator into the oil reservoir and the rotor was unfurled by the spring. The second automatic control system was of a purely mechanical passive type. The rotor thrust, which was laterally off-set from the yaw axis, in combination with a yawing component of the rotor torque due to uptilt of the rotor axis overcame at rated power the unfurling spring and furled the rotor. The analytically predicted and experimentally substantiated negative rotor yaw damping would cause excessive furling rates unless alleviated by a furl damper. The tests were supported by a specially developed dynamic yawing analysis. Both analysis and tests indicated that the two-bladed passive cyclic pitch wind rotor can be effectively torque or speed limited by rotor yaw control systems which are less costly and more reliable than the conventional blade feathering control systems.

  3. Failure and factors of safety in piping system design

    SciTech Connect

    Antaki, G.A.

    1993-06-01

    An important body of test and performance data on the behavior of piping systems has led to an ongoing reassessment of the code stress allowables and their safety margin. The codes stress allowables, and their factors of safety, are developed from limits on the incipient yield (for ductile materials), or incipient rupture (for brittle materials), of a test specimen loaded in simple tension. In this paper, we examine the failure theories introduced in the B31 and ASME III codes for piping and their inherent approximations compared to textbook failure theories. We summarize the evolution of factors of safety in ASME and B31 and point out that, for piping systems, it is appropriate to reconsider the concept and definition of factors of safety.

  4. Method of Testing and Predicting Failures of Electronic Mechanical Systems

    NASA Technical Reports Server (NTRS)

    Iverson, David L.; Patterson-Hine, Frances A.

    1996-01-01

    A method employing a knowledge base of human expertise comprising a reliability model analysis implemented for diagnostic routines is disclosed. The reliability analysis comprises digraph models that determine target events created by hardware failures human actions, and other factors affecting the system operation. The reliability analysis contains a wealth of human expertise information that is used to build automatic diagnostic routines and which provides a knowledge base that can be used to solve other artificial intelligence problems.

  5. Understanding Search Failures in Consumer Health Information Systems

    PubMed Central

    McCray, Alexa T.; Tse, Tony

    2003-01-01

    We examined queries that led to search failures on two National Library of Medicine Web-based consumer health sites, ClincialTrials.gov and MEDLINEplus. The purpose of the study was to analyze and categorize queries resulting that led to no results with the ultimate goal of developing interventions to assist users in recovering from those failures. We first analyzed over 2,700 queries, iteratively developing a coding scheme. We subsequently applied the codes to an additional set of 2,000 queries. We found that most of the queries were in scope, relevant to the system being searched, and did not exhibit so-called consumer language. As the final step, we developed a taxonomy based on whether the search failures were due primarily to content issues, to problems in query formulation, or to limitations of the search system. The results reported here have informed the further development of our own systems, and they may be helpful to others as they seek to improve consumer access to health information. PMID:14728209

  6. Preprogrammed capillarity to passively control system-level sequential and parallel microfluidic flows.

    PubMed

    Kim, Sung-Jin; Paczesny, Sophie; Takayama, Shuichi; Kurabayashi, Katsuo

    2013-06-07

    In microfluidics, capillarity-driven solution flow is often beneficial, owing to its inherently spontaneous motion. However, it is commonly perceived that, in an integrated microfluidic system, the passive capillarity control alone can hardly achieve well-controlled sequential and parallel flow of multiple solutions. Despite this common notion, we hereby demonstrate system-level sequential and parallel microfluidic flow processing by fully passive capillarity-driven control. After manual loading of solutions with a pipette, a network of microfluidic channels passively regulates the flow timing of the multiple solution menisci in a sequential and synchronous manner. Also, use of auxiliary channels and preprogramming of inlet-well meniscus pressure and channel fluidic conductance allow for controlling the flow direction of multiple solutions in our microfluidic system. With those components orchestrated in a single device chip, we show preprogrammed flow control of 10 solutions. The demonstrated system-level flow control proves capillarity as a useful means even for sophisticated microfluidic processing without any actively controlled valves and pumps.

  7. Preprogrammed capillarity to passively control system-level sequential and parallel microfluidic flows

    PubMed Central

    Kim, Sung-Jin; Paczesny, Sophie; Takayama, Shuichi; Kurabayashi, Katsuo

    2013-01-01

    In microfluidics, capillarity-driven solution flow is often beneficial, owing to its inherently spontaneous motion. However, it is commonly perceived that, in an integrated microfluidic system, the passive capillarity control alone can hardly achieve well-controlled sequential and parallel flow of multiple solutions. Despite this common notion, we hereby demonstrate system-level sequential and parallel microfluidic flow processing by fully passive capillarity-driven control. After manual loading of solutions with a pipette, a network of microfluidic channels passively regulates the flow timing of the multiple solution menisci in a sequential and synchronous manner. Also, use of auxiliary channels and preprogramming of inlet-well meniscus pressure and channel fluidic conductance allow for controlling the flow direction of multiple solutions in our microfluidic system. With those components orchestrated in a single device chip, we show preprogrammed flow control of 10 solutions. The demonstrated system-level flow control proves capillarity as a useful means even for sophisticated microfluidic processing without any actively controlled valves and pumps. PMID:23598742

  8. Brix refractometry in serum as a measure of failure of passive transfer compared to measured immunoglobulin G and total protein by refractometry in serum from dairy calves.

    PubMed

    Hernandez, D; Nydam, D V; Godden, S M; Bristol, L S; Kryzer, A; Ranum, J; Schaefer, D

    2016-05-01

    A series of trials were conducted to evaluate Brix refractometry (Brix %) for the assessment of failure of passive transfer (FPT) in dairy calves compared to: (1) serum IgG (reference standard) when measured by radial immunodiffusion (RID) or a turbidometric immunoassay (TIA), and (2) serum total protein refractometry (STP). For the serum samples tested with TIA, STP, and Brix % (n = 310; Holstein calves), the median concentrations were 21.3 g/L IgG, 58 g/L STP, and 9.2%, respectively. For the serum samples tested with RID, STP and Brix % (n = 112; Jersey calves), the mean concentrations were 38 g/L IgG, 68 g/L STP, and 10.2%, respectively. For samples tested with only Brix % and STP (n = 265; Holstein calves), median STP and Brix % were 50 g/L STP and 8.5%, respectively. Correlations between Brix % and RID, and between Brix % and TIA were equal (r = 0.79, respectively). Brix % and STP were positively correlated (r = 0.99). Brix % estimated serum IgG concentrations determined by TIA and RID (r(2) = 0.63, 0.62, respectively). When FPT was defined as serum IgG < 10 g/L, Brix % ≤ 8.5% showed optimal sensitivity (100%) and specificity (89.2%) to predict FPT. At the same IgG cut-point, an STP value of ≤ 52 g/L showed a similar sensitivity (100%) and specificity (80.4%) to predict FPT. Brix refractometry predicted successful transfer of passive immunity in dairy calves, but further evaluation as a diagnostic tool for the diagnosis of FPT is warranted. Copyright © 2016. Published by Elsevier Ltd.

  9. A mixture Weibull proportional hazard model for mechanical system failure prediction utilising lifetime and monitoring data

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Hua, Cheng; Xu, Guanghua

    2014-02-01

    As mechanical systems increase in complexity, it is becoming more and more common to observe multiple failure modes. The system failure can be regarded as the result of interaction and competition between different failure modes. It is therefore necessary to combine multiple failure modes when analysing the failure of an overall system. In this paper, a mixture Weibull proportional hazard model (MWPHM) is proposed to predict the failure of a mechanical system with multiple failure modes. The mixed model parameters are estimated by combining historical lifetime and monitoring data of all failure modes. In addition, the system failure probability density is obtained by proportionally mixing the failure probability density of multiple failure modes. Monitoring data are input into the MWPHM to estimate the system reliability and predict the system failure time. A simulated sample set is used to verify the ability of the MWPHM to model multiple failure modes. Finally, the MWPHM and the traditional Weibull proportional hazard model (WPHM) are applied to a high-pressure water descaling pump, which has two failure modes: sealing ring wear and thrust bearing damage. Results show that the MWPHM is greatly superior in system failure prediction to the WPHM.

  10. The study of quasi-optical system used in a passive near-field tetrahertz imaging system

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Zhu, Wei-wen; Zhang, Wen-si; Zhang, Cheng-jiang; Ding, Qing; Bi, Xian-ting; Wu, Jui-feng

    2013-08-01

    Passive terahertz imaging technology, which provided blackbody thermal imaging, showed great potential for security applications during the last years. Different research teams in different countries spent a great effort on it for obvious reasons, and first commercial passive THz human imaging system was available. Yet, development of passive THz-imaging system was always limited by the frame rate, spatial resolution and detector cell of it. In this paper, we presented the concept and experimental set-up for a quasi-optical system used in a near-field 0.14THz passive terahertz imaging system. The quasi-optical system was composed of a double-mirror beam-waveguide system and a special feed-horns array. The design of quasi-optical system was based on near-field Gauss optics theory. The double-mirror beam waveguide system was made up of an off-axis ellipsoid mirror and a flat mirror. The influence of angle-scanning of quasi-optics system in near-field THz-imaging was investigated theoretically. Meanwhile, a spatial sparse array-arrangement of feed-horns was applied in quasi-optics system, that the adjacent feed-horns were stagger in the horizontal direction. The influence of this special feed-horns array arrangement on the near-field imaging was also discussed in theory. The quasi-optical system met the requirements of the near-field imaging. The problem of low frame rate of traditional sparse array arrangement was solved by this special array arrangement. And the spatial imaging range of the passive imaging system was also increased. The experimental results of this terahertz imaging system were consistent with our earlier theoretical results. When the detective distance was 3-5m, the experimental spatial resolution of near-field THz imaging was 5cm, and a 5Hz of frame rate was obtained. The quasi-optics system had demonstrated its ability to scan persons and various kinds of objects. We hoped a commercial, user-friendly terahertz imaging system, which could be used

  11. Robust passive control for a class of uncertain neutral systems based on sliding mode observer.

    PubMed

    Liu, Zhen; Zhao, Lin; Kao, Yonggui; Gao, Cunchen

    2017-01-01

    The passivity-based sliding mode control (SMC) problem for a class of uncertain neutral systems with unmeasured states is investigated. Firstly, a particular non-fragile state observer is designed to generate the estimations of the system states, based upon which a novel integral-type sliding surface function is established for the control process. Secondly, a new sufficient condition for robust asymptotic stability and passivity of the resultant sliding mode dynamics (SMDs) is obtained in terms of linear matrix inequalities (LMIs). Thirdly, the finite-time reachability of the predesigned sliding surface is ensured by resorting to a novel adaptive SMC law. Finally, the validity and superiority of the scheme are justified via several examples.

  12. Robust controller designs for second-order dynamic system: A virtual passive approach

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Phan, Minh

    1990-01-01

    A robust controller design is presented for second-order dynamic systems. The controller is model-independent and itself is a virtual second-order dynamic system. Conditions on actuator and sensor placements are identified for controller designs that guarantee overall closed-loop stability. The dynamic controller can be viewed as a virtual passive damping system that serves to stabilize the actual dynamic system. The control gains are interpreted as virtual mass, spring, and dashpot elements that play the same roles as actual physical elements in stability analysis. Position, velocity, and acceleration feedback are considered. Simple examples are provided to illustrate the physical meaning of this controller design.

  13. Thermal System Verification and Model Validation for NASA's Cryogenic Passively Cooled James Webb Space Telescope

    NASA Technical Reports Server (NTRS)

    Cleveland, Paul E.; Parrish, Keith A.

    2005-01-01

    A thorough and unique thermal verification and model validation plan has been developed for NASA s James Webb Space Telescope. The JWST observatory consists of a large deployed aperture optical telescope passively cooled to below 50 Kelvin along with a suite of several instruments passively and actively cooled to below 37 Kelvin and 7 Kelvin, respectively. Passive cooling to these extremely low temperatures is made feasible by the use of a large deployed high efficiency sunshield and an orbit location at the L2 Lagrange point. Another enabling feature is the scale or size of the observatory that allows for large radiator sizes that are compatible with the expected power dissipation of the instruments and large format Mercury Cadmium Telluride (HgCdTe) detector arrays. This passive cooling concept is simple, reliable, and mission enabling when compared to the alternatives of mechanical coolers and stored cryogens. However, these same large scale observatory features, which make passive cooling viable, also prevent the typical flight configuration fully-deployed thermal balance test that is the keystone to most space missions thermal verification plan. JWST is simply too large in its deployed configuration to be properly thermal balance tested in the facilities that currently exist. This reality, when combined with a mission thermal concept with little to no flight heritage, has necessitated the need for a unique and alternative approach to thermal system verification and model validation. This paper describes the thermal verification and model validation plan that has been developed for JWST. The plan relies on judicious use of cryogenic and thermal design margin, a completely independent thermal modeling cross check utilizing different analysis teams and software packages, and finally, a comprehensive set of thermal tests that occur at different levels of JWST assembly. After a brief description of the JWST mission and thermal architecture, a detailed description

  14. Failure and Reliability Analysis for the Master Pump Shutdown System

    SciTech Connect

    BEVINS, R.R.

    2000-09-05

    The Master Pump Shutdown System (MPSS) will be installed in the 200 Areas of the Hanford Site to monitor and control the transfer of liquid waste between tank farms and between the 200 West and 200 East areas through the Cross-Site Transfer Line. The Safety Function provided by the MPSS is to shutdown any waste transfer process within or between tank farms if a waste leak should occur along the selected transfer route. The MPSS, which provides this Safety Class Function, is composed of Programmable Logic Controllers (PLCs), interconnecting wires, relays, Human to Machine Interfaces (HMI), and software. These components are defined as providing a Safety Class Function and will be designated in this report as MPSS/PLC. Input signals to the MPSS/PLC are provided by leak detection systems from each of the tank farm leak detector locations along the waste transfer route. The combination of the MPSS/PLC, leak detection system, and transfer pump controller system will be referred to as MPSS/SYS. The components addressed in this analysis are associated with the MPSS/SYS. The purpose of this failure and reliability analysis is to address the following design issues of the Project Development Specification (PDS) for the MPSS/SYS (HNF 2000a): (1) Single Component Failure Criterion, (2) System Status Upon Loss of Electrical Power, (3) Physical Separation of Safety Class cables, (4) Physical Isolation of Safety Class Wiring from General Service Wiring, and (5) Meeting the MPSS/PLC Option 1b (RPP 1999) Reliability estimate. The failure and reliability analysis examined the system on a component level basis and identified any hardware or software elements that could fail and/or prevent the system from performing its intended safety function.

  15. Peformance evaluation of a passive microwave imaging system. [for remote sensing

    NASA Technical Reports Server (NTRS)

    Mcallum, W. E.

    1973-01-01

    A test program was conducted to evaluate the passive microwave imaging system for possible application in the NASA Earth Resources Program. In addition to test data analysis, the report gives a brief description of the radiometer, its software, and the ground support equipment. The microwave image quality is adequate for remote sensing applications studies. Instrument problems are described, and suggestions are given for possible improvements and potential applications.

  16. Advanced Passive Acoustic Leak Location and Detection Verification System for Underground Fuel Pipelines

    DTIC Science & Technology

    2003-04-01

    Conference (March 1993). 4. E. G. Eckert, M. R. Fierro , and J. W. Maresca, Jr., “A Passive-Acoustic Approach to the Detection of Leaking Valves in...Pressurized Pipelines,” Technical Report for Martin Marietta Energy Systems, Inc., Vista Research Project 1050, Vista Research, Inc., Mountain View...California (August 1994). 5. E. G. Eckert, M. R. Fierro , and J. W. Maresca, Jr., “Demonstration of a Gas Acoustic Tracer (GAT) Method for the Location of

  17. Millimeter-Wave and Submillimeter-Wave/Terahertz Passive Imaging System Requirements: A Phenomenological Perspective

    DTIC Science & Technology

    2013-05-01

    Hecht , E. Optics ; (Third Edition), Chapter 13, Addison-Wesley: Reading, 1998. 18. Holst, G. Electro0- Optical Imaging System Performance; Chapter 18, SPIE...and 2. ..........................................3 Table 2. Optical properties of 5-mm-thick explosives, skin, metal, denim, and T-shirt (excerpted...reflectivity across the band. For passive imaging, the contrast mechanism changes as frequency increases. At frequencies of 100 GHz and below, the optical

  18. SWAD: small arms fire warning and direction finding system: a passive IR concept

    NASA Astrophysics Data System (ADS)

    Zahler, Moti; Danino, Meir

    2007-04-01

    A passive IR approach for stationary system is introduced providing protection to high value infrastructure and strategic areas by detecting and warnings against fire shot from rifles, carbines, sub-machines and various other small arms - SWAD. SWAD provides protected surroundings in which it remotely detects small arms fire. By analyzing their patterns, including duration and intensity, SWAD classifies the type of weapon being used.

  19. Demonstration of a cost-effective, broadband passive optical network system

    NASA Astrophysics Data System (ADS)

    Wood, Thomas H.; Feldman, Robert D.; Austin, Richard F.

    1994-04-01

    We demonstrate that a combination of coarse wavelength division multiplexing, time division multiplexing, and subcarrier multiple access can be used to provide broadband service over a 16-way split, single-fiber passive optical network. We provide an aggregate bit rate of 622 Mb/s outbound and 48 Mb/s return in our system, with power margins of at least 9.4 dB in excess of specifications.

  20. Lopez-Alegria with Passive Observatories for Experimental Microbial Systems (POEMS) foam cushion

    NASA Image and Video Library

    2006-10-03

    ISS014-E-05118 (3 Oct. 2006) --- Astronaut Michael E. Lopez-Alegria, Expedition 14 commander and NASA space station science officer, works with the Passive Observatories for Experimental Microbial Systems in Micro-G (POEMS) payload in the Minus Eighty Degree Laboratory Freezer for ISS (MELFI) in the Destiny laboratory of the International Space Station. MELFI is a low temperature freezer facility with nominal operating temperatures of -80, -26 and +4 degrees Celsius that will preserve experiment materials over long periods.

  1. Spacecraft dynamics characterization and control system failure detection, volume 1

    NASA Astrophysics Data System (ADS)

    1992-07-01

    The work under this grant has been directed to two aspects of the control of flexible spacecraft: (1) the modeling of deployed or erected structures including nonlinear joint characteristics; and (2) the detection and isolation of failures of the components of control systems for large space structures. The motivation for the first of these research tasks is the fact that very large assemblies in space will have to be built or deployed in situ. A likely scenario is, in fact, a combination of these wherein modules which are folded for transportation into orbit are erected to their final configuration and then jointed with other such erected modules to form the full assembly. Any such erectable modules will have joints. It remains to be seen whether or not joints designed for operational assemblies will have nonlinear properties, but it seems prudent to develop a methodology for dealing with that possibility. The motivation for the second of these research tasks is the fact that we foresee large assemblies in space which will require active control to damp vibrations and/or hold a desired shape. Lightweight structures will be very flexible, with many elastic modes having very low frequencies. In order to control these modes well, the control system will likely require many sensors and many actuators, probably distributed over much of the structure. The combination of a large number of control system components with long operational periods virtually guarantees that these systems will suffer control system component failures during operation. The control system must be designed to tolerate failures of some sensors and actuators, and still be able to continue to perform its function.

  2. Spacecraft dynamics characterization and control system failure detection, volume 1

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The work under this grant has been directed to two aspects of the control of flexible spacecraft: (1) the modeling of deployed or erected structures including nonlinear joint characteristics; and (2) the detection and isolation of failures of the components of control systems for large space structures. The motivation for the first of these research tasks is the fact that very large assemblies in space will have to be built or deployed in situ. A likely scenario is, in fact, a combination of these wherein modules which are folded for transportation into orbit are erected to their final configuration and then jointed with other such erected modules to form the full assembly. Any such erectable modules will have joints. It remains to be seen whether or not joints designed for operational assemblies will have nonlinear properties, but it seems prudent to develop a methodology for dealing with that possibility. The motivation for the second of these research tasks is the fact that we foresee large assemblies in space which will require active control to damp vibrations and/or hold a desired shape. Lightweight structures will be very flexible, with many elastic modes having very low frequencies. In order to control these modes well, the control system will likely require many sensors and many actuators, probably distributed over much of the structure. The combination of a large number of control system components with long operational periods virtually guarantees that these systems will suffer control system component failures during operation. The control system must be designed to tolerate failures of some sensors and actuators, and still be able to continue to perform its function.

  3. Design and fabrication of passive wireless sensor array system using composite coding resonant SAW transducer

    NASA Astrophysics Data System (ADS)

    Li, Ping; Wen, Yumei

    2006-02-01

    This paper presents a novel composite SAW (surface acoustic wave) passive wireless sensor system involving a resonator and a delay line. While the interrogational signal is a sinusoidal burst, the response is a delayed and damped oscillation. The frequency and the delay time of response are related to the measurand and the coding of the sensor element, respectively. The composite sensor consists of a SAW resonator and a delay line. It combines the advantages of these two devices and can be used as elements of multiple sensors for longer distance passive wireless measurements. As the wireless sensing response is weak and transient, in order to get the response with the maximum signal-to-noise ratio, the interrogational frequency is designed to be adjustable according to the result of frequency estimation. As a result, an optimal sensing result is achieved. In the transceiver set-up, the software DDS (direct digital synthesis) source with a rather high resolution is implemented to track the passive wireless sensor. An isolated switch is set in transmitter to depress the correlation leakage noise after switching off the wireless RF (radio frequency) interrogation signal. In this paper, the characteristics of the response, the working procedure of the signal processing, sensor temperature test results and the system error analyses are elaborated. A prototype instrument is built. Experimental results show the effectiveness of the instrumentation and the advantages of the composite sensor system.

  4. Accuracy of Biodex system 3 pro computerized dynamometer in passive mode.

    PubMed

    Nordez, A; Casari, P; Cornu, C

    2008-09-01

    A specific experimental design has been developed to determine the accuracy of the Biodex system 3 pro dynamometer in passive mode. Five cyclic stretching repetitions were imposed to an elastic rubber band at different velocities using the dynamometer, and the torque produced was measured using both the dynamometer and external force and position sensors. Velocity patterns performed by the dynamometer were also characterized and our results show that these patterns were reliable (ICC=1.00). The torque measured with the dynamometer and the sensors were reliable (ICC=1.00), although significant differences were observed between both methods. However, the measured torque standard error was velocity independent and was lower than 0.33 Nm. Moreover, regressions between the two torque measurements were close to the axes-bisector (r=1.00, slope: 1.01+/-0.01, y-intercept: -0.36+/-0.22 Nm). Finally, our results showed decreases in torque during the five cycles, but these decreases were not due to the dynamometer. It can be concluded that the dynamometer performed valid torque measurements in passive mode, and was an accurate tool to determine passive mechanical properties of the musculo-articular system. However, some discrepancies between the programmed and the measured speed profiles have been observed when approaching the speed limit of the system.

  5. Landing Characteristics of a Re-entry Vehicle with a Passive Landing System for Impact Alleviation

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Landing Characteristics of a Re-entry Vehicle with a Passive Landing System for Impact Alleviation. An experimental investigation was made to determine the landing characteristics of a 1/8-scale dynamic model of a reentry vehicle using a passive landing system to alleviate the landing-impact loads. The passive landing system consisted of a flexible heat shield with a small section of aluminum honeycomb placed between the heat shield and the crew compartment at the point that would be the first to contact the landing surface. The model was landed on concrete and sand landing surfaces at parachute letdown velocities. The investigations simulated a vertical velocity of 30 ft/sec (full scale), horizontal velocities of 0, 15, 30, 40, and 50 ft/sec (full scale), and landing attitudes ranging from -30 degrees to 20 degrees. The model investigation indicated that stable landings could be made on a concrete surface at horizontal velocities up to about 30 ft/sec, but the stable landing-attitude range at these speeds was small. The aluminum honeycomb bottomed occasionally during landings on concrete. When bottoming did not occur, maximum normal and longitudinal accelerations at the center of gravity of the vehicle were approximately 50g and 30g, respectively. [Entire movie available on DVD from CASI as Doc ID 20070030981. Contact help@sti.nasa.gov

  6. A new passive polarimetric imaging system collecting polarization signatures in the visible and infrared bands

    NASA Astrophysics Data System (ADS)

    Lavigne, Daniel A.; Breton, Mélanie; Fournier, Georges; Pichette, Mario; Rivet, Vincent

    2009-05-01

    Electro-optical imaging systems are frequently employed during surveillance operations and search and rescue missions to detect various targets of interest in both the civilian and military communities. By incorporating the polarization of light as supplementary information to such electro-optical imaging systems, it may be possible to increase the target discrimination performance considering that man-made objects are known to depolarize light in different manners than natural backgrounds. Consequently, many passive Stokes-vector imagers have been developed over the years. These sensors generally operate using one single spectral band at a time, which limits considerably the polarization information collected across a scene over a predefined specific spectral range. In order to improve the understanding of the phenomena that arise in polarimetric signatures of man-made targets, a new passive polarimetric imaging system was developed at Defence Research and Development Canada - Valcartier to collect polarization signatures over an extended spectral coverage. The Visible Infrared Passive Spectral Polarimetric Imager for Contrast Enhancement (VIP SPICE) operates four broad-band cameras concomitantly in the visible (VIS), the shortwave infrared (SWIR), the midwave infrared (MWIR), and the longwave infrared (LWIR) bands. The sensor is made of four synchronously-rotating polarizers mounted in front of each of the four cameras. Polarimetric signatures of man-made objects were acquired at various polarization angles in the four spectral bands. Preliminary results demonstrate the utility of the sensor to collect significant polarimetric signatures to discriminate man-made objects from their background.

  7. Impact of Passive Safety on FHR Instrumentation Systems Design and Classification

    SciTech Connect

    Holcomb, David Eugene

    2015-01-01

    Fluoride salt-cooled high-temperature reactors (FHRs) will rely more extensively on passive safety than earlier reactor classes. 10CFR50 Appendix A, General Design Criteria for Nuclear Power Plants, establishes minimum design requirements to provide reasonable assurance of adequate safety. 10CFR50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors, provides guidance on how the safety significance of systems, structures, and components (SSCs) should be reflected in their regulatory treatment. The Nuclear Energy Institute (NEI) has provided 10 CFR 50.69 SSC Categorization Guideline (NEI-00-04) that factors in probabilistic risk assessment (PRA) model insights, as well as deterministic insights, through an integrated decision-making panel. Employing the PRA to inform deterministic requirements enables an appropriately balanced, technically sound categorization to be established. No FHR currently has an adequate PRA or set of design basis accidents to enable establishing the safety classification of its SSCs. While all SSCs used to comply with the general design criteria (GDCs) will be safety related, the intent is to limit the instrumentation risk significance through effective design and reliance on inherent passive safety characteristics. For example, FHRs have no safety-significant temperature threshold phenomena, thus enabling the primary and reserve reactivity control systems required by GDC 26 to be passively, thermally triggered at temperatures well below those for which core or primary coolant boundary damage would occur. Moreover, the passive thermal triggering of the primary and reserve shutdown systems may relegate the control rod drive motors to the control system, substantially decreasing the amount of safety-significant wiring needed. Similarly, FHR decay heat removal systems are intended to be running continuously to minimize the amount of safety-significant instrumentation needed to initiate

  8. Methods, apparatus and system for notification of predictable memory failure

    DOEpatents

    Cher, Chen-Yong; Andrade Costa, Carlos H.; Park, Yoonho; Rosenburg, Bryan S.; Ryu, Kyung D.

    2017-01-03

    A method for providing notification of a predictable memory failure includes the steps of: obtaining information regarding at least one condition associated with a memory; calculating a memory failure probability as a function of the obtained information; calculating a failure probability threshold; and generating a signal when the memory failure probability exceeds the failure probability threshold, the signal being indicative of a predicted future memory failure.

  9. Optimizing the robustness of electrical power systems against cascading failures

    NASA Astrophysics Data System (ADS)

    Zhang, Yingrui; Yağan, Osman

    2016-06-01

    Electrical power systems are one of the most important infrastructures that support our society. However, their vulnerabilities have raised great concern recently due to several large-scale blackouts around the world. In this paper, we investigate the robustness of power systems against cascading failures initiated by a random attack. This is done under a simple yet useful model based on global and equal redistribution of load upon failures. We provide a comprehensive understanding of system robustness under this model by (i) deriving an expression for the final system size as a function of the size of initial attacks; (ii) deriving the critical attack size after which system breaks down completely; (iii) showing that complete system breakdown takes place through a first-order (i.e., discontinuous) transition in terms of the attack size; and (iv) establishing the optimal load-capacity distribution that maximizes robustness. In particular, we show that robustness is maximized when the difference between the capacity and initial load is the same for all lines; i.e., when all lines have the same redundant space regardless of their initial load. This is in contrast with the intuitive and commonly used setting where capacity of a line is a fixed factor of its initial load.

  10. Optimizing the robustness of electrical power systems against cascading failures

    PubMed Central

    Zhang, Yingrui; Yağan, Osman

    2016-01-01

    Electrical power systems are one of the most important infrastructures that support our society. However, their vulnerabilities have raised great concern recently due to several large-scale blackouts around the world. In this paper, we investigate the robustness of power systems against cascading failures initiated by a random attack. This is done under a simple yet useful model based on global and equal redistribution of load upon failures. We provide a comprehensive understanding of system robustness under this model by (i) deriving an expression for the final system size as a function of the size of initial attacks; (ii) deriving the critical attack size after which system breaks down completely; (iii) showing that complete system breakdown takes place through a first-order (i.e., discontinuous) transition in terms of the attack size; and (iv) establishing the optimal load-capacity distribution that maximizes robustness. In particular, we show that robustness is maximized when the difference between the capacity and initial load is the same for all lines; i.e., when all lines have the same redundant space regardless of their initial load. This is in contrast with the intuitive and commonly used setting where capacity of a line is a fixed factor of its initial load. PMID:27325160

  11. Performance evaluation of a hybrid-passive landfill leachate treatment system using multivariate statistical techniques.

    PubMed

    Wallace, Jack; Champagne, Pascale; Monnier, Anne-Charlotte

    2015-01-01

    A pilot-scale hybrid-passive treatment system operated at the Merrick Landfill in North Bay, Ontario, Canada, treats municipal landfill leachate and provides for subsequent natural attenuation. Collected leachate is directed to a hybrid-passive treatment system, followed by controlled release to a natural attenuation zone before entering the nearby Little Sturgeon River. The study presents a comprehensive evaluation of the performance of the system using multivariate statistical techniques to determine the interactions between parameters, major pollutants in the leachate, and the biological and chemical processes occurring in the system. Five parameters (ammonia, alkalinity, chemical oxygen demand (COD), "heavy" metals of interest, with atomic weights above calcium, and iron) were set as criteria for the evaluation of system performance based on their toxicity to aquatic ecosystems and importance in treatment with respect to discharge regulations. System data for a full range of water quality parameters over a 21-month period were analyzed using principal components analysis (PCA), as well as principal components (PC) and partial least squares (PLS) regressions. PCA indicated a high degree of association for most parameters with the first PC, which explained a high percentage (>40%) of the variation in the data, suggesting strong statistical relationships among most of the parameters in the system. Regression analyses identified 8 parameters (set as independent variables) that were most frequently retained for modeling the five criteria parameters (set as dependent variables), on a statistically significant level: conductivity, dissolved oxygen (DO), nitrite (NO2(-)), organic nitrogen (N), oxidation reduction potential (ORP), pH, sulfate and total volatile solids (TVS). The criteria parameters and the significant explanatory parameters were most important in modeling the dynamics of the passive treatment system during the study period. Such techniques and

  12. Elbow spasticity during passive stretch-reflex: clinical evaluation using a wearable sensor system

    PubMed Central

    2013-01-01

    Background Spasticity is a prevalent chronic condition among persons with upper motor neuron syndrome that significantly impacts function and can be costly to treat. Clinical assessment is most often performed with passive stretch-reflex tests and graded on a scale, such as the Modified Ashworth Scale (MAS). However, these scales are limited in sensitivity and are highly subjective. This paper shows that a simple wearable sensor system (angle sensor and 2-channel EMG) worn during a stretch-reflex assessment can be used to more objectively quantify spasticity in a clinical setting. Methods A wearable sensor system consisting of a fibre-optic goniometer and 2-channel electromyography (EMG) was used to capture data during administration of the passive stretch-reflex test for elbow flexor and extensor spasticity. A kinematic model of unrestricted passive joint motion was used to extract metrics from the kinematic and EMG data to represent the intensity of the involuntary reflex. Relationships between the biometric results and clinical measures (MAS, isometric muscle strength and passive range of motion) were explored. Results Preliminary results based on nine patients with varying degrees of flexor and extensor spasticity showed that kinematic and EMG derived metrics were strongly correlated with one another, were correlated positively (and significantly) with clinical MAS, and negatively correlated (though mostly non-significant) with isometric muscle strength. Conclusions We conclude that a wearable sensor system used in conjunction with a simple kinematic model can capture clinically relevant features of elbow spasticity during stretch-reflex testing in a clinical environment. PMID:23782931

  13. Characterization of robotic system passive path repeatability during specimen removal and reinstallation for in vitro knee joint testing.

    PubMed

    Goldsmith, Mary T; Smith, Sean D; Jansson, Kyle S; LaPrade, Robert F; Wijdicks, Coen A

    2014-10-01

    Robotic testing systems are commonly utilized for the study of orthopaedic biomechanics. Quantification of system error is essential for reliable use of robotic systems. Therefore, the purpose of this study was to quantify a 6-DOF robotic system's repeatability during knee biomechanical testing and characterize the error induced in passive path repeatability by removing and reinstalling the knee. We hypothesized removing and reinstalling the knee would substantially alter passive path repeatability. Testing was performed on four fresh-frozen cadaver knees. To determine repeatability and reproducibility, the passive path was collected three times per knee following the initial setup (intra-setup), and a single time following two subsequent re-setups (inter-setup). Repeatability was calculated as root mean square error. The intra-setup passive path had a position repeatability of 0.23 mm. In contrast, inter-setup passive paths had a position repeatability of 0.89 mm. When a previously collected passive path was replayed following re-setup of the knee, resultant total force repeatability across the passive path increased to 28.2N (6.4N medial-lateral, 25.4N proximal-distal, and 10.5 N anterior-posterior). This study demonstrated that removal and re-setup of a knee can have substantial, clinically significant changes on our system's repeatability and ultimately, accuracy of the reported results. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  14. Optimal component sizing in a two-reservoir passive energy harvesting system

    NASA Astrophysics Data System (ADS)

    Munsing, E.; Cowell, M.; Moura, S.; Wright, P.

    2016-11-01

    We utilize particle swarm optimization to reduce the size of the energy management components in an energy harvesting system, allowing us to eliminate the need for voltage regulators or DC-DC converters without affecting system performance. Prior literature on optimal power management in microelectronics [1, 2] has relied on engineering estimates or exhaustive parameter searches to optimize system design. No prior literature has considered the optimal design of a device with only passive components [3]. By using particle swarm optimization, we demonstrate a 55% reduction in device size relative to conventional engineering calculations of an optimal device design.

  15. Failure of ubiquitin proteasome system: risk for neurodegenerative diseases.

    PubMed

    Zheng, Chen; Geetha, Thangiah; Babu, Jeganathan Ramesh

    2014-01-01

    The ubiquitin proteasome system (UPS) is the primary proteolytic quality control system in cells and has an essential function in the nervous system. UPS dysfunction has been linked to neurodegenerative conditions, including Alzheimer's, Parkinson's and Huntington's diseases. The pathology of neurodegenerative diseases is characterized by the abnormal accumulation of insoluble protein aggregates or inclusion bodies within neurons. The failure or dysregulation of the UPS prevents the degradation of misfolded/aberrant proteins, leading to deficient synaptic function that eventually affects the nervous system. In this review, we discuss the UPS and its physiological roles in the nervous system, its influence on neuronal function, and how UPS dysfunction contributes to the development of neurodegenerative diseases. © 2014 S. Karger AG, Basel.

  16. ISSUES ASSOCIATED WITH PROBABILISTIC FAILURE MODELING OF DIGITAL SYSTEMS

    SciTech Connect

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

    2004-09-19

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

  17. Providing the Basis for Innovative Improvements in Advanced LWR Reactor Passive Safety Systems Design: An Educational R&D Project

    SciTech Connect

    Brian G. Williams; Jim C. P. Liou; Hiral Kadakia; Bill Phoenix; Richard R. Schultz

    2007-02-27

    This project characterizes typical two-phase stratified flow conditions in advanced water reactor horizontal pipe sections, following activation of passive cooling systems. It provides (1) a means to educate nuclear engineering students regarding the importance of two-phase stratified flow in passive cooling systems to the safety of advanced reactor systems and (2) describes the experimental apparatus and process to measure key parameters essential to consider when designing passive emergency core cooling flow paths that may encounter this flow regime. Based on data collected, the state of analysis capabilities can be determined regarding stratified flow in advanced reactor systems and the best paths forward can be identified to ensure that the nuclear industry can properly characterize two-phase stratified flow in passive emergency core cooling systems.

  18. Function Test of an Automatic Locking and Unlocking System for Passive Damper by using Parabolic Flight

    NASA Astrophysics Data System (ADS)

    Sakurai, M.; Yoshihara, S.; Ohnishi, M.; Watanabe, K.; Sekiya, T.

    2002-01-01

    existence of residual acceleration has been reported.The acceleration is called "g-jitter".In a lot of experiments carried out in space, the adverse influence of the g-jitter on their results has been found out.To understand the effect of g-jitter on fluid phenomena, we are making preparation to orbital experiment as a post-JUSTSAP. In the experiment, the information to understand the influence of the g-jitter on diffusion phenomena will be obtained by comparing diffusion process in two containers. One container is isolated from the g-jitter using a passive damper and the other is not. To avoid the strong accelerations during launch giving damage to the passive damper, an automatic locking and unlocking system for the passive damper must be applied to the experimental apparatus. To increase flight opportunity of the experiment, the apparatus is designed as a small, light, self-controlled and self-powered system.In order to test the function of the apparatus, we have carried out parabolic flight experiments as preparations for the orbital experiment. mol/l), ethanol (0.7%) and NaCl (0.02 mol/l) is set on the upper base plate, which has the passive damper and the locking-unlocking system.The other container is directly set on the lower base plate.The passive damper comprises of flexible membranes and thin-metal plate and connecting rods. The damping is performed under micro-gravity condition by utilizing the non-linear elasticity of flexible membranes. The CPU unit on the upper base plate has 8 channels of A/D converter to measure 3-dimensional vibrations and 8 relays to control all experimental procedures, that is, locking, unlocking, heating, recording and so on. The power unit provides electricity to the CPU unit, the locking-unlocking system and heaters. A digital camera records diffusion of color in both cells simultaneously. color between pH8.3 and pH10. airplane vibrations were directly translated to the experimental container.During a parabolic flight, a

  19. Enhancing VHTR passive safety and economy with thermal radiation based direct reactor auxiliary cooling system

    SciTech Connect

    Zhao, H.; Zhang, H.; Zou, L.; Sun, X.

    2012-07-01

    One of the most important requirements for Gen. IV Very High Temperature Reactor (VHTR) is passive safety. Currently all the gas cooled version of VHTR designs use Reactor Vessel Auxiliary Cooling System (RVACS) for passive decay heat removal. The RVACS can be characterized as a surface-based decay heat removal system. It is especially suitable for smaller power reactors since small systems have relatively larger surface area to volume ratio. However, RVACS limits the maximum achievable power level for modular VHTRs due to the mismatch between the reactor power (proportional to the core volume) and decay heat removal capability (proportional to the vessel surface area). Besides the safety considerations, VHTRs also need to be economical in order to compete with other reactor concepts and other types of energy sources. The limit of decay heat removal capability set by using RVACS has affected the economy of VHTRs. A potential alternative solution is to use a volume-based passive decay heat removal system, called Direct Reactor Auxiliary Cooling Systems (DRACS), to remove or mitigate the limitation on decay heat removal capability. DRACS composes of natural circulation loops with two sets of heat exchangers, one on the reactor side and another on the environmental side. For the reactor side, cooling pipes will be inserted into holes made in the outer or inner graphite reflector blocks. There will be gaps or annular regions formed between these cooling pipes and their corresponding surrounding graphite surfaces. Graphite has an excellent heat conduction property. By taking advantage of this feature, we can have a volume-based method to remove decay heat. The scalability can be achieved, if needed, by employing more rows of cooling pipes to accommodate higher decay heat rates. Since heat can easily conduct through the graphite regions among the holes made for the cooling pipes, those cooling pipes located further away from the active core region can still be very

  20. Passive mitigation strategies for mode instabilities in high-power fiber laser systems.

    PubMed

    Jauregui, Cesar; Otto, Hans-Jürgen; Stutzki, Fabian; Jansen, Florian; Limpert, Jens; Tünnermann, Andreas

    2013-08-12

    Mode instabilities have quickly become the most limiting effect when it comes to scaling the output average power of fiber laser systems. In consequence, there is an urgent need for effective strategies to mitigate it and, thus, to increase the power threshold at which it appears. Passive mitigation strategies can be classified into intrinsic, which are related to the fiber design, and extrinsic, which require a modification of the setup. In order to evaluate the impact of mitigation strategies, a means to calculate its power threshold and predict its behavior is required. In this paper we present a simple semi-analytic formula that is able to predict the changes of the mode instability threshold by analyzing the strength of the thermally-induced waveguide perturbations. Furthermore, we propose two passive mitigation strategies, one intrinsic and one extrinsic, that should lead to a significant increase of the power threshold of mode instabilities.

  1. Experimental active and passive dosimetry systems for the NASA Skylab program

    NASA Technical Reports Server (NTRS)

    Schneider, M. F.; Janni, J. F.; Ainsworth, G. C.

    1972-01-01

    Active and passive dosimetry instrumentation to measure absorbed dose, charged particle spectra, and linear energy transfer spectra inside the command module and orbital workshop on the Skylab program were developed and tested. The active dosimetry system consists of one integral unit employing both a tissue equivalent ionization chamber and silicon solid state detectors. The instrument measures dose rates from 0.2 millirad/hour to 25 rads/hour, linear energy transfer spectra from 2.8 to 42.4 Kev/micron, and the proton and alpha particle energy spectra from 0.5 to 75 Mev. The active dosimeter is equipped with a portable radiation sensor for use in astronaut on-body and spacecraft shielding surveys during passage of the Skylab through significant space radiations. Data are transmitted in real time or are recorded by onboard spacecraft tape recorder for rapid evaluation of the radiation levels. The passive dosimetry systems consist of twelve (12) hard-mounted assemblies, each containing a variety of passive radiation sensors which are recoverable at the end of the mission for analysis.

  2. Corrosion control when using passively treated abandoned mine drainage as alternative makeup water for cooling systems.

    PubMed

    Hsieh, Ming-Kai; Chien, Shih-Hsiang; Li, Heng; Monnell, Jason D; Dzombak, David A; Vidic, Radisav D

    2011-09-01

    Passively treated abandoned mine drainage (AMD) is a promising alternative to fresh water as power plant cooling water system makeup water in mining regions where such water is abundant. Passive treatment and reuse of AMD can avoid the contamination of surface water caused by discharge of abandoned mine water, which typically is acidic and contains high concentrations of metals, especially iron. The purpose of this study was to evaluate the feasibility of reusing passively treated AMD in cooling systems with respect to corrosion control through laboratory experiments and pilot-scale field testing. The results showed that, with the addition of the inhibitor mixture orthophosphate and tolyltriazole, mild steel and copper corrosion rates were reduced to acceptable levels (< 0.127 mm/y and < 0.0076 mm/y, respectively). Aluminum had pitting corrosion problems in every condition tested, while cupronickel showed that, even in the absence of any inhibitor and in the presence of the biocide monochloramine, its corrosion rate was still very low (0.018 mm/y).

  3. Performance evaluation of a hybrid-passive landfill leachate treatment system using multivariate statistical techniques

    SciTech Connect

    Wallace, Jack; Champagne, Pascale; Monnier, Anne-Charlotte

    2015-01-15

    Highlights: • Performance of a hybrid passive landfill leachate treatment system was evaluated. • 33 Water chemistry parameters were sampled for 21 months and statistically analyzed. • Parameters were strongly linked and explained most (>40%) of the variation in data. • Alkalinity, ammonia, COD, heavy metals, and iron were criteria for performance. • Eight other parameters were key in modeling system dynamics and criteria. - Abstract: A pilot-scale hybrid-passive treatment system operated at the Merrick Landfill in North Bay, Ontario, Canada, treats municipal landfill leachate and provides for subsequent natural attenuation. Collected leachate is directed to a hybrid-passive treatment system, followed by controlled release to a natural attenuation zone before entering the nearby Little Sturgeon River. The study presents a comprehensive evaluation of the performance of the system using multivariate statistical techniques to determine the interactions between parameters, major pollutants in the leachate, and the biological and chemical processes occurring in the system. Five parameters (ammonia, alkalinity, chemical oxygen demand (COD), “heavy” metals of interest, with atomic weights above calcium, and iron) were set as criteria for the evaluation of system performance based on their toxicity to aquatic ecosystems and importance in treatment with respect to discharge regulations. System data for a full range of water quality parameters over a 21-month period were analyzed using principal components analysis (PCA), as well as principal components (PC) and partial least squares (PLS) regressions. PCA indicated a high degree of association for most parameters with the first PC, which explained a high percentage (>40%) of the variation in the data, suggesting strong statistical relationships among most of the parameters in the system. Regression analyses identified 8 parameters (set as independent variables) that were most frequently retained for modeling

  4. A non-imaging polarized terahertz passive system for detecting and identifying concealed explosives

    NASA Astrophysics Data System (ADS)

    Karam, Mostafa A.; Meyer, Doug

    2011-06-01

    Existing terahertz THz systems for detecting concealed explosives are not capable of identifying explosive type which leads to higher false alarm rates. Moreover, some of those systems are imaging systems that invade personal privacy, and require more processing and computational resources. Other systems have no polarization preference which makes them incapable of capturing the geometric features of an explosive. In this study a non-imaging polarized THz passive system for detecting and identifying concealed explosives overcoming the forgoing shortcomings is developed. The system employs a polarized passive THz sensor in acquiring emitted data from a scene that may have concealed explosives. The acquired data are decomposed into their natural resonance frequencies, and the number of those frequencies is used as criteria in detecting the explosive presence. If the presence of an explosive is confirmed, a set of physically based retrieval algorithms is used in extracting the explosive dielectric constant/refractive index value from natural resonance frequencies and amplitudes of associated signals. Comparing the refractive index value against a database of refractive indexes of known explosives identifies the explosive type. As an application, a system having a dual polarized radiometer operating within the frequency band of 0.62- 0.82 THz is presented and used in detecting and identifying person borne C-4 explosive concealed under a cotton garment. The system showed higher efficiencies in detecting and identifying the explosive.

  5. Failure analysis for micro-electrical-mechanical systems (MEMS)

    SciTech Connect

    Peterson, K.A.; Tangyunyong, P.; Barton, D.L.

    1997-10-01

    Micro-Electrical Mechanical Systems (MEMS) is an emerging technology with demonstrated potential for a wide range of applications including sensors and actuators for medical, industrial, consumer, military, automotive and instrumentation products. Failure analysis (FA) of MEMS is critically needed for the successful design, fabrication, performance analysis and reliability assurance of this new technology. Many devices have been examined using techniques developed for integrated circuit analysis, including optical inspection, scanning laser microscopy (SLM), scanning electron microscopy (SEM), focused ion beam (FIB) techniques, atomic force microscopy (AFM), infrared (IR) microscopy, light emission (LE) microscopy, acoustic microscopy and acoustic emission analysis. For example, the FIB was used to microsection microengines that developed poor performance characteristics. Subsequent SEM analysis clearly demonstrated the absence of wear on gear, hub, and pin joint bearing surfaces, contrary to expectations. Another example involved the use of infrared microscopy for thermal analysis of operating microengines. Hot spots were located, which did not involve the gear or hub, but indicated contact between comb structures which drive microengines. Voltage contrast imaging proved useful on static and operating MEMS in both the SEM and the FIB and identified electrostatic clamping as a potentially significant contributor to failure mechanisms in microengines. This work describes MEMS devices, FA techniques, failure modes, and examples of FA of MEMS.

  6. FASTHELP. Integrated Circuit Failure Analysis Hypertext Help System

    SciTech Connect

    Henderson, C; Barton, D; Campbell, A; Cole, E; Mikawa, R E; Peterson, K A; Rife, J L; Soden, J M

    1994-09-30

    This software assists a failure analyst performing failure analysis on integrated circuits. The software can also be used to train inexperienced failure analysts. The software also provides a method for storing information and making it easily available to experienced failure analysts.

  7. 49 CFR 214.529 - In-service failure of primary braking system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false In-service failure of primary braking system. 214... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway...

  8. 49 CFR 214.529 - In-service failure of primary braking system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false In-service failure of primary braking system. 214... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway...

  9. 49 CFR 214.529 - In-service failure of primary braking system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false In-service failure of primary braking system. 214... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway...

  10. 49 CFR 214.529 - In-service failure of primary braking system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false In-service failure of primary braking system. 214... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway...

  11. Evaluation of layered and mixed passive treatment systems for acid mine drainage.

    PubMed

    Jeen, Sung-Wook; Mattson, Bruce

    2016-11-01

    Laboratory column tests for passive treatment systems for mine drainage from a waste rock storage area were conducted to evaluate suitable reactive mixture, system configuration, effects of influent water chemistry, and required residence time. Five columns containing straw, chicken manure, mushroom compost, and limestone (LS), in either layered or mixed configurations, were set up to simulate the treatment system. The results showed that all of the five columns removed metals of concern (i.e. Al, Cd, Co, Cu, Fe, Ni, and Zn) with a residence time of 15 h and greater. Reaction mechanisms responsible for the removal of metals may include sulfate reduction and subsequent sulfide precipitation, precipitation of secondary carbonates and hydroxides, co-precipitation, and sorption on organic substrates and secondary precipitates. The results suggest that the mixed systems containing organic materials and LS perform better than the layered systems, sequentially treated by organic and LS layers, due to the enhanced pH adjustment, which is beneficial to bacterial activity and precipitation of secondary minerals. The column tests provide a basis for the design of a field-scale passive treatment system, such as a reducing and alkalinity producing system or a permeable reactive barrier.

  12. Performance of commercially available Passive Integrated Transponder (PIT) tag systems used for fish identification and interjurisdictional fisheries management

    USDA-ARS?s Scientific Manuscript database

    Passive integrated transponder (PIT) tag systems are commonly used for identification and monitoring programs with fisheries applications. Transponders of different frequencies, sizes, and code formats are available from numerous manufacturers, and there is an increasing concern regarding the need ...

  13. Feasibility study of an MR damper-based smart passive control system employing an electromagnetic induction device

    NASA Astrophysics Data System (ADS)

    Choi, Kang-Min; Jung, Hyung-Jo; Lee, Heon-Jae; Cho, Sang-Won

    2007-12-01

    The feasibility of a newly developed smart passive control system equipped electromagnetic induction device is experimentally investigated. An electromagnetic induction device consists of a permanent magnet and a solenoid, which produces electrical energy (i.e. induced current) according to Faraday's law of electromagnetic induction. The produced energy is applied to the magnetorheological (i.e. MR) damper to change the damping characteristics by itself without any controller or corresponding sensors for reducing structural responses. Recently, the smart passive control system was conceptually and numerically introduced without consideration of its practical applicability. This paper describes the design of an electromagnetic inductive device which is composed of a permanent magnet and a solenoid, and experiments with the MR damper-based smart passive control system on a shaking table which produces various sinusoidal and random excitations. The experimental results demonstrate that it is feasible to apply the smart passive control system equipped electromagnetic induction device for changing the damping characteristics of an MR damper.

  14. Combined Active and Passive Solar Space Heating and Solar Hot Water Systems for an Elementary School in Boise, Idaho.

    ERIC Educational Resources Information Center

    Smull, Neil A.; Armstrong, Gerald L.

    1979-01-01

    Amity Elementary School in Boise, Idaho, features a solar space heating and domestic hot water system along with an earth covering to accommodate the passive aspects of energy conservation. (Author/MLF)

  15. Combined Active and Passive Solar Space Heating and Solar Hot Water Systems for an Elementary School in Boise, Idaho.

    ERIC Educational Resources Information Center

    Smull, Neil A.; Armstrong, Gerald L.

    1979-01-01

    Amity Elementary School in Boise, Idaho, features a solar space heating and domestic hot water system along with an earth covering to accommodate the passive aspects of energy conservation. (Author/MLF)

  16. Passive, Direct-Read Monitoring System for Selective Detection and Quantification of Hydrogen Chloride

    NASA Technical Reports Server (NTRS)

    Chapman, K. B.; Mihaylov, G. M.; Kirollos, K. S.

    2000-01-01

    Monitoring the exposure of an employee to hydrogen chloride or hydrochloric acid in the presence of other acids has been a challenge to the industrial hygiene community. The capability of a device to differentiate the levels of acid vapors would allow for more accurate determinations of exposure and therefore improved occupational health. In this work, a selective direct-read colorimetric badge system was validated for Short Term Exposure Limit (STEL) monitoring of hydrogen chloride. The passive colorimetric badge system consists of a direct reading badge and a color scale. The badge has a coated indicator layer with a diffusive resistance in the shape of an exclamation mark. An exclamation mark will appear if hydrogen chloride is present in the atmosphere at concentrations at or above 2.0 ppm. By using the color scale, the intensity of the color formed on the badge can be further quantified up to 25 ppm. The system was validated according to a protocol based on the NIOSH Protocol for the Evaluation of Passive Monitors. The badge was exposed to relative humidities ranging from 11% to 92%, temperatures ranging from 7 C to 400 C and air velocities ranging from 5 cm/sec to 170 cm/sec. All experiments were conducted in a laboratory vapor generation system. Hydrofluoric acid, nitric acid, sulfuric acid, chlorine, hydrogen sulfide and organic acids showed no effect on the performance of the hydrogen chloride monitoring system. The passive badge and color scale system exceeded the accuracy requirements as defined by NIOSH. At ambient conditions, the mean coefficient of variation was 10.86 and the mean bias was 1.3%. This data was presented previously at the American Industrial Hygiene Conference and Exposition in Toronto, Canada in June 1999.

  17. Passive, Direct-Read Monitoring System for Selective Detection and Quantification of Hydrogen Chloride

    NASA Technical Reports Server (NTRS)

    Chapman, K. B.; Mihaylov, G. M.; Kirollos, K. S.

    2000-01-01

    Monitoring the exposure of an employee to hydrogen chloride or hydrochloric acid in the presence of other acids has been a challenge to the industrial hygiene community. The capability of a device to differentiate the levels of acid vapors would allow for more accurate determinations of exposure and therefore improved occupational health. In this work, a selective direct-read colorimetric badge system was validated for Short Term Exposure Limit (STEL) monitoring of hydrogen chloride. The passive colorimetric badge system consists of a direct reading badge and a color scale. The badge has a coated indicator layer with a diffusive resistance in the shape of an exclamation mark. An exclamation mark will appear if hydrogen chloride is present in the atmosphere at concentrations at or above 2.0 ppm. By using the color scale, the intensity of the color formed on the badge can be further quantified up to 25 ppm. The system was validated according to a protocol based on the NIOSH Protocol for the Evaluation of Passive Monitors. The badge was exposed to relative humidities ranging from 11% to 92%, temperatures ranging from 7 C to 400 C and air velocities ranging from 5 cm/sec to 170 cm/sec. All experiments were conducted in a laboratory vapor generation system. Hydrofluoric acid, nitric acid, sulfuric acid, chlorine, hydrogen sulfide and organic acids showed no effect on the performance of the hydrogen chloride monitoring system. The passive badge and color scale system exceeded the accuracy requirements as defined by NIOSH. At ambient conditions, the mean coefficient of variation was 10.86 and the mean bias was 1.3%. This data was presented previously at the American Industrial Hygiene Conference and Exposition in Toronto, Canada in June 1999.

  18. Weld monitor and failure detector for nuclear reactor system

    DOEpatents

    Sutton, Jr., Harry G.

    1987-01-01

    Critical but inaccessible welds in a nuclear reactor system are monitored throughout the life of the reactor by providing small aperture means projecting completely through the reactor vessel wall and also through the weld or welds to be monitored. The aperture means is normally sealed from the atmosphere within the reactor. Any incipient failure or cracking of the weld will cause the environment contained within the reactor to pass into the aperture means and thence to the outer surface of the reactor vessel where its presence is readily detected.

  19. Spacecraft dynamics characterization and control system failure detection

    NASA Astrophysics Data System (ADS)

    Vandervelde, Wallace E.

    1990-08-01

    Two important aspects of the control of large space structures are studied: the modeling of deployed or erected structures including nonlinear joint characteristics; and the detection and isolation of failures of the components of control systems for large space structures. The emphasis in the first task is on efficient representation of the dynamics of large and complex structures having a great many joints. The initial emphasis in the second task is on experimental evaluation of FDI methodologies using ground-based facilities in place at NASA Langley Research Center and Marshall Space Flight Center. The progress to date on both research tasks is summarized.

  20. Spacecraft dynamics characterization and control system failure detection

    NASA Technical Reports Server (NTRS)

    Vandervelde, Wallace E.

    1990-01-01

    Two important aspects of the control of large space structures are studied: the modeling of deployed or erected structures including nonlinear joint characteristics; and the detection and isolation of failures of the components of control systems for large space structures. The emphasis in the first task is on efficient representation of the dynamics of large and complex structures having a great many joints. The initial emphasis in the second task is on experimental evaluation of FDI methodologies using ground-based facilities in place at NASA Langley Research Center and Marshall Space Flight Center. The progress to date on both research tasks is summarized.

  1. Passive pavement-mounted acoustical linguistic drive alert system and method

    DOEpatents

    Kisner, Roger A.; Anderson, Richard L.; Carnal, Charles L.; Hylton, James O.; Stevens, Samuel S.

    2001-01-01

    Systems and methods are described for passive pavement-mounted acoustical alert of the occupants of a vehicle. A method of notifying a vehicle occupant includes providing a driving medium upon which a vehicle is to be driven; and texturing a portion of the driving medium such that the textured portion interacts with the vehicle to produce audible signals, the textured portion pattern such that a linguistic message is encoded into the audible signals. The systems and methods provide advantages because information can be conveyed to the occupants of the vehicle based on the location of the vehicle relative to the textured surface.

  2. Active and passive calcium transport systems in plant cells: Progress report, January 1986--June 1989

    SciTech Connect

    Sze, H.

    1989-01-01

    The objectives of this proposal are to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells. Several different energy-dependent Ca transport systems have been identified and characterized from oat root tissue (a monocot tissue) and carrot suspension cells (a dicot tissue). They are described in more detail below. I also have included in this progress report our continuing studies to understand the mode of action of the Helminthosporium maydis T toxin. This study was initially supported by a preceding DOE grant. The time needed to complete the study overlapped partly with the present grant period.

  3. A passive autofocus system by using standard deviation of the image on a liquid lens

    NASA Astrophysics Data System (ADS)

    Rasti, Pejman; Kesküla, Arko; Haus, Henry; Schlaak, Helmut F.; Anbarjafari, Gholamreza; Aabloo, Alvo; Kiefer, Rudolf

    2015-04-01

    Today most of applications have a small camera such as cell phones, tablets and medical devices. A micro lens is required in order to reduce the size of the devices. In this paper an auto focus system is used in order to find the best position of a liquid lens without any active components such as ultrasonic or infrared. In fact a passive auto focus system by using standard deviation of the images on a liquid lens which consist of a Dielectric Elastomer Actuator (DEA) membrane between oil and water is proposed.

  4. Passive Gas-Gap Heat Switches for Use in Low-Temperature Cryogenic Systems

    NASA Technical Reports Server (NTRS)

    Kimball, M. O.; Shirron, P. J.; Canavan, E. R.; Tuttle, J. G.; Jahromi, A. E.; Dipirro, M. J.; James, B. L.; Sampson, M. A.; Letmate, R. V.

    2017-01-01

    We present the current state of development in passive gas-gap heat switches. This type of switch does not require a separate heater to activate heat transfer but, instead, relies upon the warming of one end due to an intrinsic step in a thermodynamic cycle to raise a getter above a threshold temperature. Above this temperature sequestered gas is released to couple both sides of the switch. This enhances the thermodynamic efficiency of the system and reduces the complexity of the control system. Various gas mixtures and getter configurations will be presented.

  5. Municipal waste stabilization in a reactor with an integrated active and passive aeration system.

    PubMed

    Kasinski, Slawomir; Slota, Monika; Markowski, Michal; Kaminska, Anna

    2016-04-01

    To test whether an integrated passive and active aeration system could be an effective solution for aerobic decomposition of municipal waste in technical conditions, a full-scale composting reactor was designed. The waste was actively aerated for 5d, passively aerated for 35 d, and then actively aerated for 5d, and the entire composting process was monitored. During the 45-day observation period, changes in the fractional, morphological and physico-chemical characteristics of the waste at the top of the reactor differed from those in the center of the reactor. The fractional and morphological analysis made during the entire process of stabilization, showed the total reduction of organic matter measured of 82 wt% and 86 wt% at the respective depths. The reduction of organic matter calculated using the results of Lost of Ignition (LOI) and Total Organic Carbon (TOC) showed, respectively, 40.51-46.62% organic matter loss at the top and 45.33-53.39% in the center of the reactor. At the end of the process, moisture content, LOI and TOC at the top were 3.29%, 6.10% and 4.13% higher, respectively, than in the center. The results showed that application of passive aeration in larger scale simultaneously allows the thermophilic levels to be maintained during municipal solid waste composting process while not inhibiting microbial activity in the reactor.

  6. Advanced phase change materials and systems for solar passive heating and cooling of residential buildings

    SciTech Connect

    Salyer, I.O.; Sircar, A.K.; Dantiki, S.

    1988-01-01

    During the last three years under the sponsorship of the DOE Solar Passive Division, the University of Dayton Research Institute (UDRI) has investigated four phase change material (PCM) systems for utility in thermal energy storage for solar passive heating and cooling applications. From this research on the basis of cost, performance, containment, and environmental acceptability, we have selected as our current and most promising series of candidate phase change materials, C-15 to C-24 linear crystalline alkyl hydrocarbons. The major part of the research during this contract period was directed toward the following three objectives. Find, test, and develop low-cost effective phase change materials (PCM) that melt and freeze sharply in the comfort temperature range of 73--77{degree}F for use in solar passive heating and cooling of buildings. Define practical materials and processes for fire retarding plasterboard/PCM building products. Develop cost-effective methods for incorporating PCM into building construction materials (concrete, plasterboard, etc.) which will lead to the commercial manufacture and sale of PCM-containing products resulting in significant energy conservation.

  7. Research of aberration properties and passive athermalization of optical systems for infrared region

    NASA Astrophysics Data System (ADS)

    Romanova, Galina E.; Pyś, Grzegorz

    2015-09-01

    Infrared optical systems are widely used for surveillance, military and many other purposes. Image quality of such systems should be stable over wide working temperature range from - 40 up to +60°C. Due to temperature dependence of properties of optical materials and mechanical parts it is a difficult task to achieve the required stability. Passive and active methods exist to compensate the most significant aberration - so called thermal defocus. Passive compensation ways are the most attractive because complicated mechanical parts or devices are not required. The work is aimed at developing and improving of the IR system design methods. The analysis of thermoaberrations starts with analysis of possibilities of chromatic and thermal defocus correction in two and three component systems. Based on these results the development and improvement of the design method which was proposed earlier was implemented. Examples of designed systems are given. Results of the work may be helpful for designers to find optimal material combination for further designing of thermostabilized systems working in IR region.

  8. Ambient-Temperature Passive Magnetic Bearings for Flywheel Energy Storage Systems

    SciTech Connect

    Bender, D.; Post, R.

    2000-05-26

    Based on prior work at the Lawrence Livermore National Laboratory ambient-temperature passive magnetic bearings are being adapted for use in high-power flywheel energy storage systems developed at the Trinity Flywheel Power company. En route to this goal specialized test stands have been built and computer codes have been written to aid in the development of the component parts of these bearing systems. The Livermore passive magnetic bearing system involves three types of elements, as follows: (1) Axially symmetric levitation elements, energized by permanent magnets., (2) electrodynamic ''stabilizers'' employing axially symmetric arrays of permanent magnet bars (''Halbach arrays'') on the rotating system, interacting with specially wound electrically shorted stator circuits, and, (3) eddy-current-type vibration dampers, employing axially symmetric rotating pole assemblies interacting with stationary metallic discs. The theory of the Livermore passive magnetic bearing concept describes specific quantitative stability criteria. The satisfaction of these criteria will insure that, when rotating above a low critical speed, a bearing system made up of the three elements described above will be dynamically stable. That is, it will not only be stable for small displacements from equilibrium (''Earnshaw-stable''), but will also be stable against whirl-type instabilities of the types that can arise from displacement-dependent drag forces, or from mechanical-hysteritic losses that may occur in the rotor. Our design problem thus becomes one of calculating and/or measuring the relevant stiffnesses and drag coefficients of the various elements and comparing our results with the theory so as to assure that the cited stability criteria are satisfied.

  9. Failure Mechanism for Thermal Fatigue of Thermal Barrier Coating Systems

    NASA Astrophysics Data System (ADS)

    Giolli, C.; Scrivani, A.; Rizzi, G.; Borgioli, F.; Bolelli, G.; Lusvarghi, L.

    2009-06-01

    Thick thermal barrier coatings (TBCs), consisting of a CoNiCrAlY bond coat and yttria-partially stabilized zirconia top coat with different porosity values, were produced by air plasma spray (APS). The thermal fatigue resistance limit of the TBCs was tested by furnace cycling tests (FCT) according to the specifications of an original equipment manufacturer (OEM). The morphology, residual stresses, and micromechanical properties (microhardness, indentation fracture toughness) of the TBC systems before and after FCT were analyzed. The thermal fatigue resistance increases with the amount of porosity in the top coat. The compressive in-plane stresses increase in the TBC systems after thermal cycling; nevertheless the increasing rate has a trend contrary to the porosity level of top coat. The data suggest that the spallation happens at the TGO/top coat interface. The failure mechanism of thick TBCs was found to be similar to that of conventional thin TBC systems made by APS.

  10. Processing resource demands of failure detection in dynamic systems.

    PubMed

    Wickens, C D; Kessel, C

    1980-08-01

    The information-processing channels, proprioceptive versus visual, that are used to detect changes in the response of dynamic systems are investigated using a loading-task methodology. Conditions are compared in which subjects either control the dynamic system (MA mode) or monitor an autopilot controlling the same system (AU mode). Failure detection in these two modes of participation is evaluated when subjects perform the task alone and concurrently with either a tracking loading task or a mental arithmetic-memory loading task. The former task disrupted MA detection but not AU detection, whereas the converse results were obtained with the mental-arithmetic task. The results, interpreted within the framework of a structure-specific resource theory of human attention, suggest that AU detection relies exclusively on processing resources associated with perceptual/central-processing stages. MA detection in contrast relies on separate-processing resources residing in a response-related reservoir.

  11. Application of a passive/active autoparametric cantilever beam absorber with PZT actuator for Duffing systems

    NASA Astrophysics Data System (ADS)

    Silva-Navarro, G.; Abundis-Fong, H. F.; Vazquez-Gonzalez, B.

    2013-04-01

    An experimental investigation is carried out on a cantilever-type passive/active autoparametric vibration absorber, with a PZT patch actuator, to be used in a primary damped Duffing system. The primary system consists of a mass, viscous damping and a cubic stiffness provided by a soft helical spring, over which is mounted a cantilever beam with a PZT patch actuator actively controlled to attenuate harmonic and resonant excitation forces. With the PZT actuator on the cantilever beam absorber, cemented to the base of the beam, the auto-parametric vibration absorber is made active, thus enabling the possibility to control the effective stiffness and damping associated to the passive absorber and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty. This active vibration absorber employs feedback information from a high resolution optical encoder on the primary Duffing system and an accelerometer on the tip beam absorber, a strain gage on the base of the beam, feedforward information from the excitation force and on-line computations from the nonlinear approximate frequency response, parameterized in terms of a proportional gain provided by a voltage input to the PZT actuator, thus modifying the closed-loop dynamic stiffness and providing a mechanism to asymptotically track an optimal, robust and stable attenuation solution on the primary Duffing system. Experimental results are included to describe the dynamic and robust performance of the overall closed-loop system.

  12. Design and Transient Analysis of Passive Safety Cooling Systems for Advanced Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Galvez, Cristhian

    2011-12-01

    The Pebble Bed Advanced High Temperature Reactor (PB-AHTR) is a pebble fueled, liquid salt cooled, high temperature nuclear reactor design that can be used for electricity generation or other applications requiring the availability of heat at elevated temperatures. A stage in the design evolution of this plant requires the analysis of the plant during a variety of potential transients to understand the primary and safety cooling system response. This study focuses on the performance of the passive safety cooling system with a dual purpose, to assess the capacity to maintain the core at safe temperatures and to assist the design process of this system to achieve this objective. The analysis requires the use of complex computational tools for simulation and verification using analytical solutions and comparisons with experimental data. This investigation builds upon previous detailed design work for the PB-AHTR components, including the core, reactivity control mechanisms and the intermediate heat exchanger, developed in 2008. In addition the study of this reference plant design employs a wealth of auxiliary information including thermal-hydraulic physical phenomena correlations for multiple geometries and thermophysical properties for the constituents of the plant. Finally, the set of performance requirements and limitations imposed from physical constrains and safety considerations provide with a criteria and metrics for acceptability of the design. The passive safety cooling system concept is turned into a detailed design as a result from this study. A methodology for the design of air-cooled passive safety systems was developed and a transient analysis of the plant, evaluating a scrammed loss of forced cooling event was performed. Furthermore, a design optimization study of the passive safety system and an approach for the validation and verification of the analysis is presented. This study demonstrates that the resulting point design responds properly to the

  13. Current Perspectives on Systemic Hypertension in Heart Failure with Preserved Ejection Fraction.

    PubMed

    Tam, Marty C; Lee, Ran; Cascino, Thomas M; Konerman, Matthew C; Hummel, Scott L

    2017-02-01

    Heart failure with preserved ejection fraction (HFpEF) is a prevalent but incompletely understood syndrome. Traditional models of HFpEF pathophysiology revolve around systemic HTN and other causes of increased left ventricular afterload leading to left ventricular hypertrophy (LVH) and diastolic dysfunction. However, emerging models attribute the development of HFpEF to systemic proinflammatory changes secondary to common comorbidities which include HTN. Alterations in passive ventricular stiffness, ventricular-arterial coupling, peripheral microvascular function, systolic reserve, and chronotropic response occur. As a result, HFpEF is heterogeneous in nature, making it difficult to prescribe uniform therapies to all patients. Nonetheless, treating systemic HTN remains a cornerstone of HFpEF management. Antihypertensive therapies have been linked to LVH regression and improvement in diastolic dysfunction. However, to date, no therapies have definitive mortality benefit in HFpEF. Non-pharmacologic management for HTN, including dietary modification, exercise, and treating sleep disordered breathing, may provide some morbidity benefit in the HFpEF population. Future research is need to identify effective treatments, perhaps in more specific subgroups, and focus may need to shift from reducing mortality to improving exercise capacity and symptoms. Tailoring antihypertensive therapies to specific phenotypes of HFpEF may be an important component of this strategy.

  14. [Chronic heart failure and cachexia: role of endocrine system].

    PubMed

    Dei Cas, A; Muoio, A; Zavaroni, I

    2011-12-01

    Chronic heart failure (CHF) is a major health problem that carries a devastating prognosis. The prognosis worsens considerably once cardiac cachexia has been diagnosed. Neurohormonal, metabolic, hemodynamic and immunological alterations are involved in the initiation and progression of cardiac cachexia. Cachexia is characterized by a hypothalamic inappropriate response to the mechanisms controlling energy homeostasis. Levels of the anorexigenic hormone leptin are decreased whereas the orexigenic gherlin hormone levels are normal or elevated. Nevertheless, energy intake is not increased as expected due to a persistent activation of the proopiomelanocortin (POMC) system (anorexigenic) paralleled by a decreased activity of the neuropeptide Y (NPY, orexigenic) neurons. Cachexia is also characterized by an imbalance in anabolic (impairment in the growth hormone/insulin-like growth factor-I axis, insulin resistance) and catabolic (increased levels of catecholamines, increased cortisol/dehydroepiandrosterone ratio and activation of proinflammatory cytokines such as tumor necrosis factor-alpha, interleuchin-6, interleuchin-1') at the basis of the wasting process. This review discusses the complex role of the endocrine system in modulating energy balance, appetite and metabolism in patients with chronic heart failure. A joint multidisciplinary effort of the cardiologists, immunologists and endocrinologists might be useful to identify the precise mechanisms involved in the neuroendocrine alteration and to develop therapeutic strategies able to improve the prognosis of CHF patients.

  15. Physicochemical characterization and failure analysis of military coating systems

    NASA Astrophysics Data System (ADS)

    Keene, Lionel Thomas

    Modern military coating systems, as fielded by all branches of the U.S. military, generally consist of a diverse array of organic and inorganic components that can complicate their physicochemical analysis. These coating systems consist of VOC-solvent/waterborne automotive grade polyurethane matrix containing a variety of inorganic pigments and flattening agents. The research presented here was designed to overcome the practical difficulties regarding the study of such systems through the combined application of several cross-disciplinary techniques, including vibrational spectroscopy, electron microscopy, microtomy, ultra-fast laser ablation and optical interferometry. The goal of this research has been to determine the degree and spatial progression of weathering-induced alteration of military coating systems as a whole, as well as to determine the failure modes involved, and characterizing the impact of these failures on the physical barrier performance of the coatings. Transmission-mode Fourier Transform Infrared (FTIR) spectroscopy has been applied to cross-sections of both baseline and artificially weathered samples to elucidate weathering-induced spatial gradients to the baseline chemistry of the coatings. A large discrepancy in physical durability (as indicated by the spatial progression of these gradients) has been found between older and newer generation coatings. Data will be shown implicating silica fillers (previously considered inert) as the probable cause for this behavioral divergence. A case study is presented wherein the application of the aforementioned FTIR technique fails to predict the durability of the coating system as a whole. The exploitation of the ultra-fast optical phenomenon of femtosecond (10-15S) laser ablation is studied as a potential tool to facilitate spectroscopic depth profiling of composite materials. Finally, the interferometric technique of Phase Shifting was evaluated as a potential high-sensitivity technique applied to the

  16. Instrument Failures for the da Vinci Surgical System: a Food and Drug Administration MAUDE Database Study.

    PubMed

    Friedman, Diana C W; Lendvay, Thomas S; Hannaford, Blake

    2013-05-01

    Our goal was to analyze reported instances of the da Vinci robotic surgical system instrument failures using the FDA's MAUDE (Manufacturer and User Facility Device Experience) database. From these data we identified some root causes of failures as well as trends that may assist surgeons and users of the robotic technology. We conducted a survey of the MAUDE database and tallied robotic instrument failures that occurred between January 2009 and December 2010. We categorized failures into five main groups (cautery, shaft, wrist or tool tip, cable, and control housing) based on technical differences in instrument design and function. A total of 565 instrument failures were documented through 528 reports. The majority of failures (285) were of the instrument's wrist or tool tip. Cautery problems comprised 174 failures, 76 were shaft failures, 29 were cable failures, and 7 were control housing failures. Of the reports, 10 had no discernible failure mode and 49 exhibited multiple failures. The data show that a number of robotic instrument failures occurred in a short period of time. In reality, many instrument failures may go unreported, thus a true failure rate cannot be determined from these data. However, education of hospital administrators, operating room staff, surgeons, and patients should be incorporated into discussions regarding the introduction and utilization of robotic technology. We recommend institutions incorporate standard failure reporting policies so that the community of robotic surgery companies and surgeons can improve on existing technologies for optimal patient safety and outcomes.

  17. Evolving Systems: Adaptive Key Component Control and Inheritance of Passivity and Dissipativity

    NASA Technical Reports Server (NTRS)

    Frost, S. A.; Balas, M. J.

    2010-01-01

    We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. Autonomous assembly of large, complex flexible structures in space is a target application for Evolving Systems. A critical requirement for autonomous assembling structures is that they remain stable during and after assembly. The fundamental topic of inheritance of stability, dissipativity, and passivity in Evolving Systems is the primary focus of this research. In this paper, we develop an adaptive key component controller to restore stability in Nonlinear Evolving Systems that would otherwise fail to inherit the stability traits of their components. We provide sufficient conditions for the use of this novel control method and demonstrate its use on an illustrative example.

  18. Simultaneous active and passive control for eigenstructure assignment in lightly damped systems

    NASA Astrophysics Data System (ADS)

    Richiedei, Dario; Trevisani, Alberto

    2017-02-01

    The assignment of the eigenstructure (i.e. eigenvalues and eigenvectors) in vibrating systems is an effective way to improve their dynamic performances. System controllability ensures that the poles of the controlled system are exactly assigned but it does not allow to assign arbitrary desired eigenvectors. To this purpose, this paper proposes a novel method for vibration control in lightly damped systems through the concurrent synthesis of passive structural modifications and active state (or state derivative) feedback control gains. Indeed, the suitable modification of the inertial and elastic parameters allows to enlarge the range of assignable eigenvectors. The problem is formulated as an optimization problem, where constraints are introduced to assure the feasibility of the physical system modifications while avoiding spillover phenomena. The experimental application to the eigenstructure assignment on a manipulator proves the method effectiveness.

  19. Global asymptotic stabilisation in probability of nonlinear stochastic systems via passivity

    NASA Astrophysics Data System (ADS)

    Florchinger, Patrick

    2016-07-01

    The purpose of this paper is to develop a systematic method for global asymptotic stabilisation in probability of nonlinear control stochastic systems with stable in probability unforced dynamics. The method is based on the theory of passivity for nonaffine stochastic differential systems combined with the technique of Lyapunov asymptotic stability in probability for stochastic differential equations. In particular, we prove that a nonlinear stochastic differential system whose unforced dynamics are Lyapunov stable in probability is globally asymptotically stabilisable in probability provided some rank conditions involving the affine part of the system coefficients are satisfied. In this framework, we show that a stabilising smooth state feedback law can be designed explicitly. A dynamic output feedback compensator for a class of nonaffine stochastic systems is constructed as an application of our analysis.

  20. Conceptual Design of Passive Safety System for Lead-Bismuth Cooled Fast Reactor

    NASA Astrophysics Data System (ADS)

    Abdullah, A. G.; Nandiyanto, A. B. D.

    2016-04-01

    This paper presents the results of the conceptual design of passive safety systems for reactor power 225 MWth using Pb-Bi coolant. Main purpose of this research is to design of heat removal system from the reactor wall. The heat from the reactor wall is removed by RVACS system using the natural circulation from the atmosphere around the reactor at steady state. The calculation is performed numerically using Newton-Raphson method. The analysis involves the heat transfer systems in a radiation, conduction and natural convection. Heat transfer calculations is performed on the elements of the reactor vessel, outer wall of guard vessel and the separator plate. The simulation results conclude that the conceptual design is able to remove heat 1.33% to 4.67% from the thermal reactor power. It’s can be hypothesized if the reactor had an accident, the system can still overcome the heat due to decay.

  1. Effect of Component Failures on Economics of Distributed Photovoltaic Systems

    SciTech Connect

    Lubin, Barry T.

    2012-02-02

    both. Some societal benefits associated with financial benefits to the utility of having a distributed generation capacity that is not fossil-fuel based have been included into the economic models. Also included and quantified in the models are several benefits to society more generally: job creation and some estimates of benefits from avoiding greenhouse emissions. PV system failures result in a lowering of the economic values of a grid-connected system, but this turned out to be a surprisingly small effect on the overall economics. The most significant benefit noted resulted from including the societal benefits accrued to the utility. This provided a marked increase in the valuations of the array and made the overall value proposition a financially attractive one, in that net present values exceeded installation costs. These results indicate that the Department of Energy and state regulatory bodies should consider focusing on societal benefits that create economic value for the utility, confirm these quantitative values, and work to have them accepted by the utilities and reflected in the rate structures for power obtained from grid-connected arrays. Understanding and applying the economic benefits evident in this work can significantly improve the business case for grid-connected PV installations. This work also indicates that the societal benefits to the population are real and defensible, but not nearly as easy to justify in a business case as are the benefits that accrue directly to the utility.

  2. Passive-performance, analysis, and upgrades of a 1-ton seismic attenuation system

    NASA Astrophysics Data System (ADS)

    Bergmann, G.; Mow-Lowry, C. M.; Adya, V. B.; Bertolini, A.; Hanke, M. M.; Kirchhoff, R.; Köhlenbeck, S. M.; Kühn, G.; Oppermann, P.; Wanner, A.; Westphal, T.; Wöhler, J.; Wu, D. S.; Lück, H.; Strain, K. A.; Danzmann, K.

    2017-03-01

    The 10 m prototype facility at the Albert-Einstein-institute (AEI) in Hanover, Germany, employs three large seismic attenuation systems to reduce mechanical motion. The AEI seismic-attenuation-system (AEI-SAS) uses mechanical anti-springs in order to achieve resonance frequencies below 0.5 Hz. This system provides passive isolation from ground motion by a factor of about 400 in the horizontal direction at 4 Hz and in the vertical direction at 9 Hz. The presented isolation performance is measured under vacuum conditions using a combination of commercial and custom-made inertial sensors. Detailed analysis of this performance led to the design and implementation of tuned dampers to mitigate the effect of the unavoidable higher order modes of the system. These dampers reduce RMS motion substantially in the frequency range between 10 and 100 Hz in 6 degrees of freedom. The results presented here demonstrate that the AEI-SAS provides substantial passive isolation at all the fundamental mirror-suspension resonances.

  3. Integration of active and passive cool roof system for attic temperature reduction

    NASA Astrophysics Data System (ADS)

    Yew, Ming Chian; Yew, Ming Kun; Saw, Lip Huat; Durairaj, Rajkumar

    2017-04-01

    The aim of this project is to study the capability of cool roof system in the reduction of heat transmission through metal roof into an attic. The cool roof system is designed in active and passive methods to reduce the thermal loads imposed to a building. Two main features are introduced to this cool roof system, which is thermal insulation coating (TIC) and moving air cavity (MAC) that served as active and passive manner, respectively. For MAC, two designs are introduced. Normal MAC is fabricated by six aluminium tubes whereby each aluminium tube is made up by sticking up of five aluminium cans. While improved MAC is also made by six aluminium tubes whereby each aluminium tube is custom made from steel rods and aluminium foils. MAC provides ventilation and heat reflection under the metal roof before the heat transfer into attic. It also coupled with three solar powered fans to increase heat flow inside the channel. The cool roof that incorporated TIC, MAC with solar powered fans and opened attic inlet showed a significant improvement with a reduction of up to 14 °C in the attic temperature compared to conventional roof system.

  4. Analysis of Semi-Active and Passive Suspensions System for Off-Road Vehicles

    NASA Astrophysics Data System (ADS)

    BenLahcene, Zohir; Faris, Waleed F.; Khan, M. D. Raisuddin

    2009-03-01

    The speed of off-road vehicles over rough terrain is generally determined by the ride quality not by the engine power. For this reason, researches are currently being undertaking to improve the ride dynamics of these vehicles using an advanced suspension system. This study intends to provide a preliminary evaluation of whether semi-active suspensions are beneficial to improving ride and handling in off-road vehicles. One of the greatest challenges in designing off-road vehicle suspension system is maintaining a good balance between vehicle ride and handling. Three configurations of these vehicles; 2-axle, 3-xle and 4-axles have been studied and their performances are compared. The application of several control policies of semi-active suspension system, namely skyhook; ground-hook and hybrid controls have been analyzed and compared with passive systems. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and ground-hook control policies. Results show an improvement in ride comfort and vehicle handling using 4-axle over 3-axle and 2-axle when emphasis is placed on the response of the vehicle body acceleration, suspension and tyre deflection.

  5. A wireless demodulation system for passive surface acoustic wave torque sensor

    NASA Astrophysics Data System (ADS)

    Ji, Xiaojun; Fan, Yanping; Qi, Hongli; Chen, Jing; Han, Tao; Cai, Ping

    2014-12-01

    Surface acoustic wave (SAW) resonators are utilized as torque sensors for their passive and wireless features. However, the response of a SAW torque sensor is difficult to detect because of the transient response duration and interruption of channel noise, which limit the application of SAW torque sensors. The sensitive mechanism and response function of a passive wireless SAW torque sensor are analyzed in this study. A novel demodulation system involving both hardware and software is developed for the SAW torque sensor. A clipping amplifier is utilized in the hardware to widen the dynamic response range and increase the length of the valid signal. Correlation extension and centroid algorithms are designed to lengthen the received signal and improve the estimation accuracy of the center frequency of the response signal, respectively. Meanwhile, a fast binary search algorithm is proposed to accelerate the scanning cycle according to the developed response function. Finally, the SAW torque sensor demodulation system is set up and SAW resonators with high sensitivity are fabricated on a quartz substrate. The presented demodulation system is tested, and a standard deviation of 0.28 kHz is achieved. This value is much smaller than that of classic and modern spectrum estimation methods. The sensitivity of resonance frequency shift versus torque on the shaft of the assembled senor is 2.03 kHz/Nm; the coefficient of determination is 0.999, and the linearity is 0.87%. Experimental results verify the validity and feasibility of the proposed SAW torque sensor demodulation system.

  6. Malfunction and failure of robotic systems during general surgical procedures.

    PubMed

    Agcaoglu, Orhan; Aliyev, Shamil; Taskin, Halit Eren; Chalikonda, Sricharan; Walsh, Matthew; Costedio, Meagan M; Kroh, Matthew; Rogula, Tomasz; Chand, Bipan; Gorgun, Emre; Siperstein, Allan; Berber, Eren

    2012-12-01

    There has been recent interest in using robots for general surgical procedures. This shift in technique raises the issue of patient safety with automated instrumentation. Although the safety of robotics has been established for urologic procedures, there are scant data on its use in general surgical procedures. The aim of this study is to analyze the incidence of robotic malfunction and its consequences for general surgical procedures. All robotic general surgical procedures performed at a tertiary center between 2008 and 2011 were reviewed from institutional review board (IRB)-approved prospective databases. A total of 223 cases were done robotically, including 102 endocrine, 83 hepatopancreaticobiliary, 17 upper gastrointestinal, and 21 lower gastrointestinal colorectal procedures. There were 10 cases of robotic malfunction (4.5%). These failures were related to robotic instruments (n = 4), optical system (n = 3), robotic arms (n = 2), and robotic console (n = 1). None of these failures led to adverse patient consequences or conversion to open. Six (2.7%) cases were converted to open due to bleeding (n = 3), difficult dissection plane (n = 1), invasion of tumor to surrounding structures (n = 1), and intolerance of pneumoperitoneum due to CO(2) retention (n = 1). There was no mortality, and morbidity was 1% (n = 2). To our knowledge, this is the largest North American report to date on robotic general surgical procedures. Our results show that robotic malfunction occurs in a minority of cases, with no adverse consequences. We believe that awareness of these failures and knowing how to troubleshoot are important to maintain the efficiency of these procedures.

  7. Optical heterodyne accelerometry: passively stabilized, fully balanced velocity interferometer system for any reflector

    SciTech Connect

    Buttler, William T.; Lamoreaux, Steven K.

    2010-08-10

    We formalize the physics of an optical heterodyne accelerometer that allows measurement of low and high velocities from material surfaces under high strain. The proposed apparatus incorporates currently common optical velocimetry techniques used in shock physics, with interferometric techniques developed to self-stabilize and passively balance interferometers in quantum cryptography. The result is a robust telecom-fiber-based velocimetry system insensitive to modal and frequency dispersion that should work well in the presence of decoherent scattering processes, such as from ejecta clouds and shocked surfaces.

  8. Counter Unmanned Aerial Systems Testing: Evaluation of VIS SWIR MWIR and LWIR passive imagers.

    SciTech Connect

    Birch, Gabriel Carlisle; Woo, Bryana Lynn

    2017-01-01

    This report contains analysis of unmanned aerial systems as imaged by visible, short-wave infrared, mid-wave infrared, and long-wave infrared passive devices. Testing was conducted at the Nevada National Security Site (NNSS) during the week of August 15, 2016. Target images in all spectral bands are shown and contrast versus background is reported. Calculations are performed to determine estimated pixels-on-target for detection and assessment levels, and the number of pixels needed to cover a hemisphere for detection or assessment at defined distances. Background clutter challenges are qualitatively discussed for different spectral bands, and low contrast scenarios are highlighted for long-wave infrared imagers.

  9. Toward Interpreting Failure in Sintered-Silver Interconnection Systems

    SciTech Connect

    Wereszczak, Andrew A; Waters, Shirley B

    2016-01-01

    The mechanical strength and subsequent reliability of a sintered-silver interconnection system is a function of numerous independent parameters. That system is still undergoing process development. Most of those parameters (e.g., choice of plating) are arguably and unfortunately taken for granted and are independent of the silver s cohesive strength. To explore such effects, shear strength testing and failure analyses were completed on a simple, mock sintered-silver interconnection system consisting of bonding two DBC ceramic substrates. Silver and gold platings were part of the test matrix, as was pre-drying strategies, and the consideration of stencil-printing vs. screen-printing. Shear strength of sintered-silver interconnect systems was found to be was insensitive to the choice of plating, drying practice, and printing method provided careful and consistent processing of the sintered-silver are practiced. But if the service stress in sintered silver interconnect systems is anticipated to exceed ~ 60 MPa, then the system will likely fail.

  10. Understanding the Impact of Interconnect Failures on System Operation

    SciTech Connect

    Ezell, Matthew A

    2013-01-01

    Hardware failures are inevitable on large high performance computing systems. Faults or performance degradations in the high-speed network can reduce the entire system s performance. Since the introduction of the Gemini interconnect, Cray systems have become resilient to many networking faults that were fatal in their previous generation systems. These new network reliability and resiliency features have enabled higher uptimes on Cray systems by allowing them to continue running with reduced network performance. Oak Ridge National Laboratory has developed a set of user-level diagnostics that stresses the high-speed network and searches for components that are not performing as expected. Nearest-neighbor bandwidth tests check every network chip and network link in the system. Additionally, performance counters stored on the network ASIC s memory mapped registers (MMRs) are used to better understand the state of the network. Applications have also been characterized under various suboptimal network conditions to better understand what impact network problems have on user codes.

  11. Evaluation of five commercially available assays and measurement of serum total protein concentration via refractometry for the diagnosis of failure of passive transfer of immunity in foals.

    PubMed

    Davis, Rachel; Giguère, Steeve

    2005-11-15

    To determine and compare sensitivity, specificity, accuracy, and predictive values of measurement of serum total protein concentration by refractometry as well as 5 commercially available kits for the diagnosis of failure of passive transfer (FPT) of immunity in foals. Prospective study. 65 foals with various medical problems and 35 clinically normal foals. IgG concentration in serum was assessed by use of zinc sulfate turbidity (assay C), glutaraldehyde coagulation (assay D), 2 semiquantitative immunoassays (assays F and G), and a quantitative immunoassay (assay H). Serum total protein concentration was assessed by refractometry. Radial immunodiffusion (assays A and B) was used as the reference method. For detection of IgG < 400 mg/dL, sensitivity of assay H (100%) was not significantly different from that of assays C, E, and G (88.9%). Specificity of assays H (96.0%) and G (95.8%) was significantly higher than that of assays C (79.4%) and E (78.1 %). For detection of IgG < 800 mg/dL, sensitivities of assays H (976%), D (92.9%), C (81.0%), and G (81.0%) were significantly higher than that of assay F (52.4%). Specificity of assays F (100%), G (94.7%), and H (82.8%) was significantly higher than that of assays C (56.9%) and D (58.6%). Serum total protein concentration < or = 4.5 g/dL was suggestive of FPT, whereas values > or = 6.0 g/dL indicated adequate IgG concentrations. Most assays were adequate as initial screening tests. However, their use as a definitive test would result in unnecessary treatment of foals with adequate IgG concentrations.

  12. RECONFIGURING POWER SYSTEMS TO MINIMIZE CASCADING FAILURES: MODELS AND ALGORITHMS

    SciTech Connect

    Bienstock, Daniel

    2014-04-11

    the main goal of this project was to develop new scientific tools, based on optimization techniques, with the purpose of controlling and modeling cascading failures of electrical power transmission systems. We have developed a high-quality tool for simulating cascading failures. The problem of how to control a cascade was addressed, with the aim of stopping the cascade with a minimum of load lost. Yet another aspect of cascade is the investigation of which events would trigger a cascade, or more appropriately the computation of the most harmful initiating event given some constraint on the severity of the event. One common feature of the cascade models described (indeed, of several of the cascade models found in the literature) is that we study thermally-induced line tripping. We have produced a study that accounts for exogenous randomness (e.g. wind and ambient temperature) that could affect the thermal behavior of a line, with a focus on controlling the power flow of the line while maintaining safe probability of line overload. This was done by means of a rigorous analysis of a stochastic version of the heat equation. we incorporated a model of randomness in the behavior of wind power output; again modeling an OPF-like problem that uses chance-constraints to maintain low probability of line overloads; this work has been continued so as to account for generator dynamics as well.

  13. A Passive Wireless Multi-Sensor SAW Technology Device and System Perspectives

    PubMed Central

    Malocha, Donald C.; Gallagher, Mark; Fisher, Brian; Humphries, James; Gallagher, Daniel; Kozlovski, Nikolai

    2013-01-01

    This paper will discuss a SAW passive, wireless multi-sensor system under development by our group for the past several years. The device focus is on orthogonal frequency coded (OFC) SAW sensors, which use both frequency diversity and pulse position reflectors to encode the device ID and will be briefly contrasted to other embodiments. A synchronous correlator transceiver is used for the hardware and post processing and correlation techniques of the received signal to extract the sensor information will be presented. Critical device and system parameters addressed include encoding, operational range, SAW device parameters, post-processing, and antenna-SAW device integration. A fully developed 915 MHz OFC SAW multi-sensor system is used to show experimental results. The system is based on a software radio approach that provides great flexibility for future enhancements and diverse sensor applications. Several different sensor types using the OFC SAW platform are shown. PMID:23666124

  14. Approximate adaptive output feedback stabilization via passivation of MIMO uncertain systems using neural networks.

    PubMed

    Kostarigka, Artemis K; Rovithakis, George A

    2009-10-01

    An adaptive output feedback neural network controller is designed, which is capable of rendering affine-in-the-control uncertain multi-input-multi-output nonlinear systems strictly passive with respect to an appropriately defined set. Consequently, a simple output feedback is employed to stabilize the system. The controlled system need not be in normal form or have a well-defined relative degree. Without requiring a zero-state detectability assumption, uniform ultimate boundedness, with respect to an arbitrarily small set, of both the system's state and the output is guaranteed, along with boundedness of all other signals in the closed loop. To effectively avoid possible division by zero, the proposed adaptive controller is of switching type. However, its continuity is guaranteed, thus alleviating drawbacks connected to existence of solutions and chattering phenomena. Simulations illustrate the approach.

  15. Mitigation of steam generator tube rupture in a pressurized water reactor with passive safety systems

    DOEpatents

    McDermott, Daniel J.; Schrader, Kenneth J.; Schulz, Terry L.

    1994-01-01

    The effects of steam generator tube ruptures in a pressurized water reactor are mitigated by reducing the pressure in the primary loop by diverting reactor coolant through the heat exchanger of a passive heat removal system immersed in the in containment refueling water storage tank in response to a high feed water level in the steam generator. Reactor coolant inventory is maintained by also in response to high steam generator level introducing coolant into the primary loop from core make-up tanks at the pressure in the reactor coolant system pressurizer. The high steam generator level is also used to isolate the start-up feed water system and the chemical and volume control system to prevent flooding into the steam header. 2 figures.

  16. Mitigation of steam generator tube rupture in a pressurized water reactor with passive safety systems

    DOEpatents

    McDermott, D.J.; Schrader, K.J.; Schulz, T.L.

    1994-05-03

    The effects of steam generator tube ruptures in a pressurized water reactor are mitigated by reducing the pressure in the primary loop by diverting reactor coolant through the heat exchanger of a passive heat removal system immersed in the in containment refueling water storage tank in response to a high feed water level in the steam generator. Reactor coolant inventory is maintained by also in response to high steam generator level introducing coolant into the primary loop from core make-up tanks at the pressure in the reactor coolant system pressurizer. The high steam generator level is also used to isolate the start-up feed water system and the chemical and volume control system to prevent flooding into the steam header. 2 figures.

  17. Passive isolation/damping system for the Hubble space telescope reaction wheels

    NASA Technical Reports Server (NTRS)

    Hasha, Martin D.

    1987-01-01

    NASA's Hubble Space Telescope contain large, diffraction limited optics with extraordinary resolution and performance for surpassing existing observatories. The need to reduce structural borne vibration and resultant optical jitter from critical Pointing Control System components, Reaction Wheels, prompted the feasibility investigation and eventual development of a passive isolation system. Alternative design concepts considered were required to meet a host of stringent specifications and pass rigid tests to be successfully verified and integrated into the already built flight vehicle. The final design employs multiple arrays of fluid damped springs that attenuate over a wide spectrum, while confining newly introduced resonances to benign regions of vehicle dynamic response. Overall jitter improvement of roughly a factor of 2 to 3 is attained with this system. The basis, evolution, and performance of the isolation system, specifically discussing design concepts considered, optimization studies, development lessons learned, innovative features, and analytical and ground test verified results are presented.

  18. Passive decay heat removal system for water-cooled nuclear reactors

    DOEpatents

    Forsberg, Charles W.

    1991-01-01

    A passive decay-heat removal system for a water-cooled nuclear reactor employs a closed heat transfer loop having heat-exchanging coils inside an open-topped, insulated box located inside the reactor vessel, below its normal water level, in communication with a condenser located outside of containment and exposed to the atmosphere. The heat transfer loop is located such that the evaporator is in a position where, when the water level drops in the reactor, it will become exposed to steam. Vapor produced in the evaporator passes upward to the condenser above the normal water level. In operation, condensation in the condenser removes heat from the system, and the condensed liquid is returned to the evaporator. The system is disposed such that during normal reactor operations where the water level is at its usual position, very little heat will be removed from the system, but during emergency, low water level conditions, substantial amounts of decay heat will be removed.

  19. A passive wireless multi-sensor SAW technology device and system perspectives.

    PubMed

    Malocha, Donald C; Gallagher, Mark; Fisher, Brian; Humphries, James; Gallagher, Daniel; Kozlovski, Nikolai

    2013-05-10

    This paper will discuss a SAW passive, wireless multi-sensor system under development by our group for the past several years. The device focus is on orthogonal frequency coded (OFC) SAW sensors, which use both frequency diversity and pulse position reflectors to encode the device ID and will be briefly contrasted to other embodiments. A synchronous correlator transceiver is used for the hardware and post processing and correlation techniques of the received signal to extract the sensor information will be presented. Critical device and system parameters addressed include encoding, operational range, SAW device parameters, post-processing, and antenna-SAW device integration. A fully developed 915 MHz OFC SAW multi-sensor system is used to show experimental results. The system is based on a software radio approach that provides great flexibility for future enhancements and diverse sensor applications. Several different sensor types using the OFC SAW platform are shown.

  20. Design and fabrication of a passive droplet dispenser for portable high resolution imaging system.

    PubMed

    Kamal, Tahseen; Watkins, Rachel; Cen, Zijian; Rubinstein, Jaden; Kong, Gary; Lee, Woei Ming

    2017-01-27

    Moldless lens manufacturing techniques using standard droplet dispensing technology often require precise control over pressure to initiate fluid flow and control droplet formation. We have determined a series of interfacial fluid parameters optimised using standard 3D printed tools to extract, dispense and capture a single silicone droplet that is then cured to obtain high quality lenses. The dispensing process relies on the recapitulation of liquid dripping action (Rayleigh-Plateau instability) and the capturing method uses the interplay of gravitational force, capillary forces and liquid pinning to control the droplet shape. The key advantage of the passive lens fabrication approach is rapid scale-up using 3D printing by avoiding complex dispensing tools. We characterise the quality of the lenses fabricated using the passive approach by measuring wavefront aberration and high resolution imaging. The fabricated lenses are then integrated into a portable imaging system; a wearable thimble imaging device with a detachable camera housing, that is constructed for field imaging. This paper provides the full exposition of steps, from lens fabrication to imaging platform, necessary to construct a standalone high resolution imaging system. The simplicity of our methodology can be implemented using a regular desktop 3D printer and commercially available digital imaging systems.

  1. Design and fabrication of a passive droplet dispenser for portable high resolution imaging system

    NASA Astrophysics Data System (ADS)

    Kamal, Tahseen; Watkins, Rachel; Cen, Zijian; Rubinstein, Jaden; Kong, Gary; Lee, Woei Ming

    2017-01-01

    Moldless lens manufacturing techniques using standard droplet dispensing technology often require precise control over pressure to initiate fluid flow and control droplet formation. We have determined a series of interfacial fluid parameters optimised using standard 3D printed tools to extract, dispense and capture a single silicone droplet that is then cured to obtain high quality lenses. The dispensing process relies on the recapitulation of liquid dripping action (Rayleigh-Plateau instability) and the capturing method uses the interplay of gravitational force, capillary forces and liquid pinning to control the droplet shape. The key advantage of the passive lens fabrication approach is rapid scale-up using 3D printing by avoiding complex dispensing tools. We characterise the quality of the lenses fabricated using the passive approach by measuring wavefront aberration and high resolution imaging. The fabricated lenses are then integrated into a portable imaging system; a wearable thimble imaging device with a detachable camera housing, that is constructed for field imaging. This paper provides the full exposition of steps, from lens fabrication to imaging platform, necessary to construct a standalone high resolution imaging system. The simplicity of our methodology can be implemented using a regular desktop 3D printer and commercially available digital imaging systems.

  2. Passive locomotion of a simple articulated fish-like system in the wake of an obstacle

    NASA Astrophysics Data System (ADS)

    Eldredge, Jeff D.; Pisani, David

    The behaviour of a passive system of two-dimensional linked rigid bodies in the wake of a circular cylinder at Re=100 is studied computationally. The three rigid bodies are connected by two frictionless hinges, and the system () is initially aligned with a streamwise axis three diameters behind the cylinder. Once flow symmetry is broken, the wake rolls up into a Kn vortex street in which the fish is stably trapped, and the passing large-scale vortices induce an undulatory shape change in the articulated system. It is found that, for certain fish lengths relative to cylinder diameter, the fish is propelled upstream toward the cylinder. Furthermore, the fish is propelled equally effectively when the hinges are locked, confirming that induced body undulation is not necessary for achieving a net thrust. An analysis of the forces on constituent bodies shows that leading-edge suction and negative skin friction on the forward portion of the fish are in competition with positive skin friction on the aft portion; propulsion is achieved when the forebody contributions dominate those on the aftbody. It is shown that the so-called behind the cylinder that enables this passive propulsion is double the length of that without a fish present.

  3. Transdermal therapeutic systems for memantine delivery. Comparison of passive and iontophoretic transport.

    PubMed

    Del Río-Sancho, S; Serna-Jiménez, C E; Sebastián-Morelló, M; Calatayud-Pascual, M A; Balaguer-Fernández, C; Femenía-Font, A; Kalia, Y N; Merino, V; López-Castellano, A

    2017-01-30

    Memantine is a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist used in the treatment of moderate to severe dementia including the symptoms of Alzheimer's disease (AD). It is administered orally but compliance, swallowing problems and the routine use of multiple medications in elderly AD patients means that an alternative route of administration would be of interest. The aim of the present study was to develop memantine hydrochloride occlusive transdermal therapeutic systems (TTS) for passive and iontophoretic delivery across the skin. Polyvinyl pyrrolidone (PVP) and a mixture with polyvinyl alcohol (PVA) were employed as polymeric matrices. The study involved the TTS characterization in addition to quantification of the memantine transport across porcine skin in vitro. The evaluation of the TTS physical properties suggested that systems were made more mechanically resistant by including PVA (6%) or high concentrations of PVP (24%). Moreover, a linear correlation was observed between the concentration of PVP and the bioadhesion of the systems. Drug delivery experiments showed that the highest transdermal flux provided by a passive TTS (PVP 24% w/w limonene) was 8.89±0.81μgcm(-2)h(-1) whereas the highest iontophoretic transport was 46.4±3.6μgcm(-2)h(-1). These innovative TTS would enable two dosage regimens that could lead to therapeutic plasma concentrations.

  4. Design and fabrication of a passive droplet dispenser for portable high resolution imaging system

    PubMed Central

    Kamal, Tahseen; Watkins, Rachel; Cen, Zijian; Rubinstein, Jaden; Kong, Gary; Lee, Woei Ming

    2017-01-01

    Moldless lens manufacturing techniques using standard droplet dispensing technology often require precise control over pressure to initiate fluid flow and control droplet formation. We have determined a series of interfacial fluid parameters optimised using standard 3D printed tools to extract, dispense and capture a single silicone droplet that is then cured to obtain high quality lenses. The dispensing process relies on the recapitulation of liquid dripping action (Rayleigh-Plateau instability) and the capturing method uses the interplay of gravitational force, capillary forces and liquid pinning to control the droplet shape. The key advantage of the passive lens fabrication approach is rapid scale-up using 3D printing by avoiding complex dispensing tools. We characterise the quality of the lenses fabricated using the passive approach by measuring wavefront aberration and high resolution imaging. The fabricated lenses are then integrated into a portable imaging system; a wearable thimble imaging device with a detachable camera housing, that is constructed for field imaging. This paper provides the full exposition of steps, from lens fabrication to imaging platform, necessary to construct a standalone high resolution imaging system. The simplicity of our methodology can be implemented using a regular desktop 3D printer and commercially available digital imaging systems. PMID:28128365

  5. Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

    SciTech Connect

    Prikhodko, Vitaly Y; Parks, II, James E; Pihl, Josh A; Toops, Todd J

    2016-01-01

    Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three-way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in the oxygen-rich exhaust. Thus, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCR approach is of interest. In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. 15% excess NH3 production over a 1:1 NH3:NOX ratio was required (via longer rich cycle timing) to achieve 99.7% NOX conversion at an SCR average inlet temperature of 350 C. Increasing NH3 generation further resulted in even higher NOX conversion; however, tailpipe NH3 emissions resulted. At higher temperatures, NH3 oxidation becomes important and limits NH3 availability for NOX reduction. At the engine conditions studied here, greater than 99% NOX conversion was achieved with passive SCR while delivering fuel

  6. Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

    SciTech Connect

    Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.; Toops, Todd J.

    2016-04-05

    Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCR approach is of interest. In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH3 generation further resulted in even higher NOX conversion; however, tailpipe NH3 emissions resulted. At higher underfloor temperatures, NH3 oxidation over the SCR limited NH3 availability for NOX reduction. At the

  7. Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

    DOE PAGES

    Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.; ...

    2016-04-05

    Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCRmore » approach is of interest. In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH3 generation further resulted in even higher NOX conversion; however, tailpipe NH3 emissions resulted. At higher underfloor temperatures, NH3 oxidation over the SCR limited NH3 availability for NOX reduction. At the engine conditions studied, greater than 99 % NOX conversion was achieved with passive SCR while delivering

  8. Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

    SciTech Connect

    Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.; Toops, Todd J.

    Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCR approach is of interest. In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH3 generation further resulted in even higher NOX conversion; however, tailpipe NH3 emissions resulted. At higher underfloor temperatures, NH3 oxidation over the SCR limited NH3 availability for NOX reduction. At the

  9. Failure Detection, Isolation, and Recovery in an Integrated Navigation System

    DTIC Science & Technology

    1993-12-01

    bias and one for a ramp offset. These filters are unique because they are each driven by two different failure models, nt~p(tjk) and nramp (ts,O...delay in the failure models is addressed in Section 3.4.5. Continuing on, for each of the two failure models, n,,t and nramp , a GLR. matching filter is...the GLR ramp failure model: 0 if t, < 0 nramp (ti) 0 (3.52) (tj ý’)if tj >Oj" For both the sitep and the ramp GLR failure models, unity magnitude has

  10. Hybrid Active-Passive Systems for Control of Aircraft Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, Chris R.

    1999-01-01

    Previous work has demonstrated the large potential for hybrid active-passive systems for attenuating interior noise in aircraft fuselages. The main advantage of an active-passive system is, by utilizing the natural dynamics of the actuator system, the control actuator power and weight is markedly reduced and stability/robustness is enhanced. Three different active-passive approaches were studied in the past year. The first technique utilizes multiple tunable vibration absorbers (ATVA) for reducing narrow band sound radiated from panels and transmitted through fuselage structures. The focus is on reducing interior noise due to propeller or turbo fan harmonic excitation. Two types of tunable vibration absorbers were investigated; a solid state system based upon a piezoelectric mechanical exciter and an electromechanical system based upon a Motran shaker. Both of these systems utilize a mass-spring dynamic effect to maximize tile output force near resonance of the shaker system and so can also be used as vibration absorbers. The dynamic properties of the absorbers (i.e. resonance frequency) were modified using a feedback signal from an accelerometer mounted on the active mass, passed through a compensator and fed into the drive component of the shaker system (piezoelectric element or voice coil respectively). The feedback loop consisted of a two coefficient FIR filter, implemented on a DSP, where the input is acceleration of tile ATVA mass and the output is a force acting in parallel with the stiffness of the absorber. By separating the feedback signal into real and imaginary components, the effective natural frequency and damping of the ATVA can be altered independently. This approach gave control of the resonance frequencies while also allowing the simultaneous removal of damping from the ATVA, thus increasing the ease of controllability and effectiveness. In order to obtain a "tuned" vibration absorber the chosen resonant frequency was set to the excitation

  11. Bumpless switching control for switched systems with partial actuator failures

    NASA Astrophysics Data System (ADS)

    Qi, Yiwen; Bao, Wen; Zhang, Qingxin; Chang, Juntao

    2016-11-01

    This study is concerned with the bumpless transfer problem for switched systems with partial actuator failures, in order to obtain smooth system performance output transition. Taking into account that the system requires a controller switching from current sub-controller to a fault-tolerant sub-controller after actuator fault. And bumpless transfer for control input cannot be traditionally designed when the actuator fault occurs, while performance smoothing can be considered and it is actually the ultimate goal of bumpless transfer. Specifically, the actuator fault model is firstly established and partial actuator fault is considered. Then, the system performance output signal is deemed as the main design variable of bumpless transfer, and closed-loop control systems both previous and after controller switching are constructed. Moreover, by using model matching thought and the adaptive sliding mode control technique, a bumpless transfer compensator design strategy is given to drive the performance output variable (after controller switching) to track the one of reference model. At last, simulation results of numeric and application examples demonstrate the effectiveness of the proposed bumpless transfer strategy.

  12. Management of heart failure patients using telemedicine communication systems.

    PubMed

    Kashem, Abul; Cross, Robert C; Santamore, William P; Bove, Alfred A

    2006-05-01

    Heart failure (HF) continues to place significant demands on health care resources because of the large number of hospital admissions for HF, the growth of the elderly population with HF, and the improved survival of patients with chronic heart disease who develop HF that requires continuous care. Because HF is best managed using a disease management approach, frequent communication is an important component of care. A variety of studies using the telephone to maintain communication have demonstrated reduced hospital admissions and improved morbidity rate. Hardware monitoring systems that can record vital signs and transmit information from the home to a data center have also demonstrated their value in HF care, but such systems become expensive when considered for large populations of HF patients. Most HF patients can transmit their vital signs, weight, and symptoms to a practice data center using the Internet with no specialized hardware other than a sphygmomanometer and a scale. We have used such a system to monitor HF patients and have provided care instructions using the same system. With use of an Internet communication system, it is possible to reduce hospitalizations and maintain a stable HF status without frequent office visits.

  13. Genetic variation in the natriuretic peptide system and heart failure.

    PubMed

    Lanfear, David E

    2010-05-01

    Heart failure (HF) is a modern epidemic and is one of the few cardiovascular diseases which is increasing in prevalence. The growing importance of the Natriuretic Peptide (NP) system in HF is well recognized. Laboratory tests for B-type Natriuretic Peptide (BNP) have proven value as diagnostic and prognostic tools in HF and are now part of routine clinical care. Furthermore, recombinant atrial natriuretic peptide (ANP) (carperitide) and BNP (nesiritide) and are approved HF therapies in Japan and the US, respectively and additional natriuretic peptides (e.g., CNP, urodilatin, and designer NPs) are under investigation for use in HF. Common genetic sequence variants are increasingly being recognized as determinants of disease risk or drug response and may help explain a portion of the inter-individual variation in the human NP system. This review describes current knowledge of NP system genetic variation as it pertains to HF as well as ongoing studies and where the field is expected to progress in the near future. To briefly summarize, NP system genetic variants have been associated with alterations in gene expression, NP levels, and cardiovascular disease. The next step forward will include specific investigations into how this genetic variation can advance 'Personalized Medicine', such as whether they impact the utility of diagnostic BNP testing or effectiveness of therapeutic NP infusion. This is already in progress, with pharmacogenetic studies of nesiritide currently underway. We expect that within 5 years there should be a reasonable idea of whether NP system genetic variation will have important clinical implications.

  14. An adaptive tracking observer for failure-detection systems

    NASA Technical Reports Server (NTRS)

    Sidar, M.

    1982-01-01

    The design problem of adaptive observers applied to linear, constant and variable parameters, multi-input, multi-output systems, is considered. It is shown that, in order to keep the observer's (or Kalman filter) false-alarm rate (FAR) under a certain specified value, it is necessary to have an acceptable proper matching between the observer (or KF) model and the system parameters. An adaptive observer algorithm is introduced in order to maintain desired system-observer model matching, despite initial mismatching and/or system parameter variations. Only a properly designed adaptive observer is able to detect abrupt changes in the system (actuator, sensor failures, etc.) with adequate reliability and FAR. Conditions for convergence for the adaptive process were obtained, leading to a simple adaptive law (algorithm) with the possibility of an a priori choice of fixed adaptive gains. Simulation results show good tracking performance with small observer output errors and accurate and fast parameter identification, in both deterministic and stochastic cases.

  15. Failure Accommodation Tested in Magnetic Suspension Systems for Rotating Machinery

    NASA Technical Reports Server (NTRS)

    Provenza, Andy J.

    2000-01-01

    The NASA Glenn Research Center at Lewis Field and Texas A&M University are developing techniques for accommodating certain types of failures in magnetic suspension systems used in rotating machinery. In recent years, magnetic bearings have become a viable alternative to rolling element bearings for many applications. For example, industrial machinery such as machine tool spindles and turbomolecular pumps can today be bought off the shelf with magnetically supported rotating components. Nova Gas Transmission Ltd. has large gas compressors in Canada that have been running flawlessly for years on magnetic bearings. To help mature this technology and quiet concerns over the reliability of magnetic bearings, NASA researchers have been investigating ways of making the bearing system tolerant to faults. Since the potential benefits from an oil-free, actively controlled bearing system are so attractive, research that is focused on assuring system reliability and safety is justifiable. With support from the Fast Quiet Engine program, Glenn's Structural Mechanics and Dynamics Branch is working to demonstrate fault-tolerant magnetic suspension systems targeted for aerospace engine applications. The Flywheel Energy Storage Program is also helping to fund this research.

  16. Assessment of Integrated Pedestrian Protection Systems with Autonomous Emergency Braking (AEB) and Passive Safety Components.

    PubMed

    Edwards, Mervyn; Nathanson, Andrew; Carroll, Jolyon; Wisch, Marcus; Zander, Oliver; Lubbe, Nils

    2015-01-01

    Autonomous emergency braking (AEB) systems fitted to cars for pedestrians have been predicted to offer substantial benefit. On this basis, consumer rating programs-for example, the European New Car Assessment Programme (Euro NCAP)-are developing rating schemes to encourage fitment of these systems. One of the questions that needs to be answered to do this fully is how the assessment of the speed reduction offered by the AEB is integrated with the current assessment of the passive safety for mitigation of pedestrian injury. Ideally, this should be done on a benefit-related basis. The objective of this research was to develop a benefit-based methodology for assessment of integrated pedestrian protection systems with AEB and passive safety components. The method should include weighting procedures to ensure that it represents injury patterns from accident data and replicates an independently estimated benefit of AEB. A methodology has been developed to calculate the expected societal cost of pedestrian injuries, assuming that all pedestrians in the target population (i.e., pedestrians impacted by the front of a passenger car) are impacted by the car being assessed, taking into account the impact speed reduction offered by the car's AEB (if fitted) and the passive safety protection offered by the car's frontal structure. For rating purposes, the cost for the assessed car is normalized by comparing it to the cost calculated for a reference car. The speed reductions measured in AEB tests are used to determine the speed at which each pedestrian in the target population will be impacted. Injury probabilities for each impact are then calculated using the results from Euro NCAP pedestrian impactor tests and injury risk curves. These injury probabilities are converted into cost using "harm"-type costs for the body regions tested. These costs are weighted and summed. Weighting factors were determined using accident data from Germany and Great Britain and an independently

  17. Enhancing VHTR Passive Safety and Economy with Thermal Radiation Based Direct Reactor Auxiliary Cooling System

    SciTech Connect

    Haihua Zhao; Hongbin Zhang; Ling Zou; Xiaodong Sun

    2012-06-01

    One of the most important requirements for Gen. IV Very High Temperature Reactor (VHTR) is passive safety. Currently all the gas cooled version of VHTR designs use Reactor Vessel Auxiliary Cooling System (RVACS) for passive decay heat removal. The decay heat first is transferred to the core barrel by conduction and radiation, and then to the reactor vessel by thermal radiation and convection; finally the decay heat is transferred to natural circulated air or water systems. RVACS can be characterized as a surface based decay heat removal system. The RVACS is especially suitable for smaller power reactors since small systems have relatively larger surface area to volume ratio. However, RVACS limits the maximum achievable power level for modular VHTRs due to the mismatch between the reactor power (proportional to volume) and decay heat removal capability (proportional to surface area). When the relative decay heat removal capability decreases, the peak fuel temperature increases, even close to the design limit. Annular core designs with inner graphite reflector can mitigate this effect; therefore can further increase the reactor power. Another way to increase the reactor power is to increase power density. However, the reactor power is also limited by the decay heat removal capability. Besides the safety considerations, VHTRs also need to be economical in order to compete with other reactor concepts and other types of energy sources. The limit of decay heat removal capability set by using RVACS has affected the economy of VHTRs. A potential alternative solution is to use a volume-based passive decay heat removal system, called Direct Reactor Auxiliary Cooling Systems (DRACS), to remove or mitigate the limitation on decay heat removal capability. DRACS composes of natural circulation loops with two sets of heat exchangers, one on the reactor side and another on the environment side. For the reactor side, cooling pipes will be inserted into holes made in the outer or

  18. Failure detection system design methodology. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.

    1980-01-01

    The design of a failure detection and identification system consists of designing a robust residual generation process and a high performance decision making process. The design of these two processes are examined separately. Residual generation is based on analytical redundancy. Redundancy relations that are insensitive to modelling errors and noise effects are important for designing robust residual generation processes. The characterization of the concept of analytical redundancy in terms of a generalized parity space provides a framework in which a systematic approach to the determination of robust redundancy relations are developed. The Bayesian approach is adopted for the design of high performance decision processes. The FDI decision problem is formulated as a Bayes sequential decision problem. Since the optimal decision rule is incomputable, a methodology for designing suboptimal rules is proposed. A numerical algorithm is developed to facilitate the design and performance evaluation of suboptimal rules.

  19. Effectiveness of a passive subslab ventilation system in reducing radon concentrations in a home

    SciTech Connect

    Holford, D.J.; Freeman, H.D.

    1996-10-01

    The effectiveness of a passive subslab ventilation system in reducing radon concentrations in an occupied home was investigated by measuring radon concentrations and pressure differentials during a 1-year period when a passive subslab ventilation system was being cycled on and off. Radon concentrations in the house were 30% lower during periods when the stack was open to the atmosphere. The effect was most pronounced when the home was unoccupied and during the winter and spring months. Furnace use and wind speed were the best predictors of transient changes in basement radon concentrations, whether the stack was open or closed. Pressure differential measurements show that subslab depressurization occurs when the stack is open during the winter and spring months due to bouyancy-driven air flow up the stack, but not during the summer. Numerical simulations of gas flow and radon transport into the house from the surrounding soil were calibrated to observed pressure differentials and radon concentrations. The model predicts that peak radon concentrations caused by furnace use will be reduced by flow out of the stack. However, the model is unable to account for the reduction in average radon concentrations observed while the stack is open in the winter. 19 refs., 16 figs., 1 tab.

  20. Recovery of Rare Earth Elements and Yttrium from Passive-Remediation Systems of Acid Mine Drainage.

    PubMed

    Ayora, Carlos; Macías, Francisco; Torres, Ester; Lozano, Alba; Carrero, Sergio; Nieto, José-Miguel; Pérez-López, Rafael; Fernández-Martínez, Alejandro; Castillo-Michel, Hiram

    2016-08-02

    Rare earth elements and yttrium (REY) are raw materials of increasing importance for modern technologies, and finding new sources has become a pressing need. Acid mine drainage (AMD) is commonly considered an environmental pollution issue. However, REY concentrations in AMD can be several orders of magnitude higher than in naturally occurring water bodies. With respect to shale standards, the REY distribution pattern in AMD is enriched in intermediate and valuable REY, such as Tb and Dy. The objective of the present work is to study the behavior of REY in AMD passive-remediation systems. Traditional AMD passive remediation systems are based on the reaction of AMD with calcite-based permeable substrates followed by decantation ponds. Experiments with two columns simulating AMD treatment demonstrate that schwertmannite does not accumulate REY, which, instead, are retained in the basaluminite residue. The same observation is made in two field-scale treatments from the Iberian Pyrite Belt (IPB, southwest Spain). On the basis of the amplitude of this process and on the extent of the IPB, our findings suggest that the proposed AMD remediation process can represent a modest but suitable REY source. In this sense, the IPB could function as a giant heap-leaching process of regional scale in which rain and oxygen act as natural driving forces with no energy investment. In addition to having environmental benefits of its treatment, AMD is expected to last for hundreds of years, and therefore, the total reserves are practically unlimited.

  1. Materials research for passive solar systems: solid-state phase-change materials

    SciTech Connect

    Benson, D.K.; Webb, J.D.; Burrows, R.W.; McFadden, J.D.O.; Christensen, C.

    1985-03-01

    A set of solid-state phase-change materials is being evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol (C/sub 5/H/sub 12/O/sub 4/), pentaglycerinve (C/sub 5/H/sub 12/O/sub 3/), and neopentyl glycol (C/sub 5/H/sub 12/O/sub 2/). Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature betweeen 25/sup 0/C and 188/sup 0/C, and have latent heats of transformation between 20 and 70 cal/g. Transformation temperatures, specific heats, and latent heats of transformation have been measured for a number of these materials. Limited cyclic experiments suggest that the solid solutions are stable. These phase-change materials exhibit large amounts of undercooling; however, the addition of certain nucleating agents as particulate dispersions in the solid phase-change material greatly reduces this effect. Computer simulations suggest that the use of an optimized solid-state phase-change material in a Trombe wall could provide better performance than a concrete Trombe wall four times thicker and nine times heavier. Nevertheless, a higher cost of the phase-change materials (approx. =$0.70 per pound) is likely to limit their applicability in passive solar systems unless their performance can be significantly improved through further research.

  2. Active and passive mode calibration of the Combined Thermal Epithermal Neutron (CTEN) system

    SciTech Connect

    Veilleux, J. M.

    2002-06-01

    The Combined Thermal/Epithermal Neutron (CTEN) non-destructive assay (NDA) system was designed to assay transuranic waste by employing an induced active neutron interrogation and/or a spontaneous passive neutron measurement. This is the second of two papers, and focuses on the passive mode, relating the net double neutron coincidence measurement to the plutonium mass via the calibration constant. National Institute of Standards and Technology (NIST) calibration standards were used and the results verified with NIST-traceable verification standards. Performance demonstration program (PDP) 'empty' 208-L matrix drum was used for the calibration. The experimentally derived calibration constant was found to be 0.0735 {+-} 0.0059 g {sup 240}Pu effective per unit response. Using this calibration constant, the Waste Isolation Pilot Plant (WIPP) criteria was satisfied with five minute waste assays in the range from 3 to 177g Pu. CTEN also participated in the PDP Cycle 8A blind assay with organic sludge and metal matrices and passed the criteria for accuracy and precision in both assay modes. The WIPP and EPA audit was completed March 1, 2002 and full certification is awaiting the closeout of one finding during the audit. With the successful closeout of the audit, the CTEN system will have shown that it can provide very fast assays (five minutes or less) of waste in the range from the minimum detection limit (about 2 mg Pu) to 177 g Pu.

  3. Magnetorheological valve based actuator for improvement of passively controlled turbocharger system

    NASA Astrophysics Data System (ADS)

    Bahiuddin, I.; Mazlan, S. A.; Imaduddin, F.; Ubaidillah, Ichwan, B.

    2016-03-01

    Variable geometry turbochargers have been widely researched to fulfil the current engine stringent regulations. The passively controlled turbocharger (PCT) concept has been proposed to reduce energy consumption by utilizing the emission energy to move the actuator. However, it only covered a small range operating condition. Therefore, a magnetorheological(MR) Valve device, as typical smart material devices to enhance a passive device, is proposed to improve the PCT. Even though the benefits have been considered for the compactness and easiness to connect to an electrical system, the number of publications regarding the MR application within engine system is hard to be found. Therefore, this paper introduces a design of an MR Valve in a turbocharger. The main challenge is to make sure its capability to produce a sufficient total pressure drop. To overcome the challenge, its material properties, shape and pressure drop calculation has been analyzed to fulfil the requirement. Finally, to get a more understanding of actuator performance, the actuator response was simulated by treating the exhaust gas pressure as an input. It shows that the new MR actuator has a potential dynamic to improve the PCT controllability.

  4. DEROB - A system for simulating the dynamic energy performance of passive solar structures

    NASA Astrophysics Data System (ADS)

    Arumi-Noe, A.; Wysocki, M.

    1980-07-01

    An overview of DEROB, a system of FORTRAN programs capable of simulating the energy response of buildings composed of multiple thermally coupled volumes of arbitrary geometries and correctly interpreting the presence of shading devices, is presented. The physical and mathematical basis of DEROB's heat transfer algorithms is outlined. The results of validation studies are discussed which tested DEROB against empirical data obtained from 10 target structures (3,4,5). These test results show that DEROB can accurately simulate the thermal performances of a wide variety of functional and geometric conditions which are often met with when dealing with passively heated and cooled buildings (e.g. direct gain systems, water-walls, water Trombe walls, Trombe walls, convective loops, rock storage bins, greehousessun space systems, all of which may be modeled with or without the use of moveable insulation).

  5. A water management system for metal-based micro passive direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Xuelin; Li, Yang; Chen, Hailong; Wang, Zhigang; Zeng, Zhaoyang; Cai, Mengyuan; Zhang, Yufeng; Liu, Xiaowei

    2015-01-01

    A novel water management system for micro passive DMFC is fabricated and characterized in this paper. This system consists of both a cathode current collector made of a 316L sintered stainless fiber felt (SSFF) and an aluminum-based end plate fabricated with a perforated flow field. Besides, some water-collecting channels were fabricated on the surface of the cathode end plate and then covered by the plasma electrolytic oxidation (PEO) coating. The results show that the PEO coating plays crucial roles in the water management system. Because of the highly hydrophilic property of the coating, the channels work well in collecting the liquid water from the current collector, and water accumulation along the air-breathing holes can be well prevented, which improves the stability of the micro DMFC.

  6. Design of a photovoltaic system for a passive design northeast all-electric residence

    NASA Astrophysics Data System (ADS)

    Mehalick, E. M.; Tully, G. F.; Johnson, J.; Parker, J.; Felice, R.

    1982-01-01

    A photovoltaic system was developed and integrated into a passively designed, low energy consuming home suitable for the Northeast region of the country. The selected array size is 4.1 kW and covers 51 square meters of roof area. The design addresses the residential market segment of low energy consuming houses with limited roof area availability for photovoltaic arrays. A direct mount, next generation, larger sized, photovoltaic shingle module is used to reduce installation costs over earlier generation shingle modules. A 4 kW line-commutated inverter is used in the power conversion subsystem, since it is representative of currently available equipment. The complete system and house design are described, including all the pertinent installation and construction drawings. Specific performance results are presented for the Boston and Madison region. The system design presented, coupled with previously completed designs, provide a set of design options expected to be available to residential homeowners in the mid 1980's.

  7. Systemic anti-inflammatory fibrosis suppression in threatened trabeculectomy failure.

    PubMed

    Vote, Brendan; Fuller, J Robert; Bevin, Tui H; Molteno, Anthony C B

    2004-02-01

    To provide a rationale for the use of systemic anti-inflammatory fibrosis suppression in the postoperative management of threatened early trabeculectomy bleb failure. A review of the literature and of the authors' own experiences was conducted. The most important cause of persistent elevation of intraocular pressure after trabeculectomy is unduly marked or persistent inflammation with deposition of fibrous tissue, which prevents the formation of an adequately draining bleb. It was found that a clinically useful degree of suppression of bleb inflammation and fibrosis can be obtained with a 4-6 week course of the combined systemic administration of prednisone (10 mg t.i.d.), a non-steroidal anti-inflammatory agent (e.g. diclofenac 100 mg SR daily) and colchicine (0.25 mg or 0.3 mg t.i.d.), which was termed anti-inflammatory fibrosis suppression. Topical atropine 1% t.i.d. and adrenaline 1% t.i.d. eye drops can also be considered in addition to routine postoperative topical steroids. Despite advances in surgical techniques and methods to control fibrosis, anti-inflammatory fibrosis suppression is a valuable tool to have available in the post-operative period for management of trabeculectomies that threaten failure. This regime produces a diffuse bleb, which has a very low risk of late infection or bleb perforation. It is recommend that this regime be added to the list of therapies that are considered when clinical features suggestive of a failing bleb are confronted early in the post-operative course.

  8. Multimodal Integration of Self-Motion Cues in the Vestibular System: Active versus Passive Translations

    PubMed Central

    Carriot, Jerome; Brooks, Jessica X.

    2013-01-01

    The ability to keep track of where we are going as we navigate through our environment requires knowledge of our ongoing location and orientation. In response to passively applied motion, the otolith organs of the vestibular system encode changes in the velocity and direction of linear self-motion (i.e., heading). When self-motion is voluntarily generated, proprioceptive and motor efference copy information is also available to contribute to the brain's internal representation of current heading direction and speed. However to date, how the brain integrates these extra-vestibular cues with otolith signals during active linear self-motion remains unknown. Here, to address this question, we compared the responses of macaque vestibular neurons during active and passive translations. Single-unit recordings were made from a subgroup of neurons at the first central stage of sensory processing in the vestibular pathways involved in postural control and the computation of self-motion perception. Neurons responded far less robustly to otolith stimulation during self-generated than passive head translations. Yet, the mechanism underlying the marked cancellation of otolith signals did not affect other characteristics of neuronal responses (i.e., baseline firing rate, tuning ratio, orientation of maximal sensitivity vector). Transiently applied perturbations during active motion further established that an otolith cancellation signal was only gated in conditions where proprioceptive sensory feedback matched the motor-based expectation. Together our results have important implications for understanding the brain's ability to ensure accurate postural and motor control, as well as perceptual stability, during active self-motion. PMID:24336720

  9. Quantifying Pilot Contribution to Flight Safety during Hydraulic Systems Failure

    NASA Technical Reports Server (NTRS)

    Kramer, Lynda J.; Etherington, Timothy J.; Bailey, Randall E.; Kennedy, Kellie D.

    2017-01-01

    Accident statistics cite the flight crew as a causal factor in over 60% of large transport aircraft fatal accidents. Yet, a well-trained and well-qualified pilot is acknowledged as the critical center point of aircraft systems safety and an integral safety component of the entire commercial aviation system. The latter statement, while generally accepted, cannot be verified because little or no quantitative data exists on how and how many accidents/incidents are averted by crew actions. A joint NASA/FAA high-fidelity motion-base human-in-the-loop test was conducted using a Level D certified Boeing 737-800 simulator to evaluate the pilot's contribution to safety-of-flight during routine air carrier flight operations and in response to aircraft system failures. To quantify the human's contribution, crew complement (two-crew, reduced crew, single pilot) was used as the independent variable in a between-subjects design. This paper details the crew's actions, including decision-making, and responses while dealing with a hydraulic systems leak - one of 6 total non-normal events that were simulated in this experiment.

  10. Urine monitoring system failure analysis and operational verification test report

    NASA Technical Reports Server (NTRS)

    Glanfield, E. J.

    1978-01-01

    Failure analysis and testing of a prototype urine monitoring system (UMS) are reported. System performance was characterized by a regression formula developed from volume measurement test data. When the volume measurement test data. When the volume measurement data was imputted to the formula, the standard error of the estimate calculated using the regression formula was found to be within 1.524% of the mean of the mass of the input. System repeatability was found to be somewhat dependent upon the residual volume of the system and the evaporation of fluid from the separator. The evaporation rate was determined to be approximately 1cc/minute. The residual volume in the UMS was determined by measuring the concentration of LiCl in the flush water. Observed results indicated residual levels in the range of 9-10ml, however, results obtained during the flushing efficiency test indicated a residual level of approximately 20ml. It is recommended that the phase separator pumpout time be extended or the design modified to minimize the residual level.

  11. A Remote Patient Monitoring System for Congestive Heart Failure

    PubMed Central

    Suh, Myung-kyung; Chen, Chien-An; Woodbridge, Jonathan; Tu, Michael Kai; Kim, Jung In; Nahapetian, Ani; Evangelista, Lorraine S.; Sarrafzadeh, Majid

    2011-01-01

    Congestive heart failure (CHF) is a leading cause of death in the United States affecting approximately 670,000 individuals. Due to the prevalence of CHF related issues, it is prudent to seek out methodologies that would facilitate the prevention, monitoring, and treatment of heart disease on a daily basis. This paper describes WANDA (Weight and Activity with Blood Pressure Monitoring System); a study that leverages sensor technologies and wireless communications to monitor the health related measurements of patients with CHF. The WANDA system is a three-tier architecture consisting of sensors, web servers, and back-end databases. The system was developed in conjunction with the UCLA School of Nursing and the UCLA Wireless Health Institute to enable early detection of key clinical symptoms indicative of CHF-related decompensation. This study shows that CHF patients monitored by WANDA are less likely to have readings fall outside a healthy range. In addition, WANDA provides a useful feedback system for regulating readings of CHF patients. PMID:21611788

  12. Disinfection of Spacecraft Potable Water Systems by Passivation with Ionic Silver

    NASA Technical Reports Server (NTRS)

    Birmele, Michele N.; McCoy, LaShelle e.; Roberts, Michael S.

    2011-01-01

    Microbial growth is common on wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and physical disinfection methods. Advanced control technologies are needed to limit microorganisms and increase the reliability of life support systems required for long-duration human missions. Silver ions and compounds are widely used as antimicrobial agents for medical applications and continue to be used as a residual biocide in some spacecraft water systems. The National Aeronautics and Space Administration (NASA) has identified silver fluoride for use in the potable water system on the next generation spacecraft. Due to ionic interactions between silver fluoride in solution and wetted metallic surfaces, ionic silver is rapidly depleted from solution and loses its antimicrobial efficacy over time. This report describes research to prolong the antimicrobial efficacy of ionic silver by maintaining its solubility. Three types of metal coupons (lnconel 718, Stainless Steel 316, and Titanium 6AI-4V) used in spacecraft potable water systems were exposed to either a continuous flow of water amended with 0.4 mg/L ionic silver fluoride or to a static, pre-treatment passivation in 50 mg/L ionic silver fluoride with or without a surface oxidation pre-treatment. Coupons were then challenged in a high-shear, CDC bioreactor (BioSurface Technologies) by exposure to six bacteria previously isolated from spacecraft potable water systems. Continuous exposure to 0.4 mg/L ionic silver over the course of 24 hours during the flow phase resulted in a >7-log reduction. The residual effect of a 24-hour passivation treatment in 50 mg/L of ionic silver resulted in a >3-log reduction, whereas a two-week treatment resulted in a >4-log reduction. Results indicate that 0.4 mg/L ionic silver is an effective biocide against many bacteria and that a prepassivation of metal surfaces with silver can provide additional microbial control.

  13. Identification and characterization of passive safety system and inherent safety feature building blocks for advanced light-water reactors

    SciTech Connect

    Forsberg, C.W.

    1989-01-01

    Oak Ridge National Laboratory (ORNL) is investigating passive and inherent safety options for Advanced Light-Water Reactors (ALWRs). A major activity in 1989 includes identification and characterization of passive safety system and inherent safety feature building blocks, both existing and proposed, for ALWRs. Preliminary results of this work are reported herein. This activity is part of a larger effort by the US Department of Energy, reactor vendors, utilities, and others in the United States to develop improved LWRs. The Advanced Boiling Water Reactor (ABWR) program and the Advanced Pressurized Water Reactor (APWR) program have as goals improved, commercially available LWRs in the early 1990s. The Advanced Simplified Boiling Water Reactor (ASBWR) program and the AP-600 program are developing more advanced reactors with increased use of passive safety systems. It is planned that these reactors will become commercially available in the mid 1990s. The ORNL program is an exploratory research program for LWRs beyond the year 2000. Desired long-term goals for such reactors include: (1) use of only passive and inherent safety, (2) foolproof against operator errors, (3) malevolence resistance against internal sabotage and external assault and (4) walkaway safety. The acronym ''PRIME'' (Passive safety, Resilient operation, Inherent safety, Malevolence resistance, and Extended (walkaway) safety) is used to summarize these desired characteristics. Existing passive and inherent safety options are discussed in this document.

  14. A six-axis hybrid vibration isolation system using active zero-power control supported by passive weight support mechanism

    NASA Astrophysics Data System (ADS)

    Emdadul Hoque, Md.; Mizuno, Takeshi; Ishino, Yuji; Takasaki, Masaya

    2010-08-01

    This paper presents a six-degree-of-freedom hybrid vibration isolation system integrated with an active negative suspension, an active-passive positive suspension and a passive weight support mechanism. The aim of the research consists in maximizing the system and control performances, and minimizing the system development and maintenance costs. The vibration isolation system is, fundamentally, developed by connecting an active negative suspension realized by zero-power control in series with an active-passive positive suspension. The system could effectively isolate ground vibrations in addition to suppress the effect of on-board generated direct disturbances of the six-axis motions, associated with vertical and horizontal directions. The system is further reinforced by introducing a passive weight support mechanism in parallel with the basic system. The modified system with zero-power control allows simplified design of the isolation table without power consumption. It also offers enhanced performance on direct disturbance suppression and large payload supporting capabilities, without degrading transmissibility characteristics. A mathematical model of the system is presented and, therefore, analyzed to demonstrate that zero-compliance to direct disturbance could be generated by the developed system. Experimental demonstrations validate the proposed concept that exhibits high stiffness of the isolation table to static and dynamic direct disturbances, and good transmissibility characteristics against ground vibration. Further improvements of the vibration isolation system and the control system are discussed as well.

  15. Tritium Waste Treatment System component failure data analysis from June 18, 1984--December 31, 1989

    SciTech Connect

    Cadwallader, L.C. ); Stolpe Gavett, M.A. )

    1990-09-01

    This document gives the failure rates for the major tritium-bearing components in the Tritium Waste Treatment System at the Tritium Systems Test Assembly, which is a fusion research and technology facility at the Los Alamos National Laboratory. The failure reports, component populations, and operating demands/hours are given in this report, and sample calculations for binomial demand failure rates and poisson hourly failure rates are given in the appendices. The failure rates for tritium-bearing components were on the order of the screening failure rate values suggested for fusion reliability and risk analyses. More effort should be directed toward collecting and analyzing fusion component failure data, since accurate failure rates are necessary to refine reliability and risk analyses. 15 refs., 4 figs., 4 tabs.

  16. A passive cooling system proposal for multifunction and high-power displays

    NASA Astrophysics Data System (ADS)

    Tari, Ilker

    2013-03-01

    Flat panel displays are conventionally cooled by internal natural convection, which constrains the possible rate of heat transfer from the panel. On one hand, during the last few years, the power consumption and the related cooling requirement for 1080p displays have decreased mostly due to energy savings by the switch to LED backlighting and more efficient electronics. However, on the other hand, the required cooling rate recently started to increase with new directions in the industry such as 3D displays, and ultra-high-resolution displays (recent 4K announcements and planned introduction of 8K). In addition to these trends in display technology itself, there is also a trend to integrate consumer entertainment products into displays with the ultimate goal of designing a multifunction device replacing the TV, the media player, the PC, the game console and the sound system. Considering the increasing power requirement for higher fidelity in video processing, these multifunction devices tend to generate very high heat fluxes, which are impossible to dissipate with internal natural convection. In order to overcome this obstacle, instead of active cooling with forced convection that comes with drawbacks of noise, additional power consumption, and reduced reliability, a passive cooling system relying on external natural convection and radiation is proposed here. The proposed cooling system consists of a heat spreader flat heat pipe and aluminum plate-finned heat sink with anodized surfaces. For this system, the possible maximum heat dissipation rates from the standard size panels (in 26-70 inch range) are estimated by using our recently obtained heat transfer correlations for the natural convection from aluminum plate-finned heat sinks together with the surface-to-surface radiation. With the use of the proposed passive cooling system, the possibility of dissipating very high heat rates is demonstrated, hinting a promising green alternative to active cooling.

  17. 10 CFR 1008.24 - Criminal penalties-failure to publish a system notice.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Criminal penalties-failure to publish a system notice...—failure to publish a system notice. Subsection (i)(2) of the Act provides that an agency officer or employee who willfully maintains a system of records without publishing a system notice as required by...

  18. 10 CFR 1008.24 - Criminal penalties-failure to publish a system notice.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Criminal penalties-failure to publish a system notice...—failure to publish a system notice. Subsection (i)(2) of the Act provides that an agency officer or employee who willfully maintains a system of records without publishing a system notice as required by...

  19. A machine learning system to improve heart failure patient assistance.

    PubMed

    Guidi, Gabriele; Pettenati, Maria Chiara; Melillo, Paolo; Iadanza, Ernesto

    2014-11-01

    In this paper, we present a clinical decision support system (CDSS) for the analysis of heart failure (HF) patients, providing various outputs such as an HF severity evaluation, HF-type prediction, as well as a management interface that compares the different patients' follow-ups. The whole system is composed of a part of intelligent core and of an HF special-purpose management tool also providing the function to act as interface for the artificial intelligence training and use. To implement the smart intelligent functions, we adopted a machine learning approach. In this paper, we compare the performance of a neural network (NN), a support vector machine, a system with fuzzy rules genetically produced, and a classification and regression tree and its direct evolution, which is the random forest, in analyzing our database. Best performances in both HF severity evaluation and HF-type prediction functions are obtained by using the random forest algorithm. The management tool allows the cardiologist to populate a "supervised database" suitable for machine learning during his or her regular outpatient consultations. The idea comes from the fact that in literature there are a few databases of this type, and they are not scalable to our case.

  20. Real Time Fire Reconnaissance Satellite Monitoring System Failure Model

    NASA Astrophysics Data System (ADS)

    Nino Prieto, Omar Ariosto; Colmenares Guillen, Luis Enrique

    2013-09-01

    In this paper the Real Time Fire Reconnaissance Satellite Monitoring System is presented. This architecture is a legacy of the Detection System for Real-Time Physical Variables which is undergoing a patent process in Mexico. The methodologies for this design are the Structured Analysis for Real Time (SA- RT) [8], and the software is carried out by LACATRE (Langage d'aide à la Conception d'Application multitâche Temps Réel) [9,10] Real Time formal language. The system failures model is analyzed and the proposal is based on the formal language for the design of critical systems and Risk Assessment; AltaRica. This formal architecture uses satellites as input sensors and it was adapted from the original model which is a design pattern for physical variation detection in Real Time. The original design, whose task is to monitor events such as natural disasters and health related applications, or actual sickness monitoring and prevention, as the Real Time Diabetes Monitoring System, among others. Some related work has been presented on the Mexican Space Agency (AEM) Creation and Consultation Forums (2010-2011), and throughout the International Mexican Aerospace Science and Technology Society (SOMECYTA) international congress held in San Luis Potosí, México (2012). This Architecture will allow a Real Time Fire Satellite Monitoring, which will reduce the damage and danger caused by fires which consumes the forests and tropical forests of Mexico. This new proposal, permits having a new system that impacts on disaster prevention, by combining national and international technologies and cooperation for the benefit of humankind.

  1. Reliability bounds for fault-tolerant systems with competing responses to component failures

    NASA Technical Reports Server (NTRS)

    Lee, L. D.

    1985-01-01

    Bounds are established on the probability of system failure for fault-tolerant systems of the type used, for example, in aviation control. Event series leading to system failure are assumed to follow a semi-Markov model in which the potential sojourn times associated with component failures have exponential distributions and those associated with system responses have distributions with unspecified form. A product form of the bounds is derived by using a model that provides for multiple competing system responses to component failures.

  2. Reliability bounds for fault-tolerant systems with competing responses to component failures

    NASA Technical Reports Server (NTRS)

    Lee, L. D.

    1986-01-01

    Bounds are established on the probability of system failure for fault-tolerant systems of the type used, for example, in aviation control. Event series leading to system failure are assumed to follow a semi-Markov model in which the potential sojourn times associated with component failures have exponential distributions and those associated with system responses have distributions with unspecified form. A product form of the bounds is derived by using a model that provides for multiple competing system responses to component failures.

  3. Evaluation of Corrosion Failure in Tractor-Trailer Brake System

    SciTech Connect

    Wilson, DF

    2002-10-22

    As reported to ORNL, concomitant with the introduction of different deicing and anti-icing compounds, there was an increase in the brake failure rate of tractor-trailer trucks. A forensic evaluation of a failed brake system was performed. Optical and scanning electron microscopic evaluation showed corrosion to be mostly confined to the brake table/lining interface. The corrosion is non-uniform as is to be expected for plain carbon steel in chloride environments. This initial analysis found no evidence for the chlorides of calcium and magnesium, which are the newly introduced deicing and antiicing compounds and are less soluble in water than the identified chlorides of sodium and potassium, in the scale. The result could be as a result of non-exposure of the examined brake table to calcium and magnesium chloride. The mechanisms for the increased failure rate are postulated as being an increased rate of corrosion due to positive shifts in the corrosion potential, and an increased amount of corrosion due to an increased ''time of wetness'' that results from the presence of hygroscopic salts. Laboratory scale evaluation of the corrosion of plain carbon steel in simulated deicing and anti-icing solutions need to be performed to determine corrosion rates and morphological development of corrosion product, to compare laboratory data to in-service data, and to rank economically feasible replacement materials for low carbon steel. In addition, the mechanical behavior of the lining attached to the brake shoe table needs to be assessed. It is opined that an appropriate adjustment of materials could easily allow for a doubling of a brake table/lining lifetime. Suggestions for additional work, to clarify the mechanisms of rust jacking and to develop possible solutions, are described.

  4. Architecture and Design of IP Broadcasting System Using Passive Optical Network

    NASA Astrophysics Data System (ADS)

    Ikeda, Hiroki; Sugawa, Jun; Ashi, Yoshihiro; Sakamoto, Kenichi

    We propose an IP broadcasting system architecture using passive optical networks (PON) utilizing the optical broadcast links of a PON with a downstream bandwidth allocation algorithm to provide a multi-channel IP broadcasting service to home subscribers on single broadband IP network infrastructures. We introduce the design and adaptation of the optical broadcast links to effectively broadcast video contents to home subscribers. We present a performance analysis that includes the downstream bandwidth utilization efficiency of the broadcast link and the bandwidth control of the IP broadcasting and Internet data. Our analysis and simulation results show that the proposed system can provide 100 HDTV channels to every user over fiber lines. We also propose an IPTV channel selection mechanism in an ONT by selecting a broadcast stream. We developed and evaluated a prototype that can achieve a 15-msec IPTV channel selection speed.

  5. Bilateral shared autonomous systems with passive and nonpassive input forces under time varying delay.

    PubMed

    Islam, Shafiqul; Liu, Peter X; El Saddik, Abdulmotaleb; Dias, J; Seneviratne, Lakmal

    2015-01-01

    In this paper, we address stability and tracking control problem of bilateral shared autonomous systems in the presence of passive and nonpassive input interaction forces. The design comprises delayed position and position-velocity signals with the known and unknown structures of the master and slave manipulator dynamics. Using novel Lyapunov-Krasovskii functional, stability and tracking conditions of the coupled master-slave shared autonomous systems are developed under symmetrical and unsymmetrical time varying data transmission delays. This condition allows the designer to estimate the control design parameters to ensure position, velocity and synchronizing errors of the master and slave manipulators. Finally, evaluation results are presented to demonstrate the validity of the proposed design for real-time teleoperation applications.

  6. Probability of loss of assured safety in systems with multiple time-dependent failure modes.

    SciTech Connect

    Helton, Jon Craig; Pilch, Martin.; Sallaberry, Cedric Jean-Marie.

    2012-09-01

    Weak link (WL)/strong link (SL) systems are important parts of the overall operational design of high-consequence systems. In such designs, the SL system is very robust and is intended to permit operation of the entire system under, and only under, intended conditions. In contrast, the WL system is intended to fail in a predictable and irreversible manner under accident conditions and render the entire system inoperable before an accidental operation of the SL system. The likelihood that the WL system will fail to deactivate the entire system before the SL system fails (i.e., degrades into a configuration that could allow an accidental operation of the entire system) is referred to as probability of loss of assured safety (PLOAS). Representations for PLOAS for situations in which both link physical properties and link failure properties are time-dependent are derived and numerically evaluated for a variety of WL/SL configurations, including PLOAS defined by (i) failure of all SLs before failure of any WL, (ii) failure of any SL before failure of any WL, (iii) failure of all SLs before failure of all WLs, and (iv) failure of any SL before failure of all WLs. The effects of aleatory uncertainty and epistemic uncertainty in the definition and numerical evaluation of PLOAS are considered.

  7. Design and evaluation of a failure detection and isolation algorithm for restructurable control systems

    NASA Technical Reports Server (NTRS)

    Weiss, Jerold L.; Hsu, John Y.

    1986-01-01

    The use of a decentralized approach to failure detection and isolation for use in restructurable control systems is examined. This work has produced: (1) A method for evaluating fundamental limits to FDI performance; (2) Application using flight recorded data; (3) A working control element FDI system with maximal sensitivity to critical control element failures; (4) Extensive testing on realistic simulations; and (5) A detailed design methodology involving parameter optimization (with respect to model uncertainties) and sensitivity analyses. This project has concentrated on detection and isolation of generic control element failures since these failures frequently lead to emergency conditions and since knowledge of remaining control authority is essential for control system redesign. The failures are generic in the sense that no temporal failure signature information was assumed. Thus, various forms of functional failures are treated in a unified fashion. Such a treatment results in a robust FDI system (i.e., one that covers all failure modes) but sacrifices some performance when detailed failure signature information is known, useful, and employed properly. It was assumed throughout that all sensors are validated (i.e., contain only in-spec errors) and that only the first failure of a single control element needs to be detected and isolated. The FDI system which has been developed will handle a class of multiple failures.

  8. SWEPP PAN assay system uncertainty analysis: Passive mode measurements of graphite waste

    SciTech Connect

    Blackwood, L.G.; Harker, Y.D.; Meachum, T.R.; Yoon, Woo Y.

    1997-07-01

    The Idaho National Engineering and Environmental Laboratory is being used as a temporary storage facility for transuranic waste generated by the U.S. Nuclear Weapons program at the Rocky Flats Plant (RFP) in Golden, Colorado. Currently, there is a large effort in progress to prepare to ship this waste to the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. In order to meet the TRU Waste Characterization Quality Assurance Program Plan nondestructive assay compliance requirements and quality assurance objectives, it is necessary to determine the total uncertainty of the radioassay results produced by the Stored Waste Examination Pilot Plant (SWEPP) Passive Active Neutron (PAN) radioassay system. To this end a modified statistical sampling and verification approach has been developed to determine the total uncertainty of a PAN measurement. In this approach the total performance of the PAN nondestructive assay system is simulated using computer models of the assay system and the resultant output is compared with the known input to assess the total uncertainty. This paper is one of a series of reports quantifying the results of the uncertainty analysis of the PAN system measurements for specific waste types and measurement modes. In particular this report covers passive mode measurements of weapons grade plutonium-contaminated graphite molds contained in 208 liter drums (waste code 300). The validity of the simulation approach is verified by comparing simulated output against results from measurements using known plutonium sources and a surrogate graphite waste form drum. For actual graphite waste form conditions, a set of 50 cases covering a statistical sampling of the conditions exhibited in graphite wastes was compiled using a Latin hypercube statistical sampling approach.

  9. Analysis of substrate leachate from an innovative vertical flow AMD passive treatment system

    SciTech Connect

    Mercer, M.N.; Nairn, R.W.

    1999-07-01

    Although many organic substrate-based acid mine drainage (AMD) passive treatment systems have been constructed, analyses of initial leachate components has been limited. Labile organic materials, although providing an effective substrate for important bacterial processes in AMD treatment, may leach organic compounds, nutrients and other substances into receiving waters. Decreased dissolved oxygen levels, discoloration, nutrient enrichment and subsequent eutrophication may result. In this study, organic and inorganic components of substrate leachate from an innovative vertical flow acid mine drainage (AMD) passive treatment systems were determined during initial operation. A portion (approximately 17 L/minute) of an AMD discharge from an abandoned underground mine in southeastern Oklahoma was directed to a pilot-scale treatment system. The treatment system consists of four 185 m{sup 2} in-series cells and is comprised of alternating vertical flow anaerobic compost wetlands (VFs) and surface flow aerobic settling ponds (APs). the substrate in the VFs consists of spent mushroom substrate (SMS), high CaCO{sub 3} limestone gravel, and hydrated fly ash (HFA) in a 2:1:0.1 ratio by volume. HFA is a coal combustion product and has been identified as an effective alkalinity generating material in laboratory studies. Field data (pH, temperature, dissolved oxygen, conductivity and alkalinity) and water samples for subsequent analyses were collected at the discharge, at the inflow to each cell, and at several locations in the receiving waters. Initial data indicate pH increase to 7.3, and generation of approximately 150 mg/L alkalinity as CaCO{sub 3} eq. by the second aerobic settling pond. Total organic carbon, chemical oxygen demand, color, metals, and concentrations of other significant components were measured at all sampling locations.

  10. Optimisation of concentrating solar cell systems with passive and active cooling

    NASA Astrophysics Data System (ADS)

    Blumenberg, J.

    1983-10-01

    Design considerations for concentrator solar cell arrays for space applications are reviewed, noting the restrictions on total mass that govern system selections. Consideration is given to systems with parabolic mirrors and Si and GaAs solar cells. Passive and active cooling systems for the arrays are discussed, as is the addition of a heat engine with a turbogenerator to utilize part of the waste heat of the cooling cycle. Attention is given to systems orbiting at 0.5, 1, and 3.5 AU from the sun. Flat panels are found to be more suitable for missions near the sun for Si solar cells, while GaAs cells with concentration are preferred to flat panel systems at all distances from the sun. Nuclear turboelectric systems are better than concentrator Si arrays at large distances from the sun, in terms of specific masses of the systems. The addition of a system to use waste heat is judged unfavorable from specific mass factors.

  11. Agent autonomy approach to probabilistic physics-of-failure modeling of complex dynamic systems with interacting failure mechanisms

    NASA Astrophysics Data System (ADS)

    Gromek, Katherine Emily

    A novel computational and inference framework of the physics-of-failure (PoF) reliability modeling for complex dynamic systems has been established in this research. The PoF-based reliability models are used to perform a real time simulation of system failure processes, so that the system level reliability modeling would constitute inferences from checking the status of component level reliability at any given time. The "agent autonomy" concept is applied as a solution method for the system-level probabilistic PoF-based (i.e. PPoF-based) modeling. This concept originated from artificial intelligence (AI) as a leading intelligent computational inference in modeling of multi agents systems (MAS). The concept of agent autonomy in the context of reliability modeling was first proposed by M. Azarkhail [1], where a fundamentally new idea of system representation by autonomous intelligent agents for the purpose of reliability modeling was introduced. Contribution of the current work lies in the further development of the agent anatomy concept, particularly the refined agent classification within the scope of the PoF-based system reliability modeling, new approaches to the learning and the autonomy properties of the intelligent agents, and modeling interacting failure mechanisms within the dynamic engineering system. The autonomous property of intelligent agents is defined as agent's ability to self-activate, deactivate or completely redefine their role in the analysis. This property of agents and the ability to model interacting failure mechanisms of the system elements makes the agent autonomy fundamentally different from all existing methods of probabilistic PoF-based reliability modeling. 1. Azarkhail, M., "Agent Autonomy Approach to Physics-Based Reliability Modeling of Structures and Mechanical Systems", PhD thesis, University of Maryland, College Park, 2007.

  12. Preliminary Failure Modes and Effects Analysis of the US Massive Gas Injection Disruption Mitigation System Design

    SciTech Connect

    Lee C. Cadwallader

    2013-10-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a candidate design for the ITER Disruption Mitigation System. This candidate is the Massive Gas Injection System that provides machine protection in a plasma disruption event. The FMEA was quantified with “generic” component failure rate data as well as some data calculated from operating facilities, and the failure events were ranked for their criticality to system operation.

  13. Usefulness of a commercial equine IgG test and serum protein concentration as indicators of failure of transfer of passive immunity in hospitalized foals.

    PubMed

    Metzger, Nadine; Hinchcliff, Kenneth W; Hardy, Joanne; Schwarzwald, Colin C; Wittum, Thomas

    2006-01-01

    Detection of failure of transfer of passive immunity (FTPI) is important in reducing morbidity and mortality in neonatal foals. We investigated the performance of a commercial equine IgG test (SNAP Foal IgG Test Kit) to diagnose FTPI in hospitalized foals. Furthermore, we evaluated the usefulness of serum total protein (STP) and serum globulin (SG) concentrations as indicators of FTPI. Serum IgG concentration was measured by means of the SNAP test and single radial immunodiffusion, and SG and STP concentrations were determined by means of a clinical chemistry analyzer. Subjects were 67 hospitalized foals <19 days old. The SNAP test was repeated on 37 samples from 29 foals, with identical results for 24 samples (kappa statistic, 0.64; 95% confidence interval [CI], 0.46-0.82). The sensitivity of the SNAP test to detect serum IgG concentration [IgG] < or =400 and < or =800 mg/dl was 90% (95% CI, 71-98%) and 95% (85-99%), respectively, and the specificity was 79% (71-82%) and 52% (39-57%), respectively. Sensitivity for detection of [IgG] < or =400 mg/dl was not affected (P > .05) by plasma fibrinogen concentration, sepsis score, or bacteremia. Specificity for detection of [IgG] < or = 800 mg/dl was lower (P < .05) in foals with sepsis score < or =11 (50% [31-60%] versus 100% [8-100%]) and bacteremia (25% [5-56%] versus 62% [45-62%]). Sensitivity and specificity of [STP] < or = 5.0 g/dl for [IgG] < or =800 mg/dl was 94% (83-99%) and 47% (30-56%), respectively. Performance of the SNAP test in hospitalized foals is impaired because of low specificity, but can have usefulness provided that the properties of the test and characteristics of the foal being examined are considered when interpreting the results. The STP and SG concentrations are poor sole indicators of FTPI in hospitalized foals, but may be useful adjunctive tests.

  14. Wavelet features for failure detection and identification in vibration systems

    NASA Astrophysics Data System (ADS)

    Deckert, James C.; Rhenals, Alonso E.; Tenney, Robert R.; Willsky, Alan S.

    1992-12-01

    The result of this effort is an extremely flexible and powerful methodology for failure detection and identification (FDI) in vibrating systems. The essential elements of this methodology are: (1) an off-line set of techniques to identify high-energy, statistically significant features in the continuous wavelet transform (CWT); (2) a CWT-based preprocessor to extract the most useful features from the sensor signal; and (3) simple artificial neural networks (incorporating a mechanism to defer any decision if the current feature sample is determined to be ambiguous) for the subsequent classification task. For the helicopter intermediate gearbox test-stand data and centrifugal and fire pump shipboard (mild operating condition) data used, the algorithms designed using this method achieved perfect detection performance (1.000 probability of detection, and 0.000 false alarm probability), with a probability less than 0.04 that a decision would be deferred-based on only 500 milliseconds of data from each sample case. While this effort shows the exceptional promise of our wavelet-based method for FDI in vibrating systems, more demanding applications, which also have other sources of high-energy vibration, raise additional technical issues that could provide the focus for a Phase 2 effort.

  15. A Dynamical System that Describes Vein Graft Adaptation and Failure

    PubMed Central

    Garbey, Marc; Berceli, Scott A.

    2013-01-01

    Adaptation of vein bypass grafts to the mechanical stresses imposed by the arterial circulation is thought to be the primary determinant for lesion development, yet an understanding of how the various forces dictate local wall remodeling is lacking. We develop a dynamical system that summarizes the complex interplay between the mechanical environment and cell/matrix kinetics, ultimately dictating changes in the vein graft architecture. Based on a systematic mapping of the parameter space, three general remodeling response patterns are observed: 1) shear stabilized intimal thickening, 2) tension induced wall thinning and lumen expansion, and 3) tension stabilized wall thickening. Notable is our observation that the integration of multiple feedback mechanisms leads to a variety of non-linear responses that would be unanticipated by an analysis of each system component independently. This dynamic analysis supports the clinical observation that the majority of vein grafts proceed along an adaptive trajectory, where grafts dilate and mildly thicken in response to the increased tension and shear, but a small portion of the grafts demonstrate a maladaptive phenotype, where progressive inward remodeling and accentuated wall thickening lead to graft failure. PMID:23871714

  16. The Sandia MEMS passive shock sensor : FY07 maturation activities.

    SciTech Connect

    Houston, Jack E.; Blecke, Jill; Mitchell, John Anthony; Wittwer, Jonathan W.; Crowson, Douglas A.; Clemens, Rebecca C.; Walraven, Jeremy Allen; Epp, David S.; Baker, Michael Sean

    2008-08-01

    This report describes activities conducted in FY07 to mature the MEMS passive shock sensor. The first chapter of the report provides motivation and background on activities that are described in detail in later chapters. The second chapter discusses concepts that are important for integrating the MEMS passive shock sensor into a system. Following these two introductory chapters, the report details modeling and design efforts, packaging, failure analysis and testing and validation. At the end of FY07, the MEMS passive shock sensor was at TRL 4.

  17. Coding hazardous tree failures for a data management system

    Treesearch

    Lee A. Paine

    1978-01-01

    Codes for automatic data processing (ADP) are provided for hazardous tree failure data submitted on Report of Tree Failure forms. Definitions of data items and suggestions for interpreting ambiguously worded reports are also included. The manual is intended to insure the production of accurate and consistent punched ADP cards which are used in transfer of the data to...

  18. Direct Adaptive Control of Systems with Actuator Failures: State of the Art and Continuing Challenges

    NASA Technical Reports Server (NTRS)

    Tao, Gang; Joshi, Suresh M.

    2008-01-01

    In this paper, the problem of controlling systems with failures and faults is introduced, and an overview of recent work on direct adaptive control for compensation of uncertain actuator failures is presented. Actuator failures may be characterized by some unknown system inputs being stuck at some unknown (fixed or varying) values at unknown time instants, that cannot be influenced by the control signals. The key task of adaptive compensation is to design the control signals in such a manner that the remaining actuators can automatically and seamlessly take over for the failed ones, and achieve desired stability and asymptotic tracking. A certain degree of redundancy is necessary to accomplish failure compensation. The objective of adaptive control design is to effectively use the available actuation redundancy to handle failures without the knowledge of the failure patterns, parameters, and time of occurrence. This is a challenging problem because failures introduce large uncertainties in the dynamic structure of the system, in addition to parametric uncertainties and unknown disturbances. The paper addresses some theoretical issues in adaptive actuator failure compensation: actuator failure modeling, redundant actuation requirements, plant-model matching, error system dynamics, adaptation laws, and stability, tracking, and performance analysis. Adaptive control designs can be shown to effectively handle uncertain actuator failures without explicit failure detection. Some open technical challenges and research problems in this important research area are discussed.

  19. Developing healthcare rule-based expert systems: case study of a heart failure telemonitoring system.

    PubMed

    Seto, Emily; Leonard, Kevin J; Cafazzo, Joseph A; Barnsley, Jan; Masino, Caterina; Ross, Heather J

    2012-08-01

    The use of expert systems to generate automated alerts and patient instructions based on telemonitoring data could enable increased self-care and improve clinical management. However, of great importance is the development of the rule set to ensure safe and clinically relevant alerts and instructions are sent. The purpose of this work was to develop a rule-based expert system for a heart failure mobile phone-based telemonitoring system, to evaluate the expert system, and to generalize the lessons learned from the development process for use in other healthcare applications. Semi-structured interviews were conducted with 10 heart failure clinicians to inform the development of a draft heart failure rule set for alerts and patient instructions. The draft rule set was validated and refined with 9 additional interviews with heart failure clinicians. Finally, the clinical champion of the project vetted the rule set. The concerns voiced by the clinicians during the interviews were noted, and methods to mitigate these concerns were employed. The rule set was then evaluated as part of a 6-month randomized controlled trial of a mobile phone-based heart failure telemonitoring system (n=50 for each of the telemonitoring and control groups). The developed expert system generated alerts and instructions based on the patient's weight, blood pressure, heart rate, and symptoms. During the trial, 1620 alerts were generated, which led to various clinical actions including 105 medication changes/instructions. The findings from the trial indicated the rule set was associated with improved quality of life and self-care. A rule set was developed with extensive input by heart failure clinicians. The results from the trial indicated the rule set was associated with significantly increased self-care and improved the clinical management of heart failure. The developed rule set can be used as a basis for other heart failure telemonitoring systems, but should be validated and modified as

  20. Passive hybrid technique for the vibration mitigation of systems of interconnected stays

    NASA Astrophysics Data System (ADS)

    Caracoglia, Luca; Jones, Nicholas P.

    2007-11-01

    The problem of stay oscillation mitigation in cable-stayed bridges, usually induced by wind or wind and rain, may require the introduction of passive devices, such as dampers on individual stays or the use of transverse restrainers (cross-ties). The damper performance is often affected by the geometrical constraints of the bridge deck that limit the installation of such devices to locations very close to the end of the cable. On the other hand, cross-ties are generally incapable of direct energy dissipation. Therefore, the authors have proposed and analyzed a hybrid passive system in which the advantages of both techniques are applied to the oscillation mitigation of complex interconnected systems with multiple external dampers at the deck level, in correspondence with the cross-tie lines. This paper summarizes the relevant findings of a research program involving the authors' efforts focused on the in-plane free-vibration analysis of stay-cable systems. This research is also based upon some recent results associated with the analytical solution of a taut-cable with two attached viscous dampers. These findings are initially extended to a simplified network with reduced number of connectors and one damper, for which the derivation of analytical solution is still possible. Subsequently, an existing multistay multidamped arrangement on a real bridge is considered, in which a fully numerical approach is required. The modal behavior is compared to the simplified examples, also enabling the interpretation of the results in the context of more general guidelines for potential future application.