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Sample records for instantaneous reactive power

  1. Measurement and evaluation of instantaneous reactive power using neural networks

    SciTech Connect

    Chow, T.W.S.; Yam, Y.F. )

    1994-07-01

    The erratic disturbance caused by an electric arc furnace requires a fast and accurate VAr evaluation algorithm for compensation. This paper describes the development of a novel method using the approach of Artificial Neural Networks (ANN) to evaluate the instantaneous VAr. Comparing to the conventional methods, this neural network based algorithm is capable of operating at a much lower sampling rate and delivering an accurate and fast response output. By hardware implementation of this algorithm using neuron chips, the erratic VAr fluctuation can be accurately estimated for compensation.

  2. New Approach to Optimize the Apfs Placement Based on Instantaneous Reactive Power Theory by Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Hashemi-Dezaki, Hamed; Mohammadalizadeh-Shabestary, Masoud; Askarian-Abyaneh, Hossein; Rezaei-Jegarluei, Mohammad

    2014-01-01

    In electrical distribution systems, a great amount of power are wasting across the lines, also nowadays power factors, voltage profiles and total harmonic distortions (THDs) of most loads are not as would be desired. So these important parameters of a system play highly important role in wasting money and energy, and besides both consumers and sources are suffering from a high rate of distortions and even instabilities. Active power filters (APFs) are innovative ideas for solving of this adversity which have recently used instantaneous reactive power theory. In this paper, a novel method is proposed to optimize the allocation of APFs. The introduced method is based on the instantaneous reactive power theory in vectorial representation. By use of this representation, it is possible to asses different compensation strategies. Also, APFs proper placement in the system plays a crucial role in either reducing the losses costs and power quality improvement. To optimize the APFs placement, a new objective function has been defined on the basis of five terms: total losses, power factor, voltage profile, THD and cost. Genetic algorithm has been used to solve the optimization problem. The results of applying this method to a distribution network illustrate the method advantages.

  3. Reactive Power Compensator.

    DOEpatents

    El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

    1992-07-28

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

  4. Reactive power compensator

    DOEpatents

    El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  5. Design of Instantaneous High Power Supply System with power distribution management for portable military devices

    NASA Astrophysics Data System (ADS)

    Kwak, Kiho; Kwak, Dongmin; Yoon, Joohong

    2015-08-01

    A design of an Instantaneous High Power Supply System (IHPSS) with a power distribution management (PDM) for portable military devices is newly addressed. The system includes a power board and a hybrid battery that can not only supply instantaneous high power but also maintain stable operation at critical low temperature (-30 °C). The power leakage and battery overcharge are effectively prevented by the optimal PDM. The performance of the proposed system under the required pulse loads and the operating conditions of a Korean Advanced Combat Rifle employed in the battlefield is modeled with simulations and verified experimentally. The system with the IHPSS charged the fuse setter with 1.7 times higher voltage (8.6 V) than the one without (5.4 V) under the pulse discharging rate (1 A at 0.5 duty, 1 ms) for 500 ms.

  6. Development and validation of instantaneous risk model in nuclear power plant's risk monitor

    SciTech Connect

    Wang, J.; Li, Y.; Wang, F.; Wang, J.; Hu, L.

    2012-07-01

    The instantaneous risk model is the fundament of calculation and analysis in a risk monitor. This study focused on the development and validation of an instantaneous risk model. Therefore the principles converting from the baseline risk model to the instantaneous risk model were studied and separated trains' failure modes modeling method was developed. The development and validation process in an operating nuclear power plant's risk monitor were also introduced. Correctness of instantaneous risk model and rationality of converting method were demonstrated by comparison with the result of baseline risk model. (authors)

  7. Reactive power compensating system

    DOEpatents

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1987-01-01

    The reactive power of an induction machine is compensated by providing fixed capacitors on each phase line for the minimum compensation required, sensing the current on one line at the time its voltage crosses zero to determine the actual compensation required for each phase, and selecting switched capacitors on each line to provide the balance of the compensation required.

  8. Reactive Power Compensating System.

    DOEpatents

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1985-01-04

    The circuit was designed for the specific application of wind-driven induction generators. It has great potential for application in any situation where a varying reactive power load is present, such as with induction motors or generators, or for transmission network compensation.

  9. DC uninterrupted power supply having instantaneous switching followed by low impedance switching

    NASA Astrophysics Data System (ADS)

    Hammond, Russell E.; Northup, Robert L.; Shimp, Alan G.

    1991-10-01

    An uninterruptible power supply is provided that incorporates switching circuitry permitting a path for instantaneous DC backup power to be supplied to a voltage-declining primary power supply bus. Once the instantaneous transition is made, battery power is switched to a low impedance path to provide long-term battery power delivery to the bus. At a point where the backup batteries no longer supply useful power to a load, disabling circuitry disconnects the batteries from the load so that excessive draining of the batteries does not result in irreversible battery damage. The uninterruptible power supply of the invention further includes an automatic battery charging circuitry that seeks to maintain the power supply batteries at optimal charge level. To enable an operator to adequately assess battery charge condition, the invention provides battery test circuitry that causes a simulated load to appear at the power supply batteries. Visual representations are then made as to battery status.

  10. A Tariff for Reactive Power

    SciTech Connect

    Kueck, John D; Kirby, Brendan J; Li, Fangxing; Tufon, Christopher; Isemonger, Alan

    2008-07-01

    Two kinds of power are required to operate an electric power system: real power, measured in watts, and reactive power, measured in volt-amperes reactive or VARs. Reactive power supply is one of a class of power system reliability services collectively known as ancillary services, and is essential for the reliable operation of the bulk power system. Reactive power flows when current leads or lags behind voltage. Typically, the current in a distribution system lags behind voltage because of inductive loads such as motors. Reactive power flow wastes energy and capacity and causes voltage droop. To correct lagging power flow, leading reactive power (current leading voltage) is supplied to bring the current into phase with voltage. When the current is in phase with voltage, there is a reduction in system losses, an increase in system capacity, and a rise in voltage. Reactive power can be supplied from either static or dynamic VAR sources. Static sources are typically transmission and distribution equipment, such as capacitors at substations, and their cost has historically been included in the revenue requirement of the transmission operator (TO), and recovered through cost-of-service rates. By contrast, dynamic sources are typically generators capable of producing variable levels of reactive power by automatically controlling the generator to regulate voltage. Transmission system devices such as synchronous condensers can also provide dynamic reactive power. A class of solid state devices (called flexible AC transmission system devices or FACTs) can provide dynamic reactive power. One specific device has the unfortunate name of static VAR compensator (SVC), where 'static' refers to the solid state nature of the device (it does not include rotating equipment) and not to the production of static reactive power. Dynamic sources at the distribution level, while more costly would be very useful in helping to regulate local voltage. Local voltage regulation would reduce

  11. Instantaneous Active and Nonactive Power Control of Distributed Energy Resources with Current Limiter

    SciTech Connect

    Xu, Yan; Li, Huijuan; Rizy, D Tom; Li, Fangxing; Kueck, John D

    2010-01-01

    Abstract -- Distributed energy resources (DER) with a power electronics inverter interface can provide both active power and nonactive power simultaneously and independently. A decoupled control algorithm of active power and nonactive power is developed based on the instantaneous active power and nonactive power theory. A current limiter is combined to the control algorithm, and it ensures that the inverter is not overloaded. During the normal system operation, the active power has higher priority over the nonactive power so that the energy from a DER can be fully transferred to the grid. Within the inverter s capability, nonactive power is provided to the grid as required. With this control algorithm, the inverter s capabilities are taken full advantage at all times, both in terms of functionality as well as making use of its full KVA rating. Through the algorithm, the inverter s active power and nonactive power are controlled directly, simultaneously, and independently. Several experimental results fully demonstrate the validity and effectiveness of this new control algorithm. As evidenced by the fast dynamic response that results, a DER system with the control algorithm can provide full services to the grid in both steady state and during transient events.

  12. Local control of reactive power by distributed photovoltaic generators

    SciTech Connect

    Chertkov, Michael; Turitsyn, Konstantin; Sulc, Petr; Backhaus, Scott

    2010-01-01

    High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may severely degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We suggest a local control scheme that dispatches reactive power from each PV inverter based on local instantaneous measurements of the real and reactive components of the consumed power and the real power generated by the PVs. Using one adjustable parameter per circuit, we balance the requirements on power quality and desire to minimize thermal losses. Numerical analysis of two exemplary systems, with comparable total PV generation albeit a different spatial distribution, show how to adjust the optimization parameter depending on the goal. Overall, this local scheme shows excellent performance; it's capable of guaranteeing acceptable power quality and achieving significant saving in thermal losses in various situations even when the renewable generation in excess of the circuit own load, i.e. feeding power back to the higher-level system.

  13. Photonic instantaneous frequency measurement with digital output based on dispersion induced power fading functions

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Yang, Bo; Chi, Hao; Jin, Xiaofeng; Zheng, Shilie; Zhang, Xianmin

    2013-04-01

    A novel photonic approach to realize the instantaneous microwave frequency measurement with digital output is proposed and demonstrated experimentally. Based on the power fading function of a double-sideband modulated microwave signal transmitting in a dispersive fiber channel, the microwave frequency to digital code mapping can be realized in a multi-channel system where each channel is configured with a predetermined amount of dispersion. The coding process involved here is similar to that of the photonic analog-to-digital conversion. The principle of the system is discussed in detail. An experiment is carried out, in which the frequency identification with 4-bit quantization levels in 17.5 GHz measurement range is demonstrated. The measurement range and the resolution are discussed theoretically and numerically.

  14. Instantaneous Impulses.

    ERIC Educational Resources Information Center

    Erlichson, Herman

    2000-01-01

    Describes an experiment that extends Newton's instantaneous-impulse method of orbital analysis to a graphical method of orbit determination. Discusses the experiment's usefulness for teaching both horizontal projectile motion and instantaneous impulse. (WRM)

  15. Power-balancing instantaneous optimization energy management for a novel series-parallel hybrid electric bus

    NASA Astrophysics Data System (ADS)

    Sun, Dongye; Lin, Xinyou; Qin, Datong; Deng, Tao

    2012-11-01

    Energy management(EM) is a core technique of hybrid electric bus(HEB) in order to advance fuel economy performance optimization and is unique for the corresponding configuration. There are existing algorithms of control strategy seldom take battery power management into account with international combustion engine power management. In this paper, a type of power-balancing instantaneous optimization(PBIO) energy management control strategy is proposed for a novel series-parallel hybrid electric bus. According to the characteristic of the novel series-parallel architecture, the switching boundary condition between series and parallel mode as well as the control rules of the power-balancing strategy are developed. The equivalent fuel model of battery is implemented and combined with the fuel of engine to constitute the objective function which is to minimize the fuel consumption at each sampled time and to coordinate the power distribution in real-time between the engine and battery. To validate the proposed strategy effective and reasonable, a forward model is built based on Matlab/Simulink for the simulation and the dSPACE autobox is applied to act as a controller for hardware in-the-loop integrated with bench test. Both the results of simulation and hardware-in-the-loop demonstrate that the proposed strategy not only enable to sustain the battery SOC within its operational range and keep the engine operation point locating the peak efficiency region, but also the fuel economy of series-parallel hybrid electric bus(SPHEB) dramatically advanced up to 30.73% via comparing with the prototype bus and a similar improvement for PBIO strategy relative to rule-based strategy, the reduction of fuel consumption is up to 12.38%. The proposed research ensures the algorithm of PBIO is real-time applicability, improves the efficiency of SPHEB system, as well as suite to complicated configuration perfectly.

  16. Optimal reactive power control of grid connected photovoltaic resources

    NASA Astrophysics Data System (ADS)

    Trimble, Joshua Ryan

    As more photovoltaic distributed generation resources are installed on distribution power systems, selective control of the inverters connecting the DC power sources presents the opportunity to supply both real and reactive power at the point of common coupling. This thesis presents a simulated distribution system with individually controlled PV resources with the objective of minimizing total system losses while operating at the maximum power point and below the simulated rating of the associated inverters. The control strategy assumes the characteristics of the distribution system are known and solves for the optimal power flow operating point. The ability of each PV source to provide real and reactive power varies instantaneously as irradiance changes, so the operating point for each resource must be constantly recalculated and adjusted. The assumption of known system paramaters can be justified in a SmartGrid context, and a solution based on overall system power flow should be considered as a benchmark for any other state estimation or local control approaches.

  17. A Tariff for Reactive Power - IEEE

    SciTech Connect

    Kueck, John D; Tufon, Christopher; Isemonger, Alan; Kirby, Brendan J

    2008-11-01

    This paper describes a suggested tariff or payment for the local supply of reactive power from distributed energy resources. The authors consider four sample customers, and estimate the cost of supply of reactive power for each customer. The power system savings from the local supply of reactive power are also estimated for a hypothetical circuit. It is found that reactive power for local voltage regulation could be supplied to the distribution system economically by customers when new inverters are installed. The inverter would be supplied with a power factor of 0.8, and would be capable of local voltage regulation to a schedule supplied by the utility. Inverters are now installed with photovoltaic systems, fuel cells and microturbines, and adjustable-speed motor drives.

  18. Water reactive hydrogen fuel cell power system

    DOEpatents

    Wallace, Andrew P; Melack, John M; Lefenfeld, Michael

    2014-11-25

    A water reactive hydrogen fueled power system includes devices and methods to combine reactant fuel materials and aqueous solutions to generate hydrogen. The generated hydrogen is converted in a fuel cell to provide electricity. The water reactive hydrogen fueled power system includes a fuel cell, a water feed tray, and a fuel cartridge to generate power for portable power electronics. The removable fuel cartridge is encompassed by the water feed tray and fuel cell. The water feed tray is refillable with water by a user. The water is then transferred from the water feed tray into the fuel cartridge to generate hydrogen for the fuel cell which then produces power for the user.

  19. Water reactive hydrogen fuel cell power system

    DOEpatents

    Wallace, Andrew P; Melack, John M; Lefenfeld, Michael

    2014-01-21

    A water reactive hydrogen fueled power system includes devices and methods to combine reactant fuel materials and aqueous solutions to generate hydrogen. The generated hydrogen is converted in a fuel cell to provide electricity. The water reactive hydrogen fueled power system includes a fuel cell, a water feed tray, and a fuel cartridge to generate power for portable power electronics. The removable fuel cartridge is encompassed by the water feed tray and fuel cell. The water feed tray is refillable with water by a user. The water is then transferred from the water feed tray into a fuel cartridge to generate hydrogen for the fuel cell which then produces power for the user.

  20. Compensation for Harmonic Currents and Reactive Power in Wind Power Generation System using PWM Inverter

    NASA Astrophysics Data System (ADS)

    Shinohara, Katsuji; Shinhatsubo, Kurato; Iimori, Kenichi; Yamamoto, Kichiro; Saruban, Takamichi; Yamaemori, Takahiro

    In recent year, consciousness of environmental problems is enhancing, and the price of the electric power purchased by an electric power company is established expensive for the power plant utilizing the natural energy. So, the introduction of the wind power generation is promoted in Japan. Generally, squirrel-cage induction machines are widely used as a generator in wind power generation system because of its small size, lightweight and low-cost. However, the induction machines do not have a source of excitation. Thus, it causes the inrush currents and the instantaneous voltage drop when the generator is directly connected to a power grid. To reduce the inrush currents, an AC power regulator is used. Wind power generations are frequently connected to and disconnected from the power grid. However, when the inrush currents are reduced, harmonic currents are caused by phase control of the AC power regulator. And the phase control of AC power regulator cannot control the power factor. Therefore, we propose the use of the AC power regulator to compensate for the harmonic currents and reactive power in the wind power generation system, and demonstrate the validity of its system by simulated and experimental results.

  1. 77 FR 11109 - Reactive Power Resources; Notice of Technical Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ... Energy Regulatory Commission Reactive Power Resources; Notice of Technical Conference The Federal Energy... docket highlights potential issues regarding the need for reactive power capability among newly... technical conference to examine whether the Commission should reconsider or modify the reactive...

  2. Photovoltaic solar system connected to the electric power grid operating as active power generator and reactive power compensator

    SciTech Connect

    Albuquerque, Fabio L.; Moraes, Adelio J.; Guimaraes, Geraldo C.; Sanhueza, Sergio M.R.; Vaz, Alexandre R.

    2010-07-15

    In the case of photovoltaic (PV) systems acting as distributed generation (DG) systems, the DC energy that is produced is fed to the grid through the power-conditioning unit (inverter). The majority of contemporary inverters used in DG systems are current source inverters (CSI) operating at unity power factor. If, however, we assume that voltage source inverters (VSI) can replace CSIs, we can generate reactive power proportionally to the remaining unused capacity at any given time. According to the theory of instantaneous power, the inverter reactive power can be regulated by changing the amplitude of its output voltage. In addition, the inverter active power can be adjusted by modifying the phase angle of its output voltage. Based on such theory, both the active power supply and the reactive power compensation (RPC) can be carried out simultaneously. When the insolation is weak or the PV modules are inoperative at night, the RPC feature of a PV system can still be used to improve the inverter utilisation factor. Some MATLAB simulation results are included here to show the feasibility of the method. (author)

  3. On reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.

    2016-01-01

    High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition (IPVD) technique that is particularly promising for reactive sputtering applications. However, there are few issues that have to be resolved before the full potential of this technique can be realized. Here we give an overview of the key experimental findings for the reactive HiPIMS discharge. An increase in the discharge current is commonly observed with increased partial pressure of the reactive gas or decreased repetition pulse frequency. There are somewhat conflicting claims regarding the hysteresis effect in the reactive HiPIMS discharge as some report reduction or elimination of the hysteresis effect while others claim a feedback control is essential. The ion energy distribution of the metal ion and the atomic ion of the reactive gas are similar and extend to very high energies while the ion energy distribution of the working gas and the molecular ion of the reactive gas are similar and are much less energetic.

  4. A heuristic method for reactive power planning

    SciTech Connect

    Mantovani, J.R.S.

    1996-02-01

    An approach for solving reactive power planning problems is presented, which is based on binary search techniques and the use of a special heuristic to obtain a discrete solution. Two versions were developed, one to run on conventional (sequential) computers and the other to run on a distributed memory (hypercube) machine. This latter parallel processing version employs an asynchronous programming model. Once the set of candidate bases has been defined, the program gives the location and size of the reactive sources needed (if any) in keeping with operating and security constraints.

  5. Reactive power management and voltage control in deregulated power markets

    NASA Astrophysics Data System (ADS)

    Spangler, Robert G.

    The research that is the subject of this dissertation is about the management of reactive power and voltage support in the wholesale open access power markets in the United States (US). The purpose of this research is to place decisions about open access market structures, as they relate to reactive power and voltage control, on a logical and consistent economic basis, given the engineering needs of a commercial electric power system. An examination of the electricity markets operating in the US today reveals that current approaches to reactive power management and voltage support are extensions of those based on historical, regulated monopoly electric service. A case for change is built by first looking at the subject of reactive power from an engineering viewpoint and then from an economic perspective. Ultimately, a set of market rules for managing reactive power and voltage support is proposed. The proposal suggests that cost recovery for static and dynamic VARs is appropriately accomplished through the regulated transmission cost of service. Static VAR cost recovery should follow traditional rate recovery methodologies. In the case of dynamic VARs, this work provides a methodology based on the microeconomic theory of the firm for determining such cost. It further suggests that an operational strategy that reduces and limits the use of dynamic VARs, during normal operations, is appropriate. This latter point leads to an increase in the fixed cost of the transmission network but prevents price spikes and short supply situations from affecting, or being affected by, the reactive capability limitations associated with dynamic VARs supplied from synchronous generators. The rules are consistent with a market structure that includes competitive generation and their application will result in the communication of a clear understanding of the responsibilities, related to voltage control, of each type of market entity. In this sense, their application will contribute to

  6. New hybrid active power filter for harmonic current suppression and reactive power compensation

    NASA Astrophysics Data System (ADS)

    Biricik, Samet; Cemal Ozerdem, Ozgur; Redif, Soydan; Sezai Dincer, Mustafa

    2016-08-01

    In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.

  7. 77 FR 24949 - Reactive Power Resources; Supplemental Notice Requesting Comments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-26

    ... Energy Regulatory Commission Reactive Power Resources; Supplemental Notice Requesting Comments On April... whether the Commission should reconsider or modify the reactive power provisions of Order No. 661-A and examine what evidence could be developed under Order No. 661 to support a request to apply reactive...

  8. Control circuit maintains unity power factor of reactive load

    NASA Technical Reports Server (NTRS)

    Kramer, M.; Martinage, L. H.

    1966-01-01

    Circuit including feedback control elements automatically corrects the power factor of a reactive load. It maintains power supply efficiency where negative load reactance changes and varies by providing corrective error signals to the control windings of a power supply transformer.

  9. Reactive power optimization by genetic algorithm

    SciTech Connect

    Iba, Kenji )

    1994-05-01

    This paper presents a new approach to optimal reactive power planning based on a genetic algorithm. Many outstanding methods to this problem have been proposed in the past. However, most of these approaches have the common defect of being caught to a local minimum solution. The integer problem which yields integer value solutions for discrete controllers/banks still remains as a difficult one. The genetic algorithm is a kind of search algorithm based on the mechanics of natural selection and genetics. This algorithm can search for a global solution using multiple paths and treat integer problems naturally. The proposed method was applied to practical 51-bus and 224-bus systems to show its feasibility and capabilities. Although this method is not as fast as sophisticated traditional methods, the concept is quite promising and useful.

  10. Voltage Stability Impact of Grid-Tied Photovoltaic Systems Utilizing Dynamic Reactive Power Control

    NASA Astrophysics Data System (ADS)

    Omole, Adedamola

    Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid, although this feature is currently rarely utilized as most DG systems are designed to operate with unity power factor and supply real power only to the grid. In this work, the voltage stability of a power system embedded with PV DG is examined in the context of the high reactive power requirement after a voltage sag or fault. A real-time dynamic multi-function power controller that enables renewable source PV DGs to provide the reactive power support necessary to maintain the voltage stability of the microgrid, and consequently, the wider power system is proposed. The loadability limit necessary to maintain the voltage stability of an interconnected microgrid is determined by using bifurcation analysis to test for the singularity of the network Jacobian and load differential equations with and without the contribution of the DG. The maximum and minimum real and reactive power support permissible from the DG is obtained from the loadability limit and used as the limiting factors in controlling the real and reactive power contribution from the PV source. The designed controller regulates the voltage output based on instantaneous power theory at the point-of-common coupling (PCC) while the reactive power supply is controlled by means of the power factor and reactive current droop method. The control method is implemented in a modified IEEE 13-bus test feeder system using PSCADRTM power system analysis software and is applied to the model of a Tampa ElectricRTM PV installation at Lowry Park Zoo in Tampa, FL. This dissertation accomplishes the systematic analysis of the voltage impact of a PV DG-embedded power distribution system. The method employed in this work bases the contribution of the PV resource on the voltage stability margins of the microgrid rather than the commonly used loss-of-load probability (LOLP) and effective load-carrying capability (ELCC) measures. The results of

  11. Distributed control of reactive power flow in a radial distribution circuit with high photovoltaic penetration

    SciTech Connect

    Chertkov, Michael; Turitsyn, Konstantin; Backhaus, Scott; Sule, Petr

    2009-01-01

    We show how distributed control of reactive power can serve to regulate voltage and minimize resistive losses in a distribution circuit that includes a significant level of photovoltaic (PV) generation. To demonstrate the technique, we consider a radial distribution circuit with a single branch consisting of sequentially-arranged residential-scale loads that consume both real and reactive power. In parallel, some loads also have PV generation capability. We postulate that the inverters associated with each PV system are also capable of limited reactive power generation or consumption, and we seek to find the optimal dispatch of each inverter's reactive power to both maintain the voltage within an acceptable range and minimize the resistive losses over the entire circuit. We assume the complex impedance of the distribution circuit links and the instantaneous load and PV generation at each load are known. We compare the results of the optimal dispatch with a suboptimal local scheme that does not require any communication. On our model distribution circuit, we illustrate the feasibility of high levels of PV penetration and a significant (20% or higher) reduction in losses.

  12. Optimized Reactive Power Compensation Using Fuzzy Logic Controller

    NASA Astrophysics Data System (ADS)

    George, S.; Mini, K. N.; Supriya, K.

    2015-03-01

    Reactive power flow in a long transmission line plays a vital role in power transfer capability and voltage stability in power system. Traditionally, shunt connected compensators are used to control reactive power in long transmission line. Thyristor controlled reactor is used to control reactive power under lightly loaded condition. By controlling firing angle of thyristor, it is possible to control reactive power in the transmission lines. However, thyristor controlled reactor will inject harmonic current into the system. An attempt to reduce reactive power injection will increase harmonic distortion in the line current and vice versa. Thus, there is a trade-off between reactive power injection and harmonics in current. By optimally controlling the reactive power injection, harmonics in current can be brought within the specified limit. In this paper, a Fuzzy Logic Controller is implemented to obtain optimal control of reactive power of the compensator to maintain voltage and harmonic in current within the limits. An algorithm which optimizes the firing angle in each fuzzy subset by calculating the rank of feasible firing angles is proposed for the construction of rules in Fuzzy Logic Controller. The novelty of the algorithm is that it uses a simple error formula for the calculation of the rank of the feasible firing angles in each fuzzy subset.

  13. Assessment of the Economic Benefits from Reactive Power Compensation

    SciTech Connect

    Li, Fangxing; Kueck, John D; Rizy, D Tom; Tolbert, Leon M; Zhang, Wenjuan

    2006-01-01

    The U.S. power industry is under great pressure to provide reactive power or Var support. Although it is generally known that there are technical benefits for utilities and industrial customers to provide local reactive power support, a thorough quantitative investigation of the economic benefit is greatly needed. This paper seeks to provide a quantitative approach to evaluate the benefits from local reactive power compensation. This paper investigates the benefits including reduced losses, shifting reactive power flow to real power flow, and increased transfer capability. These benefits are illustrated with a simple two-bus model and then presented with a more complicated model using Optimal Power Flow. Tests are conducted on a system with seven buses in two areas. These simulations show that the economic benefits can be significant, if compared with capacity payment to central generators or power factor penalties applied to utilities. This economic value may give utilities a better understanding of the Var benefits to assist their cost-benefit analysis for Var compensation. In addition, since the economic benefits are significant, this paper suggests that the future reactive power market should consider local Var providers.

  14. Instantaneous Frequency Attribute Comparison

    NASA Astrophysics Data System (ADS)

    Yedlin, M. J.; Margrave, G. F.; Ben Horin, Y.

    2013-12-01

    The instantaneous seismic data attribute provides a different means of seismic interpretation, for all types of seismic data. It first came to the fore in exploration seismology in the classic paper of Taner et al (1979), entitled " Complex seismic trace analysis". Subsequently a vast literature has been accumulated on the subject, which has been given an excellent review by Barnes (1992). In this research we will compare two different methods of computation of the instantaneous frequency. The first method is based on the original idea of Taner et al (1979) and utilizes the derivative of the instantaneous phase of the analytic signal. The second method is based on the computation of the power centroid of the time-frequency spectrum, obtained using either the Gabor Transform as computed by Margrave et al (2011) or the Stockwell Transform as described by Stockwell et al (1996). We will apply both methods to exploration seismic data and the DPRK events recorded in 2006 and 2013. In applying the classical analytic signal technique, which is known to be unstable, due to the division of the square of the envelope, we will incorporate the stabilization and smoothing method proposed in the two paper of Fomel (2007). This method employs linear inverse theory regularization coupled with the application of an appropriate data smoother. The centroid method application is straightforward and is based on the very complete theoretical analysis provided in elegant fashion by Cohen (1995). While the results of the two methods are very similar, noticeable differences are seen at the data edges. This is most likely due to the edge effects of the smoothing operator in the Fomel method, which is more computationally intensive, when an optimal search of the regularization parameter is done. An advantage of the centroid method is the intrinsic smoothing of the data, which is inherent in the sliding window application used in all Short-Time Fourier Transform methods. The Fomel technique

  15. Static reactive power compensators for high-voltage power systems. Final report

    SciTech Connect

    Not Available

    1981-04-01

    A study conducted to summarize the role of static reactive power compensators for high voltage power system applications is described. This information should be useful to the utility system planning engineer in applying static var systems (SVS) to high voltage as (HVAC) systems. The static var system is defined as a form of reactive power compensator. The general need for reactive power compensation in HVAC systems is discussed, and the static var system is compared to other devices utilized to provide reactive power compensation. Examples are presented of applying SVS for specific functions, such as the prevention of voltage collapse. The operating principles of commercially available SVS's are discussed in detail. The perormance and active power loss characteristics of SVS types are compared.

  16. Index-based reactive power compensation scheme for voltage regulation

    NASA Astrophysics Data System (ADS)

    Dike, Damian Obioma

    2008-10-01

    Increasing demand for electrical power arising from deregulation and the restrictions posed to the construction of new transmission lines by environment, socioeconomic, and political issues had led to higher grid loading. Consequently, voltage instability has become a major concern, and reactive power support is vital to enhance transmission grid performance. Improved reactive power support to distressed grid is possible through the application of relatively unfamiliar emerging technologies of "Flexible AC Transmission Systems (FACTS)" devices and "Distributed Energy Resources (DERS)." In addition to these infrastructure issues, a lack of situational awareness by system operators can cause major power outages as evidenced by the August 14, 2003 widespread North American blackout. This and many other recent major outages have highlighted the inadequacies of existing power system indexes. In this work, a novel "Index-based reactive compensation scheme" appropriate for both on-line and off-line computation of grid status has been developed. A new voltage stability index (Ls-index) suitable for long transmission lines was developed, simulated, and compared to the existing two-machine modeled L-index. This showed the effect of long distance power wheeling amongst regional transmission organizations. The dissertation further provided models for index modulated voltage source converters (VSC) and index-based load flow analysis of both FACTS and microgrid interconnected power systems using the Newton-Raphson's load flow model incorporated with multi-FACTS devices. The developed package has been made user-friendly through the embodiment of interactive graphical user interface and implemented on the IEEE 14, 30, and 300 bus systems. The results showed reactive compensation has system wide-effect, provided readily accessible system status indicators, ensured seamless DERs interconnection through new islanding modes and enhanced VSC utilization. These outcomes may contribute

  17. Development of Voltage Reactive Power Control Considering Load Change

    NASA Astrophysics Data System (ADS)

    Shimone, Takaaki; Yatsubo, Osamu; Ishigame, Atsushi; Hasegawa, Tsuguto

    Modern power system has become large and complex networks, which require more flexible system operation. Voltage and reactive power control (VQC) that transports more electric powers especially maintaining voltages within range of constraints is expected to become more important for a high-performance system operation. In this paper, we propose a new technique of VQC considering load change with a short-term load forecasting and an optimal control by a new Meta-heuristics technique with combination of Particle Swarm Optimization (PSO) and Tabu Search (TS).

  18. Application of Newton's optimal power flow in voltage/reactive power control

    SciTech Connect

    Bjelogrlic, M.; Babic, B.S. ); Calovic, M.S. ); Ristanovic, P. )

    1990-11-01

    This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system security and economy is also proposed. For the real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states.

  19. Comparative Studies of Particle Swarm Optimization Techniques for Reactive Power Allocation Planning in Power Systems

    NASA Astrophysics Data System (ADS)

    Fukuyama, Yoshikazu

    This paper compares particle swarm optimization (PSO) techniques for a reactive power allocation planning problem in power systems. The problem can be formulated as a mixed-integer nonlinear optimization problem (MINLP). The PSO based methods determines a reactive power allocation strategy with continuous and discrete state variables such as automatic voltage regulator (AVR) operating values of electric power generators, tap positions of on-load tap changer (OLTC) of transformers, and the number of reactive power compensation equipment. Namely, this paper investigates applicability of PSO techniques to one of the practical MINLPs in power systems. Four variations of PSO: PSO with inertia weight approach (IWA), PSO with constriction factor approach (CFA), hybrid particle swarm optimization (HPSO) with IWA, and HPSO with CFA are compared. The four methods are applied to the standard IEEE14 bus system and a practical 112 bus system.

  20. Modified artificial bee colony algorithm for reactive power optimization

    NASA Astrophysics Data System (ADS)

    Sulaiman, Noorazliza; Mohamad-Saleh, Junita; Abro, Abdul Ghani

    2015-05-01

    Bio-inspired algorithms (BIAs) implemented to solve various optimization problems have shown promising results which are very important in this severely complex real-world. Artificial Bee Colony (ABC) algorithm, a kind of BIAs has demonstrated tremendous results as compared to other optimization algorithms. This paper presents a new modified ABC algorithm referred to as JA-ABC3 with the aim to enhance convergence speed and avoid premature convergence. The proposed algorithm has been simulated on ten commonly used benchmarks functions. Its performance has also been compared with other existing ABC variants. To justify its robust applicability, the proposed algorithm has been tested to solve Reactive Power Optimization problem. The results have shown that the proposed algorithm has superior performance to other existing ABC variants e.g. GABC, BABC1, BABC2, BsfABC dan IABC in terms of convergence speed. Furthermore, the proposed algorithm has also demonstrated excellence performance in solving Reactive Power Optimization problem.

  1. Voltage and Reactive Power Control by Parallel Calculation Processing

    NASA Astrophysics Data System (ADS)

    Michihata, Masashi; Aoki, Hidenori; Mizutani, Yoshibumi

    This paper presents a new approach to optimal voltage and reactive power control based on a genetic algorithm (GA) and a tabu search (TS). To reduce time to calculate the control procedure, the parallel computation using Linux is executed. In addition, TS and GA are calculated by the master and each slave based on the parallel program language. The effectiveness of the proposed method is demonstrated by practical 118-bus system.

  2. Minimization of Reactive Power Fluctuation in JT-60SA Magnet Power Supply

    NASA Astrophysics Data System (ADS)

    Shimada, K.; Terakado, T.; Yamauchi, K.; Matsukawa, M.; Baulaigue, O.; Coletti, R.; Coletti, A.; Novello, L.

    2013-02-01

    This paper describes an asymmetric control method for the firing angle and a start/stop timing shift control of four thyristor converters called “Booster PS" to minimize the reactive power fluctuation during plasma initiation in JT-60SA. From the simulation using the “PSCAD/EMTDC" code, it is found that these control methods can drastically reduce the reactive power induced by the four units of the “Booster PS". In addition, the voltage fluctuation of the motor-generator connected to the “Booster PS" is expected to be suppressed. This can also contribute to achieve stable control of the JT-60SA magnet power supplies.

  3. A Single-Phase Current Source Solar Inverter with Constant Instantaneous Power, Improved Reliability, and Reduced-Size DC-Link Filter

    NASA Astrophysics Data System (ADS)

    Bush, Craig R.

    This dissertation presents a novel current source converter topology that is primarily intended for single-phase photovoltaic (PV) applications. In comparison with the existing PV inverter technology, the salient features of the proposed topology are: a) the low frequency (double of line frequency) ripple that is common to single-phase inverters is greatly reduced; b) the absence of low frequency ripple enables significantly reduced size pass components to achieve necessary DC-link stiffness and c) improved maximum power point tracking (MPPT) performance is readily achieved due to the tightened current ripple even with reduced-size passive components. The proposed topology does not utilize any electrolytic capacitors. Instead an inductor is used as the DC-link filter and reliable AC film capacitors are utilized for the filter and auxiliary capacitor. The proposed topology has a life expectancy on par with PV panels. The proposed modulation technique can be used for any current source inverter where an unbalanced three-phase operation is desires such as active filters and power controllers. The proposed topology is ready for the next phase of microgrid and power system controllers in that it accepts reactive power commands. This work presents the proposed topology and its working principle supported by with numerical verifications and hardware results. Conclusions and future work are also presented.

  4. A fuzzy-based optimal reactive power control

    SciTech Connect

    Abdul-Rahman, K.H.; Shahidehpour, S.M. . Dept. of Electrical and Computer Engineering)

    1993-05-01

    This paper presents a mathematical formulation for the optimal reactive power control problem using the fuzzy set theory. The objectives are to minimize real power losses and improve the voltage profile of a given system. Transmission loses are expressed in terms of voltage increments by relating the control variables, i.e., tap positions of transformers and reactive power injections of VAR sources, to the voltage increments in a modified Jacobian matrix. This specific formulation of the problem does not require the Jacobian matrix inversion, and hence it will save computation time and memory space. The objective function and the constraints are modeled by fuzzy sets. Linear membership functions of the fuzzy sets are defined and the fuzzy linear optimization problem is formulated. The solution space in this case is defined as the intersection of the fuzzy sets describing the constraints and the objective functions. Each solution is characterized by a parameter that determines the degree of satisfaction with the solution. The optimal solution is the one with the maximum value for the satisfaction parameter. Results for the application of this approach on test systems reveal its numerous advantages.

  5. Short-term scheduling of reactive power controllers

    SciTech Connect

    Hong Yingyi; Liao Csongming

    1995-05-01

    A two-level approach is presented to solve the problem of optimal short-term (one day) scheduling of reactive power controllers in this paper. The entire problem is decomposed into two levels: the master and the slave levels. The master level deals with minimization of the depreciation cost of compensators and EHV transformer taps in order to reduce the control action for compensators and EHV transformer taps while satisfying operating constraints. The slave level treats minimization of capitalized MW losses while satisfying system security constraints. The slave level also treats OLTCs and determines scheduling of the generator voltages. These two levels interact through linear constraints in the iteration process. A practical 265-bus system, namely Taiwan Power System, are used to serve as a sample to show the applicability of the presented approach.

  6. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1985-01-01

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas.

  7. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1985-09-03

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas. 5 figs.

  8. 78 FR 77670 - Zero Rate Reactive Power Rate Schedules; Notice Allowing Post-Workshop Comments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-24

    ... Comments On December 11, 2013, a Commission staff-led workshop explored the mechanics of filing reactive... written comments focused on the mechanics of filing reactive power rate schedules for which there is...

  9. Unified active and reactive power modulation of HVDC transmission systems

    NASA Astrophysics Data System (ADS)

    Grund, C. E.; Pohl, R. V.

    1981-11-01

    The power modulation of a high voltage direct current (HVDC) system for stabilization of an ac/dc network was investigated. It was found that simultaneous modulation of both dc current and voltage was more effective than just current modulation by itself, since the dc voltage modulation could be used to minimize the reactive power changes resulting from a change of the dc current. This helps stabilize the ac busbar voltages at the converters, which reduces undesirable load flow changes to voltage dependent ac loads, thus improving the effectiveness of the dc power modulation. This unified modulation control concept was evaluated by means of digital computer studies as well as a special purpose HVDC simulator. Several combined ac/dc power transmission systems were synthesized for testing of different modulation controller concepts. An optimum controller design incorporating a linear quadratic control algorithm with full state feedback was first studied. This provided a basis for comparison of suboptimal controller designs utilizing reduced state feedback and a Kalman filter state reconstruction technique.

  10. Investigation on application of genetic algorithms to optimal reactive power dispatch of power systems

    NASA Astrophysics Data System (ADS)

    Wu, Q. H.; Ma, J. T.

    1993-09-01

    A primary investigation into application of genetic algorithms in optimal reactive power dispatch and voltage control is presented. The application was achieved, based on (the United Kingdom) National Grid 48 bus network model, using a novel genetic search approach. Simulation results, compared with that obtained using nonlinear programming methods, are included to show the potential of applications of the genetic search methodology in power system economical and secure operations.

  11. Secure provision of reactive power ancillary services in competitive electricity markets

    NASA Astrophysics Data System (ADS)

    El-Samahy, Ismael

    The research work presented in this thesis discusses various complex issues associated with reactive power management and pricing in the context of new operating paradigms in deregulated power systems, proposing appropriate policy solutions. An integrated two-level framework for reactive power management is set forth, which is both suitable for a competitive market and ensures a secure and reliable operation of the associated power system. The framework is generic in nature and can be adopted for any electricity market structure. The proposed hierarchical reactive power market structure comprises two stages: procurement of reactive power resources on a seasonal basis, and real-time reactive power dispatch. The main objective of the proposed framework is to provide appropriate reactive power support from service providers at least cost, while ensuring a secure operation of the power system. The proposed procurement procedure is based on a two-step optimization model. First, the marginal benefits of reactive power supply from each provider, with respect to system security, are obtained by solving a loadability-maximization problem subject to transmission security constraints imposed by voltage and thermal limits. Second, the selected set of generators is determined by solving an optimal power flow (OPF)-based auction. This auction maximizes a societal advantage function comprising generators' offers and their corresponding marginal benefits with respect to system security, and considering all transmission system constraints. The proposed procedure yields the selected set of generators and zonal price components, which would form the basis for seasonal contracts between the system operator and the selected reactive power service providers. The main objective of the proposed reactive power dispatch model is to minimize the total payment burden on the Independent System Operator (ISO), which is associated with reactive power dispatch. The real power generation is

  12. Advanced configuration of hybrid passive filter for reactive power and harmonic compensation.

    PubMed

    Kececioglu, O Fatih; Acikgoz, Hakan; Sekkeli, Mustafa

    2016-01-01

    Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. Simulation results show that performance of reactive power and harmonic compensation with advanced hybrid passive filter is better than conventional hybrid passive filters. PMID:27536512

  13. Local Dynamic Reactive Power for Correction of System Voltage Problems

    SciTech Connect

    Kueck, John D; Rizy, D Tom; Li, Fangxing; Xu, Yan; Li, Huijuan; Adhikari, Sarina; Irminger, Philip

    2008-12-01

    Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors and because the use of electric A/C is growing in use and becoming a larger percentage of system load. A method for local dynamic voltage regulation is discussed which uses reactive power injection or absorption from local DER. This method is independent, rapid, and will not interfere with conventional utility system voltage control. The results of simulations of this method are provided. The method has also been tested at the ORNL s Distributed Energy Communications and Control (DECC) Laboratory using our research inverter and synchronous condenser. These systems at the DECC Lab are interconnected to an actual distribution system, the ORNL distribution system, which is fed from TVA s 161kV sub-transmission backbone. The test results

  14. Distance Relaying with Power Swing Detection based on Voltage and Reactive Power Sensitivity

    NASA Astrophysics Data System (ADS)

    Patel, Ujjaval J.; Chothani, Nilesh G.; Bhatt, Praghnesh J.

    2016-02-01

    Sudden changes in loading or configuration of an electrical network causes power swing which may result in an unwanted tripping of the distance relay. Hence, it becomes utmost necessary to rapidly and reliably discriminate between actual fault and power swing conditions in order to prevent instability in power network due to mal operation of distance relay. This paper proposes a novel method for the discrimination between fault and power swing based on rate of change of voltage and reactive power measured at relay location. The effectiveness of the proposed algorithm is evaluated by simulating series of power swing conditions in PSCAD/EMTDC® software for different disturbances such as change in mechanical power input to synchronous generator, tripping of parallel line due to fault and sudden application of heavy load. It is revealed that the distance relay gives successful tripping in case of different fault conditions and remains inoperative for power swing with the implementation of the proposed algorithm. Moreover, the proposed scheme has ability to distinguish the symmetrical and asymmetrical fault occurrence during power swing condition.

  15. A flexible active and reactive power control strategy for a variable speed constant frequency generating system

    SciTech Connect

    Tang, Y.; Xu, L.

    1995-07-01

    Variable-speed constant-frequency generating systems are used in wind power, hydro power, aerospace, and naval power generations to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising of doubly excited induction machine or doubly excited brushless reluctance machine and PWM converters with a dc link. In this paper, a flexible active and reactive power control strategy is developed, such that the optimal torque-speed profile of the turbine can be followed and overall reactive power can be controlled, while the machine copper losses have been minimized. At the same time, harmonics injected into the power network has also been minimized. In this manner, the system can function as both a high-efficient power generator and a flexible reactive power compensator.

  16. Assessment of the Economic Potential of Microgrids for Reactive Power Supply

    SciTech Connect

    Appen, Jan von; Marnay, Chris; Stadler, Michael; Momber, Ilan; Klapp, David; Scheven, Alexander von

    2011-05-01

    As power generation from variable distributed energy resources (DER) grows, energy flows in the network are changing, increasing the requirements for ancillary services, including voltage support. With the appropriate power converter, DER can provide ancillary services such as frequency control and voltage support. This paper outlines the economic potential of DERs coordinated in a microgrid to provide reactive power and voltage support at its point of common coupling. The DER Customer Adoption Model assesses the costs of providing reactive power, given local utility rules. Depending on the installed DER, the cost minimizing solution for supplying reactive power locally is chosen. Costs include the variable cost of the additional losses and the investment cost of appropriately over-sizing converters or purchasing capacitors. A case study of a large health care building in San Francisco is used to evaluate different revenue possibilities of creating an incentive for microgrids to provide reactive power.

  17. Instantaneous fields in classical electrodynamics

    NASA Astrophysics Data System (ADS)

    Heras, J. A.

    2005-01-01

    In this paper we express the retarded fields of Maxwell's theory in terms of the instantaneous fields of a Galilei-invariant electromagnetic and we find the vector function χL whose spatial and temporal derivatives transform the Euclidean fields into the retarded ones. We conclude that the instantaneous fields can formally be introduced as unphysical objects into classical electrodynamics which can be used to find the physical retarded fields.

  18. Common station system for voltage and reactive power regulation at the Mosenergo TETs-27 heating and electric power plant

    SciTech Connect

    Krasnova, M. E.

    2009-05-15

    The system for common station regulation of the voltage and reactive power at the Mosenergo TETs-27 heating and electric power plant is described briefly. Features of the algorithms for this system, which uses programs and instrumentation from the automatic control system for the electrical equipment in the 450 MW power generation unit No. 3, are examined.

  19. Fixed costs of providing ancillary services from power plants: Reactive supply and voltage control, regulation and frequency response, operating reserve--spinning. Final report

    SciTech Connect

    Boyle, R.; Kure-Jensen, J.

    1998-12-01

    This report describes methodologies to determine the fixed costs for a steam cycle generating unit to participate in Reactive Supply and Voltage Control (RS-VC), Regulation and Frequency Response (RFR), and Operating Reserve-Spinning (ORS) services. It is intended for use by a Generator of electricity who is planning to offer these ancillary services in a competitive market. The methodology is based on common steam power plant engineering and economic principles. Reactive supply and voltage control provides reactive supply through changes to generator reactive output to maintain acceptable transmission system voltages and facilitate electricity transfers and provides the ability to continually adjust transmission system voltage in response to system changes. Regulation and frequency response service include all rapid load changes whether their purpose is to meet the instantaneous load demand, to balance control area supply resources with load, or to maintain frequency. Spinning reserve is provided by generating units that are on-line and loaded at less than maximum output. They are available to serve load immediately in an unexpected contingency such as an unplanned outage of a generating unit.

  20. The instantaneous frequency rate spectrogram

    NASA Astrophysics Data System (ADS)

    Czarnecki, Krzysztof

    2016-01-01

    An accelerogram of the instantaneous phase of signal components referred to as an instantaneous frequency rate spectrogram (IFRS) is presented as a joint time-frequency distribution. The distribution is directly obtained by processing the short-time Fourier transform (STFT) locally. A novel approach to amplitude demodulation based upon the reassignment method is introduced as a useful by-product. Additionally, an estimator of energy density versus the instantaneous frequency rate (IFR) is proposed and referred to as the IFR profile. The energy density is estimated based upon both the classical energy spectrogram and the IFRS smoothened by the median filter. Moreover, the impact of an analyzing window width, additive white Gaussian noise and observation time is tested. Finally, the introduced method is used for the analysis of the acoustic emission of an automotive engine. The recording of the engine of a Lamborghini Gallardo is analyzed as an example.

  1. Reactive Inkjet Printing: Reactive Inkjet Printing of Biocompatible Enzyme Powered Silk Micro-Rockets (Small 30/2016).

    PubMed

    Gregory, David A; Zhang, Yu; Smith, Patrick J; Zhao, Xiubo; Ebbens, Stephen J

    2016-08-01

    On page 4048, X. Zhao, S. J. Ebbens, and co-workers demonstrate the ability to fabricate biocompatible silk microrockets via reactive inkjet printing. The microrockets are powered by catalase and undergo bubble propulsion in the presence of hydrogen peroxide. Microrockets are capable of swimming in a large variety of media including biological solutions. Inkjet printing allows digital definition of enzyme distribution within the silk scaffold to control rocket directionality. PMID:27492495

  2. Perspective on fossil power plant layup and reactivation

    SciTech Connect

    Tsou, J.L.

    1996-12-31

    In recent years, many utilities have developed excess generation capacity problems during period of low system load growth, particularly with new generation units coming on-line. System load studies may indicate that the situation is temporary and higher generation capacity will be needed in the near future. The objective of layup is to prevent component deterioration during the long shut down periods. This paper discusses equipment preservation practices in use by the electric utility industry and the advantages/disadvantages of various layup methods. Other issues related to plant layup and reactivation are also presented.

  3. On the Sequential Control of ITER Poloidal Field Converters for Reactive Power Reduction

    NASA Astrophysics Data System (ADS)

    Yuan, Hongwen; Fu, Peng; Gao, Ge; Huang, Liansheng; Song, Zhiquan; He, Shiying; Wu, Yanan; Dong, Lin; Wang, Min; Fang, Tongzhen

    2014-12-01

    Sequential control applied to the International Thermonuclear Experimental Reactor (ITER) poloidal field converter system for the purpose of reactive power reduction is the subject of this investigation. Due to the inherent characteristics of thyristor-based phase-controlled converter, the poloidal field converter system consumes a huge amount of reactive power from the grid, which subsequently results in a voltage drop at the 66 kV busbar if no measure is taken. The installation of a static var compensator rated for 750 MVar at the 66 kV busbar is an essential way to compensate reactive power to the grid, which is the most effective measure to solve the problem. However, sequential control of the multi-series converters provides an additional method to improve the natural power factor and thus alleviate the pressure of reactive power demand of the converter system without any additional cost. In the present paper, by comparing with the symmetrical control technique, the advantage of sequential control in reactive power consumption is highlighted. Simulation results based on SIMULINK are found in agreement with the theoretical analysis.

  4. Preparation of hydrogenated diamond-like carbon films by reactive Ar/CH4 high power impulse magnetron sputtering with negative pulse voltage

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    High power impulse magnetron sputtering (HiPIMS) has been attracted, because sputtered target species are highly ionized. High densities of active species such as radical ions and neutral radicals can be also achieved owing to high density reactive HiPIMS plasmas. We investigate properties of hydrogenated diamond-like carbon films prepared by reactive HiPIMS of Ar/CH4 gas mixture. The properties of the films strongly depend on the plasma compositions and the kinetic energy of the carbon-containing ions which can enter into the films. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz, changing CH4 fraction up to 15%. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 36 A. A negative pulse voltage is applied to the substrates for about 10 μs after the target voltage changed from about -600 V to 0 V. The structural properties are characterized by Raman spectroscopy and nano-indentation method. Film hardness strongly depends on the magnitude of negative pulse voltage. By adjusting the magnitude of negative voltage, the film hardness ranges between about 10 and 22 GPa. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  5. 78 FR 63176 - Notice Announcing Workshop; Zero Rate Reactive Power Rate Schedules

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Notice Announcing Workshop; Zero Rate Reactive Power Rate Schedules Concurrent with this notice, the Commission is issuing an order in Chehalis Power Generating, L.P., Docket...

  6. Genetic algorithms for optimal reactive power compensation planning on the national grid system

    NASA Astrophysics Data System (ADS)

    Pilgrim, J. D.

    This work investigates the use of Genetic Algorithms (GAs) for optimal Reactive power Compensation Planning (RCP) of practical power systems. In particular, RCP of the transmission system of England and Wales as owned and operated by National Grid is considered. The GA is used to simultaneously solve both the siting problem---optimisation of the installation of new devices---and the operational problem---optimisation of preventive transformer taps and the controller characteristics of dynamic compensation devices. A computer package called Genetic Compensation Placement (GCP) has been developed which uses an Integer coded GA (IGA) to solve the RCP problem. The RCP problem is implemented as a multi-objective optimisation: in the interests of security, the number of system and operational constraint violations and the deviation of the busbar voltages from the ideal are all minimised for the base (intact) case and the contingent cases. In the interests of cost reduction, the reactive power cost is minimised for the base case. The reactive power cost encompasses the costs incurred from the installation of reactive power sources and the utilisation of new and existing dynamic reactive power compensation devices. GCP is compared to SCORPION (a planning program currently being used by National Grid) which uses a combination of linear programming and heuristic back-tracking. Results are presented for a practical test system developed with the cooperation of National Grid, and it is found that GCP produces solutions that are cheaper than solutions found by SCORPION and perform extremely well: an improvement in voltage profiles, a decrease in complex power mismatches, and a reduction in MVolt Amps-reactive (VAr) utilisation were observed.

  7. EV/PHEV Bidirectional Charger Assessment for V2G Reactive Power Operation

    SciTech Connect

    Kisacikoglu, Mithat C; Ozpineci, Burak; Tolbert, Leon M

    2013-01-01

    This paper presents a summary of the available single-phase ac-dc topologies used for EV/PHEV, level-1 and -2 on-board charging and for providing reactive power support to the utility grid. It presents the design motives of single-phase on-board chargers in detail and makes a classification of the chargers based on their future vehicle-to-grid usage. The pros and cons of each different ac-dc topology are discussed to shed light on their suitability for reactive power support. This paper also presents and analyzes the differences between charging-only operation and capacitive reactive power operation that results in increased demand from the dc-link capacitor (more charge/discharge cycles and increased second harmonic ripple current). Moreover, battery state of charge is spared from losses during reactive power operation, but converter output power must be limited below its rated power rating to have the same stress on the dc-link capacitor.

  8. Reactive power interconnection requirements for PV and wind plants : recommendations to NERC.

    SciTech Connect

    McDowell, Jason; Walling, Reigh; Peter, William; Von Engeln, Edi; Seymour, Eric; Nelson, Robert; Casey, Leo; Ellis, Abraham; Barker, Chris.

    2012-02-01

    Voltage on the North American bulk system is normally regulated by synchronous generators, which typically are provided with voltage schedules by transmission system operators. In the past, variable generation plants were considered very small relative to conventional generating units, and were characteristically either induction generator (wind) or line-commutated inverters (photovoltaic) that have no inherent voltage regulation capability. However, the growing level of penetration of non-traditional renewable generation - especially wind and solar - has led to the need for renewable generation to contribute more significantly to power system voltage control and reactive power capacity. Modern wind-turbine generators, and increasingly PV inverters as well, have considerable dynamic reactive power capability, which can be further enhanced with other reactive support equipment at the plant level to meet interconnection requirements. This report contains a set of recommendations to the North-America Electricity Reliability Corporation (NERC) as part of Task 1-3 (interconnection requirements) of the Integration of Variable Generation Task Force (IVGTF) work plan. The report discusses reactive capability of different generator technologies, reviews existing reactive power standards, and provides specific recommendations to improve existing interconnection standards.

  9. 78 FR 63177 - Order on Voluntary Remand and Clarifying Policy on Filing of Reactive Power Service Rate...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-23

    ... Generation Sources Service (reactive power) to the Bonneville Power Administration (Bonneville or BPA) is a....'' \\5\\ The Commission stated that ``Chehalis has been providing reactive power to BPA pursuant to an... interconnection agreement between Chehalis and BPA was required to be filed prior to May 2005, even though it...

  10. Interpolation Approximation of Voltage Stability Constrained OPF (VSCOPF) for Reactive Power Planning

    SciTech Connect

    Tolbert, Leon M; Zhang, Wenjuan; Li, Fangxing

    2011-01-01

    Reactive power planning (RPP), or Var planning, is to identify the optimal size and location of reactive power sources. In this paper, first, the previous work using least square method to simplify the voltage stability constrained OPF (VSCOPF) model for RPP is presented. Then, this paper presents a new model simplification solution using interpolation. The interpolation approach can be easily applied to a piecewise formulation while preserving the continuity at boundary points, which cannot be easily achieved by previous works like the least square method. The proposed interpolation approach is numerically tested and compared with the least square approach. It is concluded that interpolation is an improved model simplification approach for RPP.

  11. Reactive power planning under high penetration of wind energy using Benders decomposition

    DOE PAGESBeta

    Xu, Yan; Wei, Yanli; Fang, Xin; Li, Fangxing; Azim, Riyasat

    2015-11-05

    This study addresses the optimal allocation of reactive power volt-ampere reactive (VAR) sources under the paradigm of high penetration of wind energy. Reactive power planning (RPP) in this particular condition involves a high level of uncertainty because of wind power characteristic. To properly model wind generation uncertainty, a multi-scenario framework optimal power flow that considers the voltage stability constraint under the worst wind scenario and transmission N 1 contingency is developed. The objective of RPP in this study is to minimise the total cost including the VAR investment cost and the expected generation cost. Therefore RPP under this condition ismore » modelled as a two-stage stochastic programming problem to optimise the VAR location and size in one stage, then to minimise the fuel cost in the other stage, and eventually, to find the global optimal RPP results iteratively. Benders decomposition is used to solve this model with an upper level problem (master problem) for VAR allocation optimisation and a lower problem (sub-problem) for generation cost minimisation. Impact of the potential reactive power support from doubly-fed induction generator (DFIG) is also analysed. Lastly, case studies on the IEEE 14-bus and 118-bus systems are provided to verify the proposed method.« less

  12. Reactive power planning under high penetration of wind energy using Benders decomposition

    SciTech Connect

    Xu, Yan; Wei, Yanli; Fang, Xin; Li, Fangxing; Azim, Riyasat

    2015-11-05

    This study addresses the optimal allocation of reactive power volt-ampere reactive (VAR) sources under the paradigm of high penetration of wind energy. Reactive power planning (RPP) in this particular condition involves a high level of uncertainty because of wind power characteristic. To properly model wind generation uncertainty, a multi-scenario framework optimal power flow that considers the voltage stability constraint under the worst wind scenario and transmission N 1 contingency is developed. The objective of RPP in this study is to minimise the total cost including the VAR investment cost and the expected generation cost. Therefore RPP under this condition is modelled as a two-stage stochastic programming problem to optimise the VAR location and size in one stage, then to minimise the fuel cost in the other stage, and eventually, to find the global optimal RPP results iteratively. Benders decomposition is used to solve this model with an upper level problem (master problem) for VAR allocation optimisation and a lower problem (sub-problem) for generation cost minimisation. Impact of the potential reactive power support from doubly-fed induction generator (DFIG) is also analysed. Lastly, case studies on the IEEE 14-bus and 118-bus systems are provided to verify the proposed method.

  13. Asymptotic Rayleigh instantaneous unit hydrograph

    USGS Publications Warehouse

    Troutman, B.M.; Karlinger, M.R.

    1988-01-01

    The instantaneous unit hydrograph for a channel network under general linear routing and conditioned on the network magnitude, N, tends asymptotically, as N grows large, to a Rayleigh probability density function. This behavior is identical to that of the width function of the network, and is proven under the assumption that the network link configuration is topologically random and the link hydraulic and geometric properties are independent and identically distributed random variables. The asymptotic distribution depends only on a scale factor, {Mathematical expression}, where ?? is a mean link wave travel time. ?? 1988 Springer-Verlag.

  14. Examination of a PHEV Bi-Directional Charger System for V2G Reactive Power Compensation

    SciTech Connect

    Kisacikoglu, Mithat C; Ozpineci, Burak; Tolbert, Leon M

    2010-01-01

    Plug-in hybrid electric vehicles (PHEVs) potentially have the capability to fulfill the energy storage needs of the electric grid by supplying ancillary services such as reactive power compensation. However, in order to allow bidirectional power transfer, the PHEV battery charger should be designed to manage such capability. While many different battery chargers have been available since the inception of the first electric vehicles (EVs), an on-board, conductive charger with bidirectional power transferring capability have recently drawn attention due to their inherent advantages in charging accessibility, ease of use and efficiency. In this study, a reactive power compensation case study using the inverter dc-link capacitor is given when a PHEV battery is under charging operation. Finally, the impact of providing these services on the batteries is also explained.

  15. Voltage and Reactive Power Control by Integration of Genetic Algorithm and Tabu Search

    NASA Astrophysics Data System (ADS)

    Aoki, Hidenori; Yamamoto, Kensei; Mizutani, Yoshibumi

    This paper presents on the result of voltage and reactive power control by use of the proposed method. The feature of proposed method is integration of genetic algorithm (GA) and tabu search (TS). This method obtains an excellent fitness at shorter calculation time than GA considering conventional control process. The effectiveness of this method is shown by a practicable 15-bus system.

  16. 78 FR 72673 - Zero Rate Reactive Power Rate Schedules; Notice of Staff Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Zero Rate Reactive Power Rate Schedules; Notice of Staff Workshop This.... to 4 p.m. at the Federal Energy Regulatory Commission, 888 First Street NE., Washington, DC...

  17. 78 FR 75562 - Zero Rate Reactive Power Rate Schedules; Notice of Staff Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-12

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Zero Rate Reactive Power Rate Schedules; Notice of Staff Workshop This... on December 11, 2013 from 1:30 p.m. to 4 p.m. at the Federal Energy Regulatory Commission, 888...

  18. 77 FR 21555 - Reactive Power Resources; Supplemental Notice of Technical Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-10

    ... Interconnection Studies. This panel will discuss: Methods used to determine the reactive power requirements for a... Robert Jenkins, Director--Utility Interconnection, First Solar Kris Zadlo, Vice President, Invenergy..., Director--Utility Interconnection, First Solar Michael Jacobs, Director Market and Regulatory...

  19. Real Power and Reactive Power Control of a Three-Phase Single-Stage-PV System and PV voltage Stability

    SciTech Connect

    Li, Huijuan; Xu, Yan; Adhikari, Sarina; Rizy, D Tom; Li, Fangxing; Irminger, Philip

    2012-01-01

    Grid-connected photovoltaic (PV) systems with power electronic interfaces can provide both real and reactive power to meet power system needs with appropriate control algorithms. This paper presents the control algorithm design for a three-phase single-stage grid-connected PV inverter to achieve either maximum power point tracking (MPPT) or a certain amount of real power injection, as well as the voltage/var control. The switching between MPPT control mode and a certain amount of real power control mode is automatic and seamless. Without the DC-to-DC booster stage, PV DC voltage stability is an important issue in the control design especially when the PV inverter is operating at maximum power point (MPP) with voltage/var control. The PV DC voltage collapse phenomenon and its reason are discussed. The method based on dynamic correction of the PV inverter output is proposed to ensure PV DC voltage stability. Simulation results of the single-stage PV system during system disturbances and fast solar irradiation changes confirm that the proposed control algorithm for single-stage PV inverters can provide appropriate real and reactive power services and ensure PV DC voltage stability during dynamic system operation and atmospheric conditions.

  20. A parametric model for reactive high-power impulse magnetron sputtering of films

    NASA Astrophysics Data System (ADS)

    Kozák, Tomáš; Vlček, Jaroslav

    2016-02-01

    We present a time-dependent parametric model for reactive HiPIMS deposition of films. Specific features of HiPIMS discharges and a possible increase in the density of the reactive gas in front of the reactive gas inlets placed between the target and the substrate are considered in the model. The model makes it possible to calculate the compound fractions in two target layers and in one substrate layer, and the deposition rate of films at fixed partial pressures of the reactive and inert gas. A simplified relation for the deposition rate of films prepared using a reactive HiPIMS is presented. We used the model to simulate controlled reactive HiPIMS depositions of stoichiometric \\text{Zr}{{\\text{O}}2} films, which were recently carried out in our laboratories with two different configurations of the {{\\text{O}}2} inlets in front of the sputtered target. The repetition frequency was 500 Hz at the deposition-averaged target power densities of 5 Wcm-2and 50 Wcm-2 with a pulse-averaged target power density up to 2 kWcm-2. The pulse durations were 50 μs and 200 μs. Our model calculations show that the to-substrate {{\\text{O}}2} inlet provides systematically lower compound fractions in the target surface layer and higher compound fractions in the substrate surface layer, compared with the to-target {{\\text{O}}2} inlet. The low compound fractions in the target surface layer (being approximately 10% at the deposition-averaged target power density of 50 Wcm-2 and the pulse duration of 200 μs) result in high deposition rates of the films produced, which are in agreement with experimental values.

  1. Some Statistics of Instantaneous Precipitation.

    NASA Astrophysics Data System (ADS)

    Jones, Douglas M. A.; Wendland, Wayne M.

    1984-09-01

    Known sources of data from arrays of instantaneous precipitation intensity recorders in southern Germany, east-central Illinois, northeastern Illinois, central Florida, and Hilo, Hawaii are obtained. These data are analyzed for line averages of the percent frequency of occurrence of the exceedance of selected threshold precipitation intensities. The correlation coefficients of the precipitation intensity at sites at varying distances from a reference site are determined. The decay in correlation is found to be a function of climatic region and the type of precipitation: showery or continuous. Showery rains are found to be essentially uncorrelated about 12 km from the reference site while continuous rain exhibits no correlation beyond about 50 km.Single-station intensity data collected at Urbana, Illinois; Paris, France; Inyanga, Zimbabwe; Bogor, Indonesia; Reading, United Kingdom; Island Beach, New Jersey; Miami, Florida; Franklin, North Carolina; and Majuro, Marshall Islands, are compared.

  2. Movable-molybdenum-reflector reactivity experiments for control studies of compact space power reactor concepts

    NASA Technical Reports Server (NTRS)

    Fox, T. A.

    1973-01-01

    An experimental reflector reactivity study was made with a compact cylindrical reactor using a uranyl fluoride - water fuel solution. The reactor was axially unreflected and radially reflected with segments of molybdenum. The reflector segments were displaced incrementally in both the axial and radial dimensions, and the shutdown of each configuration was measured by using the pulsed-neutron source technique. The reactivity effects for axial and radial displacement of reflector segments are tabulated separately and compared. The experiments provide data for control-system studies of compact-space-power-reactor concepts.

  3. Optimal reactive power planning for distribution systems considering intermittent wind power using Markov model and genetic algorithm

    NASA Astrophysics Data System (ADS)

    Li, Cheng

    Wind farms, photovoltaic arrays, fuel cells, and micro-turbines are all considered to be Distributed Generation (DG). DG is defined as the generation of power which is dispersed throughout a utility's service territory and either connected to the utility's distribution system or isolated in a small grid. This thesis addresses modeling and economic issues pertaining to the optimal reactive power planning for distribution system with wind power generation (WPG) units. Wind farms are inclined to cause reverse power flows and voltage variations due to the random-like outputs of wind turbines. To deal with this kind of problem caused by wide spread usage of wind power generation, this thesis investigates voltage and reactive power controls in such a distribution system. Consequently static capacitors (SC) and transformer taps are introduced into the system and treated as controllers. For the purpose of getting optimum voltage and realizing reactive power control, the research proposes a proper coordination among the controllers like on-load tap changer (OLTC), feeder-switched capacitors. What's more, in order to simulate its uncertainty, the wind power generation is modeled by the Markov model. In that way, calculating the probabilities for all the scenarios is possible. Some outputs with consecutive and discrete values have been used for transition between successive time states and within state wind speeds. The thesis will describe the method to generate the wind speed time series from the transition probability matrix. After that, utilizing genetic algorithm, the optimal locations of SCs, the sizes of SCs and transformer taps are determined so as to minimize the cost or minimize the power loss, and more importantly improve voltage profiles. The applicability of the proposed method is verified through simulation on a 9-bus system and a 30-bus system respectively. At last, the simulation results indicate that as long as the available capacitors are able to sufficiently

  4. Reactive Power Laboratory: Synchronous Condenser Testing&Modeling Results - Interim Report

    SciTech Connect

    Henry, SD

    2005-09-27

    The subject report documents the work carried out by Oak Ridge National Laboratory (ORNL) during months 5-7 (May-July 2005) of a multi-year research project. The project has the overall goal of developing methods of incorporating distributed energy (DE) that can produce reactive power locally and for injecting into the distribution system. The objective for this new type of DE is to be able to provide voltage regulation and dynamic reactive power reserves without the use of extensive communication and control systems. The work performed over this three-month period focused on four aspects of the overall objective: (1) characterization of a 250HP (about 300KVAr) synchronous condenser (SC) via test runs at the ORNL Reactive Power Laboratory; (2) development of a data acquisition scheme for collecting the necessary voltage, current and power readings at the synchronous condenser and on the distribution system; (3) development of algorithms for analyzing raw test data from the various test runs; and (4) validation of a steady-state model for the synchronous condenser via the use of a commercial software package to study its effects on the ORNL 13.8/2.4kV distribution network.

  5. Mechanism of instantaneous coal outbursts

    SciTech Connect

    Guan, P.; Wang, H.Y.; Zhang, Y.X.

    2009-10-15

    Thousands of mine workers die every year from mining accidents, and instantaneous coal outbursts in underground coal mines are one of the major killers. Various models for these outbursts have been proposed, but the precise mechanism is still unknown. We hypothesize that the mechanism of coal outbursts is similar to magma fragmentation during explosive volcanic eruptions; i.e., it is caused by high gas pressure inside coal but low ambient pressure on it, breaking coal into pieces and releasing the high-pressure gas in a shock wave. Hence, coal outbursts may be regarded as another type of gas-driven eruption, in addition to explosive volcanic, lake, and possible ocean eruptions. We verify the hypothesis by experiments using a shock-tube apparatus. Knowing the mechanism of coal outbursts is the first step in developing prediction and mitigation measures. The new concept of gas-driven solid eruption is also important to a better understanding of salt-gas outbursts, rock-gas outbursts, and mud volcano eruptions.

  6. Estimating instantaneous respiratory rate from the photoplethysmogram.

    PubMed

    Dehkordi, Parastoo; Garde, Ainara; Molavi, Behnam; Petersen, Christian L; Ansermino, J Mark; Dumont, Guy A

    2015-08-01

    The photoplethysmogram (PPG) obtained from pulse oximetry shows the local changes of blood volume in tissues. Respiration induces variation in the PPG baseline due to the variation in venous blood return during each breathing cycle. We have proposed an algorithm based on the synchrosqueezing transform (SST) to estimate instantaneous respiratory rate (IRR) from the PPG. The SST is a combination of wavelet analysis and a reallocation method which aims to sharpen the time-frequency representation of the signal and can provide an accurate estimation of instantaneous frequency. In this application, the SST was applied to the PPG and IRR was detected as the predominant ridge in the respiratory band (0.1 Hz - 1 Hz) in the SST plane. The algorithm was tested against the Capnobase benchmark dataset that contains PPG, capnography, and expert labelled reference respiratory rate from 42 subjects. The IRR estimation accuracy was assessed using the root mean square (RMS) error and Bland-Altman plot. The median RMS error was 0.39 breaths/min for all subjects which ranged from the lowest error of 0.18 breaths/min to the highest error of 13.86 breaths/min. A Bland-Altman plot showed an agreement between the IRR obtained from PPG and reference respiratory rate with a bias of -0.32 and limits agreement of -7.72 to 7.07. Extracting IRR from PPG expands the functionality of pulse oximeters and provides additional diagnostic power to this non-invasive monitoring tool. PMID:26737696

  7. Regularization of Instantaneous Frequency Attribute Computations

    NASA Astrophysics Data System (ADS)

    Yedlin, M. J.; Margrave, G. F.; Van Vorst, D. G.; Ben Horin, Y.

    2014-12-01

    We compare two different methods of computation of a temporally local frequency:1) A stabilized instantaneous frequency using the theory of the analytic signal.2) A temporally variant centroid (or dominant) frequency estimated from a time-frequency decomposition.The first method derives from Taner et al (1979) as modified by Fomel (2007) and utilizes the derivative of the instantaneous phase of the analytic signal. The second method computes the power centroid (Cohen, 1995) of the time-frequency spectrum, obtained using either the Gabor or Stockwell Transform. Common to both methods is the necessity of division by a diagonal matrix, which requires appropriate regularization.We modify Fomel's (2007) method by explicitly penalizing the roughness of the estimate. Following Farquharson and Oldenburg (2004), we employ both the L curve and GCV methods to obtain the smoothest model that fits the data in the L2 norm.Using synthetic data, quarry blast, earthquakes and the DPRK tests, our results suggest that the optimal method depends on the data. One of the main applications for this work is the discrimination between blast events and earthquakesFomel, Sergey. " Local seismic attributes." , Geophysics, 72.3 (2007): A29-A33.Cohen, Leon. " Time frequency analysis theory and applications." USA: Prentice Hall, (1995).Farquharson, Colin G., and Douglas W. Oldenburg. "A comparison of automatic techniques for estimating the regularization parameter in non-linear inverse problems." Geophysical Journal International 156.3 (2004): 411-425.Taner, M. Turhan, Fulton Koehler, and R. E. Sheriff. " Complex seismic trace analysis." Geophysics, 44.6 (1979): 1041-1063.

  8. A Preliminary Analysis of the Economics of Using Distributed Energy as a Source of Reactive Power Supply

    SciTech Connect

    Li, Fangxing; Kueck, John D; Rizy, D Tom; King, Thomas F

    2006-04-01

    A major blackout affecting 50 million people in the Northeast United States, where insufficient reactive power supply was an issue, and an increased number of filings made to the Federal Energy Regulatory Commission by generators for reactive power has led to a closer look at reactive power supply and compensation. The Northeastern Massachusetts region is one such area where there is an insufficiency in reactive power compensation. Distributed energy due to its close proximity to loads seems to be a viable option for solving any present or future reactive power shortage problems. Industry experts believe that supplying reactive power from synchronized distributed energy sources can be 2 to 3 times more effective than providing reactive support in bulk from longer distances at the transmission or generation level. Several technology options are available to supply reactive power from distributed energy sources such as small generators, synchronous condensers, fuel cells or microturbines. In addition, simple payback analysis indicates that investments in DG to provide reactive power can be recouped in less than 5 years when capacity payments for providing reactive power are larger than $5,000/kVAR and the DG capital and installation costs are lower than $30/kVAR. However, the current institutional arrangements for reactive power compensation present a significant barrier to wider adoption of distributed energy as a source of reactive power. Furthermore, there is a significant difference between how generators and transmission owners/providers are compensated for reactive power supplied. The situation for distributed energy sources is even more difficult, as there are no arrangements to compensate independent DE owners interested in supplying reactive power to the grid other than those for very large IPPs. There are comparable functionality barriers as well, as these smaller devices do not have the control and communications requirements necessary for automatic

  9. TLBO based Voltage Stable Environment Friendly Economic Dispatch Considering Real and Reactive Power Constraints

    NASA Astrophysics Data System (ADS)

    Verma, H. K.; Mafidar, P.

    2013-09-01

    In view of growing concern towards environment, power system engineers are forced to generate quality green energy. Hence the economic dispatch (ED) aims at the power generation to meet the load demand at minimum fuel cost with environmental and voltage constraints along with essential constraints on real and reactive power. The emission control which reduces the negative impact on environment is achieved by including the additional constraints in ED problem. Presently, the power system mostly operates near its stability limits, therefore with increased demand the system faces voltage problem. The bus voltages are brought within limit in the present work by placement of static var compensator (SVC) at weak bus which is identified from bus participation factor. The optimal size of SVC is determined by univariate search method. This paper presents the use of Teaching Learning based Optimization (TLBO) algorithm for voltage stable environment friendly ED problem with real and reactive power constraints. The computational effectiveness of TLBO is established through test results over particle swarm optimization (PSO) and Big Bang-Big Crunch (BB-BC) algorithms for the ED problem.

  10. Modeling for V—O2 reactive sputtering process using a pulsed power supply

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Yu, He; Dong, Xiang; Jiang, Ya-Dong; Chen, Chao; Wu, Ro-Land

    2014-08-01

    In this article, we present a time-dependent model that enables us to describe the dynamic behavior of pulsed DC reactive sputtering and predict the film compositions of VOx prepared by this process. In this modeling, the average current J is replaced by a new parameter of Jeff. Meanwhile, the four species states of V, V2O3, VO2, and V2O5 in the vanadium oxide films are taken into consideration. Based on this work, the influences of the oxygen gas supply and the pulsed power parameters including the duty cycle and frequency on film compositions are discussed. The model suggests that the time to reach process equilibrium may vary substantially depending on these parameters. It is also indicated that the compositions of VOx films are quite sensitive to both the reactive gas supply and the duty cycle when the power supply works in pulse mode. The ‘steady-state’ balance values obtained by these simulations show excellent agreement with the experimental data, which indicates that the experimentally obtained dynamic behavior of the film composition can be explained by this time-dependent modeling for pulsed DC reactive sputtering process. Moreover, the computer simulation results indicate that the curves will essentially yield oscillations around the average value of the film compositions with lower pulse frequency.

  11. STATCOM-Based Wind-Solar-Hydro Electric Power System with Modified Real and Reactive Power Controls

    NASA Astrophysics Data System (ADS)

    Ram Prabhakar, J.; Ragavan, K.

    2014-01-01

    This paper presents a control of distributed generation (DG) system subjected to sudden rise in demand, faults on the distribution feeder and unbalanced load condition. The effects of line to ground faults on the system are investigated and control measures are taken to stabilize the generator speed and to improve voltage quality at the point of common coupling (PCC). The static shunt compensator (STATCOM) is connected at PCC to provide voltage support during sudden demand rise and fault on feeder. Moreover, the STATCOM control is devised such that even during unbalanced load condition the converter current and hydro-turbine-driven induction generator current is balanced. Owing to this, the double power frequency oscillations in the dc-link voltage and torque pulsations in generator can be averted. The STATCOM also supplies reactive power to the load. In addition to this, generation-demand mismatch is moderated using real and reactive power controllers. To demonstrate the performance of the DG system with the said control approach, model of system is simulated in Matlab-Simulink environment and the results are presented.

  12. Proactive and Reactive Transmission Power Control for Energy-Efficient On-Body Communications

    PubMed Central

    Vallejo, Mónica; Recas, Joaquín.; Ayala, José L.

    2015-01-01

    In wireless body sensor network (WBSNs), the human body has an important effect on the performance of the communication due to the temporal variations caused and the attenuation and fluctuation of the path loss. This fact suggests that the transmission power must adapt to the current state of the link in a way that it ensures a balance between energy consumption and packet loss. In this paper, we validate our two transmission power level policies (reactive and predictive approaches) using the Castalia simulator. The integration of our experimental measurements in the simulator allows us to easily evaluate complex scenarios, avoiding the difficulties associated with a practical realization. Our results show that both schemes perform satisfactorily, providing overall energy savings of 24% and 22% for a case of study, as compared to the maximum transmission power mode. PMID:25769049

  13. Proactive and reactive transmission power control for energy-efficient on-body communications.

    PubMed

    Vallejo, Mónica; Recas, Joaquín; Ayala, José L

    2015-01-01

    In wireless body sensor network (WBSNs), the human body has an important effect on the performance of the communication due to the temporal variations caused and the attenuation and fluctuation of the path loss. This fact suggests that the transmission power must adapt to the current state of the link in a way that it ensures a balance between energy consumption and packet loss. In this paper, we validate our two transmission power level policies (reactive and predictive approaches) using the Castalia simulator. The integration of our experimental measurements in the simulator allows us to easily evaluate complex scenarios, avoiding the difficulties associated with a practical realization. Our results show that both schemes perform satisfactorily, providing overall energy savings of 24% and 22% for a case of study, as compared to the maximum transmission power mode. PMID:25769049

  14. Voltage and Reactive Power Control by Parallel Calculation Management using Multi-Point TS and CGA

    NASA Astrophysics Data System (ADS)

    Aoki, Hidenori; Michihata, Masashi; Mizutani, Yoshibumi; Hoshino, Hiroshi

    This paper presents a new approach to optimal voltage and reactive power control based on a genetic algorithm (GA) and a tabu search (TS). To reduce time to calculate the control procedure, the parallel computation using Linux is executed. In order to obtain more effective and optimum parallel computation, the characteristic of the parallel processing algorithm used in the proposed method is to effectively utilize the Master operation of ordinary GA parallel processing. In other words, using the waiting time for transmission from the Slave to execute TS as Master. The effectiveness of the proposed method is demonstrated by practical 118-bus system.

  15. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  16. Evaluation of the Portable Instantaneous Display Analysis Spectrometer (PIDAS)

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.; Rubin, Tod; Ohashi, Makoto

    1988-01-01

    The Portable Instantaneous Display Analysis System (PIDAS) was evaluated by measuring 125 spectra of mineral specimens and rock samples under the following conditions: in the laboratory under artificial illumination and outdoors, on the building patio, while still using the line voltage electric power supplies. The PIDAS was compared and contrasted with the GEOSCAN PFS, Daedalus-Spectrafax 440, and the Geophysical Environmental Research (GER) IRIS Mark 4.

  17. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  18. Testing of an Integrated Reactor Core Simulator and Power Conversion System with Simulated Reactivity Feedback

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Hervol, David S.; Godfroy, Thomas J.

    2010-01-01

    A Direct Drive Gas-Cooled (DDG) reactor core simulator has been coupled to a Brayton Power Conversion Unit (BPCU) for integrated system testing at NASA Glenn Research Center (GRC) in Cleveland, Ohio. This is a closed-cycle system that incorporates an electrically heated reactor core module, turboalternator, recuperator, and gas cooler. Nuclear fuel elements in the gas-cooled reactor design are replaced with electric resistance heaters to simulate the heat from nuclear fuel in the corresponding fast spectrum nuclear reactor. The thermodynamic transient behavior of the integrated system was the focus of this test series. In order to better mimic the integrated response of the nuclear-fueled system, a simulated reactivity feedback control loop was implemented. Core power was controlled by a point kinetics model in which the reactivity feedback was based on core temperature measurements; the neutron generation time and the temperature feedback coefficient are provided as model inputs. These dynamic system response tests demonstrate the overall capability of a non-nuclear test facility in assessing system integration issues and characterizing integrated system response times and response characteristics.

  19. Testing of an Integrated Reactor Core Simulator and Power Conversion System with Simulated Reactivity Feedback

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Hervol, David S.; Godfroy, Thomas J.

    2009-01-01

    A Direct Drive Gas-Cooled (DDG) reactor core simulator has been coupled to a Brayton Power Conversion Unit (BPCU) for integrated system testing at NASA Glenn Research Center (GRC) in Cleveland, OH. This is a closed-cycle system that incorporates an electrically heated reactor core module, turbo alternator, recuperator, and gas cooler. Nuclear fuel elements in the gas-cooled reactor design are replaced with electric resistance heaters to simulate the heat from nuclear fuel in the corresponding fast spectrum nuclear reactor. The thermodynamic transient behavior of the integrated system was the focus of this test series. In order to better mimic the integrated response of the nuclear-fueled system, a simulated reactivity feedback control loop was implemented. Core power was controlled by a point kinetics model in which the reactivity feedback was based on core temperature measurements; the neutron generation time and the temperature feedback coefficient are provided as model inputs. These dynamic system response tests demonstrate the overall capability of a non-nuclear test facility in assessing system integration issues and characterizing integrated system response times and response characteristics.

  20. Effects of V2G Reactive Power Compensation on the Component Selection in an EV or PHEV Bidirectional Charger

    SciTech Connect

    Kisacikoglu, Mithat C; Ozpineci, Burak; Tolbert, Leon M

    2010-01-01

    Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) are becoming a part of the electric grid day by day. Chargers for these vehicles have the ability to make this interaction better for the consumer and for the grid. Vehicle to grid (V2G) power transfer has been under research for more than a decade because of the large energy reserve of an electric vehicle battery and the potential of thousands of these connected to the grid. Rather than discharging the vehicle batteries, reactive power compensation in particular is beneficial for both consumers and for the utility. However, certain adverse effects or requirements of reactive power transfer should be defined before a design stage. To understand the dynamics of this operation, this study investigates the effect of reactive power transfer on the charger system components, especially on the dc-link capacitor and the battery.

  1. Estimation of reactive power export and import capability for non-utility generators

    SciTech Connect

    Nolan, G.J.; Winge, D.E.; Khalafalla, E.B.; Swartley, B.S.; Arnold, E.H.

    1995-12-31

    Non-utility generators (NUGs) are typically required by their electric power sales agreement to have the capability to supply power to the purchasing utility near unity power factor. With the advent of large combustion turbine generators, many NUGs are simple or combined cycle facilities with generating capacities in excess of low megawatts. Utilities are recognizing that these large NUG facilities can be significant contributors to the reactive power (megavars-Mvars) flow needed to support system requirements and transmission level grid voltages. NUGs are now being dispatched for Mvar export and import activities to meet utility requirements. The ability of a NUG to export or import Mvars is highly dependent on the actual transmission intertie voltage level. Unless plant specific studies are performed, this can be difficult to ascertain for the NUG`s operating and engineering personnel. This paper presents a method, based on system load flow studies, for estimating the capacity of a NUG to export or import Mvars at a given transmission intertie voltage level. It also explores other key variables which determine the ability of a NUG to export or import VARS. This methodology can be used to aid operating personnel at existing facilities or as a guide during the design of a new facility.

  2. Application of fuzzy sets to optimal reactive power planning with security constraints

    SciTech Connect

    Abdul-Rahman, K.H.; Shahidehpour, S.M. . Dept. of Electrical and Computer Engineering)

    1994-05-01

    This paper presents a mathematical formulation for the optimal reactive power planning taking into account the static security constraints and the non-probabilistic uncertainty in load values. The planning process is decomposed into investment and operation problems via the generalized Benders decomposition (GBD). Fixed and variable costs are considered in the investment problem. Linguistic declarations of load values in the operation problem are translated into possibility distribution functions. The operation problem is decomposed into 4 subproblems via Dantzig-Wolfe decomposition (DWD), and the modeling of multi-area power systems is considered by applying a second DWD to each subproblem, leading to a significant reduction in its dimensions for personal computer applications. Voltage constraints within each area are modeled as fuzzy sets for the static security analysis by biasing the final solution towards desired values of variables within their given ranges. The overall solution is a compromise between economics (lower investment and operation costs) and security (tighter feasible region). Numerical examples for the applicability of the proposed approach to multi-area power systems are discussed.

  3. Reactive-power compensation of coal mining excavators by using a new-generation STATCOM

    SciTech Connect

    Bilgin, H.F.; Ermis, M.; Kose, K.N.; Cadirci, I.; Acik, A.; Demirci, T.; Terciyanli, A.; Kocak, C.; Yorukoglu, M.

    2007-01-15

    This paper deals with the development and implementation of a current-source-converter-based static synchronous compensator (CSC-STATCOM) applied to the volt-ampere-reactive (VAR) compensation problem of coal mining excavators. It is composed of a +/- 750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a Delta/Y-connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyristor (IGCT) connected in series with a reverse-blocking diode and switched at 500 Hz to eliminate 5th, 7th, 11th, and 13th current harmonics produced by the CSC. Operating principles, power stage, design of dc link, and input filter are also described in this paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAR consumption of electric excavators, resulting in nearly unity power factor on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with the IEEE Standard 519-1992.

  4. Voltage and Reactive Power Control by Integrating Genetic Algorithm and Tabu Search Considering Control Process

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kensei; Aoki, Hidenori; Naoi, Kenji; Mizutani, Yoshibumi

    This paper presents the result of executing the conventional genetic algorithm (GA) and a new method to the voltage and reactive power control (VQC). The conventional GA can give the control process and improve the fitness with the practical control times. And, the method to cancel the limited deviation as early as possible is implemented. Moreover, the method to reduce the control times to the fitness as much as possible is proposed. The proposed method is integrated the tabu search (TS) into the conventional GA. The proposed method generates next generation’s individual with the crossover of the conventional GA and the neighborhood search of the TS. Therefore, the proposed method executes an effective search. As a result, the proposed method can obtain better fitness than the conventional GA in the same calculation times. The effectiveness of the proposed method is demonstrated by practical 15-bus and 118-bus systems.

  5. Thermal analysis of a reactive generalized Couette flow of power law fluids between concentric cylindrical pipes

    NASA Astrophysics Data System (ADS)

    Makinde, O. D.

    2014-12-01

    In this paper, the steady generalized axial Couette flow of Ostwald-de Waele power law reactive fluids between concentric cylindrical pipes is investigated. It is assumed that the outer cylinder is stationary and exchanges heat with the ambient surrounding following Newton's law of cooling, while the inner cylinder with isothermal surface is set in motion in the axial direction. The model nonlinear differential equations for the momentum and energy balance are obtained and tackled numerically using the shooting method coupled with the Runge-Kutta-Fehlberg integration technique. The effects of various embedded thermophysical parameters on the velocity and temperature fields including skin friction, Nusselt number and thermal criticality conditions are presented graphically and discussed quantitatively.

  6. New Enhanced Artificial Bee Colony (JA-ABC5) Algorithm with Application for Reactive Power Optimization

    PubMed Central

    2015-01-01

    The standard artificial bee colony (ABC) algorithm involves exploration and exploitation processes which need to be balanced for enhanced performance. This paper proposes a new modified ABC algorithm named JA-ABC5 to enhance convergence speed and improve the ability to reach the global optimum by balancing exploration and exploitation processes. New stages have been proposed at the earlier stages of the algorithm to increase the exploitation process. Besides that, modified mutation equations have also been introduced in the employed and onlooker-bees phases to balance the two processes. The performance of JA-ABC5 has been analyzed on 27 commonly used benchmark functions and tested to optimize the reactive power optimization problem. The performance results have clearly shown that the newly proposed algorithm has outperformed other compared algorithms in terms of convergence speed and global optimum achievement. PMID:25879054

  7. Deposition of highly textured AlN thin films by reactive high power impulse magnetron sputtering

    SciTech Connect

    Moreira, Milena A.; Törndahl, Tobias; Katardjiev, Ilia; Kubart, Tomas

    2015-03-15

    Aluminum nitride thin films were deposited by reactive high power impulse magnetron sputtering (HiPIMS) and pulsed direct-current on Si (100) and textured Mo substrates, where the same deposition conditions were used for both techniques. The films were characterized by x-ray diffraction and atomic force microscopy. The results show a pronounced improvement in the AlN crystalline texture for all films deposited by HiPIMS on Si. Already at room temperature, the HiPIMS films exhibited a strong preferred (002) orientation and at 400 °C, no contributions from other orientations were detected. Despite the low film thickness of only 200 nm, an ω-scan full width at half maximum value of 5.1° was achieved on Si. The results are attributed to the high ionization of sputtered material achieved in HiPIMS. On textured Mo, there was no significant difference between the deposition techniques.

  8. Computing Instantaneous Frequency by normalizing Hilbert Transform

    NASA Technical Reports Server (NTRS)

    Huang, Norden E. (Inventor)

    2005-01-01

    This invention presents Normalized Amplitude Hilbert Transform (NAHT) and Normalized Hilbert Transform(NHT), both of which are new methods for computing Instantaneous Frequency. This method is designed specifically to circumvent the limitation set by the Bedorsian and Nuttal Theorems, and to provide a sharp local measure of error when the quadrature and the Hilbert Transform do not agree. Motivation for this method is that straightforward application of the Hilbert Transform followed by taking the derivative of the phase-angle as the Instantaneous Frequency (IF) leads to a common mistake made up to this date. In order to make the Hilbert Transform method work, the data has to obey certain restrictions.

  9. Computing Instantaneous Frequency by normalizing Hilbert Transform

    DOEpatents

    Huang, Norden E.

    2005-05-31

    This invention presents Normalized Amplitude Hilbert Transform (NAHT) and Normalized Hilbert Transform(NHT), both of which are new methods for computing Instantaneous Frequency. This method is designed specifically to circumvent the limitation set by the Bedorsian and Nuttal Theorems, and to provide a sharp local measure of error when the quadrature and the Hilbert Transform do not agree. Motivation for this method is that straightforward application of the Hilbert Transform followed by taking the derivative of the phase-angle as the Instantaneous Frequency (IF) leads to a common mistake made up to this date. In order to make the Hilbert Transform method work, the data has to obey certain restrictions.

  10. Heterodyne laser instantaneous frequency measurement system

    DOEpatents

    Wyeth, Richard W.; Johnson, Michael A.; Globig, Michael A.

    1990-01-01

    A heterodyne laser instantaneous frequency measurement system is disclosed. The system utilizes heterodyning of a pulsed laser beam with a continuous wave laser beam to form a beat signal. The beat signal is processed by a controller or computer which determines both the average frequency of the laser pulse and any changes or chirp of the frequency during the pulse.

  11. Heterodyne laser instantaneous frequency measurement system

    DOEpatents

    Wyeth, Richard W.; Johnson, Michael A.; Globig, Michael A.

    1989-01-01

    A heterodyne laser instantaneous frequency measurement system is disclosed. The system utilizes heterodyning of a pulsed laser beam with a continuous wave laser beam to form a beat signal. The beat signal is processed by a controller or computer which determines both the average frequency of the laser pulse and any changes or chirp of th frequency during the pulse.

  12. Current-voltage-time characteristics of the reactive Ar/N{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Magnus, F.; Sveinsson, O. B.; Olafsson, S.; Gudmundsson, J. T.

    2011-10-15

    The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N{sub 2} discharge with a Ti target for 400 {mu}s long pulses. We observe that the current waveform in the reactive Ar/N{sub 2} HiPIMS discharge is highly dependent on the pulse repetition frequency, unlike the non-reactive Ar discharge. The current is found to increase significantly as the frequency is lowered. This is attributed to an increase in the secondary electron emission yield during the self-sputtering phase, when the nitride forms on the target at low frequencies. In addition, self-sputtering runaway occurs at lower discharge voltages when nitrogen is added to the discharge. This illustrates the crucial role of self-sputtering in the behavior of the reactive HiPIMS discharge.

  13. An error bound for instantaneous coverage

    NASA Technical Reports Server (NTRS)

    White, Allan L.

    1991-01-01

    An error bound is derived for a reliability model approximation method. The approximation method is appropriate for the semi-Markov models of reconfigurable systems that are designed to achieve extremely high reliability. The semi-Markov models of these system are complex, and a significant amount of their complexity arises from the detailed descriptions of the reconfiguration processes. The reliability model approximation method consists of replacing a detailed description of a reconfiguration process with the probabilities of the possible outcomes of the reconfiguration process. These probabilities are included in the model as instantaneous jumps from the fault-occurrence state. Since little time is spent in the reconfiguration states, instantaneous jumps are a close approximation to the original model. This approximation procedure is shown to produce an overestimation for the probability of system failure, and an error bound is derived for this overestimation.

  14. Quantifying instantaneous performance in alpine ski racing.

    PubMed

    Federolf, Peter Andreas

    2012-01-01

    Alpine ski racing is a popular sport in many countries and a lot of research has gone into optimising athlete performance. Two factors influence athlete performance in a ski race: speed and the chosen path between the gates. However, to date there is no objective, quantitative method to determine instantaneous skiing performance that takes both of these factors into account. The purpose of this short communication was to define a variable quantifying instantaneous skiing performance and to study how this variable depended on the skiers' speed and on their chosen path. Instantaneous skiing performance was defined as time loss per elevation difference dt/dz, which depends on the skier's speed v(z), and the distance travelled per elevation difference ds/dz. Using kinematic data collected in an earlier study, it was evaluated how these variables can be used to assess the individual performance of six ski racers in two slalom turns. The performance analysis conducted in this study might be a useful tool not only for athletes and coaches preparing for competition, but also for sports scientists investigating skiing techniques or engineers developing and testing skiing equipment. PMID:22620279

  15. Multi-Objective Advanced Inverter Controls to Dispatch the Real and Reactive Power of Many Distributed PV Systems.

    SciTech Connect

    Reno, Matthew J.; Lave, Matthew Samuel; Broderick, Robert Joseph; Seuss, John; Grijalva, Santiago

    2016-01-01

    The research presented in this report compares several real - time control strategies for the power output of a large number of PV distributed throughout a large distribution feeder circuit. Both real and reactive power controls are considered with the goal of minimizing network over - voltage violations caused by large amounts of PV generation. Several control strategies are considered under various assumptions regarding the existence and latency of a communication network. The control parameters are adjusted to maximize the effectiveness of each control. The controls are then compared based on their ability to achieve multiple objectiv es. These objectives include minimizing the total number of voltage violations , minimizing the total amount of PV energy curtailed or reactive power generated, and maximizing the fairness of any control action among all PV systems . The controls are simulat ed on the OpenDSS platform using time series load and spatially - distributed irradiance data.

  16. Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Villamayor, M.; Lundin, D.; Helmersson, U.

    2016-02-01

    A simple and cost effective approach to stabilize the sputtering process in the transition zone during reactive high-power impulse magnetron sputtering (HiPIMS) is proposed. The method is based on real-time monitoring and control of the discharge current waveforms. To stabilize the process conditions at a given set point, a feedback control system was implemented that automatically regulates the pulse frequency, and thereby the average sputtering power, to maintain a constant maximum discharge current. In the present study, the variation of the pulse current waveforms over a wide range of reactive gas flows and pulse frequencies during a reactive HiPIMS process of Hf-N in an Ar-N2 atmosphere illustrates that the discharge current waveform is a an excellent indicator of the process conditions. Activating the reactive HiPIMS peak current regulation, stable process conditions were maintained when varying the N2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse frequency from 600 Hz to 1150 Hz and consequently an increase of the average power from 110 to 270 W. Hf-N films deposited using peak current regulation exhibited a stable stoichiometry, a nearly constant power-normalized deposition rate, and a polycrystalline cubic phase Hf-N with (1 1 1)-preferred orientation over the entire reactive gas flow range investigated. The physical reasons for the change in the current pulse waveform for different process conditions are discussed in some detail.

  17. Characterization of combined power plasma jet using AC high voltage and nanosecond pulse for reactive species composition control

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Konishi, Hideaki; Kato, Toshiaki; Kaneko, Toshiro

    2014-10-01

    In the application studies for both bio-medical and agricultural applications, the roles of the reactive oxide and/or nitride species generated in the plasma has been reported as a key to control the effects and ill-effects on the living organism. The correlation between total OH radical exposure from an air atmospheric pressure plasma jet and the sterilization threshold on Botrytis cinerea is presented. With the increase of the OH radical exposure to the Botrytis cinerea, the probability of sterilization is increased. In this study, to resolve the roles of reactive species including OH radicals, a combined power plasma jet using nanosecond pulses and low-frequency sinusoidal AC high voltage (a few kHz) is studied for controlling the composition of the reactive species. The nanosecond pulses are superimposed on the AC voltage which is in synchronization with the AC phase. The undergoing work to characterize the combined power discharge with electric charge and voltage cycle on the plasma jet will also be presented to discuss the discharge characteristics to control the composition of the reactive species.

  18. An improved instantaneous laser Doppler velocity system

    NASA Astrophysics Data System (ADS)

    Desio, Charles V.; Olcmen, Semih; Schinetsky, Philip

    2016-02-01

    In this paper, improvements made on a single velocity component instantaneous laser Doppler velocimetry (ILDV) system are detailed. The ILDV system developed in this research effort is capable of measuring a single velocity component at a rate as high as two megahertz. The current system accounts for the effects of the laser intensity variation on the measured velocity and eliminates the use of a Pockels cell used in previous ILDV systems. The system developed in the current effort was tested using compressible, subsonic jet flows. The ILDV system developed would be most beneficial where a high data capture rate is needed such as in shock tubes, and high-speed wind tunnels.

  19. The instantaneous light-intensity function of a fluorescent lamp

    NASA Astrophysics Data System (ADS)

    Gluskin, Emanuel; Topalis, Frangiskos V.; Kateri, Ifigenia; Bisketzis, Nikolas

    2006-05-01

    Using some simple physics and “system” considerations, the instantaneous light intensity function ψ(t) of a fluorescent lamp fed via a regular ballast from the 50 60 Hz line is argued to be ψ(t)=ψ+bp(t), where p(t) is the instantaneous power function of the lamp, and b is a constant, and experiment confirms this formula well. The main frequency of ψ(t), the very significant singularity of its waveform, and the relative intensity of the ripple, i.e., the depth of the modulation, are the focus. The results are important for research into the vision problem that some humans (autistic, but others, too) experience regarding fluorescent light. The inertia of the processes in the lamp which are responsible for the light emission, provides some nonzero emission at the instants when p(t) has zeros. The smaller the volume of the tube and the mass of the gas are, the more weakly the inertia of the processes is expressed, and the relatively smaller is ψ. However, it should be very difficult to theoretically obtain ψ(t), in particular ψ, from the very complicated physics of the low-pressure discharge in the tube. We conclude that ψ has to be connected with the (also easily measured) lamp's inductance. The work should attract more attention of the physicists to the properties of the common fluorescent lamps.

  20. Compatibility of Space Nuclear Power Plant Materials in an Inert He/Xe Working Gas Containing Reactive Impurities

    SciTech Connect

    MM Hall

    2006-01-31

    A major materials selection and qualification issue identified in the Space Materials Plan is the potential for creating materials compatibility problems by combining dissimilar reactor core, Brayton Unit and other power conversion plant materials in a recirculating, inert He/Xe gas loop containing reactive impurity gases. Reported here are results of equilibrium thermochemical analyses that address the compatibility of space nuclear power plant (SNPP) materials in high temperature impure He gas environments. These studies provide early information regarding the constraints that exist for SNPP materials selection and provide guidance for establishing test objectives and environments for SNPP materials qualification testing.

  1. Voltage control for a wind power plant based on the available reactive current of a DFIG and its impacts on the point of interconnection

    DOE PAGESBeta

    Usman, Yasir; Kim, Jinho; Muljadi, Eduard; Kang, Yong Cheol

    2016-01-01

    Wake effects cause wind turbine generators (WTGs) within a wind power plant (WPP) to produce different levels of active power and subsequent reactive power capabilities. Further, the impedance between a WTG and the point of interconnection (POI)-which depends on the distance between them-impacts the WPP's reactive power injection capability at the POI. This paper proposes a voltage control scheme for a WPP based on the available reactive current of the doubly-fed induction generators (DFIGs) and its impacts on the POI to improve the reactive power injection capability of the WPP. In this paper, a design strategy for modifying the gainmore » of DFIG controller is suggested and the comprehensive properties of these control gains are investigated. In the proposed scheme, the WPP controller, which operates in a voltage control mode, sends the command signal to the DFIGs based on the voltage difference at the POI. The DFIG controllers, which operate in a voltage control mode, employ a proportional controller with a limiter. The gain of the proportional controller is adjusted depending on the available reactive current of the DFIG and the series impedance between the DFIG and the POI. The performance of the proposed scheme is validated for various disturbances such as a reactive load connection and grid fault using an EMTP-RV simulator. Furthermore, simulation results demonstrate that the proposed scheme promptly recovers the POI voltage by injecting more reactive power after a disturbance than the conventional scheme.« less

  2. Voltage control for a wind power plant based on the available reactive current of a DFIG and its impacts on the point of interconnection

    SciTech Connect

    Usman, Yasir; Kim, Jinho; Muljadi, Eduard; Kang, Yong Cheol

    2016-01-01

    Wake effects cause wind turbine generators (WTGs) within a wind power plant (WPP) to produce different levels of active power and subsequent reactive power capabilities. Further, the impedance between a WTG and the point of interconnection (POI)-which depends on the distance between them-impacts the WPP's reactive power injection capability at the POI. This paper proposes a voltage control scheme for a WPP based on the available reactive current of the doubly-fed induction generators (DFIGs) and its impacts on the POI to improve the reactive power injection capability of the WPP. In this paper, a design strategy for modifying the gain of DFIG controller is suggested and the comprehensive properties of these control gains are investigated. In the proposed scheme, the WPP controller, which operates in a voltage control mode, sends the command signal to the DFIGs based on the voltage difference at the POI. The DFIG controllers, which operate in a voltage control mode, employ a proportional controller with a limiter. The gain of the proportional controller is adjusted depending on the available reactive current of the DFIG and the series impedance between the DFIG and the POI. The performance of the proposed scheme is validated for various disturbances such as a reactive load connection and grid fault using an EMTP-RV simulator. Furthermore, simulation results demonstrate that the proposed scheme promptly recovers the POI voltage by injecting more reactive power after a disturbance than the conventional scheme.

  3. Instantaneous Slip Length in Superhydrophobic Microchannels

    NASA Astrophysics Data System (ADS)

    Hemeda, Ahmed; Tafreshi, Hooman; VCU Team

    2015-11-01

    Superhydrophobic (SHP) surfaces can be used to reduce the skin-friction drag in a microchannel. This favorable effect, however, can deteriorate over time if the surface geometry is not designed properly. This study presents a mathematical means for studying the time-dependent drag-reduction in a microchannel enhanced with SHP grooves of varying geometries. The performance of an SHP groove is found to be dependent on the interplay between the effects of the apparent contact angle of the air-water interface and the initial volume of the groove. The instantaneous slip length is calculated by solving the Navier-Stokes equations for flow in a microchannel with such SHP grooves, and the results are compared with the studies in the literature. National Science Foundation CMMI 1029924 and CBET 1402655.

  4. Numerical modelling of instantaneous plate tectonics

    NASA Technical Reports Server (NTRS)

    Minster, J. B.; Haines, E.; Jordan, T. H.; Molnar, P.

    1974-01-01

    Assuming lithospheric plates to be rigid, 68 spreading rates, 62 fracture zones trends, and 106 earthquake slip vectors are systematically inverted to obtain a self-consistent model of instantaneous relative motions for eleven major plates. The inverse problem is linearized and solved iteratively by a maximum-likelihood procedure. Because the uncertainties in the data are small, Gaussian statistics are shown to be adequate. The use of a linear theory permits (1) the calculation of the uncertainties in the various angular velocity vectors caused by uncertainties in the data, and (2) quantitative examination of the distribution of information within the data set. The existence of a self-consistent model satisfying all the data is strong justification of the rigid plate assumption. Slow movement between North and South America is shown to be resolvable.

  5. Field of Attention for Instantaneous Object Recognition

    PubMed Central

    Yao, Jian-Gao; Gao, Xin; Yan, Hong-Mei; Li, Chao-Yi

    2011-01-01

    Background Instantaneous object discrimination and categorization are fundamental cognitive capacities performed with the guidance of visual attention. Visual attention enables selection of a salient object within a limited area of the visual field; we referred to as “field of attention” (FA). Though there is some evidence concerning the spatial extent of object recognition, the following questions still remain unknown: (a) how large is the FA for rapid object categorization, (b) how accuracy of attention is distributed over the FA, and (c) how fast complex objects can be categorized when presented against backgrounds formed by natural scenes. Methodology/Principal Findings To answer these questions, we used a visual perceptual task in which subjects were asked to focus their attention on a point while being required to categorize briefly flashed (20 ms) photographs of natural scenes by indicating whether or not these contained an animal. By measuring the accuracy of categorization at different eccentricities from the fixation point, we were able to determine the spatial extent and the distribution of accuracy over the FA, as well as the speed of categorizing objects using stimulus onset asynchrony (SOA). Our results revealed that subjects are able to rapidly categorize complex natural images within about 0.1 s without eye movement, and showed that the FA for instantaneous image categorization covers a visual field extending 20°×24°, and accuracy was highest (>90%) at the center of FA and declined with increasing eccentricity. Conclusions/Significance In conclusion, human beings are able to categorize complex natural images at a glance over a large extent of the visual field without eye movement. PMID:21283690

  6. Observation of a periodic runaway in the reactive Ar/O{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Shayestehaminzadeh, Seyedmohammad E-mail: shayesteh@mch.rwth-aachen.de; Arnalds, Unnar B.; Magnusson, Rögnvaldur L.; Olafsson, Sveinn

    2015-11-15

    This paper reports the observation of a periodic runaway of plasma to a higher density for the reactive discharge of the target material (Ti) with moderate sputter yield. Variable emission of secondary electrons, for the alternating transition of the target from metal mode to oxide mode, is understood to be the main reason for the runaway occurring periodically. Increasing the pulsing frequency can bring the target back to a metal (or suboxide) mode, and eliminate the periodic transition of the target. Therefore, a pulsing frequency interval is defined for the reactive Ar/O{sub 2} discharge in order to sustain the plasma in a runaway-free mode without exceeding the maximum power that the magnetron can tolerate.

  7. "Body-In-The-Loop": Optimizing Device Parameters Using Measures of Instantaneous Energetic Cost

    PubMed Central

    Felt, Wyatt; Selinger, Jessica C.; Donelan, J. Maxwell; Remy, C. David

    2015-01-01

    This paper demonstrates methods for the online optimization of assistive robotic devices such as powered prostheses, orthoses and exoskeletons. Our algorithms estimate the value of a physiological objective in real-time (with a body “in-the-loop”) and use this information to identify optimal device parameters. To handle sensor data that are noisy and dynamically delayed, we rely on a combination of dynamic estimation and response surface identification. We evaluated three algorithms (Steady-State Cost Mapping, Instantaneous Cost Mapping, and Instantaneous Cost Gradient Search) with eight healthy human subjects. Steady-State Cost Mapping is an established technique that fits a cubic polynomial to averages of steady-state measures at different parameter settings. The optimal parameter value is determined from the polynomial fit. Using a continuous sweep over a range of parameters and taking into account measurement dynamics, Instantaneous Cost Mapping identifies a cubic polynomial more quickly. Instantaneous Cost Gradient Search uses a similar technique to iteratively approach the optimal parameter value using estimates of the local gradient. To evaluate these methods in a simple and repeatable way, we prescribed step frequency via a metronome and optimized this frequency to minimize metabolic energetic cost. This use of step frequency allows a comparison of our results to established techniques and enables others to replicate our methods. Our results show that all three methods achieve similar accuracy in estimating optimal step frequency. For all methods, the average error between the predicted minima and the subjects’ preferred step frequencies was less than 1% with a standard deviation between 4% and 5%. Using Instantaneous Cost Mapping, we were able to reduce subject walking-time from over an hour to less than 10 minutes. While, for a single parameter, the Instantaneous Cost Gradient Search is not much faster than Steady-State Cost Mapping, the

  8. Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films

    SciTech Connect

    Schmidt, Susann; Czigany, Zsolt; Greczynski, Grzegorz; Jensen, Jens; Hultman, Lars

    2013-01-15

    The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CN{sub x}) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N{sub 2} was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CN{sub x} thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CN{sub x} films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CN{sub x} thin films.

  9. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  10. Effects of anodic potential and chloride ion on overall reactivity in electrochemical reactors designed for solar-powered wastewater treatment.

    PubMed

    Cho, Kangwoo; Qu, Yan; Kwon, Daejung; Zhang, Hao; Cid, Clément A; Aryanfar, Asghar; Hoffmann, Michael R

    2014-02-18

    We have investigated electrochemical treatment of real domestic wastewater coupled with simultaneous production of molecular H2 as useful byproduct. The electrolysis cells employ multilayer semiconductor anodes with electroactive bismuth-doped TiO2 functionalities and stainless steel cathodes. DC-powered laboratory-scale electrolysis experiments were performed under static anodic potentials (+2.2 or +3.0 V NHE) using domestic wastewater samples, with added chloride ion in variable concentrations. Greater than 95% reductions in chemical oxygen demand (COD) and ammonium ion were achieved within 6 h. In addition, we experimentally determined a decreasing overall reactivity of reactive chlorine species toward COD with an increasing chloride ion concentration under chlorine radicals (Cl·, Cl2(-)·) generation at +3.0 V NHE. The current efficiency for COD removal was 12% with the lowest specific energy consumption of 96 kWh kgCOD(-1) at the cell voltage of near 4 V in 50 mM chloride. The current efficiency and energy efficiency for H2 generation were calculated to range from 34 to 84% and 14 to 26%, respectively. The hydrogen comprised 35 to 60% by volume of evolved gases. The efficacy of our electrolysis cell was further demonstrated by a 20 L prototype reactor totally powered by a photovoltaic (PV) panel, which was shown to eliminate COD and total coliform bacteria in less than 4 h of treatment. PMID:24417418

  11. Observing and recording instantaneous images on ATM television monitors

    NASA Technical Reports Server (NTRS)

    Patterson, N. P.; Delamere, W. A.; Tousey, R.

    1977-01-01

    A persistent image-converter device was utilized to make visible to the astronaut solar images that were isolated, instantaneous flashes on the ATM TV monitors. In addition, these instantaneous images, as well as normal TV images, were recorded with a Polaroid SX-70 camera for study by the astronauts.

  12. K 4R - Knowledge to the Power of RESTful, Resourceful and Reactive Rules

    NASA Astrophysics Data System (ADS)

    Amador, Ricardo

    The Web of today clearly answers questions of the form "What is the representation of ...?". The Semantic Web (SW) of tomorrow aims at answering questions of the form "What is the meaning of ...?". It is our stance that in order to realize the full potential of the original concept proposed by Tim Berners-Lee et al. (in Scientific American, May 2001), the SW must also answer, in a meaningful way, questions of a dynamic and active nature, like "What to do if ...?" or "What to do when ...?". Moreover, SW questions of the form "What to do ...?" must be expressed and answered in a declarative, compositional and language agnostic way. It is our (hypo)thesis that formally established concepts, viz. the Web's REST architectural style, declarative SW representation of resources based on Description Logics (e.g., OWL-DL), and Reactive Rules (e.g., "on Event if Condition do Action" -ECA- rules), provide the proper theoretical foundations to achieve this goal. This paper describes our current research proposal, K 4R (pronounced, with an Italian flavor, "Che fare?"), towards achieving a declarative model for expressing (re)active behavior in and for the SW.

  13. Three-dimensional Reluctance Network Analysis of an EIE-Core Variable Inductor and Application to Reactive Power Compensation in a Distribution System

    NASA Astrophysics Data System (ADS)

    Nakamura, Kenji; Ohinata, Takashi; Arimatsu, Kenji; Sakamoto, Kunio; Ichinokura, Osamu

    This paper describes a three-dimensional reluctance network analysis (RNA) of an EIE-core variable inductor, which can be applied as a reactive power compensator in electric power systems. First, a three-dimensional RNA model of an EIE-core considering the magnetic saturation and iron loss is presented. Using the proposed RNA model with external electric circuits, operating characteristics of the variable inductor including the iron loss are calculated accurately. Next, high performance of a 6.6 kV-300 kVA reactive power compensator using the EIE-core variable inductor is demonstrated in a distribution system.

  14. Computation and Experiment: A Powerful Combination to Understand and Predict Reactivities.

    PubMed

    Sperger, Theresa; Sanhueza, Italo A; Schoenebeck, Franziska

    2016-06-21

    Computational chemistry has become an established tool for the study of the origins of chemical phenomena and examination of molecular properties. Because of major advances in theory, hardware and software, calculations of molecular processes can nowadays be done with reasonable accuracy on a time-scale that is competitive or even faster than experiments. This overview will highlight broad applications of computational chemistry in the study of organic and organometallic reactivities, including catalytic (NHC-, Cu-, Pd-, Ni-catalyzed) and noncatalytic examples of relevance to organic synthesis. The selected examples showcase the ability of computational chemistry to rationalize and also predict reactivities of broad significance. A particular emphasis is placed on the synergistic interplay of computations and experiments. It is discussed how this approach allows one to (i) gain greater insight than the isolated techniques, (ii) inspire novel chemistry avenues, and (iii) assist in reaction development. Examples of successful rationalizations of reactivities are discussed, including the elucidation of mechanistic features (radical versus polar) and origins of stereoselectivity in NHC-catalyzed reactions as well as the rationalization of ligand effects on ligation states and selectivity in Pd- and Ni-catalyzed transformations. Beyond explaining, the synergistic interplay of computation and experiments is then discussed, showcasing the identification of the likely catalytically active species as a function of ligand, additive, and solvent in Pd-catalyzed cross-coupling reactions. These may vary between mono- or bisphosphine-bound or even anionic Pd complexes in polar media in the presence of coordinating additives. These fundamental studies also inspired avenues in catalysis via dinuclear Pd(I) cycles. Detailed mechanistic studies supporting the direct reactivity of Pd(I)-Pd(I) with aryl halides as well as applications of air-stable dinuclear Pd(I) catalysts are

  15. Covert Waking Brain Activity Reveals Instantaneous Sleep Depth

    PubMed Central

    McKinney, Scott M.; Dang-Vu, Thien Thanh; Buxton, Orfeu M.; Solet, Jo M.; Ellenbogen, Jeffrey M.

    2011-01-01

    The neural correlates of the wake-sleep continuum remain incompletely understood, limiting the development of adaptive drug delivery systems for promoting sleep maintenance. The most useful measure for resolving early positions along this continuum is the alpha oscillation, an 8–13 Hz electroencephalographic rhythm prominent over posterior scalp locations. The brain activation signature of wakefulness, alpha expression discloses immediate levels of alertness and dissipates in concert with fading awareness as sleep begins. This brain activity pattern, however, is largely ignored once sleep begins. Here we show that the intensity of spectral power in the alpha band actually continues to disclose instantaneous responsiveness to noise—a measure of sleep depth—throughout a night of sleep. By systematically challenging sleep with realistic and varied acoustic disruption, we found that sleepers exhibited markedly greater sensitivity to sounds during moments of elevated alpha expression. This result demonstrates that alpha power is not a binary marker of the transition between sleep and wakefulness, but carries rich information about immediate sleep stability. Further, it shows that an empirical and ecologically relevant form of sleep depth is revealed in real-time by EEG spectral content in the alpha band, a measure that affords prediction on the order of minutes. This signal, which transcends the boundaries of classical sleep stages, could potentially be used for real-time feedback to novel, adaptive drug delivery systems for inducing sleep. PMID:21408616

  16. Effects of Instantaneous Multiband Dynamic Compression on Speech Intelligibility

    NASA Astrophysics Data System (ADS)

    Herzke, Tobias; Hohmann, Volker

    2005-12-01

    The recruitment phenomenon, that is, the reduced dynamic range between threshold and uncomfortable level, is attributed to the loss of instantaneous dynamic compression on the basilar membrane. Despite this, hearing aids commonly use slow-acting dynamic compression for its compensation, because this was found to be the most successful strategy in terms of speech quality and intelligibility rehabilitation. Former attempts to use fast-acting compression gave ambiguous results, raising the question as to whether auditory-based recruitment compensation by instantaneous compression is in principle applicable in hearing aids. This study thus investigates instantaneous multiband dynamic compression based on an auditory filterbank. Instantaneous envelope compression is performed in each frequency band of a gammatone filterbank, which provides a combination of time and frequency resolution comparable to the normal healthy cochlea. The gain characteristics used for dynamic compression are deduced from categorical loudness scaling. In speech intelligibility tests, the instantaneous dynamic compression scheme was compared against a linear amplification scheme, which used the same filterbank for frequency analysis, but employed constant gain factors that restored the sound level for medium perceived loudness in each frequency band. In subjective comparisons, five of nine subjects preferred the linear amplification scheme and would not accept the instantaneous dynamic compression in hearing aids. Four of nine subjects did not perceive any quality differences. A sentence intelligibility test in noise (Oldenburg sentence test) showed little to no negative effects of the instantaneous dynamic compression, compared to linear amplification. A word intelligibility test in quiet (one-syllable rhyme test) showed that the subjects benefit from the larger amplification at low levels provided by instantaneous dynamic compression. Further analysis showed that the increase in intelligibility

  17. The state of the art of the development of SMES for bridging instantaneous voltage dips in Japan

    NASA Astrophysics Data System (ADS)

    Nagaya, Shigeo; Hirano, Naoki; Katagiri, Toshio; Tamada, Tsutomu; Shikimachi, Koji; Iwatani, Yu; Saito, Fusao; Ishii, Yusuke

    2012-12-01

    Development of apparatuses for protecting industrial facilities such as semiconductor plants or information industries from instantaneous voltage dips, which requires very large output power, has been expected. A Superconducting magnetic energy storage system (SMES), one of such apparatus, consists of superconducting magnets that must withstand high voltage during operation and require high reliability. We have already development of SMES using conventional superconducting coils and done the field test of the SMES for bridging instantaneous voltage dips. After field test, the commercial SMES for instantaneous voltage dips is working there. Since field test has started, we have confirmed nearly 40 operations, and all have succeeded. In 2011, three commercial SMES units for bridging instantaneous voltage dips are operating in Japan.

  18. SiNx Coatings Deposited by Reactive High Power Impulse Magnetron Sputtering: Process Parameters Influencing the Nitrogen Content.

    PubMed

    Schmidt, Susann; Hänninen, Tuomas; Goyenola, Cecilia; Wissting, Jonas; Jensen, Jens; Hultman, Lars; Goebbels, Nico; Tobler, Markus; Högberg, Hans

    2016-08-10

    Reactive high power impulse magnetron sputtering (rHiPIMS) was used to deposit silicon nitride (SiNx) coatings for biomedical applications. The SiNx growth and plasma characterization were conducted in an industrial coater, using Si targets and N2 as reactive gas. The effects of different N2-to-Ar flow ratios between 0 and 0.3, pulse frequencies, target power settings, and substrate temperatures on the discharge and the N content of SiNx coatings were investigated. Plasma ion mass spectrometry shows high amounts of ionized isotopes during the initial part of the pulse for discharges with low N2-to-Ar flow ratios of <0.16, while signals from ionized molecules rise with the N2-to-Ar flow ratio at the pulse end and during pulse-off times. Langmuir probe measurements show electron temperatures of 2-3 eV for nonreactive discharges and 5.0-6.6 eV for discharges in transition mode. The SiNx coatings were characterized with respect to their composition, chemical bond structure, density, and mechanical properties by X-ray photoelectron spectroscopy, X-ray reflectivity, X-ray diffraction, and nanoindentation, respectively. The SiNx deposition processes and coating properties are mainly influenced by the N2-to-Ar flow ratio and thus by the N content in the SiNx films and to a lower extent by the HiPIMS frequencies and power settings as well as substrate temperatures. Increasing N2-to-Ar flow ratios lead to decreasing growth rates, while the N content, coating densities, residual stresses, and the hardness increase. These experimental findings were corroborated by density functional theory calculations of precursor species present during rHiPIMS. PMID:27414283

  19. Subwavelength structures for high power laser antireflection application on fused silica by one-step reactive ion etching

    NASA Astrophysics Data System (ADS)

    Ye, Xin; Jiang, Xiao-Dong; Huang, Jin; Sun, Lai-Xi; Geng, Feng; Yi, Zao; Zu, Xiao-Tao; Wu, Wei-Dong; Zheng, Wanguo

    2016-03-01

    In this paper we report a simple method to fabricate a novel subwavelength structure surface on fused silica substrate using one-step reactive ion etching with two-dimensional polystyrene colloidal crystals as masks. The etching process and the morphologies of the obtained structure are controlled. We show that the period of the obtained fused silica pillar-like arrays were determined by the initial polystyrene nanoparticle size. The height of pillar arrays can be adjusted by controlling the etching duration, which is proved to be of importance in tailoring the antireflection properties of subwavelength structures surface. The novel subwavelength structures surface exhibit excellent broadband antireflection properties, but the size of the pillar affects the antireflective properties in short wavelength region. We anticipate this method would offer a convenient and scalable way for inexpensive and high-efficiency high power laser field designs.

  20. Reactive Inkjet Printing of Biocompatible Enzyme Powered Silk Micro-Rockets.

    PubMed

    Gregory, David A; Zhang, Yu; Smith, Patrick J; Zhao, Xiubo; Ebbens, Stephen J

    2016-08-01

    Inkjet-printed enzyme-powered silk-based micro-rockets are able to undergo autonomous motion in a vast variety of fluidic environments including complex media such as human serum. By means of digital inkjet printing it is possible to alter the catalyst distribution simply and generate varying trajectory behavior of these micro-rockets. Made of silk scaffolds containing enzymes these micro-rockets are highly biocompatible and non-biofouling. PMID:27345008

  1. Measurement of ultrashort pulses with a non-instantaneous nonlinearity

    SciTech Connect

    DeLong, K.W.; Ladera, C.L.; Trebino, R.; Kohler, B.; Wilson, K.R.

    1995-02-01

    We show how non-instantaneous nonlinearities can be used to characterize an ultrashort pulse in an extension of the Frequency-Resolved Optical Gating technique. We demonstrate this principle using the Raman effect in fused silica.

  2. Instantaneous mental workload - Concept and potential methods for measurement

    NASA Technical Reports Server (NTRS)

    Wierwille, W. W.

    1981-01-01

    This paper provides an initial conceptual framework for instantaneous workload and describes potential methods for short-term measurement. Many existing estimation techniques can be modified for use as short-term assessment techniques. Techniques in the (1) opinion, (2) spare mental capacity, (3) primary task, and (4) physiological categories are discussed. The limitations involved in instantaneous workload, which are real and fundamental, are also described.

  3. Limiting amplifier for instantaneous frequency measuring system

    NASA Astrophysics Data System (ADS)

    Askew, R. E.

    1984-12-01

    The microwave integrated-circuit limiting amplifier (LA) described in this article was designed to provide a constant output signal level over a wide (8 to 11 GHz) frequency band while the input signal level varies over the range of -50 to 0 dBm. A salient feature of the LA is the slope of the output power versus frequency response. This slope allows the LA to function as a wide-band limiter/discriminator when a suitable detector is added to the output.

  4. A new algorithm for real-time optimal dispatch of active and reactive power generation retaining nonlinearity

    SciTech Connect

    Roy, L.; Rao, N.D.

    1983-04-01

    This paper presents a new method for optimal dispatch of real and reactive power generation which is based on cartesian coordinate formulation of economic dispatch problem and reclassification of state and control variables associated with generator buses. The voltage and power at these buses are classified as parametric and functional inequality constraints, and are handled by reduced gradient technique and penalty factor approach respectively. The advantage of this classification is the reduction in the size of the equality constraint model, leading to less storage requirement. The rectangular coordinate formulation results in an exact equality constraint model in which the coefficient matrix is real, sparse, diagonally dominant, smaller in size and need be computed and factorized once only in each gradient step. In addition, Lagragian multipliers are calculated using a new efficient procedure. A natural outcome of these features is the solution of the economic dispatch problem, faster than other methods available to date in the literature. Rapid and reliable convergence is an additional desirable characteristic of the method. Digital simulation results are presented on several IEEE test systems to illustrate the range of application of the method visa-vis the popular Dommel-Tinney (DT) procedure. It is found that the proposed method is more reliable, 3-4 times faster and requires 20-30 percent less storage compared to the DT algorithm, while being just as general. Thus, owing to its exactness, robust mathematical model and less computational requirements, the method developed in the paper is shown to be a practically feasible algorithm for on-line optimal power dispatch.

  5. Instantaneous normal modes and the protein glass transition.

    PubMed

    Schulz, Roland; Krishnan, Marimuthu; Daidone, Isabella; Smith, Jeremy C

    2009-01-01

    In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at approximately 220 K. The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition. PMID:19167298

  6. Instantaneous Normal Modes and the Protein Glass Transition

    SciTech Connect

    Schultz, Roland; Krishnan, Marimuthu; Daidone, Isabella; Smith, Jeremy C

    2009-01-01

    In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at 220 K. The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition.

  7. Popescu-Rohrlich correlations imply efficient instantaneous nonlocal quantum computation

    NASA Astrophysics Data System (ADS)

    Broadbent, Anne

    2016-08-01

    In instantaneous nonlocal quantum computation, two parties cooperate in order to perform a quantum computation on their joint inputs, while being restricted to a single round of simultaneous communication. Previous results showed that instantaneous nonlocal quantum computation is possible, at the cost of an exponential amount of prior shared entanglement (in the size of the input). Here, we show that a linear amount of entanglement suffices, (in the size of the computation), as long as the parties share nonlocal correlations as given by the Popescu-Rohrlich box. This means that communication is not required for efficient instantaneous nonlocal quantum computation. Exploiting the well-known relation to position-based cryptography, our result also implies the impossibility of secure position-based cryptography against adversaries with nonsignaling correlations. Furthermore, our construction establishes a quantum analog of the classical communication complexity collapse under nonsignaling correlations.

  8. Tracking instantaneous entropy in heartbeat dynamics through inhomogeneous point-process nonlinear models.

    PubMed

    Valenza, Gaetano; Citi, Luca; Scilingo, Enzo Pasquale; Barbieri, Riccardo

    2014-01-01

    Measures of entropy have been proved as powerful quantifiers of complex nonlinear systems, particularly when applied to stochastic series of heartbeat dynamics. Despite the remarkable achievements obtained through standard definitions of approximate and sample entropy, a time-varying definition of entropy characterizing the physiological dynamics at each moment in time is still missing. To this extent, we propose two novel measures of entropy based on the inho-mogeneous point-process theory. The RR interval series is modeled through probability density functions (pdfs) which characterize and predict the time until the next event occurs as a function of the past history. Laguerre expansions of the Wiener-Volterra autoregressive terms account for the long-term nonlinear information. As the proposed measures of entropy are instantaneously defined through such probability functions, the proposed indices are able to provide instantaneous tracking of autonomic nervous system complexity. Of note, the distance between the time-varying phase-space vectors is calculated through the Kolmogorov-Smirnov distance of two pdfs. Experimental results, obtained from the analysis of RR interval series extracted from ten healthy subjects during stand-up tasks, suggest that the proposed entropy indices provide instantaneous tracking of the heartbeat complexity, also allowing for the definition of complexity variability indices. PMID:25571453

  9. DEVELOPMENT AND EVALUATION OF AN INSTANTANEOUS ATMOSPHERIC CORROSION RATE MONITOR

    EPA Science Inventory

    A research program has been carried out in which a new instantaneous atmospheric corrosion rate monitor (ACRM) has been developed and evaluated, and equipment has been constructed which will allow the use of many sensors in an economical way in outdoor exposures. In the first tas...

  10. Instantaneous Observability of Tightly Coupled SINS/GPS during Maneuvers

    PubMed Central

    Jiang, Junxiang; Yu, Fei; Lan, Haiyu; Dong, Qianhui

    2016-01-01

    The tightly coupled strapdown inertial navigation system (SINS)/global position system (GPS) has been widely used. The system observability determines whether the system state can be estimated by a filter efficiently or not. In this paper, the observability analysis of a two-channel and a three-channel tightly coupled SINS/GPS are performed, respectively, during arbitrary translational maneuvers and angle maneuvers, where the translational maneuver and angle maneuver are modeled. A novel instantaneous observability matrix (IOM) based on a reconstructed psi-angle model is proposed to make the theoretical analysis simpler, which starts from the observability definition directly. Based on the IOM, a series of theoretical analysis are performed. Analysis results show that almost all kinds of translational maneuver and angle maneuver can make a three-channel system instantaneously observable, but there is no one translational maneuver or angle maneuver can make a two-channel system instantaneously observable. The system’s performance is investigated when the system is not instantaneously observable. A series of simulation studies based on EKF are performed to confirm the analytic conclusions. PMID:27240369

  11. Instantaneous assessment of autonomic cardiovascular control during general anesthesia.

    PubMed

    Chen, Zhe; Citi, Luca; Purdon, Patrick L; Brown, Emery N; Barbieri, Riccardo

    2011-01-01

    We present a comprehensive probabilistic point process framework to estimate and monitor the instantaneous heartbeat dynamics as related to specific cardiovascular control mechanisms and hemodynamics. Assessment of the model's statistics is established through the Wiener-Volterra theory and a multivariate autoregressive (AR) structure. A variety of instantaneous cardiovascular metrics, such as heart rate (HR), heart rate variability (HRV), respiratory sinus arrhythmia (RSA), and baroreceptor-cardiac reflex (BRS), can be rigorously derived within a parametric framework and instantaneously updated with an adaptive algorithm. Instantaneous metrics of nonlinearity, such as the bispectrum of heartbeat intervals, can also be derived. We have applied the proposed point process framework to experimental recordings from healthy subjects in order to monitor cardiovascular regulation under propofol anesthesia. Results reveal interesting dynamic trends across different pharmacological interventions, confirming the ability of the algorithm to track important changes in cardiorespiratory elicited interactions, and pointing at our mathematical approach as a promising monitoring tool for an accurate, noninvasive assessment of general anesthesia. PMID:22256307

  12. ESTIMATING CONCENTRATIONS DOWNWIND FROM AN INSTANTANEOUS PUFF RELEASE

    EPA Science Inventory

    This document provides an approach to estimating concentrations downwind of an instantaneous puff release. Dispersion of the puff is described by the Gaussian puff equation, using the didpersion parameters presented in Meteorology and Atomic Energy. The primary purpose of this wo...

  13. CALIBRATION OF A PREDICTIVE MODEL FOR INSTANTANEOUSLY DISCHARGED DREDGED MATERIAL

    EPA Science Inventory

    This report describes modifications to a computer model originally developed by R.C.Y. Koh and Y.C. Chang for predicting the physical fate of dredged material instantaneously released into a water column. Changes to the simulation include the calibration and verification of the p...

  14. Instantaneous Observability of Tightly Coupled SINS/GPS during Maneuvers.

    PubMed

    Jiang, Junxiang; Yu, Fei; Lan, Haiyu; Dong, Qianhui

    2016-01-01

    The tightly coupled strapdown inertial navigation system (SINS)/global position system (GPS) has been widely used. The system observability determines whether the system state can be estimated by a filter efficiently or not. In this paper, the observability analysis of a two-channel and a three-channel tightly coupled SINS/GPS are performed, respectively, during arbitrary translational maneuvers and angle maneuvers, where the translational maneuver and angle maneuver are modeled. A novel instantaneous observability matrix (IOM) based on a reconstructed psi-angle model is proposed to make the theoretical analysis simpler, which starts from the observability definition directly. Based on the IOM, a series of theoretical analysis are performed. Analysis results show that almost all kinds of translational maneuver and angle maneuver can make a three-channel system instantaneously observable, but there is no one translational maneuver or angle maneuver can make a two-channel system instantaneously observable. The system's performance is investigated when the system is not instantaneously observable. A series of simulation studies based on EKF are performed to confirm the analytic conclusions. PMID:27240369

  15. Instantaneous Spreading Versus Space Localization for Nonrelativistic Quantum Systems

    NASA Astrophysics Data System (ADS)

    Coutinho, F. A. B.; Wreszinski, W. F.

    2016-08-01

    A theorem of Hegerfeldt (Kielanowski et al. 1998) establishes, for a class of quantum systems, a dichotomy between those which are permanently localized in a bounded region of space, and those exhibiting instantaneous spreading. We analyze in some detail the physical inconsistencies which follow from both of these options, and formulate which, in our view, are the basic open problems.

  16. Application of simultaneous active and reactive power modulation of superconducting magnetic energy storage unit to damp turbine-generator subsynchronous oscillations

    SciTech Connect

    Wu, Chijui; Lee, Yuangshung )

    1993-03-01

    An active and reactive power (P-Q) simultaneous control scheme which is based on a superconducting magnetic energy storage (SMES) unit is designed to damp out the subsynchronous resonant (SSR) oscillations of a turbine-generator unit. In order to suppress unstable torsional mode oscillations, a proportional-integral-derivative (PID) controller is employed to modulate the active and reactive power input/output of the SMES unit according to speed deviation of the generator shaft. The gains of the proposed PID controller are determined by pole assignment approach based on modal control theory. Eigenvalue analysis of the studied system shows that the PID controller is quite effective over a wide range of operating conditions. Dynamic simulations using the nonlinear system model are also performed to demonstrate the damping effect of the proposed control scheme under disturbance conditions.

  17. Battery energy storage. Another option for load-frequency-control and instantaneous reserve

    SciTech Connect

    Kunisch, H.J.; Kramer, K.G.; Dominik, H.

    1986-09-01

    Energy storage plants utilizing batteries and thyristor power converters can be operated like pumped hydrostorage units. Under the conditions actually prevailing in Europe, load leveling operation of such plants is not economical. Nevertheless, a battery energy storage plant promises both operational and economical advantages for load-frequency-control and instantaneous reserve operation. Queries according to this unconventional operation of batteries have been settled in a test facility in Berlin (West). After two years of test operation a decision was made to build up a full-scale demonstration plant, which will be commissioned in early 1987.

  18. Hysteresis effects in instantaneous frequency scaling of attenuation on 20 and 30 GHz satellite links

    NASA Technical Reports Server (NTRS)

    Sweeney, D. G.; Pratt, T.; Bostian, C. W.

    1992-01-01

    It has been observed with 20/30 GHz satellite beacon measurements that the ratio of 30 GHz to 20 GHz attenuation changes during some fade events. This ratio displays a hysteresis effect. This effect can be explained by a change in the drop size distribution (DSD) during the event. However, it appears only above approximately 6-8 dB of attenuation at 20 GHz. Instantaneous frequency scaling of attenuation is being proposed as part of an algorithm for uplink power control (ULPC) and the dynamic range of such an algorithm must be appropriately limited to avoid the hysteresis.

  19. Calculation and comparison of xenon and samarium reactivities of the HEU, LEU core in the low power research reactor.

    PubMed

    Dawahra, S; Khattab, K; Saba, G

    2015-07-01

    Comparative studies for the conversion of the fuel from HEU to LEU in the Miniature Neutron Source Reactor (MNSR) have been performed using the MCNP4C and GETERA codes. The precise calculations of (135)Xe and (149)Sm concentrations and reactivities were carried out and compared during the MNSR operation time and after shutdown for the existing HEU fuel (UAl4-Al, 90% enriched) and the potential LEU fuels (U3Si2-Al, U3Si-Al, U9Mo-Al, 19.75% enriched and UO2, 12.6% enriched) in this paper using the MCNP4C and GETERA codes. It was found that the (135)Xe and (149)Sm reactivities did not reach their equilibrium reactivities during the daily operating time of the reactor. The (149)Sm reactivities could be neglected compared to (135)Xe reactivities during the reactor operating time and after shutdown. The calculations for the UAl4-Al produced the highest (135)Xe reactivity in all the studied fuel group during the reactor operation (0.39 mk) and after the reactor shutdown (0.735 mk), It followed by U3Si-Al (0.34 mk, 0.653 mk), U3Si2-Al (0.33 mk, 0.634 mk), U9Mo-Al (0.3 mk, 0.568 mk) and UO2 (0.24 mk, 0.448 mk) fuels, respectively. Finally, the results showed that the UO2 was the best candidate for fuel conversion to LEU in the MNSR since it gave the lowest (135)Xe reactivity during the reactor operation and after shutdown. PMID:25816783

  20. Instantaneous Wavelet Energetic Transfers between Atmospheric Blocking and Local Eddies.

    NASA Astrophysics Data System (ADS)

    Fournier, Aimé

    2005-07-01

    A new wavelet energetics technique, based on best-shift orthonormal wavelet analysis (OWA) of an instantaneous synoptic map, is constructed for diagnosing nonlinear kinetic energy (KE) transfers in five observed blocking cases. At least 90% of the longitudinal variance of time and latitude band mean 50-kPa geopotential is reconstructed by only two wavelets using best shift. This superior efficiency to the standard OWAs persists for time-evolving structures. The cases comprise two categories, respectively dominated by zonal-wavenumber sets {1} and {1, 2}. Further OWA of instantaneous residual nonblocking structures, combined with new “nearness” criteria, yields three more orthogonal components, representing smaller-scale eddies near the block (upstream and downstream) and distant structures. This decomposition fulfills a vision expressed to the author by Saltzman. Such a decomposition is not obtainable by simple Fourier analysis.Eddy patterns apparent in the components' contours suggest inferring geostrophic energetic interactions, but the component Rossby numbers may be too large to support the inference. However, a new result enabled by this method is the instantaneous attribution of blocking strain-field effects to particular energetically interactive eddies, consistent with Shutts' hypothesis. Such attribution was only possible before in simplified models or in a time-average sense. In four of five blocks, the upstream eddies feed KE to the block, which in turn, in three of four cases, transmits KE to the downstream eddies. The small case size precludes statistically significant conclusions. The appendixes link low-order blocking structure and dynamics to some wavelet design principles and propose a new interaction diagnosis, similar to E-vector analysis, but instantaneous.

  1. Instantaneous Bethe-Salpeter kernel for the lightest pseudoscalar mesons

    NASA Astrophysics Data System (ADS)

    Lucha, Wolfgang; Schöberl, Franz F.

    2016-05-01

    Starting from a phenomenologically successful, numerical solution of the Dyson-Schwinger equation that governs the quark propagator, we reconstruct in detail the interaction kernel that has to enter the instantaneous approximation to the Bethe-Salpeter equation to allow us to describe the lightest pseudoscalar mesons as quark-antiquark bound states exhibiting the (almost) masslessness necessary for them to be interpretable as the (pseudo) Goldstone bosons related to the spontaneous chiral symmetry breaking of quantum chromodynamics.

  2. Speed Scaling for Energy and Performance with Instantaneous Parallelism

    NASA Astrophysics Data System (ADS)

    Sun, Hongyang; He, Yuxiong; Hsu, Wen-Jing

    We consider energy-performance tradeoff for scheduling parallel jobs on multiprocessors using dynamic speed scaling. The objective is to minimize the sum of energy consumption and certain performance metric, including makespan and total flow time. We focus on designing algorithms that are aware of the jobs' instantaneous parallelism but not their characteristics in the future. For total flow time plus energy, it is known that any algorithm that does not rely on instantaneous parallelism is Ω(ln 1/α P)-competitive, where P is the total number of processors. In this paper, we demonstrate the benefits of knowing instantaneous parallelism by presenting an O(1)-competitive algorithm. In the case of makespan plus energy, which is considered in the literature for the first time, we present an O(ln 1 - 1/α P)-competitive algorithm for batched jobs consisting of fully-parallel and sequential phases. We show that this algorithm is asymptotically optimal by providing a matching lower bound.

  3. A New Instantaneous Frequency Measure Based on The Stockwell Transform

    NASA Astrophysics Data System (ADS)

    yedlin, M. J.; Ben-Horrin, Y.; Fraser, J. D.

    2011-12-01

    We propose the use of a new transform, the Stockwell transform[1], as a means of creating time-frequency maps and applying them to distinguish blasts from earthquakes. This new transform, the Stockwell transform can be considered as a variant of the continuous wavelet transform, that preserves the absolute phase.The Stockwell transform employs a complex Morlet mother wavelet. The novelty of this transform lies in its resolution properties. High frequencies in the candidate signal are well-resolved in time but poorly resolved in frequency, while the converse is true for low frequency signal components. The goal of this research is to obtain the instantaneous frequency as a function of time for both the earthquakes and the blasts. Two methods will be compared. In the first method, we will compute the analytic signal, the envelope and the instantaneous phase as a function of time[2]. The instantaneous phase derivative will yield the instantaneous angular frequency. The second method will be based on time-frequency analysis using the Stockwell transform. The Stockwell transform will be computed in non-redundant fashion using a dyadic representation[3]. For each time-point, the frequency centroid will be computed -- a representation for the most likely frequency at that time. A detailed comparison will be presented for both approaches to the computation of the instantaneous frequency. An advantage of the Stockwell approach is that no differentiation is applied. The Hilbert transform method can be less sensitive to edge effects. The goal of this research is to see if the new Stockwell-based method could be used as a discriminant between earthquakes and blasts. References [1] Stockwell, R.G., Mansinha, L. and Lowe, R.P. "Localization of the complex spectrum: the S transform", IEEE Trans. Signal Processing, vol.44, no.4, pp.998-1001, (1996). [2]Taner, M.T., Koehler, F. "Complex seismic trace analysis", Geophysics, vol. 44, Issue 6, pp. 1041-1063 (1979). [3] Brown, R

  4. Measurement and analysis of instantaneous torque and angular velocity variations of a low speed two stroke diesel engine

    NASA Astrophysics Data System (ADS)

    Jiménez Espadafor, Francisco J.; A. Becerra Villanueva, José; Palomo Guerrero, Daniel; Torres García, Miguel; Carvajal Trujillo, Elisa; Fernández Vacas, Francisco

    2014-12-01

    This paper presents an investigation into the potential of using direct measurement of engine torque for diagnostic purposes in large engines - in this case applied to power generation. The procedures for measuring and analyzing the instantaneous torque, the angular displacement on the generator output end and the angular displacement on its free end for a ten-cylinder, low speed two stroke diesel engine are presented. Angular speed oscillations are frequently used for combustion engine diagnostics although they cannot be used to measure engine power directly. In addition, and for engines with huge inertia generators such as those used in power plants, speed oscillations are very low and this reduces the signal to noise ratio and makes the evaluation of the instantaneous angular speed very noisy. In the work described here, torque and angular displacement measurements carried out at the same point and with the same engine conditions are compared and the superior performance of torque is demonstrated. Harmonic analysis of instantaneous torque allowed the identification of the dynamic characteristics of the power train of the diesel group and clearly suggests that this signal can be used as a diagnostic tool for excitation, combustion malfunctions, or for the mechanical characteristics of the system and crankshaft stiffness. The torque distortion introduced by the generator due to the discontinuity imposed by the pole pairs is also observed in the torque signal, suggesting that the torque signal can be used to identify generator malfunction.

  5. A real-time and fine resolution analyser used to estimate the instantaneous energy distribution of Doppler signals.

    PubMed

    Fan, L; Evans, D H

    1994-01-01

    Doppler ultrasound signal analysers in current use require that the signal be stationary within the time interval of processing, and yield average results for that interval. A real-time instantaneous frequency analyser based on the Wigner distribution function (WDF) has been developed, which provides a means of analysing time-varying signals or signals with short stationary time periods, and also produces results with very high instantaneous temporal resolution without causing significant deterioration of frequency resolution. In addition to the real-time processing, the most recent 2.4 s of Doppler signal is stored in the analyser so that the operator can perform further fine analysis and obtain results with very high resolutions in both the time and frequency domains. The pseudo-instantaneous mean frequency (PIMF) and the Pseudo-Instantaneous Power Distribution (PIPD) are calculated and displayed every 4.0 ms in the real-time processing mode, and with a resolution of between 80 microseconds and 2 ms in the fine resolution analysis mode. The analyser utilises an algorithm developed so that the WDF can be calculated efficiently using the conventional Fast Fourier Transform (FFT) method, and the PIPDs are calculated from data that contribute equally. PMID:7941102

  6. A Method for Compensating Customer Voltage Drops due to Nighttime Simultaneous Charging of EVs Utilizing Reactive Power Injection from Battery Chargers

    NASA Astrophysics Data System (ADS)

    Noda, Taku; Kabasawa, Yuichiro; Fukushima, Kentaro; Nemoto, Koshichi; Uemura, Satoshi

    When we consider the global warming, the reduction of CO2 emission is one of the most important problems which require urgent solutions. One option is to integrate low-CO2-emission generators to the grid as much as possible. Another option is to replace inefficient vehicles based on internal-combustion engines with electric ones (EVs). Due to the latter, we can easily estimate that most consumers will charge EVs' batteries at nighttime. Thus, excessive voltage drops due to the nighttime simultaneous charging are supposed to be a possible future problem. This paper proposes a method for compensating the voltage drops by injecting reactive power from EV battery chargers.

  7. Instantaneous planar visualization of reacting supersonic flows using silane seeding

    NASA Technical Reports Server (NTRS)

    Smith, Michael W.; Northam, G. B.

    1991-01-01

    A new visualization technique for reacting flows has been developed. This technique, which is suitable for supersonic combustion flows, has been demonstrated on a scramjet combustor model. In this application, gaseous silane (SiH4) was added to the primary hydrogen fuel. When the fuel reacted, so did the (SiH4), producing silica (SiO2) particles in situ. The particles were illuminated with a laser sheet formed from a frequency-doubled Nd:YAG laser (532 nm) beam and the Mie scattering signal was imaged. These planar images of the silica Mie scattering provided instantaneous 'maps' of combustion progress within the turbulent reacting flowfield.

  8. Measurement of gear-tooth instantaneous deformation by optical method

    NASA Astrophysics Data System (ADS)

    Li, Jianfeng; Liu, Wenxin; Zhu, Chuanmin; Tian, Zhiren; Zhao, Junqing

    1996-10-01

    Speckle photography has been used to measure the instantaneous deformation of gear teeth when gears are rotating under load. Double exposure photograms are recorded with a pulse ruby laser, and correlation fringes formed by spatial filtering of the developed film. A new technique is presented for eliminating the influence of diffraction halo. A method reducing the noise level is proposed. As a conclusion, the values of gear tooth dynamic deformation are a little larger than those of the analytical calculated by finite element method in static condition, but the regulation both the measurement results and analytical ones is in good agreement.

  9. Collapse Arrest in Instantaneous Kerr Media via Parametric Interactions

    NASA Astrophysics Data System (ADS)

    Pasquazi, Alessia; Peccianti, Marco; Clerici, Matteo; Conti, Claudio; Morandotti, Roberto

    2014-09-01

    We demonstrate, theoretically and experimentally, that a four-wave mixing parametric interaction is able to arrest the collapse of a two-dimensional multicolor beam in an instantaneous Kerr medium. We consider two weak idlers interacting via a third order nonlinearity with two pump beams and we show that a class of collapse-free quasisolitary solutions can be experimentally observed in a normal dispersion Kerr glass. This observation is sustained by rigorous theoretical analysis demonstrating the stability of the observed self-trapped beams.

  10. Evanescent Modes and Tunnelling Instantaneously Act at a Distance

    SciTech Connect

    Nimtz, Guenter; Stahlhofen, Alfons A.

    2008-03-06

    Photonic tunnelling experiments have shown that i) the Einstein energy relation is violated, ii) the tunnelling process is non-local, iii) the signal velocity is faster than light, i.e. superluminal, iv) the tunnelling signal is not observable, since photonic tunnelling is described by virtual photons, and v) according to the experimental results the signal velocity is infinite inside the barriers, implying that tunnelling instantaneously acts at a distance. We think these properties are not compatible with the claims of many text books on Special Relativity.

  11. Instantaneous nitric oxide effect on secondary organic aerosol formation from m-xylene photooxidation

    NASA Astrophysics Data System (ADS)

    Li, Lijie; Tang, Ping; Cocker, David R.

    2015-10-01

    Secondary organic aerosol (SOA) formation from aromatic hydrocarbon photooxidation is highly sensitive to NO concentration. The instantaneous effect of NO on SOA formation from m-xylene photooxidation is investigated in this work by data mining 10 years of aromatic hydrocarbon chamber experiments conducted in the UC Riverside/CE-CERT chamber. First, the effect of sub-ppb NO concentrations on SOA formation is explored. The relationship of SOA growth rate to 1) NO2/NO ratio; 2) instantaneous HC/NO; 3) absolute NO concentration; 4) peroxy radical reaction branching ratio and 5) hydroxyl radical concentration are illustrated. Second, continuous and stepwise NO, NO2 and HONO injection are applied to m-xylene photooxidation experiments to simulate continuous NO sources in an urban area. The influence of these reaction scenarios on radical concentrations and SOA formation is explored. [HO2rad ]/[RO2rad ] shows a strong correlation with SOA yields in addition to [rad OH]/[HO2rad ], [rad OH], [HO2rad ] and [RO2rad ]. Enhanced SOA formation is observed when low NO levels (<1 ppb) are artificially maintained by continuous or step-wise injection; consistent with earlier research, SOA formation is observed to be suppressed by large initial NO injections. It is proposed that NO at sub-ppb level enhances rad OH formation increasing HO2rad and RO2rad and therefore promoting SOA formation. Further, two NO pathways (one promoting and one suppressing SOA formation) and one extremely low NO phase (NO "free") are used to demonstrate the evolution of NO impact on SOA formation during photooxidation. This study implies that SOA yields from aromatic hydrocarbon and low NOx photooxidation is previously underestimated due to differences between traditional environmental chamber experiments and atmospheric reactivity.

  12. Instantaneous, parallel mapping of protein electronic function with angle-resolved coherent wave-mixing

    NASA Astrophysics Data System (ADS)

    Mercer, Ian

    2010-03-01

    We present a novel laser method, angle-resolved coherent (ARC) wave-mixing, that separates out coherent electronic couplings from energy transfers in an instantaneous two-dimensional mapping (Ian P. Mercer et.al., Phys. Rev. Lett. 102, 57402, 2009). For this we use an ultra-broadband hollow fibre laser source. The power of the new method is demonstrated with the light harvesting complex II (LH2) of purple bacteria at ambient temperature. We observe signaturs of a coherent quantum electronic beating, a correlation between excitation and emission energies in the protein and a coherent component to the energy transfer between molecular rings. We are interested in exploring avenues for high throughput fingerprinting of molecular structure and function. Massively parallel maps, rich in detail, can be taken from solutions, surface films or solids of between 1 and 1000 microL. Each ARC map is generated instantaneously, with high throughput (currently up to 1kHz frame rate) and is noninvasive.

  13. Instantaneous electron beam emittance measurement system based on the optical transition radiation principle

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Guo; Wang, Yuan; Zhang, Kai-Zhi; Yang, Guo-Jun; Shi, Jin-Shui; Deng, Jian-Jun; Li, Jin

    2014-01-01

    One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.

  14. Estimating instantaneous peak flow from mean daily flow

    NASA Astrophysics Data System (ADS)

    Chen, B.; Krajewski, W. F.

    2015-12-01

    While instantaneous peak flow (IPF) records have historically been necessary for practical applications in flood risk management and hydraulic structure design, mean daily flow (MDF) values are often all that are available. To address this problem, we propose a simple method, which requires only MDF records as its input and uses the rising and falling slopes of daily hydrographs, to estimate IPFs. We applied this method to 144 catchments in Iowa, USA, with drainage areas ranging from about 7 to 220,000 km2. This application involves about 3800 peak flow events originating from different flood generation mechanisms over the period from 1997 to 2014. About 55% of the catchments have prediction errors within ±10%, and 85% of the catchments have predictions errors within ±20%. The method works well for catchments larger than 500 km2, poorly for catchments smaller than 100 km2, and fairly well for catchments in between these sizes. The reduction in the method's effectiveness with decreasing catchment size is due to the fact that the smaller the catchment, the more information is lost when using MDF to characterize the instantaneous flow processes. Our proposed method is simple and promising in terms of estimating IPFs from MDFs for areas where IPF records are unavailable or are insufficient.

  15. Instantaneous Helical Axis Methodology to Identify Aberrant Neck Motion

    PubMed Central

    Ellingson, Arin M.; Yelisetti, Vishal; Schulz, Craig A.; Bronfort, Gert; Downing, Joseph; Keefe, Daniel F.; Nuckley, David J.

    2013-01-01

    Background Neck pain afflicts 30-50% of the U.S. population annually; however we currently have poor diagnostic differentiation techniques to inform individualized treatment. Planar neck kinematics has been shown to be correlated with neck pain, but neck motion is much more complex than pure planar activities. Our objective was to define a methodology for determining aberrant neck kinematics and assess it. Methods We examined a complex neck kinematic activity of neck circumduction, computed the pathway of motion using the instantaneous helical axis approach in 81 patients with non-specific neck pain and in 20 non-matched symptom free subjects. Neck circumduction, or rolling of the head, represents a complex neck kinematic activity, investigating the innate coupled motion of the cervical spine at the end ranges of motion in all directions. Instance of discontinuities in the helical axis patterns, or folds, were identified and labeled as occurrences of aberrant motion. Findings The instances of aberrant motion, or folds, which are nearly non-existent in the healthy sample group, are present in both the pre and post treatment neck pain patients. Following a treatment intervention of the symptomatic patients, pain and neck disability index decreased significantly (p<0.001) concomitant with a decrease in the number of folds (p=0.021). Interpretation The present study highlights a new technique using an instantaneous helical axis approach to detect subtle abnormalities in the pathway of motion of the head about the trunk, during a neck circumduction exercise. PMID:23911108

  16. Instantaneous Wavenumber Estimation for Damage Quantification in Layered Plate Structures

    NASA Technical Reports Server (NTRS)

    Mesnil, Olivier; Leckey, Cara A. C.; Ruzzene, Massimo

    2014-01-01

    This paper illustrates the application of instantaneous and local wavenumber damage quantification techniques for high frequency guided wave interrogation. The proposed methodologies can be considered as first steps towards a hybrid structural health monitoring/ nondestructive evaluation (SHM/NDE) approach for damage assessment in composites. The challenges and opportunities related to the considered type of interrogation and signal processing are explored through the analysis of numerical data obtained via EFIT simulations of damage in CRFP plates. Realistic damage configurations are modeled from x-ray CT scan data of plates subjected to actual impacts, in order to accurately predict wave-damage interactions in terms of scattering and mode conversions. Simulation data is utilized to enhance the information provided by instantaneous and local wavenumbers and mitigate the complexity related to the multi-modal content of the plate response. Signal processing strategies considered for this purpose include modal decoupling through filtering in the frequency/wavenumber domain, the combination of displacement components, and the exploitation of polarization information for the various modes as evaluated through the dispersion analysis of the considered laminate lay-up sequence. The results presented assess the effectiveness of the proposed wavefield processing techniques as a hybrid SHM/NDE technique for damage detection and quantification in composite, plate-like structures.

  17. Sodium nitrite enhances generation of reactive oxygen species that decrease antioxidant power and inhibit plasma membrane redox system of human erythrocytes.

    PubMed

    Ansari, Fariheen Aisha; Mahmood, Riaz

    2016-08-01

    Nitrite/nitrate salts are used in fertilizers and as food preservatives. Human exposure to high levels of nitrite results in its uptake and subsequent entry into blood where it can interact with erythrocytes. We show that treatment of human erythrocytes with sodium nitrite (NaNO2 ) results in a dose-dependent increase in the production of reactive oxygen species. This was accompanied by a decrease in the antioxidant power which lowered the free radical quenching and metal-reducing ability. NaNO2 treatment also inhibited plasma membrane redox system (PMRS) of erythrocytes. These changes increase the susceptibility of erythrocytes to oxidative damage, decrease the antioxidant power of whole blood, and can be a major cause of nitrite-induced cellular toxicity. PMID:27214747

  18. An analysis of thermionic space nuclear reactor power system: I. Effect of disassembling radial reflector, following a reactivity initiated accident

    SciTech Connect

    El-Genk, M.S.; Paramonov, D. )

    1993-01-10

    An analysis is performed to determine the effect of disassembling the radial reflector of the TOPAZ-II reactor, following a hypothetical severe Reactivity Initiated Accident (RIA). Such an RIA is assumed to occur during the system start-up in orbit due to a malfunction of the drive mechanism of the control drums, causing the drums to rotate the full 180[degree] outward at their maximum speed of 1.4[degree]/s. Results indicate that disassembling only three of twelve radial reflector panels would successfully shutdown the reactor, with little overheating of the fuel and the moderator.

  19. Study on Reactive Automatic Compensation System Design

    NASA Astrophysics Data System (ADS)

    Zhe, Sun; Qingyang, Liang; Peiqing, Luo; Chenfei, Zhang

    At present, low-voltage side of transformer is public in urban distribution network, as inductive load of household appliances is increasing, the power factor decreased, this lead to a large loss of public transformer low voltage side, the supply voltage indicators can not meet user's requirements. Therefore, the design of reactive power compensation system has become another popular research. This paper introduces the principle of reactive power compensation, analyzes key technologies of reactive power compensation, design an overall program of reactive power automatic compensation system to conquer various deficiencies of reactive power automatic compensation equipment.

  20. Instantaneous signal attenuation method for analysis of PFG fractional diffusions

    NASA Astrophysics Data System (ADS)

    Lin, Guoxing

    2016-08-01

    An instantaneous signal attenuation (ISA) method for analyzing pulsed field gradient (PFG) fractional diffusion (FD) has been developed, which is modified from the propagator approach developed in 2001 by Lin et al. for analyzing PFG normal diffusion. Both, the current ISA method and the propagator method have the same fundamental basis that the total signal attenuation (SA) is the accumulation of all the ISA, and the ISA is the average SA of the whole diffusion system at each moment. However, the manner of calculating ISA is different. Unlike the use of the instantaneous propagator in the propagator method, the current method directly calculates ISA as A(K(t‧), t‧ + dt‧)/A(K(t‧), t‧), where A(K(t‧), t‧ + dt‧) and A(K(t‧), t‧) are the SA. This modification makes the current method applicable to PFG FD as the instantaneous propagator may not be obtainable in FD. The ISA method was applied to study PFG SA including the effect of finite gradient pulse widths (FGPW) for free FD, restricted FD and the FD affected by a non-homogeneous gradient field. The SA expressions were successfully obtained for all three types of free FDs while other current methods still have difficulty in obtaining all of them. The results from this method agree with reported results such as that obtained by the effective phase shift diffusion equation (EPSDE) method. The M-Wright phase distribution approximation was also used to derive an SA expression for time FD as a comparison, which agrees with ISA method. Additionally, the continuous-time random walk (CTRW) simulation was performed to simulate the SA of PFG FD, and the simulation results agree with the analytical results. Particularly, the CTRW simulation results give good support to the analytical results including FGPW effect for free FD and restricted time FD based on a fractional derivative model where there have been no corresponding theoretical reports to date. The theoretical SA expressions including FGPW obtained

  1. Instantaneous signal attenuation method for analysis of PFG fractional diffusions.

    PubMed

    Lin, Guoxing

    2016-08-01

    An instantaneous signal attenuation (ISA) method for analyzing pulsed field gradient (PFG) fractional diffusion (FD) has been developed, which is modified from the propagator approach developed in 2001 by Lin et al. for analyzing PFG normal diffusion. Both, the current ISA method and the propagator method have the same fundamental basis that the total signal attenuation (SA) is the accumulation of all the ISA, and the ISA is the average SA of the whole diffusion system at each moment. However, the manner of calculating ISA is different. Unlike the use of the instantaneous propagator in the propagator method, the current method directly calculates ISA as A(K(t'),t'+dt')/A(K(t'),t'), where A(K(t'),t'+dt') and A(K(t'),t') are the SA. This modification makes the current method applicable to PFG FD as the instantaneous propagator may not be obtainable in FD. The ISA method was applied to study PFG SA including the effect of finite gradient pulse widths (FGPW) for free FD, restricted FD and the FD affected by a non-homogeneous gradient field. The SA expressions were successfully obtained for all three types of free FDs while other current methods still have difficulty in obtaining all of them. The results from this method agree with reported results such as that obtained by the effective phase shift diffusion equation (EPSDE) method. The M-Wright phase distribution approximation was also used to derive an SA expression for time FD as a comparison, which agrees with ISA method. Additionally, the continuous-time random walk (CTRW) simulation was performed to simulate the SA of PFG FD, and the simulation results agree with the analytical results. Particularly, the CTRW simulation results give good support to the analytical results including FGPW effect for free FD and restricted time FD based on a fractional derivative model where there have been no corresponding theoretical reports to date. The theoretical SA expressions including FGPW obtained here such as [Formula: see

  2. Effects of radio frequency power on the chemical bonding, optical and mechanical properties for radio frequency reactive sputtered germanium carbide films

    NASA Astrophysics Data System (ADS)

    Hu, C. Q.; Xu, L.; Tian, H. W.; Jin, Z. S.; Lv, X. Y.; Zheng, W. T.

    2006-12-01

    Germanium carbide (Ge1-xCx) films have been prepared by radio frequency (RF) reactive sputtering of a pure Ge(111) target in a CH4/Ar mixture discharge, and their composition, chemical bonding, optical and mechanical properties have been investigated as a function of RF power. The relationship between the chemical bonding and the optical and mechanical properties of the Ge1-xCx films has been explored. The results show that the refractive index of Ge1-xCx films increases from 1.9 to 3.2 and the optical gap decreases from 1.9 to 1.0 eV as RF power increases from 80 to 250 W, which is due to an increase in the germanium content with increasing RF power. Also, it is found that the hardness of Ge1-xCx films increases with increasing RF power, which can be attributed to an increase in the fraction of sp3 Ge-C bonds at the expense of the sp2 C-C bonds in the Ge1-xCx films.

  3. Export of reactive nitrogen from coal-fired power plants in the U.S.: Estimates from a plume-in-grid modeling study - article no. D04308

    SciTech Connect

    Vijayaraghavan, K.; Zhang, Y.; Seigneur, C.; Karamchandani, P.; Snell, H.E.

    2009-02-15

    The export of reactive nitrogen (nitrogen oxides and their oxidation products, collectively referred to as NOy) from coal-fired power plants in the U.S. to the rest of the world could have a significant global contribution to ozone. Traditional Eulerian gridded air quality models cannot characterize accurately the chemistry and transport of plumes from elevated point sources such as power plant stacks. A state-of-the-science plume-in-grid (PinG) air quality model, a reactive plume model embedded in an Eulerian gridded model, is used to estimate the export of NOy from 25 large coal-fired power plants in the U. S. (in terms of NOx and SO{sub 2} emissions) in July 2001 to the global atmosphere. The PinG model used is the Community Multiscale Air Quality Model with Advanced Plume Treatment (CMAQ-APT). A benchmark simulation with only the gridded model, CMAQ, is also conducted for comparison purposes. The simulations with and without advanced plume treatment show differences in the calculated export of NOy from the 25 plants considered reflecting the effect of using a detailed and explicit treatment of plume transport and chemistry. The advanced plume treatment results in 31% greater simulated export of NOy compared to the purely grid-based modeling approach. The export efficiency of NOy (the fraction of NOy emitted that is exported) is predicted to be 21% without APT and 27% with APT. When considering only export through the eastern boundary across the Atlantic, CMAQ-APT predicts that the export efficiency is 24% and that 2% of NOy is exported as NOx, 49% as inorganic nitrate, and 25% as PAN. These results are in reasonably good agreement with an analysis reported in the literature of aircraft measurements over the North Atlantic.

  4. Video measurements of instantaneous forces of flapping wing vehicles

    NASA Astrophysics Data System (ADS)

    Jennings, Alan; Mayhew, Michael; Black, Jonathan

    2015-12-01

    Flapping wings for small aerial vehicles have revolutionary potential for maneuverability and endurance. Ornithopters fail to achieve the performance of their biological equivalents, despite extensive research on how animals fly. Flapping wings produce peak forces due to the stroke reversal of the wing. This research demonstrates in-flight measurements of an ornithopter through the use of image processing, specifically measuring instantaneous forces. Results show that the oscillation about the flight path is significant, being about 20% of the mean velocity and up to 10 g's. Results match forces with deformations of the wing to contrast the timing and wing shape of the upstroke and the downstroke. Holding the vehicle fixed (e.g. wind tunnel testing or simulations) structural resonance is affected along with peak forces, also affecting lift. Non-contact, in-flight measurements are proposed as the best method for matching the flight conditions of flapping wing vehicles.

  5. Inversion of instantaneous equivalent absorption coefficient and its application

    SciTech Connect

    Weihua, W. )

    1992-01-01

    Absorption coefficient is an important parameter for reservoir description. The major troubles in extracting absorption coefficient from seismic data are amplitude and waveform distortions; they greatly restrict the inversion which is based on reflection amplitude variation or reflection frequency variation. This paper presents a new method which avoids amplitude and uses waveform variation gradient in wave propagation to make the inversion of absorption coefficient. Apparent absorption coefficient and pseudo absorption coefficient are adopted so as to remove the influence which the waveform distortion due to thin bed tuning brings to absorption coefficient extraction. The final instantaneous equivalent absorption coefficient, a true absorption coefficient which reflects real absorptive character of a seismic medium, can be obtained by subtracting the pseudo absorption coefficient (inversely calculated using maximum entropy) from the apparent absorption coefficient the authors have calculated.

  6. Phonetic applications of the time-corrected instantaneous frequency spectrogram.

    PubMed

    Fulop, Sean A

    2007-01-01

    A reassigned or time-corrected instantaneous frequency spectrogram has been developed in the work of a number of practitioners. Here we present a general description of this imaging technique and explore its manifold applications to acoustic phonetics. The TCIF spectrogram shows the locations of signal components with unrivalled precision, eliminating the blurring and smearing of components that hamper the readability of the conventional spectrogram. Formants of vowels and other resonants are shown with great accuracy by observing glottal pulsations at very short time scales with a wideband analysis. A further post-processing technique is also described, by which signal components such as formants, as well as impulsive events, can be effectively isolated to the exclusion of other signal information. When the phonation process is examined this closely, a variety of evidence surfaces which supports recent developments in the theory and computational simulation of aeroacoustic phenomena in speech. Narrowband analysis is also demonstrated to permit pitch tracking with relative ease. PMID:18421245

  7. Full field imaging based instantaneous hyperspectral absolute refractive index measurement

    SciTech Connect

    Baba, Justin S; Boudreaux, Philip R

    2012-01-01

    Multispectral refractometers typically measure refractive index (RI) at discrete monochromatic wavelengths via a serial process. We report on the demonstration of a white light full field imaging based refractometer capable of instantaneous multispectral measurement of absolute RI of clear liquid/gel samples across the entire visible light spectrum. The broad optical bandwidth refractometer is capable of hyperspectral measurement of RI in the range 1.30 1.70 between 400nm 700nm with a maximum error of 0.0036 units (0.24% of actual) at 414nm for a = 1.50 sample. We present system design and calibration method details as well as results from a system validation sample.

  8. [Detonation temperature measurement of epoxypropane using instantaneous spectrum method].

    PubMed

    Li, Ying; Li, Ping; Xiao, Hai-Bo; Hu, Dong; Yuan, Chang-Ying

    2008-03-01

    After solving the problems of synchronization of the measuring system and the avoidance of false trigger signal, the instantaneous emission spectrum of epoxypropane with an exposure time of 2 micros and a resolution of 0.2 nm was acquired from a side window of a shock tube at the very moment when the epoxypropane transformed from deflagration to detonation. The measuring system consists of an advanced intensified charge-coupled-device spectroscopic detector, a digital delay generator DG535, an explosion shock tube and optical fibers. The DDT process was monitored by pressure transducers. After correcting the intensity of the spectrum obtained, the background curve of the heat radiation intensity of the detonation was given immediately. The detonation temperature of 2 416 K for epoxypropane was derived from fitting the curve with Planck blackbody formula by least squares principle. The detonation temperature of epoxypropane can provide an experimental datum for analyzing the microscopic mechanism of DDT process. PMID:18536396

  9. Developing EPQ models for non-instantaneous deteriorating items

    NASA Astrophysics Data System (ADS)

    Ghasemi, Naser

    2015-04-01

    In this paper, the classical economic production quantity (EPQ) model is developed for non-instantaneous deteriorating items by considering a relationship between the holding cost and the ordering cycle length. Two models are developed. First, the proposed model is considered when backorders are not permitted and this condition is waived for the second case. The cost functions associated with these models are proved to be convex and an algorithm is designed to find the optimum solutions of the proposed model. Results show that the relationship between holding cost and ordering cycle length has a significant impact on the optimal lot size and total cost in the EPQ model. Numerical examples are presented to demonstrate the utility of the models.

  10. Instantaneous engine frictional torque, its components and piston assembly friction

    SciTech Connect

    Nichols, F.A. ); Henein, N.A. . Center for Automotive Research)

    1992-05-01

    The overall goal of this report is to document the work done to determine the instantaneous frictional torque of internal combustion engine by using a new approach known as (P-[omega]) method developed at Wayne State University. The emphasis has been to improve the accuracy of the method, and apply it to both diesel and gasoline engines under different operating conditions. Also work included an investigation to determine the effect of using advanced materials and techniques to coat the piston rings on the instantaneous engine frictional torque and the piston assembly friction. The errors in measuring the angular velocity, [omega], have been determined and found to be caused by variations in the divisions within one encoder, encoder-to-encoder variations, misalignment within the encoder itself and misalignment between the encoder and crankshaft. The errors in measuring the cylinder gas pressure, P, have been determined and found to be caused by transducer-to-transducer variations, zero drift, thermal stresses and lack of linearity. The ability of the (P-[omega]) method in determining the frictional torque of many engine components has been demonstrated. These components include valve train, fuel injection pump with and without fuel injection, and piston with and without different ring combinations. The emphasis in this part of the research program has been on the piston-ring assembly friction. The effects of load and other operating variables on IFT have been determined. The motoring test, which is widely used in industry to measure engine friction has been found to be inaccurate. The errors have been determined at different loads.

  11. Instantaneous mantle dynamics of the Western Mediterranean region

    NASA Astrophysics Data System (ADS)

    Mohammadi, S.; Geenen, T.; van den Berg, A. P.; Spakman, W.

    2012-04-01

    Our research is concerned with the establishment of links between deep mantle processes and surface deformation. Our main focus is on the instantaneous mantle dynamics of the European-Mediterranean region and its surface responses. Here we have constructed instantaneous 3-D dynamic models of the Western Mediterranean region with focus on subduction below Betic-Rif-Alboran region. The driving forces in the models are due to temperature variation, which is derived from seismic tomography. The tomography model, which is used in our research, is the global P-wave speed model UU-P07 (M. Amaru, PhD Thesis, Utrecht University, 2007; Van der Meer et al., Nature Geoscience, 2010). For the subducted slab in this region we have assumed a temperature profile according to the Jurassic-Early Cretaceous age of the oceanic lithosphere. The boundary conditions used in the dynamic models allow us to include constraints from motions of the larger tectonic plates regarding the convergence of African and Eurasian plates. We present the topography response and the predicted patterns of surface deformations for this region based on a number of assumptions regarding the scaling of tomography to temperature and density, and rheology. A depth and temperature dependent rheology is assumed for most of the domain. Lithosphere faults are modeled with low viscosity zones. The mesh-generating tool used enables us to have finer resolution at the scale of a few kilometers in fault zones and along plate boundaries in the area of interest. 1) This research is part of the EUROCORES TOPO-EUROPE, particularly of project TOPO-4D

  12. Mammalian energetics. Instantaneous energetics of puma kills reveal advantage of felid sneak attacks.

    PubMed

    Williams, Terrie M; Wolfe, Lisa; Davis, Tracy; Kendall, Traci; Richter, Beau; Wang, Yiwei; Bryce, Caleb; Elkaim, Gabriel Hugh; Wilmers, Christopher C

    2014-10-01

    Pumas (Puma concolor) live in diverse, often rugged, complex habitats. The energy they expend for hunting must account for this complexity but is difficult to measure for this and other large, cryptic carnivores. We developed and deployed a physiological SMART (species movement, acceleration, and radio tracking) collar that used accelerometry to continuously monitor energetics, movements, and behavior of free-ranging pumas. This felid species displayed marked individuality in predatory activities, ranging from low-cost sit-and-wait behaviors to constant movements with energetic costs averaging 2.3 times those predicted for running mammals. Pumas reduce these costs by remaining cryptic and precisely matching maximum pouncing force (overall dynamic body acceleration = 5.3 to 16.1g) to prey size. Such instantaneous energetics help to explain why most felids stalk and pounce, and their analysis represents a powerful approach for accurately forecasting resource demands required for survival by large, mobile predators. PMID:25278610

  13. Instantaneous and efficient surface wave excitation of a low pressure gas or gases

    DOEpatents

    Levy, Donald J.; Berman, Samuel M.

    1988-01-01

    A system for instantaneously ionizing and continuously delivering energy in the form of surface waves to a low pressure gas or mixture of low pressure gases, comprising a source of rf energy, a discharge container, (such as a fluorescent lamp discharge tube), an rf shield, and a coupling device responsive to rf energy from the source to couple rf energy directly and efficiently to the gas or mixture of gases to ionize at least a portion of the gas or gases and to provide energy to the gas or gases in the form of surface waves. The majority of the rf power is transferred to the gas or gases near the inner surface of the discharge container to efficiently transfer rf energy as excitation energy for at least one of the gases. The most important use of the invention is to provide more efficient fluorescent and/or ultraviolet lamps.

  14. A Method for Capturing Sub-Gridscale Interactions in Numerical Simulation of Flow and Reactive Transport in Power-Law Media

    NASA Astrophysics Data System (ADS)

    Travis, B. J.

    2013-12-01

    For nonlinear, coupled flow and reactive transport in heterogeneous systems, capturing sub-gridscale dynamics is a serious challenge for coarse-grained numerical simulation. Even simply for linear, uncomplicated flow systems, accurate estimation of sub-gridscale effects may require averaging over a possibly tensor, multi-scale permeability distribution. Stochastic process modeling and statistical analysis methods are available and are being improved for calculating average and variance properties of flow and transport systems. Frequently, in addition to the average dynamics, a solution for an individual realization, or for many realizations, is desired or required. For media whose smaller-scale heterogeneity can be approximated by a power law (fractal) model (and this is approximately true for many soils), fractal interpolating functions, constrained by measured properties and distributions, provide an efficient way to capture sub-gridscale dynamics for individual realizations. An advantage of this approach is that it can be incorporated readily into conventional finite difference or finite element flow and transport codes, providing a multi-resolution solution for less cost than a finely-grained one. Several examples illustrate the potential usefulness of this approach for numerical simulation of flow and reactive transport in heterogeneous media. Comparisons are made to finely gridded traditional numerical solutions. Limitations and conditions of use are discussed.

  15. NDE evaluation of the intergranular corrosion susceptibility of a 2205 duplex stainless steel using thermoelectric power and double loop electrochemical potentiokinetic reactivation methods

    NASA Astrophysics Data System (ADS)

    Ortiz, N.; Carreón, H.; Ruiz, A.

    2013-01-01

    There is a need for a nondestructive technique to assess rapidly and with confidence the degree of sensitization (DOS) in duplex stainless steel (DSS). In this investigation, we present the use of thermoelectric power (TEP) measurements as nondestructive method for the determination of DOS in isothermally aged 2205 DSS at 700°C for different aging times. The DOS of the aged samples was first established by performing the double loop electrochemical potentiokinetic reactivation (DL-EPR) test. The microstructural evolution was evaluated by scanning electron microscopy (SEM). Experimental results indicate that TEP coefficient is sensitive to gradual microstructural changes produced by thermal aging and can be used to monitor IGC sensitization of 2205 duplex stainless steel.

  16. Thermonuclear runaways in nova outbursts. 2: Effect of strong, instantaneous, local fluctuations

    NASA Technical Reports Server (NTRS)

    Shankar, Anurag; Arnett, David

    1994-01-01

    In an attempt to understand the manner in which nova outbursts are initiated on the surface of a white dwarf, we investigate the effects fluctuations have on the evolution of a thermonuclear runaway. Fluctuations in temperature density, or the composition of material in the burning shell may arise due to the chaotic flow field generated by convection when it occurs, or by the accretion process itself. With the aid of two-dimensional reactive flow calculations, we consider cases where a strong fluctutation in temperature arises during the early, quiescent accretion phase or during the later, more dynamic, explosion phase. In all cases we find that an instantaneous, local temperature fluctuation causes the affected material to become Rayleigh-Taylor unstable. The rapid rise and subsequent expansion of matter immediately cools the hot blob, which prevents the lateral propagation of burning. This suggests that local temperature fluctuations do not play a significant role in directly initiating the runaway, especially during the early stages. However, they may provide an efficient mechanism of mixing core material into the envelope (thereby pre-enriching the fuel for subsequent episodes of explosive hydrogen burning) and of mixing substantial amounts of the radioactive nucleus N-13 into the surface layers, making novae potential gamma-ray sources. This suggests that it is the global not the local, evolution of the core-envelope interface to high temperatures which dominates the development of the runaway. We also present a possible new scenario for the initiation of nova outbursts based on our results.

  17. Use of instantaneous bandwidth for excising AM-FM jammers in direct-sequence spread-spectrum communication systems

    NASA Astrophysics Data System (ADS)

    Jang, SeongCheol; Loughlin, Patrick J.

    2000-11-01

    While spread spectrum systems are robust to many types of interference, performance can be significantly degraded if the interference is strong enough, particularly for wideband interferences. In these situations, various signal processing methods can be employed to remove, or excise the jammer prior to despreading the received signal, resulting in enhanced performance. We investigate the effects of amplitude and frequency modulated (AM-FM) jammers on the performance of direct sequence spread spectrum communication systems. We demonstrate that such jammers cause significant degradation in bit-error-rate with increasing AM on systems designed to excise FM jammers only (i.e., systems with fixed notch-width excision filters). We propose an adaptive technique that utilizes the instantaneous bandwidth of the jammer, in addition to its instantaneous frequency, to filter wideband AM- FM interference from the DSSS signal. We also investigate the effects of adapting the filter notch-depth as well, according to the instantaneous power of the jammer. Simulations demonstrate additional improvement in system performance for the proposed adaptive technique compared to fixed notch-width and fixed notch- depth excision filters.

  18. Reactive programming of simulations in physics

    NASA Astrophysics Data System (ADS)

    Boussinot, Frédéric; Monasse, Bernard; Susini, Jean-Ferdy

    2015-04-01

    We consider the Reactive Programming (RP) approach to simulate physical systems. The choice of RP is motivated by the fact that RP genuinely offers logical parallelism, instantaneously broadcast events, and dynamic creation/destruction of parallel components and events. To illustrate our approach, we consider the implementation of a system of Molecular Dynamics, in the context of Java with the Java3D library for 3D visualization.

  19. Archiving and Near Real Time Visualization of USGS Instantaneous Data

    NASA Astrophysics Data System (ADS)

    Zaslavsky, I.; Ryan, D.; Whitenack, T.; Valentine, D. W.; Rodriguez, M.

    2009-12-01

    The CUAHSI Hydrologic Information System project has been developing databases, services and online and desktop software applications supporting standards-based publication and access to large volumes of hydrologic data from US federal agencies and academic partners. In particular, the CUAHSI WaterML 1.x schema specification for exchanging hydrologic time series, earlier published as an OGC Discussion Paper (2007), has been adopted by the United States Geological Survey to provide web service access to USGS daily values and instantaneous data. The latter service, making available raw measurements of discharge, gage height and several other parameters for over 10,000 USGS real time measurement points, was announced by USGS, as an experimental WaterML-compliant service, at the end of July 2009. We demonstrate an online application that leverages the new service for nearly continuous harvesting of USGS real time data, and simultaneous visualization and analysis of the data streams. To make this possible, we integrate service components of the CUAHSI software stack with Open Source Data Turbine (OSDT) system, an NSF-supported software environment for robust and scalable assimilation of multimedia data streams (e.g. from sensors), and interfacing with a variety of viewers, databases, archival systems and client applications. Our application continuously queries USGS Instantaneous water data service (which provides access to 15-min measurements updated at USGS every 4 hours), and maps the results for each station-variable combination to a separate "channel", which is used by OSDT to quickly access and manipulate the time series. About 15,000 channels are used, which makes it by far the largest deployment of OSDT. Using RealTime Data Viewer, users can now select one or more stations of interest (e.g. from upstream or downstream from each other), and observe and annotate simultaneous dynamics in the respective discharge and gage height values, using fast forward or

  20. Instantaneous frequency measurement by in-fiber 0.5th order fractional differentiation

    NASA Astrophysics Data System (ADS)

    Poveda-Wong, L.; Carrascosa, A.; Cuadrado-Laborde, C.; Cruz, J. L.; Díez, A.; Andrés, M. V.

    2016-07-01

    We experimentally demonstrate the possibility to retrieve the instantaneous frequency profile of a given temporal light pulse by in-fiber fractional order differentiation of 0.5th-order. The signal's temporal instantaneous frequency profile is obtained by simple dividing two temporal intensity profiles, namely the intensities of the input and output pulses of a spectrally-shifted fractional order differentiation. The results are supported by the experimental measurement of the instantaneous frequency profile of a mode-locked laser.

  1. Toward reconciling instantaneous roadside measurements of light duty vehicle exhaust emissions with type approval driving cycles.

    PubMed

    Rhys-Tyler, Glyn A; Bell, Margaret C

    2012-10-01

    A method is proposed to relate essentially instantaneous roadside measurements of vehicle exhaust emissions, with emission results generated over a type approval driving cycle. An urban remote sensing data set collected in 2008 is used to define the dynamic relationship between vehicle specific power and exhaust emissions, across a range of vehicle ages, engine capacities, and fuel types. The New European Driving Cycle is synthesized from the remote sensing data using vehicle specific power to characterize engine load, and the results compared with official published emissions data from vehicle type approval tests over the same driving cycle. Mean carbon monoxide emissions from gasoline-powered cars ≤ 3 years old measured using remote sensing are found to be 1.3 times higher than published original type approval test values; this factor increases to 2.2 for cars 4-8 years old, and 6.4 for cars 9-12 years old. The corresponding factors for diesel cars are 1.1, 1.4, and 1.2, respectively. Results for nitric oxide, hydrocarbons, and particulate matter are also reported. The findings have potential implications for the design of traffic management interventions aimed at reducing emissions, fleet inspection and maintenance programs, and the specification of vehicle emission models. PMID:22894824

  2. Limitations of rupture forecasting exposed by instantaneously triggered earthquake doublet

    NASA Astrophysics Data System (ADS)

    Nissen, E.; Elliott, J. R.; Sloan, R. A.; Craig, T. J.; Funning, G. J.; Hutko, A.; Parsons, B. E.; Wright, T. J.

    2016-04-01

    Earthquake hazard assessments and rupture forecasts are based on the potential length of seismic rupture and whether or not slip is arrested at fault segment boundaries. Such forecasts do not generally consider that one earthquake can trigger a second large event, near-instantaneously, at distances greater than a few kilometres. Here we present a geodetic and seismological analysis of a magnitude 7.1 intracontinental earthquake that occurred in Pakistan in 1997. We find that the earthquake, rather than a single event as hitherto assumed, was in fact an earthquake doublet: initial rupture on a shallow, blind reverse fault was followed just 19 s later by a second rupture on a separate reverse fault 50 km away. Slip on the second fault increased the total seismic moment by half, and doubled both the combined event duration and the area of maximum ground shaking. We infer that static Coulomb stresses at the initiation location of the second earthquake were probably reduced as a result of the first. Instead, we suggest that a dynamic triggering mechanism is likely, although the responsible seismic wave phase is unclear. Our results expose a flaw in earthquake rupture forecasts that disregard cascading, multiple-fault ruptures of this type.

  3. Sensor for measuring instantaneous angle of attack of helicopter blades

    NASA Technical Reports Server (NTRS)

    Barna, P. S.

    1980-01-01

    Systematic investigations were performed on a variety of probes to determine their potential for possible application as sensors attached to helicopter blades to measure both the instantaneous angle of attack as well as the dynamic head during actual flight operations. After some preliminary considerations a sensor of essentially spherical shape, about 30 mm in diameter, was designed. The sensor was provided with three pressure ports, and it housed two pressure transducers required for sensing the prevailing pressures acting outside on the surface. The sensors were subsequently tested in the laboratory under a variety of flow conditions to determine their aerodynamic characteristics. Two series of tests were performed: in the first series the sensor was fixed in space while exposed to steady uniform flow, while in the second series the sensor was made to oscillate, thus simulating the cyclic pitch change of the helicopter blades. While the cyclic pitch frequencies were of about the same magnitude as encountered in flight, the flow velocities during tests fell well below those experienced in a rotating blade. The tests showed that the sensors performed satisfactorily under low subsonic flow conditions with frequencies not exceeding five Hz.

  4. Instantaneous BeiDou-GPS attitude determination: A performance analysis

    NASA Astrophysics Data System (ADS)

    Nadarajah, Nandakumaran; Teunissen, Peter J. G.; Raziq, Noor

    2014-09-01

    The advent of modernized and new global navigation satellite systems (GNSS) has enhanced the availability of satellite based positioning, navigation, and timing (PNT) solutions. Specifically, it increases redundancy and yields operational back-up or independence in case of failure or unavailability of one system. Among existing GNSS, the Chinese BeiDou system (BDS) is being developed and will consist of geostationary (GEO) satellites, inclined geosynchronous orbit (IGSO) satellites, and medium-Earth-orbit (MEO) satellites. In this contribution, a BeiDou-GPS robustness analysis is carried out for instantaneous, unaided attitude determination. Precise attitude determination using multiple GNSS antennas mounted on a platform relies on the successful resolution of the integer carrier phase ambiguities. The constrained Least-squares AMBiguity Decorrelation Adjustment (C-LAMBDA) method has been developed for the quadratically constrained GNSS compass model that incorporates the known baseline length. In this contribution the method is used to analyse the attitude determination performance when using the GPS and BeiDou systems. The attitude determination performance is evaluated using GPS/BeiDou data sets from a real data campaign in Australia spanning several days. The study includes the performance analyses of both stand-alone and mixed constellation (GPS/BeiDou) attitude estimation under various satellite deprived environments. We demonstrate and quantify the improved availability and accuracy of attitude determination using the combined constellation.

  5. Development and evaluation of an instantaneous atmospheric corrosion rate monitor

    NASA Astrophysics Data System (ADS)

    Mansfeld, F.; Jeanjaquet, S. L.; Kendig, M. W.; Roe, D. K.

    1985-06-01

    A research program was carried out in which a new instantaneous atmospheric corrosion rate monitor (ACRM) was developed and evaluated, and equipment was constructed which will allow the use of many sensors in an economical way in outdoor exposures. In the first task, the ACRM was developed and tested in flow chambers in which relative humidity and gaseous and particulate pollutant levels can be controlled. Diurnal cycles and periods of rain were simulated. The effects of aerosols were studied. A computerized system was used for collection, storage, and analysis of the electrochemical data. In the second task, a relatively inexpensive electronics system for control of the ACRM and measurement of atmospheric corrosion rates was designed and built. In the third task, calibration of deterioration rates of various metallic and nonmetallic materials with the response of the ACRMs attached to these materials was carried out under controlled environmental conditions using the system developed in the second task. A Quality Assurance project plan was prepared with inputs from the Rockwell International Environmental Monitoring and Service Center and Quality Assurance System audits were performed.

  6. User-interactive electronic skin for instantaneous pressure visualization

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Hwang, David; Yu, Zhibin; Takei, Kuniharu; Park, Junwoo; Chen, Teresa; Ma, Biwu; Javey, Ali

    2013-10-01

    Electronic skin (e-skin) presents a network of mechanically flexible sensors that can conformally wrap irregular surfaces and spatially map and quantify various stimuli. Previous works on e-skin have focused on the optimization of pressure sensors interfaced with an electronic readout, whereas user interfaces based on a human-readable output were not explored. Here, we report the first user-interactive e-skin that not only spatially maps the applied pressure but also provides an instantaneous visual response through a built-in active-matrix organic light-emitting diode display with red, green and blue pixels. In this system, organic light-emitting diodes (OLEDs) are turned on locally where the surface is touched, and the intensity of the emitted light quantifies the magnitude of the applied pressure. This work represents a system-on-plastic demonstration where three distinct electronic components—thin-film transistor, pressure sensor and OLED arrays—are monolithically integrated over large areas on a single plastic substrate. The reported e-skin may find a wide range of applications in interactive input/control devices, smart wallpapers, robotics and medical/health monitoring devices.

  7. Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition

    PubMed Central

    Wang, Fu-Tai; Chan, Hsiao-Lung; Wang, Chun-Li; Jian, Hung-Ming; Lin, Sheng-Hsiung

    2015-01-01

    Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD) can decompose a signal into several intrinsic mode functions (IMFs) that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method. PMID:26198231

  8. Heart Instantaneous Frequency Based Estimation of HRV from Blood Pressure Waveforms

    NASA Astrophysics Data System (ADS)

    Lucena, Fausto; Barros, Allan Kardec; Takeuchi, Yoshinori; Ohnishi, Noboru

    The heart rate variability (HRV) is a measure based on the time position of the electrocardiogram (ECG) R-waves. There is a discussion whether or not we can obtain the HRV pattern from blood pressure (BP). In this paper, we propose a method for estimating HRV from a BP signal based on a HIF algorithm and carrying out experiments to compare BP as an alternative measurement of ECG to calculate HRV. Based on the hypotheses that ECG and BP have the same harmonic behavior, we model an alternative HRV signal using a nonlinear algorithm, called heart instantaneous frequency (HIF). It tracks the instantaneous frequency through a rough fundamental frequency using power spectral density (PSD). A novelty in this work is to use fundamental frequency instead of wave-peaks as a parameter to estimate and quantify beat-to-beat heart rate variability from BP waveforms. To verify how the estimate HRV signals derived from BP using HIF correlates to the standard gold measures, i.e. HRV derived from ECG, we use a traditional algorithm based on QRS detectors followed by thresholding to localize the R-wave time peak. The results show the following: 1) The spectral error caused by misestimation of time by R-peak detectors is demonstrated by an increase in high-frequency bands followed by the loss of time domain pattern. 2) The HIF was shown to be robust against noise and nuisances. 3) By using statistical methods and nonlinear analysis no difference between HIF derived from BP and HRV derived from ECG was observed.

  9. Small-Scale Hydroelectric Power Demonstration Project: reactivation of the Elk Rapids Hydroelectric Facility. Final technical and construction cost report

    SciTech Connect

    Not Available

    1985-05-01

    The Elk Rapids powerhouse dam is located on the Elk River channel in the Village of Elk Rapids, Michigan. Together with a small spillway structure located approximately 500 ft south of the dam, it constitutes the outlet to Lake Michigan for Elk Lake, Skegemog Lake, Torch Lake, Lake Bellaire, Clam Lake, and several smaller lakes. Power has been generated at the Elk Rapids site since the late nineteenth century, but the history of the present facility goes back to 1916 with the construction of the existing powerhouse dam by the Elk Rapids Iron Works Company. The facility was designed to contain four vertical-shaft generating units; however, only a single 270 hp Leffel type K unit was installed in 1916. In 1929, two additional Leffel units, rated 525 hp, were installed, and in 1930 a third 525 hp Leffel unit was added completely utilizing the capacity of the powerhouse and bringing the combined turbine capacity to 1845 hp.

  10. Reactive arthritis

    MedlinePlus

    Reactive arthritis is a group of conditions that may involve the joints, eyes, and urinary and genital systems. ... The exact cause of reactive arthritis is unknown. It occurs most often in men younger than age 40. It may follow an infection in the urethra ...

  11. 16 CFR Appendix D4 to Part 305 - Water Heaters-Instantaneous-Gas

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Water Heaters-Instantaneous-Gas D4 Appendix... CONGRESS RULE CONCERNING DISCLOSURES REGARDING ENERGY CONSUMPTION AND WATER USE OF CERTAIN HOME APPLIANCES...) Pt. 305, App. D4 Appendix D4 to Part 305—Water Heaters-Instantaneous-Gas Link to an...

  12. 16 CFR Appendix D4 to Part 305 - Water Heaters-Instantaneous-Gas

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Water Heaters-Instantaneous-Gas D4 Appendix... CONGRESS RULE CONCERNING DISCLOSURES REGARDING ENERGY CONSUMPTION AND WATER USE OF CERTAIN HOME APPLIANCES...) Pt. 305, App. D4 Appendix D4 to Part 305—Water Heaters-Instantaneous-Gas Range Information...

  13. Instantaneous detection of spatial gradient errors in differential GNSS

    NASA Astrophysics Data System (ADS)

    Jing, Jing

    Global Navigation Satellite Systems (GNSS) have become a critical element of modern engineering and scientific applications. GPS is currently being used in the design of navigation systems for both civil and military aviation applications. Differential GPS carrier phase measurements between antennas provide a very precise measurement that is useful for these applications. In fact, ground infrastructure has already been implemented in the Ground Based Augmentation System (GBAS) to take advantage of these precise measurements for use in civil aviation. Furthermore, these antennas can also be used to detect and isolate certain signal-in-space (SIS) failures and anomalies that are hazardous to aviation applications, for example the ionospheric anomalies and ephemeris failures. This realization, in turn, has led to the development of numerous carrier-phase based monitors. One drawback of the majority of these monitors is that their performance within a given configuration is dependent on how antennas are paired to form double differences. In contrast, the null space monitor approach is developed to provide consistent detection performance regardless of how the antennas are paired which combines measurements from multiple, spatially separated ground antennas through a null space transformation. The instantaneous carrier phase monitor cannot detect all gradients due to the presence of integer ambiguities. These ambiguities cannot be resolved because the gradient magnitude is unknown a priori. Furthermore, it has been shown that the performance of such monitors is highly dependent on the reference antenna topology. The range of detectable gradients for all carrier phase monitors depends on two factors: the number of antennas and their configuration. Antenna configuration is often overlooked as a means to improve performance. and heuristic arguments typically prevail in the associated siting decisions. However. such heuristics do not provide the maximum detectable range of

  14. Instantaneous attribute profiling of GPR data using the HHT technique

    NASA Astrophysics Data System (ADS)

    Jeng*, Y.; Yu**, H.-M.; Chen, C.-S.

    2012-04-01

    * Corresponding author ** Presenting author The analysis of instantaneous attributes (IAs) is a useful tool for interpreting ground penetrating radar (GPR) data. However, the conventional Hilbert transform used for deriving the IAs is controversial because it cannot provide the full IAs of the data. The conventional method only leads to an apparent spectrogram. A newer analysis method, the Hilbert-Huang transform (HHT), consisting of empirical mode decomposition (EMD) and the Hilbert transform is applied in this study for seeking a better resolution of IAs. In this study, we decomposed the original GPR data into a series of intrinsic mode functions (IMFs) with ensemble empirical mode decomposition (EEMD), and then applied the Hilbert transform to generate the imaginary part of each IMF component. As a consequence, the IMF can be expressed in complex form after the Hilbert transform, and the IAs of each IMF component is obtained by simple trigonometry calculation and differentiation accordingly. With the aid of the EEMD technique, the Hilbert transform is well-behaved; therefore, it renders full IAs of each decomposed component as functions of time. We display the IAs of the GPR section in separate profiles to demonstrate the interpretation of their physical significance. A controlled experimental study was performed on a site of known buried targets to acquire sample data for testing this new method and establishing the basic data processing sequence. We also conducted a pseudo-3D GPR survey with 50 MHz antennas along the channel bed of the Chingshui River in Ilan County, northeastern Taiwan to collect real data for further evaluation. To compare the HHT with the conventional Hilbert transform, we applied both techniques to the GPR stacked section. The IAs are displayed in amplitude, phase, and frequency profiles. The residue resulting from the EEMD is normally excluded to remove the bias. The signal can further be enhanced by removing noisy components before

  15. Reactive Arthritis

    MedlinePlus

    ... with treatment and may cause joint damage. What Research Is Being Conducted on Reactive Arthritis? Researchers continue ... such as methotrexate and sulfasalazine. More information on research is available from the following websites: National Institutes ...

  16. Preparation of diamond-like carbon films using reactive Ar/CH4 high power impulse magnetron sputtering system with negative pulse voltage source for substrate

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2016-04-01

    Diamond-like carbon films were prepared using a reactive Ar/CH4 high-power impulse magnetron sputtering system with a negative pulse voltage source for the substrate, changing the CH4 fraction up to 15% in the total pressure range from 0.3 to 2 Pa. The magnitude of the negative pulse voltage for the substrate was also varied up to about 500 V. The hardness of films monotonically increased with increasing magnitude of the negative pulse voltage. The films with hardnesses between 16.5 and 23 GPa were prepared at total pressures less than 0.5 Pa and CH4 fractions less than 10% by applying an appropriate negative pulse voltage of 300-400 V. In X-ray photoelectron spectroscopy, the area ratio C-C sp3/(C-C sp2 + C-C sp3) in the C 1s core level was higher than 30% at pressures less than 0.5 Pa and CH4 fractions less than 15%. On the other hand, the films with hardnesses between 5 and 10 GPa were prepared with a relatively high growth rate at the partial pressures of CH4 higher than 0.1 Pa. However, the observation of the photoluminescence background in Raman spectroscopy indicated a relatively high hydrogen content.

  17. Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Chun; Tang, Ping-Han; Wu, Ten-Ming

    2013-11-01

    By exploiting the instantaneous normal mode (INM) analysis for models of flexible molecules, we investigate intermolecular and intramolecular vibrations of water from the atomic point of view. With two flexible SPC/E models, our investigations include three aspects about their INM spectra, which are separated into the unstable, intermolecular, bending, and stretching bands. First, the O- and H-atom contributions in the four INM bands are calculated and their stable INM spectra are compared with the power spectra of the atomic velocity autocorrelation functions. The unstable and intermolecular bands of the flexible models are also compared with those of the SPC/E model of rigid molecules. Second, we formulate the inverse participation ratio (IPR) of the INMs, respectively, for the O- and H-atom and molecule. With the IPRs, the numbers of the three species participated in the INMs are estimated so that the localization characters of the INMs in each band are studied. Further, by the ratio of the IPR of the H atom to that of the O atom, we explore the number of involved OH bond per molecule participated in the INMs. Third, by classifying simulated molecules into subensembles according to the geometry of their local environments or their H-bond configurations, we examine the local-structure effects on the bending and stretching INM bands. All of our results are verified to be insensible to the definition of H-bond. Our conclusions about the intermolecular and intramolecular vibrations in water are given.

  18. Sustained Magnetic Responses in Temporal Cortex Reflect Instantaneous Significance of Approaching and Receding Sounds

    PubMed Central

    Bach, Dominik R.; Furl, Nicholas; Barnes, Gareth; Dolan, Raymond J.

    2015-01-01

    Rising sound intensity often signals an approaching sound source and can serve as a powerful warning cue, eliciting phasic attention, perception biases and emotional responses. How the evaluation of approaching sounds unfolds over time remains elusive. Here, we capitalised on the temporal resolution of magnetoencephalograpy (MEG) to investigate in humans a dynamic encoding of perceiving approaching and receding sounds. We compared magnetic responses to intensity envelopes of complex sounds to those of white noise sounds, in which intensity change is not perceived as approaching. Sustained magnetic fields over temporal sensors tracked intensity change in complex sounds in an approximately linear fashion, an effect not seen for intensity change in white noise sounds, or for overall intensity. Hence, these fields are likely to track approach/recession, but not the apparent (instantaneous) distance of the sound source, or its intensity as such. As a likely source of this activity, the bilateral inferior temporal gyrus and right temporo-parietal junction emerged. Our results indicate that discrete temporal cortical areas parametrically encode behavioural significance in moving sound sources where the signal unfolded in a manner reminiscent of evidence accumulation. This may help an understanding of how acoustic percepts are evaluated as behaviourally relevant, where our results highlight a crucial role of cortical areas. PMID:26226395

  19. Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view

    SciTech Connect

    Chen, Yu-Chun; Tang, Ping-Han; Wu, Ten-Ming

    2013-11-28

    By exploiting the instantaneous normal mode (INM) analysis for models of flexible molecules, we investigate intermolecular and intramolecular vibrations of water from the atomic point of view. With two flexible SPC/E models, our investigations include three aspects about their INM spectra, which are separated into the unstable, intermolecular, bending, and stretching bands. First, the O- and H-atom contributions in the four INM bands are calculated and their stable INM spectra are compared with the power spectra of the atomic velocity autocorrelation functions. The unstable and intermolecular bands of the flexible models are also compared with those of the SPC/E model of rigid molecules. Second, we formulate the inverse participation ratio (IPR) of the INMs, respectively, for the O- and H-atom and molecule. With the IPRs, the numbers of the three species participated in the INMs are estimated so that the localization characters of the INMs in each band are studied. Further, by the ratio of the IPR of the H atom to that of the O atom, we explore the number of involved OH bond per molecule participated in the INMs. Third, by classifying simulated molecules into subensembles according to the geometry of their local environments or their H-bond configurations, we examine the local-structure effects on the bending and stretching INM bands. All of our results are verified to be insensible to the definition of H-bond. Our conclusions about the intermolecular and intramolecular vibrations in water are given.

  20. Instantaneous and Frequency-Warped Signal Processing Techniques for Auditory Source Separation.

    NASA Astrophysics Data System (ADS)

    Wang, Avery Li-Chun

    This thesis summarizes several contributions to the areas of signal processing and auditory source separation. The philosophy of Frequency-Warped Signal Processing is introduced as a means for separating the AM and FM contributions to the bandwidth of a complex-valued, frequency-varying sinusoid p (n), transforming it into a signal with slowly-varying parameters. This transformation facilitates the removal of p (n) from an additive mixture while minimizing the amount of damage done to other signal components. The average winding rate of a complex-valued phasor is explored as an estimate of the instantaneous frequency. Theorems are provided showing the robustness of this measure. To implement frequency tracking, a Frequency-Locked Loop algorithm is introduced which uses the complex winding error to update its frequency estimate. The input signal is dynamically demodulated and filtered to extract the envelope. This envelope may then be remodulated to reconstruct the target partial, which may be subtracted from the original signal mixture to yield a new, quickly-adapting form of notch filtering. Enhancements to the basic tracker are made which, under certain conditions, attain the Cramer -Rao bound for the instantaneous frequency estimate. To improve tracking, the novel idea of Harmonic -Locked Loop tracking, using N harmonically constrained trackers, is introduced for tracking signals, such as voices and certain musical instruments. The estimated fundamental frequency is computed from a maximum-likelihood weighting of the N tracking estimates, making it highly robust. The result is that harmonic signals, such as voices, can be isolated from complex mixtures in the presence of other spectrally overlapping signals. Additionally, since phase information is preserved, the resynthesized harmonic signals may be removed from the original mixtures with relatively little damage to the residual signal. Finally, a new methodology is given for designing linear-phase FIR filters

  1. Method for preparing hydride configurations and reactive metal surfaces

    DOEpatents

    Silver, G.L.

    1984-05-18

    A method for preparing reactive metal surfaces, particularly uranium surfaces is disclosed, whereby the metal is immediately reactive to hydrogen gas at room temperature and low pressure. The metal surfaces are first pretreated by exposure to an acid which forms an adherent hydride-bearing composition on the metal surface. Subsequent heating of the pretreated metal at a temperature sufficient to decompose the hydride coating in vacuum or inert gas renders the metal surface instantaneously reactive to hydrogen gas at room temperature and low pressure.

  2. Reactive arthritis.

    PubMed

    Keat, A

    1999-01-01

    Reactive arthritis is one of the spondyloarthropathy family of clinical syndromes. The clinical features are those shared by other members of the spondyloarthritis family, though it is distinguished by a clear relationship with a precipitating infection. Susceptibility to reactive arthritis is closely linked with the class 1 HLA allele B27; it is likely that all sub-types pre-dispose to this condition. The link between HLA B27 and infection is mirrored by the development of arthritis in HLA B27-transgenic rats. In this model, arthritis does not develop in animals maintained in a germ-free environment. Infections of the gastrointestinal, genitourinary and respiratory tract appear to provoke reactive arthritis and a wide range of pathogens has now been implicated. Although mechanistic parallels may exist, reactive arthritis is distinguished from Lyme disease, rheumatic fever and Whipple's disease by virtue of the distinct clinical features and the link with HLA B27. As in these conditions both antigens and DNA of several micro-organisms have been detected in joint material from patients with reactive arthritis. The role of such disseminated microbial elements in the provocation or maintenance of arthritis remains unclear. HLA B27-restricted T-cell responses to microbial antigens have been demonstrated and these may be important in disease pathogenesis. The importance of dissemination of bacteria from sites of mucosal infection and their deposition in joints has yet to be fully understood. The role of antibiotic therapy in the treatment of reactive arthritis is being explored; in some circumstances, both the anti-inflammatory and anti-microbial effects of certain antibiotics appear to be valuable. The term reactive arthritis should be seen as a transitory one, reflecting a concept which may itself be on the verge of replacement, as our understanding of the condition develops. Nevertheless it appropriately describes arthritis that is associated with demonstrable

  3. Reactive sputtering of δ-ZrH{sub 2} thin films by high power impulse magnetron sputtering and direct current magnetron sputtering

    SciTech Connect

    Högberg, Hans Tengdelius, Lina; Eriksson, Fredrik; Broitman, Esteban; Lu, Jun; Jensen, Jens; Hultman, Lars; Samuelsson, Mattias

    2014-07-01

    Reactive sputtering by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a Zr target in Ar/H{sub 2} plasmas was employed to deposit Zr-H films on Si(100) substrates, and with H content up to 61 at. % and O contents typically below 0.2 at. % as determined by elastic recoil detection analysis. X-ray photoelectron spectroscopy reveals a chemical shift of ∼0.7 eV to higher binding energies for the Zr-H films compared to pure Zr films, consistent with a charge transfer from Zr to H in a zirconium hydride. X-ray diffraction shows that the films are single-phase δ-ZrH{sub 2} (CaF{sub 2} type structure) at H content >∼55 at. % and pole figure measurements give a 111 preferred orientation for these films. Scanning electron microscopy cross-section images show a glasslike microstructure for the HiPIMS films, while the DCMS films are columnar. Nanoindentation yield hardness values of 5.5–7 GPa for the δ-ZrH{sub 2} films that is slightly harder than the ∼5 GPa determined for Zr films and with coefficients of friction in the range of 0.12–0.18 to compare with the range of 0.4–0.6 obtained for Zr films. Wear resistance testing show that phase-pure δ-ZrH{sub 2} films deposited by HiPIMS exhibit up to 50 times lower wear rate compared to those containing a secondary Zr phase. Four-point probe measurements give resistivity values in the range of ∼100–120 μΩ cm for the δ-ZrH{sub 2} films, which is slightly higher compared to Zr films with values in the range 70–80 μΩ cm.

  4. Pulse-by-pulse method to characterize partially coherent pulse propagation in instantaneous nonlinear media.

    PubMed

    Lajunen, Hanna; Torres-Company, Víctor; Lancis, Jesús; Silvestre, Enrique; Andrès, Pedro

    2010-07-01

    We propose a numerical method for analyzing extensively the evolution of the coherence functions of nonstationary optical pulses in dispersive, instantaneous nonlinear Kerr media. Our approach deals with the individual propagation of samples from a properly selected ensemble that reproduces the coherence properties of the input pulsed light. In contrast to the usual strategy assuming Gaussian statistics, our numerical algorithm allows us to model the propagation of arbitrary partially coherent pulses in media with strong and instantaneous nonlinearities. PMID:20639984

  5. Skylab reactivation mission report

    NASA Technical Reports Server (NTRS)

    Chubb, W. B.

    1980-01-01

    On July 11, 1979, Skylab impacted the Earth's surface. The debris dispersion area stretched from the South Eastern Indian Ocean across a sparsely populated section of Western Australia. The events leading to the reentry of Skylab are discussed and a final assessment of the Skylab debris impact footprint is presented. Also included are detailed evaluations of the various Skylab systems that were reactivated when control of Skylab was regained in mid-1978 after having been powered down since February 4, 1974.

  6. Cross-correlation of instantaneous phase increments in pressure-flow fluctuations: Applications to cerebral autoregulation

    NASA Astrophysics Data System (ADS)

    Chen, Zhi; Hu, Kun; Stanley, H. Eugene; Novak, Vera; Ivanov, Plamen Ch.

    2006-03-01

    We investigate the relationship between the blood flow velocities (BFV) in the middle cerebral arteries and beat-to-beat blood pressure (BP) recorded from a finger in healthy and post-stroke subjects during the quasisteady state after perturbation for four different physiologic conditions: supine rest, head-up tilt, hyperventilation, and CO2 rebreathing in upright position. To evaluate whether instantaneous BP changes in the steady state are coupled with instantaneous changes in the BFV, we compare dynamical patterns in the instantaneous phases of these signals, obtained from the Hilbert transform, as a function of time. We find that in post-stroke subjects the instantaneous phase increments of BP and BFV exhibit well-pronounced patterns that remain stable in time for all four physiologic conditions, while in healthy subjects these patterns are different, less pronounced, and more variable. We propose an approach based on the cross-correlation of the instantaneous phase increments to quantify the coupling between BP and BFV signals. We find that the maximum correlation strength is different for the two groups and for the different conditions. For healthy subjects the amplitude of the cross-correlation between the instantaneous phase increments of BP and BFV is small and attenuates within 3-5 heartbeats. In contrast, for post-stroke subjects, this amplitude is significantly larger and cross-correlations persist up to 20 heartbeats. Further, we show that the instantaneous phase increments of BP and BFV are cross-correlated even within a single heartbeat cycle. We compare the results of our approach with three complementary methods: direct BP-BFV cross-correlation, transfer function analysis, and phase synchronization analysis. Our findings provide insight into the mechanism of cerebral vascular control in healthy subjects, suggesting that this control mechanism may involve rapid adjustments (within a heartbeat) of the cerebral vessels, so that BFV remains steady in

  7. Fuel Temperature Coefficient of Reactivity

    SciTech Connect

    Loewe, W.E.

    2001-07-31

    A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.

  8. What Is Reactive Arthritis?

    MedlinePlus

    ... Arthritis PDF Version Size: 69 KB November 2014 What is Reactive Arthritis? Fast Facts: An Easy-to- ... Information About Reactive Arthritis and Other Related Conditions What Causes Reactive Arthritis? Sometimes, reactive arthritis is set ...

  9. Thermodynamics of iodide adsorption at the instantaneous air-water interface

    NASA Astrophysics Data System (ADS)

    Stern, Abraham C.; Baer, Marcel D.; Mundy, Christopher J.; Tobias, Douglas J.

    2013-03-01

    We performed molecular dynamics simulations using both polarizable and non-polarizable force fields to study the adsorption of iodide to the air-water interface. A novel aspect of our analysis is that the progress of ion adsorption is measured as the distance from the instantaneous interface, which is defined by a coarse-graining scheme proposed recently by Willard and Chandler ["Instantaneous liquid interfaces," J. Phys. Chem. B 114, 1954-1958 (2010), 10.1021/jp909219k]. Referring structural and thermodynamic quantities to the instantaneous interface unmasks molecular-scale details that are obscured by thermal fluctuations when the same quantities are referred to an average measure of the position of the interface, such as the Gibbs dividing surface. Our results suggest that an ion adsorbed at the interface resides primarily in the topmost water layer, and the interfacial location of the ion is favored by enthalpy and opposed by entropy.

  10. Observation of Brownian motion in liquids at short times: instantaneous velocity and memory loss.

    PubMed

    Kheifets, Simon; Simha, Akarsh; Melin, Kevin; Li, Tongcang; Raizen, Mark G

    2014-03-28

    Measurement of the instantaneous velocity of Brownian motion of suspended particles in liquid probes the microscopic foundations of statistical mechanics in soft condensed matter. However, instantaneous velocity has eluded experimental observation for more than a century since Einstein's prediction of the small length and time scales involved. We report shot-noise-limited, high-bandwidth measurements of Brownian motion of micrometer-sized beads suspended in water and acetone by an optical tweezer. We observe the hydrodynamic instantaneous velocity of Brownian motion in a liquid, which follows a modified energy equipartition theorem that accounts for the kinetic energy of the fluid displaced by the moving bead. We also observe an anticorrelated thermal force, which is conventionally assumed to be uncorrelated. PMID:24675957

  11. Torque Ripple Minimization with Instantaneous Current Feedback Compensation for Switched Reluctance Motors

    NASA Astrophysics Data System (ADS)

    Rishab, Paudel; Ishikawa, Hiroki; Naitoh, Haruo

    This paper presents a novel strategy for torque ripple minimization with instantaneous current feedback compensation for switched reluctance motors (SRMs). The authors have already proposed suitable reference current profiles and a control algorithm to obtain an instantaneously flat torque of an SRM and confirmed the effectiveness of the algorithm by performing experiment in the low-speed range. In the high-speed range, however, the winding current cannot track the reference current owing to the lack of necessary voltage. In this study, mathematical analyses on the inability to trace the current profiles are performed. A new current control with compensation of the current profiles with instantaneous feedback is proposed. The validity of the proposed control is demonstrated by the experimental results.

  12. Instantaneous Click Chemistry by a Copper-Containing Polymeric-Membrane-Installed Microflow Catalytic Reactor.

    PubMed

    Yamada, Yoichi M A; Ohno, Aya; Sato, Takuma; Uozumi, Yasuhiro

    2015-11-23

    The copper(I)-catalyzed Huisgen cycloaddition (azide-alkyne cycloaddition) is an important reaction in click chemistry that ideally proceeds instantaneously. An instantaneous Huisgen cycloaddition has been developed that uses a novel catalytic dinuclear copper complex-containing polymeric membrane-installed microflow device. A polymeric membranous copper catalyst was prepared from poly(4-vinylpyridine), copper(II) sulfate, sodium chloride, and sodium ascorbate at the interface of two laminar flows inside microchannels. Elucidation of the structure by XANES, EXAFS, and elemental analysis, as well as second-order Møller-Plesset perturbation theory (MP2) calculations and density functional theory (DFT) calculations assigned the local structure near Cu as a μ-chloro dinuclear Cu(I) complex. The microflow device promotes the instantaneous click reaction of a variety of alkynes and organic azides to afford the corresponding triazoles in quantitative yield. PMID:26439220

  13. Reactivity effects in VVER-1000 of the third unit of the kalinin nuclear power plant at physical start-up. Computations in ShIPR intellectual code system with library of two-group cross sections generated by UNK code

    NASA Astrophysics Data System (ADS)

    Zizin, M. N.; Zimin, V. G.; Zizina, S. N.; Kryakvin, L. V.; Pitilimov, V. A.; Tereshonok, V. A.

    2010-12-01

    The ShIPR intellectual code system for mathematical simulation of nuclear reactors includes a set of computing modules implementing the preparation of macro cross sections on the basis of the two-group library of neutron-physics cross sections obtained for the SKETCH-N nodal code. This library is created by using the UNK code for 3D diffusion computation of first VVER-1000 fuel loadings. Computation of neutron fields in the ShIPR system is performed using the DP3 code in the two-group diffusion approximation in 3D triangular geometry. The efficiency of all groups of control rods for the first fuel loading of the third unit of the Kalinin Nuclear Power Plant is computed. The temperature, barometric, and density effects of reactivity as well as the reactivity coefficient due to the concentration of boric acid in the reactor were computed additionally. Results of computations are compared with the experiment.

  14. Reactivity effects in VVER-1000 of the third unit of the kalinin nuclear power plant at physical start-up. Computations in ShIPR intellectual code system with library of two-group cross sections generated by UNK code

    SciTech Connect

    Zizin, M. N.; Zimin, V. G.; Zizina, S. N. Kryakvin, L. V.; Pitilimov, V. A.; Tereshonok, V. A.

    2010-12-15

    The ShIPR intellectual code system for mathematical simulation of nuclear reactors includes a set of computing modules implementing the preparation of macro cross sections on the basis of the two-group library of neutron-physics cross sections obtained for the SKETCH-N nodal code. This library is created by using the UNK code for 3D diffusion computation of first VVER-1000 fuel loadings. Computation of neutron fields in the ShIPR system is performed using the DP3 code in the two-group diffusion approximation in 3D triangular geometry. The efficiency of all groups of control rods for the first fuel loading of the third unit of the Kalinin Nuclear Power Plant is computed. The temperature, barometric, and density effects of reactivity as well as the reactivity coefficient due to the concentration of boric acid in the reactor were computed additionally. Results of computations are compared with the experiment.

  15. Instantaneous scale of fluctuation using Kalman-TFD and applications in machine tool monitoring

    NASA Astrophysics Data System (ADS)

    Madhavan, P. G.

    1997-10-01

    A new theory of random fields based on the concept of local averaging was developed in the 80s where the second-order properties of the random fields are characterized by the variance function. Certain asymptotic properties of the variance function lead to the definition of a scalar called the 'scale of fluctuation,' which has many interesting properties. A non- parametric method of estimating instantaneous scale of fluctuation is developed using the time-varying model-based time-frequency distribution. A wide range of random processes can be modeled by appropriate state-space models with white process noise. For properly defined state transition matrices and observation vectors, the states estimated using Kalman filtering or smoothing algorithms provide the estimated time-frequency distribution (Kalman-TFD). Using Kalman-TFD, the instantaneous scale of fluctuation is estimated. Performance of this estimator is compared to other instantaneous and block methods using the coefficient of variation of the estimators. The Kalman-TFD-based scale of fluctuation estimator has a coefficient of variation of 6% where as other methods yield coefficients of variation greater than 35%. The instantaneous scale of fluctuation quantifies the temporal variability of the underlying system and possible resultant limit- cycle oscillations. Tests with real vibration data from machine tools before and during chatter show that the estimated instantaneous scale of fluctuation may permit on-line prediction of chatter development many hundreds of milliseconds in advance. To explain the behavior of the estimated instantaneous scale of fluctuation during pre-chatter period, detailed simulations were undertaken which revealed that the random process during pre- chatter condition goes through an increase in 'degrees-of-freedom' or its unit standard deviation contour volume.

  16. Assessing Dynamic Spectral Causality by Lagged Adaptive Directed Transfer Function and Instantaneous Effect Factor

    PubMed Central

    Xu, Haojie; Lu, Yunfeng; Zhu, Shanan

    2014-01-01

    It is of significance to assess the dynamic spectral causality among physiological signals. Several practical estimators adapted from spectral Granger causality have been exploited to track dynamic causality based on the framework of time-varying multivariate autoregressive (tvMVAR) models. The non-zero covariance of the model’s residuals has been used to describe the instantaneous effect phenomenon in some causality estimators. However, for the situations with Gaussian residuals in some autoregressive models, it is challenging to distinguish the directed instantaneous causality if the sufficient prior information about the “causal ordering” is missing. Here, we propose a new algorithm to assess the time-varying causal ordering of tvMVAR model under the assumption that the signals follow the same acyclic causal ordering for all time lags and to estimate the instantaneous effect factor (IEF) value in order to track the dynamic directed instantaneous connectivity. The time-lagged adaptive directed transfer function (ADTF) is also estimated to assess the lagged causality after removing the instantaneous effect. In the present study, we firstly investigated the performance of the causal-ordering estimation algorithm and the accuracy of IEF value. Then, we presented the results of IEF and time-lagged ADTF method by comparing with the conventional ADTF method through simulations of various propagation models. Statistical analysis results suggest that the new algorithm could accurately estimate the causal ordering and give a good estimation of the IEF values in the Gaussian residual conditions. Meanwhile, the time-lagged ADTF approach is also more accurate in estimating the time-lagged dynamic interactions in a complex nervous system after extracting the instantaneous effect. In addition to the simulation studies, we applied the proposed method to estimate the dynamic spectral causality on real visual evoked potential (VEP) data in a human subject. Its usefulness in

  17. Overestimating Fish Counts by Non-Instantaneous Visual Censuses: Consequences for Population and Community Descriptions

    PubMed Central

    Ward-Paige, Christine; Mills Flemming, Joanna; Lotze, Heike K.

    2010-01-01

    Background Increasingly, underwater visual censuses (UVC) are used to assess fish populations. Several studies have demonstrated the effectiveness of protected areas for increasing fish abundance or provided insight into the natural abundance and structure of reef fish communities in remote areas. Recently, high apex predator densities (>100,000 individuals·km−2) and biomasses (>4 tonnes·ha−1) have been reported for some remote islands suggesting the occurrence of inverted trophic biomass pyramids. However, few studies have critically evaluated the methods used for sampling conspicuous and highly mobile fish such as sharks. Ideally, UVC are done instantaneously, however, researchers often count animals that enter the survey area after the survey has started, thus performing non-instantaneous UVC. Methodology/Principal Findings We developed a simulation model to evaluate counts obtained by divers deploying non-instantaneous belt-transect and stationary-point-count techniques. We assessed how fish speed and survey procedure (visibility, diver speed, survey time and dimensions) affect observed fish counts. Results indicate that the bias caused by fish speed alone is huge, while survey procedures had varying effects. Because the fastest fishes tend to be the largest, the bias would have significant implications on their biomass contribution. Therefore, caution is needed when describing abundance, biomass, and community structure based on non-instantaneous UVC, especially for highly mobile species such as sharks. Conclusions/Significance Based on our results, we urge that published literature state explicitly whether instantaneous counts were made and that survey procedures be accounted for when non-instantaneous counts are used. Using published density and biomass values of communities that include sharks we explore the effect of this bias and suggest that further investigation may be needed to determine pristine shark abundances and the existence of inverted

  18. The instantaneous rate dependence in low temperature laboratory rock friction and rock deformation experiments

    USGS Publications Warehouse

    Beeler, N.M.; Tullis, T.E.; Kronenberg, A.K.; Reinen, L.A.

    2007-01-01

    Earthquake occurrence probabilities that account for stress transfer and time-dependent failure depend on the product of the effective normal stress and a lab-derived dimensionless coefficient a. This coefficient describes the instantaneous dependence of fault strength on deformation rate, and determines the duration of precursory slip. Although an instantaneous rate dependence is observed for fracture, friction, crack growth, and low temperature plasticity in laboratory experiments, the physical origin of this effect during earthquake faulting is obscure. We examine this rate dependence in laboratory experiments on different rock types using a normalization scheme modified from one proposed by Tullis and Weeks [1987]. We compare the instantaneous rate dependence in rock friction with rate dependence measurements from higher temperature dislocation glide experiments. The same normalization scheme is used to compare rate dependence in friction to rock fracture and to low-temperature crack growth tests. For particular weak phyllosilicate minerals, the instantaneous friction rate dependence is consistent with dislocation glide. In intact rock failure tests, for each rock type considered, the instantaneous rate dependence is the same size as for friction, suggesting a common physical origin. During subcritical crack growth in strong quartzofeldspathic and carbonate rock where glide is not possible, the instantaneous rate dependence measured during failure or creep tests at high stress has long been thought to be due to crack growth; however, direct comparison between crack growth and friction tests shows poor agreement. The crack growth rate dependence appears to be higher than the rate dependence of friction and fracture by a factor of two to three for all rock types considered. Copyright 2007 by the American Geophysical Union.

  19. Experimental study on instantaneous thrust and lift of two plunging wings in tandem

    NASA Astrophysics Data System (ADS)

    Gong, Wu Qi; Jia, Bo Bo; Xi, Guang

    2016-01-01

    Two tandem wings undergoing a two-dimensional sinusoidal plunging motion are studied in a low Reynolds number water tunnel. The influence of the phase angle and leading-edge vortex (LEV) on the peak value of the instantaneous thrust and lift is studied. The instantaneous lift and thrust are measured by a force sensor; the velocity and vorticity fields are captured by digital particle image velocimetry. For the forewing, noticeable differences at various phase angles are found in the peak value of the instantaneous lift and thrust rather than in their minimum value. The LEV of the hindwing increased the maximum effective angle of attack of the forewing and enhanced the jet-like flow behind the forewing, which accounts for the increase in peak value. For the hindwing, the phase angle determines the sign of the forewing-shed LEV when the hindwing encounters this LEV. If the forewing-shed LEV before the leading edge of the hindwing has the opposite sense of rotation as the LEV of the hindwing, the velocity of the flow on the windward side of the hindwing increases, resulting in high instantaneous thrust and lift. If the two LEVs have the same sense of rotation, the forewing-shed LEV hinders the growth of the hindwing LEV because of the small effective angle of attack, leading to low instantaneous thrust and lift. Non-circulatory forces on the wings are calculated according to a potential flow model. Results show that the non-circulatory force has important effects on the peak value and symmetry of the instantaneous lift and thrust curves.

  20. Engine combustion control via fuel reactivity stratification

    SciTech Connect

    Reitz, Rolf Deneys; Hanson, Reed M.; Splitter, Derek A.; Kokjohn, Sage L.

    2015-07-14

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  1. Engine combustion control via fuel reactivity stratification

    SciTech Connect

    Reitz, Rolf Deneys; Hanson, Reed M; Splitter, Derek A; Kokjohn, Sage L

    2013-12-31

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choose the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  2. Engine combustion control via fuel reactivity stratification

    DOEpatents

    Reitz, Rolf Deneys; Hanson, Reed M.; Splitter, Derek A.; Kokjohn, Sage L.

    2016-06-28

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  3. Precise measurement of instantaneous volume of eccrine sweat gland in mental sweating by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Sugawa, Yoshihiko; Fukuda, Akihiro; Ohmi, Masato

    2015-03-01

    We have demonstrated dynamic analysis of the physiological function of eccrine sweat glands underneath skin surface by optical coherence tomography (OCT). We propose a method for extraction of the target eccrine sweat gland by use of the connected component extraction process and the adaptive threshold method, where the en-face OCT images are constructed by the SS-OCT. Furthermore, we demonstrate precise measurement of instantaneous volume of the sweat gland in response to the external stimulus. The dynamic change of instantaneous volume of eccrine sweat gland in mental sweating is performed by this method during the period of 300 sec with the frame intervals of 3.23 sec.

  4. Combining the Power of Irmpd with Ion-Molecule Reactions: the Structure and Reactivity of Radical Ions of Cysteine and its Derivatives

    NASA Astrophysics Data System (ADS)

    Lesslie, Michael; Osburn, Sandra; Berden, Giel; Oomens, J.; Ryzhov, Victor

    2015-06-01

    Most of the work on peptide radical cations has involved protons as the source of charge. Nonetheless, using metal ions as charge sources often offers advantages like stabilization of the structure via multidentate coordination and the elimination of the "mobile proton". Moreover, characterization of metal-bound amino acids is of general interest as the interaction of peptide side chains with metal ions in biological systems is known to occur extensively. In the current study, we generate thiyl radicals of cysteine and homocysteine in the gas phase complexed to alkali metal ions. Subsequently, we utilize infrared multiple-photon dissociation (IRMPD) and ion-molecule reactions (IMR) to characterize the structure and reactivity of these radical ions. Our group has worked extensively with the cysteine-based radical cations and anions, characterizing the gas-phase reactivity and rearrangement of the amino acid and several of its derivatives. In a continuation of this work, we are perusing the effects of metal ions as the charge bearing species on the reactivity of the sulfur radical. Our S-nitroso chemistry can easily be used in conjunction with metal ion coordination to produce initial S-based radicals in peptide radical-metal ion complexes. In all cases we have been able to achieve radical formation with significant yield to study reactivity. Ion-molecule reactions of metallated radicals with allyl iodide, dimethyl disulfide, and allyl bromide have all shown decreasing reactivity going down group 1A. Recently, we determined the experimental IR spectra for the homocysteine radical cation with Li+, Na+, and K+ as the charge bearing species at the FELIX facility. For comparison, the protonated IR spectrum of homocysteine has previously been obtained by our group. A preliminary match of the IR spectra has been confirmed. Finally, calculations are underway to determine the bond distances of all the metal adduct structures.

  5. Instantaneous and time-averaged dispersion and measurement models for estimation theory applications with elevated point source plumes

    NASA Technical Reports Server (NTRS)

    Diamante, J. M.; Englar, T. S., Jr.; Jazwinski, A. H.

    1977-01-01

    Estimation theory, which originated in guidance and control research, is applied to the analysis of air quality measurements and atmospheric dispersion models to provide reliable area-wide air quality estimates. A method for low dimensional modeling (in terms of the estimation state vector) of the instantaneous and time-average pollutant distributions is discussed. In particular, the fluctuating plume model of Gifford (1959) is extended to provide an expression for the instantaneous concentration due to an elevated point source. Individual models are also developed for all parameters in the instantaneous and the time-average plume equations, including the stochastic properties of the instantaneous fluctuating plume.

  6. A method to account for variation of average compressor inlet pressure during instantaneous distortion analyses

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Wenzel, L. M.

    1976-01-01

    A method is presented to calculate the available surge margin as a function of time and incorporate it into an instantaneous distortion analysis. Results show that inlet pressure variations which cause only a small change at the compressor exit can cause a significant variation in the available surge margin.

  7. Estimation of the instantaneous rotation speed using complex shifted Morlet wavelets

    NASA Astrophysics Data System (ADS)

    Gryllias, Konstantinos C.; Antoniadis, Ioannis A.

    2013-07-01

    The ability of the complex continuous wavelet transform (CCWT) to provide also an estimation of the instantaneous frequency of a signal, parallel to the estimation of the instantaneous amplitude of the signal, is proposed as an approach for the estimation of the instantaneous rotation speed of machinery. Complex shifted Morlet wavelets (CSMW) present a number of advantages. The concept of shifting the Morlet wavelet in the frequency domain allows the simultaneous optimal selection of both the wavelet center frequency and the wavelet bandwidth. In this paper it is shown that the recovery of the signal frequency can be performed accurately, without the requirement that the wavelet center frequency coincides to the signal frequency. Contrarily, the accurate recovery of the signal amplitude requires additionally this last condition. The algorithm is tested on two synthetic signals and four non-stationary experimental vibration signals, in an experimental fault test rig and in a motorcycle engine. The proposed instantaneous frequency estimation approach presents very good results and in comparison to the Hilbert Transform achieves a significantly lower RMSE.

  8. Inhomogeneous Point-Processes to Instantaneously Assess Affective Haptic Perception through Heartbeat Dynamics Information

    NASA Astrophysics Data System (ADS)

    Valenza, G.; Greco, A.; Citi, L.; Bianchi, M.; Barbieri, R.; Scilingo, E. P.

    2016-06-01

    This study proposes the application of a comprehensive signal processing framework, based on inhomogeneous point-process models of heartbeat dynamics, to instantaneously assess affective haptic perception using electrocardiogram-derived information exclusively. The framework relies on inverse-Gaussian point-processes with Laguerre expansion of the nonlinear Wiener-Volterra kernels, accounting for the long-term information given by the past heartbeat events. Up to cubic-order nonlinearities allow for an instantaneous estimation of the dynamic spectrum and bispectrum of the considered cardiovascular dynamics, as well as for instantaneous measures of complexity, through Lyapunov exponents and entropy. Short-term caress-like stimuli were administered for 4.3–25 seconds on the forearms of 32 healthy volunteers (16 females) through a wearable haptic device, by selectively superimposing two levels of force, 2 N and 6 N, and two levels of velocity, 9.4 mm/s and 65 mm/s. Results demonstrated that our instantaneous linear and nonlinear features were able to finely characterize the affective haptic perception, with a recognition accuracy of 69.79% along the force dimension, and 81.25% along the velocity dimension.

  9. Inhomogeneous Point-Processes to Instantaneously Assess Affective Haptic Perception through Heartbeat Dynamics Information

    PubMed Central

    Valenza, G.; Greco, A.; Citi, L.; Bianchi, M.; Barbieri, R.; Scilingo, E. P.

    2016-01-01

    This study proposes the application of a comprehensive signal processing framework, based on inhomogeneous point-process models of heartbeat dynamics, to instantaneously assess affective haptic perception using electrocardiogram-derived information exclusively. The framework relies on inverse-Gaussian point-processes with Laguerre expansion of the nonlinear Wiener-Volterra kernels, accounting for the long-term information given by the past heartbeat events. Up to cubic-order nonlinearities allow for an instantaneous estimation of the dynamic spectrum and bispectrum of the considered cardiovascular dynamics, as well as for instantaneous measures of complexity, through Lyapunov exponents and entropy. Short-term caress-like stimuli were administered for 4.3–25 seconds on the forearms of 32 healthy volunteers (16 females) through a wearable haptic device, by selectively superimposing two levels of force, 2 N and 6 N, and two levels of velocity, 9.4 mm/s and 65 mm/s. Results demonstrated that our instantaneous linear and nonlinear features were able to finely characterize the affective haptic perception, with a recognition accuracy of 69.79% along the force dimension, and 81.25% along the velocity dimension. PMID:27357966

  10. 16 CFR Appendix D4 to Part 305 - Water Heaters-Instantaneous-Gas

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CONGRESS ENERGY AND WATER USE LABELING FOR CONSUMER PRODUCTS UNDER THE ENERGY POLICY AND CONSERVATION ACT (âENERGY LABELING RULEâ) Pt. 305, App. D4 Appendix D4 to Part 305—Water Heaters—Instantaneous—Gas... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Water Heaters-Instantaneous-Gas D4...