Science.gov

Sample records for hybrid switched reluctance

  1. Electromagnetic Forces in a Hybrid Magnetic-Bearing Switched-Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

    2008-01-01

    Analysis and experimental measurement of the electromagnetic force loads on the hybrid rotor in a novel hybrid magnetic-bearing switched-reluctance motor (MBSRM) have been performed. A MBSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The MBSRM discussed in this report has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of four stator poles, while a second set of four stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Static torque and radial force analysis were done for rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental and the theoretical radial force loads predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

  2. Accurate modeling of switched reluctance machine based on hybrid trained WNN

    NASA Astrophysics Data System (ADS)

    Song, Shoujun; Ge, Lefei; Ma, Shaojie; Zhang, Man

    2014-04-01

    According to the strong nonlinear electromagnetic characteristics of switched reluctance machine (SRM), a novel accurate modeling method is proposed based on hybrid trained wavelet neural network (WNN) which combines improved genetic algorithm (GA) with gradient descent (GD) method to train the network. In the novel method, WNN is trained by GD method based on the initial weights obtained per improved GA optimization, and the global parallel searching capability of stochastic algorithm and local convergence speed of deterministic algorithm are combined to enhance the training accuracy, stability and speed. Based on the measured electromagnetic characteristics of a 3-phase 12/8-pole SRM, the nonlinear simulation model is built by hybrid trained WNN in Matlab. The phase current and mechanical characteristics from simulation under different working conditions meet well with those from experiments, which indicates the accuracy of the model for dynamic and static performance evaluation of SRM and verifies the effectiveness of the proposed modeling method.

  3. Accurate modeling of switched reluctance machine based on hybrid trained WNN

    SciTech Connect

    Song, Shoujun Ge, Lefei; Ma, Shaojie; Zhang, Man

    2014-04-15

    According to the strong nonlinear electromagnetic characteristics of switched reluctance machine (SRM), a novel accurate modeling method is proposed based on hybrid trained wavelet neural network (WNN) which combines improved genetic algorithm (GA) with gradient descent (GD) method to train the network. In the novel method, WNN is trained by GD method based on the initial weights obtained per improved GA optimization, and the global parallel searching capability of stochastic algorithm and local convergence speed of deterministic algorithm are combined to enhance the training accuracy, stability and speed. Based on the measured electromagnetic characteristics of a 3-phase 12/8-pole SRM, the nonlinear simulation model is built by hybrid trained WNN in Matlab. The phase current and mechanical characteristics from simulation under different working conditions meet well with those from experiments, which indicates the accuracy of the model for dynamic and static performance evaluation of SRM and verifies the effectiveness of the proposed modeling method.

  4. Analysis and comparison of end effects in linear switched reluctance and hybrid motors

    NASA Astrophysics Data System (ADS)

    Barhoumi, El Manaa; Abo-Khalil, Ahmed Galal; Berrouche, Youcef; Wurtz, Frederic

    2017-03-01

    This paper presents and discusses the longitudinal and transversal end effects which affects the propulsive force of linear motors. Generally, the modeling of linear machine considers the forces distortion due to the specific geometry of linear actuators. The insertion of permanent magnets on the stator allows improving the propulsive force produced by switched reluctance linear motors. Also, the inserted permanent magnets in the hybrid structure allow reducing considerably the ends effects observed in linear motors. The analysis was conducted using 2D and 3D finite elements method. The permanent magnet reinforces the flux produced by the winding and reorients it which allows modifying the impact of end effects. Presented simulations and discussions show the importance of this study to characterize the end effects in two different linear motors.

  5. Electromagnetic Radial Forces in a Hybrid Eight-Stator-Pole, Six-Rotor-Pole Bearingless Switched-Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

    2007-01-01

    Analysis and experimental measurement of the electromagnet force loads on the hybrid rotor in a novel bearingless switched-reluctance motor (BSRM) have been performed. A BSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The BSRM has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of stator poles. A second set of stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Analysis was done for nonrotating rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental results and the theoretical predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

  6. Improved Bearingless Switched-Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.

    2003-01-01

    The Morrison rotor, named after its inventor, is a hybrid rotor for use in a bearingless switched-reluctance electric motor. The motor is characterized as bearingless in the sense that it does not rely on conventional mechanical bearings: instead, it functions as both a magnetic bearing and a motor. Bearingless switched-reluctance motors are attractive for use in situations in which large variations in temperatures and/or other extreme conditions preclude the use of conventional electric motors and mechanical bearings. In the Morrison motor, as in a prior bearingless switched-reluctance motor, a multipole rotor is simultaneously levitated and rotated. In the prior motor, simultaneous levitation and rotation are achieved by means of two kinds of stator windings: (1) main motor windings and (2) windings that exert levitating forces on a multipole rotor. The multipole geometry is suboptimum for levitation in that it presents a discontinuous surface to the stator pole faces, thereby degrading the vibration-suppression capability of the magnetic bearing. The Morrison rotor simplifies the stator design in that the stator contains only one type of winding. The rotor is a hybrid that includes both (1) a circular lamination stack for levitation and (2) a multipole lamination stack for rotation. A prototype includes six rotor poles and eight stator poles (see figure). During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. The relative lengths of the circular and multipole lamination stacks on the rotor can be chosen to tailor the performance of the motor for a specific application. For a given overall length, increasing the length of the multipole stack relative to the circular stack results in an increase in torque relative to levitation load capacity and stiffness, and vice versa.

  7. Bearingless Switched-Reluctance Motor Improved

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.

    2004-01-01

    The Morrison rotor, named after its inventor, is a hybrid rotor for use in a switched reluctance electric motor. The motor is characterized as bearingless in the sense that it does not rely on conventional mechanical bearings: instead, it functions as both a magnetic bearing and a motor. Bearingless switched-reluctance motors are attractive for use in situations in which large variations in temperatures and/or other extreme conditions preclude the use of conventional electric motors and mechanical bearings. In the Morrison motor, as in prior bearingless switched-reluctance motors, a multipole rotor is simultaneously levitated and rotated. In the prior motors, simultaneous levitation and rotation are achieved by means of two kinds of stator windings: (1) main motor windings and (2) windings that exert levitating forces on a multipole rotor. The multipole geometry is suboptimum for levitation because it presents a discontinuous surface to the stator pole faces, thereby degrading the vibration suppression capability of the magnetic bearing. The Morrison rotor simplifies the stator design in that it contains only one type of winding. The rotor is a hybrid that includes both (1) a circular lamination stack for levitation and (2) a multipole lamination stack for rotation. Simultaneous levitation and rotation at 6000 rpm were achieved with a prototype that included six rotor poles and eight stator poles. During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. The relative length of the circular and multipole lamination stacks on the rotor can be chosen to tailor the performance of the motor for a specific application. For a given overall length, increasing the length of the multipole stack relative to the circular stack results in an increase in torque relative to the levitation

  8. The Morrison Bearingless Switched Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Wong, David S.

    2004-01-01

    Switched reluctance motors typically consist of pairs of poles protruding outward from a central rotor, surrounded by pairs of coils protruding inward from a stator. The pairs of coils, positioned a short distance from opposing sides of the rotor, are connected in series. A current runs through the coils, generating a magnetic flux between the coils. This attracts the protruding poles on the rotor, and just as the poles on the rotor approach the coils, the current to the coils is inverted, repelling the rotor s poles as they pass the coils. This current switching, back and forth, provides a continuous rotational torque to the rotor. reliability, durability, low cost, and operation in adverse environments such as high temperatures, extreme temperature variations, and high rotational speeds. However, because rotors are often manufactured with minute flaws due to imperfections in the machining process, traditional switched reluctance motors often suffer from substantial amounts of vibration. In addition, the current in the coils imparts a strong radial magnetic force on the rotor; the continuous alternating of the direction of this force also causes vibration. As a result, switched reluctance motors require bearings that, run at high speeds, can require lubrication apparatus and are subject to problems with heat and wear. My mentor s recent invention, the "Bearingless" Switched Reluctance Motor, actually uses magnetic bearings instead of traditional physical bearings. Sensors are used to continuously determine the position of the rotor. A computer reads the position sensor input, performs calculations, and outputs a current to a set of extra coils (in addition to the coils rotating the rotor). This current provides a magnetic force that counters and damps the vibration. The sense-calculate-update loop iterates more than thirty thousand times per second. For now, our goal is to have the rotor rotate at about 6000 rprn, and at that speed, the magnetic bearing is

  9. Applying Switched Reluctance Motor to Oil Hydraulic Pump Use

    NASA Astrophysics Data System (ADS)

    Yamai, Hiroyuki; Sawada, Yuzo; Ohyama, Kazunobu

    Hydraulic pump units are widely used to operate hydraulic actuators. In a typical machine shop, conventional constant speed hydraulic pump units consume more than 20% of the total electric power necessary to operate CNC machine tools. Most of that energy are wasted to run the axial piston pump at idle. This paper describes a variable speed hydraulic pump unit using a switched reluctance motor (SRM), which saves energy drastically. SRM was selected as the most suitable motor for this application. Design and control strategy of this motor are described. Application examples to machine tools shows the effectiveness of the new hybrid pump system in saving energy and in reducing acoustic noise.

  10. Reconstruction of the Switched Reluctance Motor Stator

    NASA Astrophysics Data System (ADS)

    El-Kharashi, Eyhab; Hassanien, Hany M.

    2012-01-01

    The paper re-designs the conventional 6/8 switched reluctance motor (SRM) by a particular way to minimize the losses. The flux loops are shortened by making each two stator teeth incorporated in one magnetic circuit only. Subsequently the flux does not cross in some iron parts of the stator core backs. These unused iron sections are taken off consequently the iron losses decreased. Now the stator consists of three separated sections and they are fixed inside non-magnetic cylinder. The copper losses also are decreased because less copper windings are used to produce the same amount of the output torque as the flux paths become short then the flux density increases. The analysis and comparison of the 6/8 SRM before and after the re-design process are presented. A m files Matlab software is used to simulate the dynamic performance. Then the paper proceeds to examine different control techniques to the new design. The hysteresis and PI controllers are used as classical method to control the SRM. Then the artificial neural network (ANN) is used to test the new control techniques.

  11. Switched reluctance motor systems poised for rapid growth

    SciTech Connect

    Lovins, A.B.; Howe, B.

    1992-12-31

    The emergence of a rugged, versatile, and highly efficient alternative to conventional electric motors promises to have a major impact on drivepower markets over the next decade. Although switched reluctance drives are not yet available ``off the shelf`` from major motor manufacturers, they are likely to compete favorably across a broad range of applications, due to their superior performance characteristics. Switched reluctance drives maintain higher torque and efficiency over broader speed ranges than can be achieved with other advanced variable-speed systems, can be programmed to precisely match the loads they serve and, in high-volume production, are likely to be less expensive than competing systems. The principal obstacle to rapid commercialization of switched reluctance motors is the fact that few engineers are trained to perform the exacting and specialized design that this technology requires. This hurdle is gradually being overcome as over two dozen firms now design or manufacture switched reluctance drives, and several are moving into mass production applications. As these and other firms gain experience with the technology, new opportunities will arise for utilities, energy users, and original equipment manufacturers to capture the benefits of switched reluctance motor systems. This report appraises recent progress toward moving switched reluctance drives to mass production and provides an inventory of major manufacturers.

  12. Fault tolerant operation of switched reluctance machine

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    The energy crisis and environmental challenges have driven industry towards more energy efficient solutions. With nearly 60% of electricity consumed by various electric machines in industry sector, advancement in the efficiency of the electric drive system is of vital importance. Adjustable speed drive system (ASDS) provides excellent speed regulation and dynamic performance as well as dramatically improved system efficiency compared with conventional motors without electronics drives. Industry has witnessed tremendous grow in ASDS applications not only as a driving force but also as an electric auxiliary system for replacing bulky and low efficiency auxiliary hydraulic and mechanical systems. With the vast penetration of ASDS, its fault tolerant operation capability is more widely recognized as an important feature of drive performance especially for aerospace, automotive applications and other industrial drive applications demanding high reliability. The Switched Reluctance Machine (SRM), a low cost, highly reliable electric machine with fault tolerant operation capability, has drawn substantial attention in the past three decades. Nevertheless, SRM is not free of fault. Certain faults such as converter faults, sensor faults, winding shorts, eccentricity and position sensor faults are commonly shared among all ASDS. In this dissertation, a thorough understanding of various faults and their influence on transient and steady state performance of SRM is developed via simulation and experimental study, providing necessary knowledge for fault detection and post fault management. Lumped parameter models are established for fast real time simulation and drive control. Based on the behavior of the faults, a fault detection scheme is developed for the purpose of fast and reliable fault diagnosis. In order to improve the SRM power and torque capacity under faults, the maximum torque per ampere excitation are conceptualized and validated through theoretical analysis and

  13. Prediction of Radial Vibration in Switched Reluctance Machines

    SciTech Connect

    Lin, CJ; Fahimi, B

    2013-12-01

    Origins of vibration in switched reluctance machines (SRMs) are investigated. Accordingly, an input-output model based on the mechanical impulse response of the SRMis developed. The proposed model is derived using an experimental approach. Using the proposed approach, vibration of the stator frame is captured and experimentally verified.

  14. Control Code for Bearingless Switched-Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.

    2007-01-01

    A computer program has been devised for controlling a machine that is an integral combination of magnetic bearings and a switched-reluctance motor. The motor contains an eight-pole stator and a hybrid rotor, which has both (1) a circular lamination stack for levitation and (2) a six-pole lamination stack for rotation. The program computes drive and levitation currents for the stator windings with real-time feedback control. During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. This version is executable in a control-loop time of 40 s on a Pentium (or equivalent) processor that operates at a clock speed of 400 MHz. The program can be expanded, by addition of logic blocks, to enable control of position along additional axes. The code enables adjustment of operational parameters (e.g., motor speed and stiffness, and damping parameters of magnetic bearings) through computer keyboard key presses.

  15. A Microprocessor Control Scheme For Switched Reluctance Motor Drives

    NASA Astrophysics Data System (ADS)

    Oza, A. R.; Krishnan, R.; Adkar, S.

    1987-10-01

    A microprocessor control scheme for a switched reluctance motor(SRM) drive is discussed. A SRM is inherently a variable speed machine since it requires a converter even for constant speed running. Starting with a conceptual development, a particular hardware scheme is discussed for controller implementation. Hardware-software tradeoffs incorporated in the design are discussed. Some results of an actual system are evaluated. It is shown that a microprocessor controller has many advantages over conventional controllers. The controller design uses rotor position and speed feedbacks. Self-starting is incorporated into the design. Use of off-the-shelf components makes the controller simple, reliable, and economical.

  16. Prediction of Acoustic Noise in Switched Reluctance Motor Drives

    SciTech Connect

    Lin, CJ; Fahimi, B

    2014-03-01

    Prediction of acoustic noise distribution generated by electric machines has become an integral part of design and control in noise sensitive applications. This paper presents a fast and precise acoustic noise imaging technique for switched reluctance machines (SRMs). This method is based on distribution of radial vibration in the stator frame of the SRM. Radial vibration of the stator frame, at a network of probing points, is computed using input phase current and phase voltage waveforms. Sequentially, the acceleration of the probing network will be expanded to predict full acceleration on the stator frame surface, using which acoustic noise emission caused by the stator can be calculated using the boundary element method.

  17. Computer aided design of multi-phase switched reluctance motor

    NASA Astrophysics Data System (ADS)

    Sheth, N. K.; Rajagopal, K. R.

    2005-05-01

    In this paper, a comprehensive computer-aided design (CAD) procedure of multiphase switched reluctance motor (SRM) is presented. Better approach for calculation of the outer dimensions, phase inductance, flux linkage and losses, and also a different concept for calculating the average torque of the motor are incorporated in the CAD program. The average torque is calculated based on the most effective 15° (for 8/6 SRM) of the static torque profile of the motor. A sample design of a 5hp SRM is presented in detail and the design is validated by conducting a two-dimensional finite element analysis of the motor.

  18. A non linear analytical model of switched reluctance machines

    NASA Astrophysics Data System (ADS)

    Sofiane, Y.; Tounzi, A.; Piriou, F.

    2002-06-01

    Nowadays, the switched reluctance machine are widely used. To determine their performances and to elaborate control strategy, we generally use the linear analytical model. Unhappily, this last is not very accurate. To yield accurate modelling results, we use then numerical models based on either 2D or 3D Finite Element Method. However, this approach is very expensive in terms of computation time and remains suitable to study the behaviour of eventually a whole device. However, it is not, a priori, adapted to elaborate control strategy for electrical machines. This paper deals with a non linear analytical model in terms of variable inductances. The theoretical development of the proposed model is introduced. Then, the model is applied to study the behaviour of a whole controlled switched reluctance machine. The parameters of the structure are identified from a 2D numerical model. They can also be determined from an experimental bench. Then, the results given by the proposed model are compared to those issue from the 2D-FEM approach and from the classical linear analytical model.

  19. Finite element analysis and performance study of switched reluctance generator

    NASA Astrophysics Data System (ADS)

    Zhang, Qianhan; Guo, Yingjun; Xu, Qi; Yu, Xiaoying; Guo, Yajie

    2017-03-01

    Analyses a three-phase 12/8 switched reluctance generator (SRG) which is based on its structure and performance principle. The initial size data were calculated by MathCAD, and the simulation model was set up in the ANSOFT software environment with the maximum efficiency and the maximum output power as the main reference parameters. The outer diameter of the stator and the inner diameter of the rotor were parameterized. The static magnetic field distribution, magnetic flux, magnetic energy, torque, inductance characteristics, back electromotive force and phase current waveform of SRG is obtained by analyzing the static magnetic field and the steady state motion of two-dimensional transient magnetic field in ANSOFT environment. Finally, the experimental data of the prototype are compared with the simulation results, which provide a reliable basis for the design and research of SRG wind turbine system.

  20. Development of a Switched Reluctance Motor made of Permendur

    NASA Astrophysics Data System (ADS)

    Hasegawa, Y.; Nakamura, K.; Ichinokura, O.

    2011-01-01

    A switched reluctance (SR) motor consists of stator and rotor cores, and windings. Both the stator and rotor have salient poles. The stator has concentrated windings on each salient pole. On the other hand, the rotor has no windings and no permanent magnets. Therefore, the SR motor is a low cost, extremely robust, and wide-range variable-speed motor. The performance of the SR motor greatly depends on magnetic properties of core material since it consists of only iron cores and windings. This paper presents the development of a novel SR motor made of permendur which has extremely high saturation flux density and very low core loss. Two types of SR motors, one is made of conventional non-oriented Si steel, the other is made of permendur, are compared by simulation and experiment. It is demonstrated that the torque of the SR motor made of permendur is greater than that of the conventional Si steel by 20%.

  1. A Study on Temperature Analysis of Switched Reluctance Motor

    NASA Astrophysics Data System (ADS)

    Inamura, Shingo; Sawa, Koichiro

    This paper describes the temperature analysis of a Switched Reluctance Motor (SRM) taking into account the temperature rise in the inside air. The temperature of motor will be known to be important for motor design, because the rated values such as voltage, current, and output considerably depend on it. Moreover the temperature rise affects the magnetic characteristics of material e.g. permanent magnet, electrical steel sheets.In this paper, we introduced the equation of temperature rise in the inside air which includes the heat convection to the iron and the outside air for analysis. Finite Element Method (FEM) was combined with it and solved simultaneously by iterative method. In comparison with measured value, it is clear that the model of the temperature rise is effective for highly accurate analysis.Furthermore, the distribution of temperature in SRM is obtained, which makes it possible to estimate the local heat generation.

  2. Personal Computer Based Controller For Switched Reluctance Motor Drives

    NASA Astrophysics Data System (ADS)

    Mang, X.; Krishnan, R.; Adkar, S.; Chandramouli, G.

    1987-10-01

    Th9, switched reluctance motor (SRM) has recently gained considerable attention in the variable speed drive market. Two important factors that have contributed to this are, the simplicity of construction and the possibility of developing low cost con-trollers with minimum number of switching devices in the drive circuits. This is mainly due to the state-of-art of the present digital circuits technology and the low cost of switching devices. The control of this motor drive is under research. Optimized performance of the SRM motor drive is very dependent on the integration of the controller, converter and the motor. This research on system integration involves considerable changes in the control algorithms and their implementation. A Personal computer (PC) based controller is very appropriate for this purpose. Accordingly, the present paper is concerned with the design of a PC based controller for a SRM. The PC allows for real-time microprocessor control with the possibility of on-line system parameter modifications. Software reconfiguration of this controller is easier than a hardware based controller. User friendliness is a natural consequence of such a system. Considering the low cost of PCs, this controller will offer an excellent cost-effective means of studying the control strategies for the SRM drive intop greater detail than in the past.

  3. High-Temperature Switched-Reluctance Electric Motor

    NASA Technical Reports Server (NTRS)

    Montague, Gerald; Brown, Gerald; Morrison, Carlos; Provenza, Andy; Kascak, Albert; Palazzolo, Alan

    2003-01-01

    An eight-pole radial magnetic bearing has been modified into a switched-reluctance electric motor capable of operating at a speed as high as 8,000 rpm at a temperature as high as 1,000 F (=540 C). The motor (see figure) is an experimental prototype of starter-motor/generator units that have been proposed to be incorporated into advanced gas turbine engines and that could operate without need for lubrication or active cooling. The unique features of this motor are its electromagnet coils and, to some extent, its control software. Heretofore, there has been no commercial-off-the-shelf wire capable of satisfying all of the requirements for fabrication of electromagnet coils capable of operation at temperatures up to 1,000 F (=540 C). The issues addressed in the development of these electromagnet coils included thermal expansion, oxidation, pliability to small bend radii, micro-fretting, dielectric breakdown, tensile strength, potting compound, thermal conduction, and packing factor. For a test, the motor was supported, along with a rotor of 18 lb (.8-kg) mass, 3-in. (.7.6-cm) diameter, 21-in. (.53-cm) length, on bearings packed with high-temperature grease. The motor was located at the mid span of the rotor and wrapped with heaters. The motor stator was instrumented with thermocouples. At the time of reporting the information for this article, the motor had undergone 14 thermal cycles between room temperature and 1,000 F (.540 C) and had accumulated operating time >27.5 hours at 1,000 F (=540 C). The motor-controller hardware includes a personal computer equipped with analog-to-digital input and digital-to-analog output cards. The controller software is a C-language code that implements a switched-reluctance motor-control principle: that is, it causes the coils to be energized in a sequence timed to generate a rotating magnetic flux that creates a torque on a scalloped rotor. The controller can operate in an open- or closed-loop mode. In addition, the software has

  4. Rotor Losses in a Switched Reluctance Motor - Analysis and Reduction Methods

    NASA Astrophysics Data System (ADS)

    Schweighofer, B.; Recheis, M.; Fulmek, P.; Wegleiter, H.

    2013-01-01

    Due to the increasing hybridization and electrification of vehicles, flywheel energy storage devices are an important area of research. In automotive application besides the weight criteria, some additionally constrains, such as size, efficiency and especially cost have to be fulfilled. Therefore typically a compact design, in which the rotor of the needed electrical machine simultaneously acts as storage mass is chosen. Since the machine is running in vacuum and the rotor can dissipate its heat only by means of thermal radiation or through the bearings if conventional bearings are used, the rotor losses play a vital role. In this work the rotor losses of a switched reluctance machine are analyzed in detail and a method to reduce the rotor losses is proposed.

  5. Experimental Manufacture and Performance Evaluation of Linear Switched Reluctance Motor with HTS Excitation Windings

    NASA Astrophysics Data System (ADS)

    Hirayama, Tadashi; Oto, Satoshi; Higashijima, Atsushi; Kawabata, Shuma

    This paper presents an experimental manufacture and performance evaluation of prototype linear switched reluctance motor with HTS excitation windings (HTS-LSRM). The Ag-alloy sheathed Bi-2223 tapes are used for HTS coils. We first present a structure of the prototype HTS-LSRM. Next, current-carrying properties of the HTS coils are measured. Furthermore, current and voltage waveforms are measured and we evaluation a control performance of the current and voltage.

  6. Research on Electromagnetic Force Distribution and Vibration Performance of A Novel 10/4 Switched Reluctance Motor

    NASA Astrophysics Data System (ADS)

    Fu, Ziyu; Wang, Xinyu; Cao, Cheng; Liu, Meng; Wang, Kangxi

    2017-06-01

    Radial electromagnetic force is one of the main reasons causing the vibration and noise of the switched reluctance motor. Based on this, the novel structure of 10/4 pole switched reluctance motor is proposed, which increases the air gap flux and electromagnetic torque by increasing the number of stator poles. In addition, the excitation current of the stator winding is reduced by early turn-off angle. Through the finite element modelling analysis, the results show the superiority of the new type of switched reluctance motor. In the end, the vibration characteristics of the conventional motor and the new motor are compared and analysed, and the effect of the structure of this new type of switched reluctance motor is verified.

  7. Control system of mutually coupled switched reluctance motor drive of mining machines in generator mode

    NASA Astrophysics Data System (ADS)

    Ivanov, A. S.; Kalanchin, I. Yu; Pugacheva, E. E.

    2017-09-01

    One of the first electric motors, based on the use of electromagnets, was a reluctance motor in the XIX century. Due to the complexities in the implementation of control system the development of switched reluctance electric machines was repeatedly initiated only in 1960 thanks to the development of computers and power electronic devices. The main feature of these machines is the capacity to work both in engine mode and in generator mode. Thanks to a simple and reliable design in which there is no winding of the rotor, commutator, permanent magnets, a reactive gate-inductor electric drive operating in the engine mode is actively being introduced into various areas such as car industry, production of household appliances, wind power engineering, as well as responsible production processes in the oil and mining industries. However, the existing shortcomings of switched reluctance electric machines, such as nonlinear pulsations of electromagnetic moment, the presence of three or four phase supply system and sensor of rotor position prevent wide distribution of this kind of electric machines.

  8. A new two-phase homopolar switched reluctance motor for electric vehicle applications

    NASA Astrophysics Data System (ADS)

    Tsai, Mi-Ching; Huang, Chien-Chin; Huang, Zheng-Yi

    2003-12-01

    This paper presents a novel 2-phase homopolar switched reluctance motor (SRM), whose design successfully avoids dead-zone problems that afflict low cost 1- and/or 2-phase SRMs. Unlike conventional radial-winding-radial-gap motors, the proposed SRM has an interior stator that is of the pancake type with axial winding. Such a design allows for a high slot-fill factor and is suitable for implementation as a flat pancake-shaped stator. An efficient, compact prototype was produced with TMS320F240 DSP driving control unit. Experimental results indicate that the present SRM design has the potential to be used for electric bicycles and scooters.

  9. Inductance and Active Phase Vector Based Torque Control for Switched Reluctance Motor Drives.

    NASA Astrophysics Data System (ADS)

    Kalpathi, Ramani Raman

    The Switched Reluctance Motor (SRM) drive technology has developed significantly over the last few years. The simplicity in both motor design and power converter requirement along with the availability of high frequency, high power semiconductor switches have made SRMs compete with conventional adjustable speed drive technologies. The subject of winding current control in switched reluctance machines has always been associated with the shaft position information. The use of inductance for direct commutation control is the central subject of this dissertation. In contrast to the conventional methods based on position commutation, new methods of control based on inductance commutation are presented. The object of a commutation algorithm is to switch the currents in the phase coils, in order to provide continuous energy conversion with maximum torque output for a given unit of input current. Since torque production in a SRM is based on the concept of variable reluctance, it makes more sense to observe the instantaneous phase inductance or reluctance instead of estimating the rotor position. The inductance sensors observe the machine parameters and provide sufficient information on the electrical characteristics of the coils. This control strategy avoids the inductance to position transformation blocks conventionally used in SRM control systems. In a typical SRM, the phase coils have a nonlinear behavior of inductance due to effects of current saturation. Also the parameters of one phase coil differ from those of the other due to manufacturing tolerances or due to bearing wear. In such cases, the algorithms written during the stage of manufacturing may not be valid after parameter changes. Optimizing torque production in the event of phase asymmetry and saturation is developed in this research. Indirect sensors connected to the active phase coil of the SRM are based on sensing the flux level in the active coil. New commutation algorithms based on flux sensing concepts

  10. Position Estimation for Switched Reluctance Motor Based on the Single Threshold Angle

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Li, Pang; Yu, Yue

    2017-05-01

    This paper presents a position estimate model of switched reluctance motor based on the single threshold angle. In view of the relationship of between the inductance and rotor position, the position is estimated by comparing the real-time dynamic flux linkage with the threshold angle position flux linkage (7.5° threshold angle, 12/8SRM). The sensorless model is built by Maltab/Simulink, the simulation are implemented under the steady state and transient state different condition, and verified its validity and feasibility of the method..

  11. Steady State Analysis Of The Variable Speed Switched Reluctance Motor Drive

    NASA Astrophysics Data System (ADS)

    Materu, P.; Krishnan, R.; Farzanehfard, H.

    1987-10-01

    The switched reluctance motor (SRM) drive has recently received attention mainly because of its simple motor construction and unidirectional converter requirement. The principle of operation of the motor drive demands that the motor and converter be treated as one unit. Little has been done to develop a complete analysis of this motor-converter combination 1'2. This paper presents an approach to the steady state analysis of the SRM drive including the effects of stator winding resistance, input filter dynamics and snubber circuits which are often neglected. The analysis yields phase current waveforms providing guidelines to the optimal design of the converter and motor. A novel single-switch-per phase converter developed by one of the authors is used. The approach can be used for any other motor-converter combination.

  12. Formation of failure matrix and failure-free control algorithm for multi-sectioned Switched-reluctance drive

    NASA Astrophysics Data System (ADS)

    Odnokopylov, G.; Rozayev, I.

    2014-10-01

    We review fault-tolerant switched reluctance drive with sectioning of the three-phase stator winding. In the operating process of an electric drive, there will be continuous monitoring of the operating state on the basis of a developed algorithm to analyse drive operability and formation tabulate a failure matrix. The paper introduces a failure-free control algorithm for multi-section switch - reluctance motor with formation the assignment values of amplitude phase currents taking into account the failure matrix. We show that in an emergency such single failure or multiple failure in switched-reluctance drive it is possible to provide reduction of torque fall and pro-gressively stock depletion with providing fault-tolerance of drive system. A method of residual life evaluation is proposed on the basis of calculating the coefficient of operability of the electric drive system that gives possibility to control the endurance of electric drive in real time from operational to completely unusable.

  13. A Bearingless Switched-Reluctance Motor for High Specific Power Applications

    NASA Technical Reports Server (NTRS)

    Choi, Benjamin B.; Siebert, Mark

    2006-01-01

    A 12-8 switched-reluctance motor (SRM) is studied in bearingless (or self-levitated) operation with coil currents limited to the linear region to avoid magnetic saturation. The required motoring and levitating currents are summed and go into a single motor coil per pole to obtain the highest power output of the motor by having more space for motor coil winding. Two controllers are investigated for the bearingless SRM operation. First, a model-based controller using the radial force, which is adjusted by a factor derived from finite element analysis, is presented. Then a simple and practical observation-based controller using a PD (proportional-derivative) control algorithm is presented. Both controllers were experimentally demonstrated to 6500 rpm. This paper reports the initial efforts toward eventual self levitation of a SRM operating into strong magnetic core saturation at liquid nitrogen temperature.

  14. An inductance Fourier decomposition-based current-hysteresis control strategy for switched reluctance motors

    NASA Astrophysics Data System (ADS)

    Hua, Wei; Qi, Ji; Jia, Meng

    2017-05-01

    Switched reluctance machines (SRMs) have attracted extensive attentions due to the inherent advantages, including simple and robust structure, low cost, excellent fault-tolerance and wide speed range, etc. However, one of the bottlenecks limiting the SRMs for further applications is its unfavorable torque ripple, and consequently noise and vibration due to the unique doubly-salient structure and pulse-current-based power supply method. In this paper, an inductance Fourier decomposition-based current-hysteresis-control (IFD-CHC) strategy is proposed to reduce torque ripple of SRMs. After obtaining a nonlinear inductance-current-position model based Fourier decomposition, reference currents can be calculated by reference torque and the derived inductance model. Both the simulations and experimental results confirm the effectiveness of the proposed strategy.

  15. Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

    NASA Astrophysics Data System (ADS)

    Millithaler, Pierre; Dupont, Jean-Baptiste; Ouisse, Morvan; Sadoulet-Reboul, Émeline; Bouhaddi, Noureddine

    2017-10-01

    Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers.

  16. Modeling and controller performance assessment for a switched reluctance motor drive based on setpoint relay.

    PubMed

    dos Reis, L L N; Coelho, A A R; Almeida, O M; Campos, J C T

    2009-04-01

    This paper considers the implementation of a current control method for switched reluctance motors (SRMs) and presents a novel approach to the accurate on-line modeling of an SRM drive. A simple autotuning technique for the SRM drives using a PWM controller is considered. Furthermore, conventional PI control and Internal Model Control (IMC) are considered to validate this method and present corresponding robust control analysis for the process. The control structures are comparatively analyzed using standard robustness measures for stability and performance. The proposed PWM controller is simulated and a hardware prototype is then implemented using digital signal processor control to evaluate the method using a 12/8, three-phase SRM. The experimental results of the SRM drive model validates the performance of the current loop.

  17. Optimal design of switched reluctance motor using two-dimensional finite element method

    NASA Astrophysics Data System (ADS)

    Kim, Youn-Hyun; Choi, Jae-Hak; Jung, Sung-In; Chun, Yon-Do; Kim, Sol; Lee, Ju; Chu, Min-Sik; Hong, Kyung-Jin; Choi, Dong-Hoon

    2002-05-01

    Switched reluctance motor (SRM) has some advantages such as low cost, high torque density, etc., but SRM has essentially high torque ripple due to its salient structure. To apply SRM to the industrial field, we have to minimize torque ripple, which is the weak point of SRM. This article introduces optimal design process of SRM using a numerical method such as two-dimensional (2D) finite element method. The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, we can obtain the optimal design, which minimizes the torque ripple. We also can obtain the optimal design, which maximizes the average torque. Finally, this article presents performance comparison of two optimal designs, the minimized torque ripple, and the maximized average torque.

  18. Sensorless control for switched reluctance motor based on special position detection.

    PubMed

    Shao, Jie; Deng, Zhiquan; Gu, Yu

    2017-09-01

    This paper proposes a new sensorless control approach for switched reluctance motor (SRM) in the single pulse control mode in high speed operation. The sensorless method uses the cross point position of transformer electromotive force (EMF) and motional back electromotive force (BEMF) to estimate the rotor position. The cross point position can be derived from the inductance model of SRM, and it is regarded as reference position. The rotor position can be calculated by detecting the special position for each electrical cycle. The proposed position estimation method is not affected by the magnetic saturation of SRM. Importantly, no additional hardware and no complicated computation or memory storage are required with the proposed method. Finally, the simulation and experimental results on a three-phase 12/8-pole SRM demonstrate the validity of the proposed sensorless scheme. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  19. Performance analysis of photovoltaic-powered water-pumping systems using switched reluctance motor drives

    NASA Astrophysics Data System (ADS)

    Metwally, Hamid M. B.; Anis, Wagdy R.

    A photovoltaic-powered (PV) pumping system that uses a switched reluctance motor (SRM) is investigated. The motor is supplied by a d.c. voltage through a switching circuit. The drive circuit is much simpler than the normal d.c./a.c. inverter that is required to supply the induction motor. The efficiency of the SRM is considerably higher than that of equivalent d.c. or induction motors. In addition, because of the simple construction, the SRM is cheaper. By virtue of these advantages of the SRM, the proposed system has higher efficiency and lower cost compared with other systems. A design example is studied in detail to explore the advantages of PV pumping systems based on this new drive. It is found that the operating efficiency of the motor is about 85% during most of its working time. The matching efficiency between the PV array and the proposed system approaches 95%. The major part of the losses takes place in the pump and the riser pipes; this loss represents one-third of the total available energy.

  20. An Improved Model Predictive Current Controller of Switched Reluctance Machines Using Time-Multiplexed Current Sensor

    PubMed Central

    Li, Bingchu; Ling, Xiao; Huang, Yixiang; Gong, Liang; Liu, Chengliang

    2017-01-01

    This paper presents a fixed-switching-frequency model predictive current controller using multiplexed current sensor for switched reluctance machine (SRM) drives. The converter was modified to distinguish currents from simultaneously excited phases during the sampling period. The only current sensor installed in the converter was time division multiplexing for phase current sampling. During the commutation stage, the control steps of adjacent phases were shifted so that sampling time was staggered. The maximum and minimum duty ratio of pulse width modulation (PWM) was limited to keep enough sampling time for analog-to-digital (A/D) conversion. Current sensor multiplexing was realized without complex adjustment of either driver circuit nor control algorithms, while it helps to reduce the cost and errors introduced in current sampling due to inconsistency between sensors. The proposed controller is validated by both simulation and experimental results with a 1.5 kW three-phase 12/8 SRM. Satisfied current sampling is received with little difference compared with independent phase current sensors for each phase. The proposed controller tracks the reference current profile as accurately as the model predictive current controller with independent phase current sensors, while having minor tracking errors compared with a hysteresis current controller. PMID:28513554

  1. An Improved Model Predictive Current Controller of Switched Reluctance Machines Using Time-Multiplexed Current Sensor.

    PubMed

    Li, Bingchu; Ling, Xiao; Huang, Yixiang; Gong, Liang; Liu, Chengliang

    2017-05-17

    This paper presents a fixed-switching-frequency model predictive current controller using multiplexed current sensor for switched reluctance machine (SRM) drives. The converter was modified to distinguish currents from simultaneously excited phases during the sampling period. The only current sensor installed in the converter was time division multiplexing for phase current sampling. During the commutation stage, the control steps of adjacent phases were shifted so that sampling time was staggered. The maximum and minimum duty ratio of pulse width modulation (PWM) was limited to keep enough sampling time for analog-to-digital (A/D) conversion. Current sensor multiplexing was realized without complex adjustment of either driver circuit nor control algorithms, while it helps to reduce the cost and errors introduced in current sampling due to inconsistency between sensors. The proposed controller is validated by both simulation and experimental results with a 1.5 kW three-phase 12/8 SRM. Satisfied current sampling is received with little difference compared with independent phase current sensors for each phase. The proposed controller tracks the reference current profile as accurately as the model predictive current controller with independent phase current sensors, while having minor tracking errors compared with a hysteresis current controller.

  2. Hybrid switch for resonant power converters

    DOEpatents

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  3. Hybrid solid state switch replaces motor- driven power switch

    NASA Technical Reports Server (NTRS)

    Booth, R. A.; Schloss, A. I.

    1967-01-01

    Hybrid solid state switch replaces existing motor-driven power switches used on spacecraft. It uses a transistor circuit to limit the open circuit voltage and allow small relay contacts to handle high transient currents at reasonable cycle life.

  4. Simplified Evaluation Method of Drive Characteristics for Computer-Aided Design of Switched Reluctance Motors

    NASA Astrophysics Data System (ADS)

    Kano, Yoshiaki; Fubuki, Shingo; Kosaka, Takashi; Matsui, Nobuyuki

    Since Switched Reluctance Motors (SRM) have simple and rugged construction, they are suitable for low-cost variable speed drives in many industrial applications. However, it is rather difficult to design the motor and to predict the drive performance because of high magnetic non-linearity of the motors. Although FEM is useful for the SRM design, one of disadvantages is a long computation time. This paper proposes a simplified and fast evaluation method of the drive characteristics of SRM whose dimensions are given. The proposed method is composed of an analytical expression of magnetizing curvebased modeling approach and a simple non-linear magnetic analysis. At first, the comparative studies using 12/8 SRM show that the calculated current waveform and stiffness characteristic of the proposed modeling approach are in good agreement with those of experiment. Secondly, it is shown that the proposed magnetic analysis provides accurate and extremely fast magnetizing curves computation for the given motor dimensions compared to 3D-FEM. From the standpoints of analytical accuracy and the required computation time, the effectiveness of the proposed method is verified through the comparisons with 3D-FEM using two SRMs with different specifications.

  5. Collaborative Tracking Control of Dual Linear Switched Reluctance Machines Over Communication Network With Time Delays.

    PubMed

    Qiu, Li; Shi, Yang; Pan, Jianfei; Zhang, Bo; Xu, Gang

    2016-10-11

    This paper investigates the collaborative tracking control for dual linear switched reluctance machines (LSRMs) over a communication network with random time delays. Considering the spatio-temporal constraint relationship of the dual LSRMs in complex industrial processes, the collaborative tracking control scheme is proposed based on the networked motion control method. The stability conditions and the controller design method for the networked dual LSRMs are obtained from the two motors relative position error by using Lyapunov theory and delay systems approach. Four different allocation schemes combined with two kinds of external control signals are applied onto the collaborative tracking control experiment platform of the dual LSRMs to validate the effectiveness of the proposed method. The maximum steady-state relative position error within 0.104 mm can be achieved under the constant absolute position reference input signal of 3 mm, and the maximum absolute relative position error within ±0.46 mm can be achieved under the sinusoidal reference of 8 mm amplitude and 0.2 Hz.

  6. Prediction and measurement of heat transfer in a switched reluctance generator

    NASA Astrophysics Data System (ADS)

    Himes, Marvin Eugene, Jr.

    This research is an experimental investigation of the convective film coefficients on the unique pole faces of a high speed rotor operating within a generator. The specific geometry studied is that of a switched reluctance generator under development by the United States Air Force for use on jet aircraft as an integrated power unit (IPU) to provide auxiliary and emergency power to the aircraft's electrical system. The generator consists of a four pole rotor, nominally 4.30 inches in diameter, housed within a stator assembly. The clearance gap between the rotor pole tip and the stator wall is nominally 0.020 inches. The rotor is designed to rotate at 55,000 rpm. Rotor cooling is achieved by convection to air flowing axially through the rotor cavities. The convective film coefficient for each unique pole face, as well as an overall film coefficient for the four pole faces are inferred from the rate at which insulated test rates cool when subjected to various rates of rotor rotational speed and axial airflows. The high velocity of the rotor tips in close proximity to the stator wall results in aerodynamic heating of the air in the gap region. Convective film coefficients associated with high speed flow must be referenced to the adiabatic wall temperature to account for the effects of viscous heating. An estimate of the adiabatic wall temperature in the rotor gap region is developed analytically starting with the fundamental case of high-speed, wall-driven flow. These analytical results for wall-driven flow are verified experimentally using a smooth poled rotor. The analytically predicted film coefficients are within 10% of the experimental results. Experiments are conducted for rotor speeds ranging from 5,000 to 30,000 rpm and axial airflows ranging from 0.036 to 0.073 kg/s (0.08 to 0.16 lbm/s). The convective film coefficients for each pole face as well as average values representing heat loss from the combined faces are presented in terms of Stanton and Nusselt

  7. An approach to selecting the optimal sensing coil configuration structure for switched reluctance motor rotor position measurement

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Deng, Zhiquan

    2015-02-01

    Accurate rotor position signal is highly required for controlling the switched reluctance motor (SRM). The use of galvanic isolated sensing coils can provide independent circuit for position estimation without affecting the SRM actuation. However, the cross-coupling between main winding and sensing coil, and the mutual coupling between adjacent phase sensing coils may affect the position estimation performance seriously. In this paper, three sensing coil configurations in a 12/8 structure SRM are analyzed and compared for selecting an optimal configuration that can effectively minimize the bad effects of the cross-coupling factors. The finite element analysis and experimental results are provided for verification.

  8. Position error compensation via a variable reluctance sensor applied to a Hybrid Vehicle Electric machine.

    PubMed

    Bucak, Ihsan Ömür

    2010-01-01

    In the automotive industry, electromagnetic variable reluctance (VR) sensors have been extensively used to measure engine position and speed through a toothed wheel mounted on the crankshaft. In this work, an application that already uses the VR sensing unit for engine and/or transmission has been chosen to infer, this time, the indirect position of the electric machine in a parallel Hybrid Electric Vehicle (HEV) system. A VR sensor has been chosen to correct the position of the electric machine, mainly because it may still become critical in the operation of HEVs to avoid possible vehicle failures during the start-up and on-the-road, especially when the machine is used with an internal combustion engine. The proposed method uses Chi-square test and is adaptive in a sense that it derives the compensation factors during the shaft operation and updates them in a timely fashion.

  9. Position Error Compensation via a Variable Reluctance Sensor Applied to a Hybrid Vehicle Electric Machine

    PubMed Central

    Bucak, İhsan Ömür

    2010-01-01

    In the automotive industry, electromagnetic variable reluctance (VR) sensors have been extensively used to measure engine position and speed through a toothed wheel mounted on the crankshaft. In this work, an application that already uses the VR sensing unit for engine and/or transmission has been chosen to infer, this time, the indirect position of the electric machine in a parallel Hybrid Electric Vehicle (HEV) system. A VR sensor has been chosen to correct the position of the electric machine, mainly because it may still become critical in the operation of HEVs to avoid possible vehicle failures during the start-up and on-the-road, especially when the machine is used with an internal combustion engine. The proposed method uses Chi-square test and is adaptive in a sense that it derives the compensation factors during the shaft operation and updates them in a timely fashion. PMID:22294906

  10. Loading characteristic and optimum switching conditions of multistack variable reluctance type stepping motors

    NASA Astrophysics Data System (ADS)

    Rahman, M. F.; Bell, R.

    1984-02-01

    This paper deals with the relationship between the angular positional error of the rotor of a multistack variable reluctance type stepping motor and the average motor torque at various operating speeds. The relationships have been established theoretically using a linear model and experimentally using a lag measuring circuit over the slewing range of stepping rates. With the help of this approach the dynamic performance of this type of steppers has been studied and its limits defined.

  11. High-performance prediction for variable-speed switched reluctance drives

    SciTech Connect

    Ismail, F.; Wahsh, S.; Mohamed, A.Z.

    1997-12-31

    This work presents a simple developed nonlinear dynamic model of variable reluctance motor (VRM) based on its magnetic characteristics, considering the saturation effect. Most preliminary design work is centered on a fixed speed, or a small number of fixed speeds, even when the requirement is for operation over a wide speed range. This work deals with both constant and variable speed operation. Model development is motivated by the good performance predictions required to support and simplify the design of a high performance controller. Because the magnetization curves do not need to be pre-calculated, measured, stored, curve-fitted, or idealized the model is extremely simple, fast, and accurate. Simulation results of the phase current and torque on both chopping and single-pulse mode of operations are presented.

  12. A novel approach to controlling the phase angle of a variable switched reluctance motor for electric vehicle propulsion using the statistic matrix norm

    SciTech Connect

    Holling, G.H.

    1994-12-31

    Variable switched reluctance (VSR) motors are gaining importance for industrial applications. The paper will introduce a novel approach to simplify the computation involved in the control of VSR motors. Results are shown, that validate the approach and demonstrates the superior performance compared to tabulated control parameters with linear interpolation, which are widely used in implementations.

  13. An Intelligent Sensor Array Distributed System for Vibration Analysis and Acoustic Noise Characterization of a Linear Switched Reluctance Actuator

    PubMed Central

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications. PMID:22969364

  14. Detailed design of a 30-kW switched reluctance starter/generator system for a gas turbine engine application

    SciTech Connect

    Ferreira, C.A.; Jones, S.R.; Heglund, W.S.; Jones, W.D.

    1995-05-01

    A new switched reluctance starter/generator (SR S/G) system has been developed for an aircraft engine application. The system is rated at 30 kW, 270 Vdc, 52 k r/min maximum operating speed. The system also provides 17 hp to start the 1,400-hp engine. The system consists of an SR machine directly coupled to the gas turbine engine, an inverter converter unit (ICU), and an electronic controller. The system is designed to meet requirements such as power quality per MIL-STD-704E, 300% (9 kW) step loads, 75% constant power loads, operation over a wide speed range, and a {minus}51 C to +125 C environment. This paper focuses on the design and implementation of the system. The SR S/G system is currently undergoing design assurance tests. Test results are given to validate the system design and performance. System efficiency is about 80% when generating 30 kW.

  15. An intelligent sensor array distributed system for vibration analysis and acoustic noise characterization of a linear switched reluctance actuator.

    PubMed

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications.

  16. Comparison of channel assignment techniques for hybrid switching

    NASA Technical Reports Server (NTRS)

    Schwartz, M.; Kraimeche, B.

    1982-01-01

    The performance of four circuit-switched channel assignment strategies for use in a hybrid switch accommodating multiple users is analyzed and compared. Each scheme is associated with a fixed frame movable boundary TDM channel that multiplexes circuit-switched (CS) and packet-switched (PS) traffic. The performance measures used are blocking probability for the circuit-switched traffic and time delay for the packet-switched traffic.

  17. A hybrid electromechanical solid state switch for ac power control

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Bidirectional thyristor coupled to a series of actuator driven electromechanical contacts generates hybrid electromechanical solid state switch for ac power control. Device is useful in power control applications where zero crossover switching is required.

  18. Design comparison of single phase outer and inner-rotor hybrid excitation flux switching motor for hybrid electric vehicles

    NASA Astrophysics Data System (ADS)

    Mazlan, Mohamed Mubin Aizat; Sulaiman, Erwan; Husin, Zhafir Aizat; Othman, Syed Muhammad Naufal Syed; Khan, Faisal

    2015-05-01

    In hybrid excitation machines (HEMs), there are two main flux sources which are permanent magnet (PM) and field excitation coil (FEC). These HEMs have better features when compared with the interior permanent magnet synchronous machines (IPMSM) used in conventional hybrid electric vehicles (HEVs). Since all flux sources including PM, FEC and armature coils are located on the stator core, the rotor becomes a single piece structure similar with switch reluctance machine (SRM). The combined flux generated by PM and FEC established more excitation fluxes that are required to produce much higher torque of the motor. In addition, variable DC FEC can control the flux capabilities of the motor, thus the machine can be applied for high-speed motor drive system. In this paper, the comparisons of single-phase 8S-4P outer and inner rotor hybrid excitation flux switching machine (HEFSM) are presented. Initially, design procedures of the HEFSM including parts drawing, materials and conditions setting, and properties setting are explained. Flux comparisons analysis is performed to investigate the flux capabilities at various current densities. Then the flux linkages of PM with DC FEC of various DC FEC current densities are examined. Finally torque performances are analyzed at various armature and FEC current densities for both designs. As a result, the outer-rotor HEFSM has higher flux linkage of PM with DC FEC and higher average torque of approximately 10% when compared with inner-rotor HEFSM.

  19. Characteristic analysis of a less-rare-earth hybrid PM-assisted synchronous reluctance motor for EVs application

    NASA Astrophysics Data System (ADS)

    Wu, Wenye; Zhu, Xiaoyong; Quan, Li; Fan, Deyang; Xiang, Zixuan

    2017-05-01

    Low-energy permanent magnet (PM) such as ferrite is usually adopted in a PM-assisted reluctance (PMAREL) motor to enhance the output torque and reduce costs. However, the relatively low magnetic energy product and remanence in such PMs may lead to the risk of demagnetization. By using two types of materials of rare-earth NdFeB and non-rare-earth ferrite PM, a new less-rare-earth hybrid PMAREL motor is proposed in this paper, where the output torque and the power factor can be improved obviously, and meanwhile the risk of irreversible demagnetization in ferrite PMs can be reduced significantly due to the existence of NdFeB PMs. To verify the validity of the proposed motor, the operating principles of the motor and the positive interaction influences between the two involved types of PMs are analyzed. Moreover, by using the finite element method, the torque characteristics and anti-demagnetization capabilities are also investigated in details. Both the theoretical analysis and simulated results confirm the advantages of the proposed motor.

  20. Design and implementation of a five-hp, switched reluctance, fuel-lube, pump motor drive for a gas turbine engine

    SciTech Connect

    Ferreira, C.A.; Jones, S.R.; Drager, B.T.; Heglund, W.S. )

    1995-01-01

    A new switched reluctance (SR) fuel/lube (F/L) pump system has been developed for a gas turbine engine application. The system is rated at 5 hp, 270 Vdc, 12.5 krpm maximum operating speed, and consists of a SR machine mounted on the F/L pump shaft, an inverter, and an electronic controller. This paper focuses on the design, implementation, and performance of the system. The system can use one of two methods for rotor position sensing, either a resolver or electronic position sensing (EPS). The F/L pump system has undergone extensive performance testing with the resolver. Currently, testing is underway using electronic position sensing. Test results are given to validate the system design and compare the performance using both approaches to position sensing. System efficiency is about 82% at full load.

  1. Low cost, compact, and high efficiency traction motor for electric and hybrid electric vehicles

    SciTech Connect

    Ehsani, Mark

    2002-10-07

    A new motor drive, the switched reluctance motor drive, has been developed for hybrid-electric vehicles. The motor drive has been designed, built and tested in the test bed at a near vehicle scale. It has been shown that the switched reluctance motor drive is more suitable for traction application than any other motor drive.

  2. Single bus star connected reluctance drive and method

    DOEpatents

    Fahimi, Babak; Shamsi, Pourya

    2016-05-10

    A system and methods for operating a switched reluctance machine includes a controller, an inverter connected to the controller and to the switched reluctance machine, a hysteresis control connected to the controller and to the inverter, a set of sensors connected to the switched reluctance machine and to the controller, the switched reluctance machine further including a set of phases the controller further comprising a processor and a memory connected to the processor, wherein the processor programmed to execute a control process and a generation process.

  3. A novel design and driving strategy for a hybrid electric machine with torque performance enhancement both taking reluctance and electromagnetic attraction effects into account

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Nan; Chen, Wan-Pei; Teng, Ching-Cheng; Chen, Mu-Ping

    2006-09-01

    A novel design, the hybrid electric machine, that owns improved competence for the output torque regulation as well as enlarged power density comparing to the conventional brushless machines by making use of the simultaneous performance overlapping concept based on magnetism is proposed in this paper. The developed design concept is focused on electric machine structure and its counterpart drive for applying two main magnetic-power transmitting paths by combination of both features of magnetic tendencies of flux generation that may flow in the path with minimum reluctance and direction owning the electromagnetic motive attraction. The verifications demonstrate that the outputted torque owns effective improvement by the presented concept of the electric machine based on the equivalent 3-hp frame than the conventional brushless motors.

  4. Hybrid MOSFET/Driver for Ultra-Fast Switching

    SciTech Connect

    Tang, T

    2009-07-14

    The ultra-fast switching of power MOSFETs, in about 1ns, is very challenging. This is largely due to the parasitic inductance that is intrinsic to commercial packages used for both MOSFETs and drivers. Parasitic gate and source inductance not only limit the voltage rise time on the MOSFET internal gate structure but can also cause the gate voltage to oscillate. This paper describes a hybrid approach that substantially reduces the parasitic inductance between the driver and MOSFET gate, as well as between the MOSFET source and its external connection. A flip chip assembly is used to directly attach a die-form power MOSFET and driver on a PCB. The parasitic inductances are significantly reduced by eliminating bond wires and minimizing lead length. The experimental results demonstrate ultra-fast switching of the power MOSFET with excellent control of the gate-source voltage.

  5. The Role of Reluctance in PM Motors

    SciTech Connect

    Otaduy, P.J.

    2005-06-16

    The international research community has lately focused efforts on interior permanent magnet (IPM) motors to produce a traction motor for hybrid electric vehicles (HEV). One of the beneficial features of this technology is the additional torque produced by reluctance. The objective of this report is to analytically describe the role that reluctance plays in permanent magnet (PM) motors, to explore ways to increase reluctance torque without sacrificing the torque produced by the PMs, and to compare three IPM configurations with respect to torque, power, amount of magnet material required (cost), and percentage of reluctance torque. Results of this study will be used to determine future research directions in utilizing reluctance to obtain maximum torque and power while using a minimum amount of magnet material.

  6. Hybrid burst/packet switching architectures from IP NOBEL

    NASA Astrophysics Data System (ADS)

    Leligou, Helen C.; Eilenberger, Gert; Dembeck, Lars; Lautenschlaeger, Wolfram; Bunse, Stephan; Stavdas, A.; Angelopoulos, J.; Politi, Christina T.

    2006-10-01

    In spite of its long term promise, all-optical switching is still plagued by high cost, low efficiency when handling bursty data traffic, immature management and protection and poor output port contention resolution leading to heavy loss. Given the current situation, hybrid approaches that keep the best features of optics, reverting to the electrical plane when expedient, constitute sensible interim steps that can offer cost-effective solutions along the road to an eventual all-optical core. Two such approaches developed in the framework of the European IP project NOBEL are presented in this work. The first is a quite mature solution that extends present day concepts to achieve multiplexing gain while keeping all the management and restoration benefits of SDH. The other mimics early LANs in executing a distributed switching via its electrical control plane using two-way reservations, thus restricting its applicability to smaller domains. Combining the two leads to a system fulfilling most of today's requirements for Tb/s core networks.

  7. Hybrid Voltage-Multipliers Based Switching Power Converters

    NASA Astrophysics Data System (ADS)

    Rosas-Caro, Julio C.; Mayo-Maldonado, Jonathan C.; Vazquez-Bautista, Rene Fabian; Valderrabano-Gonzalez, Antonio; Salas-Cabrera, Ruben; Valdez-Resendiz, Jesus Elias

    2011-08-01

    This work presents a derivation of PWM DC-DC hybrid converters by combining traditional converters with the Cockcroft-Walton voltage multiplier, the voltage multiplier of each converter is driven with the same transistor of the basic topology; this fact makes the structure of the new converters very simple and provides high-voltage gain. The traditional topologies discussed are the boost, buck-boost, Cuk and SEPIC. They main features of the discussed family are: (i) high-voltage gain without using extreme duty cycles or transformers, which allow high switching frequency and (ii) low voltage stress in switching devices, along with modular structures, and more output levels can be added without modifying the main circuit, which is highly desirable in some applications such as renewable energy generation systems. It is shown how a multiplier converter can become a generalized topology and how some of the traditional converters and several state-of-the-art converters can be derived from the generalized topologies and vice-versa. All the discussed converters were simulated, additionally experimental results are provided with an interleaved multiplier converter.

  8. Motivating Reluctant Writers.

    ERIC Educational Resources Information Center

    Pierce, Joyce; And Others

    This report describes a program for motivating reluctant writers. The targeted population consisted of one fourth-grade and four fifth-grade classrooms in three elementary schools. All three schools were located in the western suburbs of Chicago, Illinois. The problems of reluctant writers were documented with timed writing samples, student and…

  9. Hybrid plasmonic nanodevices: Switching mechanism for the nonlinear emission

    SciTech Connect

    Bragas, Andrea V.; Singh, Mahi R.

    2014-03-31

    Control of the light emission at the nanoscale is of central interest in nanophotonics due to the many applications in very different fields, ranging from quantum information to biophysics. Resonant excitation of surface plasmon polaritons in metal nanoparticles create nanostructured and enhanced light fields around those structures, which produce their strong interaction in a hybrid nanodevice with other plasmonic or non-plasmonic objects. This interaction may in turn also modulate the far field with important consequences in the applications. We show in this paper that the nonlinear emission from semiconductor quantum dots is strongly affected by the close presence of metal nanoparticles, which are resonantly excited. Using a pulsed laser, optical second harmonic is generated in the quantum dot, and it is highly enhanced when the laser is tuned around the nanoparticle plasmon resonance. Even more interesting is the demonstration of a switching mechanism, controlled by an external continuous-wave field, which can enhance or extinguish the SH signal, even when the pulsed laser is always on. Experimental observations are in excellent agreement with the theoretical calculations, based on the dipole-dipole near-field coupling of the objects forming the hybrid system.

  10. Hybrid optimization method with general switching strategy for parameter estimation.

    PubMed

    Balsa-Canto, Eva; Peifer, Martin; Banga, Julio R; Timmer, Jens; Fleck, Christian

    2008-03-24

    Modeling and simulation of cellular signaling and metabolic pathways as networks of biochemical reactions yields sets of non-linear ordinary differential equations. These models usually depend on several parameters and initial conditions. If these parameters are unknown, results from simulation studies can be misleading. Such a scenario can be avoided by fitting the model to experimental data before analyzing the system. This involves parameter estimation which is usually performed by minimizing a cost function which quantifies the difference between model predictions and measurements. Mathematically, this is formulated as a non-linear optimization problem which often results to be multi-modal (non-convex), rendering local optimization methods detrimental. In this work we propose a new hybrid global method, based on the combination of an evolutionary search strategy with a local multiple-shooting approach, which offers a reliable and efficient alternative for the solution of large scale parameter estimation problems. The presented new hybrid strategy offers two main advantages over previous approaches: First, it is equipped with a switching strategy which allows the systematic determination of the transition from the local to global search. This avoids computationally expensive tests in advance. Second, using multiple-shooting as the local search procedure reduces the multi-modality of the non-linear optimization problem significantly. Because multiple-shooting avoids possible spurious solutions in the vicinity of the global optimum it often outperforms the frequently used initial value approach (single-shooting). Thereby, the use of multiple-shooting yields an enhanced robustness of the hybrid approach.

  11. Novel multiterabit optical router based on hybrid switching technologies

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Zeng, QingJi; Ouyang, Yong; Liu, Jimin; Luo, Xuan; Huang, Xuejun

    2002-07-01

    Internet backbone network is undergoing a large-scale transformation from the current complex, static and multi-layer electronic-based architecture to the emerging simplified, and dynamic and one-layer photonic-based architecture. The explosive growth in the Internet, multi-media services, and IP router links are demanding the next generation Internet that can accommodate the entire traffic in a cost-effective manner. There is a consensus in current industries that IP over WDM integration technologies will be viable for the next generation of the optical Internet where the simplified flat network architecture can facilitate the networking performance and the networking management. In this paper, we firstly propose a novel node architecture-Terabit Optical Router (TOR) for building the next generation optical Internet and analyses each key function unit of TOR including multi-granularity electrical-optical hybrid switching fabrics, unified control plane unit and so on. Secondly, we give the unified routing definition of multi-layer in TOR and present control plane software structure with emphasis on multi-layer routing issues. Thirdly we describe our cost vs. performance analysis for various application of TOR. According to our calculation, we can get a cost reduction of more than 60 percent by using the TOR. Finally, we reach conclusions that TORs rather than OBS/OPS-based optical routers or big fat router, a cost effective multi-granularity switching and routing technique, are feasible to build the next generation Internet in the coming 5-10 years.

  12. A hybrid photonic-electronic switching architecture for next generation datacenters

    NASA Astrophysics Data System (ADS)

    Bernier, Eric; Mehrvar, Hamid; Kiaei, Mohammad; Ma, Huixiao; Yang, Xiaoling; Wang, Yan; Li, Shuaibing; Graves, Alan; Wang, Dawei; Fu, H. Y.; Geng, Dongyu; Goodwill, Dominic

    2015-02-01

    We provide an alternative architecture for the next generation datacenters by employing electronic and photonic switching cores. The capacity of electronic packet switching (EPS) cores is not enough for the bandwidth requirements of next generation datacenters. On the other hand, it is prohibitively costly to build pure photonic packet switching (OPS) core which is capable of switching native Ethernet frames in nanoseconds. We propose a low-cost hybrid OPS/EPS platform which significantly increases the switching capacity of datacenters for all traffic patterns while using the existing EPS cores. Our proposed architecture is a fat-tree hierarchy consisting of servers, top-of-racks (TOR), aggregation switches, and core switches. The aggregation switches are interconnected to the core hybrid OPS/EPS switch. Since the traffic inside datacenters is typically bimodal, the hybrid switch core becomes feasible by switching short and long packets using EPS and OPS cores, respectively. In order to prepare long packets for photonic switching, they undergo packet contention resolution, compression, and bitwise scrambling. Afterwards, a photonic destination label is added to the long packets, and they are sent out through an optical transmitter. For compressing the long packets, the clock rate is raised on the output of the physical layer. Packet compression increases inter-packet gap to insert the photonic label. Also, it provides more time for photonic switch connection set-up and receiver synchronization at the destination aggregation switch. We developed a test bed for our architecture and used it to transmit real-time traffic. Our experiments show successful transmission of all packets through OPS.

  13. Investigation of a hybrid optical-electronic switch supporting different service classes

    NASA Astrophysics Data System (ADS)

    Samoud, Wiem; Ware, Cédric; Lourdiane, Mounia

    2014-09-01

    Optical fiber is considered the most competitive wired transmission support thanks to its low attenuation, wide optical bandwidth, long reach, and low cost. However, optics do not yet perform higher functionalities such as switching. In fact, all-optical switches face a contention issue, due to the lack of practical optical buffers. Thus, the switching function is still performed electronically, which requires energetically costly optical-to-electronic conversions. The energy consumption is a critical issue within the growing data traffic. Thus, a proposition of hybrid switch architecture supplementing optical switch with an electronic buffer. In this paper, we propose to investigate the performance of hybrid switch that supports different priority classes where the priority is defined in terms of Packet Loss Ratio (PLR). We show that the hybrid switch is a good trade off since it allows significant performance improvements towards a buffer-less all optical switch in terms of PLR and sustainable load, for relatively few electronic ports of the buffer, which would reduce energy consumption compared to an electronic switch.

  14. Monolithic MZI-SOA hybrid switch for low-power and low-penalty operation.

    PubMed

    Cheng, Q; Wonfor, A; Wei, J L; Penty, R V; White, I H

    2014-03-15

    We report the first experimental demonstration of a monolithically integrated hybrid dilated 2×2 modular optical switch using Mach-Zehnder modulators as low-loss 1×2 switching elements and short semiconductor optical amplifiers to provide additional extinction and gain. An excellent 40 dB cross-talk/extinction ratio is recorded with data-modulated signal-to-noise ratios of up to 44 dB in a 0.1 nm bandwidth. A switching time of 3 ns is demonstrated. Bit error rate studies show extremely low subsystem penalties of less than 0.1 dB, and studies indicate that, by using this hybrid switch building block, an 8×8 port switch could be achieved with 14 dB input power dynamic range for subsystem penalties of less than 0.5 dB.

  15. The Reluctant Reader.

    ERIC Educational Resources Information Center

    Chambers, Aidan

    This book is concerned with the approximately 60% of capable adolescent readers who have little or no inclination to read creative literature. The possible causes of this reluctance to read are examined and various solutions to the problems are discussed. Chapters focus on the reading interests and motivations of teenagers, on the reasons that…

  16. Motivating the Reluctant Reader.

    ERIC Educational Resources Information Center

    Buzard, Barbara; Jarosz, Diane; Lato, Kelly; Zimmermann, Lori

    This report describes a program for increasing student reading motivation through the use of cooperative learning activities, differentiating reading instruction, and active reading strategies. The students of the targeted second, fourth, sixth and eighth grade classes exhibited a reluctance to read that interfered with academic growth. Probable…

  17. Analysis of the Ultra-fast Switching Dynamics in a Hybrid MOSFET/Driver

    SciTech Connect

    Tang, T.; Burkhart, C.; /SLAC

    2011-08-17

    The turn-on dynamics of a power MOSFET during ultra-fast, {approx} ns, switching are discussed in this paper. The testing was performed using a custom hybrid MOSFET/Driver module, which was fabricated by directly assembling die-form components, power MOSFET and drivers, on a printed circuit board. By using die-form components, the hybrid approach substantially reduces parasitic inductance, which facilitates ultra-fast switching. The measured turn on time of the hybrid module with a resistive load is 1.2 ns with an applied voltage of 1000 V and drain current of 33 A. Detailed analysis of the switching waveforms reveals that switching behavior must be interpreted differently in the ultra-fast regime. For example, the gate threshold voltage to turn on the device is observed to increase as the switching time decreases. Further analysis and simulation of MOSFET switching behavior shows that the minimum turn on time scales with the product of the drain-source on resistance and drain-source capacitance, R{sub DS(on)}C{sub OSS}. This information will be useful in power MOSFET selection and gate driver design for ultra-fast switching applications.

  18. Demonstration of the feasibility of large-port-count optical switching using a hybrid Mach-Zehnder interferometer-semiconductor optical amplifier switch module in a recirculating loop.

    PubMed

    Cheng, Q; Wonfor, A; Wei, J L; Penty, R V; White, I H

    2014-09-15

    For what we believe is the first time, the feasibility of large-port-count nanosecond-reconfiguration-time optical switches is demonstrated using a hybrid approach, where Mach-Zehnder interferometric (MZI) switches provide low-loss, high-speed routing with short semiconductor optical amplifiers (SOAs) being integrated to enhance extinction. By repeatedly passing signals through a monolithic hybrid dilated 2×2 switch module in a recirculating loop, the potential performance of high-port-count switches using the hybrid approach is demonstrated. Experimentally, a single pass switch penalty of only 0.1 dB is demonstrated for the 2×2 module, while even after seven passes through the switch, equivalent to a 128×128 router, a penalty of only 2.4 dB is recorded at a data rate of 10 Gb/s.

  19. Coupling Inductor Based Hybrid Millimeter-Wave Switch

    NASA Technical Reports Server (NTRS)

    Shu, Ran (Inventor); Tang, Adrian J. (Inventor); Gu, Qun (Inventor); Drouin, Brian J. (Inventor)

    2017-01-01

    A switch comprising a plurality of inductors and a plurality of shunt transistors is described. Each inductor can be electrically coupled between adjacent shunt transistors to form a distributed switch structure. At least two inductors in the plurality of inductors can be inductively coupled with each other. The plurality of inductors can correspond to portions of a coupling inductor, wherein the coupling inductor can have an irregular octagonal shape.

  20. Origins of two hemiclonal hybrids among three Hexagrammos species (Teleostei: Hexagrammidae): genetic diversification through host switching.

    PubMed

    Munehara, Hiroyuki; Horita, Miho; Kimura-Kawaguchi, Motoko R; Yamazaki, Aya

    2016-10-01

    Two natural, hemiclonal hybrid strains were discovered in three Hexagrammos species. The natural hybrids, all of which were females that produced haploid eggs containing only the Hexagrammos octogrammus genome (maternal ancestor; hereafter Hoc), generated F1 hybrid-type offspring by fertilization with haploid sperm of Hexagrammos agrammus or Hexagrammos otakii (paternal species; Hag and Hot, respectively). This study was performed to clarify the extent of diversification between the two hybrids and the maternal ancestor. Genealogical analysis using mtDNA revealed that all 38 Hoc/Hot hybrids formed a branch (Branch I) with 18 of the 33 Hoc/Hag hybrids. No haplotype sharing was observed with the maternal ancestor. Further, microsatellite DNA analysis suggested that the members of Branch I shared the same hemiclonal genome set. The results suggested that Hoc/Hot hybrids originated by anomalous hybridization, or "host switching," between Hoc/Hag and Hot, and not from interspecific hybridization between Hoc and Hot. The remaining 9 of 11 Hoc/Hag haplotypes and all of the 27 Hoc haplotypes were mixed within the genealogical tree, as if they had originated from multiple mutations. However, Hoc/Hag could also mate with Hoc. Although offspring from this host switch (Backcross-Hoc) have the same genome as normal Hoc, a part of their genome retains genetic factors capable of producing hemiclones. Consequently, when a descendant of a BC-Hoc hybrid mates with Hag males, a new hemiclone lineage will arise. Multiple haplotype revival through host switching from a single mutation in hybrids is another possible hypothesis for the observed mixing of Hoc/Hag haplotypes within the mtDNA genealogical tree.

  1. Variable reluctance drive system

    SciTech Connect

    Lipo, T.A.; Liang, F.

    1995-10-17

    A variable reluctance drive system including a motor and corresponding converter for improved current commutation is described. The motor incorporates a salient pole rotor and a salient pole stator having one or more full pitch windings which operate by mutual inductance to transfer the current from the active short pitch winding following phase alignment. This increases output torque and/or speed and permits a number of simple and economical converter circuits. 17 figs.

  2. Hybrid zero-voltage switching (ZVS) control for power inverters

    SciTech Connect

    Amirahmadi, Ahmadreza; Hu, Haibing; Batarseh, Issa

    2016-11-01

    A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit.

  3. Hybrid colored noise process with space-dependent switching rates

    NASA Astrophysics Data System (ADS)

    Bressloff, Paul C.; Lawley, Sean D.

    2017-07-01

    A fundamental issue in the theory of continuous stochastic process is the interpretation of multiplicative white noise, which is often referred to as the Itô-Stratonovich dilemma. From a physical perspective, this reflects the need to introduce additional constraints in order to specify the nature of the noise, whereas from a mathematical perspective it reflects an ambiguity in the formulation of stochastic differential equations (SDEs). Recently, we have identified a mechanism for obtaining an Itô SDE based on a form of temporal disorder. Motivated by switching processes in molecular biology, we considered a Brownian particle that randomly switches between two distinct conformational states with different diffusivities. In each state, the particle undergoes normal diffusion (additive noise) so there is no ambiguity in the interpretation of the noise. However, if the switching rates depend on position, then in the fast switching limit one obtains Brownian motion with a space-dependent diffusivity of the Itô form. In this paper, we extend our theory to include colored additive noise. We show that the nature of the effective multiplicative noise process obtained by taking both the white-noise limit (κ →0 ) and fast switching limit (ɛ →0 ) depends on the order the two limits are taken. If the white-noise limit is taken first, then we obtain Itô, and if the fast switching limit is taken first, then we obtain Stratonovich. Moreover, the form of the effective diffusion coefficient differs in the two cases. The latter result holds even in the case of space-independent transition rates, where one obtains additive noise processes with different diffusion coefficients. Finally, we show that yet another form of multiplicative noise is obtained in the simultaneous limit ɛ ,κ →0 with ɛ /κ2 fixed.

  4. A Switching Type-II Hybrid ARQ Scheme with RCPT Codes

    NASA Astrophysics Data System (ADS)

    Chen, Ju-Ya

    A switching type-II hybrid ARQ scheme with rate compatible punctured turbo (RCPT) codes is proposed in this letter. The proposed scheme combines three retransmission schemes by minimizing a cost function that yields a compromise between throughput and delay time. The performance of the proposed algorithm is evaluated by computer simulations. Compared with conventional hybrid ARQ algorithms, the proposed algorithm can offer almost the same throughput performance with smaller time delay.

  5. Polarization switch of four-wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2015-02-15

    Degenerate spontaneous four-wave mixing is considered in a large mode area hybrid photonic crystal fiber. Numerical and experimental results show birefringence assisted four-wave mixing for a certain polarization state of the pump field. The parametric gain can be turned on and off by switching the polarization state of the pump field between the two principal axis of the hybrid photonic crystal fiber.

  6. Improved performance of thermal-optic switch using polymer/silica hybrid and air trench waveguide structures.

    PubMed

    Liu, Yu-Fen; Wang, Xi-Bin; Sun, Jing-Wen; Sun, Jian; Wang, Fei; Chen, Chang-Ming; Sun, Xiao-Qiang; Cui, Zhan-Chen; Zhang, Da-Ming

    2015-05-01

    By exploiting the polymer/silica hybrid and the air trench waveguide structures, we demonstrate a new type of low-power consuming and high-speed thermal-optic (TO) switch. Such a design provides an effective means to shorten the switching time of the TO switches, as well as to reduce the power consumption at the same time. This TO switch operated with less than 150 μs of switching time via a polymer/silica hybrid waveguide structure. Meanwhile, the power consumption was reduced to be 3.4 mW by introducing the air trench structure.

  7. Hybrid approach to repair of pulmonary venous baffle obstruction after atrial switch operation.

    PubMed

    Sareyyupoglu, Basar; Burkhart, Harold M; Hagler, Donald J; Dearani, Joseph A; Cabalka, Allison; Cetta, Frank; Schaff, Hartzell V

    2009-11-01

    Pulmonary venous pathway obstruction is a late complication of the atrial switch operation for transposition of the great arteries. Gaining peripheral access to the pulmonary venous baffle obstruction to treat the obstruction with stent deployment is difficult if not impossible. We present three patients in which we used hybrid procedures in the operating room to relieve the pulmonary venous pathway obstructions.

  8. Complexity, Robustness, and Multistability in Network Systems with Switching Topologies: A Hierarchical Hybrid Control Approach

    DTIC Science & Technology

    2015-05-22

    AFRL-AFOSR-VA-TR-2015-0282 Complexity, Robustness, and Multistability in Network Systems with Switching Topologies A Hierarchical Hybrid Control ...concentrated on the development of a unified discontinuous dynamical framework for nonlinear network systems. In particular, control algorithms were... network systems, large-scale systems, adaptive control , discontinuous systems 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF

  9. Misfire detection based on switched state observer of hybrid system in internal combustion engine

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhou, Tonglin; Zheng, Taixiong; Han, Weimin; Tan, Rui; Wang, Yanjun

    2017-04-01

    This paper proposes a novel switched state observer of hybrid system using Luenberger sliding mode observer to estimate crankshaft angular acceleration which is further applied to detect misfire fault. The output error of hybrid system of internal combustion engine (engine speed) and the designed observer (estimated speed) is taken as input of observer to estimate crankshaft acceleration. Convergence of hybrid system is proven through Lyapunov stability theory. The experimental results show that the presented estimated technique has a higher accuracy and can be effectively used to misfire detection compared with reduced-order observer and sliding mode observer.

  10. Robust transmission stabilization and dynamic switching in broadband hybrid waveguide systems with nonlinear gain and loss

    NASA Astrophysics Data System (ADS)

    Nguyen, Quan M.; Peleg, Avner; Tran, Thinh P.

    2015-01-01

    We develop a method for transmission stabilization and robust dynamic switching for colliding optical soliton sequences in broadband waveguide systems with nonlinear gain and loss. The method is based on employing hybrid waveguides, consisting of spans with linear gain and cubic loss, and spans with linear loss, cubic gain, and quintic loss. We show that the amplitude dynamics is described by a hybrid Lotka-Volterra (LV) model, and use the model to determine the physical parameter values required for enhanced transmission stabilization and switching. Numerical simulations with coupled nonlinear Schrödinger equations confirm the predictions of the LV model, and show complete suppression of radiative instability and pulse distortion. This enables stable transmission over distances larger by an order of magnitude compared with uniform waveguides with linear gain and cubic loss. Moreover, multiple on-off and off-on dynamic switching events are demonstrated over a wide range of soliton amplitudes, showing the superiority of hybrid waveguides compared with static switching in uniform waveguides.

  11. Variable-Reluctance Motor For Electric Vehicles

    NASA Technical Reports Server (NTRS)

    Lang, Jeffrey H.

    1987-01-01

    Report describes research on variable-reluctance electric-motor drive for eventual use in electric-vehicle propulsion. Primary design and performance criteria were torque and power output per unit mass of motor, cost, and drive efficiency. For each criterion, optimized drive design developed, and designs unified to yield single electric-vehicle drive. Scaled-down motor performed as expected. Prototype of paraplegic lift operated by toggle switch and joystick. Lift plugs into household electrical outlet for recharging when not in use.

  12. Variable-Reluctance Motor For Electric Vehicles

    NASA Technical Reports Server (NTRS)

    Lang, Jeffrey H.

    1987-01-01

    Report describes research on variable-reluctance electric-motor drive for eventual use in electric-vehicle propulsion. Primary design and performance criteria were torque and power output per unit mass of motor, cost, and drive efficiency. For each criterion, optimized drive design developed, and designs unified to yield single electric-vehicle drive. Scaled-down motor performed as expected. Prototype of paraplegic lift operated by toggle switch and joystick. Lift plugs into household electrical outlet for recharging when not in use.

  13. Current induced magnetization dynamics and magnetization switching in superconducting ferromagnetic hybrid ( F |S |F ) structures

    NASA Astrophysics Data System (ADS)

    Acharjee, Saumen; Goswami, Umananda Dev

    2016-12-01

    We investigate the current induced magnetization dynamics and magnetization switching in an unconventional p-wave superconductor sandwiched between two misaligned ferromagnetic layers by numerically solving the Landau-Lifshitz-Gilbert equation modified with current induced Slonczewski's spin torque term. A modified form of the Ginzburg-Landau free energy functional has been used for this purpose. We demonstrated the possibility of current induced magnetization switching in the spin-triplet ferromagnetic superconducting hybrid structures with a strong easy axis anisotropy and the condition for magnetization reversal. The switching time for such arrangement is calculated and is found to be highly dependent on the magnetic configuration along with the biasing current. This study would be useful in designing the practical superconducting-spintronic devices.

  14. Picosecond pulse generation in a hybrid Q-switched laser source by using a microelectromechanical mirror.

    PubMed

    Couderc, Vincent; Crunteanu, Aurelian; Fabert, Marc; Doutre, Florent; El Bassri, Farid; Pagnoux, Dominique; Jalocha, Alain

    2012-02-27

    We present a novel Q-switched laser source using a micro-optical-electromechanical mirror (MOEM) designed for short pulse emission. It is based on a hybrid configuration including a passively Q-switched microchip laser coupled to a fiber cavity closed by a cantilever type MOEM acting as an active modulator. This specially designed mirror with a single reflecting gold membrane is switched by low bias voltage ~50 V (peak to peak). This device emits pulses at tunable repetition rates up to 1.6 kHz, with ~564 ps duration and 3.4 kW peak power, which constitutes the shortest pulse duration ever reported with MOEMs based pulsed lasers.

  15. A Soft-Switching Inverter for High-Temperature Advanced Hybrid Electric Vehicle Traction Motor Drives

    SciTech Connect

    Lai, Jason; Yu, Wensong; Sun, Pengwei; Leslie, Scott; Prusia, Duane; Arnet, Beat; Smith, Chris; Cogan, Art

    2012-03-31

    The state-of-the-art hybrid electric vehicles (HEVs) require the inverter cooling system to have a separate loop to avoid power semiconductor junction over temperatures because the engine coolant temperature of 105°C does not allow for much temperature rise in silicon devices. The proposed work is to develop an advanced soft-switching inverter that will eliminate the device switching loss and cut down the power loss so that the inverter can operate at high-temperature conditions while operating at high switching frequencies with small current ripple in low inductance based permanent magnet motors. The proposed tasks also include high-temperature packaging and thermal modeling and simulation to ensure the packaged module can operate at the desired temperature. The developed module will be integrated with the motor and vehicle controller for dynamometer and in-vehicle testing to prove its superiority. This report will describe the detailed technical design of the soft-switching inverters and their test results. The experiments were conducted both in module level for the module conduction and switching characteristics and in inverter level for its efficiency under inductive and dynamometer load conditions. The performance will be compared with the DOE original specification.

  16. Thermo-optic switches using sol-gel processed hybrid materials

    NASA Astrophysics Data System (ADS)

    Kribich, Kada R.; Barry, Henry; Copperwhite, Robert; Kolodziejczyk, Boleslaw; O'Dwyer, Kieran; Sabattie, Jean-Marc; MacCraith, Brian D.

    2004-08-01

    There is a clear need for low cost, high performance and large-scale production of photonic chips. Network development requires more interconnecting components. A flexible and low-cost process using good quality material is necessary. The sol-gel process is a chemical method to fabricate glasses at ambient pressure and moderate temperature. The resulting material properties can be tuned depending on the precursors used. Hybrid materials, mixing organic and inorganic parts, offer the advantages of polymer-like materials and glasses. We have developed sol-gel-processed integrated optical circuits using hybrid materials. We report on the development of active devices based on the thermo-optic effect. Thermo-optic coefficients as high as -2.10-4/°K have been measured in our materials. This enables the design of compact devices with low power consumption. Our goal is to utilise the thermo-optic effect in the development of integrated optical switches. The kHz response time of such switches makes them unsuitable for modulation applications, but they can be used for network protection, reconfiguration purposes in routing and multiplexing applications such as Code Division Multiplexing. New designs, based on multimode interference couplers (MMIC), have also been created. In this work we first describe the synthesis of the hybrid materials as well as the fabrication processes. Using the measured properties of the materials developed, we can simulate the optical and thermal properties of the target devices. The simulation results have been exploited to model and optimise a range of switch designs, including MMI-based 1xN switches. Finally, we report on the full characterisation of the different structures and devices created in terms of fabrication quality and optical and thermal response.

  17. Nano-electromechanical switch-CMOS hybrid technology and its applications.

    PubMed

    Lee, B H; Hwang, H J; Cho, C H; Lim, S K; Lee, S Y; Hwang, H

    2011-01-01

    Si-based CMOS technology is facing a serious challenge in terms of power consumption and variability. The increasing costs associated with physical scaling have motivated a search for alternative approaches. Hybridization of nano-electromechanical (NEM)-switch and Si-based CMOS devices has shown a theoretical feasibility for power management, but a huge technical gap must be bridged before a nanoscale NEM switch can be realized due to insufficient material development and the limited understanding of its reliability characteristics. These authors propose the use of a multilayer graphene as a nanoscale cantilever material for a nanoscale NEM switchwith dimensions comparable to those of the state-of-the-art Si-based CMOS devices. The optimal thickness for the multilayer graphene (about five layers) is suggested based on an analytical model. Multilayer graphene can provide the highest Young's modulus among the known electrode materials and a yielding strength that allows more than 15% bending. Further research on material screening and device integration is needed, however, to realize the promises of the hybridization of NEM-switch and Si-based CMOS devices.

  18. Performance evaluation of an optical hybrid switch with circuit queued reservations and circuit priority preemption.

    PubMed

    Wong, Eric W M; Zukerman, Moshe

    2006-11-13

    We provide here a new loss model for an optical hybrid switch that can function as an optical burst switch and/or optical circuit switch. Our model is general as it considers an implementation whereby some of the circuits have preemptive priority over bursts and others are allowed to queue their reservations. We first present an analysis based on a 3-dimension state-space Markov chain that provides exact results for the blocking probabilities of bursts and circuits, the proportion of circuits that are delayed and the mean delay of the circuits that are delayed. Because it is difficult to exactly compute the blocking probability in realistic scenarios with a large number of wavelengths, we derive computationally a scalable and accurate approximations based on reducing the 3-dimension state space into a single dimension. These scalable approximations that can produce performance results in a fraction of a second can readily enable switch dimensioning. Extensive numerical results are presented to demonstrate the accuracy and the use of the new approximations.

  19. Graph-Switching Based Modeling of Mode Transition Constraints for Model Predictive Control of Hybrid Systems

    NASA Astrophysics Data System (ADS)

    Kobayashi, Koichi; Hiraishi, Kunihiko

    The model predictive/optimal control problem for hybrid systems is reduced to a mixed integer quadratic programming (MIQP) problem. However, the MIQP problem has one serious weakness, i.e., the computation time to solve the MIQP problem is too long for practical plants. For overcoming this technical issue, there are several approaches. In this paper, a modeling of mode transition constraints, which are expressed by a directed graph, is focused, and a new method to represent a directed graph is proposed. The effectiveness of the proposed method is shown by numerical examples on linear switched systems and piecewise linear systems.

  20. Hybrid metamaterial switching for manipulating chirality based on VO2 phase transition

    PubMed Central

    Lv, T. T.; Li, Y. X.; Ma, H. F.; Zhu, Z.; Li, Z. P.; Guan, C. Y.; Shi, J. H.; Zhang, H.; Cui, T. J.

    2016-01-01

    Polarization manipulations of electromagnetic waves can be obtained by chiral and anisotropic metamaterials routinely, but the dynamic and high-efficiency modulations of chiral properties still remain challenging at the terahertz range. Here, we theoretically demonstrate a new scheme for realizing thermal-controlled chirality using a hybrid terahertz metamaterial with embedded vanadium dioxide (VO2) films. The phase transition of VO2 films in 90° twisted E-shaped resonators enables high-efficiency thermal modulation of linear polarization conversion. The asymmetric transmission of linearly polarized wave and circular dichroism simultaneously exhibit a pronounced switching effect dictated by temperature-controlled conductivity of VO2 inclusions. The proposed hybrid metamaterial design opens exciting possibilities to achieve dynamic modulation of terahertz waves and further develop tunable terahertz polarization devices. PMID:27000427

  1. Hybrid Pwm Switching Strategy for a Three-Level Inverter Fed Induction Motor Drive with Open-End Windings

    NASA Astrophysics Data System (ADS)

    Srinivas, S.; Ramachandrasekhar, K.

    2010-06-01

    A dual two-level inverter fed induction motor with open-end windings is capable of generating a three-level output voltage. Several, sine-triangle and space vector pulse width modulation (PWM) switching strategies are presented for the dual-inverter scheme either using space-vector or carrier-based implementation. In this paper, a hybrid PWM switching strategy for the dual-inverter scheme is proposed employing sine-triangle PWM (SPWM) and space vector PWM (SVPWM) for the individual inverters. SPWM is theoretically analyzed and space vector based implementation of SPWM is presented using a simple offset-time concept. This is exploited to implement the hybrid PWM switching strategy for the dual two-level inverter. The implementation of the hybrid PWM switching strategy proposed in this paper do not require any look-up tables, the switching is totally automatic obviating the time-consuming task of sector identification. The implementation of the hybrid PWM scheme requires only the three instantaneous phase reference voltages corresponding to the reference space vector. The third harmonic component in the voltage appearing across the motor phase windings in the induction motor is significantly reduced (by 50%) with the use of the proposed hybrid PWM scheme as compared to the use of the PWM scheme presented earlier. Also, the percentage weighted total harmonic distortion (%WTHD) of the output voltage is significantly reduced in the entire range of speed of the induction motor driven by the dual-inverter scheme.

  2. Discrete Adjoint Sensitivity Analysis of Hybrid Dynamical Systems With Switching [Discrete Adjoint Sensitivity Analysis of Hybrid Dynamical Systems

    DOE PAGES

    Zhang, Hong; Abhyankar, Shrirang; Constantinescu, Emil; ...

    2017-01-24

    Sensitivity analysis is an important tool for describing power system dynamic behavior in response to parameter variations. It is a central component in preventive and corrective control applications. The existing approaches for sensitivity calculations, namely, finite-difference and forward sensitivity analysis, require a computational effort that increases linearly with the number of sensitivity parameters. In this paper, we investigate, implement, and test a discrete adjoint sensitivity approach whose computational effort is effectively independent of the number of sensitivity parameters. The proposed approach is highly efficient for calculating sensitivities of larger systems and is consistent, within machine precision, with the function whosemore » sensitivity we are seeking. This is an essential feature for use in optimization applications. Moreover, our approach includes a consistent treatment of systems with switching, such as dc exciters, by deriving and implementing the adjoint jump conditions that arise from state-dependent and time-dependent switchings. The accuracy and the computational efficiency of the proposed approach are demonstrated in comparison with the forward sensitivity analysis approach. In conclusion, this paper focuses primarily on the power system dynamics, but the approach is general and can be applied to hybrid dynamical systems in a broader range of fields.« less

  3. Developing high-power hybrid resonant gain-switched thulium fiber lasers.

    PubMed

    Yan, Shuo; Wang, Yao; Zhou, Yan; Yang, Nan; Li, Yue; Tang, Yulong; Xu, Jianqiu

    2015-10-05

    In this paper, we propose hybrid-pumped resonant gain-switched thulium fiber lasers to realize high-average-power and high-pulse-energy 2-μm laser emissions. Based on numerical simulation, laser dynamics (pulse peak power, pulse energy, pulse duration, etc.) of this kind of laser system are investigated in detail. By taking advantages of the 793 nm continuous wave pump and the 1900 nm pulsed pump, performance of the laser emission can be significantly improved, with the highest average power of 28 W, peak power of 3.5 kW, pulse energy of 281 μJ, and narrowest pulse duration of 92 ns, all of which can be further optimized through designing the cavity parameters and the pumping circumstance. Compared with the pump pulses, two times improvement in pulse energy and average power has been achieved. This hybrid resonant gain-switched system has an all-fiber configuration and high efficiency (low heat load), and can be steadily extended into the cladding pump scheme, thus paving a new way to realize high power (>100 W average power) and high pulse energy (>1 mJ) 2 μm thulium fiber lasers.

  4. Resistive Switching Characteristics of Tantalum Oxide Thin Film and Titanium Oxide Nanoparticles Hybrid Structure.

    PubMed

    Park, Mi Ra; Abbas, Yawar; Hu, Quanli; Yoon, Tae-Sik; Choi, Young Jin; Kang, Chi Jung

    2015-11-01

    The fabrication of hybrid structure with TiO2 nanoparticle assembly and Ta2O5 thin film layer was demonstrated. The close-packed nanoparticles could influence the resistive switching behaviors due to the huge numbers of interface states and vacancies in the nanoparticle assembly. The device with hybrid structure presented the typical bipolar resistive switching characteristics in the structure of Ti/TiO2/Ta2O5/Au on SiO2/Si substrate. The set voltage was observed at -0.7 V, and the reset voltage occurred at (-)-0.7 V, which was smaller than that of Ta2O5 layer only. The electrical conduction mechanisms were the ohmic conduction at low resistance state (LRS) and the space charge limited conduction at high resistance state (HRS), respectively. The devices showed stable current ratio of LRS to HRS. The temperature dependent properties of the devices were also investigated. The device with nanoparticle assembly showed better electrical characteristics with low HRS current level and stable LRS current level with respect to the temperature.

  5. Effect of halide-mixing on the switching behaviors of organic-inorganic hybrid perovskite memory

    NASA Astrophysics Data System (ADS)

    Hwang, Bohee; Gu, Chungwan; Lee, Donghwa; Lee, Jang-Sik

    2017-03-01

    Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3-xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3-xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3-xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3-xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br- (0.23 eV) than for I- (0.29-0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film.

  6. On the fly all-optical packet switching based on hybrid WDM/OCDMA labeling scheme

    NASA Astrophysics Data System (ADS)

    Brahmi, Houssem; Giannoulis, Giannis; Menif, Mourad; Katopodis, Vasilis; Kalavrouziotis, Dimitrios; Kouloumentas, Christos; Groumas, Panos; Kanakis, Giannis; Stamatiadis, Christos; Avramopoulos, Hercules; Erasme, Didier

    2014-02-01

    We introduce a novel design of an all-optical packet routing node that allows for the selection and forwarding of optical packets based on the routing information contained in hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) labels. A stripping paradigm of optical code-label is adopted. The router is built around an optical-code gate that consists in an optical flip-flop controlled by two fiber Bragg grating correlators and is combined with a Mach-Zehnder interferometer (MZI)-based forwarding gate. We experimentally verify the proof-of-principle operation of the proposed self-routing node under NRZ and OCDMA packet traffic conditions. The successful switching of elastic NRZ payload at 40 Gb/s controlled by DS-OCDMA coded labels and the forwarding operation of encoded data using EQC codes are presented. Proper auto-correlation functions are obtained with higher than 8.1 dB contrast ratio, suitable to efficiently trigger the latching device with a contrast ratio of 11.6 dB and switching times below 3.8 ns. Error-free operation is achieved with 1.5 dB penalty for 40 Gb/s NRZ data and with 2.1 dB penalty for DS-OCDMA packets. The scheme can further be applied to large-scale optical packet switching networks by exploiting efficient optical coders allocated at different WDM channels.

  7. Variability of multilevel switching in scaled hybrid RS/CMOS nanoelectronic circuits: theory

    NASA Astrophysics Data System (ADS)

    Heittmann, Arne; Noll, Tobias G.

    2013-07-01

    A theory is presented which describes the variability of multilevel switching in scaled hybrid resistive-switching/CMOS nanoelectronic circuits. Variability is quantified in terms of conductance variation using the first two moments derived from the probability density function (PDF) of the RS conductance. For RS, which are based on the electrochemical metallization effect (ECM), this variability is - to some extent - caused by discrete events such as electrochemical reactions, which occur on atomic scale and are at random. The theory shows that the conductance variation depends on the joint interaction between the programming circuit and the resistive switch (RS), and explicitly quantifies the impact of RS device parameters and parameters of the programming circuit on the conductance variance. Using a current mirror as an exemplary programming circuit an upper limit of 2-4 bits (dependent on the filament surface area) is estimated as the storage capacity exploiting the multilevel capabilities of an ECM cell. The theoretical results were verified by Monte Carlo circuit simulations on a standard circuit simulation environment using an ECM device model which models the filament growth by a Poisson process. Contribution to the Topical Issue “International Semiconductor Conference Dresden-Grenoble - ISCDG 2012”, Edited by Gérard Ghibaudo, Francis Balestra and Simon Deleonibus.

  8. Fundamental Frequency Switching Control of Seven-Level Hybrid Cascaded H-bridge Multilevel Inverter

    SciTech Connect

    Du, Zhong; Chiasson, John N; Ozpineci, Burak; Tolbert, Leon M

    2009-01-01

    This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require n dc sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the remaining n-1 dc sources being capacitors, which is referred to as hybrid cascaded H-bridge multilevel inverter (HCMLI) in this paper. It is shown that the inverter can simultaneously maintain the dc voltage level of the capacitors and choose a fundamental frequency switching pattern to produce a nearly sinusoidal output. HCMLI using only a single dc source for each phase is promising for high-power motor drive applications as it significantly decreases the number of required dc power supplies, provides high-quality output power due to its high number of output levels, and results in high conversion efficiency and low thermal stress as it uses a fundamental frequency switching scheme. This paper mainly discusses control of seven-level HCMLI with fundamental frequency switching control and how its modulation index range can be extended using triplen harmonic compensation.

  9. Switching behavior of thermochromic copper and silver tetraiodomercurate embedded in silica hybrid materials

    NASA Astrophysics Data System (ADS)

    Raditoiu, Valentin; Radovici, Constantin; Raditoiu, Alina; Nicolae, Cristian Andi; Culita, Daniela Cristina; Fierascu, Radu Claudiu; Amariutei, Viorica; Wagner, Luminita Eugenia

    2013-10-01

    Thermochromic silica hybrids containing copper or silver mercuric iodides and cetyltrimethylammonium bromide (CTAB) were obtained and characterized. The color and switching behavior of the materials was studied in relationship with the structure of the thermochromic composites and silica network modifiers. In order to evidence the presence of the components and possible interactions governing the thermochromic transition, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis - DR), Fourier transform infrared spectroscopy - attenuated reflection (FTIR-ATR), X-ray diffraction spectroscopy (XRD) and X-ray fluorescence (XRF) analysis were performed. The dynamic behavior was studied by UV-Vis reflectance spectra, FTIR and differential thermal analysis (DTA) analysis. Results confirm that during the embedding of thermochromic compounds in silica hybrid matrices, in the presence of CTAB, some interactions are established between thermochromic compounds and CTAB. These interactions determine the parameters of thermochromic transition in all cases of thermochromic composites. Hysteresis during the repetitive heating-cooling cycles was also observed. Thermal stability of the thermochromic compounds was enhanced after embedding in silica hybrids.

  10. Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems.

    PubMed

    Wohlhüter, Phillip; Bryan, Matthew Thomas; Warnicke, Peter; Gliga, Sebastian; Stevenson, Stephanie Elizabeth; Heldt, Georg; Saharan, Lalita; Suszka, Anna Kinga; Moutafis, Christoforos; Chopdekar, Rajesh Vilas; Raabe, Jörg; Thomson, Thomas; Hrkac, Gino; Heyderman, Laura Jane

    2015-08-04

    Vortices are fundamental magnetic topological structures characterized by a curling magnetization around a highly stable nanometric core. The control of the polarization of this core and its gyration is key to the utilization of vortices in technological applications. So far polarization control has been achieved in single-material structures using magnetic fields, spin-polarized currents or spin waves. Here we demonstrate local control of the vortex core orientation in hybrid structures where the vortex in an in-plane Permalloy film coexists with out-of-plane maze domains in a Co/Pd multilayer. The vortex core reverses its polarization on crossing a maze domain boundary. This reversal is mediated by a pair of magnetic singularities, known as Bloch points, and leads to the transient formation of a three-dimensional magnetization structure: a Bloch core. The interaction between vortex and domain wall thus acts as a nanoscale switch for the vortex core polarization.

  11. Cyclic Parameter Refinement of 4S-10 Hybrid Flux-Switching Motor for Lightweight Electric Vehicle

    NASA Astrophysics Data System (ADS)

    Rani, J. Abd; Sulaiman, E.; Kumar, R.

    2017-08-01

    A great deal of attention has been given to the reduction of lighting the vehicle because the lighter the vehicle the energy consumption is comparatively low. Hence, the lightweight electric vehicle was introduced for lower carbon footprint and the sizing of the vehicle itself. One of the components to reduce the weight of the vehicle is the propulsion system which comprised of electric motor functioning as the source of torque to drive the propulsion system of the machine. This paper presents the refinement methodology for the optimized design of the 4S-10P E-Core hybrid excitation flux switching motor. The purpose of the refinement methodology is to improve the torque production of the optimized motor. The result of the successful improvement of the torque production is justifiable for a lightweight electric vehicle to drive the propulsion system.

  12. Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems

    NASA Astrophysics Data System (ADS)

    Wohlhüter, Phillip; Bryan, Matthew Thomas; Warnicke, Peter; Gliga, Sebastian; Stevenson, Stephanie Elizabeth; Heldt, Georg; Saharan, Lalita; Suszka, Anna Kinga; Moutafis, Christoforos; Chopdekar, Rajesh Vilas; Raabe, Jörg; Thomson, Thomas; Hrkac, Gino; Heyderman, Laura Jane

    2015-08-01

    Vortices are fundamental magnetic topological structures characterized by a curling magnetization around a highly stable nanometric core. The control of the polarization of this core and its gyration is key to the utilization of vortices in technological applications. So far polarization control has been achieved in single-material structures using magnetic fields, spin-polarized currents or spin waves. Here we demonstrate local control of the vortex core orientation in hybrid structures where the vortex in an in-plane Permalloy film coexists with out-of-plane maze domains in a Co/Pd multilayer. The vortex core reverses its polarization on crossing a maze domain boundary. This reversal is mediated by a pair of magnetic singularities, known as Bloch points, and leads to the transient formation of a three-dimensional magnetization structure: a Bloch core. The interaction between vortex and domain wall thus acts as a nanoscale switch for the vortex core polarization.

  13. Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems

    PubMed Central

    Wohlhüter, Phillip; Bryan, Matthew Thomas; Warnicke, Peter; Gliga, Sebastian; Stevenson, Stephanie Elizabeth; Heldt, Georg; Saharan, Lalita; Suszka, Anna Kinga; Moutafis, Christoforos; Chopdekar, Rajesh Vilas; Raabe, Jörg; Thomson, Thomas; Hrkac, Gino; Heyderman, Laura Jane

    2015-01-01

    Vortices are fundamental magnetic topological structures characterized by a curling magnetization around a highly stable nanometric core. The control of the polarization of this core and its gyration is key to the utilization of vortices in technological applications. So far polarization control has been achieved in single-material structures using magnetic fields, spin-polarized currents or spin waves. Here we demonstrate local control of the vortex core orientation in hybrid structures where the vortex in an in-plane Permalloy film coexists with out-of-plane maze domains in a Co/Pd multilayer. The vortex core reverses its polarization on crossing a maze domain boundary. This reversal is mediated by a pair of magnetic singularities, known as Bloch points, and leads to the transient formation of a three-dimensional magnetization structure: a Bloch core. The interaction between vortex and domain wall thus acts as a nanoscale switch for the vortex core polarization. PMID:26238042

  14. Model predictive control of an air suspension system with damping multi-mode switching damper based on hybrid model

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoqiang; Yuan, Chaochun; Cai, Yingfeng; Wang, Shaohua; Chen, Long

    2017-09-01

    This paper presents the hybrid modeling and the model predictive control of an air suspension system with damping multi-mode switching damper. Unlike traditional damper with continuously adjustable damping, in this study, a new damper with four discrete damping modes is applied to vehicle semi-active air suspension. The new damper can achieve different damping modes by just controlling the on-off statuses of two solenoid valves, which makes its damping adjustment more efficient and more reliable. However, since the damping mode switching induces different modes of operation, the air suspension system with the new damper poses challenging hybrid control problem. To model both the continuous/discrete dynamics and the switching between different damping modes, the framework of mixed logical dynamical (MLD) systems is used to establish the system hybrid model. Based on the resulting hybrid dynamical model, the system control problem is recast as a model predictive control (MPC) problem, which allows us to optimize the switching sequences of the damping modes by taking into account the suspension performance requirements. Numerical simulations results demonstrate the efficacy of the proposed control method finally.

  15. Hybrid Nd 3+-doped passively Q-switched waveguide laser made by ion exchange

    NASA Astrophysics Data System (ADS)

    Salas-Montiel, Rafael; Bastard, Lionel; Broquin, Jean-Emmanuel

    2008-02-01

    In the mid 80's, the doping of optical fiber's core with rare earth atoms has been a major breakthrough in the field of optical telecommunications since it allowed the realization of in-line optical amplifiers. However, erbium-doped fiber amplifiers are a few meters long and a huge effort has been made in order to realize compact and efficient active devices based on rare-earth-doped waveguides. For this purpose the use of phosphate glasses instead of silicate ones has been investigated because they allow a better solubility of the inserted rare earths. In this paper we present the realization of a hybrid Neodymium-doped passively Q-switched waveguide laser made by ion exchange on a Schott IOG-1 phosphate laser glass combined with the deposition of a BDN saturable absorber diluted in a cellulose acetate polymer cladding. In a first step, we present the CW operation of the laser with an undoped cladding. We show that for a 3.5-μm wide, 1.4-cm long waveguide realized by a silver-sodium ion exchange, a 6 mW output has been achieved by creating a Fabry-Perot cavity with dielectric multilayers mirrors sticked to the chip facets. Then, the characterizations performed on the BDN doped layers are presented. It is shown that a proper selection of the hybrid guiding structure and saturable absorber concentration entail an excess absorption ranging from 1 to 10 dB/cm at zero flux. Finally, results on Q-switched behavior are presented. Optical pulse duration of 2-ns (FWHM) was obtained with repetition rates ranging from 5 to around 50 kHz for a 22 W pulse peak power.

  16. Effect of halide-mixing on the switching behaviors of organic-inorganic hybrid perovskite memory

    PubMed Central

    Hwang, Bohee; Gu, Chungwan; Lee, Donghwa; Lee, Jang-Sik

    2017-01-01

    Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3−xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3−xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3−xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3−xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br− (0.23 eV) than for I− (0.29–0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film. PMID:28272547

  17. Torquemeter With Variable Reluctance Transducer

    NASA Astrophysics Data System (ADS)

    Gonzalez, Julio

    1987-01-01

    A new variable reluctance transducer is described. Two static coils constitute two branches of a Wheastone bridge. The magnetic circuit of each one of the windings is closed through two gear wheels attached to the shaft. These are related to each other in such a way as to leave two air gaps, each of these in front of one of the coils in the stator assambly. These gaps change with the torque.

  18. Domain topology and domain switching kinetics in a hybrid improper ferroelectric

    PubMed Central

    Huang, F. -T.; Xue, F.; Gao, B.; Wang, L. H.; Luo, X.; Cai, W.; Lu, X. -Z.; Rondinelli, J. M.; Chen, L. Q.; Cheong, S. -W.

    2016-01-01

    Charged polar interfaces such as charged ferroelectric walls or heterostructured interfaces of ZnO/(Zn,Mg)O and LaAlO3/SrTiO3, across which the normal component of electric polarization changes suddenly, can host large two-dimensional conduction. Charged ferroelectric walls, which are energetically unfavourable in general, were found to be mysteriously abundant in hybrid improper ferroelectric (Ca,Sr)3Ti2O7 crystals. From the exploration of antiphase boundaries in bilayer-perovskites, here we discover that each of four polarization-direction states is degenerate with two antiphase domains, and these eight structural variants form a Z4 × Z2 domain structure with Z3 vortices and five distinct types of domain walls, whose topology is directly relevant to the presence of abundant charged walls. We also discover a zipper-like nature of antiphase boundaries, which are the reversible creation/annihilation centres of pairs of two types of ferroelectric walls (and also Z3-vortex pairs) in 90° and 180° polarization switching. Our results demonstrate the unexpectedly rich nature of hybrid improper ferroelectricity. PMID:27215944

  19. Domain topology and domain switching kinetics in a hybrid improper ferroelectric.

    PubMed

    Huang, F-T; Xue, F; Gao, B; Wang, L H; Luo, X; Cai, W; Lu, X-Z; Rondinelli, J M; Chen, L Q; Cheong, S-W

    2016-05-24

    Charged polar interfaces such as charged ferroelectric walls or heterostructured interfaces of ZnO/(Zn,Mg)O and LaAlO3/SrTiO3, across which the normal component of electric polarization changes suddenly, can host large two-dimensional conduction. Charged ferroelectric walls, which are energetically unfavourable in general, were found to be mysteriously abundant in hybrid improper ferroelectric (Ca,Sr)3Ti2O7 crystals. From the exploration of antiphase boundaries in bilayer-perovskites, here we discover that each of four polarization-direction states is degenerate with two antiphase domains, and these eight structural variants form a Z4 × Z2 domain structure with Z3 vortices and five distinct types of domain walls, whose topology is directly relevant to the presence of abundant charged walls. We also discover a zipper-like nature of antiphase boundaries, which are the reversible creation/annihilation centres of pairs of two types of ferroelectric walls (and also Z3-vortex pairs) in 90° and 180° polarization switching. Our results demonstrate the unexpectedly rich nature of hybrid improper ferroelectricity.

  20. A dual-channel flux-switching permanent magnet motor for hybrid electric vehicles

    NASA Astrophysics Data System (ADS)

    Hua, Wei; Wu, Zhongze; Cheng, Ming; Wang, Baoan; Zhang, Jianzhong; Zhou, Shigui

    2012-04-01

    The flux-switching permanent magnet (FSPM) motor is a relatively novel brushless machine having both magnets and concentrated windings in the stator, which exhibits inherently sinusoidal PM flux-linkage, back-EMF waveforms, and high torque capability. However, in the application of hybrid electric vehicles, it is essential to prevent magnets and armature windings moving in radial direction due to the possible vibration during operation, and to ensure fault-tolerant capability. Hence, in this paper based on an original FSPM motor, a dual-channel FSPM (DC-FSPM) motor with modified structure to fix both armature windings and magnets and improved reliability is proposed for a practical 10 kW integral starter/generator (ISG) in hybrid electric vehicles. The influences of different solutions and the end-effect on the static characteristics, are evaluated based on the 2D and 3D finite element analysis, respectively. Finally, both the predicted and experimental results, compared with a prototype DC-FSPM motor and an interior PM motor used in Honda Civic, confirm that the more sinusoidal back-EMF waveform and lower torque ripple can be achieved in the DC-FSPM motor, whereas the torque is smaller under the same coil current.

  1. Modulation Extension Control of Hybrid Cascaded H-Bridge Multilevel Converters with 7-Level Fundamental Frequency Switching Scheme

    SciTech Connect

    Du, Zhong; Ozpineci, Burak; Tolbert, Leon M

    2007-01-01

    This paper presents a modulation extension control algorithm for hybrid cascaded H-bridge multilevel converters. The hybrid cascaded H-bridge multilevel motor drive using only a single DC source for each phase is promising for high power motor drive applications since it can greatly decrease the number of required DC power supplies, has high quality output power due to its high number of output levels, and has high conversion efficiency and low thermal stress by using fundamental frequency switching scheme. But one disadvantage of the 7-level fundamental frequency switching scheme is that its modulation index range is too narrow when capacitor's voltage balance is maintained. The proposed modulation extension control algorithm can greatly increase capacitors' charging time and decrease the capacitors' discharging time by injecting triplen harmonics to extend the modulation index range of the hybrid cascaded H-bridge multilevel converters.

  2. Optimization of a Small Scale Linear Reluctance Accelerator

    NASA Astrophysics Data System (ADS)

    Barrera, Thor; Beard, Robby

    2011-11-01

    Reluctance accelerators are extremely promising future methods of transportation. Several problems still plague these devices, most prominently low efficiency. Variables to overcoming efficiency problems are many and difficult to correlate how they affect our accelerator. The study examined several differing variables that present potential challenges in optimizing the efficiency of reluctance accelerators. These include coil and projectile design, power supplies, switching, and the elusive gradient inductance problem. Extensive research in these areas has been performed from computational and theoretical to experimental. Findings show that these parameters share significant similarity to transformer design elements, thus general findings show current optimized parameters the research suggests as a baseline for further research and design. Demonstration of these current findings will be offered at the time of presentation.

  3. Investigation of DC hybrid circuit breaker based on high-speed switch and arc generator.

    PubMed

    Wu, Yifei; Rong, Mingzhe; Wu, Yi; Yang, Fei; Li, Mei; Zhong, Jianying; Han, Guohui; Niu, Chunping; Hu, Yang

    2015-02-01

    A new design of DC hybrid circuit breaker based on high-speed switch (HSS) and arc generator (AG), which can drastically profit from low heat loss in normal state and fast current breaking under fault state, is presented and analyzed in this paper. AG is designed according to the magnetic pinch effect of liquid metal. By utilizing the arc voltage generated across AG, the fault current is rapidly commutated from HSS into parallel connected branch. As a consequence, the arcless open of HSS is achieved. The post-arc conducting resume time (Δ tc) of AG and the commutation original voltage (Uc), two key factors in the commutation process, are investigated experimentally. Particularly, influences of the liquid metal channel diameter (Φ) of AG, fault current rate of rise (di/dt) and Uc on Δ tc are focused on. Furthermore, a suitable Uc is determined during the current commutation process, aiming at the reliable arcless open of HSS and short breaking time. Finally, the fault current breaking test is carried out for the current peak value of 11.8 kA, and the validity of the design is confirmed by the experimental results.

  4. Fabrication and test of nano crossbar switches/MOSFET hybrid circuits by imprinting lithography

    NASA Astrophysics Data System (ADS)

    Li, Zhiyong; Li, Xuema; Ohlberg, Douglas A. A.; Straznicky, Joseph; Wu, Wei; Yu, Zhaoning; Borghetti, Julien; Tong, William; Stewart, Duncan; Williams, R. Stanley

    2008-03-01

    An integrated circuit combining imprinted, nanoscale crossbar switches with metal-oxide field effect transistors (MOSFET) was fabricated and tested. Construction of the circuits began with fabrication of n-channel MOSFET devices on silicon-on-insulator (SOI) substrates using CMOS compatible process techniques. To protect the FET devices as well as provide a flat surface for subsequent nanoimprint lithography, passivation and planarization layers were deposited. Crossbar junctions were then fabricated next to the FETs using imprint lithography to first define arrays of parallel nanowires over which, a switchable material layer was deposited. This was followed by a second imprint proces to construct another set of parallel wires on top of, and orthogonal to the first, to complete the nano-crossbar array with a half pitch (hp) of 50 nm. The switchable crossbar devices were then connected to the gate of the FETs and the resulting integrated circuit was tested using the FET as the output signal follower. This successful fabrication process serves as a proof-of-principle demonstration and a platform for advanced CMOS/nanoscale crossbar hybrid logic circuits.

  5. Noise reduction in computed tomography scans using 3-d anisotropic hybrid diffusion with continuous switch.

    PubMed

    Mendrik, Adriënne M; Vonken, Evert-Jan; Rutten, Annemarieke; Viergever, Max A; van Ginneken, Bram

    2009-10-01

    Noise filtering techniques that maintain image contrast while decreasing image noise have the potential to optimize the quality of computed tomography (CT) images acquired at reduced radiation dose. In this paper, a hybrid diffusion filter with continuous switch (HDCS) is introduced, which exploits the benefits of three-dimensional edge-enhancing diffusion (EED) and coherence-enhancing diffusion (CED). Noise is filtered, while edges, tubular structures, and small spherical structures are preserved. From ten high dose thorax CT scans, acquired at clinical doses, ultra low dose ( 15 mAs ) scans were simulated and used to evaluate and compare HDCS to other diffusion filters, such as regularized Perona-Malik diffusion and EED. Quantitative results show that the HDCS filter outperforms the other filters in restoring the high dose CT scan from the corresponding simulated low dose scan. A qualitative evaluation was performed on filtered real low dose CT thorax scans. An expert observer scored artifacts as well as fine structures and was asked to choose one of three scans (two filtered (blinded), one unfiltered) for three different settings (trachea, lung, and mediastinal). Overall, the HDCS filtered scan was chosen most often.

  6. Conducting Ferroelectric Walls, Domain Topology, and Domain Switching Kinetics in a Hybrid Improper Ferroelectric

    NASA Astrophysics Data System (ADS)

    Cheong, Sang-Wook; Rutgers CenterEmergent Materials Team

    Charged polar interfaces such as charged ferroelectric domain walls or heterostructured interfaces of ZnO/(Zn,Mg)O and LaAlO 3 /SrTiO 3 , across which the normal component of electric polarization changes suddenly, can host large two-dimensional conduction. Charged ferroelectric domain walls can be highly conducting but energetically unfavored; however, they were found to be mysteriously abundant in hybrid improper ferroelectric (Ca,Sr) 3 Ti 2 O 7 single crystals. From the exploration of antiphase domain boundaries, which are hidden in piezoresponse force microscopy, using dark-field electron microscopy, we have explored the macroscopic topology of polarization domains and antiphase domains. We found that the macroscopic domain topology is directly responsible for the presence of charged domain walls, and is closely related with the polarization domain switching mechanism in (Ca,Sr) 3 Ti 2 O 7 . Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.

  7. Investigation of DC hybrid circuit breaker based on high-speed switch and arc generator

    NASA Astrophysics Data System (ADS)

    Wu, Yifei; Rong, Mingzhe; Wu, Yi; Yang, Fei; Li, Mei; Zhong, Jianying; Han, Guohui; Niu, Chunping; Hu, Yang

    2015-02-01

    A new design of DC hybrid circuit breaker based on high-speed switch (HSS) and arc generator (AG), which can drastically profit from low heat loss in normal state and fast current breaking under fault state, is presented and analyzed in this paper. AG is designed according to the magnetic pinch effect of liquid metal. By utilizing the arc voltage generated across AG, the fault current is rapidly commutated from HSS into parallel connected branch. As a consequence, the arcless open of HSS is achieved. The post-arc conducting resume time (Δ tc) of AG and the commutation original voltage (Uc), two key factors in the commutation process, are investigated experimentally. Particularly, influences of the liquid metal channel diameter (Φ) of AG, fault current rate of rise (di/dt) and Uc on Δ tc are focused on. Furthermore, a suitable Uc is determined during the current commutation process, aiming at the reliable arcless open of HSS and short breaking time. Finally, the fault current breaking test is carried out for the current peak value of 11.8 kA, and the validity of the design is confirmed by the experimental results.

  8. High-performance hybrid complementary logic inverter through monolithic integration of a MEMS switch and an oxide TFT.

    PubMed

    Song, Yong-Ha; Ahn, Sang-Joon Kenny; Kim, Min-Wu; Lee, Jeong-Oen; Hwang, Chi-Sun; Pi, Jae-Eun; Ko, Seung-Deok; Choi, Kwang-Wook; Park, Sang-Hee Ko; Yoon, Jun-Bo

    2015-03-25

    A hybrid complementary logic inverter consisting of a microelectromechanical system switch as a promising alternative for the p-type oxide thin film transistor (TFT) and an n-type oxide TFT is presented for ultralow power integrated circuits. These heterogeneous microdevices are monolithically integrated. The resulting logic device shows a distinctive voltage transfer characteristic curve, very low static leakage, zero-short circuit current, and exceedingly high voltage gain.

  9. Reluctant partners: Implementing federal policy

    SciTech Connect

    Stoker, R.P.

    1991-01-01

    Reluctant Partners examines how the federal government can secure the cooperation it needs to effect national policy goals whtn the implementation process itself empowers potential adversaries. The current battle over how and where to permanently store the nation's high-level nuclear waste poses one of the greatest challenges to federalism since the Civil War. Authority has been legislatively diffused among the federal government, the states, the counties, and certain affected Indian tribes. The situation also epitomizes the conflict that arises when Congress delegates final decisionmaking authority to the bureaucracy. The book contributes to the body of implementation literature by moving past organizational theory to consider issues of governance and leadership. However, it will disappoint the empiricist who sees an opportunity for the application of a theory go by the boards.

  10. Highly efficient, narrow-linewidth, and single-frequency actively and passively Q-switched fiber-bulk hybrid Er:YAG lasers operating at 1645 nm.

    PubMed

    Moskalev, Igor S; Fedorov, Vladimir V; Gapontsev, Valentin P; Gapontsev, Denis V; Platonov, Nikolai S; Mirov, Sergey B

    2008-11-24

    High power, highly efficient single frequency oscillation of Er:YAG fiber-bulk hybrid laser at 1645 nm is demonstrated in actively and passively Q-switched operation modes. The slope efficiencies in the active and passive Q-switched operation reached 75% and 20%, respectively, with the record output powers in the narrow-linewidth and single longitudinal mode regimes of operation.

  11. Turning Reluctant Learners into Inspired Learners

    ERIC Educational Resources Information Center

    Sanacore, Joseph

    2008-01-01

    Motivation is a key factor in promoting academic success, and intrinsic motivation is especially important for developing autonomous learners. Reluctant learners, in particular, benefit from intrinsic motivation that makes learning relevant to their lives. In this article, the author describes commonalities of reluctant learners and presents…

  12. Intravascular and hybrid intraoperative stent placement for baffle obstruction in transposition of the great arteries after atrial switch.

    PubMed

    Poterucha, Joseph T; Taggart, Nathaniel W; Johnson, Jonathan N; Cannon, Bryan C; Cabalka, Allison K; Hagler, Donald J; Dearani, Joseph A; Cetta, Frank

    2017-02-01

    To report our experience with intravascular and hybrid intra-operative stent placement for baffle obstruction in patients with complete transposition of the great arteries (TGA) after the atrial switch (Mustard/Senning) operation. Venous baffle obstruction is a challenging complication after atrial switch operation in patients with TGA. Traditional treatment options include intravascular stenting or surgery. A retrospective analysis of Mayo Clinic's electronic medical record was completed to identify consecutive pediatric and adult patients with TGA after atrial switch who underwent baffle stent implantation from 1994 to 2015. Overall, 64 patients were referred for cardiac catheterization, in whom 47 (73%) were noted to have hemodynamic and angiographic evidence of baffle obstruction. A total of 20 patients mean age 33 (range: 8-46) years old underwent stent implantation of baffle stenosis at a mean of 33 (range: 7.5-45) years after initial atrial switch operation (Mustard, n = 19; Senning, n = 1). Overall, 27 baffles were stented in 20 patients via the following approaches: intravascular (17); hybrid surgical (3); staged intravascular & hybrid (2). Sites of stent placement were: superior vena cava (SVC) (13); inferior vena cava (IVC) (9); pulmonary venous baffle (5). Three patients had stent placement in the SVC and IVC baffles during the same procedure. Procedural adverse events occurred in 2/22 cases (9%) including creation of unintentional baffle leak (n = 1) and stent migration (n = 1). There was no procedure-related mortality. At follow-up (median 2, range 0.02-10 years), significantly improved NYHA class and mean Doppler baffle gradient were demonstrated (P < 0.05). Mild baffle re-stenosis (mean Doppler gradient; 2-3 mmHg) occurred in two patients who have not required re-intervention. Trivial baffle leak was noted in four patients. Baffle re-intervention was only occurred in one patient. One patient with pre-procedural Class IV symptoms

  13. Mathematical Modelling and Parameter Determination of Reluctance Synchronous Motor with Squirrel Cage

    NASA Astrophysics Data System (ADS)

    Hudák, Peter; Hrabovcová, Valéria

    2010-11-01

    The paper provides an analysis of reluctance synchronous motor (RSM) with asymmetrical rotor cage. Its performances during its starting up is investigated. A mathematical model is created on the basis of detailed investigation of model parameters. The RSM starting up by switching it directly across the line was simulated and verified by measurements.

  14. Electronic interaction and bipolar resistive switching in copper oxide-multilayer graphene hybrid interface: Graphene as an oxygen ion storage and blocking layer

    NASA Astrophysics Data System (ADS)

    Singh, Bharti; Mehta, B. R.; Govind, Feng, X.; Müllen, Klaus

    2011-11-01

    This study reports a bipolar resistive switching device based on copper oxide (CuO)-multilayer graphene (MLG) hybrid interface in complete contrast to the ohmic and rectifying characteristics of junctions based on individual MLG and CuO layers. The observed shift and the occurrence of additional O1s, Cu2p, and C1s core level peaks indicate electronic interaction at the hybrid interfacial layer. Large changes in the resistive switching parameters on changing the ambient conditions from air to vacuum establish the important role of MLG as oxygen ion storage and blocking layer towards the observed resistive switching effect.

  15. Rotor position sensor switches currents in brushless dc motors

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Reluctance switch incorporated in an induction motor is used for sensing rotor position and switching armature circuits in a brushless dc motor. This device drives the solar array system of an unmanned space satellite.

  16. Variable reluctance proximity sensors for cryogenic valve position indication

    NASA Technical Reports Server (NTRS)

    Cloyd, R. A.

    1982-01-01

    A test was conducted to determine the performance of a variable reluctance proximity sensor system when installed in a space shuttle external tank vent/relief valve. The sensors were used as position indicators. The valve and sensors were cycled through a series of thermal transients; while the valve was being opened and closed pneumatically, the sensor's performance was being monitored. During these thermal transients, the vent valve was cooled ten times by liquid nitrogen and two times by liquid hydrogen. It was concluded that the sensors were acceptable replacements for the existing mechanical switches. However, the sensors need a mechanical override for the target similar to what is presently used with the mechanical switches. This override could insure contact between sensor and target and eliminate any problems of actuation gap growth caused by thermal gradients.

  17. Time-wavelength hybrid optical CDMA system with tunable encoder/decoder using switch and fixed delay-line

    NASA Astrophysics Data System (ADS)

    Min, Seong-Sik; Yoo, Hark; Won, Yong Hyub

    2003-02-01

    A novel tunable encoding/decoding scheme based on an arrayed waveguide grating (AWG) and optical switches for time-wavelength hybrid (TWH) optical code division multiple-access (CDMA) systems is proposed. The scheme uses optical switches and fixed delay lines instead of tunable delay lines (TDLs) and utilizes the structure of the TWH optical signature sequences. The advantages of the scheme are that it can be implemented using fewer elements and that the encoded signal suffers lower loss than in those using TDLs. A TWH optical CDMA system for local area network (LAN) applications using the proposed tunable encoder and a simple fixed decoder is examined and its feasibility is experimentally verified.

  18. On the estimation of the domain of attraction for discrete-time switched and hybrid nonlinear systems

    NASA Astrophysics Data System (ADS)

    Kit Luk, Chuen; Chesi, Graziano

    2015-11-01

    This paper addresses the estimation of the domain of attraction for discrete-time nonlinear systems where the vector field is subject to changes. First, the paper considers the case of switched systems, where the vector field is allowed to arbitrarily switch among the elements of a finite family. Second, the paper considers the case of hybrid systems, where the state space is partitioned into several regions described by polynomial inequalities, and the vector field is defined on each region independently from the other ones. In both cases, the problem consists of computing the largest sublevel set of a Lyapunov function included in the domain of attraction. An approach is proposed for solving this problem based on convex programming, which provides a guaranteed inner estimate of the sought sublevel set. The conservatism of the provided estimate can be decreased by increasing the size of the optimisation problem. Some numerical examples illustrate the proposed approach.

  19. Finding Hooks to Catch Reluctant Readers.

    ERIC Educational Resources Information Center

    Grimes, Marijo

    1991-01-01

    Discusses a list of books of varying lengths and difficulty that the reading teacher can use to help reluctant readers find that all-important breakthrough book to discover what reading can do for them. (KEH)

  20. Area-efficient nonvolatile carry chain based on pass-transistor/atom-switch hybrid logic

    NASA Astrophysics Data System (ADS)

    Bai, Xu; Tsuji, Yukihide; Sakamoto, Toshitsugu; Morioka, Ayuka; Miyamura, Makoto; Tada, Munehiro; Banno, Naoki; Okamoto, Koichiro; Iguchi, Noriyuki; Hada, Hiromitsu

    2016-04-01

    For the first time, an area-efficient nonvolatile carry chain combining look-up tables and a pass-transistor-logic-based adder is newly developed using complementary atom switches without additional CMOS circuits. A proposed tristate switch composed of three pairs of complementary atom switches selects one of “0”, “1”, and the “carry_in” signal as the input of a common multiplexer for both a look-up table and an adder. The developed nonvolatile carry chain achieves the reductions of 20% area, 17% delay, and 17% power consumption, respectively, in comparison with a conventional nonvolatile carry chain using dedicated CMOS gates.

  1. 16,000-rpm Interior Permanent Magnet Reluctance Machine with Brushless Field Excitation

    SciTech Connect

    Hsu, J.S.; Burress, T.A.; Lee, S.T.; Wiles, R.H.; Coomer, C.L.; McKeever, J.W.; Adams, D.J.

    2007-10-31

    The reluctance interior permanent magnet (RIPM) motor is currently used by many leading auto manufacturers for hybrid vehicles. The power density for this type of motor is high compared with that of induction motors and switched reluctance motors. The primary drawback of the RIPM motor is the permanent magnet (PM) because during high-speed operation, the fixed PM produces a huge back electromotive force (emf) that must be reduced before the current will pass through the stator windings. This reduction in back-emf is accomplished with a significant direct-axis (d-axis) demagnetization current, which opposes the PM's flux to reduce the flux seen by the stator wires. This may lower the power factor and efficiency of the motor and raise the requirement on the alternate current (ac) power supply; consequently, bigger inverter switching components, thicker motor winding conductors, and heavier cables are required. The direct current (dc) link capacitor is also affected when it must accommodate heavier harmonic currents. It is commonly agreed that, for synchronous machines, the power factor can be optimized by varying the field excitation to minimize the current. The field produced by the PM is fixed and cannot be adjusted. What can be adjusted is reactive current to the d-axis of the stator winding, which consumes reactive power but does not always help to improve the power factor. The objective of this project is to avoid the primary drawbacks of the RIPM motor by introducing brushless field excitation (BFE). This offers both high torque per ampere (A) per core length at low speed by using flux, which is enhanced by increasing current to a fixed excitation coil, and flux, which is weakened at high speed by reducing current to the excitation coil. If field weakening is used, the dc/dc boost converter used in a conventional RIPM motor may be eliminated to reduce system costs. However, BFE supports a drive system with a dc/dc boost converter, because it can further extend

  2. Design study and performance analysis of 12S-14P field excitation flux switching motor for hybrid electric vehicle

    NASA Astrophysics Data System (ADS)

    Husin, Zhafir Aizat; Sulaiman, Erwan; Khan, Faisal; Mazlan, Mohamed Mubin Aizat; Othman, Syed Muhammad Naufal Syed

    2015-05-01

    This paper presents a new structure of 12slot-14pole field excitation flux switching motor (FEFSM) as an alternative candidate of non-Permanent Magnet (PM) machine for HEV drives. Design study, performance analysis and optimization of field excitation flux switching machine with non-rare-earth magnet for hybrid electric vehicle drive applications is done. The stator of projected machine consists of iron core made of electromagnetic steels, armature coils and field excitation coils as the only field mmf source. The rotor is consisted of only stack of iron and hence, it is reliable and appropriate for high speed operation. The design target is a machine with the maximum torque, power and power density, more than 210Nm, 123kW and 3.5kW/kg, respectively, which competes with interior permanent magnet synchronous machine used in existing hybrid electric vehicle. Some design feasibility studies on FEFSM based on 2D-FEA and deterministic optimization method will be applied to design the proposed machine.

  3. A hybrid optical switch architecture to integrate IP into optical networks to provide flexible and intelligent bandwidth on demand for cloud computing

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Hall, Trevor J.

    2013-12-01

    The Internet is entering an era of cloud computing to provide more cost effective, eco-friendly and reliable services to consumer and business users. As a consequence, the nature of the Internet traffic has been fundamentally transformed from a pure packet-based pattern to today's predominantly flow-based pattern. Cloud computing has also brought about an unprecedented growth in the Internet traffic. In this paper, a hybrid optical switch architecture is presented to deal with the flow-based Internet traffic, aiming to offer flexible and intelligent bandwidth on demand to improve fiber capacity utilization. The hybrid optical switch is capable of integrating IP into optical networks for cloud-based traffic with predictable performance, for which the delay performance of the electronic module in the hybrid optical switch architecture is evaluated through simulation.

  4. Electric field control of deterministic current-induced magnetization switching in a hybrid ferromagnetic/ferroelectric structure

    NASA Astrophysics Data System (ADS)

    Cai, Kaiming; Yang, Meiyin; Ju, Hailang; Wang, Sumei; Ji, Yang; Li, Baohe; Edmonds, Kevin William; Sheng, Yu; Zhang, Bao; Zhang, Nan; Liu, Shuai; Zheng, Houzhi; Wang, Kaiyou

    2017-07-01

    All-electrical and programmable manipulations of ferromagnetic bits are highly pursued for the aim of high integration and low energy consumption in modern information technology. Methods based on the spin-orbit torque switching in heavy metal/ferromagnet structures have been proposed with magnetic field, and are heading toward deterministic switching without external magnetic field. Here we demonstrate that an in-plane effective magnetic field can be induced by an electric field without breaking the symmetry of the structure of the thin film, and realize the deterministic magnetization switching in a hybrid ferromagnetic/ferroelectric structure with Pt/Co/Ni/Co/Pt layers on PMN-PT substrate. The effective magnetic field can be reversed by changing the direction of the applied electric field on the PMN-PT substrate, which fully replaces the controllability function of the external magnetic field. The electric field is found to generate an additional spin-orbit torque on the CoNiCo magnets, which is confirmed by macrospin calculations and micromagnetic simulations.

  5. The role of oxygen vacancies in resistive switching behavior of organic-TiO2 hybrid composite

    NASA Astrophysics Data System (ADS)

    Zhang, Jiahua; Chen, Da; Huang, Shihua

    2017-10-01

    Effects of polyethylene glycol (PEG) on resistive switching behaviors and mechanisms in organic-TiO2 hybrid composites were investigated. The reversed current-voltage curves in the negative bias during the initial voltage sweeps were first observed in the composites annealed at 150, 200 and 250 °C, which is ascribed to the accumulation of oxygen vacancies and the inhibition effect of polarities of PEG chains. In addition, the volatility of composites with relatively high content of PEG is caused by the inhibition effect of PEG on creating oxygen vacancies. The formation and rupture of oxygen-vacancy filaments was considered as the resistive switching mechanism. Finally, the charging and discharging process in PEG-TiO2 composite annealed at 150 °C results in the instability of the electron-occupied oxygen vacancies and the inhibition of PEG chains. This study demonstrates a new way to investigate the interaction between polymers and TiO2 for understanding the resistive switching mechanism of TiO2-based memories.

  6. Hybrid origin of Baltic salmon-specific parasite Gyrodactylus salaris: a model for speciation by host switch for hemiclonal organisms.

    PubMed

    Kuusela, Jussi; Zietara, Marek S; Lumme, J

    2007-12-01

    Host switching explains the high species number of ectoparasitic, viviparous, mainly parthenogenetic but potentially hermaphroditic flatworms of the genus Gyrodactylus. The starlike mitochondrial phylogeny of Gyrodactylus salaris suggested parallel divergence of several clades on grayling (also named as Gyrodactylus thymalli) and an embedded sister clade on Baltic salmon. The hypothesis that the parasite switched from grayling to salmon during the glacial diaspora was tested using a 493-bp nuclear DNA marker ADNAM1. The parasites on salmon in lakes Onega and Ladoga were heterozygous for divergent ADNAM1 alleles WS1 and BS1, found as nearly fixed in grayling parasites in the White Sea and Baltic Sea basins, respectively. In the Baltic salmon-specific mtDNA clade, the WS/BS heterozygosity was maintained in 23 out of the 24 local clones. The permanently heterozygous clade was endemic in the Baltic Sea basin, and it had accumulated variation in mtDNA (31 variable sites on 1600 bp) and in the alleles of the nuclear locus (two point mutations and three nucleotide conversions along 493 bp). Mendelian shuffling of the nuclear alleles between the local clones indicated rare sex within the clade, but the WS/BS heterozygosity was lost in only one salmon hatchery clone, which was heterozygous WS1/WS3. The Baltic salmon-specific G. salaris lineage was monophyletic, descending from a single historical hybridization and consequential host switch, frozen by permanent heterozygosity. A possible time for the hybridization of grayling parasite strains from the White Sea and Baltic Sea basins was during the Eemian interglacial 132 000 years bp. Strains having a separate divergent mtDNA observed on farmed rainbow trout, and on salmon in Russian lake Kuito were suggested to be clones derived from secondary and tertiary recombination events.

  7. Stability analysis of hybrid switched nonlinear singular time-delay systems with stable and unstable subsystems

    NASA Astrophysics Data System (ADS)

    Zamani, Iman; Shafiee, Masoud; Ibeas, Asier

    2014-05-01

    The issue of exponential stability of a class of continuous-time switched nonlinear singular systems consisting of a family of stable and unstable subsystems with time-varying delay is considered in this paper. Based on the free-weighting matrix approach, the average dwell-time approach and by constructing a Lyapunov-like Krasovskii functional, delay-dependent sufficient conditions are derived and formulated to check the exponential stability of such systems in terms of linear matrix inequalities (LMIs). By checking the corresponding LMI conditions, the average dwell-time and switching signal conditions are obtained. This paper also highlights the relationship between the average dwell-time of the switched nonlinear singular time-delay system, its stability and the exponential convergence rate of differential and algebraic states. A numerical example shows the effectiveness of the proposed method.

  8. Switched-Reluctance Cryogenic Motor Tested and Upgraded

    NASA Technical Reports Server (NTRS)

    Brown, Gerald V.; Siebert, mark W.

    2005-01-01

    Pollution-free flight is one of NASA s goals for the 21st century. One method of approaching that goal is to use hydrogen-fueled aircraft that use fuel cells or turbogenerators to produce electric power to drive electric motors that turn the aircraft s propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at hydrogen s boiling point of 20.5 K (-422.5 F). The liquid hydrogen could provide essentially free refrigeration to cool electric motor windings before being used as fuel. Either superconductivity or the low resistance of pure copper or aluminum in liquid hydrogen could be applied to greatly increase electric current density and motor power density.

  9. Report 1: Basic Operation of the Switched Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Pillay, Pragasen

    1998-01-01

    Typically salient poles have windings forming coils wrapped around the waists (or pole cores) of each pole. This is true for the stator of the SRM but not for the rotor. The rotor has no windings, no coils, no magnets, no commutator, or slip rings it is only comprised of laminated steel sheets stamped in the shape of the pole design and mounted on a shaft. This allows for ease in manufacturing the rotor as well as reducing the rotor's inertia. There is also no electrical loss associated with the rotor since there are no windings, commutator, or slip rings.

  10. Ultrafast all-optical switching and error-free 10 Gbit/s wavelength conversion in hybrid InP-silicon on insulator nanocavities using surface quantum wells

    SciTech Connect

    Bazin, Alexandre; Monnier, Paul; Beaudoin, Grégoire; Sagnes, Isabelle; Raj, Rama; Lenglé, Kevin; Gay, Mathilde; Bramerie, Laurent; Braive, Rémy; Raineri, Fabrice

    2014-01-06

    Ultrafast switching with low energies is demonstrated using InP photonic crystal nanocavities embedding InGaAs surface quantum wells heterogeneously integrated to a silicon on insulator waveguide circuitry. Thanks to the engineered enhancement of surface non radiative recombination of carriers, switching time is obtained to be as fast as 10 ps. These hybrid nanostructures are shown to be capable of achieving systems level performance by demonstrating error free wavelength conversion at 10 Gbit/s with 6 mW switching powers.

  11. Bipolar resistive switching properties of Ti-CuO/(hexafluoro-hexa-peri-hexabenzocoronene)-Cu hybrid interface device: Influence of electronic nature of organic layer

    NASA Astrophysics Data System (ADS)

    Singh, Bharti; Mehta, B. R.; Varandani, Deepak; Govind; Narita, A.; Feng, X.; Müllen, K.

    2013-05-01

    This study reports the change in the structural and junction properties of Ti-CuO-Cu structure on incorporation of a 2-dimensional (2D) organic layer comprising of n-type hexafluoro-hexa-peri-hexabenzocoronene (6F-HBC). A bipolar resistive switching is observed in the device having interface between sputter deposited copper oxide (CuO) and vacuum sublimated 6F-HBC hybrid interface. The CuO/6F-HBC hybrid interface exhibits rectifying I-V characteristics in complete contrast to the ohmic and rectifying characteristics of junctions based on individual 6F-HBC and CuO layers. Large change in resistive switching property from unipolar resistive switching in CuO/HBC to bipolar resistive switching in CuO/6F-HBC interface was observed. At the CuO/6F-HBC interface, C1s peak corresponding to fluorinated carbon is shifted by 0.68 eV towards higher binding energy (BE) side and O1s peak due to non-lattice oxygen is shifted by 0.6 eV towards lower BE, confirming the interaction of O2- ion in CuO with fluorinated carbon atoms in 6F-HBC at the hybrid interface. Correlation between conductive atomic force microscopy images and atomic force microscopy topography images, I-V characteristics in conducting, non-conducting, and pristine regions along with x-ray photoelectron spectroscopy results establishes the important role of hybrid interface to determining the resistive switching properties. This study demonstrates that the resistive switching and interface properties of a hybrid device based on inorganic and organic 2D materials can be modified by changing the electronic properties of organic layer by attaching suitable functional groups.

  12. Study of the Synchronous Reluctance Motor Design

    NASA Astrophysics Data System (ADS)

    Dirba, J.; Lavrinovicha, L.; Dobriyan, R.

    2016-08-01

    The paper focuses on studying the external-rotor synchronous reluctance motor. The analysis is performed to estimate the influence of the number of stator slots and non-magnetic areas in the rotor (i.e., flux barriers) on the electromagnetic torque and torque ripple of the studied motor. It is concluded that the increase in the number of stator slots Z = 6 to Z = 18 causes an approximately twofold decrease in the ripple factor, but torque increases by 5 %. Electromagnetic torque will be increased approximately by 24 %, if non-magnetic flux barriers are created in the rotor of the studied synchronous reluctance motor.

  13. Helicity-dependent all-optical switching in hybrid metal-ferromagnet structures for ultrafast magnetic data storage

    NASA Astrophysics Data System (ADS)

    Cheng, Feng

    The emerging Big Data era demands the rapidly increasing need for speed and capacity of storing and processing information. Standalone magnetic recording devices, such as hard disk drives (HDDs), have always been playing a central role in modern data storage and continuously advancing. Recognizing the growing capacity gap between the demand and production, industry has pushed the bit areal density in HDDs to 900 Giga-bit/square-inch, a remarkable 450-million-fold increase since the invention of the first hard disk drive in 1956. However, the further development of HDD capacity is facing a pressing challenge, the so-called superparamagnetic effect, that leads to the loss of information when a single bit becomes too small to preserve the magnetization. This requires new magnetic recording technologies that can write more stable magnetic bits into hard magnetic materials. Recent research has shown that it is possible to use ultrafast laser pulses to switch the magnetization in certain types of magnetic thin films. Surprisingly, such a process does not require an externally applied magnetic field that always exists in conventional HDDs. Furthermore, the optically induced magnetization switching is extremely fast, up to sub-picosecond (10 -12 s) level, while with traditional recording method the deterministic switching does not take place shorter than 20 ps. It's worth noting that the direction of magnetization is related to the helicity of the incident laser pulses. Namely, the right-handed polarized laser pulses will generate magnetization pointing in one direction while left-handed polarized laser pulses generate magnetization pointing in the other direction. This so-called helicity-dependent all-optical switching (HD-AOS) phenomenon can be potentially used in the next-generation of magnetic storage systems. In this thesis, I explore the HD-AOS phenomenon in hybrid metal-ferromagnet structures, which consist of gold and Co/Pt multilayers. The experiment results show

  14. Voltage-Driven In-Plane Magnetization Easy Axis Switching in FeNi/Piezoelectric Actuator Hybrid Structure

    NASA Astrophysics Data System (ADS)

    Xi, Li; Guo, Xiaobin; Wang, Zhen; Li, Yue; Yao, Yuelin; Zuo, Yalu; Xue, Desheng

    2013-01-01

    FeNi thin films with the in-plane uniaxial anisotropy were fabricated by direct current magnetron sputtering. An FeNi/piezoelectric actuator hybrid structure was used to investigate the voltage-controlled magnetization switching. A theoretical calculation was performed to provide a simplified vision of the magnetoelastic contribution to the magnetic anisotropy. Magneto-optical Kerr effect measurements were performed and the rotation of the magnetization easy axis in the FeNi film upon application of a voltage with or without the application of a magnetic field was demonstrated. A film-thickness dependent in-plane magnetization easy axis rotation angle was observed and explained by the variation of the magnetostriction.

  15. Irreversible magnetization switching at the onset of superconductivity in a superconductor ferromagnet hybrid

    SciTech Connect

    Curran, P. J.; Bending, S. J.; Kim, J.; Satchell, N.; Witt, J. D. S.; Burnell, G.; Flokstra, M. G.; Lee, S. L.; Cooper, J. F. K.; Kinane, C. J.; Langridge, S.; Isidori, A.; Eschrig, M.; Pugach, N.

    2015-12-28

    We demonstrate that the magnetic state of a superconducting spin valve, that is normally controlled with an external magnetic field, can also be manipulated by varying the temperature which increases the functionality and flexibility of such structures as switching elements. In this case, switching is driven by changes in the magnetostatic energy due to spontaneous Meissner screening currents forming in the superconductor below the critical temperature. Our scanning Hall probe measurements also reveal vortex-mediated pinning of the ferromagnetic domain structure due to the pinning of quantized stray fields in the adjacent superconductor. The ability to use temperature as well as magnetic field to control the local magnetisation structure raises the prospect of potential applications in magnetic memory devices.

  16. Megawatt-level peak-power from a passively Q-switched hybrid fiber-bulk amplifier and its applications

    NASA Astrophysics Data System (ADS)

    Reiser, Axel; Bdzoch, Juraj; Höfer, Sven; Scholz-Riecke, Sina; Seitz, Daniel; Kugler, Nicolas; Genter, Peter

    2016-03-01

    A novel laser system with optical parameters that fill the gap between Q-switched and modelocked lasers has been developed. It consists of a high gain hybrid fiber-bulk amplifier seeded by a low power SESAM Q-switched oscillator. The mW level output power of the seed oscillator is preamplified by a single mode fiber which is limited by SRS effects. The final amplification stage is realized by a longitudinal pumped Nd:YVO4 crystal in a double pass setup. This MOPA configuration delivers sub-300ps pulses at repetition rates up to 1 MHz with an output power exceeding 60W. Nonlinear frequency conversion to 532nm and 355nm is achieved with efficiencies of >75% and >45%, respectively. Due to the high peak power, high repetition rate and high beam quality of this system, applications formerly only addressable at lower pulse repetition frequencies or with complex modelocked laser systems are now possible with high speed and lower cost of ownership. Application results that take benefit from these new laser parameters will be shown. Furthermore, the reduction of the pulse duration to sub-100ps and power scaling to output powers <100W by the use of the Innoslab concept are being presented.

  17. Analysis and design of asymmetrical reluctance machine

    NASA Astrophysics Data System (ADS)

    Harianto, Cahya A.

    Over the past few decades the induction machine has been chosen for many applications due to its structural simplicity and low manufacturing cost. However, modest torque density and control challenges have motivated researchers to find alternative machines. The permanent magnet synchronous machine has been viewed as one of the alternatives because it features higher torque density for a given loss than the induction machine. However, the assembly and permanent magnet material cost, along with safety under fault conditions, have been concerns for this class of machine. An alternative machine type, namely the asymmetrical reluctance machine, is proposed in this work. Since the proposed machine is of the reluctance machine type, it possesses desirable feature, such as near absence of rotor losses, low assembly cost, low no-load rotational losses, modest torque ripple, and rather benign fault conditions. Through theoretical analysis performed herein, it is shown that this machine has a higher torque density for a given loss than typical reluctance machines, although not as high as the permanent magnet machines. Thus, the asymmetrical reluctance machine is a viable and advantageous machine alternative where the use of permanent magnet machines are undesirable.

  18. Using Nooks to Hook Reluctant Readers

    ERIC Educational Resources Information Center

    Dierking, Rebecca

    2015-01-01

    This article presents the findings of a two-year qualitative study of electronic reading device use with high school sophomores, most of whom self-identified as reluctant or struggling readers. Electronic readers were used primarily in one weekly fifty-minute class period, during silent sustained reading, wherein students chose freely their texts.…

  19. Using Nooks to Hook Reluctant Readers

    ERIC Educational Resources Information Center

    Dierking, Rebecca

    2015-01-01

    This article presents the findings of a two-year qualitative study of electronic reading device use with high school sophomores, most of whom self-identified as reluctant or struggling readers. Electronic readers were used primarily in one weekly fifty-minute class period, during silent sustained reading, wherein students chose freely their texts.…

  20. Multiferroic Nanopatterned Hybrid Material with Room-Temperature Magnetic Switching of the Electric Polarization.

    PubMed

    Cai, Ronggang; Antohe, Vlad-Andrei; Hu, Zhijun; Nysten, Bernard; Piraux, Luc; Jonas, Alain M

    2017-02-01

    A nanopatterned hybrid layer is designed, wherein the electric polarization can be flipped at room temperature by a magnetic field aided by an electrical field. This is achieved by embedding ferromagnetic nanopillars in a continuous organic ferroelectric layer, and amplifying the magnetostriction-generated stress gradients by scaling down the supracrystalline cell of the material.

  1. Evolutionary restoration of fertility in an interspecies hybrid yeast, by whole-genome duplication after a failed mating-type switch

    PubMed Central

    Ortiz-Merino, Raúl A.; Kuanyshev, Nurzhan; Braun-Galleani, Stephanie; Byrne, Kevin P.; Porro, Danilo; Branduardi, Paola

    2017-01-01

    Many interspecies hybrids have been discovered in yeasts, but most of these hybrids are asexual and can replicate only mitotically. Whole-genome duplication has been proposed as a mechanism by which interspecies hybrids can regain fertility, restoring their ability to perform meiosis and sporulate. Here, we show that this process occurred naturally during the evolution of Zygosaccharomyces parabailii, an interspecies hybrid that was formed by mating between 2 parents that differed by 7% in genome sequence and by many interchromosomal rearrangements. Surprisingly, Z. parabailii has a full sexual cycle and is genetically haploid. It goes through mating-type switching and autodiploidization, followed by immediate sporulation. We identified the key evolutionary event that enabled Z. parabailii to regain fertility, which was breakage of 1 of the 2 homeologous copies of the mating-type (MAT) locus in the hybrid, resulting in a chromosomal rearrangement and irreparable damage to 1 MAT locus. This rearrangement was caused by HO endonuclease, which normally functions in mating-type switching. With 1 copy of MAT inactivated, the interspecies hybrid now behaves as a haploid. Our results provide the first demonstration that MAT locus damage is a naturally occurring evolutionary mechanism for whole-genome duplication and restoration of fertility to interspecies hybrids. The events that occurred in Z. parabailii strongly resemble those postulated to have caused ancient whole-genome duplication in an ancestor of Saccharomyces cerevisiae. PMID:28510588

  2. Hairpin DNA Switch for Ultrasensitive Spectrophotometric Detection of DNA Hybridization Based on Gold Nanoparticles and Enzyme Signal Amplification

    SciTech Connect

    Zhang, Youyu; Tang, Zhiwen; Wang, Jun; Wu, Hong; Maham, Aihui; Lin, Yuehe

    2010-08-01

    A novel DNA detection platform based on a hairpin-DNA switch, nanoparticles, and enzyme signal amplification for ultrasensitive detection of DNA hybridization has been developed in this work. In this DNA assay, a “stem-loop” DNA probe dually labeled with a thiol at its 5’ end and a biotin at its 3’ end, respectively, was used. This probe was immobilized on the gold nanoparticles (AuNPs) anchored by a protein, globulin, on a 96-well microplate. In the absence of target DNA, the immobilized probe with the stem-loop structure shields the biotin from being approached by a bulky horseradish peroxidase linked-avidin (avidin-HRP) conjugate due to the steric hindrance. However, in the presence of target DNA, the hybridization between the hairpin DNA probe and the target DNA causes significant conformational change of the probe, which forces biotin away from the surface of AuNPs. As a result, the biotin becomes accessible by the avidin-HRP, and the target hybridization event can be sensitively detected via the HRP catalyzed substrate 3, 3', 5, 5'-tetramethylbenzidine using spectrophometric method. Some experimental parameters governing the performance of the assay have been optimized. At optimal conditions, this DNA assay can detect DNA at the concentration of femtomolar level by means of a signal amplification strategy based on the combination of enzymes and nanoparticles. This approach also has shown excellent specificity to distinguish single-base mismatches of DNA targets because of the intrinsic high selectivity of the hairpin DNA probe.

  3. Study of switching electric circuits with DC hybrid breaker, one stage

    NASA Astrophysics Data System (ADS)

    Niculescu, T.; Marcu, M.; Popescu, F. G.

    2016-06-01

    The paper presents a method of extinguishing the electric arc that occurs between the contacts of direct current breakers. The method consists of using an LC type extinguishing group to be optimally sized. From this point of view is presented a theoretical approach to the phenomena that occurs immediately after disconnecting the load and the specific diagrams are drawn. Using these, the elements extinguishing group we can choose. At the second part of the paper there is presented an analyses of the circuit switching process by decomposing the process in particular time sequences. For every time interval there was conceived a numerical simulation model in MATLAB-SIMULINK medium which integrates the characteristic differential equation and plots the capacitor voltage variation diagram and the circuit dumping current diagram.

  4. Spontaneous symmetry breaking in cosmos: the hybrid symmetron as a dark energy switching device

    SciTech Connect

    Bamba, K.; Nojiri, S.; Gannouji, R.; Kamijo, M.; Sami, M. E-mail: gannouji@rs.kagu.tus.ac.jp E-mail: nojiri@phys.nagoya-u.ac.jp

    2013-07-01

    We consider symmetron model in a generalized background with a hope to make it compatible with dark energy. We observe a ''no go'' theorem at least in case of a conformal coupling. Being convinced of symmetron incapability to be dark energy, we try to retain its role for spontaneous symmetry breaking and assign the role of dark energy either to standard quintessence or F(R) theory which are switched on by symmetron field in the symmetry broken phase. The scenario reduces to standard Einstein gravity in the high density region. After the phase transition generated by symmetron field, either the F(R) gravity or the standard quintessence are induced in the low density region. we demonstrate that local gravity constraints and other requirements are satisfied although the model could generate the late-time acceleration of Universe.

  5. Characterization of a variable reluctance harvester

    NASA Astrophysics Data System (ADS)

    Kroener, M.; Moll, N.; Ravindran, S. K. T.; Mehne, P.; Woias, P.

    2014-11-01

    In our last year's PowerMEMS contribution we presented a proof-of-concept of a variable reluctance harvester for the application in a railroad surveillance system. It was shown that intermittently closing a magnetic circuit could supply power output in the range of mW's. The test setup used showed unwanted energy pickup from the electro motor used. In this paper we present thorough measurements of the reluctance circuit with a compressed air motor to exclude the effects of the above mentioned magnetic stray fields. The effects of eddy currents and moment of inertia on the output power, the optimal coil position on the stators, and effects of different magnetic field strengths are studied. The gap width is set to a fixed value of 14 mm, representing a realistic scenario.

  6. Analysis of Fault Arc in High-Speed Switch Applied in Hybrid Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Wu, Yifei; Ren, Zhigang; Feng, Ying; Li, Mei; Zhang, Hantian

    2016-03-01

    The behavior of fault arc in a high-speed switch (HSS) has been studied theoretically and experimentally. A simplified HSS setup is designed to support this work. A two-dimensional arc model is developed to analyze the characteristics of fault arc based on magnetic-hydrodynamic (MHD) theory. The advantage of such a model is that the thermal transfer coefficient can be determined by depending on the numerical method alone. The influence of net emission coefficients (NEC) radiation model and P1 model on fault arc is analyzed in detail. Results show that NEC model predicts more radiation energy and less pressure rise without the re-absorption effect considered. As a consequence, P1 model is more suitable to calculate the pressure rise caused by fault arc. Finally, the pressure rise during longer arcing time for different arc currents is predicted. supported by National Key Basic Research Program of China (973 Program) (No. 2015CB251001), National Natural Science Foundation of China (Nos. 51221005, 51177124, 51377128, 51323012), the Science and Technology Project Funds of the Grid State Corporation SGSNKYOOKJJS1501564 and Shaanxi Province Natural Science Foundation of China (No. 2013JM-7010)

  7. A hybrid EKF and switching PSO algorithm for joint state and parameter estimation of lateral flow immunoassay models.

    PubMed

    Zeng, Nianyin; Wang, Zidong; Li, Yurong; Du, Min; Liu, Xiaohui

    2012-01-01

    In this paper, a hybrid extended Kalman filter (EKF) and switching particle swarm optimization (SPSO) algorithm is proposed for jointly estimating both the parameters and states of the lateral flow immunoassay model through available short time-series measurement. Our proposed method generalizes the well-known EKF algorithm by imposing physical constraints on the system states. Note that the state constraints are encountered very often in practice that give rise to considerable difficulties in system analysis and design. The main purpose of this paper is to handle the dynamic modeling problem with state constraints by combining the extended Kalman filtering and constrained optimization algorithms via the maximization probability method. More specifically, a recently developed SPSO algorithm is used to cope with the constrained optimization problem by converting it into an unconstrained optimization one through adding a penalty term to the objective function. The proposed algorithm is then employed to simultaneously identify the parameters and states of a lateral flow immunoassay model. It is shown that the proposed algorithm gives much improved performance over the traditional EKF method.

  8. Hybrid MPI/OpenMP Implementation of the ORAC Molecular Dynamics Program for Generalized Ensemble and Fast Switching Alchemical Simulations.

    PubMed

    Procacci, Piero

    2016-06-27

    We present a new release (6.0β) of the ORAC program [Marsili et al. J. Comput. Chem. 2010, 31, 1106-1116] with a hybrid OpenMP/MPI (open multiprocessing message passing interface) multilevel parallelism tailored for generalized ensemble (GE) and fast switching double annihilation (FS-DAM) nonequilibrium technology aimed at evaluating the binding free energy in drug-receptor system on high performance computing platforms. The production of the GE or FS-DAM trajectories is handled using a weak scaling parallel approach on the MPI level only, while a strong scaling force decomposition scheme is implemented for intranode computations with shared memory access at the OpenMP level. The efficiency, simplicity, and inherent parallel nature of the ORAC implementation of the FS-DAM algorithm, project the code as a possible effective tool for a second generation high throughput virtual screening in drug discovery and design. The code, along with documentation, testing, and ancillary tools, is distributed under the provisions of the General Public License and can be freely downloaded at www.chim.unifi.it/orac .

  9. Hybrid Q-switched laser with MoS2 saturable absorber and AOM driven sub-nanosecond KTP-OPO.

    PubMed

    Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao

    2017-02-20

    Two-dimensional (2D) materials, especially transition-metal dichalcogenides, such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2), have attracted great interests due to their exceptional optical properties as saturable absorbers in laser systems. In this work, at first, we presented a diode-pumped passively Q-switched laser with MoS2 saturable absorber (MoS2-SA). At an incident pump power of 6.54 W, a maximum output power of 1.15 W with a minimum pulse duration of 70.6 ns was obtained, which is the shortest pulse duration of diode pumped passively Q-switched laser with MoS2-SA to the best of our knowledge. Then, by using a hybrid Q-switched laser with a MoS2-SA and an acousto-optic modulator (AOM) as pumping fundamental laser, a sub-nanosecond KTiOPO4 (KTP) based intracavity optical parametric oscillation (IOPO) was realized. With an incident pump power of 10.2 W and AOM repetition rate of 10 kHz, the maximum output power of 183 mW with minimum pulse duration of 850 ps was obtained. The experimental results indicate that the IOPO pumped by the hybrid Q-switched laser with AOM and MoS2-SA can generate signal wave with shorter pulse duration than those IOPOs pumped by hybrid Q-switched laser with AOM and Cr4+:YAG or single-walled carbon nanotube saturable absober (SWCNT-SA) or monolayer graphene SA.

  10. Hybrid Lead Halide Perovskites for Ultrasensitive Photoactive Switching in Terahertz Metamaterial Devices.

    PubMed

    Manjappa, Manukumara; Srivastava, Yogesh Kumar; Solanki, Ankur; Kumar, Abhishek; Sum, Tze Chien; Singh, Ranjan

    2017-08-01

    The recent meteoric rise in the field of photovoltaics with the discovery of highly efficient solar-cell devices is inspired by solution-processed organic-inorganic lead halide perovskites that exhibit unprecedented light-to-electricity conversion efficiencies. The stunning performance of perovskites is attributed to their strong photoresponsive properties that are thoroughly utilized in designing excellent perovskite solar cells, light-emitting diodes, infrared lasers, and ultrafast photodetectors. However, optoelectronic application of halide perovskites in realizing highly efficient subwavelength photonic devices has remained a challenge. Here, the remarkable photoconductivity of organic-inorganic lead halide perovskites is exploited to demonstrate a hybrid perovskite-metamaterial device that shows extremely low power photoswitching of the metamaterial resonances in the terahertz part of the electromagnetic spectrum. Furthermore, a signature of a coupled phonon-metamaterial resonance is observed at higher pump powers, where the Fano resonance amplitude is extremely weak. In addition, a low threshold, dynamic control of the highly confined electric field intensity is also observed in the system, which could tremendously benefit the new generation of subwavelength photonic devices as active sensors, low threshold optically controlled lasers, and active nonlinear devices with enhanced functionalities in the infrared, optical, and the terahertz parts of the electromagnetic spectrum. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Optoelectronic techniques for broadband switching

    NASA Astrophysics Data System (ADS)

    Su, S. F.; Jou, L.; Lenart, J.

    1988-01-01

    Optoelectronic switching employs a hybrid optical/electronic principle to perform the switching function and is applicable for either analog broadband or high-bit rate digital switching. The major advantages of optoelectronic switching include high isolation, low crosstalk, small physical size, light weight, and low power consumption. These advantages make optoelectronic switching an excellent candidate for on-board satellite switching. This paper describes a number of optoelectronic switching architectures. System components required for implementing these switching architectures are discussed. Performance of these architectures are evaluated by calculating their crosstalk, isolation, insertion loss, matrix size, drive power, throughput, and switching speed. Technologies needed for monolithic optoelectronic switching are also identified.

  12. Porous silicon-VO{sub 2} based hybrids as possible optical temperature sensor: Wavelength-dependent optical switching from visible to near-infrared range

    SciTech Connect

    Antunez, E. E.; Salazar-Kuri, U.; Estevez, J. O.; Basurto, M. A.; Agarwal, V.; Campos, J.

    2015-10-07

    Morphological properties of thermochromic VO{sub 2}—porous silicon based hybrids reveal the growth of well-crystalized nanometer-scale features of VO{sub 2} as compared with typical submicron granular structure obtained in thin films deposited on flat substrates. Structural characterization performed as a function of temperature via grazing incidence X-ray diffraction and micro-Raman demonstrate reversible semiconductor-metal transition of the hybrid, changing from a low-temperature monoclinic VO{sub 2}(M) to a high-temperature tetragonal rutile VO{sub 2}(R) crystalline structure, coupled with a decrease in phase transition temperature. Effective optical response studied in terms of red/blue shift of the reflectance spectra results in a wavelength-dependent optical switching with temperature. As compared to VO{sub 2} film over crystalline silicon substrate, the hybrid structure is found to demonstrate up to 3-fold increase in the change of reflectivity with temperature, an enlarged hysteresis loop and a wider operational window for its potential application as an optical temperature sensor. Such silicon based hybrids represent an exciting class of functional materials to display thermally triggered optical switching culminated by the characteristics of each of the constituent blocks as well as device compatibility with standard integrated circuit technology.

  13. Porous silicon-VO2 based hybrids as possible optical temperature sensor: Wavelength-dependent optical switching from visible to near-infrared range

    NASA Astrophysics Data System (ADS)

    Antunez, E. E.; Salazar-Kuri, U.; Estevez, J. O.; Campos, J.; Basurto, M. A.; Jiménez Sandoval, S.; Agarwal, V.

    2015-10-01

    Morphological properties of thermochromic VO2—porous silicon based hybrids reveal the growth of well-crystalized nanometer-scale features of VO2 as compared with typical submicron granular structure obtained in thin films deposited on flat substrates. Structural characterization performed as a function of temperature via grazing incidence X-ray diffraction and micro-Raman demonstrate reversible semiconductor-metal transition of the hybrid, changing from a low-temperature monoclinic VO2(M) to a high-temperature tetragonal rutile VO2(R) crystalline structure, coupled with a decrease in phase transition temperature. Effective optical response studied in terms of red/blue shift of the reflectance spectra results in a wavelength-dependent optical switching with temperature. As compared to VO2 film over crystalline silicon substrate, the hybrid structure is found to demonstrate up to 3-fold increase in the change of reflectivity with temperature, an enlarged hysteresis loop and a wider operational window for its potential application as an optical temperature sensor. Such silicon based hybrids represent an exciting class of functional materials to display thermally triggered optical switching culminated by the characteristics of each of the constituent blocks as well as device compatibility with standard integrated circuit technology.

  14. Wireless Energy Transfer Through Magnetic Reluctance Coupling

    NASA Astrophysics Data System (ADS)

    Pillatsch, P.

    2014-11-01

    Energy harvesting from human motion for body worn or implanted devices faces the problem of the wearer being still, e.g. while asleep. Especially for medical devices this can become an issue if a patient is bed-bound for prolonged periods of time and the internal battery of a harvesting system is not recharged. This article introduces a mechanism for wireless energy transfer based on a previously presented energy harvesting device. The internal rotor of the energy harvester is made of mild steel and can be actuated through a magnetic reluctance coupling to an external motor. The internal piezoelectric transducer is consequently actuated and generates electricity. This paper successfully demonstrates energy transfer over a distance of 16 mm in air and an achieved power output of 85 μW at 25 Hz. The device functional volume is 1.85 cm3. Furthermore, it was demonstrated that increasing the driving frequency beyond 25 Hz did not yield a further increase in power output. Future research will focus on improving the reluctance coupling, e.g. by investigating the use of multiple or stronger magnets, in order to increase transmission distance.

  15. Evaluation of performance of a hybrid electro-optic directional coupler and a Mach-Zehnder switch

    NASA Astrophysics Data System (ADS)

    Nitiss, Edgars

    2017-01-01

    The efficiency of an electro-optic (EO) directional coupler (DC) and a Mach-Zehnder (MZ) switch is discussed. The specific designs employ a passive waveguide core and an EO cladding. The performance of a DC switch was evaluated by numerical methods, namely coupled mode theory (CMT), eigenmode expansion (EME) method, and beam envelope method. Using the CMT and EME methods, it is shown that in the DC with a passive waveguide core and EO cladding at certain waveguide parameters the switching effect does not take place. The effect is demonstrated for the first time and suggests that careful optimization of the DC switch should be done before experimental realization of the device. The efficiency of an optimized DC switch is shown to be of an order lower than that of an MZ switch.

  16. Resistive Switching in All-Printed, Flexible and Hybrid MoS2-PVA Nanocomposite based Memristive Device Fabricated by Reverse Offset

    NASA Astrophysics Data System (ADS)

    Rehman, Muhammad Muqeet; Siddiqui, Ghayas Uddin; Gul, Jahan Zeb; Kim, Soo-Wan; Lim, Jong Hwan; Choi, Kyung Hyun

    2016-11-01

    Owing to the increasing interest in the nonvolatile memory devices, resistive switching based on hybrid nanocomposite of a 2D material, molybdenum disulphide (MoS2) and polyvinyl alcohol (PVA) is explored in this work. As a proof of concept, we have demonstrated the fabrication of a memory device with the configuration of PET/Ag/MoS2-PVA/Ag via an all printed, hybrid, and state of the art fabrication approach. Bottom Ag electrodes, active layer of hybrid MoS2-PVA nanocomposite and top Ag electrode are deposited by reverse offset, electrohydrodynamic (EHD) atomization and electrohydrodynamic (EHD) patterning respectively. The fabricated device displayed characteristic bistable, nonvolatile and rewritable resistive switching behavior at a low operating voltage. A decent off/on ratio, high retention time, and large endurance of 1.28 × 102, 105 sec and 1000 voltage sweeps were recorded respectively. Double logarithmic curve satisfy the trap controlled space charge limited current (TCSCLC) model in high resistance state (HRS) and ohmic model in low resistance state (LRS). Bendability test at various bending diameters (50-2 mm) for 1500 cycles was carried out to show the mechanical robustness of fabricated device.

  17. Calcium phosphate-based organic-inorganic hybrid nanocarriers with pH-responsive on/off switch for photodynamic therapy.

    PubMed

    Nomoto, Takahiro; Fukushima, Shigeto; Kumagai, Michiaki; Miyazaki, Kozo; Inoue, Aki; Mi, Peng; Maeda, Yoshinori; Toh, Kazuko; Matsumoto, Yu; Morimoto, Yuji; Kishimura, Akihiro; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2016-05-26

    Photodynamic therapy (PDT) is a promising treatment modality for malignant tumors in a light-selective manner. To improve the PDT efficacy, numerous kinds of nanocarriers have been developed to deliver photosensitizers (PSs) selectively into the tumor through leaky tumor-associated vasculature. However, the corresponding prolonged retention of the nanocarrier in the bloodstream may lead to unfavorable photochemical damage to normal tissues such as skin. Here, we report an organic-inorganic hybrid nanocarrier with a pH-responsive on/off switch of PDT efficacy. This hybrid nanocarrier is constructed by hydrothermal synthesis after simple mixing of calcium/phosphate ions, chlorin e6 (amphiphilic low molecular weight PS), and poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAsp) copolymers in an aqueous solution. The hybrid nanocarrier possesses a calcium phosphate (CaP) core encapsulating the PSs, which is surrounded by a PEG shielding layer. Under physiological conditions (pH 7.4), the nanocarrier suppressed the photochemical activity of PS by lowering the access of oxygen molecules to the incorporated PS, while PDT efficacy was restored in a pH-responsive manner because of the dissolution of CaP and eventual recovery of access between the oxygen and the PS. Owing to this switch, the nanocarrier reduced the photochemical damage in the bloodstream, while it induced effective PDT efficacy inside the tumor cell in response to the acidic conditions of the endo-/lysosomes.

  18. Resistive Switching in All-Printed, Flexible and Hybrid MoS2-PVA Nanocomposite based Memristive Device Fabricated by Reverse Offset

    PubMed Central

    Rehman, Muhammad Muqeet; Siddiqui, Ghayas Uddin; Gul, Jahan Zeb; Kim, Soo-Wan; Lim, Jong Hwan; Choi, Kyung Hyun

    2016-01-01

    Owing to the increasing interest in the nonvolatile memory devices, resistive switching based on hybrid nanocomposite of a 2D material, molybdenum disulphide (MoS2) and polyvinyl alcohol (PVA) is explored in this work. As a proof of concept, we have demonstrated the fabrication of a memory device with the configuration of PET/Ag/MoS2-PVA/Ag via an all printed, hybrid, and state of the art fabrication approach. Bottom Ag electrodes, active layer of hybrid MoS2-PVA nanocomposite and top Ag electrode are deposited by reverse offset, electrohydrodynamic (EHD) atomization and electrohydrodynamic (EHD) patterning respectively. The fabricated device displayed characteristic bistable, nonvolatile and rewritable resistive switching behavior at a low operating voltage. A decent off/on ratio, high retention time, and large endurance of 1.28 × 102, 105 sec and 1000 voltage sweeps were recorded respectively. Double logarithmic curve satisfy the trap controlled space charge limited current (TCSCLC) model in high resistance state (HRS) and ohmic model in low resistance state (LRS). Bendability test at various bending diameters (50-2 mm) for 1500 cycles was carried out to show the mechanical robustness of fabricated device. PMID:27811977

  19. Modeling Reluctance-Assisted PM Motors

    SciTech Connect

    Otaduy, P.J.

    2006-01-13

    This report contains a derivation of the fundamental equations used to calculate the base speed, torque delivery, and power output of a reluctance-assisted PM motor which has a saliency ratio greater than 1 as a function of its terminal voltage, current, voltage-phase angle, and current-phase angle. The equations are applied to model Motor X using symbolically-oriented methods with the computer tool Mathematica to determine: (1) the values of current-phase angle and voltage-phase angle that are uniquely determined once a base speed has been selected; (2) the attainable current in the voltage-limited region above base speed as a function of terminal voltage, speed, and current-phase angle; (3) the attainable current in the voltage-limited region above base speed as a function of terminal voltage, speed, and voltage-phase angle; (4) the maximum-power output in the voltage-limited region above base speed as a function of speed; (5) the optimal voltage-phase angle in the voltage-limited region above base speed required to obtain maximum-power output; (6) the maximum-power speed curve which was linear from rest to base speed in the current limited region below base speed; (7) the current angle as a function of saliency ratio in the current-limited region below base speed; and (8) the torque as a function of saliency ratio which is almost linear in the current-limited region below base speed. The equations were applied to model Motor X using numerically-oriented methods with the computer tool LabVIEW. The equations were solved iteratively to find optimal current and voltage angles that yield maximum power and maximum efficiency from rest through the current-limited region to base speed and then through the voltage-limited region to high-rotational speeds. Currents, voltages, and reluctance factors were all calculated and external loops were employed to perform additional optimization with respect to PM pitch angle (magnet fraction) and with respect to magnet strength

  20. The reluctant imperialism of the medical profession.

    PubMed

    de Swaan, A

    1989-01-01

    Medical authority is invoked ever more frequently, also in situations that are outside the scope of scientific medicine. The main but latent function of this medicalization is the resolution of social conflict. This occurs more often than not in tacit collusion between a work organization (or the wider community) on the one hand, the individualized 'patient' on the other hand and the doctor as the arbiter who defines socially contested issues in terms of medical problems. As scientific medicine provides insufficient justification of these medical interventions, they threaten to become the subject of open controversy within the organized medical profession and thus to undermine professional unanimity, and with it the authority of the profession as a whole. This explains the reluctance of organized medicine to claim these new fields as its legitimate province.

  1. Stabilization of large space structures by linear reluctance actuators

    NASA Technical Reports Server (NTRS)

    Biswas, Saroj K.; Sendaula, Henry M.

    1991-01-01

    Application of magnetic forces are considered for stabilization of vibrations of flexible space structures. Three electromagnetic phenomena are studied, such as: (1) magnetic body force; (2) reluctance torque; and (3) magnetostriction, and their application is analyzed for stabilization of a beam. The magnetic body force actuator uses the force that exists between poles of magnets. The reluctance actuator is configured in such a way that the reluctance of the magnetic circuit will be minimum when the beam is straight. Any bending of the beam increases the reluctance and hence generates a restoring torque that reduces bending. The gain of the actuator is controlled by varying the magnetizing current. Since the energy density of a magnetic device is much higher compared to piezoelectric or thermal actuators, it is expected that the reluctance actuator will be more effective in controlling the structural vibrations.

  2. A Global Sliding-Mode Control Scheme with Adjustable Robustness for A Linear Variable Reluctance Motor

    NASA Astrophysics Data System (ADS)

    Lin, Jin-Yuan; Lu, Yu-Sheng; Chen, Jian-Shiang

    A novel global sliding-mode control (GSMC) scheme with adjustable robustness is presented in this article. The proposed scheme offers a switching function together with unperturbed system dynamics to weigh the contribution from SMC such that all of the closed-loop poles can be located within predefined regions to provide design flexibility, and the robustness of system can thus be adjusted. By this scheme, the maximal control effort and chattering level can be reduced according to designer's specifications directly. Since the switching function can initially be made to equal to zero, the adjustable performance during the entire response can be guaranteed, and the reaching condition is thus lifted. The efficacy of this scheme is demonstrated via successful implementation on a linear variable reluctance motor (LVRM) servo system. Both simulation and experimental studies further demonstrate its feasibility and effectiveness.

  3. Ag/GeSx/Pt-based complementary resistive switches for hybrid CMOS/Nanoelectronic logic and memory architectures

    NASA Astrophysics Data System (ADS)

    van den Hurk, Jan; Havel, Viktor; Linn, Eike; Waser, Rainer; Valov, Ilia

    2013-10-01

    Complementary resistive switches based on two anti-serially connected Ag/GeSx/Pt devices were studied. The main focus was placed on the pulse mode properties as typically required in memory and logic applications. A self-designed measurement setup was applied to access each CRS part-cell individually. Our findings reveal the existence of two distinct read voltage regimes enabling both spike read as well as level read approaches. Furthermore, we experimentally verified the theoretically predicted kinetic properties in terms of pulse height vs. switching time relationship. The results obtained by this alternative approach allow a significant improvement of the basic understanding of the interplay between the two part-cells in a complementary resistive switch configuration. Furthermore, from these observations we can deduce a simplified write voltage scheme which is applicable for the considered type of memory cell.

  4. Improved variable-reluctance transducer measures transient pressures

    NASA Technical Reports Server (NTRS)

    Morton, R. W.; Patterson, J. L.

    1964-01-01

    A flush-diaphragm pickup and a feedback stabilized carrier amplifier are among the features incorporated into an improved variable-reluctance transducer. This low impedance device responds to steady-state as well as transient pressures.

  5. Novel Hybrid Materials with High Stability for Electrically Switched Ion Exchange: Carbon Nanotubes/Polyaniline/Nickel Hexacyanoferrate Nanocomposites

    SciTech Connect

    Lin, Yuehe; Cui, Xiaoli

    2005-04-21

    A novel and stable carbon nanotubes /polyaniline /nickel hexacyanoferrates composite film has been synthesized with electrodeposition method, and the possibility for removing cesium through an electrically switched ion exchange has been evaluated in a mixture containing NaNO3 and CsNO3.

  6. Optical switch using Risley prisms

    DOEpatents

    Sweatt, William C.; Christenson, Todd R.

    2003-04-15

    An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

  7. Optical Switch Using Risley Prisms

    DOEpatents

    Sweatt, William C.; Christenson, Todd R.

    2005-02-22

    An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

  8. Analysis of drugs in plasma samples from schizophrenic patients by column-switching liquid chromatography-tandem mass spectrometry with organic-inorganic hybrid cyanopropyl monolithic column.

    PubMed

    Domingues, Diego Soares; Souza, Israel Donizeti de; Queiroz, Maria Eugênia Costa

    2015-07-01

    This study reports on the development of a rapid, selective, and sensitive column-switching liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze sixteen drugs (antidepressants, anticonvulsants, anxiolytics, and antipsychotics) in plasma samples from schizophrenic patients. The developed organic-inorganic hybrid monolithic column with cyanopropyl groups was used for the first dimension of the column-switching arrangement. This arrangement enabled online pre-concentration of the drugs (monolithic column) and their subsequent analytical separation on an XSelect SCH C18 column. The drugs were detected on a triple quadrupole tandem mass spectrometer (multiple reactions monitoring mode) with an electrospray ionization source in the positive ion mode. The developed method afforded adequate linearity for the sixteen target drugs; the coefficients of determination (R(2)) lay above 0.9932, the interassay precision had coefficients of variation lower than 6.5%, and the relative standard error values of the accuracy ranged from -14.0 to 11.8%. The lower limits of quantification in plasma samples ranged from 63 to 1250pgmL(-1). The developed method successfully analyzed the target drugs in plasma samples from schizophrenic patients for therapeutic drug monitoring (TDM).

  9. Evaluation of Externally-Powered Hybrid System: Viennatone Hand, EMG and Switch Control, Hosmer E400 Elbow, AE Prosthesis.

    DTIC Science & Technology

    A prosthetic hybrid system consisting of an above elbow prosthesis containing an externally-powered electromechanical hand and a conventional...mechanical elbow was functionally evaluated. Two different means of controlling the terminal device were provided. The hand was first controlled by EMG

  10. Resonance switching using ultrafast laser in THz plasmonic devices based on hybrid structure of semiconductor and carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hong, J. T.; Ahn, Y. H.; Choi, S. B.; Park, D. J.

    2017-06-01

    We demonstrate all-optical switching of plasmonic resonance patterned on the carbon nanotube films supported on the silicon substrates. A considerable suppression of terahertz wave was observed in the transmission resonance, when the near-infrared femtosecond laser pulse is irradiated. A Fourier-transformed terahertz spectrum reveals that the resonance feature that was governed by the geometry of the slot antenna are almost completely removed with the laser irradiation having sufficiently high pulse energy reaching 18 μJ. A screening of terahertz field was analyzed in terms of the free carrier generation originating from the photoexcitation in semiconductor film.

  11. Genomic divergence and lack of introgressive hybridization between two 13-year periodical cicadas support life cycle switching in the face of climate change.

    PubMed

    Koyama, Takuya; Ito, Hiromu; Fujisawa, Tomochika; Ikeda, Hiroshi; Kakishima, Satoshi; Cooley, John R; Simon, Chris; Yoshimura, Jin; Sota, Teiji

    2016-11-01

    Life history evolution spurred by post-Pleistocene climatic change is hypothesized to be responsible for the present diversity in periodical cicadas (Magicicada), but the mechanism of life cycle change has been controversial. To understand the divergence process of 13-year and 17-year cicada life cycles, we studied genetic relationships between two synchronously emerging, parapatric 13-year periodical cicada species in the Decim group, Magicicada tredecim and M. neotredecim. The latter was hypothesized to be of hybrid origin or to have switched from a 17-year cycle via developmental plasticity. Phylogenetic analysis using restriction-site-associated DNA sequences for all Decim species and broods revealed that the 13-year M. tredecim lineage is genomically distinct from 17-year Magicicada septendecim but that 13-year M. neotredecim is not. We detected no significant introgression between M. tredecim and M. neotredecim/M. septendecim thus refuting the hypothesis that M. neotredecim are products of hybridization between M. tredecim and M. septendecim. Further, we found that introgressive hybridization is very rare or absent in the contact zone between the two 13-year species evidenced by segregation patterns in single nucleotide polymorphisms, mitochondrial lineage identity and head width and abdominal sternite colour phenotypes. Our study demonstrates that the two 13-year Decim species are of independent origin and nearly completely reproductively isolated. Combining our data with increasing observations of occasional life cycle change in part of a cohort (e.g. 4-year acceleration of emergence in 17-year species), we suggest a pivotal role for developmental plasticity in Magicicada life cycle evolution.

  12. Q-switched hybrid MOPA laser system based on Yb fibre with side pumping by single source

    NASA Astrophysics Data System (ADS)

    Kobtsev, Sergey; Kukarin, Sergey; Fedotov, Yurii

    2009-02-01

    A novel fiber-based Q-switched master-oscillator & power-amplifier system was developed by using non-PM Yb fiber with side pumping by single source. The passive Q-switched system provides for pulse energy up to 110 microjoule at CW 12 W single pump. Duration and repetition rate of generated pulses at 1080 nm can be varied from 280 ns to 1,8 microsecond, and in the range of 45-140 kHz depending on pump power at 980 nm. Design of master oscillator ensures linearly polarized output which remains polarized after passing power amplifier. Maximum stable average output of the system was 5 W and above this value we observed appearance of nonregular giant pulses which were able to initiate supercontinuum generation over 550-1750 nm range in relatively short-length microstructured fibre. For the first time to our knowledge, wideband supercontinuum generation was obtained with microsecond laser system pump. More details and results including applications for materials processing will be presented.

  13. Why are junior doctors reluctant to consult attending physicians?

    PubMed

    Swank, Otto H

    2010-03-01

    A physician performs two tasks: making diagnoses and determining treatments. To reduce medical error, junior doctors are supposed to consult their supervisors when they face uncommon circumstances. However, recent research shows that junior doctors are reluctant to do so. This paper presents a model that explains (i) which junior doctors shy away from consulting; (ii) when junior doctors are reluctant; (iii) the importance of protocols in the medical sector; and (iv) when consulting is a sign of strength or a sign of weakness. Furthermore, I show that encouraging junior doctors to consult by investigating mishaps leads to another distortion: they will give too much weight to own assessments.

  14. The Comparative Analysis of Inductor and Reluctance Wind Generators

    NASA Astrophysics Data System (ADS)

    Kamoliņš, Edmunds

    2009-01-01

    In the presented work two designs of brushless generators are compared: inductor and reluctance. Both designs are multipolar and also can be applied as directly driven wind generators. Both one and the second designs are basically similar, but in the inductor generator are windings of excitation or permanent magnets which complicate a design, increase consumption of the copper and energy losses. In work shown that reluctance generator has no winding of excitation, it is simple and more reliable, it has less weight. It's more competitive for use in low power wind plants.

  15. Reinforcement procedure in the treatment of reluctant speech.

    PubMed

    Morin, C; Ladouceur, R; Cloutier, R

    1982-06-01

    The efficacy of a positive reinforcement contingency procedure was evaluated in the treatment of a 6-year old boy with reluctant speech. The intervention was conducted in the kindergarten classroom and the teacher served as therapist. Using an ABABB' single case experimental design, positive reinforcement was found to be effective for increasing the child's verbal responsiveness. At a 1-year follow-up, therapeutic benefits were maintained at an optimal level. The present results bring support to the use of reinforcement procedures in the case of reluctant speech.

  16. More Rip-Roaring Reads for Reluctant Teen Readers.

    ERIC Educational Resources Information Center

    Ammon, Bette D.; Sherman, Gale W.

    This publication describes 40 fiction and nonfiction titles for grades 5 through 12 that will get the attention of even the most reluctant readers. Books range from humor and romance to adventure, mystery, and the supernatural. The titles were chosen based on the following criteria: recent publication date; relatively short length; appealing…

  17. American Fiction for Reluctant Readers (Resources and Reviews).

    ERIC Educational Resources Information Center

    Goldman, Milton E.

    1990-01-01

    Describes a high school course in American fiction in which students read an excerpt from a work of literature, watch the film adaptation of the work, and study both from a particular literary standpoint. Notes that such an approach appeals to reluctant readers. (RS)

  18. The Story of Sam: Advancing Proficiency in Reluctant Learners

    ERIC Educational Resources Information Center

    Dann, Tammy

    2014-01-01

    In this article, Tammy Dann, describes the issues presented by a reluctant learner in a foreign language class and the strategies required to see effective change. The student described in the article struggled to learn or had difficulty paying attention in the Spanish language class. One strategy used was "LinguaFolio Jr." for students…

  19. Giving Voice to Reluctant Learners: An Exploratory Study

    ERIC Educational Resources Information Center

    Pringle, Mark T.

    2010-01-01

    The purpose of this exploratory study is to hear from reluctant learners about their perceptions of their experiences in middle school and the meanings they make from these. This study will give voice to students, a stakeholder group that has been traditionally silent in the literature on K-12 learning and achievement. Capturing the perceptions…

  20. Engaging Reluctant Readers in a French Immersion Classroom

    ERIC Educational Resources Information Center

    Capina, Amanda Borton; Bryan, Gregory

    2017-01-01

    Reading engagement is like a puzzle consisting of many pieces to emplace for successful engagement to occur. The author, a French Immersion teacher/researcher, found that many of her grade one reluctant readers--those students who could read but chose not to--approached reading with some pieces of the puzzle. They had strategies and knowledge but…

  1. More Rip-Roaring Reads for Reluctant Teen Readers.

    ERIC Educational Resources Information Center

    Ammon, Bette D.; Sherman, Gale W.

    This publication describes 40 fiction and nonfiction titles for grades 5 through 12 that will get the attention of even the most reluctant readers. Books range from humor and romance to adventure, mystery, and the supernatural. The titles were chosen based on the following criteria: recent publication date; relatively short length; appealing…

  2. Reluctant Middle School ELLs: Creating Conditions for Quality Schoolwork

    ERIC Educational Resources Information Center

    Montgomery, Joel R.

    2009-01-01

    The purpose of this article is to provide middle level educators with an orientation to an intervention designed to facilitate reluctant middle school English language learners (ELLs) engagement in quality schoolwork. The article introduces a new investigation of English language learning through the lens of Glasser's Quality School and Choice…

  3. Giving Voice to Reluctant Learners: An Exploratory Study

    ERIC Educational Resources Information Center

    Pringle, Mark T.

    2010-01-01

    The purpose of this exploratory study is to hear from reluctant learners about their perceptions of their experiences in middle school and the meanings they make from these. This study will give voice to students, a stakeholder group that has been traditionally silent in the literature on K-12 learning and achievement. Capturing the perceptions…

  4. Successful Teachers Develop Academic Momentum with Reluctant Students

    ERIC Educational Resources Information Center

    Strahan, David

    2008-01-01

    In a series of investigations, the author and his colleagues have examined ways that students who once did poorly in school made progress and how their teachers nurtured their accomplishments. They have chronicled ways that successful teachers learned to understand why students are reluctant to do their work, how to help them think through their…

  5. Effective Approaches to Motivate and Engage Reluctant Boys in Literacy

    ERIC Educational Resources Information Center

    Senn, Nicole

    2012-01-01

    The purpose of this article was to investigate the reasons why elementary-aged boys often lack motivation in literacy and to provide teachers with useful approaches to engage reluctant boys in reading and writing. Following a comprehensive search of multiple university data base search engines, the author critically evaluated 21 peer-reviewed…

  6. Variable-reluctance motors for electric vehicle propulsion

    SciTech Connect

    Vallese, F.J.; Lang, J.H.

    1985-01-01

    This paper discusses the design, operation, and expected performance of a 60-kW variable-reluctance motor and inverter-designed for electric vehicle propulsion. To substantiate the performance of this system, experimental data obtained with a prototype 3.8-kW motor and inverter are provided.

  7. Design Methodology for Low-Speed Variable Reluctance Motors

    NASA Astrophysics Data System (ADS)

    Suriano, John Riden

    Lowering the gear reduction in actuators by utilizing high-torque low-speed motors enables the use of less expensive and simpler gear systems and decreases the overall system inertia. Variable reluctance machines can produce high torque at low speeds. Their static torque, a critical quantity for determination of low speed operation, is compared for three variable reluctance motor design variations using linear analysis. Saturation effects, which are crucial to the accurate determination of static torque, are modeled using a dual energy technique first proposed by Lord Rayleigh. Dual energy techniques utilizing flux tubes and magnetomotive force slices are developed into a numerical method for predicting nonlinear three-dimensional magnetostatic field parameters. The dual energy method offers a compromise between the accurate but laborious finite element method and the speed of simplified lumped parameter magnetic circuit calculations. A two-dimensional dual energy model of a variable reluctance motor is developed. Results of calculations on a 4 kW Oulton machine are compared to measurements and other calculation methods. Finally, as a demonstration, the model is used to evaluate two competing variable reluctance motors for use as replacements for a DC windshield wiper motor.

  8. Effective Approaches to Motivate and Engage Reluctant Boys in Literacy

    ERIC Educational Resources Information Center

    Senn, Nicole

    2012-01-01

    The purpose of this article was to investigate the reasons why elementary-aged boys often lack motivation in literacy and to provide teachers with useful approaches to engage reluctant boys in reading and writing. Following a comprehensive search of multiple university data base search engines, the author critically evaluated 21 peer-reviewed…

  9. 'All-in-one' analysis for metabolite identification using liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry with collision energy switching.

    PubMed

    Wrona, Mark; Mauriala, Timo; Bateman, Kevin P; Mortishire-Smith, Russell J; O'Connor, Desmond

    2005-01-01

    The removal of bottlenecks in discovery stage metabolite identification studies is an ongoing challenge for the pharmaceutical industry. We describe the use of an 'All-in-One' approach to metabolite characterization that leverages the fast scanning and high mass accuracy of hybrid quadrupole time-of-flight mass spectrometry (QqToFMS) instruments. Full-scan MS and MS/MS data is acquired using collision energy switching without the preselection, either manually or in a data-dependent manner, of precursor ions. The acquisition of 'clean' MS/MS data is assisted by the use of ultrahigh-performance chromatography. Data acquired using this method can then be mined post-acquisition in a number of ways. These include using narrow window extracted ion chromatograms (nwXICs) for expected biotransformations, XICs for the product ions of the parent compound and/or expected modification of these product ions, and neutral loss chromatograms. This approach has the potential to be truly comprehensive for the determination of in vitro biotransformations in a drug discovery environment.

  10. Photoelectrochemical lab-on-paper device equipped with a porous Au-paper electrode and fluidic delay-switch for sensitive detection of DNA hybridization.

    PubMed

    Wang, Yanhu; Ge, Lei; Wang, Panpan; Yan, Mei; Ge, Shenguang; Li, Nianqiang; Yu, Jinghua; Huang, Jiadong

    2013-10-07

    The sequence-specific detection of DNA hybridization has attracted considerable interest in numerous fields. Although traditional DNA biosensors have been widely explored due to their high sensitivity, it is still challenging to develop a low-cost, portable, disposable, fast, and easy-to-use DNA detection method for public use at home or in the field. To address these challenges, herein, we report a novel microfluidic photoelectrochemical (PEC) paper-based analytical platform, integrated with an internal chemiluminescent light source, a novel paper supercapacitor (PS) amplifier, and a terminal digital multi-meter (DMM) detector, for sensitive DNA detection using a graphene-modified porous Au-paper electrode as the working electrode to obtain enhanced PEC responses. The quantification mechanism of this strategy is based on the charging of this PS, which was constructed on a paper-based analytical platform through a simple "drawing and soaking" method, by the generated photocurrent. After a fixed period, the PS was automatically shorted under the control of a novel built-in fluidic delay-switch to output an instantaneously amplified current, which could be sensitively detected by the DMM. At optimal conditions, this paper-based analytical platform can detect DNA at concentrations at femtomolar level. This approach also shows excellent specificity toward single nucleotide mismatches.

  11. Electric Field-induced Resistance Switching in VO2 Channels using Hybrid Gate Dielectric of High- k Ta2O5/Organic material Parylene-C

    NASA Astrophysics Data System (ADS)

    Wei, Tingting; Kanki, Teruo; Fujiwara, Kohei; Chikanari, Masashi; Tanaka, Hidekazu

    Electrostatic approach utilizing field-effect transistor (FET) with correlated electron materials provides an avenue to realize the novel devices (Mott-transistor) and to clarify condensed matter physics. In this study, we have prepared Mott-transistors using vanadium dioxide (VO2) channels and employed hybrid gate dielectric consisted of high- k material Ta2O5 and organic polymer parylene-C to trigger carrier transport modulation in VO2. Obvious resistance modulations were observed in insulating regime through time-dependent resistance measurement at varied square-shaped gate bias (VG) . Contrasting to the hysteretic response in electric double layer transistor (EDLT), an abrupt resistance switching in less than of 2-second-interval enables us to attribute such immediate modulation to pure electrostatic effect. Moreover, the maximum of resistance change was identified to appear around phase transition temperature (TMI) , which confirmed the disordered heterogeneous regime at TMI. Taking advantage of systematic modulation using VO2-based devices, we demonstrated the pronounced shifts of TMI by gate bias. Another fascinating behavior on asymmetric drop in TMI by hole-electron carrier doping was observed.

  12. Ability of dynamic holography in self-assembled hybrid nanostructured silica films for all-optical switching and multiplexing

    NASA Astrophysics Data System (ADS)

    Telbiz, German; Bugaychuk, Svitlana; Leonenko, Eugen; Derzhypolska, Liudmyla; Gnatovskyy, Vladimir; Pryadko, Igor

    2015-04-01

    The sol-gel method has been employed in the fabrication of easily processable mesostructured films consisting of a nonionic surfactant and silica as the inorganic component. The ability of the occluded Pluronic P123 mesostructures to solubilize guest molecules made these films ideal host matrices for organic dyes and molecular assemblies, possessing substantial nonlinear susceptibilities. These films were explored for use as the photonic layer in all-optical time-to-space converters and proved successful at increasing the optical response of the intercalated dyes to a point that would make these composite films applicable for use as the photonic layer. Recording of a dynamical grating in a single-pulse regime has been obtained. Since the dynamical grating exhibits the fast relaxation time (up to 10 ns), the nonlinear mechanism represents an electronic excitation of the photosensitive molecules. As far as the dye molecules are distributed in nanoporous silica, a model of `gas of molecular dye' may be rightly used in order to consider nonlinear optical properties in the nanostructured hybrid films. We suppose that further improvement of the nonlinear optical nanomaterials may follow on the way to embed additional inclusions, which will not promote the heat accumulation in the host matrix and will lead to effective dissipation of the heat energy.

  13. Comparison of capabilities of reluctance synchronous motor and induction motor

    NASA Astrophysics Data System (ADS)

    Štumberger, Gorazd; Hadžiselimović, Miralem; Štumberger, Bojan; Miljavec, Damijan; Dolinar, Drago; Zagradišnik, Ivan

    2006-09-01

    This paper compares the capabilities of a reluctance synchronous motor (RSM) with those of an induction motor (IM). An RSM and IM were designed and made, with the same rated power and speed. They differ only in the rotor portion while their stators, housings and cooling systems are identical. The capabilities of both motors in a variable speed drive are evaluated by comparison of the results obtained by magnetically nonlinear models and by measurements.

  14. Controlled power transfer from wind driven reluctance generator

    SciTech Connect

    Rahim, Y.H.A.; Al-Sabbagh, A.M.L.

    1997-12-01

    The paper describes the dynamic performance of a wind driven reluctance generator connected to an electric network of large capacity. A controller that makes possible the regular flow of power to the network has been considered. Controller parameters that successfully suppress unwanted mechanical and electrical stresses and overshoots due to wind gust, have been estimated. The performance of the controller has also been examined for short-circuit faults at the terminals of the generators.

  15. Why Psychiatrists are Reluctant to Diagnose: Borderline Personality Disorder.

    PubMed

    Paris, Joel

    2007-01-01

    Clinicians can be reluctant to make a diagnosis of borderline personality disorder (BPD). One reason is that BPD is a complex syndrome with symptoms that overlap many Axis I disorders. This paper will examine interfaces between BPD and depression, between BPD and bipolar disorder, and between BPD and psychoses. It will suggest that making a BPD diagnosis does more justice to patients than avoiding it.

  16. Magnetic field distribution of strong hybrid magnet in high torque motor

    NASA Astrophysics Data System (ADS)

    Oguri, Kazuya; Mizutani, Akihiro; Ogino, Sanshiroh; Ochiai, Yasuzumi; Kawahata, Masahiro; Nishi, Yoshitake

    2002-11-01

    A variable reluctance hybrid magnet has been developed to apply new type of high torque motors. A permanent magnet, electromagnet and yoke construct the variable reluctance hybrid magnet. From an engineering point of view, it is important to know the magnetic field around a variable reluctance hybrid magnet. Based on the results of magnetic flux density measurement around the hybrid variable reluctance magnet, the high magnetic flux density was found at edges and joints. The high magnetic flux density was also obtained with electrical current of 10 A at optimum setting form. Therefore, we concluded that the strong force of rotor of the hybrid motor was generated by high surface flux density of the hybrid magnet.

  17. Development of Permanent Magnet Reluctance Motor Suitable for Variable-Speed Drive for Electric Vehicle

    NASA Astrophysics Data System (ADS)

    Sakai, Kazuto; Takahashi, Norio; Shimomura, Eiji; Arata, Masanobu; Nakazawa, Yousuke; Tajima, Toshinobu

    Regarding environmental and energy issues, increasing importance has been placed on energy saving in various systems. To save energy, it would be desirable if the total efficiency of various types of equipment were increased.Recently, a hybrid electric vehicle (HEV) and an electric vehicle (EV) have been developed. The use of new technologies will eventually lead to the realization of the new- generation vehicle with high efficiency. One new technology is the variable-speed drive over a wide range of speeds. The motor driving systems of the EV or the HEV must operate in the variable-speed range of up to 1:5. This has created the need for a high-efficiency motor that is capable of operation over a wide speed range. In this paper, we describe the concept of a novel permanent magnet reluctance motor (PRM) and discuss its characteristics. We developed the PRM, which has the capability of operating over a wide speed range with high efficiency. The PRM has a rotor with a salient pole, which generates magnetic anisotropy. In addition, the permanent magnets embedded in the rotor core counter the q-axis flux by the armature reaction. Then, the power density and the power factor increase. The PRM produces reluctance torque and torque by permanent magnet (PM) flux. The reluctance torque is 1 to 2 times larger than the PM torque. When the PRM operates over a constant-power speed range, the field component of the current will be regulated to maintain a constant voltage. The output power of the developed PRM is 8 to 250kW. It is clarified that the PRM operates at a wide variable-speed range (1:5) with high efficiency (92-97%). It is concluded that the PRM has high performance over a wide constant-power speed range. In addition, the PRM is constructed using a small PM, so that we can solve the problem of cost. Thus, the PRM is a superior machine that is suited for variable-speed drive applications.

  18. Reluctant entrepreneurs: professionally qualified Asian migrants in small business.

    PubMed

    Ip, D F

    1993-01-01

    "The abandonment of the White Australia Policy after World War II and the implementation of a points system in Australia's immigration program have led to a dramatic increase in the number of highly educated Asian migrants in the country. A study of 144 entrepreneurs of small business in the Indian and Chinese communities in Brisbane and Sydney found that, faced with institutionalized blockages, few of these highly educated migrants could practice what they were originally trained for. The majority of them, with their class resources, determination and optimism, became reluctant entrepreneurs."

  19. Parameter measurement of synchronous reluctance motor using LC resonance

    NASA Astrophysics Data System (ADS)

    Ahn, Joonseon; Kim, Ki-Chan; Lee, Ju

    2006-04-01

    The motor characterizing parameters are most important factors to drive precisely, effectively, and robustly. Especially, the exact knowledge of synchronous inductance is necessary to control the torque precisely in synchronous reluctance motor (SynRM). Therefore many works have been done for the exact measurement of motor parameters. In this paper, we propose the simple method of measuring the motor parameters, especially measuring the synchronous inductance of SynRM, which can overcome the demerits of conventional methods and measure the exact values. The proposed method uses the resonance phenomenon between the phase inductance and capacitors externally connected.

  20. Prediction and analysis of variable reluctance stepmotor drive systems

    NASA Astrophysics Data System (ADS)

    Pulle, D. W. J.

    1982-01-01

    A relationship between the electric terminal parameters and output/input power is derived for conventional doubly-salient synchronous machines and extended to include the variable reluctance motor. The advantages and limitations of the drive-schemes are shown in Blondel diagrams and torque speed curves. A general method for obtaining a quantitative assessment of drive-schemes is developed by the introduction of so-called performance figures, related to the output power and efficiency. From this method applied to four drive schemes, it is concluded that severe performance degradation is the result of using a forging resistance in a drive-scheme. A forced decay unipolar chopper drive is presented.

  1. Petroleum staff reluctance and adjustment to innovative changes

    NASA Astrophysics Data System (ADS)

    Makasheva, Yu S.; Makasheva, N. P.; Remnyakov, V. V.; Burykhin, B. S.; Shenderova, I. V.

    2015-11-01

    The modern economy is developing in the direction of innovations implementation. Innovations are becoming the basic prerequisite for the competitiveness of the enterprises. The Russian oil and gas sector innovation issue is very crucial. Low innovation activity of companies could result in a serious threat due to the strong global competition, increased uncertainty and risks. The need for innovative changes often meets reluctance. The reasons of it vary and require serious research. Managers should give special attention to the development of adjustment ability of the staff, to introduce modern methods for improving the adjustment potential of the enterprise staff.

  2. Variable-reluctance motor drives for electric vehicle propulsion. Final report

    SciTech Connect

    Lang, J.H.; Vallese, F.J.

    1985-05-01

    A methodology is presented for the design of a variable reluctance motor drive having high specific torque, power output and efficiency. Models are developed that describe the magnetic terminal relations of the VRM. These models are based on a flux-tube analysis that is motivated by numerically obtained finite-difference magnetic simulations. The result is a model for the flux-linkage/phase-current characteristic of the VRM. Intrinsic to this model is the estimation of maximum and minimum inductance as well the incremental inductance during bulk saturation. Also fundamental is the behavior of the flux linkage during local pole-tip saturation and due to bulk core saturation. This model agrees favorably with data available in the literature as well as experimental results presented in this thesis. The drive-oriented treatment of modelling and design uncovered important design interactions between the VRM, its inverter, and its excitation. The experimental 3.8-kW drive operated as expected, verifying the models and the design optimizations developed for VRM drives. These experimental results were projected to the 60-kW level, indicating that a 60-kW drive could be constructed with a VRM having a mass of approximately 65 kg, and an efficiency in excess of 95% at and below peak power output. The corresponding inverter was designed with only three high-power switches so as to reduce its cost.

  3. Molecular DNA switches and DNA chips

    NASA Astrophysics Data System (ADS)

    Sabanayagam, Chandran R.; Berkey, Cristin; Lavi, Uri; Cantor, Charles R.; Smith, Cassandra L.

    1999-06-01

    We present an assay to detect single-nucleotide polymorphisms on a chip using molecular DNA switches and isothermal rolling- circle amplification. The basic principle behind the switch is an allele-specific oligonucleotide circularization, mediated by DNA ligase. A DNA switch is closed when perfect hybridization between the probe oligonucleotide and target DNA allows ligase to covalently circularize the probe. Mismatches around the ligation site prevent probe circularization, resulting in an open switch. DNA polymerase is then used to preferentially amplify the closed switches, via rolling-circle amplification. The stringency of the molecular switches yields 102 - 103 fold discrimination between matched and mismatched sequences.

  4. Exciter switch

    NASA Technical Reports Server (NTRS)

    Mcpeak, W. L.

    1975-01-01

    A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

  5. Switch wear leveling

    DOEpatents

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

    2015-09-01

    An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

  6. Design of a variable reluctance asymmetric stepping millimotor

    SciTech Connect

    GARCIA,ERNEST J.; GREENWOOD,WILLIAM H.; OLIVER,ANDREW D.

    2000-06-01

    This paper reports on the design, simulation, and preliminary testing of a three phase variable reluctance stepping motor. This motor is pancake-shaped with an overall outside diameter of 8 mm and a height of 3 mm. The outside diameter of the rotor is 4.7 mm. The rotor and stators occupy 2 mm of the height with the remaining 1 mm reserved for a 6:1 planetary gear reductor. The rotor and stators were constructed of Hyperco 50 using conventional miniature machining. The reductor was assembled using copper and PMMA (polymethylmethacrylate) components that were constructed using the LIGA (Lithographic Galvanoformung Abformung) microfabrication process. The maximum measured stall torque of the motor without the reductor is 0.47mNm at 4W and the maximum speed is 2,400 rpm.

  7. Writing in Context: Reluctant Writers and Their Writing at Home and at School

    ERIC Educational Resources Information Center

    Gardner, Paul

    2013-01-01

    This study investigated the engagement with writing of reluctant writers in the contexts of home and school. A structured and semi-structured survey method was used to capture responses from 106 reluctant writers in 9 primary schools (age range 6--9 year olds) in the UK. Findings show that although these students were deemed to be reluctant…

  8. What Happens When Readers Do Not Read? The Problem of Reluctant Readers.

    ERIC Educational Resources Information Center

    Thompson, Mark E.

    Noting that what becomes of reluctant readers should be of great concern to a nation that advocates education and has traditionally been committed to principles of the higher order, this paper identifies the characteristics of reluctant or unmotivated readers and discusses what happens to them. Following background reflection on the limits people…

  9. Arc-Free High-Power dc Switch

    NASA Technical Reports Server (NTRS)

    Miller, W. N.; Gray, O. E.

    1982-01-01

    Hybrid switch allows high-power direct current to be turned on and off without arcing or erosion. Switch consists of bank of transistors in parallel with mechanical contacts. Transistor bank makes and breaks switched circuit; contacts carry current only during steady-state "on" condition. Designed for Space Shuttle orbiter, hybrid switch can be used also in high-power control circuits in aircraft, electric autos, industrial furnaces, and solar-cell arrays.

  10. Coaxial Switch

    DTIC Science & Technology

    2014-04-23

    08-2015 Publication Coaxial Switch David J. Bamford et al Naval Undersea Warfare Center Division, Newport 1176 Howell Street, Bldg 102T, Code 00L...Distribution A A coaxial switch having a housing and a shaft extending through and rotatably mounted to the housing. The shaft extends from opposite...conductor members are electrically connected together. When the coaxial switch is engaged, the conductor members are inserted into the connector body

  11. Enhanced performance of light-controlled conductive switching in hybrid cuprous oxide/reduced graphene oxide (Cu2O/rGO) nanocomposites.

    PubMed

    Wei, Jing; Zang, Zhigang; Zhang, Yubo; Wang, Ming; Du, Jihe; Tang, Xiaosheng

    2017-03-01

    A significant enhancement of photoresponse from the light-controlled conductive switching based on Cu2O/rGO nanocomposites was experimentally demonstrated. Cu2O/rGO nanocomposites were synthesized via a facile wet-reduced method. The crystalline structure, morphologies, and photoluminescence of the Cu2O/rGO nanocomposites were characterized and analyzed. The fabricated conductive switching was measured under the irradiation of a continuous laser. When the laser was turned on and off alternately, the photoconductive switching obviously displayed a state conversion between "on" and "off" reversibly. Furthermore, the typical current-voltage (I-V) and current-time (I-t) curves exhibited a relatively high switching ratio (Ion/Ioff) of 3.25 and a fast response time of 0.45 s. The excellent "on-off" characteristics of the device show promising applications in memory storage and logic circuits.

  12. Optical switches and switching methods

    DOEpatents

    Doty, Michael

    2008-03-04

    A device and method for collecting subject responses, particularly during magnetic imaging experiments and testing using a method such as functional MRI. The device comprises a non-metallic input device which is coupled via fiber optic cables to a computer or other data collection device. One or more optical switches transmit the subject's responses. The input device keeps the subject's fingers comfortably aligned with the switches by partially immobilizing the forearm, wrist, and/or hand of the subject. Also a robust nonmetallic switch, particularly for use with the input device and methods for optical switching.

  13. Negotiating vaccine acceptance in an era of reluctance.

    PubMed

    Larson, Heidi J

    2013-08-01

    Studies to better understand the determinants of vaccine acceptance have expanded to include more investigation into dynamics of individual decision-making as well as the influences of peers and social networks. Vaccine acceptance is determined by a range of factors, from structural issues of supply, costs and access to services, as well as the more demand-side determinants. The term vaccine hesitancy is increasingly used in the investigation of demand-side determinants, moving away from the more polarized framing of pro- and anti-vaccine groups to recognizing the importance of understanding and engaging those who are delaying vaccination, accepting only some vaccines, or who are yet undecided, but reluctant. As hesitancy is a state of indecision, it is difficult to measure, but the stage of indecision is a critical time to engage and support the decision-making process. This article suggests modes of investigating the determinants of vaccine confidence and levers of vaccine acceptance toward better engagement and dialogue early in the process of decision-making. Pressure to vaccinate can be counter-productive. Listening and dialog can support individual decision-making and more effectively inform the public health community of the issues and concerns influencing vaccine hesitancy.

  14. Variable-reluctance motor drives for electric vehicle propulsion

    NASA Astrophysics Data System (ADS)

    Lang, J. H.; Vallese, F. J.

    1985-05-01

    A methodology is presented for the design of a variable reluctance motor drive having high specific torque, power output and efficiency. Models are developed that describe the magnetic terminal relations of the VRM. These models are based on a flux-tube analysis that is motivated by numerically obtained finite-difference magnetic simulations. The result is a model for the flux-linkage/phase-current characteristic of the VRM. Intrinsic to this model is the estimation of maximum and minimum inductance as well the incremental inductance during bulk saturation. Also fundamental is the behavior of the flux linkage during local pole-tip saturation and due to bulk core saturation. The drive-oriented treatment of modelling and design uncovered important design interactions between the VRM, its inverter, and its excitation. The experimental 3.8-kW drive operated as expected, verifying the models and the design optimizations developed for VRM drives. These experimental results were projected to the 60-kW level, indicating that a 60-kW drive could be constructed with a VRM having a mass of approximately 65 kg, and an efficiency in excess of 95% at and below peak power output.

  15. Interior Permanent Magnet Reluctance Machine with Brushless Field Excitation

    SciTech Connect

    Wiles, R.H.

    2005-10-07

    In a conventional permanent magnet (PM) machine, the air-gap flux produced by the PM is fixed. It is difficult to enhance the air-gap flux density due to limitations of the PM in a series-magnetic circuit. However, the air-gap flux density can be weakened by using power electronic field weakening to the limit of demagnetization of the PMs. This paper presents the test results of controlling the PM air-gap flux density through the use of a stationary brushless excitation coil in a reluctance interior permanent magnet with brushless field excitation (RIPM-BFE) motor. Through the use of this technology the air-gap flux density can be either enhanced or weakened. There is no concern with demagnetizing the PMs during field weakening. The leakage flux of the excitation coil through the PMs is blocked. The prototype motor built on this principle confirms the concept of flux enhancement and weakening through the use of excitation coils.

  16. Regulating Charge and Exciton Distribution in High-Performance Hybrid White Organic Light-Emitting Diodes with n-Type Interlayer Switch

    NASA Astrophysics Data System (ADS)

    Luo, Dongxiang; Yang, Yanfeng; Xiao, Ye; Zhao, Yu; Yang, Yibin; Liu, Baiquan

    2017-10-01

    The interlayer (IL) plays a vital role in hybrid white organic light-emitting diodes (WOLEDs); however, only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time, has been demonstrated to achieve a high efficiency, high color rendering index (CRI), and low voltage trade-off. The device exhibits a maximum total efficiency of 41.5 lm W-1, the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs (80-88) at practical luminances (≥1000 cd m-2) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V (>1 cd m-2), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs. [Figure not available: see fulltext.

  17. ION SWITCH

    DOEpatents

    Cook, B.

    1959-02-10

    An ion switch capable of transferring large magnitudes of power is described. An ion switch constructed in accordance with the invention includes a pair of spaced control electrodes disposed in a highly evacuated region for connection in a conventional circuit to control the passing of power therethrough. A controllable ionic conduction path is provided directiy between the control electrodes by a source unit to close the ion switch. Conventional power supply means are provided to trigger the source unit and control the magnitude, durations and pulse repetition rate of the aforementioned ionic conduction path.

  18. Allogamy-Autogamy Switch Enhance Assortative Mating in the Allotetraploid Centaurea seridis L. Coexisting with the Diploid Centaurea aspera L. and Triggers the Asymmetrical Formation of Triploid Hybrids.

    PubMed

    Ferriol, María; Garmendia, Alfonso; Gonzalez, Ana; Merle, Hugo

    2015-01-01

    Hybridization between tetraploids and their related diploids is generally unsuccessful in Centaurea, hence natural formation of triploid hybrids is rare. In contrast, the diploid Centaurea aspera and the allotetraploid C. seridis coexist in several contact zones where a high frequency of triploid hybrids is found. We analyzed the floral biology of the three taxa to identify reproductive isolation mechanisms that allow their coexistence. Flowering phenology was recorded, and controlled pollinations within and between the three taxa were performed in the field. Ploidy level and germination of progeny were also assessed. There was a 50% flowering overlap which indicated a phenological shift. Diploids were strictly allogamous and did not display mentor effects, while tetraploids were found to be highly autogamous. This breakdown of self-incompatibility by polyploids is first described in Centaurea. The asymmetrical formation of the hybrid was also found: all the triploid intact cypselae came from the diploid mothers pollinated by the pollen of tetraploids. Pollen and eggs from triploids were totally sterile, acting as a strong triploid block. These prezygotic isolation mechanisms ensured higher assortative mating in tetraploids than in diploids, improving their persistence in the contact zones. However these mechanisms can also be the cause of the low genetic diversity and high genetic structure observed in C. seridis.

  19. Allogamy-Autogamy Switch Enhance Assortative Mating in the Allotetraploid Centaurea seridis L. Coexisting with the Diploid Centaurea aspera L. and Triggers the Asymmetrical Formation of Triploid Hybrids

    PubMed Central

    Ferriol, María; Garmendia, Alfonso; Gonzalez, Ana; Merle, Hugo

    2015-01-01

    Hybridization between tetraploids and their related diploids is generally unsuccessful in Centaurea, hence natural formation of triploid hybrids is rare. In contrast, the diploid Centaurea aspera and the allotetraploid C. seridis coexist in several contact zones where a high frequency of triploid hybrids is found. We analyzed the floral biology of the three taxa to identify reproductive isolation mechanisms that allow their coexistence. Flowering phenology was recorded, and controlled pollinations within and between the three taxa were performed in the field. Ploidy level and germination of progeny were also assessed. There was a 50% flowering overlap which indicated a phenological shift. Diploids were strictly allogamous and did not display mentor effects, while tetraploids were found to be highly autogamous. This breakdown of self-incompatibility by polyploids is first described in Centaurea. The asymmetrical formation of the hybrid was also found: all the triploid intact cypselae came from the diploid mothers pollinated by the pollen of tetraploids. Pollen and eggs from triploids were totally sterile, acting as a strong triploid block. These prezygotic isolation mechanisms ensured higher assortative mating in tetraploids than in diploids, improving their persistence in the contact zones. However these mechanisms can also be the cause of the low genetic diversity and high genetic structure observed in C. seridis. PMID:26469271

  20. Design Method of ILQ Robust Current Control System for Synchronous Reluctance Electrical Motors

    NASA Astrophysics Data System (ADS)

    Amano, Yoko; Takami, Hiroshi; Fujii, Takao

    In this paper, a robust current control system for a synchronous reluctance electrical motor by an ILQ (Inverse Linear Quadratic) design method is proposed newly. First, for performing simultaneously decouple and large region linearization of an d-q axes system in the synchronous reluctance electrical motor using nonlinear state feedback, it is derived that a linear current-voltage state equation linearized model by the d-q axes decouple of the synchronous reluctance electrical motor. Next, according to the ILQ design method, an optimum solution and an optimal condition that achieve the robust current control system for the synchronous reluctance electrical motor are analytically derived, then the robust current control system can be designed. Finally, in practical experiments, we compare the proposed method with the PI (Proportional Integral) control method, the creativity and the usefulness of the proposed method are confirmed by experimental results.

  1. Reluctance to start medication for Parkinson's disease: a mutual misunderstanding by patients and physicians.

    PubMed

    Mestre, Tiago A; Teodoro, Tiago; Reginold, William; Graf, Julia; Kasten, Maike; Sale, Joanna; Zurowski, Mateusz; Miyasaki, Janis; Ferreira, Joaquim J; Marras, Connie

    2014-06-01

    Reluctance to start medication has never been investigated before in PD. We studied reluctance to start medication for PD motor symptoms, namely its prevalence, underlying reasons, drug-specificity, and associated delay in the start of PD medication. A cross-sectional observational international study was conducted. Patients with a clinical diagnosis of PD advised to start antiparkinsonian medication in the previous 5 years were invited to complete a questionnaire in three centers located in North America and Europe. An electronic online survey was sent to physicians through the mailing list of the Movement Disorder Society. 469 participants (201 PD patients, 268 physicians). 40.2% (n = 82) of the patients reported reluctance to start medication, but 88.6% (n = 234/264) of the physicians estimated that ≤20% of their patients with PD had been reluctant to start medication. The most common reasons reported by patients were the fear of side effects (n = 35, 55.6%), followed by non-acceptance of diagnosis (n = 23, 36.5%); fear of a temporally limited benefit was more commonly selected by physicians (n = 92/267, 34.5%). Patients indicated reluctance to start DAs more frequently compared with L-DOPA (OR: 2.22, 95% CI: 1.30, 9.03; p = 0.013) while physicians perceived L-DOPA to be associated with more reluctance (OR: 4.7, 95% CI: 3.41; 6.59; p < 0.0001). Patients with PD and physicians have a different perspective on the issue of reluctance to start medication. There is a need to bring physicians and patients with PD closer to a shared vision of the problem reluctance to start medication. Copyright © 2014. Published by Elsevier Ltd.

  2. Arterial switch.

    PubMed

    Planche, C; Lacour-Gayet, F; Serraf, A

    1998-01-01

    A relatively large spectra of anatomic variations are found within the unifying features of discordant ventriculoarterial connections. Variants that lend themselves to anatomic repair by the arterial switch operation are discussed, these include transposition of the great arteries with intact ventricular septum (TGA IVS), TGA associated with a ventricular septal defect (TGA VSD), double-outlet right ventricle with subpulmonary VSD (DORV VSD), and TGA or DORV with VSD associated with coarctation. Double discordance with VSD, which is currently treated by double switch or Rastelli and atrial switch and which probably represents, in our department, the only remaining indication for atrial switch, is not discussed. Also, we exclude TGA associated with pulmonary stenosis, which is treated by Rastelli or REV operation.

  3. Magnetic switching

    NASA Astrophysics Data System (ADS)

    Kirbie, H. C.

    1989-04-01

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented.

  4. Acceleration switch

    DOEpatents

    Abbin, J.P. Jr.; Devaney, H.F.; Hake, L.W.

    1979-08-29

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  5. Acceleration switch

    DOEpatents

    Abbin, Jr., Joseph P.; Devaney, Howard F.; Hake, Lewis W.

    1982-08-17

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  6. Nucleosome Switches

    NASA Astrophysics Data System (ADS)

    Schwab, David J.; Bruinsma, Robijn F.; Rudnick, Joseph; Widom, Jonathan

    2008-06-01

    We present a statistical-mechanical model for the positioning of nucleosomes along genomic DNA molecules as a function of the strength of the binding potential and the chemical potential of the nucleosomes. We show that a significant section of the DNA is composed of two-level nucleosome switching regions where the nucleosome distribution undergoes a localized, first-order transition. The location of the nucleosome switches shows a strong correlation with the location of gene-regulation regions.

  7. Nucleosome switches.

    PubMed

    Schwab, David J; Bruinsma, Robijn F; Rudnick, Joseph; Widom, Jonathan

    2008-06-06

    We present a statistical-mechanical model for the positioning of nucleosomes along genomic DNA molecules as a function of the strength of the binding potential and the chemical potential of the nucleosomes. We show that a significant section of the DNA is composed of two-level nucleosome switching regions where the nucleosome distribution undergoes a localized, first-order transition. The location of the nucleosome switches shows a strong correlation with the location of gene-regulation regions.

  8. Keep flexible - Keep switching! The influence of forced task switching on voluntary task switching.

    PubMed

    Fröber, Kerstin; Dreisbach, Gesine

    2017-05-01

    Goal directed behavior depends on a dynamic balance between cognitive flexibility and stability. Identifying factors that modulate the balance between these control states is therefore of major interest for the understanding of human action control. In two experiments we used a hybrid paradigm combining forced- and free-choice task switching and measured spontaneous voluntary switch rate (VSR) as an indicator of cognitive flexibility. In Experiment 1 participants were free to choose a given task on 75%, 50%, or 25% of all trials. In the remaining forced-choice trials task repetitions and switches were roughly equally distributed. Results showed that VSR increases with increasing proportion of forced choices. To clarify whether the frequency of forced choices per se or the frequency of forced task switches in particular drives this effect we conducted Experiment 2. In a fully orthogonal between design participants were free to choose a given task on 75% or 25% of all trials with a predetermined switch rate in the remaining forced-choice trials of 75% or 25%, respectively. Results revealed an interaction of both manipulations: The highest VSR was found for the combination of 75% forced-choice trials with 75% forced switch rate, while VSR for 75% forced-choice trials with 25% forced switch rate was still higher than VSRs in both conditions with 25% forced-choice trials. This suggests that a context of frequent forced task switching changes global control parameters towards more flexible behavior. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Acoustically assisted spin-transfer-torque switching of nanomagnets: An energy-efficient hybrid writing scheme for non-volatile memory

    SciTech Connect

    Biswas, Ayan K.; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2013-12-02

    We show that the energy dissipated to write bits in spin-transfer-torque random access memory can be reduced by an order of magnitude if a surface acoustic wave (SAW) is launched underneath the magneto-tunneling junctions (MTJs) storing the bits. The SAW-generated strain rotates the magnetization of every MTJs' soft magnet from the easy towards the hard axis, whereupon passage of a small spin-polarized current through a target MTJ selectively switches it to the desired state with > 99.99% probability at room temperature, thereby writing the bit. The other MTJs return to their original states at the completion of the SAW cycle.

  10. Switch for serial or parallel communication networks

    DOEpatents

    Crosette, Dario B.

    1994-01-01

    A communication switch apparatus and a method for use in a geographically extensive serial, parallel or hybrid communication network linking a multi-processor or parallel processing system has a very low software processing overhead in order to accommodate random burst of high density data. Associated with each processor is a communication switch. A data source and a data destination, a sensor suite or robot for example, may also be associated with a switch. The configuration of the switches in the network are coordinated through a master processor node and depends on the operational phase of the multi-processor network: data acquisition, data processing, and data exchange. The master processor node passes information on the state to be assumed by each switch to the processor node associated with the switch. The processor node then operates a series of multi-state switches internal to each communication switch. The communication switch does not parse and interpret communication protocol and message routing information. During a data acquisition phase, the communication switch couples sensors producing data to the processor node associated with the switch, to a downlink destination on the communications network, or to both. It also may couple an uplink data source to its processor node. During the data exchange phase, the switch couples its processor node or an uplink data source to a downlink destination (which may include a processor node or a robot), or couples an uplink source to its processor node and its processor node to a downlink destination.

  11. Switch for serial or parallel communication networks

    DOEpatents

    Crosette, D.B.

    1994-07-19

    A communication switch apparatus and a method for use in a geographically extensive serial, parallel or hybrid communication network linking a multi-processor or parallel processing system has a very low software processing overhead in order to accommodate random burst of high density data. Associated with each processor is a communication switch. A data source and a data destination, a sensor suite or robot for example, may also be associated with a switch. The configuration of the switches in the network are coordinated through a master processor node and depends on the operational phase of the multi-processor network: data acquisition, data processing, and data exchange. The master processor node passes information on the state to be assumed by each switch to the processor node associated with the switch. The processor node then operates a series of multi-state switches internal to each communication switch. The communication switch does not parse and interpret communication protocol and message routing information. During a data acquisition phase, the communication switch couples sensors producing data to the processor node associated with the switch, to a downlink destination on the communications network, or to both. It also may couple an uplink data source to its processor node. During the data exchange phase, the switch couples its processor node or an uplink data source to a downlink destination (which may include a processor node or a robot), or couples an uplink source to its processor node and its processor node to a downlink destination. 9 figs.

  12. Asynchronous switching output feedback control of discrete-time switched linear systems

    NASA Astrophysics Data System (ADS)

    Yuan, Chengzhi; Wu, Fen

    2015-09-01

    In this paper, the problem of dynamic output-feedback control synthesis is addressed for discrete-time switched linear systems under asynchronous switching. The proposed hybrid controller consists of a standard dynamic output-feedback switching control law and an impulsive reset law induced by controller state jumps. Using the average dwell time technique incorporating with multiple quadratic Lyapunov functions, the switching control synthesis conditions for asymptotic stability with guaranteed weighted ℓ2-gain performance are derived as a set of linear matrix inequalities (LMIs). The proposed hybrid synthesis scheme advances existing design methods for output-feedback asynchronous switching control of switched linear systems in two important aspects: LMI formulation of the synthesis problem; and arbitrary order of the controller state. A numerical example is used to illustrate the effectiveness and advantages of the proposed design technique.

  13. Hybrid power source

    DOEpatents

    Singh, Harmohan N.

    2012-06-05

    A hybrid power system is comprised of a high energy density element such as a fuel-cell and high power density elements such as a supercapacitor banks. A DC/DC converter electrically connected to the fuel cell and converting the energy level of the energy supplied by the fuel cell. A first switch is electrically connected to the DC/DC converter. First and second supercapacitors are electrically connected to the first switch and a second switch. A controller is connected to the first switch and the second switch, monitoring charge levels of the supercapacitors and controls the switching in response to the charge levels. A load is electrically connected to the second switch. The first switch connects the DC/DC converter to the first supercapacitor when the second switch connects the second supercapacitor to the load. The first switch connects the DC/DC converter to the second supercapacitor when the second switch connects the first supercapacitor to the load.

  14. Optical switch

    DOEpatents

    Reedy, Robert P.

    1987-01-01

    An optical switching device (10) is provided whereby light from a first glass fiber (16) or a second glass fiber (14) may be selectively transmitted into a third glass fiber (18). Each glass fiber is provided with a focusing and collimating lens system (26, 28, 30). In one mode of operation, light from the first glass fiber (16) is reflected by a planar mirror (36) into the third glass fiber (18). In another mode of operation, light from the second glass fiber (14) passes directly into the third glass fiber (18). The planar mirror (36) is attached to a rotatable table (32) which is rotated to provide the optical switching.

  15. Optical switch

    DOEpatents

    Reedy, R.P.

    1987-11-10

    An optical switching device is provided whereby light from a first glass fiber or a second glass fiber may be selectively transmitted into a third glass fiber. Each glass fiber is provided with a focusing and collimating lens system. In one mode of operation, light from the first glass fiber is reflected by a planar mirror into the third glass fiber. In another mode of operation, light from the second glass fiber passes directly into the third glass fiber. The planar mirror is attached to a rotatable table which is rotated to provide the optical switching. 3 figs.

  16. Optical switch

    DOEpatents

    Reedy, R.P.

    1985-01-18

    An optical switching device is provided whereby light from a first glass fiber or a second glass fiber may be selectively transmitted into a third glass fiber. Each glass fiber is provided with a focusing and collimating lens system. In one mode of operation, light from the first glass fiber is reflected by a planar mirror into the third glass fiber. In another mode of operation, light from the second glass fiber passes directly into the third glass fiber. The planar mirror is attached to a rotatable table which is rotated to provide the optical switching.

  17. Switching Transistor

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Westinghouse Electric Corporation's D60T transistors are used primarily as switching devices for controlling high power in electrical circuits. It enables reduction in the number and size of circuit components and promotes more efficient use of energy. Wide range of application from a popcorn popper to a radio frequency generator for solar cell production.

  18. Switched power workshop. [Switched power electron guns

    SciTech Connect

    Palmer, R.B.

    1988-01-01

    This paper discusses the design of a switched power electron gun. Particular topics discussed are: vacuum photodiode switch; laser switched solid state diodes; gun performance; charging supply; and laser requirements. (LSP)

  19. Optimization of Pole and Slot Widths for Reluctance Torque Reduction in a Brushless DC Spindle Motor

    NASA Astrophysics Data System (ADS)

    Chuang, T. Y.; Lieu, D. K.; McAllister, J. S.

    A parametric study was conducted to determine the effect of motor stator slot widths and rotor permanent magnet pole separation widths on the reluctance torque. This study is based on a finite element analysis of a particular 6-pole/9-slot motor. The analysis can be expanded to other slot/pole combinations. Force and torque calculations were based on an integration of the Maxwell stresses along the center of the airgap. As a general rule, the reluctance torque may be reduced by decreasing the slot width for any given pole separation. For any given slot width, the reluctance torque can be reduced to zero by selection of the proper pole separation. The optimum slot widths are slightly different than those predicted by past analytical formulation. There will be, however, a noticeable effect on the main drive torque and the torque ripple.

  20. Strain-driven and ultrasensitive resistive sensor/switch based on conductive alginate/nitrogen-doped carbon-nanotube-supported Ag hybrid aerogels with pyramid design.

    PubMed

    Zhao, Songfang; Zhang, Guoping; Gao, Yongju; Deng, Libo; Li, Jinhui; Sun, Rong; Wong, Ching-Ping

    2014-12-24

    Flexible strain-driven sensor is an essential component in the flexible electronics. Especially, high durability and sensitivity to strain are required. Here, we present an efficient and low-cost fabrication strategy to construct a highly sensitive and flexible pressure sensor based on a conductive, elastic aerogel with pyramid design. When pressure is loaded, the contact area between the interfaces of the conductive aerogel and the copper electrode as well as among the building blocks of the nitrogen-doped carbon-nanotube-supported Ag (N-CNTs/Ag) aerogel monoliths, changes in reversible and directional manners. This contact resistance mechanism enables the hybrid aerogels to act as strain-driven sensors with high sensitivity and excellent on/off swithching behavior, and the gauge factor (GF) is ∼15 under strain of 3%, which is superior to those reported for other aerogels. In addition, robust, elastomeric and conductive nanocomposites can be fabricated by injecting polydimethylsiloxane (PDMS) into alginate/N-CNTs/Ag aerogels. Importantly, the building blocks forming the aerogels retain their initial contact and percolation after undergoing large-strain deformation, PDMS infiltration, and cross-linking of PDMS, suggesting their potential applications as strain sensors.

  1. Design optimization of the electrically peaking hybrid (ELPH) vehicle. Research report

    SciTech Connect

    Ehsani, M.; Gao, Y.; Butler, K.

    1998-10-01

    Electrically Peaking Hybrid (ELPH) is a parallel hybrid electric vehicle propulsion concept that was invented at Texas A and M University, by the advanced vehicle systems research group. Over the past six years, design methodologies, component development, and system optimization work has been going on for this invention. This project was a first attempt in integrating the above developments into an optimized design of an ELPH passenger car. Design specifications were chosen for a full size passenger car, performing as well as any conventional car, over the EPA-FTP-75 combined city/highway drive cycles. The results of this design project were two propulsion systems. Both were appropriate for commercial production, from the points of view of cost, availability of the technologies, and components. One utilized regenerative braking and the other did not. Substantial fuel savings and emissions reductions resulted from simulating these designs on the FTP-75 drive cycle. For example, the authors` ELPH full size car, with regenerative braking, was capable of delivering over 50 miles per gallon in city driving, with corresponding reductions in its emissions. This project established the viability of the authors` ELPH concept and their design methodologies, in computer simulations. More work remains to be done on investigating more advanced power plants, such as fuel cells, and more advanced components, such as switched reluctance motor drives, for the authors` designs. Furthermore, the authors` design optimization can be carried out to more detailed levels, for prototyping and production.

  2. Farm Owners' Reluctance to Embrace Family Succession and the Implications for Extension: The Case of Family Farms in New Zealand

    ERIC Educational Resources Information Center

    Nuthall, P. L.; Old, K. M.

    2017-01-01

    Purpose: Despite the benefits of early planning for business succession, and plan implementation, many owners/managers fail to act expeditiously. Factors such as a reluctance to accept ageing, a concern over the risks involved and inappropriate objectives may be causative. This research moves towards explaining this reluctance and, consequently,…

  3. The insula modulates arousal-induced reluctance to try novel tastes through adrenergic transmission in the rat

    PubMed Central

    Rojas, Sebastián; Diaz-Galarce, Raúl; Jerez-Baraona, Juan Manuel; Quintana-Donoso, Daisy; Moraga-Amaro, Rodrigo; Stehberg, Jimmy

    2015-01-01

    Reluctance to try novel tastes (neophobia) can be exacerbated in arousing situations, such as when children are under social stress or in rodents, when the new taste is presented in a high arousal context (HA) compared to a low arousal context (LA). The present study aimed at determining whether adrenergic transmission at the Insula regulates the reluctance to try novel tastes induced by arousing contexts. To this end, a combination of systemic and intra-insular manipulations of adrenergic activity was performed before the novel taste (saccharin 0.1%) was presented either in LA or HA contexts in rats. Our results show that systemic adrenergic activity modulates reluctance to try novel tastes. Moreover, intra-insular microinjections of propranolol or norepinephrine (NE) were found to modulate the effects of arousing contexts on reluctance to try novel tastes. Finally, intra-insular propranolol blocked epinephrine-induced increased reluctance, while intra-insular NE blocked oral propranolol-induced decreases in reluctance and increased the reluctance to try novel tastes presented in low arousing contexts. In conclusion, our results suggest that the insula is a critical site for regulating the effects of arousal in the reluctance to try novel tastes via the adrenergic system. PMID:26175672

  4. Farm Owners' Reluctance to Embrace Family Succession and the Implications for Extension: The Case of Family Farms in New Zealand

    ERIC Educational Resources Information Center

    Nuthall, P. L.; Old, K. M.

    2017-01-01

    Purpose: Despite the benefits of early planning for business succession, and plan implementation, many owners/managers fail to act expeditiously. Factors such as a reluctance to accept ageing, a concern over the risks involved and inappropriate objectives may be causative. This research moves towards explaining this reluctance and, consequently,…

  5. The insula modulates arousal-induced reluctance to try novel tastes through adrenergic transmission in the rat.

    PubMed

    Rojas, Sebastián; Diaz-Galarce, Raúl; Jerez-Baraona, Juan Manuel; Quintana-Donoso, Daisy; Moraga-Amaro, Rodrigo; Stehberg, Jimmy

    2015-01-01

    Reluctance to try novel tastes (neophobia) can be exacerbated in arousing situations, such as when children are under social stress or in rodents, when the new taste is presented in a high arousal context (HA) compared to a low arousal context (LA). The present study aimed at determining whether adrenergic transmission at the Insula regulates the reluctance to try novel tastes induced by arousing contexts. To this end, a combination of systemic and intra-insular manipulations of adrenergic activity was performed before the novel taste (saccharin 0.1%) was presented either in LA or HA contexts in rats. Our results show that systemic adrenergic activity modulates reluctance to try novel tastes. Moreover, intra-insular microinjections of propranolol or norepinephrine (NE) were found to modulate the effects of arousing contexts on reluctance to try novel tastes. Finally, intra-insular propranolol blocked epinephrine-induced increased reluctance, while intra-insular NE blocked oral propranolol-induced decreases in reluctance and increased the reluctance to try novel tastes presented in low arousing contexts. In conclusion, our results suggest that the insula is a critical site for regulating the effects of arousal in the reluctance to try novel tastes via the adrenergic system.

  6. High/Low Handbook: Best Books and Web Sites for Reluctant Teen Readers. 4th Edition.

    ERIC Educational Resources Information Center

    LiBretto, Ellen V.; Barr, Catherine

    This handbook is a practical guide to the selection of high-interest, low-reading-level books and Web sites that will inspire a love of reading in teenagers who fall within the category of reluctant readers. It is especially useful for professionals in school and public libraries charged with building collections of suitable titles for these…

  7. Mathematical Tasks without Words and Word Problems: Perceptions of Reluctant Problem Solvers

    ERIC Educational Resources Information Center

    Holbert, Sydney Margaret

    2013-01-01

    This qualitative research study used a multiple, holistic case study approach (Yin, 2009) to explore the perceptions of reluctant problem solvers related to mathematical tasks without words and word problems. Participants were given a choice of working a mathematical task without words or a word problem during four problem-solving sessions. Data…

  8. The Reasons for the Reluctance of Princess Alia University College Students' from Practicing Sports Activities

    ERIC Educational Resources Information Center

    Odat, Jebril

    2015-01-01

    This study aimed at investigating the reasons lying behind the reluctance of participation in sport activities among Alia Princess College female students, using descriptive approach. The population of the study consisted of (2000) female students, whereas the sample was of (200) students. They were randomly selected and a questionnaire of 31…

  9. The Integrated Curriculum: Books for Reluctant Readers, Grades 2-5.

    ERIC Educational Resources Information Center

    Fredericks, Anthony D.

    Demonstrating that reading can and should be part of every curricular area, this book provides a wide selection of activities developed for 39 books selected on the basis of their interest level and application to the needs of reluctant readers in grades 2 through 5. The first part of the book presents guidelines for motivating students and…

  10. "You Play on Them. They're Active." Enhancing the Mathematics Learning of Reluctant Teenage Students

    ERIC Educational Resources Information Center

    Calder, Nigel; Campbell, Anthony

    2015-01-01

    This paper reports on a research project that examined the beliefs and attitudes of reluctant 16 to 18-year-old learners when using apps in their numeracy and literacy programmes. In particular, it considers the students' change of attitude towards numeracy learning. The data were consistent that the use of apps in the numeracy programme was…

  11. Identification of multi-modal plasma responses to applied magnetic perturbations using the plasma reluctance

    DOE PAGES

    Logan, Nikolas C.; Paz-Soldan, Carlos; Park, Jong-Kyu; ...

    2016-05-03

    Using the plasma reluctance, the Ideal Perturbed Equilibrium Code is able to efficiently identify the structure of multi-modal magnetic plasma response measurements and the corresponding impact on plasma performance in the DIII-D tokamak. Recent experiments demonstrated that multiple kink modes of comparable amplitudes can be driven by applied nonaxisymmetric fields with toroidal mode number n = 2. This multi-modal response is in good agreement with ideal magnetohydrodynamic models, but detailed decompositions presented here show that the mode structures are not fully described by either the least stable modes or the resonant plasma response. This paper identifies the measured response fieldsmore » as the first eigenmodes of the plasma reluctance, enabling clear diagnosis of the plasma modes and their impact on performance from external sensors. The reluctance shows, for example, how very stable modes compose a significant portion of the multi-modal plasma response field and that these stable modes drive significant resonant current. Finally, this work is an overview of the first experimental applications using the reluctance to interpret the measured response and relate it to multifaceted physics, aimed towards providing the foundation of understanding needed to optimize nonaxisymmetric fields for independent control of stability and transport.« less

  12. The Integrated Curriculum: Books for Reluctant Readers, Grades 2-5.

    ERIC Educational Resources Information Center

    Fredericks, Anthony D.

    Demonstrating that reading can and should be part of every curricular area, this book provides a wide selection of activities developed for 39 books selected on the basis of their interest level and application to the needs of reluctant readers in grades 2 through 5. The first part of the book presents guidelines for motivating students and…

  13. Success with Reluctant Researchers: Real Life Experiences in a Rural School Setting.

    ERIC Educational Resources Information Center

    Collins, Belva C.; Hall, Meada; Branson, Terri A.

    For five years, a collaborative team consisting of a special education teacher, a general education teacher, and a university professor conducted research studies in a rural secondary school. Although the general education teacher initially was reluctant to participate in a research project, especially one that involved students with disabilities,…

  14. Hysteresis and reluctance electric machines with bulk HTS elements. Recent results and future development

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; M-A Koneev, S.; Poltavets, V. N.; Larionoff, A. E.; Modestov, K. A.; Larionoff, S. A.; Gawalek, W.; Habisreuther, T.; Oswald, B.; Best, K.-J.; Strasser, T.

    2000-05-01

    Two new types of HTS electric machine are considered. The first type is hysteresis motors and generators with cylindrical and disc rotors containing bulk HTS elements. The second type is reluctance motors with compound HTS-ferromagnetic rotors. The compound HTS-ferromagnetic rotors, consisting of joined alternating bulk HTS (YBCO) and ferromagnetic (iron) plates, provide a new active material for electromechanical purposes. Such rotors have anisotropic properties (ferromagnetic in one direction and diamagnetic in the perpendicular one). Theoretical and experimental results for HTS hysteresis and reluctance motors are presented. A series of hysteresis HTS motors with output power rating from 1 kW (at 50 Hz) up to 4 kW (at 400 Hz) and a series of reluctance HTS motors with output power 2-18.5 kW (at 50 Hz) were constructed and successfully tested. It was shown that HTS reluctance motors could reach two to five times better overall dimensions and specific power than conventional asynchronous motors of the same size and will have higher values of power factor (cos ϕ≥0.7 to 0.8).

  15. My Bluford High Boys: How a Book Club for Reluctant Readers Proved the Naysayers Wrong

    ERIC Educational Resources Information Center

    Stevenson, Sara

    2009-01-01

    As a middle school librarian in Austin, Texas, the author has been running weekly book clubs for years, which covered many genres that appeal to a wide cross section of kids. When approached by a group of Latino boys from low-income families, the author was inspired to run a Bluford High book club for reluctant readers. The author shares how she…

  16. Turning Them on: How Does a Teacher Reach the Reluctant Learner?

    ERIC Educational Resources Information Center

    Gutmann, David

    2007-01-01

    Over a 27-year teaching career in schools in North London and the Zambian bush I have relished the challenge of helping the disaffected or reluctant learner. Most of my teaching was in the area of business and vocational education, where learners have often been placed not through choice but because they were not seen as high enough achievers to…

  17. On Being a Social Change Agent in a Reluctant Collegial Environment.

    ERIC Educational Resources Information Center

    Cleveland-Innes, Martha; Emes, Claudia; Ellard, John H.

    2001-01-01

    Reviews a collaborative process established at the University of Calgary in the earliest stages of strategic planning and maintained throughout undergraduate curriculum redesign and implementation. Offers some lessons learned by the change agents operating within a reluctant environment, including: start with serious self-reflection, understand…

  18. High/Low Handbook: Best Books and Web Sites for Reluctant Teen Readers. 4th Edition.

    ERIC Educational Resources Information Center

    LiBretto, Ellen V.; Barr, Catherine

    This handbook is a practical guide to the selection of high-interest, low-reading-level books and Web sites that will inspire a love of reading in teenagers who fall within the category of reluctant readers. It is especially useful for professionals in school and public libraries charged with building collections of suitable titles for these…

  19. The "Reluctant" State and the Beginning of the End of State Education

    ERIC Educational Resources Information Center

    Ball, Stephen J.

    2012-01-01

    This paper argues that English education policy has come full-circle--from the first constitution of a state system of education in 1870 to the beginning of the end of state education in 2010--and that this circularity can be understood in relation to the reluctant state. That is, in the nineteenth century, the English state hesitantly and slowly…

  20. Online Statistics Labs in MSW Research Methods Courses: Reducing Reluctance toward Statistics

    ERIC Educational Resources Information Center

    Elliott, William; Choi, Eunhee; Friedline, Terri

    2013-01-01

    This article presents results from an evaluation of an online statistics lab as part of a foundations research methods course for master's-level social work students. The article discusses factors that contribute to an environment in social work that fosters attitudes of reluctance toward learning and teaching statistics in research methods…

  1. Identification of multi-modal plasma responses to applied magnetic perturbations using the plasma reluctance

    SciTech Connect

    Logan, Nikolas C.; Paz-Soldan, Carlos; Park, Jong-Kyu; Nazikian, Raffi

    2016-05-03

    Using the plasma reluctance, the Ideal Perturbed Equilibrium Code is able to efficiently identify the structure of multi-modal magnetic plasma response measurements and the corresponding impact on plasma performance in the DIII-D tokamak. Recent experiments demonstrated that multiple kink modes of comparable amplitudes can be driven by applied nonaxisymmetric fields with toroidal mode number n = 2. This multi-modal response is in good agreement with ideal magnetohydrodynamic models, but detailed decompositions presented here show that the mode structures are not fully described by either the least stable modes or the resonant plasma response. This paper identifies the measured response fields as the first eigenmodes of the plasma reluctance, enabling clear diagnosis of the plasma modes and their impact on performance from external sensors. The reluctance shows, for example, how very stable modes compose a significant portion of the multi-modal plasma response field and that these stable modes drive significant resonant current. Finally, this work is an overview of the first experimental applications using the reluctance to interpret the measured response and relate it to multifaceted physics, aimed towards providing the foundation of understanding needed to optimize nonaxisymmetric fields for independent control of stability and transport.

  2. Online Statistics Labs in MSW Research Methods Courses: Reducing Reluctance toward Statistics

    ERIC Educational Resources Information Center

    Elliott, William; Choi, Eunhee; Friedline, Terri

    2013-01-01

    This article presents results from an evaluation of an online statistics lab as part of a foundations research methods course for master's-level social work students. The article discusses factors that contribute to an environment in social work that fosters attitudes of reluctance toward learning and teaching statistics in research methods…

  3. The "Reluctant" State and the Beginning of the End of State Education

    ERIC Educational Resources Information Center

    Ball, Stephen J.

    2012-01-01

    This paper argues that English education policy has come full-circle--from the first constitution of a state system of education in 1870 to the beginning of the end of state education in 2010--and that this circularity can be understood in relation to the reluctant state. That is, in the nineteenth century, the English state hesitantly and slowly…

  4. Identification of multi-modal plasma responses to applied magnetic perturbations using the plasma reluctance

    SciTech Connect

    Logan, Nikolas C.; Paz-Soldan, Carlos; Park, Jong-Kyu; Nazikian, Raffi

    2016-05-03

    Using the plasma reluctance, the Ideal Perturbed Equilibrium Code is able to efficiently identify the structure of multi-modal magnetic plasma response measurements and the corresponding impact on plasma performance in the DIII-D tokamak. Recent experiments demonstrated that multiple kink modes of comparable amplitudes can be driven by applied nonaxisymmetric fields with toroidal mode number n = 2. This multi-modal response is in good agreement with ideal magnetohydrodynamic models, but detailed decompositions presented here show that the mode structures are not fully described by either the least stable modes or the resonant plasma response. This paper identifies the measured response fields as the first eigenmodes of the plasma reluctance, enabling clear diagnosis of the plasma modes and their impact on performance from external sensors. The reluctance shows, for example, how very stable modes compose a significant portion of the multi-modal plasma response field and that these stable modes drive significant resonant current. Finally, this work is an overview of the first experimental applications using the reluctance to interpret the measured response and relate it to multifaceted physics, aimed towards providing the foundation of understanding needed to optimize nonaxisymmetric fields for independent control of stability and transport.

  5. Reluctant Mathematician: Skills-Based MOOC Scaffolds Wide Range of Learners

    ERIC Educational Resources Information Center

    Lambert, Sarah

    2015-01-01

    The University of Wollongong's first locally developed and hosted Massive Open Online Course (MOOC) "The Reluctant Mathematician" was run in the last four weeks of our summer holiday, prior to Autumn session in 2014. It was developed to lift maths skills at our university and also in the community--where maths skills continue to be a…

  6. The hybrid BCI.

    PubMed

    Pfurtscheller, Gert; Allison, Brendan Z; Brunner, Clemens; Bauernfeind, Gunther; Solis-Escalante, Teodoro; Scherer, Reinhold; Zander, Thorsten O; Mueller-Putz, Gernot; Neuper, Christa; Birbaumer, Niels

    2010-01-01

    Nowadays, everybody knows what a hybrid car is. A hybrid car normally has two engines to enhance energy efficiency and reduce CO2 output. Similarly, a hybrid brain-computer interface (BCI) is composed of two BCIs, or at least one BCI and another system. A hybrid BCI, like any BCI, must fulfill the following four criteria: (i) the device must rely on signals recorded directly from the brain; (ii) there must be at least one recordable brain signal that the user can intentionally modulate to effect goal-directed behaviour; (iii) real time processing; and (iv) the user must obtain feedback. This paper introduces hybrid BCIs that have already been published or are in development. We also introduce concepts for future work. We describe BCIs that classify two EEG patterns: one is the event-related (de)synchronisation (ERD, ERS) of sensorimotor rhythms, and the other is the steady-state visual evoked potential (SSVEP). Hybrid BCIs can either process their inputs simultaneously, or operate two systems sequentially, where the first system can act as a "brain switch". For example, we describe a hybrid BCI that simultaneously combines ERD and SSVEP BCIs. We also describe a sequential hybrid BCI, in which subjects could use a brain switch to control an SSVEP-based hand orthosis. Subjects who used this hybrid BCI exhibited about half the false positives encountered while using the SSVEP BCI alone. A brain switch can also rely on hemodynamic changes measured through near-infrared spectroscopy (NIRS). Hybrid BCIs can also use one brain signal and a different type of input. This additional input can be an electrophysiological signal such as the heart rate, or a signal from an external device such as an eye tracking system.

  7. Impact of interviewers' supportive comments and children's reluctance to cooperate during sexual abuse disclosure.

    PubMed

    Lewy, Jennifer; Cyr, Mireille; Dion, Jacinthe

    2015-05-01

    In the field of child sexual abuse (CSA) disclosure, many studies have been conducted on the impact of interviewers' questioning style, but few have examined the impact of interviewers' supportive comments on children's cooperative and reluctant disclosure of substantive details. This field study used a sample of children ranging from 4 to 13 years of age who have all disclosed CSA. The first objective was to examine if the interviewer's and the child's comments during CSA interviews would vary as a function of the use of the National Institute of Child Health and Human Development (NICHD) Protocol. The second objective was to identify the strongest correlates of the proportion of details disclosed by the children during forensic interviews. A total of 90 matched NICHD Protocol and non-Protocol interviews done by the same interviewers were audio-taped, transcribed, and coded using verbal subscales. The goal was to explore if differences exist between the interviewers' supportive and non-supportive comments as well as children's cooperative and reluctant statements during investigative interviews conducted prior to or after the NICHD Protocol training. Results of a MANCOVA showed that the use of the NICHD Protocol had no influence on interviewers' and children's demeanors. A hierarchical multiple regression analysis controlling for relevant variables (e.g., child's age and NICHD Protocol) showed that children's reluctance and interviewers' non-support were associated with a lesser proportion of details. Overall, these results indicate that in order to promote detailed disclosure of CSA, interviewers should decrease their non-supportive comments and learn to deal more effectively with children's reluctance during forensic interviews. As such, protocols and training should encourage investigative interviewers to devote more time identifying early signs of children's verbal reluctance and to understand the negative impact of non-supportive comments on the disclosure of

  8. Stackable Organic Switches for Reconfigurable Switching Hybrid Systems

    DTIC Science & Technology

    2013-01-27

    aiming to (a) understand the potential of conjugated polymer based solar cell under simulated space radiation conditions, (2) develop and improving...tandem polymer solar cell structures - constantly pushing the envelope of organic solar cell performance; (3) develop novel polymers for high...of conjugated polymer based solar cell under simulated space radiation conditions, (2) develop and improving tandem polymer solar cell structures

  9. Creep behavior of thin laminates of iron-cobalt alloys for use in switched reluctance motors and generators

    NASA Astrophysics Data System (ADS)

    Fingers, Richard Todd

    The United States Air Force is in the process of developing magnetic bearings as well as an aircraft Integrated Power Unit and an Internal Starter/Generator for main propulsion engines. These developments are the driving force behind a new emphasis on high temperature, high strength magnetic materials for power applications. Analytical work, utilizing elasticity theory, in conjunction with design requirements, indicates a need for magnetic materials to have strengths in excess of 80 ksi up to about 1000sp°F. It is this combination of desired material characteristics that is the motivation for this effort to measure, model, and predict the creep behavior of such advanced magnetic materials. Hipercosp°ler Alloy 50HS, manufactured by Carpenter Technology Corporation, is one of the leading candidates for application and is studied in this effort by subjecting mechanical test specimens to a battery of tensile and creep tests. The tensile tests provide stress versus strain behaviors that clearly indicate: a yield point, a heterogeneous deformation described as Luders elongation, the Portevin-LeChatelier effect at elevated temperatures, and, most often, a section of homogeneous deformation that concluded with necking and fracture. Creep testing indicated two distinct types of behavior. The first was a traditional response with primary, secondary and tertiary stages, while the second type could be characterized by an abrupt increase in strain rate that acted as a transition from one steady state behavior to another. This second linear region was then followed by the tertiary stage. The relationship between the tensile response and the creep responses is discussed. Analyses of the mechanical behavior includes double linear regression of empirically modeled data, scanning electron microscopy for microstructural investigations, isochronous stress-strain relations, and constant strain rate testing to relate the tensile and creep test parameters. Also, elastic and creep deformation analyses are done, which incorporate material property data and material constants determined along with stress and displacement profiles for a specific Air Force design configuration.

  10. Switches And Modulators For Coherent Systems

    NASA Astrophysics Data System (ADS)

    Ner, M. S.; McDonach, A.; Macfadyen, D. N.; Gibson, D. R.; Binnie, C.; Diemeer, M. B. J.

    1988-06-01

    The performance of switches and modulators for coherent systems is described. Emphasis is placed on enviromental stability and reliability of devices based on both Lithium Niobate and Electro-Optical Polymers. For hybrid opto-electronics Niobate devices offer the best performance and have proven reliability for applications in first generation systems. In the longer term hybrid systems using electro-optical polymer based active components are expected to outperform their monolithic semiconductor counterparts.

  11. Magnetic switching

    SciTech Connect

    Birx, D.; Cook, E.; Hawkins, S.; Poor, S.; Reginato, L.; Schmidt, J.; Smith, M.

    1983-06-01

    The paper discusses the development program in magnetic switching which was aimed at solving the rep-rate and reliability limitations of the ATA spark gaps. The end result has been a prototype physically very similar to the present Advanced Test Accelerator (ATA) pulse power unit but vastly superior in performance. This prototype, which is easily adaptable to the existing systems, has achieved a burst rep-rate of 20 kHz and an output voltage of 500 kV. A one-on-one substitution of the existing pulse power module would result in a 100 MeV accelerator. Furthermore, the high efficiency of the magnetic pulse compression stages has allowed CW operation of the prototype at one kilohertz opening up other applications for the pulse power. Performance and design details will be described.

  12. Plasma Switch Development.

    DTIC Science & Technology

    1984-06-08

    switch :9 (1) the low-pressure gas switch 17 (2) the surface flashover switch ,18 (3) the thyrtron,’ŕ (4) the high pressure...spark gap, (5) the magnetic switch .’ 9 20 and (6) the ECS. The ongoing research for both the low pressure gas and surface flashover closing- switches has... investigations into optimizing gas mixtures for opening switch applications 1 ’"’"’’’a𔃻 ; and a preliminary study of the discharge stabili-

  13. Performance Analysis of a Self-Excited Synchronous Reluctance Generator with Multiple-Barrier Rotor

    NASA Astrophysics Data System (ADS)

    Kawasaki, Kouichi; Fukami, Tadashi; Hanaoka, Ryoichi; Takata, Shinzo

    The modeling and steady-state performance of a self-excited synchronous reluctance generator (SESRG) that has a multiple-barrier (MB) rotor is set forth in this paper. In addition to the core loss, the magnetic saturation in both d-q axes is included in the developed model. Experimental results conducted on a 0.75-kVA testing machine are provided to justify the analytical approach and performance calculations.

  14. Influence of magnetic reluctances of magnetic elements on servo valve torque motors

    NASA Astrophysics Data System (ADS)

    Liu, Changhai; Jiang, Hongzhou

    2016-01-01

    The current research of electro-hydraulic servo valves mainly focuses on the vibration, pressure oscillating and source of noise. Unfortunately, literatures relating to the study of the influence of the magnetic reluctances of the magnetic elements are rarely available. This paper aims to analyze the influence of the magnetic reluctances of the magnetic elements on torque motor. Considering these magnetic reluctances ignored in previous literatures, a new mathematical model of servo valve torque motor is developed and proposed based on the fundamental laws of electromagnetism. By using this new mathematical model and the previous models, electromagnetic torque constant and magnetic spring stiffness are evaluated for a given set of torque motor parameters. A computer simulation by using AMESim software is also performed for the same set of torque motor parameters to verify the proposed model. The theoretical results of electromagnetic torque constant and magnetic spring stiffness evaluated by the proposed model render closer agreement with the simulation results than those evaluated by the previous models. In addition, an experimental measurement of the magnetic flux densities in the air-gaps is carried out by using SFL218 servo valve torque motor. Compared with the theoretical results of the magnetic flux densities in the air-gaps evaluated by the previous models, the theoretical results evaluated by the proposed model also show better agreement with the experimental data. The proposed model shows the influence of the magnetic reluctances of the magnetic elements on the servo valve torque motor, and offers modified and analytical expressions to electromagnetic torque constant and magnetic spring stiffness. These modified and analytical expressions could provide guidance more accurately for a linear control design approach and sensitivity analysis on electro-hydraulic servo valves than the previous expressions.

  15. Why are Dutch rheumatologists reluctant to use the COBRA treatment strategy in early rheumatoid arthritis?

    PubMed Central

    van Tuyl, Lilian H D; Plass, Anne Marie C; Lems, Willem F; Voskuyl, Alexandre E; Dijkmans, Ben A C; Boers, Maarten

    2007-01-01

    Background The Combinatietherapie Bij Reumatoide Artritis (COBRA) trial has proved that combination therapy with prednisolone, methotrexate and sulphasalazine is superior to sulphasalazine monotherapy in suppressing disease activity and radiological progression of early rheumatoid arthritis (RA). In addition, 5 years of follow‐up proved that COBRA therapy results in sustained reduction of the rate of radiological progression. Despite this evidence, Dutch rheumatologists seem reluctant to prescribe COBRA therapy. Objective To explore the reasons for the reluctance in Dutch rheumatologists to prescribe COBRA therapy. Methods A short structured questionnaire based on social–psychological theories of behaviour was sent to all Dutch rheumatologists (n = 230). Results The response rate was 50%. COBRA therapy was perceived as both effective and safe, but complex to administer. Furthermore, rheumatologists expressed their concern about the large number of pills that had to be taken, the side effects of high‐dose prednisolone and the low dose of methotrexate. Although the average attitude towards the COBRA therapy was slightly positive (above the neutral point), the majority of responding rheumatologists had a negative intention (below the neutral point) to prescribe COBRA therapy in the near future. Conclusion The reluctance of Dutch rheumatologists to prescribe effective COBRA therapy may be due to perceptions of complexity of the treatment schedule and negative patient‐related consequences of the therapy. PMID:17392349

  16. Why are Dutch rheumatologists reluctant to use the COBRA treatment strategy in early rheumatoid arthritis?

    PubMed

    van Tuyl, Lilian H D; Plass, Anne Marie C; Lems, Willem F; Voskuyl, Alexandre E; Dijkmans, Ben A C; Boers, Maarten

    2007-07-01

    The Combinatietherapie Bij Reumatoide Artritis (COBRA) trial has proved that combination therapy with prednisolone, methotrexate and sulphasalazine is superior to sulphasalazine monotherapy in suppressing disease activity and radiological progression of early rheumatoid arthritis (RA). In addition, 5 years of follow-up proved that COBRA therapy results in sustained reduction of the rate of radiological progression. Despite this evidence, Dutch rheumatologists seem reluctant to prescribe COBRA therapy. To explore the reasons for the reluctance in Dutch rheumatologists to prescribe COBRA therapy. A short structured questionnaire based on social-psychological theories of behaviour was sent to all Dutch rheumatologists (n = 230). The response rate was 50%. COBRA therapy was perceived as both effective and safe, but complex to administer. Furthermore, rheumatologists expressed their concern about the large number of pills that had to be taken, the side effects of high-dose prednisolone and the low dose of methotrexate. Although the average attitude towards the COBRA therapy was slightly positive (above the neutral point), the majority of responding rheumatologists had a negative intention (below the neutral point) to prescribe COBRA therapy in the near future. The reluctance of Dutch rheumatologists to prescribe effective COBRA therapy may be due to perceptions of complexity of the treatment schedule and negative patient-related consequences of the therapy.

  17. The complex initial reluctivity, permeability and susceptibility spectra of magnetic materials

    NASA Astrophysics Data System (ADS)

    Hamilton, N. C.

    2015-03-01

    The HF complex permeability spectrum of a magnetic material is deduced from the measured impedance spectrum, which is then normalized to a series permeability spectrum. However, this series permeability spectrum has previously been shown to correspond to a parallel magnetic circuit, which is not appropriate. Some of the implications of this truth are examined. This electric/magnetic duality has frustrated efforts to interpret the shape of the complex magnetic permeability spectra of materials, and has hindered the application of impedance spectroscopy to magnetic materials. In the presence of magnetic loss, the relationship between the relative magnetic permeability and the magnetic susceptibility is called into question. The use of reluctivity spectra for expressing magnetic material properties is advocated. The relative loss factor, tanδm/μi is shown to be an approximation for the imaginary part of the reluctivity. A single relaxation model for the initial reluctivity spectra of magnetic materials is presented, and its principles are applied to measurements of a high permeability ferrite. The results are presented as contour plots of the spectra as a function of temperature.

  18. Switch Transcripts in Immunoglobulin Class Switching

    NASA Astrophysics Data System (ADS)

    Lorenz, Matthias; Jung, Steffen; Radbruch, Andreas

    1995-03-01

    B cells can exchange gene segments for the constant region of the immunoglobulin heavy chain, altering the class and effector function of the antibodies that they produce. Class switching is directed to distinct classes by cytokines, which induce transcription of the targeted DNA sequences. These transcripts are processed, resulting in spliced "switch" transcripts. Switch recombination can be directed to immunoglobulin G1 (IgG1) by the heterologous human metallothionein II_A promoter in mutant mice. Induction of the structurally conserved, spliced switch transcripts is sufficient to target switch recombination to IgG1, whereas transcription alone is not.

  19. Language and task switching in the bilingual brain: Bilinguals are staying, not switching, experts.

    PubMed

    Weissberger, Gali H; Gollan, Tamar H; Bondi, Mark W; Clark, Lindsay R; Wierenga, Christina E

    2015-01-01

    Bilinguals' ability to control which language they speak and to switch between languages may rely on neurocognitive mechanisms shared with non-linguistic task switching. However, recent studies also reveal some limitations on the extent control mechanisms are shared across domains, introducing the possibility that some control mechanisms are unique to language. We investigated this hypothesis by directly comparing the neural correlates of task switching and language switching. Nineteen Spanish-English bilingual university students underwent a functional magnetic resonance imaging (fMRI) study employing a hybrid (event-related and blocked) design involving both color-shape switching and language switching paradigms. We compared the two switching tasks using within-subject voxel-wise t-tests for each of three trial types (single trials in single blocks, and stay and switch trials in mixed blocks). Comparing trial types to baseline in each task revealed widespread activation for single, stay, and switch trials in both color-shape and language switching. Direct comparisons of each task for each trial type revealed few differences between tasks on single and switch trials, but large task differences during stay trials, with more widespread activation for the non-linguistic than for the language task. Our results confirm previous suggestions of shared mechanisms of switching across domains, but also reveal bilinguals have greater efficiency for sustaining the inhibition of the non-target language than the non-target task when two responses are available. This efficiency of language control might arise from bilinguals' need to control interference from the non-target language specifically when not switching languages, when speaking in single- or mixed-language contexts.

  20. Permanent magnet machine and method with reluctance poles and non-identical PM poles for high density operation

    DOEpatents

    Hsu, John S.

    2010-05-18

    A method and apparatus in which a stator (11) and a rotor (12) define a primary air gap (20) for receiving AC flux and at least one source (23, 40), and preferably two sources (23, 24, 40) of DC excitation are positioned for inducing DC flux at opposite ends of the rotor (12). Portions of PM material (17, 17a) are provided as boundaries separating PM rotor pole portions from each other and from reluctance poles. The PM poles (18) and the reluctance poles (19) can be formed with poles of one polarity having enlarged flux paths in relation to flux paths for pole portions of an opposite polarity, the enlarged flux paths communicating with a core of the rotor (12) so as to increase reluctance torque produced by the electric machine. Reluctance torque is increased by providing asymmetrical pole faces. The DC excitation can also use asymmetric poles and asymmetric excitation sources. Several embodiments are disclosed with additional variations.

  1. Design and development of a 5 kV isolated solid state switch

    NASA Technical Reports Server (NTRS)

    Holbrook, R. J.; Scapple, R. Y.; Keister, F. Z.; Gooder, S. T.

    1975-01-01

    A unique microcircuit intended for use as a shorting switch for large extraterrestrial solar cell arrays is described. The packaging design for the 5 kV isolated hybrid switch is different from most hybrid microcircuits in that it utilizes a compartmentalized plastic case (a portion of which is encapsulated), is not hermetic, and is designed for high voltage operation.

  2. High power ferrite microwave switch

    NASA Technical Reports Server (NTRS)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  3. Latching relay switch assembly

    DOEpatents

    Duimstra, Frederick A.

    1991-01-01

    A latching relay switch assembly which includes a coil section and a switch or contact section. The coil section includes at least one permanent magnet and at least one electromagnet. The respective sections are, generally, arranged in separate locations or cavities in the assembly. The switch is latched by a permanent magnet assembly and selectively switched by an overriding electromagnetic assembly.

  4. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E.

    1990-03-06

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  5. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E.

    1990-01-01

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  6. A Mechanochemical Switch to Control Radical Intermediates

    PubMed Central

    2015-01-01

    B12-dependent enzymes employ radical species with exceptional prowess to catalyze some of the most chemically challenging, thermodynamically unfavorable reactions. However, dealing with highly reactive intermediates is an extremely demanding task, requiring sophisticated control strategies to prevent unwanted side reactions. Using hybrid quantum mechanical/molecular mechanical simulations, we follow the full catalytic cycle of an AdoB12-dependent enzyme and present the details of a mechanism that utilizes a highly effective mechanochemical switch. When the switch is “off”, the 5′-deoxyadenosyl radical moiety is stabilized by releasing the internal strain of an enzyme-imposed conformation. Turning the switch “on,” the enzyme environment becomes the driving force to impose a distinct conformation of the 5′-deoxyadenosyl radical to avoid deleterious radical transfer. This mechanochemical switch illustrates the elaborate way in which enzymes attain selectivity of extremely chemically challenging reactions. PMID:24846280

  7. A mechanochemical switch to control radical intermediates.

    PubMed

    Brunk, Elizabeth; Kellett, Whitney F; Richards, Nigel G J; Rothlisberger, Ursula

    2014-06-17

    B₁₂-dependent enzymes employ radical species with exceptional prowess to catalyze some of the most chemically challenging, thermodynamically unfavorable reactions. However, dealing with highly reactive intermediates is an extremely demanding task, requiring sophisticated control strategies to prevent unwanted side reactions. Using hybrid quantum mechanical/molecular mechanical simulations, we follow the full catalytic cycle of an AdoB₁₂-dependent enzyme and present the details of a mechanism that utilizes a highly effective mechanochemical switch. When the switch is "off", the 5'-deoxyadenosyl radical moiety is stabilized by releasing the internal strain of an enzyme-imposed conformation. Turning the switch "on," the enzyme environment becomes the driving force to impose a distinct conformation of the 5'-deoxyadenosyl radical to avoid deleterious radical transfer. This mechanochemical switch illustrates the elaborate way in which enzymes attain selectivity of extremely chemically challenging reactions.

  8. Sequential Modulation of Cue Use in the Task Switching Paradigm

    PubMed Central

    Wendt, Mike; Luna-Rodriguez, Aquiles; Reisenauer, Renate; Jacobsen, Thomas; Dreisbach, Gesine

    2012-01-01

    In task switching studies, pre-cuing of the upcoming task improves performance, indicating preparatory activation of the upcoming task-set, and/or inhibition of the previous task-set. To further investigate cue-based task preparation, the authors presented both valid and invalid task cues in a task switching experiment involving three tasks. Consistent with previous findings, a validity effect in terms of higher reaction times on invalidly compared to validly cued tasks was obtained. However, this validity effect was reduced following invalidly cued trials, suggesting dynamic adjustment in terms of decreased cue-based preparation after being misled. Performance was particularly impaired when the current task was the one that was invalidly cued on the preceding trial. This finding may reflect either particular reluctance to prepare or persisting inhibition of the erroneously prepared task-set from the pre-trial. PMID:22908004

  9. Hybrid model for solidification and convection

    NASA Technical Reports Server (NTRS)

    Oldenburg, Curtis M.; Spera, Frank J.

    1992-01-01

    A hybrid model for continuum phase-change problems is presented. The hybrid model accounts for flow in regions of concentrated mush, dilute mush, and single-phase liquid. Scale analysis shows that, in dilute mush, the Blake-Kozeny-Carman relation may lead to inaccuracy in the continuum formulation for certain values of the Rayleigh and Darcy numbers. The hybrid model uses arctangent switching functions to switch on the Darcy flow and variable viscosity terms depending on the local value of the fraction solid. Two-dimensional example calculations suggest that the hybrid model more accurately accounts for transport in the dilute mush region.

  10. Temporal switching jitter in photoconductive switches

    SciTech Connect

    GAUDET,JOHN A.; SKIPPER,MICHAEL C.; ABDALLA,MICHAEL D.; AHERN,SEAN M.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; ROMERO,SAMUEL P.

    2000-04-13

    This paper reports on a recent comparison made between the Air Force Research Laboratory (AFRL) gallium arsenide, optically-triggered switch test configuration and the Sandia National Laboratories (SNL) gallium arsenide, optically-triggered switch test configuration. The purpose of these measurements was to compare the temporal switch jitter times. It is found that the optical trigger laser characteristics are dominant in determining the PCSS jitter.

  11. Construction of an Effective Landscape for Multistate Genetic Switches

    NASA Astrophysics Data System (ADS)

    Lu, Mingyang; Onuchic, José; Ben-Jacob, Eshel

    2014-08-01

    Multistate genetic switches play a crucial role during embryonic development and tumorigenesis. An archetypical example is the three-way switch regulating epithelial-hybrid-mesenchymal transitions. We devise a special WKB-based approach to investigate white Gaussian and shot noise effects on three-way switches, and construct an effective landscape in good quantitative agreement with stochastic simulations. This approach allows efficient analytical or numerical calculation of the landscape contours, the optimal path, and the state relative stability for general multicomponent multistate switches.

  12. Reluctance to Accept Alcohol Treatment by Alcoholic Liver Disease Transplant Patients: A Qualitative Study

    PubMed Central

    Heyes, Cathy M.; Schofield, Toni; Gribble, Robert; Day, Carolyn A.; Haber, Paul S.

    2016-01-01

    Background Liver transplantation (LT) is the optimum treatment for patients with end-stage alcoholic liver disease (ALD). However, despite a recognized risk of relapse to harmful drinking, ALD transplant patients are reluctant to use speciality alcohol treatment to support their abstinence, even when offered within the LT context. This study aimed to understand and identify factors contributing to alcohol treatment reluctance by ALD patients undergoing transplantation. Methods We conducted an in-depth qualitative study of ALD transplant patients. Minimally structured face-to-face interviews explored participants' alcohol-related experiences and their reasons for not using alcohol treatment during the course of their transplantation. Thematic analysis was used to analyze and interpret interview data to understand treatment reluctance based on participants' experiences. Results Five major themes were identified among 3 subgroups of patients (pretransplant and posttransplant abstainers and posttransplant relapsers): (i) the “contract” of mandatory abstinence, (ii) the “gap in the program” involving the lack of candour between patient and staff about alcohol-related matters and the lack of addiction services, (iii) a preference by participants to self-manage their alcohol use disorder, (iv) social support as a facilitator of abstinence and the risk of relapse when social support is diminished, and (v) the fear of stigmatization. Each of these factors were dynamically interrelated and differed slightly for each subgroup. Conclusions The LT services may benefit from the inclusion of integrated specialist addiction services in their model of care. Such an approach may enhance the acceptability of alcohol treatment and reduce the risk of relapse among ALD transplant participants, especially for those whose social supports have diminished. PMID:27795986

  13. Latching micro optical switch

    DOEpatents

    Garcia, Ernest J; Polosky, Marc A

    2013-05-21

    An optical switch reliably maintains its on or off state even when subjected to environments where the switch is bumped or otherwise moved. In addition, the optical switch maintains its on or off state indefinitely without requiring external power. External power is used only to transition the switch from one state to the other. The optical switch is configured with a fixed optical fiber and a movable optical fiber. The movable optical fiber is guided by various actuators in conjunction with a latching mechanism that configure the switch in one position that corresponds to the on state and in another position that corresponds to the off state.

  14. A miniature Hopkinson experiment device based on multistage reluctance coil electromagnetic launch.

    PubMed

    Huang, Wenkai; Huan, Shi; Xiao, Ying

    2017-09-01

    A set of seven-stage reluctance miniaturized Hopkinson bar electromagnetic launcher has been developed in this paper. With the characteristics of high precision, small size, and little noise pollution, the device complies with the requirements of miniaturized Hopkinson bar for high strain rate. The launcher is a seven-stage accelerating device up to 65.5 m/s. A high performance microcontroller is used to control accurately the discharge of capacitor sets, by means of which the outlet velocity of the projectile can be controlled within a certain velocity range.

  15. A miniature Hopkinson experiment device based on multistage reluctance coil electromagnetic launch

    NASA Astrophysics Data System (ADS)

    Huang, Wenkai; Huan, Shi; Xiao, Ying

    2017-09-01

    A set of seven-stage reluctance miniaturized Hopkinson bar electromagnetic launcher has been developed in this paper. With the characteristics of high precision, small size, and little noise pollution, the device complies with the requirements of miniaturized Hopkinson bar for high strain rate. The launcher is a seven-stage accelerating device up to 65.5 m/s. A high performance microcontroller is used to control accurately the discharge of capacitor sets, by means of which the outlet velocity of the projectile can be controlled within a certain velocity range.

  16. Improvements of Power Factor and Torque of a Synchronous Reluctance Motor with a Slit Rotor

    NASA Astrophysics Data System (ADS)

    Nashiki, Masayuki; Inoue, Yoshimitu; Kawai, Youichi; Yokochi, Takanori; Satake, Akiyoshi; Okuma, Shigeru

    Power factor and torque of synchronous reluctance motors with a slit rotor are studied. In there stators, divided teeth made of powder magnetic core are adopted and windings are improved to get high space factor of stator windings and to shorten coil ends. In there rotors, stainless sheets are inserted among soft magnetic metal sheets with adhesive to strengthen the rotors and rotor structure is improved to enlarge the saliency ratio (Ld/Lq). As the result, the power factor 0.78 and 1.6 times torque at same motor size are attained.

  17. Extensive Reading Program Which Changes Reluctant Engineering Students into Autonomous Learners of English

    NASA Astrophysics Data System (ADS)

    Nishizawa, Hitoshi; Yoshioka, Takayoshi; Itoh, Kazuaki

    This article introduces extensive reading (ER) as an approach to improve fundamental communication skills in English of reluctant EFL learners : average Japanese engineering students. It is distinct from concurrent translation approach from a perspective that the learners use English instead of Japanese to grasp the meaning of what they read and enjoy reading. In the ER program at Toyota National College of Technology, many students developed more positive attitude toward English, increased their reading speed, and achieved higher TOEIC scores, which was compared to those of the students before this ER program was introduced. Comparison between three groups of the students showed strong correlation between their TOEIC scores and the reading amount.

  18. My snowflake is so unique … Experiences of a reluctant Data Scientist

    NASA Astrophysics Data System (ADS)

    Ritchey, N. A.; Kearns, E. J.

    2014-12-01

    As with many data scientists, this wasn't my initial career objective. In fact it wasn't even seen as a viable option at that time. However I needed to manage data for my physical science projects and the teams I supported, so I reluctantly accepted this task as part of my "real" science job. Over the years, many challenges have been solved, that then allow us the ability to address more difficult issues. This presentation will address current data scientist challenges from a "real" scientist's perspective at a federal archive.

  19. Heat Switches for ADRs

    NASA Technical Reports Server (NTRS)

    DiPirro, M. J.; Shirron, P. J.

    2014-01-01

    Heat switches are key elements in the cyclic operation of Adiabatic Demagnetization Refrigerators (ADRs). Several of the types of heat switches that have been used for ADRs are described in this paper. Key elements in selection and design of these switches include not only ON/OFF switching ratio, but also method of actuation, size, weight, and structural soundness. Some of the trade-off are detailed in this paper.

  20. Heat switches for ADRs

    NASA Astrophysics Data System (ADS)

    DiPirro, M. J.; Shirron, P. J.

    2014-07-01

    Heat switches are key elements in the cyclic operation of Adiabatic Demagnetization Refrigerators (ADRs). Several of the types of heat switches that have been used for ADRs are described in this paper. Key elements in selection and design of these switches include not only ON/OFF switching ratio, but also method of actuation, size, weight, and structural soundness. Some of the trade-off are detailed in this paper.

  1. Remote switch actuator

    DOEpatents

    Haas, Edwin Gerard; Beauman, Ronald; Palo, Jr., Stefan

    2013-01-29

    The invention provides a device and method for actuating electrical switches remotely. The device is removably attached to the switch and is actuated through the transfer of a user's force. The user is able to remain physically removed from the switch site obviating need for protective equipment. The device and method allow rapid, safe actuation of high-voltage or high-current carrying electrical switches or circuit breakers.

  2. Call for Papers: Photonics in Switching

    NASA Astrophysics Data System (ADS)

    Wosinska, Lena; Glick, Madeleine

    2006-04-01

  3. Hybrid OBS/TDM or OBS/wavelength routing
  4. Manuscript Submission

    To submit to this special issue, follow the normal procedure for submission to JON and select ``Photonics in Switching' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Photonics in Switching.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 15 September 2006

  5. Torque Ripple Reduction of Reluctance Torque Assisted Motors Using Asymmetric Flux Barriers

    NASA Astrophysics Data System (ADS)

    Hiramoto, Kenji; Takeda, Yoji; Sanada, Masayuki; Morimoto, Shigeo

    Interior permanent magnet synchronous motor (IPMSM) is efficient and can be operated in wide speed region; therefore it is used widely. However, torque ripple of reluctance torque assisted motors, for example IPMSM and synchronous reluctance motor (SynRM), is very large. The skew is known in the prior art as a torque ripple reduction method of AC motors. Although the skew is effective for torque ripple reduction, structure is complicated and it has the disadvantage that average torque will decrease. The discontinuous variation of magnetic resistance between flux barriers and teeth cause the torque ripple. In this paper, in order to ease the discontinuous variation of magnetic resistance, flux barriers are asymmetrically designed so that the relative position relation between flux barriers and teeth may not be in agreement as much as possible. As a result, the torque ripple can be reduced dramatically without the average torque decrease. The experimental motor has been fabricated and the results of measuring torque ripple prove the validity of the torque ripple reduction using asymmetric flux barriers.

  6. High output power reluctance electric motors with bulk high-temperature superconductor elements

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; Larionoff, A. E.; M-A Koneev, S.; Modestov, K. A.; Larionoff, S. A.; Poltavets, V. N.; Akimov, I. I.; Alexandrov, V. V.; Gawalek, W.; Oswald, B.; Krabbes, G.

    2002-05-01

    We present new types of electric machines with the rotors containing bulk high-temperature superconductor (HTS) - YBCO and Bi-Ag - elements. We discuss different schematics of hysteresis, reluctance, 'trapped field' and composed synchronous HTS machines. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the single-domain and polycrystal YBCO ceramic samples and plate shape Bi-Ag elements. We give the test results of the series of hysteresis, reluctance, 'trapped field' and composed with permanent magnets HTS motors with an output power rating of 0.1-18 kW and current frequencies 50 Hz and 400 Hz. These results show that in the media of liquid nitrogen the specific output power per one unit weight of the HTS motor is four to seven times better than for conventional electric machines. A comparison of the theoretical and experimental characteristics of the developed HTS motors show that they are in good agreement. We discuss the test results for a liquid nitrogen cryogenic pump system with a hysteresis 500 W HTS motor. We describe several designs of new HTS motors operating in the media of liquid nitrogen with an output power 125 kW (and more) and a power factor of more than 0.8. We discuss future applications of new types of HTS motors for aerospace technology, on-land industry and transport systems.

  7. A non-contact mechanical solution for implementing synchronized switching techniques for energy harvesting using reed switches

    NASA Astrophysics Data System (ADS)

    Shih, Ya Shan; Vasic, Dejan; Jong Wu, Wen

    2016-12-01

    In this work we proposed a new mechanical method of implementing the synchronized switching technique for piezoelectric energy harvesting based on reed switches. Serving as a mechanical displacement monitor and the switch itself, it holds the merit of non-contact, persistence, and the low voltage threshold of merely a single PN junction. However, as all mechanical switches inherits chattering, or bouncing, energy loss and damping on the inversion was caused. To side pass the chattering, three types of electro-mechanical hybrid switches were furthermore developed to stabilize the interfered current flow: resistor-capacitor snubbers, inductor-capacitor snubbers, and silicon controlled rectifiers (SCRs). Each of the method has its merit and suitable working conditions. Comparing to conventional electrical switches, the proposed switches, greatly reduced the switch impedance since the mechanical switch part provides a physically open switch, and the electrical switch part merely consist of either a diode and a MOSFET pair, or a single SCR. Subsequently, the power loss due to the circuit was efficiently eliminated.

  8. Apollo Ring Optical Switch

    SciTech Connect

    Maestas, J.H.

    1987-03-01

    An optical switch was designed, built, and installed at Sandia National Laboratories in Albuquerque, New Mexico, to facilitate the integration of two Apollo computer networks into a single network. This report presents an overview of the optical switch as well as its layout, switch testing procedure and test data, and installation.

  9. Triggered plasma opening switch

    DOEpatents

    Mendel, Clifford W.

    1988-01-01

    A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

  10. The Influence of Training, Reluctance, Efficacy, and Stigma on Suicide Intervention Behavior Among NCOs in the Army and Marine Corps.

    PubMed

    Ayer, Lynsay; Ramchand, Rajeev; Geyer, Lily; Burgette, Lane; Kofner, Aaron

    2016-06-01

    The Army and Marine Corps have consistently experienced the highest rates of suicide relative to the other services. In both the Army and Marine Corps, the service members responsible for identifying and referring individuals at risk for suicide are called "gatekeepers" and are typically noncommissioned officers (NCOs). We used structural equation modeling on survey responses from 1184 Army soldiers and 796 marines to estimate the relationships between training, intervention efficacy, reluctance, and mental health stigma on NCO intervention behaviors. Efficacy and reluctance were independently associated with intervention behaviors, and stigma was only associated with intervention behaviors among Army NCOs. Study results suggest that while quantity of training may help NCOs feel more confident about their ability to intervene, other efforts such as changing training content and delivery mode (e.g., interactive vs. didactic training) may be necessary in order to reduce reluctance and stigma to intervene with service members at risk for suicide.

  11. Hybrid Solar GHP Simulator

    SciTech Connect

    Yavuzturk, Cy; Chiasson, Andrew; Shonder, John

    2012-12-11

    This project provides an easy-to-use, menu-driven, software tool for designing hybrid solar-geothermal heat pump systems (GHP) for both heating- and cooling-dominated buildings. No such design tool currently exists. In heating-dominated buildings, the design approach takes advantage of glazed solar collectors to effectively balance the annual thermal loads on the ground with renewable solar energy. In cooling-dominated climates, the design approach takes advantage of relatively low-cost, unglazed solar collectors as the heat rejecting component. The primary benefit of hybrid GHPs is the reduced initial cost of the ground heat exchanger (GHX). Furthermore, solar thermal collectors can be used to balance the ground loads over the annual cycle, thus making the GHX fully sustainable; in heating-dominated buildings, the hybrid energy source (i.e., solar) is renewable, in contrast to a typical fossil fuel boiler or electric resistance as the hybrid component; in cooling-dominated buildings, use of unglazed solar collectors as a heat rejecter allows for passive heat rejection, in contrast to a cooling tower that consumes a significant amount of energy to operate, and hybrid GHPs can expand the market by allowing reduced GHX footprint in both heating- and cooling-dominated climates. The design tool allows for the straight-forward design of innovative GHP systems that currently pose a significant design challenge. The project lays the foundations for proper and reliable design of hybrid GHP systems, overcoming a series of difficult and cumbersome steps without the use of a system simulation approach, and without an automated optimization scheme. As new technologies and design concepts emerge, sophisticated design tools and methodologies must accompany them and be made usable for practitioners. Lack of reliable design tools results in reluctance of practitioners to implement more complex systems. A menu-driven software tool for the design of hybrid solar GHP systems is

  12. REMOTE CONTROLLED SWITCHING DEVICE

    DOEpatents

    Hobbs, J.C.

    1959-02-01

    An electrical switching device which can be remotely controlled and in which one or more switches may be accurately operated at predetermined times or with predetermined intervening time intervals is described. The switching device consists essentially of a deck, a post projecting from the deck at right angles thereto, cam means mounted for rotation around said posts and a switch connected to said deck and actuated by said cam means. Means is provided for rotating the cam means at a constant speed and the switching apparatus is enclosed in a sealed container with external adjusting means and electrical connection elements.

  13. On the Switching Control

    NASA Astrophysics Data System (ADS)

    Balas, Valentina E.; Balas, Marius M.

    2009-04-01

    The paper is discussing the measures able to reject the instability that may unexpectedly appear in particular conditions, in switching controllers applications. The switching controllers' effect is explained by the combined effects of the unsuitable choice of the switching moments (in the first or third quadrants of the phase trajectory of the switching error) and of the temporal aliasing that can distort the digital control systems when the sampling rate is close to the frequency of the oscillations that are produced by the commutation. The correct switching moments are located into the second and fourth quadrants of the phase trajectory of the switching error, but an active preparation of the commutation may be simply achieved by using a tracking controller, that is driving the output of open loop controller to follow the output of the close loop controller, permanently minimizing the switching error. Simulations issued from a dc driver speed controller and from an aircraft are provided.

  14. Calculation and Measurement of Coil Inductance Profile in Tubular Linear Reluctance Motor and its Validation by Three Dimensional FEM

    NASA Astrophysics Data System (ADS)

    Mosallanejad, Ali; Shoulaie, Abbas

    2011-07-01

    This paper reports a study of coil inductance profile in all positions of plunger in tubular linear reluctance motors (TLRMs) with open type magnetic circuits. In this paper, maximum inductance calculation methods in winding of tubular linear reluctance motors are described based on energy method. Furthermore, in order to calculate the maximum inductance, equivalent permeability is measured. Electromagnetic finite-element analysis for simulation and calculation of coil inductance in this motor is used. Simulation results of coil inductance calculation using 3-D FEM with coil current excitation is compared to theoretical and experimental results. The comparison yields a good agreement.

  15. Advanced Propulsion Power Distribution System for Next Generation Electric/Hybrid Vehicle. Phase 1; Preliminary System Studies

    NASA Technical Reports Server (NTRS)

    Bose, Bimal K.; Kim, Min-Huei

    1995-01-01

    The report essentially summarizes the work performed in order to satisfy the above project objective. In the beginning, different energy storage devices, such as battery, flywheel and ultra capacitor are reviewed and compared, establishing the superiority of the battery. Then, the possible power sources, such as IC engine, diesel engine, gas turbine and fuel cell are reviewed and compared, and the superiority of IC engine has been established. Different types of machines for drive motor/engine generator, such as induction machine, PM synchronous machine and switched reluctance machine are compared, and the induction machine is established as the superior candidate. Similar discussion was made for power converters and devices. The Insulated Gate Bipolar Transistor (IGBT) appears to be the most superior device although Mercury Cadmium Telluride (MCT) shows future promise. Different types of candidate distribution systems with the possible combinations of power and energy sources have been discussed and the most viable system consisting of battery, IC engine and induction machine has been identified. Then, HFAC system has been compared with the DC system establishing the superiority of the former. The detailed component sizing calculations of HFAC and DC systems reinforce the superiority of the former. A preliminary control strategy has been developed for the candidate HFAC system. Finally, modeling and simulation study have been made to validate the system performance. The study in the report demonstrates the superiority of HFAC distribution system for next generation electric/hybrid vehicle.

  16. Design and development of a 5 kV isolated solid state switch

    NASA Technical Reports Server (NTRS)

    Holbrook, R. J.; Scapple, R. Y.; Keister, F. Z.; Gooder, S. T.

    1975-01-01

    This paper describes the design and fabrication of a 5000 volt isolated hybrid switch developed by Hughes Aircraft Company under contract to NASA/Lewis. Hughes did the packaging design and NASA did the circuit design. This unique microcircuit is intended for use as a shorting switch for large extraterrestrial solar cell arrays. The packaging design for the 5 kV isolated hybrid switch is different from most hybrid microcircuits in that it utilizes a compartmentalized plastic case (a portion of which is encapsulated), is not hermetic, and is designed for high voltage operation.

  17. Design and development of a 5 kV isolated solid state switch

    NASA Technical Reports Server (NTRS)

    Holbrook, R. J.; Scapple, R. Y.; Keister, F. Z.; Gooder, S. T.

    1975-01-01

    This paper describes the design and fabrication of a 5000 volt isolated hybrid switch developed by Hughes Aircraft Company under contract to NASA/Lewis. Hughes did the packaging design and NASA did the circuit design. This unique microcircuit is intended for use as a shorting switch for large extraterrestrial solar cell arrays. The packaging design for the 5 kV isolated hybrid switch is different from most hybrid microcircuits in that it utilizes a compartmentalized plastic case (a portion of which is encapsulated), is not hermetic, and is designed for high voltage operation.

  18. Conoco gives shot of CO/sub 2/ to reluctant reservoir

    SciTech Connect

    Wash, R.

    1981-06-01

    The Ford-Geraldine Field in Reeves and Culberson Counties, Texas, has earned itself the title reluctant reservoir. Through initial production and a secondary recovery attempt by waterflood, the unit has yielded only approximately 1/4 of the estimated 93 million bbl of original oil in place, leaving field operators to discover a way of retrieving the approximately 70 million bbl remaining in the ground. As a solution to the field's stubbornness in giving up its oil reserves, Conoco Inc. has implemented a third recovery project involving the injection of 96.9 billion cu ft of carbon dioxide over an 8-yr period. The company hopes to recover an additional 8.45 million bbl which is 11.6% of the remaining oil in place and 9.1% of the original oil in place.

  19. 2D analytical modeling of a wholly superconducting synchronous reluctance motor

    NASA Astrophysics Data System (ADS)

    Malé, G.; Lubin, T.; Mezani, S.; Lévêque, J.

    2011-03-01

    An analytical computation of the magnetic field distribution in a wholly superconducting synchronous reluctance motor is proposed. The stator of the studied motor consists of three-phase HTS armature windings fed by AC currents. The rotor is made with HTS bulks which have a nearly diamagnetic behavior under zero field cooling. The electromagnetic torque is obtained by the interaction between the rotating magnetic field created by the HTS windings and the HTS bulks. The proposed analytical model is based on the resolution of Laplace's and Poisson's equations (by the separation-of-variables technique) for each sub-domain, i.e. stator windings, air-gap, holes between HTS bulks and exterior iron shield. For the study, the HTS bulks are considered as perfect diamagnetic materials. The boundary and continuity conditions between the sub-domains yield to the global solution. Magnetic field distributions and electromagnetic torque obtained by the analytical method are compared with those obtained from finite element analyses.

  20. Algebraic dual-energy magnetic analysis with application to variable reluctance motor design

    SciTech Connect

    Tolikas, M.; Lang, J.H.; Kirtley, J.L. Jr.

    1995-12-31

    The dual-energy method has been successfully employed in the calculation of static resistances, capacitances and inductances, yielding fast and accurate solutions. Two different directions can be followed in applying the method, one is the more widely known method of tubes and slices, the other is the algebraic approach and is explored further in this paper. The present literature on the algebraic dual-energy method involves trivial examples with boundaries, boundary conditions and source distributions that are easily handled. However, the geometry of the variable reluctance motor at the unaligned position, the dominating curvatures characterizing its electromagnetic field distribution and the presence of a large number of boundary conditions arising at the steel boundaries, provide a challenging exercise in the application, behavior and effectiveness of the dual-energy method in a realistic framework.

  21. An analysis of noise reduction in variable reluctance motors using pulse position randomization

    NASA Astrophysics Data System (ADS)

    Smoot, Melissa C.

    1994-05-01

    The design and implementation of a control system to introduce randomization into the control of a variable reluctance motor (VRM) is presented. The goal is to reduce noise generated by radial vibrations of the stator. Motor phase commutation angles are dithered by 1 or 2 mechanical degrees to investigate the effect of randomization on acoustic noise. VRM commutation points are varied using a uniform probability density function and a 4 state Markov chain among other methods. The theory of VRM and inverter operation and a derivation of the major source of acoustic noise are developed. The experimental results show the effects of randomization. Uniform dithering and Markov chain dithering both tend to spread the noise spectrum, reducing peak noise components. No clear evidence is found to determine which is the optimum randomization scheme. The benefit of commutation angle randomization in reducing VRM loudness as perceived by humans is found to be questionable.

  22. Performance Evaluation of a Dual-Winding Reluctance Generator with a Multiple-Barrier Rotor

    NASA Astrophysics Data System (ADS)

    Yokoi, Masashi; Fukami, Tadashi; Shima, Kazuo; Hanaoka, Ryoichi; Takata, Shinzo

    This paper presents a novel type of dual-winding reluctance generator (DWRG) which uses a multiple-barrier (MB) rotor. The stator of the DWRG is equipped with an armature winding and a field winding. By changing the stator field current, the constant voltage control is easily achieved over a wide range of speeds. The structure and operating principle of the DWRG are described, and its performance is evaluated by the equivalent circuit approach, finite-element (FE) analysis, and experiments conducted on a prototype machine. Compared to a salient-pole (SP) rotor used in a conventional DWRG, the studied MB rotor provides good magnetic coupling between the two stator windings and was found to have great potential as a DWRG rotor.

  1. [Reluctant partner: Canada's relationship with the Pan American Health Organization (PAHO)].

    PubMed

    Dmitrienko, Klaudia

    2006-01-01

    Despite a strong commitment to multilateralism and international health cooperation in the post World War II era, Canada refrained form joining the Pan American Health Organization - PAHO until 1971. Drawing on letters and memos sent between Canadian diplomats and government representatives, this paper explores official Canadian accounts of the factors that delayed Canada's membership in PAHO. These factors include the initial lack of official relations between Canada and Latin America, US hegemony in the region, and budgetary constraints. Canada's cautious position regarding PAHO is also placed within the context of Canada's overall foreign policy to the region, emphasizing the parallels between Canada's reluctant association with PAHO and the evolution of Canada's engagement with the region as a whole.

  2. Identification of reluctant factors in using footpaths based on the pedestrians' perception

    NASA Astrophysics Data System (ADS)

    Hadiyanto, Wahyu; Handayani, Dewi; Yulianto, Budi

    2017-06-01

    Footpath is a path intended particularly for pedestrians to avoid any conflicts with motor vehicles. However in reality, most of the pedestrians are unwilling to use paths and they prefer to walk on the roads. This research was conducted with the aim to identify the existing condition of pedestrian footpaths based on field observations and to determine the factors that cause the pedestrians are reluctant to walk on the trails. The method used to investigate the pedestrians' perception was by distributing questionnaires to the pedestrians. The results of this study found that the factors that caused the pedestrians did not want to use footpaths were the footpath width, the existence of barriers and obstacles, unstable height (not continuous), damaged surface, non-standard driveway that intersects sidewalk, suboptimal function of ramp, transverse steep slope, and the absence of bollard that could protect footpaths from the access of motorcycles.

  3. Sexual conflict in Sepsis cynipsea: female reluctance, fertility and mate choice.

    PubMed

    Hosken, D J; Martin, O Y; Born, J; Huber, F

    2003-05-01

    Sexual conflict can elevate mating costs via male inflicted damage to females. Possible selective advantages to males include decreasing the likelihood that females remate and/or increasing females' current reproductive investment in a manner analogous to terminal reproductive investment. We investigated female mating behaviour relative to their number of previous copulations in the fly Sepsis cynipsea, and whether males accepted as first mates were more likely to be accepted again. Females were more likely to remate with new rather than original males, although there was no associated fitness benefit, and in contrast to theoretical predictions, females became less reluctant to remate as the number of previous copulations increased. Additionally, females did not increase reproductive investment as would be expected if they were ensuring their final reproductive efforts were maximized by remating. This suggests that damaging females is a pleiotropic effect which inadvertently leads to increased, not decreased, polyandry.

  4. The nurse educator as teacher: exploring the construction of the 'reluctant instructor'.

    PubMed

    Bruni, N

    1997-03-01

    This paper explores the discursive construction of the category of teacher identified as the 'reluctant instructor'. Data are drawn from my doctoral study, an ethnography of a school of nursing located in the higher education sector in which I was employed. This study explored the question: What shapes nurse educators and what do they, in turn, shape? Participants included nurse educators who taught a pre-registration programme. Data were gathered through interview and observations of classroom teaching. Analysis focused on the discursive constitution of participants' sense of being a nurse educator and on the implications of their ways of 'knowing and doing' for students. The analysis suggests that the dominant subject positions adopted by participants were those of 'academic' and 'victim'. They employed an ideal/real dichotomy to give a sense of coherence to the inconsistencies or contradications that they saw as structuring their daily activities. Being an academic entailed being an educator, specifically a facilitator, as being competent and having some degree of autonomy. However, participants saw the reality of their situation as markedly different from their ideal; as exhibiting traits of the 'outmoded', oppressive, hospital system of nurse training. Within this context most participants positioned themselves as a 'reluctant instructor'. The implications of their practices for the creation of the 'passive student' are suggested in the paper. In this analysis the nurse educator is viewed as implicated in the formation and maintenance of the context in which she or he is located. Such a view challenges the neutrality that is implicated in understandings of the nurse educator that inform nursing texts and that helped constitute participants' sense of self.

  5. Selection for reluctance to avoid humans during the domestication of mice.

    PubMed

    Goto, T; Tanave, A; Moriwaki, K; Shiroishi, T; Koide, T

    2013-11-01

    Many animal species have been domesticated over the course of human history and became tame as a result of domestication. Tameness is a behavioral characteristic with 2 potential components: (1) reluctance to avoid humans and (2) motivation to approach humans. However, the specific behavioral characteristics selected during domestication processes remain to be clarified for many species. To quantify these 2 different components of tameness separately, we established 3 behavioral tests: the 'active tame', 'passive tame' and 'stay-on-hand' tests. We subjected genetically diverse mouse strains to these tests, including 10 wild strains (BFM/2Ms, PGN2/Ms, HMI/Ms, BLG2/Ms, NJL/Ms, KJR/Ms, SWN/Ms, CHD/Ms, MSM/Ms and CAST/Ei), a fancy strain (JF1/Ms) and 6 standard laboratory strains (C3H/HeNJcl, CBA/J, BALB/cAnNCrlCrlj, DBA/2JJcl, 129(+Ter) /SvJcl and C57BL/6JJcl). To analyze the effects of domestication, these 17 strains were divided into 2 groups: domesticated strains (fancy and laboratory strains) and wild strains. Significant differences between strains were observed in all traits, and the calculated estimates of broad-sense heritability were 0.15-0.72. These results illustrate that tameness in mice is significantly influenced by genetic background. In addition, they clearly show the differences in the features of tameness in domesticated and wild strains. Most of the domesticated strains showed significantly greater reluctance to avoid humans than wild strains, whereas there was no significant difference in the level of motivation to approach humans between these 2 groups. These results might help to clarify the genetic basis of tameness in mice. © 2013 The Authors. Genes, Brain and Behavior published by International Behavioural and Neural Genetics Society and John Wiley & Sons Ltd.

  6. Monolithic Microwave Switching Matrix

    NASA Technical Reports Server (NTRS)

    Fujikawa, Gene; Ch'en, Daniel R.; Petersen, Wendell C.

    1989-01-01

    Gallium arsenide integrated-circuit chip switches any of three microwave input signals to any of three output ports. Measuring 4.9 mm on side, chip contains nine field-effect transistor (FET) crosspoint switches. Housed in custom-designed package with standard connectors for easy integration into system. FET's on chip operated as passive switches and consume no static power and insignificant amounts of switching power. Chip module cascades with similar modules into large arrays handling as many as 100 inputs and 100 outputs. Applications include switching and routing vast amounts of data between computers at extremely high speed. On communications satellite, chip switches microwave signals to and from Earth stations and other satellites.

  7. Effective switching frequency multiplier inverter

    DOEpatents

    Su, Gui-Jia; Peng, Fang Z.

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  8. Using the Learning Sciences and Knowledge about How People Learn to Support Reluctant and Disengaged Secondary School Learners

    ERIC Educational Resources Information Center

    Turner, Steven L.

    2008-01-01

    As secondary educators seek strategies to support reluctant and disengaged learners, a greater understanding of the learning sciences (how people learn) becomes more important. This article examines the emerging knowledge base on the learning sciences and investigates how what has been discoveries about how and why people learn have practical…

  9. Apparatus for efficient sidewall containment of molten metal with horizontal alternating magnetic fields utilizing low reluctance rims

    DOEpatents

    Praeg, Walter F.

    1999-01-01

    A method and apparatus for casting sheets of metal from molten metal. The apparatus includes a containment structure having an open side, a horizontal alternating magnetic field generating structure and rollers including low reluctance rim structures. The magnetic field and the rollers help contain the molten metal from leaking out of the containment structure.

  10. "There Is No Space for Being German": Portraits of Willing and Reluctant Heritage Language Learners of German

    ERIC Educational Resources Information Center

    Dressler, Roswita

    2010-01-01

    Some heritage language learners (HLLs) are comfortable identifying themselves as such, while others are decidedly reluctant to adopt this term (Pino & Pino, 2000). HLLs in this paper are defined as those students having a parent or grandparent who speaks German or those who have spent a significant part of their childhood in a German-speaking…

  11. "There Is No Space for Being German": Portraits of Willing and Reluctant Heritage Language Learners of German

    ERIC Educational Resources Information Center

    Dressler, Roswita

    2010-01-01

    Some heritage language learners (HLLs) are comfortable identifying themselves as such, while others are decidedly reluctant to adopt this term (Pino & Pino, 2000). HLLs in this paper are defined as those students having a parent or grandparent who speaks German or those who have spent a significant part of their childhood in a German-speaking…

  12. Double-Bounce Switching

    DTIC Science & Technology

    1983-06-01

    module. Adjustments provided to investigate double- bounce switching are noted. limitation is at a higher level and occurs in the conventionally...To be presented at the 4th IEEE PUlsed Power Conference, June 6-8, 1983, Albuquerque, NM. DOUBLE- BOUNCE SWITCHING* George B. Frazier and Steven R...Ashby Physics International Company 2700 Merced Street San Leandro, California 94577 Abstract Double- bounce switching is a technique for

  13. Avalanche Photoconductive Switching

    DTIC Science & Technology

    1989-06-01

    held off across the switch. In our case this corresponds to 70 kV/cm and is limited by surface flashover . The pulse length is determined by the...off across the gap of the switch, which in turn appears to be limited by surface flashover . There appears to be a threshold electric field of 20-60...and understand this mode of operation. Introduction Laser activated photoconductive switching in semiconductors is a promising technology for high

  14. Thermally actuated thermionic switch

    DOEpatents

    Barrus, Donald M.; Shires, Charles D.

    1988-01-01

    A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

  15. Thermally actuated thermionic switch

    DOEpatents

    Barrus, D.M.; Shires, C.D.

    1982-09-30

    A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

  16. Solid state switch

    DOEpatents

    Merritt, Bernard T.; Dreifuerst, Gary R.

    1994-01-01

    A solid state switch, with reverse conducting thyristors, is designed to operate at 20 kV hold-off voltage, 1500 A peak, 1.0 .mu.s pulsewidth, and 4500 pps, to replace thyratrons. The solid state switch is more reliable, more economical, and more easily repaired. The switch includes a stack of circuit card assemblies, a magnetic assist and a trigger chassis. Each circuit card assembly contains a reverse conducting thyristor, a resistor capacitor network, and triggering circuitry.

  17. AC magnetohydrodynamic microfluidic switch

    SciTech Connect

    Lemoff, A V; Lee, A P

    2000-03-02

    A microfluidic switch has been demonstrated using an AC Magnetohydrodynamic (MHD) pumping mechanism in which the Lorentz force is used to pump an electrolytic solution. By integrating two AC MHD pumps into different arms of a Y-shaped fluidic circuit, flow can be switched between the two arms. This type of switch can be used to produce complex fluidic routing, which may have multiple applications in {micro}TAS.

  18. Alarm toe switch

    DOEpatents

    Ganyard, Floyd P.

    1982-01-01

    An alarm toe switch inserted within a shoe for energizing an alarm circuit n a covert manner includes an insole mounting pad into which a miniature reed switch is fixedly molded. An elongated slot perpendicular to the reed switch is formed in the bottom surface of the mounting pad. A permanent cylindrical magnet positioned in the forward portion of the slot with a diameter greater than the pad thickness causes a bump above the pad. A foam rubber block is also positioned in the slot rearwardly of the magnet and holds the magnet in normal inoperative relation. A non-magnetic support plate covers the slot and holds the magnet and foam rubber in the slot. The plate minimizes bending and frictional forces to improve movement of the magnet for reliable switch activation. The bump occupies the knuckle space beneath the big toe. When the big toe is scrunched rearwardly the magnet is moved within the slot relative to the reed switch, thus magnetically activating the switch. When toe pressure is released the foam rubber block forces the magnet back into normal inoperative position to deactivate the reed switch. The reed switch is hermetically sealed with the magnet acting through the wall so the switch assembly S is capable of reliable operation even in wet and corrosive environments.

  19. Reusable fast opening switch

    DOEpatents

    Van Devender, J.P.; Emin, D.

    1983-12-21

    A reusable fast opening switch for transferring energy, in the form of a high power pulse, from an electromagnetic storage device such as an inductor into a load. The switch is efficient, compact, fast and reusable. The switch comprises a ferromagnetic semiconductor which undergoes a fast transition between conductive and metallic states at a critical temperature and which undergoes the transition without a phase change in its crystal structure. A semiconductor such as europium rich europhous oxide, which undergoes a conductor to insulator transition when it is joule heated from its conductor state, can be used to form the switch.

  20. Reusable fast opening switch

    DOEpatents

    Van Devender, John P.; Emin, David

    1986-01-01

    A reusable fast opening switch for transferring energy, in the form of a high power pulse, from an electromagnetic storage device such as an inductor into a load. The switch is efficient, compact, fast and reusable. The switch comprises a ferromagnetic semiconductor which undergoes a fast transition between conductive and insulating states at a critical temperature and which undergoes the transition without a phase change in its crystal structure. A semiconductor such as europium rich europhous oxide, which undergoes a conductor to insulator transition when it is joule heated from its conductor state, can be used to form the switch.

  1. Platform switching and bone platform switching.

    PubMed

    Carinci, Francesco; Brunelli, Giorgio; Danza, Matteo

    2009-01-01

    Bone platform switching involves an inward bone ring in the coronal part of the implant that is in continuity with the alveolar bone crest. Bone platform switching is obtained by using a dental fixture with a reverse conical neck. A retrospective study was performed to evaluate the effectiveness of conventional vs reverse conical neck implants. In the period between May 2004 and November 2007, 86 patients (55 females and 31 males; median age, 53 years) were operated and 234 implants were inserted: 40 and 194 were conventional vs reverse conical neck implants, respectively. Kaplan-Meier algorithm and Cox regression were used to detect those variables associated with the clinical outcome. No differences in survival and success rates were detected between conventional vs reverse conical neck implants alone or in combination with any of the studied variables. Although bone platform switching leads to several advantages, no statistical difference in alveolar crest resorption is detected in comparison with reverse conical neck implants. We suppose that the proximity of the implant abutment junction to the alveolar crestal bone gives no protection against the microflora contained in the micrograph. Additional studies on larger series and a combination of platform switching and bone platform switching could lead to improved clinical outcomes.

  2. Development, Integration and Testing of Automated Triggering Circuit for Hybrid DC Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Kanabar, Deven; Roy, Swati; Dodiya, Chiragkumar; Pradhan, Subrata

    2017-04-01

    A novel concept of Hybrid DC circuit breaker having combination of mechanical switch and static switch provides arc-less current commutation into the dump resistor during quench in superconducting magnet operation. The triggering of mechanical and static switches in Hybrid DC breaker can be automatized which can effectively reduce the overall current commutation time of hybrid DC circuit breaker and make the operation independent of opening time of mechanical switch. With this view, a dedicated control circuit (auto-triggering circuit) has been developed which can decide the timing and pulse duration for mechanical switch as well as static switch from the operating parameters. This circuit has been tested with dummy parameters and thereafter integrated with the actual test set up of hybrid DC circuit breaker. This paper deals with the conceptual design of the auto-triggering circuit, its control logic and operation. The test results of Hybrid DC circuit breaker using this circuit have also been discussed.

  3. Asymmetrical Switch Costs in Children

    ERIC Educational Resources Information Center

    Ellefson, Michelle R.; Shapiron, Laura R.; Chater, Nick

    2006-01-01

    Switching between tasks produces decreases in performance as compared to repeating the same task. Asymmetrical switch costs occur when switching between two tasks of unequal difficulty. This asymmetry occurs because the cost is greater when switching to the less difficult task than when switching to the more difficult task. Various theories about…

  4. Quantum cryptography without switching.

    PubMed

    Weedbrook, Christian; Lance, Andrew M; Bowen, Warwick P; Symul, Thomas; Ralph, Timothy C; Lam, Ping Koy

    2004-10-22

    We propose a new coherent state quantum key distribution protocol that eliminates the need to randomly switch between measurement bases. This protocol provides significantly higher secret key rates with increased bandwidths than previous schemes that only make single quadrature measurements. It also offers the further advantage of simplicity compared to all previous protocols which, to date, have relied on switching.

  5. Power-Switching Circuit

    NASA Technical Reports Server (NTRS)

    Praver, Gerald A.; Theisinger, Peter C.; Genofsky, John

    1987-01-01

    Functions of circuit breakers, meters, and switches combined. Circuit that includes power field-effect transistors (PFET's) provides on/off switching, soft starting, current monitoring, current tripping, and protection against overcurrent for 30-Vdc power supply at normal load currents up to 2 A. Has no moving parts.

  6. Reflective HTS switch

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Hohenwarter, G.K.G.

    1994-09-27

    A HTS (High Temperature Superconductor) switch includes a HTS conductor for providing a superconducting path for an electrical signal and an serpentine wire actuator for controllably heating a portion of the conductor sufficiently to cause that portion to have normal, and not superconducting, resistivity. Mass of the portion is reduced to decrease switching time. 6 figs.

  7. Reflective HTS switch

    SciTech Connect

    Martens, Jon S.; Hietala, Vincent M.; Hohenwarter, Gert K. G.

    1994-01-01

    A HTS switch includes a HTS conductor for providing a superconducting path for an electrical signal and an serpentine wire actuator for controllably heating a portion of the conductor sufficiently to cause that portion to have normal, and not superconducting, resistivity. Mass of the portion is reduced to decrease switching time.

  8. Manually operated coded switch

    DOEpatents

    Barnette, Jon H.

    1978-01-01

    The disclosure relates to a manually operated recodable coded switch in which a code may be inserted, tried and used to actuate a lever controlling an external device. After attempting a code, the switch's code wheels must be returned to their zero positions before another try is made.

  9. A Novel Molecular Switch

    PubMed Central

    Daber, Robert; Lewis, Mitchell

    2009-01-01

    Transcriptional regulation is a fundamental process for regulating the flux of all metabolic pathways. For the last several decades, the lac operon has served as a valuable model for studying transcription. More recently, the switch that controls the operon has also been successfully adapted to function in mammalian cells. Here we describe how, using directed evolution, we have created a novel switch that recognizes an asymmetric operator sequence. The new switch has a repressor with altered headpiece domains for operator recognition, and a redesigned dimer interface to create a heterodimeric repressor. Quite unexpectedly, the heterodimeric switch functions better than the natural system. It can repress more tightly than the naturally occurring switch of the lac operon; it is less leaky and can be induced more efficiently. Ultimately these novel repressors could be evolved to recognize eukaryotic promoters and used to regulate gene expression in mammalian systems. PMID:19540845

  10. Erected mirror optical switch

    DOEpatents

    Allen, James J.

    2005-06-07

    A microelectromechanical (MEM) optical switching apparatus is disclosed that is based on an erectable mirror which is formed on a rotatable stage using surface micromachining. An electrostatic actuator is also formed on the substrate to rotate the stage and mirror with a high angular precision. The mirror can be erected manually after fabrication of the device and used to redirect an incident light beam at an arbitrary angel and to maintain this state in the absence of any applied electrical power. A 1.times.N optical switch can be formed using a single rotatable mirror. In some embodiments of the present invention, a plurality of rotatable mirrors can be configured so that the stages and mirrors rotate in unison when driven by a single micromotor thereby forming a 2.times.2 optical switch which can be used to switch a pair of incident light beams, or as a building block to form a higher-order optical switch.

  11. Temperature-Triggered Dielectric-Optical Duple Switch Based on an Organic-Inorganic Hybrid Phase Transition Crystal: [C5N2H16]2SbBr5.

    PubMed

    Mao, Chen-Yu; Liao, Wei-Qiang; Wang, Zhong-Xia; Zafar, Zainab; Li, Peng-Fei; Lv, Xing-Hui; Fu, Da-Wei

    2016-08-01

    Molecular optical-electrical duple switches (switch "ON" and "OFF" bistable states) represent a class of highly desirable intelligent materials because of their sensitive switchable physical and/or chemical responses, simple and environmentally friendly processing, light weights, and mechanical flexibility. In the current work, the phase transition of 1 (general formula R2MX5, [C5N2H16]2[SbBr5]) can be triggered by the order-disorder transition of the organic cations at 278.3 K. The temperature-induced phase transition causes novel bistable optical-electrical duple characteristics, which indicates that 1 might be an excellent candidate for a potential switchable optical-electrical (fluorescence/dielectric) material. In the dielectric measurements, remarkable bistable dielectric responses were detected, accompanied by striking anisotropy along various crystallographic axes. For the intriguing fluorescence emission spectra, the intensity and position changed significantly with the occurrence of the structural phase transition. We believe that these findings might further promote the application of halogenoantimonates(III) and halogenobismuthates(III) in the field of optoelectronic multifunctional devices.

  12. Mouse manipulation through single-switch scanning.

    PubMed

    Blackstien-Adler, Susie; Shein, Fraser; Quintal, Janet; Birch, Shae; Weiss, Patrice L Tamar

    2004-01-01

    Given the current extensive reliance on the graphical user interface, independent access to computer software requires that users be able to manipulate a pointing device of some type (e.g., mouse, trackball) or be able to emulate a mouse by some other means (e.g., scanning). The purpose of the present study was to identify one or more optimal single-switch scanning mouse emulation strategies. Four alternative scanning strategies (continuous Cartesian, discrete Cartesian, rotational, and hybrid quadrant/continuous Cartesian) were selected for testing based on current market availability as well as on theoretical considerations of their potential speed and accuracy. Each strategy was evaluated using a repeated measures study design by means of a test program that permitted mouse emulation via any one of four scanning strategies in a motivating environment; response speed and accuracy could be automatically recorded and considered in view of the motor, cognitive, and perceptual demands of each scanning strategy. Ten individuals whose disabilities required them to operate a computer via single-switch scanning participated in the study. Results indicated that Cartesian scanning was the preferred and most effective scanning strategy. There were no significant differences between results from the Continuous Cartesian and Discrete Cartesian scanning strategies. Rotational scanning was quite slow with respect to the other strategies, although it was equally accurate. Hybrid Quadrant scanning improved access time but at the cost of fewer correct selections. These results demonstrated the importance of testing and comparing alternate single-switch scanning strategies.

  13. Optical packet switching

    NASA Astrophysics Data System (ADS)

    Shekel, Eyal; Ruschin, Shlomo; Majer, Daniel; Levy, Jeff; Matmon, Guy; Koenigsberg, Lisa; Vecht, Jacob; Geron, Amir; Harlavan, Rotem; Shfaram, Harel; Arbel, Arnon; McDermott, Tom; Brewer, Tony

    2005-02-01

    We report here a scalable, multichassis, 6.3 terabit core router, which utilizes our proprietary optical switch. The router is commercially available and deployed in several customer sites. Our solution combines optical switching with electronic routing. An internal optical packet switching network interconnects the router"s electronic line cards, where routing and buffering functions take place electronically. The system architecture and performance will be described. The optical switch is based on Optical Phased Array (OPA) technology. It is a 64 x 64, fully non-blocking, optical crossbar switch, capable of switching in a fraction of a nanosecond. The basic principles of operation will be explained. Loss and crosstalk results will be presented, as well as the results of BER measurements of a 160 Gbps transmission through one channel. Basic principles of operation and measured results will be presented for the burst-mode-receivers, arbitration algorithm and synchronization. Finally, we will present some of our current research work on a next-generation optical switch. The technological issues we have solved in our internal optical packet network can have broad applicability to any global optical packet network.

  14. Optical Circuit Switched Protocol

    NASA Technical Reports Server (NTRS)

    Monacos, Steve P. (Inventor)

    2000-01-01

    The present invention is a system and method embodied in an optical circuit switched protocol for the transmission of data through a network. The optical circuit switched protocol is an all-optical circuit switched network and includes novel optical switching nodes for transmitting optical data packets within a network. Each optical switching node comprises a detector for receiving the header, header detection logic for translating the header into routing information and eliminating the header, and a controller for receiving the routing information and configuring an all optical path within the node. The all optical path located within the node is solely an optical path without having electronic storage of the data and without having optical delay of the data. Since electronic storage of the header is not necessary and the initial header is eliminated by the first detector of the first switching node. multiple identical headers are sent throughout the network so that subsequent switching nodes can receive and read the header for setting up an optical data path.

  15. Age Differences in Strategy Shift: Retrieval Avoidance or General Shift Reluctance?

    PubMed Central

    Frank, David J.; Touron, Dayna R.; Hertzog, Christopher

    2013-01-01

    Previous studies of metacognitive age differences in skill acquisition strategies have relied exclusively on tasks with a processing shift from an algorithm to retrieval strategy. Older adults’ demonstrated reluctance to shift strategies in such tasks could reflect either a specific aversion to a memory retrieval strategy or a general, inertial resistance to strategy change. Haider and Frensch’s (1999) alphabet verification task (AVT) affords a non-retrieval-based strategy shift. Participants verify the continuation of alphabet strings such as D E F G [4] L, with the bracketed digit indicating a number of letters to be skipped. When all deviations are restricted to the letter-digit-letter portion, participants can speed their responses by selectively attend only to that part of the stimulus. We adapted the AVT to include conditions which promoted shift to a retrieval strategy, a selective attention strategy, or both strategies. Item-level strategy reports were validated by eye movement data. Older adults shifted more slowly to the retrieval strategy but more quickly to the selective attention strategy than young adults, indicating a retrieval-strategy avoidance. Strategy confidence and perceived strategy difficulty correlated with shift to the two strategies in both age groups. Perceived speed of responses with each strategy specifically correlated with older adults’ strategy choices, suggesting that some older adults avoid retrieval because they do not appreciate its efficiency benefits. PMID:23088195

  16. Addressing Risk and Reluctance at the Nexus of HIV and Anal Cancer Screening

    PubMed Central

    Ka‘opua, Lana Sue I.; Cassel, Kevin; Shiramizu, Bruce; Stotzer, Rebecca L.; Robles, Andrew; Kapua, Cathy; Orton, Malulani; Milne, Cris; Sesepasara, Maddalynn

    2015-01-01

    Anal cancer disproportionately burdens persons living with human immunodeficiency virus (PLHIV) regardless of natal sex, sexual orientation, gender expression, and ethnic identity. Culturally competent communications are recommended to address health disparities, with sociocultural relevance ensured through constituent dialogic processes. Results are presented from six provider focus groups conducted to inform the promotion/education component of a Hawai‘i-based project on anal cancer screening tools. Krueger’s focus group methodology guided discussion queries. Verbatim transcripts of digitally recorded discussions were analyzed using grounded theory and PEN-3 procedures. Adherence to an audit trail ensured analytic rigor. Grounded theory analysis detected the overall theme of risk and reluctance to anal cancer screening, characterized by anal cancer not being “on the radar” of PLHIV, conflicting attributions of the anus and anal sex, fear of sex-shaming/-blaming, and other interrelated conceptual categories. PEN-3 analysis revealed strategies for destigmatizing anal cancer, through “real talk” (proactive, candid, nonjudgmental discussion) nested in a framework of sexual health and overall well-being, with additional tailoring for relevance to Native Hawaiians/Pacific Islanders, transgender persons, and other marginalized groups. Application of strategies for health practice are specific to the Hawai‘i context, yet may offer considerations for developing strengths-based, culturally relevant screening promotion/education with diverse PLHIV in other locales. PMID:26630979

  17. Age differences in strategy shift: retrieval avoidance or general shift reluctance?

    PubMed

    Frank, David J; Touron, Dayna R; Hertzog, Christopher

    2013-09-01

    Previous studies of metacognitive age differences in skill acquisition strategies have relied exclusively on tasks with a processing shift from an algorithm to retrieval strategy. Older adults' demonstrated reluctance to shift strategies in such tasks could reflect either a specific aversion to a memory retrieval strategy or a general, inertial resistance to strategy change. Haider and Frensch's (1999) alphabet verification task (AVT) affords a non-retrieval-based strategy shift. Participants verify the continuation of alphabet strings such as D E F G [4] L, with the bracketed digit indicating a number of letters to be skipped. When all deviations are restricted to the letter-digit-letter portion, participants can speed their responses by selectively attending to only that part of the stimulus. We adapted the AVT to include conditions that promoted shift to a retrieval strategy, a selective attention strategy, or both strategies. Item-level strategy reports were validated by eye movement data. Older adults shifted more slowly to the retrieval strategy but more quickly to the selective attention strategy than young adults, indicating a retrieval-strategy avoidance. Strategy confidence and perceived strategy difficulty correlated with shift to the two strategies in both age groups. Perceived speed of responses with each strategy specifically correlated with older adults' strategy choices, suggesting that some older adults avoid retrieval because they do not appreciate its efficiency benefits.

  18. From Persuasion to Coercion: Responding to the Reluctant Patient in Rehabilitation.

    PubMed

    Anderson, Lynley; Delany, Clare

    2016-08-01

    Early mobilization of patients while in hospital has been demonstrated to provide better outcomes for patients and use fewer resources. Physical therapy-based rehabilitation is central to achieving those goals. Successful rehabilitation requires that patient's and therapist's goals align, and this is commonly the case. However, occasionally, physical therapists will come across patients who are competent but reluctant to mobilize. This situation leaves the physical therapist in an ethical quandary: either accept the patient's right to refuse proposed treatment or utilize other strategies to encourage the patient to adhere to treatment. Practically, physical therapists will use a range of treatment pressures, including persuasion, offering incentives, inducements, possibly threatening or coercing, and even explicitly overriding the patient's wishes (compulsion). Deciding which treatment pressure is ethically acceptable involves the physical therapist balancing his or her therapeutic view of what is in a patient's best interests against the therapist's ethical responsibility to respect patient autonomy. This article evaluates some common strategies used by physical therapists to influence, persuade, or perhaps pressure patients to adhere to rehabilitation. The work of Szmukler and Appelbaum is utilized in analyzing treatment pressures. The authors conclude that there is a spectrum of treatment pressures, with some (persuasion and incentives) being more acceptable than others (threats and compulsion). As physical therapists balance health system pressures for rapid turnover of beds with obligations to benefit patients within limited reimbursement models, while respecting the patients' autonomy, they must be mindful of the effects of treatment pressure on patient care. © 2016 American Physical Therapy Association.

  19. Addressing Risk and Reluctance at the Nexus of HIV and Anal Cancer Screening.

    PubMed

    Ka'opua, Lana Sue I; Cassel, Kevin; Shiramizu, Bruce; Stotzer, Rebecca L; Robles, Andrew; Kapua, Cathy; Orton, Malulani; Milne, Cris; Sesepasara, Maddalynn

    2016-01-01

    Anal cancer disproportionately burdens persons living with human immunodeficiency virus (PLHIV) regardless of natal sex, sexual orientation, gender expression, and ethnic identity. Culturally competent communications are recommended to address health disparities, with sociocultural relevance ensured through constituent dialogic processes. Results are presented from six provider focus groups conducted to inform the promotion/education component of a Hawai'i-based project on anal cancer screening tools. Krueger's focus group methodology guided discussion queries. Verbatim transcripts of digitally recorded discussions were analyzed using grounded theory and PEN-3 procedures. Adherence to an audit trail ensured analytic rigor. Grounded theory analysis detected the overall theme of risk and reluctance to anal cancer screening, characterized by anal cancer not being "on the radar" of PLHIV, conflicting attributions of the anus and anal sex, fear of sex-shaming/-blaming, and other interrelated conceptual categories. PEN-3 analysis revealed strategies for destigmatizing anal cancer, through "real talk" (proactive, candid, nonjudgmental discussion) nested in a framework of sexual health and overall well-being, with additional tailoring for relevance to Native Hawaiians/Pacific Islanders, transgender persons, and other marginalized groups. Application of strategies for health practice are specific to the Hawai'i context, yet may offer considerations for developing strengths-based, culturally relevant screening promotion/education with diverse PLHIV in other locales.

  20. Permanent Magnet Machine And Method With Reluctance Poles For High Strength Undiffused Brushless Operation.

    DOEpatents

    Hsu, John S [Oak Ridge, TN

    2005-12-06

    A method and apparatus in which a rotor (11) and a stator (17) define a radial air gap (20) for receiving AC flux and at least one, and preferably two, DC excitation assemblies (23, 24) are positioned at opposite ends of the rotor (20) to define secondary air gaps (21, 22). Portions of PM material (14a, 14b) are provided as boundaries separating the rotor pole portions (12a, 12b) of opposite polarity from other portions of the rotor (11) and from each other to define PM poles (12a, 12b) for conveying the DC flux to or from the primary air gap (20) and for inhibiting flux from leaking from the pole portions prior to reaching the primary air gap (20). The portions of PM material (14a, 14b) are spaced from each other so as to include reluctance poles (15) of ferromagnetic material between the PM poles (12a, 12b) to interact with the AC flux in the primary-air gap (20).

  1. Electromechanical magnetization switching

    SciTech Connect

    Chudnovsky, Eugene M.; Jaafar, Reem

    2015-03-14

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

  2. Sleep State Switching

    PubMed Central

    Saper, Clifford B.; Fuller, Patrick M.; Pedersen, Nigel P.; Lu, Jun; Scammell, Thomas E.

    2010-01-01

    We take for granted the ability to fall asleep or to snap out of sleep into wakefulness, but these changes in behavioral state require specific switching mechanisms in the brain that allow well-defined state transitions. In this review, we examine the basic circuitry underlying the regulation of sleep and wakefulness, and discuss a theoretical framework wherein the interactions between reciprocal neuronal circuits enable relatively rapid and complete state transitions. We also review how homeostatic, circadian, and allostatic drives help regulate sleep state switching, and discuss how breakdown of the switching mechanism may contribute to sleep disorders such as narcolepsy. PMID:21172606

  3. Photoconductive switch package

    DOEpatents

    Ca[rasp, George J

    2013-10-22

    A photoconductive switch is formed of a substrate that has a central portion of SiC or other photoconductive material and an outer portion of cvd-diamond or other suitable material surrounding the central portion. Conducting electrodes are formed on opposed sides of the substrate, with the electrodes extending beyond the central portion and the edges of the electrodes lying over the outer portion. Thus any high electric fields produced at the edges of the electrodes lie outside of and do not affect the central portion, which is the active switching element. Light is transmitted through the outer portion to the central portion to actuate the switch.

  4. SPARK GAP SWITCH

    DOEpatents

    Neal, R.B.

    1957-12-17

    An improved triggered spark gap switch is described, capable of precisely controllable firing time while switching very large amounts of power. The invention in general comprises three electrodes adjustably spaced and adapted to have a large potential impressed between the outer electrodes. The central electrode includes two separate elements electrically connected togetaer and spaced apart to define a pair of spark gaps between the end electrodes. Means are provided to cause the gas flow in the switch to pass towards the central electrode, through a passage in each separate element, and out an exit disposed between the two separate central electrode elements in order to withdraw ions from the spark gap.

  5. Photoconductive switch package

    DOEpatents

    Caporaso, George J.

    2015-10-27

    A photoconductive switch is formed of a substrate that has a central portion of SiC or other photoconductive material and an outer portion of cvd-diamond or other suitable material surrounding the central portion. Conducting electrodes are formed on opposed sides of the substrate, with the electrodes extending beyond the central portion and the edges of the electrodes lying over the outer portion. Thus any high electric fields produced at the edges of the electrodes lie outside of and do not affect the central portion, which is the active switching element. Light is transmitted through the outer portion to the central portion to actuate the switch.

  6. Solid state switch

    DOEpatents

    Merritt, B.T.; Dreifuerst, G.R.

    1994-07-19

    A solid state switch, with reverse conducting thyristors, is designed to operate at 20 kV hold-off voltage, 1,500 A peak, 1.0 [mu]s pulsewidth, and 4,500 pps, to replace thyratrons. The solid state switch is more reliable, more economical, and more easily repaired. The switch includes a stack of circuit card assemblies, a magnetic assist and a trigger chassis. Each circuit card assembly contains a reverse conducting thyristor, a resistor capacitor network, and triggering circuitry. 6 figs.

  7. Si:Bi switched photoconducttor infrared detector array

    NASA Technical Reports Server (NTRS)

    Eakin, C. E.

    1983-01-01

    A multiplexed infrared detector array is described. The small demonstration prototype consisted of two cryogenically cooled, bismuth doped silicon, extrinsic photoconductor pixels multiplexed onto a single output channel using an on focal plane switch integration sampling technique. Noise levels of the order of 400 to 600 rms electrons per sample were demonstrated for this chip and wire hybrid version.

  8. A new FET-bipolar combinational power semiconductor switch

    NASA Technical Reports Server (NTRS)

    Chen, D. Y.; Chandrasekaran, S.; Chin, S. A.

    1984-01-01

    A novel FET-BJT combinational transistor configuration is proposed and demonstrated using discrete devices. This new transistor features fast switching, very simple drive requirement, elimination of reverse bias second breakdown, and good utilization of semiconductor chip area. Initial results indicate that power hybrid construction of the device is essential to enhance the current rating of the device.

  9. Effects of anisotropy on the performance characteristics of an axially laminated anisotropic-rotor synchronous reluctance motor drive system

    SciTech Connect

    Isaac, F.N.; Arkadan, A.A.; Russell, A.A.; El-Antably, A.

    1998-09-01

    In the last few years, increased attention has been paid to the performance characterization and evaluation of the performance of synchronous reluctance machines. Extensive research has concentrated on different rotor structures in order to achieve high performance variable speed drives for applications such as electric vehicles. The effects of accounting for anisotropy on the performance characteristics of Axially Laminated Anisotropic (ALA) rotor Synchronous Reluctance Motor (SynRM) drive systems are studied. These effects are evaluated from the simulations of a computer aided model. The model is based on the use of an iterative approach which indirectly couples a two dimensional (2D) nonlinear finite element (FE) model, which accounts for anisotropy, to a state space model describing the SynRM drive system. The simulation results are also validated by comparison to test data of a prototype ALA rotor SynRM drive system.

  10. Hybrid power semiconductor

    NASA Technical Reports Server (NTRS)

    Chen, D. Y.

    1985-01-01

    The voltage rating of a bipolar transistor may be greatly extended while at the same time reducing its switching time by operating it in conjunction with FETs in a hybrid circuit. One FET is used to drive the bipolar transistor while the other FET is connected in series with the transistor and an inductive load. Both FETs are turned on or off by a single drive signal of load power, the second FET upon ceasing conductions, rendering one power electrode of the bipolar transistor open. Means are provided to dissipate currents which flow after the bipolar transistor is rendered nonconducting.

  11. Isolated and soft-switched power converter

    DOEpatents

    Peng, Fang Zheng; Adams, Donald Joe

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  12. a Nonlinear Hybrid and VR Stepping Motor Analysis via AN Integrated Finite Element and Lumped Parameter Modeling Technique

    NASA Astrophysics Data System (ADS)

    Huard, Steven Roger

    The work involves the magnetic modeling of a variable reluctance and a hybrid stepping motor. The model combines two traditional methods for creating a magnetic model. Nonlinear two dimensional finite element analysis is combined with nonlinear lumped element modeling to create a three dimension lumped model. The two dimensional finite element analysis is used to numerically calculate the effective reluctance function of the motor tooth region. After the finite element analysis is completed, a two terminal tooth region reluctance element that is a function of both rotor angle and tooth region flux density results. The two terminal lumped element is then used to represent the tooth region of the motor in a lumped parameter model. The process by which the tooth region finite element field solution is transformed into the two terminal lumped reluctance is a new modeling approach; and, it is the foundation of the modeling method in this dissertation. Torque, back EMF, and inductance are some of the more important motor parameters predicted by the modeling method. The model predictions are compared to experimental data in the dissertation. The final motor parameter predictions from the model correlated quite well with experimental data. Also included in the dissertation is a unique derivation which defines the constraints that a region must satisfy such that a general three dimensional region of non-homogenous material can be modeled as a two terminal lumped reluctance element. The final restrictions imposed on the general three dimensional region are quite liberal. A method for solving any arbitrarily connected network of nonlinear lumped reluctances and sources is shown in detail. The method was developed specifically for use in this dissertation research, however, it is general enough to be applied to a wide variety of lumped element magnetic problems. The method explains how a Newton-Raphson iteration loop can be used to solve the nonlinear matrix equation created

  13. Solar array switching unit

    NASA Technical Reports Server (NTRS)

    Craig, Jr., Calvin L. (Inventor)

    2000-01-01

    A solar array switching (SASU) unit (22) according to the present invention includes a control system (24), a solar cell array (26) and switch circuits (28). The SASU unit (22) is associated with a power card (30) for receiving an output from the array (26). The array (26) has a number (0.5Y) of rows (38) each of which includes a pair of cell strings (42) separated by one of the switch circuits (28). Each of the strings (42) includes a number (X) of cells in electrical series. The SASU (22) switches the array (26) between a short string configuration where the array (26) effectively includes Y strings of X length, and a long string configuration where the array (26) effectively includes 0.5Y strings of 2X length. The SASU (22) thereby facilitates the use of solar power for space missions where solar intensity, operating temperature or other factors vary significantly.

  14. Plasmonic enhanced ultrafast switch.

    SciTech Connect

    Subramania,Ganapathi Subramanian; Reno, John Louis; Passmore, Brandon Scott; Harris, Tom.; Shaner, Eric Arthur; Barrick, Todd A.

    2009-09-01

    Ultrafast electronic switches fabricated from defective material have been used for several decades in order to produce picosecond electrical transients and TeraHertz radiation. Due to the ultrashort recombination time in the photoconductor materials used, these switches are inefficient and are ultimately limited by the amount of optical power that can be applied to the switch before self-destruction. The goal of this work is to create ultrafast (sub-picosecond response) photoconductive switches on GaAs that are enhanced through plasmonic coupling structures. Here, the plasmonic coupler primarily plays the role of being a radiation condenser which will cause carriers to be generated adjacent to metallic electrodes where they can more efficiently be collected.

  15. An optical switch

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1987-04-30

    The invention is a gas mixture for a diffuse discharge switch having an electron attaching gas wherein electron attachment is brought about by indirect excitation of molecules to long live states by exposure to laser light. 3 figs.

  16. Switching and stopping antidepressants

    PubMed Central

    Keks, Nicholas; Hope, Judy; Keogh, Simone

    2016-01-01

    SUMMARY Switching from one antidepressant to another is frequently indicated due to an inadequate treatment response or unacceptable adverse effects. All antidepressant switches must be carried out cautiously and under close observation. Conservative switching strategies involve gradually tapering the first antidepressant followed by an adequate washout period before the new antidepressant is started. This can take a long time and include periods of no treatment with the risk of potentially life-threatening exacerbations of illness. Clinical expertise is needed for more rapid or cross-taper switching as drug toxicity, including serotonin syndrome, may result from inappropriate co-administration of antidepressants. Some antidepressants must not be combined. Antidepressants can cause withdrawal syndromes if discontinued abruptly after prolonged use. Relapse and exacerbation of depression can also occur. Gradual dose reduction over days to weeks reduces the risk and severity of complications. PMID:27346915

  17. Optical fiber crossbar switch

    NASA Astrophysics Data System (ADS)

    Kilcoyne, Michael K.; Beccue, Stephen M.; Brar, Berinder; Robinson, G.; Pedrotti, Kenneth D.; Haber, William A.

    1990-07-01

    Advances in high performance computers and signal processing systems have led to parallel system architectures. The main limitation in achieving the performance expected of these parallel systems has been the realization of an efficient means to interconnect many processors into a effective parallel system. Electronic interconnections have proved cumbersome, costly and ineffective. The Optical Fiber Crossbar Switch (OFCS) is a compact low power, multi-gigahertz bandwidth multi-channel switch which can be used in large scale computer and telecommunication applications. The switch operates in the optical domain using GaAs semiconductor lasers to transmit wideband multiple channel optical data over fiber optic cables. Recently, a 32 X 32 crossbar switching system was completed and demonstrated. Error free performance was obtained at a data bandwidth of 410 MBPS, using a silicon switch IC. The switch can be completely reconfigured in less than 50 nanoseconds under computer control. The fully populated OFCS has the capability to handle 12.8 gigabits per second (GBPS) of data while switching this data over 32 channels without the loss of a single bit during switching. GaAs IC technology has now progressed to the point that 16 X 16 GaAs based crossbar switch Ics are available which have increased the data bandwidth capability to 2.4 GBPS. The present optical interfaces are integrated GaAs transmitter drivers, GaAs lasers, and integrated GaAs optical receivers with data bandwidths exceeding 2.4 GBPS. A system using all Ill-V switching and optoelectronic components is presently under development for both NASA and DoD programs. The overall system is designed to operate at 1.3 GBPS. It is expected that these systems will find wide application in high capacity computing systems based on parallel microprocessor architecture which require high data bandwidth communication between processors. The OFCS will also have application in commercial optical telecommunication systems

  18. Cygnus PFL Switch Jitter

    SciTech Connect

    C. Mitton, G. Corrow, M. Hansen, D. Henderson, et al.

    2007-07-21

    The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources: Cygnus 1 and Cygnus 2. Each source has the following X-ray output: 1-mm diameter spot size, 4 rads at 1 m, 50-ns full-widthhalf-maximum. The diode pulse has the following electrical specifications: 2.25 MV, 60 kA, 60 ns. This Radiographic Facility is located in an underground tunnel test area at the Nevada Test Site (NTS). The sources were developed to produce high-resolution images on subcritical tests performed at NTS. Subcritical tests are single-shot, high-value events. For this application, it is desirable to maintain a high level of reproducibility in source output. The major components of the Cygnus machines are Marx generator, water-filled pulse forming line (PFL), water-filled coaxial transmission line, threecell inductive voltage adder, and rod-pinch diode. A primary source of fluctuation in Cygnus shot-to-shot performance may be jitter in breakdown of the main PFL switch, which is a “self-break” switch. The PFL switch breakdown time determines the peak PFL charging voltage, which ultimately affects the source X-ray spectrum and dose. Therefore, PFL switch jitter may contribute to shot-to-shot variation in these parameters, which are crucial to radiographic quality. In this paper we will present PFL switch jitter analysis for both Cygnus machines and present the correlation with dose. For this analysis, the PFL switch on each machine was maintained at a single gap setting, which has been used for the majority of shots at NTS. In addition the PFL switch performance for one larger switch gap setting will be examined.

  19. uv preilluminated gas switches

    SciTech Connect

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-06-03

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10/sup 12/ amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters.

  20. High Power Switching Transistor

    NASA Technical Reports Server (NTRS)

    Hower, P. L.; Kao, Y. C.; Carnahan, D. C.

    1983-01-01

    Improved switching transistors handle 400-A peak currents and up to 1,200 V. Using large diameter silicon wafers with twice effective area as D60T, form basis for D7 family of power switching transistors. Package includes npn wafer, emitter preform, and base-contact insert. Applications are: 25to 50-kilowatt high-frequency dc/dc inverters, VSCF converters, and motor controllers for electrical vehicles.

  1. Cygnus Water Switch Jitter

    SciTech Connect

    Charles V. Mitton, George D. Corrow, Mark D. Hansen, David J. Henderson, et al.

    2008-03-01

    The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources - Cygnus 1 and Cygnus 2. Each source has the following x-ray output: 1-mm diameter spot size, 4 rad at 1 m, 50-ns Full Width Half Max. The diode pulse has the following electrical specifications: 2.25 MV, 60 kA, 60 ns. This Radiographic Facility is located in an underground tunnel test area at the Nevada Test Site (NTS). The sources were developed to produce high-resolution images on subcritical tests which are performed at NTS. Subcritical tests are single-shot, high-value events. For this application, it is desirable to maintain a high level of reproducibility in source output. The major components of the Cygnus machines are: Marx generator, water-filled pulse–forming line (PFL), water-filled coaxial transmission line, three-cell inductive voltage adder, and rod-pinch diode. A primary source of fluctuation in Cygnus shot-to-shot performance is jitter in breakdown of the main PFL switch, which is a “self-break” switch. The PFL switch breakdown time determines the peak PFL charging voltage, which ultimately affects the diode pulse. Therefore, PFL switch jitter contributes to shot-to-shot variation in source endpoint energy and dose. In this paper we will present PFL switch jitter analysis for both Cygnus machines and give the correlation with diode performance. For this analysis the PFL switch on each machine was maintained at a single gap setting which has been used for the majority of shots at NTS. In addition to this analysis, PFL switch performance for different switch gap settings taken recently will be examined. Lastly, implications of source jitter for radiographic diagnosis of subcritical shots will be discussed.

  2. Finding a stabilising switching law for switching nonlinear models

    NASA Astrophysics Data System (ADS)

    Lendek, Zs.; Raica, P.; Lauber, J.; Guerra, T. M.

    2016-09-01

    This paper considers the stabilisation of switching nonlinear models by switching between the subsystems. We assume that arbitrary switching between two subsystems is possible once a subsystem has been active for a predefined number of samples. We use a Takagi-Sugeno representation of the models and a switching Lyapunov function is employed to develop sufficient stability conditions. If the conditions are satisfied, we construct a switching law that stabilises the system. The application of the conditions is illustrated in several examples.

  3. Light-induced electrical switching of porphyrin-covered silicon nanowire FETs (presentation video)

    NASA Astrophysics Data System (ADS)

    Cuniberti, Gianaurelio

    2014-03-01

    Nanowires represent excellent building blocks for future nanoelectronics, due to their efficient charge transport characteristics. Here we present light-induced switching behaviour of porphyrin-coated silicon nanowire field effect transistors (Si NW FETs) and demonstrate their capabilities for design of hybrid nanodevices - consisting of organic complexes and inorganic nanowires. Switching of Si NW FETs highly reflects the electrical change of porphyrin molecules by light. To demonstrate significant factors of concentration-dependent switching of porphyrin-covered devices, electrical charging mechanism through molecules and nanowires has been understood, that allows the systematic integration of the hybrid devices.

  4. From dictatorship to a reluctant democracy: stroke therapists talking about self-management

    PubMed Central

    Kilbride, Cherry

    2014-01-01

    Purpose Self-management is being increasingly promoted within chronic conditions including stroke. Concerns have been raised regarding professional ownership of some programmes, yet little is known of the professional’s experience. This paper aims to present the views of trained therapists about the utility of a specific self-management approach in stroke rehabilitation. Method Eleven stroke therapists trained in the self-management approach participated in semi-structured interviews. These were audio recorded, transcribed verbatim and analysed thematically. Results Two overriding themes emerged. The first was the sense that in normal practice therapists act as “benign dictators”, committed to help their patients, but most comfortable when they, the professional, are in control. Following the adoption of the self-management approach therapists challenged themselves to empower stroke survivors to take control of their own recovery. However, therapists had to confront many internal and external challenges in this transition of power resulting in the promotion of a somewhat “reluctant democracy”. Conclusions This study illustrates that stroke therapists desire a more participatory approach to rehabilitation. However, obstacles challenged the successful delivery of this goal. If self-management is an appropriate model to develop in post stroke pathways, then serious consideration must be given to how and if these obstacles can be overcome. Implications for Rehabilitation Stroke therapists perceive that self-management is appropriate for encouraging ownership of rehabilitation post stroke. Numerous obstacles were identified as challenging the implementation of self-management post stroke. These included: professional models, practices and expectations; institutional demands and perceived wishes of stroke survivors. For self-management to be effectively implemented by stroke therapists, these obstacles must be considered and overcome. This should be as part of

  5. A Experimental Investigation and Optimization of a Variable Reluctance Spherical Motor.

    NASA Astrophysics Data System (ADS)

    Roth, Ronald B.

    1992-01-01

    In robotic wrist applications, a three degree -of-freedom variable reluctance (VR) spherical motor offers advantages over conventional mechanisms which includes its compact size, the potential of no singularities in its workspace except at its boundaries, and continuous three dimensional motion with uniform resolution. Although the principle of a VR spherical motor has been demonstrated, the modeling techniques remained to be verified. Therefore, this research investigated and further developed the magnetic modeling techniques essential to the design and control law development of a VR spherical motor. A nonlinear magnetic circuit model is presented which is composed of linear (airgap) permeance elements and nonlinear (iron) permeance elements. The model reduces the complex field distribution of the spherical motor magnetic system governed by Maxwell's equations to a tractable magnetic model. A torque prediction model is presented which determines the torque generated by the spherical motor for a given set of input currents to the coils. An experimental airgap permeance function was determined from a VR spherical motor experimental testbed utilizing the linear magnetic circuit model. The permeance function showed good agreement with the theoretical overlapping area permeance model for small pole separation angles. Flux density levels were estimated in iron "choke" points and saturation was successfully predicted. Inclusion of the iron permeance in noncritical motor iron regions improved torque predictions under saturated conditions. Finally, a methodology for optimizing the VR spherical motor's magnetics is presented. The formulation focused on the derivation of inequalities governing geometry, thermal, amplifier, saturation, and leakage flux. An example problem is presented where the motor's geometry is determined by maximizing the output torque at one rotor orientation subject to constraints. The resulting analysis provides experimental verification of modeling

  6. Low inductance gas switching.

    SciTech Connect

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  7. Innovative switching technology

    NASA Astrophysics Data System (ADS)

    Rosen, A.; Stabile, P. J.; Gombar, A. M.; Janton, W. M.; Gilbert, D. B.; Herczfeld, P. R.; Bahasadri, A.

    1991-03-01

    We have developed an all-semiconductor high-power optical switch. Potential uses include both military applications, such as ultra-wide-band impulse radar and high-frequency antenna couplers, and commercial use, such as high-power switching for utility companies. Under this three-year program, we have demonstrated various switching applications from dc to GHz frequencies. The generic switches comprise a 2-D semiconductor laser diode array and Si or GaAs devices. In the Si area (linear switches - no gain) and dc-biased network, a single two-sided PIN device, activated by two 1 kW laser arrays, has yielded a holding voltage of 1.3 kV and conducted 192 A. Similar devices have later yielded a holding voltage of 3.3 kV, demonstrating the capability of switching more than 500 kW with a single two-sided PIN device. The same generic technology was also demonstrated in high-power high-frequency antenna coupler applications as well as in mm-wave (60 GHz) attenuators and phase shifters. PIN devices tested in a RF circuit between 2-30 MHz yielded an isolation value of between 28 and 49 dB in the off-state, and insertion losses as low as 0.1 dB when illuminated with 280 W (peak) optical power at 808 nm. In the area of GaAs, PIN, and bulk devices under this project, we were able to deliver devices for experiments in both opening and closing switches. We have demonstrated a compact, all-semiconductor switch system that has switched up to 8.5 MW into a 38 (omega) load. The system uses a 2-D laser diode array with a peak power of 850 W to rigger a 1.5 cm long GaAs photoconductor into a high-gain combination mode known as 'lock on'. The highest power switch was pulse-charged to 55 kV and delivered 470 A to a 38 (omega) load in 160 ns long pulse. In the area of 2-D laser arrays, a peak power density of 7 kW/cm(exp 2) was achieved.

  8. PM Motor Parametric Design Analyses for Hybrid Electric Vehicle Traction Drive Application: Interim Report

    SciTech Connect

    Staunton, R.H.

    2004-08-11

    The Department of Energy's (DOE) Office of FreedomCAR (Cooperative Automotive Research) and Vehicle Technologies has a strong interest in making rapid progress in permanent magnet (PM) machine development. The program is directing various technology development projects that will advance the technology and lead to request for proposals (RFP) for manufacturer prototypes. This aggressive approach is possible because the technology is clearly within reach and the approach is deemed essential, based on strong market demand, escalating fuel prices, and competitive considerations. In response, this study began parallel development paths that included a literature search/review, development and utilization of multiple parametric models to determine the effects of design parameters, verification of the modeling methodology, development of an interior PM (IPM) machine baseline design, development of alternative machine baseline designs, and cost analyses for several candidate machines. This interim progress report summarizes the results of these activities as of June 2004. This report provides background and summary information for recent machine parametric studies and testing programs that demonstrate both the potential capabilities and technical limitations of brushless PM machines (axial gap and radial gap), the IPM machine, the surface-mount PM machines (interior or exterior rotor), induction machines, and switched reluctance machines. The FreedomCAR program, while acknowledging the progress made by Oak Ridge National Laboratory, Delphi, Delco-Remy International, and others in these programs, has redirected efforts toward a ''short path'' to a marketable and competitive PM motor for hybrid electric vehicle traction applications. The program has developed a set of performance targets for the type of traction machine desired. The short-path approach entails a comprehensive design effort focusing on the IPM machine and meeting the performance targets. The selection of the

  9. PM Motor Parametric Design Analyses for a Hybrid Electric Vehicle Traction Drive Application

    SciTech Connect

    Staunton, R.H.

    2004-10-11

    The Department of Energy's (DOE) Office of FreedomCAR (Cooperative Automotive Research) and Vehicle Technologies office has a strong interest in making rapid progress in permanent magnet (PM) machine development. The DOE FreedomCAR program is directing various technology development projects that will advance the technology and hopefully lead to a near-term request for proposals (RFP) for a to-be-determined level of initial production. This aggressive approach is possible because the technology is clearly within reach and the approach is deemed essential, based on strong market demand, escalating fuel prices, and competitive considerations. In response, this study began parallel development paths that included a literature search/review, development and utilization of multiple parametric models, verification of the modeling methodology, development of an interior PM (IPM) machine baseline design, development of alternative machine baseline designs, and cost analyses for several candidate machines. This report summarizes the results of these activities as of September 2004. This report provides background and summary information for recent machine parametric studies and testing programs that demonstrate both the potential capabilities and technical limitations of brushless PM machines (axial gap and radial gap), the IPM machine, the surface-mount PM machines (interior or exterior rotor), induction machines, and switched-reluctance machines. The FreedomCAR program, while acknowledging the progress made by Oak Ridge National Laboratory (ORNL), Delphi, Delco-Remy International, and others in these programs, has redirected efforts toward a ''short path'' to a marketable and competitive PM motor for hybrid electric vehicle (HEV) traction applications. The program has developed a set of performance targets for the type of traction machine desired. The short-path approach entails a comprehensive design effort focusing on the IPM machine and meeting the performance targets

  10. A radiation hard vacuum switch

    DOEpatents

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  11. Long Life MEM Switch Technology

    DTIC Science & Technology

    2006-05-23

    The first type of MEM switch developed was the miniature switched capacitor. This device is 150-300 times smaller than conventional MEM switches...down and the shunt capacitance to the ground is increased. The mechanical behavior of the MEM capacitor is designed using conventional mechanical...switched capacitors. It proves that by decreasing the size, miniature switched capacitors with Con/ Coff =2.8 for a single bridge and Con/ Coff =1.9 for a 3

  12. Switching power pulse system

    DOEpatents

    Aaland, K.

    1983-08-09

    A switching system for delivering pulses of power from a source to a load using a storage capacitor charged through a rectifier, and maintained charged to a reference voltage level by a transistor switch and voltage comparator. A thyristor is triggered to discharge the storage capacitor through a saturable reactor and fractional turn saturable transformer having a secondary to primary turn ratio N of n:l/n = n[sup 2]. The saturable reactor functions as a soaker'' while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor charges, and then switches to a low impedance state to dump the charge of the storage capacitor into the load through the coupling capacitor. The transformer is comprised of a multilayer core having two secondary windings tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe for a linear particle accelerator and capacitance of a pulse forming network. To hold off discharge of the capacitance until it is fully charged, a saturable core is provided around the resistive beampipe to isolate the beampipe from the capacitance until it is fully charged. 5 figs.

  13. Atomic Scale Plasmonic Switch.

    PubMed

    Emboras, Alexandros; Niegemann, Jens; Ma, Ping; Haffner, Christian; Pedersen, Andreas; Luisier, Mathieu; Hafner, Christian; Schimmel, Thomas; Leuthold, Juerg

    2016-01-13

    The atom sets an ultimate scaling limit to Moore's law in the electronics industry. While electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling, similar to electronics, is only limited by the atom. More precisely, we introduce an electrically controlled plasmonic switch operating at the atomic scale. The switch allows for fast and reproducible switching by means of the relocation of an individual or, at most, a few atoms in a plasmonic cavity. Depending on the location of the atom either of two distinct plasmonic cavity resonance states are supported. Experimental results show reversible digital optical switching with an extinction ratio of 9.2 dB and operation at room temperature up to MHz with femtojoule (fJ) power consumption for a single switch operation. This demonstration of an integrated quantum device allowing to control photons at the atomic level opens intriguing perspectives for a fully integrated and highly scalable chip platform, a platform where optics, electronics, and memory may be controlled at the single-atom level.

  14. Silicon carbide photoconductive switches

    NASA Astrophysics Data System (ADS)

    Saddow, Stephen E.

    1994-09-01

    The optoelectronic properties of p-type 6-H silicon carbide (6H-SiC) have been investigated in an experiment that used lateral and vertical photoconductive (PC) switches. Both photovoltaic and photoconductive effects are reported, which were observed on switches using both geometries and measured at several wavelengths near the 6H-SiC absorption edge. PC techniques were employed to measure the surface and bulk carrier lifetimes of 40 and 200 ns, respectively. The switches displayed a high-speed photovoltaic response to picosecond laser excitations in the UV and visible spectral regions. In particular, efficient subnanosecond optical absorption processes were observed in the visible region. The photovoltage was measured as a function of both laser wavelength (and hence absorption depth) and laser beam position within the switching gap. The switch response to picosecond laser pulses in the UV, violet, green, and red spectral regions was shown to have subnanosecond photovoltaic response times. Finally, since the optical absorption coefficient had not been well established for device-grade 6H-SiC, the optical absorption coefficient near the 6H-SiC bandgap energy (Eg) was also measured, and the bandgap was determined to be approximately 3.1 eV.

  15. Multiple switch actuator

    DOEpatents

    Beyer, Edward T.

    1976-01-06

    The present invention relates to switches and switch actuating devices to be operated for purposes of arming a bomb or other missile as it is dropped or released from an aircraft. The particular bomb or missile in which this invention is applied is one in which there is a plurality of circuits which are to be armed by the closing of switches upon dropping or releasing of the bomb. The operation of the switches to closed position is normally accomplished by means of a pull-out wire; that is, a wire which is withdrawn from the bomb or missile at the time of release of the bomb, one end of the wire being attached to the aircraft. The conditions to be met are that the arming switches must be positively and surely maintained in open position until the bomb is released and the arming action is effected. The action of the pull-out wire in achieving the arming action must be sure and positive with minimum danger of malfunctioning, jamming or binding.

  16. Thermionic gas switch

    DOEpatents

    Hatch, G.L.; Brummond, W.A.; Barrus, D.M.

    1984-04-05

    The present invention is directed to an improved temperature responsive thermionic gas switch utilizing a hollow cathode and a folded emitter surface area. The folded emitter surface area of the thermionic switch substantially increases the on/off ratio by changing the conduction surface area involved in the two modes thereof. The improved switch of this invention provides an on/off ratio of 450:1 compared to the 10:1 ratio of the prior known thermionic switch, while providing for adjusting the on current. In the improved switch of this invention the conduction area is made small in the off mode, while in the on mode the conduction area is made large. This is achieved by utilizing a folded hollow cathode configuration and utilizing a folded emitter surface area, and by making the dimensions of the folds small enough so that a space charge will develop in the convolutions of the folds and suppress unignited current, thus limiting the current carrying surface in the off mode.

  17. Semiconductor/High-Tc-Superconductor Hybrid ICs

    NASA Technical Reports Server (NTRS)

    Burns, Michael J.

    1995-01-01

    Hybrid integrated circuits (ICs) containing both Si-based semiconducting and YBa(2)Cu(3)O(7-x) superconducting circuit elements on sapphire substrates developed. Help to prevent diffusion of Cu from superconductors into semiconductors. These hybrid ICs combine superconducting and semiconducting features unavailable in superconducting or semiconducting circuitry alone. For example, complementary metal oxide/semiconductor (CMOS) readout and memory devices integrated with fast-switching Josephson-junction super-conducting logic devices and zero-resistance interconnections.

  18. Semiconductor/High-Tc-Superconductor Hybrid ICs

    NASA Technical Reports Server (NTRS)

    Burns, Michael J.

    1995-01-01

    Hybrid integrated circuits (ICs) containing both Si-based semiconducting and YBa(2)Cu(3)O(7-x) superconducting circuit elements on sapphire substrates developed. Help to prevent diffusion of Cu from superconductors into semiconductors. These hybrid ICs combine superconducting and semiconducting features unavailable in superconducting or semiconducting circuitry alone. For example, complementary metal oxide/semiconductor (CMOS) readout and memory devices integrated with fast-switching Josephson-junction super-conducting logic devices and zero-resistance interconnections.

  19. Microfabricated triggered vacuum switch

    DOEpatents

    Roesler, Alexander W.; Schare, Joshua M.; Bunch, Kyle

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  20. Optical computer switching network

    NASA Technical Reports Server (NTRS)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  1. Switching power supply

    DOEpatents

    Mihalka, A.M.

    1984-06-05

    The invention is a repratable capacitor charging, switching power supply. A ferrite transformer steps up a dc input. The transformer primary is in a full bridge configuration utilizing power MOSFETs as the bridge switches. The transformer secondary is fed into a high voltage, full wave rectifier whose output is connected directly to the energy storage capacitor. The transformer is designed to provide adequate leakage inductance to limit capacitor current. The MOSFETs are switched to the variable frequency from 20 to 50 kHz to charge a capacitor from 0.6 kV. The peak current in a transformer primary and secondary is controlled by increasing the pulse width as the capacitor charges. A digital ripple counter counts pulses and after a preselected desired number is reached an up-counter is clocked.

  2. SWITCH user's manual

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The planning program, SWITCH, and its surrounding changed-goal-replanning program, Runaround, are described. The evolution of SWITCH and Runaround from an earlier planner, DEVISER, is recounted. SWITCH's plan representation, and its process of building a plan by backward chaining with strict chronological backtracking, are described. A guide for writing knowledge base files is provided, as are narrative guides for installing the program, running it, and interacting with it while it is running. Some utility functions are documented. For the sake of completeness, a narrative guide to the experimental discrepancy-replanning feature is provided. Appendices contain knowledge base files for a blocksworld domain, and a DRIBBLE file illustrating the output from, and user interaction with, the program in that domain.

  3. Optical Computer Switching Network

    NASA Astrophysics Data System (ADS)

    Clymer, B.; Collins, S. A., Jr.

    1985-02-01

    In this paper we present the design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. We first present the basic system, then describe the matrix-based connecting system and review some of the optical components to be used. Finally, the details of the control system are given and illustrated with a discussion of timing.

  4. Optical computer switching network

    NASA Astrophysics Data System (ADS)

    Clymer, B.; Collins, S. A., Jr.

    1985-02-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  5. Optical computer switching network

    NASA Technical Reports Server (NTRS)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  6. FAST ACTING CURRENT SWITCH

    DOEpatents

    Batzer, T.H.; Cummings, D.B.; Ryan, J.F.

    1962-05-22

    A high-current, fast-acting switch is designed for utilization as a crowbar switch in a high-current circuit such as used to generate the magnetic confinement field of a plasma-confining and heat device, e.g., Pyrotron. The device particularly comprises a cylindrical housing containing two stationary, cylindrical contacts between which a movable contact is bridged to close the switch. The movable contact is actuated by a differential-pressure, airdriven piston assembly also within the housing. To absorb the acceleration (and the shock imparted to the device by the rapidly driven, movable contact), an adjustable air buffer assembly is provided, integrally connected to the movable contact and piston assembly. Various safety locks and circuit-synchronizing means are also provided to permit proper cooperation of the invention and the high-current circuit in which it is installed. (AEC)

  7. SHOCKPROOF MAGNETIC REED SWITCH

    DOEpatents

    Medal, E.

    1962-03-13

    A shockproof magnetic reed switch is described which comprises essentially a plurality of pairs of reed contacts of magnetic, electrical conducting material which are arranged generally in circumferential spaced relationship. At least two of the pairs are disposed to operate at a predetermined angle with respect to each other, and the contacts are wired in the circuit, so that the continuity, or discontinuity, of the circuit is not affected by a shock imposed on the switch. The contacts are hermetically sealed within an outer tubular jacket. (AEC)

  8. Thermionic gas switch

    DOEpatents

    Hatch, George L.; Brummond, William A.; Barrus, Donald M.

    1986-01-01

    A temperature responsive thermionic gas switch having folded electron emitting surfaces. An ionizable gas is located between the emitter and an interior surface of a collector, coaxial with the emitter. In response to the temperature exceeding a predetermined level, sufficient electrons are derived from the emitter to cause the gas in the gap between the emitter and collector to become ionized, whereby a very large increase in current in the gap occurs. Due to the folded emitter surface area of the switch, increasing the "on/off" current ratio and adjusting the "on" current capacity is accomplished.

  9. Organometallic spintronics: dicobaltocene switch.

    PubMed

    Liu, Rui; Ke, San-Huang; Baranger, Harold U; Yang, Weitao

    2005-10-01

    A single-molecule spintronic switch and spin valve using two cobaltocene moieties is proposed. Spin-dependent transport through a lead-molecule-lead junction has been calculated using first-principles density functional and nonequilibrium Green function methods. We find that the antiparallel (singlet) configuration of the cobaltocene spins blocks electron transport near the Fermi energy, while the spin parallel (triplet) configuration enables much higher current. The energy difierence between the antiparallel and parallel states depends on the insulating spacer separating the two cobaltocenes, allowing switching through the application of a moderate magnetic field.

  10. Wide-Scope Screening of Illegal Adulterants in Dietary and Herbal Supplements via Rapid Polarity-Switching and Multistage Accurate Mass Confirmation Using an LC-IT/TOF Hybrid Instrument.

    PubMed

    Guo, Bin; Wang, Meiling; Liu, Yanyan; Zhou, Jing; Dai, Hua; Huang, Zhiqiang; Shen, Lingling; Zhang, Qingsheng; Chen, Bo

    2015-08-12

    A new analytical strategy was developed that integrates a generic sample preparation into a liquid chromatography-multistage ion trap/time-of-flight mass spectrometry (LC-IT(MS(n))/TOF), allowing for large-scale screening and qualitative confirmation of wide-scope illegal adulterants in different food matrices. Samples were pretreated by a fast single-tube multifunction extraction for accurate multistage mass measurement on the hybrid LC-IT/TOF system. A qualitative validation performed for over 500 analyte-matrix pairs showed the method can reduce most of the matrix effects and achieve a lower limit of confirmation at 0.1 mg/kg for 73% of the target compounds. A unique combination of dual-polarity detection, retention time, isotopic profile, and accurate MS(n) spectra enables more comprehensive and precise confirmation, based on the multiparameter matching by automated library searching against the user-created database. Finally, the applicability of this LC-IT(MS(n))/TOF-based screening procedure for discriminating coeluting isobars, identifying nontarget adulterants, and even tentatively elucidating unexpected species in real samples is demonstrated.

  11. Electric and hybrid vehicle systems assessment seminar: proceedings

    SciTech Connect

    Not Available

    1984-03-15

    The following twenty papers are included in these proceedings: (1) electric and hybrid vehicle assessment overview, (2) electric and hybrid vehicle systems considerations, (3) advanced vehicle assessment, (4) hybrid vehicle assessment, (5) battery optimization considerations, (6) alkaline battery technology, (7) lead-acid batteries, (8) nickel-iron batteries, (9) zinc-chloride batteries, (10) zinc-bromine batteries, (11) sodium-sulfur batteries, (12) system/battery design interaction for a lithium-method sulfide van battery, (13) iorn-air batteries, (14) aluminium-air cells, (15) fuel cell overview, (16) variable-reluctance motor drives, (17) electric vehicle design, (18) advanced electric vehicle powertrain program, (19) Eaton ac drivetrains, and (20) JET Propulsion Laboratory ac power system. (MOW)

  12. Main electrical switch banks, plant switch house, looking to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Main electrical switch banks, plant switch house, looking to the North - Bureau of Mines Metallurgical Research Laboratory, Original Building, Date Street north of U.S. Highway 93, Boulder City, Clark County, NV

  13. 41. INTERIOR VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. INTERIOR VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH LEVER ASSEMBLAGE AND DISPLAY BOARD - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  14. 35. END VIEW, INTERIOR, SHOWING SWITCHING LEVERS, BERK SWITCH TOWER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. END VIEW, INTERIOR, SHOWING SWITCHING LEVERS, BERK SWITCH TOWER, SOUTH NORWALK - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  15. 36. INTERIOR VIEW, BERK SWITCH TOWER, SOUTH NORWALK, SHOWING SWITCHING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. INTERIOR VIEW, BERK SWITCH TOWER, SOUTH NORWALK, SHOWING SWITCHING LEVERS FROM OPERATOR'S POSITION - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  16. 43. OBLIQUE VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    43. OBLIQUE VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH LEVER ASSEMBLAGE AND DISPLAY BOARD - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  17. Differential Occurrence of Reluctant Openings in G-Protein–Inhibited N- and P/Q-Type Calcium Channels

    PubMed Central

    Colecraft, Henry M.; Patil, Parag G.; Yue, David T.

    2000-01-01

    Voltage-dependent inhibition of N- and P/Q-type calcium channels by G proteins is crucial for presynaptic inhibition of neurotransmitter release, and may contribute importantly to short-term synaptic plasticity. Such calcium-channel modulation could thereby impact significantly the neuro-computational repertoire of neural networks. The differential modulation of N and P/Q channels could even further enrich their impact upon synaptic tuning. Here, we performed in-depth comparison of the G-protein inhibition of recombinant N and P/Q channels, expressed in HEK 293 cells with the m2 muscarinic receptor. While both channel types display classic features of G-protein modulation (kinetic slowing of activation, prepulse facilitation, and voltage dependence of inhibition), we confirmed previously reported quantitative differences, with N channels displaying stronger inhibition and greater relief of inhibition by prepulses. A more fundamental, qualitative difference in the modulation of these two channels was revealed by a modified tail-activation paradigm, as well as by a novel “slope” analysis method comparing time courses of slow activation and prepulse facilitation. The stark contrast in modulatory behavior can be understood within the context of the “willing–reluctant” model, in which binding of G-protein βγ subunits to channels induces a reluctant mode of gating, where stronger depolarization is required for opening. Our experiments suggest that only N channels could be opened in the reluctant mode, at voltages normally spanned by neuronal action potentials. By contrast, P/Q channels appear to remain closed, especially over these physiological voltages. Further, the differential occurrence of reluctant openings is not explained by differences in the rate of G-protein unbinding from the two channels. These two scenarios predict very different effects of G-protein inhibition on the waveform of Ca2+ entry during action potentials, with potentially important

  18. Photonic MEMS switch applications

    NASA Astrophysics Data System (ADS)

    Husain, Anis

    2001-07-01

    As carriers and service providers continue their quest for profitable network solutions, they have shifted their focus from raw bandwidth to rapid provisioning, delivery and management of revenue generating services. Inherently transparent to data rate the transmission wavelength and data format, MEMS add scalability, reliability, low power and compact size providing flexible solutions to the management and/or fiber channels in long haul, metro, and access networks. MEMS based photonic switches have gone from the lab to commercial availability and are now currently in carrier trials and volume production. 2D MEMS switches offer low up-front deployment costs while remaining scalable to large arrays. They allow for transparent, native protocol transmission. 2D switches enable rapid service turn-up and management for many existing and emerging revenue rich services such as storage connectivity, optical Ethernet, wavelength leasing and optical VPN. As the network services evolve, the larger 3D MEMS switches, which provide greater scalability and flexibility, will become economically viable to serve the ever-increasing needs.

  19. Kiowa Creek Switching Station

    SciTech Connect

    Not Available

    1990-03-01

    The Western Area Power Administration (Western) proposes to construct, operate, and maintain a new Kiowa Creek Switching Station near Orchard in Morgan County, Colorado. Kiowa Creek Switching Station would consist of a fenced area of approximately 300 by 300 feet and contain various electrical equipment typical for a switching station. As part of this new construction, approximately one mile of an existing 115-kilovolt (kV) transmission line will be removed and replaced with a double circuit overhead line. The project will also include a short (one-third mile) realignment of an existing line to permit connection with the new switching station. In accordance with the Council on Environmental Quality (CEQ) regulations for implementing the procedural provisions of the National Environmental Policy Act of 1969 (NEPA), 40 CFR Parts 1500--1508, the Department of Energy (DOE) has determined that an environmental impact statement (EIS) is not required for the proposed project. This determination is based on the information contained in this environmental assessment (EA) prepared by Western. The EA identifies and evaluates the environmental and socioeconomic effects of the proposed action, and concludes that the advance impacts on the human environment resulting from the proposed project would not be significant. 8 refs., 3 figs., 1 tab.

  20. Multipath star switch controller

    NASA Technical Reports Server (NTRS)

    Anderson, T. O.

    1980-01-01

    Device concept permits parallel computers to scan several commonnetwork-connected data stations at maximum rate. Sequencers leap-frog to bypass ports already being serviced by another computer. Two-path system for 16-port star switch controller is cost effective if added bandwidth or increased reliability is desired. Triple-path system would be cost effective for 32-port controller.

  1. Waveguide switch protector

    NASA Technical Reports Server (NTRS)

    Kolbly, R. B.

    1972-01-01

    Device for detecting excessive operation of electric motors used to drive waveguide switches is described. Purpose of device is to prevent burnout of electric motor in event of waveguide stoppage at some point other than extreme limits of travel. Operation of equipment, components used to sense motor performance, and schematic diagram are included.

  2. Gas injected vacuum switch

    DOEpatents

    Hardin, K. Dan

    1977-01-01

    The disclosure relates to a gas injected vacuum switch comprising a housing having an interior chamber, a conduit for evacuating the interior chamber, within the chamber an anode and a cathode spaced from the anode, and a detonator for injecting electrically conductive gas into the chamber between the anode and the cathode to provide a current path therebetween.

  3. Silicon Carbide Photoconductive Switches

    DTIC Science & Technology

    1994-09-01

    The optoelectronic properties of p-type 6-H silicon carbide (6H-SiC) have been investigated in an experiment that used lateral and vertical...and the bandgap was determined to be approximately 3.1 eV. 6H-SiC, Photoconductive, Photovoltaic, Absorption coefficient, Switch, Silicon carbide

  4. An integrated circuit switch

    NASA Technical Reports Server (NTRS)

    Bonin, E. L.

    1969-01-01

    Multi-chip integrated circuit switch consists of a GaAs photon-emitting diode in close proximity with S1 phototransistor. A high current gain is obtained when the transistor has a high forward common-emitter current gain.

  5. Molecular Rotors as Switches

    PubMed Central

    Xue, Mei; Wang, Kang L.

    2012-01-01

    The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene) monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P+ Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 104, a read window of about 2.5 V, and a retention time of greater than 104 s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V) revealed a temperature-dependent negative differential resistance (NDR) associated with the device. The analysis of the device I–V characteristics suggests the source of the

  6. Exhaust Fan Temperature Switch

    SciTech Connect

    Ball, G.S.; /Fermilab

    1989-05-11

    The 13000 cfm 'emergency' vent fan must be protected from over cooling which would result in a mechanical failure. Over cooling could result from a catastrophic cryogen release from the cryostat(s) or Argon Storage Dewar. In order to protect the fan, a VPT has been calibrated for -31 C to open a switch which sends a signal to allow warm gas to enter the sump by means of a motor controlled louver installed at 'sidewalk level' in the ductwork between the assembly hall and the Argon Dewar Enclosure. The bulb of the VPT is enclosed in a thermal well and will be placed in the gas stream directly above the fan. The switching unit will be mounted nearby on the wall in order to isolate it from vibrational effects. Should the fan be activated due to a cryogen release, it should not experience any problems when operating above -40 C. The switch was set and checked in a saturated calcium chloride solution cooled to -31 C by running cold gaseous Nitrogen through a copper tube coiled in a dewar. Switching temperature was measured by a thermocouple tied to the VPT bulb. The thermocouple was checked in LN2, in an ice water bath, and against an ordinary thermometer (which was assumed to be accurate to plus or minus 0.3 C) at room temperature. The results are shown below in 'Table 1' By interpolation of the data, thermocouple error at -31.0 C was found to be 0.43 C on the warm side. Since this error was small, it was ignored. 'Table 2' shows the results of the tests. Ten readings were taken with the switch wired in the 'normally open' mode. This results in a signal at room temperature. The worst deviation was 2.5 C. Three readings were then taken from the 'normally closed' wiring arrangement (the way it will be wired for installation). The greatest deviation was 1.2 C. The next day, the switch was checked five times wired in the 'normally open' configuration. The greatest error was 1.1 C. A graph has been prepared showing the switching and resetting temperatures. The errors these

  7. Heat-transfer thermal switch

    NASA Technical Reports Server (NTRS)

    Friedell, M. V.; Anderson, A. J.

    1974-01-01

    Thermal switch maintains temperature of planetary lander, within definite range, by transferring heat. Switch produces relatively large stroke and force, uses minimum electrical power, is lightweight, is vapor pressure actuated, and withstands sterilization temperatures without damage.

  8. Automatic thermal switch. [spacecraft applications

    NASA Technical Reports Server (NTRS)

    Cunningham, J. W.; Wing, L. D. (Inventor)

    1983-01-01

    An automatic thermal switch to control heat flow includes two thermally conductive plates and a thermally conductive switch saddle pivotally mounted to the first plate. A flexible heat carrier is connected between the switch saddle and the second plate. A phase-change power unit, including a piston coupled to the switch saddle, is in thermal contact with the first thermally conductive plate. A biasing element biases the switch saddle in a predetermined position with respect to the first plate. When the phase-change power unit is actuated by an increase in heat transmitted through the first place, the piston extends and causes the switch saddle to pivot, thereby varying the thermal conduction between the two plates through the switch saddle and flexible heat carrier. The biasing element, switch saddle, and piston can be arranged to provide either a normally closed or normally opened thermally conductive path between the two plates.

  9. Switching power pulse system

    DOEpatents

    Aaland, Kristian

    1983-01-01

    A switching system for delivering pulses of power from a source (10) to a load (20) using a storage capacitor (C3) charged through a rectifier (D1, D2), and maintained charged to a reference voltage level by a transistor switch (Q1) and voltage comparator (12). A thyristor (22) is triggered to discharge the storage capacitor through a saturable reactor (18) and fractional turn saturable transformer (16) having a secondary to primary turn ratio N of n:l/n=n.sup.2. The saturable reactor (18) functions as a "soaker" while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor (C4) charges, and then switches to a low impedance state to dump the charge of the storage capacitor (C3) into the load through the coupling capacitor (C4). The transformer is comprised of a multilayer core (26) having two secondary windings (28, 30) tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes (32, 34) for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe (40) for a linear particle accelerator and capacitance of a pulse forming network (42). To hold off discharge of the capacitance until it is fully charged, a saturable core (44) is provided around the resistive beampipe (40) to isolate the beampipe from the capacitance (42) until it is fully charged.

  10. Transparent electrode for optical switch

    DOEpatents

    Goldhar, J.; Henesian, M.A.

    1984-10-19

    The invention relates generally to optical switches and techniques for applying a voltage to an electro-optical crystal, and more particularly, to transparent electodes for an optical switch. System architectures for very large inertial confinement fusion (ICF) lasers require active optical elements with apertures on the order of one meter. Large aperture optical switches are needed for isolation of stages, switch-out from regenerative amplifier cavities and protection from target retroreflections.

  11. Radiation sensitive solid state switch

    NASA Technical Reports Server (NTRS)

    Hutto, R. J. (Inventor)

    1973-01-01

    A mechanically operable solid state switch suited for use in achieving a variable circuit-switching function is described. This switch is characterized by an annular array of photoresponsive switching devices, disposed in communication with an included source of radiation, and a plurality of interchangeable, mechanically operable interrupter disks. Each disk has a predetermined pattern of transparent and opaque portions. Operative displacement of each disk serves to make and break selected electrical circuits through the photo responsive devices of said array.

  12. Easily-wired toggle switch

    NASA Technical Reports Server (NTRS)

    Dean, W. T.; Stringer, E. J.

    1979-01-01

    Crimp-type connectors reduce assembly and disassembly time. With design, no switch preparation is necessary and socket contracts are crimped to wires inserted in module attached to back of toggle switch engaging pins inside module to make electrical connections. Wires are easily removed with standard detachment tool. Design can accommodate wires of any gage and as many terminals can be placed on switch as wire gage and switch dimensions will allow.

  13. Plastic-Sealed Hybrid Power Circuit Package

    NASA Technical Reports Server (NTRS)

    Miller, W. N.; Gray, O. E.

    1983-01-01

    Proposed design for hybrid high-voltage power-circuit package uses molded plastic for hermetic sealing instead of glass-to-metal seal. New package used to house high-voltage regulators and solid-state switches for applications in aircraft, electric automobiles, industrial equipment, satellites, solarcell arrays, and other equipment in extreme environments.

  14. Illuminated push-button switch

    NASA Technical Reports Server (NTRS)

    Iwagiri, T.

    1983-01-01

    An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

  15. Illuminated push-button switch

    NASA Astrophysics Data System (ADS)

    Iwagiri, T.

    1983-05-01

    An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

  16. Organic Materials For Optical Switching

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.

    1993-01-01

    Equations predict properties of candidate materials. Report presents results of theoretical study of nonlinear optical properties of organic materials. Such materials used in optical switching devices for computers and telecommunications, replacing electronic switches. Optical switching potentially offers extremely high information throughout in compact hardware.

  17. A Lie algebraic condition for exponential stability of discrete hybrid systems and application to hybrid synchronization.

    PubMed

    Zhao, Shouwei

    2011-06-01

    A Lie algebraic condition for global exponential stability of linear discrete switched impulsive systems is presented in this paper. By considering a Lie algebra generated by all subsystem matrices and impulsive matrices, when not all of these matrices are Schur stable, we derive new criteria for global exponential stability of linear discrete switched impulsive systems. Moreover, simple sufficient conditions in terms of Lie algebra are established for the synchronization of nonlinear discrete systems using a hybrid switching and impulsive control. As an application, discrete chaotic system's synchronization is investigated by the proposed method.

  18. A Lie algebraic condition for exponential stability of discrete hybrid systems and application to hybrid synchronization

    NASA Astrophysics Data System (ADS)

    Zhao, Shouwei

    2011-06-01

    A Lie algebraic condition for global exponential stability of linear discrete switched impulsive systems is presented in this paper. By considering a Lie algebra generated by all subsystem matrices and impulsive matrices, when not all of these matrices are Schur stable, we derive new criteria for global exponential stability of linear discrete switched impulsive systems. Moreover, simple sufficient conditions in terms of Lie algebra are established for the synchronization of nonlinear discrete systems using a hybrid switching and impulsive control. As an application, discrete chaotic system's synchronization is investigated by the proposed method.

  19. CMOS analog switches for adaptive filters

    NASA Technical Reports Server (NTRS)

    Dixon, C. E.

    1980-01-01

    Adaptive active low-pass filters incorporate CMOS (Complimentary Metal-Oxide Semiconductor) analog switches (such as 4066 switch) that reduce variation in switch resistance when filter is switched to any selected transfer function.

  20. High gain GaAs photoconductive semiconductor switches: Switch longevity

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; Mar, A.

    1998-07-01

    Optically activated, high gain GaAs switches are being tested for many different pulsed power applications that require long lifetime (longevity). The switches have p and n contact metallization (with intentional or unintentional dopants) configured in such a way as to produce p-i-n or n-i-n switches. The longevity of the switches is determined by circuit parameters and by the ability of the contacts to resist erosion. This paper will describe how the switches performed in test-beds designed to measure switch longevity. The best longevity was achieved with switches made with diffused contacts, achieving over 50 million pulses at 10 A and over 2 million pulses at 80 A.

  1. Measurement method for determining the magnetic hysteresis effects of reluctance actuators by evaluation of the force and flux variation

    NASA Astrophysics Data System (ADS)

    Vrijsen, N. H.; Jansen, J. W.; Compter, J. C.; Lomonova, E. A.

    2013-07-01

    A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.

  2. Measurement method for determining the magnetic hysteresis effects of reluctance actuators by evaluation of the force and flux variation.

    PubMed

    Vrijsen, N H; Jansen, J W; Compter, J C; Lomonova, E A

    2013-07-01

    A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.

  3. Simulink(Trademark) Controller for a Reluctance Motor With a Four-Pole Rotor and 36-Tooth Stator

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Provenza, Andrew J.

    2017-01-01

    NASA Glenn Research Center has developed a Simulink(Trademark) controller logic for driving a room temperature, 36-teeth stator, four-pole rotor reluctance motor. The Simulink logic was extracted from an existing C++ motor controller that was previously employed to achieve a rotor speed of 3000 rpm. The Simulink controller has additional logic refinements that were not available in past C++ controller, such as the per rev logic component and its frequency filter. The filter provides a more accurate reading of the rotor input signals. The controller is versatile, and with slight modifications, can be used to drive other reluctance motor types incorporating dissimilar stator rotor pole combinations. The original C++ controller was designed with the goal (after appropriate modification) of controlling a future superconducting motor. This superconducting motor will be employed as a test bed for developing other superconducting aviation propulsion motors envisioned for future turbo-electric aircrafts. The Simulink results presented in this paper were generated from simulated rotor inputs. However, in an actual application, these simulated inputs are to be replaced by actual proximity probe signals emanating from D-Space hardware inputs.

  4. Why are some HIV/AIDS patients reluctant to receive antiviral therapy as soon as possible in China?

    PubMed

    Sun, Yang; Lu, Hongzhou

    2014-06-01

    In more than 20 years of medical practice, a surprising phenomenon has often occurred: some patients with acquired immunodeficiency syndrome (AIDS) decide not to go to the hospital and they do not let others know that they are suffering from the disease unless they believe that they are dieing. Zhang Shan (a pseudonym) is one such patient with human immunodeficiency virus (HIV)/AIDS who was reluctant to receive antiviral therapy as soon as possible, and this paper shares Zhang's story as he related it. Clearly, there are numerous views as to why patients in China behave as Zhang did. Presented here are several reasons, including society, history, morality and ideology, family, and education. Although all of these reasons do play a role, the patient's mindset and behavior is the most significant reason for a patient's reluctance to seek treatment or disclose his/her status. If the individual patient's mindset and behavior are not dealt with effectively, then HIV/AIDS can continue to spread and threaten additional lives and even the fabric of society. This paper analyzes the reasons why patients are hesitant to receive antiviral therapy, but this paper also suggests steps healthcare personnel can take to encourage patients to seek treatment. Such steps can save the lives of current patients with HIV/AIDS. In addition, sound public health measures and a rational approach to treatment are important to helping potential patients with HIV/AIDS.

  5. Sonic crystal acoustic switch device.

    PubMed

    Alagoz, Serkan; Alagoz, Baris Baykant

    2013-06-01

    This study reports a wave-controlled sonic crystal switch device that exhibits a destructive interference-based wave to wave reverse switching effect. By applying control waves, this acoustic device, composed of a two-dimensional square lattice sonic crystal block, reduces acoustic wave transmission from input to output. The finite difference time domain simulation and experimental results confirm the wave-to-wave reverse switching effect at the peak frequencies of the second band. The proposed sonic crystal switch prototype provides a contrast rate of 86% at 11.3 kHz frequency. This wave-to-wave switching effect is useful for controlling wave propagation for smart structure applications.

  6. Hybrid Vehicles

    DTIC Science & Technology

    2008-12-08

    hybrid electric vehicles typically contain potentially hazardous levels of electrical voltage or current. It is important to protect the operators...60740. ITOP 2-2-607(1)41 is used for tracked vehicles. 13 TOP 2-1-003 08 December 2008 Hybrid electric vehicles often employ much more

  7. Plasma opening switch

    DOEpatents

    Savage, Mark E.; Mendel, Jr., Clifford W.

    2001-01-01

    A command triggered plasma opening switch assembly using an amplification stage. The assembly surrounds a coaxial transmission line and has a main plasma opening switch (POS) close to the load and a trigger POS upstream from the main POS. The trigger POS establishes two different current pathways through the assembly depended on whether it has received a trigger current pulse. The initial pathway has both POS's with plasma between their anodes and cathodes to form a short across the transmission line and isolating the load. The final current pathway is formed when the trigger POS receives a trigger current pulse which energizes its fast coil to push the conductive plasma out from between its anode and cathode, allowing the main transmission line current to pass to the fast coil of the main POS, thus pushing its plasma out the way so as to establish a direct current pathway to the load.

  8. Future switching satellites

    NASA Technical Reports Server (NTRS)

    Campanella, S. Joseph; Pontano, Benjamin A.; Chalmers, Harvey

    1988-01-01

    Communications satellites of the future are likely to use much narrower beams in order to increase the uplink G/T and the downlink EIRP so that small earth terminals of the VSAT class can achieve full mesh connectivity. These satellites will need onboard switches to route traffic from originating upbeams to destination downbeams. This paper presents a new approach to accomplishing this rerouting using destination-directed packets that inherently carry the information needed to control the onboard switch connections and to adjust the traffic flow among the beams and the stations. The method also inherently provides channel multiplication and DAMA advantages which result in maximally efficient utilization of the space segment resource.

  9. Switched Matrix Accelerator

    SciTech Connect

    Whittum, David H

    2000-10-04

    We describe a new concept for a microwave circuit functioning as a charged-particle accelerator at mm-wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cyclic fatigue. The device provides acceleration for multiple bunches in parallel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a smooth transmission line model and a complementary treatment with a coupled-cavity simulation. We provide also an electromagnetic design for the accelerating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392. GHz. A critical element in the concept is a fast mm-wave switch suitable for operation at high-power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium.

  10. Optical fiber switch

    DOEpatents

    Early, James W.; Lester, Charles S.

    2002-01-01

    Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

  11. Cryogenic switched MOSFET characterization

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Both p channel and n channel enhancement mode MOSFETs can be readily switched on and off at temperatures as low as 2.8 K so that switch sampled readout of a VLWIR Ge:Ga focal plane is electronically possible. Noise levels as low as 100 rms electrons per sample (independent of sample rate) can be achieved using existing p channel MOSFETs, at overall rates up to 30,000 samples/second per multiplexed channel (e.g., 32 detectors at a rate of almost 1,000 frames/second). Run of the mill devices, including very low power dissipation n channel FETs would still permit noise levels of the order of 500 electrons/sample.

  12. The quantum cryptographic switch

    NASA Astrophysics Data System (ADS)

    Srinatha, N.; Omkar, S.; Srikanth, R.; Banerjee, Subhashish; Pathak, Anirban

    2014-01-01

    We illustrate the principle of a cryptographic switch for a quantum scenario, in which a third party (Charlie) can control to a continuously varying degree the amount of information the receiver (Bob) receives, after the sender (Alice) has sent her information through a quantum channel. Suppose Charlie transmits a Bell state to Alice and Bob. Alice uses dense coding to transmit two bits to Bob. Only if the 2-bit information corresponding to the choice of the Bell state is made available by Charlie to Bob can the latter recover Alice's information. By varying the amount of information Charlie gives, he can continuously alter the information recovered by Bob. The performance of the protocol as subjected to the squeezed generalized amplitude damping channel is considered. We also present a number of practical situations where a cryptographic switch would be of use.

  13. MULTIPLE SPARK GAP SWITCH

    DOEpatents

    Schofield, A.E.

    1958-07-22

    A multiple spark gap switch of unique construction is described which will permit controlled, simultaneous discharge of several capacitors into a load. The switch construction includes a disc electrode with a plurality of protuberances of generally convex shape on one surface. A firing electrode is insulatingly supponted In each of the electrode protuberances and extends substantially to the apex thereof. Individual electrodes are disposed on an insulating plate parallel with the disc electrode to form a number of spark gaps with the protuberances. These electrodes are each connected to a separate charged capacitor and when a voltage ls applied simultaneously between the trigger electrodes and the dlsc electrode, each spark gap fires to connect its capacitor to the disc electrode and a subsequent load.

  14. Many-Body Switches

    NASA Astrophysics Data System (ADS)

    MacDonald, Allan H.

    2014-03-01

    Most current electronic devices use gate voltages to switch individual electron transport channels or off. This architecture necessarily leads to operating voltages that are much larger than the temperature thermal energy, and places lower bounds on power consumption that are becoming. I will discuss strategies for achieving devices in which gates are used to collective many-electron states, in principle allowing charge transport to be switched by smaller voltage changes and both operating voltages and power consumption to reduced. I will specifically address devices based on the properties of itinerant electroninsulating magnetic systems, and devices based on bilayer exciton condensation. This work is based on work performed in collaboration with Sanjay Banerjee and Frank Register.

  15. Automatic switching matrix

    DOEpatents

    Schlecht, Martin F.; Kassakian, John G.; Caloggero, Anthony J.; Rhodes, Bruce; Otten, David; Rasmussen, Neil

    1982-01-01

    An automatic switching matrix that includes an apertured matrix board containing a matrix of wires that can be interconnected at each aperture. Each aperture has associated therewith a conductive pin which, when fully inserted into the associated aperture, effects electrical connection between the wires within that particular aperture. Means is provided for automatically inserting the pins in a determined pattern and for removing all the pins to permit other interconnecting patterns.

  16. Composite Material Switches

    NASA Technical Reports Server (NTRS)

    Javadi, Hamid (Inventor)

    2001-01-01

    A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

  17. CREE: Making the Switch

    SciTech Connect

    Grider, David; Palmer, John

    2014-03-06

    CREE, with the help of ARPA-E funding, has developed a Silicon Carbide (SIC) transistor which can be used to create solid state transformers capable of meeting the unique needs of the emerging smart grid. SIC transistors are different from common silicon computer chips in that they handle grid scale voltages with ease and their high frequency switching is well suited to the intermittent nature of renewable energy generation.

  18. CREE: Making the Switch

    ScienceCinema

    Grider, David; Palmer, John

    2016-07-12

    CREE, with the help of ARPA-E funding, has developed a Silicon Carbide (SIC) transistor which can be used to create solid state transformers capable of meeting the unique needs of the emerging smart grid. SIC transistors are different from common silicon computer chips in that they handle grid scale voltages with ease and their high frequency switching is well suited to the intermittent nature of renewable energy generation.

  19. Organic optical bistable switch

    NASA Astrophysics Data System (ADS)

    Xue, Jiangeng; Forrest, Stephen R.

    2003-01-01

    We demonstrate an organic optical bistable switch by integrating an efficient organic photodetector on top of a transparent electrophosphorescent organic light-emitting diode (TOLED). The bistability is achieved with an external field-effect transistor providing positive feedback. In the "LOW" state, the TOLED is off and the current in the photodetector is solely its dark current. In the "HIGH" state, the TOLED emits light that is directly coupled into the integrated photodetector through the transparent cathode. The photocurrent then is fed back to the TOLED, maintaining it in the HIGH state. The green electrophosphorescent material, fac tris(2-phenylpyridine) iridium [Ir(ppy)3] doped into a 4,4'-N,N'-dicarbazole-biphenyl host was used as the luminescent material in the TOLED, while alternating thin layers of copper phthalocyanine and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole were used as the active region of the organic photodetector. The circuit has a 3 dB bandwidth of 25 kHz, and can be switched between HIGH and LOW using pulses as narrow as 60 ns. The bistable switch can be both electrically and optically reset, making it a candidate for image-retaining displays (e.g., electronic paper) and other photonic logic applications. The integrated organic device also has broad use as a linear circuit element in applications such as automatic brightness control.

  20. Cygnus Diverter Switch Analysis

    SciTech Connect

    G. Corrow, M. Hansen, D. Henderson, C. Mitton et al.

    2008-02-01

    The Cygnus Dual Beam Radiographic Facility consists of two 2.25-MV, 60-kA, 50-ns x-ray sources fielded in an underground laboratory at the Nevada Test Site. The tests performed in this laboratory involve study of the dynamic properties of plutonium and are called subcritical experiments. From end-to-end, the Cygnus machines utilize the following components: Marx generator, water-filled pulse-forming line (PFL), waterfilled coaxial transmission line (WTL), 3-cell inductive voltage adder (IVA), and rod-pinch diode. The upstream WTL interface to the PFL is via a radial insulator with coaxial geometry. The downstream WTL terminates in a manifold where the center conductor splits into three lines which individually connect to each of the IVA cell inputs. There is an impedance mismatch at this juncture. It is a concern that a reflected pulse due to anomalous behavior in the IVA or diode might initiate breakdown upon arrival at the upstream PFL/WTL insulator. Therefore near the beginning of the WTL a radial diverter switch is installed to protect the insulator from over voltage and breakdown. The diverter has adjustable gap spacing, and an in-line aqueous-solution (sodium thiosulfate) resistor array for energy dissipation. There are capacitive voltage probes at both ends of the WTL and on the diverter switch. These voltage signals will be analyzed to determine diverter performance. Using this analysis the usefulness of the diverter switch will be evaluated.

  1. Ultrafast gas switching experiments

    NASA Astrophysics Data System (ADS)

    Frost, C. A.; Martin, T. H.; Patterson, P. E.; Rinehart, L. F.; Rohwein, G. J.; Roose, L. D.; Aurand, J. F.; Buttram, M. T.

    1993-06-01

    Recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less are described. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes less than 100 ps which can be used for ultrawideband radar systems, particle accelerators, laser drivers, bioelectromagnetic studies, electromagnetic effects testing, and for basic studies of gas breakdown physics. Pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to 1 kHz were produced and accurately measured. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than 1 nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and waveforms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and pressure. This technology was applied to practical systems driving ultrawideband radiating antennas and bounded wave simulators. A thyristor/pulse transformer based system using a highly overvolted cable switch was developed. This pulser driving a Sandia-designed TEM cell, provides an ultra wideband impulse with less than 200 ps risetime to the test object at a PRF greater than 1 kHz at grater tha n 100 kV/m E field.

  2. "Platform switching": serendipity.

    PubMed

    Kalavathy, N; Sridevi, J; Gehlot, Roshni; Kumar, Santosh

    2014-01-01

    Implant dentistry is the latest developing field in terms of clinical techniques, research, material science and oral rehabilitation. Extensive work is being done to improve the designing of implants in order to achieve better esthetics and function. The main drawback with respect to implant restoration is achieving good osseointegration along with satisfactory stress distribution, which in turn will improve the prognosis of implant prosthesis by reducing the crestal bone loss. Many concepts have been developed with reference to surface coating of implants, surgical techniques for implant placement, immediate and delayed loading, platform switching concept, etc. This article has made an attempt to review the concept of platform switching was in fact revealed accidentally due to the nonavailability of the abutment appropriate to the size of the implant placed. A few aspect of platform switching, an upcoming idea to reduce crestal bone loss have been covered. The various methods used for locating and preparing the data were done through textbooks, Google search and related articles.

  3. Ferroelectric switching of elastin

    PubMed Central

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-01-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 μC/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  4. Ultrafast gas switching experiments

    SciTech Connect

    Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D.; Aurand, J.F.; Buttram, M.T.

    1993-08-01

    We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes < 100 ps which can be used for ultrawideband radar systems, particle accelerators, laser drivers, bioelectromagnetic studies, electromagnetic effects testing, and for basic studies of gas breakdown physics. We have produced and accurately measured pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to 1 kHz. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than 1 nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and waveforms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and technology to practical systems antennas and bounded wave developed a thyristor/pulse transformer based system using a highly overvolted cable switch. This pulser driving a Sandia-designed TEM cell, provides an ultra wideband impulse with < 200 ps risetime to the test object at a PRF > Khz at > 100 kV/m E field.

  5. Ultrafast gas switching experiments

    SciTech Connect

    Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D.; Aurand, J.F.; Buttram, M.T.

    1996-11-01

    We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes < 100 ps which can be used for ultrawideband radar systems, particle accelerators, laser drivers, bioelectromagnetic studies, electromagnetic effects testing, and for basic studies of gas breakdown physics. We have produced and accurately measured pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to I kHz. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than I nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and wave forms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and pressure. We have applied this technology to practical systems driving ultrawideband radiating antennas and bounded wave simulators. For example, we have developed a thyristor/pulse transformer based system using a highly overvolted cable switch. This pulser driving a Sandia- designed TEM cell, provides an ultra wideband impulse with < 200 ps risetime to the test object at a PRF > 1 kHz at > 100 kV/m E field.

  6. High-performance multicasting schemes in optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Yuefeng; Liu, Xin; Zhang, Jie; Zhang, Min

    2009-11-01

    Current trends in communications indicate that multicasting is becoming increasingly popular and important in networking applications. Since multicasting can be supported more efficiently in optical domain by utilizing the inherent light-splitting capacity of optical devices, such as optical splitters, than by copying data in electronic domain, issues concerning running multicast sessions in the all-optical networks have received much attention in recent years. In this paper, different multicasting schemes and their performance in the Optical Packet Switched networks are investigated, including the parallel mode, serial mode, and hybrid mode multicasting schemes. Computer simulation results show that compared with the parallel-mode and serial-mode multicasting schemes, hybrid-mode multicasting scheme is the best way to deliver multicast sessions in the Optical Packet Switched networks due to its highest performance.

  7. THz bandwidth optical switching with carbon nanotube metamaterial.

    PubMed

    Nikolaenko, Andrey E; Papasimakis, Nikitas; Chipouline, Arkadi; De Angelis, Francesco; Di Fabrizio, Enzo; Zheludev, Nikolay I

    2012-03-12

    We provide the first demonstration of exceptional light-with-light optical switching performance of a carbon nanotube metamaterial - a hybrid nanostructure of a plasmonic metamaterial with semiconducting single-walled carbon nanotubes. A modulation depth of 10% in the near-IR with sub-500 fs response time is achieved with a pump fluence of just 10 μJ/cm², which is an order of magnitude lower than in previously reported artificial nanostructures. The improved switching characteristics of the carbon nanotube metamaterial are defined by an excitonic nonlinearity of carbon nanotubes resonantly enhanced by a concentration of local fields in the metamaterial. Since the spectral position of the excitonic response and metamaterial plasmonic resonance can be adjusted by using carbon nanotubes of different diameter and scaling of the metamaterial design, the giant nonlinear response of the hybrid metamaterial - in principle - can be engineered to cover the entire second and third telecom windows, from O- to U-band.

  8. Solid state switch for high reliability spacecraft use

    SciTech Connect

    Kamon, D.; Dalton, J.F.

    1995-12-31

    The drive to improve interplanetary spacecraft power system reliability and fault tolerance spurred JPL to develop a Solid State Power Switch (SSPS). JPL began the development of the SSPS in the late nineteen eighties to replace the traditional mechanical relay/fuse combination with high reliability solid state designs that provide distributed fault protection and load switching. The JPL design was driven by the high reliability, fault tolerant requirements of the Cassini mission to Saturn (late 1997 launch). The Cassini spacecraft will be the first JPL spacecraft to utilize a solid state device for power distribution. One hundred and ninety-two (192) SSPS hybrid units will be used to control numerous spacecraft loads. The system approach and design philosophy of the SSPS were previously reported at the 1994, 29th IECEC conference (Dalton, et al.). This paper describes the design and implementation of the flight qualified hybridized SSPS.

  9. Transcription-dependent R-loop formation at mammalian class switch sequences

    PubMed Central

    Tracy, Robert B.; Lieber, Michael R.

    2000-01-01

    Immunoglobulin class switching is mediated by recombination between switch sequences located immediately upstream of the immunoglobulin constant heavy chain genes. Targeting of recombination to particular switch sequences is associated temporally with transcription through these regions. We recently have provided evidence for inducible and stable RNA–DNA hybrid formation at switch sequences in the mouse genome that are mechanistically important for class switching in vivo. Here, we define in vitro the precise configuration of the DNA and RNA strands within this hybrid structure at the Sμ, Sγ3 and Sγ2b mouse switch sequences. We find that the G–rich (non-template) DNA strand of each switch sequence is hypersensitive to probes throughout much of its length, while the C–rich (template) DNA strand is essentially resistant. These results demonstrate formation of an R–loop, whereby the G–rich RNA strand forms a stable heteroduplex with its C–rich DNA strand counterpart, and the G–rich DNA strand exists primarily in a single-stranded state. We propose that the organized structure of the R–loop is essential for targeting the class switch recombination machinery to these sequences. PMID:10698946

  10. Photochromic mesoporous hybrid coatings

    NASA Astrophysics Data System (ADS)

    Raboin, L.; Matheron, M.; Gacoin, T.; Boilot, J.-P.

    2008-09-01

    Spirooxazine (SO) photochromic molecules were trapped in sol-gel matrices. In order to increase the colourability and improve mechanical properties of sol-gel photochromic films, we present an original strategy in which SO photochromic molecules were dispersed in mesoporous organized films using the impregnation technique. Well-ordered organosilicate mesoporous coatings with the 3D-hexagonal symmetry were prepared by the sol-gel technique. These robust mesoporous films, which contain high amounts of hydrophobic methyl groups at the pore surface, offer optimized environments for photochromic dyes dispersed by impregnation technique. After impregnation by a spirooxazine solution, the photochromic response is only slightly slower when compared with mesostructured or soft sol-gel matrices, showing that mesoporous organized hybrid matrix are good host for photochromic dyes. Moreover, the molecular loading in films is easily adjustable in a large range using multi-impregnation procedure and increasing the film thickness leading to coatings for optical switching devices.

  11. Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration

    SciTech Connect

    Loubriel, G.M.; Mar, A.; Hamil, R.A.; Zutavern, F.J.; Helgeson, W.D.

    1997-12-01

    This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered with small amounts of laser light. The specific goals of the LDRD were to demonstrate: (1) that small laser diode arrays that are potential candidates for laser-switch integration will indeed trigger the PCSS switch, and (2) that high gain GaAs switches can be used to trigger optical Q-switches in lasers such as the lasers to be used in the X-1 Advanced Radiation Source and the laser used for direct optical initiation (DOI) of explosives. The technology developed with this LDRD is now the prime candidate for triggering the Q switch in the multiple lasers in the laser trigger system of the X-1 Advanced Radiation Source and may be utilized in other accelerators. As part of the LDRD we developed a commercial supplier. To study laser/switch integration we tested triggering the high gain GaAs switches with: edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs), and transverse junction stripe (TJS) lasers. The first two types of lasers (edge emitting and VCSELs) did activate the PCSS but are harder to integrate with the PCSS for a compact package. The US lasers, while easier to integrate with the switch, did not trigger the PCSS at the US laser power levels we used. The PCSS was used to activate the Q-switch of the compact laser to be used in the X-1 Advanced Radiation Source.

  12. Bindi tattoo on forehead: success with modified R-20 technique using low fluence q-switched nd yag laser: a case report.

    PubMed

    Zawar, Vijay; Sarda, Aarti; De, Abhishek

    2014-01-01

    Bindi tattoo on the forehead, is one of the cultural practice in Indian women from rural areas. Many patients are not pleased with the appearance of their tattoo and thus seek removal. The development of quality-switched lasers has revolutionized the removal of unwanted tattoos. However, despite multiple treatment sessions, the efficacy is often found to be limited. We herein report a case of green-blue bindi tattoo which failed to clear after 8 sessions of Q-switched Nd YAG laser. The tattoo significantly cleared with R-20 method using low fluence Q-switched Nd YAG Laser. R-20 technique seems to be an effective method of tattoo removal and might be a boon for patients who are reluctant to pursue laser treatment because of fear of expenditure, side effects and uncertainty of result. We report efficacy of R-20 technique for a bindi tattoo on forehead.

  13. Bindi Tattoo on Forehead: Success with Modified R-20 Technique Using Low Fluence Q-Switched Nd Yag Laser: A Case Report

    PubMed Central

    Zawar, Vijay; Sarda, Aarti; De, Abhishek

    2014-01-01

    Bindi tattoo on the forehead, is one of the cultural practice in Indian women from rural areas. Many patients are not pleased with the appearance of their tattoo and thus seek removal. The development of quality-switched lasers has revolutionized the removal of unwanted tattoos. However, despite multiple treatment sessions, the efficacy is often found to be limited. We herein report a case of green-blue bindi tattoo which failed to clear after 8 sessions of Q-switched Nd YAG laser. The tattoo significantly cleared with R-20 method using low fluence Q-switched Nd YAG Laser. R-20 technique seems to be an effective method of tattoo removal and might be a boon for patients who are reluctant to pursue laser treatment because of fear of expenditure, side effects and uncertainty of result. We report efficacy of R-20 technique for a bindi tattoo on forehead. PMID:24761103

  14. Third-order leader-following consensus with circumstance noise under impulsive and switching control

    NASA Astrophysics Data System (ADS)

    Sun, Mei; Han, Dun; Li, Dandan; Jia, Qiang; Wang, Yaqi

    2014-02-01

    This research is aimed at investigating the leader-follower problem of third-order multi-agent with noise perturbation over fixed network under impulsive and switching control. Based on stochastic differential equation theory and hybrid control theory, effective impulsive and switching controllers are proposed, and the sufficient conditions for reaching multi-agent leader-following consensus are acquired. Numerical simulations verify the validity of the theoretical research results.

  15. Ultrafast Silicon-based Modulators using Optical Switching of Vanadium Dioxide

    DTIC Science & Technology

    2014-12-04

    intensity. Ultrafast, all-optical switching at the nanosecond time scale is then demonstrated by using a pulsed nanosecond laser for excitation. Ultrafast...the excitation laser ) with optical modulation depths in excess of 7 dB from high-bandwidth (>100 GHz) hybrid structures. Record low switching times...ring waveguide width is ~500nm while the bus waveguide width is slightly reduced to ~400nm to promote better phase matching. A coupling gap of ~75nm

  16. Switch on or switch off: an optical DNA sensor based on poly(p-phenylenevinylene) grafted magnetic beads.

    PubMed

    Srinivas, Anupama R Gulur; Peng, Hui; Barker, David; Travas-Sejdic, Jadranka

    2012-05-15

    There has been an enormous demand for commercial label-free DNA sensors in a diverse range of fields including pre-emptive medicine, diagnostics, environmental monitoring, and food industry. Addressing the need for sensitive, selective and facile DNA sensors, we demonstrate a novel switch on/off sensor design that utilizes sandwich hybridization between photoluminescent anionic conjugated polyelectrolyte (CPE) bound captureprobe coated onto magnetic beads, target and the signaling probe. The hybridization-readout in our sensor was monitored by either fluorescence resonance energy transfer (FRET, switch-on) or superquenching (switch-off) depending on the type of signaling probe used. Moreover recent designs that utilize beads for sensing DNA have been limited towards using electrostatic interactions or intercalation of dyes to observe FRET. To our knowledge this is the first report of a switch on/off sensor utilizing either FRET or superquenching thus providing flexibility for future development of such rapid, facile and sensitive DNA sensors. The FRET-based sensor was investigated by optimizing the reaction parameters and selectivity. A low detection limit of 240 fmol in 2 mL of SSC buffer was achieved.

  17. Why are Korean American Physicians Reluctant to Recommend Colorectal Cancer Screening to Korean American Patients? Exploratory Interview Findings

    PubMed Central

    Maxwell, Annette E.; Rick, Albert J.; Cha, Jennifer; Bastani, Roshan

    2009-01-01

    Background Korean Americans have one of the lowest screening rates for colorectal cancer. Although physician recommendation is one of the most important predictors of cancer screening across populations, only few Korean American patients receive such a recommendation. Methods We interviewed 14 Korean American physicians in Los Angeles area who primarily serve Korean Americans to explore why they are reluctant to recommend colorectal cancer screening to their Korean patients. Results Physicians identified barriers attributable to themselves (i.e., lack of knowledge, fear of medicolegal liability), their patients (i.e., patient’s unfamiliarity with the concept of screening), and the health care system (i.e., lack of referral network, poor reimbursement). Discussion Our results suggest the need for multi-faceted interventions directed at the physicians, their patients, and the health care system. Further research is needed to validate our results and to assess the extent to which they apply to physicians from other racial/ethnic groups. PMID:18607728

  18. [End-of-life decisions and reluctant treatment of newborns on the borderline of viability in the Netherlands].

    PubMed

    Kollée, L A A

    2005-09-10

    End-of-life decisions are taken in the majority of deaths below one year of age, especially in neonatal intensive-care units. In the Netherlands, the frequency of such decisions has not increased in recent years. Intentional termination of life occurred in 1% of the deaths, which would be about 10 cases each year. However, only 3 such cases are reported to the public prosecutor for review by the responsible physician. Proposals from the government to facilitate reporting of such cases are awaited. Dutch neonatologists are reluctant to administer full neonatal intensive care to extremely preterm infants. Currently, the policy regarding antenatal referral and treatment of extremely preterm infants is being re-evaluated by obstetricians and neonatologists. Behind the stable frequency of end-of-life decisions, difficult ethical issues remain to be solved.

  19. Community mental health provider reluctance to provide pharmacotherapy may be a barrier to addressing perinatal depression: a preliminary study.

    PubMed

    Byatt, Nancy; Biebel, Kathleen; Debordes-Jackson, Gifty; Lundquist, Rebecca S; Moore Simas, Tiffany A; Weinreb, Linda; Ziedonis, Douglas

    2013-06-01

    This is the first study evaluating obstetrics and gynecology (OB/Gyn) provider and staff perceptions of barriers to accessing pharmacotherapy for perinatal depression outside the obstetric setting. Four, 90 min focus groups were conducted with OB/Gyn physicians, advance practice nurses, and support and nursing staff (n = 28). Data were analyzed with a grounded theory approach. Participants perceived that community mental health providers and pharmacists often do not want to participate in pharmacotherapy for perinatal women. Participants believed the solution is training for community mental health providers in the risks and benefits of pharmacotherapy for perinatal depression and improved communication between OB/Gyn's and community mental health providers. Community mental health provider and pharmacist reluctance to provide pharmacotherapy hinders OB/Gyn's perceived ability to address perinatal depression. Community mental health provider and pharmacist training are needed to mitigate precipitous discontinuation of treatment and to improve access to pharmacotherapy for perinatal women.

  20. Rosacea Fulminans Precipitated by Acute Stress: A Case Report Describing an Integrative Approach for a Patient Reluctant to Use Isotretinoin

    PubMed Central

    Veerkamp, Patrick; Mousdicas, Nico; Bednarek, Robert

    2016-01-01

    Context Rosacea fulminans is a rare skin disorder with a multifactorial etiology. Stress is one of the common precipitating factors of this condition but is not often targeted in treatment. Isotretinoin is considered part of the first-line therapy for this condition but, in cases where its use is restricted, other therapeutic interventions as part of an integrative approach may be effective. Patient Concerns A 38-y-old female presented with rosacea fulminans brought on by an acutely stressful event. After multiple failed therapies, she experienced resolution of her symptoms with a combination of systemic corticosteroids, antibiotics, diet modification, and stress reduction, with the treatment of stress playing a significant role. Conclusions Stress management and diet modification are key adjunctive therapies in the treatment of rosacea fulminans and need to be addressed more often in treatment. In cases where patients are reluctant or unable to take isotretinoin, an integrative approach may be effective in achieving symptomatic improvement. PMID:28223895