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Sample records for hybrid switched reluctance

  1. Switched reluctance drives for electric and hybrid vehicles

    SciTech Connect

    Yelne, A.; Heitner, K.

    1996-09-01

    Several characteristics of switched reluctance drive (SRD) systems, such as high torque density, high efficiency, fault tolerant operation, and simplicity of construction make them potentially attractive for electric vehicle (EV) traction applications. This paper presents the results of an evaluation of the design and performance aspects of switched reluctance (SR) drive technology, with special emphasis on EV traction. Rotor/stator design and construction, choice of materials, electronic component selection, and production costs are some of the important design and manufacturing issues analyzed. Performance characteristics such as drive control, torque ripple and noise, fault tolerance, efficiency, torque-speed characteristics, and regeneration are discussed. Several of these design and manufacturing issues are compared with similar issues for drive systems currently used for electric vehicle applications. The results of the assessment show several benefits of applying SR motors in EV drives, including, high efficiency and excellent torque characteristics over a wide speed range, rugged and fault tolerant design, and the potential for economic mass production. However, further work is necessary and is being applied to improve torque ripple, noise and other drive systems design issues. The performance of an EV-suitable SRD and three competitive EV drive systems were compared by modeling these drives using SIMPLEV, the electric and hybrid vehicle simulation software. Each of the four drives was modeled to provide 45 kW to a BMW-E1 electric vehicle over the LA-92 driving cycle. The results suggest that the performance of SRDs is comparable to other state-of-the-art EV drive technologies.

  2. Bearingless switched reluctance motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R. (Inventor)

    2004-01-01

    A switched reluctance motor has a stator with a first set of poles directed toward levitating a rotor horizontally within the stator. A disc shaped portion of a hybrid rotor is affected by the change in flux relative to the current provided at these levitation poles. A processor senses the position of the rotor and changes the flux to move the rotor toward center of the stator. A second set of poles of the stator are utilized to impart torque upon a second portion of the rotor. These second set of poles are driven in a traditional switched reluctance manner by the processor.

  3. 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.

  4. 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.

  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. 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

  7. 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.

  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. PD control for robot manipulators actuated by switched reluctance motors

    NASA Astrophysics Data System (ADS)

    Hernández-Guzmán, Victor M.; Carrillo-Serrano, Roberto V.; Silva-Ortigoza, Ramón

    2013-03-01

    This article is concerned with position regulation in direct-drive n degrees of freedom rigid robots equipped only with revolute joints when actuated by switched reluctance motors. Our controller represents an extension to this case of a previous work in the literature which was proposed for a single-switched reluctance motor when moving a simple linear mechanical load. We show how to avoid a singularity present in such a previous controller. We also introduce some simplifications since the number of terms to be fedback is smaller. Further, a linear proportional inner electric current loop is included instead of a velocity dependent one.

  14. 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.

  15. 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.

  16. A new energy optimizing control strategy for switched reluctance motors

    SciTech Connect

    Kjaer, P.C.; Nielsen, P.

    1995-09-01

    This paper describes a new and machine-independent method to minimize the energy consumption of a speed controlled Switched Reluctance Motor (SRM). The control strategy is to vary the duty cycle of the applied dc voltage in order to obtain the desired speed quickly and when operating in steady-state vary the turn-on angle ({alpha}{sub on}) of the phase voltage to minimize the energy consumption. The power flow is measured in the dc-link and used to control the turn-on angle. Simulations carried out on a three-phase 6/4 pole SRM justify the algorithm and the physical implementation in a Siemens SAB 80C517A microcontroller is described. Measurements on two different load systems show it is possible to minimize the energy consumption on-line in a speed controlled Switched Reluctance Motor without losing the dynamic performance. A comparison with an ordinary mode-shift controlled SRM shows more than an 8% increase in overall efficiency for some operation points. The algorithm is fully applicable to other Switched Reluctance Motors at other power levels or with other pole configurations.

  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. Research on a novel Rotor Structure Switched Reluctance Motor

    NASA Astrophysics Data System (ADS)

    Zeng, Lingquan; Yu, Haiwei

    The paper proposes a novel switched reluctance motor with improved rotor structure, in which the segment core is embedded in aluminum rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. The effect of design parameters on the average torque is investigated using the finite element method. Comparison with conventional VR type SRM and segment type SRM without conductive metal construction rotor show the proposed novel SRM has advantages in the torque performances and the vibration and noise characteristics. The performance is also investigated by experiment.

  19. 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.

  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. Flux-linkage characteristics of switched reluctance motor

    SciTech Connect

    Ramanarayanan, V.; Venkatesha, L.; Panda, D.

    1995-12-31

    An important requirement in modeling of switched reluctance motor (SRM) is the knowledge of its flux-linkage characteristics. Idealization of the flux-linkage characteristics will result in a model which cannot predict the performance of the machine with sufficient accuracy. It is necessary therefore to determine flux-linkage characteristics as closely as possible. In this paper, the method of finding the flux-linkage characteristics is explained. The same is demonstrated on a commercially available 4 KW, 8/6 pole OULTON SRM. The validity of the test result is checked by computing the static torque characteristics based on the measured flux-linkage characteristics and comparing it with the experimentally measured static torque characteristics. The sources of measurement error are discussed.

  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. A modified split-supply switched-reluctance drive inverter

    SciTech Connect

    Chan, S.; Omar, A.M.

    1995-12-31

    This paper describes the application of a new simple voltage-boosting feature to split-supply SR (switched-reluctance) inverter. As its name implies, the SR motor always operates in switching mode and has distinct motoring and generating rotor angular regions. The effectiveness of the energy conversion process of SR motor depends basically on the ability of its inverter to inject adequate current during the positive-torque angular region and to reduce the current to negligible value during negative-torque angular region. The modified inverter effectively generates boost voltages for accelerating current build-up and decay and hence enhances the performance of SR drives. Benefits of the added boosting include: higher average current, better energy recovery during commutation and a wider feasible speed range. This paper will assess the implications of the boost feature on inverter cost and performance. A time-stepping simulation procedure which includes the modelling of current overlapping between phases will be presented together with simulation results.

  4. 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

  5. Novel rotor position estimation technique for switched reluctance motor (SRM)

    NASA Astrophysics Data System (ADS)

    Moradi, Hassan; Afjei, Ebrahim

    2011-09-01

    This article presents a new and novel method which is designed to detect the rotor position at standstill and at low speeds in switched reluctance motor. Since the inductance parameter plays a significant role both in the steady state and in the dynamic characteristics of an electromagnetic device, the rotor position can be determined using inductance bridge systems to measure unknown inductance and resistance values. In this method we use motor winding in Maxwell-Wien Bridge, with the standard capacitor and the resistor in parallel with it adjusted to achieve balance in an aligned position when the maximum inductance occurs. The supply voltage, in conjunction with the drive transistor, produces short pulses for this AC bridge. The condition of the balanced bridge v 0 = 0 leads to the relation between the impedances of the bridge branches. The phase inductance varies with the rotor position. Therefore the motor goes into an unaligned position and the Maxwell-Wien Bridge goes into an unbalanced condition thus causing variation in the state of the bridge output. It then continues to sense the rotor position with the motor running by applying the same procedure, but only to the un-energised phases winding. The simulation and experimentally obtained results demonstrate the feasibility and practicability of this method.

  6. A new integrated controller for switched reluctance motor

    SciTech Connect

    Hossain, A.; Ahmed, A.

    1995-12-31

    The interest in switched reluctance motors (SRMs) have increased significantly in recent years, as these motors have found wide applications in industry as a possible alternative to adjustable speed AC and DC drives for many commercial applications. The simple construction and low cost of the SRM have made it an attractive candidate for replacing adjustable speed drives in automobile, aerospace, manufacturing and consumer product. Smooth operation and control of the SRM greatly depend on the external control unit. Instead of using a traditional digital controller with discrete devices, the authors have designed and fabricated a single chip logic controller for controlling torque and speed of an SRM. They have used Programmable Logic Device (PLD) to implement the digital logic coupled with a power controller. They have described the operational logic in the form of a block diagram and from there they have derived the controller logic. Initial testing of the controller for a four-phase SRM drive has been completed. Thorough testing and further research are in progress.

  7. Short flux paths optimize the efficiency of a 5-phase switched reluctance drive

    SciTech Connect

    Michaelides, A.; Pollock, C.

    1995-12-31

    A new configuration of switched reluctance drive is proposed in which the windings of a 5-phase motor are configured to encourage short flux paths within the motor. The 5-phase prototype motor can be fed from a new power converter which uses only six switching devices in a shared switch configuration. Experimental results demonstrate that the 5-phase prototype achieves higher efficiency than prior arc switched reluctance and induction drives constructed in the same frame size, and with the benefit of the new electronic circuit it is very cost effective.

  8. Novel tubular switched reluctance motor with double excitation windings: Design, modeling, and experiments

    NASA Astrophysics Data System (ADS)

    Yan, Liang; Li, Wei; Jiao, Zongxia; Chen, I.-Ming

    2015-12-01

    The space utilization of linear switched reluctance machine is relatively low, which unavoidably constrains the improvement of system output performance. The objective of this paper is to propose a novel tubular linear switched reluctance motor with double excitation windings. The employment of double excitation helps to increase the electromagnetic force of the system. Furthermore, the installation of windings on both stator and mover can make the structure more compact and increase the system force density. The design concept and operating principle are presented. Following that, the major structure parameters of the system are determined. Subsequently, electromagnetic force and reluctance are formulated analytically based on equivalent magnetic circuits, and the result is validated with numerical computation. Then, a research prototype is developed, and experiments are conducted on the system output performance. It shows that the proposed design of electric linear machine can achieve higher thrust force compared with conventional linear switched reluctance machines.

  9. Novel tubular switched reluctance motor with double excitation windings: Design, modeling, and experiments.

    PubMed

    Yan, Liang; Li, Wei; Jiao, Zongxia; Chen, I-Ming

    2015-12-01

    The space utilization of linear switched reluctance machine is relatively low, which unavoidably constrains the improvement of system output performance. The objective of this paper is to propose a novel tubular linear switched reluctance motor with double excitation windings. The employment of double excitation helps to increase the electromagnetic force of the system. Furthermore, the installation of windings on both stator and mover can make the structure more compact and increase the system force density. The design concept and operating principle are presented. Following that, the major structure parameters of the system are determined. Subsequently, electromagnetic force and reluctance are formulated analytically based on equivalent magnetic circuits, and the result is validated with numerical computation. Then, a research prototype is developed, and experiments are conducted on the system output performance. It shows that the proposed design of electric linear machine can achieve higher thrust force compared with conventional linear switched reluctance machines. PMID:26724063

  10. 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.

  11. Dual-decay converter for switched reluctance motor drives in low-voltage applications

    SciTech Connect

    Ehsani, Mehrdad; Husain, Iqbal; Ramani, K.R. . Dept. of Electrical Engineering); Galloway, J.H. )

    1993-04-01

    A modified converter topology for star-connected switched reluctance motors suitable for low-voltage applications is proposed in this paper. A dual time constant freewheeling circuit has been designed to improve the drive performance and efficiency over a wide range of speeds. The different modes of operation of the converter are discussed, and a comparison is made with other converter configurations.

  12. Performance of a high-speed switched reluctance starter/generator system using electronic position sensing

    SciTech Connect

    Jones, S.R.; Drager, B.T.

    1995-12-31

    A switched reluctance machine based system, whether a motor drive or a starter/generator, requires the rotor position to be determined to commutate at the correct instants. This paper compares the performance of a high-speed switched reluctance starter/generator (SR S/G) system when operating with a resolver to the performance when operating resolverless, or sensorless, using an electronic position sensing (EPS) subsystem for rotor position estimation. A brief overview of the SR S/G system is given, followed by the approach for sensorless system operation. Test results are given, and system efficiency is compared, for both approaches when operating both as a starter and as a generator. Minimal difference is seen in system efficiency, with peaks at over 75% for start-mode and at over 79% for generate mode, for both resolver-based and sensorless operation.

  13. Modeling and design optimization of switched reluctance machine by boundary element analysis and simulation

    SciTech Connect

    Tang, Y.; Kline, J.A. Sr.

    1996-12-01

    Nonlinear boundary element analysis provides a more accurate and detailing tool for the design of switched reluctance machines, than the conventional equivalent-circuit methods. Design optimization through more detailed analysis and simulation can reduce development and prototyping costs and time to market. Firstly, magnetic field modeling of an industrial switched reluctance machine by boundary element method is reported in this paper. Secondly, performance prediction and dynamic simulation of motor and control design are presented. Thirdly, magnetic forces that cause noise and vibration are studied, to include the effects of motor and control design variations on noise in the design process. Testing of the motor in NEMA 215-Frame size is carried out to verify the accuracy of modeling and simulation.

  14. Speed control of switched reluctance motor using sliding mode control strategy

    SciTech Connect

    John, G.; Eastham, A.R.

    1995-12-31

    A robust speed drive system for a switched reluctance motor (SRM) using sliding mode control strategy (SLMC) is presented. After reviewing the operation of an SRM drive, a SLMC based scheme is formulated to control the drive speed. The scheme is implemented using a micro-controller and a high resolution position sensor. The parameter insensitive characteristics are demonstrated through computer simulations and experimental verification.

  15. 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.

  16. An analysis and an operating method of switched reluctance motors based on a simple inductance representation

    SciTech Connect

    Chiba, Akira; Fukao, Tadashi

    1995-12-31

    In this paper, a mathematical analysis based on a simple model is carried out. The operating characteristics of switched reluctance motors fed by square waveform voltage are analyzed. Inductance variations with respect to the rotor rotational position is approximated with only a sinusoidal function and a constant. Square waveform voltage is approximated by a fundamental component only. Based on this simple representation, it is possible to analyze operating characteristics mathematically in normalized planes and to derive a general control method. It is found that there exists a particular voltage phase angle which realizes the maximum output per current. It was also found that the maximum output per voltage can be achieved at the another particular voltage phase angle. These characteristics are found to be very similar to those of synchronous reluctance motors. As a result of the analysis, an efficient operating method is proposed. These results are confirmed by a 6,000 r/min., 2kW prototype machine.

  17. 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.

  18. Design trends and trade-offs for sensorless operation of switched reluctance motor drives

    SciTech Connect

    Perl, T.; Husain, I.; Elbuluk, M.

    1995-12-31

    The aligned to unaligned phase inductance ratio and the number of stator and rotor poles strongly affect the resolution of indirect rotor position sensing methods for switched reluctance motor (SRM) drives. A higher inductance ratio increases the resolution, while higher number of phases increases the available sampling window for indirect position sensing. However, these requirements are conflicting design criteria for an SRM. In this paper, the design considerations and trade-offs for sensorless SRM drives are analyzed by computer simulations. The existing indirect position sensing methods and their applicability for various SRM drives are also discussed.

  19. Advantages of switched reluctance motor applications to EV and HEV: Design and control issues

    SciTech Connect

    Rahman, K.M.; Fahimi, B.; Suresh, G.; Rajarathnam, A.V.; Ehsani, M.

    2000-02-01

    Land vehicles need their drivetrain to operate entirely in constant power in order to meet their operational constraints, such as initial acceleration and gradability, with minimum power rating. The internal combustion engine (ICE) is inappropriate for producing this torque-speed profile. Therefore, multiple gear transmission is necessary with the ICE in a vehicle. Some electric machines, if designed and controlled appropriately, are capable of producing an extended constant power range. The purpose of this paper is to investigate the capabilities of the switched reluctance motor (SRM) for electric vehicle and hybrid electric vehicle applications. This investigation will be carried out in two steps. The first step involves the machine design and the finite-element analysis to obtain the static characteristic of the motor. In the second step, the finite-element field solutions are used in the development of a nonlinear model to investigate the dynamic performance of the designed motor. Several 8-6 and 6-4 SRM geometries will be investigated. Effects of different stator and rotor pole widths and pole heights on the steady state as well as on the dynamic performance of the motor will be studied. The air gap for each motor will be made as small as manufacturally possible. The aspects of performance to be compared for each design motor are: (1) the range of the constant power operation; (2) drive efficiency in this extended constant power range; (3) the power factor in this operational range; and (4) the short time overload capability. The first performance index defines the rated power of the motor. The longer the constant power range, the lower is the power rating for the same vehicle performance. In the high-speed operation of the SRM, there will be considerable phase overlapping. Hence, thicker back iron than usual might be needed to prevent the back iron from saturating. However, since flux peaking of each phase occurs at different rotor positions, the phase

  20. Energy-efficient C-dump converters for switched reluctance motors

    SciTech Connect

    Mir, S.; Husain, I.; Elbuluk, M.E.

    1997-09-01

    Two energy-efficient converter topologies, derived from the conventional C-dump converter, are proposed for switched reluctance motor (SRM) drives. The proposed topologies overcome the limitations of the conventional C-dump converter, and could reduce the overall cost of the SRM drive. The voltage ratings of the dump capacitor and some of the switching devices in the proposed converters are reduced to the supply voltage (V{sub dc}) level compared to twice the supply voltage (2V{sub dc}) in the conventional C-dump converter. Also, the size of the dump inductor is considerably reduced. The converters have simple control requirements, and allow the motor phase current to freewheel during chopping mode. Simulation and experimental results of the converters are presented and discussed.

  1. A very high speed switched-reluctance starter-generator for aircraft engine applications

    NASA Astrophysics Data System (ADS)

    MacMinn, Stephen R.; Jones, William D.

    An electric direct-drive gearless starter-generator has been designed and built for an aircraft engine application. The system is based on a switched-reluctance motor, which was chosen for its simplicity, robustness, high-speed capability, and efficiency. The overall system configuration and the design of the switched-reluctance motor and its solid-state power converter are described. When operating as engine starter, the motor produces torque to spin the engine up to its light-off speed. Following light-off, the motor continues to produce torque to assist the engine in accelerating to idle speed. When the engine is running, the machine generates electrical power to supply engine and vehicle loads up to a peak operating speed of 50,000 rev/min. Key issues in the machine design are reliability, high speed, power density, and cost. Test results have verified that the system can meet the torque and generated-power requirements over its entire operating range.

  2. Vibration modes and acoustic noise in a 4-phase switched reluctance motor

    SciTech Connect

    Colby, R.S.; Mottier, F.; Miller, T.J.E.

    1995-12-31

    Acoustic noise in the switched reluctance motor is caused primarily by the deformation of the stator lamination stack. Acoustic noise is most severe when the periodic excitation of the SRM phases excites a natural vibration mode of the stack. The natural vibration modes and frequencies of a 4-phase, 8/6 switched reluctance motor are examined. Structural finite element analysis is used to compute the natural modes and frequencies. Impulse tests on the stator stack verify the calculations and show which modes are excited. Heuristic arguments are developed to predict the operating conditions that will excite the natural modes. Measurement of vibration while the machine is under load shows which operating conditions excite the natural modes and verifies the predictions. An approximate formula is derived to predict the frequency of the fundamental vibration mode in terms of lamination dimensions and material properties. The formula is validated by comparison with finite element calculations for several laminations, and hence is shown to be useful in design trade-off studies.

  3. Vibration effect and control of In-Wheel Switched Reluctance Motor for electric vehicle

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Li, Yinong; Huang, Jingying; Zhang, Nong

    2015-03-01

    The Switched Reluctance Motor (SRM) processes favorable driving capacity and great application potential in In-Wheel Motor (IWM) Electric Vehicle (EV). However vibration and noise problems are always the disadvantages of SRM. This paper investigates the vibration and noise issues and corresponding control methodology for the IWM application of SRM. By utilizing the analytical Fourier fitting method, a convenience method for modeling In-Wheel Switched Reluctance Motor (IW SRM) is proposed and the characteristics of the unbalanced residual lateral force related to vibration excitation are analyzed. Then the dynamic negative effect of IW SRM on vehicle is analyzed with a quarter driving and vibration vehicle model. It is found that the vertical shock occurs under the vehicle starting condition and high frequency force excitation exists under the constant speed condition. To address these issues, corresponding control methods are proposed, modified and compared. The proposed combined vibration feedback control of current chopping with PWM can effectively reduce the SRM residual force and ensure the required vehicle speed, though some slight low frequency forces are induced.

  4. 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.

  5. 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.

  6. Input Power Quality Improvement in Switched Reluctance Motor Drive using Minnesota Rectifier

    NASA Astrophysics Data System (ADS)

    Singh, B.; Rajesh, M.

    2013-09-01

    This paper deals with an input power quality improvement in a midpoint converter based switched reluctance motor (SRM) drive at ac mains using Minnesota rectifier. Normally a midpoint converter is used as a power converter for SRM drive. Conventionally three phase ac mains fed bridge rectifier is used as a dc source to feed this power converter which produces high content of harmonics at ac mains with a very low power factor. The proposed Minnesota rectifier with a midpoint converter fed SRM drive improves the power factor at ac mains with low current harmonics. This method provides constant dc link voltage and balanced capacitor voltages of the midpoint converter. The Minnesota rectifier fed SRM drive is modelled and its performance is simulated in Matlab/Simulink environment. The performance of Minnesota rectifier is compared with a conventional bridge topology for SRM drive to demonstrate improved power quality at ac mains.

  7. Switched reluctance motor with magnetic slot wedges for automotive traction application

    NASA Astrophysics Data System (ADS)

    Belhadi, M.'Hamed; Krebs, Guillaume; Marchand, Claude; Hannoun, Hala; Mininger, Xavier

    2015-12-01

    The switched reluctance motor (SRM) is very attractive because of its many advantages especially in electric vehicle (EV). However, it presents two major drawbacks: torque ripples and stator vibrations. These phenomena are the cause of a disturbing noise. In order to reduce the torque ripples and the radial force (main cause of the stator vibrations), one solution is to add magnetic slot wedges. In this paper, a SRM with wedges is compared to the conventional one including some static and dynamic features. First, field lines, magnetization curves and static torques are discussed. Secondly, torque-speed curves, harmonic analyzes and cartographies with minimum ripples are compared. The last includes several operating points (speed-torque) in steady state.

  8. Design and implementation of sensorless techniques for switched reluctance drive systems

    NASA Astrophysics Data System (ADS)

    Liu, Tian-Hua; Chen, Ching-Guo

    2010-09-01

    This article proposes two different methods for estimating the shaft position for a switched reluctance motor (SRM). Method 1 uses the self-inductance estimation technique to obtain the rotor position. First, by on-line measuring the slope of the stator current and compensating for the back electromotive force (EMF) effect, the self-inductance of the SRM can be detected. Then, the shaft position of the motor can be estimated according to the self-inductance. Method 2, on the other hand, uses the phase-locked loop technique to generate high-frequency signals. These signals can be used to estimate the shaft position of the SRM. The two proposed methods are compared and discussed in the article. Several experimental results are shown to validate the theoretical analysis. The adjustable speed range of the system is from 10 to 3000 rpm. Additionally, the proposed drive system can automatically start from a standstill to a setting speed.

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

    NASA Astrophysics Data System (ADS)

    Rishab, Paudel; Ishikawa, Hiroki; Naitoh, Haruo

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

  10. Multi-Objective Optimal Design of Switch Reluctance Motors Using Adaptive Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Rashidi, Mehran; Rashidi, Farzan

    In this paper a design methodology based on multi objective genetic algorithm (MOGA) is presented to design the switched reluctance motors with multiple conflicting objectives such as efficiency, power factor, full load torque, and full load current, specified dimension, weight of cooper and iron and also manufacturing cost. The optimally designed motor is compared with an industrial motor having the same ratings. Results verify that the proposed method gives better performance for the multi-objective optimization problems. The results of optimal design show the reduction in the specified dimension, weight and manufacturing cost, and the improvement in the power factor, full load torque, and efficiency of the motor.A major advantage of the method is its quite short response time in obtaining the optimal design.

  11. Rotating vector methods for smooth torque control of a switched reluctance motor drive

    SciTech Connect

    Nagel, N.J.; Lorenz, R.D.

    2000-04-01

    This paper has two primary contributions to switched reluctance motor (SRM) control: a systematic approach to smooth torque production and a high-performance technique for sensorless motion control. The systematic approach to smooth torque production is based on development of novel rotating spatial vectors methods that can be used to predict the torque produced in an arbitrary SRM. This analysis directly leads to explicit, insightful methods to provide smooth torque control of SRM's. The high-performance technique for sensorless motion control is based on a rotating vector method for high bandwidth, high resolution, position, and velocity estimation suitable for both precise torque and motion control. The sensorless control and smooth torque control methods are both verified experimentally.

  12. 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. PMID:19100982

  13. Analysis and design of energy recovery snubbers for switched reluctance motor drives

    SciTech Connect

    Gharpure, V.S.; Krishnan, R.; Lee, S.

    1994-12-31

    Snubber studies for switched reluctance motor (SRM) drives are nonexistent even though the power converter topologies are unique and do not fall under the category of inverter topologies applicable to AC motor drives. The importance of the snubbers does not come into the picture until either the power rating of the converter is high and in the multi-kW range or the switching frequency requirement is in the 20 kHz range. Such requirements are coming to the fore in many product development applications such as extruders, general purpose drives, integral starter generators for aircraft, electric vehicles, high speed spindles and centrifuges, etc. This paper is concerned with extending the Undeland snubber configuration to the two-switches per phase power converter topology of the SRM drive including the energy recovery feature. The energy recovery snubbers are then analyzed in terms of the various modes of operation encountered in the converter. A design procedure for the energy recovery snubbers is developed. The design procedure and the operation of the proposed snubber configuration in the SRM drive are experimentally verified with a laboratory prototype SRM drive. The impact of the proposed snubber on the power converter efficiency and its comparison with conventional snubber based systems, such as RCDs, is evaluated to assess the advantages of the proposed energy recovery snubber. 10 refs.

  14. Performance analysis of PV pumping systems using switched reluctance motor drives

    SciTech Connect

    Metwally, H.M.B.; Anis, W.R.

    1996-12-31

    A PV pumping system using switched reluctance motor (SRM) is thoroughly investigated in this work. This motor is supplied by a d.c. voltage through a simple switching circuit. This drive circuit is much simpler than the normal d.c./a.c. inverter required to supply the induction motor. The efficiency of this motor is considerably higher than that of the equivalent d.c. or induction motors. In addition, because of the simple construction, SRM is cheaper than these conventional drives. Because of the above advantages of the SRM, the proposed system has higher efficiency and lower cost as compared with other systems. A design example is studied in detail to explore the advantages of PV pumping systems based on this new drive. The study of the performance of the proposed system showed 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. 21 refs., 10 figs.

  15. 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.

  16. Artificial neural network based torque calculation of switched reluctance motor without locking the rotor

    NASA Astrophysics Data System (ADS)

    Kucuk, Fuat; Goto, Hiroki; Guo, Hai-Jiao; Ichinokura, Osamu

    2009-04-01

    Feedback of motor torque is required in most of switched reluctance (SR) motor applications in order to control torque and its ripple. An SR motor shows highly nonlinear property which does not allow calculating torque analytically. Torque can be directly measured by torque sensor, but it inevitably increases the cost and has to be properly mounted on the motor shaft. Instead of torque sensor, finite element analysis (FEA) may be employed for torque calculation. However, motor modeling and calculation takes relatively long time. The results of FEA may also differ from the actual results. The most convenient way seems to calculate torque from the measured values of rotor position, current, and flux linkage while locking the rotor at definite positions. However, this method needs an extra assembly to lock the rotor. In this study, a novel torque calculation based on artificial neural networks (ANNs) is presented. Magnetizing data are collected while a 6/4 SR motor is running. They need to be interpolated for torque calculation. ANN is very strong tool for data interpolation. ANN based torque estimation is verified on the 6/4 SR motor and is compared by FEA based torque estimation to show its validity.

  17. Experimental verification of adaptive and robust trajectory tracking controllers for switched reluctance motors

    SciTech Connect

    Carroll, J.J.; Dawson, D.M.; Vedagarbha, P.

    1994-12-31

    Integrator backstepping design techniques have recently been used to develop voltage level control algorithms for various classes of electric machines. The resulting control algorithms yield rigorous stability results that are attractive for motor drive applications for several reasons: (1) they can compensate for typically neglected electrical dynamics associated with the motor drive system, (2) they can compensate for a variety of uncertainties throughout the entire drive system (i.e., both modeled and unmodelled electromechanical dynamics), and (3) they can be designed to operate with only partial state measurements (i.e., sensorless control). Despite this promising outlook, few backstepping based algorithms have been experimentally verified, primarily due to their recent theoretical emergence. This paper examines two backstepping based algorithms for switched reluctance (SR) machines which use full-state measurements (i.e., motor position, velocity, and per phase winding currents), to yield rigorous theoretical stability results on the rotor trajectory tracking error despite uncertainty in the SR motor drive system. The controllers incorporate a smooth commutation strategy for the shared specification of the individual SR phase currents. The proposed controllers are experimentally verified using a digital signal processor based data acquisition and control system, and the performance results compared to a backstepping based, exact model knowledge control algorithm.

  18. Performance evaluation of a 250 kW switched reluctance starter generator

    SciTech Connect

    Richter, E.; Ferreira, C.

    1995-12-31

    This paper describes the system integration and performance evaluation testing of a high speed, 250 kW starter/generator [S/G] system used for starting and secondary electrical power extraction from an aircraft propulsion gas turbine. The effort described here is part of a contract sponsored by the USAF, Wright Laboratories, WPAFB. The paper describes a switched reluctance [SR] machine which is operating both as a motor and generator in a speed range of 0 to 22,224 rpm. Additionally it is one of the highest rated motor/generator systems in the SR technology. The system employs two independent channels consisting of two groups of three phase windings, two three phase inverters, and two controllers and can provide two different power output buses for independent loading. The system hardware is described briefly followed by a detailed description of the test results. These show some surprises with regards to single channel operating mode. A brief derivation and explanation of the findings is provided. The motor/generator system is planned to be part of a more electric aircraft power system.

  19. Modelling and steady state simulation of a switched reluctance motor drive

    SciTech Connect

    Ruckstadter, E.J.; Kee, R.J.

    1995-12-31

    The switched reluctance motor (SRM) has been a popular topic of research for the last 15 years. As a result of this development activity, the SRM has evolved into a practical alternative to other machines for a variety of applications. It is now becoming increasingly important to understand the SRM`s control characteristics and power requirements. To accomplish this a thorough description of the machine`s terminal characteristics is required. The SRM can be described as a system with two ports, the windings through which electrical power is transferred and the shaft through which mechanical power flows. These systems are coupled by a magnetic system, through which the energy conversion process occurs. The windings can be modelled as an inductor and much work has focused on the modelling of the SRM inductance. The difficulty with this approach is that the SRM magnetic structures must operate in deep saturation resulting in a nonlinear winding inductance. Many people have linearized this inductance using a variety of techniques but each results in unnecessarily complicated models for many applications. In this paper a relatively simple model for the SRM is developed. This type of model could be a cheap and effective tool for the development of SRM drive systems. This approach will become increasingly relevant as these drives become increasingly popular. In this paper the machine terminal characteristics in terms of flux linkage are described. It will be shown that flux linkage is a function of two variables resulting in a surface function. Additionally it will be shown that this surface function contains the terminal characteristics of the SRM. Finally measurements from actual hardware are made and used to develop a model using the techniques developed here. Results of model simulation are then compared with measured data.

  20. 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

  1. Study on Thrust Improvement and Ripple Suppression of HTS Linear Switched Reluctance Motor with Coreless HTS Excitation Windings

    NASA Astrophysics Data System (ADS)

    Oto, Satoshi; Hirayama, Tadashi; Kawabata, Shuma

    This paper describes a linear switched reluctance motor (LSRM) in which HTS tapes are used for coreless excitation windings in order to reduce the thrust ripple and normal force. This LSRM consists of a mover with saliency structure, coreless HTS coils and a stator back yoke. In this paper, we first describe the operating principle of the HTS-LSRM. Next, we calculate performances of the HTS-LSRM using 3-D FEM analysis. The effects of the motor structure on the thrust characteristic and normal force characteristics are clarified from the numerical results. Furthermore, we investigate the motor structure for thrust improvement, thrust ripple and normal force reduction.

  2. 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.

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

    PubMed

    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. PMID:25725876

  4. 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

  5. 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. PMID:22294906

  6. 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.

  7. 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.

  8. 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. PMID:22969364

  9. 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

  10. 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.

  11. Dynamics in hybrid complex systems of switches and oscillators

    NASA Astrophysics Data System (ADS)

    Taylor, Dane; Fertig, Elana J.; Restrepo, Juan G.

    2013-09-01

    While considerable progress has been made in the analysis of large systems containing a single type of coupled dynamical component (e.g., coupled oscillators or coupled switches), systems containing diverse components (e.g., both oscillators and switches) have received much less attention. We analyze large, hybrid systems of interconnected Kuramoto oscillators and Hopfield switches with positive feedback. In this system, oscillator synchronization promotes switches to turn on. In turn, when switches turn on, they enhance the synchrony of the oscillators to which they are coupled. Depending on the choice of parameters, we find theoretically coexisting stable solutions with either (i) incoherent oscillators and all switches permanently off, (ii) synchronized oscillators and all switches permanently on, or (iii) synchronized oscillators and switches that periodically alternate between the on and off states. Numerical experiments confirm these predictions. We discuss how transitions between these steady state solutions can be onset deterministically through dynamic bifurcations or spontaneously due to finite-size fluctuations.

  12. 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.

  13. Design of a hybrid switching architecture for avionic WDM platforms

    NASA Astrophysics Data System (ADS)

    Huang, Jin; Qiu, Kun; Xu, Bo; Ling, Yun

    2014-01-01

    A novel hybrid switching architecture using optical circuit switching for intra-subnet communication and fiber channel (FC) for inter-subnet communication is proposed. The proposed scheme utilizes small-size arrayed waveguide grating routers (AWGRs) and legacy FC switches to construct the large-scale avionic network, thus has the potential of the lower latency, the satisfactory network bandwidth and the lower power consumption. The simulation results verify that the proposed architecture outperforms FC switched architecture in terms of real time performance and power consumption.

  14. 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.

  15. Recent Advances of Reluctance Torque Assisted Motors

    NASA Astrophysics Data System (ADS)

    Ohyama, Kazunobu

    The history of motor technology began with the discovery of electromagnetic induction by Faraday. Various kinds of motors were developed by the recent progress of the fundamental technology (magnetic structure, magnetic material, drive circuit, control method). Especially, motors using the reluctance torque have many advantages and some of them are used as high efficient motors. This paper overviews recent advances of reluctance torque assisted motors such as Switched Reluctance Motor (SRM), Synchronous Reluctance Motor (SynRM) and Interior Permanent Magnet Synchronous Motor (IPMSM).

  16. 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.

  17. 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.

  18. Hybrid MOSFET/Driver for Ultra-Fast Switching

    SciTech Connect

    Tang, T; Burkhart, C.; /SLAC

    2008-07-11

    The ultra-fast switching of power MOSFETs, in {approx}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 the 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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. PMID:24690810

  5. Reluctance and doubly-excited reluctance motors

    NASA Astrophysics Data System (ADS)

    Heyne, C. J.; El-Antably, A. M.

    1984-11-01

    Since the energy crisis in 1974, there was increasing awareness of conserving energy. Industrial ac motors from 1 to 125 hp are estimated to consume 60% of the total electricity produced in the United States. Significant energy conservation could be achieved if the efficiency of these motors is improved. The work described was sponsored by the Division of Electric Energy Systems (EES) of the United States Department of Energy (DOE) through a subcontract with the Power Systems Technology Program at the Oak Ridge National Laboratory (Oak Ridge, Tennessee, USA). The design, analysis, and test of two types of motors designed to have a high efficiency and power factor are described. The first type, reluctance motors (RMs), are similar to synchronous motors but without dc excitation. A novel 3-phase RM was designed and tested, and it was found to have superior efficiency when compared with a similar induction motor.

  6. Reluctance and doubly-excited reluctance motors

    SciTech Connect

    Heyne, C.J.; El-Antably, A.M.

    1984-11-01

    Since the energy crisis in 1974, there has been increasing awareness of conserving energy. Industrial ac motors from 1 to 125 hp are estimated to consume 60% of the total electricity produced in the United States. Significant energy conservation could be achieved if the efficiency of these motors is improved. The work described in this report was sponsored by the Division of Electric Energy Systems (EES) of the United States Department of Energy (DOE) through a subcontract with the Power Systems Technology Program at the Oak Ridge National Laboratory (Oak Ridge, Tennessee, USA). This work deals with the design, analysis, and test of two types of motors designed to have a high efficiency and power factor. The first type, reluctance motors (RMs), are similar to synchronous motors but without dc excitation. A novel 3-phase RM has been designed and tested, and it was found to have superior efficiency when compared with a similar induction motor.

  7. 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.

  8. For Reluctant Readers.

    ERIC Educational Resources Information Center

    Fidell, Jeannette A.; Horn, Valerie

    The eleven lesson plans outlined in this booklet are designed to stimulate and challenge both underachievers and reluctant readers by helping them learn to read "The New York Times." The lesson plans include the following: exercises in vocabulary enrichment; exercises for developing dictionary skills; topics for oral reports; topics for written…

  9. 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…

  10. 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. PMID:26466241

  11. 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.

  12. 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. PMID:25680131

  13. Polarization Domain Switching of Improper Hybrid Ferroelectric (Ca,Sr)3Ti2O7 Crystals

    NASA Astrophysics Data System (ADS)

    Lim, Seong Joon; Gao, Bin; Kim, Jaewook; Huang, Fei-Ting; Cheong, Sang-Wook; RCEM Team

    The observation of switchable polarization loops at room temperature in (Ca,Sr)3Ti2O7, induced by improper hybrid ferroelectricity, has drawn much attention. Since the ferroelectric polarization directly couples with structural distortions (oxygen octahedral tilting and rotation) in hybrid improper ferroelectrics, the energy barrier for polarization switching is predicted to be large, and the observation of ferroelectric polarization loops was a surprise. Furthermore, the observed complexity of the domain wall configuration in (Ca,Sr)3Ti2O7 may complicate the domain wall motion or the domain nucleation for polarization switching. Thus, it is imperative to understand the mechanism and dynamics of polarization domain switching. Particularly, it has to be clarified if polarization switching occurs through 90° or 180° switching. Comparing piezoresponse force microscope and polarized optical microscope images before and after applying electric fields consecutively, we explored the mechanism and dynamics of polarization domain switching. This work is funded by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF4413 to the Rutgers Center for Emergent Materials.

  14. Proton switch for modulating oxygen reduction by a copper electrocatalyst embedded in a hybrid bilayer membrane

    NASA Astrophysics Data System (ADS)

    Barile, Christopher J.; Tse, Edmund C. M.; Li, Ying; Sobyra, Thomas B.; Zimmerman, Steven C.; Hosseini, Ali; Gewirth, Andrew A.

    2014-06-01

    Molecular switches gate many fundamental processes in natural and artificial systems. Here, we report the development of an electrochemical platform in which a proton carrier switches the activity of a catalyst. By incorporating an alkyl phosphate in the lipid layer of a hybrid bilayer membrane, we regulate proton transport to a Cu-based molecular oxygen reduction reaction catalyst. To construct this hybrid bilayer membrane system, we prepare an example of a synthetic Cu oxygen reduction reaction catalyst that forms a self-assembled monolayer on Au surfaces. We then embed this Cu catalyst inside a hybrid bilayer membrane by depositing a monolayer of lipid on the self-assembled monolayer. We envisage that this electrochemical system can give a unique mechanistic insight not only into the oxygen reduction reaction, but into proton-coupled electron transfer in general.

  15. 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.

  16. 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.

  17. Hybrid electro-optic plasmonic modulators based on directional coupler switches

    NASA Astrophysics Data System (ADS)

    Zografopoulos, Dimitrios C.; Swillam, Mohamed A.; Shahada, Lamees A.; Beccherelli, Romeo

    2016-04-01

    By breaking the diffraction limit, plasmonics enable the miniaturization of integrated optical signal processing units in a platform compatible with traditional CMOS technology. In such architectures, modulators and switches are essential elements for fast and low-power optical signal processing. This work presents the design of a CMOS-compatible hybrid plasmonic modulator based on directional couplers enhanced with a layer of electro-optic polymer. The modulator shows very broad operating window with low crosstalk values and very small footprint with respect to similar couplers and switches of the silicon photonics platform.

  18. 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.

  19. Operation Analysis for Electrical Machinery Based on Reluctance Network

    NASA Astrophysics Data System (ADS)

    Nakamura, Kenji; Ichinokura, Osamu

    In this paper, we describe the basis of a magnetic circuit method and introduce a reluctance network analysis (RNA) proposed by authors. The RNA, which is based on the magnetic circuit method, has some suitable merits for simulating electrical machineries such as a simple analytical model, ease of coupled analysis with electrical circuits, motion, and thermal fields. In addition to these merits, a general-purpose circuit simulator like “SPICE" can be utilized as a solver. We present some applications of the RNA to operation analysis for an orthogonal-core, a switched reluctance motor, and a permanent magnet generator.

  20. 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.

  1. 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. PMID:21446436

  2. Switching of nanoparticles in large-scale hybrid electro-optofluidics integration.

    PubMed

    Jiao, Wenxiang; Wang, Guanghui; Ying, Zhoufeng; Zou, Yi; Ho, Ho-Pui; Sun, Tianyu; Huang, Ying; Zhang, Xuping

    2016-06-01

    We numerically demonstrate the scheme of independent optofluidic switching of nanoparticles on a silicon-based lab-on-a-chip system, using an electronic logic activated ring-assisted Mach-Zehnder interferometer (RAMZI). By using the carrier injection method with a tiny refractive index change of 8.00×10-4 to adjust the phase delay of a ring resonator sitting on one arm of the MZI, the light passing through could be switched to any output port of MZI followed by a directional coupler (DC). Meanwhile, the trapping force and scattering force of the guided lightwave could provide the actuation for sample delivery. Therefore, the switching logic of the guided mode is mapping to its loaded sample of nanomaterials. Our structure possesses high compactness, scalability, and time-effectiveness and, thereby, it is very appropriate for on-chip optical manipulation. The introduction of the RAMZI and cascaded RAMZIs in an optofluidic chip can form a scalable switching module with an independent electronic logic trigger signal, and make the chip dynamically configurable and scalable, which is very critical and opens a new horizon for the large-scale hybrid electro-optofluidics integration of a lab-on-a-chip system. PMID:27244437

  3. Note. Switch-Mode Hybrid Current Controllers for Quantum Cascade Lasers

    SciTech Connect

    Taubman, Matthew S.

    2013-01-07

    Chemical sensing in the mid-infrared has been revolutionized by the advent of quantum cascade lasers. Their higher current and voltage demands compared to laser diodes however, negatively impact size, weight and power footprint for fieldable systems, particularly in hot environments. This letter presents a switch-mode/linear hybrid controller design, furnishing low-noise drive current up to 2 amperes at compliance voltages up to 15 volts, with noise levels close to the Johnson noise of the internal resistors. Current modulation from near zero to 1.8 Amps is also demonstrated at frequencies up to a kilohertz.

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

    NASA Astrophysics Data System (ADS)

    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.

    2016-03-01

    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.

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

    PubMed

    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

  6. 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

  7. 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

    2015-10-01

    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. PMID:26480083

  8. 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. PMID:26726561

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Giving Reluctant Students a Voice

    ERIC Educational Resources Information Center

    Redekopp, Reynold; Bourbonniere, Elizabeth

    2009-01-01

    All teachers know them--the students who sit in the back of the room and never make a peep. If prodded, they may reluctantly offer a comment or opinion, but they are so obviously uncomfortable about participating that a teacher may wonder if it is even worth trying to engage them. Are they unprepared or just shy? Do they lack ideas or merely need…

  15. 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.

  16. 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

    2016-01-01

    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

  17. 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

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Cheong, Sang-Wook; Rutgers Center For Emergent 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.

  1. 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. PMID:25725867

  2. 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.

  3. 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. PMID:25418881

  4. 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…

  5. 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.

  6. 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.

  7. 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.

  8. Optoelectronic ATM switch employing hybrid silicon CMOS/GaAs FET-SEEDs

    NASA Astrophysics Data System (ADS)

    Lentine, Anthony L.; Reiley, Daniel J.; Novotny, Robert A.; Morrison, Rick L.; Sasian, Jose M.; Beckman, Martin G.; Buchholz, D. B.; Hinterlong, Stephen J.; Cloonan, Thomas J.; Richards, Gaylord W.; McCormick, Frederick B., Jr.

    1996-03-01

    In the past few years, the demand for telecommunications services beyond voice telephony has skyrocketed. For the growth of these services to continue at this rate, cost effective means of transporting and switching large amounts of information must be found. Although fiber optic transmission has significantly reduced the cost of transmission, switching high bandwidth signals remains expensive. While all electronic switching systems are certainly possible for these high bandwidth systems, considerable effort has been expended to reduce the cost of fiber optic connections between frames or racks of equipment separated by several meters. As an example, one can envision fiber-optic data links connecting the line units that receive and transmit data from the outside world with an electronic switching fabric. Optical data links, ODLs, can perform the optical to electrical conversions. Several of these optical data links can be electrically connected with electronic switching chips on a printed circuit board. As the demand for bandwidth increases, several hundred to several thousand optical fibers might be incident on the switching fabric. Discrete optical data links and parallel data links with up to 32 fibers per data link remain an expensive solution to transporting this information due to their per-link cost, physical size, and power dissipation. Power dissipation on the switching chips is high because of the need for electronic drivers for the high speed electrical interconnections between the switching chips and the data links. By integrating the O/E conversions directly onto the switching chips, lower cost and higher density systems can be built. In this paper, we describe preliminary results of an experimental optoelectronic switching network based on this lower cost solution. The network is designed to be part of an asynchronous transfer mode (ATM) network based on the Growable Packet Architecture. The switching chip consists of GaAs/AlGaAs multiple quantum well

  9. Motivating Reluctant Learners: Innovative Contingency Packages.

    ERIC Educational Resources Information Center

    Raschke, Donna; And Others

    1987-01-01

    Contingency packages can be incorporated into classroom management techniques for reluctant learners (who may have already experienced failure in education) to encourage enthusiasm and motivation for learning. Suggestions are provided for implementing programs using a robot or football concepts. (CB)

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Resistive Switching Behavior in Organic-Inorganic Hybrid CH3 NH3 PbI3-x Clx Perovskite for Resistive Random Access Memory Devices.

    PubMed

    Yoo, Eun Ji; Lyu, Miaoqiang; Yun, Jung-Ho; Kang, Chi Jung; Choi, Young Jin; Wang, Lianzhou

    2015-10-28

    The CH3 NH3 PbI3- x Clx organic-inorganic hybrid perovskite material demonstrates remarkable resistive switching behavior, which can be applicable in resistive random access memory devices. The simply designed Au/CH3 NH3 PbI3- x Clx /FTO structure is fabricated by a low-temperature, solution-processable method, which exhibits remarkable bipolar resistive switching and nonvolatile properties. PMID:26331363

  15. 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.

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

    SciTech Connect

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

    2013-05-28

    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 O{sup 2-} 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.

  17. 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.

  18. 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.

  19. Silicon oxide deposition for enhanced optical switching in polydimethylsiloxane-liquid crystal hybrids.

    PubMed

    De Sio, Luciano; Vasdekis, Andreas E; Cuennet, Julien G; De Luca, Antonio; Pane, Alfredo; Psaltis, Demetri

    2011-11-01

    We report an optical switch based on a diffraction grating by combining PDMS microstructures with a photo-responsive Nematic Liquid Crystal (NLC). The grating was realized via replica molding and was subsequently coated with a thin SiO layer. SiO induced a full planar alignment of the liquid crystal. The induced parallel alignment of the LC reduces the response time of the structure by approximately an order of magnitude compared to the same structures without SiO. We explored the effect of the pump intensity on the transmission properties and time response of the switch and identified a strong dependence on the probe polarization, due to the full planar alignment in this structure. The aforementioned inclusion of the SiO layer enables enhanced performance of optical devices based on the fusion of nematogens with soft and flexible substrates. PMID:22109231

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Curran, P. 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.; Pugach, N.; Eschrig, M.; Bending, S. J.

    2015-12-01

    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.

  2. 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.

  3. 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.…

  4. Radial force in a bearingless reluctance motor

    NASA Astrophysics Data System (ADS)

    Chiba, Akira; Rahman, M. A.; Fukao, Tadashi

    1991-03-01

    A four-pole reluctance synchronous machine with additional two-pole windings was constructed. The additional winding currents produce the radial force to act as a magnetic bearing. Expressions for the machine inductance functions are given. Inductance functions with respect to the eccentric displacement of the rotor were measured. The contribution of these inductances to the radial force production is established.

  5. A hybrid model for the charging process of the amorphous SiO2 film in radio frequency microelectromechanical system capacitive switches

    NASA Astrophysics Data System (ADS)

    Wang, Li-Feng; Huang, Qing-An; Tang, Jie-Ying; Liao, Xiao-Ping

    2011-03-01

    Charging is one of the most important reliability issues in radio frequency microelectro- mechanical systems (RF MEMS) capacitive switches since it makes the actuation voltage unstable. This paper proposes a hybrid model to describe the transient dielectric charging and discharging process in the defect-rich amorphous SiO2 RF MEMS capacitive switches and verifies experimentally. The hybrid model contains two parts according to two different charging mechanisms of the amorphous SiO2, which are the polarisation and charge injection. The models for polarisation and for charge injection are established, respectively. Analysis and experimental results show that polarisation is always effective, while the charge injection has a threshold electric field to the amorphous SiO2 film. Under different control voltage conditions, the hybrid model can accurately describe the experimental data. Project supported by the National Natural Science Foundation of China (Grant No. 60676043).

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Iron loss calculation for synchronous reluctance machines

    SciTech Connect

    Leonardi, F.; Matsuo, T.; Lipo, T.A.

    1995-12-31

    A numerical method for iron loss calculation is presented in this paper. The method is suitable for any synchronous and most dc machines, especially if the current waveforms are known a priori . This technique will be principally useful for high speed machines and in particular for the synchronous reluctance machines and in particular for the synchronous reluctance machine, where the iron losses are often an important issue. The calculation is based on Finite Element Analysis, which provides the flux density waveforms in the iron, and on the Fourier Analysis of these waveforms. Several Finite Element Simulations are necessary to obtain the induced voltage versus time waveforms. To reduce the post-processing time the majority of the elements of the model are grouped together to create super elements. Also the periodicity of the motor can be used to reduce the number of required simulations. The method is applied to the calculation of the iron losses of a synchronous reluctance generator, and a number of interesting results are discussed in the paper.

  11. 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)

  12. Prospects for Use of Synchronous Reluctance Motors in Low-Power Electrical Devices

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    This paper focuses on studying the synchronous reluctance motors as an alternative to low-power commutator motors. Analysis is done for the improved design of synchronous reluctance motor with a segmental external rotor. Relevant equations and a suitable method are proposed for calculating characteristics of the synchronous reluctance motors operating in a specific mode with electronic commutation as switched reluctance motors. It is concluded that synchronous reluctance motors in this mode can provide a wide range of characteristics and are quite competitive with commutator motors used in low-power devices. Aplūkoti sinhronie reaktīvie dzinēji kā mazjaudas kolektordzinēju alternatīva. Analizētas sinhrono reaktīvo dzinēju uzlabotas konstrukcijas ar segmentveida ārējo rotoru. Aprakstīti sinhrono reaktīvo dzinēju vienādojumi un raksturlīkņu aprēķināšanas metodika gadījumam, kad tie darbojas ventiļdzinēju sastāvā. Parādīts, ka sinhronie reaktīvie dzinēji šādos gadījumos var nodrošināt plašu mehānisko raksturlīkņu spektru un sekmīgi konkurēt ar kolektordzinējiem mazjaudas elektroierīcēs.

  13. 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 . PMID:27231982

  14. 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.

  15. 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.

  16. Thermal Analysis Of Reluctant Glass Formers

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Curreri, Peter A.

    1989-01-01

    Thermocouple holds sample and monitors temperature during cooling. Ellipsoidal furnace provides controlled cooling rates for studies of thermal properties of reluctant glass formers. Glass tube inserted into furnace and used to blow helium on specimen to cool rapidly. Cooling curve analyzed to determine rate of cooling and such properties of sample as nucleation and recalescence temperatures at cooling rate. Continuous-cooling-crystallization boundaries determined empirically from plots of nucleation time vs. nucleation temperature from runs at large number of different rates of cooling. Apparatus used to examine glass-formation ability of material and critical cooling rate to form glass.

  17. 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.

  18. 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. PMID:26971562

  19. Design and Simulation of 2×2 MMI Coupler and Thermo-optic Switch Using Sol-Gel Derived Organic-Inorganic Hybrid Material

    NASA Astrophysics Data System (ADS)

    Samah, M. Firdaus A.; Nawabjan, Amirjan; Abdullah, Ahmad Sharmi; Ibrahim, Mohd Haniff; Kassim, Norazan Mohd; Mohamad, Abu Bakar

    2011-05-01

    A new design of Multimode Interference (MMI) thermo-optic switch with improved crosstalk figure is demonstrated in this paper. The device is designed and simulated using BeamProp 3D from Rsoft and 3D BPM CAD softwares. The devices are designed based on sol-gel derived organic-inorganic hybrid material, vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and tetrabutoxytitanate (TTBu) or VTT with refractive index of 1.47 as a core and surrounded by silica with refractive index of 1.45 at 1550 nm wavelength. The switching power is 164mW and the simulation result show that the propagation loss of the MMI device is 1.8 dB and zero crosstalk.

  20. 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

  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 fully digital control strategy for synchronous reluctance motor servo drives

    SciTech Connect

    Xiang, Y.Q.; Nasar, S.A.

    1995-12-31

    For existing electric drives, the controller implementation is either totally analog or hybrid analog/digital, and the control algorithm broadly falls into two categories: Average Torque Control (ATC) and Instantaneous Torque Control (InsTC). In this paper, a fully digital implementation oriented control strategy--Incremental Torque Control (IncTC)--is proposed and verified with digital simulation. A TMS320C30 DSP based implementation of the proposed IncTC is developed and tested. Experimental results given in the paper indicate that the proposed IncTC is valid and holds a great promise for reluctance motor digital control.

  3. Effects of converter excitation on the performance of axially laminated anisotropic synchronous reluctance motor drives

    SciTech Connect

    Arkadan, A.A.; Russell, A.A. . Electrical and Computer Engineering Dept.)

    1999-05-01

    An indirectly coupled State Space-Finite Element (ICSS-FE) model of Axially Laminated Anisotropic (ALA) Synchronous Reluctance Motor (SynRM) drive systems is used to evaluate the impact of converter excitation on the machine performance characteristics., The model utilizes an iterative approach which includes the full impact of nonlinearities on the machine magnetic circuit, and which results in the nonsinusoidal flux waveforms in the different parts of the machine. The modeling approach is applied to a prototype ALA SynRM designed for use in hybrid vehicle applications.

  4. Optimization of Our SC HTS Reluctance Motor

    NASA Astrophysics Data System (ADS)

    Oswald, B.; Best, K.-J.; Setzer, M.; Söll, M.; Gawalek, W.; Gutt, A.; Kovalev, L.; Fisher, L.; Krabbes, G.; Freyhardt, H. C.

    2004-06-01

    Since several years we have successfully designed, built and tested at 77K several reluctance motors. YBCO bulk material has been incorporated into the rotor. Our latest results, based on the old design, will be published within the proceedings of the 8th VDI-Status-Seminar. The range of mechanical output power achieved is up to about 200 kW. All these motors have shown that a significant step in performance is obtained by using HTS bulk elements in the rotor, compared to the data of these test motors without superconductors. However, by now the motor parameters have been limited to certain values. In order to optimize this type of motor and to achieve increased output power and power density we have modified the design with several respects. This includes properties of the superconductor (critical current density raised by about 20%), the use of special soft magnetic material in the stator (increased saturation polarization), modified cut of the laminations (optimized for application at 77 K), and new geometry of the motor dimensions aimed at extremely high dynamics in order to adapt this motor to some special applications. With our present paper we present the results of this optimization which have brought the expected improvements and which are in excellent accordance with theory.

  5. 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.

  6. Reluctance machines incorporating high temperature superconducting materials on the rotor

    NASA Astrophysics Data System (ADS)

    Rodrigues, A. L.; Pires, A. J.

    2010-01-01

    The computer modelling of reluctance machines with rotors containing both iron and high temperature superconducting (HTS) materials, using the finite element method (FEM), is presented in this paper. The modelling permits to obtain the field and stator current distribution from where reluctance torque is evaluated. Different solutions are analyzed and experimental results on a 2 kW reluctance motor using HTS materials on the rotor and cooled by liquid nitrogen, show a significant increase in the torque values, when compared with that of a correspondent conventional machine. Pre-magnetization of these rotors by field cooling is explained and this process gives a mechanical output power undoubtedly better than that of a conventional reluctance machine.

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

    PubMed Central

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

    2013-01-01

    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. PMID:24091355

  8. 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.

  9. Optical Switch Using Risley Prisms

    SciTech Connect

    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.

  10. Hybrid aluminum and indium conducting filaments for nonpolar resistive switching of Al/AlOx/indium tin oxide flexible device

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Wang, Jer-Chyi; Zhang, Zhigang; Ye, Yu-Ren; Pan, Liyang; Xu, Jun; Lai, Chao-Sung

    2014-02-01

    The nonpolar resistive switching characteristics of an Al/AlOx/indium tin oxide (ITO) device on a plastic flexible substrate are investigated. By analyzing the electron diffraction spectroscopy results and thermal coefficient of resistivity, it is discovered that the formation of aluminum and indium conducting filaments in AlOx film strongly depends on the polarity of the applied voltage. The metal ions arising from the Al and ITO electrodes respectively govern the resistive switching in corresponding operation polarity. After 104 times of mechanical bending, the device can perform satisfactorily in terms of resistance distribution, read sequence of high and low resistive states, and thermal retention properties.

  11. All-optical switching with 1-ps response time in a DDMEBT enabled silicon grating coupler/resonator hybrid device.

    PubMed

    Covey, John; Finke, Aaron D; Xu, Xiaochuan; Wu, Wenzhi; Wang, Yaguo; Diederich, François; Chen, Ray T

    2014-10-01

    An amorphous film of the third-order nonlinear optical material DDMEBT was spun onto silicon chips for the first time, filling 80 nm lithographic features. A 710 μm² device was designed, fabricated, and tested that acts both as a nonlinear resonator switch and as an input/output grating coupler to a perfectly vertical single mode fiber. Autocorrelation and spectral measurements indicate the device has <1 ps response time, 4 nm of switching bandwidth, and 4 dB of on/off contrast. With sufficient power, this all-optical device can potentially modulate a single optical carrier frequency in excess of 1 THz. PMID:25322028

  12. 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.

  13. A new metal-organic hybrid material with intrinsic resistance-based bistability: monitoring in situ room temperature switching behavior

    SciTech Connect

    Zhang, Zhongyue; Zhao, Hanhua; Matsushita, Michio M.; Awaga, Kunio; Dunbar, Kim R.

    2014-08-06

    Two new silver containing materials with TCNQ derivatives were prepared by electrocrystallization. Synchrotron radiation diffraction studies were conducted to determine the structures of the new phases which exhibit unprecedented high room temperature conductivity. The I–V characteristics reveal a room-temperature switching behaviour and memory effect based on intrinsic negative differential resistance (NDR). EPR spectroscopic measurements performed under an applied electric field indicate a g-tensor shift that is correlated to the amplitude of current.

  14. A frequency-locked and frequency-doubled, hybrid Q-switched Yb:KYW laser at 515 nm with a widely adjustable repetition rate

    NASA Astrophysics Data System (ADS)

    Tjörnhammar, S.; Zukauskas, A.; Canalias, C.; Pasiskevicius, V.; Laurell, F.

    2015-09-01

    We demonstrate a compact wavelength-stabilized, frequency-doubled Yb-doped double-tungstate laser with widely tunable repetition rate, spanning from 35 Hz to 3 kHz obtained by hybrid Q-switching. The Q-switching unit consisted of a combination of a passive Cr:YAG crystal and an opto-mechanical active intensity modulator. The fundamental wavelength was locked at 1029 nm with a volume Bragg grating, and the pulse length and energy were 42 ns and 250 µJ, respectively. As the laser was stabilized with the VBG and the opto-mechanical modulator, the frequency instability was reduced six times from free running down to 0.29 %. Frequency doubling was done extra-cavity in PPKTP, and a repetition rate-independent conversion efficiency of 63 % was obtained. The controllable repetition rate together with stable temporal and spatial characteristics makes this laser a suitable candidate in many biology-related experiments, as a pump source for in vivo excitation of fluorophores, e.g., pumping of "living lasers" and matrix-assisted laser desorption/ionization mass spectroscopy.

  15. 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). PMID:25984963

  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. Retaining Reluctant Learners in ABE through the Student Intake Period.

    ERIC Educational Resources Information Center

    Pennsylvania State Univ., University Park. Inst. for the Study of Adult Literacy.

    A project sought to determine if reluctant learners, about 30 percent of the adult basic education (ABE) population, can be retained in ABE classes through accommodations in the program structure and more effective teacher/counselor intervention. The project was based on earlier research findings that most ABE learners who drop out do so in the…

  18. Jason's Story: Motivating the Reluctant Student to Write.

    ERIC Educational Resources Information Center

    Carignan-Belleville, Lynne

    1989-01-01

    Proposes that reluctant writers' motivation can be enhanced by using a simple writing format, by allowing students to write in areas of strong interest, and by giving much reassurance. Stresses that success in an endeavor is essential to motivation and achievement. (SR)

  19. 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…

  20. 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…

  1. 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…

  2. Reel Teaching = Real Learning: Motivating Reluctant Students through Film Studies

    ERIC Educational Resources Information Center

    Smilanich, Brad; Lafreniere, Nicole

    2010-01-01

    The authors provide a rationale for the critical study of film texts in the English language arts. For struggling or reluctant students, film offers an accessibility that the printed text may not. Students who are intimidated by, or impeded from, accessing print text are able to discuss film with acuity and insight. The study of visual texts can…

  3. Reflecting on Ways to Help the Reluctant Artist Communicate

    ERIC Educational Resources Information Center

    Bentley, Dana Frantz

    2011-01-01

    In this article, the author shares how she changed the way she engaged with Alex, a student who was reluctant to do art projects. While reflecting on Alex's objections to doing art projects, she noticed one concern in particular that arose again and again: he wanted to play. Alex experienced the shift into art-making as a break from playing with…

  4. 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.

  5. A New Analysis about Efficient Drive of Synchronous Reluctance Motors

    NASA Astrophysics Data System (ADS)

    Shinnaka, Shinji

    This paper gives a new analysis about the minimum current under the flux saturation for efficient drive of synchronous reluctance motors. This paper shows that the asymmetric flux saturation of the mirror-phase inductance causes the nonlinear minimum current trajectory, and derives newly the general analytical trajectory and a concrete approximated analytical trajectory.

  6. 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…

  7. 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.

  8. ``Hybrid'' multi-gap/single-gap Josephson junctions: Evidence of macroscopic quantum tunneling in superconducting-to-normal switching experiments on MgB2/I/Pb and MgB2/I/Sn junctions

    NASA Astrophysics Data System (ADS)

    Carabello, Steve; Lambert, Joseph; Dai, Wenqing; Li, Qi; Chen, Ke; Cunnane, Daniel; Xi, X. X.; Ramos, Roberto

    We report results of superconducting-to-normal switching experiments on MgB2/I/Pb and MgB2/I/Sn junctions, with and without microwaves. These results suggest that the switching behavior is dominated by quantum tunneling through the washboard potential barrier, rather than thermal excitations or electronic noise. Evidence includes a leveling in the standard deviation of the switching current distribution below a crossover temperature, a Lorentzian shape of the escape rate enhancement peak upon excitation by microwaves, and a narrowing in the histogram of escape counts in the presence of resonant microwave excitation relative to that in the absence of microwaves. These are the first such results reported in ``hybrid'' Josephson tunnel junctions, consisting of multi-gap and single-gap superconducting electrodes.

  9. 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.

  10. High-speed synchronous reluctance machine with minimized rotor losses

    SciTech Connect

    Hofmann, H.; Sanders, S.R.

    2000-04-01

    This paper presents a refined design of a high-speed synchronous reluctance machine with minimized eddy-current losses in the rotor. Design criteria are the ability of the rotor to withstand high speeds, ability to operate in vacuum, negligible zero-torque spinning losses, high reliability, high efficiency, and low manufacturing cost. The rotor of the synchronous reluctance machine consists of bonded sections of ferromagnetic and non-magnetic steels. Finite-element code, incorporating rotor rotation, has been developed in MATLAB that calculates steady-state eddy currents (and losses) in the rotor. A stator iron and stator winding have been designed to minimize rotor losses, and two such prototype machines have been fabricated. Experimental results show an efficiency of 91% at a 10-kW 10,000-r/min operating point, and rotor losses less than 0.5% of input power.

  11. Design optimization of axially laminated rotors for synchronous reluctance motors

    NASA Astrophysics Data System (ADS)

    Wakao, S.; Nishimura, Y.; Ando, H.; Onuki, T.

    2000-05-01

    This article describes a design optimization of an axially laminated rotor of the synchronous reluctance motor, using the optimization method combined with the magnetic field analysis. The magnetic flux distribution in the synchronous reluctance motor is distorted due to the complicated rotor configuration and the influence of magnetic saturation, which results in a large number of local minimum solutions. Therefore, taking account of the magnetic saturation by the finite element method, the authors propose a novel optimization approach by coupling the stochastic search method with the deterministic one. In the optimization process a suitable objective function for the stability of machine performances is also proposed. Finally some numerical results that demonstrate the validity of the proposed approach are presented.

  12. Study of Axially-Laminated Anisotropic Rotor Reluctance Synchronous Machine and its Drive

    NASA Astrophysics Data System (ADS)

    Fu, Zhenxing

    1991-02-01

    This dissertation presents a relatively comprehensive study of 2-pole axially-laminated anisotropic (ALA) rotor reluctance synchronous machine in both motoring and generating modes. The theory, analysis techniques, and vector control strategies developed can be applied to other types of reluctance synchronous machines as well, with or without corresponding modifications. Space phasor models of the machine in stator or rotor coordinates are presented. Steady state performance, such as, maximum power factor and efficiency are studied. Transient torque capabilities for constant stator flux, current, and voltage are investigated together with transient state operations. Analytical determinations of d-axis and q -axis magnetic fields, and the corresponding inductances are presented. FEM numerical magnetic field analysis along the d-axis and q-axis is performed for refined design and parameter estimations. To meet the desired performance and high d-axis to q-axis inductances ratio from axially -laminated anisotropic rotor, multi-slot per phase per pole should be used. Experimental tests of the machine in both motoring and generating modes are performed, a high d-axis to q-axis inductances ratio of 21.3 and a maximum power factor of 0.914 and a maximum efficiency of 94% are obtained. Novel current vector control and torque vector control schemes are developed with extensive digital simulations. Sliding mode controller is used and compared with PI controller. Torque vector control principles and stator flux and torque estimation techniques are presented together with the table of optimal voltage vector switchings. A wide controllable speed range of 0.1 rpm to 5000 rpm (for current vector control) and 0.2 rpm to 12000 rpm (for torque vector control) are obtained. The dynamics of the vector controlled drive are fast and relatively robust. A novel fuzzy knowledge-based sensorless dc output voltage control of ALA-rotor reluctance generator is developed and digitally simulated

  13. 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.

  14. Transient model of a doubly excited reluctance motor

    SciTech Connect

    Xu, L.; Liang, F.; Lipo, T.A. . Dept. of Electrical and Computer Engineering)

    1991-03-01

    A transient machine model of a doubly fed reluctance motor is derived by means of winding function and d-q transformation theory. The machine consists of a double wound stator having four and eight pole sets. The rotor is equipped with six poles. The machine, related to the Hunt motor, has a synchronous speed of a twelve pole machine. Comparison of simulated to tested results indicates that the higher harmonics in the motor inductances are important for predicting current waveform.

  15. 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.

  16. 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.

  17. Towards single molecule switches.

    PubMed

    Zhang, Jia Lin; Zhong, Jian Qiang; Lin, Jia Dan; Hu, Wen Ping; Wu, Kai; Xu, Guo Qin; Wee, Andrew T S; Chen, Wei

    2015-05-21

    The concept of using single molecules as key building blocks for logic gates, diodes and transistors to perform basic functions of digital electronic devices at the molecular scale has been explored over the past decades. However, in addition to mimicking the basic functions of current silicon devices, molecules often possess unique properties that have no parallel in conventional materials and promise new hybrid devices with novel functions that cannot be achieved with equivalent solid-state devices. The most appealing example is the molecular switch. Over the past decade, molecular switches on surfaces have been intensely investigated. A variety of external stimuli such as light, electric field, temperature, tunneling electrons and even chemical stimulus have been used to activate these molecular switches between bistable or even multiple states by manipulating molecular conformations, dipole orientations, spin states, charge states and even chemical bond formation. The switching event can occur either on surfaces or in break junctions. The aim of this review is to highlight recent advances in molecular switches triggered by various external stimuli, as investigated by low-temperature scanning tunneling microscopy (LT-STM) and the break junction technique. We begin by presenting the molecular switches triggered by various external stimuli that do not provide single molecule selectivity, referred to as non-selective switching. Special focus is then given to selective single molecule switching realized using the LT-STM tip on surfaces. Single molecule switches operated by different mechanisms are reviewed and discussed. Finally, molecular switches embedded in self-assembled monolayers (SAMs) and single molecule junctions are addressed. PMID:25757483

  18. Efficiency aspects of vector control applied to synchronous reluctance motors

    SciTech Connect

    Fletcher, J.E.; Williams, B.W.; Green, T.C.

    1995-12-31

    Core losses in a synchronous reluctance machine are modeled. The empirical model obtained is used to implement a control scheme to compensate for equivalent core loss currents. This enables accurate control of the magnetizing currents, hence torque. Efficiency over the base speed operating range of the machine is compared for two different vector control schemes. Methods of triplen series injection for vector controllers are discussed and a new method proposed. The new technique has advantages in terms of overall triplen content and computational requirements. Inductance ripple in the machine is estimated using direct torque ripple measurements and incorporated in a machine model valid for low speed operation.

  19. 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.

  20. 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.

  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. Switch wear leveling

    SciTech Connect

    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.

  4. Magnetically nonlinear and anisotropic iron core model of synchronous reluctance motor

    NASA Astrophysics Data System (ADS)

    Štumberger, G.; Štumberger, B.; Dolinar, D.

    2003-01-01

    The magnetically nonlinear and anisotropic iron core model of a synchronous reluctance motor (SRM) is presented. The iron core model is given by the current-dependent flux linkages and their partial derivatives. It is included in a dynamic SRM model and confirmed through the comparison of measured and calculated results in the case of current-controlled linear synchronous reluctance servomotor.

  5. Passive adaptive control of chaos in synchronous reluctance motor

    NASA Astrophysics Data System (ADS)

    Wei, Du-Qu; Luo, Xiao-Shu

    2008-01-01

    The performance of synchronous reluctance motor (SynRM) degrades due to chaos when its systemic parameters fall into a certain area. To control the undesirable chaos in SynRM, a passive control law is presented in this paper, which transforms the chaotic SynRM into an equivalent passive system. It is proved that the equivalent system can be asymptotically stabilized at the set equilibrium point, namely, chaos in SynRM can be controlled. Moreover, in order to eliminate the influence of undeterministic parameters, an adaptive law is introduced into the designed controller. Computer simulation results show that the proposed controller is very effective and robust against the uncertainties in systemic parameters. The present study may help to maintain the secure operation of industrial servo drive system.

  6. Position tracking control of a synchronous reluctance motor

    SciTech Connect

    Geoghan, A.J.; Carroll, J.J.

    1995-12-31

    The synchronous reluctance (SynR) motor is an attractive candidate for high-performance servo drive systems for various reasons. An integrator back-stepping technique is used to design a trajectory tracking control strategy for SynR motors driving inertial loads. A d-q model which describes the dynamical behavior of the SynR motor is introduced; based on this model, a voltage level controller is proposed which theoretically provides globally uniform asymptotically stable (GUAS) motor trajectory tracking given exact model knowledge and full state feedback (i.e., rotor position, velocity, and the per phase winding currents). The performance of the proposed voltage level controller is verified using computer simulation.

  7. 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.

  8. High-speed synchronous reluctance machine for flywheel applications

    NASA Astrophysics Data System (ADS)

    Hofmann, Heath Fred

    1998-12-01

    This thesis presents a synchronous reluctance motor/alternator design for a flywheel energy storage system. The goal of this project is to provide an inexpensive alternative to permanent magnet machines in this application. Key design criteria for the machine are high power output at high speeds with high efficiency and low rotor losses. The proposed rotor design consists of alternating layers of ferromagnetic and nonmagnetic steels which are bonded together using a high-strength bonding process such as brazing or explosive bonding. Analytical expressions are developed to calculate the direct and quadrature inductances, as wen as maximum output torque and maximum-power-factor torque, of this design. These expressions are then used to design rotors with optimized performance. A two-dimensional finite element simulator has been developed in MATLAB which calculates the steady-state eddy currents induced in the rotor at a given operating point. Results from the simulator suggest that a machine design with manageable rotor losses can be achieved. Stator and rotor design criteria are developed and combined in the formulation of a design process for high-speed synchronous reluctance machines. Two prototype machines, designed to provide 60kW over a speed range of 24,000--48,000rpm, have been constructed along with two 400V , 200A inverters. A stator-flux-oriented torque controller with an optimal-efficiency algorithm has been developed to drive the machines. Experimental results largely validate the design process, except that core losses in the stator iron were significantly higher than expected. Nevertheless, efficiencies of up to 91% were achieved at a 10kW, 10,000rpm operating point with estimated rotor losses less than 0.5% of total input power.

  9. Switching antipsychotic therapy: what to expect and clinical strategies for improving therapeutic outcomes.

    PubMed

    Lambert, Tim J

    2007-01-01

    When a patient taking an antipsychotic is not experiencing symptomatic remission, or is experiencing adverse effects (AEs) that are intolerable or damaging to his or her physical health, a change in medication may be the best path to a good outcome. However, many clinicians are reluctant to switch medications in all but the clearest cases of failure. This reluctance is intensified by the occurrence of AEs caused by transitioning patients too rapidly between agents with different receptor-binding profiles. Emergent antipsychotic-switching syndromes include the "withdrawal triad," comprised of cholinergic rebound, supersensitivity psychosis, and emergent withdrawal dyskinesias (and other motor syndromes). More recently, another element has been observed consistent with an activation syndrome. This activation syndrome may occur as a consequence of switching from highly sedative agents or as a consequence of initial prodopaminergic drive. All of these effects can be minimized by careful planning of gradual switch procedures and judicious use of adjunctive medications. PMID:17650054

  10. A tubular flux-switching permanent magnet machine

    NASA Astrophysics Data System (ADS)

    Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

    2008-04-01

    The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

  11. 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.

  12. 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.

  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. PMID:23896582

  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. Hysteresis modeling of synchronous reluctance motor considering PWM input voltage

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Kim, J. C.; Hyun, D. S.

    2000-01-01

    This paper deals with the hysteresis characteristics analysis in PWM fed synchronous reluctance motor (SynRM) using a coupled finite element method (FEM) and Preisach's modeling, which is presented to analyze the characteristics under the effect of saturation and hysteresis loss. With regard to the PWM characteristics, a vector control inverter is combined with an analysis tool. Also, a moving mesh technique is used with regard to rotation due to velocity. The focus of this paper is the applied method of Preisach modeling for rotating machines and the characteristics analysis of a SynRM using the proposed method of analysis. For the propriety of proposed method of analysis, TMS320C31 DSP-installed experimental devices are used. And then, computer simulation and experimental result for the i- λ loci, speed, current response, show the propriety of the proposed method. The characteristic analysis is performed in relation to the maximum efficiency condition for a SynRM in simulation and experiment.

  16. Self-protecting solid state isolated switch

    NASA Technical Reports Server (NTRS)

    Hoffman, A. C.; Gooder, S. T.

    1974-01-01

    Solid state switch has following capabilities: (1) Hybrid or IC from compatible with direct mounting on solar array substrate; (2) Continuous signal is not required to hold it in either on or off state; (3) Separate signal lines for on and off control; (4) Electrically isolated from input signals; and (5) Current surges will not cause switch failure.

  17. 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.

  18. 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.

  19. 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. PMID:24661467

  20. 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

  1. 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. PMID:26469271

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. DNAzyme-based magneto-controlled electronic switch for picomolar detection of lead (II) coupling with DNA-based hybridization chain reaction.

    PubMed

    Zhuang, Junyang; Fu, Libing; Xu, Mingdi; Zhou, Qian; Chen, Guonan; Tang, Dianping

    2013-07-15

    A novel magneto-controlled electrochemical DNA biosensor is designed for the ultrasensitive detection of lead coupling a lead-specific DNAzyme with DNA-based hybridization chain reaction (HCR). To construct such a magnetic lead sensor, DNAzyme-based molecular beacons, selective to cleavage in the presence of Pb(2+), are initially immobilized onto magnetic beads, which were used as the recognition elements. Upon addition of target lead, catalytic cleavage of substrate DNA segments in the double-stranded DNAzymes results in the capture of the initiator strands via the conjugated catalytic strands on magnetic beads. The captured DNA initiator strands trigger the hybridization chain reaction between two alternating hairpin DNA structures labeled with ferrocene to form a nicked double-helix on the magnetic beads. Numerous ferrocene molecules are formed on the neighboring probes, each of which produces an electrochemical signal within the applied potential. Under optimal conditions, the electrochemical signal of the magnetic lead sensor increases with the increasing lead level in the sample, and exhibits a linear response over a Pb(2+) concentration range of 0.1-75 nM with a detection limit of 37 pM. Quantitative measurement of Pb(2+) in the complex sample demonstrates the selectivity of the sensor scheme and points favorably to the application of such technologies to the analysis of environmental samples. The unique combination of a DNAzyme with hybridization chain reaction makes it possible to change the DNAzyme to select for other compounds of interest. This work represents the initial steps toward the creation of a robust field sensor for lead in groundwater or drinking water. PMID:23454343

  9. 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.

  10. 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.

  11. 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.

  12. Design and simulation of a smart optically controlled high-power switch based on a Si/SiC hybrid device structure

    NASA Astrophysics Data System (ADS)

    Bhadri, Prashant; Sukumaran, Deepti; Dasgupta, Samhita; Beyette, Fred R., Jr.

    2001-11-01

    In avionic systems, data integrity and high data rates are necessary for stable flight control. Unfortunately, conventional electronic control systems are susceptible to electromagnetic interference (EMI) that can reduce the clarity of flight control signals. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Fly-by-Light in avionic systems reduces electromagnetic interference hence improving the clarity of the control signals. A hybrid approach combining a silicon photoreceiver module with a SiC power transistor is proposed. The resulting device uses a 5 mW optical control signal to produce a 150 A current suitable for driving an electric motor.

  13. Characteristic analysis of permanent magnet-assisted synchronous reluctance motor for high power application

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ho; Jang, Young-Jin; Hong, Jung-Pyo

    2005-05-01

    In this paper, finite element analysis for a permanent magnet-assisted synchronous reluctance motor (PMASynRM) is presented and the inductance, torque characteristics analysis is performed under the effect of saturation. Comparisons are given with inductance and torque characteristics of normal synchronous reluctance motor (SynRM) and those according to quantity of residual flux density (0.1-0.4T) in PMASynRM, respectively. Comparisons are given with output characteristics of normal SynRM and those of PMASynRM, according to load, respectively. It is confirmed that the proposed model results in high output power performance.

  14. 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

  15. Peer Feedback in an Undergraduate Programme: Using Action Research to Overcome Students' Reluctance to Criticise

    ERIC Educational Resources Information Center

    McMahon, Tim

    2010-01-01

    Within an undergraduate programme, a four-year, action research project implemented, evaluated and refined a regime of peer assessment focused on generating high-quality peer feedback. Changes in structure and process transformed a system that had initially been characterised by a reluctance to criticise fellow students into one that produced…

  16. Disrupting Communities of Practice? How "Reluctant" Practitioners View Early Years Workforce Reform in England

    ERIC Educational Resources Information Center

    Payler, Jane K.; Locke, Rachel

    2013-01-01

    This article reports on the views of early years practitioners in England from settings that were identified as "reluctant to engage" with one of the government's key policies, the introduction of Early Years Professional Status (EYPS), to drive forwards workforce reform. Focus groups, interviews and a survey were undertaken in 2009 with 35…

  17. 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…

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

    DOE PAGESBeta

    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 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

  19. 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…

  20. Countering Science Reluctance in Elementary Science Education: Contrasting Approaches via Action Research.

    ERIC Educational Resources Information Center

    Hodson, Derek

    2002-01-01

    Describes and evaluates the work of an action research group established to address some of the problems associated with teaching science in elementary schools, in particular what has been described as 'science reluctance' or, in its more extreme form, 'science phobia'. Explains how an elementary school teacher replaced science teaching with…

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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 work 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. 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. 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…

  3. 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…

  4. A New Analysis about Efficient Drive of Synchronous Reluctance Motors with Core Losses

    NASA Astrophysics Data System (ADS)

    Shinnaka, Shinji; Mukai, Taisuke

    This paper gives a new analysis for efficient drive of synchronous reluctance motors with core loss. The optimal current trajectory that minimizes totally copper and iron losses is newly and analytically derived. And it is shown that the optimal trajectory is a straight line tilting to q-axis with the speed.

  5. 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).

  6. 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…

  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. Nanoelectromechanical contact switches

    NASA Astrophysics Data System (ADS)

    Loh, Owen Y.; Espinosa, Horacio D.

    2012-05-01

    Nanoelectromechanical (NEM) switches are similar to conventional semiconductor switches in that they can be used as relays, transistors, logic devices and sensors. However, the operating principles of NEM switches and semiconductor switches are fundamentally different. These differences give NEM switches an advantage over semiconductor switches in some applications -- for example, NEM switches perform much better in extreme environments -- but semiconductor switches benefit from a much superior manufacturing infrastructure. Here we review the potential of NEM-switch technologies to complement or selectively replace conventional complementary metal-oxide semiconductor technology, and identify the challenges involved in the large-scale manufacture of a representative set of NEM-based devices.

  9. 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.

  10. 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.