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1

Effects of 22 MeV protons on single junction and silicon controlled rectifiers  

NASA Technical Reports Server (NTRS)

The effects of 22-MeV protons on various types of silicon single junction and silicon controlled rectifiers were investigated. The results show that low-leakage devices and silicon controlled rectifiers are the most susceptable to radiation damage. There are also differences noted between single junction rectifiers of the same type made by different manufacturers, which emphasizes the need for better selection of devices used in spacecraft.

Beatty, M. E., III

1972-01-01

2

Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles  

NASA Technical Reports Server (NTRS)

The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

Gourash, F.

1984-01-01

3

Sliding mode control for three phase rectifiers  

Microsoft Academic Search

A sliding mode control for a boost type three phase rectifier is presented. A new mathematical model whose state variables are the amplitude and the phase of the input current is achieved. Several problems related to the controller design are dealt with: a sliding manifold shaping which avoids the absence of permissible control configurations during start up operating conditions is

Pompeo Marino; Francesco Vasca

1995-01-01

4

Analysis of three phase controlled rectifier with current active filter  

Microsoft Academic Search

The subject of this paper is the analysis of three-phase rectifiers with active filters. The new concept of three-phase controlled rectifier input current filtering is proposed and analysed. A modified technique for input current and output voltage control are presented. The simple hysteresis-band current control PWM method ensures a nearly sinusoidal input current with low harmonic content. Applying an additional

W. Koezara; P. Biloskorski

1996-01-01

5

Apparatus for Controlling the Firing of Rectifiers in Polyphase Rectifying Circuits.  

National Technical Information Service (NTIS)

A polyphase rectifier is controlled with precision by a circuit that filters and shifts a reference signal associated with each phase and that starts a ramp signal at a zero crossing of the shifted reference signal. The difference between the ramp signal ...

R. J. Yarema

1979-01-01

6

Comparison of Thyristor Rectifier Characteristics with Different Gate Control Systems.  

National Technical Information Service (NTIS)

Some thyristor gate control systems both synchronous and nonsynchronous ones are described. The experimental results of supply voltage asymmetry influence on spectral contents of rectified. output voltage are quoted. Dynamic and frequency responses of the...

V. Gula A. A. Cherepakhin

1982-01-01

7

Hybrid Digital Control for Three Phase Rectifier Inverter System  

Microsoft Academic Search

A DSP based digital control platform for a rectifier-inverter system built in the laboratory is presented and described in this paper. The digital platform offers the opportunity to test different control algorithms, of which the discrete PI control, a state feedback based dead beat control algorithm and digital hysteresis controllers have been the focus. An optimum digital control algorithm needs

H. Gueldner; S. Mohan; J. Losansky; M. Rentzsch

2006-01-01

8

Some Basic Physical Properties of Silicon and How They Relate to Rectifier Design and Application  

Microsoft Academic Search

The saturation range and the avalanche range of the reverse characteristic of a silicon rectifier and how these regions vary qualitatively with temperature and bulk characteristics of the silicon used are discussed. Also some reasons why these characteristics may vary from theoretical values are given. The forward current is discussed from the standpoint of the resistive component and conductivity modulation.

G. Finn; R. Parsons

1956-01-01

9

Simplified control of a three-phase PWM rectifier  

Microsoft Academic Search

A simple algorithm to control the PWM rectifier has been presented. Harmonics and unbalance in the AC-side line currents are compensated and the DC-bus voltage is regulated. The power factor of the compensated line currents is high. The algorithm may be used unmodified to control an active power filter. Simulation and experimental results have been presented to validate the control

S. R. Naidu; D. A. Fernandes; K. P. Medeiros

2011-01-01

10

Development of PI controller for battery charger using PFC rectifier  

Microsoft Academic Search

This paper illustrated simulation evaluations of a PI Controller for battery Charger employing Power Factor Correction (PFC) rectifier using MATLAB Simulink software packages and was compared with hardware prototype. The proposed system has been used single-phase incorporated with proportional-integral control technique to give appropriate compensation to resolve problems caused by the load such as current displacement, current harmonics and to

M. N. M. Hussain; M. F. M. Idris; I. Intan Rahayu; K. H. Mustafar; D. Nor Salwa; O. Nor Azlan; R. Rosfariza

2010-01-01

11

Frequency-Controlled LCC Resonant Converter with Synchronous Rectifier  

Microsoft Academic Search

This paper presents the theoretical analysis and experimental results for a frequency controlled LCC resonant converter. A prototype based on LCC resonant converter employing resonant gate drive synchronous rectifier is constructed to validate the theoretical analysis. The experimental results are in good agreement with the theoretical predictions.

Yu Ma; Xiaogao Xie; Zhaoming Qian

2007-01-01

12

Repetitive controlled three-phase reversible PWM rectifier  

Microsoft Academic Search

In this paper, a repetitive current control scheme for three-phase reversible PWM rectifier is proposed. The proposed control scheme is of typical dual-loop structure: inner AC current loop with plug-in repetitive plus feedback deadbeat controller, and outer DC voltage loop with PI controller. The unit power factor and constant DC bus voltage are obtained under load disturbance. Simulation results are

Keliang Zhou; Danwei Wang; Guangyan Xu

2000-01-01

13

A linearization voltage control strategy of three-phase PWM rectifier  

Microsoft Academic Search

In the double closed loops control strategy of three-phase voltage source PWM rectifier in the synchronous reference frame, the linear PI control is usually adopted in the voltage control loop, which cannot reflect the nonlinear nature of the PWM rectifier, and restricts the systempsilas control performance. According to the analyses on the voltage equation of the PWM rectifier, a voltage

Yanping Zhong; Yaojun Chen; Dan Chen

2008-01-01

14

Average current control of three-phase PWM boost rectifier  

Microsoft Academic Search

Average current control of three-phase PWM boost rectifiers with three linear current compensators and six-step PWM is a very attractive solution for its simplicity. The performance of the closed-loop control depends on the compensator design. This paper presents a modeling, analysis and design procedure for the average current control scheme. The current compensator design is verified experimentally on a high-frequency

Silva Hiti; Dusan Borojevic; Ravindra Ambatipudi; Richard Zhang; Yimin Jiang

1995-01-01

15

A fuzzy-logic-based controller for active rectifier  

Microsoft Academic Search

This paper presents a current-sensorless active rectifier specifically designed for low-cost applications. Both the control and the modulation use fuzzy logic. A simple model of the system is given in order to explain the current feedforward control using fuzzy logic and the fuzzy-logic-based modulation, then, the new algorithm is analyzed looking for high performance even using small passive elements and

Carlo Cecati; Antonio Dell' Aquila; Marco Liserre; Antonio Ometto

2003-01-01

16

Class D current-driven transformer center-tapped controllable synchronous rectifier  

Microsoft Academic Search

We present analysis and experimental results for a phase-controlled, synchronous, transformer center-tapped rectifier. The rectifier is driven by a resonant inverter. A digital control adjusts the phase in the driver of the rectifier MOSFET's. The output voltage is regulated while maintaining a 94% maximum and a 80% minimum efficiency for a 30% line swing, and 50% efficiency for a load

Marian K. Kazimierczuk; Mark J. Mescher; Roger M. Prenger

1996-01-01

17

Silicon carbide pinch rectifiers using a dual-metal Ti-Ni2Si Schottky barrier  

Microsoft Academic Search

The electrical characterization of dual-metal-planar Schottky diodes on silicon carbide is reported. The devices were fabricated on both 6H- and 4H-SiC by using titanium (Ti) and nickel silicide (Ni2Si) as Schottky metals. These rectifiers yielded the same forward voltage drop as the Ti diodes and leakage current densities comparable to those of the Ni2Si diodes. The reduction of the reverse

Fabrizio Roccaforte; Francesco La Via; Antonino La Magna; Salvatore Di Franco; Vito Raineri

2003-01-01

18

Comparison of Ti and Pt silicon carbide Schottky rectifiers  

Microsoft Academic Search

This paper describes the fabrication and characterization of high breakdown voltage titanium and platinum Schottky contacts to silicon carbide for high temperature and high frequency applications. Diodes fabricated with both Pt and Ti showed excellent on-state conduction characteristics with forward voltage drop of ~1.1 V at 100 A\\/cm2 for a temperature range of 25°C to 200°C. The reverse I-V characteristics

M. Bhatnagar; H. Nakanishi; P. K. Mclarty; B. J. Baliga; B. Patnaik; N. Parikh

1992-01-01

19

Modelling a single phase voltage controlled rectifier using Laplace transforms  

NASA Technical Reports Server (NTRS)

The development of a 20 kHz, AC power system by NASA for large space projects has spurred a need to develop models for the equipment which will be used on these single phase systems. To date, models for the AC source (i.e., inverters) have been developed. It is the intent of this paper to develop a method to model the single phase voltage controlled rectifiers which will be attached to the AC power grid as an interface for connected loads. A modified version of EPRI's HARMFLO program is used as the shell for these models. The results obtained from the model developed in this paper are quite adequate for the analysis of problems such as voltage resonance. The unique technique presented in this paper uses the Laplace transforms to determine the harmonic content of the load current of the rectifier rather than a curve fitting technique. Laplace transforms yield the coefficient of the differential equations which model the line current to the rectifier directly.

Kraft, L. Alan; Kankam, M. David

1992-01-01

20

Design and implementation of H? controller for three-phase PWM rectifiers  

Microsoft Academic Search

For the three-phase pulse-width modulated (PWM) rectifiers, the controller's performance can be influenced by the mathematic model error, parameter variation and external disturbances, etc. This paper presents a robust H? control method for the PWM rectifiers to improve the control performance. The outer voltage loop controller and the inner current loop controller are designed separately. Based on the mathematical model

Rui-wen Yu; Hui Zhang; Guo-jun Tan

2010-01-01

21

Decoupled State-Feedback and Sliding-Mode Control for Three-Phase PWM Rectifier  

Microsoft Academic Search

A nonlinear mathematical model of three-phase voltage source PWM rectifier is established in the dq rotating frame. Aiming at the poor dynamic performance of conventional PI controlled three-phase PWM rectifier, a control system with double close-loops of voltage and current is designed based on the mathematical model of 3-phase PWM rectifier. A sliding-mode control algorithm on synchronous rotating reference frame

Zhi Zhang; Yunxiang Xie; Jiangyuan Le; Lin Chen

2009-01-01

22

Selective harmonic elimination for cascaded H-bridge rectifiers based on indirect control  

Microsoft Academic Search

In this paper, a selective harmonic elimination pulsewidth modulation (SHE-PWM) method is introduced for multilevel cascaded H-bridge rectifiers. The indirect control strategy is utilized for control of the multilevel rectifier, where it does not need any current sensor and the system reliability increases by this way. Using the proposed control strategy and the modulation technique, a controllable power factor with

A. Marzoughi; H. Iman-Eini

2012-01-01

23

Techniques for minimizing the input current distortion of current-controlled single-phase boost rectifiers  

Microsoft Academic Search

Techniques for minimizing the input current distortion of current-controlled single-phase boost rectifiers are described. The switching patterns of several boost rectifiers are examined to identify the nature of their input current waveforms. This analysis is used to examine the low-frequency current distortion levels, and hence the power quality, associated with the rectifiers. A PWM (pulse width modulation) strategy that selectively

John C. Salmon

1993-01-01

24

Simulation of Three-Phase Voltage Source PWM Rectifier Based on Direct Current Control  

Microsoft Academic Search

This paper is concerned with the design and simulation of a pulse width modulation (PWM) rectifier for three-phase Permanent Magnetic motor drive. Based on the mathematical model of PWM rectifier, the dual-close-loop engineering design with decoupled feed-forward control is applied in the 3-phase voltage source rectifier. The objective to be reached is to realize unity power factor at the input

Xu Wang; Kaizheng Huang; Shijie Yan; Bin Xu

2008-01-01

25

Instantaneous switch state fuzzy vector controller for 3-phase switch controlled rectifiers  

Microsoft Academic Search

Conventional feedback control of a switch controlled 3-phase rectifier usually utilises PI control in the forward path. Studies have shown that fuzzy logic control (FLC) can provide advantages when power system and other parameters change in a nonlinear and nonpredictable way. In microprocessor control applications power semiconductor switching speeds are often limited by the microprocessor calculation times. This paper studies

K. Hoffman

1998-01-01

26

Direct power control for three-phase PWM rectifier with active filtering function  

Microsoft Academic Search

A novel virtual flux based direct power control space vector modulated (DPC-SVM) for 3-phase PWM rectifier with compensation of higher harmonics function is presented. The active and reactive power is used as a control variables for the PWM rectifier and active filtering operation. As a result several coordinate transformations are eliminated. Simulated and experimental steady state and dynamic performance for

Mariusz Cichowlas; Mariusz Malinowski; Marian P. Kazmierkowski; Frede Blaabjerg

2003-01-01

27

Modeling and control of three phase rectifier with electronic smoothing inductor  

Microsoft Academic Search

This paper presents a simple, direct method for deriving the approximate, small-signal, average model and control strategy for three-phase diode bridge rectifier operating with electronic smoothing technique. Electronic smoothing inductor (ESI) performs the function of an inductor that has controlled variable impedance. This increases power factor (PF) and reduces total harmonic distortions (THDs) in mains current. The ESI based rectifier

Yash Veer Singh; Peter Omand Rasmussen; Torben Ole Andersen; Hamidreza Shaker

2011-01-01

28

Full discrete sliding mode controller for three phase PWM rectifier based on load current estimation  

Microsoft Academic Search

This paper presents a novel full discrete sliding mode controller for voltage-sourced three phase rectifier to improve its dynamic response under the load and dc link voltage variation. Using the concept of power balance in three phase rectifier, the sliding mode controller for dc link voltage regulation is derived. Also, in order to avoid the additional load current sensor, a

Jin Ye; Xu Yang; Haizhong Ye; Xiang Hao

2010-01-01

29

Modeling and simulation of a digitally controlled active rectifier for power conditioning  

Microsoft Academic Search

The authors describe a single-phase active rectifier that provides an input AC current with unity displacement power factor and 3% total harmonic distortion (THD). The goal is to devise a rectifier to compensate for current harmonics and to improve the power factor of the line current. A closed-loop current control is proposed which will force the AC line current to

Ray Hudson; Soonwook Hong; Richard Hoft

1991-01-01

30

Efficiency Improvement of a Gas Engine Cogeneration System by Power Factor Control with an IGBT Rectifier  

Microsoft Academic Search

Improvement of the efficiency of a 1 kW household type gas engine cogeneration system is investigated. We propose two approaches. One is the power factor control of the synchronous generator by using an IGBT rectifier instead of a diode rectifier to improve the generator efficiency. This approach enables us to reduce the copper losses in the generator windings by reducing

Y. Miura; S. Kokubo; D. Maekawa; T. Ise

2007-01-01

31

Discrete-time Model Following Control of Inverter with Rectifier Load  

NASA Astrophysics Data System (ADS)

Electronic apparatus, such as a computer, are a capacitor input type rectifier load for a power supply. The rectifier load causes the fact that a power source voltage waveform is distorted. This paper describes the output voltage characteristic of the single phase PWM inverter applied a discrete-time model following control to the rectifier load. First the rectifier load model of a discrete time system is considered. Next, the discrete- time model following control system used for this load is described. Then, a simulation result and an experimental result are examined. The simulation results is shown that this method has robustness to the load change. The experimental system consists of an inverter controlled by a digital signal processor (DSP) and the rectifier load. The validity of a simulation result is shown by the experiment.

Umemura, Atsushi; Haneyoshi, Toshimasa; Saito, Yukio; Harashima, Fumio

32

Power control of three-phase PWM rectifier for microturbine  

Microsoft Academic Search

Microturbine generator system is one of the most promising distributed generation systems because it is small, efficient and mobile. When it is running, the high-frequency alternating current of permanent magnet synchronous generator generating must be rectified and inverted into 50Hz AC to meet the user requirements. Normally, the diode rectifier is used. When we need to regulate voltage, the DC\\/DC

Shijie Yan; Xu Wang; Yao Li

2010-01-01

33

Comparison of current control techniques for single-phase voltage-source PWM rectifiers  

Microsoft Academic Search

This paper presents two current control techniques for single-phase voltage-source PWM rectifiers. The PI controller is compared with the resonant controller. In addition, a compensating method to eliminate input current distortion caused by supply voltage harmonics for the resonant control is proposed. Finally, the differences in the performance of the two controllers in a single-phase PWM rectifier are investigated by

Fen Li; Yunping Zou; Wei Chen; Jie Zhang

2008-01-01

34

Closed loop input current control of a hybrid 12-pulse rectifier  

Microsoft Academic Search

This paper presents a novel closed loop current control strategy for a hybrid 12-pulse rectifier that uses a two-switch boost stage for output voltage regulation. Unlike previous attempts to mitigate input current distortion, e.g. by injecting voltages on the rectifier output side in open loop control mode, this new closed loop current control scheme directly controls the input current space

J. Biela; D. Hassler; J. Schonberger; J. W. Kolar

2008-01-01

35

Adaptive fuzzy control of a single-phase sinusoidal rectifier with step-up\\/down characteristics  

Microsoft Academic Search

This paper proposes an adaptive fuzzy logic controller for feedback output voltage control of a single-phase sinusoidal rectifier with step-up\\/down characteristics. These rectifiers, with a sliding mode current controller, ensure a near unity power factor operation and an input current with low harmonic content. The reference of the current controller is a sinusoidal waveform whose amplitude is modulated by the

Tito G. Amaral; V. F. Pires; M. Crisostomo; J. F. Silva

2000-01-01

36

Modeling and power quality enhancement to AC drives based on synchronous PI current control technology of PWM rectifier  

Microsoft Academic Search

This paper researches the performance analysis of a power quality enhancement rectifier fed vector control induction motor (VCIM) for electric driving application and presents a power quality enhancement test system to AC drives fed by PWM rectifier using synchronous PI current control technique. The PWM rectifier provides the tested system for research on the power quality of grid. The induction

Chaoyong Guo; Fei Lin; Xiaojie You; Trillion Q. Zheng

2008-01-01

37

Simulation of Direct Current Controlled PWM Rectifier Feeding to Adjustable Speed Drives  

Microsoft Academic Search

The objective of this paper is to model and simulate a three-phase Voltage Source Pulse Width Modulation (PWM) Rectifier Based on Direct Current Control feeding an indirect vector controlled Induction Motor Drive (VCIM) and 3-Level SVM based PMSM Drive. Based on the mathematical model of PWM rectifier, the dual close loop engineering design with decoupled feed-forward control is applied in

T. Narasa Reddy; T. Purnachandra Rao; M. Dilip Kumar

2009-01-01

38

A vector controlled current-source PWM rectifier with a novel current damping method  

Microsoft Academic Search

Three-phase current-type pulse width modulation (PWM) rectifiers are becoming increasingly popular as the front-end converter unit in power electronic systems due to tighter electromagnetic compatibility (EMC) regulations. In this paper the control of the current source PWM rectifier in the synchronously rotating reference frame is discussed. A control system is presented in which the active and reactive power are independently

Mika Salo; Heikki Tuusa

2000-01-01

39

Modeling and Robust Control of a Three-Phase Buck+Boost PWM Rectifier (VRX-4)  

Microsoft Academic Search

The modeling and control of a three-phase three-switch buck-type rectifier system with integrated boost output stage (voltage range extended 4-switch rectifier) is analyzed in this paper. A cascaded multiloop control structure is presented that has the following features: constant output voltage for a wide input voltage range and stepwise changes of load; sinusoidal input currents in phase with the mains

Thomas Nussbaumer; Guanghai Gong; Marcelo Lobo Heldwein; Johann W. Kolar

2008-01-01

40

Discrete-time sliding mode direct power control for three-phase rectifiers  

Microsoft Academic Search

In this paper a new discrete-time sliding mode control scheme for three-phase PWM rectifiers is proposed. Active and reactive powers are directly controlled using a virtual-flux oriented reference frame. Robustness of the proposed methodology to filter inductance variation is shown. Simulation results of a rectifier connected to a large power system are presented to compare the performances of the proposed

Felipe Camboim; Roberto Dias Filho; Francisco Neves; Emilio Bueno; Marcelo Cavalcanti

2009-01-01

41

Adaptive nonlinear control of a three-phase three-level neutral point clamped rectifier  

Microsoft Academic Search

This paper presents a control strategy for a three-phase three-level neutral-point-clamped boost rectifier, which consists of applying an adaptive nonlinear control. The exact nonlinear multiple-input multiple-output state space model of the rectifier was obtained in the (d,q,0) reference frame using the power balance between the input and output sides. Applying a change of coordinates and nonlinear feedback linearization technique to

L. Yacoubi; F. Fnaiech; L. A. Dessaint; K. Al-Haddad

2001-01-01

42

An integrated control method for three-level NPC based PWM rectifier-inverter  

Microsoft Academic Search

This paper presents a novel integrated control scheme for three-level neutral point clamped (NPC) based PWM rectifier-inverter. Two measures are taken to minimize the size of dc-bus capacitors which are expensive, bulky and have a lifetime limit. Firstly, the direct power control (DPC) for front-end three-level PWM rectifier is applied, which will provide better dynamic performance for the dc-link. Secondly,

Zhang Yingchao; Zhao Zhengming; Lu Ting; Jin Liping

2010-01-01

43

Research on control method of three-level NPC voltage source rectifier  

Microsoft Academic Search

In this paper, the mathematical model of three-phase four-wire three-level neutral-point-clamped (NPC) voltage source rectifier (VSR) using switching functions is founded and its operating principle analyzed. Then a new nonlinear control law based on Lyapunovpsilas stability theory for the PWM rectifier is presented. With this control law, the converter can be stabilized globally for handling large-signal disturbances, and exhibit good

Zhou Jinghua; Meng Yongqing; Li Zhengxi; Liu Kun

2008-01-01

44

Novel hybrid 12-pulse line interphase transformer boost-type rectifier with controlled output voltage  

Microsoft Academic Search

This paper describes two novel hybrid 12-pulse line interphase transformer rectifier systems with integrated single-switch or two-switch boost-type output stage. The boost stage allows controlling the output voltage to a constant value independent of line voltage or output power variations. In combination with low complexity and\\/or high reliability the hybrid rectifier concept therefore is of potential interest for supplying electrically

K. Mino; G. Gong; J. W. Kolar

2004-01-01

45

Synthesis of a nonlinear H? controller for a three-phase active rectifier  

Microsoft Academic Search

Switch-mode rectifiers have been proved as effective devices to supply steady dc power with improved power quality at ac mains. In this paper, we present a new control scheme, developed under the formulation of nonlinear theory, for three-phase pulsewidth modulation boost rectifiers to achieve unity-power-factor and dc-link voltage regulation with guaranteed robust performance. The closed-loop system is also shown to

Tzann-Shin Lee; Chieh-Jen Chang

2008-01-01

46

Research on three-phase PWM rectifier based on predictive control  

Microsoft Academic Search

PWM rectifier control system is designed, where predictive current control in two static reference frames is as current control method, voltage space vector pulse width modulation is pulse width modulation method, and traditional PI regulator is adopted as DC voltage control. This method has an advantage of quick response of hysteresis current control, the frequency of apparatus is fixed, and

Zheng Zheng; Cong Wang; Haijun Tao

2008-01-01

47

Nonlinear Control of a Single Phase Unity Power Factor Rectifier: Design, Analysis, and Experimental Results  

Microsoft Academic Search

This brief presents nonlinear control strategies for a single quadrant unity power factor rectifier. First, a standard average model is utilized to design an adaptive controller and exponential stability of the controlled system is demonstrated via a Lyapunov stability argument. It is shown that: (1) the initial output voltage needs to be sufficiently large to ensure boundedness of the system

V. M. Rao; A. K. Jain; K. K. Reddy; A. Behal

2008-01-01

48

An adaptive direct power control for three-phase pwm rectifier in the unbalanced case  

Microsoft Academic Search

In this paper, a model based controller is proposed that directly controls the instantaneous active and reactive power of a PWM rectifier in the unbalanced case. Instrumental for our developments is the expression of the source voltage in terms of both sequences, positive and negative, which allows a more complete description of the model. The controller incorporates an adaptation mechanism

G. Escobar; M. F. Martinez-Montejano; R. E. Torres Olguin; A. A. Valdez

2008-01-01

49

Nonlinear PID control of three-phase pulse width modulation rectifier  

Microsoft Academic Search

This paper proposes a nonlinear PID control strategy of three-phase voltage source pulse width modulation (PWM) rectifier based on predictive current control. The nonlinear controller is consisted of tracking differentiators (TD) and nonlinear combination of error. It improves DC voltage response velocity, restrains overshoot and enhances robustness against load change. In addition, the sinusoidal AC current and unity power factor

Liang Ma; Fei Lin; Xiaojie You; Trillion Q. Zheng

2008-01-01

50

Generalized Feedforward Control of Single-Phase PWM Rectifiers Using Disturbance Observers  

Microsoft Academic Search

This paper presents a generalized feedforward control scheme for a single-phase boost rectifier, operating with indirect current control, to improve the dynamic response of its output voltage against line and load disturbances, as well as for changes in the reference voltage. Digital implementation of the control method is discussed. A small-signal model of the converter system is presented. The stability

Rajesh Ghosh; G. Narayanan

2007-01-01

51

Control of Three-Phase PWM Rectifiers Using A Single DC Current Sensor  

Microsoft Academic Search

This paper presents a new current control method for three-phase pulse width modulation rectifiers with active power factor correction (PFC). Conventional three-phase PFC control re- quires sensing of at least two input phase currents. Since the input line must be isolated from the control circuitry, current transform- ers or Hall effects current sensors are required for sensing the phase currents,

Zhonghui Bing; Xiong Du; Jian Sun

2011-01-01

52

Indirect control for cascaded H-bridge rectifiers with unequal loads  

Microsoft Academic Search

In this paper, an indirect control strategy for multilevel cascaded H-bridge rectifiers is introduced. The indirect control does not need any current sensors, hence the system reliability increases. Using this method, controllable power factor with nearly sinusoidal ac current could be achieved. All dc link voltages are regulated to a constant reference voltage, even if they consume various amounts of

A. Marzoughi; H. Iman-Eini

2012-01-01

53

Development of a fuzzy logic controller for boost rectifier with active power factor correction  

Microsoft Academic Search

This paper presents the use of fuzzy logic to derive a practical control scheme for a boost rectifier with active power factor correction. The methodology integrates a fuzzy logic control technique in the feedback path and linear programming rule on controlling the duty cycle of the switch for shaping the input current waveform. The proposed approach avoids complexities associated with

Henry S. H. Chung; Eugene P. W. Tam; S. Y. R. Hui

1999-01-01

54

A New Robust Controller for a Three-Phase Three-Level NPC Rectifier  

Microsoft Academic Search

This paper presents a new control strategy for a three-phase, three-level, neutral point clamped (NPC) rectifier. The controller is a combination of three sub-controllers, one for each of the d-axis, q-axis and zero-sequence components of the converter dynamic model In the proposed control strategy, the zero-sequence and the q-axis sub-controllers are inner loop controllers, whereas the d-axis sub-controller acts as

A. F. Okou; M. Tarbouchi; D. Bouchard; A. A. Amoussou

2007-01-01

55

Predictive Direct Power Control of Three-Phase Pulsewidth Modulation (PWM) Rectifier Using Space-Vector Modulation (SVM)  

Microsoft Academic Search

In this paper, we present a direct power control (DPC) of three-phase pulsewidth modulation rectifier with constant switching frequency using space-vector modulation (SVM). The developed DPC scheme is based on the predictive control strategy to achieve direct control of instantaneous active and reactive power of the converter. For this purpose, at the beginning of each switching period, the required rectifier

Abdelouahab Bouafia; Jean-Paul Gaubert; Fateh Krim

2010-01-01

56

dq-control of high-power current source rectifiers utilizing Selective Harmonic Elimination  

Microsoft Academic Search

Selective harmonic elimination (SHE) is usually the preferred modulation technique for high power converters. When such modulation is used with current source rectifiers (CSR), control of the DC-link current and of the input displacement power factor is typically achieved by adjusting the amplitude and phase of the CSR modulation index. In this paper control of an SHE modulated CSR is

Matteo Tomasini; Ralph Feldman; Patrick Wheeler; Jon Clare; Christian Klumpner; Ushe Mupambireyi

2009-01-01

57

A novel and efficient control strategy for three-phase boost rectifiers  

Microsoft Academic Search

To date three-phase boost rectifiers, due to their high efficiency, good current quality and low EMI emissions are widely used in industry as power factor correction (PFC) converters. Performance criteria of these converters significantly improve with increasing the switching frequency, and highly depend on the control strategy used. This paper introduces a simple and fast control strategy for three-phase boost

D. Yazdani; A. R. Bakhshai; P. Jain

2003-01-01

58

New Stationary Frame Control Scheme for Three Phase PWM Rectifiers under Unbalanced Voltage Dips Conditions  

Microsoft Academic Search

A new stationary frame control scheme for three-phase pulse width modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage. The paper novelty is the development of a new current-reference calculation

D. Roiu; R. Bojoi; L. R. Limongi; A. Tenconi

2008-01-01

59

Single-phase high power factor rectifier based on PI controller with grey prediction  

Microsoft Academic Search

This paper presents a single-phase rectifier with power factor correction. The full-bridge converter is used in this circuit to perform bidirectional power flow capability. A novel control scheme based on grey prediction method is used to improve the system transient response. Two control loops are adopted in the system to obtain a constant DC bus voltage and achieve line current

Huann-Keng Chiang; Bor-Ren Lin; Kai-Tsang Yang

2004-01-01

60

Nonlinear partial state feedback controller for a single phase active rectifier  

Microsoft Academic Search

This paper presents a partial state feedback controller for an active rectifier to regulate dc output voltage and to guarantee a power factor close to unity. The partial information controller is based on the Exact Tracking Error Dynamics Passive Output Feedback (ETDPOF) technique in conjunction with an Immersion and Invariance based inductor current observer. Numerical simulations are presented to evaluate

Manuel Flota; Ricardo Alvarez-Salas; H. Rodriguez-Cortes; C. Nunez

2008-01-01

61

DC bus sensor fault tolerant control of single phase PWM rectifier for electrical traction  

Microsoft Academic Search

The paper deals with a dc bus voltage sensor fault tolerant control (FTC) for a single phase PWM rectifier used in electric traction application. FTC increases the availability and reliability of the system, since it allows fault detection and isolation (FDI) of faulty component and then control reconfiguration. Estimator and Luenberger observer are developed in order to generate residual for

Ahlem Ben Youssef; Sejir Khojet El Khil; Ilhem Slama-Belkhodja

2011-01-01

62

A critical review of ohmic and rectifying contacts for silicon carbide  

Microsoft Academic Search

For more than three decades, SiC has been investigated as a wide band gap semiconductor. This paper reviews ohmic and rectifying metal contacts on n- and p-type ?- and ?-SiC reported throughout that time period. Electrical characteristics, Schottky barrier heights (SBHs), thermal stability, and chemical reactions are discussed. Most metals formed very good rectifying contacts in the as-deposited condition on

Lisa M. Porter; Robert F. Davis

1995-01-01

63

Advanced Control Strategy for Single-Phase Voltage-Source Active Rectifier with Low Harmonic Emission  

NASA Astrophysics Data System (ADS)

This paper introduces the advanced control of single-phase voltage-source active rectifier. This control provide direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. Our proposed control strategy combines PR controller with feed-forward model and low-frequency harmonic compensator based on resonant controllers. Achieved experimental results show excellent converter behavior, where converter is fed by strongly distorted supply voltage.

Blahník, Vojt?ch; Peroutka, Zden?k; Talla, Jakub

2014-03-01

64

Bipolar Hvdc Transmission System Study: Development of Controlled Cascade Rectifier for Insulator Testing. Final Report.  

National Technical Information Service (NTIS)

This project constitutes a continuation of EPRI project 430-1 covering the power supply for insulator pollution testing. The aims of this project are to determine the circuit elements of a controlled cascade rectifier source to perform pollution tests; th...

Y. Beausejour F. A. M. Rizk

1980-01-01

65

Linear and Nonlinear Control Techniques for a Three-Phase Three-Level NPC Boost Rectifier  

Microsoft Academic Search

This paper deals with three control techniques for a three-phase three-level neutral-point-clamped (NPC) boost rectifier to study their relative performance. Linear, nonlinear, and nonlinear model reference adaptive control (MRAC) methods are developed to control power factor (PF) and regulate output and neutral point voltages. These controllers are designed in Simulink and implemented in real time using the DS1104 DSP of

Loubna Yacoubi; Kamal Al-Haddad; Louis-A. Dessaint; Farhat Fnaiech

2006-01-01

66

A Simple Analog Controller for Single-Phase Half-Bridge Rectifier  

Microsoft Academic Search

A simple analog controller is proposed for the single-phase half-bridge pulsewidth modulation rectifier to maintain near unity power factor at the input and balance the voltages across each half of the dc bus. The controller works in the principle of constant-frequency current programmed control. The required gating pulses are generated by comparing the input current with a linear and bipolar

Rajesh Ghosh; G. Narayanan

2007-01-01

67

PIR-based control for three-phase PWM rectifier with H-bridge load  

Microsoft Academic Search

In order to eliminate the pulsating instantaneous power of twice of the output voltage frequency in case of single-phase load, a proportional-integral-resonant (PIR) based controller is proposed in this paper for the PWM rectifier in both the dc-link voltage control loop and the ac current control loop. The resonant regulator is very suitable for tracking the ac component, which provides

Wang Jian; Li Yongdong; Zheng Yanwen; Yuan Xibo

2009-01-01

68

Input-output linearization and generalized PI control of a single-phase active multilevel rectifier  

Microsoft Academic Search

A two stages robust Generalized PI feedback controller for a single-phase active multilevel rectifier is proposed. The controller is based on the system modeled in the d-q synchronous reference frame. Based on input-output linearization theory a current controller that decouples the d-q components and compensates unknown perturbations is obtained. Performing a transformation of the system, stability of zero dynamics is

A. R. Rami?rez-Lo?pez; Nancy Visairo-Cruz; C. A. Nuñez-Gutie?rrez; J. J. Lira-Pe?rez; Hebertt Sira-Ramírez

2010-01-01

69

Paralleled DSP-based soft switching-mode rectifiers with robust voltage regulation control  

Microsoft Academic Search

This paper presents the current sharing and robust voltage regulation controls for paralleled digital signal processor-based soft switching-mode rectifiers (SSMRs). First, the design and implementation of single-module SSMRs are made. In dealing with the current control loop design of each SSMR module, the small-signal model is derived and used to design the current-controlled pulse-width modulation (PWM) scheme. As to the

Sheng-Hua Li; Chang-Ming Liaw

2004-01-01

70

DSP implementation of direct power control with constant switching frequency for three-phase PWM rectifiers  

Microsoft Academic Search

This paper proposes a novel and simple direct power control scheme for three-phase PWM rectifiers operated at constant switching frequency using space vector modulation (DPC-SVM). The active and reactive power is used as the pulse width modulated (PWM) control variables instead of the three-phase line currents usually used. Moreover, a line voltage sensors are replaced by virtual flux (VF) estimator.

Mariusz Malinowski; M. P. Kamierkowski

2002-01-01

71

Research on control strategy for Three-Phase PWM Voltage Source Rectifier  

Microsoft Academic Search

This paper first introduces the topology of three-phase PWM voltage source rectifier (VSR). Then the mathematical models in three-phase static and two-phase rotary coordinate system are built. Based on that theory and the voltage-oriented vector control's idea, the paper introduces a dual-channel closed-loop control strategy with current-inner-loop and voltage-outer-loop. Active power channel is aim to make DC side voltage remain

Yu Wang; Yanbo Che; K. W. E. Cheng

2009-01-01

72

Continuous and discrete variable-structure controls for parallel three-phase boost rectifier  

Microsoft Academic Search

We describe three nonlinear control schemes for a parallel three-phase boost rectifier consisting of two modules. The basic idea, however, can be extended to a system with N modules. All of the control schemes are developed in a synchronous frame. Moreover, each of the closed-loop power-converter modules operates asynchronously without any communication with the other module. Based on the dynamical

Sudip K. Mazumder

2005-01-01

73

Control of three-phase PWM rectifier under unbalanced input voltage conditions without sequential component extraction  

Microsoft Academic Search

Many methods for control of three-phase boost-type PWM rectifier under unbalanced input voltage conditions have been presented in the last two decades. Among these methods, the input-output-power-control (IOPC) method seems the most desirable one offering ripple-free dc bus voltage, low-distortion input currents and average unity power factor on the grid side. Most of the IOPC schemes adopt rotating frame and

Zixin Li; Ping Wang; Yaohua Li; Haibin Zhu; Fanqiang Gao

2010-01-01

74

Flatness-based voltage-oriented control of three-phase PWM rectifiers  

Microsoft Academic Search

Flatness-based control is applied to the three-phase PWM-rectifier in synchronous reference frame. The DC-link voltage and reactive current are shown to be flat outputs of the full-order system. Two different approaches are presented. At first the DC-link voltage is controlled directly. The second employs inner current loops. Feed forward design based on system flatness is shown and discussed. In many

J. Dannehl; F. W. Fuchs

2008-01-01

75

New Stationary Frame Control Scheme for Three-Phase PWM Rectifiers Under Unbalanced Voltage Dips Conditions  

Microsoft Academic Search

A new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented

Daniel Roiu; Radu Iustin Bojoi; Leonardo Rodrigues Limongi; Alberto Tenconi

2010-01-01

76

Design of mixed H? and optimal controller for three-phase PWM rectifiers  

Microsoft Academic Search

The mathematic model of three-phase pulse-width modulated (PWM) voltage rectifiers is nonlinear, strong coupling. And the mathematic model error, time-varying uncertainties and external disturbance will influence the performance of the system. This paper presents a linear quadratic regulator (LQR) for the inner current loop control without decoupling, and a robust H? control method for the outer voltage loop. For the

Hui Zhang; Guojun Tan; Minglian Zhang; Ruiwen Yu

2010-01-01

77

A nonlinear control method for three-phase three-level NPC rectifier  

Microsoft Academic Search

A nonlinear control strategy is proposed for the three-phase three-level NPC rectifier based on the feedback linearization theory. The proposed strategy can realize the decoupled control of active and reactive current of the VSR in the d-q frame. A strategy of changing the voltage adjusting coefficient to adjust the dwelling time of the positive and the negative small vectors to

Zhang Zhi; Xie Yun-xiang; Le Jiang-yuan; Chen lin

2009-01-01

78

Digital repetitive controlled three-phase PWM rectifier  

Microsoft Academic Search

In this paper, a digital repetitive control (RC) strategy is proposed to achieve zero tracking error for constant-voltage constant-frequency (CVCF) pulse width modulation (PWM) converters. The proposed control scheme is of \\

Keliang Zhou; Danwei Wang

2003-01-01

79

A novel simplified space-vector-modulated control scheme for three-phase switch-mode rectifier  

Microsoft Academic Search

A novel simplified control scheme for a three-phase switch-mode rectifier is proposed in this paper. The proposed control scheme is based upon a load-conductance rectifier controller, in which reference current signals are obtained. The goal to follow the reference current is converted to follow a reference voltage. A simplified control scheme utilizing space-vector modulation is developed to calculate the duty

Chern-Lin Chen; Che-Ming Lee; Rong-Jie Tu; Guo-Kiang Horng

1999-01-01

80

Synchronous PI current control technique for three-phase PFC rectifier for PMSG wind generation system  

Microsoft Academic Search

For rectification of the three-phase AC voltages of permanent magnetic synchronous generator (PMSG) applied to variable speed constant frequency wind generation, a synchronous PI current control technique is proposed based on a novel topology called three-phase PFC rectifier. It consists of three single-phase power factor correction (PFC) circuits, each of which is for one phase of PMSG. The stator alternating

Yingtao Ma; Xudong Sun; Jianyun Chai

2010-01-01

81

Analysis of three phase PWM buck rectifier under modulation magnitude and angle control  

Microsoft Academic Search

The analysis of the steady-state, dynamic, and small-signal performance of a three-phase AC\\/DC buck rectifier using pulse width modulation (PWM) with modulation magnitude and angle control is presented. General equations of the converter including switching discontinuities are derived and used for transient and dynamic simulations. From these nonlinear equations, using the concept of existence function and synchronous reference frame d-q-o

Olorunfemi Ojo; Ishwar Bhat

1993-01-01

82

Analysis and design of predictive control strategy for Sheppard-Taylor based PFC rectifier  

Microsoft Academic Search

In this paper CCM\\/CVM operation and modeling of the Sheppard-Taylor topology is reviewed and a predictive control strategy is applied for a Sheppard-Taylor-based power factor correction (PFC) rectifier. Compared to conventional boost or buck - boost PFCpsilas, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Consequently, the high

M. R. Abedi; F. Tahami

2008-01-01

83

Half-Controlled Boost Rectifier for Low-Power High-Speed Permanent-Magnet Generators  

Microsoft Academic Search

Literature reports several future portable and distributed power supplies in the watt-to-kilowatt range based on rotating machinery equipped with a variable-speed permanent- magnet generator. In order to generate a constant direct-current output voltage, an ultracompact highly efficient low-power recti- fier is required. A suitable concept, i.e., the half-controlled three- phase pulsewidth-modulation boost rectifier (HCBR), is analyzed in this paper. In

Daniel Krahenbuhl; Christof Zwyssig; Johann W. Kolar

2011-01-01

84

Control of Three-Phase Boost-Type PWM Rectifier in Stationary Frame Under Unbalanced Input Voltage  

Microsoft Academic Search

In the last decade, many methods for control of three-phase boost-type pulsewidth modulation (PWM) rectifier under unbalanced input voltage conditions have been studied and presented. These methods use the sequential components of input voltages, pole voltages, and input currents of the rectifier to analyze and control the instantaneous powers, of which dual (positive-sequence and negative-sequence rotating) frame control is the

Zixin Li; Yaohua Li; Ping Wang; Haibin Zhu; Congwei Liu; Wei Xu

2010-01-01

85

A Study of Dual-loop Control Scheme and Corresponding Neutral-point Voltage Balance Control Method for Three-level PWM Rectifiers  

Microsoft Academic Search

The mathematical model of the three-level PWM rectifiers is set up in this paper. By comparing it with the model of DC motors, some similarities are established. Based on the state feedback decoupling, the dual-loop close control scheme of DC motors is implemented to three-level PWM rectifiers. As a result, the three-level rectifier has favorable dynamic and steady state performance,

Lin Lei; Zhong Heqing; Deng Yu; Zhang Jie; Zou Yunping; She Xu

2009-01-01

86

A Superconducting Reversible Rectifier That Controls the Motion of Magnetic Flux Quanta  

NASA Astrophysics Data System (ADS)

We fabricated a device that controls the motion of flux quanta in a niobium superconducting film grown on an array of nanoscale triangular pinning potentials. The controllable rectification of the vortex motion is due to the asymmetry of the fabricated magnetic pinning centers. The reversal in the direction of the vortex flow is explained by the interaction between the vortices trapped on the magnetic nanostructures and the interstitial vortices. The applied magnetic field and input current strength can tune both the polarity and magnitude of the rectified vortex flow. Our ratchet system is explained and modeled theoretically, taking the interactions between particles into consideration.

Villegas, J. E.; Savel'ev, Sergey; Nori, Franco; Gonzalez, E. M.; Anguita, J. V.; García, R.; Vicent, J. L.

2003-11-01

87

Space-vector ?? modulator and sliding mode control of the three-phase buck type rectifier with freewheeling diode  

Microsoft Academic Search

This paper presents a vector based sliding mode control method for three-phase buck type three-phase rectifiers with freewheeling diode. This fast and robust technique uses sliding mode to generate ?? space-vector modulation, which forces the input line currents to track a suitable sinusoidal reference. A near unity power factor operation of the rectifier is obtained using a sinusoidal reference in

V. Ferngo Pires; J. Fernando Silva; G. D. Marques

2002-01-01

88

A direct power control scheme for three-phase PWM rectifiers based on sliding-mode variable structure control theory  

Microsoft Academic Search

A direct power control (DPC) scheme for three-phase PWM rectifier based on sliding-mode variable structure control theory is presented. Compared with the traditional PI controller, the proposed scheme is much more robust with better transient performance, lower total harmonic distortion (THD) and simpler tuning of parameters. Modeling and simulation done in MATLAB\\/SIMULINK environment shows that the proposed scheme is superior

Wanwei Wang; Huajie Yin; Lin Guan

2009-01-01

89

An Integrated Power-Efficient Active Rectifier With Offset-Controlled High Speed Comparators for Inductively Powered Applications  

PubMed Central

We present an active full-wave rectifier with offset-controlled high speed comparators in standard CMOS that provides high power conversion efficiency (PCE) in high frequency (HF) range for inductively powered devices. This rectifier provides much lower dropout voltage and far better PCE compared to the passive on-chip or off-chip rectifiers. The built-in offset-control functions in the comparators compensate for both turn-on and turn-off delays in the main rectifying switches, thus maximizing the forward current delivered to the load and minimizing the back current to improve the PCE. We have fabricated this active rectifier in a 0.5-?m 3M2P standard CMOS process, occupying 0.18 mm2 of chip area. With 3.8 V peak ac input at 13.56 MHz, the rectifier provides 3.12 V dc output to a 500 ? load, resulting in the PCE of 80.2%, which is the highest measured at this frequency. In addition, overvoltage protection (OVP) as safety measure and built-in back telemetry capabilities have been incorporated in our design using detuning and load shift keying (LSK) techniques, respectively, and tested.

Lee, Hyung-Min; Ghovanloo, Maysam

2011-01-01

90

Control-oriented modeling and robust control of a three-phase buck+boost PWM rectifier (VRX-4)  

Microsoft Academic Search

The modeling and control of a three-phase, three-switch buck-type rectifier system with integrated boost output stage (VRX-4) is analyzed in this paper. A cascaded multi-loop control structure is presented that has the following features: constant output voltage for a wide input voltage range and step-wise changes of load; sinusoidal input currents in phase with the mains voltages that also remain

T. Nussbaumer; G. Gong; M. L. Heldwein; J. W. Kolar

2005-01-01

91

Experimental validation of nonlinear and adaptive control strategies implemented on a 3-phase 3-level NPC boost rectifier  

Microsoft Academic Search

In this paper, the authors present detailed experimental validation of nonlinear and adaptive control strategies implemented on a 3-phase 3-level neutral point clamped (NPC) boost rectifier. These control strategies are developed to control power factor, output and neutral point voltages and also to reduce parametric variation and utility disturbance influences. These two control methods are designed and applied to the

Loubna Yacoubi; Kamal AI-Haddad; Farbat Fnaiech; L.-A. Dessaint

2004-01-01

92

Power factor control of a three-phase boost rectifier with specific power factor under asymmetrical conditions  

Microsoft Academic Search

A new current controller structure for the three-phase boost rectifier, using actual phase currents achieving both controllable input power factor and constant DC voltage under asymmetrical source voltages and\\/or unequal line impedances, is presented in this paper. All the control variables in the new scheme are AC signals instead of the DC signals used in the industry standard synchronous reference

Zhiqiao Wu; Olorunfemi Ojo

2005-01-01

93

Power balance control techniques applied to parallel AC to DC converters using single-phase SEPIC rectifier modules  

Microsoft Academic Search

Power balance control techniques applied to parallel AC to DC converters for single-phase SEPIC rectifier modules is presented. The analysis and simulation results of such system with nearly unity power factor using single voltage loop control and inductor current calculator for input current wave shaping and output voltage regulation have been shown. Each converter operates in continuous conduction mode and

U. Kamnarn; V. Chunkag

2004-01-01

94

A Pi-based control scheme for primary cascaded H-bridge rectifier in transformerless traction converters  

Microsoft Academic Search

Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue

Tao Xinghua; Li Yongdong; Sun Min

2010-01-01

95

Nanoscale Spin Seebeck Rectifier: Controlling Thermal Spin Transport across Insulating Magnetic Junctions with Localized Spin  

NASA Astrophysics Data System (ADS)

The spin Seebeck effect is studied across a charge insulating magnetic junction, in which thermal-spin conjugate transport is assisted by the exchange interactions between the localized spin in the center and electrons in metallic leads. We show that, in contrast with bulk spin Seebeck effect, the figure of merit of such nanoscale thermal-spin conversion can be infinite, leading to the ideal Carnot efficiency in the linear response regime. We also find that in the nonlinear spin Seebeck transport regime the device possesses the asymmetric and negative differential spin Seebeck effects. In the last, the situations with leaking electron tunneling are also discussed. This nanoscale thermal spin rectifier, by tuning the junction parameters, can act as a spin Seebeck diode, spin Seebeck transistor, and spin Seebeck switch, which could have substantial implications for flexible thermal and information control in molecular spin caloritronics.

Ren, Jie; Fransson, Jonas; Zhu, Jian-Xin

2014-06-01

96

DC Link Voltage and Supply-Side Current HarmonicsMinimization of Three Phase PWM BoostRectifiers Using Frequency Domain BasedRepetitive Current Controllers  

Microsoft Academic Search

This paper presents a digital plug-in frequency domain based repetitive control scheme for minimizing the odd order harmonics in the supply line side currents of the three phase pulsewidth modulation (PWM) boost rectifier under the distorted and unbalanced supply voltage conditions. Based on the mathematical model of the three-phase PWM boost rectifier under the generalized supply voltage conditions, the control

X. H. Wu; S. K. Panda; J. X. Xu

2008-01-01

97

Characteristics of the Inward Rectifier and Its Control by pH  

Microsoft Academic Search

Intracellular microelectrode recordings and a two-electrode voltage clamp have been used to characterize the current carried by inward rectifying K ÷ channels of stomatal guard cells from the broadbean, Vicia faba L. Superficially, the current displayed many features common to inward rectifiers of neuromuscular and egg cell membranes. In millimolar external K ÷ concentrations (K~), it activated on hyperpolarization with

MICHAEL R. BLAa-T

98

A novel control method for input output harmonic elimination of the PWM boost type rectifier under unbalanced operating conditions  

Microsoft Academic Search

This paper presents a new control strategy to improve the performance of the PWM boost type rectifier when operating under an unbalanced supply. An analytical solution for harmonic elimination under unbalanced input voltages is obtained resulting in a smooth (constant) power flow from AC to DC side in spite of the unbalanced voltage condition. Based on the analysis of the

A. V. Stankovic; T.A. Lipo

2000-01-01

99

Multiple Reference Frame-Based Control of Three-Phase PWM Boost Rectifiers under Unbalanced and Distorted Input Conditions  

Microsoft Academic Search

Many control algorithms and circuits for three-phase pulse width modulation active rectifiers have been proposed in the past decades. In most of the research, it is often assumed that the input voltages are balanced or contain only fundamental frequency components. In this paper, a selective harmonic compensation method is proposed based on an improved multiple reference frame algorithm, which decouples

Peng Xiao; Keith A. Corzine; Ganesh Kumar Venayagamoorthy

2008-01-01

100

A study of startup inrush current of three-phase voltage source PWM rectifier with PI controller  

Microsoft Academic Search

Usually, the control method with voltage and current PI regulators in synchronous rotating frame is applied to three-phase voltage source PWM rectifier. It is easy to generate inrush current during startup period. A slow ramp reference current is commonly used to achieve the soft starting, but not quite effective. The paper first analyzed the cause of inrush current and obtained

Qu Bo; Hong Xiao-yuan; Zheng-yu Lu

2009-01-01

101

On Acoustic-Noise-Reduction Control Using Random Switching Technique for Switch-Mode Rectifiers in PMSM Drive  

Microsoft Academic Search

This paper presents an acoustic-noise-reduction control using a random switching technique for front-end switch-mode rectifiers (SMRs) of a permanent-magnet synchronous-motor (PMSM) drive. First, the PMSM drive and its front-end ac-switch-based SMR are established. The proper controls are conducted to let the motor drive possess good driving characteristics. In the acoustic-noise-reduction control for a low-frequency SMR under a voltage closed-loop control,

Jui-Yuan Chai; Yeh-Hsiang Ho; Yu-Choung Chang; Chang-Ming Liaw

2008-01-01

102

Performance Comparison of Voltage Mode Control and Current Mode Control of a Three-Phase PWM Rectifier based on a Dual SISO Model  

Microsoft Academic Search

The challenge in controlling a three-phase PWM rectifier mainly arises from the fact that the state-space-averaged model reported in literature has a multi-input multi-output (MIMO) non-linear structure and furthermore exhibits non-minimum phase feature. Recently, a dual single-input single-output (SISO) model developed for the rectifier showed that the dynamics of the d-axis is similar to that of a traditional dc-dc boost

B. Yin; R. Oruganti; S. K. Panda; A. K. S. Bhat

2006-01-01

103

Combinational logic for generating gate drive signals for phase control rectifiers  

NASA Technical Reports Server (NTRS)

Control signals for phase-delay rectifiers, which require a variable firing angle that ranges from 0 deg to 180 deg, are derived from line-to-line 3-phase signals and both positive and negative firing angle control signals which are generated by comparing current command and actual current. Line-to-line phases are transformed into line-to-neutral phases and integrated to produce 90 deg phase delayed signals that are inverted to produce three cosine signals, such that for each its maximum occurs at the intersection of positive half cycles of the other two phases which are inputs to other inverters. At the same time, both positive and negative (inverted) phase sync signals are generated for each phase by comparing each with the next and producing a square wave when it is greater. Ramp, sync and firing angle controls signals are than used in combinational logic to generate the gate firing control signals SCR gate drives which fire SCR devices in a bridge circuit.

Dolland, C. R.; Trimble, D. W. (inventors)

1982-01-01

104

A new digital control system for a single-phase half-bridge rectifier with fast dynamic response  

Microsoft Academic Search

This paper proposes a digital control system for a half-bridge boost rectifier, which composes the input stage of a single-phase transformerless double-conversion UPS. The proposed control system has an inner current loop and two outer voltage loops to maintain near unity input power factor and to regulate the dc bus voltages. The control loops operate with distinct sampling frequencies, so

Luis M. Nodari; M. Mezaroba; L. Michels; C. Rech

2010-01-01

105

Adrenergic control of the ultrarapid delayed rectifier current in canine atrial myocytes  

PubMed Central

The effects of adrenergic stimulation on the ultrarapid delayed rectifier K+ current (IKur,d) of dog atrial myocytes was studied with patch-clamp methods. Isoproterenol (isoprenaline) increased IKur,d in a concentration-dependent fashion with an EC50 of 7·3 ± 0·8 nM. The effect of isoproterenol was blocked by propranolol, mimicked by forskolin and 8-bromo-cAMP, and prevented by inhibition of protein kinase A. Phenylephrine (in the presence of propranolol) increased IKur,d with an EC50 of 0·49 ± 0·06 ?M. The effect of phenylephrine was blocked by prazosin, prevented by inhibition of protein kinase C, and mimicked by activation of protein kinase C with phorbol ester. Phenylephrine significantly abbreviated canine atrial action potential duration in the absence of tetraethylammonium (TEA). When TEA was present under both control conditions and in the presence of phenylephrine, phenylephrine failed to alter canine atrial repolarization. We conclude that ?- and ?-adrenergic stimulation increase IKur,d via protein kinase A and C, respectively, and that the induced changes in IKur,d may play a role in adrenergic control of canine atrial repolarization.

Yue, Lixia; Feng, Jianlin; Wang, Zhiguo; Nattel, Stanley

1999-01-01

106

A Simple Analog Controller for Single-Phase Half-Bridge Rectifier and its Application to Transformerless UPS  

Microsoft Academic Search

A simple, low-cost, constant frequency, analog controller is proposed for the front-end half-bridge rectifier of a single-phase transformerless UPS system to maintain near unity power factor at the input and zero dc-offset voltage at the output. The controller generates the required gating pulses by comparing the input current with a periodic, bipolar, linear carrier without sensing the input voltage. Two

Rajesh Ghosh; G. Narayanan

2005-01-01

107

Automatic Distributed Load Temperature Control Strategies for a Rectified Continuous Flow Loop Interfaced with a Pulse Tube Cryocooler  

NASA Astrophysics Data System (ADS)

Distributed thermal loads are frequently encountered in large deployable structures used in space applications such as optical mirrors and focal plane electronics. An innovative mechanism for providing distributed cooling is an oscillatory pulse-tube cryocooler that is integrated with a fluid rectification system consisting of check-valves and buffer volumes in order to extract a small amount of continuous flow. This continuous flow allows relatively large loads to be accepted over a long distance. An additional advantage of the rectified system is the ability to provide rapid and precise temperature control via modulation of the flow rate in the flow loop. This paper presents an experimental demonstration of this temperature control method. A rectified interface is integrated with a thermal load and subjected to various thermal disturbances. Temperature regulation is enabled using temperature feedback control of a valve placed in the distribution loop. The control parameters are selected to meet temperature regulation specifications, including maximum temperature deviation and settling time in response to a step change in distributed load. The measured controlled transient behaviors to step and sinusoidal distributed load variations are presented. The predicted and measured behaviors are compared in order to validate the thermal model of the rectifying interface system.

Skye, H. M.; Nellis, G. F.; Klein, S. A.

2008-03-01

108

New direct power control of three-phase PWM boost rectifiers under distorted and imbalanced line voltage conditions  

Microsoft Academic Search

The three-phase PWM boost rectifier is an interesting solution thanks to advantages as: bi-directional power flow, low harmonic distortion of line current, regulation of input power factor to unity, adjustment and stabilization of DC-link voltage. This paper proposes a new direct power control for this kind of converter using space vector modulation (DPC-SVM). The active and reactive power is used

M. Malinowski; G. Marques; M. Cichowlas; M. P. Kazmierkowski

2003-01-01

109

Input state feedback linearization control of a three-phase three-level neutral point clamped rectifier  

Microsoft Academic Search

An exact nonlinear multiple-input multiple-output (MIMO) state space mathematical model of the power circuit of pulse-width-modulation (PWM) three-phase three-level neutral point clamped AC\\/DC rectifier was developed. Using this nonlinear model, an input\\/output feedback linearization was then designed. Analytical expressions of the linearizing control law (LCL) were derived. The resulting linearized model is simply a decoupled linear system equation. Linear state

L. Yacoubi; F. Fnaiech; K. Al-Haddad; L.-A. Dessaint

2001-01-01

110

Dual frame cascaded controller design for three phase PWM boost rectifier under generalized supply voltage conditions using singular perturbation method  

Microsoft Academic Search

This paper proposes the design of a dual frame cascaded PI controller for the three phase PWM boost rectifier under unbalanced supply voltage conditions by using singular perturbation method. By inducing two-time-scale motions, namely fast motion sub-system and slow motion sub-system, the desired output transient performance can be achieved with stability conditions imposed on the fast and slow modes with

Xinhui Wu; Sanjib K. Panda; Jianxin Xu; Valery D. Yurkevich

2008-01-01

111

An Output-Power-Control Strategy for a Three-Phase PWM Rectifier Under Unbalanced Supply Conditions  

Microsoft Academic Search

Instantaneous power regulation is an effective way to improve the performance of a pulsewidth-modulation rectifier operating under unbalanced supply-voltage conditions. By properly setting current commands, this approach aims to achieve performance features that are normally achievable only under ideal balanced operating conditions. This paper proposes an instantaneous power-regulation strategy called output-power-control method, in which the current commands are determined so

Bo Yin; Ramesh Oruganti; Sanjib Kumar Panda; Ashoka K. S. Bhat

2008-01-01

112

A Power Balance Control Technique for Operating a Three-Phase AC to DC Converter Using Single-Phase CUK Rectifier Modules  

Microsoft Academic Search

The analysis and design of a single-stage three-phase AC to DC converter using single-phase CUK rectifier modules is discussed based on power balance control technique. The proposed system is formed by an input-side star-connected of three single-phase CUK rectifier modules with parallel connected at DC outputs. The control strategy consists of single voltage loop control and three-inductor current calculator. The

U. Kamnarn; V. Chunkag

2006-01-01

113

A DSP-based implementation of a new nonlinear control for a three-phase neutral point clamped boost rectifier prototype  

Microsoft Academic Search

This work presents the design and implementation of a nonlinear control strategy for a three-phase three-level neutral-point-clamped boost rectifier. The adopted control consists of nonlinear feedback linearization technique. The nonlinear state-space model of the rectifier was obtained in the dq0 reference frame. The input\\/output feedback linearization is then applied and the linearizing control law is derived. Therefore, the resulting model

Loubna Yacoubi; Kamal Al-Haddad; Farhat Fnaiech; L.-A. Dessaint

2005-01-01

114

Reduction of the power dissipation in silicon carbide Schottky rectifiers by a dual-metal planar structure  

NASA Astrophysics Data System (ADS)

A dual-metal-planar rectifier on 6H-SiC was fabricated using Ti and Ni2Si as Schottky metals. The forward current voltage (I-V) characteristic of the dual-metal devices was comparable with that of Ti diodes. On the other hand, under reverse bias, almost the same leakage current of the Ni2Si rectifiers was achieved, i.e., a factor 1000 lower than that of Ti diodes. The fabricated diodes allowed to obtain a power dissipation of 0.37 W/cm2, significantly reduced with respect to the Ti and Ni2Si diodes dissipation. Moreover, the breakdown voltage was the same as in the planar Ni2Si diode, thus indicating that the planar structure is very efficient in avoiding electric field crowding at the titanium stripes edges.

Roccaforte, F.; La Via, F.; Di Franco, S.; Raineri, V.

2002-08-01

115

The 3 phase PWM voltage source reversible rectifier based on a novel space vector control method  

Microsoft Academic Search

In this paper, a novel voltage space vector (NVSV) method used for 3-phase pulse width modulation voltage source reversible rectifier (PWM VSR) is described in detail. Based on the conventional voltage space vector (CVSV) method and its geometry topology, the actual switching time has a very simple form. With the ??-coordinate transformation, the NVSV can be easily realized. Its effect

Zhan Changjiang; Han Yingduo; Wong Manchung

1998-01-01

116

Control performance of active damp LCL filter of three phase PWM boost rectifier  

Microsoft Academic Search

This paper presents three methods of a three phase PWM boost rectifier connected to the grid via a single stage L filter, an undamp LCL filter and an active damp LCL filter. The first method is the simplest method uses the biggest size of single stage L filter. Although this method is straightforward, it increases the system size and weight

Surasak Nuilers; Bunlung Neammanee

2010-01-01

117

Transformer-rectifier flux pump using inductive current transfer and thermally controlled Nb(3)Sn cryotrons.  

PubMed

Transformer-rectifier flux pumps using thermally switched Nb(3)Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz. PMID:18699368

Atherton, D L; Davies, R

1979-10-01

118

DQ modeling and control of a single-phase three-level boost rectifier with power factor correction and neutral-point voltage balancing  

Microsoft Academic Search

This paper deals with the analysis, design and operation of a control system for a single-phase three-level rectifier with a neutral-point-clamped (NPC) topology. Usually the desired operating conditions for this type of converter are: unity displacement factor, output DC voltage regulation and neutral point voltage balancing. A d-q reference frame has been used in this work to model the rectifier

Joan Salaet; Salvador Alepuz; Alex Gilabert; Josep Bordonau; Juan Peracaula

2002-01-01

119

Simplified Control Structure for Current Control of Single Phase Rectifiers Using COT-ANN-PWM  

Microsoft Academic Search

This paper describes a single phase switched recti- fier for current control using Model Reference Adaptive Control (MRAC) with a Continually On-Line Trained Artificial Neural Network (COT-ANN). The results obtained with the proposed scheme are similar to the ones obtained in a previous work but using a simpler control structure. Simulations are used to test the validity of the proposed

Julio Viola; Jose Restrepo; Mary Diaz; Jose M. Aller; Ronald G. Harley; T. G. Habetler

2007-01-01

120

Improved Pulse Delay Circuit for Phase-Controlled Rectifiers and Ac Voltage Controllers  

Microsoft Academic Search

The paper presents a new method of synchronization of the pulse delay control circuits for, triggering thyristors in line commutated converters, where an exact 180° phase difference is ensured between the firing ing pulses sent to the thyristors in the same mains phase. In 3-phase systems, it provides small deviation from the desired ± 120° difference with respect to the

Alexander Yair; Meir Steinkoler

1977-01-01

121

A current controlled near unity power factor three-phase PWM buck rectifier without passive damping requirements  

Microsoft Academic Search

Three-phase current source PWM rectifier (also known as three-phase buck rectifier) is often used as the front-end in utility interfaced systems. An input LC filter is required to suppress the current harmonics injected into AC mains. The input filter affects the input displacement factor (IDF) of the system, which varies with the rectifier operating point and may result in unacceptable

Navid R. Zargari; D. Raonic

1995-01-01

122

INTRODUCING AN EFFICIENT AND HIGH-PERFORMANCE CONTROL STRATEGY BASED ON A NOVEL VECTOR CLAMPING CLASSIFICATION TECHNIQUE FOR THREE PHASE BOOST RECTIFIERS  

Microsoft Academic Search

To date three-phase boost rectifiers, due to their high efficiency, good current quality and low EMI emissions are widely used in industry as Power Factor Correction (PFC) converters. Performance criteria of these converters improve significantly with increasing the switching frequency, and depend highly on the control strategy used. This paper introduces a simple and fast control strategy for three-phase boost

D. YAZDANI; A. BAKHSHAI

123

New Results on the Rectifying Process in Surface Barrier Counters  

Microsoft Academic Search

In order to understand the rectifying process involved in silicon surface barrier nuclear particle counters, we have substituted the usual gold contact with various metals. The results obtained from this substitution with twenty different metals are given. New results concerning the formation of the rectifying process for the case of gold-silicon diodes are presented. In particular, we have considered the

P. Siffert; A. Coche

1965-01-01

124

Simple Diode Rectifier Circuit  

NSDL National Science Digital Library

This website from the Thayer School of Engineering at Dartmouth College features an animation of a simple diode rectifier circuit. A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification.

2012-10-24

125

Fault Detection of Rectifier based on Residuals  

NASA Astrophysics Data System (ADS)

For diagnosing failure and sick rectifying elements, a fault detection and prediction method of rectifier was presented in this paper. The output voltage of rectifier was contrasted with normal simulation signal in phase to obtain the difference signal. After it was processed according to the set threshold, the coding of the difference signal was achieved. The signal coding was adopted to diagnose failure elements or sick elements. In simulation test, the fault code tables of rectifier with different control angle were given. The simulation results show the validity of the fault detection method presented in this paper.

Qingfeng, Liu; Zhaoxia, Leng; Jinkun, Sun; Huamin, Wang

126

Sinusoidal internal model based control of a three-phase voltage source rectifier with buck-boost operation  

Microsoft Academic Search

A rectifier system having a DC voltage step-up and step-down characteristic is treated. The system consists of a PWM voltage source rectifier and a DC-to-DC buck converter connected in cascade. Theoretically, the system can produce a DC output voltage ranging from zero volts to infinity and a sinusoidal AC input current, and the displacement power factor can be kept at

Atsushi Moki; Shoji Fukuda

2003-01-01

127

Control of three-phase single-stage isolated buck+boost unity power factor rectifier for unbalanced input voltages  

Microsoft Academic Search

A single-stage structure is proposed for realizing a unity power factor three-phase isolated AC-DC converter for telecommunication power supply modules. This structure is composed by integrating a boost converter to the isolated three-phase three-switch buck rectifier. Modified space vector modulation method is applied to the three-phase three-switch isolated unity power factor input buck rectifier based on the space vector modulation

Ali Mohammadpour; Mohammad Reza Zolghadri

2009-01-01

128

Decoupled control of active and reactive power for three phase PWM rectifiers  

Microsoft Academic Search

This paper proposes a new control schemes for three phase P WM rectijiers which is easy to implement. The method is based on decoupled control of instantaneous active and reactive power components, where the corresponding reference ac line currents are obtained using two PI-controllers loops. One PI controller is for the active power loop and the other is for the

Mohamed Azab

2004-01-01

129

A DSP-based implementation of a nonlinear model reference adaptive control for a three-phase three-level NPC boost rectifier prototype  

Microsoft Academic Search

In this paper, the design and the implementation of a model reference adaptive control (MRAC) applied to a three-phase three-level neutral-point-clamped (NPC) boost rectifier are presented. This control strategy is developed with a view to regulate dc output and neutral point voltages and to reduce the influence of parameter variations while maintaining unity power factor. A nonlinear multiple-input multiple-output (MIMO)

Loubna Yacoubi; Kamal Al-Haddad; L.-A. Dessaint; F. Fnaiech

2005-01-01

130

A DSP based controller for power factor correction (PFC) in a rectifier circuit  

Microsoft Academic Search

In this paper a digital signal processor (DSP) based power factor correction (PFC) scheme is presented. A dual-loop controller is designed to control the average input AC current as well as DC bus voltage. The DSP controller is implemented and tested. Design methodologies and trade-offs such as discrete-time implementation methods are also presented

M. Fu; Q. Chen

2001-01-01

131

Hybrid offshore wind and tidal turbine energy harvesting system with independently controlled rectifiers  

Microsoft Academic Search

This paper proposes a hybrid offshore wind and tidal energy conversion system. In this study, dynamic model and control schemes of this hybrid system are presented. Gearless generators are designed to achieve direct-drive application. A Permanent Magnet Synchronous Generator (PMSG) model is established in the dq-synchronous rotating frame, and Maximum Power Point Tracking (MPPT) is realized through controlling the speed

Yao Da; Alireza Khaligh

2009-01-01

132

Silicon-controlled-rectifier square-wave inverter with protection against commutation failure  

NASA Technical Reports Server (NTRS)

The square-wave SCR inverter that was designed, built, and tested includes a circuit to turn off the inverter in case of commutation failure. The basic power stage is a complementary impulse-commutated parallel inverter consisting of only six components. The 400-watt breadboard was tested while operating at + or - 28 volts, and it had a peak efficiency of 95.5 percent at 60 hertz and 91.7 percent at 400 hertz. The voltage regulation for a fixed input was 3 percent at 60 hertz. An analysis of the operation and design information is included.

Birchenough, A. G.

1971-01-01

133

Silicon controlled rectifier polyphase bridge inverter commutated with gate-turn-off thyristor  

NASA Technical Reports Server (NTRS)

A polyphase SCR inverter (10) having N switching poles, each comprised of two SCR switches (1A, 1B; 2A, 2B . . . NA, NB) and two diodes (D1B; D1B; D2A, D2B . . . DNA, DNB) in series opposition with saturable reactors (L1A, L1B; L2A, L2B . . . LNA, LNB) connecting the junctions between the SCR switches and diodes to an output terminal (1, 2 . . . 3) is commutated with only one GTO thyristor (16) connected between the common negative terminal of a dc source and a tap of a series inductor (14) connected to the positive terminal of the dc source. A clamp winding (22) and diode (24) are provided, as is a snubber (18) which may have its capacitance (c) sized for maximum load current divided into a plurality of capacitors (C.sub.1, C.sub.2 . . . C.sub.N), each in series with an SCR switch S.sub.1, S.sub.2 . . . S.sub.N). The total capacitance may be selected by activating selected switches as a function of load current. A resistor 28 and SCR switch 26 shunt reverse current when the load acts as a generator, such as a motor while braking.

Edwards, Dean B. (Inventor); Rippel, Wally E. (Inventor)

1986-01-01

134

A Unity Power Factor Boost Rectifier with a Predictive Capacitor Model for High Bandwidth DC Bus Voltage Control  

Microsoft Academic Search

Single phase rectifiers with power factor correction circuits based on the boost converter find broad application in consumer equipment. A fundamental design difficultly is caused by the need to trade off the input line current wave shape and the dynamic response of the output energy storage capacitor voltage regulation loop. The energy balance requirement inherent in single phase systems forces

Peter Wolfs; Peter Thomas

135

Analysis and Control of the Output Instantaneous Power for Three Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Conditions  

Microsoft Academic Search

This paper proposes a new method to analyze the output instantaneous power of the three phase PWM boost rectifier under unbalanced supply voltage conditions. An analytical expression for the output instantaneous power has been derived and presented, which provides the link between the output dc linkage voltage and the instantaneous output power. Based on the mathematical model of the three

Xinhui Wu; Sanjib K. Panda; Jianxin Xu

2006-01-01

136

K+ channels of stomatal guard cells. Characteristics of the inward rectifier and its control by pH  

PubMed Central

Intracellular microelectrode recordings and a two-electrode voltage clamp have been used to characterize the current carried by inward rectifying K+ channels of stomatal guard cells from the broadbean, Vicia faba L. Superficially, the current displayed many features common to inward rectifiers of neuromuscular and egg cell membranes. In millimolar external K+ concentrations (Ko+), it activated on hyperpolarization with half-times of 100-200 ms, showed no evidence of time- or voltage-dependent inactivation, and deactivated rapidly (tau approximately 10 ms) on clamping to 0 mV. Steady-state conductance- voltage characteristics indicated an apparent gating charge of 1.3-1.6. Current reversal showed a Nernstian dependence on Ko+ over the range 3- 30 mM, and the inward rectifier was found to be highly selective for K+ over other monovalent cations (K+ greater than Rb+ greater than Cs+ much greater than Na+). Unlike the inward rectifiers of animal membranes, the current was blocked by charybdotoxin and alpha- dendrotoxin (Kd much less than 50 nM), as well as by tetraethylammonium chloride (K1/2 = 9.1 mM); gating of the guard cell K+ current was fixed to voltages near -120 mV, independent of Ko+, and the current activated only with supramillimolar K+ outside (EK+ greater than -120 mV). Most striking, however, was inward rectifier sensitivity to [H+] with the K+ current activated reversibly by mild acid external pH. Current through the K+ inward rectifier was found to be largely independent of intracellular pH and the current reversal (equilibrium) potential was unaffected by pHo from 7.4 to 5.5. By contrast, current through the K+ outward rectifier previously characterized in these cells (1988. J. Membr. Biol. 102:235) was largely insensitive to pHo, but was blocked reversibly by acid-going intracellular pH. The action of pHo on the K+ inward rectifier could not be mimicked by extracellular Ca2+ for which changes in activation, deactivation, and conductance were consonant with an effect on surface charge ([Ca2+] less than or equal to 1 mM). Rather, extracellular pH affected activation and deactivation kinetics disproportionately, with acid-going pHo raising the K+ conductance and shifting the conductance-voltage profile positive-going along the voltage axis and into the physiological voltage range. Voltage and pH dependencies for gating were consistent with a single, titratable group (pKa approximately 7 at -200 mV) residing deep within the membrane electric field and accessible from the outside.(ABSTRACT TRUNCATED AT 400 WORDS)

1992-01-01

137

Atomic layer controlled digital etching of silicon  

Microsoft Academic Search

The mechanisms of atomic layer controlled digital etching are examined with particular reference to the digital etching of silicon with fluorine. The experiments included repeated reaction cycles of fluorine atom adsorption on a cooled Si surface followed by Ar(+) ion (20 eV) irradiation inducing fluorine\\/Si reactions. With an increase in Ar(+) irradiation time, the digital etch rate increases and reaches

Hiroyuki Sakaue; Seiji Iseda; Kazushi Asami; Jirou Yamamoto; Masataka Hirose; Yasuhiro Horiike

1990-01-01

138

Control of silicon nanoparticle size embedded in silicon oxynitride dielectric matrix  

SciTech Connect

In this study, silicon rich silicon oxynitride layers containing more than 15% nitrogen were deposited by electron cyclotron resonance assisted plasma enhanced vapor deposition in order to form silicon nanoparticles after a high temperature thermal annealing. The effect of the flows of the precursor gases on the composition and the structural properties of the layers was assessed by Rutherford backscattering spectroscopy, elastic recoil detection analysis, and infrared spectroscopic measurements. The morphological and crystallinity properties were investigated by energy filtered transmission electron microscopy and Raman spectroscopy. We show that the excess of silicon in the silicon oxynitride layer controls the silicon nanoparticles size. On the other hand, the crystalline fraction of particles is found to be strongly correlated to the nanoparticle size. Finally, the photoluminescence measurements show that it is also possible to tune the photoluminescence peak position between 400 and 800 nm and its intensity by changing the silicon excess in the silicon rich silicon oxynitride matrix.

Ehrhardt, F.; Ferblantier, G.; Muller, D.; Slaoui, A. [ICube, Strasbourg University-CNRS, 23 rue du Loess BP20, 67037 Strasbourg Cedex 2 (France); Ulhaq-Bouillet, C. [IPCMS, Strasbourg University-CNRS, 23 rue du Loess BP43, 67034 Strasbourg Cedex 2 (France); Rinnert, H. [IJL, CNRS, Campus Victor Grignard BP 70239, 54506 Vandoeuvre-les-Nancy Cedex (France)

2013-07-21

139

A high frequency DC link single phase PWM rectifier  

Microsoft Academic Search

A high frequency dc link single phase PWM rectifier is proposed in this paper. It has the advantages of high efficiency, high power density, high reliability, and wide range of output voltage etc. A dual loop control scheme for this PWM rectifier is developed, which includes an inner PR (Proportional-Resonant) current controller and an outer PI (Proportional-Integral) controller. Nearly unit

Wenjie Zhu; Keliang Zhou; Li Zhu; Xiu'e Su

2010-01-01

140

Diodes and Rectifiers  

NSDL National Science Digital Library

Written by Tony R. Kuphaldt, this chapter of All About Circuit's third volume on Semiconductors describes the physics behind diodes and rectifiers. The chapter is divided into fourteen sections on topics including diode ratings, voltage multipliers, and zener diodes. Each section has clear illustrations and examples, and most have a concise, bulleted review of what was covered at the end of the page. This is an excellent resource for educators in physics and electronic engineering classrooms to introduce lessons or units on semiconductors, diodes, and rectifiers. [ASC

Kuphaldt, Tony R.

2008-07-02

141

Artificial neural networks for control of a grid-connected rectifier/inverter under disturbance, dynamic and power converter switching conditions.  

PubMed

Three-phase grid-connected converters are widely used in renewable and electric power system applications. Traditionally, grid-connected converters are controlled with standard decoupled d-q vector control mechanisms. However, recent studies indicate that such mechanisms show limitations in their applicability to dynamic systems. This paper investigates how to mitigate such restrictions using a neural network to control a grid-connected rectifier/inverter. The neural network implements a dynamic programming algorithm and is trained by using back-propagation through time. To enhance performance and stability under disturbance, additional strategies are adopted, including the use of integrals of error signals to the network inputs and the introduction of grid disturbance voltage to the outputs of a well-trained network. The performance of the neural-network controller is studied under typical vector control conditions and compared against conventional vector control methods, which demonstrates that the neural vector control strategy proposed in this paper is effective. Even in dynamic and power converter switching environments, the neural vector controller shows strong ability to trace rapidly changing reference commands, tolerate system disturbances, and satisfy control requirements for a faulted power system. PMID:24807951

Li, Shuhui; Fairbank, Michael; Johnson, Cameron; Wunsch, Donald C; Alonso, Eduardo; Proaño, Julio L

2014-04-01

142

Controlled thinning and surface smoothening of silicon nanopillars  

Microsoft Academic Search

A convenient method has been developed to thin electron beam fabricated silicon nanopillars under controlled surface manipulation by transforming the surface of the pillars to an oxide shell layer followed by the growth of sacrificial ammonium silicon fluoride coating. The results show the formation of an oxide shell and a silicon core without significantly changing the original length and shape

S. Kalem; P. Werner; B. Nilsson; V. G. Talalaev; M. Hagberg; Ö. Arthursson; U. Södervall

2009-01-01

143

A low cost fuzzy logic active rectifier  

Microsoft Academic Search

This paper presents a current-sensorless active rectifier specifically designed for low cost applications. Both the control and the modulation use fuzzy logic. A simple model of the system is given in order to explain the current feedforward control using fuzzy logic and the fuzzy logic-based modulation. In this paper, the new algorithm has been deeply analysed looking to obtain the

Carlo Cecati; Antonio Dell' Aquila; Marco Liserre; Antonio Ometto

2001-01-01

144

Current Control Method to Achieve Wide-Range Power Driving for Linear Synchronous Motor with Half-Wave-Rectified Self-Excitation  

NASA Astrophysics Data System (ADS)

In a previous paper, we proposed a novel linear synchronous motor with half-wave-rectified self-excitation. The long-stator-type linear synchronous motor was built, and its performance was verified by performing experiments. This paper presents a new current control method for the linear synchronous motor for achieving a wide range of speeds and high-power operations. First, we propose the current control method for high-thrust operation in the constant-thrust region. This operation is realized by using a reluctance thrust resulting from the saliency of the linear synchronous motor. Furthermore, we propose a control method that maximizes the ratio of the thrust to the voltage; this method can be used to expand the operating range. Wide-range-speed operation can be achieved by applying this new control method along with field-weakening control. The thrust and operation characteristics of the proposed control methods are estimated by performing experiments and an electric and magnetic coupled analysis.

Hirayama, Tadashi; Higuchi, Tsuyoshi

145

Active particle control through silicon using conventional optical trapping techniques.  

PubMed

Functional integration of optical trapping techniques with silicon surfaces and environments can be realized with minimal modification of conventional optical trapping instruments offering a method to manipulate, track and position cells or non-biological particles over silicon substrates. This technique supports control and measurement advances including the optical control of silicon-based microfluidic devices and precision single molecule measurement of biological interactions at the semiconductor interface. Using a trapping laser in the near infra-red and a reflective imaging arrangement enables object control and measurement capabilities comparable to trapping through a classical glass substrate. The transmission efficiency of the silicon substrate affords the only reduction in trap stiffness. We implement conventional trap calibration, positioning, and object tracking over silicon surfaces. We demonstrate control of multiple objects including cells and complex non-spherical objects on silicon wafers and fabricated surfaces. PMID:18030409

Appleyard, David C; Lang, Matthew J

2007-12-01

146

Unimolecular electronic rectifiers  

NASA Astrophysics Data System (ADS)

The fabrication of a unimolecular rectifier is the first step toward the fabrication of nanoscale unimolecular electronic circuit elements. For instance, a nanoscale current transistor will enable the future molecular computer to be much denser, smaller, and faster than present computers, provided that the size of each element (rectifier, resistor, transistor) is small (3-10 nm) and the speed of electron transfer through the element is fast (<1 ns). Macroscopic current-voltage measurements reveal asymmetries in the DC electrical conductivity, probably due to an intramolecular electron transfer, through Langmuir-Blodgett multilayers and even monolayers of ?-(n-hexadecyl)quinolinum tricyanoquinodimethanide, C16H33Q- 3CNQ (1). The data showing rectification in the expected direction and some rectification in the reverse direction are analyzed and discussed. Thu through-film electrical conductivity of Langmuir-Blodgett monolayer films of 1 was studied as a function of temperature. The current is usually smaller at low temperature, but rectification was observed between 370 K and 105 K, with a rectification ratio as large at 105 K as at room temperature. Unimolecular electrical rectification by monolayers of molecule 1 is unequivocally confirmed. The sandwich ``Al | LB monolayer of 1 | Al'' is the smallest rectifier in the world. The details of the fabrication of the sandwich, the instrumentation, as well as the electrical circuit are described. The core-level N1s XPS spectrum reveals the three expected N valence states. The valence-level XPS spectrum can be correlated with theory. Pressure/area isotherms, film transfer, and rectification of five analogs of the molecule were studied, but no rectification was observed on these systems. Pressure/area isotherms of four cholesterol derivatives and a fullerene derivative are reported. Preliminary work on a molecular transistor is also reported. Future work on low-temperature measurements with an improved sandwich structure, and on a molecular transistor is proposed.

Chen, Bo

147

Supply-side Current Harmonics Control of Three Phase PWM Boost Rectifiers Under Distorted and Unbalanced Supply Voltage Conditions  

Microsoft Academic Search

This paper presents a hybrid current control scheme to minimize the even order harmonics at the dc link voltage and odd order harmonics in the line currents under the distorted and unbalanced supply voltage conditions. The hybrid current control scheme consists of a conventional PI and a repetitive controller (RC). Based on the mathematical model of the three-phase PWM boost

Xinhui Wu; Sanjib K. Panda; Jianxin Xu

2007-01-01

148

Thin-film semiconductor rectifier has improved properties  

NASA Technical Reports Server (NTRS)

Cadmium selenide-zinc selenide film is used as a thin film semiconductor rectifier. The film is vapor-deposited in a controlled concentration gradient into a glass substrate to form the required junctions between vapor-deposited gold electrodes.

1966-01-01

149

Method of controlling defect orientation in silicon crystal ribbon growth  

NASA Technical Reports Server (NTRS)

The orientation of twinning and other effects in silicon crystal ribbon growth is controlled by use of a starting seed crystal having a specific (110) crystallographic plane and (112) crystallographic growth direction.

Leipold, M. H. (inventor)

1978-01-01

150

Comparison between two methods of DQ transformation for single phase converters control. Application to a 3-level boost rectifier  

Microsoft Academic Search

The paper discusses the analysis and control of single-phase AC systems by means of rotating frames. Two methods for the D-Q transformation are compared in terms of computational requirements, transient response and sensibility. One of the transformation methods is based on sine and cosine composition, while the other uses a bi-phase transformation. The comparison has been done using simulation and

J. Salaet; S. Alepuz; A. Gilabert; J. Bordonau

2004-01-01

151

Black silicon with controllable macropore array for enhanced photoelectrochemical performance  

NASA Astrophysics Data System (ADS)

Macroporous silicon with multiscale texture for reflection suppression and light trapping was achieved through a controllable electrochemical etching process. It was coated with TiO2 by atomic layer deposition, and used as the photoanode in photocatalytic water splitting. A conformal pn-junction was also built-in in order to split water without external bias. A 45% enhancement in photocurrent density was observed after black silicon etching. In comparison with nano-structured silicon, the etching process here has neither metal contamination nor requirement of vacuum facilities.

Ao, Xianyu; Tong, Xili; Sik Kim, Dong; Zhang, Lianbing; Knez, Mato; Müller, Frank; He, Sailing; Schmidt, Volker

2012-09-01

152

Control of Axial Resistivity Distribution in Bridgman Silicon Growth  

NASA Astrophysics Data System (ADS)

We propose the simple codoping method for improving the productivity of silicon single-crystal growth by controlling axial specific resistivity distribution. Numerical simulations have been performed to study the transport phenomena of dopant impurities in conventional and proposed Bridgman silicon growth using the finite element method and implicit Euler time integration. It has been demonstrated using mathematical models and by numerical analysis that the axial specific resistivity distribution can be modified in horizontal Bridgman silicon growth and relatively uniform its profile is feasible by the proposed doping method.

Wang, Jong Hoe; Im, Jong-In

2004-07-01

153

A distributed rectifier testing system based on RS485  

Microsoft Academic Search

Focusing on the function shortage and low productivity of existing testing equipment in the semiconductor rectifier bridge manufacture procedure, we designed a master-slave structure testing system. In this system, a PC acts as host processor, and several distributing local single chip micro controllers(SCMs)act as slave processors. The SCMs mainly perform classification and testing each rectifier, and the PC performs data

Yanfang Wang; Wandui Mao; Jinying Li; Peng Zhang; Xiaoping Wang

2010-01-01

154

A phase-disposition PWM method for DC voltage balance in cascaded H-Bridge rectifier  

Microsoft Academic Search

In this paper, a novel control scheme for cascaded H-Bridge rectifier (CHBR), which can be used as the primary end of high voltage high power multilevel converters, is presented. The controller is similar with the one for single phase rectifier. To improve the performance of the controller, notch filter and proportion resonance (PR) controller are employed and the discrete methods

Tao Xinghua; Li Yongdong; Sun Min

2010-01-01

155

Controlling cellular activity by manipulating silicone surface roughness.  

PubMed

Silicone elastomers exhibit a broad range of beneficial properties that are exploited in biomaterials. In some cases, however, problems can arise at silicone elastomer interfaces. With breast implants, for example, the fibrous capsule that forms at the silicone interface can undergo contracture, which can lead to the need for revision surgery. The relationship between surface topography and wound healing--which could impact on the degree of contracture--has not been examined in detail. To address this, we prepared silicone elastomer samples with rms surface roughnesses varying from 88 to 650 nm and examined the growth of 3T3 fibroblasts on these surfaces. The PicoGreen assay demonstrated that fibroblast growth decreased with increases in surface roughness. Relatively smooth (approximately 88 nm) PDMS samples had ca. twice as much fibroblast DNA per unit area than the 'bumpy' (approximately 378 nm) and very rough (approximately 604 and approximately 650 nm) PDMS samples. While the PDMS sample with roughness of approximately 650 nm had significantly fewer fibroblasts at 24h than the TCP control, fibroblasts on the smooth silicone surprisingly reached confluence much more rapidly than on TCP, the gold standard for cell culture. Thus, increasing the surface roughness at the sub-micron scale could be a strategy worthy of consideration to help mitigate fibroblast growth and control fibrous capsule formation on silicone elastomer implants. PMID:20363600

Prasad, Babu R; Brook, Michael A; Smith, Terry; Zhao, Shigui; Chen, Yang; Sheardown, Heather; D'souza, Renita; Rochev, Yuri

2010-07-01

156

Passivity-based control with dual lagrangian model of four-wire three-level three-phase NPC voltage-source rectifier  

Microsoft Academic Search

This paper presents the EL modeling of the four-wire 3-level 3-phase NPC voltage source rectifier (VSR). The load current of the four-wire 3-level 3-phase could be expressed in two forms: the load current involving the current of capacitor C1, and the load current involving the current of capacitor C2. So that two EL models will be obtained for four-wire 3-level

Majid Mehrasa; Saeed Lesan; S. N. H. Emeni; A. Sheikholeslami

2009-01-01

157

Modeling and Simulation of Three-phase Rectifier Based on SVPWM  

Microsoft Academic Search

The mathematical and simulation model of three-phase voltage source rectifier (VSR) used in aircraft is introduced in this paper. Based on the model, the principle of the seven-segment space vector pulse-with modulation (SVPWM) control strategy is presented. The double closed-loop control method is applied in the PWM rectifier. The rectifier can realize unity power factor by adopting the fixed switching

Shutuan Zhang; Kai Zhang; Zhongshan Jiang; Fang Lu

2010-01-01

158

A Battery Charge and Discharge Device Using PID Genetic Algorithm Based on PWM Rectifier  

Microsoft Academic Search

The research on the application of the 3-phase high power PWM (Pulse Width Modulation) rectifier in the battery charge and discharge device has been a hotspot in the field of power electronics and control. As the traditional PID controller is difficult to achieve the optimum parameters, this paper proposes a new control method of PWM rectifier based on Genetic Algorithm

Zhu Jun-jie; Chen Cheng; Xu Jin; Yao Ye

2010-01-01

159

AC Switches Control Energy Reduction  

Microsoft Academic Search

Electricity production is drastically increasing due to the energy consumption growth through the world. Many organizations are becoming aware of the environmental impact, and are considering energy efficiency as one way to reduce emissions and preserve natural resources. Most of AC loads installed in domestic appliances are controlled by TRIACs or SCRs (silicon controlled rectifier) because they present the best

G. Benabdelaziz; L. Gonthier; J. C. Le Bunetel; D. Magnon

2005-01-01

160

Controlled growth of nanocrystalline silicon within amorphous silicon carbide thin films  

NASA Astrophysics Data System (ADS)

Controlled formation of nanocrystalline silicon (nc-Si) within hydrogenated amorphous silicon carbide (a-SiC:H) thin films has been demonstrated by a rf (13.56 MHz) plasma chemical vapour deposition (PECVD) method at a low deposition temperature of 200°C by regulating the deposition pressure (Pr) between 26.7 Pa and 133.3 Pa. Evolution of the size and the crystalline silicon volume fraction within the a-SiC:H matrix has been studied by XRD, Raman and HRTEM. The study reveals that at Pr of 26.7 Pa there are mostly isolated grains of nc-Si within the a-SiC:H matrix with average size of 4.5 nm. With increase of Pr the isolated nc-Si grains coalesce more and more giving rise to larger size connected nc-Si islands which appear as microcrystalline silicon in the Raman spectra. As a result net isolated nc-Si volume fraction decreases while the total crystalline silicon volume fraction increases.

Kole, Arindam; Chaudhuri, Partha

2014-04-01

161

Power quality improvement in DTC based induction motor drive using Minnesota rectifier  

Microsoft Academic Search

This paper presents power quality improvement at the utility interface for a Direct Torque Controlled (DTC) induction motor drive by making use of a Minnesota rectifier. The proposed Minnesota rectifier for a 2.2 kW drive is designed, modeled and simulated in MATLAB\\/Simulink platform. The design of the proposed Minnesota rectifier is developed along with the necessary modifications required for making

Bhim Singh; G. Bhuvaneswari; Sandeep Madishetti

2011-01-01

162

Dual frame control scheme with a plug-in frequency domain based repetitive controller for three phase PWM boost rectifier under distorted and unbalanced supply voltages  

Microsoft Academic Search

This paper presents a dual frame control scheme with a digital plug-in frequency domain based repetitive controller (FDRC) for minimizing the even order harmonics at the output dc link voltage and odd order harmonics in the line currents under the distorted and unbalanced supply voltage conditions. The proposed current controller consists of a conventional PI controller and a frequency domain

Xinhui Wu; Sanjib K. Panda; Jianxin Xu

2008-01-01

163

Thermostatic control for temperature compensation of a silicon pressure sensor  

Microsoft Academic Search

An alternative temperature compensation technique for a silicon pressure sensor is presented. By using on-chip heater and temperature sensing electrodes, a thermostatic control loop is implemented. The sensor is biased at a reference temperature, which is maintained with high accuracy over a specified range, hereby eliminating the dependence of the pressure sensor output on ambient temperature. No additional calibration procedures

Dirk De Bruyker; Robert Puers

2000-01-01

164

Three-phase PWM sinusoidal current rectifier with power conditioning capability  

Microsoft Academic Search

This paper presents a PWM three-phase rectifier controlled to demand a sinusoidal source current in phase with the positive-sequence fundamental source voltage, providing unity displacement power factor. The operation of the rectifier is controlled so that in case of a nonlinear load connected to the grid, the power converter also operates as an active power filter, improving the global power

M. I. Milanés Montero; E. Romero Cadaval; V. M. Miñambres Marcos; M. A. G. Martinez

2009-01-01

165

Multi objectives operation of cascade inverter-based voltage quality compensator with PWM rectifier supply  

Microsoft Academic Search

A novel main circuit topology of voltage quality compensator (VQC) is proposed in this paper, composed of PWM rectifier and cascade H-bridges inverter. The three phase inverter is decoupling controlled. PWM rectifier is adopted to maintain the dc-bus voltage stably and provide or absorb real power. The inverter is controlled by carrier phase shifting with FPGA. The simulation model is

Renzhong Shan; Zhongdong Yin; Xiangning Xiao; Yajing Di; Ke Li

2009-01-01

166

Silicon foils growth by interface-controlled crystallization  

NASA Technical Reports Server (NTRS)

During interface controlled crystallization (ICC) the chance to accelerate the removal of crystallization heat is the basis for high pulling rates of about 100 mm/min. The forced heat flow from the extended crystallization front to a cooling ramp is controlled by a lubricating melt film which also influences the crystallization behavior by suppressing nucleation centers. The basic principles of this full casting technique are presented and the influences of process parameters on the morphology of prepared silicon foils are demonstrated. Three different types of crystalline structure were found in silicon foils grown to ICC technique: dendritic, coarse granular and monocrystalline with (111) 211 orientation. The criteria for their appearance of process variables are discussed.

Helmreich, D.

1984-01-01

167

Controlling the porosity and density of silicone rubber prosthetic materials.  

PubMed

The chemical components of the four silicone rubber polymers were reviewed. Methods of controlling the porosity and density of both the one-component semisolid prepolymer and the two-component fluid prepolymer systems were evaluated. The variables examined were deairing of the fluid systems; trial packing, pressure sealing, and processing of the semisolid materials; injection versus hand packing of the mold; the effects of moist-heat versus dry-heat application during processing; and the need for investment of the mold within the confines of a closed flask. It can be concluded that porosity of medical-grade silicone rubber polymers may be totally prevented, or accurately controlled, by proper handling techniques. PMID:6578331

Kent, K; Zeigel, R F; Kent, K; Frost, A L; Schaaf, N G

1983-08-01

168

Design and Evaluation of a 42-V Automotive Alternator With Integrated Switched-Mode Rectifier  

Microsoft Academic Search

This paper presents techniques for the design of high-power Lundell alternators with integrated switched-mode rectifiers. A multisection stator winding and interleaved rectifier arrangement is introduced that enables high power levels to be achieved using small semiconductor devices, and which greatly reduces the output filter capacitor requirements. We also demonstrate control methods suited for this interleaved system. In addition to accurate

Sai Chun Tang; David M. Otten; Thomas A. Keim; David J. Perreault

2010-01-01

169

Physics of the frequency response of rectifying organic Schottky diodes  

NASA Astrophysics Data System (ADS)

The frequency response of unipolar organic Schottky diodes used in a rectifying circuit, such as an RFID tag, has been investigated in detail. The time dependent response of rectifying circuits has been simulated solving both the Drift Diffusion and Poisson equations to model the hole transport within the diode, coupled with time dependent circuit equations. Several approximations have also been discussed. It turns out that the cut off frequency of the rectifying circuit is indeed limited by the carrier time-of-flight and not by the diode equivalent capacitance. Simulations have also been confirmed by comparison with experiments, involving diodes with different mobilities and thicknesses. This work confirms that the 13.56 MHz frequency can be reached using polymer semiconductors, as already experimentally demonstrated in the literature, by an adequate control of the active layer thickness.

Altazin, Stéphane; Clerc, Raphaël; Gwoziecki, Romain; Verilhac, Jean-Marie; Boudinet, Damien; Pananakakis, Georges; Ghibaudo, Gérard; Chartier, Isabelle; Coppard, Romain

2014-02-01

170

A silicon implementation of the fly's optomotor control system.  

PubMed

Flies are capable of stabilizing their body during free flight by using visual motion information to estimate self-rotation. We have built a hardware model of this optomotor control system in a standard CMOS VLSI process. The result is a small, low-power chip that receives input directly from the real world through on-board photoreceptors and generates motor commands in real time. The chip was tested under closed-loop conditions typically used for insect studies. The silicon system exhibited stable control sufficiently analogous to the biological system to allow for quantitative comparisons. PMID:11032035

Harrison, R R; Koch, C

2000-10-01

171

Distant Cytosolic Residues Mediate a Two-way Molecular Switch That Controls the Modulation of Inwardly Rectifying Potassium (Kir) Channels by Cholesterol and Phosphatidylinositol 4,5-Bisphosphate (PI(4,5)P2)*  

PubMed Central

Inwardly rectifying potassium (Kir) channels play an important role in setting the resting membrane potential and modulating membrane excitability. An emerging feature of several Kir channels is that they are regulated by cholesterol. However, the mechanism by which cholesterol affects channel function is unclear. Here we show that mutations of two distant Kir2.1 cytosolic residues, Leu-222 and Asn-251, form a two-way molecular switch that controls channel modulation by cholesterol and affects critical hydrogen bonding. Notably, these two residues are linked by a residue chain that continues from Asn-251 to connect adjacent subunits. Furthermore, our data indicate that the same switch also regulates the sensitivity of the channels to phosphatidylinositol 4,5-bisphosphate, a phosphoinositide that is required for activation of Kir channels. Thus, although cholesterol and phosphatidylinositol 4,5-bisphosphate do not interact with the same region of Kir2.1, these different modulators induce a common gating pathway of the channel.

Rosenhouse-Dantsker, Avia; Noskov, Sergei; Han, Huazhi; Adney, Scott K.; Tang, Qiong-Yao; Rodriguez-Menchaca, Aldo A.; Kowalsky, Gregory B.; Petrou, Vasileios I.; Osborn, Catherine V.; Logothetis, Diomedes E.; Levitan, Irena

2012-01-01

172

Magnetic field controllable nonvolatile resistive switching effect in silicon device  

NASA Astrophysics Data System (ADS)

A Si-SiO2-MgO device showing nonvolatile resistive switching effect is fabricated. It is observed the resistance of the device changed from high value to low value at a certain transition voltage after being stimulated by a large current. In addition, the transition voltage shifts reproducibly under a reversed large current. By applying a reading voltage in the range of the transition voltages, nonvolatile resistive switching phenomena with on/off ratio of about 10, endurance of more than 200 cycles and retention of more than 104 s is obtained. More importantly, it is also observed that the magnetic field could shift the transition voltage to higher values, affecting or even suppressing the resistive switching. The magnetic field controllable nonvolatile resistive switching effect in the silicon device suggested by this work may be helpful to the silicon based industry.

Wang, Jimin; Zhang, Xiaozhong; Piao, Hong-Guang; Luo, Zhaochu; Xiong, Chengyue; Wang, Xiaofeng; Yang, Fuhua

2014-06-01

173

Sized controlled synthesis, purification, and cell studies with silicon quantum dots  

Microsoft Academic Search

This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum

Amane Shiohara; Sujay Prabakar; Angelique Faramus; Chia-Yen Hsu; Ping-Shan Lai; Peter T. Northcote; Richard D. Tilley

2011-01-01

174

Functions of large conductance Ca2+-activated (BKCa), delayed rectifier (KV) and background K+ channels in the control of membrane potential in rabbit renal arcuate artery.  

PubMed

1. The types of K+ channel which determine the membrane potential of arcuate artery smooth muscle cells were investigated by patch-clamp recording from isolated cells and lumenal diameter measurements from intact pressurized renal arcuate arteries. 2. Single cells had a mean resting potential of -38 mV and were depolarized by 130 mM K+ but not by the Cl- channel blocker 4,4'-diisothiocyanatostilbene-2, 2'-disulphonic acid (DIDS). 3. Iberiotoxin did not affect the resting potential but inhibited spontaneous transient hyperpolarizations. Iberiotoxin or 1 mM tetraethylammonium (TEA+) constricted intact arteries. 3,4-Diaminopyridine (3,4-DAP)-sensitive delayed rectifier K+ (KV) channel current was elicited by depolarization but 3,4-DAP did not affect the resting potential or induce constriction in the intact artery. 4. A voltage-independent K+ current was inhibited by >= 0.1 mM barium (Ba2+) and unaffected by iberiotoxin, glibenclamide, apamin, 3,4-DAP and ouabain. In six out of ten cells, 1 mM Ba2+ depolarized the resting potential, while in the other cells the potential was resistant to all of the K+ channel blockers and ouabain. Ba2+ (0.1-1 mM) constricted the intact artery, but 10 microM Ba2+, 1 microM glibenclamide or 100 nM apamin had no effect. 5. The data suggest that resting potential is determined by background K+ channels, one type being Ba2+ sensitive and voltage independent, and another type being poorly defined due to its resistance to any inhibitor. Large conductance Ca2+-activated K+ (BKCa) and KV channels do not determine the resting potential but have separate functions to underlie transient Ca2+-induced hyperpolarizations and to protect against depolarization past about -30 mV. PMID:9679171

Prior, H M; Yates, M S; Beech, D J

1998-08-15

175

Precise Control of a Three-Phase Squirrel-Cage Induction Motor Using a Practical Cycloconverter  

Microsoft Academic Search

The advent of the silicon controlled rectifier has permitted the design of a practical cycloconverter source of 3-phase electrical power which can be continuously controlled in frequency, from dc to approximately one-half the input power frequency, as required to control the speed of a 3-phase induction motor. The correspondence between the applied stator frequency, the resulting magnetic flux phase rotation,

Walter Slabiak; Louis J. Lawson

1966-01-01

176

Fast recovery, high voltage silicon diodes for AC motor controllers  

NASA Technical Reports Server (NTRS)

The fabrication and characterization of a high voltage, high current, fast recovery silicon diode for use in AC motor controllers, originally developed for NASA for use in avionics power supplies, is presented. The diode utilizes a positive bevel PIN mesa structure with glass passivation and has the following characteristics: peak inverse voltage - 1200 volts, forward voltage at 50 amperes - 1.5 volts, reverse recovery time of 200 nanoseconds. Characterization data for the diode, included in a table, show agreement with design concepts developed for power diodes. Circuit diagrams of the diode are also given.

Balodis, V.; Berman, A. H.; Gaugh, C.

1982-01-01

177

Low Voltage Slow Controls for the Silicon Vertex Tracker  

NASA Astrophysics Data System (ADS)

Nuclear physics research requires the use of detectors, like the Silicon Vertex Tracker (SVT) being developed at Thomas Jefferson National Accelerator Facility, to understand the fundamental properties of particles. This detector is designed to reconstruct the paths of charged particles, aiding in the determination of their momentum. Each of the SVT's 66 individual modules is connected to a High Flex Circuit Board (HFCB). A HFCB requires 4 low voltage channels. A slow controls program was developed to control the voltage. The program allows the user to set the voltage at the 2.5 V required for the HFCB. The program is also capable of reading back the voltage and current. It includes features for real-time data monitoring and offline data analysis. The program will be expanded to control all 264 channels used for the final SVT as well as measure more parameters such as temperature and humidity.

Hammerton, Kalee

2012-10-01

178

Implementation issues of a fuzzy-logic-based three-phase active rectifier employing only Voltage sensors  

Microsoft Academic Search

Switch-mode rectifiers are becoming more and more interesting in those applications where bidirectional power flow, power-factor correction, and electromagnetic interference reduction are required. Typical active rectifiers include current or voltage sensors, however, in order to obtain low-cost systems, their number should be reduced. In this paper, a current-sensorless active rectifier with feedforward fuzzy logic control is presented and discussed. The

Carlo Cecati; Antonio Dell' Aquila; Agostino Lecci; Marco Liserre

2005-01-01

179

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2013-10-01

180

Silicon-on-insulator control impact-ionization-avalanche transistor  

NASA Astrophysics Data System (ADS)

In thin silicon-on-insulator structures, the gate effectively controls the longitudinal component of the electric field intensity in the pn+ junction, and thus the impact avalanche ionization of carriers. The present work proposes a device based on this operation principle: the control-impact-ionization-avalanche transistor, which achieves a transconductance of 0.14 (A/V)/mm. According to the developed theoretical model and preliminary experimental data, the device can be optimized to achieve very high transconductance and frequencies such as several (A/V)/mm at frequencies of the order of 100 MHz and lower, and about 1 (A/V)/mm in 0.1-1 THz range.

Dobrovolsky, V.; Pavljuk, S.; Rossokhaty, V.; Cristoloveanu, S.

2006-02-01

181

Surface Diffusion Controlled Formation of Nickel Silicides in Silicon Nanowires  

NASA Astrophysics Data System (ADS)

Nickel silicide/silicon contacts used in field-effect transistors (FET) based on silicon nanowires (SiNWs) can be formed by thermally activated axial intrusion of nickel silicides into the SiNW from prepatterned nickel reservoirs located at both ends of the NWs. This method seems promising for future electronic applications. Transformation of the longitudinal NW segments into single-crystalline nickel silicides throughout the entire NWs bulk has been interpreted as evidence of a volume diffusion control process. However, the volume diffusion coefficients of nickel in Ni2Si at 300°C to 400°C are inconsistent with observable nickel silicide intrusion lengths. The experimental results published so far show a distinct dependence of nickel silicide intrusion length on the silicon NW diameter, which is indicative of a surface diffusion or a surface reaction controlled process. In this work, this problem was considered theoretically in the framework of a model of a diffusion-controlled phase formation. Diffusion growth of a wedge-like new phase in a cylindrical NW was described using a quasistationary approximation. The rate of longitudinal growth depends on the NW radius, R, and decreases with the radius increase as ~ R -0.75. The dependence of R on annealing time, t, is close to t 0.5. The profile of the new phase was described for different combinations of two dimensionless parameters: R/ ? and D ?/ D s?, where ? is the thickness of the high-diffusivity surface layer with diffusion coefficient D s?, and D ? is the volume diffusion coefficient. After the formation of a continuous layer of a new phase, further growth is controlled exclusively by the interface diffusion of Ni along the nickel silicide surface and Si/Ni2Si interface. The growth kinetics depends on the ratio of diffusion coefficients D s?/ D b, where D b is the interface diffusion coefficient, and may be parabolic or linear. The calculated dependencies were compared with the published experimental results for nickel silicide formation in SiNWs. The analysis performed indicates that surface and interface diffusion of nickel play an important role in the formation of nickel silicides in NWs—a critical finding that should be considered in the design of SiNW FETs.

Katsman, A.; Yaish, Y.; Rabkin, E.; Beregovsky, M.

2010-04-01

182

Controlling the electrical resistance of silicon carbide powders  

Microsoft Academic Search

Conclusions A method is specified for determining the specific electrical resistance of silicon carbide powders; the characteristics of the materials used in the production of silicon carbide electric heaters are determined.

V. I. Kolynina; L. G. Gurvich; V. K. Zakharenkov

1986-01-01

183

Design of on-chip Transient Voltage Suppressor in a silicon-based transceiver IC to meet IEC system-level ESD specification  

Microsoft Academic Search

The on-chip Transient Voltage Suppressor (TVS) embedded in the silicon based transceiver IC has been proposed in this paper by using 0.8 ?m Bipolar-CMOS-DMOS (BCD) process. The structure of the on-chip TVS is a high voltage Dual Silicon-Controlled-Rectifier (DSCR) with ±19V of high holding voltage (Vh) under the evaluation of 100ns pulse width of the Transmission Line Pulsing (TLP) system.

Ryan Hsin-Chin Jiang; Tang-Kuei Tseng; Chi-Hao Chen; Che-Hao Chuang

2011-01-01

184

A new multiple loops linear control scheme applied to a current-injection three-phase unity-power-factor rectifier  

Microsoft Academic Search

In this paper, a new linear control strategy applied to a three-phase current injection AC-DC converter is presented. The proposed control scheme is based on the elaboration of the converter small-signal mathematical model, derived from the application of the state-space-averaging technique. The control design methodology of both current and voltage loops uses linear control theory. More precisely, each regulator's parameters

H. Kanaan; H. F. Blanchette; K. Al-Haddad; R. Chaffai; L. Duguay; F. Fnaiech

2002-01-01

185

Method for rapid, controllable growth and thickness, of epitaxial silicon films  

DOEpatents

A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor deposition by controlling the rate of silicon deposition in a temperature range that spans the transition from a monohydride to a hydrogen free silicon surface in a vacuum, to obtain phase-pure epitaxial silicon film of increased thickness is disclosed. The method includes placing a c-Si substrate in a HWCVD reactor chamber. The method also includes supplying a gas containing silicon at a sufficient rate into the reaction chamber to interact with the substrate to deposit a layer containing silicon thereon at a predefined growth rate to obtain phase-pure epitaxial silicon film of increased thickness.

Wang, Qi (Littleton, CO); Stradins, Paul (Golden, CO); Teplin, Charles (Boulder, CO); Branz, Howard M. (Boulder, CO)

2009-10-13

186

Gate-controlled resonant interband tunneling in silicon  

SciTech Connect

We present gate-controlled resonant interband tunneling on silicon <111>. The investigated structure principally consists of a vertical, gated p-i-n diode grown by molecular beam epitaxy. We evaluated the surface tunnel current from a gate-induced two-dimensional electron channel into the quantized hole states of a degenerately doped {delta}p{sup +} layer. This current reveals a negative differential resistance due to resonant interband tunneling in the forward biased p-i-n diode at 200 K. Even at room temperature the influence of this tunnel mechanism is observed. The experimental results are in good agreement with simulated band diagrams and their dependence on the applied voltages.

Sedlmaier, S.; Bhuwalka, Krishna K.; Ludsteck, A.; Schmidt, M.; Schulze, J.; Hansch, W.; Eisele, I. [Institute of Physics, Universitaet der Bundeswehr Muenchen, Werner-Heisenberg-Weg 39, D-85577 Neubiberg (Germany)

2004-09-06

187

High Voltage Slow Controls for the Silicon Vertex Tracker  

NASA Astrophysics Data System (ADS)

The slow controls program developed at Thomas Jefferson National Accelerator Facility, JLab, for the Silicon Vertex Tracker, SVT, controls and reports high voltage and reads back the current drawn. The SVT is a large acceptance spectrometer designed to detect charged particles and reconstruct their paths in order to determine their momentum. It consists of 66 identical modules, each of which is connected to a High Flex Circuit Board, HFCB. Each HFCB requires 2 high voltage channels. The slow controls LabVIEW program designed for the SVT allows the user to set the threshold settings at 75V required for the HFCB to operate. If the threshold settings for voltage or current are detected outside of the operating range the channel will shut-off at a ramp rate of 5V/sec to preserve the detector. The program includes features for real-time data monitoring and offline data analysis. It will be expanded to control 132 high voltage channels to be used in Hall B at JLab and will expand to measure more parameters such as temperature and humidity.

Chabwera, Minnae

2012-10-01

188

Stable silicone oil emulsion composition, article of manufacture, and method of fabric wrinkle control  

US Patent & Trademark Office Database

Silicone emulsion comprising: at least about 0.025% and less than about 10% of silicone oil; an active amount to emulsify said silicone oil and reduce surface tension of said composition of a surfactant system; and a an effective amount of a buffering system to maintain a pH of said composition to be at least about 6 for a period of at least about 3 months, are useful for controlling wrinkles in fabrics.

2005-06-21

189

Simplified input current waveshaping technique by using inductor voltage sensing for high power factor isolated Sepic, Cuk and flyback rectifiers  

Microsoft Academic Search

This paper, a new simple current waveshaping technique in CCM by using inductor voltage sensing for high power factor rectifier based on isolated Sepic, Cuk, and flyback converters is introduced and experimented. The duty ratio is obtained by comparing an integral signal of the rectified inductor voltage and a negative ramp carrier waveform. Using the proposed control technique, input voltage

T. Tanitteerapan; S. Mori

2002-01-01

190

Diodes and Rectifier Circuits - Solid State Principles.  

National Technical Information Service (NTIS)

Explains the principles of ac and dc current in solid state diodes and rectifiers. Uses schematics to show resistance and voltage flow. Reviews chemical and material makeup of donor and acceptor atoms. Also defines conductors, semiconductors, and insulato...

1994-01-01

191

Analysis of new multizone rectifier for electric locomotives of V185 type  

Microsoft Academic Search

In this work the new single-phase three-zone AC-DC voltage converter is compared with the existing scheme of the four-zone rectifier used in electric locomotives. It is shown, that in the new scheme of the three-zone (n-zone in general) rectifier essentially decrease reverse voltage on thyristors. Analytical expressions for total harmonic distortion of output voltage, input current, control and external characteristics,

A. P. Kosarev; A. G. Volkov; G. S. Zinoviev

2010-01-01

192

Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts  

NASA Technical Reports Server (NTRS)

The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.

Kerkar, Awdhoot V.; Henderson, Robert J. M.; Feke, Donald L.

1990-01-01

193

DQ-transformation approach for modelling and stability analysis of AC-DC power system with controlled PWM rectifier and constant power loads  

Microsoft Academic Search

In this paper a technique for analysing aircraft frequency wild power systems with constant power loads is developed and demonstrated. Power electronic based loads often behave as constant power loads, especially when feeding machine or actuator drives under current and speed control. The constant power (CP) loads can affect the stability of the power system. The problem is a particular

K.-N. Areerak; S. V. Bozhko; G. M. Asher; D. W. P. Thomas

2008-01-01

194

Implementation of a New Linear Control Technique Based on Experimentally Validated Small-Signal Model of Three-Phase Three-Level Boost-Type Vienna Rectifier  

Microsoft Academic Search

In this paper, the design and implementation of a new multiple-input-multiple-output linear control technique based on a theoretically established and experimentally validated small- signal model for the three-phase three-level boost-type ac\\/dc Vienna converter are presented. Averaging and local linearization techniques are used to derive the dynamic model expressed in the dqo reference frame. The resulted transfer functions are discretized for

Nesrine Bel Haj Youssef; Kamal Al-Haddad; Hadi Y. Kanaan

2008-01-01

195

Controlling carbon nanotube photoluminescence using silicon microring resonators.  

PubMed

We report on coupling between semiconducting single-wall carbon nanotubes (s-SWNT) photoluminescence and silicon microring resonators. Polyfluorene extracted s-SWNT deposited on such resonators exhibit sharp emission peaks, due to interaction with the cavity modes of the microring resonators. Ring resonators with radius of 5 ?m and 10 ?m were used, reaching quality factors up to 4000 in emission. These are among the highest values reported for carbon nanotubes coupled with an integrated cavity on silicon platform, which open up the possibility to build s-SWNT based efficient light source on silicon. PMID:24787283

Noury, Adrien; Roux, Xavier Le; Vivien, Laurent; Izard, Nicolas

2014-05-30

196

Inward-rectifier chloride currents in Reissner's membrane epithelial cells.  

PubMed

Sensory transduction in the cochlea depends on regulated ion secretion and absorption. Results of whole-organ experiments suggested that Reissner's membrane may play a role in the control of luminal Cl(-). We tested for the presence of Cl(-) transport pathways in isolated mouse Reissner's membrane using whole-cell patch clamp recording and gene transcript analyses using RT-PCR. The current-voltage (I-V) relationship in the presence of symmetrical NMDG-Cl was strongly inward-rectifying at negative voltages, with a small outward current at positive voltages. The inward-rectifying component of the I-V curve had several properties similar to those of the ClC-2 Cl(-) channel. It was stimulated by extracellular acidity and inhibited by extracellular Cd2+, Zn2+ and intracellular ClC-2 antibody. Channel transcripts expressed include ClC-2, Slc26a7 and ClC-Ka, but not Cftr, ClC-1, ClCa1, ClCa2, ClCa3, ClCa4, Slc26a9, ClC-Kb, Best1, Best2, Best3 or the beta-subunit of ClC-K, barttin. ClC-2 is the only molecularly-identified channel present that is a strong inward rectifier. This study is the first report of conductive Cl(-) transport in epithelial cells of Reissner's membrane and is consistent with an important role in endolymph anion homeostasis. PMID:20226170

Kim, Kyunghee X; Marcus, Daniel C

2010-04-01

197

Vacuum-stripped silicone binder for thermal-control paint  

NASA Technical Reports Server (NTRS)

Silicone elastomer is placed in evacuating system, heated to 160 C and held at this temperature for 24 hours. Elastomer is then cooled to room temperature in vacuum, producing upgraded, low outgassing polymer of increased molecular weight.

Gilligan, J. E.; Rogers, F. O.

1973-01-01

198

Controlling growth of aligned carbon nanotubes from porous silicon templates  

Microsoft Academic Search

Fabricating well-aligned carbon nanotubes, especially, on a silicon substrate is very important for their applications. In\\u000a this paper, an aligned carbon nanotube array has been prepared by pyrolysis of hydrocarbons catalyzed by nickel nanoparticles\\u000a embedded in porous silicon (PS) templates. High-magnification transmission electron microscopy images confirm that the nanotubes\\u000a are well graphitized. The PS substrates with pore sizes between 10

Dongsheng Xu; Guolin Guo; Linlin Gui; Youqi Tang; Zujin Shi; Zhaoxia Jin; Zhennan Gu

2000-01-01

199

Sloping profile and pattern transfer to silicon by shape-controllable 3-D lithography and ICP  

Microsoft Academic Search

This paper describes a simple and effective method to fabricate various shapes and profiles of three-dimensional (3-D) silicon microstructures using a shape-controllable 3-D lithography along with dry plasma etching. The first step is to fabricate 3-D photoresist patterns with various slopes and round profiles on a silicon substrate by the shape-controllable 3-D lithography using polymer dispersed liquid crystal (PDLC) films,

Jin-Wan Jeon; Jun-Bo Yoon; Koeng Su Lim

2007-01-01

200

PWM rectifier with low dc voltage ripple for magnet supply  

SciTech Connect

PWM bridge rectifiers with GTO switches are considered for application to particle accelerator magnet power supplies, where two-quadrant operation and extremely low dc current ripple are required. Different control strategies, with both preprogrammed and variable switching patterns, are examined and compared in view of optimization of the system performance. In particular, optimum digital PWM, multilevel delta modulation, and hybrid PWM/delta techniques are analyzed. In this paper the validity of the control methods is verified by simulation and experimental tests on a 60-kW prototype.

Ciscato, D. (Dept. of Electronics and Informatics, Univ. of Padova, Padova (Italy)); Malesani, L.; Rosetto, L.; Tenti, P. (Dept. of Electrical Engineering, Univ. of Padova, Padova (Italy)); Basile, G.L.; Pasti, M. (OCEM SpA, San Giorgio di Piano (Italy)); Voelker, F. (Proton Synchrotron Div., CERN, Geneva (Switzerland))

1992-04-01

201

Circuit topologies for PWM boost rectifiers operated from 1-phase and 3-phase AC supplies and using either single or split DC rail voltage outputs  

Microsoft Academic Search

This paper provides a survey of PWM boost rectifier circuit topologies for controlling a nonisolated DC-rail voltage whilst drawing supply currents at a unity fundamental power factor and with a low total harmonic distortion. Rectifier-leg topologies are classified by the number of switches and by the PWM waveforms generated. Complete rectifier circuit topologies are described for operation off 1-phase and

John C. Salmon

1995-01-01

202

A Monitor Wafer Based Controller For Pecvd Silicon Nitride Process On Amt 5000  

Microsoft Academic Search

In this paper we describe a monitor wafer based controller, developed for equipment without in-situ sensors. We report the controller's application to the plasma enhanced chemical vapor deposition of silicon nitride (PECVD Nitride) process run on Applied Materials Precision Reactor (AMT 5000). Using model based SQC, the controller compares product parameter measurements to model predictions to determine whether the process

P. K. Mozumder; Sharad Saxena; Dave Collins

1993-01-01

203

Steady State Analysis of the Rectified Superconducting Alternator.  

National Technical Information Service (NTIS)

Equation are derived to predict the electrical behavior of a three-phase superconducting alternator connected to a full-wave bridge rectifier. This is accomplished by expanding a previous analysis for conventional rectified alternators and adding computat...

T. A. Stuart M. W. Tripp

1977-01-01

204

Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer  

DOEpatents

Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

Carlson, David E. (Yardley, PA)

1980-01-01

205

Mechanisms controlling the silicon isotopic compositions of river waters  

Microsoft Academic Search

It has been proposed that silicon (Si) isotopes are fractionated during weathering and biological activity leading to heavy dissolved riverine compositions. In this study, the first seasonal variations of stable isotope compositions of dissolved riverine Si are reported and compared with concomitant changes in water chemistry. Four different rivers in Switzerland were sampled between March 2004 and July 2005. The

R. B. Georg; B. C. Reynolds; M. Frank; A. N. Halliday

2006-01-01

206

Controls on silicon cycling in Southeast Asian rice production systems  

NASA Astrophysics Data System (ADS)

Recent research suggests that silicon (Si) is beneficial for rice plants, i.e., a sufficient Si supply improves their resistance against pests and pathogens and increases the uptake of essential nutrients. Despite its potential importance for rice yields, cycling of Si in rice production systems is poorly studied. We assess plant-available Si (Sipa; determined using acetate extraction) in topsoils (Ap+Arp horizons) and Si uptake by plants at 70 paddy fields managed by local farmers in contrasting regions of Vietnam and the Philippines. First results show that Sipa contents are considerably larger in Philippine (217 ± 100 mg Sipa kg-1 ) than in Vietnamese (32 ± 19 mg Sipa kg-1) paddy soils. Rice straw from the Philippines contains 8.6 ± 0.9 % Si, straw from Vietnam 5.0 ± 1.2 % Si. Laboratory experiments showed that Si is limiting the growth of rice plants in some of the Vietnamese soils. We assume that differences in geo-/ pedologic conditions between Vietnam and the Philippines explain the data. Large Sipa contents in the Philippine soils are due to recent rock formation by active volcanism, hence, by a large Sipa input due to mineral weathering in recent geologic history. In contrast, parent materials of the Vietnamese paddy soils derive from old and highly weathered land surfaces. Hence, our data suggest that geo-/pedologic conditions are the main control for the availability of Si in paddy soils. Currently, we examine the relevance of agricultural practices for small-scale differences in the availability of Si within regions. Inadequate practices, such as removal of rice straw from the fields, might deplete Sipa in paddy soils causing a decrease in rice yields in some regions of Vietnam. We investigate the role of phytoliths (amorphous Si bodies contained in rice straw) as source of Sipa in paddy soils. Our methods include laboratory experiments and the assessment of turnover times of phytoliths in paddy soils; first results will be presented and discussed at the EGU conference.

Klotzbücher, Thimo; Marxen, Anika; Vetterlein, Doris; Jahn, Reinhold

2013-04-01

207

A modified boost topology to minimize distortion in PFC rectifier  

Microsoft Academic Search

The cusp distortion is an inherent behavior of all boost PFC rectifiers. Though the contribution of cusp distortion is small but it limits the maximum achievable performance in PFC rectifier. In spite of this fact, little effort has been made in the past to avoid cusp distortion. We will propose a new topology to minimize the distortion in boost rectifier.

Muhammad Mansoor Khan; Wu Zhi-Ming

2004-01-01

208

Mechanisms controlling the silicon isotopic compositions of river waters  

NASA Astrophysics Data System (ADS)

It has been proposed that silicon (Si) isotopes are fractionated during weathering and biological activity leading to heavy dissolved riverine compositions. In this study, the first seasonal variations of stable isotope compositions of dissolved riverine Si are reported and compared with concomitant changes in water chemistry. Four different rivers in Switzerland were sampled between March 2004 and July 2005. The unique high-resolution multi-collector ICP-MS Nu1700, has been used to provide simultaneous interference-free measurements of 28Si, 29Si and 30Si abundances with an average limiting precision of ± 0.04‰ on ? 30Si. This precision facilitates the clarification of small temporal variations in isotope composition. The average of all the data for the 40 samples is ? 30Si = + 0.84 ± 0.19‰ (± 1? SD). Despite significant differences in catchment lithologies, biomass, climate, total dissolved solids and weathering fluxes the averaged isotopic composition of dissolved Si in each river is strikingly similar with means of + 0.70 ± 0.12‰ for the Birs,+ 0.95 ± 0.22‰ for the Saane,+ 0.93 ± 0.12‰ for the Ticino and + 0.79 ± 0.19‰ for the Verzasca. However, the ? 30Si undergoes seasonal variations of up to 0.6‰. Comparisons between ? 30Si and physico-chemical parameters, such as the concentration of dissolved Si and other cations, the discharge of the rivers, and the resulting weathering fluxes, permits an understanding of the processes that control the Si budget and the fate of dissolved Si within these rivers. The main mechanism controlling the Si isotope composition of the mountainous Verzasca River appears to be a two component mixing between the seepage of soil/ground waters, with heavier Si produced by clay formation and superficial runoff associated with lighter Si during high discharge events. A biologically-mediated fractionation can be excluded in this particular river system. The other rivers display increasing complexity with increases in the proportion of forested and cultivated landscapes as well as carbonate rocks in the catchment. In these instances it is impossible to resolve the extent of the isotopic fractionation and contributed flux of Si contributed by biological processes as opposed to abiotic weathering. The presence of seasonal variations in Si isotope composition in mountainous rivers provides evidence that extreme changes in climate affect the overall composition of dissolved Si delivered to the oceans. The oceanic Si isotope composition is very sensitive to even small changes in the riverine Si isotope composition and this parameter appears to be more critical than plausible changes in the Si flux. Therefore, concurrent changes in weathering style may need to be considered when using the Si isotopic compositions of diatoms, sponges and radiolaria as paleoproductivity proxies.

Georg, R. B.; Reynolds, B. C.; Frank, M.; Halliday, A. N.

2006-09-01

209

Single-Phase Boost Rectifier with Resonant Snubber Switch Cell Operating in DCM  

NASA Astrophysics Data System (ADS)

Single-phase boost rectifier with a resonant snubber switch cell is studied. The resonant snubber switch cell consists of an only active power switching device and a LC resonant circuit, and can also provide the necessary control over the current. To turn on and off an active power device under the soft switching conditions, the rectifier is operated in the discontinuous conduction mode (DCM). The experimental results under the charge control confirm that the input current can nearly be wave-shaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu

210

Size controlled synthesis of silicon nanocrystals using cationic surfactant templates.  

PubMed

Alkyl-terminated silicon nanocrystals (Si NCs) are synthesized at room temperature by hydride reduction of silicon tetrachloride (SiCl?) within inverse micelles. Highly monodisperse Si nanocrystals with average diameters ranging from 2 to 6 nm are produced by variation of the cationic quaternary ammonium salts used to form the inverse micelles. Transmission electron microscopy imaging shows that the NCs are highly crystalline, while FTIR spectra confirm that the NCs are passivated by covalent attachment of alkanes, with minimal surface oxidation. UV-vis absorbance and photoluminescence spectroscopy show significant quantum confinement effects, with moderate absorption in the UV spectral range, and a strong blue emission with a marked dependency on excitation wavelength. The photoluminescence quantum yield (?) of the Si NCs exhibits an inverse relationship with the mean NC diameter, with a maximum of 12% recorded for 2 nm NCs. PMID:24027115

Linehan, Keith; Doyle, Hugh

2014-02-12

211

Gate-controlled donor activation in silicon nanowires.  

PubMed

Due to the proximity to an embedding medium with low dielectric constant (e.g., oxides), semiconductor nanowires have higher impurity ionization energy than their bulk counterparts, resulting lower free carrier density. Using ab initio calculations within density functional theory, we propose a way to reduce the ionization energy in nanowires by fabricating a special cross section with appropriate engineering of doping and an applied gate voltage. We demonstrate on a phosphorus-doped silicon nanowire that the ionization energy can be effectively tuned and the impurity backscattering can also be reduced. For instance, even without special engineering of doping, the free carrier density may increase by 40% in a silicon nanowire with 15 nm diameter and special cross section. Our proposal has profound implications to fabricate nanowire devices with high carrier density. PMID:20718483

Yan, Binghai; Frauenheim, Thomas; Gali, Adám

2010-09-01

212

Size control of erbium-doped silicon nanocrystals  

NASA Astrophysics Data System (ADS)

This work describes the effects of pyrolysis oven length and erbium precursor on the preparation of discrete erbium-doped silicon nanoparticles. These doped nanoparticles were prepared by the co-pyrolysis of disilane and the volatile complex Er(tmhd)3 (tmhd=2,2,6,6-tetramethyl-3,5-heptanedionato). The particle sizes and size distributions were determined using high resolution and conventional transmission electron microscopy. Erbium-doped silicon nanoparticles exhibit a selected area electron diffraction pattern consistent with the diamond cubic phase and a distinctive dark contrast in the transmission electron microscope. The presence of erbium is confirmed by x-ray energy dispersive spectroscopy. In general, the mean diameter of the individual nanoparticles increases as the length of the pyrolysis oven used during their preparation is increased.

John, John St.; Coffer, Jeffery L.; Chen, Yandong; Pinizzotto, Russell F.

2000-09-01

213

Controllable and facile fabrication of gold nanostructures for selective metal-assisted etching of silicon.  

PubMed

A method with the combination of organic-vapor-assisted polymer swelling and nanotransfer printing (nTP) is used to manufacture desirable patterns consisting of gold nano-clusters on silicon wafers for Au-assisted etching of silicon. This method remarkably benefits to the size control and regional selection of the deposited Au. By tuning the thickness of the Au films deposited on the polydimethylsiloxane (PDMS) stamps, along with the swelling of PDMS stamps in acetone atmosphere, the Au films are cracked into diverse nanostructures. These nanostructures are covalently transferred onto silicon substrates in a large scale and enable to accelerate the chemical etching of silicon. The etched areas are composed of porous structures which can be readily distinguished from the surroundings on optical microscope. PDMS stamps and the Au clusters provide the control over the feature of the etched areas and the porous silicon, respectively. The silicon surfaces with patterned porous features offer a platform for exploiting new functional templates, for example, they present a diversity of antireflective and fluorescent performance. PMID:24599660

Zhang, Xinyue; Zhu, Juan; Huang, Xiaopeng; Qian, Qiuping; He, Yonglin; Chi, Lifeng; Wang, Yapei

2014-06-01

214

Femtosecond-laser hyperdoping: controlling sulfur concentrations in silicon for band gap engineering  

NASA Astrophysics Data System (ADS)

Doping silicon to concentrations above the metal-insulator transition threshold yields a novel material that has potential for photovoltaic applications. By focusing femtosecond laser pulses on the surface of a silicon wafer in a sulfur hexafluoride (SF6) environment, silicon is doped with 1% atomic sulfur. This material exhibits near-unity, broadband absorption from the visible to the near infrared (< 0.5 eV, deep below the silicon band gap), and metallic-like conduction. These unusual optical and electronic properties suggest the formation of an intermediate band. We report on the femtosecond laser doping techniques we employ and the resulting material properties. By changing the laser parameters and ambient environment we can control the dopant profiles, crystallinity, and surface morphology. We perform optical absorption and temperature-dependent Hall measurements to investigate electron transport and to identify the energy states of the sulfur donors.

Sher, Meng-Ju; Winkler, Mark; Lin, Yu-Ting; Franta, Benjamin; Mazur, Eric

2012-02-01

215

RF sputtering for controlling dihydride and monohydride bond densities in amorphous silicon hydride  

DOEpatents

A process is described for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicone produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous solicone hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

Jeffery, F.R.; Shanks, H.R.

1980-08-26

216

The search for organic unimolecular rectifiers  

NASA Astrophysics Data System (ADS)

The continuing quest for an organic unimolecular rectifier is reviewed. Langmuir-Blodgett (LB) films of D-?-A molecules (D=one-electron donor, ?=carbamate, A=one-electron acceptor) have been prepared, and electrical current measurements through monolayers have been measured, both by macroscopic means and by scanning tunneling microscopy. A definitive experimental proof of the 1974 Aviram-Ratner Ansatz still eludes us.

Metzger, Robert M.

1992-07-01

217

High voltage GaN Schottky rectifiers  

Microsoft Academic Search

Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (VRB) up to 550 and >2000 V, respectively, have been fabricated. The on-state resistance, RON , was 6 m?·cm2 and 0.8 ? cm2 , respectively, producing figure-of-merit values for (VRB )2\\/RON in the range 5-48 MW·cm-2 . At low biases the reverse leakage current was proportional to the size

Gerard T. Dang; Anping P. Zhang; Fan Ren; Xianan A. Cao; Stephen J. Pearton; Hyun Cho; Jung Han; Jenn-Inn Chyi; C.-M. Lee; C.-C. Chuo; S. N. G. Chu; R. G. Wilson

2000-01-01

218

Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens  

SciTech Connect

Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R. [Core Systems, 1050 Kifer Road Sunnyvale, CA 94086 (United States); FI Silicon, 1050 Kifer Road Sunnyvale, CA 94086 (United States); Core Systems, 1050 Kifer Road Sunnyvale, CA 94086 (United States)

2012-11-06

219

Controlling optical properties and surface morphology of dry etched porous silicon  

NASA Astrophysics Data System (ADS)

Porous silicon is a potentially useful substrate for fluorescence and scattering enhancement, with a large surface to volume ratio and thermal stability providing a potentially regenerable host matrix for sensor development. A simple process using XeF2 gas phase etching for creating porous silicon is explained. Moreover, how pores diameter can be controlled reproducibly with commensurate effects upon the silicon reflection and pore distribution is discussed. In previous work with this new system, it was clear that control on pore size and morphology was required and a systematic optimization of process conditions was performed to produce greater consistency of the result. The influence of the duration of the pre-etching processing in HF, concentration of the HF in the pre-etching process, and the XeF2 exposure time during the dry etching on surface morphology, pore size, and optical reflectance is explored.

Cheung, Maurice C.-K.; Roche, Philip J. R.; Hajj-Hassan, Mohamad; Kirk, Andrew G.; Mi, Zetian; Chodavarapu, Vamsy P.

2011-01-01

220

An optical leaky wave antenna with silicon perturbations for electronic control  

NASA Astrophysics Data System (ADS)

An optical leaky wave antenna (OLWA) is a device that radiates a light wave into the surrounding space from a leaky wave (LW) guided mode or receives optical power from the surrounding space into a guided optical mode. In this work, we propose and provide a 3D analysis of a novel CMOS compatible OLWA made of a silicon nitride (Si3N4) waveguide comprising periodic silicon perturbations which allow electronic tuning capability. The analysis presented here includes the effect of the number of semiconductor perturbations, the antenna radiation pattern and directivity. We show that the number of the silicon perturbations has to be large to provide a long radiating section required to achieve radiation with high directivity. In other words, the proposed structure allows for a very narrow-beam radiation. Preliminary results are confirmed by exploiting leaky wave and antenna array factor theory, as well as verified by means of two full-wave simulators (HFSS and COMSOL). Our purpose is to ultimately use PIN junctions as building blocks for each silicon implantation for the electronic control of the radiation. In particular, the electronic tunability of the optical parameters of silicon (such as refractive index and absorption coefficient) via current injection renders itself the ideal platform for optical antennas that can facilitate electronic beam control, and boost the efficiency of optoelectronic devices such as light-emitting diodes, lasers and solar cells, and bio-chemical sensors.

Campione, Salvatore; Song, Qi; Boyraz, Ozdal; Capolino, Filippo

2011-09-01

221

Nitrogen doping-induced rectifying behavior with large rectifying ratio in graphene nanoribbons device  

NASA Astrophysics Data System (ADS)

By applying nonequilibrium Green's functions in combination with density-function theory, we investigate the electronic transport properties of armchair graphene nanoribbons devices with one undoped and one nitrogen-doped armchair graphene nanoribbons electrode. For the doped armchair graphene nanoribbons electrode, an N dopant is considered to substitute the center or edge carbon atom. The results show that the electronic transport properties are strongly dependent on the width of the ribbon and the position of the N dopant. The rectifying behavior with large rectifying ratio can be observed and can be modulated by changing the width of the ribbon or the position of the N dopant. A mechanism for the rectifying behavior is suggested.

Zeng, Jing; Chen, Ke-Qiu; He, Jun; Fan, Zhi-Qiang; Zhang, Xiao-Jiao

2011-06-01

222

Energy-harvesting shock absorber with a mechanical motion rectifier  

NASA Astrophysics Data System (ADS)

Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ‘mechanical motion rectifier (MMR)’, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.

Li, Zhongjie; Zuo, Lei; Kuang, Jian; Luhrs, George

2013-02-01

223

Programmable input power factor correction method for switch-mode rectifiers  

SciTech Connect

A programmable method for single- and three-phase switch-mode rectifiers (SMR`s), operating with discontinuous current conduction to control input power factor close to unity, is presented. Single-phase SMR operation is based on variable turn-on time, while three-phase SMR operation is based on constant turn-on time.

Dawande, M.S. [R.K.N. Engineering Coll., Nagpur (India). Dept. of Electrical Engineering] [R.K.N. Engineering Coll., Nagpur (India). Dept. of Electrical Engineering; Dubey, G.K. [Indian Inst. of Tech., Kanpur (India). Dept. of Electrical Engineering] [Indian Inst. of Tech., Kanpur (India). Dept. of Electrical Engineering

1996-07-01

224

Merging functional studies with structures of inward-rectifier K+ channels  

Microsoft Academic Search

Inwardly rectifying K+ (Kir) channels have a wide range of functions including the control of neuronal signalling, heart rate, blood flow and insulin release. Because of the physiological importance of these channels, considerable effort has been invested in understanding the structural basis of their physiology. In this review, we use two recent, high-resolution structures as foundations for examining our current

Delphine Bichet; Friederike A. Haass; Lily Yeh Jan

2003-01-01

225

Active Silicon Substrate MultiChip Module Technology for Sensor Signal Processing and Control  

Microsoft Academic Search

A new approach to build multi-chip modules (MCMs) using active silicon substrate (ASIS) technology is being developed by Lockheed for future sensor signal processing and control applications. The ASIS MCM inherently offers a functional platform versus other approaches using a passive nonfunctional substrate. The Lockheed ASIS design uses benzocyclobutene (BCB) for a low dielectric and copper for interconnect over an

Richard E. Pearson

1994-01-01

226

Outdoor performance stability and controlled light-soak testing of amorphous silicon multijunction modules at NREL.  

National Technical Information Service (NTIS)

The National Renewable Energy Laboratory (NREL) has been testing amorphous silicon (a-Si) Photovoltaic (PV) modules for more than a decade. NREL has been conducting controlled light-soak testing of multifunction a-Si modules to characterize their performa...

L. Mrig J. Burdick W. Luft B. Kroposki

1995-01-01

227

Exploring the Silicon Design Limits of Thin Wafer IGBT Technology: The Controlled Punch Through (CPT) IGBT  

Microsoft Academic Search

The paper introduces a new controlled punch through (CPT) IGBT buffer for next generation devices, which utilise thin wafers technology. The new concept is based on very shallow buffers with optimized doping profiles enabling minimum silicon design thicknesses close to the theoretical limit for a given voltage class. The advanced shaping of the buffer doping profile brings additional degree of

J. Vobecky; M. Rahimo; A. Kopta; S. Linder

2008-01-01

228

Structural Determinants of Gating in Inward-Rectifier K + Channels  

Microsoft Academic Search

The gating characteristics of two ion channels in the inward-rectifier K+ channel superfamily were compared at the single-channel level. The strong inward rectifier IRK1 (Kir 2.1) opened and closed with kinetics that were slow relative to those of the weakly rectifying ROMK2 (Kir 1.1b). At a membrane potential of ?60mV, both IRK and ROMK had single-exponential open-time distributions, with mean

Han Choe; Lawrence G. Palmer; Henry Sackin

1999-01-01

229

Self-controlled fabrication of single-crystalline silicon nanobeams using conventional micromachining.  

PubMed

This paper reports on a low-cost top-down approach to the nano-precision fabrication of nanobeams on single-crystalline silicon using only conventional micromachining technology. The fabrication technique takes advantage of the crystalline structure of silicon for controllable feature size reduction of nanobeams with atomically smooth surfaces and sharp edges. Applying a deliberate rotational misalignment in a 2 ?m resolution standard lithography process, followed by anisotropic wet etching of the silicon, nanobeams with well uniform widths as small as ?85 nm are fabricated on thin SOI substrates. As a proof of concept for the incorporation of such nanobeams within electromechancial structures, we successfully demonstrate thermally actuated resonators that show very high frequencies (close to 50 MHz). PMID:25036338

Mehdizadeh, Emad; Rahafrooz, Amir; Pourkamali, Siavash

2014-08-01

230

Resistive switching with self-rectifying behavior in Cu/SiOx/Si structure fabricated by plasma-oxidation  

NASA Astrophysics Data System (ADS)

We report a resistive switching memory structure based on silicon wafers by employing both materials and processing fully compatible with complementary metal-oxide semiconductor technology. A SiOx nanolayer was fabricated by direct plasma-oxidation of silicon wafers at room-temperature. Resistive switching behaviors were investigated on both p- and n-Si wafers, whereas self-rectifying effect was obtained in the Cu/SiOx/n-Si structure at low-resistance state. The self-rectifying effect was explained by formation of the Schottky barrier between the as-formed Cu filament and the n-Si. These results suggest a convenient and cost-efficient technical-route to develop high-density resistive switching memory for nowadays Si-based semiconductor industry.

Tang, G. S.; Zeng, F.; Chen, C.; Liu, H. Y.; Gao, S.; Li, S. Z.; Song, C.; Wang, G. Y.; Pan, F.

2013-06-01

231

Polytype control of spin qubits in silicon carbide  

NASA Astrophysics Data System (ADS)

The search for coherently addressable spin states in technologically important materials is a promising direction for solid-state quantum information science. Silicon carbide, a particularly suitable target, is not a single material but a collection of about 250 known polytypes, each with its own set of physical properties and technological applications. We show that in spite of these differences, the 4H-, 6H-, and 3C-SiC polytypes all exhibit optically addressable spins with long coherence times [1]. These results include room temperature spins in all three polytypes and suggest a new method for tuning quantum states using crystal polymorphism. Long spin coherence times allow us to use double electron-electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Since such inequivalent spin have distinct optical and spin transition energies, these interactions could lead to dipole-coupled networks of separately addressable spins.[4pt] [1] A. Falk et al., submitted

Falk, A. L.; Buckley, B. B.; Calusine, G.; Koehl, W. F.; Politi, A.; Awschalom, D. D.; Dobrovitski, V. V.; Zorman, C. A.; Feng, P. X.-L.

2013-03-01

232

Controlled growth of oriented amorphous silicon nanowires via a solid–liquid–solid (SLS) mechanism  

Microsoft Academic Search

Highly oriented amorphous silicon nanowires (a-SiNWs ) were grown on Si (111). The length and diameter of oriented SiNWs are almost uniform, which are 1?m and 25nm, respectively. Different from the well-known vapor–liquid–solid (VLS) for conventional whisker growth, it was found that growth of the a-SiNWs was controlled by a solid–liquid–solid mechanism (SLS). This synthesis method is simple and controllable.

D. P Yu; Y. J Xing; Q. L Hang; H. F Yan; J Xu; Z. H Xi; S. Q Feng

2001-01-01

233

Control of the ionization state of three single donor atoms in silicon  

NASA Astrophysics Data System (ADS)

By varying the front-gate and the substrate voltages in a short silicon-on-insulator trigate field-effect transistor, we control the ionization state of three arsenic donors. We obtain good quantitative agreement between three-dimensional electrostatic simulations and experiment for the control voltages at which the ionization takes place. It allows us to observe the three doubly occupied states As- at strong electric field in the presence of nearby source-drain electrodes.

Voisin, B.; Cobian, M.; Jehl, X.; Vinet, M.; Niquet, Y.-M.; Delerue, C.; de Franceschi, S.; Sanquer, M.

2014-04-01

234

Alternating to Direct: Rectifying Alternating Current  

NSDL National Science Digital Library

The Materials Science and Technology Teacher's Workshop (MAST) provides this activity for classes learning about diodes and electrical currents. The laboratory illustrates how diodes can be used to rectify alternating current. It uses a galvanometer to determine the direction of current flow when an AC or DC current is applied to the circuit containing a diode in series with a resistor and a galvanometer.The lesson includes step by step directions for the experiment.The activity should require about 20-30 minutes of class time to complete. Discussion questions and teacher notes are included.

2012-12-03

235

Development of high temperature gallium phosphide rectifiers  

NASA Technical Reports Server (NTRS)

Large area high performance, GaP rectifiers were fabricated by means of Zn diffusion into vapor phase epitaxial GaP. Devices with an active area of 0.01 sq cm typically exhibit forward voltages of 3 volts for a bias current of 1 ampere and have reverse breakdown voltages of 300 volts for temperatures from 27 C to 400 C. Typical device reverse saturation current at a reverse bias of 150 volts is less than 10 to the minus 9th power amp at 27 C and less than 0.000050 amp at 400 C.

Craford, M. G.; Keune, D. L.

1972-01-01

236

Polyamine Block of Inwardly Rectifying Potassium Channels  

PubMed Central

Polyamine blockade of inwardly rectifying potassium (Kir) channels underlies their steep voltage-dependence observed in native cells. The structural determinants of polyamine blockade and the structure-activity profile of endogenous polyamines requires specialized methodology for characterizing polyamine interactions with Kir channels. Recent identification and growing interest in the structure and function of prokaryotic Kir channels (KirBacs) has driven the development of new techniques for measuring ion channel activity. Several methods for measuring polyamine interactions with prokaryotic and eukaryotic Kir channels are discussed.

Kurata, Harley T.; Cheng, Wayland W.L.; Nichols, Colin G.

2011-01-01

237

Unity Power Factor Isolated Three-Phase Rectifier With Two Single-Phase Buck Rectifiers Based on the Scott Transformer  

Microsoft Academic Search

This paper proposes an isolated three-phase rectifier power-factor correction using two single-phase buckpreregulators in continuous conduction mode. The use of the Scott transformer renders a simple and robust rectifier to operate with unity power factor. With only two active switches, the rectifier is able to gener- ate symmetrical currents in the line and a regulated voltage out- put without any

Alceu André Badin; Ivo Barbi

2011-01-01

238

A passivity-based multilevel active rectifier with adaptive compensation for traction applications  

Microsoft Academic Search

The control of a single-phase multilevel H-bridge rectifier suitable for traction applications is considered. Such a converter often presents instability problems making difficult its design and uncertain its behavior. In this paper the use of a passivity-based controller is experimentally investigated. Such a controller achieves stability, unity power factor, good balancing between the two DC links, and satisfactory behavior even

Carlo Cecati; Antonio Dell' Aquila; Marco Liserre; Vito Giuseppe Monopoli

2003-01-01

239

Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz  

NASA Technical Reports Server (NTRS)

A group at UCLA, in collaboration with the Jet Propulsion Laboratory, has designed a voltage-controlled oscillator (VCO) created specifically for a compact, integrated, electronically tunable frequency generator useable for submillimeter- wave science instruments operating in extreme cold environments.

Wong, Alden; Larocca, Tim; Chang, M. Frank; Samoska, Lorene A.

2011-01-01

240

High Voltage GaN Schottky Rectifiers  

SciTech Connect

Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.

CAO,X.A.; CHO,H.; CHU,S.N.G.; CHUO,C.-C.; CHYI,J.-I.; DANG,G.T.; HAN,JUNG; LEE,C.-M.; PEARTON,S.J.; REN,F.; WILSON,R.G.; ZHANG,A.P.

1999-10-25

241

Single-shot readout and microwave control of an electron spin in silicon  

NASA Astrophysics Data System (ADS)

The electron spin of a donor in silicon is an excellent candidate for a solid-state qubit. It is known to have very long coherence and relaxation times in bulk [1], and several architectures have been proposed to integrate donor spin qubits with classical silicon microelectronics [2]. Here we show the first experimental proof of single-shot readout of an electron spin in silicon. The device consists of implanted phosphorus donors, tunnel-coupled to a silicon Single-Electron Transistor (SET), where the SET island is used as a reservoir for spin-to-charge conversion [3]. The large charge transfer signals allow readout fidelity >90% with 3 ?s response time. By measuring the occurrence of excited spin states as a function of wait time, we find spin lifetimes (T1) up to ˜ 6 s at B = 1.5 T, and a magnetic-field dependence T1-1 B^5 consistent with that of phosphorus donors in silicon [4]. In a subsequent experiment we have integrated the single-shot spin readout device with an on-chip microwave transmission line for coherent control of the electron spin. We have detected the spin resonance of a single electron, and observed two hyperfine-split resonance lines, consistent with Stark-shifted coupling to the ^31P nuclear spin. Further experiments are underway to demonstrate coherent spin control and observe Rabi oscillations. This demonstrates the microwave control of a single spin, combined -- for the first time in the same experiment -- with electrically detected single-shot spin readout. [1] A. M. Tyryshkin et al., Phys. Rev. B 68, 193207 (2003). [2] L. C. L. Hollenberg et al., Phys. Rev. B. 74, 045311 (2006). [3] A. Morello et al., Phys. Rev. B 80, 081307(R) (2009). [4] A. Morello et al., Nature 467, 687 (2010).

Morello, Andrea

2011-03-01

242

Digital implementation of a line current shaping algorithm for three phase high power factor boost rectifier without input voltage sensing  

Microsoft Academic Search

In this paper the implementation of a simple yet high performance digital current mode controller that achieves high power factor operation for three phase boost rectifier is described. The indicated objective is achieved without input voltage sensing and without transformation of the control variables into rotating reference frame. The controller uses the concept of resistance emulation for shaping of input

Souvik Chattopadhyay; V. Ramanarayanan

2004-01-01

243

Outwardly rectifying chloride channels and CF: A divorce and remarriage  

Microsoft Academic Search

Outwardly rectifying Cl- channels were originally thought to be the central element in cystic fibrosis. The role of these channels in CF was questioned to such an extent that doubts were rasied about the validity of the original experiments. Recent data reestablishes a role for outwardly rectifying Cl- channels (ORCC) in CF and suggests that the protein encoded by the

William B. Guggino

1993-01-01

244

A dual effect of formaldehyde on the inwardly rectifying potassium conductance in skeletal muscle.  

PubMed Central

1. The inwardly rectifying potassium conductance of the membrane of frog sartorius muscle fibres is greatly reduced by treatment of muscles for 30 min with a solution containing formaldehyde (10 mM). 2. A transient increase in the conductance of the inward rectifier is observed early during formaldehyde action. 3. Analysis of the biphasic time course of the conductance changes, as determined under controlled voltage conditions, suggests that treatment with formaldehyde alters simultaneously, but in opposite ways, two factors that determine the conductance of the inward rectifier. 4. The linear component of the current-voltage relation, which dominates the relation at strongly positive potentials, is not affected while the above changes occur. But on prolonged exposure to formaldehyde the leak conductance increases. 5. The effects of formaldehyde on the inward rectifier are reversible on prolonged superfusion with normal Ringer solution. 6. The slight inward rectification remaining after most of the extracellular K is replaced by Rb, is similarly reduced by treatment with formaldehyde. 7. The results are interpreted in terms of the chemical properties of formaldehyde and present views of the mechanisms of inward rectification.

Hutter, O F; Williams, T L

1979-01-01

245

High precision quantum control of single donor spins in silicon.  

PubMed

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using tight-binding and band minima basis approaches and compared to the recent precision measurements. In contrast with previous effective mass-based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work. PMID:17678301

Rahman, Rajib; Wellard, Cameron J; Bradbury, Forrest R; Prada, Marta; Cole, Jared H; Klimeck, Gerhard; Hollenberg, Lloyd C L

2007-07-20

246

A Simulation Study of Space Vector PWM Rectifier Based on PSCAD  

Microsoft Academic Search

\\u000a The simulation method of three-phase voltage source rectifier(VSR) using the Space Vector pulse width modulation (SVPWM) and\\u000a feedforward decoupling control strategy is studied in PSCAD. Firstly, the mathematical model of VSR under the rotating coordinates\\u000a axis was set up; then discussed the realization of SVPWM in PSCAD, and designed a decoupling control system of VSR; lastly,\\u000a compared the performance of

Dong-dong Li; Lu Wang

247

Operation of the LCC-type parallel resonant converter as a low harmonic rectifier  

Microsoft Academic Search

A single-phase high frequency transformer isolated AC-to-DC controlled rectifier with low line current harmonic distortion using a variable frequency controlled LCC-type (or series-parallel) resonant power converter (SPRC) is presented. A simple analysis and design procedure is used for designing the power converter for low line current harmonic distortion and high power factor operation. The converter performance characteristics have been verified

V. Belaguli; A. K. S. Bhat

1996-01-01

248

Quantum entanglement and spin control in silicon nanocrystal.  

PubMed

Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure (29)Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of (29)Si <100> axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of (29)Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution.PACS NUMBERS: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj. PMID:23028884

Berec, Vesna

2012-01-01

249

Quantum Entanglement and Spin Control in Silicon Nanocrystal  

PubMed Central

Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure 29Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of 29Si axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of 29Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution. PACS numbers: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj

Berec, Vesna

2012-01-01

250

TEMPO/viologen electrochemical heterojunction for diffusion-controlled redox mediation: a highly rectifying bilayer-sandwiched device based on cross-reaction at the interface between dissimilar redox polymers.  

PubMed

A couple of totally reversible redox-active molecules, which are different in redox potentials, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and viologen (V(2+)), were employed to give rise to a rectified redox conduction effect. Single-layer and bilayer devices were fabricated using polymers containing these sites as pendant groups per repeating unit. The devices were obtained by sandwiching the redox polymer layer(s) with indium tin oxide (ITO)/glass and Pt foil electrodes. Electrochemical measurements of the single-layer device composed of polynorbornene-bearing TEMPO (PTNB) exhibited a diffusion-limited current-voltage response based on the TEMPO(+)/TEMPO exchange reaction, which was almost equivalent to a redox gradient through the PTNB layer depending upon the thickness. The bilayer device gave rise to the current rectification because of the thermodynamically favored cross-reaction between TEMPO(+) and V(+) at the polymer/polymer interface. A current-voltage response obtained for the bilayer device demonstrated a two-step diffusion-limited current behavior as a result of the concurrent V(2+)/V(+) and V(+)/V(0) exchange reactions according to the voltage and suggested that the charge transport process through the device was most likely to be rate-determined by a redox gradient in the polymer layer. Current collection experiments revealed a charge transport balance throughout the device, as a result of the electrochemical stability and robustness of the polymers in both redox states. PMID:24559298

Tokue, Hiroshi; Oyaizu, Kenichi; Sukegawa, Takashi; Nishide, Hiroyuki

2014-03-26

251

Candidate locations for SPS rectifying antennas  

NASA Technical Reports Server (NTRS)

The feasibility of placing 120 Satellite Power System (SPS) rectifying antenna (rectenna) sites across the U.S. was studied. An initial attempt is made to put two land sites in each state using several land site selection criteria. When only 69 land sites are located, it is decided to put the remaining sites in the sea and sea site selection criteria are identified. An estimated projection of electrical demand distribution for the year 2000 is then used to determine the distribution of these sites along the Pacific, Atlantic, and Gulf Coasts. A methodology for distributing rectenna sites across the country and for fine-tuning exact locations is developed, and recommendations on rectenna design and operations are made.

Eberhardt, A. W.

1977-01-01

252

Topographic control on silicone surface using chemical oxidization method  

NASA Astrophysics Data System (ADS)

The paper describes a wet process for modifying the surface of polydimethylsiloxane (PDMS) using H 2SO 4/HNO 3 solutions. The oxidation on the surface of PDMS was confirmed by the examinations of Fourier transform infrared spectrometry (FTIR), contact angle of water drop and X-ray photoelectron spectroscopy (XPS). The hydrophobic surface of pristine PDMS was not only changed to hydrophilic, but also formed wrinkles on it after chemical modification. Bilayer systems, stiff oxidized PDMS layers were capped on soft PDMS foundations, would generate easily compressive stresses due to the large difference in volumetric contraction rates and led to form wrinkles on the surface. Experimental results demonstrated the periodicity of wrinkles was controllable by controlling the duration of oxidation. Therefore, wrinkles could be arranged orderly by the guidance of external forces before oxidization. The potential technology for generating and ordering wrinkles on the PDMS surface is valuable in the applications of pressure sensors, biology, micro-optics and nano-/micro-fabrication in the future.

Shih, Teng-Kai; Ho, Jeng-Rong; Chen, Chia-Fu; Whang, Wha-Tzong; Chen, Chien-Chung

2007-10-01

253

Serum proteins and paraproteins in women with silicone implants and connective tissue disease: a case–control study  

Microsoft Academic Search

Prior studies have suggested abnormalities of serum proteins, including paraproteins, in women with silicone implants but did not control for the presence of connective-tissue disease (CTD). This retrospective case–control study, performed in tertiary-care academic centers, assessed possible alterations of serum proteins, including paraproteins, in such a population. Seventy-four women with silicone implants who subsequently developed CTD, and 74 age-matched and

Gyorgy Csako; Rene Costello; Ejaz A Shamim; Terrance P O'Hanlon; Anthony Tran; Daniel J Clauw; H James Williams; Frederick W Miller

2007-01-01

254

Photoluminescent logic gate controlled by the optical Kerr effect exhibited by porous silicon  

NASA Astrophysics Data System (ADS)

The magnitude of the third order optical susceptibility exhibited by porous silicon monolayers was measured by a non-degenerated vectorial two-wave interaction. Optical irradiations at 488 nm and 532 nm wavelengths were employed to carry out the nonlinear optical experiments. Compared to bulk silicon material, a noticeable enhancement in the third order nonlinear optical response was identified. Photoluminescence and photoconductive properties were evaluated for the two studied wavelengths. The photoluminescent logic gate function AND was experimentally demonstrated using as a control a reflective optical Kerr gate configuration. A perceptible contribution for the third order optical nonlinearities seems to be related to the optical Kerr effect originated by excited states population. A two-level model was considered in order to describe the observed optical behavior.

de la Mora, M. B.; Torres-Torres, C.; Nava, R.; Trejo-Valdez, M.; Reyes-Esqueda, J. A.

2014-07-01

255

Controlling the Er content of porous silicon using the doping current intensity  

PubMed Central

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process. PACS 81.05.Rm; 82.45.Rr

2014-01-01

256

Polarization Control in Silicon Photonic Waveguide Components Using Cladding Stress Engineering  

NASA Astrophysics Data System (ADS)

This chapter reviews the characteristics of SOI ridge waveguide birefringence, as governed by the waveguide cross-section geometry, the cladding stress level, and cladding thickness. Typical stress levels in dielectric cladding films such as silicon dioxide and silicon nitride are such that the stress-induced birefringence is of comparable magnitude to the waveguide geometrical birefringence. Therefore the total waveguide birefringence can be precisely controlled by counter-balancing these two factors. The application of this technique for achieving polarization independence in a variety of photonic components is described, as well as an example of polarization splitting. Passive and active tuning of the stress-induced birefringence is discussed. The use of birefringence tuning to enhance the efficiency in optical parametric processes and stress-induced Pockels electro-optic effect are also briefly addressed.

Xu, Dan-Xia

257

Controlled line shaped electron beam for silicon zone melting recrystallization on float glass substrates  

SciTech Connect

A line shaped electron beam system for the zone melting recrystallization (ZMR) of thick silicon films on float glass substrates is described. The low thermal stability of the glass requires a rapid regulated zone heating. The electron beam system allows the ZMR in a continuous scan without pulsing. The setup consists of the tungsten wire with a Pierce reflector as line cathode and the moving substrate as anode. A negative voltage applied on the reflectors limits the electron emission and provides the necessary control. The melt energy for optimized processing decreases with an increase of the velocity. The beam profiles and penetration depth of the electrons is discussed. Homogenous polycrystalline silicon areas of several 10 cm{sup 2} are achieved on a tungsten coated borosilicate float glass for the intended use as solar cell absorber.

Gromball, F.; Groth, C.; Mueller, J. [Department of Micro Systems Technology, Technical University Hamburg-Harburg, Eissendorfer Strasse 42, 21073 Hamburg (Germany)

2005-06-15

258

Insertion of intelligent hydrogel into silicone resin for thermal control applications  

NASA Astrophysics Data System (ADS)

As a kind of intelligent temperature-sensitive polymer, the poly (N-isopropylacrylamide) (PNIPA) hydrogel has lower critical solution temperature (LCST) of 33°C. PNIPA could change from transparency to opacification due to its phase separation. In this work, silicone coatings were doped with PNIPA particles, which were obtained by rotary cutting after N-isopropylacrylamide cross link reaction between N-isopropylacrylamide and N, N-methylenebisacrylamide in the aqueous solution below 20°C. The morphology and optical properties were characterized by SEM, FTIR and UV-Vis-NIR, respectively. The results show that combination of silicone resin and PNIPA particles enhances the diffuse reflection and operability in applications. It proves that the reversible thermal chronic property of PNIPA is useful for intelligent thermal control application.

Wei, Hua; Ge, Dengteng; Fan, Zeng; Liu, Chang; He, Xiaodong; Li, Yao

2009-07-01

259

Gate-controlled-diodes in silicon-on-sapphire: A computer simulation  

NASA Technical Reports Server (NTRS)

The computer simulation of the electrical behavior of a Gate-Controlled Diode (GCD) fabricated in Silicon-On-Sapphire (SOS) was described. A procedure for determining lifetime profiles from capacitance and reverse current measurements on the GCD was established. Chapter 1 discusses the SOS structure and points out the need of lifetime profiles to assist in device design for GCD's and bipolar transistors. Chapter 2 presents the one-dimensional analytical formula for electrostatic analysis of the SOS-GCD which are useful for data interpretation and setting boundary conditions on a simplified two-dimensional analysis. Chapter 3 gives the results of a two-dimensional analysis which treats the field as one-dimensional until the silicon film is depleted and the field penetrates the sapphire substrate. Chapter 4 describes a more complete two-dimensional model and gives results of programs implementing the model.

Gassaway, J. D.

1974-01-01

260

Polypropylene vs silicone Ahmed valve with adjunctive mitomycin C in paediatric age group: a prospective controlled study  

PubMed Central

Purpose To compare the results of silicone and polypropylene Ahmed glaucoma valves (AGV) implanted during the first 10 years of life. Methods A prospective study was performed on 50 eyes of 33 patients with paediatric glaucoma. Eyes were matched to either polypropylene or silicone AGV. In eyes with bilateral glaucoma, one eye was implanted with polypropylene and the other eye was implanted with silicone AGV. Results Fifty eyes of 33 children were reviewed. Twenty five eyes received a polypropylene valve, and 25 eyes received a silicone valve. Eyes implanted with silicone valves achieved a significantly lower intraocular pressure (IOP) compared with the polypropylene group at 6 months, 1 year, and 2 years postoperatively. The average survival time was significantly longer (P=0.001 by the log-rank test) for the silicone group than for the polypropylene group and the cumulative probability of survival by the log-rank test at the end of the second year was 80% (SE: 8.0, 95% confidence interval (CI): 64–96%) in the silicone group and 56% (SE: 9.8, 95% CI: 40–90%) in the polypropylene group. The difference in the number of postoperative interventions and complications between both groups was statistically insignificant. Conclusion Silicone AGVs can achieve better IOP control, and longer survival with less antiglaucoma drops compared with polypropylene valves in children younger than 10 years.

El Sayed, Y; Awadein, A

2013-01-01

261

Sensorless optimization of dead times in DC-DC converters with synchronous rectifiers  

Microsoft Academic Search

This paper introduces an approach to achieve optimum dead times in dc-dc converters with synchronous rectifiers without sensing any of the power-stage signals other than the output voltage. The dead times are adjusted adaptively to minimize the duty-cycle command, which results in maximization of the converter efficiency. The method is particularly well suited for digital controller implementation, requiring no additional

Vahid Yousefzadeh; Dragan Maksimovic ´

2006-01-01

262

Evaluation of ultra-compact rectifiers for low power, high-speed, permanent-magnet generators  

Microsoft Academic Search

Literature reports several future portable and distributed power supplies in the watt to kilowatt range based on rotating machinery equipped with a variable-speed permanent-magnet generator. In order to generate a constant dc voltage, an ultra-compact, highly efficient, low power rectifier is required. In this paper, different topologies are compared concerning losses, volume and control complexity. The most suitable, the half

D. Krahenbuhl; C. Zwyssig; K. Bitterli; M. Imhof; J. W. Kolar

2009-01-01

263

A Simple Single-Input–Single-Output (SISO) Model for a Three-Phase PWM Rectifier  

Microsoft Academic Search

The challenge in controlling a three-phase pulsewidth modulation (PWM) rectifier under balanced conditions arises from the fact that the state-space averaged model reported in literature has a multi-input-multi-output nonlinear structure and furthermore exhibits a nonminimum phase feature. In this paper, a simple single-input-single-output model is constructed by separating the d -axis and the q-axis dynamics through appropriate nonlinear feedforward decoupling

Bo Yin; Ramesh Oruganti; Sanjib Kumar Panda; Ashoka K. S. Bhat

2009-01-01

264

A Single-Phase Boost Rectifier System for Wide Range of Load Variations  

Microsoft Academic Search

Converters operated in discontinuous-conduction-mode (DCM) and in continuous-conduction-mode (CCM) are suitable for lighter and higher loads, respectively. A new, constant switching frequency based single-phase rectifier system is proposed, which operates in DCM and in CCM for outputs less than and greater than 50% rated load, respectively, covering a wide range of load variation. The power circuit and the control circuit

Rajesh Ghosh; G. Narayanan

2007-01-01

265

Adaptation of a Space Vector Modulation to a Single-Phase Three Level Rectifier  

Microsoft Academic Search

This paper deals with the analysis, design and operation of a control system for a single-phase three-level rectifier with a neutral -point-clamped (NPC) topology. Usually the desired operating conditions for this type of converter are: unity displacement factor, output DC voltage regulation and neutral point voltage balancing. A d -q reference frame has been utilized in this work for modeling

Joan Salaet; Montserrat Corbalán

266

Influence of input supply voltage unbalances on the performance of AC\\/DC buck rectifiers  

Microsoft Academic Search

This paper deals with the effects of input supply voltage unbalance on the steady-state, small-signal dynamic and transient performance of AC\\/DC buck rectifiers with modulation magnitude and phase angle control. Operations with balanced and unbalanced input supply voltage source are compared. A comprehensive analysis based on the complex d-q-n synchronous reference frame transformation and harmonic balance technique shows that third

Olorunfemi Ojo; Ishwar Bhat

1994-01-01

267

Single-Phase Voltage-Quadrupler Rectifier Using Only One Dual-Switch Power Module  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier using only one dual-switch power module is presented. This is based on the half-bridge converter and the higher output voltage can easily be obtained by introducing the pumping action. The prototype, employing a power module with two insulated-gate bipolar transistors, is implemented. The experimental results under the current-mode control confirm that the input current can be wave-shaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu; Haraguchi, Takahiro

268

Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures  

SciTech Connect

Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

2002-04-01

269

HfO2 based memory devices with rectifying capabilities  

NASA Astrophysics Data System (ADS)

We report on the fabrication and characterization of metal/insulator/metal capacitor like devices, with both rectifying and hysteretic features. Devices are formed by two junctions, Ti/HfO2 and Co/HfO2. Each junction exhibits highly repetitive hysteretic I-V curves with a sharp transition from a high to a low resistance state (3-4 orders of magnitude jump). The opposite transition (from low to high) is induced by polarity reversal. The rectifying non-crossing characteristics of the I-V branches denote their potential use as a multifunctional device, acting as a built-in rectifier and memory cell in a single device. Based on the phenomenological model description by Zazpe et al. [Appl. Phys. Lett. 103, 073114 (2013)], we propose a circuital equivalent representation supported on switchable rectifying junctions. By exploring different electrode connections, we disentangle the role of the bulk transport in HfO2 devices.

Quinteros, C.; Zazpe, R.; Marlasca, F. G.; Golmar, F.; Casanova, F.; Stoliar, P.; Hueso, L.; Levy, P.

2014-01-01

270

Silicon oxide nanowires: facile and controlled large area fabrication of vertically oriented silicon oxide nanowires for photoluminescence and sensor applications.  

PubMed

We describe a technique for the fabrication of dense and patterned arrays of aligned silicon oxide nanowires for applications in surface modification, optoelectronic, and electromechanical based devices. Conventional techniques for the fabrication of silicon oxide nanowires based on the vapor-liquid-solid (VLS) chemical vapor deposition (CVD) processes involve the use of high temperatures and catalysts. We demonstrate a technique that extends the use of a plasma thermal reactive ion etching for the fabrication of aligned silicon oxide nanowires with aspect ratios extending up to 20 and lengths exceeding 1 ?m. The process incorporates phase separated PS-b-P4VP block copolymer loaded with an iron salt. The iron salt preferentially segregates into the P4VP layer and during an O2 etch is not removed but forms a hexagonally packed array on the silicon oxide substrate. Further etching with CHF3/O2 gas mixture over time can generate nanodots, to nanopillars, and then nanowires of silicon oxide. The photoluminescence property of the as-fabricated nanowire arrays as well as the parasitic ferromagnetic effect from the iron oxide-tipped section of the wires resulting in coalescence under an scanning electron microscope (SEM) are demonstrated. This technique is simpler compared to existing VLS fabrication approaches and can be used for the direct fabrication of patterned arrays of nanowires when a laser interference ablation step is incorporated into the fabrication procedure. PMID:23915216

Alabi, Taiwo R; Yuan, Dajun; Bucknall, David; Das, Suman

2013-09-25

271

Chemical control over the formation and reactivity of ultra-thin films and amino-terminated layers on silicon  

Microsoft Academic Search

The physical-chemical properties of several interfacial systems of technological relevance are investigated, having as a common goal the elucidation of strategies towards their atomic- and molecular-level control. Such systems can be classified in three groups: (i) ultra-thin films deposited using metalorganic precursors, (ii) metalorganic monolayers on silicon, and (iii) amine-functionalized silicon surfaces. Experimental, theoretical and chemometric methods are conveniently combined

Juan Carlos F. Rodriguez-Reyes

2010-01-01

272

A simple system for remote monitoring of cathodic rectifiers  

SciTech Connect

Efforts to remotely monitor Con Edison's (New York, New York) cathodic protection (CP) rectifiers began in 1988 with the use of a monitor made specifically for this purpose. The company sought an effective, economic system to remotely monitor its cathodic protection rectifiers. This article describes the systems tried, especially the computerized system that proved most reliable and economical, while complying with federal and state regulations.

Dolan, M.P. (Consolidated Edison Co. of New York Inc., New York (United States))

1993-05-01

273

Average-value modeling of automotive alternator-rectifier systems  

Microsoft Academic Search

Average-value modeling is indispensable for dynamic characterization of automotive machine-converter systems. However, analytical derivation of accurate models at low voltage applications is challenging due to the non-ideal characteristics of semiconductor switches (rectifier diodes). This paper presents a parametric average-value model of a car alternator-rectifier system. The model parameters take into account the diode forward voltage drop and are extracted using

Sina Chiniforoosh; Pooya Alaeinovin; Ali Davoudi; Juri Jatskevich; Patrick L. Chapman

2008-01-01

274

Dual Modulation of an Inwardly Rectifying Potassium Conductance  

Microsoft Academic Search

The modulation of a constitutively active IRK1-like inwardly rectifying potassium channel, that is endogenously expressed in the RBL-2H3 cell, was studied with the whole-cell patch-clamp technique. Activation of G-proteins by intracellular application of GTP?S revealed a dual modulation of the inward rectifier. An initial increase in inward current amplitude was induced by GTP?S, followed by a profound inhibition of the

S. V. P JONES

1997-01-01

275

Design, fabrication, and characterization of gallium nitride high power rectifiers  

Microsoft Academic Search

The edge termination design, device modeling, fabrication and characterization of gallium nitride (GaN) high power diode rectifiers are reported in this dissertation. The important parameter sets of GaN materials and physical models are first reviewed and applied to the standard drift-diffusion device simulator MEDICI(TM). Theoretical calculations of GaN high power rectifiers have been made based on the breakdown voltage, the

Kwang Hyeon Baik

2004-01-01

276

Controlled blueshift of the resonant wavelength in porous silicon microcavities using ion irradiation  

NASA Astrophysics Data System (ADS)

High-energy focused proton beam irradiation has been used to controllably blueshift the resonant wavelength of porous silicon microcavities in heavily doped p-type wafers. Irradiation results in an increased resistivity, hence a locally reduced rate of anodization. Irradiated regions are consequently thinner and of a higher refractive index than unirradiated regions, and the microcavity blueshift arises from a net reduction in the optical thickness of each porous layer. Using this process wafers are patterned on a micrometer lateral scale with microcavities tuned to different resonant wavelengths, giving rise to high-resolution full-color reflection images over the full visible spectrum.

Mangaiyarkarasi, D.; Breese, M. B. H.; Ow, Y. S.; Vijila, C.

2006-07-01

277

Controlled blueshift of the resonant wavelength in porous silicon microcavities using ion irradiation  

SciTech Connect

High-energy focused proton beam irradiation has been used to controllably blueshift the resonant wavelength of porous silicon microcavities in heavily doped p-type wafers. Irradiation results in an increased resistivity, hence a locally reduced rate of anodization. Irradiated regions are consequently thinner and of a higher refractive index than unirradiated regions, and the microcavity blueshift arises from a net reduction in the optical thickness of each porous layer. Using this process wafers are patterned on a micrometer lateral scale with microcavities tuned to different resonant wavelengths, giving rise to high-resolution full-color reflection images over the full visible spectrum.

Mangaiyarkarasi, D.; Breese, M. B. H.; Ow, Y. S.; Vijila, C. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Institute of Materials Research Engineering, 3 Research Link, Singapore 117602 (Singapore)

2006-07-10

278

Offshore wind farm grid connection using a novel diode-rectifier and VSC-inverter based HVDC transmission link  

Microsoft Academic Search

This paper carries out a technical feasibility study on the use of HVDC diode based rectifiers for the connection of large off-shore wind farms, together with an on-shore voltage source converter. An integrated control technique for the overall system is developed and validated by means of PSCAD simulation of the distributed wind farm together with the complete HVDC link. The

S. Bernal-Perez; S. Ano-Villalba; R. Blasco-Gimenez; J. Rodriguez-D'Derlee

2011-01-01

279

Precision control of thermal transport in cryogenic single-crystal silicon devices  

NASA Astrophysics Data System (ADS)

We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1 K. It is shown that the phonon mean-free-path ? is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than ?, even when the surface is fairly smooth, 5-10 nm rms, and the peak thermal wavelength is 0.6 ?m. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ?, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of ±8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

2014-03-01

280

Rectifying thermal fluctuations: Minimal pumping and Maxwell's demon  

NASA Astrophysics Data System (ADS)

Molecular complexes with movable components form the basis of nanoscale machines. Their inherent stochastic nature makes it a challenge to generate any controllable movement. Rather than fighting these fluctuations, one can utilize them by the periodic modulation of system parameters, or stochastic pumping. For the no-pumping theorem (NPT), which establishes minimal conditions for directed pumping, we present a simplified proof using an elementary graph theoretical construction. Motivated by recent experiments, we propose a new class of "hybrid" models combining elements of both the purely discrete and purely continuous descriptions prevalent in the field. We formulate the NPT in this hybrid framework to give a detailed justification of the original experiment observation. We also present an extension of the NPT to open stochastic systems. Next we consider the paradox of "Maxwell's demon," an imaginary intelligent being that rectifies thermal fluctuations in a manner that seems to violate the second law of thermodynamics. We present two exactly solvable, autonomous models that can reproduce the actions of the demon. Of necessity, both of these models write information on a memory device as part of their operation. By exposing their explicit, transparent mechanisms, our models offer simple paradigms to investigate the autonomous rectification of thermal fluctuations and the thermodynamics of information processing.

Mandal, Dibyendu

281

Oscillatory spin-polarized tunnelling from silicon quantum wells controlled by electric field  

NASA Astrophysics Data System (ADS)

Spin-dependent electronic transport is widely used to probe and manipulate magnetic materials and develop spin-based devices. Spin-polarized tunnelling, successful in ferromagnetic metal junctions, was recently used to inject and detect electron spins in organics and bulk GaAs or Si. Electric field control of spin precession was studied in III-V semiconductors relying on spin-orbit interaction, which makes this approach inefficient for Si, the mainstream semiconductor. Methods to control spin other than through precession are thus desired. Here we demonstrate electrostatic modification of the magnitude of spin polarization in a silicon quantum well, and detection thereof by means of tunnelling to a ferromagnet, producing prominent oscillations of tunnel magnetoresistance of up to 8%. The electric modification of the spin polarization relies on discrete states in the Si with a Zeeman spin splitting, an approach that is also applicable to organic, carbon-based and other materials with weak spin-orbit interaction.

Jansen, Ron; Min, Byoung-Chul; Dash, Saroj P.

2010-02-01

282

Synchronous rectifiers versus Schottky diodes: a comparison of the losses of a synchronous rectifier versus the losses of a Schottky diode rectifier  

Microsoft Academic Search

A brief description of the differences in current flow through a MOSFET and a Schottky diode establishes the basis for a prediction of future device performance. Two different forward converter designs are used to illustrate the expected performance differences between the synchronous rectifier and Schottky diode designs. The current levels were selected to provide the designer with a more intuitive

Carl Blake; Dan Kinzer; Peter Wood

1994-01-01

283

Performance evaluation of silicon carbide devices in power converters  

Microsoft Academic Search

Commercial silicon carbide (SiC) Schottky and PIN diodes, and JFETs were characterized for static conduction and dynamic switching performances in hard- and soft-switching buck converters. The results are compared with the measured data obtained from similarly rated silicon and GaAs devices. It is shown that for low-voltage rectifiers the only real advantage of SiC over silicon and GaAs is the

Krishna Shenai; Philip G. Neudeck

2000-01-01

284

Three-Phase Ac Buck Rectifier using Normally-On SiC JFETs at 150 kHz Switching Frequency  

Microsoft Academic Search

For many applications of high-performance three- phase AC converters, silicon carbide (SiC) switching devices promise breakthroughs in performance and power density. The SiC JFET technology is maturing, and will likely be the first SiC power switch available for applications requiring blocking voltages on the order of 1 kV. In this paper, a 2 kW three-phase buck rectifier with 150 kHz

Callaway J. Cass; Rolando Burgos; Fred Wang; Dushan Boroyevich

2007-01-01

285

Hydrogenated amorphous silicon deposited under accurately controlled ion bombardment using pulse-shaped substrate biasing  

SciTech Connect

We have applied pulse-shaped biasing to the expanding thermal plasma deposition of hydrogenated amorphous silicon at substrate temperatures {approx}200 deg. C and growth rates around 1 nm/s. Substrate voltage measurements and measurements with a retarding field energy analyzer demonstrate the achieved control over the ion energy distribution for deposition on conductive substrates and for deposition of conductive materials on nonconductive substrates. Presence of negative ions/particles in the Ar-H{sub 2}-SiH{sub 4} plasma is deduced from a voltage offset during biasing. Densification of the material at low Urbach energies is observed at a deposited energy <4.8 eV/Si atom and attributed to an increase in surface mobility of mobile species as well as well as surface atom displacement. The subsequent increase in Urbach energy >4.8 eV/Si atom is attributed to bulk atom displacement in subsurface layers. We make the unique experimental abservation of a decreasing Tauc band gap at increasing total hydrogen concentration - this allows to directly relate the band gap of amorphous silicon to the presence of nanovoids in the material.

Wank, M. A.; Swaaij, R. A. C. M. M. van; Zeman, M. [Photovoltaic Materials and Devices Group/DIMES, Delft University of Technology, P.O. Box 5053, Delft 2600 GB (Netherlands); Kudlacek, P.; Sanden, M. C. M. van de [Department of Applied Physics, Plasma and Material Processing Group, Eindhoven University of Technology, Eindhoven 5600 MB (Netherlands)

2010-11-15

286

Controlling the surface roughness of epitaxial SiC on silicon  

NASA Astrophysics Data System (ADS)

The surface of cubic silicon carbide (3C-SiC) hetero-epitaxial films grown on the (111) surface of silicon is a promising template for the subsequent epitaxial growth of III-V semiconductor layers and graphene. We investigate growth and post-growth approaches for controlling the surface roughness of epitaxial SiC to produce an optimal template. We first explore 3C-SiC growth on various degrees of offcut Si(111) substrates, although we observe that the SiC roughness tends to worsen as the degree of offcut increases. Hence we focus on post-growth approaches available on full wafers, comparing chemical mechanical polishing (CMP) and a novel plasma smoothening process. The CMP leads to a dramatic improvement, bringing the SiC surface roughness down to sub-nanometer level, though removing about 200 nm of the SiC layer. On the other hand, our proposed HCl plasma process appears very effective in smoothening selectively the sharpest surface topography, leading up to 30% improvement in SiC roughness with only about 50 nm thickness loss. We propose a simple physical model explaining the action of the plasma smoothening.

Mishra, N.; Hold, L.; Iacopi, A.; Gupta, B.; Motta, N.; Iacopi, F.

2014-05-01

287

Dynamic nuclear polarization of 29Si via spin S=1 centers in isotopically controlled silicon  

NASA Astrophysics Data System (ADS)

We report the results of the experiments on dynamic nuclear polarization (DNP) of 29Si nuclei under saturation the electron paramagnetic resonance (EPR) transitions of the photoexcited spin S=1 states of the oxygen+vacancy complexes in irradiated 29Si isotopically controlled silicon. The effect of isotope 29Si abundance on the line width and hyperfine structure of the Si-SL1 EPR spectra was observed. It was shown clearly that the decrease of the 29Si abundance leads to the transformation the DNP mechanism from the “differential” to “resolved” solid-effect accompanied with the increase of DNP degree. High steady-state 29Si nuclear polarization of 6% due to “resolved” solid-effect was achieved in silicon crystals with the 29Si isotope abundance below 4.7%. It was found that the DNP induced by saturation the hyperfine structure EPR lines of triplet centers does not follow the symmetric first derivative EPR line shape, showing the additional contribution to the DNP process.

Itahashi, T.; Hayashi, H.; Itoh, K. M.; Poloskin, D. S.; Vlasenko, L. S.; Vlasenko, M. P.

2009-12-01

288

A randomized controlled trial comparing nonoxynol-9 lubricated condoms with silicone lubricated condoms for prophylaxis  

PubMed Central

OBJECTIVE: We tested the effect of nonoxynol-9 (N-9) in condom lubrication on the risk of acquiring STD and genital discomfort. METHODS: The study was a triple masked, randomised controlled trial comparing N-9 lubricated condoms with plain silicone lubricated condoms among Dominican female sex workers. RESULTS: Randomisation provided two groups (313 for N-9 and 322 for plain) similar in baseline characteristics, but extensive loss to follow up occurred (56 women in each group completed the 24 week follow up). Most vaginal acts with clients were protected with condoms (99% of vaginal sex) but fewer acts with non-clients were protected (43% of vaginal sex). No significant differences occurred in rates of cervical infections (N-9 = 3.4 per 100 person months v plain = 2.8), trichomoniasis (N-9 = 2.8 v plain = 3.6), or discomfort rates (N-9 = 0.82 v plain = 0.92). CONCLUSIONS: Plain silicone lubricated condoms are as effective as N-9 lubricated condoms, cost less, have longer expected shelf life, and therefore may be the better condom to provide. ?????

Roddy, R. E.; Cordero, M.; Ryan, K. A.; Figueroa, J.

1998-01-01

289

On the DSP-based switch-mode rectifier with robust varying-band hysteresis PWM scheme  

Microsoft Academic Search

This paper presents the development of digital signal processor (DSP) based switch-mode rectifier (SMR) with robust varying-band hysteresis current-controlled (HCC) pulse width modulated (PWM) schemes. First, a robust fixed-frequency HCC PWM control scheme is developed. Through robust harmonic spectrum shaping, the constant frequency control performance is insensitive to the changes of system parameters and operating condition, and the low frequency

Sheng-Hua Li; Chang-Ming Liaw

2004-01-01

290

Characterization of a proton-activated, outwardly rectifying anion channel  

PubMed Central

Anion channels are present in every mammalian cell and serve many different functions, including cell volume regulation, ion transport across epithelia, regulation of membrane potential and vesicular acidification. Here we characterize a proton-activated, outwardly rectifying current endogenously expressed in HEK293 cells. Binding of three to four protons activated the anion permeable channels at external pH below 5.5 (50% activation at pH 5.1). The proton-activated current is strongly outwardly rectifying, due to an outwardly rectifying single channel conductance and an additional voltage dependent facilitation at depolarized membrane potentials. The anion channel blocker 4,4?-diisothiocyanostilbene-2,2?-disulphonic acid (DIDS) rapidly and potently inhibited the channel (IC50: 2.9 ?m). Flufenamic acid blocked this channel only slowly, while mibefradil and amiloride at high concentrations had no effect. As determined from reversal potential measurements under bi-ionic conditions, the relative permeability sequence of this channel was SCN?> I?> NO3?> Br?> Cl?. None of the previously characterized anion channel matches the properties of the proton-activated, outwardly rectifying channel. Specifically, the proton-activated and the volume-regulated anion channels are two distinct and separable populations of ion channels, each having its own set of biophysical and pharmacological properties. We also demonstrate endogenous proton-activated currents in primary cultured hippocampal astrocytes. The proton-activated current in astrocytes is also carried by anions, strongly outwardly rectifying, voltage dependent and inhibited by DIDS. Proton-activated, outwardly rectifying anion channels therefore may be a broadly expressed part of the anionic channel repertoire of mammalian cells.

Lambert, Sachar; Oberwinkler, Johannes

2005-01-01

291

Electrical control of interfacial trapping for magnetic tunnel transistor on silicon  

NASA Astrophysics Data System (ADS)

We demonstrate an electrical control of an interfacial trapping effect for hot electrons injected in silicon by studying a magnetic tunnel transistor on wafer bonded Si substrate. Below 25 K, hot electrons are trapped at the Cu/Si interface, resulting in collector current suppression through scattering in both parallel and antiparallel magnetic configurations. Consequently, the magneto-current ratio strongly decreases from 300% at 27 K to 30% at 22 K. The application of a relatively small electric field (˜333 V/cm) across the Cu/Si interface is enough to strip the trapped electrons and restore the magneto-current ratio at low temperature. We also present a model taking into account the effects of both electric field and temperature that closely reproduces the experimental results and allows extraction of the trapping binding energy (˜1.6 meV).

Lu, Y.; Lacour, D.; Lengaigne, G.; Le Gall, S.; Suire, S.; Montaigne, F.; Hehn, M.; Wu, M. W.

2014-01-01

292

Doping strategies to control A-centres in silicon: insights from hybrid density functional theory.  

PubMed

Hybrid density functional theory is used to gain insights into the interaction of intrinsic vacancies (V) and oxygen-vacancy pairs (VO, known as A-centres) with the dopants (D) germanium (Ge), tin (Sn), and lead (Pb) in silicon (Si). We determine the structures as well as binding and formation energies of the DVO and DV complexes. The results are discussed in terms of the density of states and in view of the potential of isovalent doping to control A-centres in Si. We argue that doping with Sn is the most efficient isovalent doping strategy to suppress A-centres by the formation of SnVO complexes, as these are charge neutral and strongly bound. PMID:24667874

Wang, H; Chroneos, A; Londos, C A; Sgourou, E N; Schwingenschlögl, U

2014-05-14

293

Luminescent isolated diamond particles with controllably embedded silicon-vacancy colour centres  

NASA Astrophysics Data System (ADS)

A technique to fabricate isolated diamond particles with controllably embedded silicon-vacancy (Si-V) colour centres is described. Particle growth and Si doping are performed by microwave plasma-enhanced chemical vapour deposition (CVD) using silane as a source of impurity atoms. The Si-V centres have a strong narrow-band photoluminescence (PL) at room temperature. The dependence of PL intensity of the 738 nm zero-phonon line (ZPL) on silane concentration in the feed-gas mixture exhibits a pronounced maximum. A comparison of the PL and Raman spectra shows that there is an evident correlation between the ZPL intensity and the presence of structural defects and nondiamond carbon phases that act as nonradiative recombination centres suppressing radiative recombination. The results open the door for using the powerful CVD technique for large-scale production of photostable near-infrared single-photon emitters and noncytotoxic biomarkers.

Grudinkin, S. A.; Feoktistov, N. A.; Medvedev, A. V.; Bogdanov, K. V.; Baranov, A. V.; Vul', A. Ya; Golubev, V. G.

2012-02-01

294

Optimization of surface temperature distribution for control of point defects in the silicon single crystal  

NASA Astrophysics Data System (ADS)

Optimization of crystal surface temperature distribution is performed for the control of point defects in a silicon single crystal grown by the Czochralski process. In the optimization problem, we seek an optimal solution that minimizes the level of point defects while the radial uniformity of temperature is maximized. In order to solve the optimization problem with the equality constraints described by partial differential equations, the variational principle is used. Based on the calculus of variations and the method of Lagrange multiplier, the Euler-Lagrange equations are derived and solved by the finite difference method. In order to handle inequality constraints, the penalty function method is also applied. The optimal distribution of the crystal surface temperature is expected to provide an insight for the design of thermal surroundings such as the thermal shield configuration and the heater/cooler position.

Sung Woo, Hwa; Hoon Jeong, Ja; Kang, In Seok

2003-01-01

295

Improving solar grade silicon by controlling extended defect generation and foreign atom defect interactions  

NASA Astrophysics Data System (ADS)

Multicrystalline silicon has a high commercial potential for solar cell applications. Extended lattice defects, such as dislocations and grain boundaries, are important as recombination and storage centers for metallic impurities. Their control is essential to obtain high efficiencies of the solar cell. Important parameters for the assessment of the final efficiency of the solar cells are the distribution and structure of the defects and their impact on the lifetime of minority carriers. The current understanding of the nucleation mechanisms of the most important defects during crystal growth will be described. Interaction processes between mobile impurities and extended defects are important for the recombination activity. Measurements of the recombination behavior and the contamination level will be presented. Finally, the ramifications on the solar cell efficiency shall be discussed.

Möller, H. J.; Kaden, T.; Scholz, S.; Würzner, S.

2009-07-01

296

A diode rectifier series tap on an HVDC line  

SciTech Connect

Electrical energy of a rather small isolated source in vicinity of an HVDC line may be transmitted via the same line by application of a series tapping station. For such purposes, a diode rectifier series tap, which offers considerable savings as well as a high degree of reliability, is proposed and discussed in this paper. Digital simulation studies have been carried out for a 10% diode rectifier series tap on an otherwise point-to-point HVDC system (Manitoba Hydro's Bipole II) using Electromagnetic Transients Program (EMTP). The results reveal the technical feasibility of the idea, without the need for any dc circuit breaker.

Arabi, S.; Tarnawecky, M.Z.

1985-09-01

297

Room temperature coherent control of defect spin qubits in silicon carbide.  

PubMed

Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical electronic and optical technologies. PMID:22051676

Koehl, William F; Buckley, Bob B; Heremans, F Joseph; Calusine, Greg; Awschalom, David D

2011-11-01

298

Tensile-mode fatigue tests and fatigue life predictions of single crystal silicon in humidity controlled environments  

Microsoft Academic Search

This paper reports on a tensile-mode fatigue test in a constant humidity, even in a very high humidity, to reveal the mechanism of fatigue fractures of MEMS materials. A newly developed tensile-mode fatigue tester using the electrostatic grip can control the humidity from 25% RH to 90% RH. Using this tester, the fatigue life and strength of single crystal silicon

Y. Yamaji; K. Sugano; O. Tabata; T. Tsuchiya

2007-01-01

299

Non-Dissipative Snubber for Rectifying Diodes in a High-Power DC-DC Converter  

NASA Astrophysics Data System (ADS)

In a high output current DC-DC converter, most power dissipation comes from rectifying diodes. In this paper, a novel non-dissipative snubber is proposed for the rectifying diodes to reduce the power dissipation of the rectifying circuit. This snubber is applied to the center-tapped rectifying circuit in a full-bridge DC-DC converter. As a result, the efficiency has been improved to 91% on the prototype of 12V/80A output.

Hirokawa, Masahiko; Ninomiya, Tamotsu

300

Method of seismic data enhancement using a phase of rectified trace seismic parameter  

SciTech Connect

The method is described of developing a specific seismic data parameter from seismic trace data, comprising: receiving processed seismic trace data for a selected plane of investigation; rectifying the seismic trace data; producing the Hilbert transform of the rectified trace data; determining the instantaneous phase using Hilbert transformed rectified data; and interpreting geological significance of the plane of investigation using instantaneous phase of the rectified and transformed data.

Stebens, B.; Parsons, R.K.; Baumel, R.T.; Terral, D.K.; Yedlin, M.J.

1986-12-30

301

37. VIEW OF SIX GAP ROTARY RECTIFIER FOR MAINTAINING CORONA ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

37. VIEW OF SIX GAP ROTARY RECTIFIER FOR MAINTAINING CORONA DISCHARGE IN THE COTTRELL ELECTROSTATIC GENERATORS. THE SYSTEM WAS CAPABLE OF PROVIDING 88,000 VOLTS TO THE ELECTRODES WITHIN THE PRECIPITATOR CHAMBER THE UNIT WAS LOCATED TO THE REAR OF BOILER 904 IN AN ENCLOSED ROOM. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

302

Seismic triggering by rectified diffusion in geothermal systems  

Microsoft Academic Search

Widespread seismicity was triggered by the June 28, 1992, Landers California, earthquake at a rate which was maximum immediately after passage of the exciting seismic waves. Rectified diffusion of vapor from hydrothermal liquids and magma into bubbles oscillating in an earthquake can increase the local pore pressure to seismically significant levels within the duration of the earthquake. In a hydrothermal

Bradford Sturtevant; Hiroo Kanamori; Emily E. Brodsky

1996-01-01

303

A Diode Rectifier Series Tap on an HVDC Line  

Microsoft Academic Search

Electrical energy of a rather small isolated source in vicinity of an HVDC line may be transmitted via the same line by application of a series tapping station. For such purposes, a diode rectifier series tap, which offers considerable savings as well as a high degree of reliability, is proposed and discussed in this paper. Digital simulation studies have been

S. Arabi; M. Z. Tarnawecky

1985-01-01

304

Systemintegrated Active Power Filter for Three-Phase Rectifier Application  

Microsoft Academic Search

This paper proposed a novel three-phase dynamically decoupled active power filter (APF) topology suitable for compensating three-phase rectifier loads. With superior stability characteristics, the possibilities of load source impedance resonance can be eliminated. This active filter can be implemented in combination with passive filters thus power rating and heat dissipation of voltage source inverter stage can be minimized. The system

Han Yang; Muhammad Mansoor Khan

2007-01-01

305

High rectifying behavior in Al/Si nanocrystal-embedded SiOxNy/p-Si heterojunctions  

NASA Astrophysics Data System (ADS)

We examine the electrical properties of MIS devices made of Al/Si nanocrystal-SiOxNy/p-Si. The J-V characteristics of the devices present a high rectifying behavior. Temperature measurements show that the forward current is thermally activated following the thermal diffusion model of carriers. At low reverse bias, the current is governed by thermal emission amplified by the Poole-Frenkel effect of carriers from defects located at the silicon nanocrystals/SiOxNy interfaces, whereas tunnel conduction in silicon oxynitride matrix dominates at high reverse bias. The devices exhibit a rectification ratio >104 for the current measured at V = ± 1 V. Study reveals that thermal annealing in forming gas (H2/N2) improves the electrical properties of the devices due to the passivation of defects.

Jacques, E.; Pichon, L.; Debieu, O.; Gourbilleau, F.; Coulon, N.

2011-05-01

306

A high speed comparator based active rectifier for wireless power transfer systems  

Microsoft Academic Search

Wireless power transfer technique can be used in many applications nowadays. The main limitation of this wireless power transfer system is in their interface circuitry. In this paper, a highly efficient active rectifier is proposed. By adopting the high speed comparator and, proposed rectifier solved the turn on and off delay of power transistor problem of conventional rectifier and shows

Yang Sun; Chang-jin Jeong; Seok-kyun Han; Sang-gug Lee

2011-01-01

307

Active filtering function of three-phase PWM boost rectifier under different line voltage conditions  

Microsoft Academic Search

Slight hardware and algorithm modifications as well as a higher power ratio of a three-phase pulsewidth-modulation (PWM) rectifier make compensation of neighboring nonlinear power load possible. The active filtering function enlarges the functionality of PWM rectifiers, which decreases the cost of additional installation of compensating equipment. It gives a chance to fulfill both shunt active filter (SAF) and PWM rectifier

Mariusz Cichowlas; Mariusz Malinowski; Marian P. Kazmierkowski; Dariusz L. Sobczuk; Pedro Rodríguez; Josep Pou

2005-01-01

308

Re-using and re-rating older rectifiers with new DC\\/DC choppers  

Microsoft Academic Search

The development of high power DC\\/DC converters (more commonly know as chopper rectifiers) allows customers the option to keep older rectifier transformers and refurbished systems if reconfiguring or installing new cell line loads. Normally, new cell line impedances would require the replacement of transformer\\/rectifier equipment. This paper is intended to describe how one can change the output operating range of

J. Beak; P. Buddingh; V. Scaini

2000-01-01

309

Dynamic nuclear polarization of {sup 29}Si nuclei in isotopically controlled phosphorus doped silicon  

SciTech Connect

Dynamic nuclear polarization (DNP) of {sup 29}Si nuclei in isotopically controlled silicon single crystals with the {sup 29}Si isotope abundance f{sub 29Si} varied from 1.2% to 99.2% is reported. It was found that both the DNP enhancement and {sup 29}Si nuclear spin-lattice relaxation time under saturation of the electron paramagnetic resonance transitions of phosphorus donors increase with the decrease in the {sup 29}Si abundance. A remarkably large steady-state DNP enhancement, E{sup ss}=2680 which is comparable to the theoretical upper limit of 3310, has been achieved through the ''resolved'' solid effect that has been identified clearly in the f{sub 29Si}=1.2% sample. The DNP enhancement depends not only on the {sup 29}Si abundance but also on the electron spin-lattice relaxation time that can be controlled by temperature and/or illumination. The linewidth of {sup 29}Si NMR spectra after DNP shows a linear dependence on f{sub 29Si} for f{sub 29Si}{<=}10% and changes to a square-root dependence for f{sub 29Si}{>=}50%. Comparison of experimentally determined nuclear polarization time with nuclear spin diffusion coefficients indicates that the rate of DNP is limited by the polarization transfer rather than by spin diffusion.

Hayashi, Hiroshi; Itahashi, Tatsumasa; Itoh, Kohei M.; Vlasenko, Leonid S.; Vlasenko, Marina P. [School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); A. F. Ioffe Physico-Technical Institute, 194021 Saint Petersburg (Russian Federation)

2009-07-15

310

Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights  

NASA Astrophysics Data System (ADS)

Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H2O2 electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 ?m. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ˜670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ˜660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K.

2014-05-01

311

Etude de l'amelioration des Diodes Schottky sur Silicium Amorphe Prepare par Pulverisation Cathodique (Study of Improvements to Schottky Diodes on Amorphous Silicon, Prepared by Cathodic Sputtering).  

National Technical Information Service (NTIS)

Schottky diodes on amorphous hydrogenated silicon have been successfully prepared, each layer of the structure having been deposited by cathodic sputtering. Electrical measurements show that the diodes are good quality rectifiers with a current saturation...

L. Vieux-Rochaz

1982-01-01

312

Degradation in silicon solar cells caused by the formation of Schottky barrier contacts during accelerated testing  

Microsoft Academic Search

When p+\\/n silicon solar cells having a lightly doped substrate, i.e. no back surface field, were subjected to accelerated stress testing an irregularity occurred in the VI characteristic along with the resulting loss of power output. Evidence is presented which indicates that this is due to formation of a rectifying Schottky barrier between the back metal contact and the silicon,

J. W. Lathrop; C. W. Davis; K. Misiakos

1984-01-01

313

Deconvolving the controls on the deep ocean's silicon stable isotope distribution  

NASA Astrophysics Data System (ADS)

We trace the marine biogeochemical silicon (Si) cycle using the stable isotope composition of Si dissolved in seawater (expressed as ?30Si). Open ocean ?30Si observations indicate a surprisingly strong influence of the physical circulation on the large-scale marine Si distribution. Here, we present an ocean general circulation model simulation that deconvolves the physical and biogeochemical controls on the ?30Si distribution in the deep oceanic interior. By parsing dissolved Si into its preformed and regenerated components, we separate the influence of deep water formation and circulation from the effects of biogeochemical cycling related to opal dissolution at depth. We show that the systematic meridional ?30Si gradient observed in the deep Atlantic Ocean is primarily determined by the preformed component of Si, whose distribution in the interior is controlled solely by the circulation. We also demonstrate that the ?30Si value of the regenerated component of Si in the global deep ocean is dominantly set by oceanic regions where opal export fluxes to the deep ocean are large, i.e. primarily in the Southern Ocean's opal belt. The global importance of this regionally dynamic Si cycling helps explain the observed strong physical control on the oceanic ?30Si distribution, since most of the regenerated Si present within the deep Atlantic and Indo-Pacific Oceans is in fact transported into these basins by deep waters flowing northward from the Southern Ocean. Our results thus provide a mechanistic explanation for the observed ?30Si distribution that emphasizes the dominant importance of the Southern Ocean in the marine Si cycle.

de Souza, Gregory F.; Slater, Richard D.; Dunne, John P.; Sarmiento, Jorge L.

2014-07-01

314

SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications  

SciTech Connect

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.

Onar, Omer C [ORNL] [ORNL; Tang, Lixin [ORNL] [ORNL; Chinthavali, Madhu Sudhan [ORNL] [ORNL; Campbell, Steven L [ORNL] [ORNL; Miller (JNJ), John M. [JNJ-Miller PLC] [JNJ-Miller PLC

2014-01-01

315

Controllable shrinking of inverted-pyramid silicon nanopore arrays by dry-oxygen oxidation.  

PubMed

A novel and simple technique for the controllable shrinkage of inverted-pyramid silicon (Si) nanopore arrays is reported. The Si nanopore arrays with sizes from 60 to 150 nm, made using a combination of dry and wet etching, were shrunk to sub 10 nm, or even closed, using direct dry-oxygen oxidation at 900?° C. The shrinkage process of the pyramidal nanopore induced by oxidation was carefully modeled and simulated. The simulation was found to be in good agreement with the experimental data within most of the oxidation time range. Using this method, square nanopore arrays with an average size of 30 nm, and rectangular nanopores and nanoslits with feature sizes as small as 8 nm, have been obtained. Furthermore, focused ion beam cutting experiments revealed that the inner structure of the nanopore after the shrinkage kept its typical inverted-pyramid shape, which is of importance in many fields such as biomolecular sensors and ionic analogs of electronic devices, as well as nanostencils for surface nano-patterning. PMID:24285505

Deng, Tao; Chen, Jian; Li, Mengwei; Wang, Yifan; Zhao, Chenxu; Zhang, Zhonghui; Liu, Zewen

2013-12-20

316

Controllable shrinking of inverted-pyramid silicon nanopore arrays by dry-oxygen oxidation  

NASA Astrophysics Data System (ADS)

A novel and simple technique for the controllable shrinkage of inverted-pyramid silicon (Si) nanopore arrays is reported. The Si nanopore arrays with sizes from 60 to 150 nm, made using a combination of dry and wet etching, were shrunk to sub 10 nm, or even closed, using direct dry-oxygen oxidation at 900?° C. The shrinkage process of the pyramidal nanopore induced by oxidation was carefully modeled and simulated. The simulation was found to be in good agreement with the experimental data within most of the oxidation time range. Using this method, square nanopore arrays with an average size of 30 nm, and rectangular nanopores and nanoslits with feature sizes as small as 8 nm, have been obtained. Furthermore, focused ion beam cutting experiments revealed that the inner structure of the nanopore after the shrinkage kept its typical inverted-pyramid shape, which is of importance in many fields such as biomolecular sensors and ionic analogs of electronic devices, as well as nanostencils for surface nano-patterning.

Deng, Tao; Chen, Jian; Li, Mengwei; Wang, Yifan; Zhao, Chenxu; Zhang, Zhonghui; Liu, Zewen

2013-12-01

317

Controllable light-induced conic structures in silicon nanowire arrays by metal-assisted chemical etching  

NASA Astrophysics Data System (ADS)

Silicon nanowires (SiNWs) have long been considered a promising material due to their extraordinary electrical and optical properties. As a simple, highly efficient fabrication method for SiNWs, metal-assisted chemical etching (MACE) has been intensively studied over recent years. However, effective control by modulation of simple parameters is still a challenging topic and some key questions still remain in the mechanistic processes. In this work, a novel method to manipulate SiNWs with a light-modulated MACE process has been systematically investigated. Conic structures consisting of inclined and clustered SiNWs can be generated and effectively modified by the incident light while new patterns such as ‘bamboo shoot’ arrays can also be formed under certain conditions. More importantly, detailed study has revealed a new top-down ‘diverting etching’ model of the conic structures in this process, different from the previously proposed ‘bending’ model. As a consequence of this mechanism, preferential lateral mass transport of silver particles occurs. Evidence suggests a relationship of this phenomenon to the inhomogeneous distribution of the light-induced electron-hole pairs beneath the etching front. Study on the morphological change and related mechanism will hopefully open new routes to understand and modulate the formation of SiNWs and other nanostructures.

Zhang, Shenli; Wang, Xinwei; Liu, Hong; Shen, Wenzhong

2014-01-01

318

Controllable light-induced conic structures in silicon nanowire arrays by metal-assisted chemical etching.  

PubMed

Silicon nanowires (SiNWs) have long been considered a promising material due to their extraordinary electrical and optical properties. As a simple, highly efficient fabrication method for SiNWs, metal-assisted chemical etching (MACE) has been intensively studied over recent years. However, effective control by modulation of simple parameters is still a challenging topic and some key questions still remain in the mechanistic processes. In this work, a novel method to manipulate SiNWs with a light-modulated MACE process has been systematically investigated. Conic structures consisting of inclined and clustered SiNWs can be generated and effectively modified by the incident light while new patterns such as 'bamboo shoot' arrays can also be formed under certain conditions. More importantly, detailed study has revealed a new top-down 'diverting etching' model of the conic structures in this process, different from the previously proposed 'bending' model. As a consequence of this mechanism, preferential lateral mass transport of silver particles occurs. Evidence suggests a relationship of this phenomenon to the inhomogeneous distribution of the light-induced electron-hole pairs beneath the etching front. Study on the morphological change and related mechanism will hopefully open new routes to understand and modulate the formation of SiNWs and other nanostructures. PMID:24334462

Zhang, Shenli; Wang, Xinwei; Liu, Hong; Shen, Wenzhong

2014-01-17

319

Stable atom-scale junctions on silicon fabricated by kinetically controlled electrochemical deposition and dissolution.  

PubMed

Metallic atom-scale junctions (ASJs) constitute the natural limit of nanowires, in which the limiting region of conduction is only a few atoms wide. They are of interest because they exhibit ballistic conduction and their conductance is extraordinarily sensitive to molecular adsorption. However, identifying robust and regenerable mechanisms for their production is a challenge. Gold ASJs have been fabricated electrochemically on silicon using an iodide-containing medium to control the kinetics. Extremely slow electrodeposition or electrodissolution rates were achieved and used to reliably produce ASJs with limiting conductance <5 G(0). Starting from a photolithographically fabricated, Si(3)N(4)-protected micrometer-scale Au bridge between two contact electrodes, a nanometer-scale gap was prepared by focused ion beam milling. The opposing Au faces of this construct were then used in an open-circuit working electrode configuration to produce Au ASJs, either directly or by first overgrowing a thicker Au nanowire and electrothinning it back to an ASJ. Gold ASJs produced by either approach exhibit good stabilityin some cases being stable over hours at 300 Kand quantized conductance properties. The influence of deposition/dissolution potential and supporting electrolyte on the stability of ASJs are considered. PMID:19206360

Shi, Ping; Bohn, Paul W

2008-08-01

320

Controllable Change of Photoluminescence Spectra of Silicone Rubber Modified by 193 nm ArF Excimer Laser  

NASA Astrophysics Data System (ADS)

Photoluminescence spectra of silicone rubber ([SiO(CH3)2]n) photochemically modified by a 193 nm ArF excimer laser was found to be controllable. Compared with the modification in air, the photoluminescence spectra could be blueshifted by the modification in vacuum or the additional irradiation of ArF excimer laser in vacuum after the modification in air. To redshift, on the other hand, the additional irradiation of a 157 nm F2 laser in air after the modification in air, the modification in oxygen gas, or the postannealing after the modification in oxygen gas was effective. The blue and redshifts of the photoluminescence were essentially due to the acceleration of reduction and oxidation reactions of silicone rubber, respectively, because the photoluminescence derives its origin from oxygen deficiency centers and peroxy centers of the silica structure in the modified silicone rubber. On the basis of the spectra changes, colorful light-guiding sheets made of silicone rubber under illumination of a 375 nm light-emitting diode were successfully fabricated for cellular phone use.

Okoshi, Masayuki; Iyono, Minako; Inoue, Narumi

2009-12-01

321

Three-dimensional analysis of dislocation multiplication in single-crystal silicon under accurate control of cooling history of temperature  

NASA Astrophysics Data System (ADS)

Dislocation multiplication in single-crystal silicon during heating and cooling processes was studied by three-dimensional simulation under accurate control of the temperature history. Three different cooling temperature histories were designed. The results showed that the cooling rate in the high-temperature region has a large effect on the final dislocations and residual stress. The most effective method to reduce dislocations is to use a slow cooling rate in the high-temperature region.

Gao, B.; Kakimoto, K.

2014-06-01

322

Development of a Thermal Rectifier Usable at High Temperature  

NASA Astrophysics Data System (ADS)

By using Al-based metallic alloys characterized by a disordered structure and a narrow pseudogap of a few hundred meV in energy width persisting at the Fermi level, we succeeded in preparing materials possessing a large increase of thermal conductivity with increasing temperature. This unusual increase of thermal conductivity is caused by the electronic structure effect known as the bipolar diffusion effect (BDE) in the context of the two-band model. A thermal rectifier was constructed using materials exhibiting the BDE. By showing the thermal rectification of the bulk sample prepared in this study, we demonstrate that our newly proposed idea of a thermal rectifier using the BDE is applicable for practical use.

Takeuchi, Tsunehiro; Goto, Hiroki; Toyama, Yasuhiro; Itoh, Takashi; Mikami, Masashi

2011-05-01

323

Single mode heat rectifier: controlling energy flow between electronic conductors.  

PubMed

We study heat transfer between conductors, mediated by the excitation of a monomodal harmonic oscillator. Using a simple model, we show that the onset of rectification in the system is directly related to the nonlinearity of the electron gas dispersion relation. When the metals have a strictly linear dispersion relation, a Landauer-type expression for the thermal current holds, symmetric with respect to the temperature difference. Rectification becomes prominent when deviations from linear dispersion exist, and the fermionic model cannot be mapped into a harmonic bosonized representation. The effects described here are relevant for understanding radiative heat transfer and vibrational energy flow in electrically insulating molecular junctions. PMID:18352208

Segal, Dvira

2008-03-14

324

Catastrophic bifurcation in three-phase boost rectifiers  

Microsoft Academic Search

Active PWM voltage rectifiers are commonly used to convert ac power from a three-phase grid to a regulated dc voltage with unity input power factor. The output voltage regulation is normally achieved by an outer voltage feedback loop and a sinusoidal-pulse-width-modulation (SPWM) inner current loop. Due to output voltage disturbances, such as those produced by a capacitive load, the inner

Meng Huang; Siu-Chung Wong; Chi K. Tse; Xinbo Ruan

2011-01-01

325

Control of silicon solidification and the impurities from an Al-Si melt  

NASA Astrophysics Data System (ADS)

The investigation on purification of metallurgical grade silicon by solidification of hypereutectic Al-Si melt under the temperature gradient as an intensified separation way was carried out. Based on the available thermodynamic parameters and experimental data, the thermodynamic behavior and chemical composition of metallic impurities was studied in the solidification process. The principle for the silicon growth in the Al-Si melts was investigated. The results indicated that the refined silicon grains were successfully enriched at the top of the Al-Si alloy. Then the top part refined silicon was collected by aqua regia leaching. Electrorefining of the bottom part (Al-22%Si) was investigated effectively in view of recovering pure Si and Al. Additionally, according to previous investigation, the optimized technical process for SOG-Si production was proposed.

Wang, Panpan; Lu, Huimin; Lai, Yuanshi

2014-03-01

326

New unimolecular rectifiers and through-bond electron tunneling probed by IETs  

NASA Astrophysics Data System (ADS)

Rectification of electrical current by a monolayer of organic molecules, sandwiched between two macroscopic metal electrodes, can be viewed as rectification in parallel by many individual rectifiers, or unimolecular rectification. A new class of such rectifiers, namely [6]-[6] fullerene monoadducts show current rectification in monolayers sandwiched between Au electrodes at room temperature. They form very sturdy monolayers at the air-water interface, and can be easily transferred onto Au solid substrates by the Langmuir-Schaefer technique. The current-voltage measurements show that these molecules rectify current in a mechanism opposite to the one predicted by Aviram-Ratner model. Indirect spectroscopic techniques were used to determine the placement of relevant molecular orbitals, relative to the Fermi level of the Au electrodes. The results strongly indicate that the dominant enhanced electron transport takes place through a relevant unoccupied molecular orbital, which is placed asymmetrically in the gap. Hexadecylquinolinium-gamma-tricyanoquinodimethanide and its tetrafluoro analog exhibit a strongly polarized charge transfer (CT) band in solid Langmuir-Blodgett (LB) monolayers. Both compounds rectify in a LB monolayer sandwiched between Au electrodes at room temperature. The direction of polarization of the CT band can be controlled during monolayer deposition: the CT band transition dipole is either perpendicular or parallel to the substrate, depending on film transfer pressure. This CT band was thought to play an important role in the mechanism of rectification. Inelastic electron tunneling spectroscopy (IETS) can elucidate the electron transport mechanism in metal | organic | metal tunneling junctions. An inelastic tunneling spectrometer was built in our laboratory, and the principles are presented in detail. The spectra acquired at intermediate biases (0--0.5 V) at the temperature of 4.2 K are due to known molecular vibrational modes. For higher bias ranges, broad bands are observed at 4.2 K: these bands are probably due to the onset of resonance between the Fermi level of the metal electrodes and an available molecular orbital. These bands, together with the corresponding current enhancement observed in the current-voltage scans of the same junctions appear to be both manifestations of unimolecular rectification.

Honciuc, Andrei

327

Characterization of a controlled electroless deposition of copper thin film on germanium and silicon surfaces  

Microsoft Academic Search

Nanofilms of copper were deposited on silicon and, for the first time, on polycrystalline germanium substrates by electroless deposition. Germanium or silicon disks were immersed in a 10mM copper sulfate solution containing dilute hydrofluoric acid at room temperature. This simple one-step deposition does not require the use of laborious operations or expensive equipment, that the reaction medium be degassed, or

Louis Scudiero; Ayuba Fasasi; Peter R. Griffiths

2011-01-01

328

Controlling light with high-Q silicon photonic crystal nanocavities: Photon confinement, nonlinearity and coherence  

Microsoft Academic Search

The strong light localization and long photon lifetimes in two-dimensional silicon photonic crystal nanocavities with high quality factor (Q ) and subwavelength modal volume (V) significantly enhance the light-matter interactions, presenting many opportunities to explore new functionalities in silicon nanophotonic integrated circuits for on-chip all-optical information processing, optical computation and optical communications. This thesis will focus on the design, nanofabrication,

Xiaodong Yang

2009-01-01

329

Two-photon indirect optical injection and two-color coherent control in bulk silicon  

NASA Astrophysics Data System (ADS)

Using an empirical pseudopotential description of electron states and an adiabatic bond charge model for phonon states in bulk silicon, we theoretically investigate two-photon indirect optical injection of carriers and spins and two-color coherent control of the motion of the injected carriers and spins. For two-photon indirect carrier and spin injection, we identify the selection rules of band edge transitions, the injection in each conduction band valley, and the injection from each phonon branch at 4 and 300 K. At 4 K, the TA-phonon-assisted transitions dominate the injection at low photon energies and the TO-phonon-assisted transitions at high photon energies. At 300 K, the former dominates at all photon energies of interest. The carrier injection shows anisotropy and linear-circular dichroism with respect to the light propagation direction. For light propagating along the <001> direction, the carrier injection exhibits valley anisotropy, and the injection into the Z conduction band valley is larger than that into the X and Y valleys. For ?- light propagating along the <001> (<111>) direction, the degree of spin polarization gives a maximum value about 20% (6%) at 4 K and -10% (20%) at 300 K, and at both temperature shows abundant structure near the injection edges due to contributions from different phonon branches. For two-color coherent current injection with an incident optical field composed of a fundamental frequency and its second harmonic, the response tensors of the electron (hole) charge and spin currents are calculated at 4 and 300 K. We show the current control for three different polarization scenarios: For cocircularly polarized beams, the direction of the charge current and the polarization direction of the spin current can be controlled by a relative-phase parameter; for the collinearly and cross-linearly polarized beams, the current amplitude can be controlled by that parameter. The spectral dependence of the maximum swarm velocity shows that the direction of the charge current reverses under an increase in photon energy.

Cheng, J. L.; Rioux, J.; Sipe, J. E.

2011-12-01

330

Silicon carbide devices and processes - present status and future pers  

Microsoft Academic Search

Silicon carbide electronic devices are already commercially available in a few application areas such as high voltage rectifiers and emerging RF power amplifiers. Over the past 15 years a very rapid progress of both materials and device quality has been seen and is very encouraging for the near future application market. Prototype devices show amazing improvement each year in all

M. Ostling; H.-S. Lee; M. Domeij; C.-M. Zetterling

2006-01-01

331

An Experimental Verification of a Simplified Five-Level PWM Rectifier with Twelve Switches for Use in High-Frequency Power Supply Systems  

NASA Astrophysics Data System (ADS)

In this paper evaluates a reduced switch count five-level PWM rectifier in a high frequency power supply system. The rectifier is combined a diode clump type topology with a flying capacitor type topology. Moreover, it uses only four switches per leg in spite of being a five-level converter. This paper describes the features of the proposed circuit topology and the corresponding methods of the high input frequency. Finally, the performance of the input current control of the proposed circuit is confirmed using the experimental setup. In addition, the operation of the proposed circuit at a high frequency of 800Hz is confirmed experimentally.

Noge, Yuichi; Itoh, Jun-Ichi

332

Comparison of static, switching and thermal behavior between a 1500 V silicon and silicon carbide bipolar diodes  

Microsoft Academic Search

This paper proposes a comparison between 1500 V Si bipolar diode and 1500 V 4H-SiC bipolar diode operations. The 1500 V blocking voltage is chosen because it corresponds to the highest rating for commercial silicon high voltage rectifiers. Electrical simulations (ISE program) are performed taking into account structure descriptions in agreement with the technology state of the art. The static

F. Nallet; D. Planson; K. Isoird; M. L. Locatelli; J. P. Chante

1999-01-01

333

Power Factor Improvement of Single-Phase Diode Rectifier Circuit By Field-Weakening of Inverter Driven IPM Motor  

NASA Astrophysics Data System (ADS)

This paper proposes a novel inverter drive system to improve input power factor of the single-phase diode rectifier. Conventional rectifier needs a high frequency switching devices and a reactor to improve input power factor. However, the proposed power converter doesn’t need the switching device, the electrolytic capacitor and the reactor. By making many ripples across the dc-bus voltage and then, the input power factor can be improved. The proposed system consists of an only single-phase diode rectifier, small film capacitor, three-phase inverter and motor. The proposed system adopts an interior permanent magnet (IPM) synchronous motor. The IPM motor is well known as a high efficiency motor and can get field weakening. The basic ideas of the inverter control method are based on two following operations. First, the inverter’s controlled synchronous with the dc-bus ripple voltage by field-weakening method.The other is direct active power feeding from the source side to the motor without smoothing the dc-bus voltage. This paper describes that the proposed method can obtain the input power factor 97.3% by experimental tests, and realize the small size and the long life of the system.

Takahashi, Isao; Haga, Hitoshi

334

Rectified cell migration on saw-like micro-elastically patterned hydrogels with asymmetric gradient ratchet teeth.  

PubMed

To control cell motility is one of the essential technologies for biomedical engineering. To establish a methodology of the surface design of elastic substrate to control the long-range cell movements, here we report a sophisticated cell culture hydrogel with a micro-elastically patterned surface that allows long-range durotaxis. This hydrogel has a saw-like pattern with asymmetric gradient ratchet teeth, and rectifies random cell movements. Durotaxis only occurs at boundaries in which the gradient strength of elasticity is above a threshold level. Consequently, in gels with unit teeth patterns, durotaxis should only occur at the sides of the teeth in which the gradient strength of elasticity is above this threshold level. Therefore, such gels are expected to support the long-range biased movement of cells via a mechanism similar to the Feynman-Smoluchowski ratchet, i.e., rectified cell migration. The present study verifies this working hypothesis by using photolithographic microelasticity patterning of photocurable gelatin gels. Gels in which each teeth unit was 100-120 µm wide with a ratio of ascending:descending elasticity gradient of 1:2 and a peak elasticity of ca. 100 kPa supported the efficient rectified migration of 3T3 fibroblast cells. In addition, long-range cell migration was most efficient when soft lanes were introduced perpendicular to the saw-like patterns. This study demonstrates that asymmetric elasticity gradient patterning of cell culture gels is a versatile means of manipulating cell motility. PMID:24147112

Kidoaki, Satoru; Sakashita, Hiroyuki

2013-01-01

335

Rectified Cell Migration on Saw-Like Micro-Elastically Patterned Hydrogels with Asymmetric Gradient Ratchet Teeth  

PubMed Central

To control cell motility is one of the essential technologies for biomedical engineering. To establish a methodology of the surface design of elastic substrate to control the long-range cell movements, here we report a sophisticated cell culture hydrogel with a micro-elastically patterned surface that allows long-range durotaxis. This hydrogel has a saw-like pattern with asymmetric gradient ratchet teeth, and rectifies random cell movements. Durotaxis only occurs at boundaries in which the gradient strength of elasticity is above a threshold level. Consequently, in gels with unit teeth patterns, durotaxis should only occur at the sides of the teeth in which the gradient strength of elasticity is above this threshold level. Therefore, such gels are expected to support the long-range biased movement of cells via a mechanism similar to the Feynman-Smoluchowski ratchet, i.e., rectified cell migration. The present study verifies this working hypothesis by using photolithographic microelasticity patterning of photocurable gelatin gels. Gels in which each teeth unit was 100–120 µm wide with a ratio of ascending:descending elasticity gradient of 1:2 and a peak elasticity of ca. 100 kPa supported the efficient rectified migration of 3T3 fibroblast cells. In addition, long-range cell migration was most efficient when soft lanes were introduced perpendicular to the saw-like patterns. This study demonstrates that asymmetric elasticity gradient patterning of cell culture gels is a versatile means of manipulating cell motility.

Kidoaki, Satoru; Sakashita, Hiroyuki

2013-01-01

336

An Integrated Amorphous Silicon Gate Driver Circuit Using Voltage-Controlled Capacitance Modeling for High Definition Television  

NASA Astrophysics Data System (ADS)

We have developed the integrated amorphous silicon gate driver circuit using the model extraction technique of the inverted staggered and nonsymmetric amorphous silicon (a-Si) thin film transistor. The relation between capacitance characteristics of hydrogenated a-Si (a-Si:H) integrated transistors and the output signal of the gate driver circuit is analyzed using UTMOST IV ver. 1.6.4.R and SMARTSPICE ver. 3.19.15.C. The accuracy of the simulated gate output signal using voltage-controlled capacitance modeling is verified with measured data. The a-Si gate driver circuit using the proposed (TFT) model increased the accuracy of rising (95.3%) and falling (92%) time, compared to the conventional model. The suggested model extraction technique can be used for bottom gate and asymmetric TFT structures.

Han, Sang-Kug; Choi, Hoon; Moon, Kyo-Ho; Choi, Young-Seok; Jeong, Kyung-Deuk; Park, Kwang-Mook; Choi, Sie-Young

2012-04-01

337

Improving the stability of nanostructured silicon thin film lithium-ion battery anodes through their controlled oxidation.  

PubMed

Silicon and partially oxidized silicon thin films with nanocolumnar morphology were synthesized by evaporative deposition at a glancing angle, and their performance as lithium-ion battery anodes was evaluated. The incorporated oxygen concentration was controlled by varying the partial pressure of water during the deposition and monitored by quartz crystal microbalance, X-ray photoelectron spectroscopy. In addition to bulk oxygen content, surface oxidation and annealing at low temperature affected the cycling stability and lithium-storage capacity of the films. By simultaneously optimizing all three, films of ~2200 mAh/g capacity were synthesized. Coin cells made with the optimized films were reversibly cycled for ~120 cycles with virtually no capacity fade. After 300 cycles, 80% of the initial reversible capacity was retained. PMID:22372404

Abel, Paul R; Lin, Yong-Mao; Celio, Hugo; Heller, Adam; Mullins, C Buddie

2012-03-27

338

Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures  

NASA Astrophysics Data System (ADS)

In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent.

Hilali, Mohamed M.; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S. V.

2012-10-01

339

Properties of Two Outward-Rectifying Channels in Root Xylem Parenchyma Cells Suggest a Role in K+ Homeostasis and Long-Distance Signaling  

Microsoft Academic Search

Xylem parenchyma cells (XPCs) control the composition of the transpiration stream in plants and are thought to play a role in long-distance signaling as well. We addressed the regulation, selec- tivity, and dependence on the apoplastic ion concentrations of two types of outward rectifiers in the plasma membrane of XPCs, to asses the physiological role of these conductances. In whole-cell

Lars H. Wegner; Albertus H. De Boer

340

Properties of the K + inward rectifier in the plasma membrane of xylem parenchyma cells from barley roots: Effects of TEA + , Ca 2+ , Ba 2+ and La 3+  

Microsoft Academic Search

Xylem parenchyma cells are situated around the (apoplastic) xylem vessels and are involved in the control of the composition of the xylem sap by exporting and resorbing solutes. We investigated properties of the K+ inward rectifier in the plasma membrane of these cells by performing patch clamp experiments on protoplasts in the whole-cell configuration. Inward currents were sensitive to the

L. H. Wegner; A. H. De Boer; K. Raschke

1994-01-01

341

In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire  

Microsoft Academic Search

Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm\\/min)

Gong Yibin; Dai Pengfei; Gao Anran; Li Tie; Zhou Ping; Wang Yuelin

2011-01-01

342

Optically-controlled extinction ratio and Q-factor tunable silicon microring resonators based on optical forces  

PubMed Central

Tunability is a desirable property of microring resonators to facilitate superior performance. Using light to control light, we present an alternative simple approach to tuning the extinction ratio (ER) and Q-factor of silicon microring resonators based on optical forces. We design an opto-mechanical tunable silicon microring resonator consisting of an add-drop microring resonator and a control-light-carrying waveguide (“controlling” waveguide). One of the two bus waveguides of the microring resonator is a deformable nanostring put in parallel with the “controlling” waveguide. The tuning mechanism relies on the optical force induced deflection of suspended nanostring, leading to the change of coupling coefficient of microring and resultant tuning of ER and Q-factor. Two possible geometries, i.e. double-clamped nanostring and cantilever nanostring, are studied in detail for comparison. The obtained results imply a favorable structure with the microring positioned at the end of the cantilever nanostring. It features a wide tuning range of ER from 5.6 to 39.9?dB and Q-factor from 309 to 639 as changing the control power from 0 to 1.4?mW.

Long, Yun; Wang, Jian

2014-01-01

343

Methods for controlling the pore properties of ultra-thin nanocrystalline silicon membranes  

NASA Astrophysics Data System (ADS)

Porous nanocrystalline silicon (pnc-Si) membranes are a new class of solid-state ultra-thin membranes with promising applications ranging from biological separations to use as a platform for electron imaging and spectroscopy. Because the thickness of the membrane is only 15-30 nm, on the order of that of the molecules to be separated, mass transport through the membrane is greatly enhanced. For applications involving molecular separations, it is crucial that the membrane is highly permeable to some species while being nearly impermeable to others. An important approach to adjusting the permeability of a membrane is by changing the size and density of the pores. With pnc-Si, a rapid thermal treatment is used to induce nanopore formation in a thin film of nanocrystalline silicon, which is then released over a silicon scaffold using an anisotropic etchant. In this study, we examine the influence of thin film deposition and thermal treatment parameters on pore size and density.

Fang, D. Z.; Striemer, C. C.; Gaborski, T. R.; McGrath, J. L.; Fauchet, P. M.

2010-11-01

344

Ultrafast optical control using the Kerr nonlinearity in hydrogenated amorphous silicon microcylindrical resonators  

PubMed Central

Microresonators are ideal systems for probing nonlinear phenomena at low thresholds due to their small mode volumes and high quality (Q) factors. As such, they have found use both for fundamental studies of light-matter interactions as well as for applications in areas ranging from telecommunications to medicine. In particular, semiconductor-based resonators with large Kerr nonlinearities have great potential for high speed, low power all-optical processing. Here we present experiments to characterize the size of the Kerr induced resonance wavelength shifting in a hydrogenated amorphous silicon resonator and demonstrate its potential for ultrafast all-optical modulation and switching. Large wavelength shifts are observed for low pump powers due to the high nonlinearity of the amorphous silicon material and the strong mode confinement in the microcylindrical resonator. The threshold energy for switching is less than a picojoule, representing a significant step towards advantageous low power silicon-based photonic technologies.

Vukovic, N.; Healy, N.; Suhailin, F. H.; Mehta, P.; Day, T. D.; Badding, J. V.; Peacock, A. C.

2013-01-01

345

Current-controlled synchronous rectification  

Microsoft Academic Search

This paper presents several strategies for implementing a current-controlled synchronous rectifier. One approach utilizes a current-sensing transformer in series with the rectifying MOSFET to derive the required gating signals. The second method uses the mirror current of a current-sensing MOSFET. Experimental results obtained with current-driven rectifiers in a center-tapped, full-wave configuration are presented

Brian Acker; Charles R. Sullivan; Seth R. Sanders

1994-01-01

346

Large scale low cost fabrication of diameter controllable silicon nanowire arrays.  

PubMed

We report on a novel solution etching method to fabricate vertically aligned aperiodic silicon nanowire (SiNW) arrays. We begin with a simple dewetting process to fabricate a monolayer of well-spaced metal particles in situ on a silicon wafer. The particles function as a sacrificial template to pattern a Ti/Au catalyst film into a metal mesh and the size of particles directly determines the diameter of SiNW. A conventional metal-assisted chemical etching process is then carried out with the obtained metal mesh as a catalyst to realize a vertically aligned SiNW array at a large scale and low cost. PMID:24896291

Sun, Leimeng; Fan, Yu; Wang, Xinghui; Agung Susantyoko, Rahmat; Zhang, Qing

2014-06-27

347

Dopant profile control of epitaxial emitter for silicon solar cells by low temperature epitaxy  

NASA Astrophysics Data System (ADS)

We report an alternative approach to grow phosphorus-doped epitaxial silicon emitter by rapid thermal chemical vapor deposition at low temperature (T >= 700 °C). A power conversion efficiency (PCE) of (6.6 +/- 0.3)% and a pseudo PCE of (10.2 +/- 0.2)% has been achieved for the solar cell with epi-emitter grown at 700 °C, in the absence of surface texturization, antireflective coating, and back surface field enhancement, without considering front contact shading. Secondary ion mass spectroscopy revealed that lower temperature silicon epitaxy yields a more abrupt p-n junction, suggesting potential applications for radial p-n junction wire array solar cells.

Lai, Donny; Tan, Yew Heng; Gunawan, Oki; He, Lining; Seng Tan, Chuan

2011-07-01

348

Rectifying and perfect spin filtering behavior realized by tailoring graphene nanoribbons  

NASA Astrophysics Data System (ADS)

An armchair graphene nanoribbon based electronic device with spin filtering and rectifying behavior is designed by means of molecular tailoring, and the electronic transport properties are calculated by using nonequilibrium Green's functions in combination with the density functional theory. The results show that the rectifying behavior can be observed in the junctions, and the rectifying ratio can be effectively tuned by edge doping. Furthermore, perfect spin polarization behavior can also be observed in the junctions.

He, Jun; Chen, Ke-Qiu

2012-12-01

349

State-space average modelling of 6- and 12-pulse diode rectifiers  

Microsoft Academic Search

This paper derives averaged-value models for 6- and 12- pulse transformer-diode rectifier units and validates their utilities by comparison of the resultant transient and steady state behaviors with those obtained from extensive simulations of detailed 6- and 12-pulse diode rectifier models. It is shown that the averaged-value models capture the key features of the dynamic characteristics of the rectifiers, while

Liqiu Han; Jiabin Wang; David Howe

2007-01-01

350

High-voltage rectifiers for new systems of electrosupply of railways  

Microsoft Academic Search

In the given work were made the comparison of new three-phase high-voltage rectifiers with the classical scheme of 12-pulse rectifier. It is shown, that in the new scheme of three-phase threezone (n-zone in generally) rectifier the number of thyristors essentially decreases and reverse voltage on gates decrease. The figures of factors of harmonics of output voltage, an input current, and

Alexander G. Volkov; Gennadiy S. Zinoviev; Alexey P. Kosarev

2010-01-01

351

Circuit topologies for single-phase voltage-doubler boost rectifiers  

Microsoft Academic Search

A new family of single-phase voltage-doubler PWM (pulse width modulated) boost rectifiers is presented. By examining the switching states of several standard single-phase boost rectifier circuits, three characteristic PWM voltage switching patterns are identified: unipolar PWM; bipolar PWM; and phase-adjusted unipolar PWM. From this analysis, an equivalent family of voltage-doubler rectifiers is derived. When high output voltages are required, voltage-doubler

John C. Salmon

1993-01-01

352

Reusing and rerating older rectifiers with new DC\\/DC choppers  

Microsoft Academic Search

The development of high-power DC\\/DC converters (more commonly known as chopper rectifiers) allows customers the option to keep older rectifier transformers and refurbished systems if reconfiguring or installing new cell line loads. Normally, new cell line impedances would require the replacement of transformer\\/rectifier equipment. This paper describes how one can change the output operating range of existing equipment as well

John Beak; Paul Buddingh; Vince Scaini

2001-01-01

353

Bidirectional rectifier-inverter multilevel topology without DC-link passive components  

Microsoft Academic Search

A capacitor-less rectifier-inverter topology based on a fundamental frequency switched rectifier and a three-level flying capacitor is presented in this paper. The DC-link is free of any passive elements (capacitors, chokes or braking resistors). The removal of the large and bulky DC-link electrolytic capacitor, typically employed in rectifier-inverter topologies results in the elimination of a fault prone element and can

Georgios S. Konstantinou; V. G. Agelidis

2010-01-01

354

Analysis of a high-voltage merged p-i-n\\/Schottky (MPS) rectifier  

Microsoft Academic Search

A new operating mode for the merged p-i-n\\/Schottky (MPS) rectifier structure is analyzed. It is shown that these devices exhibit superior forward-drop and turn-off-speed characteristics. As an example, for the same forward drop, the 400-V MPS rectifier is an order of magnitude faster in switching speed when compared to a p-i-n rectifier. In addition, for equal switching speed, the MPS

B. JAYANT BALIGA

1987-01-01

355

Bias-controlled friction of InAs nanowires on a silicon nitride layer studied by atomic force microscopy  

NASA Astrophysics Data System (ADS)

By studying how nanowires lying on a surface bend when pushed by an atomic force microscopy tip we are able to measure the friction between them and the substrate. Here, we show how the friction between InAs nanowires and an insulating silicon nitride layer varies when a dc voltage is applied to the tip during manipulation. The bias charges the capacitor formed by the wire and the grounded silicon back contact. Electrostatic forces increase the contact pressure and allow us to tune the friction between the wire and the silicon nitride surface. Using nanowires of about 40-70 nm diameter and a few microns in length we have applied biases in the range +12 to -12V . A monotonic increase of the sliding friction with voltage was observed. This increase in friction with the normal force implies that the mesoscopic nanowire-surface system behaves like a macroscopic contact, despite the nanometer size of the contact in the direction of motion. The demonstrated bias-controlled friction has potential applications in MEMS/NEMS devices.

Conache, G.; Ribayrol, A.; Fröberg, L. E.; Borgström, M. T.; Samuelson, L.; Montelius, L.; Pettersson, H.; Gray, S. M.

2010-07-01

356

Rectifying performance of D-?-A molecules based on cyanovinyl aniline derivatives  

NASA Astrophysics Data System (ADS)

Using the first-principles method, we investigate rectifying performances of D-?-A molecules based on cyanovinyl aniline derivatives. The calculated results show that different functional groups can change the location of molecular orbitals and thus change the rectifying properties of molecules. Interestingly, we find that although the electronic structure for our studied systems is in agreement with that proposed originally by Aviram and Ratner [Chem. Phys. Lett. 29, 277 (1974)], the rectifying direction is opposite from it due to the asymmetric shift of molecular levels under biases of different polarities. Only for model (M4), it shows a forward rectifying performance under larger bias.

Pan, J. B.; Zhang, Z. H.; Deng, X. Q.; Qiu, M.; Guo, C.

2010-11-01

357

Amorphous Silicon(aSi:H) Thin Film Based Omnidirectional Control Solar Powered Vehicle  

Microsoft Academic Search

Through the paper, our goal is to drive a car with the help of thin film based solar cell. Mechanical and Electrical parts are assembled thereby. The main objective of this project is to collect maximum solar energy from the solar spectrum and use that solar energy to drive the car. Amorphous silicon based thin film solar panel has been

Abdullah Moinuddin; Jony C. Sarker; Akhter Zia

2012-01-01

358

Precise Depth Control of Silicon Etching Using Chlorine Atomic Layer Etching  

Microsoft Academic Search

In this study, the atomic layer etching (ALE) of Si was carried out using Cl2 adsorption followed by Ar+ ion beam irradiation with a low energy Ar+ ion beam generated by an inductively coupled plasma ion gun. A saturated silicon etch rate due to chlorine ALE could be obtained when the Ar+ ion acceleration voltage of the ion gun was

Sang-Duk Park; Kyung-Suk Min; Byoung-Young Yoon; Do-Haing Lee; Geun-Young Yeom

2005-01-01

359

Rectified Brownian motion and kinesin motion along microtubules  

NASA Astrophysics Data System (ADS)

The mechanism of rectified Brownian movement is used to analyze measured data for kinesin motion along microtubules. A key component of the mechanism is the diffusive movement of the microtubule binding heads of kinesin during the adenosine triphosphate (ATP) cycle. The first-passage time distribution for this step is analyzed in detail and is shown to be responsible for observed load-velocity profiles. The ATPase activity of the kinesin heads is that of a nucleotide switch and not that of a direct chemomechanical energy converter. Experimental data acquisition, rate constants, and alternative explanations are discussed. The mechanism described in this paper is fundamental to the nanobiology of intracellular processes.

Fox, Ronald F.; Choi, Mee Hyang

2001-05-01

360

Nanoscale lateral switchable rectifiers fabricated by local anodic oxidation  

NASA Astrophysics Data System (ADS)

Scanning probe lithography as a mean to pattern, implement, and discover new devices in different materials systems provides an elevated degree of flexibility, permitting one to tailor device geometries and structures at will, in particular by virtue of modification of the local chemistry. Here we define metal-insulator-metal junctions exhibiting a switchable rectifier behavior by patterning titanium channels through local anodic oxidation techniques. The nanoscale TiO2 junctions thus formed exhibit IV characteristics with non-volatile switchable rectification and memristive behavior due to ionic motion through the metal-semiconductor interfaces.

Siles, Pablo F.; Archanjo, B. S.; Baptista, D. L.; Pimentel, V. L.; Joshua, J.; Neves, B. R. A.; Medeiros-Ribeiro, G.

2011-07-01

361

Use of power semiconductors to control locomotive traction motors in the French national railways  

Microsoft Academic Search

The application of semiconductor rectifiers and thyristors in the control of power to ac, dc, and diesel powered locomotives in the French National Railways is presented. A total of 260 locomotives have been equipped with 60 000 semiconductor rectifiers since 1959. The failure rate of these rectifiers has been 0.12 percent or 1.35 percent for every million kilometers traveled. Four

F. Nouvion

1967-01-01

362

Silicon Wafer Lapping  

NSDL National Science Digital Library

This Quicktime animation shows how the machining process of "lapping" removes controlled amounts of silicon from a wafer in order to ensure flatness of the silicon wafer. This process removes particles and improves the quality of the wafer after they are cut. This animation is the fifth in a series of how silicon wafers are created.The previous animation showing silicon ingot edge profiling can be seen here.The next animation in this sequence about silicon wafer polishing can be seen here.

2010-02-08

363

Analysis and design of a modular three-phase AC to DC converter using CUK rectifier module with nearly unity power factor and fast dynamic response  

Microsoft Academic Search

The analysis and design of a modular three-phase ac to dc converter using single-phase CUK rectifier modules is discussed based on power balance control technique. The control strategy consists of single output voltage loop control and three-inductor current calculator. The main objective of the proposed system is to reduce the number of stages and improve dynamic response of dc bus

U. Kamnarn; V. Chunkag

2008-01-01

364

A novel method for gas flow and impurity control in directional solidification of multi-crystalline silicon  

NASA Astrophysics Data System (ADS)

In this paper the potential of a specially designed argon gas injector for controlling the gas flow and transport of impurities in directional solidification of multi-crystalline silicon is evaluated. The gas injector which consists of a valve allows one to control the flow direction independently in the vertical and horizontal directions. Based on a gas flow model derived from a semi-industrial crystallization furnace the impact of different gas injection combinations on the gas flow pattern and impurity transport is studied. Special focus is given to the SiO evacuation from the melt-free surface, the CO formation at graphite surfaces and the CO evacuation from the furnace interior. It is found that for gas flow pattern formed through horizontal rather than vertical gas injection, SiO and CO are evacuated most effectively from the furnace interior and the formation of CO is inhibited. Such a type of gas injector presents a versatile tool for controlling the flow and impurity transport in the gas phase and possibly improving the material properties of crystalline silicon.

Bellmann, M. P.; Lindholm, D.; M'Hamdi, M.

2014-08-01

365

Controlled doping of silicon nanocrystals investigated by solution-processed field effect transistors.  

PubMed

The doping of semiconductor nanocrystals (NCs), which is vital for the optimization of NC-based devices, remains a significant challenge. While gas-phase plasma approaches have been successful in incorporating dopant atoms into NCs, little is known about their electronic activation. Here, we investigate the electronic properties of doped silicon NC thin films cast from solution by field effect transistor analysis. We find that, analogous to bulk silicon, boron and phosphorus electronically dope Si NC thin films; however, the dopant activation efficiency is only ?10(-2)-10(-4). We also show that surface doping of Si NCs is an effective way to alter the carrier concentrations in Si NC films. PMID:24832958

Gresback, Ryan; Kramer, Nicolaas J; Ding, Yi; Chen, Ting; Kortshagen, Uwe R; Nozaki, Tomohiro

2014-06-24

366

Process for fabricating device structures for real-time process control of silicon doping  

DOEpatents

Silicon device structures designed to allow measurement of important doping process parameters immediately after the doping step has occurred. The test structures are processed through contact formation using standard semiconductor fabrication techniques. After the contacts have been formed, the structures are covered by an oxide layer and an aluminum layer. The aluminum layer is then patterned to expose the contact pads and selected regions of the silicon to be doped. Doping is then performed, and the whole structure is annealed with a pulsed excimer laser. But laser annealing, unlike standard annealing techniques, does not effect the aluminum contacts because the laser light is reflected by the aluminum. Once the annealing process is complete, the structures can be probed, using standard techniques, to ascertain data about the doping step. Analysis of the data can be used to determine probable yield reductions due to improper execution of the doping step and thus provide real-time feedback during integrated circuit fabrication.

Weiner, Kurt H. (San Jose, CA)

2001-01-01

367

Investigation of the mechanisms controlling the stability of a porous silicon electroluminescent device  

Microsoft Academic Search

It has been shown that an all solid-state porous silicon electroluminescent device with an efficiency greater than 0.1% can be fabricated (A. Loni et al., Electron. Lett., 31 (15) (1995) 1288–1289). However, one important factor limiting the practical application of this device is the stability of the electroluminescence. With the support of optical, electrical and chemographical investigations, we report on

A. J. Simons; T. I. Cox; A. Loni; L. T. Canham; R. Blacker

1997-01-01

368

Effects of Dot Size and its Distribution on Electron Number Control in Metal-Oxide-Semiconductor-Field-Effect-Transistor Memories Based on Silicon Nanocrystal Floating Dots  

Microsoft Academic Search

Effects of dot size and dot size distribution on electron number control in silicon floating dot memories at room temperature are investigated by numerical calculation. When the dot size is sufficiently small and the size distribution is negligible, the number of electrons in the dot is precisely controlled by the Coulomb blockade and the electron number shows a staircase feature

Haining Wang; Nobuyoshi Takahashi; Hideaki Majima; Takashi Inukai; Masumi Saitoh; Toshiro Hiramoto

2001-01-01

369

Controlling the formation of luminescent Si nanocrystals in plasma-enhanced chemical vapor deposited silicon-rich silicon oxide through ion irradiation  

Microsoft Academic Search

The effect of ion irradiation on the formation of luminescent Si nanocrystals from silicon-rich silicon oxide (SRSO) films deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition (PECVD) whose Si content ranged from 33 to 50 at. % is investigated. As-deposited SRSO films contained a high density of irregular-shaped Si nanocrystals. Irradiating these films with 380 keV Si at room

T. G. Kim; C. N. Whang; Yohan Sun; Se-Young Seo; Jung H. Shin; J. H. Song

2002-01-01

370

A rotating magnetic field approach to a low distortion poly-phase power rectifier  

Microsoft Academic Search

The rotating magnetic field generated by a balanced three phase AC system of currents is employed to excite a polyphase secondary which is subsequently rectified. The use of the rotating magnetic field structure has distinct advantages for isolating the input AC system from the rectified DC system and, therefore, substantially reducing the current distortion present to a much lower level

Kenneth A. Buckle; J. W. Luce

1996-01-01

371

Determination of the subunit stoichiometry of an inwardly rectifying potassium channel  

Microsoft Academic Search

Inwardly rectifying K+ channels are distantly related to their voltage-gated counterparts and possess a structural motif of only two putative transmembrane segments in each subunit. They are formed by the assembly of an unknown number of subunits. We have examined the subunit stolchiometry of a strongly rectifying K+ channel, IRK1, by linking together the coding sequence of three or four

Jian Yang; Yuh Nung Jan; Lily Yeh Jan

1995-01-01

372

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

NASA Astrophysics Data System (ADS)

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.

Singh, B.; Rajesh, M.

2013-09-01

373

A passive UHF RFID tag with a dynamic-Vth-cancellation rectifier  

NASA Astrophysics Data System (ADS)

This paper presents a passive UHF RFID tag with a dynamic-Vth-cancellation (DVC) rectifier. In the rectifier, the threshold voltages of MOSFETs are cancelled by applying gate bias voltages, which are dynamically changed according to the states of the MOSFETs. The DVC rectifier enables both low ON-resistance and small reverse leakage of the MOSFETs, resulting in high power conversion efficiency (PCE). An area-efficient demodulator with a novel average detector is also designed, which takes advantage of the rectifier's first stage as the envelope detector. The whole tag chip is implemented in a 0.18 ?m CMOS process with a die size of 880 × 950 ?m2. Measurement results show that the rectifier achieves a maximum PCE of 53.7% with 80 k? resistor load.

Jinpeng, Shen; Bo, Wang; Shan, Liu; Xin'an, Wang; Zhengkun, Ruan; Shoucheng, Li

2013-09-01

374

Chemical control over the formation and reactivity of ultra-thin films and amino-terminated layers on silicon  

NASA Astrophysics Data System (ADS)

The physical-chemical properties of several interfacial systems of technological relevance are investigated, having as a common goal the elucidation of strategies towards their atomic- and molecular-level control. Such systems can be classified in three groups: (i) ultra-thin films deposited using metalorganic precursors, (ii) metalorganic monolayers on silicon, and (iii) amine-functionalized silicon surfaces. Experimental, theoretical and chemometric methods are conveniently combined to gain a solid understanding of these systems. The ultra-thin films under investigation are titanium carbonitride (TiNC) and hafnium oxide (HfO2). Since these films may serve as substrates for deposition of other materials in circuit components, their surface chemistry needs to be understood and controlled in order to facilitate further deposition steps. The surface of a TiCN film is transformed to titanium nitride (TiN) through nitridation with ammonia; this compositional change can be reversed by the partial decomposition of ethylene molecules on the surface. The surface reactivity is observed to depend on the film composition, and therefore the method described above serves to reversibly tune the reactivity of Ti-based films. As for HfO2 films, it is found that the deposition temperature affects the degree of crystallinity of the films, which in turn affects their surface chemistry. Thus, together with a control of the composition, it is found that the reactivity of a film can be controlled precisely by controlling the crystallinity. The investigation of metalorganic monolayers on silicon surfaces was motivated by the need for understanding the first steps of metalorganic-based deposition of films, which is usually characterized by a heavy presence of contaminants that degrade the film properties. Through a combination of vibrational (infrared) spectroscopy and theoretical methods, a feasible pathway for the adsorption and decomposition of Ti[N(CH3)2]4 is found. This pathway starts with the ligand-mediated attachment of the precursor (through a N atom), followed by dissociation of a metal-ligand bond. In addition, the C-H bond is broken, possibly forming Si-C bonds and causing carbon incorporation. This model is found to be rather robust and to adequately describe other types of metalorganic precursors. It allows establishing a generalized model able to explain the success or failure of a metalorganic precursor chemistry for film deposition. Finally, amine-functionalized silicon surfaces are considered as prototypical systems where the spatial distribution of adsorbates and the control over the reactivity of surface sites can be investigated. The spatial distribution of molecules is investigated at the atomic level by considering the saturation of a Si(100) surface with NH3. It is found that the distribution of (Si)NH2 species can be controlled thermally and, more importantly, that during thermal decomposition N inserts into the substrate in manners that minimize the arising strain. When the surface is covered with NH 3 or with organic amines, its chemical behavior is determined by the basicity of the molecule functionalizing the surface. The precise tuning of the reactivity (basicity) of surface sites opens the doors for highly controllable, selective reactions. Although these results are obtained from rather fundamental grounds, their interpretation is often translated into manners in which technological applications can be improved. Further directions worth exploring emanated from this work are outlined and discussed. Ultimately, this work intends to highlight the current importance of surface physical chemistry in the continuous development of modern society through the improvement of its technology.

Rodriguez-Reyes, Juan Carlos F.

375

On the Switched-Reluctance Motor Drive With Three-Phase Single-Switch Switch-Mode Rectifier Front-End  

Microsoft Academic Search

This paper presents a switched reluctance motor (SRM) drive powered by a three-phase single-switch (3P1SW) switch-mode rectifier (SMR). The digital controls of both power stages are realized in a common DSP. In the front-end SMR, a robust current harmonic cancellation scheme and a robust voltage control scheme are developed. The undesired line current and output voltage ripples are regarded as

Jui-Yuan Chai; Yuan-Chih Chang; Chang-Ming Liaw

2010-01-01

376

Analysis and Design of a Modular Three-Phase AC-to-DC Converter Using CUK Rectifier Module With Nearly Unity Power Factor and Fast Dynamic Response  

Microsoft Academic Search

In this paper, the analysis and design of a modular three-phase AC-to-DC converter using single-phase isolated Cuk rectifier modules is discussed based on power balance control technique. This paper analyzes the operation of a modular converter as continuous-conduction-mode power factor correction (CCM-PFC). Design equations, as well as an average small-signal model of the proposed system to aid the control loop

Uthen Kamnarn; Viboon Chunkag

2009-01-01

377

Silicon nanowires with controlled sidewall profile and roughness fabricated by thin-film dewetting and metal-assisted chemical etching  

NASA Astrophysics Data System (ADS)

This paper presents a non-lithographic approach to generate wafer-scale single crystal silicon nanowires (SiNWs) with controlled sidewall profile and surface morphology. The approach begins with silver (Ag) thin-film thermal dewetting, gold (Au) deposition and lift-off to generate a large-scale Au mesh on Si substrates. This is followed by metal-assisted chemical etching (MacEtch), where the Au mesh serves as a catalyst to produce arrays of smooth Si nanowires with tunable taper up to 13°. The mean diameter of the thus fabricated SiNWs can be controlled to range from 62 to 300 nm with standard deviations as small as 13.6 nm, and the areal coverage of the wire arrays can be up to 46%. Control of the mean wire diameter is achieved by controlling the pore diameter of the metallic mesh which is, in turn, controlled by adjusting the initial thin-film thickness and deposition rate. To control the wire surface morphology, a post-fabrication roughening step is added to the approach. This step uses Au nanoparticles and slow-rate MacEtch to produce rms surface roughness up to 3.6 nm.

Azeredo, B. P.; Sadhu, J.; Ma, J.; Jacobs, K.; Kim, J.; Lee, K.; Eraker, J. H.; Li, X.; Sinha, S.; Fang, N.; Ferreira, P.; Hsu, K.

2013-06-01

378

Control of interface fracture in silicon nitride ceramics: influence of different rare earth elements  

SciTech Connect

The toughness of self-reinforced silicon nitride ceramics is improved by enhancing crack deflection and crack bridging mechanisms. Both mechanisms rely on the interfacial debonding process between the elongated {Beta}-Si{sub 3}N{sub 4} grains and the intergranular amorphous phases. The various sintering additives used for densification may influence the interfacial debonding process by modifying the thermal and mechanical properties of the intergranular glasses, which will result in different residual thermal expansion mismatch stresses; and the atomic bonding structure across the {Beta}-Si{sub 3}N{sub 4} glass interface. Earlier studies indicated that self-reinforced silicon nitrides sintered with different rare earth additives and/or different Y{sub 2}O{sub 3}:AI{sub 2}0{sub 3} ratios could exhibit different fracture behavior that varied from intergranular to transgranular fracture. No studies have been conducted to investigate the influence of sintering additives on the interfacial fracture in silicon nitride ceramics. Because of the complexity of the material system and the extremely small scale, it is difficult to conduct quantitative analyses on the chemistry and stress states of the intergranular glass phases and to relate the results to the bulk properties. The influence of different sintering additives on the interfacial fracture behavior is assessed using model systems in which {Beta}-Si{sub 3}N{sub 4}whiskers are embedded in SIAIRE (RE: rare-earth) oxynitride glasses. By systematically varying the glass composition, the role of various rare-earth additives on interfacial fracture has been examined. Specifically, four different additives were investigated: Al{sub 2}0{sub 3}, Y{sub 2}0{sub 3}, La{sub 2}O{sub 3}, and Yb{sub 2}O{sub 3}. In addition, applying the results from the model systems, the R- curve behavior of self-reinforced silicon nitride ceramics sintered with different Y{sub 2}0{sub 3}:AI{sub 2}0{sub 3} ratios was characterized.

Sun, E.Y.; Becher, P.F.; Waters, S.B.; Hsueh, Chun-Hway; Plucknett, K.P. [Oak Ridge National Lab., TN (United States); Hoffmann, M.J. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Keramik im Maschinenbau

1996-10-01

379

Rectifying behavior of graphene/h-boron-nitride heterostructure  

NASA Astrophysics Data System (ADS)

The rectifying behavior of a simple graphene/boron-nitride heterostructure between two semi-infinite electrodes is investigated by using the non-equilibrium Green's function method. Also a simple analytical model is used to explain the current-voltage characteristic of a typical heterostructure. The Hamiltonian of nanostructure is written in the tight-binding model and the interaction of heterostructure with left and right leads is studied in the wide-band approximation. The current-voltage curve of graphene/boron-nitride shows an asymmetric behavior and negative-differential-resistance in the positive bias voltage which is explained in the simple model. By increasing the ribbon width, current increases and the peak-to-valley current ratio decreases. All the G/h-BN shows a large rectification ratio in a certain voltage region. The rectification behavior in the hetero-junction is related to the barrier potential at the interface of two structures.

Modarresi, M.; Roknabadi, M. R.; Shahtahmassebi, N.

2013-04-01

380

Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures.  

PubMed

In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent. PMID:22997169

Hilali, Mohamed M; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S V

2012-10-12

381

Control of Electrostatic Coupling Observed for Silicon Double Quantum Dot Structures  

NASA Astrophysics Data System (ADS)

We study the electrostatic coupling in the silicon double quantum dot (DQD) structure as a key building block for a charge-based quantum computer and a quantum cellular automaton (QCA). We realize the three interdot coupling regimes of the DQD structure only by optimizing the DQD design and the thermal oxidation condition. We then demonstrate that the electrostatic coupling between DQDs can be modulated by tuning the negative voltage of the side gate electrode. Note that the interdot coupling was largely modulated with a small decrease in the gate voltage from 0 to -100 mV because our structure initially has the DQD geometry. Furthermore, the device fabrication is compatible with the conventional silicon complementary metal-oxide-semiconductor (CMOS) process. This structure is suitable for the future integration of CMOS devices. In addition, we show the derivation of the DQDs’ capacitances, including the gate cross capacitances, as a function of the spacing between the two adjacent charge triple points. By using these capacitances, the electron transport properties of the DQD structure are simulated, and the modulation of the electrostatic coupling is successfully simulated as the change of the total capacitance in DQDs.

Yamahata, Gento; Tsuchiya, Yoshishige; Oda, Shunri; Durrani, Zahid A. K.; Mizuta, Hiroshi

2008-06-01

382

Silicone metalization  

DOEpatents

A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2008-12-09

383

Silicone metalization  

DOEpatents

A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2006-12-05

384

Thermally controlled coupling of a rolled-up microtube integrated with a waveguide on a silicon electronic-photonic integrated circuit.  

PubMed

We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up microtube and a waveguide on a silicon electronic-photonic integrated circuit. The microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the microtube and the waveguide using localized heaters, the microtube-waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0-6 V. PMID:24784081

Zhong, Qiuhang; Tian, Zhaobing; Veerasubramanian, Venkat; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

2014-05-01

385

Fast direct voltage controller for VSC transmission  

Microsoft Academic Search

This paper develops a controller that enables good stability and fast responses of voltage source converter (VSC) transmission. The design is challenging because the uncontrolled system is multivariable having two possible rectifier inputs and many possible rectifier outputs and similar inputs and outputs on the inverter side. It is determined that the fastest possible controller is inverter DC voltage. An

L. A. Lamont; D. Jovcic; K. Abbott

2004-01-01

386

Enhanced light absorption of amorphous silicon thin film by substrate control and ion irradiation  

NASA Astrophysics Data System (ADS)

Large-area periodically aligned silicon nanopillar (PASiNP) arrays were fabricated by magnetic sputtering with glancing angle deposition (GLAD) on substrates coated by a monolayer of close-packed polystyrene (PS) nanospheres. The structure of PASiNP arrays could be manipulated by changing the diameter of PS nanospheres. Enhanced light absorptance within a wavelength range from 300 to 1,000 nm was observed as the diameter of nanopillars and porosity of PASiNP arrays increased. Meanwhile, Xe ion irradiation with dose from 1 × 1014 to 50 × 1014 ions/cm2 was employed to modify the surface morphology and top structure of thin films, and the effect of the irradiation on the optical bandgap was discussed.

Yuan, Fangda; Li, Zhengcao; Zhang, Tianci; Miao, Wei; Zhang, Zhengjun

2014-04-01

387

Nuclear magnetic resonance linewidth and spin diffusion in {sup 29}Si isotopically controlled silicon  

SciTech Connect

A nuclear magnetic resonance (NMR) study was performed with n-type silicon single crystals containing {sup 29}Si isotope abundance f ranges from 1.2% to 99.2%. The nuclear spin diffusion coefficient D has been determined from the linewidth of significantly enhanced {sup 29}Si NMR signals utilizing a developed dynamic nuclear polarization (DNP) method. The {sup 29}Si NMR linewidth depends linearly on f, at least when f<10%, and approaches {proportional_to}f{sup 1/2} dependence when f>50%. The estimated {sup 29}Si nuclear spin diffusion time T{sub sd} between phosphorus atoms used for DNP is more than ten times shorter than the nuclear polarization time T{sub 1}{sup p} of {sup 29}Si nuclei around phosphorus. Therefore, the regime of 'rapid spin diffusion' is realized in the DNP experiments.

Hayashi, Hiroshi; Itoh, Kohei M.; Vlasenko, Leonid S. [Department of Applied Physics and Physico-Informatics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); A. F. Ioffe Physico-Technical Institute, 194021 Saint Petersburg (Russian Federation)

2008-10-15

388

Enhanced light absorption of amorphous silicon thin film by substrate control and ion irradiation  

PubMed Central

Large-area periodically aligned silicon nanopillar (PASiNP) arrays were fabricated by magnetic sputtering with glancing angle deposition (GLAD) on substrates coated by a monolayer of close-packed polystyrene (PS) nanospheres. The structure of PASiNP arrays could be manipulated by changing the diameter of PS nanospheres. Enhanced light absorptance within a wavelength range from 300 to 1,000 nm was observed as the diameter of nanopillars and porosity of PASiNP arrays increased. Meanwhile, Xe ion irradiation with dose from 1?×?1014 to 50?×?1014 ions/cm2 was employed to modify the surface morphology and top structure of thin films, and the effect of the irradiation on the optical bandgap was discussed. PACS code 81.15.Cd; 78.66.Jg; 61.80.Jh

2014-01-01

389

Semiconductor-metal phase transition of vanadium dioxide nanostructures on silicon substrate: Applications for thermal control of spacecraft  

NASA Astrophysics Data System (ADS)

We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The VO2 phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO2 which has been explained by applying the Maxwell Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices to be applied for the thermal control of spacecraft. We have also applied the photothermal radiometry in order to study the changes in the modulated emissivity induced by laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide based structures.

Leahu, G. L.; Li Voti, R.; Larciprete, M. C.; Belardini, A.; Mura, F.; Fratoddi, I.; Sibilia, C.; Bertolotti, M.

2014-06-01

390

Quasi-phase-matched second harmonic generation in silicon nitride ring resonators controlled by static electric field.  

PubMed

Actively-controlled second harmonic generation in a silicon nitride ring resonator is proposed and simulated. The ring was designed to resonate at both pump and second harmonic wavelengths and quasi-phase-matched frequency conversion is induced by a periodic static electric field generated by voltage applied to electrodes arranged along the ring. Nonlinear propagation simulations were undertaken and an efficiency of -21.67 dB was calculated for 60 mW of pump power at 1550 nm and for a 30V applied voltage, which compares favorably with demonstrated all-optical second harmonic generation in integrated microresonators. Transient effects were also evaluated. The proposed design can be exploited for the construction of electro-optical devices based on nonlinear effects in CMOS compatible circuits. PMID:24514862

de Oliveira, Rafael E P; de Matos, Christiano J S

2013-12-30

391

Characterization of a controlled electroless deposition of copper thin film on germanium and silicon surfaces  

NASA Astrophysics Data System (ADS)

Nanofilms of copper were deposited on silicon and, for the first time, on polycrystalline germanium substrates by electroless deposition. Germanium or silicon disks were immersed in a 10 mM copper sulfate solution containing dilute hydrofluoric acid at room temperature. This simple one-step deposition does not require the use of laborious operations or expensive equipment, that the reaction medium be degassed, or that the film be annealed. The copper film grows in a few minutes, producing a film on both Ge and Si that covers a very large area of the substrate in contrast to other metals such as Au, Ag, Pt and Pd for which deposition on Ge and Si produces islands or dendrites. Atomic force microscopy, X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (PXRD) were used to characterize the microstructure and confirmed the formation of elemental copper nanofilms. The AFM micrographs reveal a Stranski-Krastanov type of film growth (layers + islands) that varies with the length of time the Ge or Si substrate is immersed in the CuSO 4 solution. Thicker films were observed on the Ge than on the Si substrate resulting in larger particles and rougher surface than on Si. XPS analysis shows that the elemental copper is deposited on both Ge and Si substrates and that the films oxidize over a period of weeks with air exposure at room temperature. Finally, PXRD data reveal two preferential orientations (1 1 1) and (2 0 0) for the copper crystallites grown on both Ge and Si. The same intensity of the (1 1 1)-texture was measured on both Ge and Si substrate which is an important result because it has been shown that the (1 1 1) texture reduces stress-induced voiding and increases resistance to electromigration in metal interconnects.

Scudiero, Louis; Fasasi, Ayuba; Griffiths, Peter R.

2011-02-01

392

Single-Switch Snubber Energy Recovery Bridge Leg for Buck Rectifier Applications  

NASA Astrophysics Data System (ADS)

Single-switch bridge leg with a snubber energy recovery feature is studied for buck rectifier applications. To recover the snubber energy, two snubber capacitors are arranged across an active power device. An example of a single-phase rectifier applying a proposed bridge leg is implemented to investigate the operation. The experimental results under the sinusoidal pulse-width modulation confirm that the rectifier can recover the snubber energy and the input current is almost wave-shaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu

393

Analysis of three-phase rectifiers with AC-side switches and interleaved three-phase voltage-source converters  

NASA Astrophysics Data System (ADS)

Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage-source converters is also analyzed. The low frequency circulating current characteristics of abc, dq, and nonlinear average current control are determined and experimental results for the nonlinear average current control are presented.

Miller, Stephanie Katherine Teixeira

394

Factors controlling the silicon isotope distribution in waters and surface sediments of the Peruvian coastal upwelling  

NASA Astrophysics Data System (ADS)

We present the first systematic study of the silicon isotope composition in the water column (?30Si) and in diatoms (?30Sidiatom) from the underlying surface sediments in a coastal upwelling region. The surface waters upwelling on the shelf off Peru are mainly fed by southward flowing subsurface waters along the coast, which show a mean ?30Si of +1.5‰. The concentration of dissolved silicic acid (Si(OH)4) increases towards the south in these waters and with increasing water depth, suggesting lateral mixing with water masses from the south and intense remineralisation of particulate biogenic silica (bSiO2) in the water column and in the surface sediments. Surface waters in the realm of the most intense upwelling between 5°S and 15°S have only marginally elevated ?30Si values (?30Si = +1.7‰) with respect to the source Si isotope composition, whereas further north and south, where upwelling is less pronounced, surface waters are more strongly fractionated (?30Si up to +2.8‰) due to the stronger utilisation of the smaller amounts of available Si(OH)4. The degree of Si(OH)4 utilisation in the surface waters along the shelf estimated from the Si(OH)4 concentration data ranges from 51% to 93%. The ?30Sidiatom values of hand-picked diatoms in the underlying surface sediments vary from +0.6‰ to +2.0‰, which is within the range of the expected fractionation between surface waters and diatoms. The fractionation signal in the surface waters produced during formation of the diatoms is reflected by the ?30Sidiatom values in the underlying sediments, with the lowest ?30Sidiatom values in the main upwelling region. The silicon isotope compositions of bSiO2 (?30Si) from the same surface sediment samples are generally much lower than the ?30Sidiatom signatures indicating a significant contamination of the bSiO2 with biogenic siliceous material other than diatoms, such as sponge spicules. This shift towards lighter ?30Si values by up to -1.3‰ compared to ?30Sidiatom signatures for the same surface sediment samples potentially biases the interpretation of ?30Si paleorecords from sediments with low bSiO2 concentrations, and thus the reconstruction of past Si(OH)4 utilisation in surface waters.

Ehlert, Claudia; Grasse, Patricia; Mollier-Vogel, Elfi; Böschen, Tebke; Franz, Jasmin; de Souza, Gregory F.; Reynolds, Ben C.; Stramma, Lothar; Frank, Martin

2012-12-01

395

Rectified Continuous Flow Loop for the Thermal Management of Large Structures  

NASA Astrophysics Data System (ADS)

Distributed loads are frequently encountered in large deployable structures used in space applications such as optical mirrors, actively cooled sunshades, and on focal plane electronics. One mechanism for providing distributed cooling is via an oscillatory cryocooler such as a pulse-tube that is integrated with a fluid rectification system consisting of check-valves and buffer volumes in order to extract a small amount of continuous flow. This continuous flow allows relatively large loads to be accepted over a long distance with a small temperature difference and has advantages relative to vibration and electrical isolation. Also, it is possible to provide rapid and precise temperature control via modulation of the flow rate. The same working fluid, helium, can be used throughout the entire system, reducing complexity and simplifying the contamination control process. This paper describes steady state and transient modeling results and presents experimental data for a single-stage pulse tube with a rectifying interface that is integrated with a distributed load. The predicted and measured steady state and transient behaviors are compared. The experimental data are used to demonstrate the thermal management concept and illustrate how it can be used for rapid and precise temperature control.

Skye, H. M.; Hoch, D. W.; Nellis, G. F.; Maddocks, J. R.; Klein, S. A.; Roberts, T.; Davis, T.

2006-04-01

396

Cell technology: Advanced silicon sheet  

NASA Technical Reports Server (NTRS)

The Flat-plate Solar Array (FSA)-sponsored Fourth Silicon Stress/Strain Workshop reviewed, coordinated, and assessed the progress in understanding and controlling stress and strain during the crystal growth of silicon ribbons. dislocation electrical activity and limits on solar cell efficiency, and on studying the effects of dopants on EFG characteristics. Work on silicon for high-efficiency solar cells, stress-strain relationships in silicon ribbon, and high temperature deformation of dendritic web ribbon was also discussed.

Morrison, Andrew D.

1986-01-01

397

Radiation effects in silicon-on-insulator transistors with back-gate control method fabricated with OKI Semiconductor 0.20 ?m FD-SOI technology  

NASA Astrophysics Data System (ADS)

Bonded silicon-on-insulator (SOI) wafers have the capability of realizing monolithic pixel devices, where the silicon resistivity is optimized separately for the electronics and detector parts. Using UNIBOND wafers, we are developing monolithic pixel devices fabricated with OKI Semiconductor 0.20 ?m FD-SOI technology. A set of PMOS and NMOS transistors were irradiated with protons in order to investigate the total ionization dose effect in transistor operation. We evaluated also the devices with a back-gate control electrode added underneath the buried oxide layer. Primary radiation effect appears in transistor threshold shifts, which can be explained by charge traps in the oxide layers and charge states created at the silicon-oxide boundaries. We discuss the possibility of TCAD simulation for evaluation of the charge densities.

Kochiyama, M.; Sega, T.; Hara, K.; Arai, Y.; Miyoshi, T.; Ikegami, Y.; Terada, S.; Unno, Y.; Fukuda, K.; Okihara, M.

2011-04-01

398

Voltage controlled exchange energies of a two-electron silicon double quantum dot with and without charge defects in the dielectric  

NASA Astrophysics Data System (ADS)

Quantum dots are artificial atoms used for a multitude of purposes. Charge defects are commonly present and can significantly perturb the designed energy spectrum and purpose of the dots. Voltage controlled exchange energy in silicon double quantum dots (DQDs) represents a system that is very sensitive to charge position and is of interest for quantum computing. We calculate the energy spectrum of the silicon double quantum dot system using a full configuration interaction that uses tight-binding single-particle wave functions. This approach allows us to analyze atomic scale charge perturbations of the DQD while accounting for the details of the complex momentum space physics of silicon (i.e., valley and valley-orbit physics). We analyze how the energy levels and exchange curves for a DQD are affected by nearby charge defects at various positions relative to the dot, which are consistent with defects expected in the metal-oxide-semiconductor system.

Rahman, Rajib; Nielsen, Erik; Muller, Richard P.; Carroll, Malcolm S.

2012-03-01

399

Porosity control in metal-assisted chemical etching of degenerately doped silicon nanowires  

NASA Astrophysics Data System (ADS)

We report the fabrication of degenerately doped silicon (Si) nanowires of different aspect ratios using a simple, low-cost and effective technique that involves metal-assisted chemical etching (MacEtch) combined with soft lithography or thermal dewetting metal patterning. We demonstrate sub-micron diameter Si nanowire arrays with aspect ratios as high as 180:1, and present the challenges in producing solid nanowires using MacEtch as the doping level increases in both p- and n-type Si. We report a systematic reduction in the porosity of these nanowires by adjusting the etching solution composition and temperature. We found that the porosity decreases from top to bottom along the axial direction and increases with etching time. With a MacEtch solution that has a high [HF]:[H2O2] ratio and low temperature, it is possible to form completely solid nanowires with aspect ratios of less than approximately 10:1. However, further etching to produce longer wires renders the top portion of the nanowires porous.

Balasundaram, Karthik; Sadhu, Jyothi S.; Shin, Jae Cheol; Azeredo, Bruno; Chanda, Debashis; Malik, Mohammad; Hsu, Keng; Rogers, John A.; Ferreira, Placid; Sinha, Sanjiv; Li, Xiuling

2012-08-01

400

Simulation studies of creeping flexible nematogens: flocking and rectifying barriers  

NASA Astrophysics Data System (ADS)

Recent simulation studies of active nematics have focused on rigid rods or swimming bacteria undergoing collisions via simple rules. Here we present a more physically detailed model of self-propelled creeping flexible nematogens. Each segmented "worm" is represented as nine interaction sites connected by springs. The springs' equilibrium length is modulated, causing each worm to elongate and contract periodically. Each worm alternately grips the substrate at its leading or trailing end, producing creeping locomotion. Inter-worm interactions are described via the Weeks-Chandler-Anderson potential between nearby interaction sites. Random forces and damping are also added. For worms that reverse crawling direction at random intervals, we observe a homogeneous nematic phase, and study its behavior in the presence of a rectifying barrier. For worms that move only in a single direction, we observe flocking behavior characterized by evolving stripes of densely crowded particles interspersed with low-density regions. We compare these results with relevant experiments and related theory/simulation approaches.

Nicholas, Adam; Selinger, Robin

2011-03-01

401

Remote Electrical Stimulation by Means of Implanted Rectifiers  

PubMed Central

Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants – batteries and inductive couplers – comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. In this way, low frequency currents will be generated locally around the implant and these low frequency currents will perform stimulation of excitable tissues whereas the high frequency currents will cause only innocuous heating. The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 µm) deliverable by injection are easily conceivable.

Ivorra, Antoni

2011-01-01

402

Permeation and Gating of an Inwardly Rectifying Potassium Channel  

PubMed Central

Permeation, gating, and their interrelationship in an inwardly rectifying potassium (K+) channel, ROMK2, were studied using heterologous expression in Xenopus oocytes. Patch-clamp recordings of single channels were obtained in the cell-attached mode. The gating kinetics of ROMK2 were well described by a model having one open and two closed states. One closed state was short lived (?1 ms) and the other was longer lived (?40 ms) and less frequent (?1%). The long closed state was abolished by EDTA, suggesting that it was due to block by divalent cations. These closures exhibit a biphasic voltage dependence, implying that the divalent blockers can permeate the channel. The short closures had a similar biphasic voltage dependence, suggesting that they could be due to block by monovalent, permeating cations. The rate of entering the short closed state varied with the K+ concentration and was proportional to current amplitude, suggesting that permeating K+ ions may be related to the short closures. To explain the results, we propose a variable intrapore energy well model in which a shallow well may change into a deep one, resulting in a normally permeant K+ ion becoming a blocker of its own channel.

Choe, Han; Sackin, Henry; Palmer, Lawrence G.

1998-01-01

403

Monitoring and Control of the Formation of Silicon Nanoparticles in RF Plasmas for the Optimization of the Quality of Nanostructured Silicon Films  

NASA Astrophysics Data System (ADS)

The spectacular development of the nanosciences has lead in a high interest in nanostructured materials. Among all the techniques used for their fabrication, plasma processing offers the possibility of depositing areas up to ˜1m^2 and deposition rates up to 10nm/s. In this paper, we focus on nanometer size silicon nanoparticles, which opens the possibility of fabricating optoelectronic devices such as non volatile memories or light emitting devices, but also open the possibility of obtaining nanostructured silicon materials, which have new properties. We will first present high resolution transmission electron micrographs of the material obtained under conditions where silicon nanoparticles are produced. Then, we will show how the contribution of the nanoparticles to the deposition are associated with an enhancement of the electronic properties of the material. This has motivated the study of the gas phase nucleation of the particles in order to maximize their contribution. For that purpose, we have set up an in situ Cavity Ring Down experiment, which measures absorption coefficients of the gas phase between 10-6 and 10-9cm-1, just at the right range to detect and quantify silicon nanoparticles at the concentrations . We have found concentrations of 10^9particles/cm^3 in our usual discharge conditions and tuned them in order to optimize the concentration of nanoparticles one order of magnitude, just before their coagulation in the gas phase, which has lead into an optimization of the material. Effects of the thermophoretic force on the transport of the nanoparticles, will also be presented. We will show how if thermal gradients in the chamber are high enough, the flow of the nanoparticles can be opposite to the gas drag.

Morral, Anna Fontcuberta I.; Grangeon, Frederic; Cabarrocas, Pere Roca I.

2002-10-01

404

Monitoring and Control of the Formation of Silicon Nanoparticles in RF Plasmas for the Optimization of the Quality of Nanostructured Silicon Films  

Microsoft Academic Search

The spectacular development of the nanosciences has lead in a high interest in nanostructured materials. Among all the techniques used for their fabrication, plasma processing offers the possibility of depositing areas up to ˜1m^2 and deposition rates up to 10nm\\/s. In this paper, we focus on nanometer size silicon nanoparticles, which opens the possibility of fabricating optoelectronic devices such as

Anna Fontcuberta I. Morral; Frederic Grangeon; Pere Roca I. Cabarrocas

2002-01-01

405

State-space average modelling of synchronous generator fed 18-pulse diode rectifier  

Microsoft Academic Search

The paper derives an analytical state-space average-value model of the direct symmetric topology of an 18-pulse AC-DC rectifier. The dynamic characteristics of the rectifier are fully represented while the model is time invariant and computationally efficient. The developed model, validated with comparison of the resultant transient and steady state behaviors with those obtained from detailed simulations of a test system

Antonio Griffo; Jiabin Wang

2009-01-01

406

Electrostatic tuning of Mg2+ affinity in an inward-rectifier K+ channel  

Microsoft Academic Search

INWARD-RECTIFIER potassium channels conduct K+across the cell membrane more efficiently in the inward than outward direction. This unusual conduction property is directly related to the biological action of these channels1-6. One basis for inward rectification is voltage-dependent blockade by intracellular Mg2+ (refs 1, 7-9): strong inward-rectifier channels are so sensitive to intracellular Mg2+ that no outward K+ current is measurable

Zhe Lu; Roderick MacKinnon

1994-01-01

407

Design and test of a 2.25-MW transformer rectifier assembly  

NASA Technical Reports Server (NTRS)

A new 2.25-MW transformer rectifier assembly was fabricated for DSS-13 at Goldstone, California. The transformer rectifier will provide constant output power of 2.25 MW at any voltage from 31 kV to 125 kV. This will give a new capability of 1 MW of RF power at X-band, provided appropriate microwave tubes are in the power amplifier. A description of the design and test results is presented.

Cormier, R.; Daeges, J.

1989-01-01

408

Stability analysis of input-series output-parallel connected buck rectifiers  

Microsoft Academic Search

AC voltages in the range of few kV have to be processed before being fed to traction motors. DC traction motors are normally designed for medium voltage and high current (1.2kV-1.5kV and 1200-1500A). Front-End Buck-Rectifiers are a viable solution for direct conversion of high ac voltage to low dc output voltage. However several buck-rectifier modules need to be connected in

Poonam Chaudhary; Ashish Agarwal; Parthasarathi Sensarma

2010-01-01

409

Single-Phase to Three-Phase Drive System Using Two Parallel Single-Phase Rectifiers  

Microsoft Academic Search

This paper proposes a single-phase to three-phase drive system composed of two parallel single-phase rectifiers, a three-phase inverter, and an induction motor. The proposed topology permits to reduce the rectifier switch currents, the harmonic distortion at the input converter side, and presents improvements on the fault tolerance characteristics. Even with the increase in the number of switches, the total energy

Cursino Brandão Jacobina; Euzeli Cipriano dos Santos Jr.; Nady Rocha; Edgard Luiz Lopes Fabrício

2010-01-01

410

Novel pseudo RMS current converter for sinusoidal signals using a CMOS precision current rectifier  

Microsoft Academic Search

A very simple pseudo RMS-to-DC current converter for sinusoidal signals is described. The most salient feature of the circuit is that it uses a CMOS precision current rectifier consisting of only two transistors and thus operates throughout in the current domain. The full-wave rectifier was built using CD4007 devices and tested. It was observed that the transfer curve is sharp

Z. Wang

1990-01-01

411

Molecular Coupling between Voltage Sensor and Pore Opening in the Arabidopsis Inward Rectifier KChannel KAT1  

Microsoft Academic Search

Animal and plant voltage-gated ion channels share a common architecture. They are made up of four subunits and the positive charges on helical S4 segments of the protein in animal Kchannels are the main voltage-sensing elements. The KAT1 channel cloned from Arabidopsis thaliana, despite its structural similarity to animal outward rectifier Kchannels is, however, an inward rectifier. Here we detected

Ramon Latorre; Riccardo Olcese; Claudia Basso; Carlos Gonzalez; Fabian Muñoz; Diego Cosmelli; Osvaldo Alvarez

412

Bridgeless Boost Rectifier With Low Conduction Losses and Reduced Diode Reverse-Recovery Problems  

Microsoft Academic Search

A bridgeless boost rectifier with low conduction losses and reduced diode reverse-recovery problems is proposed for power-factor correction. The proposed boost rectifier can reduce the conduction losses and alleviate the diode reverse-recovery problems by using a coupled inductor and two additional diodes. Zero-current turn-off of the output diodes is achieved, and the reverse-recovery currents of the additional diodes are slowed

Woo-Young Choi; Jung-Min Kwon; Eung-Ho Kim; Jong-Jae Lee; Bong-Hwan Kwon

2007-01-01

413

D0 Silicon Strip Detector Upgrade Project SVX Sequencer Controller Board  

SciTech Connect

The Sequencer Controller boards are 9U by 340mm circuit boards that will reside in slot 1 of each of eight Sequencer crates in the D0 detector platform. The primary purpose is to control the Sequencers during data acquisition based on trigger information from the D0 Trigger Framework. Functions and features are as follows: (1) Receives the Serial Command Link (SCL) from the D0 Trigger System and controls the operation of the Sequencers by forming a custom serial control link (NRZ/Clock) which is distributed individually to each Sequencer via the 11 Backplane; (2) Controllable delays adjust NRZ control link phasing to compensate for the various cable-length delays between the Sequencers and SVX chips, delay control is common for slots 2-11, and for slots 12-21 of the crate; (3) Each NRZ control link is phase controlled so that commands reach each Sequencer in a given half-crate simultaneously, i.e., the link is compensated for backplane propagation delays; (4) External communication via MIL-STD-1553; (5) Stand-alone operation via 1553 trigger commands in absence of an SCL link; (6) 1553-writeable register for triggering a laser, etc. followed by an acquisition cycle; (7) TTL front panel input to trigger an acquisition cycle, e.g. from a scintillator; (8) Synch Trig, Veto, Busy and Preamp Reset TTL outputs on front panel LEMOs; (9) On-board 53.104 MHz oscillator for stand-alone operation; (10) 1553 or SCL-triggerable Cal-inject cycle; (11) Front-panel inputs to accept NRZ/Clock link from the VRB Controller; (12) Front panel displays and LEDs show the board status at a glance; and (13) In-system programmable EPLDs are programmed via Altera's 'Byteblaster'.

Utes, M.; /Fermilab

2001-05-29

414

Effects of insertion of hole injection layers on pentacene rectifying diodes.  

PubMed

The main issue of the organic rectifier, the key element in radio frequency identification tags, is to improve forward-bias current density of an organic diode in the rectifier, which increases the frequency response of the rectifier. One approach to achieve high current density is inserting a hole injection layer (HIL) between the anode and the active layer to enhance the charge injection efficiency. Here we study the effect of HILs in pentacene rectifying diodes. Three different hole injection layers are applied to the pentacene diode: molybdenum trioxide (MoO3), 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN), and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). A rectifier consists of the diode with a capacitor. The results show that current density of diodes with HILs is increased by more than three orders of magnitude compared with the diode without a HIL. The diode with MoO3 and that with HAT-CN shows similar forward bias current density, while that of the diode with PEDOT:PSS is slightly lower than those. Finally, the output voltage of the rectifier with a HIL is 4.6 V at 100 MHz when input voltage of 10 V is applied. PMID:24758021

Kang, Chan-Mo; Cho, Hyunduck; Park, Myeongjin; Roh, Jeongkyun; Lee, Changhee

2014-07-01

415

Controlled Synthesis of Millimeter-Long Silicon Nanowires with Uniform Electronic Properties  

PubMed Central

We report the nanocluster-catalyzed growth of ultra-long and highly-uniform single-crystalline silicon nanowires (SiNWs) with millimeter-scale lengths and aspect ratios up to ca. 100,000. The average SiNW growth rate using disilane (Si2H6) at 400 °C was 31 µm/min, while the growth rate determined for silane (SiH4) reactant under similar growth conditions was 130 times lower. Transmission electron microscopy studies of millimeter-long SiNWs with diameters of 20–80 nm show that the nanowires grow preferentially along the <110> direction independent of diameter. In addition, ultra-long SiNWs were used as building blocks to fabricate one-dimensional arrays of field-effect transistors (FETs) consisting of ca. 100 independent devices per nanowire. Significantly, electrical transport measurements demonstrated that the millimeter-long SiNWs had uniform electrical properties along the entire length of wires, and each device can behave as a reliable FET with an on-state current, threshold voltage, and transconductance values (average ± 1 standard deviation) of 1.8 ± 0.3 µA, 6.0 ± 1.1 V, 210 ± 60 nS, respectively. Electronically-uniform millimeter-long SiNWs were also functionalized with monoclonal antibody receptors, and used to demonstrate multiplexed detection of cancer marker proteins with a single nanowire. The synthesis of structurally- and electronically-uniform ultra-long SiNWs may open up new opportunities for integrated nanoelectronics, and could serve as unique building blocks linking integrated structures from the nanometer through millimeter length scales.

Park, Won Il; Zheng, Gengfeng; Jiang, Xiaocheng; Tian, Bozhi; Lieber, Charles M.

2009-01-01

416

Compilation de Silicium: Application a la Compilation de Partie Controle (Silicon Compilers: Application to the Compilation of the Control Area).  

National Technical Information Service (NTIS)

The compilable structures of microprocessor integrated circuits are analyzed, using the Von Neuman machine concept. Different schemes of the topology for control implementation are presented. Compilation tools developed are described. Examples of circuit ...

P. Varinot

1987-01-01

417

Technological Breakthroughs in Growth Control of Silicon Carbide for High Power Electronic Devices  

Microsoft Academic Search

Technological breakthroughs in growth control of SiC are reviewed. Step-controlled epitaxy by using off-axis SiC {0001} substrates to grow high-quality epitaxial layer is explained in detail. The introduction of substrate off-angles brings step-flow growth, which easily makes polytype replication of SiC at rather low temperatures. Off-angle dependence, rate-determining processes, and temperature dependence of growth rate are discussed. Prediction, whether step-flow

Hiroyuki Matsunami

2004-01-01

418

Synchronous rectification with adaptive timing control  

Microsoft Academic Search

This paper describes a MOSFET synchronous rectifier suitable for use in high-frequency DC-DC converters. The MOSFET control circuitry is designed to replicate the basic functionality of a rectifier diode, turning on when the voltage across the device falls to zero, and turning off when the current through the device tries to reverse. This synchronous rectification device can be incorporated into

Brian Acker; Charles R. Sullivan; Seth R. Sanders

1995-01-01

419

Derivation and verification of a model of the synchronous machine with rectifier with two damper windings of the direct axis  

NASA Astrophysics Data System (ADS)

Starting with the derivation of the separate models of the synchronous machine and the rectifier, a steady state model and a dynamic model are derived. The dynamic model is a global model, in which very fast phenomena, such as the ripple on the direct current, are neglected. Due to the abscence of very fast behavior the model is well suited for implementation in a control system for a wind turbine: with a minimum of computational effort the global behavior of the system can be predicted. Since the model contains a number of unknown synchronous machine parameters, a simple method was designed to estimate these parameters. It is based on the stand still step response test with the stator voltage as excitation and the stator (and rotor) currents as responses. A least squares estimator is used to estimate the parameters from the measurements. From the comparison of measured and simulated behavior of the synchronous machine with rectifier it follows that the model (in combination with the parameter estimation method) is a good description of the actual system.

Hoeijmakers, M. J.; Vleeshouwers, J. M.

1990-12-01

420

Sputtered iron oxide/silicon heterostructures  

NASA Astrophysics Data System (ADS)

Sputtered Fe3O4 films are shown to form rectifying junctions to p-type silicon but ohmic contacts to n-type Si. It is pointed out that ohmic contacts to the Fe3O4 can be provided by Au, Al, or spray-deposited ITO. The redox couple Fe(CN)6(3-)/Fe(CN)6(4-) also seems to make an effective ohmic contact to this iron oxide. It is found that the photovoltaic and electrical characteristics of the Fe3O4/p-Si heterojunction depend strongly on the Fe3O4 film thickness.

Kardauskas, M. J.; Fonash, S. J.; Ashok, S.; Krishnaswamy, S. V.; Messier, R. F.

1981-03-01

421

BOREAS TE-18, 60-m, Radiometrically Rectified Landsat TM Imagery  

NASA Technical Reports Server (NTRS)

The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 2 1 Jun-1995. The 23 rectified images cover the period of 07-Jul-1985 to 18-Sep-1994 in the SSA and 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (1991). The original Landsat TM data were received from CCRS for use in the BOREAS project. Due to the nature of the radiometric rectification process and copyright issues, the full-resolution (30-m) images may not be publicly distributed. However, this spatially degraded 60-m resolution version of the images may be openly distributed and is available on the BOREAS CD-ROM series. After the radiometric rectification processing, the original data were degraded to a 60-m pixel size from the original 30-m pixel size by averaging the data over a 2- by 2-pixel window. The data are stored in binary image-format files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

Hall, Forrest G. (Editor); Knapp, David

2000-01-01

422

BOREAS TE-18, 30-m, Radiometrically Rectified Landsat TM Imagery  

NASA Technical Reports Server (NTRS)

The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 21-Jun-1995. the 23 rectified images cover the period of 07-Jul-1985 to 18 Sep-1994 in the SSA and from 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (199 1). The original Landsat TM data were received from CCRS for use in the BOREAS project. The data are stored in binary image-format files. Due to the nature of the radiometric rectification process and copyright issues, these full-resolution images may not be publicly distributed. However, a spatially degraded 60-m resolution version of the images is available on the BOREAS CD-ROM series. See Sections 15 and 16 for information about how to possibly acquire the full resolution data. Information about the full-resolution images is provided in an inventory listing on the CD-ROMs. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

Hall, Forrest G. (Editor); Knapp, David

2000-01-01

423

Long-pore Electrostatics in Inward-rectifier Potassium Channels  

PubMed Central

Inward-rectifier potassium (Kir) channels differ from the canonical K+ channel structure in that they possess a long extended pore (?85 Å) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gating. To elucidate the underpinnings of these functional roles, we examine the electrostatics of an ion along this extended pore. Homology models are constructed based on the open-state model of KirBac1.1 for four mammalian Kir channels: Kir1.1/ROMK, Kir2.1/IRK, Kir3.1/GIRK, and Kir6.2/KATP. By solving the Poisson-Boltzmann equation, the electrostatic free energy of a K+ ion is determined along each pore, revealing that mammalian Kir channels provide a favorable environment for cations and suggesting the existence of high-density regions in the cytoplasmic domain and cavity. The contribution from the reaction field (the self-energy arising from the dielectric polarization induced by the ion's charge in the complex geometry of the pore) is unfavorable inside the long pore. However, this is well compensated by the electrostatic interaction with the static field arising from the protein charges and shielded by the dielectric surrounding. Decomposition of the static field provides a list of residues that display remarkable correspondence with existing mutagenesis data identifying amino acids that affect conduction and rectification. Many of these residues demonstrate interactions with the ion over long distances, up to 40 Å, suggesting that mutations potentially affect ion or blocker energetics over the entire pore. These results provide a foundation for understanding ion interactions in Kir channels and extend to the study of ion permeation, block, and gating in long, cation-specific pores.

Robertson, Janice L.; Palmer, Lawrence G.; Roux, Benoit

2008-01-01

424

Edge terminations for SiC high voltage Schottky rectifiers  

Microsoft Academic Search

A study of floating metal field rings (FMRs) and resistive Schottky barrier field plate (RESP) edge terminations for high-voltage silicon carbide (SiC) Schottky barrier diodes (SBD) is reported. For a drift region doping of 2×1016 cm-3, numerical simulations indicated a breakdown voltage for an unterminated diode of about 225 V as compared to ≈1125 V for a parallel plane structure.

M. Bhatnagar; H. Nakanishi; S. Bothra; P. K. McLarty; B. J. Baliga

1993-01-01

425

Control of Crystal Orientation and Diameter of Silicon Nanowire Using Anodic Aluminum Oxide Template  

NASA Astrophysics Data System (ADS)

The control of the crystal orientation and diameter of vertically grown epitaxial Si nanowires was demonstrated using a combination of a vapor--liquid--solid (VLS) growth technique and the use of an anodic aluminum oxide (AAO) template on a single-crystal Si substrate. The [100], [110], and [111] nanowires were selectively obtained by choosing the Si substrate with appropriate crystal orientation. The diameter of a Si nanowire in the AAO template could be controlled by the modification of the pore size of the AAO template with anodic voltage during anodization.

Shimizu, Tomohiro; Inoue, Fumihiro; Wang, Chonge; Otsuka, Shintaro; Tada, Yoshihiro; Koto, Makoto; Shingubara, Shoso

2013-06-01

426

A refined cellular automaton model to rectify impractical vehicular movement behavior  

NASA Astrophysics Data System (ADS)

When implementing cellular automata (CA) into a traffic simulation, one common defect yet to be rectified is the abrupt deceleration when vehicles encounter stationary obstacles or traffic jams. To be more in line with real world vehicular movement, this paper proposes a piecewise-linear movement to replace the conventional particle-hopping movement adopted in most previous CA models. Upon this adjustment and coupled with refined cell system, a new CA model is developed using the rationale of Forbes’ et al. car-following concept. The proposed CA model is validated on a two-lane freeway mainline context. It shows that this model can fix the unrealistic deceleration behaviors, and thus can reflect genuine driver behavior in the real world. The model is also capable of revealing Kerner’s three-phase traffic patterns and phase transitions among them. Furthermore, the proposed CA model is applied to simulate a highway work zone wherein traffic efficiency (maximum flow rates) and safety (speed deviations) impacted by various control schemes are tested.

Lan, Lawrence W.; Chiou, Yu-Chiun; Lin, Zih-Shin; Hsu, Chih-Cheng

2009-09-01

427

Ultra-rapid delayed rectifier channels: molecular basis and therapeutic implications.  

PubMed

The ultrarapid delayed rectifier channels have attracted considerable interest as targets for 'atrial-selective' antiarrhythmic drugs because they contribute to atrial but not to ventricular repolarization. Thus, I(Kur) channel blockers are expected to prolong selectively the atrial effective refractory period without inducing proarrhythmic effects due to excessive ventricular action potential prolongation. Here we provide an overview of the properties of I(Kur) channels in expression systems and native cardiomyocytes. The ion conducting pore of the channel is formed by four Kv1.5 ?-subunits, whereas the ancillary ?-subunits Kv?1.2, Kv?1.3, and Kv?2.1 control channel trafficking and plasma membrane integration as well as activation and inactivation kinetics. Investigation of I(Kur) channel blockers in cardiomyocytes is complicated (i) by substantial overlap of I(Kur) with other currents, notably the transient outward current I(to), (ii) by lack of drug selectivity, and (iii) by disease-induced regulation of I(Kur). Some new compounds developed as I(Kur) blockers are described and their efficacy in treatment of atrial fibrillation (AF) is discussed. Current evidence suggests that pure I(Kur) channel block may not be sufficient to suppress AF. PMID:21159668

Ravens, Ursula; Wettwer, Erich

2011-03-01

428

DNA Physical Mapping via the Controlled Translocation of Single Molecules through a 5-10nm Silicon Nitride Nanopore  

NASA Astrophysics Data System (ADS)

The ability to map the binding position of sequence-specific markers, including transcription-factors, protein-nucleic acids (PNAs) or deactivated restriction enzymes, along a single DNA molecule in a nanofluidic device would be of key importance for the life-sciences. Such markers could give an indication of the active genes at particular stage in a cell's transcriptional cycle, pinpoint the location of mutations or even provide a DNA barcode that could aid in genomics applications. We have developed a setup consisting of a 5-10 nm nanopore in a 20nm thick silicon nitride film coupled to an optical tweezer setup. The translocation of DNA across the nanopore can be detected via blockades in the electrical current through the pore. By anchoring one end of the translocating DNA to an optically trapped microsphere, we hope to stretch out the molecule in the nanopore and control the translocation speed, enabling us to slowly scan across the genome and detect changes in the baseline current due to the presence of bound markers.

Stein, Derek; Reisner, Walter; Jiang, Zhijun; Hagerty, Nick; Wood, Charles; Chan, Jason

2009-03-01

429

Controlled aluminum-induced crystallization of an amorphous silicon thin film by using an oxide-layer diffusion barrier  

NASA Astrophysics Data System (ADS)

Aluminum-induced crystallization (AIC) of amorphous silicon with an Al2O3 diffusion barrier was investigated for controlling Si crystallization and preventing layer exchange during the annealing process. An Al2O3 layer was deposited between the a-Si and the Al films (a-Si/Al2O3/Al/Glass) and was blasted with an air spray gun with alumina beads to form diffusion channels between the Si and the Al layers. During the annealing process, small grain Si x Al seeds were formed at the channels. Then, the Al2O3 diffusion barrier was restructured to close the channels and prevent further diffusion of Al atoms into the a-Si layer. A polycrystalline Si film with (111), (220) and (311) crystallization peaks in the X-ray diffraction pattern was formed by annealing at 560 °C in a conventional furnace. That film showed a p-type semiconducting behavior with good crystallinity and a large grain size of up to 14.8 µm. No layer conversion occurred between the Si and the Al layers, which had been the fundamental obstacle to the applications in the crystallization of a-Si films by using the AIC method.

Hwang, Ji-Hyun; Kwak, Hyunmin; Kwon, Myeung Hoi

2014-03-01

430

Controlled Compensation Walls and Compromise Compensation Walls in Garnet Films by the Silicon Annealing Technique  

Microsoft Academic Search

The Si annealing technique has been used on Ga-substituted LPE bubble garnet films to reduce 4piM through zero and produce controlled, well-defined compensation walls. A Si film was deposited on a garnet film, patterned photolithographically, and annealed at 525°C for 40 hours in O2. This produced light and dark Faraday contrast regions separated by compensation walls which were independent of

R. C. Lecraw; R. Wolfe

1974-01-01

431

MEMS silicon-based resistojet micro-thruster for attitude control of nano-satellites  

Microsoft Academic Search

This paper presents a miniaturized resistojet thruster device with an integrated thin-film heater, capable of delivering thrusts in the micronewton–millinewton range. Its small size (25 mm × 5 mm × 1 mm), low mass (162 mg), low power and propellant consumption make it very attractive for attitude control of nano-satellites (mass 1-10 kg). Based on the pressure measurements with the

M. Mihailovic; T. V. Mathew; J. F. Creemer; B. T. C. Zandbergen; P. M. Sarro

2011-01-01

432

Duty ratio-controlled reflective property of silicon nitride films deposited at room temperature using a pulsed-PECVD at SiH 4–NH 3 plasma  

Microsoft Academic Search

Using pulsed, plasma-enhanced chemical vapor deposition system, silicon nitride films were deposited from SiH4 and NH3 at room temperature. Duty ratio was controlled in a range of 20–100% incrementally by 20% at radio frequency bias powers of 50, 70, and 90 W. Reflectance was studied as a function of the process parameters mentioned earlier. The impact of duty ratio on the

Daehyun Kim; Sujin Lee; Byungwhan Kim; Byung Jun Kang; Donghwan Kim

2011-01-01

433

Characteristics of degenerately doped silicon for spectral control in thermophotovoltaic systems  

SciTech Connect

Heavily doped Si was investigated for use as spectral control filter in thermal photovoltaic (TPV) system. These filters should reflect radiation at 4 {micro}m and above and transmit radiation at 2 {micro}m and below. Two approaches have been used for introducing impurities into Si to achieve high doping concentration. One was the diffusion technique, using spin-on dopants. The plasma wavelength ({lambda}{sub p}) of these filters could be adjusted by controlling the diffusion conditions. The minimum plasma wavelength achieved was 4.8 {micro}m. In addition, a significant amount of absorption was observed for the wavelength 2 {micro}m and below. The second approach was doping by ion implantation followed by thermal annealing with a capped layer of doped glass. Implantation with high dosage of B and As followed by high temperature annealing (> 1,000 C) resulted in a plasma wavelength that could be controlled between 3.5 and 6 {micro}m. The high temperature annealing (> 1,000 C) that was necessary to activate the dopant atoms and to heal the implantation damage, also caused significant absorption at 2 {micro}m. For phosphorus implanted Si, a moderate temperature (800--900 C) was sufficient to activate most of the phosphorus and to heal the implantation damage. The position of the plasma turn-on wavelength for an implantation dose of 2 {times} 10{sup 16} cm{sup {minus}2} of P was at 2.9 {micro}m. The absorption at 2 {micro}m was less than 20% and the reflection at 5 {micro}m was about 70%.

Ehsani, H.; Bhat, I.; Borrego, J.; Gutmann, R. [Rensselaer Polytechnic Inst., Troy, NY (United States); Brown, E.; Dzeindziel, R.; Freeman, M.; Choudhury, N. [Lockheed-Martin, Schenectady, NY (United States)

1995-07-01

434

Commissioning of the control and data acquisition electronics for the CDF Silicon Vertex Detector  

SciTech Connect

The SVX data acquisition system includes three components: a Fastbus Sequencer, an SVX Rabbit Crate Controller and a Digitizer. These modules are integrated into the CDF DAQ system and operate the readout chips. The results of the extensive functional tests of the SVX modules are reported. We discuss the stability of the Sequencers, systematic differences between them and methods of synchronization with the Tevatron beam crossings. The Digitizer ADC calibration procedure run on the microsequencer is described. The microsequencer code used for data taking and SVX chip calibration modes is described. Measurements of the SVX data scan time are discussed.

Tkaczyk, S.M.; Turner, K.J.; Nelson, C.A.; Shaw, T.M.; Wesson, T.R. [Fermi National Accelerator Lab., Batavia, IL (United States); Bailey, M.W.; Kruse, M.C. [Purdue Univ., Lafayette, IN (United States); Castro, A. [Padua Univ. (Italy)

1991-11-01

435

D0 Silicon Upgrade: Control Dewar Steady State Thermodynamic Operating Goals  

SciTech Connect

This engineering note documents the thermodynamic operating parameter goals for the steady state operation of the control dewar/solenoid system. Specifically, how the control dewar pressure control valve, PV-3062-H and the magnet flow control valve EVMF are operated to give the lowest possible temperature fluid at the solenoid magnet. The goals are: (1) For PV-3062-H - The process variable is the helium reservoir pressure, minimize the reservoir pressure, provide only enough pressure plus a little margin to ensure leads flow; and (2) For EVMF - The process variable is firstly a manual setpoint of flowrate as read by the flow venturi, FE3253-H, and secondly the reservoir liquid level, minimize the pressure drop thru the solenoid cooling tubes, provide at least enough flow to maintain reservoir level and stable operation of the magnet. The thermodynamic states for the fluid thru the system are shown on the Pressure versus Temperature graph. Lines of constant enthalpy are also shown. State A is shown as two phase liquid entering the inlet of the subcooler. The subcooler subcools the fluid to State B. State B to State C is caused by the pressure drop across EVMF. State C to D is the estimated pressure drop from the outlet of EVMF thru the solenoid cooling tubes and back up to the helium reservoir inlet. To give the coolest fluid in the cooling tubes, the two phase fluid in the reservoir should be at the lowest pressure (and thus temperature). This lowest pressure is limited by the required pressure for leads flow and if this does not dominate, the low pressure side pressure drop thru the refrigerator and suction pressure set point. My guess is the lead flow requirement will dominate. I suggest putting the PV-3062-H set point such that the lead flow control valves operate at about 80% open. The second parameter that will give the coolest fluid in the cooling tubes is a minimized pressure drop thru the cooling tubes. This can be accomplished by providing a minimized flowrate, sufficient only to ensure that the reservoir level is full and some liquid fraction leaves the helium outlet tubing. D-Zero Engineering note, EN-338, 'LHe Flow Regime/Pressure Drop for DO Solenoid at Steady State Conditions' shows that even though the gas fraction increases at lower flowrates, the pressure drop decreases. This goal is ideal, and assumes good cooling at the magnet. Real effects such hot spots or quench experience in the magnet may necessitate a higher flowrate. The current design flow rate from Toshiba is somewhere around 2.5 gls which is very low. Experience with the accuracy of the venturi flowmeter, coil characteristics etc. and some conservativeness will help determine the optimum flowrate. I would venture a guess that it would be a minimum of 5 g/s. The philosophy that I have been taking with transfer line and valve sizing is such that our refrigerator system will have the ability to supply up to at least 20 g/s if required and necessary. Preferably we will be around 5 g/s.

Rucincki, Russ; /Fermilab

1995-10-20

436

Cardiac ultrarapid delayed rectifiers: a novel potassium current family o f functional similarity and molecular diversity.  

PubMed

Classical cardiac delayed rectifier currents activate at least two orders of magnitude slower than delayed rectifier currents in nerve and skeletal muscle tissue. It has recently become evident that many cardiac tissues express delayed rectifier currents with kinetics similar to those of nerve and muscle. These currents have been designated I(Kur) (for 'ultrarapid' delayed rectifier), in contrast to the classical cardiac rapid (I(Kr)) and slow (I(Ks)) delayed rectifier components. Although the kinetics of I(Kur) in different species and tissues are similar, their pharmacological properties vary greatly. It now appears that the differences among various I(Kur)s are due to differences in the molecular basis. A variety of Shaker-related clones (Kv1.2, 1.5, 2.1 and 3.1) that form I(Kur) channels upon heterologous expression have been identified with specific I(Kur)s (e.g. Kv1.2, rat atrium; Kv1.5, mouse ventricle and human atrium; Kv3.1, dog atrium). The present article reviews the distribution, biophysical and pharmacological properties, molecular basis and functional role of I(Kur), as well as the potential value of I(Kur) as a target for new antiarrhythmic drug development. PMID:10575199

Nattel, S; Yue, L; Wang, Z

1999-01-01

437

Self-assembly of Ge quantum dots on Silicon: An example of controlled nanomanufacturing  

NASA Astrophysics Data System (ADS)

We have grown Ge quantum dots by Physical Vapor Deposition (PVD) on step bunched Si(111) surfaces, vicinal Si(001) surfaces and oxidized Si substrates. Control of one- and two-dimensional ordering of the islands was obtained combining top-down patterning techniques (Focused Ion Beam milling), naturally occurring instabilities and anisotropies typical of Si surfaces. Real-time study of growth kinetics and self-organization of the islands has been accomplished using Scanning Tunnelling Microscopy imaging in UHV. A software routine was used to analyze the in-plane ordering of the islands on selected images. We focused on the study of the first nucleation stages of the dots on high-miscut vicinal Si(001) surfaces, in an attempt to correlate the observed behavior with the properties of these surfaces. The relevance of this research to quantum-dots based technology is also discussed.

Bernardi, M.; Sgarlata, A.; Fanfoni, M.; Persichetti, L.; Motta, N.; Balzarotti, A.

2009-07-01

438

D0 Silicon Upgrade: Control Dewar Venturi Calibration Explanation for Toshiba  

SciTech Connect

This document is intended to explain the calibration data for the venturi, FE-3253H, which is installed in the control dewar. Further, this document will help explain how to use the venturi to make mass flow measurements during typical operating conditions. The purpose of the calibration data enclosed from the Colorado Engineering Experiment Station Inc. is to experimentally show that the venturi follows the flow equation which is enclosed as Eq. 7-36 on page 155, from the Applied Fluid Dynamics Handbook. The calibration data serves to show that the Subsonic Venturi, Serial Number 611980-18, produces results predicted by the compressible subsonic flow mass flow rate equation above and to experimentally determine the discharge coefficient C. Colorado Engineering Experiment Station Inc. ran tests at 15 independent differential pressures to conclude that use of this venturi will perform according to the mass flow rate equation. In order to verify the results from the Colorado Engineering Experiment Station Inc. we have provided you with a step-by-step procedure using the values they have chosen.

Kuwazaki, Andrew; /Fermilab

1997-01-24

439

Characterization and properties of controlled nucleation thermochemical deposited (CNTD) silicon carbide  

NASA Technical Reports Server (NTRS)

The microstructure of controlled nucleation thermochemical deposition (CNTD) - SiC material was studied and the room temperature and high temperature bend strength and oxidation resistance was evaluated. Utilizing the CNTD process, ultrafine grained (0.01-0.1 mm) SiC was deposited on W - wires (0.5 mm diameter by 20 cm long) as substrates. The deposited SiC rods had superior surface smoothness and were without any macrocolumnar growth commonly found in conventional CVD material. At both room and high temperature (1200 - 1380 C), the CNTD - SiC exhibited bend strength approximately 200,000 psi (1380 MPa), several times higher than that of hot pressed, sintered, or CVD SiC. The excellent retention of strength at high temperature was attributed to the high purity and fine grain size of the SiC deposit and the apparent absence of grain growth at elevated temperatures. The rates of weight change for CNTD - SiC during oxidation were lower than for NC-203 (hot pressed SiC), higher than for GE's CVD - SiC, and considerably below those for HS-130 (hot pressed Si3N4). The high purity, fully dense, and stable grain size CNTD - SiC material shows potential for high temperature structural applications; however problem areas might include: scaling the process to make larger parts, deposition on removable substrates, and the possible residual tensile stress.

Dutta, S.; Rice, R. W.; Graham, H. C.; Mendiratta, M. C.

1978-01-01

440

Theoretical study on the rectifying performance of organoimido derivatives of hexamolybdates.  

PubMed

We design a new type of molecular diode, based on the organoimido derivatives of hexamolybdates, by exploring the rectifying performances using density functional theory combined with the non-equilibrium Green's function. Asymmetric current-voltage characteristics were obtained for the models with an unexpected large rectification ratio. The rectifying behavior can be understood by the asymmetrical shift of the transmission peak observed under different polarities. It is interesting to find that the preferred electron-transport direction in our studied system is different from that of the organic D-bridge-A system. The results show that the studied organic-inorganic hybrid systems have an intrinsically robust rectifying ratio, which should be taken into consideration in the design of the molecular diodes. PMID:23303530

Wen, Shizheng; Yang, Guochun; Yan, Likai; Li, Haibin; Su, Zhongmin

2013-02-25

441

Small scale ethanol production demonstration: comparison of packed versus plate rectifying column  

SciTech Connect

The Johnson Environmental and Energy Center with assistance from the Madison County Farm Bureau Association received a grant in 1980 from the US Department of Energy to design, fabricate, and evaluate a small scale continuous ethanol plant. In 1981, the Center received a second DOE grant to compare the economics of replacing the plate rectifying column in the initial unit with a packed rectifying column. The results of the study indicate that the distillation unit with the packed rectifying column is capable of producing 14 gallons per hour of 170 proof ethanol. The energy ratio for distillation was a positive 2:1. Cost of the packed column was considerably less than the plate column. 1 reference, 19 figures, 9 tables.

Adcock, II, L E; Eley, M H; Schroer, B J

1982-07-01

442

Towards a 30kW/liter, Three-Phase Unity Power Factor Rectifier  

NASA Astrophysics Data System (ADS)

In this paper, a forced air-cooled, 400kHz, 10kW Vienna Rectifier with a power density of 8.5kW/liter is presented. To further improve the power density, the switching frequency is increased to reduce the EMI filter volume. A design for an 18.5kW/liter, 2.5MHz rectifier is proposed. By using today's technology, it is calculated that the maximum power density for a forced air-cooled and water-cooled rectifier is 20.8kW/liter and 24kW/liter respectively. To achieve 30kW/liter, improvements must be made in passive component material properties, reducing semiconductor losses and improving the cooling system.

Round, Simon; Karutz, Philipp; Heldwein, Marcelo; Kolar, Johann W.

443

Effect of contact geometry on 4H-SiC rectifiers with junction termination extension  

NASA Astrophysics Data System (ADS)

SiC rectifiers with an on/off current ratio of 4×10 5 (at 1.5 V/-500 V) were fabricated using junction termination extension (JTE) and dielectric overlap. The reverse breakdown voltage was inversely dependent on contact area and was not a strong function of JTE length up to 40 ?m. Similarly, for a given JTE length, the metal overlap did not have a strong influence on breakdown voltage. Oval- and circular-shaped contacts produced larger breakdown voltages than square rectifying contacts. The on-state resistance, RON, was 4.2 m ? cm 2, which is close to the theoretical minimum of these rectifiers using Ni Schottky contacts. The figure-of-merit ( VB) 2/ RON was as high as 156 MW cm -2.

Nigam, S.; Kim, J.; Luo, B.; Ren, F.; Chung, G. Y.; Pearton, S. J.; Williams, J. R.; Shenai, K.; Neudeck, P.

2003-01-01

444

Revisiting the Rectifier: New Observations of Covariance Between Terrestrial Carbon Cycling and Boundary Layer Depth (Invited)  

NASA Astrophysics Data System (ADS)

Covariance between land-surface carbon fluxes and vertical mixing in the atmosphere is among the strongest determinants of the spatial distribution of atmospheric CO2 in the lower troposphere. Differences in the magnitude of this "CO2 rectifier effect" among different tracer transport models has been shown to explain most of the variability in estimates of terrestrial carbon sinks over the northern (vs tropical) continents. We present a new analysis of the magnitude of the CO2 rectifier using a climatology of PBL depth estimated using vertical profiles of LIDAR backscatter from the CALIPSO satellite. Millions of separate soundings of PBL depth were matched with hourly estimates of photosynthesis and ecosystem respiration from the Simple Biosphere Model (SiB3) at the same locations and times over more than 6 years. Strong covariance between net carbon flux and atmospheric mixing were observed over the northern continents, especially over Boreal Asia. Negative covariance is observed over monsoon regions, which is especially strong over India. Covariance of net carbon flux with the reciprocal of PBL depth has the units of CO2 tendency (ppm per month), and can be expressed as rectifier forcing. Satellite sampling of this quantity reveals spatially-coherent patterns as strong as +/- 10 ppm per month over Siberia and India. We computed rectifier forcing with NASA's Modern Era Reanalysis (MERRA) for the same locations and times sampled by CALIPSO from 2006-2012. Comparison of the MERRA and CALIPSO data reveal that the spatial patterns and magnitudes are similar over the northern continents, but much weaker in MERRA than CALIPSO over the tropics. Using MERRA to compute the rectifier effect for SiB fluxes in GEOS-Chem allows us to establish a quantitative relationship between rectifier forcing and response that is evaluated against the CALIPSO boundary layer data. We propose a framework for model intercomparison and evaluation that can leverage the rich new data set.

Denning, S.; McGrath-Spangler, E. L.

2013-12-01

445

Enantioselective Protein-Sterol Interactions Mediate Regulation of Both Prokaryotic and Eukaryotic Inward Rectifier K+ Channels by Cholesterol  

PubMed Central

Cholesterol is the major sterol component of all mammalian cell plasma membranes and plays a critical role in cell function and growth. Previous studies have shown that cholesterol inhibits inward rectifier K+ (Kir) channels, but have not distinguished whether this is due directly to protein-sterol interactions or indirectly to changes in the physical properties of the lipid bilayer. Using purified bacterial and eukaryotic Kir channels reconstituted into liposomes of controlled lipid composition, we demonstrate by 86Rb+ influx assays that bacterial Kir channels (KirBac1.1 and KirBac3.1) and human Kir2.1 are all inhibited by cholesterol, most likely by locking the channels into prolonged closed states, whereas the enantiomer, ent-cholesterol, does not inhibit these channels. These data indicate that cholesterol regulates Kir channels through direct protein-sterol interactions likely taking advantage of an evolutionarily conserved binding pocket.

D'Avanzo, Nazzareno; Hyrc, Krzysztof; Enkvetchakul, Decha; Covey, Douglas F.; Nichols, Colin G.

2011-01-01

446

GENETIC DEFECTS IN THE HOTSPOT OF INWARDLY RECTIFYING K+ (Kir) CHANNELS AND THEIR METABOLIC CONSEQUENCES: A REVIEW  

PubMed Central

Inwardly rectifying potassium (Kir) channels are essential for maintaining normal potassium homeostasis and the resting membrane potential. As a consequence, mutations in Kir channels cause debilitating diseases ranging from cardiac failure to renal, ocular, pancreatic, and neurological abnormalities. Structurally, Kir channels consist of two trans-membrane domains, a pore-forming loop that contains the selectivity filter and two cytoplasmic polar tails. Within the cytoplasmic structure, clusters of amino acid sequences form regulatory domains that interact with cellular metabolites to control the opening and closing of the channel. In this review, we present an overview of Kir channel function and recent progress in the characterization of selected Kir channel mutations that lie in and near a C-terminal cytoplasmic ‘hotspot’ domain. The resultant molecular mechanisms by which the loss or gain of channel function leads to organ failure provide potential opportunities for targeted therapeutic interventions for this important group of channelopathies.

Pattnaik, Bikash R.; Asuma, Matti P.; Spott, Ryan; Pillers, De-Ann M.

2011-01-01

447

Role of slow delayed rectifying potassium current in dynamics of repolarization and electrical memory in swine ventricles.  

PubMed

Dynamics of repolarization, quantified as restitution and electrical memory, impact conduction stability. Relatively less is known about role of slow delayed rectifying potassium current, I Ks, in dynamics of repolarization and memory compared to the rapidly activating current I Kr. Trans-membrane potentials were recorded from right ventricular tissues from pigs during reduction (chromanol 293B) and increases in I Ks (mefenamic acid). A novel pacing protocol was used to explicitly control diastolic intervals to quantify memory. Restitution hysteresis, a consequence of memory, increased after chromanol 293B (loop thickness and area increased 27 and 38 %) and decreased after mefenamic acid (52 and 53 %). Standard and dynamic restitutions showed an increase in average slope after chromanol 293B and a decrease after mefenamic acid. Increase in slope and memory are hypothesized to have opposite effects on electrical stability; therefore, these results suggest that reduction and enhancement of I Ks likely also have offsetting components that affect stability. PMID:24682806

Jing, Linyuan; Brownson, Kathleen; Patwardhan, Abhijit

2014-05-01

448

Microrectenna: A Terahertz Antenna and Rectifier on a Chip  

NASA Technical Reports Server (NTRS)

A microrectenna that would operate at a frequency of 2.5 THz has been designed and partially fabricated. The circuit is intended to be a prototype of an extremely compact device that could be used to convert radio-beamed power to DC to drive microdevices (see Figure 1). The microrectenna (see Figure 2) circuit consists of an antenna, a diode rectifier and a DC output port. The antenna consists of a twin slot array in a conducting ground plane (denoted the antenna ground plane) over an enclosed quarter-wavelength-thick resonant cavity (denoted the reflecting ground plane). The circuit also contains a planar high-frequency low-parasitic Schottky-barrier diode, a low-impedance microstrip transmission line, capacitors, and contact beam leads. The entire 3-D circuit is fabricated monolithically from a single GaAs wafer. The resonant cavity renders the slot radiation pattern unidirectional with a half-power beam width of about 65. A unique metal mesh on the rear of the wafer forms the backplate for the cavity but allows the GaAs to be wet etched from the rear surface of the twin slot antennas and ground plane. The beam leads protrude past the edge of the chip and are used both to mount the microrectenna and to make the DC electrical connection with external circuitry. The antenna ground plane and the components on top of it are formed on a 2- m thick GaAs membrane that is grown in the initial wafer MBE (molecular beam epitaxy) process. The side walls of the antenna cavity are not metal coated and, hence, would cause some loss of power; however, the relatively high permittivity (epsilon=13) of the GaAs keeps the cavity modes well confined, without the usual surface-wave losses associated with thick dielectric substrates. The Schottky-barrier diode has the usual submicron dimensions associated with THz operation and is formed in a mesa process above the antenna ground plane. The diode is connected at the midpoint of a microstrip transmission line, which is formed on 1- m-thick SiO (permittivity of 5) laid down on top of the GaAs membrane. The twin slots are fed in phase by this structure. To prevent radio-frequency (RF) leakage past the slot antennas, low-loss capacitors are integrated into the microstrip transmission line at the edges of the slots. The DC current- carrying lines extend from the outer edges of the capacitors, widen approaching the edges of the chip, and continue past the edges of the chip to become the beam leads used in tacking down the devices. The structure provides a self-contained RF to DC converter that works in the THz range.

Siegel, Peter

2007-01-01

449

The first-principles study of oscillating rectifying performance in nanoribbon-chain-carbon nanotube junctions  

NASA Astrophysics Data System (ADS)

Electronic transport properties of armchair graphene nanoribbon and capped carbon nanotube junctions, covalently bridged by carbon atomic chains with different numbers of carbon atoms, are investigated. The first-principles calculations based on non-equilibrium Green's functions with the density-functional theory show that their I-V characteristics display odd-even effects and rectifying behaviors show obvious oscillations, namely, different bond patterns for even- and odd-numbered carbon chains affect the contact bonds, charge transfer, density of states, evolutions of molecular orbitals, and rectifying performance.

Qiu, Ming; Liew, K. M.

2013-05-01

450

Thermopower-enhanced efficiency of Si/SiGe ballistic rectifiers  

NASA Astrophysics Data System (ADS)

Injection-type ballistic rectifiers on Si/SiGe are studied with respect to the influence of gate voltage on the transfer resistance RT (output voltage divided by input current) for different positions of a local gate electrode. The rectifiers are trifurcated quantum wires with straight voltage stem and oblique current-injecting leads. Depending on the gate configuration, thermopower contributions arise from nearly pinched stem regions, which either cancel each other or impose upon the ballistic signal with same or opposite polarity. At best, this enhances RT to a maximum value of 470 ? close to threshold voltage.

Salloch, D.; Wieser, U.; Kunze, U.; Hackbarth, T.

2009-05-01

451

Transport of particles and microorganisms in microfluidic channels using rectified ac electro-osmotic flow  

PubMed Central

A new method is demonstrated to transport particles, cells, and other microorganisms using rectified ac electro-osmotic flows in open microchannels. The rectified flow is obtained by synchronous zeta potential modulation with the driving potential in the microchannel. Experiments were conducted to transport both neutral, charged particles, and microorganisms of various sizes. A maximum speed of 50 ?m?s was obtained for 8 ?m polystyrene beads, without any electrolysis, using a symmetrical square waveform driving electric field of 5 V?mm at 10 Hz and a 360 V gate potential with its polarity synchronized with the driving potential (phase lag=0°).

Wu, Wen-I; Selvaganapathy, P. Ravi; Ching, Chan Y.

2011-01-01

452

Temperature dependence of GaN high breakdown voltage diode rectifiers  

NASA Astrophysics Data System (ADS)

The temperature dependence of reverse breakdown voltage ( VRB) and forward turn-on voltage ( VF) of GaN Schottky diode rectifiers is reported. The VRB values display a negative temperature coefficient (-0.92 V K -1 for 25-50°C; -0.17 V K -1 for 50-150°C), indicative of surface- or defect-assisted breakdown. The VF values decrease with increasing temperature. The room temperature breakdown voltage is approximately a factor of three lower than the theoretical maximum expected based on avalanche breakdown, and the current performance of GaN rectifiers is comparable to that of Si at the same on-resistance.

Chyi, J.-I.; Lee, C.-M.; Chuo, C.-C.; Cao, X. A.; Dang, G. T.; Zhang, A. P.; Ren, F.; Pearton, S. J.; Chu, S. N. G.; Wilson, R. G.

2000-04-01

453

The energy consumption in a batch stripper and a batch rectifier  

Microsoft Academic Search

The energy consumption in a batch rectifier and a batch stripper was investigated with a shortcut mathematical model. The\\u000a minimum energy consumption of a batch stripper was compared to that of a batch rectifier under “general constant reflux” and\\u000a “general constant distillate composition” with the ratio of minimum energy consumption E\\u000a \\u000a S\\u000a \\/E\\u000a \\u000a R\\u000a . When the feed contains a

Xianbao Cui; Tianyang Feng; Ying Zhang; Zhicai Yang

2009-01-01

454

Recovery Act: High-Efficiency, Wideband Three-Phase Rectifiers and Adaptive Rectifier Management for Telecomm Central Office and Large Data Center Applications  

SciTech Connect

Lineage Power and Verizon teamed up to address a DOE funding opportunity focused on improving the power conversion chain in telecommunications facilities and data centers. The project had three significant elements: the design and development of high efficiency and high power three-phase rectifiers by Lineage Power, design and development of software to optimize overall plant energy efficiency by Lineage Power, and a field trial in active Verizon telecommunications facilities where energy consumption was measured before and after efficiency upgrades.

Mark A. Johnson

2012-06-29

455

IPM Motor Drive Method Using a New Inverter Having the Operation of High Power Factor Single-phase Diode Rectifier without Electrolytic Capacitor  

NASA Astrophysics Data System (ADS)

This paper proposes a new inverter drive system for an interior permanent magnet (IPM) synchronous motor and an inverter control strategy to obtain the unity power factor operation of the single-phase diode rectifier. The motor drive system for home appliances requires improving the input power factor without a reactor, an electrolytic capacitor and a switching device. This paper can achieve to improve the input power factor without a reactor, a current control-switching converter and an electrolytic capacitor. The proposed system consists of only single-phase diode rectifier, small film capacitor (10uF/kW) across the dc-bus, three-phase inverter and IPM motor. Source side energy provides directly to the motor without smoothing the dc-bus voltage. There are many ripple voltages across the dc-bus. A principle of unity-power-factor operation is that the inverter makes the waveform of input current sinusoidal. The unity power factor operation is achieved by dither effect. For IPM motor, the inverter control scheme in this paper is based on direct torque control (DTC). The proposed system is constructed by the input current controller based on DTC. The additional current controller improves its input current waveform. This paper describes that the proposed method achieves the power factor 98.8% by experimental tests.

Haga, Hitoshi; Takahashi, Isao; Ohishi, Kiyoshi

456

Three-phase series-buck rectifier with split DC-bus based on the Scott transformer  

Microsoft Academic Search

In this paper, a new unity power factor isolated three-phase buck rectifier is presented. Based on the Scott transformer, this rectifier is simple and it has the capability to obtain low output voltage. Besides, it protects against short circuit and it needs no auxiliary circuit for inrush current. Using only two active switches, it is able to generate symmetrical currents

Alceu André Badin; Ivo Barbi

2008-01-01

457

EPR line width and spin-relaxation rates of shallow and deep donors in isotopically controlled silicon  

NASA Astrophysics Data System (ADS)

The results of a numerical calculation of the contribution of ligand superhyperfine interactions to the line width for the phosphorus donor electron in silicon are reported and show linear behavior at lower concentrations compared to deep centers. The linear dependence for the phosphorus center in silicon predicts an electron spin-relaxation time for isotopically purified Si28:P longer than expected on the basis of the common square-root law. The confrontation of line width in deep-level centers with shallow states confirms that the behavior depends on the distribution of spin density around the paramagnetic center.

Guseinov, D. V.; Ezhevskii, A. A.; Ammerlaan, C. A. J.

2007-05-01

458

Composition Comprising Silicon Carbide  

NASA Technical Reports Server (NTRS)

A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy L. (Inventor)

2012-01-01

459

Semiconductor-to-metal Transition Control in Novel Vanadium Dioxide/Silicon and Vanadium Dioxide/Sapphire Epitaxial Thin Film Heterostructures for Device Applications  

NASA Astrophysics Data System (ADS)

Novel functionalities of Vanadium dioxide (VO2), such as, several orders of magnitude transition in resistivity and IR transmittance, provide an exciting opportunity for the development of next generation memory, sensor, and field-effect based devices. A critical issue in the development of practical devices based on metal oxides is the integration of high quality epitaxial oxide thin films with the existing silicon technology which is based on silicon (100) substrates. However, silicon is not suitable for epitaxial growth of oxides owing to its tendency to readily form an amorphous oxide layer or silicide at the film-substrate interface. The oxide films deposited directly on silicon exhibit poor crystallinity and are not suitable for device applications. To overcome this challenge, appropriate substrate templates must be developed for the growth of oxide thin films on silicon substrates. The primary objective of this dissertation was to develop an integration methodology of VO2 with Si (100) substrates so they could be used in "smart" sensor type of devices along with other multifunctional devices on the same silicon chip. This was achieved by using yttria-stabilized zirconia (YSZ) template layer deposited in situ. It will be shown that if the deposition conditions are controlled properly, YSZ can be grown epitaxially on silicon substrates even if the native oxide is not etched completely prior to deposition. I have used this approach to integrate VO2 thin films with Si (100) substrates using pulsed laser deposition (PLD) technique. The deposition methodology of integrating VO2 thin films on silicon using various other template layers will also be discussed. The detailed x-ray diffraction, transmission electron microscopy (TEM), electrical characterization results for the deposited films will be presented. In the framework on domain matching epitaxy, epitaxial growth of VO2 (tetragonal crystal structure at growth temperature) on both tetragonal and cubic YSZ has been explained. Our detailed phi-scan X-ray diffraction measurements corroborate our understanding of the epitaxial growth and in-plane atomic arrangements at the interface. It was observed that the transition characteristics (sharpness, over which electrical and optical property changes are completed, amplitude, transition temperature, and hysteresis) are a strong function of microstructure, strain, and stoichiometry. We have shown that by choosing the right template layer, strain in the VO2 thin films can be fully relaxed and near-bulk VO2 transition temperatures can be achieved. We have demonstrated this by using NiO as a buffer layer on Al2O3 (0001) substrate. We have also used swift heavy ion irradiation to induce controlled modifications in the semiconductor-to-metal transition characteristics of VO2 single-crystal thin films with varying ion fluences. At very high energies of ions (200 MeV), the electronic stopping (˜2009 eV/A) dominates over nuclear stopping (˜16 eV/A). Under these extreme electronic excitation conditions caused by electronic stopping and the passage of swift heavy ions through the entire thickness of the film, we expect creation of certain unique type of defects and disordered regions. Detailed characterization using X-ray diffraction, Raman spectroscopy, infra-red transmission spectroscopy, x-ray photoelectron spectroscopy (XPS), and electrical measurements were performed to investigate the characteristics and role of these defects on structural, optical, and electrical properties of VO2 thin films. XPS andelectrical resistivity measurements suggest that the ion-irradiation induces localized defect states which appear to correlate well with the creation of disordered regions in the VO2 thin films. The high energy heavy ion-irradiation changes the transition characteristics drastically from a first-order to a second-order transition (electronic -- Mott type). The low temperature conductance data for these ion-irradiated films fits well with the quasi-amorphous model for resistivity of VO2 where ion-irradiation is believed to

Gupta, Alok

460

Improving point registration in dental cephalograms by two-stage rectified point translation transform  

NASA Astrophysics Data System (ADS)

Cephalometric analysis requires to detect landmarks on cephalograms. Current registration techniques, such as that use scale-invariant feature descriptor (SIFT), perform poorly on cephalograms. We proposed to improve the registration technique for detecting the landmarks on cephalograms. The results were compared with the landmark identified by dental professionals. Twenty digital cephalograms were collected from a dental clinic. Twenty orthodontic landmarks were identified by dental professionals on each image; one of them was used as a template image. We automatically locate the landmarks using a two stages approach, the global registration of the interest points between two images and a local registration of the landmarks. In the first stage, SIFT was employed to establish point-to-point matching pairs. The matched points on the input image were treated as a set of translation transforms from the original template image. The consistence of the translation was controlled by applying a rectification factor defined in this study. In the second stage, we localized the search within the suspected regions around the landmarks derived by the translations in the first stage. Local registrations were rectified and fine-tuned until the translations close to the identified landmarks were obtained. Our method could detect all the landmarks with error distances less than the 2mm standard set forth by previous researcher. By improving the consistence of the translations, the performance of registration between two images was greatly improved. This method can be used as an initial step to locate the regions around the landmarks for improving detection in the future work.

Tam, W. K.; Lee, H. J.

2012-02-01

461

MicroRNA-26 governs profibrillatory inward-rectifier potassium current changes in atrial fibrillation  

PubMed Central

Atrial fibrillation (AF) is a highly prevalent arrhythmia with pronounced morbidity and mortality. Inward-rectifier K+ current (IK1) is believed to be an important regulator of reentrant-spiral dynamics and a major component of AF-related electrical remodeling. MicroRNA-26 (miR-26) is predicted to target the gene encoding KIR2.1, KCNJ2. We found that miR-26 was downregulated in atrial samples from AF animals and patients and this downregulation was accompanied by upregulation of IK1/KIR2.1 protein. miR-26 overexpression suppressed expression of KCNJ2/KIR2.1. In contrast, miR-26 knockdown, inhibition, or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-26 target. Knockdown of endogenous miR-26 promoted AF in mice, whereas adenovirus-mediated expression of miR-26 reduced AF vulnerability. Kcnj2-specific miR-masks eliminated miR-26–mediated reductions in Kcnj2, abolishing miR-26’s protective effects, while coinjection of a Kcnj2-specific miR-mimic prevented miR-26 knockdown-associated AF in mice. Nuclear factor of activated T cells (NFAT), a known actor in AF-associated remodeling, was found to negatively regulate miR-26 transcription. Our results demonstrate that miR-26 controls the expression of KCNJ2 and suggest that this downregulation may promote AF.

Luo, Xiaobin; Pan, Zhenwei; Shan, Hongli; Xiao, Jiening; Sun, Xuelin; Wang, Ning; Lin, Huixian; Xiao, Ling; Maguy, Ange; Qi, Xiao-Yan; Li, Yue; Gao, Xu; Dong, Deli; Zhang, Yong; Bai, Yunlong; Ai, Jing; Sun, Lihua; Lu, Hang; Luo, Xiao-Yan; Wang, Zhiguo; Lu, Yanjie; Yang, Baofeng; Nattel, Stanley

2013-01-01

462

A novel approach to gearbox condition monitoring by using drive rectifier input currents  

Microsoft Academic Search

Gearboxes are widely used and subjected to progressive deterioration which makes box condition monitoring a relevant topic in the servodrive industry. This paper proposes a novel scheme for performing integral condition monitoring in a drive containing a gearbox. The proposed scheme is based on a modified MCSA scheme (motor current signature analysis) that uses the drive rectifier input currents instead

Jesus Arellano-Padilla; Mark Sumner; Chris Gerada; Li Jing

2009-01-01

463

Simple sensorless active damping solution for three-phase PWM rectifier with LCL filter  

Microsoft Academic Search

Three-phase PWM (active) rectifiers are connected to the line power through inductance or LCL filter. LCL filter is more effective (better attenuates switching harmonics), however such solution causes stability problems. In order to assure stable operation either a damping resistor or active damping algorithm has to be used. However, extra resistor causes additional losses and active damping algorithm usually needs

Mariusz Malinowski; M. P. Kazmierkowski; Wojciech Szczygiel; Steffen Bernet

2005-01-01

464

Inhibition of G Protein-Activated Inwardly Rectifying K+ Channels by Different Classes of Antidepressants  

Microsoft Academic Search

Various antidepressants are commonly used for the treatment of depression and several other neuropsychiatric disorders. In addition to their primary effects on serotonergic or noradrenergic neurotransmitter systems, antidepressants have been shown to interact with several receptors and ion channels. However, the molecular mechanisms that underlie the effects of antidepressants have not yet been sufficiently clarified. G protein-activated inwardly rectifying K+

Toru Kobayashi; Kazuo Washiyama; Kazutaka Ikeda

2011-01-01

465

Effectiveness of different designs of 12- and 24-pulse rectifier transformers  

Microsoft Academic Search

Investigation of effectiveness of different designs of rectifier transformers of tram traction substations has covered issues such as transformer weight, rated power and efficiency and traction line voltage quality. Mathematical models have been created and time and frequency domain analysis has been run as well as power, voltage and current calculations for steady-state conditions. It is pointed out that transformer

A. Sikora; B. Kulesz

2008-01-01

466

A constant output current three-phase diode bridge rectifier employing a novel \\  

Microsoft Academic Search

This paper presents an improvement of the well-known conventional three-phase diode bridge rectifier with dc output capacitor. The proposed circuit increases the power factor (PF) at the ac input and reduces the ripple current stress on the smoothing capacitor. The basic concept is the arrangement of an active voltage source between the output of the diode bridge and the smoothing

Hans Ertl; Johann W. Kolar

2005-01-01

467

Unity power factor isolated three-phase rectifier with neutral point based on the Scott transformer  

Microsoft Academic Search

In this work, the three-phase rectifier with a new connection is presented. Based on the Scott transformer, it makes possible a neutral point voltage and it operates with unity power factor. Using only two active switches, it is able to generate symmetrical currents in the line and output voltage with balanced neutral point, which is necessary in several applications. It

A. A. Badin; I. Barbi

2006-01-01

468

PROPOSAL OF AN INTERLEAVED BOOST CONVERTER ASSOCIATED WITH A FULL-WAVE VOLTAGE DOUBLER RECTIFIER  

Microsoft Academic Search

This paper proposes the use of a voltage doubler rectifier as the output stage of an interleaved boost converter. The obtained voltage gain is twice that of traditional interleaved boost converters, but voltage stress across the switches is not increased. The resu lting topology is adequate for battery sourced systems which require low current ripple and high voltage gain e.g.

C. E. A. Silva; R. P. T. Bascopé; D. S. Oliveira Jr

469

Analysis of Inductive Coupling and Design of Rectifier Circuit for Inter-Chip Wireless Power Link  

NASA Astrophysics Data System (ADS)

A wireless power link utilizing inductive coupling is developed between stacked chips. In this paper, we discuss inductor layout optimization and rectifier circuit design. The inductive-coupling power link is analyzed using simple equivalent circuit models. On the basis of the analytic models, the inductor size is minimized for the given required power on the receiver chip. Two kinds of full-wave rectifiers are discussed and compared. Various low-power circuit design techniques for rectifiers are employed to decrease the substrate leakage current, reduce the possibility of latch-up, and improve the power transmission efficiency and the high-frequency performance of the rectifier block. Test chips are fabricated in a 0.18µm CMOS process. With a pair of 700 × 700µm2 on-chip inductors, the test chips achieve 10% peak efficiency and 36mW power transmission. Compared with the previous work the received power is 13 times larger for the same inductor size [7].

Yuan, Yuxiang; Yoshida, Yoichi; Kuroda, Tadahiro

470

Localization of PIP2 activation gate in inward rectifier K+ channels  

Microsoft Academic Search

Ion channels respond to changes in transmembrane voltage or ligand concentration by opening or closing an activation gate. In voltage-gated K+ channels, this gate has been localized to an intracellular bundle crossing. Here we examined whether this bundle crossing, or the more internal cytoplasmic pore, acts as a gate for PIP2 activation of inward rectifier K+ (Kir) channels expressed in

Jun Xiao; Xiao-guang Zhen; Jian Yang

2003-01-01

471

Current status of self rectifying air turbines for wave energy conversion  

Microsoft Academic Search

This paper reviews the present state of the art on self rectifying air turbines, which could be used for wave energy conversion. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been evaluated numerically and compared from the viewpoints of their starting and running characteristics. The types of turbine included in the

Toshiaki Setoguchi; Manabu Takao

2006-01-01

472

Effects of Serotonin on Caudal Raphe Neurons: Activation of an Inwardly Rectifying Potassium Conductance  

Microsoft Academic Search

Effects of serotonin on caudal raphe neurons: activation of an properties and that was depolarized by 5-HT. inwardly rectifying potassium conductance. J. Neurophysiol.77: 1349 - 1361, 1997. We used whole cell current- and voltage- clamp recording in neonatal rat brain stem slices to characterize firing properties and effects of serotonin ( 5-HT ) on neurons IN T R O DU

DOUGLAS A. BAYLISS; YU-WEN LI; EDMUND M. TALLEY

473

Self-Rectifying Effect in Resistive Switching Memory Using Amorphous InGaZnO  

NASA Astrophysics Data System (ADS)

Resistance random access memory (ReRAM) has received attention as next-generation memory because of its excellent operating properties and high density integration capability as a crossbar array. However, the application of the existing ReRAM as a crossbar array may lead to crosstalk between adjacent cells due to its symmetric I- V characteristics. In this study, the self-rectifying effect of contact between amorphous In-Ga-Zn-O (a-IGZO) and TaO x was examined in a Pt/a-IGZO/TaO x /Al2O3/W structure. The experimental results show not only self-rectifying behavior but also forming-free characteristics. During the deposition of a-IGZO on the TaO x , an oxygen-rich TaO x interfacial layer was formed. The rectifying effect was observed regardless of the interface formation and is believed to be associated with Schottky contact formation between a-IGZO and TaO x . The current level remained unchanged despite repeated DC sweep cycles. The low resistance state/high resistance state ratio was about 101 at a read voltage of -0.5 V, and the rectifying ratio was about 103 at ±2 V.

Lee, Jin-Woo; Kwon, Hyeon-Min; Kim, Myeong-Ho; Lee, Seung-Ryul; Kim, Young-Bae; Choi, Duck-Kyun

2014-05-01

474

Controlling the shape and gap width of silicon electrodes using local anodic oxidation and anisotropic TMAH wet etching  

Microsoft Academic Search

A simple method for fabricating silicon electrodes with various shapes and gap widths was designed using the special properties of anisotropic tetramethylammonium hydroxide (TMAH) wet etching and local anodic oxidation (LAO). A statistical system was used for the optimization of the parameters of the LAO process to facilitate a better understanding and precise analysis of the process. Analyses of the

Jalal Rouhi; Shahrom Mahmud; Sabar Derita Hutagalung; Nima Naderi; Saeid Kakooei; Mat Johar Abdullah

2012-01-01

475

Inhibition of the cardiac inward rectifier potassium currents by KB-R7943.  

PubMed

KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea) was developed as a specific inhibitor of the sarcolemmal sodium-calcium exchanger (NCX) with potential experimental and therapeutic use. However, KB-R7943 is shown to be a potent blocker of several ion currents including inward and delayed rectifier K(+) currents of cardiomyocytes. To further characterize KB-R7943 as a blocker of the cardiac inward rectifiers we compared KB-R7943 sensitivity of the background inward rectifier (IK1) and the carbacholine-induced inward rectifier (IKACh) currents in mammalian (Rattus norvegicus; rat) and fish (Carassius carassius; crucian carp) cardiac myocytes. The basal IK1 of ventricular myocytes was blocked with apparent IC50-values of 4.6×10(-6) M and 3.5×10(-6) M for rat and fish, respectively. IKACh was almost an order of magnitude more sensitive to KB-R7943 than IK1 with IC50-values of 6.2×10(-7) M for rat and 2.5×10(-7) M for fish. The fish cardiac NCX current was half-maximally blocked at the concentration of 1.9-3×10(-6) M in both forward and reversed mode of operation. Thus, the sensitivity of three cardiac currents to KB-R7943 block increases in the order IK1~INCXrectifier potassium currents, in particular IKACh, should be taken into account when interpreting the data with this inhibitor from in vivo and in vitro experiments in both mammalian and fish models. PMID:23973826

Abramochkin, Denis V; Alekseeva, Eugenia I; Vornanen, Matti

2013-09-01

476

Electrochemically oxidised porous silicon microcavities  

Microsoft Academic Search

Ageing effects in porous silicon microcavities result in emission enhancement and resonance peak blueshift. In this paper we propose electrochemical oxidation as a method to control these effects. Properties of porous silicon microcavities obtained after anodic oxidation are compared to those of microcavities aged in air for several months. This evidences that emission enhancement and resonance peak shift are two

V Mulloni; L Pavesi

2000-01-01

477

Preventing Freezeup in Silicon Ribbon Growth  

NASA Technical Reports Server (NTRS)

Carefully-shaped heat conductor helps control thermal gradients crucial to growth of single-crystal silicon sheets for solar cells. Ends of die through which silicon sheet is drawn as ribbon from molten silicon. Profiled heat extractor prevents ribbon ends from solidifying prematurely and breaking.

Mackintosh, B.

1983-01-01

478

Reversible Cycling of Silicon and Silicon Alloys  

NASA Astrophysics Data System (ADS)

Lithium ion batteries typically use a graphite negative electrode. Silicon can store more lithium than any other element and has long been considered as an attractive replacement for graphite. The theoretical lithium storage capacity of silicon is nearly ten times higher than graphite volumetrically and three times higher gravimetrically. The equilibrium Si-Li binary system is well known. Completely new phase behaviors are observed at room temperature. This includes the formation of a new phase, Li15Si4, which is the highest lithium containing phase at room temperature [1]. The formation of Li15Si4 is accompanied by a 280 percent volume expansion of silicon. During de-alloying this phase contracts, forming amorphous silicon. The volume expansion of alloys can cause intra-particle fracture and inter-particle disconnection; leading to loss of cycle life. To overcome issues with volume expansion requires a detailed knowledge of Li-Si phase behavior, careful design of the composition and nanostructure of the alloy and the microstructure of the negative electrode [2]. In this presentation the phase behavior of the Li-Si system will be described. Using this knowledge alone, strategies can be developed so that silicon can be reversibly cycled in a battery hundreds of times. Further increases in energy density and efficiency can be gained by alloying silicon with other elements, while controlling microstructure [2]. Coupled with negative electrode design strategies, practical negative electrodes for lithium ion cells can be developed based on bulk materials, with significant energy density improvement over conventional electrodes. [4pt