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1

Novel Multi-Carrier PWM Method for a Three-Phase Cascaded H-Bridge MultiLevel Inverter  

Microsoft Academic Search

A number of modulation strategies are used in multi-level power conversion applications. This paper is focused on novel multi-carrier PWM methods which have been extended for use in cascaded H-bridge multi-level inverter. Novel multi-carrier PWM method can be optimized or balanced the switch utilization in cascaded H-bridge multi-level inverter. Five-level cascaded H-bridge multi-level inverter has been simulated and controlled with

H. Keivani; M. R. Askari; F. Kavehnia; Aghdam; A. Mohammadi

2006-01-01

2

Comparison of Hard-Switched MultiLevel Inverter Topologies for STATCOM by Loss-Implemented Simulation and Cost Estimation  

Microsoft Academic Search

The voltage rating of commercial high-power IGBT modules is not sufficient for most medium-voltage applications. Therefore, three types of multi-level inverters have been proposed as a solution. They are the diode clamp multi-level inverter (DCMLI), the flying capacitor multi-level inverter (FCMLI) and the cascade cell multi-level inverter (CCMLI). In this paper, these three types of multi-level inverters are designed for

Kansuke Fujii; Ulrich Schwarzer; Rik W. De Doncker

2005-01-01

3

Application of OHSW technique in cascaded multiLevel inverter with adjustable DC sources  

Microsoft Academic Search

The Optimized Harmonic Stepped Waveform (OHSW) technique is an effective method for reduction of multi-level inverter's harmonics. This technique is very efficient for improving the quality of multi-level inverter output voltage. It is usually assumed that cascaded multi-level inverters have equal DC sources. In practice, however, this will not be happened even if the DC sources are nominally equal. In

N. Yousefpoor; S. H. Fathi; N. Farokhnia; S. H. Sadeghi

2009-01-01

4

Harmonic optimization in multi-level inverters using harmony search algorithm  

Microsoft Academic Search

This paper presents a new method to optimize harmonic stepped waveform for multi-level inverters using harmony search algorithm. The method has the benefit of high rate of convergence and precision compared to other conventional optimization methods. The proposed technique can be applied to multi-level inverters with any number of levels. The goal of optimization is to eliminate some low order

B. Majidi; H. R. Baghaee; G. B. Gharehpetian; J. Milimonfared; M. Mirsalim

2008-01-01

5

A novel structure of multi-level high voltage source inverter  

Microsoft Academic Search

This paper deals with a new multi-level high voltage source inverter with GTO thyristors. A multi-level approach seems to be best suited for implementing a high voltage conversion system because it leads to harmonic reduction and safely deals with a high power conversion system independent of the dynamic switching characteristics of each power semiconductor device. However, a conventional multi-level inverter

Young-Seek Kim; Beom-Seok Seo; Dong-Seok Hyun

1993-01-01

6

Modulation Schemes of Multi-phase Three-Level Z-Source Inverters  

Microsoft Academic Search

This paper investigates the modulation schemes of three-level multiphase Z-source inverters with either two Z-source networks or single Z-source network connected between the DC sources and inverter circuitry. With the proper offset added for achieving both desired four-leg operation and optimized harmonic performance, the proposed modulation schemes of four-leg three-level Z-source inverters can satisfy the expected buck-boost operation under unbalanced

F. Gao; P. C. Loh; F. Blaabjerg; R. Teodorescu

2007-01-01

7

Three level IGBT inverter  

Microsoft Academic Search

To extend the application of insulated gate bipolar transistor (IGBT) inverters in motor drives to higher voltages, a three-level IGBT inverter has been developed. The power circuit realized and a pulse pattern generator with space voltage modulation are described. A method to control the middle point potential is suggested. The three-level IGBT inverter can be applied to industrial drives with

Y. Tadros; S. Salama; R. Hof

1992-01-01

8

Fault recovery strategy for hybrid cascaded H-bridge multi-level inverters  

Microsoft Academic Search

In the configuration of the multilevel inverter which is used in this study, two cascaded H-bridge cells are connected in series with each phase of a three-phase three-level neutral- point clamped (NPC) inverter. The NPC inverter is fed by a single DC source; whereas, all of the cascaded H-bridge cells are supplied by capacitors. In this paper, in order to

Hossein Sepahvand; Mehdi Ferdowsi; Keith A. Corzine

2011-01-01

9

A diode-clamped multi-level inverter for the StatCom\\/BESS  

Microsoft Academic Search

Flexible AC transmission systems (FACTS) are potentially becoming more flexible and more economical local controllers in the power system. The integration of traditional FACTS devices with energy storage system (ESS) will increase FACTS device functionality. The voltage-sourced inverter is an important part of many FACTS devices, such as the StatCom and SSSC. Considerable research has been done on 2-level inverter

Ying Cheng; Mariesa L. Crow

2002-01-01

10

A novel SVPWM strategy considering DC-link balancing for a multi-level voltage source inverter  

Microsoft Academic Search

This paper proposes a novel SVPWM (space vector pulse width modulation) strategy for a multi-level voltage source inverter. This strategy is easily implemented as SPWM (sinusoidal pulse width modulation) and has the same DC-link voltage utilization as the general SVPWM scheme. The method to keep the voltage balance of the DC-link is also proposed by the analysis of DC-link voltage

Yo-Han Lee; Rae-Young Kim; Dong-Seok Hyun

1999-01-01

11

Development of multi step current source inverter  

NASA Astrophysics Data System (ADS)

Static power converter apparatus has been generally propagated with the rapid development of power semiconductor devices. Especially, CVCF and VVVF inverter have been used for induction motor drives and computer system operation without stoppage of power supply. But these inverters generate the harmonic currents and voltages. In this case the generated harmonics originate such obstacles as the burning of condenser for improving power factor, the rupture of neutral line, the torque ripple of motor in power distribution system and load equipment. The multi step method has been studied in order to suppress the harmonic obstacles of the inverter. But this method has faults such as the increment of the number of inverter and the need of phase shifting transformer (Zig-Zag, Fork connection) in order to increase above 12 steps. Therefore it is important that inverter apparatus are simple compared with the conventional one and its the effect of harmonic reduction is equal to the conventional one. Until now we have studied the multi tap changing converter for reducing the harmonics. So in this study, by using the technique of harmonic reduction in converter apparatus, we are going to develop the multi step current source inverter for reducing economically the harmonics involved in current output.

Chul-Ro, Yu

12

Developed single-phase OMTHD technique for cascaded multi-level inverter by considering adjustable DC sources  

Microsoft Academic Search

There exists an effective method for reduction of multilevel inverter's harmonics which is called the optimal minimization of the total harmonic distortion (OMTHD) technique. OMTHD technique is applied only for THD minimization with no constraint on the value of fundamental component; whereas, the primary objective in any method of inverter control is adjustment of the fundamental component to the desired

N. Yousefpoor; N. Farokhnia; S. H. Fathi; J. S. Moghani

2009-01-01

13

Control of Low-Distortion 27Level Cascade Inverter with Three H-Bridge Inverter Modules  

Microsoft Academic Search

This paper presents a digital control of 27-level cascade inverter for the applications of uninterruptible power supplies with high-power and\\/or high voltage. A conventional 27-level cascade multilevel inverter requires the combination of 13 H-bridge (single-phase full-bridge) inverter modules. A simple control of 27-level cascade inverter is proposed by using only 3 H-bridge inverter units with different dc voltage sources. The

Chih-Chiang Hua; Chun-Wei Wu; Chih-Wei Chuang

2006-01-01

14

A Grid Connected Hybrid Asymmetrical Nine level Inverter Topology Using Boost Converter  

Microsoft Academic Search

This paper presents the distributed energy re-source (DER)-based single-phase inverter is usually adopted. In order to reduce conversion losses, the key is to save costs and size by removing any kind of transformer as well as reducing the power devices. This paper deals nine-level multi-string inverter topology for DERs-based dc\\/ac conversion system. Multilevel inverter (MLI) is a new breed of

G. Ravi Srikanth; K. Achyuth Charan; A. Mowmin; Syed Baji; V. Gopi Latha

2012-01-01

15

A comparison of Z-Source three-level NPC inverter versus Z-Source two-level inverter  

Microsoft Academic Search

The Z-Source inverter enables a single stage buck-boost conversion which is a useful characteristic in battery supplied electric vehicles. However, the boost operation leads to additional losses in the semiconductors of the inverter. This paper presents a comparison of Z-Source two-level inverter and Z-Source NPC inverters with regard to their total semiconductor losses and loss distribution during boost operation. Furthermore,

Stephan Tenner; W. Hofmann

2010-01-01

16

Space vector pulse width modulation of three-level inverter extending operation into overmodulation region  

Microsoft Academic Search

Multi-level voltage-fed inverters with space vector pulse width modulation have established their importance in high power high performance industrial drive applications. The paper proposes an overmodulation strategy of space vector PWM of a three-level inverter with linear transfer characteristic that easily extends from the undermodulation strategy previously developed by the authors for neural network implementation. The overmodulation strategy is very

Subrata K. Mondal; Bimal K. Bose; Valentin Oleschuk; J. O. P. Pinto

2002-01-01

17

A four level rectifier-inverter system for drive applications  

Microsoft Academic Search

Multilevel converter technology has been receiving increased attention, especially for high power applications. In particular, three level drive systems have been extensively reported. In this paper, a four level rectifier-inverter system is investigated for drive applications. A dynamic control algorithm is described which balances the voltages on a 4 level rectifier-inverter drive system primarily from the rectifier. The proposed control

Gautam Sinha; T.A. Lipo

1996-01-01

18

Development of a scaled STATCOM prototype based on 21-level cascade H-bridge inverter  

Microsoft Academic Search

This paper is intended to present a laboratory scaled STATCOM prototype using 21-level cascade H-bridge inverter, which is developed to verify the control schemes that will be adopted in a plusmn50 MVar STATCOM project. A novel multi-pulse optimal PWM technique for STATCOM based on cascade H-bridge inverters is proposed. The harmonics are suppressed using optimization techniques. Furthermore the fundamental output

Zhichang Yuan; Qiang Song; Wenhua Liu; Yuanhua Chen; Leitan Teng

2005-01-01

19

7Level Medium Voltage Inverter System with PWM Converter for Regenerating Operation  

Microsoft Academic Search

In medium voltage drives, no standard converter topology exists to feed induction motors. So far, various topologies have been introduced to overcome limited voltage capacity of power switching devices. In market, Neutral Point Clamped(NPC) 3-level drives and H-Bridge cascaded multi-level drives are the main stream at high voltage and large capacity inverter drives. Power module, in H-Bridge cascaded multi-level topology,

Kwang-Seob Kim; Byung-Ki Kwon; Byung-Hun Yang; Chang-Ho Choi

20

Novel PWM scheme to control neutral point voltage variation in three-level voltage source inverter  

Microsoft Academic Search

This paper proposes a simple PWM scheme which alleviates the neutral point voltage fluctuation problem of the three level inverter applications. The new scheme employs modified version of well known multi-level sinusoidal pulse width modulation (SPWM) scheme. This modification shows a great potential of reducing neutral point voltage fluctuation and retained better sinusoidal shape at the output. This method avoids

K. R. M. N. Ratnayake; Y. Murai; T. Watanabe

1999-01-01

21

A four level rectifier inverter system for drive applications  

Microsoft Academic Search

In a motor drive, the converters must be able to handle bidirectional real power flow. So far, DC voltage balancing has not been satisfactorily discussed for the case when real power is drawn from the inverter. This article addresses the control issues involved in a four-level inverter based AC drive application. The DC capacitor voltages are balanced for both motoring

G. Sinha; T.A. Lipo

1998-01-01

22

Multi-Input Inverter for Grid-Connected Hybrid PV\\/Wind Power System  

Microsoft Academic Search

The objective of this paper is to propose a novel multi-input inverter for the grid-connected hybrid photovoltaic (PV)\\/wind power system in order to simplify the power system and reduce the cost. The proposed multi-input inverter consists of a buck\\/buck-boost fused multi-input dc-dc converter and a full-bridge dc-ac inverter. The output power characteristics of the PV array and the wind turbine

Yaow-Ming Chen; Yuan-Chuan Liu; Shih-Chieh Hung; Chung-Sheng Cheng

2007-01-01

23

Cascaded multi-level H-bridge drive  

US Patent & Trademark Office Database

An embodiment of the present invention comprises a multi-level PWM inverter that is constructed by cascading multi-level H-bridge inverters and providing different voltage inputs to the multi-level H-bridges. The values of the voltages, or the ratios of the voltages, are selected in order to provide an increased number of output levels. In the cascaded arrangement, at least one of the multi-level H-bridge inverters has more than three levels. Preferably, at least one of the multi-level H-bridge inverters is a 5-level inverter. According to one aspect of the invention, the cascaded arrangement may use a primary 5-level H-bridge with at least one 3-level H-bridge (referred to as a "5/3H" arrangement). This arrangement can provide up to fifteen output levels if regenerative voltage sources are used, and up to eleven output levels if a non-regenerative voltage sources are used.

2004-02-24

24

Five level GTO inverters for large induction motor drives  

Microsoft Academic Search

The use of a five-level GTO (gate turn-off thyristor) voltage sourced inverter for large induction motor drives is investigated. The advantages of such a drive are that single GTO thyristors may be used at each level, thereby avoiding the need for series connection of the thyristors. The thyristors are well protected from overvoltages by the clamping action of the DC

R. W. Menzies; P. Steimer; J. K. Steinke

1993-01-01

25

Wind energy conversion based on seven-level cascaded H-bridge inverter using LabVIEW FPGA  

Microsoft Academic Search

In this paper, an isolated wind energy conversion system (WECS) based on the cascaded H-bridge multilevel inverter (CHBMLI) topology employing a permanent magnet synchronous generator (PMSG) driven by a variable speed wind turbine and feeding high power single-phase local loads has been proposed. A seven-level cascaded H-bridge inverter employing phase-shifted multi-carrier pulse width modulation is implemented using LabVIEW FPGA. The

Paulson Samuel; Nalamati Chandrashekhar; Rajesh Gupta

2010-01-01

26

Five-level GTO inverters for large induction motor drives  

Microsoft Academic Search

The development of large induction motor drives with low torque ripple and fast dynamic response for new or retrofit applications has been limited by the device ratings and problems of series connections. This paper investigates the use of a five-level GTO voltage-sourced inverter for large induction motor drives. The advantages of such a drive are that single GTO thyristors may

R. W. Menzies; P. Steimer; J. K. Steinke

1994-01-01

27

Asymmetrical PWM Technique for a Three-Level Hybrid Inverter  

Microsoft Academic Search

Although the three-level neutral point clamped inverter is the most widely used multilevel topology, it still has some drawbacks mostly related to the balancing of the DC-link voltages across the capacitors and the unequal semiconductor stress. Many solutions devised in order to alleviate these problems rely on special symmetrical PWM modulation techniques which also increase the switching losses. This paper

Liviu Mihalache

2007-01-01

28

Research of capacitor voltage balance control method for H-bridge inverter of hybrid 9-level inverter  

Microsoft Academic Search

This paper proposes a capacitor voltage balance control method for low-voltage H-bridge inverter of hybrid 9-level inverter based on capacitor voltage imbalance predictive estimation and the injection of zero-sequence voltage. To investigate the proposed method, the charging model of capacitor voltage of H-bridge inverter is established and the inherent mechanism of capacitor voltage imbalance is analyzed in detail. The principle

Chen Yuanhua; Liu Wenhua; Yan Gangui; Song Qiang

2004-01-01

29

Topological and Modulation Design of Three-Level Z-Source Inverters  

Microsoft Academic Search

This paper presents the development of two three-level cascaded Z-source inverters, whose output voltage can be stepped down or up unlike a traditional buck three-level inverter. The proposed inverters are designed using two three-phase voltage-source inverter bridges, supplied by two uniquely designed Z-source impedance networks and cascaded at either their DC sides to form a DC-link-cascaded Z-source inverter or AC

P. C. Loh; F. Gao; F. Blaabjerg

2006-01-01

30

Control strategy for a three phase AC traction drive with three-level GTO PWM inverter  

Microsoft Academic Search

A control strategy developed for two-level inverters is applied to the three-level gate-turn-off PWM inverter. This is done by replacing the three-level inverter by two coupled two-level inverters and taking the coupling condition into account. A control strategy based on the method of direct self-control is described. Results from computer simulation for a traction motor with 1400 kW nominal power

Jiirgen K. Steinke

1988-01-01

31

Five-Level Z-Source Neutral-Point-Clamped Inverter  

Microsoft Academic Search

This paper proposes a five-level Z-source neutral-point-clamped (NPC) inverter with two Z-source networks functioning as intermediate energy storages coupled between dc sources and NPC inverter circuitry. Analyzing the operational principles of Z-source network with partial delink shoot-through scheme reveals the hidden theories in the five-level Z-source NPC inverter unlike the operational principle appeared in the general two-level Z-source inverter, so

F. Gao; P. C. Loh; F. Blaabjerg; R. Teodorescu; D. M. Vilathgamuwa

2007-01-01

32

DC voltage balancing technique using multi-pulse optimal PWM for cascade H-bridge inverters based STATCOM  

Microsoft Academic Search

A novel multi-pulse optimal PWIM technique for STATCOM based on cascade H-bridge inverters is proposed. The harmonics are suppressed using optimization techniques. Furthermore the fundamental output voltages of all the inverter cells are controlled to be equal to make all the inverter cells equally share the exchanged power with power system, which is to maintain the dc voltages as balance

Qiang Song; Wenhua Liu; Zhichang Yuan; Wenhui Wei; Yuanhua Chen

2004-01-01

33

A four-level inverter based drive with a passive front end  

Microsoft Academic Search

Multilevel inverters are suited for high power drive applications due to their increased voltage capability. Specifically, as compared to three level inverters, for a given DC bus voltage, a four-level inverter is able to synthesize better waveforms with reduced device ratings. In a medium voltage drive, a conventional diode bridge rectifier is a low cost multilevel solution if the DC

Gautam Sinha; Thomas A. Lipo

2000-01-01

34

Topological and Modulation Design of Three-Level Z-Source Inverters  

Microsoft Academic Search

This paper presents the development of two three-level cascaded Z-source inverters, whose output voltage can be stepped down or up unlike a traditional buck three-level inverter. The proposed inverters are designed using two three-phase voltage-source inverter bridges, supplied by two uniquely designed Z-source impedance networks. These three-phase bridges can either be cascaded at their dc sides to form a dc-link-cascaded

Poh Chiang Loh; Feng Gao; Frede Blaabjerg

2008-01-01

35

New Three-Level Voltage Source Inverter with Different 25 Space Voltage Vectors  

Microsoft Academic Search

This paper presents a new switching strategy controlling a new three-level voltage source inverter, resulting in different 25 space voltage-vectors. The new inverter combines some desirable features of two and three-level inverters. The proposed open-leg switching strategy intentionally opens one of the three inverter-legs per-time, in a pre-planned sequence. Thus, the number of allowed states becomes 64 compared to 27

Mohamed H. Saied; M. Z. Mostafa; T. M. Abdel-Moneim; H. A. Youse

2007-01-01

36

New three-level voltage source inverter with different 25 space voltage vectors  

Microsoft Academic Search

This paper presents a new switching strategy controlling a new three-level voltage source inverter, resulting in different 25 space voltage-vectors. The new inverter combines some desirable features of two and three-level inverters. The proposed open-leg switching strategy (OLSS) intentionally opens one of the three inverter-legs per-time, in a pre-planned sequence. Thus, the number of allowed states becomes 64 compared to

M. H. Saied; M. Z. Mostafa; T. M. Abdel-Moneim; H. A. Yousef

2006-01-01

37

New Three-Level Voltage Source Inverter with Different 25 Space Voltage Vectors  

Microsoft Academic Search

This paper presents a new switching strategy controlling a new three-level voltage source inverter, resulting in different 25 space voltage-vectors. The new inverter combines some desirable features of two and three-level inverters. The proposed open-leg switching strategy (OLSS) intentionally opens one of the three inverter-legs per-time, in a pre-planned sequence. Thus, the number of allowed switching states becomes 64 compared

Mohamed H. Saied; M. Z. Mostafa; T. M. Abdel-Moneim; H. A. Yousef

2006-01-01

38

Thermal evaluation of Space Vector PWM based four- level dual inverter fed open -end winding induction motor drive  

Microsoft Academic Search

Multilevel inverters are increasingly being used due to their superior performance compared to two-level inverters. Different circuit topologies on multilevel inverters have been extensively researched. Conduction and switching losses of IGBT in multilevel inverter is the key factor which could influence the converter reliability and efficiency. In this paper, thermal evaluation is described for four level Neutral Point Clamped inverter

B. Venugopal Reddy; V. T. Somasekhar

2011-01-01

39

A 7-level single DC source cascaded H-bridge multilevel inverters control using hybrid modulation  

Microsoft Academic Search

This paper presents a new hybrid cascaded H-bridge multilevel inverter (HCMLI) motor drive DTC control scheme for electric vehicles or hybrid electric vehicles where each phase of the inverter can be implemented using only a single DC source. Traditionally, each phase of the inverter require n DC source for 2n + 1 output voltage levels. In this paper, a scheme

F. Khoucha; A. Ales; A. Khoudiri; K. Marouani; M. E. H. Benbouzid; A. Kheloui

2010-01-01

40

Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor-Failure Conditions  

Microsoft Academic Search

This paper evaluates and proposes various compensation methods for three-level Z-source inverters under semiconductor-failure conditions. Unlike the fault-tolerant techniques used in traditional three-level inverters, where either an extra phase-leg or collective switching states are used, the proposed methods for three-level Z-source inverters simply reconfigure their relevant gating signals so as to ride-through the failed semiconductor conditions smoothly without any significant

Feng Gao; Poh Chiang Loh; Frede Blaabjerg; D. Mahinda Vilathgamuwa

2009-01-01

41

Investigation on the clamping voltage self-balancing of the three-level capacitor clamping inverter  

Microsoft Academic Search

This paper deals with the self-balancing quality of the clamping voltage in the three-level capacitor clamping inverter due to the spontaneous clamping capacitor current control loop in the circuit. Self-balancing quality of the three-level capacitor clamping inverter under sub-harmonic PWM modulation is analyzed in detail. The self-balancing mechanism in the multilevel capacitor clamping inverter (M>3) under sub-harmonic PWM modulation is

Xiaoming Yuan; Herbert Stemmler; I. Barbi

1999-01-01

42

Modeling and design of multi-loop closed loop controller for Z-source inverter for Distributed Generation  

Microsoft Academic Search

This paper presents the modelling and designing of a multi loop controller for Z-source inverters used in distributed generation systems. Z-source inverter is recently proposed converter capable of operating in buck and boost modes. Hence it is more suitable for DG applications over the other alternative converter topologies. When employing the Z-source inverter in DG applications, closed loop controlling is

C. J. Gajanayake; D. Mahinda Vilathgamuwa; Poh Chiang Loh

2006-01-01

43

High performance control of a three-level IGBT inverter fed AC drive  

Microsoft Academic Search

Three-level PWM inverters have been increasingly employed in industry and traction applications where high power and efficiency energy conversions are required. This paper presents a high performance control of a cage induction motor drive fed by a 100 hp three-level IGBT inverter operating at a low switching frequency. A practical mathematical model of the drive control system is established to

Jie Zhang

1995-01-01

44

11Level cascaded H-bridge grid-tied inverter interface with solar panels  

Microsoft Academic Search

This paper presents a single-phase 11-level (5 H-bridges) cascade multilevel DC-AC grid-tied inverter. Each inverter bridge is connected to a 200 W solar panel. OPAL-RT lab was used as the hardware in the loop (HIL) real-time control system platform where a Maximum Power Point Tracking (MPPT) algorithm was implemented based on the inverter output power to assure optimal operation of

Faete Filho; Yue Cao; Leon M. Tolbert

2010-01-01

45

Dual Z-Source Inverter With Three-Level Reduced Common-Mode Switching  

Microsoft Academic Search

This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck-boost power conversion to be performed over a wide modulation range, with three-level output waveforms

Feng Gao; Poh Chiang Loh; Frede Blaabjerg; D. Mahinda Vilathgamuwa

2007-01-01

46

Dual Z-source Inverter with Three-Level Reduced Common Mode Switching  

Microsoft Academic Search

This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck-boost power conversion to be performed over a wide modulation range with three-level output waveforms

F. Gao; P. C. Loh; F. Blaabjerg; D. M. Vilathgamuwa

2006-01-01

47

A 5-level cascaded hybrid multilevel inverter for interfacing with renewable energy resources  

Microsoft Academic Search

A 5-level cascaded hybrid multilevel inverter for interfacing with renewable energy resources is developed. The objective of this research is to propose an alternative topology of hybrid cascaded multilevel inverter applications. The modified PWM technique is also developed to reduce switching losses. Also, the proposed topology can reduce the number of required power switches compared to a traditional cascaded multilevel

Surin Khomfoi; Chatrchai Aimsaard

2009-01-01

48

Fundamental Frequency Switching Strategies of a Seven-Level Hybrid Cascaded H-Bridge Multilevel Inverter  

Microsoft Academic Search

This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require n dc sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the

Zhong Du; L eon M. Tolbert; Burak Ozpineci; John N. Chiasson

2009-01-01

49

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

Microsoft Academic Search

This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require n dc sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the

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

2009-01-01

50

Performance analysis of PWM strategies for cascaded H-bridge three-level inverter  

Microsoft Academic Search

Multilevel inverters with various pulse width modulation strategies have established their importance in high power high performance industrial applications, as they can synthesize output waveform with improved harmonic spectrum. This paper presents the performance analysis and comparison of different PWM strategies for cascaded H-bridge three-level inverter in terms of line voltage and motor current THD with their fundamental components. It

Sreenivasappa B. Veeranna; Abdul R. Beig; Udaykumar R. Yaragatti

2011-01-01

51

Loss balancing in three-level voltage source inverters applying active NPC switches  

Microsoft Academic Search

This paper investigates the use of active neutral point clamp switches in a three-level NPC voltage source inverter to balance the losses among the semiconductors. Both a control structure and algorithm are proposed which enable a substantially increased output power of the inverter and an improved performance at zero speed

T. Bruckner; S. Bemet

2001-01-01

52

SVM PWM strategy for high power 3-level inverters in variable frequency applications  

Microsoft Academic Search

A strategy for the implementation of space vector PWM in a 3-level inverter for variable frequency applications is explained in this paper. The strategy uses the nearest three vector (NTV) method and considers the switching frequency limitations of GTO thyristors used in high power inverters. Typical waveforms and harmonic analysis of the output voltage waveforms for various carrier ratios and

S. S. Kolenchery; V. C. Vaidya; M. Mangal

1996-01-01

53

3Phase Transformer Isolated Multilevel Inverter Using Common Arm  

Microsoft Academic Search

The number of transformer and the size of transformer in inverter using 3-phase transformer could be reduced compare with a multi-level inverter using single phase transformer. But still the 3-phase transformer inverter needs many switches. In this study, we proposed the isolated multi-level inverter using 3-phase transformers and common arm, in this paper. Also, using phase angle control method with

Song Jiseok; Song Dooyoung; Ju Hongju; Song Sunggun; Kim Dongok; Park Sungjun

2008-01-01

54

Three-Level Z-Source Inverters Using a Single LC Impedance Network  

Microsoft Academic Search

Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their effectiveness in achieving voltage buck-boost conversion, existing three-level Z-source inverters use two LC impedance networks and two isolated dc sources, which can significantly increase the overall system cost and require a more complex modulator for balancing the

Poh Chiang Loh; Sok Wei Lim; Feng Gao; Frede Blaabjerg

2007-01-01

55

Analysis and carrier-based modulation of Z-source NPC inverters  

Microsoft Academic Search

Multi-level neutral-point-clamped (NPC) inverters are widely used in high and medium voltage applications. However, these inverters are only buck-type converters. Recently z-source NPC inverters have been proposed as the buck-boost three-level inverter. New inverters use a z-source network as the input stage. This article analyses the features and limitations of two main topologies of z-source NPC inverters (dual z-source network

Seyed Mohammad Dehghan; Mustafa Mohamadian; Reza Gharekhani

2012-01-01

56

Research on Space Vector PWM of Five-Phase Three-Level Inverter  

Microsoft Academic Search

Aiming at five-phase permanent magnetism synchronous motor (PMSM), this paper sets up the variable-frequency variable-speed system supplied with three-level inverter and makes study about space vector PWM control algorithm of five-phase three-level inverter. In the control method of voltage space vector, the converter and machine is seen as a whole body, so it has the advantage of good control effect

Qingguo Song; Xiaofeng Zhang; Fei Yu; Chengsheng Zhang

2005-01-01

57

Generic phase shifted PWM algorithm for thirteen level cascaded H-bridge NPC inverter  

Microsoft Academic Search

The paper presents an original generic phase shifted (PS) PWM algorithm for a thirteen level cascaded H-bridge neutral point clamped inverter. According to the literature, the PSPWM was used only with cascaded 3-level H-bridges. The present algorithm could be used with any type of inverter, while the advantages of the conventional PSPWM algorithm are maintained. The generic PSPWM is applied

Raul Rabinovici; D. Baimel; J. Tomasik; A. Zuckerberger

2010-01-01

58

Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor Failure Conditions  

Microsoft Academic Search

This paper proposes various compensation methods for three-level Z-source inverters under semiconductor failure conditions. Unlike the traditional fault tolerant techniques in three-level inverter by using either an additional phase-leg or collective switching states, the proposed methods simply reconfigure the gating signals in order to tolerate the failed semiconductor devices without significantly decreasing the ac output quality and amplitude by properly

E Gaol; P. C. Loh; D. M. Vilathgamuwa; F. Blaabjerg

2007-01-01

59

Control Performance of Single-Phase STATCOM and BTB by Three-Level Inverters  

NASA Astrophysics Data System (ADS)

The so-called three level inverters have been widely used for industry applications because of high-voltage output ability and low harmonic contents. These applications are mainly suitable for ac motor drives. Nowadays, attention has been paid to larger-capacity inverters applicable to power system control. This paper describes their applications to power systems. First, harmonic analysis of a three-level inverter is achieved under the condition that its two dc capacitor voltages are unbalanced. Second, a control method for balancing the two dc capacitor voltages is described. Finally, applications of single-phase three-level inverters to STATCOM and BTB are introduced. Their control performance is confirmed by computer simulation.

Tamai, Shinzo; Akagi, Hirofumi

60

Multi-Level Item Analysis.  

ERIC Educational Resources Information Center

A new approach to item analysis, concerned not only with differences among individuals, but also differences among the groups in which the individuals may have membership, is described. This multi-level aspect may be applied to studies of differences among individuals, classes, and schools, depending upon the kind of problem being studied and the…

McLarty, Joyce R.

61

Nine level cascaded H-bridge multilevel DC-link inverter  

Microsoft Academic Search

This paper presents the nine level cascaded H-bridge multilevel inverter based on a multilevel DC link (MLDCL) and a bridge inverter to reduce the number of switches. An MLDCL can be a diode-clamped phase leg, a flying- capacitor phase leg, or cascaded half-bridge cells with each cell having its own DC source. Compared to diode clamped & flying capacitor type

N. Booma; Nagisetty Sridhar

2011-01-01

62

Three-Level Z-Source Neutral-Point-Clamped Inverter  

Microsoft Academic Search

The paper describes construction and the principles of activity, attributes and potential of 3-phase Z-type inverters. The paper focuses on the basic system and suggested 3-level system of a NPC type Z-inverter, which was elaborated by authors. Simplified theoretical analysis of both systems has been verified by detailed simulation research. In the last section of the article, the possibility to

R. Strzelecki

2006-01-01

63

Power losses analysis of two-level and three-level neutral clamped inverters for a wind pump storage system  

Microsoft Academic Search

The purpose of the paper is analyzing the possibilities of improving the efficiency of a 2 kW wind pump storage system at low wind conditions. Two possible solutions are considered for the converter supplying the induction motor pump system: two-level and respectively three-level NPC inverter. Inverter total power losses are computed based on models proposed in the paper, considering a

L. Clotea; A. Forcos; C. Marinescu; M. Georgescu

2010-01-01

64

Maximum voltage angle optimization of uninterruptible power supply on three-level transformer-less photovoltaic inverter  

Microsoft Academic Search

This paper presents a new topology of three-level transformer-less photovoltaic (PV) inverter. In this topology, a 240V AC system is developed from a full bridge inverter circuit using PIC microcontroller (PIC16F628A-I\\/P) connected to an array of PV panel through a power factor correction circuit. The output waveform of the inverter depends on the type of pulse driver. The inverter is

M. Irwanto; Y. M. Irwan; G. N. Shasidharan; A. N. Syafawati; S. P. Hadi

2012-01-01

65

High quality voltage regulation of a five-level current source inverter  

Microsoft Academic Search

This paper presents a high performance voltage regulation algorithm for a five-level current source inverter. The work combines linear voltage regulation concepts for a two level CSI, with an advanced modulation strategy that directly controls the intermediate link inductor currents of the 5-level converter. The voltage control loop is based around PI and PR stationary frame regulators, which achieve an

S. A. S. Grogan; B. P. McGrath; D. G. Holmes

2010-01-01

66

Applications of cascade multilevel inverters.  

PubMed

Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters. PMID:14566981

Peng, Fang-zen; Qian, Zhao-ming

67

Direct power control of grid connected PV systems with three level NPC inverter  

SciTech Connect

This paper presents the control of a three-level Neutral Point Clamped (NPC) voltage source inverter for grid connected photovoltaic (PV) systems. The control method used is the Extended Direct Power Control (EDPC), which is a generic approach for Direct Power Control (DPC) of multilevel inverters based on geometrical considerations. Maximum Power Point Tracking (MPPT) algorithms, that allow maximal power conversion into the grid, have been included. These methods are capable of extracting maximum power from each of the independent PV arrays connected to each DC link voltage level. The first one is a conventional MPPT which outputs DC link voltage references to EDPC. The second one is based on DPC concept. This new MPPT outputs power increment references to EDPC, thus avoiding the use of a DC link voltage regulator. The whole control system has been tested on a three-level NPC voltage source inverter connected to the grid and results confirm the validity of the method. (author)

Alonso-Martinez, Jaime; Eloy-Garcia, Joaquin; Arnaltes, Santiago [Dept. of Electrical Engineering, University Carlos III of Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain)

2010-07-15

68

Analytical Fourier Approximation of Voltage Space-Vectors in Three-Level Space-Vector Modulated Voltage Source Inverters  

Microsoft Academic Search

This paper proposes an analytical model for calculating of the harmonic spectra of a three-level voltage source inverter (VSI) with space-vector PWM (SVPWM).A three-level inverter has a large number of switching states compared to a two-level inverter and, therefore ,the SVPWM algorithm is more complex. The proposed model is based on the Laplace transform of the voltage space vectors in

Jiri Klima

2007-01-01

69

Operational analysis and modulation control of three-level Z-source inverters with enhanced output waveform quality  

Microsoft Academic Search

Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Z-source inverters are either too costly with numerous passive LC elements needed or poor in spectral quality if the \\

Poh Chiang Loh; Feng Gao; Frede Blaabjerg; Sok Wei Lim

2007-01-01

70

Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters.  

PubMed

Graphene has attracted considerable interest for future electronics, but the absence of a bandgap limits its direct applicability in transistors and logic devices. Recently, other layered materials such as molybdenum disulphide (MoS(2)) have been investigated to address this challenge. Here, we report the vertical integration of multi-heterostructures of layered materials for the fabrication of a new generation of vertical field-effect transistors (VFETs) with a room temperature on-off ratio > 10(3) and a high current density of up to 5,000 A cm(-2). An n-channel VFET is created by sandwiching few-layer MoS(2) as the semiconducting channel between a monolayer graphene sheet and a metal thin film. This approach offers a general strategy for the vertical integration of p- and n-channel transistors for high-performance logic applications. As an example, we demonstrate a complementary inverter with a larger-than-unity voltage gain by vertically stacking graphene, Bi(2)Sr(2)Co(2)O(8) (p-channel), graphene, MoS(2) (n-channel) and a metal thin film in sequence. The ability to simultaneously achieve a high on-off ratio, a high current density and a logic function in such vertically stacked multi-heterostructures can open up possibilities for three-dimensional integration in future electronics. PMID:23241535

Yu, Woo Jong; Li, Zheng; Zhou, Hailong; Chen, Yu; Wang, Yang; Huang, Yu; Duan, Xiangfeng

2012-12-16

71

Space Vector PWM modulator reducing switching losses for three-level flying-capacitor inverters  

Microsoft Academic Search

This paper presents a new Space Vector PWM Modulation (SVM) method for a three-level flying-capacitor inverter. In proposed technique switching losses are reduced by using minimal number of vectors in modulation period as well as proper selection of zero vectors. Regulation of the voltages on the flying capacitors is independent from the output voltage control. Simple algebraic equations are used

Sebastian Stynski

2010-01-01

72

A space vector PWM method for three-level flying-capacitor inverters  

Microsoft Academic Search

This paper presents a new space vector PWM method for a 3-level flying-capacitor inverter. In the proposed technique, boundary restrictions can be easily incorporated to minimize the harmonic distortion of the output voltages. Simple algebraic equations are used to calculate the pulse widths of the gate signals from the sampled reference voltages. This feature make easy the implementation in real

M. A. S. Mendes; Z. M. A. Peixoto; P. F. Seixas; P. Donoso-Garcia

2001-01-01

73

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

SciTech Connect

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

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

2009-01-01

74

A transformerless five level cascaded inverter based single phase photovoltaic system  

Microsoft Academic Search

This paper describes the current control method and the switching scheme of a cascaded five level inverter based grid connected single phase photovoltaic system. For the current control a dual polarised ramptime zero average current error control method is applied, which provides good current regulation, and a narrow ripple current frequency band. Simulation results which demonstrate the method are presented.

Martina Calais; Vassilios G. Agelidis; Lawrence J. Borle; Michael S. Dymond

2000-01-01

75

Phase gate with a four-level inverted-Y system  

SciTech Connect

The four-level atomic system in an inverted-Y configuration is investigated for large Kerr nonlinearities. The cross-Kerr nonlinearity generated in such a system can produce a phase shift of order {pi} and can be used for realizing polarization quantum phase gates.

Joshi, Amitabh; Xiao Min [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2005-12-15

76

A Series Connected Three-Level Inverter Topology For Medium Voltage Squirrel Cage Motor Drive Applications  

Microsoft Academic Search

The application of PWM voltages using two level high voltage inverters to a squirrel cage induction motor (SQIM) can cause high bearing currents, heating of rotor shaft, voltage spike across the motor terminals, etc. The increase in the number of steps of the motor voltage and hence decreasing the dv\\/dt applied to the machine terminals can be a solution to

Suvajit Mukherjee; Gautam Poddar

2008-01-01

77

An algebraic PWM method for three-level voltage source inverters  

Microsoft Academic Search

In this paper, a space vector PWM method for three-level inverters is presented. In the proposed technique, boundary restrictions can be easily incorporated to minimize the harmonic distortion output voltages, to limit the minimum pulse width and to balance the voltages of the DC-link capacitor bank. The solutions obtained are simple algebraic equations relating directly the pulse widths of the

P. F. Seixas; M. A. Severo Mendes; P. Donoso-Garcia; A. M. N. Lima

2000-01-01

78

A novel PWM scheme for a three-level voltage source inverter with GTO thyristors  

Microsoft Academic Search

This paper presents a new PWM method for the three-level GTO inverters based on the space voltage vectors. With the proposed PWM method, we can minimize the harmonic components of the output voltage by avoiding the minimum pulse width limitation problem of the GTO thyristors and keeping the voltage balancing of the DC-link capacitors. The principle of the proposed PWM

Yo-Han Lee; Bum-Seok Suh; Dong-Seok Hyun

1996-01-01

79

Topological Design and Modulation Strategy for Buck–Boost Three-Level Inverters  

Microsoft Academic Search

To date, designed topologies for DC-AC inversion with both voltage buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable buck-boost three-level inverters that can also support bidirectional power conversion. The proposed front-end circuitry is developed

Feng Gao; Poh Chiang Loh; Remus Teodorescu; Frede Blaabjerg; D. Mahinda Vilathgamuwa

2009-01-01

80

Analysis and controller design of static VAr compensator using three-level GTO inverter  

Microsoft Academic Search

A static VAr compensator (SVC) using a three-level GTO voltage source inverter (VSI) is presented for high-voltage, high-power applications. The three-level VSI has lower harmonic components and higher DC-link voltage than the two-level VSI and thus can be operated at lower switching frequency (fsw<500 Hz) without excessive harmonic contents. From the DQ-transformed equivalent circuit of the presented SVC system, DC

Guk C. Cho; Gu H. Jung; Nam S. Choi; Gyu H. Cho

1996-01-01

81

A novel double hysteresis-band current control for a three-level voltage source inverter  

Microsoft Academic Search

This paper presents a new current control strategy for a high power three-level voltage source inverter (VSI). This control strategy consists on an extension to a three-level topology of the well-known hysteresis-band current control for a conventional two-level VSI. Line current is controlled by means of two hysteresis bands slightly displaced around the reference value. A simple calculation block decides

M. Lafoz; I. J. Iglesias; C. Veganzones; M. Visiers

2000-01-01

82

An improved DTC strategy for induction motor control fed by a multi-cell voltage source inverter for high power applications  

Microsoft Academic Search

Voltage-source inverters are generally composed of only one switching cell per phase. The classical direct torque control (DTC) technique for this kind of inverter has well known advantages, but may not be used in high power systems due to the high frequency that this technique typically requires. The present work deals with the use of a multi-cell voltage-source inverter controlled

C. A. Martins; T. A. Meynard; X. Roboam; A. S. Carvalho

1998-01-01

83

Control design of three-level voltage source inverter for SMES power conditioning system  

Microsoft Academic Search

This paper describes the control design of the power processing system for superconductive magnetic energy storage (SMES). The proposed SMES power-processing system consists of series connection of a three-level voltage source inverter and a three-level chopper. The control design enables stable high-bandwidth control of power transfer to and from the SMES coil. The issues of series connection of power converters

Nikola Celanovic; Dong-Ho Lee; Dengming Peng; Dusan Borojevic; Fred C. Lee

1999-01-01

84

Ecological effects in multi-level studies  

Microsoft Academic Search

Multi-level research that attempts to describe ecological effects in themselves (for example, the effect on individual health from living in deprived communities), while also including individual level effects (for example, the effect of personal socioeconomic disadvantage), is now prominent in research on the socioeconomic determinants of health and disease. Such research often involves the application of advanced statistical multi-level methods.

Tony A Blakely; Alistair J Woodward

2000-01-01

85

Static Var Compensator and Active Power Filter With Power Injection Capability, Using 27Level Inverters and Photovoltaic Cells  

Microsoft Academic Search

An active power filter and static var compensator with active power generation capability has been implemented using a 27-level inverter. Each phase of this inverter is composed of three ldquoHrdquo bridges, all of them connected to the same dc link and their outputs connected through output transformers scaled in the power of three. The filter can compensate load currents with

Patricio Flores; Juan Dixon; Micah Ortúzar; Rodrigo Carmi; Pablo Barriuso; Luis Moran

2009-01-01

86

Effect of gate pulse variation on the performance of fifteen-level cascaded H-bridge voltage source inverter  

Microsoft Academic Search

This paper proposes a fifteen level H- Bridge cascaded multilevel inverter with fundamental frequency switching for low power applications such as solar powered power supplies, battery powered standby power supplies. The effect of the variation of gate pulse on the performance of the inverter for different conditions of gate pulse variation is studied and simulation results are presented. Experimental implementation

Tuka Al-Hanai; Thuraya Al-Hanaei; Sreenivasappa B. Veeranna; Abdul R. Beig

2011-01-01

87

PWM control of a 5-level single-phase current-source inverter with controlled intermediate DC-link current  

Microsoft Academic Search

Multilevel converters offer benefits of reduced harmonics and increased power ratings compared to their two level counterparts, but to date most of the research in this area has been directed towards voltage source inverters rather than current source inverters. Partly, this is because DC link capacitors are a more effective energy storage medium than link inductors, with less losses and

Jianyu Bao; D. G. Holmes; Zhihong Bai; Zhongchao Zhang; Dehong Xu

2006-01-01

88

Direct Torque Control with 5-level cascaded H-bridge multilevel inverter for induction machines  

Microsoft Academic Search

This paper presents a Direct Torque Control (DTC) utilizing a 5-level cascaded H-bridge multilevel inverter (CHMI) for induction machines. A multilevel hysteresis controller for flux and torque, with 12-sector stator flux angle detection and a precise look-up table for optimum vector selection is proposed to enhance DTC performances. A theoretical concept of the proposed DTC system in terms of flux

N. M. Nordin; N. R. N. Idris; N. A. Azli

2011-01-01

89

Switching frequency optimal PWM control of a three-level inverter  

Microsoft Academic Search

A pulse-width-modulation (PWM) method for the control of a three-level inverter is described. The switching frequency optimal-PWM method (SFO-PWM) works with a constant carrier frequency not synchronized with fundamental stator frequency. SFO-PWM gives an optimal utilization of the mean thyristor switching frequency permitted; therefore, PWM carrier frequency may be chosen to a value of two times the permitted mean thyristor

Jurgen K. Steinke

1992-01-01

90

Modeling, analysis and control of static VAr compensator using three-level inverter  

Microsoft Academic Search

A novel static VAr compensator (SVC) system using a three-level inverter is proposed for high-voltage and high-power applications. A general and simple model for the overall system is obtained using the circuit DQ-transform, and DC and AC analyses are performed to characterize the open-loop system. Using the proposed model, a novel control method which controls both the phase angle and

G. C. Cho; N. S. Choi; C. T. Rim; G. H. Cho

1992-01-01

91

An active power filter implemented with a three-level NPC voltage-source inverter  

Microsoft Academic Search

This paper presents an active power filter implemented using a three-level neutral point-clamped voltage-source inverter. The active power filter can compensate current harmonics and reactive power in medium voltage distribution systems. The paper presents the principles of operation and design criteria for both the power and control circuits. Finally, the viability of the proposed scheme is shown with computer simulation

Victor Aburto; M. Schneider; L. Moran; Juan Dixon

1997-01-01

92

Sine-triangle vs. space vector modulation for three-level PWM voltage source inverters  

Microsoft Academic Search

This paper studies the inherent relations between sine-triangle and space vector PWM schemes for three-level voltage source inverters. It is shown that the two schemes can function equivalently through proper selection of common mode injections in the case of sine-triangle modulation, or dwell times in equivalent redundant switching states in the case of space vector modulation. Simulation and measurement results

F. Wang

2000-01-01

93

Zero-voltage switching for three-level capacitor clamping inverter  

Microsoft Academic Search

A zero-voltage switching (ZVS) scheme for a three-level capacitor clamping inverter based on the true pulsewidth modulation (PWM) pole is proposed in this paper. With this scheme, the main switches work with ZVS through the assistance of a small rating zero current switching (ZCS) lossless auxiliary circuitry without imposing any voltage\\/current spikes on the main devices or any extra control

Xiaoming Yuan; Ivo Barbi

1999-01-01

94

The comparative analysis of multicarrier control techniques for SPWM controlled cascaded H-bridge multilevel inverter  

Microsoft Academic Search

This paper presents a cascaded H-bridge multilevel inverter that can be implemented using symmetrical topology. A multilevel inverter is a power electronic device built to synthesize a desired AC voltage from several levels of DC voltages. Multi level inverters have been an important development in recent years. Owning the capability to increase the power quality delivered to the load for

F. T. Josh; Jovitha Jerome; Arul Wilson

2011-01-01

95

Multi-modality multi-interface level measurement  

NASA Astrophysics Data System (ADS)

Crude oil separation is an important process in the oil industry. To make use of the separators efficiently, it is important to know their internal behaviour, and to measure the levels of multi-interfaces between different materials, such as gas-foam, foam-oil, oil-emulsion, emulsion-water and water-solids. A multi-modality multi-interface level instrument is presented, which is based on capacitance and electromagnetic measurements. Some key issues have been addressed, including the effect of salt content on measurement.

Hwili, A.; Yang, W.

2007-07-01

96

Operational Analysis and Modulation Control of Three-Level Z-Source Inverters With Enhanced Output Waveform Quality  

Microsoft Academic Search

Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Z-source inverters are either too costly with numerous passive LC elements needed or poor in spectral quality if the ldquoreduced element countrdquo (REC) variant is used. Instead of being constrained by the

Poh Chiang Loh; Feng Gao; Frede Blaabjerg; Sok Wei Lim

2009-01-01

97

Harmonic elimination control of a five-level DC-AC cascaded H-bridge hybrid inverter  

Microsoft Academic Search

A five-level hybrid cascaded inverter operating under selective harmonic elimination (SHE) pulse-width modulation (PWM) control is discussed in this paper. The topology is a cascaded connection of a conventional three-phase, two-level inverter and an H-bridge module for each phase with a single DC-source. The topology boosts the output voltage within limits and with no additional DC-DC converters. However, such boosting

Georgios S. Konstantinou; Sridhar R. Pulikanti; Vassilios G. Agelidis

2010-01-01

98

A Five-Level Cascade Multilevel Inverter Three-Phase Motor Drive Using a Single DC Source  

SciTech Connect

A method is presented showing that a 5-level cascade multilevel inverter for a three-phase permanent magnet sychronous motor drive can be implemented using only a single DC link to supply a standard 3-leg inverter along with three full H-bridges supplied by capacitors. It is shown that the capacitor voltages can be regulated while achieving an output voltage waveform that is 20% greater than that obained using the standard 3-leg inverter alone. Finally conditions are given in terms of the power factor and modulation index that determine when the capacitor voltage can regulated.

Chiasson, J. N. [University of Tennessee, Knoxville (UTK)

2006-10-01

99

MultiLevel Security Requirements for Hypervisors  

Microsoft Academic Search

Using hypervisors or virtual machine monitors for security has become very popular in recent years, and a number of proposals have been made for supporting multi-level security on secure hypervisors, including PR\\/SM, NetTop, sHype, and others. This paper looks at the requirements that users of MLS systems will have and discusses their implications on the design of multi-level secure hypervisors.

Paul A. Karger

2005-01-01

100

Fault Detection and Reconfiguration Technique for Cascaded H-bridge 11-level Inverter Drives Operating under Faulty Condition  

Microsoft Academic Search

A fault detection and reconfiguration technique for a cascaded H-bridge 11-level inverter drives during faulty condition is proposed in this paper. The ability of cascaded H-bridge multilevel inverter drives (MLID) to operate under faulty condition is also discussed. Output phase voltages of a MLID can be used as a diagnostic signal to detect faults and their locations. Al-based techniques are

S. Khomfoi; L. M. Tolbert

2007-01-01

101

New medium voltage drive systems using three-level neutral point clamped inverter with high voltage IGBT  

Microsoft Academic Search

This paper presents a new range of medium voltage motor drives with a three-level neutral point clamped inverter using high-voltage IGBTs. Different line side converters are available, including a twelve pulse diode rectifier and an active front end converter in the same configuration as the inverter. Innovative features of the drive include series-connection of high-voltage IGBTs and a novel isolated

R. Sommer; A. Mertens; M. Griggs; H.-J. Conraths; M. Bruckmann; T. Greif

1999-01-01

102

Development and Experimental Testing of a 3o Resolution-Level Controlled WM Inverter-Fed Induction Motor  

Microsoft Academic Search

This paper presents a novel speed control approach for inverter-fed three-phase (3Phi) induction motors. The proposed approach is called the resolution-level controller (RLC) that is realized for the 3Phi voltage-source (VS) wavelet-modulated (WM) inverters. The wavelet modulation technique generates switching pulses using a non-dyadic type multiresolution analysis (MRA) that is constructed by three scale-based linearly-combined scaling functions shifted by 2pi\\/3

S. A. Saleh; M. A. Rahman

2007-01-01

103

Analysis of DC-Link capacitor losses in three-level neutral point clamped and cascaded H-Bridge voltage source inverters  

Microsoft Academic Search

Loss estimation is a critical aspect of inverter design. The present work investigates the losses occurring in the DC-link capacitors of the three-phase three-level Neutral Point Clamped and Cascaded H-Bridge inverter topologies, by performing a harmonic analysis of the capacitor currents. Results are verified by simulations. Their analysis reveals the advantage of the NPC inverter.

Georgios I. Orfanoudakis; Suleiman M. Sharkh; Michael A. Yuratich

2010-01-01

104

Design of Parallel Inverters for Smooth Mode Transfer Microgrid Applications  

Microsoft Academic Search

In this paper, smooth mode transfers and accurate current sharing are performed in a multi-inverter-based microgrid system by the designed system level controls with control area network communication. Controllers of individual inverters within the microgrid in both grid-tie and islanding modes are also designed to ensure high-quality output waveforms. The mode transfer tests are conducted with an inverter-simulated grid to

Chien-Liang Chen; Yubin Wang; Yuang-Shung Lee; Daniel Martin

2010-01-01

105

How to Invert Multi-Band, Regional Phase Amplitudes for 2-D Attenuation and Source Parameters: Tests Using the USArray  

NASA Astrophysics Data System (ADS)

We inverted for laterally varying attenuation, absolute site terms, moments and apparent stress using over 460,000 Lg amplitudes recorded by the USArray for frequencies between 0.5 and 16 Hz. Corner frequencies of Wells, Nevada, aftershocks, obtained by independent analysis of coda spectral ratios, controlled the tradeoff between attenuation and stress, while independently determined moments from St. Louis University and the University of California constrained absolute levels. The quality factor, Q, was low for coastal regions and interior volcanic and tectonic areas, and high for stable regions such as the Great Plains, and Colorado and Columbia Plateaus. Q increased with frequency, and the rate of increase correlated inversely with 1-Hz Q, with highest rates in low-Q tectonic regions, and lowest rates in high-Q stable areas. Moments matched independently determined moments with a scatter of 0.2 NM. Apparent stress ranged from below 0.01 to above 1 MPa, with means of 0.1 MPa for smaller events, and 0.3 MPa for larger events. Stress was observed to be spatially coherent in some areas; for example, stress was lower along the San Andreas fault through central and northern California, and higher in the Walker Lane, and for isolated sequences such as Wells. Variance reduction relative to 1-D models ranged from 50 to 90 % depending on band and inversion method. Parameterizing frequency dependent Q as a power law produced little misfit relative to a collection of independent, multi-band Q models, and performed better than the omega-square source parameterization in that sense. Amplitude residuals showed modest, but regionally coherent patterns that varied from event to event, even between those with similar source mechanisms, indicating a combination of focal mechanism, and near source propagation effects played a role. An exception was the Wells mainshock, which produced dramatic amplitude patterns due to its directivity, and was thus excluded from the inversions. The 2-D Q plus absolute site models can be used for high accuracy, broad area source spectra, magnitude and yield estimation, and, in combination with models for all regional phases, can be used to improve discrimination, in particular for intermediate bands that allow coverage to be extended beyond that available for high frequency P-to-S discriminants.

Phillips, W. Scott; Mayeda, Kevin M.; Malagnini, Luca

2013-08-01

106

Comparison of Cascaded H-Bridge, Neutral Point Clamped and Flying Capacitor multilevel inverters using multicarrier PWM  

Microsoft Academic Search

Multilevel Inverters are becoming popular for their high voltage operating capability for high power applications. This paper presents a comparative study of Cascaded H-Bridge, Neutral Point Clamped and Flying Capacitor multilevel voltage source inverters. These five-level inverters are simulated in MATLAB\\/ Simulink using multi carrier sine pulse width modulation. FFT analyses of output voltages for an RL load is carried

T. Porselvi; Ranganath Muthu

2011-01-01

107

What is Multi–level Modelling For?  

Microsoft Academic Search

This paper is intended to be a consideration of the role of multi–level modelling in educational research. It is not a guide on how to design or perform such an analysis. There are several references in the text to sources that teach the practicalities perfectly well, and the technique is anyway similar to other forms of regression and to analysis

Stephen Gorard

2003-01-01

108

Switch-Off Behaviour of 6.5 kV IGBT Modules in Two-Level Voltage Source Inverter  

NASA Astrophysics Data System (ADS)

This paper presents an analysis of the switch-off process of 6.5 kV/200 A IGBT modules in a two-level half-bridge voltage source inverter. During experiments, it was stated that real switching process is far from ideal switch-off since parasitic inductance and capacitance in the circuit cause voltage spikes and high frequency oscillations during transition processes. Operation states of the inverter are described and analyzed. Experimental and simulation results are compared, the main transients are analyzed and mathematically expressed and possible problems and solutions are discussed.

Blinov, Andrei; Jalakas, Tanel; Vinnikov, Dmitri; Janson, Kuno

2010-01-01

109

Multilevel cascade voltage source inverter with seperate DC sources  

DOEpatents

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Peng, Fang Zheng (Knoxville, TN); Lai, Jih-Sheng (Blacksburg, VA)

2002-01-01

110

Multilevel cascade voltage source inverter with seperate DC sources  

DOEpatents

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Peng, Fang Zheng (Oak Ridge, TN); Lai, Jih-Sheng (Knoxville, TN)

1997-01-01

111

Multilevel cascade voltage source inverter with separate DC sources  

DOEpatents

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations. 15 figs.

Peng, F.Z.; Lai, J.S.

1997-06-24

112

A novel PWM scheme to eliminate common-mode voltage in three-level voltage source inverter  

Microsoft Academic Search

This paper proposes a simple PWM scheme which alleviates the common mode voltage problems of the three level inverter applications. The new scheme uses only seven voltage vectors. In addition, this method avoids the occurrence of narrow PWM pulses and gives the advantage of less complex control circuitry. Moreover the new PWM scheme shows a great potential of reducing common-mode

K. R. M. N. Ratnayake; Y. Murai

1998-01-01

113

Ecological effects in multi-level studies  

PubMed Central

Multi-level research that attempts to describe ecological effects in themselves (for example, the effect on individual health from living in deprived communities), while also including individual level effects (for example, the effect of personal socioeconomic disadvantage), is now prominent in research on the socioeconomic determinants of health and disease. Such research often involves the application of advanced statistical multi-level methods. It is hypothesised that such research is at risk of reaching beyond an epidemiological understanding of what constitutes an ecological effect, and what sources of error may be influencing any observed ecological effect. This paper aims to present such an epidemiological understanding. Three basic types of ecological effect are described: a direct cross level effect (for example, living in a deprived community directly affects individual personal health), cross level effect modification (for example, living in a deprived community modifies the effect of individual socioeconomic status on individual health), and an indirect cross level effect (for example, living in a deprived community increases the risk of smoking, which in turn affects individual health). Sources of error and weaknesses in study design that may affect estimates of ecological effects include: a lack of variation in the ecological exposure (and health outcome) in the available data; not allowing for intraclass correlation; selection bias; confounding at both the ecological and individual level; misclassification of variables; misclassification of units of analysis and assignment of individuals to those units; model mis-specification; and multicollinearity. Identification of ecological effects requires the minimisation of these sources of error, and a study design that captures sufficient variation in the ecological exposure of interest.???Keywords: multi-level methods; ecological research design; socioeconomic factors; confounding; bias; effect modifiers; causality

Blakely, T.; Woodward, A.

2000-01-01

114

High-frequency induction heating inverter with multi-resonant mode using newly developed normally-off type static induction transistor  

Microsoft Academic Search

This paper is mainly concerned with the state-of-the-art developments of the voltage-fed voltage-clamped type half-bridge topology of a new instantaneous resonant current vector-regulated high-frequency inverter, which efficiently operates at zero-current soft-switched quasi-resonant and load resonant tank circuit sub-resonant hybrid soft-switching schemes. This proposed multi-resonant inverter version using newly-developed high-frequency high-power normally-off type bipolar mode static induction transistors (B-SITs) is more

H. Ogiwara; M. Hayakawa; T. Nishimura; M. Nakaoka

1993-01-01

115

Conditions for Capacitor Voltage Regulation in a Five-Level Cascade Multilevel Inverter: Application to Voltage-Boost in a PM Drive  

Microsoft Academic Search

A cascade multilevel inverter is a power electronic device built to synthesize a desired AC voltage from several levels of DC voltages. Such inverters have been the subject of research in the last several years, where the DC levels were considered to be identical in that all of them were either batteries, solar cells, etc. Similar to previous results in

John Chiasson; Burak Özpineci; Zhong Du; Leon M. Tolbert

2007-01-01

116

Flexible PWM control of three-level inverters for fuel cell\\/battery supplied aeromobile drive  

Microsoft Academic Search

New method of synchronized pulsewidth modulation (PWM) has been disseminated for control of dual neutral-point-clamped inverters feeding asymmetrical dual three-phase (six-phase) motor drive with two DC voltage sources. A novel control strategy for this drive topology is based on variation of switching frequencies of each inverter depending on the magnitudes of voltages of the corresponding DC sources. Specialized control scheme

Giovanni Griva; Valentin Oleschuk

2009-01-01

117

Synchronous balanced control of cascaded two-level inverters with separated DC sources  

Microsoft Academic Search

The paper presents results of dissemination of novel method of synchronized pulsewidth modulation (PWM) for wide-range control of dual inverter-fed motor drives with power balancing capability between dc-links. This drive topology includes two insulated dc sources (with equal or different voltages), feeding two standard three-phase inverters, connected with an open-end winding induction motor. Algorithms of synchronized PWM provide both continuous

Valentin Oleschuk; Francesco Profumo

2007-01-01

118

Multi-level logic array synthesis  

SciTech Connect

Automatic synthesis of VLSI circuits from function descriptions creates the opportunity for vastly reduced design cost, but presents formidable challenges. This silicon compilation can be accomplished by a four step translation: (1) writing the function in terms of available logic components, (2) minimization of this logic representation, (3) mapping of logic into the target technology's circuit primitives, and (4) selection of a detailed layout configuration. Existing methods based on programmable logic array (PLA), standard cell and gate array topologies attack the problem using restrictions on logic minimization or circuit topology. A new method based on multilevel logic and Weinberger arrays integrates the entire compilation from functional description to layout generation, and provides greater flexibility in logic minimization, circuit topology, and design goals. Multi-level and Weinberger arrays serve as ideal partners in synthesis of large circuit structures. Deeply nested logic expressions can save area, power, and circuit delay compared to their more common sum-of-products equivalents, and Weinberger arrays can directly implement the arbitrary interconnections required by these complex logic functions. The Stanford Weinberger Array Minimizer and Implementor (SWAMI) system explores two phases of this compilation with special care, heuristic minimization of multi-level logic expressions, and gate placement in Weinberger arrays. SWAMI's logical optimization phase adopts heuristic methods to reduce the circuit area and delay for each logic function.

Rowen, C.

1985-01-01

119

Control Scheme of Three-Level NPC Inverter for Integration of Renewable Energy Resources Into AC Grid  

Microsoft Academic Search

This paper presents a multiobjective control scheme based on the dynamic model of three-level, neutral-point-clamped voltage source inverter for integration of distributed generation (DG) resources based on renewable energy resources to the distribution grid. The proposed model has been derived from the abc\\/${\\\\alpha\\\\beta}$ and ${\\\\alpha\\\\beta}$\\/dq transformation of the AC system variables. The proposed control technique generates the compensation current references

Edris Pouresmaeil; Daniel Montesinos-Miracle; Oriol Gomis-Bellmunt

2012-01-01

120

Analysis and Development of a Resolution-Level Vector-Controlled WM Inverter-Fed IPM Motor Drive  

Microsoft Academic Search

This paper presents the development, the analysis and the implementation of a resolution-level vector- controlled wavelet-modulated (WM) inverter-fed interior permanent magnet (IPM) motor drive. The proposed controller is based on mapping the changes of the quadrature axis component iq of the line currents to a phase-shift angle thetas, while maintaining the direct axis component id constant. The phase-shift thetas is

S. A. Saleh; M. A. Rahman

2008-01-01

121

Development and Experimental Validation of Resolution-Level Controlled Wavelet-Modulated Inverters for Three-Phase Induction Motor Drives  

Microsoft Academic Search

This paper presents the development, implementa- tion, and performances of a resolution-level vector controller (RLVC) for three-phase induction motor (IM) drive systems. The RLVC is structured to adjust the output voltages of a three-phase voltage-source wavelet-modulated inverter which is used to supply a three-phase IM. The objectives of the RLVC are established by controlling the quadrature axis component of the

S. A. Saleh; M. Azizur Rahman

2011-01-01

122

Sine-triangle versus space-vector modulation for three-level PWM voltage-source inverters  

Microsoft Academic Search

This paper studies the inherent relations between sine-triangle and space-vector pulsewidth modulation schemes for three-level voltage-source inverters. It is shown that the two schemes can function equivalently through proper selection of common-mode injections in the case of sine-triangle modulation, or dwell times in equivalent redundant switching states in the case of space-vector modulation. Simulation and measurement results illustrate that understanding

Fei Wang

2002-01-01

123

A state-space model for the comprehensive dynamic analysis of three-level voltage-source inverters  

Microsoft Academic Search

A new and comprehensive model of the three-level voltage-source inverter is presented. The dynamics of the complete system is considered, including the DC-link side and the load side. This model is a tool for a full control of the system. The model uses the D-Q transformation. Steady-state and small-signal analysis are obtained and the simulation results are given

J. Bordonau; M. Cosan; D. Borojevic; H. Mao; F. C. Lee

1997-01-01

124

Modeling and analysis of cascaded H-bridge inverter for wind driven isolated squirrel cage induction generators  

Microsoft Academic Search

This paper describes the simulation model and the harmonics analysis of cascaded five level H-bridge inverters fed RL load and induction motor load system for stand alone applications. The SEIG fed H- bridge multi level inverter (MLI) for variable speed wind energy conversion systems are considered for various stand alone applications. In this paper, the SEIG fed cascaded five level

M. Sasikumar; R. Madhusudhanan; S. ChenthurPandian

2010-01-01

125

A new multi-slot and multi-level coding technique for high capacity communication system  

Microsoft Academic Search

A new multi-slot and multi-level coding technique for high capacity communication system, known as Multi Slot Amplitude Coding (MSAC) is presented. This technique offers better flexibility in terms of defining the symbol based on time slot and signal level in order to generate more unique symbols as a line code with better clock information since all the symbols have zero

R. Talib; M. F. L. Abdullah; A. Malekmohammadi; M. K. Abdullah

2010-01-01

126

Ultra-short pulse propagation in multi-level media  

NASA Astrophysics Data System (ADS)

We consider the propagation of short, intense laser pulses through media consisting of two-level and three-level atoms. We derive the coupled Maxwell-Bloch (MB) equations, which describe such propagation. Many different physical situations have been studied by analyzing various limiting cases of these equations. Most of the recent work has relied on steady-state or adiabatic assumptions to simplify the analysis of the MB equations. However rapid progress has been made in recent years in developing analytic solution techniques that do not require these simplifications, such as BAcklund transformations, inverse scattering methods, and Darboux transformations. We use the Backlund solution method, to derive soliton solutions to the MB equations for various physical situations of interest in multi-level media. In addition we examine the experimental applicability of the exact solutions by numerically integrating the MB equations for more physically realistic pulse shapes and media preparations that may not permit analytic solutions. In two-level inverted gain media, we derive a pulse solution with group velocity exceeding the speed of light in vacuum (fast light). Numerical results confirm that such a pulse can exhibit fractional peak advances exceeding one pulse width despite spontaneous instabilites such as superfluorescence and stimulated instabilities related to the McCall-Hahn area theorem. In three-level ? type media we derive soliton solutions for two pulses propagating through a medium prepared in an arbitrary mixed-state of the two ground states. We include a tunable parameter in the solutions that allows one to vary the medium between completely mixed state and completely pure-state superpositions known as "phaseonium". This flexibility allows one to study the interplay between stimulated Raman scattering, electromagnetically induced transparency (EIT), self induced transparency (SIT), and pulse matching. Past results have indicated that asymptotic pulse propagation is always dominated by EIT type propagation when considering two-pulse propagation in phaseonium. Our results indicate that only for pure-state phaseonium does EIT behavior dominate. When one considers mixed state superpositions of the two ground states, termed "mixonium," asymptotic EIT dominance is replaced with SIT behavior. We show how the area theorem of self-induced transparency appears to govern propagation in both the two and three-level cases.

Clader, B. David

127

Investigation of a high-power three-level quasi-resonant DC-link voltage-source inverter  

Microsoft Academic Search

This paper investigates the feasibility of a quasi-resonant DC-link soft-switching principle for voltage-source inverters (VSIs) in the megawatt power range. An evaluation of a three-level quasi-resonant DC-link VSI (3L-QRDCWSI) featuring integrated gate-commutated thyristors (IGCTs) and a comparison-to a commercially available three-level IGCT-VSI is presented. Extensive loss measurements of IGCTs under hard- and soft-switching conditions are the basis for the design

Thomas Brückner; Steffen Bernet

2001-01-01

128

On the continuous invertibility and the Fredholm property of differential operators with multi-valued impulse effects  

NASA Astrophysics Data System (ADS)

We obtain necessary and sufficient conditions for the continuous invertibility and the Fredholm property of operators generated by a family of evolution operators, with boundary conditions given by a linear relation and impulse effects also given by a linear relation.

Didenko, Vladimir B.

2013-02-01

129

An advanced static var compensator based on a three level IGBT inverter modelling analysis and active power filtering  

NASA Astrophysics Data System (ADS)

This paper presents the dynamic performance analysis of an Advanced Static Var Compensator (ASVC) using three-level neutral point-clamped voltage source inverter. The paper presents the principles of operating and the method of reference currents generation. The dynamic behaviour of the system is further analysed using Matlab/Simulink with SimPower Systems toolbox through a set of simulation tests. The results obtained have been applied to an active power filter which might lead to the design of a robust controller for current harmonics and reactive power applications

Draou, Azeddine

2012-12-01

130

A novel dc-link voltage regulation method for single source hybrid multilevel inverters  

Microsoft Academic Search

This paper presents a novel dc-link voltage regulation technique for a hybrid inverter system formed by cascading two 3-level inverters. The two inverters are named as “bulk inverter” and “conditioning inverter”. For the hybrid system to act as a nine level inverter, conditioning inverter dc link voltage should be maintained at one third of the bulk inverter dc link voltage.

S. D. G. Jayasinghe; D. M. Vilathgamuwa; U. K. Madawala

2010-01-01

131

Application of a three-level NPC inverter as a three-phase four-wire power quality compensator by generalized 3DSVM  

Microsoft Academic Search

A two-level four-leg inverter has been developed for the three-phase four-wire power quality compensators. When it is applied to medium and large capacity compensators, the voltage stress across each switch is so high that the corresponding dv\\/dt causes large electromagnetic interference. The multilevel voltage source inverter topologies are good substitutes, since they can reduce voltage stress and improves output harmonic

Ning-Yi Dai; Man-Chung Wong; Ying-Duo Han

2006-01-01

132

An improved cascaded H-bridge multilevel inverter controlled by an unbalanced voltage level sigma-delta modulator  

Microsoft Academic Search

Multilevel inverters have been proven to be viable solutions for high-power automotive motor drive applications due to their high volt-ampere ratings. Cascaded H-bridge inverters are a promising breed of multilevel inverters which generally require several independent dc sources. Replacement of all but one of the dc sources with capacitors in cascaded H-bridge multilevel inverters, which leads to single-dc-source per-phase cascaded

Jingsheng Liao; Mehdi Ferdowsi

2008-01-01

133

Fuzzy Control of the Permanent Magnet Synchronous Machine Singularly Perturbed Fed By a Three Level Inverter  

NASA Astrophysics Data System (ADS)

In this paper, we present the control technique based on the singular perturbation technique controlled by a fuzzy regulator applied to the permanent magnet synchronous machine (PMSM). This technique applied to the PMSM conducts to a separation of the variables into disjoined subset or two separated models: one having a slow dynamics, and the other a fast dynamics. To ensure certain robustness to the decoupled control system based on these techniques, the control speed and the Id current is carried out by fuzzy regulators. A qualitative analysis of the principal variables evolution describing the behavior of the global system (PMSM-Inverter with MLI-Control) and its robustness is developed by several tests of digital simulation in last stage.

Massoum, Ahmed; Meroufel, Abdelkader; Wira, Patrice; Fellah, Mohammed Karim

2012-05-01

134

Interconnected levels of multi-stage marketing: A triadic approach  

Microsoft Academic Search

Multi-stage marketing gains increasing attention as knowledge of and influence on the customer's customer become more critical for the firm's success. Despite this increasing managerial relevance, systematic approaches for analyzing multi-stage marketing are still missing. This paper conceptualizes different levels of multi-stage marketing and illustrates these stages with a case study. In addition, a triadic perspective is introduced as an

Mette Vedel; Jens Geersbro; Thomas Ritter

2012-01-01

135

A new diode clamping multilevel inverter  

Microsoft Academic Search

This paper proposes a new diode clamping multilevel Inverter, which gets rid of the need for series association of the clamping diodes in the conventional diode clamping multilevel inverter. The new diode clamping inverter utilizes the same number of switches and diodes as the conventional one for synthesizing an inverter of a given level. Operation fundamentals, clamping mechanism as well

Xiaoming Yuan; Ivo Barbi

1999-01-01

136

Hydraulic Design of A MultiLevel Intake Structure  

Microsoft Academic Search

\\u000a In the present work design of a multi level intake is explained for a 65m high rock fill dam. This multi-level intake structure\\u000a was designed for irrigation purposes with a design discharge of 20 m3\\/s. This structure, standing vertically in the reservoir,\\u000a was 65m high and had a rectangular cross section which its dimensions were different at different elevations. Four

K. Safavi; A. R. Karaminejad; H. Jamali; H. A Sarkardeh; A. R. Zarrati

137

Reduced parts-count multi-level rectifiers  

Microsoft Academic Search

Multi-level power converters have gained much attention due to their high power quality, low switching losses, and high-voltage capability. These advantages make the multi-level converter a candidate topology for the next generation of naval ship propulsion systems. The primary disadvantage of these systems is the large number of semiconductors involved. This paper presents a reduced parts-count rectifier which is well

K. A. Corzine; J. R. Baker; J. Yuen

2001-01-01

138

New Space Vector Modulated 3-Level 3-Phase Voltage-Source Soft-Switching Inverter with Two Active Resonant DC Link Snubbers  

NASA Astrophysics Data System (ADS)

This paper presents a novel prototype of 3-level 3-phase voltage-fed soft switching commutation inverter with two Active Auxiliary Resonant DC Link (ARDCL) snubbers which can operate under a condition of Zero Voltage Switching (ZVS) transition. Its operating principle is described herein. The feasible steady-state performances of the proposed soft switching commutated inverter using the latest IGBTs such as planner type and trench type IGBTs, which is more suitable for power systems applications, are evaluated and discussed on the basis of its experimental results and simulation ones.

Yamamoto, Masayoshi; Sato, Shinji; Hiraki, Eiji; Nakaoka, Mutsuo

139

Hierarchical Classification by Multi-Level Reciprocity  

ERIC Educational Resources Information Center

A method is developed and illustrated which relaxes the principle of reciprocity in relation to characteristics of data and classifies in terms of successive levels of reciprocity, using two versions: (a) successive linkages, and (b) core assignments. (Author/RF)

McQuitty, Louis L.

1970-01-01

140

Speed sensorless stator flux oriented control of three-level inverter-fed induction motor drive based on fuzzy logic and sliding mode control  

Microsoft Academic Search

A novel simplified stator flux oriented control (SFOC) for three-level inverter-fed induction motor drive is proposed to achieve high performance torque control in both steady state and transient conditions. Sliding mode control (SMC) is designed, in stead of conventional PI controller, to obtain the continuous commanding voltage vectors. The speed accuracy and dynamic tracking performance, as well as robustness to

Yongchang Zhang; Jianguo Zhu; Wei Xu; Jiefeng Hu; David G. Dorrell; Zhengming Zhao

2010-01-01

141

A General Modulation Strategy for a Five-Level Three-Phase Current Source Inverter with Regulated Intermediate DC Link Currents  

Microsoft Academic Search

Multilevel converters use series\\/parallelled semiconductor switching devices to synthesise switched waveforms at power levels that are well above individual device ratings. To date, most multilevel inverter research has focused on voltage source structures, primarily because these topologies address the more common high power converter limiting factor of device voltage ratings. However, multilevel current source converters can have advantages in lower

Yakov L. Familiant; D. G. Holmes; T.A. Lipo; B. P. McGrath

2007-01-01

142

Multi-Level DC Bus Inverter for Providing Sinusoidal and PWM Electrical Machine Voltages.  

National Technical Information Service (NTIS)

A circuit for controlling an ac machine comprises a full bridge network of commutation switches which are connected to supply current for a corresponding voltage phase to the stator windings, a plurality of diodes, each in parallel connection to a respect...

G. J. Su

2003-01-01

143

Realization of three phase cascaded H-Bridge multi-level inverter as Shunt Active Filter  

Microsoft Academic Search

This paper presents a three-phase cascaded H-Bridge MLI as Shunt Active Filter intended for installation on industrial and utility of power distribution system is widely accepted and implemented as a solution to the power quality problems in utility, industry and commercial applications. This paper proposes the design of a shunt active power filter under the condition of voltage sag, unbalanced

N. Chellammal; Ravitheja Gurram; K. N. V. Prasad

2011-01-01

144

Inverting the source mechanism of Strombolian explosions at Mt. Yasur, Vanuatu, using a multi-parameter dataset  

NASA Astrophysics Data System (ADS)

The source mechanism of Strombolian explosions at Mt. Yasur, Vanuatu, is analyzed using a unique data set which enables us to combine different methodologies. The novelty of the approach presented here lies in the combination of seismic, acoustic and Doppler-radar data. Thus, using infrasound and Doppler radar observations we are able to provide independent estimates of the volume of the eruptive source. In the following, we show that a correlation exists between source volume and the maximum particle velocity of the expelled volcanic products. In order to determine the source location and the associated mechanism and to compare those two methods, we use time reversal imaging and moment tensor inversion. While the first method also applies to extended sources, the latter might be biased by its intrinsic point source approximation. We show that time reversal imaging can deliver an estimate of the source depth without any a priori assumptions even in an unfavorable scenario in terms of topography and receiver setup. The inverted source mechanism retrieved from moment tensor inversion is found to be largely isotropic, with minor deviatoric components. The inverted source location points towards an area to the north-west of the active craters, indicative of a common feeder system of the activity at Mt. Yasur. However, it is also evident, that to fully locate the source of Strombolian activity at Yasur location precision must be enhanced.

Kremers, S.; Wassermann, J.; Meier, K.; Pelties, C.; van Driel, M.; Vasseur, J.; Hort, M.

2013-07-01

145

Multi Core Design for Chip Level Multiprocessing  

NASA Astrophysics Data System (ADS)

Chip level integration continues to be a driving force in the computer industry. It lowers the cost and increases performance of computer systems, creating a remarkable rate of improvement in all processors, from handheld devices to supercomputers. Processor chips now (in 2009) contain up to two billion transistors. Gordon Moore outlined a roadmap for chip level integration in 1965, which has become known as Moore's Law. It predicts that the density of transistors in a silicon chip will double every process generation. It has become the heartbeat of the semiconductor industry.

Fossum, Tryggve

146

Timing Optimization for MultiLevel Combinational Networks  

Microsoft Academic Search

This paper presents a timing optimization algorithm SDLR (acronym of SYLON-DREAM Level-Reduction), which is used in the SYLON-DREAM logic synthesizer for speeding up combinational multi-level networks. In SDLR, gates on critical paths are identified and their level numbers counted from the inputs of the network are maximally reduced by a level-reduction procedure. Gates which are not on the critical paths

Kuang-chien Chen; Saburo Muroga

1990-01-01

147

High efficiency drive system with 3-level T-type inverter  

Microsoft Academic Search

In this paper an eciency optimized variable speed drive is presented. It consists of the alternative 3-level T-type converter topology which is very ecient for low switching frequencies and a standard induction machine. The total system eciency is optimized concerning the converter losses as well as fundamental and harmonic induction machine losses.

Mario Schweizer; Johann W. Kolar

2011-01-01

148

A dual inverter with integrated energy storage for wind power systems  

Microsoft Academic Search

This paper explores the possibility of using grid side inverter as an interface to connect energy storage systems. A dual inverter system, formed by cascading two 2-level inverters through a coupling transformer, is used as the testing model. The inverters are named as “main inverter” and “auxiliary inverter”. The main inverter is powered by the rectified output of the wind

S. D. G. Jayasinghe; D. M. Vilathgamuwa; U. K. Madawala

2010-01-01

149

Advanced simulation concept for power electronic systems applied to the 3-level NPC inverter  

Microsoft Academic Search

State-of-the-art high-power applications offer a high level of complexity, containing, e.g., linear, hybrid and nonlinear elements. The development of advanced control algorithms requires enhanced simulation effort featuring hybrid systems containing continuous and discrete elements. Besides a brief description of a simulation concept fulfilling these requirements and additionally minimising development time losses by program portation using an interface for control algorithms

Roman Bartelt; Carsten Heising; Martin Oettmeier; Volker Staudt; Andreas Steimel

2009-01-01

150

MATLAB-based simulation of three-level PWM inverter-fed motor speed control system  

Microsoft Academic Search

The need for energy savings and introduction of new high power devices like IGCTs accelerate the broad use of medium and high voltage adjustable speed drives (ASD) in industrial and traction applications. As part of the mission to design a 6 kV, 1600 kVA three-level converter-based ASD, a simulation system is developed using MATLAB package for the purpose of validating

Xiaorong Xie; Qiang Song; Gangui Yan; Wenhua Liu

2003-01-01

151

A general circuit topology of multilevel inverter  

Microsoft Academic Search

A generalized circuit topology of multilevel voltage source inverters which is based on a direct extension of the three-level inverter to higher level is proposed. The circuit topologies up to five-level are presented. The proposed multilevel inverter can realize any multilevel pulsewidth modulation (PWM) scheme which leads to harmonic reduction and provides full utilization of semiconductor devices like GTOs, especially

Nam S. Choi; Jung G. Cho; Gyu H. Cho

1991-01-01

152

A Simple and Reliable PWM Synchronization & Phase-Shift Method for Cascaded H-Bridge Multilevel Inverters based on a Standard Serial Communication Protocol  

Microsoft Academic Search

The use of the CAN communication protocol for H-bridge multi-level (HBML) inverters, and localized PWM generation and AVR is proposed in this paper. It is shown that the performance and reliability of conventional distributed controllers for HBML inverters can be improved with less communication hardware requirements, when using the proposed method. It is also shown that the expansion and modularization

Young-Min Park; Han-Seong Yoo; Hyun-Won Lee; Myung-Gil Jung; Se-Hyun Lee; Choong-Dong Lee; Sang-Bin Lee; Ji-Yoon Yoo

2006-01-01

153

A MultiLevel Architecture for Relational Data Base Systems  

Microsoft Academic Search

Most of the literature on implementation of relations has been directed toward user features, with little attention paid to an overall conceptual view of underlying structures. Performance oriented considerations have been treated only for isolated problems. Toward a solution to these problems we describe a multi-level architecture for relational data base systems. This architecture distinguishes clearly between user oriented features,

Hans Albrecht Schmid; Philip A. Bernstein

1975-01-01

154

IMPACT: Integrated Multi-Level Performance Framework for Scalable Systems.  

National Technical Information Service (NTIS)

The aim of the Phase 1 effort was to demonstrate the feasibility of an Integrated Multi-Level Performance Framework for Complex Systems (IMPACT) for simulation of a parallel database system. As described in this report, the Phase 1 effort resulted in the ...

J. Martin R. Bagrodia

1998-01-01

155

Service level differentiation in multi-robots control  

Microsoft Academic Search

In this paper we explore the effects of service level differentiation on a multi-robot control system. We examine the premise that although long interaction time between robots and operators hurts the efficiency of the system, as it generates longer waiting time for robots, it provides robots with longer neglect time and better performance benefiting the system. In the paper we

Ying Xu; Tinglong Dai; Katia Sycara; Michael Lewis

2010-01-01

156

Fuzzy approach for multi-level programming problems  

Microsoft Academic Search

Multi-level programming techniques are developed to solve decentralized planning problems with multiple decision makers in a hierarchical organization. These become more important for contemporary decentralized organizations where each unit or department seeks its own interests. Traditional approaches include vertex enumeration and transformation approaches. The former is in search of a compromise vertex based on adjusting the control variable(s) of the

Hsu-shih Shih; Young-jou Lai; E. Stanley Lee

1996-01-01

157

Constructing multi-level speech database for spontaneous speech processing  

Microsoft Academic Search

The paper describes a database called multi level speech database for spontaneous speech processing. We designed the database to cover textual and acoustic variations from declarative speech to spontaneous speech. The database is composed of 5 categories which are, in the order of decreasing spontaneity, spontaneous speech, interview, simulated interview, declarative speech with context, and declarative speech without context. We

Minsoo Hahn; Sanghun Kim; Jung-Chul Lee; Yong-Ju Lee

1996-01-01

158

Distributed multi-level adaptation for dynamic multi-agent systems  

Microsoft Academic Search

This paper proposes a distributed and multi-level adaptation system (MADAM) for agents to react to the changes of the world. The design of three adaptation levels in MADAM-global, middle, and local - allows agent to have both conscious and unconscious adaptive behaviors. At the local level, we use a rule-based instinctive reaction mechanism to simulate the unconscious adaptation. At the

Pham Hong Hanh; W. Rinsurongkawong; T. Ujjubandh

1999-01-01

159

Flexible Job Shop Scheduling with Multi-level Job Structures  

NASA Astrophysics Data System (ADS)

This paper deals with a scheduling problem in a flexible job shop with multi-level job structures where end products are assembled from sub-assemblies or manufactured components. For such shops MRP (Material Requirement Planning) logic is frequently used to synchronize and pace the production activities for the required parts. However, in MRP, the planning of operational-level activities is left to short term scheduling. So, we need a good scheduling algorithm to generate feasible schedules taking into account shop floor characteristics and multi-level job structures used in MRP. In this paper, we present a GA (Genetic Algorithm) solution for this complex scheduling problem based on a new gene to reflect the machine assignment, operation sequences and the levels of the operations relative to final assembly operation. The relative operation level is the control parameter that paces the completion timing of the components belonging to the same branch in the multi-level job hierarchy. We compare the genetic algorithm with several dispatching rules in terms of total tardiness and the genetic algorithm shows outstanding performance for about forty modified standard job-shop problem instances.

Jang, Yang-Ja; Kim, Ki-Dong; Jang, Seong-Yong; Park, Jinwoo

160

Three-Level Inverter-Based Shunt Active Power Filter in Three-Phase Three-Wire and Four-Wire Systems  

Microsoft Academic Search

This paper presents a direct current-space-vector control of an active power filter (APF) based on a three-level neutral-point-clamped (NPC) voltage-source inverter. The proposed method indirectly generates the compensation current reference by using an equivalent conductance of the fundamental component using APF's dc-link voltage control. The proposed control can selectively choose harmonic current components by real-time fast Fourier transform to generate

Oleg Vodyakho; Chris C. Mi

2009-01-01

161

A comprehensive study of neutral-point voltage balancing problem in three-level neutral-point-clamped voltage source PWM inverters  

Microsoft Academic Search

This paper explores the fundamental limitations of the neutral-point voltage balancing problem for different loading conditions of three-level voltage source inverters. A new model in the DQ coordinate frame utilizing current switching functions is developed as a means to investigate theoretical limitations and to offer a more intuitive insight into the problem. The low-frequency ripple of the neutral point caused

Nikola Celanovic; Dushan Boroyevich

2000-01-01

162

Low-speed rated-torque operation of a motor drive using a five-level diode-clamped PWM inverter with a front-end diode rectifier  

Microsoft Academic Search

This paper focuses on a medium-voltage motor drive requiring no regenerative braking. It is operated not only in a high-speed region but also in a low-speed region with the rated torque, intended for an application to drilling rigs. The power conversion system consists of a front-end diode rectifier, a five-level diode-clamped PWM inverter, and a dc-voltage-balancing circuit including a single

Kazunori Hasegawa; Hirofumi Akagi

2011-01-01

163

Retrofit of fixed speed induction motors with medium voltage drive converters using NPC three-level inverter high-voltage IGBT based topology  

Microsoft Academic Search

This paper presents a solution to allow simple and risk-free retrofit of existing fixed speed induction motors with medium voltage adjustable speed drives to achieve attractive energy savings. The presented medium voltage adjustable speed drive consists of a twelve-pulse diode rectifier and a three-level neutral point clamped inverter using high-voltage IGBTs. Innovative features of the drive include series-connection of high-voltage

Benoit P. Schmitt; Rainer Sommer

2001-01-01

164

A New DC-Voltage-Balancing Circuit Including a Single Coupled Inductor for a Five-Level Diode-Clamped PWM Inverter  

Microsoft Academic Search

This paper proposes a new dc-voltage-balancing cir- cuit for a five-level diode-clamped inverter intended for a medi- um-voltage motor drive with a three-phase diode rectifier used as the front end. This circuit consists of two unidirectional choppers and a single coupled inductor with two galvanically isolated wind- ings. The inductor produces no net dc magnetic flux because the individual dc

Kazunori Hasegawa; Hirofumi Akagi

2011-01-01

165

Maltweb multi-axis viewing interface and higher level scoping  

US Patent & Trademark Office Database

A method, apparatus and computer program product for navigating in a multi-dimensional space containing an electronic publication formed from predefined portions of text-based data encoded using a markup language are disclosed. A selected predefined portion is displayed in a first display region. A point on a primary axis of the multi-dimensional space corresponding to the displayed pre-defined portion is also displayed. Also, a method, apparatus and computer program product for publishing an electronic publication formed from predefined portions of text-based data encoded using a markup language are also disclosed. Predefined portions are stored in terminal nodes. Higher level nodes are provided for organising the terminal nodes into an hierarchical structure embodied in said electronic publication. Each higher level node contains the identity of a parent node, a position indicator for the higher level node and an associated identifier.

2013-02-26

166

Analysis of neutral-point voltage balancing problem in three-level neutral-point-clamped inverters with SVPWM modulation  

Microsoft Academic Search

In this paper, the evolution and the control options of the neutral point potential in NPC inverters with SVPWM modulation are analysed. In this analysis, the different components that can be found in the phase current are taken into account: fundamental, DC current and harmonics. Firstly, the current injected in the neutral point by the nonredundant medium vectors is evaluated

Oscar Alonso; L. Marroyo; P. Sanchis; E. Gubia; A. Guerrero

2002-01-01

167

Quasilinear IGBT inverter topologies  

Microsoft Academic Search

Magnetic resonance imaging (MRI) systems require stronger gradient coil currents with faster ramp times for high-speed image taking and in order to obtain a smaller field of view or a magnification effect. Previous speedup inverter circuits able to provide those higher power levels have been discussed at APEC-92 and APEC-93. They could generate squarewave currents with a constant ramp slope

O. M. Mueller; J. N. Park

1994-01-01

168

Multi-level Hybrid Cache: Impact and Feasibility  

SciTech Connect

Storage class memories, including flash, has been attracting much attention as promising candidates fitting into in today's enterprise storage systems. In particular, since the cost and performance characteristics of flash are in-between those of DRAM and hard disks, it has been considered by many studies as an secondary caching layer underneath main memory cache. However, there has been a lack of studies of correlation and interdependency between DRAM and flash caching. This paper views this problem as a special form of multi-level caching, and tries to understand the benefits of this multi-level hybrid cache hierarchy. We reveal that significant costs could be saved by using Flash to reduce the size of DRAM cache, while maintaing the same performance. We also discuss design challenges of using flash in the caching hierarchy and present potential solutions.

Zhang, Zhe [ORNL; Kim, Youngjae [ORNL; Ma, Xiaosong [ORNL; Shipman, Galen M [ORNL; Zhou, Yuanyuan [University of California, San Diego

2012-02-01

169

A multi-level method for sparse linear systems  

SciTech Connect

A multi-level method for the solution of sparse linear systems is introduced. The definition of the method is based on data from the coefficient matrix alone. An upper bound for the condition number is available for certain symmetric positive definite (SPD) problems. Numerical experiments confirm the analysis and illustrate the efficiency of the method for diffusion problems with discontinuous coefficients with discontinuities which are not aligned with the coarse meshes.

Shapira, Y.

1997-09-01

170

Glimpse: a novel input model for multi-level devices  

Microsoft Academic Search

We describe a technique that supports the previewing of navigation, exploration, and editing operations by providing convenient Undo for unsuccessful and\\/or undesirable actions on multi-level input devices such as touch screens and pen-based computers. By adding a Glimpse state to traditional three-state pressure sensitive input devices, users are able to preview the effects of their editing without committing to them.

Clifton Forlines; Chia Shen; Bill Buxton

2005-01-01

171

Advanced micromechanisms in a multi-level polysilicon technology  

SciTech Connect

Quad-level polysilicon surface micromachining technology, comprising three mechanical levels plus an electrical interconnect layer, is giving rise to a new generation of micro-electromechanical devices and assemblies. Enhanced components can not be produced through greater flexibility in fabrication and design. New levels of design complexity that include multi-level gears, single-attempt locks, and optical elements have recently been realized. Extensive utilization of the fourth layer of polysilicon differentiates these latter generation devices from their predecessors. This level of poly enables the fabrication of pin joints, linkage arms, hinges on moveable plates, and multi-level gear assemblies. The mechanical design aspects of these latest micromachines will be discussed with particular emphasis on a number of design aspects of these latest micromachines will be discussed with particular emphasis on a number of design modifications that improve the power, reliability, and smoothness of operation of the microengine. The microengine is the primary actuation mechanism that is being used to drive mirrors out of plane and rotate 1600-{mu}m diameter gears. Also discussed is the authors most advanced micromechanical system to date, a complex proof-of-concept batch-fabricated assembly that, upon transmitting the proper electrical code to a mechanical lock, permits the operation of a micro-optical shutter.

Rodgers, M.S.; Sniegowski, J.J.; Miller, S.L.; Barron, C.C.; McWhorter, P.J.

1997-08-01

172

A Multi Level Multi Domain Method for Particle In Cell plasma simulations  

NASA Astrophysics Data System (ADS)

A novel adaptive technique for electromagnetic Particle In Cell (PIC) plasma simulations is presented here. Two main issues are identified as regards the development of the algorithm. First, the choice of the size of the particle shape function in progressively refined grids, with the decision to avoid both time-dependent shape functions and cumbersome particle-to-grid interpolation techniques, and, second, the necessity to comply with the strict stability constraints of the explicit PIC algorithm. The adaptive implementation presented responds to these demands with the introduction of a Multi Level Multi Domain (MLMD) system, where a cloud of self-similar domains is fully simulated with both fields and particles, and the use of an Implicit Moment PIC method as baseline algorithm for the adaptive evolution. Information is exchanged between the levels with the projection of the field information from the refined to the coarser levels and the interpolation of the boundary conditions for the refined levels from the coarser level fields. Particles are bound to their level of origin and are prevented from transitioning to coarser levels, but are repopulated at the refined grid boundaries with a splitting technique. The presented algorithm is tested against a series of simulation challenges.

Innocenti, M. E.; Lapenta, G.; Markidis, S.; Beck, A.; Vapirev, A.

2013-04-01

173

Multi-level selection for hygienic behaviour in honeybees.  

PubMed

Disease is one of the main factors driving both natural and artificial selection. It is a particularly important and increasing threat to the managed honeybee colonies, which are vital in crop pollination. Artificial selection for disease-resistant honeybee genotypes has previously only been carried out at the colony-level, that is, by using queens or males reared from colonies that show resistance. However, honeybee queens mate with many males and so each colony consists of multiple patrilines that will vary in heritable traits, such as disease resistance. Here, we investigate whether response to artificial selection for a key resistance mechanism, hygienic behaviour, can be improved using multi-level selection, that is, by selecting not only among colonies as normal but also among patrilines within colonies. Highly hygienic colonies were identified (between-colony selection), and the specific patrilines within them responsible for most hygienic behaviour were determined using observation hives. Queens reared from these hygienic patrilines (within-colony selection) were identified using DNA microsatellite analysis of a wing-tip tissue sample and then mated to drones from a third highly hygienic colony. The resulting colonies headed by queens from hygienic patrilines showed approximately double the level of hygienic behaviour of colonies headed by sister queens from non-hygienic patrilines. The results show that multi-level selection can significantly improve the success of honeybee breeding programs. PMID:19259116

Pérez-Sato, J A; Châline, N; Martin, S J; Hughes, W O H; Ratnieks, F L W

2009-03-04

174

Fundamental-Frequency-Modulated Six-Level Diode-Clamped Multilevel Inverter for Three-Phase Stand-Alone Photovoltaic System  

SciTech Connect

This paper presents a fundamental-frequency-modulated diode-clamped multilevel inverter (DCMLI) scheme for a three-phase stand-alone photovoltaic (PV) system. The system consists of five series-connected PV modules, a six-level DCMLI generating fundamental-modulation staircase three-phase output voltages, and a three-phase induction motor as the load. In order to validate the proposed concept, simulation studies and experimental measurements using a small-scale laboratory prototype are also presented. The results show the feasibility of the fundamental frequency switching application in three-phase stand-alone PV power systems.

Ozdemir, Engin [ORNL; Ozdemir, Sule [Oak Ridge National Laboratory (ORNL); Tolbert, Leon M [ORNL

2009-01-01

175

Multi-Level Bitmap Indexes for Flash Memory Storage  

SciTech Connect

Due to their low access latency, high read speed, and power-efficient operation, flash memory storage devices are rapidly emerging as an attractive alternative to traditional magnetic storage devices. However, tests show that the most efficient indexing methods are not able to take advantage of the flash memory storage devices. In this paper, we present a set of multi-level bitmap indexes that can effectively take advantage of flash storage devices. These indexing methods use coarsely binned indexes to answer queries approximately, and then use finely binned indexes to refine the answers. Our new methods read significantly lower volumes of data at the expense of an increased disk access count, thus taking full advantage of the improved read speed and low access latency of flash devices. To demonstrate the advantage of these new indexes, we measure their performance on a number of storage systems using a standard data warehousing benchmark called the Set Query Benchmark. We observe that multi-level strategies on flash drives are up to 3 times faster than traditional indexing strategies on magnetic disk drives.

Wu, Kesheng; Madduri, Kamesh; Canon, Shane

2010-07-23

176

Multi-Level Opinion Dynamics under Bounded Confidence  

PubMed Central

Opinion dynamics focuses on the opinion evolution in a social community. Recently, some models of continuous opinion dynamics under bounded confidence were proposed by Deffuant and Krause, et al. In the literature, agents were generally assumed to have a homogeneous confidence level. This paper proposes an extended model for a group of agents with heterogeneous confidence levels. First, a social differentiation theory is introduced and a social group is divided into opinion subgroups with distinct confidence levels. Second, a multi-level heterogeneous opinion formation model is formulated under the framework of bounded confidence. Finally, computer simulations are conducted to study the collective opinion evolution, focusing on three key factors: the fractions of heterogeneous agents, the initial opinions, and the group size. The simulation results demonstrate that the number of final opinions depends on the fraction of close-minded agents when the group size and the initial opinions are fixed; the final opinions converge more easily when the initial opinions are closer; and the number of final opinions can be approximately modeled by a linear increasing function of the group size and the increasing rate is the fraction of close-minded agents.

Kou, Gang; Zhao, Yiyi; Peng, Yi; Shi, Yong

2012-01-01

177

A multi-level typology of abstract visualization tasks.  

PubMed

The considerable previous work characterizing visualization usage has focused on low-level tasks or interactions and high-level tasks, leaving a gap between them that is not addressed. This gap leads to a lack of distinction between the ends and means of a task, limiting the potential for rigorous analysis. We contribute a multi-level typology of visualization tasks to address this gap, distinguishing why and how a visualization task is performed, as well as what the task inputs and outputs are. Our typology allows complex tasks to be expressed as sequences of interdependent simpler tasks, resulting in concise and flexible descriptions for tasks of varying complexity and scope. It provides abstract rather than domain-specific descriptions of tasks, so that useful comparisons can be made between visualization systems targeted at different application domains. This descriptive power supports a level of analysis required for the generation of new designs, by guiding the translation of domain-specific problems into abstract tasks, and for the qualitative evaluation of visualization usage. We demonstrate the benefits of our approach in a detailed case study, comparing task descriptions from our typology to those derived from related work. We also discuss the similarities and differences between our typology and over two dozen extant classification systems and theoretical frameworks from the literatures of visualization, human-computer interaction, information retrieval, communications, and cartography. PMID:24051804

Brehmer, Matthew; Munzner, Tamara

2013-12-01

178

A Dual-Input–Dual-Output Z-Source Inverter  

Microsoft Academic Search

This paper presents a new z-source inverter with two AC outputs and two DC inputs. This inverter is based on the z-source inverter and nine-switch inverter. The presented inverter can control amplitude, frequency, and phase of both AC outputs and also control current of both DC inputs. Input dc voltages are boosted to the required level. Also, both outputs continue

Seyed Mohammad Dehghan; Mustafa Mohamadian; Ali Yazdian; Farhad Ashrafzadeh

2010-01-01

179

Dual-input dual-output z-source inverter  

Microsoft Academic Search

This paper presents a new z-source inverter with two AC outputs and two DC inputs. This inverter is based on the z-source inverter and nine-switch inverter. The presented inverter can control amplitude, frequency and phase of both AC outputs and also control current of both DC inputs. Input DC voltages are boosted to the required level. Also, both outputs continue

S. M. Dehghan; M. Mohamadian; A. Yazdian; F. Ashrafzadeh

2009-01-01

180

Translation Levels Control Multi-Spanning Membrane Protein Expression  

PubMed Central

Attempts to express eukaryotic multi-spanning membrane proteins at high-levels have been generally unsuccessful. In order to investigate the cause of this limitation and gain insight into the rate limiting processes involved, we have analyzed the effect of translation levels on the expression of several human membrane proteins in Escherichia coli (E. coli). These results demonstrate that excessive translation initiation rates of membrane proteins cause a block in protein synthesis and ultimately prevent the high-level accumulation of these proteins. Moderate translation rates allow coupling of peptide synthesis and membrane targeting, resulting in a significant increase in protein expression and accumulation over time. The current study evaluates four membrane proteins, CD20 (4-transmembrane (TM) helixes), the G-protein coupled receptors (GPCRs, 7-TMs) RA1c and EG-VEGFR1, and Patched 1 (12-TMs), and demonstrates the critical role of translation initiation rates in the targeting, insertion and folding of integral membrane proteins in the E. coli membrane.

Brown, Cecilia; Bostrom, Jenny; Fuh, Germaine; Lee, Chingwei V.; Huang, Arthur; Vandlen, Richard L.; Yansura, Daniel G.

2012-01-01

181

Optimal retiming of multi-phase, level-clocked circuits  

NASA Astrophysics Data System (ADS)

Using level-sensitive latches instead of edge-triggered registers for storage elements in a synchronous system can lead to faster and less expensive circuit implementations. This advantage derives from an increased flexibility in scheduling the computations performed by the circuit. In edge-clocked circuits the amount of time available for the computation between two registers is precisely the length of the clock cycle, while in circuits using level-sensitive latches a computation can borrow time across latches thus reducing the amount of dead time in the clock cycle. In either type of circuit, achieving maximum performance requires locating the storage elements in such a way as to spread the computation uniformly across a number of clock cycles. Retiming is the process of rearranging the storage elements in a circuit to reduce the cycle time or the number of storage elements without changing the interface behavior of the circuit as viewed by an outside host. Retiming in effect reschedules the circuit computations is time based on the length of those computations. In this paper, we extend the retiming techniques developed for edged-clocked circuits by Leiserson, Rose and Saxe to a general class of multi-phase, level-clocked circuits. We first describe this class of well-formed circuits and define what it means for a well-formed, level-clocked circuit to operate correctly. We then show that a set of constraints can then be used to retime a level-clocked circuit using efficient integer linear programming techniques similar to those used for edge-clocked circuits.

Lockyear, Brian; Ebeling, Carl

1991-10-01

182

Cascaded H-bridge multilevel inverter employing bidirectional switches  

Microsoft Academic Search

It presents a cascaded H-bridge multilevel inverter employing bidirectional switches to design an effective circuit to increase the number of output voltage levels. In the proposed circuit configuration, each inverter produces five output voltage levels. Because the output terminals of both inverters are connected in series, the final output voltage becomes nine levels including a zero. Different switching patterns are

Won-kyun Choi; Cheol-soon Kwon; Un-Taek Hong; Feel-soon Kang

2010-01-01

183

Fuzzy Bi-Level Multi-Objective Programming for Supply Chain  

Microsoft Academic Search

For a two-echelon supply chain consisted of multi-plants and multi-warehouses, with multi-productions, this paper develops a bi-level programming model aims to minimize the total cost. The problem includes two sub-problems: the higher-level problem and the lower-level problem respectively decided by plants and warehouses. Built in dynamic environments the model has fuzzy parameters in constraints. The way to convert fuzzy constraints

Ying Li; Shanlin Yang

2007-01-01

184

Multi-Level Modeling of Dyadic Data in Sport Sciences: Conceptual, Statistical, and Practical Issues  

ERIC Educational Resources Information Center

|The goal of this article is to present a series of conceptual, statistical, and practical issues in the modeling of multi-level dyadic data. Distinctions are made between distinguishable and undistinguishable dyads and several types of independent variables modeled at the dyadic level of analysis. Multi-level modeling equations are explained in a…

Gaudreau, Patrick; Fecteau, Marie-Claude; Perreault, Stephane

2010-01-01

185

Multi-level recordable disc using signal waveform modulation recording method  

NASA Astrophysics Data System (ADS)

A new kind of multi-level recordable disc is presented in this paper. By improving the recording control signal in DVD-R/RW burning process, a Multi-level disc with signal waveform modulation can be achieved. The multi-level recording method increases the recording density but also the channel noise. The optimally designed partial response maximum likelihood (PRML) equalizer is effective in recovering channel symbol, and the original error rate reach 10E-4. This kind of multi-level method can be used for the purpose such as increasing the capacity of disc, hiding data and burning disc identification information etc.

Pei, Jing; Pan, Longfa; Yang, Bo; Hu, Junhua

186

Verify level control criteria for multi-level cell flash memories and their applications  

NASA Astrophysics Data System (ADS)

In 1 M-bit/cell multi-level cell (MLC) flash memories, it is more difficult to guarantee the reliability of data as M increases. The reason is that an M-bit/cell MLC has 2 M states whereas a single-level cell (SLC) has only two states. Hence, compared to SLC, the margin of MLC is reduced, thereby making it sensitive to a number of degradation mechanisms such as cell-to-cell interference and charge leakage. In flash memories, distances between 2 M states can be controlled by adjusting verify levels during incremental step pulse programming (ISPP). For high data reliability, the control of verify levels in ISPP is important because the bit error rate (BER) will be affected significantly by verify levels. As M increases, the verify level control will be more important and complex. In this article, we investigate two verify level control criteria for MLC flash memories. The first criterion is to minimize the overall BER and the second criterion is to make page BERs equal. The choice between these criteria relates to flash memory architecture, bits per cell, reliability, and speed performance. Considering these factors, we will discuss the strategy of verify level control in the hybrid solid state drives (SSD) which are composed of flash memories with different number of bits per cell.

Kim, Yongjune; Kim, Jaehong; Kong, Jun Jin; K Vijaya Kumar, B. V.; Li, Xin

2012-12-01

187

Moderating role of subordinates' attitudes on transformational leadership and effectiveness: A multi-cultural and multi-level perspective  

Microsoft Academic Search

We conducted the current multi-cultural, multi-level study with three objectives in mind. First, we examined the association of transformational leadership and leader effectiveness across two different cultures, the United States (U.S.) and Korea, with three followers' attitudes toward their leader (trust in the leader, loyalty, and value congruence) as moderators of this association. Second, we conceptualized followers' collectivistic orientation as

Dongil Jung; Francis J. Yammarino; Jin K. Lee

2009-01-01

188

Conceptualising the perceived service quality of public utility services: A multi-level, multi-dimensional model  

Microsoft Academic Search

Based on the data relevant to four public utility services (water, natural gas, electricity and thermoelectricity) collected by a personally administered on-site survey, the authors develop a model to assess the perceived service quality of public utility services. In the model, the perceived service quality of public utility services has a multi-level, multi-dimensional structure with three primary dimensions: outcome, environment

Changhong Bai; Fujun Lai; Ye Chen; Joe Hutchinson

2008-01-01

189

Antibiotic resistance shaping multi-level population biology of bacteria  

PubMed Central

Antibiotics have natural functions, mostly involving cell-to-cell signaling networks. The anthropogenic production of antibiotics, and its release in the microbiosphere results in a disturbance of these networks, antibiotic resistance tending to preserve its integrity. The cost of such adaptation is the emergence and dissemination of antibiotic resistance genes, and of all genetic and cellular vehicles in which these genes are located. Selection of the combinations of the different evolutionary units (genes, integrons, transposons, plasmids, cells, communities and microbiomes, hosts) is highly asymmetrical. Each unit of selection is a self-interested entity, exploiting the higher hierarchical unit for its own benefit, but in doing so the higher hierarchical unit might acquire critical traits for its spread because of the exploitation of the lower hierarchical unit. This interactive trade-off shapes the population biology of antibiotic resistance, a composed-complex array of the independent “population biologies.” Antibiotics modify the abundance and the interactive field of each of these units. Antibiotics increase the number and evolvability of “clinical” antibiotic resistance genes, but probably also many other genes with different primary functions but with a resistance phenotype present in the environmental resistome. Antibiotics influence the abundance, modularity, and spread of integrons, transposons, and plasmids, mostly acting on structures present before the antibiotic era. Antibiotics enrich particular bacterial lineages and clones and contribute to local clonalization processes. Antibiotics amplify particular genetic exchange communities sharing antibiotic resistance genes and platforms within microbiomes. In particular human or animal hosts, the microbiomic composition might facilitate the interactions between evolutionary units involved in antibiotic resistance. The understanding of antibiotic resistance implies expanding our knowledge on multi-level population biology of bacteria.

Baquero, Fernando; Tedim, Ana P.; Coque, Teresa M.

2013-01-01

190

Recognising interdependence and defining multi-level governance in city sustainability plans  

Microsoft Academic Search

A growing number of city governments in the USA have developed plans to pursue sustainable development and mitigate climate change. City governments do not act alone on such complex environmental and social policies, but participate in a web of multi-level governance relationships, interacting with other local governments, community organisations, state and federal government agencies, and international organisations. How is multi-level

Eric Zeemering

2012-01-01

191

Cascade Multilevel Inverters for Utility Applications  

SciTech Connect

Cascade multilevel inverters have been developed by the authors for utility applications. A cascade M-level inverter consists of (M-1)/2 H- bridges in which each bridge has its own separate dc source. The new inverter: (1) can generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle, (2) can eliminate transformers of multipulse inverters used in conventional utility interfaces and static var compensators, and (3) makes possible direct parallel or series connection to medium- and high-voltage power systems without any transformers. In other words, the cascade inverter is much more efficient and suitable for utility applications than traditional multipulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for reactive power (var) and harmonic compensation. This paper will summarize features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems.Analytical, simulated, and experimental results demonstrate the superiority of the new inverters.

Peng, F.Z., McKeever, J.W., Adams, D.J.

1997-12-31

192

Application of OMTHD on the line voltage of cascaded multi-level inverters with adjustable DC sources  

Microsoft Academic Search

In this paper, the Optimal Minimization of the Total Harmonic Distortion (OMTHD) technique is improved to calculate minimum phase THD and approximate line to line THD versus variable Modulation Indices (M). In Developed single-phase OMTHD technique, the Fitness function is proposed to minimize phase THD, and fundamental component as a constraint is separately added to Fitness function to adjust the

N. Yousefpoor; S. H. Fathi; N. Farokhnia; H. A. Abyaneh

2010-01-01

193

General MultiLevel Linear Modelling for Group Analysis in FMRI  

Microsoft Academic Search

Abstract: This paper discusses general modelling of multi-subject and\\/or multi-session FMRI data. In particular, weshow that a two-level mixed-effects model (where parameters of interest at the group level are estimated fromparameter and variance estimates from the single-session level) can be made equivalent to a single completemixed-effects model (where parameters of interest at the group level are estimated directly from all

Christian F. Beckmann; Mark Jenkinson; Stephen M. Smith

194

MSPWM & MTPWM techniques for asymmetric H-bridge multilevel inverter  

Microsoft Academic Search

Multilevel inverter is a new breed of power converter which is suited for high power applications. The various topologies of multilevel inverter are diode - clamped, capacitor clamped and cascaded H-bridge inverter. It is an effective solution for increasing the number of levels in output waveform with reduced dc sources and switching elements, thereby dramatically reduces harmonics without increasing the

P. Jamuna; C. Christober Asir Rajan

2012-01-01

195

Parallel operation control technique of voltage source inverters in UPS  

Microsoft Academic Search

The control technique of a parallel operation system of voltage source inverters with other inverters or with utility source has been applied in many fields, especially in uninterruptible power supply (UPS). The multi-module UPS can flexibly implement expansion of power system capacities. Furthermore, it can be used to build up a parallel redundant system in order to improve the reliability

Duan Shanxu; Meng Yu; Xiong Jian; Kang Yong; Chen Jian

1999-01-01

196

A generalized multilevel inverter topology with self voltage balancing  

Microsoft Academic Search

Multilevel power converters that provide more than two levels of voltage to achieve smoother and less distorted AC-to-DC, DC-to-AC, and DC-to-DC power conversion, have attracted many contributors. This paper presents a generalized multilevel inverter (converter) topology with self voltage balancing. The existing multilevel inverters such as diode-clamped and capacitor-clamped multilevel inverters can be derived from the generalized inverter topology. Moreover,

Fang Zheng Peng

2001-01-01

197

A multi-level computational model for multi-scale damage analysis in composite and porous materials  

Microsoft Academic Search

An adaptive multi-level methodology is developed in this paper to create a hierarchy of computational sub-domains with varying resolution for multiple scale problems. It is intended to concurrently predict evolution of variables at the structural and microstructural scales, as well as to track the incidence and propagation of microstructural damage in composite and porous materials. The microstructural analysis is conducted

Somnath Ghosh; Kyunghoon Lee; Prasanna Raghavan

2001-01-01

198

Packet combining with chip level frequency domain turbo equalization for multi-code transmission over multi-antenna broadband channel  

Microsoft Academic Search

In this paper, we introduce two packet combining schemes with low complexity minimum mean square error (MMSE) turbo equalization for single user multi-code CDMA transmission over a broadband multiple input multiple output (MIMO) channel. The first scheme considers each transmission as an additional set of virtual receive antennas and combines multiple transmissions using a frequency domain chip level turbo equalizer.

Houda Chafnaji; Tarik Ait-idir; Samir Saoudi

2008-01-01

199

The Dynamic Processes of Volunteering in Civil Society: A Group and MultiLevel Approach  

Microsoft Academic Search

With new emphasis on civil advocacy and active citizenship, volunteering needs more of a group process and multi-level approach to civil society. A theoretical approach to doing this can be done in two ways. First, volunteering can be theorized as existing in informal networks with opinion leaders who provide information and recruit volunteers through a multi-step process. In these interpretive

Thomas Janoski

2010-01-01

200

Invertible Darboux Transformations  

NASA Astrophysics Data System (ADS)

For operators of many different kinds it has been proved that (generalized) Darboux transformations can be built using so called Wronskian formulae. Such Darboux transformations are not invertible in the sense that the corresponding mappings of the operator kernels are not invertible. The only known invertible ones were Laplace transformations (and their compositions), which are special cases of Darboux transformations for hyperbolic bivariate operators of order 2. In the present paper we find a criteria for a bivariate linear partial differential operator of an arbitrary order d to have an invertible Darboux transformation. We show that Wronkian formulae may fail in some cases, and find sufficient conditions for such formulae to work.

Shemyakova, Ekaterina

2013-01-01

201

Multi-level scanning method for defect inspection  

DOEpatents

A method for performing scanned defect inspection of a collection of contiguous areas using a specified false-alarm-rate and capture-rate within an inspection system that has characteristic seek times between inspection locations. The multi-stage method involves setting an increased false-alarm-rate for a first stage of scanning, wherein subsequent stages of scanning inspect only the detected areas of probable defects at lowered values for the false-alarm-rate. For scanning inspection operations wherein the seek time and area uncertainty is favorable, the method can substantially increase inspection throughput.

Bokor, Jeffrey (Oakland, CA); Jeong, Seongtae (Richmond, CA)

2002-01-01

202

System Identification and Multi-Level Optimization of Integrated Ground Water Systems.  

National Technical Information Service (NTIS)

Conjunctive surface water and ground water systems are analyzed using the techniques of system identification and multi-level optimization. Mathematical models describing the behavior of the ground water regime are developed. Given historic ground water l...

J. A. Dracup

1974-01-01

203

Microseismic Mapping of Hydraulic Fractures Using MultiLevel Wireline Receivers  

Microsoft Academic Search

Hydraulic fracture diagnostic experiments are being conducted at the GRI\\/DOE Multi-Site (M-Site) located in the Piceance basin of Colorado. Tests described in this paper use a multi-level advanced-receiver system to build on previous work that showed the advantages of using a single advanced receiver to monitor microseisms. The current test has a four-level receiver system monitoring four separate fracture experiments

N. R. Warpinski; B. P. Engler; C. J. Young; R. Peterson; P. T. Branagan; J. E. Fix

1995-01-01

204

The Problematique of Community-Based Conservation in a MultiLevel World  

Microsoft Academic Search

Community-based resource management or community-based conservation is not just about communities. It is about governance that starts from the ground up and involves multi-level interactions. Complexities of this multi-level world create problems but also provide opportunities to combine conservation with development. I unpack the problematique of community-based conservation and deal with four aspects of it. The first is the inability

Fikret Berkes

205

The European Union, New Institutionalism and Types of MultiLevel Governance  

Microsoft Academic Search

Multi-level Governance (MLG) fundamentally challenges a state-centric, intergovernmentalist understanding of EU policy-making, emphasising the non-hierarchical, interconnected and multi-actor nature of contemporary governing. As such, MLG encapsulates the reconfiguration of policy-making space in the EU, rejecting a conception of governing as existing at either the domestic or international level, but rather as a single entity characterised by a complex web of

Anil Awesti

2007-01-01

206

Inverted T channel FET (ITFET) - Fabrication and characteristics of vertical-horizontal, thin body, multi-gate, multi-orientation devices, ITFET SRAM bit-cell operation. A novel technology for 45nm and beyond CMOS  

Microsoft Academic Search

In this paper we demonstrate for the first time a novel CMOS IT-FET (inverted T channel FET) architecture. We demonstrate well functional ITFET SRAM bit-cells. Vertical devices such as FinFET and planar ultra thin body devices have been shown to exhibit good short channel control and proposed for future device scaling. The ITFET is novel device architecture that takes advantage

L. Mathew; M. Sadd; S. Kalpat; M. Zavala; T. Stephens; R. Mora; S. Bagchi; C. Parker; J. Vasek; D. Sing; R. Shimer; L. Prabhu; G. O. Workman; G. Ablen; Z. Shi; J. Saenz; B. Min; D. Burnett; B.-Y. Nguyen; J. Mogab; M. M. Chowdhury; W. Zhang; J. G. Fossum

2005-01-01

207

Evolution of norms in a multi-level selection model of conflict and cooperation  

Microsoft Academic Search

We investigate the evolution of social norms in a game theoretical model of multi-level selection and mutation. Cooperation is modelled at the lower level of selection by means of a social dilemma in the context of indirect reciprocity, whereas at the higher level of selection conflict is introduced via different mechanisms. The model allows the emergence of norms requiring high

J. M. Pacheco; F. C. Santos; F. A. C. C. Chalub

208

Timing optimization for multi-level combination networks  

Microsoft Academic Search

A timing optimization algorithm SDLR (SYLON-DREAM level-reduction) is presented, which is used in the SYLON-DREAM logic synthesizer for speeding up combinational multilevel networks. In SDLR, gates on critical paths are identified and their level numbers counted from the inputs of the network are maximally reduced by a level-reduction procedure. Gates which are not on the critical paths are processed by

Kuang-Chien Chen; Saburo Muroga

1990-01-01

209

On the inclusion properties for multi-level cache hierarchies  

Microsoft Academic Search

The inclusion property is essential in reducing the cache coherence complexity for multiprocessors with multilevel cache hierarchies. We give some necessary and sufficient conditions for imposing the inclusion property for fully- and set-associative caches which allow different block sizes at different levels of the hierarchy. Three multiprocessor structures with a two-level cache hierarchy (single cache extension, multiport second-level cache, bus-based)

Jean-Loup Baer; Wen-Hann Wang

1988-01-01

210

An integrated approach for multi-level sample size determination  

SciTech Connect

this paper gives an integrated approach to sampling problems involving a series of increasingly sensitive measurements on correspondingly smaller sample sizes which proceeds logically from level to level with increasing accuracy. The methods and results are consistent with those presently used by the International Atomic Energy Agency (IAEA), serve to elucidate the underlying concepts, and often simplify the calculations.

Lu, M.S.; Sanborn, J.B. [Brookhaven National Lab., Upton, NY (United States); Teichmann, T. [Vienna (Austria)

1997-02-01

211

An efficient method to improve iris recognition performance based on multi-level fusion  

NASA Astrophysics Data System (ADS)

To improve the reliability and accuracy of iris-based identification system, this paper proposed an efficient method based on multi-level fusion. Multi-level fusion contains two levels: multialgorithmic fusion and multiinstance fusion. The multialgorithmic fusion integrates the improved phase algorithm and the DCT-based algorithm, and the multiinstance fusion combines information from left iris and right iris of an individual. Both multialgorithmic fusion and multiinstance fusion are carried out at the matching score level. The experimental results on the noisy iris database UBIRIS demonstrate that the proposed fusion schemes can perform better than the simple recognition systems.

Wang, Fenghua; Zhang, Xinman

2012-01-01

212

Rule-based multi-level modeling of cell biological systems  

PubMed Central

Background Proteins, individual cells, and cell populations denote different levels of an organizational hierarchy, each of which with its own dynamics. Multi-level modeling is concerned with describing a system at these different levels and relating their dynamics. Rule-based modeling has increasingly attracted attention due to enabling a concise and compact description of biochemical systems. In addition, it allows different methods for model analysis, since more than one semantics can be defined for the same syntax. Results Multi-level modeling implies the hierarchical nesting of model entities and explicit support for downward and upward causation between different levels. Concepts to support multi-level modeling in a rule-based language are identified. To those belong rule schemata, hierarchical nesting of species, assigning attributes and solutions to species at each level and preserving content of nested species while applying rules. Further necessities are the ability to apply rules and flexibly define reaction rate kinetics and constraints on nested species as well as species that are nested within others. An example model is presented that analyses the interplay of an intracellular control circuit with states at cell level, its relation to cell division, and connections to intercellular communication within a population of cells. The example is described in ML-Rules - a rule-based multi-level approach that has been realized within the plug-in-based modeling and simulation framework JAMES II. Conclusions Rule-based languages are a suitable starting point for developing a concise and compact language for multi-level modeling of cell biological systems. The combination of nesting species, assigning attributes, and constraining reactions according to these attributes is crucial in achieving the desired expressiveness. Rule schemata allow a concise and compact description of complex models. As a result, the presented approach facilitates developing and maintaining multi-level models that, for instance, interrelate intracellular and intercellular dynamics.

2011-01-01

213

Increased Number of Voltage Steps for Cascaded H-bridge Multilevel Inverters using 3-level Operation in each Half-cycle  

Microsoft Academic Search

Some renewable energy sources provide dc electrical energy. For example, photovoltaic sources, fuel cells, and the rectified output of some turbine driven sources, produce dc voltages. If the outputs of these devices are to be fed to the ac power grid, a power interface is required. The cascaded h-bridge multilevel inverter is an electronic interface that can connect multiple dc

A. Al-Judi; N. Benaifa; M. A. Rahim; E. Nowicki

2007-01-01

214

Multi -risk assessment at a national level in Georgia  

NASA Astrophysics Data System (ADS)

Work presented here was initiated by national GNSF project " Reducing natural disasters multiple risk: a positive factor for Georgia development " and two international projects: NATO SFP 983038 "Seismic hazard and Rusk assessment for Southern Caucasus-eastern Turkey Energy Corridors" and EMME " Earthquake Model for Middle east Region". Methodology for estimation of "general" vulnerability, hazards and multiple risk to natural hazards (namely, earthquakes, landslides, snow avalanches, flash floods, mudflows, drought, hurricanes, frost, hail) where developed for Georgia. The electronic detailed databases of natural disasters were created. These databases contain the parameters of hazardous phenomena that caused natural disasters. The magnitude and intensity scale of the mentioned disasters are reviewed and the new magnitude and intensity scales are suggested for disasters for which the corresponding formalization is not yet performed. The associated economic losses were evaluated and presented in monetary terms for these hazards. Based on the hazard inventory, an approach was developed that allowed for the calculation of an overall vulnerability value for each individual hazard type, using the Gross Domestic Product per unit area (applied to population) as the indicator for elements at risk exposed. The correlation between estimated economic losses, physical exposure and the magnitude for each of the six types of hazards has been investigated in detail by using multiple linear regression analysis. Economic losses for all past events and historical vulnerability were estimated. Finally, the spatial distribution of general vulnerability was assessed, and the expected maximum economic loss was calculated as well as a multi-risk map was set-up.

Tsereteli, Nino; Varazanashvili, Otar; Amiranashvili, Avtandil; Tsereteli, Emili; Elizbarashvili, Elizbar; Saluqvadze, Manana; Dolodze, Jemal

2013-04-01

215

Retail relationships and store loyalty: A multi-level perspective  

Microsoft Academic Search

An important factor in retail store loyalty is interpersonal relationships between retail salespeople and customers. However, relationships can also exist at the person-to-store level. This paper examines the linkages between trust in a salesperson, trust in the store, and repeat purchase intention. A model of store loyalty which includes relationships at both the person-to-store as well as person-to-person level is

Gerrard Macintosh; Lawrence S. Lockshin

1997-01-01

216

Ultrashort pulse propagation in multi-level media  

Microsoft Academic Search

We consider the propagation of short, intense laser pulses through media consisting of two-level and three-level atoms. We derive the coupled Maxwell-Bloch (MB) equations, which describe such propagation. Many different physical situations have been studied by analyzing various limiting cases of these equations. Most of the recent work has relied on steady-state or adiabatic assumptions to simplify the analysis of

B. David Clader

2008-01-01

217

Extreme multi-level anterior cervical discectomy and fusion.  

PubMed

The use of anterior cervical discectomy and fusion (ACDF) is a common procedure used to treat those who suffer from degenerative disc disease (DDD) of the cervical spine which may result in spondylolisthesis, spinal stenosis, disc herniation, nerve root and/or cord compression. ACDF is regularly used for the fusion of one to four cervical spine levels; however, the literature documenting the fusion of 5 or 6 levels is surprisingly lacking. In this retrospective review of our case series, we document two 5-level and two 6-level ACDF in elderly patients using custom made titanium fusion plates and patellar allograft bone for interbody placement without posterior fixation. The documentation of these long anterior constructs without supplemental posterior fixation or the use of a halo vest apparatus, but a simple neck collar for three months, is an important contribution to the literature illustrating that with utilization of appropriate technique, a high number of levels can be safely fused in the elderly patients necessitating this particular procedure. PMID:23957113

Morgan, Jeremy P; Asfora, Wilson T

2013-07-01

218

A Multi-source Report-level Simulator for Fusion Research  

Microsoft Academic Search

The Multi-source Report-level Simulator (MRS) is a tool developed by Veridian Systems as part of its Model- adaptive Multi-source Track Fusion (MMTF) effort under DARPA's DTT program. MRS generates simulated multisensor contact reports for GMTI, HUMINT, IMINT, SIGINT, UGS, and video. It contains a spatial editor for creating ground tracks along which vehicles move over the terrain. Vehicles can start,

Mark J. Carlotto

2003-01-01

219

Collaborative systems development in disaster relief: The impact of multi-level governance  

Microsoft Academic Search

Disaster management information systems for international humanitarian relief are developed in contexts involving local, national\\u000a and inter-governmental organizations together with local and international non-governmental organizations (NGOs). While the\\u000a multi-organizational nature of disaster response is known to create challenges for information systems development, to date,\\u000a less attention has been paid to their multi-level nature. This research sheds light on the implications

Edgar A. Maldonado; Carleen F. Maitland; Andrea Hoplight Tapia

2010-01-01

220

49 CFR Figure 2a to Subpart B of... - Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location...  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location Requirements-Ã...Subpart B of Part 238âExample of an Intermediate Level Seating Area of a Multi-Level Car Complying...

2012-10-01

221

49 CFR Figure 2b to Subpart B of... - Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location...  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location Requirements-Ã...Subpart B of Part 238âExample of an Intermediate Level Seating Area of a Multi-Level Car Complying...

2011-10-01

222

49 CFR Figure 2a to Subpart B of... - Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location...  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location Requirements-Ã...Subpart B of Part 238âExample of an Intermediate Level Seating Area of a Multi-Level Car Complying...

2011-10-01

223

49 CFR Figure 2b to Subpart B of... - Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location...  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Example of an Intermediate Level Seating Area of a Multi-Level Car Complying With Window Location Requirements-Ã...Subpart B of Part 238âExample of an Intermediate Level Seating Area of a Multi-Level Car Complying...

2012-10-01

224

Performance of multi level error correction in binary holographic meniory  

Microsoft Academic Search

At the Optical Computing Lab in the Jet Propulsion Laboratory (JPL) a binary holographic data storage system was designed and tested with methods of recording and retrieving the binary information. Levels of error correction were introduced to the system including pixel averaging, thresholding, and parity checks. Errors were artificially introduced into the binary holographic data storage system and were monitored

Jay C. Hanan; Tien-Hsin Chao; George F. Reyes

225

Hamilton's rule in multi-level selection models.  

PubMed

Hamilton's rule is regarded as a useful tool in the understanding of social evolution, but it relies on restrictive, overly simple assumptions. Here we model more realistic situations, in which the traditional Hamilton's rule generally fails to predict the direction of selection. We offer modifications that allow accurate predictions, but also show that these Hamilton's rule type inequalities do not predict long-term outcomes. To illustrate these issues we propose a two-level selection model for the evolution of cooperation. The model describes the dynamics of a population of groups of cooperators and defectors of various sizes and compositions and contains birth-death processes at both the individual level and the group level. We derive Hamilton-like inequalities that accurately predict short-term evolutionary change, but do not reliably predict long-term evolutionary dynamics. Over evolutionary time, cooperators and defectors can repeatedly change roles as the favored type, because the amount of assortment between cooperators changes in complicated ways due to both individual-level and group-level processes. The equation that governs the dynamics of cooperator/defector assortment is a certain partial differential equation, which can be solved numerically, but whose behaviour cannot be predicted by Hamilton's rules, because Hamilton's rules only contain first-derivative information. In addition, Hamilton's rules are sensitive to demographic fitness effects such as local crowding, and hence models that assume constant group sizes are not equivalent to models like ours that relax that assumption. In the long-run, the group distribution typically reaches an equilibrium, in which case Hamilton's rules necessarily become equalities. PMID:21820447

Simon, Burton; Fletcher, Jeffrey A; Doebeli, Michael

2011-07-30

226

An integrated approach for multi-level sample size determination  

SciTech Connect

Inspection procedures involving the sampling of items in a population often require steps of increasingly sensitive measurements, with correspondingly smaller sample sizes; these are referred to as multilevel sampling schemes. In the case of nuclear safeguards inspections verifying that there has been no diversion of Special Nuclear Material (SNM), these procedures have been examined often and increasingly complex algorithms have been developed to implement them. The aim in this paper is to provide an integrated approach, and, in so doing, to describe a systematic, consistent method that proceeds logically from level to level with increasing accuracy. The authors emphasize that the methods discussed are generally consistent with those presented in the references mentioned, and yield comparable results when the error models are the same. However, because of its systematic, integrated approach the proposed method elucidates the conceptual understanding of what goes on, and, in many cases, simplifies the calculations. In nuclear safeguards inspections, an important aspect of verifying nuclear items to detect any possible diversion of nuclear fissile materials is the sampling of such items at various levels of sensitivity. The first step usually is sampling by ``attributes`` involving measurements of relatively low accuracy, followed by further levels of sampling involving greater accuracy. This process is discussed in some detail in the references given; also, the nomenclature is described. Here, the authors outline a coordinated step-by-step procedure for achieving such multilevel sampling, and they develop the relationships between the accuracy of measurement and the sample size required at each stage, i.e., at the various levels. The logic of the underlying procedures is carefully elucidated; the calculations involved and their implications, are clearly described, and the process is put in a form that allows systematic generalization.

Lu, M.S.; Teichmann, T.; Sanborn, J.B.

1997-12-31

227

MultiLevel Complexities in Technological Development: Competing Strategies for Drug Discovery  

Microsoft Academic Search

\\u000a Drug development regularly has to deal with complex circumstances on two levels: the local level of pharmacological intervention\\u000a on specific target proteins, and the systems level of the effects of pharmacological intervention on the organism. Different\\u000a development strategies in the recent history of early drug development can be understood as competing attempts at coming to\\u000a grips with these multi-level complexities.

Matthias Adam

228

The Levels of Decision Making in Multi-Unit Community College Systems.  

ERIC Educational Resources Information Center

Describes a survey of 33 multi-unit community colleges designed to determine the relationship between (1) the levels at which decisions were made in nine selected areas; (2) institutional size and history; and (3) the number of system-level personnel. Discusses the implications of the findings for practice. (AYC)

Henry, Thomas C.; Creswell, John W.

1983-01-01

229

A Multi-Level Examination of College and Its Influence on Ecumenical Worldview Development  

ERIC Educational Resources Information Center

|This multi-level, longitudinal study investigated the ecumenical worldview development of 13,932 students enrolled in one of 126 institutions. Results indicated that the final hierarchical linear model, consisting of institution-and-student-level predictors as well as slopes explaining the relationships among some of these predictors, explained…

Mayhew, Matthew J.

2012-01-01

230

MultiLevel Parallelism for the Cardiac Bidomain Equations  

Microsoft Academic Search

Cardiovascular diseases are associated with high mortality rates in the globe. The development of new drugs, new medical equipment\\u000a and non-invasive techniques for the heart demand multidisciplinary efforts towards the characterization of cardiac anatomy\\u000a and function from the molecular to the organ level. Computational modeling has demonstrated to be a useful tool for the investigation\\u000a and comprehension of the complex

Carolina Ribeiro Xavier; Rafael Sachetto Oliveira; Vinicius Da Fonseca Vieira; Rodrigo Weber Dos Santos; Wagner Meira Jr.

2009-01-01

231

Embedding secret information into a dithered multi-level image  

Microsoft Academic Search

A coding scheme for secretly embedding character information into a dithered multilevel image is presented. This scheme inputs both a monotone image and secret information, which is converted to binary sequences, and it outputs a single dithered image. This image contains the character data of about 2 kByte in a dithered bilevel image 3 kByte in a dithered three-level image

Kiyoshi TANAKA; Yasuhiro NAKAMURA; Kineo MATSUI

1990-01-01

232

Multi-level damage detection with nonlinear ultrasonic methods  

NASA Astrophysics Data System (ADS)

The nonlinear ultrasonic method of second harmonic generation is used to detect multiple levels of damage on a single specimen. There is a breadth of research in the literature that measures the second harmonic and the resulting nonlinear parameter to monitor increasing amounts of uniform damage, but for this method to be applicable as an in situ technique, it must be able to scan an area of a structure with varying amounts of damage over a region. To investigate this, an aluminum alloy sample is shot-peened to two intensity levels along its length, to produce different sections of cold work and residual stress as a function of spatial location. Previous research has shown that the residual stress and cold work introduced in a material from shot peening causes an increase in the nonlinear parameter. Rayleigh waves are generated in the sample and the first and second harmonic amplitudes are measured at increasing propagation distances that encompass an undamaged section and two sections, each with different levels of shot peening. Results show that the nonlinear parameter increases as the Rayleigh wedge sensor is scanned over the shot peening sections.

Matlack, Kathryn H.; Kim, Jin-Yeon; Jacobs, Laurence J.; Qu, Jianmin

2013-01-01

233

Novel multilevel inverter carrier-based PWM method  

SciTech Connect

The advent of the transformerless multilevel inverter topology has brought forth various pulsewidth modulation (PWM) schemes as a means to control the switching of the active devices in each of the multiple voltage levels in the inverter. An analysis of how existing multilevel carrier-based PWM affects switch utilization for the different levels of a diode-clamped inverter is conducted. Two novel carrier-based multilevel PWM schemes are presented which help to optimize or balance the switch utilization in multilevel inverters. A 10-kW prototype six-level diode-clamped inverter has been built and controlled with the novel PWM strategies proposed in this paper to act as a voltage-source inverter for a motor drive.

Tolbert, L.M.; Habetler, T.G.

1999-10-01

234

Resolution and sensitivity of wafer-level multi-aperture cameras  

NASA Astrophysics Data System (ADS)

The scaling limits of multi-aperture systems have been widely discussed from an information-theoretical standpoint. While these arguments are valid as an upper limit, the real-world performance of systems for mobile devices remains restricted by optical aberrations. We argue that aberrations can be more easily controlled with certain architectures of multi-aperture systems, especially those manufactured on wafer scale (wafer-level optics, WLO). We complement our analysis with measurements of one single- and one multi-aperture WLO camera. We examine both sharpness and sensitivity, giving measurements of modulation transfer function and temporal noise, and showing that multi-aperture systems can indeed reduce size without compromising performance.

Oberdörster, Alexander; Lensch, Hendrik P. A.

2013-01-01

235

Modeling and Simulation of a Flexible Inverted Pendulum System  

Microsoft Academic Search

This paper presents a dynamic model of a planar flexible inverted pendulum system under the frame of multi-body dynamics by floating frame of reference formulation (FFRF). By proper simplification and linearization, the state space equation of the system was established for linear analysis and control design. The simulation method for such a coupled system by multi-body dynamics program was also

Jiali Tang; Gexue Ren

2009-01-01

236

A multi-level parcellation approach for brain functional connectivity analysis.  

PubMed

Most brain functional connectivity methods in fMRI require a brain parcellation into functionally homogeneous regions. In this work we propose a novel parcellation approach based on a spatial hierarchical clustering, that provides clusters within a multi-level framework. The method has the advantage of producing several brain parcellations rather than a single one from a fixed size-homogeneity criterion. Results obtained on real data demonstrate the relevance of the approach. Finally, a connectivity study shows the benefit of a prior multi-level parcellation of the brain. PMID:19964995

Karkar, Slim; Faisan, Sylvain; Thoraval, Laurent; Foucher, Jack R

2009-01-01

237

Implementing multi-qubit entanglement of two-level systems inside a superconducting phase qubit  

NASA Astrophysics Data System (ADS)

The interaction between a superconducting phase qubit and the two-level systems located inside the Josephson tunnel barrier is described by the XY model, which is naturally used to implement the i-SWAP gate. With this gate, we propose a scheme to efficiently generate multi-qubit entangled states of such two-level systems, including multipartite W state and cluster states. In particular, it is found that, with the help of the phase qubit, the entanglement witness can be used to efficiently detect the produced multi-qubit entangled states.

Yu, L. B.; Xue, Z.-Y.; Wang, Z. D.; Yu, Y.; Zhu, S. L.

2011-01-01

238

Metropolitan area income inequality and self-rated health—a multi-level study  

Microsoft Academic Search

We examined the association of income inequality measured at the metropolitan area (MA) and county levels with individual self-rated health. Individual-level data were drawn from 259,762 respondents to the March Current Population Survey in 1996 and 1998. Income inequality and average income were calculated from 1990 census data, the former using Gini coefficients. Multi-level logistic regression models were used. Controlling

Tony A. Blakely; Kimberly Lochner; Ichiro Kawachi

2002-01-01

239

Exploring dynamic multi-level linkages in inter-organizational networks  

Microsoft Academic Search

When an organization pursues the goals specific to its environment, networks are constructed to gain various resources from\\u000a other collaborators. However, most individual studies on inter-organizational network have taken a simplified view of relationships\\u000a among member organizations by focusing on a static and single level linkage. This paper proposes a multi-level approach to\\u000a integrate resource, organization and network levels and

Fangcheng Tang; Youmin Xi

2006-01-01

240

Changing Drug Users' Risk Environments: Peer Health Advocates as Multi-level Community Change Agents  

PubMed Central

Peer delivered, social oriented HIV prevention intervention designs are increasingly popular for addressing broader contexts of health risk beyond a focus on individual factors. Such interventions have the potential to affect multiple social levels of risk and change, including at the individual, network, and community levels, and reflect social ecological principles of interaction across social levels over time. The iterative and feedback dynamic generated by this multi-level effect increases the likelihood for sustained health improvement initiated by those trained to deliver the peer intervention. The Risk Avoidance Partnership (RAP), conducted with heroin and cocaine/crack users in Hartford, Connecticut, exemplified this intervention design and illustrated the multi-level effect on drug users' risk and harm reduction at the individual level, the social network level, and the larger community level. Implications of the RAP program for designing effective prevention programs and for analyzing long-term change to reduce HIV transmission among high-risk groups are discussed from this ecological and multi-level intervention perspective.

Weeks, Margaret R.; Convey, Mark; Dickson-Gomez, Julia; Li, Jianghong; Radda, Kim; Martinez, Maria; Robles, Eduardo

2010-01-01

241

Multi-level step and flash imprint lithography for direct patterning of dielectrics  

NASA Astrophysics Data System (ADS)

The dual damascene process used to generate copper interconnects requires many difficult processing steps. Back End Of Line (BEOL) processing using Step and Flash Imprint Lithography (SFIL) on a directly patternable dielectric material can dramatically reduce the number of processing steps. By using multi-level SFIL rather than photolithography, two levels of interconnect structure (trench and corresponding via) can be patterned simultaneously. In addition, the imprinted material can be a imprintable dielectric precursor rather than a resist, further reducing the total number of steps in the dual damascene process. This paper presents progress towards integrating multi-level SFIL into a copper CMP process flow at ATDF, Inc. in Austin, Texas. Until now, work has focused on multi-level imprint process development. This report focuses on the development of new imprintable dielectric precursors for use with the dual damascene imprint process. SFIL compatible dielectric precursors were synthesized and characterized for integration into the ATDF copper CMP process flow. SFIL requires properties not found in currently available semiconductor dielectrics such as low viscosity and rapid photo-induced polymerization. Inorganic/organic hybrid materials derived from sol-gel chemistry and polyhedral oligomeric silsesquioxane (POSS) structures show promise for this application. The properties of three different dielectric layers are compared. The viability of each material as an interlayer dielectric is discussed and the results of multi-level patterning, metal fill, and polish are shown.

Palmieri, Frank; Stewart, Michael D.; Wetzel, Jeff; Hao, Jianjun; Nishimura, Yukio; Jen, Kane; Flannery, Colm; Li, Bin; Chao, Huang-Lin; Young, Soo; Kim, Woon C.; Ho, Paul S.; Willson, C. G.

2006-04-01

242

Power inverter topologies for photovoltaic modules-a review  

Microsoft Academic Search

This review-paper focuses on the latest development of inverters for photovoltaic AC-modules. The power range for these inverters is usually within 90 Watt to 500 Watt, which covers the most commercial photovoltaic-modules. Self-commutated inverters have replaced the grid-commutated ones. The same is true for the bulky low-frequency transformers versus the high-frequency transformers, which are used to adapt the voltage level.

Soeren Baekhoej Kjaer; John K. Pedersen; Frede Blaabjerg

2002-01-01

243

A Multi-Level Assessment of a Program to Teach Medical Students to Teach  

ERIC Educational Resources Information Center

|Few longitudinal programs exist to teach senior students (MS4s) to be teachers, nor have there been any reports of comprehensive program evaluation in this area. The primary objectives of this study were to describe our ongoing faculty development effort and to develop a multi-level program evaluation, using Dixon's model. The TALKS (Teaching and…

Blatt, Benjamin; Greenberg, Larrie

2007-01-01

244

Multi-Period Network Interdiction Problems with Applications to City-Level Drug Enforcement  

Microsoft Academic Search

We consider a new class of multi-period network interdiction problems that focus on scheduling the activities of law enforcement in order to successfully interdict criminals in an illegal drug supply chain. This class of problems possesses several novel features for interdiction problems that were motivated through collaborations with city-level drug enforcement officials. These features include modeling the temporal aspects of

Ajay Malaviya; Chase Rainwater; Thomas C. Sharkey

2011-01-01

245

Software Architecture for a Multi-Level Real-Time System.  

National Technical Information Service (NTIS)

When a real time system has a mixed set of time critical tasks, including tasks with hard deadlines and tasks with soft deadlines, managing a mixed set of tasks in a timely manner becomes harder and requires a multi-level architecture. This thesis concent...

O. Korkut

1998-01-01

246

Tree Level Vacuum Stability in Multi Higgs Doublet Models: A Cumbersome Analysis?  

Microsoft Academic Search

We introduce a simple approach to obtain the constraint for multi Higgs doublet potentials to be stable, i.e. to have tree-level\\u000a vacuum stability. We use the methodology for some special cases with three doublets.

S. Zarrinkamar; H. Hassanabadi; A. A. Rajabi

2010-01-01

247

Evaluating ammonia toxicity in sewage effluent to stream macroinvertebrates: I. A multi-level approach  

Microsoft Academic Search

A multi-level approach incorporating instream biological response, water quality, and toxicity testing was used to evaluate the toxicity of ammonia in sewage effluent to macroinvertebrates in two Ozark border streams. Macroinvertebrate community compositions at sites upstream from effluent discharge were most similar, while communities at upstream vs downstream sites were least similar. Upstream sites had abundant mayflies, blackflies, and caddisflies,

D. P. Monda; D. L. Galat; S. E. Finger

1995-01-01

248

Perceived risk and outcome differences in multi-level service relationships  

Microsoft Academic Search

Service relationships are often complex, involving multi-level relationships. Customers can have relationships with the firm and interpersonal relationships with service personnel that vary in terms of strength and intensity. A study was designed to examine the relationship between perceived risk and type of service relationship. It also examined outcomes differences between different types of service relationships. The results suggest that

Gerrard Macintosh

2002-01-01

249

Contested multi?level governance: Merseyside and the European structural funds  

Microsoft Academic Search

This paper critically explores the problems and tensions that occur within a multi?level governance structure. It examines the (conflictual) relationships between the European Commission (EC), the UK Government, and regional and local actors. The case study is Merseyside's European Union Objective I Programme, with particular reference to the Pathways to Integration initiative in the Borough of Knowsley. It traces the

Philip Boland

1999-01-01

250

GROUND WATER MONITORING AND SAMPLING: MULTI-LEVEL VERSUS TRADITIONAL METHODS WHATS WHAT?  

EPA Science Inventory

After years of research and many publications, the question still remains: What is the best method to collect representative ground water samples from monitoring wells? Numerous systems and devices are currently available for obtaining both multi-level samples as well as traditi...

251

Multi-Level Research on Youth Participation in the Haitian Reconstruction  

ERIC Educational Resources Information Center

|Research in comparative and international education routinely encounters exceptional research conditions. In this article, the author explores the particular issues he faced in his research on multi-level youth programs of the Haitian reconstruction. Through a vertical analysis of internationally sponsored programs, this study required special…

Pluim, Gary W. J.

2012-01-01

252

Transatlantic flight fights: multi-level governance, actor entrepreneurship and international anti-terrorism cooperation  

Microsoft Academic Search

Anti-terrorism cooperation has sparked a series of transatlantic conflicts. Many popular accounts look to differing policy preferences between US and European capitals to explain these disagreements. This article, by contrast, contends that these disputes are often rooted in internal multi-level governance processes within Europe that present different opportunity structures for actors to influence international debates. The case of airline passenger

Abraham Newman

2011-01-01

253

Safety climate in conditions of construction subcontracting: a multi?level analysis  

Microsoft Academic Search

A multi?level safety climate model was tested in the Australian construction industry. Subcontracted workers’ perceptions of the organizational safety response (OSR) and supervisor safety response (SSR) in their own organization and that of the principal contractor were measured using a safety climate survey administered at a large hospital construction project in Melbourne. One hundred and fourteen construction workers completed the

Helen Clare Lingard; Tracy Cooke; Nick Blismas

2010-01-01

254

Multi-Level Assessment of Scientific Content Knowledge Gains Associated with Socioscientific Issues-Based Instruction  

ERIC Educational Resources Information Center

|This study explored the impact of using a socioscientific issue (SSI) based curriculum on developing science content knowledge. Using a multi-level assessment design, student content knowledge gains were measured before and after implementation of a three-week unit on global warming (a prominent SSI) that explored both the relevant science…

Klosterman, Michelle L.; Sadler, Troy D.

2010-01-01

255

Multi Item Single Level Capacitated Dynamic Lotsizing Heuristics: A Computational Comparison (Part I: Static Case)  

Microsoft Academic Search

The multi item single level capacitated dynamic lotsizing problem consists of scheduling N items over a horizon of T periods. Demands are given and should be satisfied without backlogging. The objective is to minimize the sum of setup costs and inventory holding costs over the horizon subject to a constraint on total capacity in each period. Three simple heuristics from

Johan Maes; Luk N. Van Wassenhove

1986-01-01

256

PROPORTION OF MODERATELY EXERCISING INDIVIDUALS RESPONDING TO LOW-LEVEL, MULTI-HOUR OZONE EXPOSURE  

EPA Science Inventory

The purpose of this study was to describe the proportion of moderately exercising individuals experiencing significant respiratory responses to low-level, multi-hour ozone exposure as a function of ozone concentration and exposure duration. ixty-eight healthy, nonsmoking adults, ...

257

Markets, Resources, and Their Interplay: A MultiLevel Random Coefficient Model Approach  

Microsoft Academic Search

Looking at the micro behaviors of firms, this study analyzes the roles of markets and resources and examines how these factors influence sales performance and decisions regarding market selection. This approach addresses how resources factors, coordinated with markets, affect sales performances differently across product segments by using the multi-level random coefficient model. It suggests the importance of developing a business

Chang Hoon Oh

258

Resonant snubber inverter  

DOEpatents

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

Lai, Jih-Sheng (Knoxville, TN); Young, Sr., Robert W. (Oak Ridge, TN); Chen, Daoshen (Knoxville, TN); Scudiere, Matthew B. (Oak Ridge, TN); Ott, Jr., George W. (Knoxville, TN); White, Clifford P. (Knoxville, TN); McKeever, John W. (Oak Ridge, TN)

1997-01-01

259

Single-electron inverter  

NASA Astrophysics Data System (ADS)

A single-electron inverter was fabricated that switches from a high output to a low output when a fraction of an electron is added to the input. For the proper operation of the inverter, the two single-electron transistors that make up the inverter must exhibit voltage gain. Voltage gain was achieved by fabricating a combination of parallel-plate gate capacitors and small tunnel junctions in a two-layer circuit. Voltage gain of 2.6 was attained at 25 mK and remained larger than one for temperatures up to 140 mK. The temperature dependence of the gain agrees with the orthodox theory of single-electron tunneling.

Heij, C. P.; Hadley, P.; Mooij, J. E.

2001-02-01

260

Resonant snubber inverter  

DOEpatents

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 14 figs.

Lai, J.S.; Young, R.W. Sr.; Chen, D.; Scudiere, M.B.; Ott, G.W. Jr.; White, C.P.; McKeever, J.W.

1997-06-24

261

Laser printing of conformal and multi-level 3D interconnects  

NASA Astrophysics Data System (ADS)

A crucial challenge in three-dimensional multi-chip assemblies is to establish electrical connections between discrete devices. Here, we apply laser printing of congruent voxels of silver nanopaste for the fabrication of conformal and 3D multi-level interconnects. By controlling laser fluence, various 3D electrodes including freestanding tabs and side contacts over vertical walls can be directly printed without the need for sacrificial layers, chemical etching or electroplating. The electrical characteristics of the printed interconnects are similar to those currently in use by the semiconductor industry. These results are a promising step forward in the generation of customized interconnects for 3D microelectronics.

Kim, H.; Duocastella, M.; Charipar, K. M.; Auyeung, R. C. Y.; Piqué, A.

2013-08-01

262

SEEPAGE/INVERT INTERACTIONS  

SciTech Connect

As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for water entering the drift and reacting with the invert materials is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction, and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE), Revision 2 (NRC 1999). This AMR also seeks to: (1) Develop a logical conceptual model for physical/chemical interactions between seepage and the invert materials; (2) screen potential processes and reactions that may occur between seepage and invert to evaluate the potential consequences of the interactions; and (3) outline how seepage/invert processes may be quantified. This document provides the conceptual framework for screening out insignificant processes and for identifying and evaluating those seepage/invert interactions that have the potential to be important to subsequent PAO analyses including the Engineered Barrier System (EBS) physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. Additionally, the concepts discussed within this report may also apply to certain near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts. The seepage/invert interactions will not directly affect any principal factors.

P.S. Domski

2000-04-14

263

Multi level boarding bi-level commuter car for North American market  

Microsoft Academic Search

A multilevel boarding version (low and high level platform boarding) of the bi-level commuter car for the North American market has been developed. The major challenge of the bi-level carbody design with the high and lower boarding access, i.e., passenger doors, is the side sill interruption at the lower level. The side sill is the main structural member (beside the

R. Sarunac; T. B. Soesbee; S.-I. Ohta

2004-01-01

264

Multi-domain, Higher Order Level Set Scheme for 3D Image Segmentation on the GPU.  

PubMed

Level set method based segmentation provides an efficient tool for topological and geometrical shape handling. Conventional level set surfaces are only C(0) continuous since the level set evolution involves linear interpolation to compute derivatives. Bajaj et al. present a higher order method to evaluate level set surfaces that are C(2) continuous, but are slow due to high computational burden. In this paper, we provide a higher order GPU based solver for fast and efficient segmentation of large volumetric images. We also extend the higher order method to multi-domain segmentation. Our streaming solver is efficient in memory usage. PMID:23028208

Sharma, Ojaswa; Zhang, Qin; Anton, François; Bajaj, Chandrajit

2010-06-13

265

Design of Incoming Quality Level, Process Quality Level and Optimal Interrelated Lot-by-Lot Single Sampling Plans for a Single Product Multi-Component Multi-Stage Manufacturing System. A User's Manual for DMQS.  

National Technical Information Service (NTIS)

This is a user's manual for computer program for the design of incoming quality level, process quality level and optimal interrelated lot-by-lot single sampling plans for a single-product multi-component multi-stage manufacturing system. Reference: Hassan...

M. Z. Hassan T. W. Knowles R. Subramaniam A. Manaspiti P. Pantumsinchai

1979-01-01

266

Optimization for Multi-Resource Allocation and Leveling Based on a Self-Adaptive Ant Colony Algorithm  

Microsoft Academic Search

In this paper, Optimization of multi-resource allocation and leveling is studied. A mathematical model of multi-resource allocation and leveling problem for bi-objective and multi-restricted condition is set up. A self-adaptive ant colony algorithm for the problem is presented. According to the topological relations of network graph, we develop the method of serial scheduling generation scheme of the tour network of

Zhengjia Wu; Liping Zhang; Ying Wang; Kui Wang

2008-01-01

267

Multi-level diffractive optical elements produced by excimer laser ablation of sol-gel.  

PubMed

Material ablation by excimer laser micromachining is a promising approach for structuring sol-gel materials as we demonstrate in the present study. Using the well-known direct etching technique, the behaviour of different hybrid organic/inorganic self-made sol-gel materials is examined with a KrF* laser. Ablated depths ranging from 0.1 to 1.5 microm are obtained with a few laser pulses at low fluence (< 1 J/cm(2)). The aim is to rapidly transfer surface relief multi-level diffractive patterns in such a substrate, without intermediate steps. The combination with the 3D profilometry technique of coherence probe microscopy permits to analyse the etching process with the aim of producing multi-level Diffractive Optical Elements (DOE). Examples of four-level DOEs with 10 microm square elementary cells are presented, as well as their laser reconstructions in the infrared. PMID:18773015

Neiss, Estelle; Flury, Manuel; Mager, Loïc; Rehspringer, Jean-Luc; Fort, Alain; Montgomery, Paul; Gérard, Philippe; Fontaine, Joël; Robert, Stéphane

2008-09-01

268

A novel method for a multi-level hierarchical composite with brick-and-mortar structure  

NASA Astrophysics Data System (ADS)

The fascination for hierarchically structured hard tissues such as enamel or nacre arises from their unique structure-properties-relationship. During the last decades this numerously motivated the synthesis of composites, mimicking the brick-and-mortar structure of nacre. However, there is still a lack in synthetic engineering materials displaying a true hierarchical structure. Here, we present a novel multi-step processing route for anisotropic 2-level hierarchical composites by combining different coating techniques on different length scales. It comprises polymer-encapsulated ceramic particles as building blocks for the first level, followed by spouted bed spray granulation for a second level, and finally directional hot pressing to anisotropically consolidate the composite. The microstructure achieved reveals a brick-and-mortar hierarchical structure with distinct, however not yet optimized mechanical properties on each level. It opens up a completely new processing route for the synthesis of multi-level hierarchically structured composites, giving prospects to multi-functional structure-properties relationships.

Brandt, Kristina; Wolff, Michael F. H.; Salikov, Vitalij; Heinrich, Stefan; Schneider, Gerold A.

2013-07-01

269

The crescentic inverted scarf osteotomy.  

PubMed

A hybrid procedure combining the inverted scarf and crescentic osteotomies is presented. This procedure may serve as a viable modification of the inverted scarf bunionectomy for those surgeons desiring true rotational correction of high intermetatarsal angles. PMID:12567369

O'Brien, Todd

270

Advanced Inverter Technology.  

National Technical Information Service (NTIS)

APL has three existing series resonant inverter-based power converters: Power--10kW, 5kW, 200kW, Topology--dc/dc 1/2 Bridge, ac/dc Full Bridge, dc/dc Dual Full Bridge, the control and protection circuits are different for the three units. The purpose of t...

R. L. Moser

1984-01-01

271

Optimal load balancing leveling method for multi-leg flexible platforms  

NASA Astrophysics Data System (ADS)

The working platforms supported with multiple extensible legs must be leveled before they come into operation. Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs, the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads. These problems make it quite complex and time consuming to level such a multi-leg platform. Based on rigid body kinematics, an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform, then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs. Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration, an optimal balancing legs' loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem. By taking advantage of the concept of supporting stiffness matrix, a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform. At the end, with the concept of supporting stiffness matrix and static transmissibility matrix, an optimal load balancing leveling method is proposed to achieve geometric leveling and legs' loads balancing simultaneously. Three numerical examples are given out to illustrate the performance of proposed methods. This paper proposes a method which can effectively quantify all of the legs' extension at the same time, achieve geometric leveling and legs' loads balancing simultaneously. By using the proposed methods, the stability, precision and efficiency of auto-leveling control process can be improved.

Gang, Xianyue; Chai, Shan

2013-09-01

272

Advanced Modular Inverter Technology Development  

Microsoft Academic Search

Electric and hybrid-electric vehicle systems require an inverter to convert the direct current (DC) output of the energy generation\\/storage system (engine, fuel cells, or batteries) to the alternating current (AC) that vehicle propulsion motors use. Vehicle support systems, such as lights and air conditioning, also use the inverter AC output. Distributed energy systems require an inverter to provide the high

Adam Szczepanek

2006-01-01

273

Inverted bucket SS straps help save $500,000\\/yr  

Microsoft Academic Search

This article focuses on a solution to a chemical plant's problem with energy inefficient steam traps. The problem was solved with the installation of inverted bucket steam traps which were designed for energy-efficient, reliable operation over a wide range of service conditions. The steam trap failure level was reduced from 38% to only 2-5% after the stainless steel inverted bucket

D. Koepp; A. Gaines

1982-01-01

274

Cascaded H-bridge multilevel inverter using trinary dc sources  

Microsoft Academic Search

To obtain a large number of output voltage levels with minimum devices, it presents a cascaded H-bridge multilevel inverter employing trinary dc sources. The proposed inverter can synthesize high quality output voltage near to sinusoidal waves. The circuit configuration is simple and easy to control. The operational principle and key waveforms are illustrated and analyzed. To verify the performance of

Cheol-soon Kwon; Won-kyun Choi; Un-Taek Hong; Seok-Hwan Hyun; Feel-soon Kang

2010-01-01

275

Parallel operation of voltage source inverters with minimal intermodule reactors  

Microsoft Academic Search

Realization of large horsepower motor drives using parallel-connected voltage source inverters rated at smaller power levels would be highly desirable. A robust technique for such a realization would result in several benefits including modularity, ease of maintenance, n+1 redundancy, reliability, etc. Techniques for parallel operation of voltage source inverters with relatively large load inductance have been well established in the

Bin Shi; Giri Venkataramanan

2004-01-01

276

Multi-level conduction in NiO resistive memory device prepared by solution route  

NASA Astrophysics Data System (ADS)

In this paper, we present nickel oxide (NiO) thin film bipolar non-volatile resistive memory device with multi-level conduction prepared by solution route at room temperature. The fabricated device with structure Al/NiO/ITO exhibits excellent switching parameters, such as a stable resistance value in both ON and OFF states for over 10?000 s (retention) and 105 switching cycles of memory operation (endurance). Stable multi-level conductance states are observed in the memory device, which could be exploited for a multilevel-cell programming scheme. The switching mechanism in the resistive memory device is discussed based on the formation/dissolution of conductive filaments.

Kannan, V.; Senthilkumar, V.; Rhee, J. K.

2013-03-01

277

Rapid prototyping of multi-level polydimethylsiloxane-based microfluidic devices  

NASA Astrophysics Data System (ADS)

There has been considerable progress in the development of micro-fabricated systems for the field of chemical and biological sciences. Much development has been driven by the need of miniaturized systems that allow cost-effective and rapid processing of samples at the point of need. In this work, we investigate the application practicality of Objet Eden500VTMPolyjet as a rapid and economical tool for multi-level microfluidic device rapid prototyping. The Polyjet is a commercial system that utilizes ink-jet technology to print 3-dimensional structures with photopolymer materials. The reproducing capability of the Polyjet system in term of lateral and vertical resolutions, aspect ratio and smoothness of fabricated structures are investigated. In addition, the capability of the Polyjet is demonstrated by fabricating three different devices including: 1) multi-level microfluidic chip for two-step gene synthesis, 2) a fluidic component for micro/macro fluidic interfacing, and 3) PDMS-based microlens.

Cheong, Wai Chye; Kuan, Yoke Kong; Li, Mo-Huang; Ying, Jackie Y.

2008-12-01

278

Multi-level ground glass nodule detection and segmentation in CT lung images.  

PubMed

Early detection of Ground Glass Nodule (GGN) in lung Computed Tomography (CT) images is important for lung cancer prognosis. Due to its indistinct boundaries, manual detection and segmentation of GGN is labor-intensive and problematic. In this paper, we propose a novel multi-level learning-based framework for automatic detection and segmentation of GGN in lung CT images. Our main contributions are: firstly, a multi-level statistical learning-based approach that seamlessly integrates segmentation and detection to improve the overall accuracy for GGN detection (in a subvolume). The classification is done at two levels, both voxel-level and object-level. The algorithm starts with a three-phase voxel-level classification step, using volumetric features computed per voxel to generate a GGN class-conditional probability map. GGN candidates are then extracted from this probability map by integrating prior knowledge of shape and location, and the GGN object-level classifier is used to determine the occurrence of the GGN. Secondly, an extensive set of volumetric features are used to capture the GGN appearance. Finally, to our best knowledge, the GGN dataset used for experiments is an order of magnitude larger than previous work. The effectiveness of our method is demonstrated on a dataset of 1100 subvolumes (100 containing GGNs) extracted from about 200 subjects. PMID:20426175

Tao, Yimo; Lu, Le; Dewan, Maneesh; Chen, Albert Y; Corso, Jason; Xuan, Jianhua; Salganicoff, Marcos; Krishnan, Arun

2009-01-01

279

MultiLevel Intervention to Prevent Influenza Infections in Older Low Income and Minority Adults  

Microsoft Academic Search

In this paper we describe a successful multi-level participatory intervention grounded in principles of individual and group\\u000a empowerment, and guided by social construction theory. The intervention addressed known and persistent inequities in influenza\\u000a vaccination among African American and Latino older adults, and associated infections, hospitalizations and mortality. It\\u000a was designed to increase resident ability to make informed decisions about vaccination,

Jean J. Schensul; Kim Radda; Emil Coman; Elsie Vazquez

2009-01-01

280

A MultiLevel Assessment of a Program to Teach Medical Students to Teach  

Microsoft Academic Search

Few longitudinal programs exist to teach senior students (MS4s) to be teachers, nor have there been any reports of comprehensive\\u000a program evaluation in this area. The primary objectives of this study were to describe our ongoing faculty development effort\\u000a and to develop a multi-level program evaluation, using Dixon’s model. The TALKS (Teaching and Learning Communication Skills)\\u000a program is a senior

Benjamin Blatt; Larrie Greenberg

2007-01-01

281

Capacitor clamped multi-level matrix converter: Space vector modulation and capacitor balance  

Microsoft Academic Search

The matrix converter is an array of controlled bi-directional semi-conductor switches that allows direct AC-AC conversion without an intermediate DC link. This converter has several attractive features that have been investigated in the last two decades. Multi level converter technology has become increasingly popular in recent years due to high power quality, high-voltage capability, low switching losses, and low EMI

Xu Lie; Jon C. Clare; Patrick W. Wheeler; Lee Empringham

2008-01-01

282

Energy-Aware Data Compression for MultiLevel Cell (MLC) Flash Memory  

Microsoft Academic Search

We discover significant value-dependent programming energy variations in multi-level cell (MLC) flash memories, and introduce an energy-aware data compression method that minimizes the flash programming energy rather than the size of the compressed data. We express energy-aware data compression as an entropy coding with unequal bit-pattern costs. Deploying a probabilistic approach, we derive the energy-optimal bit-pattern probabilities and the expected

Yongsoo Joo; Youngjin Cho; Donghwa Shin; Naehyuck Chang

2007-01-01

283

Energy-aware data compression for multi-level cell (MLC) flash memory  

Microsoft Academic Search

We discover significant value-dependent programming energy variations in multi-level cell (MLC) flash memories, and introduce an energy-aware data compression method that minimizes the flash programming energy rather than the size of the compressed data. We express energy-aware data compression as an entropy coding with unequal bit-pattern costs. Deploying a probabilistic approach, we derive the energy-optimal bit-pattern probabilities and the expected

Yongsoo Joo; Youngjin Cho; Donghwa Shin; Naehyuck Chang

2007-01-01

284

A unique, multi-level-team microfabrication learning environment at Boise State University  

Microsoft Academic Search

A unique, multi-level-team microfabrication learning environment involving students and faculty from both Engineering and Applied Technology has been established at Boise State University. This two-semester laboratory sequence, which begins with safety\\/tool training, progresses to process modules, and ends with an integrated four-mask PMOS process, is team-taught by faculty from both the Electrical Engineering and the Semiconductor Technology programs. Although these

Stephen Parke; Jim Jozwiak

2001-01-01

285

What is the value of human resource certification? A multi-level framework for research  

Microsoft Academic Search

We make a contribution to narrowing the science–practice gap by adopting a multi-level theory-based approach to investigating an important issue for practitioners in human resource management: human resource (HR) certification. Despite the facts that more than 150,000 individuals in more than 70 countries have become certified and that HR certification has turned into a million-dollar industry, there is no scholarly

Mark L. Lengnick-Hall; Herman Aguinis

286

Mining Human Location-Routines using a MultiLevel Approach to Topic Modeling  

Microsoft Academic Search

In this work we address the problem of modeling varying time duration sequences for large-scale human routine discovery from cellphone sensor data using a multi-level approach to probabilistic topic models. We use an unsupervised learning approach that discovers human routines of varying durations ranging from half-hourly to several hours. Our methodology can handle large sequence lengths based on a principled

Katayoun Farrahi; Daniel Gatica-Perez

2010-01-01

287

Multi-level non-LTE radiative transfer in expanding shells.  

NASA Astrophysics Data System (ADS)

The author presents a new and general method for the solution of complex multi-level non-LTE radiative transfer problems both in static and moving media. The method is based on the approximate ?-iteration method and is a direct extension of the scheme devised by Rybicki and Hummer (1991). The author demonstrates that this method is able to treat both active continua and overlapping lines with relatively small amount of computer resources. Some simplified test cases are presented and discussed.

Hauschildt, P. H.

1993-09-01

288

Multi-classifier Scheme with Low-Level Visual Feature for Adult Image Classification  

Microsoft Academic Search

\\u000a As the usage and accessing of children to the web resources with porn images contain is growing, requirement of methods with\\u000a high accuracy to detect and block adult images is a necessity. In this paper, a novel multi-classifier scheme is proposed\\u000a based on low-level feature to exploit of advantages in classifier ensemble for achieving better accuracy compared to single\\u000a classifier

Mohammadmehdi Bozorgi; Mohd Aizaini Maarof; Lee Zhi Sam

289

Access to mammography screening in a large urban population: a multi-level analysis  

Microsoft Academic Search

Objective  To understand area-based sociodemographics, physician and medical practice characteristics, and community indicators associated\\u000a with mammography use in Los Angeles County. An earlier multi-level analysis by Gumpertz et al. found that distance to the\\u000a nearest mammography facility helped explain the higher proportion of Latinas diagnosed with late stage breast cancer compared\\u000a with non-Latina Whites in Los Angeles County. Our study examined

Stephen C. Meersman; Nancy Breen; Linda W. Pickle; Helen I. Meissner; Paul Simon

2009-01-01

290

Macro-level gender equality and alcohol consumption: a multi-level analysis across U.S. States.  

PubMed

Higher levels of women's alcohol consumption have long been attributed to increases in gender equality. However, only limited research examines the relationship between gender equality and alcohol consumption. This study examined associations between five measures of state-level gender equality and five alcohol consumption measures in the United States. Survey data regarding men's and women's alcohol consumption from the 2005 Behavioral Risk Factor Surveillance System were linked to state-level indicators of gender equality. Gender equality indicators included state-level women's socioeconomic status, gender equality in socioeconomic status, reproductive rights, policies relating to violence against women, and women's political participation. Alcohol consumption measures included past 30-day drinker status, drinking frequency, binge drinking, volume, and risky drinking. Other than drinker status, consumption is measured for drinkers only. Multi-level linear and logistic regression models adjusted for individual demographics as well as state-level income inequality, median income, and % Evangelical Protestant/Mormon. All gender equality indicators were positively associated with both women's and men's drinker status in models adjusting only for individual-level covariates; associations were not significant in models adjusting for other state-level characteristics. All other associations between gender equality and alcohol consumption were either negative or non-significant for both women and men in models adjusting for other state-level factors. Findings do not support the hypothesis that higher levels of gender equality are associated with higher levels of alcohol consumption by women or by men. In fact, most significant findings suggest that higher levels of equality are associated with less alcohol consumption overall. PMID:22521679

Roberts, Sarah C M

2012-04-04

291

Cross-Ontology Multi-level Association Rule Mining in the Gene Ontology  

PubMed Central

The Gene Ontology (GO) has become the internationally accepted standard for representing function, process, and location aspects of gene products. The wealth of GO annotation data provides a valuable source of implicit knowledge of relationships among these aspects. We describe a new method for association rule mining to discover implicit co-occurrence relationships across the GO sub-ontologies at multiple levels of abstraction. Prior work on association rule mining in the GO has concentrated on mining knowledge at a single level of abstraction and/or between terms from the same sub-ontology. We have developed a bottom-up generalization procedure called Cross-Ontology Data Mining-Level by Level (COLL) that takes into account the structure and semantics of the GO, generates generalized transactions from annotation data and mines interesting multi-level cross-ontology association rules. We applied our method on publicly available chicken and mouse GO annotation datasets and mined 5368 and 3959 multi-level cross ontology rules from the two datasets respectively. We show that our approach discovers more and higher quality association rules from the GO as evaluated by biologists in comparison to previously published methods. Biologically interesting rules discovered by our method reveal unknown and surprising knowledge about co-occurring GO terms.

Manda, Prashanti; Ozkan, Seval; Wang, Hui; McCarthy, Fiona; Bridges, Susan M.

2012-01-01

292

A multilevel voltage-source inverter with separate dc sources for static var generation  

SciTech Connect

A new multilevel voltage-source inverter with a separate dc sources is proposed for high-voltage, high-power applications, such as flexible ac transmission systems (FACTS) including static var generation (SVG), power line conditioning, series compensation, phase shifting, voltage balancing, fuel cell and photovoltaic utility systems interfacing, etc. The new M-level inverter consists of (M-1)/2 single phase full bridges in which each bridge has its own separate dc source. This inverter can generate almost sinusoidal waveform voltage with only one time switching per cycle as the number of levels increases. It can solve the problems of conventional transformer-based multipulse inverters and the problems of the multilevel diode-clamped inverter and the multilevel flying capacitor inverter. To demonstrate the superiority of the new inverter, a SVG system using the new inverter topology is discussed through analysis, simulation and experiment.

Peng, Fang Zheng [Tennessee Univ., Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States); Lai, Jih-Sheng; McKeever, J.; VanCoevering, J. [Oak Ridge National Lab., TN (United States)

1995-09-01

293

Inverted Trough Case Exercise  

NSDL National Science Digital Library

This exercise flollows the progression of a winter weather event across the Central Plains states beginning 1200 UTC on 7 March 1999. Each forecast question is accompanied by Eta model data and includes a forecast discussion by Phil Schumacher, NWS Sioux Falls, South Dakota. This exercise compliments the Webcast, Inverted Troughs and their Associated Precipitation Regimes, based on a presentation by Phil Schumacher at the MSC Winter Weather Course, December 2002, in Boulder Colorado.

Spangler, Tim

2004-01-01

294

Multi-Level Determinants of Parasitic Fly Infection in Forest Passerines  

PubMed Central

The study of myiasis is important because they may cause problems to the livestock industry, public health, or wildlife conservation. The ecology of parasitic dipterans that cause myiasis is singular, as they actively seek their hosts over relatively long distances. However, studies that address the determinants of myiasis dynamics are very scarce. The genus Philornis include species that may be excellent models to study myiasis ecology, as they exclusively parasitize bird nestlings, which stay in their nests until they are fully fledged, and larvae remain at the point of entry until the parasitic stage is over, thus allowing the collection of sequential individual-level infection data from virtually all the hosts present at a particular area. Here we offer a stratified multi-level analysis of longitudinal data of Philornis torquans parasitism in replicated forest bird communities of central Argentina. Using Generalized Linear Models and Generalized Linear Mixed Models and an information theory approach for model selection, we conducted four groups of analyses, each with a different study unit, the individual, the brood, the community at a given week, and the community at a given year. The response variable was larval abundance per nestling or mean abundance per nestling. At each level, models included the variables of interest of that particular level, and also potential confounders and effect modifiers of higher levels. We found associations of large magnitude at all levels, but only few variables truly governed the dynamics of this parasite. At the individual level, the infection was determined by the species and the age of the host. The main driver of parasite abundance at the microhabitat level was the average height of the forest, and at the community level, the density of hosts and prior rainfall. This multi-level approach contributed to a better understanding of the ecology of myiasis.

Manzoli, Dario Ezequiel; Antoniazzi, Leandro Raul; Saravia, Maria Jose; Silvestri, Leonardo; Rorhmann, David; Beldomenico, Pablo Martin

2013-01-01

295

Advanced inverter technology  

NASA Astrophysics Data System (ADS)

APL has three existing series resonant inverter-based power converters: Power--10kW, 5kW, 200kW, Topology--dc/dc 1/2 Bridge, ac/dc Full Bridge, dc/dc Dual Full Bridge, the control and protection circuits are different for the three units. The purpose of this program was to produce a control and protection architecture and functional circuits that would work with all three power stage topologies. The requirements for the three existing power stages were determined. The three existing control and protection circuits were analyzed. An IC technology study was performed to determine the optimum technology and fabrication method for SRI control and protection circuits. A control and protection architecture utilizing common functional circuits that would work with the three existing topologies was developed and block diagrams drawn. The functional tasks were portitioned into five custom parts. The requirements for the custom parts were described. A study was performed to assess the potential present and future functions for a microprocessor in a series resonant inverter. Packaging and thermal study was performed to investigate the problems associated with space deployment of a 200-kW series resonant inverter. Recommendations for control and protection architecture, functional circuits, parts selection, and fabrication as hybrid circuits are made.

Moser, R. L.

1984-07-01

296

A novel digital modulation scheme for multilevel cascaded H-bridge inverters  

Microsoft Academic Search

The multilevel cascaded H-bridge (CHB) inverters are widely used in megawatt variable speed drives, where the voltage level normally varies from seven to thirteen and the number of active switching devices used in the inverter is in the range of 36 to 72. The design of a simple modulation scheme for such inverters with superior harmonic performance is a challenging

Mouzhi Dong; Bin Wu; Navid Zargari; Jose Rodriguez

2008-01-01

297

Multilevel Optimal Modulation and Dynamic Control Strategies for STATCOMs Using Cascaded Multilevel Inverters  

Microsoft Academic Search

A multilevel optimal modulation strategy was developed for static synchronous compensators (STATCOMs) using cascaded multilevel inverters. In this strategy, besides the minimized harmonic distortion level, the inverter units' fundamental output voltages are also equalized. Therefore, all the inverter units in each phase leg can equally share the exchanged active and reactive power with the utility grid. This greatly helps the

Qiang Song; Wenhua Liu; Zhichang Yuan

2007-01-01

298

Nonlinear Controller for Cascade H-Bridge Inverter-Based STATCOM  

Microsoft Academic Search

Cascade H-bridge multilevel inverter technique brings a lot of advantages to static synchronous compensator over conventional multi-pulse STATCOM. Based on the theory of the exact linearization via feedback, a MIMO nonlinear controller is proposed. The averaged model of STATCOM based on cascade multilevel inverter is established and the nonlinear control law is analyzed. Simulation results show, under this controller, STATCOM

Zhichang Yuan; Qiang Song; Wenhua Liu; Qingguang Yu

2005-01-01

299

In Good Company? A Multi-Study, Multi-Level Investigation of the Effects of Coworker Relationships on Employee Well-Being  

ERIC Educational Resources Information Center

|Two multi-level studies were conducted to examine the effects of attitudes towards coworkers on daily well-being. Study 1 linked daily levels of coworker satisfaction to job satisfaction and life satisfaction and examined the extent to which job satisfaction mediated the relationship between coworker satisfaction and life satisfaction among 33…

Simon, Lauren S.; Judge, Timothy A.; Halvorsen-Ganepola, Marie D. K.

2010-01-01

300

Grid connected DG systems based on Z-source NPC inverters  

Microsoft Academic Search

Z-source neutral-point-clamped (NPC) inverters have been recently presented as a buck-boost three-level inverter. In this paper five new grid-connected distributed generation (DG) systems are proposed using z-source NPC inverters. With the proposed systems, output power of two separate DG systems such as photovoltaic (PV) arrays and fuel cell (FC) stacks are extracted and delivered to the grid. Since NPC inverter

S. M. Dehghan; E. Seifi; M. Mohamadian; R Gharehkhani

2011-01-01

301

Pulsewidth-Modulated Z-Source Neutral-Point-Clamped Inverter  

Microsoft Academic Search

This paper presents the careful integration of a newly proposed Z-source topological concept to the basic neutral-point-clamped (NPC) inverter topology for designing a three-level inverter with both voltage-buck and voltage-boost capabilities. The designed Z-source NPC inverter uses two unique X-shaped inductance-capacitance (LC) impedance networks that are connected between two isolated dc input power sources and its inverter circuitry for boosting

Poh Chiang Loh; Feng Gao; Frede Blaabjerg; Shi Yun Charmaine Feng; Kong Ngai Jamies Soon

2007-01-01

302

Dynamic performance and control of a static VAr generator using cascade multilevel inverters  

Microsoft Academic Search

A cascade multilevel inverter is proposed for static VAr compensation\\/generation applications. The new cascade M-level inverter consists of (M-1)\\/2 single-phase full bridges in which each bridge has its own separate DC source. This inverter can generate almost sinusoidal waveform voltage with only one time switching per cycle. It can eliminate the need for transformers in multipulse inverters. A prototype static

Fang Zheng Peng; Jih-Sheng Lai

1997-01-01

303

Space vector modulation for voltage-source inverters: a unified approach  

Microsoft Academic Search

This paper presents a unified approach of the space vector modulation for voltage-source inverters. To demonstrate the proposed unified approach, five fundamental inverters topologies are analyzed: single-phase full-bridge, three-phase three-wire, three-phase four-wire, three-phase four-leg and three-phase three-level inverters. Switching vectors, separation and boundary planes in the inverter output space as well as decomposition matrices and possible switching sequences are derived

H. Pinheiro; F. Botteron; C. Rech; L. Schuch; R. F. Camargo; H. L. Hey; H. A. Griindling; J. R. Pinheiro

2002-01-01

304

Design and characterization of water level detector using MW22B Multi-Turn potentiometer  

NASA Astrophysics Data System (ADS)

It has been designed and characterized the water level detector using MW22B Multi-Turn Potentiometer. The electrical angle of potentiometer used has been characterized, that is 3600°+/-7° and its linearity independent is +/-0.25%. The realized system consists of three parts; mechanical system of sensor, signal conditioning circuit and output system. The mechanical system of sensor is destined to convert linearly the value of potentiometer resistance to the water level variation. The signal conditioning consists of analog and digital system especially microcontroller circuit. The value of water level measured is shown on the 2×16 characters LCD. The range of measured water level is 0 - 2.7 m that correspond to the potentiometer resistance range of 100? - 100 k?. The obtained vertical resolution of instrument is about 0.03 m and the error of system is ~1.11%.

Warsito; Pauzi, Gurum A.; Suciyati, Sri W.; Turyani

2012-06-01

305

Inverter Modeling For Accurate Energy Predictions Of Tracking HCPV Installations  

NASA Astrophysics Data System (ADS)

High efficiency high concentration photovoltaic (HCPV) solar plants of megawatt scale are now operational, and opportunities for expanded adoption are plentiful. However, effective bidding for sites requires reliable prediction of energy production. HCPV module nameplate power is rated for specific test conditions; however, instantaneous HCPV power varies due to site specific irradiance and operating temperature, and is degraded by soiling, protective stowing, shading, and electrical connectivity. These factors interact with the selection of equipment typically supplied by third parties, e.g., wire gauge and inverters. We describe a time sequence model accurately accounting for these effects that predicts annual energy production, with specific reference to the impact of the inverter on energy output and interactions between system-level design decisions and the inverter. We will also show two examples, based on an actual field design, of inverter efficiency calculations and the interaction between string arrangements and inverter selection.

Bowman, J.; Jensen, S.; McDonald, Mark

2010-10-01

306

Inverted Metamorphic Cell Development: Cooperative Research and Development Final Report, CRADA Number CRD-05-156  

SciTech Connect

This CRADA targeted technology transfer of the inverted metamorphic multi-junction (IMM) solar cell innovation from NREL to Emcore Photovoltaics. The technology transfer was successfully completed. Additionally, NREL provided materials characterization of solar cell structures produced at Emcore.

Wanlass, M.

2012-05-01

307

Measurement of Low Level Explosives Reaction in Gauged Multi-Dimensional Steven Impact Tests  

NASA Astrophysics Data System (ADS)

The Steven Test was developed to determine relative impact sensitivity of metal encased solid high explosives and be amenable to two-dimensional modeling. Low level reaction thresholds occur at impact velocities below those required for shock initiation. To assist in understanding this test, multi-dimensional gauge techniques utilizing carbon foil and carbon resistor gauges were used to measure pressure and event times. Carbon resistor gauges indicated late time low level reactions 350 ms after projectile impact, creating 0.5-0.6 kb peak shocks centered in PBX 9501 explosives discs. Steven Test calculations based on ignition and growth criteria predict low level reactions occurring at 335 ms which agrees well with experimental data. Additional gauged experiments simulating the Steven Test have been performed and will be discussed. * This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National laboratory under contract No. W-7405-Eng-48.

Niles, A. M.; Forbes, J. W.; Tarver, C. M.; Chidester, S. K.; Garcia, F.; Greenwood, D. W.; Garza, R. G.

2001-06-01

308

A multi-level code for metallurgical effects in metal-forming processes  

SciTech Connect

The authors present the final report on a Laboratory-Directed Research and Development (LDRD) project, A Multi-level Code for Metallurgical Effects in metal-Forming Processes, performed during the fiscal years 1995 and 1996. The project focused on the development of new modeling capabilities for simulating forging and extrusion processes that typically display phenomenology occurring on two different length scales. In support of model fitting and code validation, ring compression and extrusion experiments were performed on 304L stainless steel, a material of interest in DOE nuclear weapons applications.

Taylor, P.A.; Silling, S.A. [Sandia National Labs., Albuquerque, NM (United States). Computational Physics and Mechanics Dept.; Hughes, D.A.; Bammann, D.J.; Chiesa, M.L. [Sandia National Labs., Livermore, CA (United States)

1997-08-01

309

Multi-level basis selection of wavelet packet decomposition tree for heart sound classification.  

PubMed

Wavelet packet transform decomposes a signal into a set of orthonormal bases (nodes) and provides opportunities to select an appropriate set of these bases for feature extraction. In this paper, multi-level basis selection (MLBS) is proposed to preserve the most informative bases of a wavelet packet decomposition tree through removing less informative bases by applying three exclusion criteria: frequency range, noise frequency, and energy threshold. MLBS achieved an accuracy of 97.56% for classifying normal heart sound, aortic stenosis, mitral regurgitation, and aortic regurgitation. MLBS is a promising basis selection to be suggested for signals with a small range of frequencies. PMID:24034732

Safara, Fatemeh; Doraisamy, Shyamala; Azman, Azreen; Jantan, Azrul; Abdullah Ramaiah, Asri Ranga

2013-07-06

310

Multi-level surface enhanced Raman scattering using AgOx thin film.  

PubMed

Ag nanostructures with surface-enhanced Raman scattering (SERS) activities have been fabricated by applying laser-direct writing (LDW) technique on silver oxide (AgOx) thin films. By controlling the laser powers, multi-level Raman imaging of organic molecules adsorbed on the nanostructures has been observed. This phenomenon is further investigated by atomic-force microscopy and electromagnetic calculation. The SERS-active nanostructure is also fabricated on transparent and flexible substrate to demonstrate our promising strategy for the development of novel and low-cost sensing chip. PMID:24150290

Tseng, Ming Lun; Chang, Chia Min; Cheng, Bo Han; Wu, Pin Chieh; Chung, Kuang Sheng; Hsiao, Min-Kai; Huang, Hsin Wei; Huang, Ding-Wei; Chiang, Hai-Pang; Leung, Pui Tak; Tsai, Din Ping

2013-10-21

311

Image segmentation of biofilm structures using optimal multi-level thresholding.  

PubMed

The appreciation of biofilm structures in digital images can be subjective to the observer, and hence it is necessary to analyse the underlying images in useful parameters by means of quantification that is, ideally, free of errors. This paper proposes a combination of techniques for segmentation of biofilm images through an optimal multi-level thresholding algorithm and a set of clustering validity indices, including the determination of the best number of thresholds. The results, which are validated through Rand Index and a quantification process performed in a laboratory, are similar to the quantification and segmentation done by an expert. PMID:21805823

Rojas, Darío; Rueda, Luis; Ngom, Alioune; Hurrutia, Homero; Cárcamo, Gerardo

2011-01-01

312

Improved inverted decoupling control using dead-time compensator for MIMO processes  

Microsoft Academic Search

This paper presents an improved inverted decoupling control strategy using dead-time compensator (DTC) for multi-input multi-output (MIMO) processes when a first order plus dead-time (FOPDT) model of the process is considered. By implementing analytic operation and a definite search algorithm, an effective DTC matrix can be attained. Then the conventional inverted decoupling can be applied to the compensated processes, and

Luo Yunhui; Liu Hongbo; Jia Lei

2010-01-01

313

Illustration of the SFG-Tracing MultiLevel Behavioral Verification Methodology, by the Correctness Proof of a High to Low Level Synthesis Application in CATHEDRAL-II  

Microsoft Academic Search

The SFG-tracing methodology addresses the automatic verification of digital synchronous circuit implementations as specified at the algorithmic level as signal- (SFG) or data flow graphs. The SFG-tracing methodology is a multi-level design verification paradigm that aims at bridging the gap between higher level specifications down to lower level implementations up to the transistor switch level. The concepts of the SFG-tracing

Mark Genoe; Luc J. M. Claesen; Eric Verlind; Frank Proesmans; Hugo De Mani

1991-01-01

314

A multi-level assessment of a program to teach medical students to teach.  

PubMed

Few longitudinal programs exist to teach senior students (MS4s) to be teachers, nor have there been any reports of comprehensive program evaluation in this area. The primary objectives of this study were to describe our ongoing faculty development effort and to develop a multi-level program evaluation, using Dixon's model. The TALKS (Teaching and Learning Communication Skills) program is a senior elective and open to all MS4s. We evaluated our program through assessment of its participants at three levels: level 1, opinion; level 2, competence; and level 3, performance; but not level 4, patient outcomes. The authors used a retrospective, pre-post questionnaire to assess MS4 attitudes about their educational experiences, a traditional instrument to assess their teaching, an interaction analysis technique using Bloom's taxonomy to assess MS4s' feedback skills, and a SP exam to assess MS4 communication skills. The authors hypothesized that MS4s participating in TALKS would view medical education more positively and informatively, would demonstrate important principles in giving feedback, would be assessed as excellent teachers, and would perform better than controls in an SP exam emphasizing communication skills. Results revealed that MS4s' ratings as teachers were very good to excellent, with the highest scores on the items "knowledgeable, supportive of me, and answering questions clearly." (Level 1, Opinion) MS4s' perceptions of their knowledge, attitudes and skills increased significantly from the pre to the post-questionnaire. (Level 2, Competence) MS4 feedback skills to MS2s revealed they did more talking than ideal, often at the lowest levels of Bloom's taxonomy. (Level 3, Performance) MS4s demonstrated better communication skills than controls on an evaluation by professional SPs. (Level 3, Performance). PMID:17041788

Blatt, Benjamin; Greenberg, Larrie

2006-10-14

315

Microseismic mapping of hydraulic fractures using multi-level wireline receivers  

SciTech Connect

Hydraulic fracture diagnostic experiments are being conducted at the GRI/DOE Multi-Site (M-Site) located in the Piceance basin of Colorado. Tests described in this paper use a multi-level advanced-receiver system to build on previous work that showed the advantages of using a single advanced receiver to monitor microseisms. The current test has a four-level receiver system monitoring four separate fracture experiments conducted over a one week period, and includes a velocity tomographic survey and detailed orientation survey. Hydraulic fractures were monitored from an offset well 210 ft away from the treatment well. The results of these monitoring tests show a fracture developing asymmetrically with time, yielding a fracture-wing asymmetry of 2:1. The fracture initially grows within the pay zone to essentially its total length, and then begins to grow upward, and later in time grow downward. Comparison with fracture models gives only a partial agreement in the final size.

Warpinski, N.R.; Engler, B.P.; Young, C.J. [Sandia National Labs., Albuquerque, NM (United States); Peterson, R.; Branagan, P.T.; Fix, J.E.

1995-07-01

316

Fabricating a multi-level barrier-integrated microfluidic device using grey-scale photolithography  

NASA Astrophysics Data System (ADS)

Most polymer-replica-based microfluidic devices are mainly fabricated by using standard soft-lithography technology so that multi-level masters (MLMs) require multiple spin-coatings, mask alignments, exposures, developments, and bakings. In this paper, we describe a simple method for fabricating MLMs for planar microfluidic channels with multi-level barriers (MLBs). A single photomask is necessary for standard photolithography technology to create a polydimethylsiloxane grey-scale photomask (PGSP), which adjusts the total amount of UV absorption in a negative-tone photoresist via a wide range of dye concentrations. Since the PGSP in turn adjusts the degree of cross-linking of the photoresist, this method enables the fabrication of MLMs for an MLB-integrated microfluidic device. Since the PGSP-based soft-lithography technology provides a simple but powerful fabrication method for MLBs in a microfluidic device, we believe that the fabrication method can be widely used for micro total analysis systems that benefit from MLBs. We demonstrate an MLB-integrated microfluidic device that can separate microparticles.

Nam, Yoonkwang; Kim, Minseok; Kim, Taesung

2013-10-01

317

Multi-level interconnects for heterojunction bipolar transistor integrated circuit technologies  

SciTech Connect

Heterojunction bipolar transistors (HBTs) are mesa structures which present difficult planarization problems in integrated circuit fabrication. The authors report a multilevel metal interconnect technology using Benzocyclobutene (BCB) to implement high-speed, low-power photoreceivers based on InGaAs/InP HBTs. Processes for patterning and dry etching BCB to achieve smooth via holes with sloped sidewalls are presented. Excellent planarization of 1.9 {micro}m mesa topographies on InGaAs/InP device structures is demonstrated using scanning electron microscopy (SEM). Additionally, SEM cross sections of both the multi-level metal interconnect via holes and the base emitter via holes required in the HBT IC process are presented. All via holes exhibit sloped sidewalls with slopes of 0.4 {micro}m/{micro}m to 2 {micro}m/{micro}m which are needed to realize a robust interconnect process. Specific contact resistances of the interconnects are found to be less than 6 {times} 10{sup {minus}8} {Omega}cm{sup 2}. Integrated circuits utilizing InGaAs/InP HBTs are fabricated to demonstrate the applicability and compatibility of the multi-level interconnect technology with integrated circuit processing.

Patrizi, G.A.; Lovejoy, M.L.; Schneider, R.P. Jr.; Hou, H.Q. [Sandia National Labs., Albuquerque, NM (United States); Enquist, P.M. [Research Triangle Inst., Research Triangle Park, NC (United States)

1995-12-31

318

The Polarization-Free Approximation Applied to Multi-Level Non-LTE Radiative Transfer  

NASA Astrophysics Data System (ADS)

The polarization-free (POF) approximation (Trujillo Bueno and Landi Degl'Innocenti, 1996) is capable of accounting for the approximate influence of the magnetic field on the statistical equilibrium, without actually solving the full Stokes vector radiative transfer equation. The method introduces the Zeeman splitting or broadening of the line absorption profile ?I in the scalar radiative transfer equation, but the coupling between Stokes I and the other Stokes parameters is neglected. The expected influence of the magnetic field is largest for strongly-split strong lines and the effect is greatly enhanced by gradients in the magnetic field strength. Formally the interaction with the other Stokes parameters may not be neglected for strongly-split strong lines, but it turns out that the error in Stokes I obtained through the POF approximation to a large extent cancels the neglect of interaction with the other Stokes parameters, so that the resulting line source functions and line opacities are more accurate than those obtained with the field-free approach. Although its merits have so far only been tested for a two-level atom, we apply the POF approximation to multi-level non-LTE radiative transfer problems on the premise that there is no essential difference between these two cases. Final verification of its validity in multi-level cases still awaits the completion of a non-LTE Stokes vector transfer code. For two realistic multi-level cases (CaII and MgI in the solar atmosphere) it is demonstrated that the POF method leads to small changes, with respect to the field-free method, in the line source functions and emergent Stokes vector profiles (much smaller than for a two-level atom). Real atoms are dominated by strong ultraviolet lines (only weakly split) and continua, and most lines with large magnetic splitting (in the red and the infrared) are at higher excitation energies, i.e. they are relatively weak and unable to produce significant changes in the statistical equilibrium. We find that it is generally unpredictable by how much the POF results will differ from the field-free results, so that it is nearly always necessary to confirm predictions by actual computations. The POF approximation provides more reliable results than the field-free approximation without significantly complicating the radiative transfer problem, i.e. without solving any extra equations and without excessive computational resource requirements, so that it is to be preferred over the field-free approximation.

Bruls, J. H. M. J.; Trujillo Bueno, J.

1996-03-01

319

Multi-Grained Level of Detail for Rendering Complex Meshes Using a Hierarchical Seamless Texture Atlas  

SciTech Connect

Previous algorithms for view-dependent level of detail provide local mesh refinements either at the finest granularity or at a fixed, coarse granularity. The former provides triangle-level adaptation, often at the expense of heavy CPU usage and low triangle rendering throughput; the latter improves CPU usage and rendering throughput by operating on groups of triangles. We present a new multiresolution hierarchy and associated algorithms that provide adaptive granularity. This multi-grained hierarchy allows independent control of the number of hierarchy nodes processed on the CPU and the number of triangles to be rendered on the GPU. We employ a seamless texture atlas style of geometry image as a GPU-friendly data organization, enabling efficient rendering and GPU-based stitching of patch borders. We demonstrate our approach on both large triangle meshes and terrains with up to billions of vertices.

Niski, K; Purnomo, B; Cohen, J

2006-11-06

320

Measurement of Low Level Explosives Reaction in Gauged Multi-dimensional Steven Impact Tests  

NASA Astrophysics Data System (ADS)

The Steven Test was developed to determine relative impact sensitivity of metal encased solid high explosives and also be amenable to two-dimensional modeling. Low level reaction thresholds occur at impact velocities below those required for shock initiation. To assist in understanding this test, multi-dimensional gauge techniques utilizing carbon foil and carbon resistor gauges were used to measure pressure and event times. Carbon resistor gauges indicated late time low level reactions 200-540 mus after projectile impact, creating 0.39-2.00 kb peak shocks centered in PBX 9501 explosives discs and a 0.60 kb peak shock in a LX-04 disk. Steven Test modeling results, based on ignition and growth criteria, are presented for two PBX 9501 scenarios: one with projectile impact velocity just under threshold (51 m/s) and one with projectile impact velocity just over threshold (55 m/s). Modeling results are presented and compared to experimental data.

Niles, A. M.; Garcia, F.; Greenwood, D. W.; Forbes, J. W.; Tarver, C. M.; Chidester, S. K.; Garza, R. G.; Swizter, L. L.

2002-07-01

321

“Voltage sag and unbalance mitigation in distribution systems using multi-level UPQC”  

Microsoft Academic Search

Unified Power Quality Conditioner (UPQC) is a series-parallel element in the Flexible AC Transmission System (FACTS) family. In this paper, a UPQC with cascaded multilevel inverter is proposed. Voltage sag, unbalance and load power factor in distribution system is mitigated using proposed multilevel UPQC. There is no need of using transformer and filter when multilevel UPQC is applied and it

Naeem Farokhnia; Seyyed Hamid Fathi; Hamidreza Toodeji

2010-01-01

322

Voltage sag and unbalance mitigation in distribution systems using multi-level UPQC  

Microsoft Academic Search

Unified Power Quality Conditioner (UPQC) is a series-parallel element in the Flexible AC Transmission System (FACTS) family. In this paper, a UPQC with cascaded multilevel inverter is proposed. Voltage sag, unbalance and load power factor in distribution system is mitigated using proposed multilevel UPQC. There is no need of using transformer and filter when multilevel UPQC is applied and it

N. Farokhnia; S. H. Fathi; H. R. Toodeji

2010-01-01

323

Optimization of inverted vector searches  

Microsoft Academic Search

A simple algorithm is presented for increasing the efficiency of information retrieval searches which are implemented using inverted files. This optimization algorithm employs knowledge about the methods used for weighting document and query terms in order to examine as few inverted lists as possible. An extension to the basic algorithm allows greatly increased performance optimization at a modest cost in

Chris Buckley; Alan F. Lewit

1985-01-01

324

Inverter, Power, Static PP-6348 ()/U.  

National Technical Information Service (NTIS)

The report covers the performance and general design of the PP-6348 ()/U Static Power Inverter. Numerical data and accompanying photographs delineate the terminal characteristics of the inverter. The design of the inverter is considered at both system and...

T. A. Froeschle H. W. Hill

1971-01-01

325

A study on the impact of high penetration distributed generation inverters on grid operation and stability  

NASA Astrophysics Data System (ADS)

Recent advances in inverter technology have enabled ancillary services such as volt/VAR regulation, SCADA communications, and active power filtering. Smart inverters can not only provide real power, but can be controlled to use excess capacity to provide reactive power compensation, power flow control, and active power filtering without supplementary inverter hardware. A transient level inverter model based on the Solectria 7700 inverter is developed and used to assess these control strategies using field data from an existing branch circuit containing two Amonix 68kW CPV-7700 systems installed at the University of California, Irvine.

Gu, Fei; Brouwer, Jack; Samuelsen, Scott

2013-09-01

326

Role of energy-level mismatches in a multi-pathway complex of photosynthesis  

NASA Astrophysics Data System (ADS)

Considering a multi-pathway structure in a light-harvesting complex of photosynthesis, we investigated the role of energy-level mismatches between antenna molecules in transferring the absorbed energy to a reaction center (RC). We found a condition in which the antenna molecules faithfully play their roles: when their effective absorption ratios are larger than those of the receiver molecule directly coupled to the RC. In the absence of energy-level mismatches and dephasing noise, there arises quantum destructive interference between multiple paths that restricts the energy transfer. On the other hand, the destructive interference diminishes as asymmetrically biasing the energy-level mismatches and/or introducing quantum noise of dephasing for the antenna molecules, so that the transfer efficiency is greatly enhanced to nearly unity. Remarkably, the near-unity efficiency can be achieved at a wide range of asymmetric energy-level mismatches. Temporal characteristics are also optimized at the energy-level mismatches where the transfer efficiency is nearly unity. We discuss these effects, in particular, for the Fenna-Matthews-Olson complex.

Lim, James; Ryu, Junghee; Lee, Changhyoup; Yoo, Seokwon; Jeong, Hyunseok; Lee, Jinhyoung

2011-10-01

327

Gender Differences in Public and Private Drinking Contexts: A Multi-Level GENACIS Analysis  

PubMed Central

This multi-national study hypothesized that higher levels of country-level gender equality would predict smaller differences in the frequency of women’s compared to men’s drinking in public (like bars and restaurants) settings and possibly private (home or party) settings. GENACIS project survey data with drinking contexts included 22 countries in Europe (8); the Americas (7); Asia (3); Australasia (2), and Africa (2), analyzed using hierarchical linear models (individuals nested within country). Age, gender and marital status were individual predictors; country-level gender equality as well as equality in economic participation, education, and political participation, and reproductive autonomy and context of violence against women measures were country-level variables. In separate models, more reproductive autonomy, economic participation, and educational attainment and less violence against women predicted smaller differences in drinking in public settings. Once controlling for country-level economic status, only equality in economic participation predicted the size of the gender difference. Most country-level variables did not explain the gender difference in frequency of drinking in private settings. Where gender equality predicted this difference, the direction of the findings was opposite from the direction in public settings, with more equality predicting a larger gender difference, although this relationship was no longer significant after controlling for country-level economic status. Findings suggest that country-level gender equality may influence gender differences in drinking. However, the effects of gender equality on drinking may depend on the specific alcohol measure, in this case drinking context, as well as on the aspect of gender equality considered. Similar studies that use only global measures of gender equality may miss key relationships. We consider potential implications for alcohol related consequences, policy and public health.

Bond, Jason C.; Roberts, Sarah C.M.; Greenfield, Thomas K.; Korcha, Rachael; Ye, Yu; Nayak, Madhabika B.

2010-01-01

328

Improved estimates of upper-ocean warming and multi-decadal sea-level rise.  

PubMed

Changes in the climate system's energy budget are predominantly revealed in ocean temperatures and the associated thermal expansion contribution to sea-level rise. Climate models, however, do not reproduce the large decadal variability in globally averaged ocean heat content inferred from the sparse observational database, even when volcanic and other variable climate forcings are included. The sum of the observed contributions has also not adequately explained the overall multi-decadal rise. Here we report improved estimates of near-global ocean heat content and thermal expansion for the upper 300 m and 700 m of the ocean for 1950-2003, using statistical techniques that allow for sparse data coverage and applying recent corrections to reduce systematic biases in the most common ocean temperature observations. Our ocean warming and thermal expansion trends for 1961-2003 are about 50 per cent larger than earlier estimates but about 40 per cent smaller for 1993-2003, which is consistent with the recognition that previously estimated rates for the 1990s had a positive bias as a result of instrumental errors. On average, the decadal variability of the climate models with volcanic forcing now agrees approximately with the observations, but the modelled multi-decadal trends are smaller than observed. We add our observational estimate of upper-ocean thermal expansion to other contributions to sea-level rise and find that the sum of contributions from 1961 to 2003 is about 1.5 +/- 0.4 mm yr(-1), in good agreement with our updated estimate of near-global mean sea-level rise (using techniques established in earlier studies) of 1.6 +/- 0.2 mm yr(-1). PMID:18563162

Domingues, Catia M; Church, John A; White, Neil J; Gleckler, Peter J; Wijffels, Susan E; Barker, Paul M; Dunn, Jeff R

2008-06-19

329

Extraction and measurement of multi-level parallelism in production systems. Master's thesis  

SciTech Connect

Production systems provide a flexible and powerful means for expressing and solving problems using high-level reasoning approaches. Unfortunately applications based on the production system paradigm are very compute intensive and therefore execute very slowly on conventional computer architectures. Lack of execution speed therefore limits the use of production systems in many time sensitive and complex tasks. Researchers have demonstrated that increasing the execution speed of production systems through the use of small scale parallel computer architecture is possible, however demonstrated execution speed is still several orders of magnitude below the desired level of performance. Past research indicates that there exists an irrevocable tie between the specific production system application and the level of parallelism inherent in that application. To date, this parallelism has been quantified only in very loose terms based on specific problem decomposition and implementation on a specific parallel architecture. This thesis examines many of the possible approaches to extracting parallelism from production systems and quantifying the level of parallelism in specific applications. This research also investigates previously unexplored aspects of several important decomposition approaches. The software products developed to support this research are Software Tool for Evaluating Parallelism in Production Systems (STEPPS) and a modified version of the C-Language Integrated Production System (CLIPS) called Multi-CLIPS.

Sawyer, G.A.

1990-12-14

330

Multi-level behaviours in agent-based simulation: colonic crypt cell populations  

NASA Astrophysics Data System (ADS)

Agent-based modelling and simulation is now beginning to establish itself as a suitable technique for studying biological systems. However, a major issue in using agent-based simulations to study complex systems such as those in Systems Biology is the fact that simulations are `opaque'. While we have knowledge of individuals' behaviour through agent rules and have techniques for evaluating global behaviour by aggregating the states of individuals, methods for identifying the interactive mechanisms giving rise to this global behaviour are lacking. Formulating precise hypotheses about these multi-level behaviours is also difficult without an established formalism for describing them. The complex event formalism allows relationships between agent-rule-generated events to be defined so that behaviours at different levels of abstraction to be described. Complex event types define categories of these behaviours, which can then be detected in simulation, giving us computational method for distinguishing between alternative interactive mechanisms underlying a higher level behaviour. We apply the complex event formalism to an agent-based model of cell populations in the colonic crypt and demonstrate how competition and selection events can be identified in simulation at both the individual and clonal level, allowing us to computationally test hypotheses about the interactive mechanisms underlying a clone's success.

Chen, Chih-Chun; Nagl, Sylvia B.; Clack, Christopher D.

331

Segmentation of hand radiographs by using multi-level connected active appearance models  

NASA Astrophysics Data System (ADS)

Robust and accurate segmentation methods are important for the computerized evaluation of medical images. For treatment of rheumatoid arthritis, joint damage assessment in radiographs of hands is frequently used for monitoring disease progression. Current clinical scoring methods are based on visual measurements that are time-consuming and subject to intra and inter-reader variance. A solution may be found in the development of partially automated assessment procedures. This requires reliable segmentation algorithms. Our work demonstrates a segmentation method based on multiple connected active appearance models (AAM) with multiple search steps using different quality levels. The quality level can be regulated by setting the image resolution and the number of landmarks in the AAMs. We performed experiments using two models of different quality levels for shape and texture information. Both models included AAMs for the carpal region, the metacarpals, and all phalanges. By starting an iterative search with the faster, low-quality model, we were able to determine the initial parameters of the second, high-quality model. After the second search, the results showed successful segmentation for 22 of 30 test images. For these images, 70% of the landmarks were found within 1.3 mm difference from manual placement by an expert. The multi-level search approach resulted in a reduction of 50% in calculation time compared to a search using a single model. Results are expected to improve when the model is refined by increasing the number of training examples and the resolution of the models.

Kauffman, Joost A.; Slump, Cornelis H.; Bernelot Moens, Hein J.

2005-04-01

332

xQTL workbench: a scalable web environment for multi-level QTL analysis  

PubMed Central

Summary: xQTL workbench is a scalable web platform for the mapping of quantitative trait loci (QTLs) at multiple levels: for example gene expression (eQTL), protein abundance (pQTL), metabolite abundance (mQTL) and phenotype (phQTL) data. Popular QTL mapping methods for model organism and human populations are accessible via the web user interface. Large calculations scale easily on to multi-core computers, clusters and Cloud. All data involved can be uploaded and queried online: markers, genotypes, microarrays, NGS, LC-MS, GC-MS, NMR, etc. When new data types come available, xQTL workbench is quickly customized using the Molgenis software generator. Availability: xQTL workbench runs on all common platforms, including Linux, Mac OS X and Windows. An online demo system, installation guide, tutorials, software and source code are available under the LGPL3 license from http://www.xqtl.org. Contact: m.a.swertz@rug.nl

Arends, Danny; van der Velde, K. Joeri; Prins, Pjotr; Broman, Karl W.; Moller, Steffen; Jansen, Ritsert C.; Swertz, Morris A.

2012-01-01

333

High-Level Waste Tanks Multi-Dimensional Contaminant Transport Model Development  

SciTech Connect

A suite of multi-dimensional computer models was developed to analyze the transport of residual contamination from high-level waste tanks through the subsurface to seeplines. Cases analyzed ranged from all the tanks in the F- and H-tank farms for an overall look; to the Tank 17-20 4-pack to study plume interaction; to individual tanks, such as Tank 17 and 20 for comparison with one-dimensional and modeling. The main purpose of this work was to develop and test the models, so only two relatively conservative contaminants were examined, Tc-99 and I-129. More complex analyses, such as solubility-limited species and radionuclides that head a decay chain were not addressed in this study.

Collard, L.B.

1999-11-15

334

Multi-Level Phase Change Memory Cells with SiN or Ta2O5 Barrier Layers  

NASA Astrophysics Data System (ADS)

This work compares the effects of SiN and Ta2O5 barrier layers in a multi-level phase change random access memory (PCRAM) cell. The PCRAM cell comprises a phase change material stack between a top and a bottom electrode. The phase change material stack comprises a nitrogen-doped Ge2Sb2Te5 (NGST) layer on top of a thin barrier layer on an undoped GST layer. The thermal conductivity and electrical resistivity of the barrier layer affect multi-level switching performance in terms of endurance as well as power consumption. Extensive electrical characterization was performed on these PCRAM multi-level devices. Thermal analysis was also performed to investigate the thermal efficiency of each barrier layer. It was observed that for a constant barrier layer thickness of 1.5 nm, the endurance of the multi-level device with the SiN barrier layer was better than that with the Ta2O5 barrier layer; however, the multi-level device with the Ta2O5 barrier layer had a lower power consumption than that with the SiN barrier layer.

Gyanathan, Ashvini; Yeo, Yee-Chia

2012-02-01

335

Multilevel inverter modulation schemes to eliminate common-mode voltages  

Microsoft Academic Search

It is well known that conventional two-level pulsewidth modulated (PWM) inverters generate high-frequency common-mode voltages with high dv\\/dt. Similarly, commonly used multilevel inverter modulation schemes generate common-mode voltages. Common-mode voltages may cause motor shaft voltages and bearing currents and conducted electromagnetic interference (EMI). Premature motor bearing failures and electronic equipment malfunctions have been reported to be directly related to bearing

Haoran Zhang; Annette von Jouanne; Shaoan Dai; Alan K. Wallace; Fei Wang

2000-01-01

336

The bidirectional Z-source inverter for energy storage application  

Microsoft Academic Search

Paper describes development of a three-phase bidirectional Z-source inverter (ZSI) interfacing an energy storage and supply network. Idea of bidirectional operation of ZSI is presented and simply solution of the capacitor voltage over boost problem is proposed. Issue of correct selection of voltage levels and minimum storage voltage for grid-connected inverter is discussed. Selection of the suitable PWM method and

Jacek Rabkowski

2007-01-01

337

Multilevel conversion: high voltage choppers and voltage-source inverters  

Microsoft Academic Search

The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters

T. A. Meynard; H. Foch

1992-01-01

338

Novel space vector based current controllers for PWM-inverters  

Microsoft Academic Search

Two novel, simple control strategies for current-controlled pulse-width modulated (PWM) transistor inverters are presented. Both methods are based on the three-level hysteresis comparators which select appropriate inverter output voltage vectors via a switching electrically programmable read-only memory (EPROM) table. The first controller works with current components represented in a stationary coordinate system (AC components) and the second with components represented

M. P. Kazmierkowski; M. A. Dzieniakowski; W. Sulkowski

1991-01-01

339

Dual inverter configuration for grid-connected photovoltaic generation systems  

Microsoft Academic Search

The design and control issues associated with the development of a novel three-phase grid-connected photovoltaic generation system are discussed in this paper. The scheme is based on two insulated strings of panels, each one feeding a standard two-level three-phase voltage source inverter (VSI). Inverters are connected to grid by a three-phase transformer with the open winding configuration on primary side.

Gabriele Grandi; Darko Ostojic; Claudio Rossi

2007-01-01

340

Fine Structure of Optical Energy Levels Scheme for Ni{sup 2+} Doped in Inverted Perovskite BaLiF{sub 3}  

SciTech Connect

The aim of this paper is to calculate the fine structure of the optical energy levels scheme of BaLiF{sub 3}:Ni{sup 2+} taken into account besides the spin-orbit interaction, also the spin-spin, orbit-orbit and spin-other-orbit interactions. The numerical theoretical crystal field parameters were computed using the model exchange charge calculations of crystal field, taking into account the effects of the covalent bond formation between the Ni{sup 2+} and F{sup -} ions. The Hamiltonian of the BaLiF{sub 3}:Ni{sup 2+} system has been diagonalized in a complete basis set spanned by all wave functions of the 3d{sup 8} electron configuration. The comparison of the calculated energy levels with experimental data gives a satisfactory agreement, which confirms the model and used method.

Andreici, Emiliana-Laura [Department of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223, Timisoara (Romania); Avram, N. M. [Department of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223, Timisoara (Romania); Academy of Romanian Scientists, Independentei 54, 050094-Bucharest (Romania)

2011-10-03

341

Modeling and design of a neutral-point voltage regulator for a three-level diode-clamped inverter using multiple-carrier modulation  

Microsoft Academic Search

The three-level diode-clamped multilevel converter commonly called the neutral-point-clamped converter has become established to be a preferred topology for high-power motor drive applications operating at several kilovolts. Although solutions to the problem of maintaining a stable neutral-point voltage in the converter continue to be the topic of research, a simple solution based on a design-oriented dynamic model of the system

Ashish Bendre; Giri Venkataramanan; Don Rosene; Vijay Srinivasan

2006-01-01

342

A multi-level data-flow architecture for signal and data processing applications. Final report  

SciTech Connect

A grant was awarded to us by the Department of Energy, Office of Energy Research, in May 1987 to support the design and performance analysis of a large grain data-driven multiprocessor system for numerical applications. The basic idea of the work is to apply the data-driven principles of execution at a more appropriate level than conventional ``atomic`` instructions. For this purpose, a level such as that of vector operations was under study. This document represents the final report concerning the results of the research supported by this grant. The goals of the project entailed an analysis of Partial Differential Equation solvers on data-driven environments, a preliminary design of our multi-level architecture, an in-depth study of some of the mechanisms of execution, and a design of the software environment. As enumerated in the original proposal, our work has yielded results in three different domain: Specifications of the application programs; design of the general concepts of the architecture and simulation; implementation of a translating environment; and we discuss each of the above items and examine specific research results.

Gaudiot, J.L.

1993-09-02

343

System-level modeling of segmented deformable micromirror using multi-port-element network method  

NASA Astrophysics Data System (ADS)

This paper presents the development of system-level modeling and simulation of segmented deformable micromirror. We represent a system-level modeling methodology called Multi-Port-Element Network (MuPEN) method for micromirror design which is different from conventional finite-element analysis(FEA) and boundary-element analysis(BEA) method in the paper. Based on this method, the segmented deformable micromirror is decomposed into functional components such as rigid plate-mass, spring beam and electrostatic gap. MuPEN models of functional components have been generated and are coded in MAST language. Then a system-level model of segmented deformable micromirror is established using MuPEN models and both static and dynamic simulation is implemented in SABER. The resonance frequency, the pull-in voltage and the response time of the micromirror are ascertained through different simulations and the simulation results show that the micromirror we designed can satisfy the adaptive optical system requirements. Besides, the frequency analysis results are verified by comparison with ANSYS simulations, and the results prove that MuPEN method has near FEM accuracy. In addition, transient analysis results indicate that the computation cost is low enough and the simulation of complicated electro-mechanical coupled system which is hardly completed by FEM software can be accomplished quickly in this way.

He, Yang; Jiang, Chengyu; Yuan, Weizheng; Huo, Pengfei; Ma, Binghe

2006-01-01

344

Multirate Deadbeat Control for 100kHz Single Phase Utility Interactive Inverter with FPGA Based Hardware Controller  

NASA Astrophysics Data System (ADS)

A current control method for the utility interactive inverter based on multi-rate deadbeat control method with FPGA based hardware controller is verified for 100kHz carrier PWM inverter. As the distributed power systems spread, the requirement of the control accuracy for the utility interactive inverter becomes more precise. Deadbeat control is one method to ensure the output voltage or current matches to the references at the sampling instant, so adopting this control law to the utility interactive inverter, the response of the system is much improved with small LC filter component compared with the conventional PI control. A current control method for the utility interactive inverter based on multi-rate deadbeat control, single-rate deadbeat control and PI control were compared. Multi-rate deadbeat control improves the tracking accuracy to the reference compared with the conventional single-rate deadbeat control and PI control. The advantages and disadvantages are discussed through simulations and experiments.

Yokoyama, Tomoki; Saigusa, Takahiro

345

Structured Multi-level Data Fusion and Modelling of Heterogeneous Environmental Data for Future Internet Applications  

NASA Astrophysics Data System (ADS)

The rapid increase in environmental observations which are conducted by Small to Medium Enterprise communities and volunteers using affordable in situ sensors at various scales, in addition to the more established observatories set up by environmental and space agencies using airborne and space-borne sensing technologies is generating serious amounts of BIG data at ever increasing speeds. Furthermore, the emergence of Future Internet technologies and the urgent requirements for the deployment of specific enablers for the delivery of processed environmental knowledge in real-time with advanced situation awareness to citizens has reached paramount importance. Specifically, it has become highly critical now to build and provide services which automate the aggregation of data from various sources, while surmounting the semantic gaps, conflicts and heterogeneity in data sources. The early stage aggregation of data will enable the pre-processing of data from multiple sources while reconciling the temporal gaps in measurement time series, and aligning their respective a-synchronicities. This low level type of data fusion process needs to be automated and chained to more advanced level of data fusion services specialising in observation forecasts at spaces where sensing is not deployed; or at time slices where sensing has not taken place yet. As a result, multi-level fusion services are required among the families of specific enablers for monitoring environments and spaces in the Future Internet. These have been intially deployed and piloted in the ongoing ENVIROFI project of the FI-PPP programme [1]. Automated fusion and modelling of in situ and remote sensing data has been set up and the experimentation successfully conducted using RBF networks for the spatial fusion of water quality parameters measurements from satellite and stationary buoys in the Irish Sea. The RBF networks method scales for the spatial data fusion of multiple types of observation sources. This important approach provides a strong basis for the delivery of environmental observations at desired spatial and temporal scales to multiple users with various needs of spatial and temporal resolutions. It has also led to building robust future internet specific enablers on data fusion, which can indeed be used for multiple usage areas above and beyond the environmental domains of the Future Internet. In this paper, data and processing workflow scenarios shall be described. The fucntionalities of the multi-level fusion services shall be demonstrated and made accessible to the wider communities of the Fututre Internet. [1] The Environmental Observation Web and its Service Applications within the Future Internet. ENVIROFI IP. FP7-2011-ICT-IF Pr.No: 284898 http://www.envirofi.eu/

Sabeur, Zoheir; Chakravarthy, Ajay; Bashevoy, Maxim; Modafferi, Stefano

2013-04-01

346

Carrier Density and Compensation in Semiconductors with Multi Dopants and Multi Transition Energy Levels: The Case of Cu Impurity in CdTe  

SciTech Connect

Doping is one of the most important issues in semiconductor physics. The charge carrier generated by doping can profoundly change the properties of semiconductors and their performance in optoelectronic device applications, such as solar cells. Using detailed balance theory and first-principles calculated defect formation energies and transition energy levels, we derive general formulae to calculate carrier density for semiconductors with multi dopants and multi transition energy levels. As an example, we studied CdTe doped with Cu, in which V{sub Cd}, Cu{sub Cd}, and Cu{sub i} are the dominant defects/impurities. We show that in this system, when Cu concentration increases, the doping properties of the system can change from a poor p-type, to a poorer p-type, to a better p-type, and then to a poor p-type again, in good agreement with experimental observation of CdTe-based solar cells.

Wei, S. H.; Ma, J.; Gessert, T. A.; Chin, K. K.

2011-01-01

347

Carrier Density and Compensation in Semiconductors with Multi Dopants and Multi Transition Energy Levels: The Case of Cu Impurity in CdTe: Preprint  

SciTech Connect

Doping is one of the most important issues in semiconductor physics. The charge carrier generated by doping can profoundly change the properties of semiconductors and their performance in optoelectronic device applications, such as solar cells. Using detailed balance theory and first-principles calculated defect formation energies and transition energy levels, we derive general formulae to calculate carrier density for semiconductors with multi dopants and multi transition energy levels. As an example, we studied CdTe doped with Cu, in which VCd, CuCd, and Cui are the dominant defects/impurities. We show that in this system, when Cu concentration increases, the doping properties of the system can change from a poor p-type, to a poorer p-type, to a better p-type, and then to a poor p-type again, in good agreement with experimental observation of CdTe-based solar cells.

Wei, S. H.; Ma, J.; Gessert, T. A.; Chin, K. K.

2011-07-01

348

Multi?level Land Cover Mapping of the Twin Cities (Minnesota) Metropolitan Area with Multi?seasonal Landsat TM\\/ETM+ Data  

Microsoft Academic Search

Land cover maps, especially vegetation maps, are of increasing interest and use to resource agencies. This paper describes a three?stage hybrid classification method for regional?scale multi?level land cover mapping. The first stage involves an unsupervised classification and stratification. The second stage includes supervised classification of forest types, rule?based clustering of non?forested vegetation, and estimation of percent impervious area with a

Fei Yuan; Marvin E. Bauer; Nathan J. Heinert; Geoffrey R. Holden

2005-01-01

349

Inverted book stand  

US Patent & Trademark Office Database

An inverted book stand having a book support platform comprised of two pivotally connected, transparent panels. The panels can be moved from a first, stowed position, where the panels are folded together and in close proximity to each other, to a second, in use position, where the panels are folded open to an angle of less than 180.degree. to form the support platform. The panels are formed with an integral, angle limiting feature at the pivotal connection to maintain the angle between panels when they are in the open position. Support members are pivotally connected to the outer edge of each panel, opposite to edge of the panel from where the panels are connected to each other. The support members can be moved from a first, stowed position, wherein each support member is in a closed position parallel and adjacent to its respective panel, and a second, in use position, where the support member is pivoted to an angle of more than 90.degree. from the panel surface. An integral limiting feature is provided at the pivotal connection between the support members and the panels to limit the angle formed between them when the support members are opened. The book stand can be folded to a substantially flat configuration for transport.

Luccia; Paul (Huntingdon Valley, PA)

1996-01-23

350

Invertible cellular automata: A review  

NASA Astrophysics Data System (ADS)

In the light of recent developments in the theory of invertible cellular automata, we attempt to give a unified presentation of the subject and discuss its relevance to computer science and mathematical physics.

Toffoli, Tommaso; Margolus, Norman H.

1990-09-01

351

General Analysis of Three-Phase Inverters  

Microsoft Academic Search

A method of analysis for three-phase inverters is described. The method is based on Park vectors [1], [2] and predicts the waveforms of inverter quantities under various load conditions. The procedure discussed can be used to determine the commutation sequence of a pulsewidth modulated inverter. The current distribution of the inverter can be obtained from the current vector. The vectors

Kalman R. Jardan; S. B. Dewan; Gordon R. Slemon

1969-01-01

352

Discontinuous energy pump source inverters  

Microsoft Academic Search

This paper introduces a family of step-up DC\\/AC converters based on discontinuous-output pump circuits. The impedance-source inverter (ZSI) is a step-up DC\\/AC converter that is composed of a conventional inverter and an impedance network. This impedance network is actually a pump circuit with discontinuous output voltage. Considering concept of ZSI, other discontinuous output pump circuits can be used as front-end

S. M. Dehghan; M. Mohamadian; E. Siefi

2011-01-01

353

A novel digital modulation scheme for multilevel cascaded H-bridge inverters in high power AC drives  

Microsoft Academic Search

The multilevel cascaded H-bridge (CHB) inverters are widely used in megawatt variable speed drives, where the voltage level normally varies from seven to thirteen and the number of active switching devices used in the inverter is in the range of 36 to 72. The design of a simple modulation scheme for such inverters with superior harmonic performance is a challenging

Mouzhi Dong

2007-01-01

354

Time-dependent radiative transfer for multi-level atoms using accelerated Lambda iteration  

NASA Astrophysics Data System (ADS)

We present a general formalism for computing self-consistent, numerical solutions to the time-dependent radiative transfer equation in low-velocity, multi-level ions undergoing radiative interactions. Recent studies of time-dependent radiative transfer have focused on radiation hydrodynamic and magnetohydrodynamic effects without lines, or have solved time-independent equations for the radiation field simultaneously with time-dependent equations for the state of the medium. In this paper, we provide a fully time-dependent numerical solution to the radiative transfer and atomic rate equations for a medium irradiated by an external source of photons. We use accelerated Lambda iteration to achieve convergence of the radiation field and atomic states. We perform calculations for a three-level atomic model that illustrates important time-dependent effects. We demonstrate that our method provides an efficient, accurate solution to the time-dependent radiative transfer problem. Finally, we characterize astrophysical scenarios in which we expect our solutions to be important.

van Adelsberg, Matthew; Perna, Rosalba

2013-02-01

355

Desynchronization of Noisy Multi-cellular Clocks Underlies the Population-level Singularity Behavior of Mammalian Circadian Clock  

NASA Astrophysics Data System (ADS)

The singularity behavior of circadian clocks defined as the suppression of circadian oscillation by critical perturbation is one of the intriguing dynamical properties of circadian rhythms. Although the singularity behaviors have been observed in various organisms, its mechanism has not yet been elucidated, because the hierarchical structure of multi-cell-level circadian clocks exists behind the organism-level circadian rhythm. In vitro light-responsible circadian system is indispensable for extracting the underlying mechanism of the singularity behavior behind the hierarchical structure of multi-cell organisms. To obtain such in vitro system, we synthetically constructed light-responsible mammalian clock cells by exogenously introducing a photo-responsible receptor. By using this synthetic system and population-level high-throughput promoter activity assay, we found that a light pulse with critical timing and strength can induce population-level singularity behavior of the light-responsible mammalian clock cells. Subsequent single-cell measurement revealed that desynchronization of multi-cellular clocks underlies the population-level singularity. A mathematical model consistently explains our population-level and single-cell-level experimental data, and also demonstrates that the synchronization and desynchronization of cellular clocks is the underlying mechanism of population-level response of circadian clocks to external perturbation. In addition, our model suggests that fluctuation in single-cell-level behavior of the clock cells is the key determinant of the observable singularity behavior.

Kobayashi, Tetsuya J.; Ukai, Hideki; Ueda, Hiroki R.

2007-07-01

356

Dual-Source Fed Multi-phase Induction Motor Drive for Fuel Cell Vehicles: Topology and Control  

Microsoft Academic Search

The paper introduces a new multi-source fed drive topology based on a multi-phase induction machine. The reference application is the hybrid fuel cell (FC) traction system (fuel cell and battery). The FC power and the battery power are directly added at the machine level, without any additional DC-DC converters. The proposed drive topology uses two three-phase inverters having different DC

R. Bojoi; A. Tenconi; F. Farina; F. Profumo

2005-01-01

357

Multicarrier PWM strategies for multilevel inverters  

Microsoft Academic Search

Analytical solutions of pulsewidth-modulation (PWM) strategies for multilevel inverters are used to identify that alternative phase opposition disposition PWM for diode-clamped inverters produces the same harmonic performance as phase-shifted carrier PWM for cascaded inverters, and hybrid PWM for hybrid inverters, when the carrier frequencies are set to achieve the same number of inverter switch transitions over each fundamental cycle. Using

Brendan Peter McGrath; Donald Grahame Holmes

2002-01-01

358

Image accuracy and representational enhancement through low-level, multi-sensor integration techniques  

SciTech Connect

Multi-Sensor Integration (MSI) is the combining of data and information from more than one source in order to generate a more reliable and consistent representation of the environment. The need for MSI derives largely from basic ambiguities inherent in our current sensor imaging technologies. These ambiguities exist as long as the mapping from reality to image is not 1-to-1. That is, if different 44 realities'' lead to identical images, a single image cannot reveal the particular reality which was the truth. MSI techniques can be divided into three categories based on the relative information content of the original images with that of the desired representation: (1) detail enhancement,'' wherein the relative information content of the original images is less rich than the desired representation; (2) data enhancement,'' wherein the MSI techniques axe concerned with improving the accuracy of the data rather than either increasing or decreasing the level of detail; and (3) conceptual enhancement,'' wherein the image contains more detail than is desired, making it difficult to easily recognize objects of interest. In conceptual enhancement one must group pixels corresponding to the same conceptual object and thereby reduce the level of extraneous detail. This research focuses on data and conceptual enhancement algorithms. To be useful in many real-world applications, e.g., autonomous or teleoperated robotics, real-time feedback is critical. But, many MSI/image processing algorithms require significant processing time. This is especially true of feature extraction, object isolation, and object recognition algorithms due to their typical reliance on global or large neighborhood information. This research attempts to exploit the speed currently available in state-of-the-art digitizers and highly parallel processing systems by developing MSI algorithms based on pixel rather than global-level features.

Baker, J.E.

1993-05-01

359

Image accuracy and representational enhancement through low-level, multi-sensor integration techniques  

SciTech Connect

Multi-Sensor Integration (MSI) is the combining of data and information from more than one source in order to generate a more reliable and consistent representation of the environment. The need for MSI derives largely from basic ambiguities inherent in our current sensor imaging technologies. These ambiguities exist as long as the mapping from reality to image is not 1-to-1. That is, if different 44 realities`` lead to identical images, a single image cannot reveal the particular reality which was the truth. MSI techniques can be divided into three categories based on the relative information content of the original images with that of the desired representation: (1) ``detail enhancement,`` wherein the relative information content of the original images is less rich than the desired representation; (2) ``data enhancement,`` wherein the MSI techniques axe concerned with improving the accuracy of the data rather than either increasing or decreasing the level of detail; and (3) ``conceptual enhancement,`` wherein the image contains more detail than is desired, making it difficult to easily recognize objects of interest. In conceptual enhancement one must group pixels corresponding to the same conceptual object and thereby reduce the level of extraneous detail. This research focuses on data and conceptual enhancement algorithms. To be useful in many real-world applications, e.g., autonomous or teleoperated robotics, real-time feedback is critical. But, many MSI/image processing algorithms require significant processing time. This is especially true of feature extraction, object isolation, and object recognition algorithms due to their typical reliance on global or large neighborhood information. This research attempts to exploit the speed currently available in state-of-the-art digitizers and highly parallel processing systems by developing MSI algorithms based on pixel rather than global-level features.

Baker, J.E.

1993-05-01

360

Voltage Control of Three-Stage Hybrid Multilevel Inverter Using Vector Transformation  

Microsoft Academic Search

This paper presents a three-stage 18-level inverter design with a novel control method. The inverter consists of a series-connected main high-voltage, medium-voltage, and low-voltage stages. The high-voltage stage is made of a three-phase, six-switch conventional inverter. The medium- and low-voltage stages are made of three-level inverters constructed by H-bridge units. The proposed control strategy assumes a reference-input voltage vector and

Saad Mekhilef; Mohamad N. Abdul Kadir

2010-01-01

361

Local charge neutrality condition, Fermi level and majority carrier density of a semiconductor with multiple localized multi-level intrinsic/impurity defects  

NASA Astrophysics Data System (ADS)

For semiconductors with localized intrinsic/impurity defects, intentionally doped or unintentionally incorporated, that have multiple transition energy levels among charge states, the general formulation of the local charge neutrality condition is given for the determination of the Fermi level and the majority carrier density. A graphical method is used to illustrate the solution of the problem. Relations among the transition energy levels of the multi-level defect are derived using the graphical method. Numerical examples are given for p-doping of the CdTe thin film used in solar panels and semi-insulating Si to illustrate the relevance and importance of the issues discussed in this work.

Chin, Ken K.

2011-11-01

362

Multi-Objective Programming Approach to Double-Level Supply Chain  

Microsoft Academic Search

Under the pressure of global financial crisis, enterprises tend to enhance ability of Supply Chain Management (SCM) and their own advantages can be developed in the competition. A decision making model of multi-product multi-stage supply chain consisted of single manufacturer and single supplier is proposed in this article. The model is proved to be superior and efficient through application example.

Ren Zezhu; Zhang Yu

2010-01-01

363

Multi-objective programming approach to double-level supply chain  

Microsoft Academic Search

Under the pressure of global financial crisis, enterprises tend to enhance ability of Supply Chain Management (SCM) and their own advantages can be developed in the competition. A decision making model of multi-product multi-stage supply chain consisted of single manufacturer and single supplier is proposed in this article. The model is proved to be superior and efficient through application example.

Wang Qiang; Sun Liang

2010-01-01

364

Putting Poverty in Political Context: A Multi-Level Analysis of Adult Poverty across 18 Affluent Democracies  

ERIC Educational Resources Information Center

Our study analyzes how political context, embodied by the welfare state and Leftist political actors, shapes individual poverty. Using the Luxembourg Income Study, we conduct a multi-level analysis of working-aged adult poverty across 18 affluent Western democracies. Our index of welfare generosity has a negative effect on poverty net of…

Brady, David; Fullerton, Andrew S.; Cross, Jennifer Moren

2009-01-01

365

The Development of a Multi-Level Model for Crisis Preparedness and Intervention in the Greek Educational System  

ERIC Educational Resources Information Center

|This article proposes a multi-level model for crisis preparedness and intervention in the Greek educational system. It presents: a) a brief overview of leading models of school crisis preparedness and intervention as well as cultural considerations for contextually relevant crisis response; b) a description of existing crisis intervention…

Hatzichristiou, Chryse; Issari, Philia; Lykitsakou, Konstantina; Lampropoulou, Aikaterini; Dimitropoulou, Panayiota

2011-01-01

366

Short temporal coherence digital holography with a femtosecond frequency comb laser for multi-level optical sectioning.  

PubMed

In this paper, we demonstrate how short temporal coherence digital holography with a femtosecond frequency comb laser source may be used for multi-level optical sectioning. The object shape is obtained by digitally reconstructing and processing a sequence of holograms recorded during stepwise shifting of a mirror in the reference arm. Experimental results are presented. PMID:22453405

Körner, Klaus; Pedrini, Giancarlo; Alexeenko, Igor; Steinmetz, Tilo; Holzwarth, R; Osten, W

2012-03-26

367

Work in progress — Medical imaging education by a multi-level module-based online teaching and assessment system  

Microsoft Academic Search

Medical imaging education is a key training component in BME programs. Medical imaging curriculum involves physics principles, mathematical derivations, engineering implementations for teaching image generation, reconstruction and application. We developed an Internet accessible, multi-level module-based interactive system for teaching five commonly used medical imaging modalities. Each imaging modality is delivered by five to six teaching modules (topics). Teaching or learning

Xiping Li; F. Manns; Weizhao Zhao

2010-01-01

368

Modeling flow through the sand pack: implications for groundwater sampling from multi- level monitoring wells in fractured bedrock aquifers  

Microsoft Academic Search

Multi-level piezometers are often used in groundwater studies to monitor multiple zones within a single borehole. In the fractured rock setting the monitoring intervals are typically designed to isolate discrete fracture features (single fractures or fracture zones). This can be very useful for determining vertical connectivity and the distribution of a contaminant within a fractured rock aquifer. A simple and

J. Kozuskanich; K. Novakowski; B. Anderson

2009-01-01

369

Digital Approaches to ISI-Mitigation in High-Resolution Oversampled MultiLevel D\\/A Converters  

Microsoft Academic Search

A new digital signal processing approach to shaping intersymbol interference (ISI) and static mismatch errors simul- taneously in oversampled multi-level digital to analog converters (DAC) has recently been proposed. In this paper, a mathematical framework is established for analyzing ISI errors as well as comparing the ISI sensitivities of different mismatch shaping algorithms. The framework is used to analyze the

Lars Risbo; Rahmi Hezar; Burak Kelleci; Halil Kiper; Mounir Fares

2011-01-01

370

Minimizing End-to-End Interference in I/O Stacks Spanning Shared Multi-Level Buffer Caches  

ERIC Educational Resources Information Center

|This thesis presents an end-to-end interference minimizing uniquely designed high performance I/O stack that spans multi-level shared buffer cache hierarchies accessing shared I/O servers to deliver a seamless high performance I/O stack. In this thesis, I show that I can build a superior I/O stack which minimizes the inter-application…

Patrick, Christina M.

2011-01-01

371

Understanding the effect of ethnic density on mental health: multi-level investigation of survey data from England  

Microsoft Academic Search

Objectives To determine if living in areas where higher proportions of people of the same ethnicity reside is protective for common mental disorders, and associated with a reduced exposure to discrimination and improved social support. Finally, to determine if any protective ethnic density effects are mediated by reduced exposure to racism and improved social support.Design Multi-level logistic regression analysis of

Jayati Das-Munshi; Laia Becares; Michael E Dewey; Stephen A Stansfeld; Martin J Prince

2010-01-01

372

Computer diagnosis and tuning of microwave filters using model-based parameter estimation and multi-level optimization  

Microsoft Academic Search

This paper describes an approach for the computer diagnosis and tuning of microwave filters relying upon model-based parameter estimation and multi-level optimization. This approach uses the reduced-order system and the effect of measurement noise is also considered. This approach can be applied to many classes of the filters. Examples are presented to demonstrate its feasibility

Masoud Kahrizi; Safieddin Safavi-Naeini; Sujeet K. Chaudhuri

2000-01-01

373

The Multi-level Learning and Classification of Multi-class Parts-Based Representations of U.S. Marine Postures  

NASA Astrophysics Data System (ADS)

This paper primarily investigates the possibility of using multi-level learning of sparse parts-based representations of US Marine postures in an outside and often crowded environment for training exercises. To do so, the paper discusses two approaches to learning parts-based representations for each posture needed. The first approach uses a two-level learning method which consists of simple clustering of interest patches extracted from a set of training images for each posture, in addition to learning the nonparametric spatial frequency distribution of the clusters that represents one posture type. The second approach uses a two-level learning method which involves convolving interest patches with filters and in addition performing joint boosting on the spatial locations of the first level of learned parts in order to create a global set of parts that the various postures share in representation. Experimental results on video from actual US Marine training exercises are included.

Goshorn, Deborah; Wachs, Juan; Kölsch, Mathias

374

Two-dimensional multi-level strain estimation for discontinuous tissue  

NASA Astrophysics Data System (ADS)

A large number of the strain estimation methods presented in the literature are based on the assumption of tissue continuity that establishes a continuous displacement field. However, in certain locations in the body such as the arteries in vivo scanning may produce displacement fields that are discontinuous between the two walls of the artery. Many of the displacement or strain estimators fail when the displacement fields are discontinuous. In this paper, we present a new 2D multi-level motion or displacement tracking method for accurate estimation of the strain in these situations. The final high-resolution displacement estimate is obtained using two processing steps. The first step involves an estimation of a coarse displacement estimate utilizing B-mode or envelope signals. To reduce computational time, the coarse displacement estimates are obtained starting from down-sampled B-mode pre- and post-compression image pairs using a pyramidal processing approach. The coarse displacement estimate obtained from the B-mode data is used to guide the final 2D cross-correlation computations on radio-frequency (RF) data. Results from finite element simulations and in vivo experimental data demonstrate the feasibility of this approach for imaging tissue with discontinuous displacement fields.

Shi, Hairong; Varghese, Tomy

2007-01-01

375

Hierarchical multi-level image mosaicing for autonomous navigation of UAV  

NASA Astrophysics Data System (ADS)

A novel algorithm for hierarchical multi-level image mosaicing for autonomous navigation of UAV is proposed. The main contribution of the proposed system is the blocking of the error accumulation propagated along the frames, by incrementally building a long-duration mosaic on the fly which is hierarchically composed of short-duration mosaics. The proposed algorithm fulfills the real-time processing requirements in autonomous navigation as follows. 1) Causality: the current output of the mosaicing system depends only on the current and/or previous input frames, contrary to existing offline mosaic algorithms that depend on future input frames as well. 2) Learnability: the algorithm autonomously analyzes/learns the scene characteristics. 3) Adaptability: the system automatically adapts itself to the scene change and chooses the proper methods for feature selection (i.e., the fast but unreliable LKT vs. the slow but robust SIFT). The evaluation of our algorithm with the extensive field test data involving several thousand airborne images shows the significant improvement in processing time, robustness and accuracy of the proposed algorithm.

Park, Sangho; Ghosh, Debabrata; Kaabouch, Naima; Fevig, Ronald A.; Semke, William

2012-01-01

376

Multi-antenna RF Ion Source at a High RF Power Level  

SciTech Connect

A multi-antenna radio-frequency ion source with a Faraday shield is newly tested at a high RF power level in a large area negative ion source of 1/5th scale of the Large Helical Device-NNBI ion source. Inductively coupled dense hydrogen plasmas were generated uniformly over an area of 25x25 cm{sup 2} at an RF input power up to 300 kW for a 10 ms pulse duration. A large negative plasma potential for the non-Faraday shielded antenna was remarkably reduced by introducing a Faraday shield. The positive ion saturation current density measured by Langmuir probe reached 148 mA/cm{sup 2} at 174 kW around the center of the plasma. The optimal hydrogen filling pressure ranged around 0.13 Pa- 0.4 Pa for the positive ions. Ion beam extraction with a single hole ({phi} 0.5 cm) extractor has been studied systematically. A maximum H{sup -} ion beam current density of 1.6 mA/cm{sup 2} was obtained preliminarily. It was confirmed that the plasma profile was controllable by both the number and configuration of the antennas.

Oka, Y.; Kaneko, O.; Takeiri, Y.; Tsumori, K.; Osakabe, M.; Ikeda, K.; Nagaoka, K.; Asano, E.; Sato, M.; Kondo, T.; Shibuya, M.; Komada, S. [National Institute for Fusion Science/-NINS-, Oroshi, Toki 509-5292, Gifu (Japan); Shoji, T. [Nagoya university, Chikusa, Nagoya 464-8603 (Japan)

2009-03-12

377

Century to multi-century sea level rise projections from CMIP5 models  

NASA Astrophysics Data System (ADS)

Long-term projections of global-ocean thermal expansion (GTE) and the dynamic sea level (DSL) change are analyzed with 34 new CMIP5 models and under three greenhouse-gas emission scenarios. Multi-model ensemble mean (MEM) and ensemble standard deviation are calculated to identify robust features and quantify uncertainty. While the MEM of GTE shows moderate difference by 2100, with magnitudes of 13, 18 and 28 cm in RCP2.6, RCP4.5 and RCP8.5, respectively, it increases and diverges significantly by 2300, with magnitudes of 21, 52 and 119 cm in the three scenarios. Model-to-model spread seems reduced in CMIP5 compared to CMIP3. The MEM changes of the DSL show similar patterns between different RCPs, but with progressively larger magnitudes in RCP2.6, RCP4.5 and RCP8.5. Notable features identified previously in the CMIP3 projections also occur in CMIP5, indicating their robustness across generations of climate model and emission scenario. The CMIP5 models still show disagreement in projecting the DSL changes, even under the same external forcing.

Yin, Jianjun

2012-09-01

378

Active power filtering by a flying-capacitor multilevel inverter with capacitor voltage balance  

Microsoft Academic Search

A new control strategy is developed for a four-level flying capacitor multilevel inverter to function as an active power filter (APF). This employs space vector modulation (SVM) scheme. However inverter switching vectors and sequences are determined according to the swings of capacitor voltage values at each level. A modified predictive current control law is developed This takes into account the

Junfei Hu; Li Zhang; S. J. Watkins

2008-01-01

379

Modeling and simulation of three phase multilevel inverter for grid connected photovoltaic systems  

Microsoft Academic Search

This paper presents a control for a three phase five-level neutral clamped inverter (NPC) for grid connected PV system. The maximum power point tracking (MPPT) is capable of extracting maximum power from the PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller. The fuzzy MPPT is integrated with the inverter so

A. Ravi; P. S. Manoharan; J. Vijay Anand

2011-01-01

380

A novel hysteresis current controller for multilevel single phase voltage source inverters  

Microsoft Academic Search

The application and benefits of hysteresis current control for two level voltage source inverters are well understood, but the extension of the strategy to multilevel inverters is much less established. Previous approaches have used either multiple hysteresis bands or a time based lockout strategy to decide when to switch to successive voltage levels, but these approaches are either complex, and\\/or

G. H. Bode; D. N. Zmood; P. C. Loh; D. G. Holmes

2001-01-01

381

The tandem inverter: combining the advantages of voltage-source and current-source inverters  

Microsoft Academic Search

A combination of a current-source primary inverter and a voltage-source secondary inverter is proposed as the so-called tandem inverter. The primary inverter operates in the square-wave mode, handling most of the converted power, while its output harmonic currents are compensated by the much smaller secondary inverter. As a result, the tandem inverter, to be used for AC motor control, combines

A. M. Trznadlowski; F. Blaabjerg; J. K. Pedersen; N. Patriciu

1998-01-01

382

Imaging the multi-level magma reservoir at Mt. Etna volcano (Italy)  

NASA Astrophysics Data System (ADS)

The continuous GPS network operating on Mt. Etna with its 36 stations is currently one of the largest worldwide. The aim of this network is the evaluation of volcanic hazard and the modelling of the active sources. In this paper, we propose an in-depth analysis and modelling of continuous GPS data collected at Mt. Etna from May 2008 to December 2010. The analyzed period has been divided into four different coherent phases: 1) 14 May 2008-02 August 2008 (deflation of the entire GPS network); 2) 02 August 2008-14 June 2009 (deflation of the summit area and inflation at lower heights); 3) 14 June 2009-21 May 2010 (inflation of the entire GPS network); 4) 21 May 2010-31 December 2010 (inflation at medium and low heights and end of the inflation in the summit area). Analytical models indicate a non-uniform deformation style revealing spaced sources acting at different time on different segments of a multi-level magma reservoir. The Etnean plumbing system imaged here is depicted as an elongated magma reservoir that extends from the volcano body downwards to about 6.5 km below sea level (b.s.l.), sloping slightly towards the North-West, with storage volumes located at about 6.5, 2.0 and 0.0 km (b.s.l.). The changes in position of the modelled pressure sources during the analyzed time intervals indicate that, throughout the 2008 eruptive period, the deformation field was mostly driven by the upward migration of magma. On the other hand, the pattern of deformation recorded after the end of the eruption strongly suggests a significant contribution of the magma overpressure generated by the gas boiling, thus outlining the importance of volatiles content in magma.

Aloisi, Marco; Mattia, Mario; Ferlito, Carmelo; Palano, Mimmo; Bruno, Valentina; Cannavò, Flavio

2011-08-01

383

String and module integrated inverters for single-phase grid connected photovoltaic systems - a review  

Microsoft Academic Search

This work presents an overview on recent developments and a summary of the state-of-the-art in inverter technology for single-phase grid connected photovoltaic (PV) systems. The information provided includes details on commercially available European string and module integrated PV inverters, their efficiency, price trends and market share. This review is given for inverters for a power level up to 6 kW.

J. M. A. Myrzik; M. Calais

2003-01-01

384

Control of cascaded H-bridge inverters using an FPGA-based platform  

Microsoft Academic Search

Cascaded H-bridge multilevel inverters are highly modular converters particularly suitable for generating high output voltages and connecting independent dc sources like solar arrays or fuel cells. Three-phase multilevel inverters based on cascaded H-bridge inverters require a large number of control signals, particularly if the number of levels is high. In this case, Field-Programmable Gate Array appears as the right solution

Emanuel C. Meireles; Antonio P. Martins

2011-01-01

385

A LOW-SIZE MULTI-POWER-LEVEL SINGLE-TRANSISTOR ELECTRONIC BALLAST FOR FLUORESCENT LAMPS, USING PIEZOELECTRIC TRANSFORMER  

Microsoft Academic Search

A 5 to 18 Watts multi-power level demonstrator with a Transoner-Type Piezoelectric Transformer (PT) has been built in class-E topology to show the functionality of low-size low-cost instant start ballast for fluorescent lamps. Zero-Voltage switching was achieved for different output power levels (different tubes), at nominal input voltage of 230 V AC, including tol- erances, using one and the same

FÁBIO E. BISOGNO; MATTHIAS RADECKER; ALOIS KNOLL; ALFREDO V. CARAZO; ANTON RIEDLHAMMER; GERALD DEBOY; J. MARIO PACAS

386

PWR integrated safety analysis methodology using multi-level coupling algorithm  

NASA Astrophysics Data System (ADS)

Coupled three-dimensional (3D) neutronics/thermal-hydraulic (T-H) system codes give a unique opportunity for a realistic modeling of the plant transients and design basis accidents (DBA) occurring in light water reactors (LWR). Examples of such DBAs are the rod ejection accidents (REA) and the main steam line break (MSLB) that constitute the bounding safety problems for pressurized water reactors (PWR). These accidents involve asymmetric 3D spatial neutronic and T-H effects during the course of the transients. The thermal margins (the peak fuel temperature, and departure from nucleate boiling ratio (DNBR)) are the measures of safety at a particular transient and need to be evaluated as accurate as possible. Modern 3D neutronics/T-H coupled codes estimate the safety margins coarsely on an assembly level, i.e. for an average fuel pin. More accurate prediction of the safety margins requires the evaluation of the transient fuel rod response involving locally coupled neutronics/T-H calculations. The proposed approach is to perform an on-line hot-channel safety analysis not for the whole core but for a selected local region, for example for the highest power loaded fuel assembly. This approach becomes feasible if an on-line algorithm capable to extract the necessary input data for a sub-channel module is available. The necessary input data include the detailed pin-power distributions and the T-H boundary conditions for each sub-channel in the considered problem. Therefore, two potential challenges are faced in the development of refined methodology for evaluation of local safety parameters. One is the development of an efficient transient pin-power reconstruction algorithm with a consistent cross-section modeling. The second is the development of a multi-level coupling algorithm for the T-H boundary and feed-back data exchange between the sub-channel module and the main 3D neutron kinetics/T-H system code, which already uses one level of coupling scheme between 3D neutronics and core thermal-hydraulics models. The major accomplishment of the thesis is the development of an integrated PWR safety analysis methodology with locally refined safety evaluations. This involved introduction of an improved method capable of efficiently restoring the fine pin-power distribution with a high degree of accuracy. In order to apply the methodology to evaluate the safety margins on a pin level, a refined on-line hot channel model was developed accounting for the cross-flow effects. Finally, this methodology was applied to best estimate safety analysis to more accurately calculate the thermal safety margins occurring during a design basis accident in PWR.

Ziabletsev, Dmitri Nickolaevich

387

Sensitivity of Aerosol Multi-Sensor Daily Data Intercomparison to Level 3 Dataday Definition  

NASA Astrophysics Data System (ADS)

One of the main goals of current research on the global distribution and impact of aerosols is the development of a multi-sensor merged or composite dataset of aerosol properties. With more and more aerosol data being available, at various spatial and temporal scales, from various spaceborn sensors, it is difficult to reach consensus derived from these heterogeneous observations. It is important to identify the sources of the differences observed by the various satellite datasets with each other and with model data. One approach has been to compare gridded Level 3 daily data that show differences usually attributed to differences in calibration, retrieval algorithms, cloud filtering, processing details and other issues. In the present paper, we address other aspects of differences between daily Level 3 aerosol data measured by different sensors that significantly contribute to the overall differences in the area around the international dateline, i.e., around the 180 deg longitude. One aspect is the different definition of the data day employed by different science teams; another is related to the fact that, for example, sensors onboard the Terra satellite perform aerosol (daytime) measurements during the descending part of the orbit, while those on Aqua (being part of the A-Train constellation) performs aerosol measurements in the ascending mode. These differences lead to significant time difference between measurements made by sensors on different satellites in some areas, thus (due to spatial and temporal variability of aerosols) lowering correlation between aerosol measurements. We demonstrate that (i) the effect of dataday definition leads to having spatially close measurements coming from orbits separated by about 23 hours (usually, these are the first and last orbits of a day) and (ii) the actual overpass time difference (several hours) is also being modulated by Terra and Aqua daytime measurements being collected during descending and ascending nodes respectively. The so-called spatial dataday definition that preserves the spatial continuity going from one orbit to another has been employed by AIRS, OMI, TOMS, TOVS, AVHRR for atmospheric products and most of the ocean data products. MODIS atmospheric group, on the other hand, has chosen to include Level 2 granules that span a 24-hour (00:00:00 to 23:59:59 UTC) interval, which leads to discontinuities around the dateline. We demonstrate that when the spatial dataday definition is applied to MODIS data, the artifact around the dateline in the correlation map between Terra and Aqua goes away. We conclude that to compare daily Level 3 data in a reasonable way, data from all sensors should be processed consistently using the spatial dataday definition.

Leptoukh, Gregory; Lary, David; Lynnes, Chritopher; Shen, Suhung

2010-05-01

388

Coupling biomechanics to a cellular level model: an approach to patient-specific image driven multi-scale and multi-physics tumor simulation.  

PubMed

Modeling of tumor growth has been performed according to various approaches addressing different biocomplexity levels and spatiotemporal scales. Mathematical treatments range from partial differential equation based diffusion models to rule-based cellular level simulators, aiming at both improving our quantitative understanding of the underlying biological processes and, in the mid- and long term, constructing reliable multi-scale predictive platforms to support patient-individualized treatment planning and optimization. The aim of this paper is to establish a multi-scale and multi-physics approach to tumor modeling taking into account both the cellular and the macroscopic mechanical level. Therefore, an already developed biomodel of clinical tumor growth and response to treatment is self-consistently coupled with a biomechanical model. Results are presented for the free growth case of the imageable component of an initially point-like glioblastoma multiforme tumor. The composite model leads to significant tumor shape corrections that are achieved through the utilization of environmental pressure information and the application of biomechanical principles. Using the ratio of smallest to largest moment of inertia of the tumor material to quantify the effect of our coupled approach, we have found a tumor shape correction of 20% by coupling biomechanics to the cellular simulator as compared to a cellular simulation without preferred growth directions. We conclude that the integration of the two models provides additional morphological insight into realistic tumor growth behavior. Therefore, it might be used for the development of an advanced oncosimulator focusing on tumor types for which morphology plays an important role in surgical and/or radio-therapeutic treatment planning. PMID:21740923

May, Christian P; Kolokotroni, Eleni; Stamatakos, Georgios S; Büchler, Philippe

2011-07-01

389

Heterogeneous Multi-core SoC Implementation with System-Level Design Methodology  

Microsoft Academic Search

The trend towards heterogeneous multi-core integration and higher communication bandwidth drastically increases the complexity of the SoC. Architecture design and system validation become extremely challenging. This paper presents a multi-core computing platform which consists of general-purpose microprocessor and dual programmable digital signal processor (DSP) cores for multimedia applications. To demonstrate its outstanding performance and energy efficiency, we develop multimedia and

Jen-Chieh Yeh; Kung-Ming Ji; Shing-Wu Tung; Shau-Yin Tseng

2011-01-01

390

Optimized space vector switching sequences for multilevel inverters  

Microsoft Academic Search

Previous work has shown that space vector modulation and carrier modulation for two-level inverters achieve the same phase leg switching sequences when appropriate zero sequence offsets are added to the reference waveforms for carrier modulation. This paper presents a similar equivalence between the phase disposition (PD) carrier and space vector modulation strategies applied to diode clamped, cascaded N-level or hybrid

Brendan Peter McGrath; Donald Grahame Holmes; Thomas Lipo

2003-01-01

391

Multi-scale dynamical analysis (MSDA) of sea level records versus PDO, AMO, and NAO indexes  

NASA Astrophysics Data System (ADS)

Herein I propose a multi-scale dynamical analysis to facilitate the physical interpretation of tide gauge records. The technique uses graphical diagrams. It is applied to six secular-long tide gauge records representative of the world oceans: Sydney, Pacific coast of Australia; Fremantle, Indian Ocean coast of Australia; New York City, Atlantic coast of USA; Honolulu, US state of Hawaii; San Diego, US state of California; and Venice, Mediterranean Sea, Italy. For comparison, an equivalent analysis is applied to the Pacific Decadal Oscillation (PDO) index and to the Atlantic Multidecadal Oscillation (AMO) index. Finally, a global reconstruction of sea level (Jevrejeva et al. in Geophys Res Lett 35:L08715, 2008) and a reconstruction of the North Atlantic Oscillation (NAO) index (Luterbacher et al. in Geophys Res Lett 26:2745-2748, 1999) are analyzed and compared: both sequences cover about three centuries from 1700 to 2000. The proposed methodology quickly highlights oscillations and teleconnections among the records at the decadal and multidecadal scales. At the secular time scales tide gauge records present relatively small (positive or negative) accelerations, as found in other studies (Houston and Dean in J Coast Res 27:409-417, 2011). On the contrary, from the decadal to the secular scales (up to 110-year intervals) the tide gauge accelerations oscillate significantly from positive to negative values mostly following the PDO, AMO and NAO oscillations. In particular, the influence of a large quasi 60-70 year natural oscillation is clearly demonstrated in these records. The multiscale dynamical evolutions of the rate and of the amplitude of the annual seasonal cycle of the chosen six tide gauge records are also studied.

Scafetta, N.

2013-04-01

392

49 CFR Figure 2 to Subpart B of... - Example of a Multi-Level Car Complying with Window Location and Staggering Requirements-§§ 238...  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Example of a Multi-Level Car Complying with Window Location and Staggering Requirements-Ã...2 Figure 2 to Subpart B of Part 238âExample of a Multi-Level Car Complying with Window Location and Staggering...

2011-10-01

393

Advanced Modular Inverter Technology Development  

SciTech Connect

Electric and hybrid-electric vehicle systems require an inverter to convert the direct current (DC) output of the energy generation/storage system (engine, fuel cells, or batteries) to the alternating current (AC) that vehicle propulsion motors use. Vehicle support systems, such as lights and air conditioning, also use the inverter AC output. Distributed energy systems require an inverter to provide the high quality AC output that energy system customers demand. Today's inverters are expensive due to the cost of the power electronics components, and system designers must also tailor the inverter for individual applications. Thus, the benefits of mass production are not available, resulting in high initial procurement costs as well as high inverter maintenance and repair costs. Electricore, Inc. (www.electricore.org) a public good 501 (c) (3) not-for-profit advanced technology development consortium assembled a highly qualified team consisting of AeroVironment Inc. (www.aerovironment.com) and Delphi Automotive Systems LLC (Delphi), (www.delphi.com), as equal tiered technical leads, to develop an advanced, modular construction, inverter packaging technology that will offer a 30% cost reduction over conventional designs adding to the development of energy conversion technologies for crosscutting applications in the building, industry, transportation, and utility sectors. The proposed inverter allows for a reduction of weight and size of power electronics in the above-mentioned sectors and is scalable over the range of 15 to 500kW. The main objective of this program was to optimize existing AeroVironment inverter technology to improve power density, reliability and producibility as well as develop new topology to reduce line filter size. The newly developed inverter design will be used in automotive and distribution generation applications. In the first part of this program the high-density power stages were redesigned, optimized and fabricated. One of the main tasks was to design and validate new gate drive circuits to provide the capability of high temp operation. The new power stages and controls were later validated through extensive performance, durability and environmental tests. To further validate the design, two power stages and controls were integrated into a grid-tied load bank test fixture, a real application for field-testing. This fixture was designed to test motor drives with PWM output up to 50kW. In the second part of this program the new control topology based on sub-phases control and interphase transformer technology was successfully developed and validated. The main advantage of this technology is to reduce magnetic mass, loss and current ripple. This report summarizes the results of the advanced modular inverter technology development and details: (1) Power stage development and fabrication (2) Power stage validation testing (3) Grid-tied test fixture fabrication and initial testing (4) Interphase transformer technology development

Adam Szczepanek

2006-02-04

394

RNA-Seq and molecular docking reveal multi-level pesticide resistance in the bed bug  

PubMed Central

Background Bed bugs (Cimex lectularius) are hematophagous nocturnal parasites of humans that have attained high impact status due to their worldwide resurgence. The sudden and rampant resurgence of C. lectularius has been attributed to numerous factors including frequent international travel, narrower pest management practices, and insecticide resistance. Results We performed a next-generation RNA sequencing (RNA-Seq) experiment to find differentially expressed genes between pesticide-resistant (PR) and pesticide-susceptible (PS) strains of C. lectularius. A reference transcriptome database of 51,492 expressed sequence tags (ESTs) was created by combining the databases derived from de novo assembled mRNA-Seq tags (30,404 ESTs) and our previous 454 pyrosequenced database (21,088 ESTs). The two-way GLMseq analysis revealed ~15,000 highly significant differentially expressed ESTs between the PR and PS strains. Among the top 5,000 differentially expressed ESTs, 109 putative defense genes (cuticular proteins, cytochrome P450s, antioxidant genes, ABC transporters, glutathione S-transferases, carboxylesterases and acetyl cholinesterase) involved in penetration resistance and metabolic resistance were identified. Tissue and development-specific expression of P450 CYP3 clan members showed high mRNA levels in the cuticle, Malpighian tubules, and midgut; and in early instar nymphs, respectively. Lastly, molecular modeling and docking of a candidate cytochrome P450 (CYP397A1V2) revealed the flexibility of the deduced protein to metabolize a broad range of insecticide substrates including DDT, deltamethrin, permethrin, and imidacloprid. Conclusions We developed significant molecular resources for C. lectularius putatively involved in metabolic resistance as well as those participating in other modes of insecticide resistance. RNA-Seq profiles of PR strains combined with tissue-specific profiles and molecular docking revealed multi-level insecticide resistance in C. lectularius. Future research that is targeted towards RNA interference (RNAi) on the identified metabolic targets such as cytochrome P450s and cuticular proteins could lay the foundation for a better understanding of the genetic basis of insecticide resistance in C. lectularius.

2012-01-01

395

Tobacco retailer density surrounding schools and youth smoking behaviour: a multi-level analysis  

PubMed Central

Background Youth smoking prevention should be a public health priority. It is not only vital to prevent youth from smoking but also to prevent non-smoking youth from becoming susceptible to smoking. Past research has examined factors associated with youth's susceptibility to become a future smoker, but research has yet to examine tobacco retailer density and susceptibility to smoking among never smokers. The objectives of this study are to examine how tobacco retailer density surrounding schools and social smoking influences are associated with smoking susceptibility among youth of never smokers, and occasional and daily smoking among youth of current smokers. Methods Data were collected in 2005-2006 from grade 9 to 12 students attending 76 secondary schools in Ontario, Canada, as part of the SHAPES-On study. A series of multi-level logistic regression analyses were performed to understand how student- and school-level factors are associated with three smoking behaviour outcomes: smoking susceptibility among never smokers, occasional smoking, and daily smoking. Results The number of tobacco retailers surrounding a school was found to be associated with the likelihood of a never smoker being susceptible to future smoking (OR 1.03, 95CI% 1.01, 1.05). We also identified that being surrounded by smoking social influences, specifically family and close friends, can substantially increase the likelihood that never smokers are at risk for future smoking or that youth are already occasional or daily smokers. Conclusions We identified that the number of tobacco retailers surrounding a school was associated with an increased odds of being susceptible to future smoking among male never smokers. Smoking social models surrounding youth also appears to have an important impact on their smoking behaviour regardless of their smoking status. It is important for youth smoking prevention programs to begin early, interrupt youths' susceptibility to future smoking, and focus on subgroups that are at higher risk of smoking. The government should consider the impact of tobacco retailer density on youth smoking behaviour, and be cautious when granting licenses for establishments to sell tobacco products.

2011-01-01

396

Two-bit multi-level phase change random access memory with a triple phase change material stack structure  

NASA Astrophysics Data System (ADS)

This work demonstrates a novel two-bit multi-level device structure comprising three phase change material (PCM) layers, separated by SiN thermal barrier layers. This triple PCM stack consisted of (from bottom to top), Ge2Sb2Te5 (GST), an ultrathin SiN barrier, nitrogen-doped GST, another ultrathin SiN barrier, and Ag0.5In0.5Sb3Te6. The PCM layers can selectively amorphize to form 4 different resistance levels (``00,'' ``01,'' ``10,'' and ``11'') using respective voltage pulses. Electrical characterization was extensively performed on these devices. Thermal analysis was also done to understand the physics behind the phase changing characteristics of the two-bit memory devices. The melting and crystallization temperatures of the PCMs play important roles in the power consumption of the multi-level devices. The electrical resistivities and thermal conductivities of the PCMs and the SiN thermal barrier are also crucial factors contributing to the phase changing behaviour of the PCMs in the two-bit multi-level PCRAM device.

Gyanathan, Ashvini; Yeo, Yee-Chia

2012-11-01

397

Inverted and multiple nematic emulsions  

Microsoft Academic Search

We investigate experimentally the structures that form when small colloidal particles are suspended in a nematic solvent. These structures are anisotropic, and their formation is driven by interactions arising from the orientational elasticity of the nematic solvent. By using inverted and multiple nematic emulsions composed of water droplets dispersed in a thermotropic liquid crystal, we identify the nature of these

P. Poulin; D. A. Weitz

1998-01-01

398

Detecting Sequence Homology at the Gene Cluster Level with MultiGeneBlast  

PubMed Central

The genes encoding many biomolecular systems and pathways are genomically organized in operons or gene clusters. With MultiGeneBlast, we provide a user-friendly and effective tool to perform homology searches with operons or gene clusters as basic units, instead of single genes. The contextualization offered by MultiGeneBlast allows users to get a better understanding of the function, evolutionary history, and practical applications of such genomic regions. The tool is fully equipped with applications to generate search databases from GenBank or from the user’s own sequence data. Finally, an architecture search mode allows searching for gene clusters with novel configurations, by detecting genomic regions with any user-specified combination of genes. Sources, precompiled binaries, and a graphical tutorial of MultiGeneBlast are freely available from http://multigeneblast.sourceforge.net/.

Medema, Marnix H.; Takano, Eriko; Breitling, Rainer

2013-01-01

399

Novel RZ-CW conversion scheme for ultra multi-level, high-speed coherent OTDM transmission.  

PubMed

A novel coherent multi-level OTDM transmission scheme is presented by using an RZ-CW conversion technique in a coherent receiver, in which the transmitted coherent RZ pulses are OTDM demultiplexed and converted into a CW signals for demodulation with a CW-LO. This scheme enables us to achieve a high SNR demodulation and demultiplexing performance even for ultrahigh-speed OTDM signals with ultra multi-level modulation, which would be difficult to realize with a conventional scheme of simultaneous demodulation and demultiplexing using a pulsed-LO. The advantage of this scheme is successfully demonstrated with 10 Gsymbol/s, 4- and 8-OTDM, 32-RZ/QAM demodulation experiments. PMID:22274073

Nakazawa, Masataka; Kasai, Keisuke; Yoshida, Masato; Hirooka, Toshihiko

2011-12-12

400

Overlaod Protection System for Power Inverter.  

National Technical Information Service (NTIS)

An overload protection system for a power inverter utilizes a first circuit for monitoring current to the load from the power inverter to detect an overload and a control circuit to shut off the power inverter when an overload condition is detected. At th...

S. Nagano

1976-01-01

401

Multilevel Inverters for Electric Vehicle Applications.  

National Technical Information Service (NTIS)

This paper presents multilevel inverters as an application for all-electric vehicle (EV) and hybrid-electric vehicle (HEV) motor drives. Diode-clamped inverters and cascaded H-bridge inverters, (1) can generate near-sinusoidal voltages with only fundament...

T. G. Habetler F. Z. Peng L. M. Tolbert

1998-01-01

402

Parallel operation of voltage source inverters  

Microsoft Academic Search

Parallel operating systems of voltage source inverters with other inverters or with the utility source are sensitive to disturbances from the load or other sources and can easily be damaged by overcurrent. Thus extremely careful attention should be given to the system design of parallel operating inverters. Types of system configuration, control methods, and means of protection against failure are

T. Kawabata; S. Higashino

1988-01-01

403

Genetic adaptive control for an inverted wedge  

Microsoft Academic Search

The inverted wedge is a planar robot with two degrees of freedom and a single control input (i.e., it is “underactuated”). The goal is to develop a digital controller that can balance the wedge in the inverted position by shifting a weight on the top of the wedge. Because it is underactuated and has complicated nonlinear dynamics, the inverted wedge

Mathew L. Moore; John T. Musacchio; Kevin M. Passino

1999-01-01

404

Bioresorbable anterior cervical plate device for multi-level degenerative disc disease: Case report with 8-year follow-up  

Microsoft Academic Search

Anterior cervical decompression and fusion is most successful when bone graft is combined with stabilizing instrumentation. The use of bioresorbable anterior cervical plates has been reported recently instead of the traditional titanium plate. We report a novel application of a bioresorbable plate in the management of a 69-year-old Caucasian female with multi-level, long-standing cervical spondylotic myelopathy. The patient previously had

Robert G. Whitmore; Elana S. Tykocinski; Matthew R. Sanborn; William C. Welch

405

Low Energy Data Management for Different On-Chip Memory Levels in Multi-Context Reconfigurable Architectures  

Microsoft Academic Search

This paper presents a new technique to improve the efficiency of data scheduling for multi-context reconfigurable architectures targeting multimedia and DSP applications. The main goal is to improve application energy consumption. Two levels of on-chip data storage are assumed in the reconfigurable architecture. The Data Scheduler attempts to optimally exploit this storage, by deciding in which on-chip memory the data

Marcos Sanchez-Elez; M. Fernandez; Manuel L. Anido; Haitao Du; Nader Bagherzadeh; Román Hermida

2003-01-01

406

A software radio architecture for the baseband level of the multi-standard user terminal: Design methodology and computational assessment  

Microsoft Academic Search

In this paper we present a design methodology and system prototyping for the baseband level of the Software Defined Radio (SDR)-based portable multi-standard terminal. The SDR-based architecture consists of three main layers denoted as: i) Upper Layer to provide communication with an end user and a network; ii) Middle Layer to establish the required protocol configuration; and iii) Bottom Layer

Olga Zlydareva; Claudio Sacchi

2010-01-01

407

Multi-level micro/nanotexturing by three-dimensionally controlled photofluidization and its use in plasmonic applications.  

PubMed

The Field-Gradient Effect extends the photofluidization of azobenzene materials to 3D, multi-level micro/nanotexturing with a newly conceptualized design strategy based on "field-gradient photofluidization". In particular, we successfully characterized the vertical gradient optical absorption within the azobenzene material and the resulting field-gradient photofluidization both theoretically and experimentally. Furthermore, we could create the heterogeneously integrated micro/nanotextures at any desired surface heights, capability that is potentially beneficial for plasmonic applications. PMID:23857634

Kang, Hong Suk; Lee, Seungwoo; Lee, Sol-Ah; Park, Jung-Ki

2013-07-15

408

Self-Perceived Job Insecurity and Social Context: A MultiLevel Analysis of 17 European Countries  

Microsoft Academic Search

Job insecurity causes far-reaching negative outcomes. The fear of job loss damages the health of employees and reduces the productivity of firms. Thus, job insecurity should result in increasing social costs. Analysing representative data from 17 European countries, this paper investigates self-perceived job insecurity. Our multi-level analysis reveals significant cross-country differences in individuals’ perception of job insecurity. This finding is

Marcel Erlinghagen

2008-01-01

409

High aspect ratio multi-level mold inserts fabricated by mechanical micro machining and deep etch X-ray lithography  

Microsoft Academic Search

Complex microstructures can be fabricated in large quantities by thermoplastic molding processes. The shape of the microstructures\\u000a is determined mainly by the mold insert. Until now, multi-level mold inserts have been fabricated either by deep etch X-ray\\u000a lithography and electroforming, Harmening et al. (1992), or by milling of a brass substrate, Schaller et al. (1995). In both\\u000a cases there are

J. Fahrenberg; Th. Schaller; W. Bacher; A. El-Kholi; W. K. Schomburg

1995-01-01

410

High aspect ratio multi-level mold inserts fabricated by mechanical micro machining and deep etch X-ray lithography  

Microsoft Academic Search

Complex microstructures can be fabricated in large quantities by thermoplastic molding processes. The shape of the microstructures\\u000a is determined mainly by the mold insert. Until now, multi-level mold inserts have been fabricated either by deep etch X-ray\\u000a lithography and electroforming, Harmening et al. (1992), or by milling of a brass substrate, Schaller et al. (1995). In both\\u000a cases there are

J. Fahrenberg; T. Schaller; W. Bacher; A. El-Kholi; W. K. Schomburg

1996-01-01

411

Teleportation of Three-Level Multi-partite Entangled State by a Partial Three-Level Bipartite Entangled State  

NASA Astrophysics Data System (ADS)

We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel. This scheme can be directly generalized to probabilistically teleport an unknown three-level k-particle entangled state by a partial three-level bipartite entangled state. All kinds of unitary transformations are given in detail. We calculate the successful total probability and the total classical communication cost required for this scheme.

Dai, Hong-Yi; Zhang, Ming; Li, Cheng-Zu

2008-04-01

412

Investigation into Harmonic Losses in a PWM Multilevel cascaded H-Bridge Inverter Fed Induction Motor  

Microsoft Academic Search

This paper presents harmonic loss considerations in a PWM multilevel cascaded H-bridge inverter fed induction motor. A non-sinusoidal waveform or voltage harmonic has influence on efficiency and performance of a drive system. Harmonic voltages depend upon PWM parameters such as modulation index, switching frequency, PWM schemes, and dc voltage levels etc. The comparison of additional losses between a conventional inverter

Prasopchok Hothongkham; Vijit Kinnares

2007-01-01

413

Comparative Evaluation of Pulsewidth Modulation Strategies for Z-Source Neutral-Point-Clamped Inverter  

Microsoft Academic Search

Z-source neutral-point-clamped (NPC) inverter has recently been proposed as an alternative three-level buck-boost power conversion solution with an improved output waveform quality. In principle, the designed Z-source inverter functions by selectively \\

Poh Chiang Loh; Frede Blaabjerg; Chow Pang Wong

2007-01-01

414

Reconfiguration of carrier-based modulation strategy for fault tolerant multilevel inverters  

Microsoft Academic Search

This paper focuses on the fault-tolerance of the multilevel inverters with the redundant switching states. The failure situations of the multilevel inverters are classified into two kinds of them according to relationship between the output voltage level and the switching states. When some of the power devices fail, the gate signals are reconfigured according to the failure types. The method

Lei Hu; Mingyao Ma; Alian Chen; Xiangning He; Hao Ma

2005-01-01

415

A novel single Z-source based multilevel inverter for renewable source  

Microsoft Academic Search

This paper presents a novel single Z-source based seven level multilevel inverter. In this topology single Z-source impedance network is used to boost up the output voltage using shoot through state control. A new PWM technique is implemented by using three reference signals and a triangular carrier signal which are used to generate the PWM signals for inverter switches, and

R. Thanasekaran; K. Senrayan; T. Anand Kumar; P. Ponmanikandan

2012-01-01

416

Comparison of high power IGBTs and hard driven GTOs for high power inverters  

Microsoft Academic Search

The paper compares hard driven GTOs (IGCTs) and high power IGBT modules in a two level PWM inverter. The structure, fundamental operation, and specific characteristics of the considered devices are shown. Simulations enable a loss comparison of IGCTs and IGBTs in a 1.14 MVA inverter at switching frequencies of fs=250 Hz\\/500 Hz. The evaluation of device characteristics is the basis

S. Bernet; R. Teichmann; A. Zuckerberger; P. Steimer

1998-01-01

417

New voltage regulation techniques for low voltage radial feed PWM inverter based distributed networks  

Microsoft Academic Search

Grid voltage rise problems occur, especially at light loads, due to the proliferation of distributed generation. Two techniques are proposed for regulating the voltage in low voltage radial networks when inverter based distributed generation is employed. The first technique, voltage regulated power control regulates the voltage by controlling the active power level delivered by the inverter to be low at

K. H. Ahmed; A. M. Massoud; S. J. Finney; B. W. Williams

2010-01-01

418

High Resolution Multi-Level Monitoring and Characterization of NA Processes  

NASA Astrophysics Data System (ADS)

Monitored natural attenuation is a potentially valuable risk-based remediation strategy for contaminated groundwater. The most important mass-removal process for natural attenuation is biodegradation. Certain zones or fringes of a contaminant plume offer enhanced conditions for biodegradation: microbes, nutrients, contaminants and electron donors / acceptors are not only found together but also in the required reaction ratios. Due to this fact these areas show a relative rapid degradation and provide a significant contribution to the overall reduction of mass within the plume. As can be shown by high resolution numerical simulations of reactive transport in groundwater, the spatial distribution of these highly reactive zones, compared to the volume of the whole plume, is quite small and characterized by steep concentration gradients, which can not be detected using standard monitoring procedures. High resolution multi-level sampling (MLS) in the order of 0.1m or less is an essential prerequisite for the investigation of NA processes within the reactive fringes at field scale. This contribution presents results from ongoing research on high resolution MLS at six field sites in different European countries. The focus was on an optimized site-specific hydraulic design and contaminant - MLS-material interaction. Most acceptable solutions (which means MLS resolution in the order of 0.1m) were found using sampling tubes with a small inner diameter (3-4mm). This results in a small stagnant water volume prior to sampling, but is still not problematic with respect to the flow induced hydraulic losses within the tube. Another requirement for high resolution sampling was to abandon standard sampling protocols (DIN, EPA, .) which often demand huge groundwater volumes (1 liter) for every single compound to be analyzed. To estimate the effects of the tubing material on the quality of the groundwater samples, an analytical model by Reynolds et al. (1990) was used to study the sorptive uptake of different organics by different tubing polymers, considering partitioning coefficients, intra-polymeric diffusion coefficients and tube-surface to tube-volume ratios.

Piepenbrink, M.; Ptak, T.; Grathwohl, P.

2003-12-01

419

Bidirectional Texture Function Compression Based on MultiLevel Vector Quantization  

Microsoft Academic Search

The Bidirectional Texture Function (BTF) is becoming widely used for accurate representation of real-world material appearance. In this paper a novel BTF compression model is proposed. The model resamples input BTF data into a parametrization, allowing decomposition of individual view and illumination dependent texels into a set of multi-dimensional conditional probability density functions. These functions are compressed in turn using

Vlastimil Havran; J. Filip; Karol Myszkowski

2010-01-01

420

Sub-genomic level sequence analysis of the aquaporin multi-gene family in cotton  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aquaporins function mainly as water transport channel proteins that facilitate water movement across intracellular and intercellular membranes in most living organisms. Plant aquaporins belong to a multi-gene family and are commonly categorized into 5 subfamilies according to sequence similarity. Re...

421

Friendship Patterns in Multi-Cultural Group: International Communication at the Personal Level.  

ERIC Educational Resources Information Center

|This paper examines the process of interpersonal communication across cultural boundaries, through a combination of the cross-cultural approach (from international communication research) and the interpersonal approach (from sociological research). The paper presents data on friendship patterns in a multi-cultural group. The experimenter observed…

Chu, Godwin C.

422

Observation of discrete quantum levels in multi-wall carbon nanotube quantum dots  

Microsoft Academic Search

Quantum dots with a size less than 100nm have been fabricated in multi-wall carbon nanotubes (MWNTs) by using the local Ar beam irradiation technique for tunnel barrier formation. The electrical transport measurement has been carried out at liquid helium temperatures, and the typical Coulomb blockade characteristics have been observed. The most striking observation is the clear indication of excited states,

D. Tsuya; M. Suzuki; S. Moriyama; Y. Aoyagi; K. Ishibashi

2004-01-01

423

RF interconnect for multi-gbit\\/s board-level clock distribution  

Microsoft Academic Search

With clock distribution of over 1 GHz, problems associated with clock skew, power consumption, and timing jitter are becoming critical for determining the processing speed of high-performance digital systems, especially for multi-processor systems. Conventional digital clock distribution interconnection has a severe power consumption problem for GHz clock distribution because of the transmission line losses, as well as exhibiting difficult signal

Woonghwan Ryu; Junwoo Lee; Hyungsoo Kim; Seungyoung Ahn; Namhoon Kim; Baekkyu Choi; Donggun Kam; Joungho Kim

2000-01-01

424

Integral inverter/battery charger for use in electric vehicles. Final report  

SciTech Connect

The design and test results of a thyristor based inverter/charger are discussed. A battery charger is included integral to the inverter by using a subset of the inverter power circuit components. The resulting charger provides electrical isolation between the vehicle propulsion battery and ac line and is capable of charging a 25 kWh propulsion battery in 8 hours from a 220 volt ac line. The integral charger employs the inverter commutation components as a resonant ac/dc isolated converter rated at 3.6 kW. Charger efficiency and power factor at an output power of 3.6 kW are 86% and 95%, respectively. The inverter, when operated with a matching polyphase ac induction motor and nominal 132 volt propulsion battery, can provide a peak shaft power of 34 kW (45 hp) during motoring operation and 45 kW (60 hp) during regeneration. Thyristors are employed for the inverter power switching devices and are arranged in an input-commutated topology. This configuration requires only two thyristors to commutate the six main inverter thyristors. Inverter efficiency during motoring operation at motor shaft speeds above 450 rad/sec (4300 rpm) is 92 to 94% for output power levels above 11 KW (15 hp). The combined ac inverter/charger package weighs 47 kg (103 lbs).

Thimmesch, D.

1983-09-01

425

Complex carbon cycle responses to multi-level warming and supplemental summer rain in the high Arctic.  

PubMed

The Arctic has experienced rapid warming and, although there are uncertainties, increases in precipitation are projected to accompany future warming. Climate changes are expected to affect magnitudes of gross ecosystem photosynthesis (GEP), ecosystem respiration (ER) and the net ecosystem exchange of CO2 (NEE). Furthermore, ecosystem responses to climate change are likely to be characterized by nonlinearities, thresholds and interactions among system components and the driving variables. These complex interactions increase the difficulty of predicting responses to climate change and necessitate the use of manipulative experiments. In 2003, we established a long-term, multi-level and multi-factor climate change experiment in a polar semidesert in northwest Greenland. Two levels of heating (30 and 60 W m(-2) ) were applied and the higher level was combined with supplemental summer rain. We made plot-level measurements of CO2 exchange, plant community composition, foliar nitrogen concentrations, leaf ?(13) C and NDVI to examine responses to our treatments at ecosystem- and leaf-levels. We confronted simple models of GEP and ER with our data to test hypotheses regarding key drivers of CO2 exchange and to estimate growing season CO2 -C budgets. Low-level warming increased the magnitude of the ecosystem C sink. Meanwhile, high-level warming made the ecosystem a source of C to the atmosphere. When high-level warming was combined with increased summer rain, the ecosystem became a C sink of magnitude similar to that observed under low-level warming. Competition among our ER models revealed the importance of soil moisture as a driving variable, likely through its effects on microbial activity and nutrient cycling. Measurements of community composition and proxies for leaf-level physiology suggest GEP responses largely reflect changes in leaf area of Salix arctica, rather than changes in leaf-level physiology. Our findings indicate that the sign and magnitude of the future High Arctic C budget may depend upon changes in summer rain. PMID:23504924

Sharp, Elizabeth D; Sullivan, Patrick F; Steltzer, Heidi; Csank, Adam Z; Welker, Jeffrey M

2013-03-09

426

OptCom: a multi-level optimization framework for the metabolic modeling and analysis of microbial communities.  

PubMed

Microorganisms rarely live isolated in their natural environments but rather function in consolidated and socializing communities. Despite the growing availability of high-throughput sequencing and metagenomic data, we still know very little about the metabolic contributions of individual microbial players within an ecological niche and the extent and directionality of interactions among them. This calls for development of efficient modeling frameworks to shed light on less understood aspects of metabolism in microbial communities. Here, we introduce OptCom, a comprehensive flux balance analysis framework for microbial communities, which relies on a multi-level and multi-objective optimization formulation to properly describe trade-offs between individual vs. community level fitness criteria. In contrast to earlier approaches that rely on a single objective function, here, we consider species-level fitness criteria for the inner problems while relying on community-level objective maximization for the outer problem. OptCom is general enough to capture any type of interactions (positive, negative or combinations thereof) and is capable of accommodating any number of microbial species (or guilds) involved. We applied OptCom to quantify the syntrophic association in a well-characterized two-species microbial system, assess the level of sub-optimal growth in phototrophic microbial mats, and elucidate the extent and direction of inter-species metabolite and electron transfer in a model microbial community. We also used OptCom to examine addition of a new member to an existing community. Our study demonstrates the importance of trade-offs between species- and community-level fitness driving forces and lays the foundation for metabolic-driven analysis of various types of interactions in multi-species microbial systems using genome-scale metabolic models. PMID:22319433

Zomorrodi, Ali R; Maranas, Costas D

2012-02-02

427

Evaluation of Register-Level Protection Techniques for the Advanced Encryption Standard by MultiLevel Fault Injections  

Microsoft Academic Search

Some protection techniques had been previously proposed for encryption blocks and applied to an AES encryption IP described at RT Level. One of these techniques had been validated by purely functional fault injections (i.e. algorithmic-level fault injections) against single- and multiple- bit errors. RT-Level fault injections have been performed recently on a few AES IPs and this paper summarizes the

Paolo Maistri; Pierre Vanhauwaert; Régis Leveugle

2007-01-01

428

A public health framework to translate risk factors related to political violence and war into multi-level preventive interventions.  

PubMed

Political violence, armed conflicts and human rights violations are produced by a variety of political, economic and socio-cultural factors. Conflicts can be analyzed with an interdisciplinary approach to obtain a global understanding of the relative contribution of risk and protective factors. A public health framework was designed to address these risk factors and protective factors. The framework resulted in a matrix that combined primary, secondary and tertiary interventions with their implementation on the levels of the society-at-large, the community, and the family and individual. Subsequently, the risk and protective factors were translated into multi-sectoral, multi-modal and multi-level preventive interventions involving the economy, governance, diplomacy, the military, human rights, agriculture, health, and education. Then the interventions were slotted in their appropriate place in the matrix. The interventions can be applied in an integrative form by international agencies, governments and non-governmental organizations, and molded to meet the requirements of the historic, political-economic and socio-cultural context. The framework maps the complementary fit among the different actors while engaging themselves in preventive, rehabilitative and reconstructive interventions. The framework shows how the economic, diplomatic, political, criminal justice, human rights, military, health and rural development sectors can collaborate to promote peace or prevent the aggravation or continuation of violence. A deeper understanding of the association between risk and protective factors and the developmental pathways of generic, country-specific and culture-specific factors leading to political violence is needed. PMID:19883967

De Jong, Joop T V M

2009-10-31

429

Capacitor Voltage Balancing Schemes in Flying Capacitor Multilevel Inverters  

Microsoft Academic Search

This paper focuses on the development of capacitor voltage balancing methods in a flying capacitor multilevel inverter (FCMLI). Three such strategies have been described and have been applied to a five-level CMLI. The sinusoidal pulse width modulation technique has been used while making the proposals. The first scheme works on the principle of selection of the most favorable switching state

Anshuman Shukla; A. Ghosh; A. Joshi

2007-01-01

430

Brain activity evoked by inverted and imagined biological motion  

Microsoft Academic Search

Previous imaging research has identified an area on the human posterior superior temporal sulcus (STS) activated upon viewing biological motion. The current experiments explore the relationship between neural activity within this region and perceptual experience. Biological motion perception is orientation dependent: inverting point-light animations make them more difficult to see. We measured activity levels within this region as observers viewed

E. D. Grossman; R. Blake

2001-01-01

431

The evaluation of a multi-level oral health intervention to improve oral health practices among caregivers of preschool children.  

PubMed

Abstract. This study reports the effects of a pilot multi-level oral health intervention on caregivers' oral health practices and their determinants. Quasi-experimental, pretest-posttest evaluations using a comparison group design were employed to evaluate the effectiveness of a proposed intervention for promoting caregiver oral health behavior. The intervention consisted of three components: home visits by lay health workers (LHWs), enhancing oral health education and services at health centers, and community mobilization. These components were designed to target factors at intrapersonal, interpersonal, organizational and community levels based on a Social Ecological Model (SEM). Four oral health behaviors associated with early childhood caries (infant bottle feeding, tooth brushing, snack consumption and fluoride use), and multi-level determinants were assessed during pre- and post-tests. The one-year intervention demonstrated a positive effect on tooth brushing, using toothpaste, and fluoride supplements, but did not have a significant effect on bottle feeding and snack consumption among children. The intervention also had no effect on dental caries; in fact caries increased in both control and experimental groups. The caregiver knowledge, attitudes, outcome expectations, and self-efficacy towards these behaviors were significantly increased in the experimental group after intervention. Caregivers in the experimental group received greater social support by LHWs and health center staff than those in the control group (p < 0.001). The program had an impact on integrating oral health services at health centers and community participation in children's oral health. These findings confirm multi-level factors influence reported oral health behavior, but not outcomes in terms of caries. Process evaluation is needed to determine actual implementation levels, barriers and suggests for modification of the program in the future to improve outcomes in terms of caries. PMID:23082602

Vichayanrat, Tippanart; Steckler, Allan; Tanasugarn, Chanuantong; Lexomboon, Duangjai

2012-03-01

432

Fabrication of organic complementary inverter  

NASA Astrophysics Data System (ADS)

We have fabricated organic complementary inverter comprised of p-channel copper phthalocyanine(CuPc) and n-channel hexadecafluoro phthalocyanine (F16CuPc) based organic thin film transistors (OTFTs) with single Cu metal electrode for both type of OTFTs. The work function of Cu is nearly equal to the highest occupied molecular orbital (HOMO) of CuPc and lowest unoccupied molecular orbital (LUMO) of F16CuPc hence it can be used as source/drain electrode for both type of OTFTs which shows field effect mobilities of CuPc and F16CuPc based OTFTs are 1.27x10-3cm2V-1S-1 and 3.30x10-4cm2V- 1S-1 respectively. Voltage transfer characteristics of complementary inverter show high noise margins and switching voltage around VDD/2 with a maximum gain in the order of 20.

Yadav, Sarita; Ghosh, Subhasis

2012-10-01

433

Simulation of Multi-Robot Teams with Flexible Level of Detail  

Microsoft Academic Search

A key methodology for the development of autonomous robots is testing using simulated robot motion and sensing systems. An impor- tant issue when simulating teams of heterogeneous autonomous robots is performance versus accuracy. In this paper the multi-robot-simulation framework (MuRoSimF) is presented which allows the exible and trans- parent exchange and combination of the algorithms used for the simula- tion

Martin Friedmann; Karen Petersen; Oskar Von Stryk

2008-01-01

434

Multi-finger pressing synergies change with the level of extra degrees of freedom  

Microsoft Academic Search

The purpose of this study was to test the principle of motor abundance, which has been hypothesized as the principle by which\\u000a the central nervous system controls the excessive degrees of freedom of the human movements, in contrast to the traditional\\u000a negative view of motor redundancy. This study investigated the changes in force stabilizing and moment stabilizing synergies\\u000a for multi-finger

Sohit Karol; You-Sin Kim; Junfeng Huang; Yoon Hyuk Kim; Kyung Koh; Bum Chul Yoon; Jae Kun Shim

2011-01-01

435

MultiCharge Carrier Trapping in Organic Crystals: Quantized Internal Macrotrap Energy Levels  

Microsoft Academic Search

Multi-charge carrier capture by each member of a set of discrete spatially extended domains (macrotraps) is considered as a trapping mechanism responsible for the space charge evolution in the high-concentration regime of the charge introduced to organic crystals.Finite dimension and energy depth limit the number of carriers of the same sign to be captured by such a macrotrap. Due to

J. Kalinowski; J. Godlewski

1991-01-01

436

Entanglement of Grassmannian Coherent States for MultiPartite n-Level Systems  

Microsoft Academic Search

In this paper, we investigate the entanglement of multi-partite Grassmannian coherent states (GCSs) described by Grassmann numbers for $n>2$ degree of nilpotency. Choosing an appropriate weight function, we show that it is possible to construct some well-known entangled pure states, consisting of {\\\\bf GHZ}, {\\\\bf W}, Bell, cluster type and bi-separable states, which are obtained by integrating over tensor product

Ghader Najarbashi; Yusef Maleki

2010-01-01

437

Polarization interference of multi-wave mixing in a confined five-level system  

Microsoft Academic Search

We investigated the coexisting four-wave mixing, six-wave mixing and eight-wave mixing in ultra-thin, micrometer and long cells. Such multi-wave mixing (MWM) processes can be modified by the polarization interference. The degree of destructive interference of atomic polarizations can be controlled by the wave vector, dressing field and cell length. Specifically, the oscillation behavior of intensity and linewidth of MWM signal

Changbiao Li; Yanpeng Zhang; Zhiguo Wang; Yuanyuan Li; Zhiqiang Nie; Yan Zhao; Ruimin Wang; Chenzhi Yuan; Keqing Lu

2011-01-01

438

Multi-attribute evaluation of landscape-level fuel management to reduce wildfire risk  

Microsoft Academic Search

This paper provides an example of the practical application of multi-attribute trade-off analysis (MATA) to wildfire management. The MATA approach supports more informed decision-making because it exposes important trade-offs among competing management objectives (requiring value-based choices), helps guide and structure necessary technical judgements, explicitly represents uncertainty (i.e., not just expected outcomes but risk profiles around outcomes) and addresses temporal trade-offs.

Dan W. Ohlson; Trent M. Berry; Robert W. Gray; Bruce A. Blackwell; Brad C. Hawkes

2006-01-01

439

Floating-Gate UVMOS inverter  

Microsoft Academic Search

This paper describes a novel technique for implementing low -voltage\\/low-power digital circuits. The threshold and supply voltage can be set to desired valueswhile exposing the chip to UV-light. UV-light activated conductances between the power supply- rails and the floating gates are used to program the desired threshold shift. The FGUVMOS inverter i s described and measurements are shown.

Yngvar Berg; Dag T. Wisland; Tor Sverre Lande

1997-01-01

440

An empirical study of statistical properties of variance partition coefficients for multi-level logistic regression models  

USGS Publications Warehouse

Partitioning the variance of a response by design levels is challenging for binomial and other discrete outcomes. Goldstein (2003) proposed four definitions for variance partitioning coefficients (VPC) under a two-level logistic regression model. In this study, we explicitly derived formulae for multi-level logistic regression model and subsequently studied the distributional properties of the calculated VPCs. Using simulations and a vegetation dataset, we demonstrated associations between different VPC definitions, the importance of methods for estimating VPCs (by comparing VPC obtained using Laplace and penalized quasilikehood methods), and bivariate dependence between VPCs calculated at different levels. Such an empirical study lends an immediate support to wider applications of VPC in scientific data analysis.

Li, J.; Gray, B. R.; Bates, D. M.

2008-01-01

441

Complementary-like semiconducting graphene logic inverters  

NASA Astrophysics Data System (ADS)

The application of graphene as a post-silicon channel material is an interesting but challenging topic due to its metallic nature and low switching ratio. It is expected that the condition would change if a sizeable band gap is introduced. Here we report the electrical characteristics of the first semiconducting graphene-based logic inverters. Free of doping, the p- and n- branches in the bipolar graphene transistors are delicately used as the complementary components required in logic devices. Within perpendicular electric fields, large transport band gap (>100,eV) and high switching ratio (˜200 at 77,) are obtained in bilayer graphene channels. Besides, a simple and high capacitive-efficiency top gate with natural alumina dielectric (˜0.9,?F/cm^2) is adopted and the operating bias is lowered within 2,. For the first time, >1 voltage gain are extracted from graphene inverters. Voltage gain up to 8 and 2 are achieved at liquid-nitrogen and room temperatures, respectively. Importantly, a match between input and output voltage levels is realized, indicating the potential for direct cascading between multiple devices for future large-scale integration.

Li, Song-Lin; Miyazaki, Hisao; Tsukagoshi, Kazuhito; Kanda, Akinobu

2011-03-01

442

A novel alignment mechanism employing orthogonal connected multi-layered flexible hinges for both leveling and centering  

NASA Astrophysics Data System (ADS)

To eliminate the effects of motion coupling for measuring cylindrical work pieces, a novel alignment mechanism integrating functions of both leveling and centering is designed and fabricated by introducing multi-layered orthogonal connected flexible hinges as the key supporting and joining elements. Different from traditional leveling mechanisms with many separate parts fabricated together, all of the flexible hinges were integrated in one three-dimensioned machining part without assembling process, and thus synchronously simplifying the structure and reducing assembly errors. Based on the screw theory, the mathematic model of the proposed alignment mechanism is established for any resolution requirements depending on screw characteristics. A millimeter-sized device is fabricated with the alignment precision of 1.0 ?m for centering within the range of +/-1 mm and 1 in. for leveling within +/-1°. The experiment results are in very close agreement to those obtained by simulation, which validate the feasibility of introducing multi-layered orthogonal flexible hinges in the centering and leveling mechanisms.

Zhao, Jian; Wang, Hongxi; Gao, Renjing; Hu, Ping; Yang, Yintang

2012-06-01

443

A novel alignment mechanism employing orthogonal connected multi-layered flexible hinges for both leveling and centering.  

PubMed

To eliminate the effects of motion coupling for measuring cylindrical work pieces, a novel alignment mechanism integrating functions of both leveling and centering is designed and fabricated by introducing multi-layered orthogonal connected flexible hinges as the key supporting and joining elements. Different from traditional leveling mechanisms with many separate parts fabricated together, all of the flexible hinges were integrated in one three-dimensioned machining part without assembling process, and thus synchronously simplifying the structure and reducing assembly errors. Based on the screw theory, the mathematic model of the proposed alignment mechanism is established for any resolution requirements depending on screw characteristics. A millimeter-sized device is fabricated with the alignment precision of 1.0 ?m for centering within the range of ±1 mm and 1 in. for leveling within ±1°. The experiment results are in very close agreement to those obtained by simulation, which validate the feasibility of introducing multi-layered orthogonal flexible hinges in the centering and leveling mechanisms. PMID:22755657

Zhao, Jian; Wang, Hongxi; Gao, Renjing; Hu, Ping; Yang, Yintang

2012-06-01

444

Continuum Level Formulation and Implementation of a Multi-scale Model for Vanadium  

SciTech Connect

A multi-scale approach is used to construct a continuum strength model for vanadium. The model is formulated assuming plastic deformation by dislocation motion and strain hardening due to dislocation interactions. Dislocation density is adopted as the state variable in the model. Information from molecular statics, molecular dynamics and dislocation dynamics simulations is combined to create kinetic relations for dislocation motion, strain hardening relations and evolution equations for the dislocation density. Implicit time integration of the constitutive equations is described in the context of implementation in a finite element code. Results are provided illustrating the strain, strain rate, temperature and pressure dependence of the constitutive model.

Lawrence Livermore National Laboratory

2009-08-17

445

Regulation of hSos1 activity is a system-level property generated by its multi-domain structure.  

PubMed

The multi-domain protein hSos1 plays a major role in cell growth and differentiation through its Ras-specific guanine nucleotide exchange domain whose complex regulation involves intra-molecular, inter-domain rearrangements. We present a stochastic mathematical model describing intra-molecular regulation of hSos1 activity. The population macroscopic effect is reproduced through a Monte-Carlo approach. Key model parameters have been experimentally determined by BIAcore analysis. Complementation experiments of a Saccharomyces cerevisiae cdc25(ts) strain with Sos deletion mutants provided a comprehensive data set for estimation of unknown parameters and model validation. The model is robust against parameter alteration and describes both the behavior of Sos deletion mutants and modulation of activity of the full length molecule under physiological conditions. By incorporating the calculated effect of amino acid changes at an inter-domain interface, the behavior of a mutant correlating with a developmental syndrome could be simulated, further validating the model. The activation state of Ras-specific guanine nucleotide exchange domain of hSos1 arises as an "emergent property" of its multi-domain structure that allows multi-level integration of a complex network of intra- and inter-molecular signals. PMID:21851854

Sacco, Elena; Farina, Marcello; Greco, Claudio; Lamperti, Stefano; Busti, Stefano; Degioia, Luca; Alberghina, Lilia; Liberati, Diego; Vanoni, Marco

2011-08-06

446

Care pathways across the primary-hospital care continuum: using the multi-level framework in explaining care coordination  

PubMed Central

Background Care pathways are widely used in hospitals for a structured and detailed planning of the care process. There is a growing interest in extending care pathways into primary care to improve quality of care by increasing care coordination. Evidence is sparse about the relationship between care pathways and care coordination. The multi-level framework explores care coordination across organizations and states that (inter)organizational mechanisms have an effect on the relationships between healthcare professionals, resulting in quality and efficiency of care. The aim of this study was to assess the extent to which care pathways support or create elements of the multi-level framework necessary to improve care coordination across the primary - hospital care continuum. Methods This study is an in-depth analysis of five existing local community projects located in four different regions in Flanders (Belgium) to determine whether the available empirical evidence supported or refuted the theoretical expectations from the multi-level framework. Data were gathered using mixed methods, including structured face-to-face interviews, participant observations, documentation and a focus group. Multiple cases were analyzed performing a cross case synthesis to strengthen the results. Results The development of a care pathway across the primary-hospital care continuum, supported by a step-by-step scenario, led to the use of existing and newly constructed structures, data monitoring and the development of information tools. The construction and use of these inter-organizational mechanisms had a positive effect on exchanging information, formulating and sharing goals, defining and knowing each other’s roles, expectations and competences and building qualitative relationships. Conclusion Care pathways across the primary-hospital care continuum enhance the components of care coordination.

2013-01-01

447

Evaluation of multi-level social learning for sustainable landscapes: perspective of a development initiative in Bergslagen, Sweden.  

PubMed

To implement policies about sustainable landscapes and rural development necessitates social learning about states and trends of sustainability indicators, norms that define sustainability, and adaptive multi-level governance. We evaluate the extent to which social learning at multiple governance levels for sustainable landscapes occur in 18 local development initiatives in the network of Sustainable Bergslagen in Sweden. We mapped activities over time, and interviewed key actors in the network about social learning. While activities resulted in exchange of experiences and some local solutions, a major challenge was to secure systematic social learning and make new knowledge explicit at multiple levels. None of the development initiatives used a systematic approach to secure social learning, and sustainability assessments were not made systematically. We discuss how social learning can be improved, and how a learning network of development initiatives could be realized. PMID:23475659

Axelsson, Robert; Angelstam, Per; Myhrman, Lennart; Sädbom, Stefan; Ivarsson, Milis; Elbakidze, Marine; Andersson, Kenneth; Cupa, Petr; Diry, Christian; Doyon, Frederic; Drotz, Marcus K; Hjorth, Arne; Hermansson, Jan Olof; Kullberg, Thomas; Lickers, F Henry; McTaggart, Johanna; Olsson, Anders; Pautov, Yurij; Svensson, Lennart; Törnblom, Johan

2013-03-01

448

Adaptive Coping under Conditions of Extreme Stress: Multi-Level Influences on the Determinants of Resilience in Maltreated Children  

PubMed Central

The study of resilience in maltreated children reveals the possibility of coping processes and resources on multiple levels of analysis, as children strive to adapt under conditions of severe stress. In a maltreating context, aspects of self-organization, including self esteem, self reliance, emotion regulation, and adaptable yet reserved personalities appear particularly important for more competent coping. Moreover, individual differences in biological processes ranging from gene by environment interactions to the HPA axis to brain organization related to emotion also are shown to influence the resilience in maltreated youth, highlighting the multi-faceted contributions to successful coping.

Cicchetti, Dante; Rogosch, Fred A.

2013-01-01

449

Identification of condition-specific regulatory modules through multi-level motif and mRNA expression analysis  

PubMed Central

Many computational methods for identification of transcription regulatory modules often result in many false positives in practice due to noise sources of binding information and gene expression profiling data. In this paper, we propose a multi-level strategy for condition-specific gene regulatory module identification by integrating motif binding information and gene expression data through support vector regression and significant analysis. We have demonstrated the feasibility of the proposed method on a yeast cell cycle data set. The study on a breast cancer microarray data set shows that it can successfully identify the significant and reliable regulatory modules associated with breast cancer.

Chen, Li; Wang, Yue; Hoffman, Eric P.; Riggins, Rebecca B.; Clarke, Robert

2013-01-01

450

Preconditioned iterative solver on the coarsest level of a multi-grid method for high frequency time harmonic electromagnetic field analyses  

Microsoft Academic Search

A multi-grid method is one of the most powerful linear solvers for finite element electromagnetic field analysis. However,\\u000a as the discretized model has recently been enlarged, a solution process for a linear system arising on the coarsest level\\u000a tends to be problematic in a complete multi-grid solution process. Whereas a linear system on the coarsest level is generally\\u000a solved by

T. Iwashita; K. Yosui; M. Mori; E. Kobayashi; S. Abe

2008-01-01

451

Multilevel Inverters for Electric Vehicle Applications  

SciTech Connect

This paper presents multilevel inverters as an application for all-electric vehicle (EV) and hybrid-electric vehicle (HEV) motor drives. Diode-clamped inverters and cascaded H-bridge inverters, (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference (EMI) and common-mode voltage; and (3) make an EV more accessible/safer and open wiring possible for most of an EV'S power system. This paper explores the benefits and discusses control schemes of the cascade inverter for use as an EV motor drive or a parallel HEV drive and the diode-clamped inverter as a series HEV motor drive. Analytical, simulated, and experimental results show the superiority of these multilevel inverters for this new niche.

Habetler, T.G.; Peng, F.Z.; Tolbert, L.M.

1998-10-22

452

System and method for regulating resonant inverters  

DOEpatents

A technique is provided for direct digital phase control of resonant inverters based on sensing of one or more parameters of the resonant inverter. The resonant inverter control system includes a switching circuit for applying power signals to the resonant inverter and a sensor for sensing one or more parameters of the resonant inverter. The one or more parameters are representative of a phase angle. The resonant inverter control system also includes a comparator for comparing the one or more parameters to a reference value and a digital controller for determining timing of the one or more parameters and for regulating operation of the switching circuit based upon the timing of the one or more parameters.

Stevanovic, Ljubisa Dragoljub (Clifton Park, NY); Zane, Regan Andrew (Superior, CO)

2007-08-28

453

Inverting Amplifier with Current Input  

NSDL National Science Digital Library

This animated gif illustrates the changing voltages a conventional inverting amplifier when it receives input from a current source rather than a voltage source. Notice that the input resistor does not offer any impedance. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations.Other 3-D Circuit Animations can be seen here.

2009-11-23

454

Organic light emitting complementary inverters  

NASA Astrophysics Data System (ADS)

We show that p- and n-type light emitting field-effect transistors (LEFETs) can be made using ``superyellow'' as a light-emitting polymer, poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) as a p-type material and a naphthalene di-imide as an n-type material. By connecting two of these LEFETs, we have demonstrated a light emitting complementary inverter (LECI). The LECI exhibited electrical and optical characteristics in the first and third quadrant of the transfer characteristics with voltage gain of 6 and 8, respectively.

Namdas, Ebinazar B.; Samuel, Ifor D. W.; Shukla, Deepak; Meyer, Dianne M.; Sun, Yanming; Hsu, Ben B. Y.; Moses, Daniel; Heeger, Alan J.

2010-01-01

455

High-Frequency Link: A Solution for Using Only One DC Source in Asymmetric Cascaded Multilevel Inverters  

Microsoft Academic Search

Multilevel inverters are in state-of-the-art power con- version systems due to their improved voltage and current wave- forms. Cascaded H-bridge (CHB) multilevel inverters have been considered as an alternative in the medium-voltage converter mar- ket and experimental electric vehicles. Their variant, the asymmet- rical CHB (ACHB) inverter, optimizes the number of voltage levels by using dc supplies with different voltages.

Javier Pereda; Juan Dixon

2011-01-01

456

A new grid-connected PV system based on cascaded H-bridge quasi-Z source inverter  

Microsoft Academic Search

A new scheme for grid-connected photovoltaic (PV) interface by combination of a quasi-Z source inverter (qZSI) into cascaded H-bridge (CHB) is proposed in this paper. The proposed scheme enables PV string voltage boost to a higher level, and solves the imbalance problem of DC-link voltage in traditional CHB inverters. A multilevel voltage waveform of inverter output is generated by an

Dongsen Sun; Baoming Ge; Fang Zheng Peng; Abu Rub Haitham; Daqiang Bi; Yushan Liu

2012-01-01

457

Poly-use multi-level sampling system for soil-gas transport analysis in the vadose zone.  

PubMed

Soil-gas turnover is important in the global cycling of greenhouse gases. The analysis of soil-gas profiles provides quantitative information on below-ground turnover and fluxes. We developed a poly-use multi-level sampling system (PMLS) for soil-gas sampling, water-content and temperature measurement with high depth resolution and minimal soil disturbance. It is based on perforated access tubes (ATs) permanently installed in the soil. A multi-level sampler allows extraction of soil-gas samples from 20 locations within 1 m depth, while a capacitance probe is used to measure volumetric water contents. During idle times, the ATs are sealed and can be equipped with temperature sensors. Proof-of-concept experiments in a field lysimeter showed good agreement of soil-gas samples and water-content measurements compared with conventional techniques, while a successfully performed gas-tracer test demonstrated the feasibility of the PMLS to determine soil-gas diffusion coefficients in situ. A field application of the PMLS to quantify oxidation of atmospheric CH4 in a field lysimeter and in the forefield of a receding glacier yielded activity coefficients and soil-atmosphere fluxes well in agreement with previous studies. With numerous options for customization, the presented tool extends the methodological choices to investigate soil-gas transport in the vadose zone. PMID:23962070

Nauer, Philipp A; Chiri, Eleonora; Schroth, Martin H

2013-09-10

458

Efficient multi-level fault simulation of HW\\/SW systems for structural faults  

Microsoft Academic Search

In recent technology nodes, reliability is increasingly considered a part of the standard design flow to be taken into account\\u000a at all levels of embedded systems design. While traditional fault simulation techniques based on low-level models at gate-\\u000a and register transfer-level offer high accuracy, they are too inefficient to properly cope with the complexity of modern embedded\\u000a systems. Moreover, they

Rafal Baranowski; Stefano Di Carlo; Nadereh Hatami; Michael E. Imhof; Michael A. Kochte; Paolo Prinetto; Hans-Joachim Wunderlich; Christian G. Zoellin

2011-01-01

459

Infant mortality: A multi-level analysis of individual and community risk factors  

Microsoft Academic Search

This paper reports the results of an analysis of infant mortality based on a conceptual model that combines micro-level and macro-level variables taken from demographic, sociological and epidemiological research traditions. Using generalized hierarchical linear modeling techniques, we analyze 1988 and 1989 linked birth and death records for Upstate New York matched with county-level data from government and private sources. Net

Donald W. Matteson; Jeffrey A. Burr; James R. Marshall

1998-01-01

460

Opal: A MultiLevel Infrastructure for Agent-Oriented Software Development  

Microsoft Academic Search

The Opal architecture for software development is described that supports the use of agent-oriented concepts at multiple levels of abstraction. At the lowest level are micro-agents, streamlined agents that can be used for conventional, system-level programming tasks. More sophisticated agents may be constructed by assembling combinations of micro-agents. The architecture consequently supports the systematic use of agent-based notions throughout the

M. Purvis; S. Cranefield; M. Nowostawski; D. Carter

2002-01-01

461

A multi-level capacitor-less memory cell fabricated on a nano-scale strained silicon-on-insulator.  

PubMed

A multi-level capacitor-less memory cell was fabricated with a fully depleted n-metal-oxide-semiconductor field-effect transistor on a nano-scale strained silicon channel on insulator (FD sSOI n-MOSFET). The 0.73% biaxial tensile strain in the silicon channel of the FD sSOI n-MOSFET enhanced the effective electron mobility to ? 1.7 times that with an unstrained silicon channel. This thereby enables both front- and back-gate cell operations, demonstrating eight-level volatile memory-cell operation with a 1 ms retention time and 12 µA memory margin. This is a step toward achieving a terabit volatile memory cell. PMID:21730757

Park, Jea-Gun; Kim, Seong-Je; Shin, Mi-Hee; Song, Seung-Hyun; Chung, Sung-Woong; Enomoto, Hirofumi; Shim, Tae-Hun

2011-07-06

462

Multi-level consistency tests in paleointensity determinations from the welded tuffs of the Aso pyroclastic-flow deposits  

NASA Astrophysics Data System (ADS)

We have performed multi-level consistency tests in an LTD-DHT Shaw paleointensity study on the welded tuffs of the Aso pyroclastic-flow deposits (Aso-1, Aso-2, Aso-3, and Aso-4) in order to obtain reliable mean paleointensities from each unit. For a unit-level consistency test, we collected samples at three or more sites in each unit. To enhance a site-level consistency test, we conducted paleointensity experiments on both whole-rock and glass samples from the same sites. Thermal demagnetization curves of the samples indicate that the main magnetic carrier is titanium-poor titanomagnetite to pure magnetite. Hysteresis parameters are different among the sites of the same units. Also, differences in unblocking spectra and hysteresis parameters are recognized between the whole-rock and glass samples from the same sites. Therefore, these samples of various properties are expected to work effectively for multi-level consistency test. Twenty-nine out of 65 whole-rock samples and 10 out of 31 glass samples gave accepted paleointensity results. At the site-level, consistency of paleointensity estimates is observed with the exception of one site. Two paleointensity estimates from glass samples of a site of Aso-4 are inconsistent and are excluded from further analysis. At the unit-level, consistency or inconsistency among the sites is observed for individual units. For Aso-1, inconsistency in paleointensity estimates among the sites is observed and we can recognize more reliable results from two sites. For Aso-2, consistency in paleointensity estimates from glass and whole-rock samples supports the acceptance of a site. For Aso-3, all paleointensity estimates from two sites are thought to be reliable because consistency between the site-means of the two sites as well as site-level consistency between the glass and whole-rock samples for each site is recognized. For Aso-4, some difference among the sites is observed, but there is no obvious reason to exclude the results of particular sites. Overall, both the site-level and unit-level consistency checks work effectively in these samples which confirm the reliability of the paleointensity estimates or highlights the erroneous ones. On the basis of the reliable paleointensity estimates, unit-mean values are obtained as 24.9 ± 2.2 (1?) ?T (N = 9) for Aso-1, 22.9 ± 1.6 ?T (N = 5) for Aso-2, 28.3 ± 3.4 ?T (N = 10) for Aso-3, and 40.1 ± 6.2 ?T (N = 7) for Aso-4.

Mochizuki, Nobutatsu; Maruuchi, Toru; Yamamoto, Yuhji; Shibuya, Hidetoshi

2013-10-01

463

Multi-Grained Level of Detail for Rendering Complex Meshes Using a Hierarchical Seamless Texture Atlas.  

National Technical Information Service (NTIS)

Previous algorithms for view-dependent level of detail provide local mesh refinements either at the finest granularity or at a fixed, coarse granularity. The former provides triangle-level adaptation, often at the expense of heavy CPU usage and low triang...

B. Purnomo J. Cohen K. Niski

2006-01-01

464

Income inequality and self-rated health in US metropolitan areas: A multi-level analysis  

Microsoft Academic Search

Income inequality has been found to affect health in a number of international and cross-national studies. Using data from a telephone survey of adults in the United States, this study analyzed the effect of metropolitan level income inequality on self-rated health. It combined individual data from the 2000 Behavioral Risk Factor Surveillance System with metropolitan level income data from the

Russ Lopez

2004-01-01

465

Measuring lake water level using multi-source remote sensing images combined with hydrological statistical data  

Microsoft Academic Search

The Poyang Lake, as one of the most frequently flooded area, is the largest freshwater lake in China. It is very significant to monitor the water level and water regime accurately and in real-time during flooding. To provide an operational method to measure shape parameters, such as water level, water regime area, and water distribution of Poyang Lake using remote

Qulin Tan; Siwen Bi; Jiping Hu; Zhengjun Liu

2004-01-01

466

Predictors of Self-Directed Learning for Low-Qualified Employees: A Multi-Level Analysis  

ERIC Educational Resources Information Center

|Purpose: This study aims to examine which variables at the level of the individual employee and at the company level are predictors of self-directed learning in low-qualified employees. Methodology: Results were obtained from a sample of 408 low-qualified employees from 35 different companies. The companies were selected from the energy sector,…

Raemdonck, Isabel; van der Leeden, Rien; Valcke, Martin; Segers, Mien; Thijssen, Jo

2012-01-01

467

A Vulcano Expert System: Automatic Alert Level Estimation and GIS Visualization on top of a multi-parameter Data Base  

NASA Astrophysics Data System (ADS)

The success of volcano fast response systems including early warning of an imminent eruption lives through its connection capability to already installed monitoring systems. Also new temporary, possible wireless networks as well as combination of different raw and model data needs to be covered. In practice this means a high-dimensional, complicated (raw or already parameterised) data stream with different sampling rates and time histories that have to be stored and analysed. In the framework of the Exupery project (GEOTECHNOLOGIEN, German Ministry for Education and Research - BMBF) the SeisHub Database handles multi-parameter data resulting from modern volcano monitoring networks simultaneously. This is a quite common situation today in order to assess volcanic activity. The warning system, here a GIS and an automatic alert level estimation, connects to the data base to retrieve the relevant information. The GIS provides access to the data as well as analysis results. By overlaying various parameters in the GIS systems the expert can analyse the situation and base his/her decision easily on multi-parameter data. In addition to data interactive visualization via the GIS the alert level of the volcano is automatically estimated using a Bayesian Belief Network (BBN) approach. This allows the expert to verify his own assessment versus the automatic system. In case there are major differences, the expert can identify the origin of the difference in the graphical representation of the BBN and if necessary adapt the BBN. BBNs are chosen because of their transparency (graphical representation), flexibility, probabilistic architecture and their possibility to incorporate expert knowledge. The probabilistic architecture allows to compute a confidence measure for the given alert level. A high, automatically estimated alert level with either high or low confidence can certainly lead to different decisions by the human interpreter.

Beyreuther, Moritz; Barsch, Robert; Bernsdorf, Stefan; Zakšek, Klemen; Wassermann, Joachim

2010-05-01

468

Review of PV Inverter Technology Cost and Performance Projections  

SciTech Connect

The National Renewable Energy Laboratory (NREL) has a major responsibility in the implementation of the U.S. Department of Energy's (DOE's) Solar Energy Technologies Program. Sandia National Laboratories (SNL) has a major role in supporting inverter development, characterization, standards, certifications, and verifications. The Solar Energy Technologies Program recently published a Multiyear Technical Plan, which establishes a goal of reducing the Levelized Energy Cost (LEC) for photovoltaic (PV) systems to $0.06/kWh by 2020. The Multiyear Technical Plan estimates that, in order to meet the PV system goal, PV inverter prices will need to decline to $0.25-0.30 Wp by 2020. DOE determined the need to conduct a rigorous review of the PV Program's technical and economic targets, including the target set for PV inverters. NREL requested that Navigant Consulting Inc.(NCI) conduct a review of historical and projected cost and performance improvements for PV inverters, including identification of critical barriers identified and the approaches government might use to address them.

Navigant Consulting Inc.

2006-01-01

469

Coherent coupling and energy transfer enhancement via multi-exciton levels in semiconductor nanocrystals  

NASA Astrophysics Data System (ADS)

The theory of coherent energy transfer (ET) in nanocrystal (NC) systems [1] is generalized for multiexciton levels. The relevant excitonic states in an isolated NC can be described by an effective four-level system, consisting of the ground level, two degenerate single exciton levels, and the biexciton level. We study the dynamics of a single donor-acceptor pair via the equation of motion for the density matrix of the system and consider analytical limits as well as numerical solutions. We show that the enhancement of the ET efficiency introduced by the biexciton levels is limited due to the coherent coupling of the exciton-biexciton levels in the donor-acceptor pair. The saturation of the ET rate in the donor-acceptor pair suggests a new mechanism to control the dipole-dipole coupling strength in NC systems, and we present here its dependence on structure parameters. [1] A. N. Al-Ahmadi and S. E. Ulloa, Phys. Rev. B 70, 201302(R) (2004).

Al-Ahmadi, Ameenah; Ulloa, Sergio

2008-03-01

470

A Multi-Level Approach to Investigating Neighborhood Effects on Physical Aggression among Urban Chicago Youth  

PubMed Central

The current study evaluates neighborhood effects, individual-level effects, and demographic characteristics that influence physically aggressive behavior among urban youth. Using data derived from 5,812 adolescents from Project Northland Chicago (PNC) and Heirarchical Linear Modeling (HLM) techniques, the results suggested that neighborhood problems significantly predicted physical aggression, before and after adjustment for individual-level risk factors (alcohol use, peer alcohol use, lack of adult supervision, and depression) and demographics. After accounting for baseline physical aggression, however, neighborhood problems were no longer a significant predictor of physical aggression. Implications for intervention at both the neighborhood and individual-level and study limitations are also discussed.

Maldonado-Molina, Mildred M.; Reingle, Jennifer M.; Komro, Kelli A.

2013-01-01

471

Etiological role of human papillomavirus infection for inverted papilloma of the bladder.  

PubMed

The status of human papillomavirus (HPV) infection in urothelial inverted papilloma was examined in the present study. Formalin-fixed and paraffin-embedded tissues from eight cases of inverted papilloma of the bladder were studied. The presence of HPV-DNA was examined by modified GP5/6+PCR using archival tissue sections by microdissection. HPV genotype was determined with a Hybri-Max HPV genotyping kit. Immunohistochemical analysis for p16-INK4a, mcm7, HPV-E4, and L1, and in situ hybridization for the HPV genome were performed. HPV was detected in seven of eight cases (87.5%) of inverted papilloma. Three cases were diagnosed as inverted papilloma with atypia, while the remaining five were typical cases. HPV-18 was detected in two cases, including one inverted papilloma with atypia, and HPV-16 was detected in four cases, including one inverted papilloma with atypia. Multiple HPV type infection was detected in one typical case and one atypical case. High-risk HPV was present in all HPV-positive cases. Cellular proteins, p16-INK4a and mcm7, which are surrogate markers for HPV-E7 expression, were detected in all HPV-positive cases, and their levels were higher in inverted papilloma with atypia than in typical cases. In contrast, HPV-E4 and L1, which are markers for HPV propagation, were observed in some parts of the typical inverted papilloma tissue. High-risk HPV infection may be one of the causes of urothelial inverted papilloma, and inverted papilloma with atypia may have malignant potential. PMID:21181923

Shigehara, Kazuyoshi; Sasagawa, Toshiyuki; Doorbar, John; Kawaguchi, Shohei; Kobori, Yoshitomo; Nakashima, Takao; Shimamura, Masayoshi; Maeda, Yuji; Miyagi, Tohru; Kitagawa, Yasuhide; Kadono, Yoshifumi; Konaka, Hiroyuki; Mizokami, Atsushi; Koh, Eitetsu; Namiki, Mikio

2011-02-01

472

A variational approach to multi-phase motion of gas, liquid and solid based on the level set method  

NASA Astrophysics Data System (ADS)

We propose a simple and robust numerical algorithm to deal with multi-phase motion of gas, liquid and solid based on the level set method [S. Osher, J.A. Sethian, Front propagating with curvature-dependent speed: Algorithms based on Hamilton-Jacobi formulation, J. Comput. Phys. 79 (1988) 12; M. Sussman, P. Smereka, S. Osher, A level set approach for capturing solution to incompressible two-phase flow, J. Comput. Phys. 114 (1994) 146; J.A. Sethian, Level Set Methods and Fast Marching Methods, Cambridge University Press, 1999; S. Osher, R. Fedkiw, Level Set Methods and Dynamics Implicit Surface, Applied Mathematical Sciences, vol. 153, Springer, 2003]. In Eulerian framework, to simulate interaction between a moving solid object and an interfacial flow, we need to define at least two functions (level set functions) to distinguish three materials. In such simulations, in general two functions overlap and/or disagree due to numerical errors such as numerical diffusion. In this paper, we resolved the problem using the idea of the active contour model [M. Kass, A. Witkin, D. Terzopoulos, Snakes: active contour models, International Journal of Computer Vision 1 (1988) 321; V. Caselles, R. Kimmel, G. Sapiro, Geodesic active contours, International Journal of Computer Vision 22 (1997) 61; G. Sapiro, Geometric Partial Differential Equations and Image Analysis, Cambridge University Press, 2001; R. Kimmel, Numerical Geometry of Images: Theory, Algorithms, and Applications, Springer-Verlag, 2003] introduced in the field of image processing.

Yokoi, Kensuke

2009-07-01

473

ILR-Based MT Comprehension Test with Multi-Level Questions.  

National Technical Information Service (NTIS)

We present results from a new Interagency Language Roundtable (ILR) based comprehension test. This new test design presents questions at multiple ILR difficulty levels within each document. We incorporated Arabic machine translation (MT) output from three...

A. Jairam D. Jones H. Ibrahim M. Herzog W. Shen

2007-01-01

474

Sensory evaluation of the odors produced during bromophenol formation using a multi-level statistical model.  

PubMed

In response to reports of medicinal taste and odor problems in suburban Paris, a lab scale study was conducted to investigate the contribution of different water quality parameters--pH, phenol, bromide, chlorine, temperature and dissolved oxygen levels--on bromophenol medicinal odor formation using the Flavor Profile Analysis (FPA) method. A study of six parameters at 2 levels (64 experiments) analyzed by the FPA method suggests that chlorine at high concentration is more important as a controlling agent than phenol under similar conditions and the ratio of HOBr:Phenol and the time for reaction will control subsequent brominated products of reaction. Results from a three-level statistical model indicate that high pH was associated with lower odor intensities, whereas high levels of chlorine, phenol and temperature were associated with high odor intensities. Potential worst case scenarios of water quality conditions were determined for evaluation by chemical identification and kinetics. PMID:15237631

Al-Samarrai, H; Matud, J; Wiesenthal, K; Atiyah, P; Bruchet, A; Suffet, I H

2004-01-01

475

A MultiLevel Approach to Investigating Neighborhood Effects on Physical Aggression among Urban Chicago Youth  

Microsoft Academic Search

The current study evaluates neighborhood effects, individual-level effects, and demographic characteristics that influence\\u000a physically aggressive behavior among urban youth. Using data derived from 5,812 adolescents from Project Northland Chicago\\u000a (PNC) and Heirarchical Linear Modeling (HLM) techniques, the results suggested that neighborhood problems significantly predicted\\u000a physical aggression, before and after adjustment for individual-level risk factors (alcohol use, peer alcohol use, lack

Wesley G. Jennings; Mildred M. Maldonado-Molina; Jennifer M. Reingle; Kelli A. Komro

476

Mapping a MultiLevel Scheduling Pattern Language to Distributed Real-Time Embedded Applications1  

Microsoft Academic Search

Mission-critical Distributed Real-Time and Embedded (DRE) systems pose significant resource management challenges at and across all architectural levels, i.e., the operating system and low-level middleware on each endsystem, and distributed services spanning multiple endsystems. Furthermore, the challenges posed by one application may differ from the challenges posed by another. As developers of complex DRE applications move increasingly from building individual

Christopher Gill; Douglas Niehaus; Lisa DiPippo; Victor Fay Wolfe; Lonnie Welch

477

Multi-level, cross-sectional study of workplace social capital and smoking among Japanese employees  

PubMed Central

Background Social capital is hypothesized to be relevant to health promotion, and the association between community social capital and cigarette smoking has been examined. Individual-level social capital has been found to be associated with smoking cessation, but evidence remains sparse on the contextual effect of social capital and smoking. Further, evidence remains sparse on the association between smoking and social capital in the workplace, where people are spending an increasing portion of their daily lives. We examined the association between workplace social capital and smoking status among Japanese private sector employees. Methods We employed a two-stage stratified random sampling procedure. Of the total of 1,800 subjects in 60 companies, 1,171 (men/women; 834/337) employees (65.1%) were identified from 46 companies in Okayama in 2007. Workplace social capital was assessed in two dimensions; trust and reciprocity. Company-level social capital was based on inquiring about employee perceptions of trust and reciprocity among co-workers, and then aggregating their responses in order to calculate the proportion of workers reporting mistrust and lack of reciprocity. Multilevel logistic regression analysis was conducted using Markov Chain Monte Carlo methods to explore whether individual- and company-level social capital was associated with smoking. Odds ratios (ORs) and 95% credible intervals (CIs) for current smoking were obtained. Results Overall, 33.3% of the subjects smoked currently. There was no relationship between individual-level mistrust of others and smoking status. By contrast, one-standard deviation change in company-level mistrust was associated with higher odds of smoking (OR: 1.25, 95% CI: 1.06-1.46) even after controlling for individual-level mistrust, sex, age, occupation, educational attainment, alcohol use, physical activity, body mass index, and chronic diseases. No clear associations were found between lack of reciprocity and smoking both at the individual- and company-level. Conclusions Company-level mistrust is associated with higher likelihood of smoking among Japanese employees, while individual perceptions of mistrust were not associated. The link between lack of reciprocity and smoking was not supported either at the individual- or company-level. Further studies are warranted to examine the possible link between company-level trust and smoking cessation in the Japanese workplace.

2010-01-01

478

A Prospective, Randomized Trial Comparing Expansile Cervical Laminoplasty versus Cervical Laminectomy and Fusion for Multi-level Cervical Myelopathy.  

PubMed

BACKGROUND:: Controversy exists as to the best posterior operative procedure to treat multi-level compressive cervical spondylotic myelopathy. OBJECTIVE:: To determine clinical, radiological and patient satisfaction outcomes between these two surgical procedures. METHODS:: We performed a prospective, randomized study of Expansile Cervical Laminoplasty (ECL) vs. Cervical Laminectomy and Fusion (CLF) in patients suffering from cervical spondylotic myelopathy. End-points included the SF-36, the NDI, VAS, modified JOA score, Nurick score and radiographic measures. RESULTS:: A survey of academic North American spine surgeons (n=30) demonstrated that CLF is the most commonly used (70%) posterior procedure to treat multi-level spondylotic cervical myelopathy. A total of 16 patients were randomized: CLF (n=7) / ECL (n=9). Both groups showed improvements in their Nurick grade and JOA score postoperatively, but only the improvement in the Nurick grade for the ECL group was statistically significant (p<0.05). The cervical ROM between C2 and C7 was reduced by 75% in the CLF group and by only 20% in the ECL group when comparing pre- and post-op range of motion. The overall increase in canal area was significantly (p<0.001) greater in the CLF, but there was a suggestion that the adjacent level was more narrowed in the CLF group in as little as 1 year post-operative. CONCLUSION:: ECL compares favorably in many respects to CLF. While patient numbers are small, there were significant improvements in pain measures in the ECL group while still maintaining range of motion. Restoration of spinal canal area was superior in the CLF group. PMID:21817931

Manzano, Glen R; Casella, Gizelda; Wang, Michael Y; D O D C, Steven Vanni; Levi, Allan D

2011-08-02

479

The Use of Biosimulation in the Design of a Novel Multi-level Weight Loss Maintenance Program for Overweight Children  

PubMed Central

Objective Weight loss outcomes achieved through conventional behavior change interventions are prone to deterioration over time. Basic learning laboratory studies in the area of behavioral extinction and renewal and multi-level models of weight control offer clues as to why newly acquired weight loss skills are prone to relapse. According to these models, current clinic-based interventions may not be of sufficient duration or scope to allow for the practice of new skills across the multiple community contexts necessary to promote sustainable weight loss. Although longer, more intensive interventions with greater reach may hold the key to improving weight loss outcomes, it is difficult to test these assumptions in a time efficient and cost-effective manner. A research design tool that has been increasingly utilized in other fields (e.g., pharmaceuticals) is the use of biosimulation analyses. The present paper describes our research team's use of computer simulation models to assist in designing a study to test a novel, comprehensive socio-environmental treatment approach to weight loss maintenance in children ages 7 to 12 years. Methods Weight outcome data from the weight loss, weight maintenance, and follow-up phases of a recently completed randomized controlled trial (RCT) were used to describe the time course of a proposed, extended multi-level treatment program. Simulations were then conducted to project the expected changes in child percent overweight trajectories in the proposed study. Results A 12.9% decrease in percent overweight at 30 months was estimated based upon the midway point between models of “best-case” and “worst-case” weight maintenance scenarios. Conclusions Preliminary data and further analyses, including biosimulation projections, suggest that our socio-environmental approach to weight loss maintenance treatment is promising and warrants evaluation in a large-scale RCT. Biosimulation techniques may have utility in the design of future community-level interventions for the treatment and prevention of childhood overweight.

Wilfley, Denise E.; Van Buren, Dorothy J.; Theim, Kelly R.; Stein, Richard I.; Saelens, Brian E.; Ezzet, Farkad; Russian, Angela C.; Perri, Michael G.; Epstein, Leonard H.

2011-01-01

480

Inverted indexes for phrases and strings  

Microsoft Academic Search

Inverted indexes are the most fundamental and widely used data structures in information retrieval. For each unique word occurring in a document collection, the inverted index stores a list of the documents in which this word occurs. Compression techniques are often applied to further reduce the space requirement of these lists. However, the index has a shortcoming, in that only

Manish Patil; Sharma V. Thankachan; Rahul Shah; Wing-Kai Hon; Jeffrey Scott Vitter; Sabrina Chandrasekaran

2011-01-01

481

Pulse width modulation inverter with battery charger  

Microsoft Academic Search

An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the

Slicker; James M

1985-01-01

482

Pulse width modulation inverter with battery charger  

Microsoft Academic Search

An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin [theta], where [theta] is the

Slicker

1985-01-01

483

An SCR inverter for electric vehicles  

Microsoft Academic Search

An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated

T. Latos; D. Bosack; R. Ehrlich; T. Jahns; J. Mezera; D. Thimmesch

1980-01-01

484

Encryption Scheme Based on Invertible Watermarking  

Microsoft Academic Search

This paper proposes a novel encryption scheme based on invertible watermarking. In the past encryption algorithms, diffusion and confusion algorithms are used to increase the effect of the encryption, however, these algorithms can only change the cover itself to be encrypted. In this paper, the invertible watermarking can be used to perform the encryption, which can not only use the

Jinwei Wang; Yufeng Shi; Shiguo Lian

2010-01-01

485

On the periodically driven inverted pendulum  

Microsoft Academic Search

We study the solution properties of a family of inverted pendulum systems driven by odd periodic forcing. Using the Schauder fixed point theorem, we show that the inverted pendulum with an odd periodic driving acceleration at the pivot always possesses an odd periodic solution. Fundamental to the production of good estimates is the development of a Green's function for an

Robert Bailey; John Hauser

2009-01-01

486

Generalized Structure of a Multilevel PWM Inverter  

Microsoft Academic Search

A generalized structure of a multilevel voltage source thyristor inverter is proposed. The multilevel concept is used to decrease the harmonic distortion in the output waveform without decreasing the inverter power output. A simple uniform PWM control of the output voltage is seen to be sufficient to practically remove all remaining harmonics. Harmonic analysis of n-step waveform is given, and

Pradeep M. Bhagwat; V. R. Stefanovic

1983-01-01

487

Inverted File Compression through Document Identifier Reassignment.  

ERIC Educational Resources Information Center

|Discusses the use of inverted files in information retrieval systems and proposes a document identifier reassignment method to reduce the average gap values in an inverted file. Highlights include the d-gap technique; document similarity; heuristic algorithms; file compression; and performance evaluation from a simulation environment. (LRW)|

Shieh, Wann-Yun; Chen, Tien-Fu; S