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1

Grid interconnection for variable-speed wind farm with multi-level inverter  

Microsoft Academic Search

This paper presents design, modeling, and control of grid interconnection for a wind farm with round-rotor synchronous generators. The grid interconnection proposed in this paper supports the variable-speed wind turbine concept with the three-phase diode bridge as a front-end rectifier. The wind energy resources and the utility grid are isolated by intermediate fly-back converters. The grid interface multi-level inverter with

Siriya Skolthanarat; Virgilio Centeno

2008-01-01

2

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

3

Multi-carrier interleaved PWM strategies for a new five-level NPC inverter using a 3-phase coupled inductor  

Microsoft Academic Search

Multi-carrier interleaved PWM techniques are presented for a new five-level Neutral Point Clamped (NPC) inverter using a 3-phase coupled inductor. The operation of the proposed topology relies on the dual requirements of balancing the DC bus capacitor voltages and the inductor common mode currents together. The inverter performance is dependent on the PWM strategies minimizing the inductor current ripple and

Behzad Vafakhah; Jeffrey Ewanchuk; John Salmon

2010-01-01

4

Analysis and comparison of multicarrier PWM schemes applied in H-bridge cascaded multi-level inverters  

Microsoft Academic Search

Four kinds of compound carrier disposition PWM schemes are discussed, two of which are proposed for the first time in the paper. Methods for analyzing the amplitudes and harmonics of the output voltage of single-phase multi-level cascaded inverter are introduced for these PWM schemes, whose carrier waves could be equivalent to the ones of phase-shifted-PWM. Features of these PWM schemes

Tengfei Wang; Yongqiang Zhu

2010-01-01

5

High efficiency Single-Inductor Boost\\/Buck Inverting Flyback converter with hybrid energy transfer media and multi level gate driving for AM OLED panel  

Microsoft Academic Search

A hybrid-type Single Inductor Boost\\/Buck Inverting Flyback(SIBBIF) DC-DC Converter is presented. To increase the converter efficiency, a flying capacitor as well as an inductor is adopted as another energy transfer medium together with multi-level gate driver (MLGD). Besides, to enhance load transient response, hybrid fast transient control (HFTC) is adopted. The proposed chip is implemented in a 0.5-?m power BCD

Se-Won Wang; Young-Jin Woo; Young-Sub Yuk; Gyu-Hyeong Cho; Gyu-Ha Cho

2010-01-01

6

Improved Design of Three-Level NPC Inverters in Comparison to Two-Level Inverters  

Microsoft Academic Search

As voltage source 3-level NPC inverters are suitable for AC drives in average voltage and FACT applications in distribution systems, this report introduces optimized design of 3-level NPC inverter by decreasing inverter losses and costs. At first optimization parameters and application functions of losses are introduced(1), then by using MATLAM6.5 program and IGBT, diodes, switching frequency and load current typical

AHMAD RADAN; HENGAMEH KOJOOYAN JAFARI

7

Modeling and Control of a Power Electronic Cascade for the Multi DC Bus Supply of a Seven-Level NPC Voltage Source Inverter  

Microsoft Academic Search

The stability problem of the input DC voltages in a seven-level Neutral Point Clamping (NPC) Voltage Source Inverter (VSI) is recalled and illustrated. A first solution involving six controlled-voltage (CV) rectifiers is presented. A knowledge model of this converter using switching functions and a PWM strategy is detailed. For an economic point of view, a second power structure is proposed.

Abdelaziz Talhal; El Madjid Berkouk; Bruno Francois; Mohamed Seghir Boucherit

2006-01-01

8

Development of multi step current source inverter.  

National Technical Information Service (NTIS)

Static power converter apparatus have 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...

Y. Chul-Ro

1994-01-01

9

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

10

Multi-inverter UPS system with redundant load sharing control  

Microsoft Academic Search

The concept of a redundant multi-inverter UPS (uninterruptible power supply) system which includes extended monitoring of the status and the operating conditions of all power electronic equipment is described. Each block of the UPS system is monitored by two independent microcomputers that process the same data. The microcomputers are part of a redundant distributed monitoring system that is separately interlinked

J. Holtz; K.-H. Werner

1990-01-01

11

Generalized hysteresis current controller for three-level inverter topologies  

Microsoft Academic Search

This paper analyzes the generalized hysteresis current control algorithm for three level inverter topologies. The inverter topologies considered are H-bridge, diode clamped and capacitor clamped three level inverters. It is shown that the switching frequency for the proposed hysteresis algorithm can be estimated using an empirical relation. The algorithm can be directly implemented for the H-bridge and diode clamped three-level

Shweta Gautam; Rajesh Gupta

2012-01-01

12

Fault tolerant SVM strategy for 3-level NPC inverter  

Microsoft Academic Search

Assuring continuity operating of induction machine drives is crucial in the most of applications. Thanks to the number of their output voltages, and the extra degrees of freedom they offer, multilevel inverters have been adopted in many applications. In this paper, a new fault tolerant SVM strategy for induction machine drives based on a 3level NPC inverter is proposed. It

H. Ben Abdelghani; A. Bennani Ben Abdelghani

2011-01-01

13

A nine-switch three-level inverter for electric vehicle applications  

Microsoft Academic Search

This paper presents a nine-switch three-level inverter used as an application for all-electric vehicle (EV) and hybrid-electric vehicle (HEV) motor drives. The proposed three-level inverter consists of a three-phase two-level inverter and three bidirectional power switches. The proposed inverter overcomes some shortcomings of two-level inverters, such as high switching frequency, high dv\\/dt and electromagnetic interference (EMI). The proposed inverter also

Mingyan Wang; Kai Tian

2008-01-01

14

Three-level inverter based shunt active power filter using generalized hysteresis current control method  

Microsoft Academic Search

This paper proposes a generalized hysteresis current controlled three level voltage source inverter (VSI) based single phase shunt active power filter (SAPF). The three level inverter topologies considered in this paper are H-bridge and diode clamped inverters. A generalized hysteresis current control with multiband hysteresis modulation has been used to control the voltage source inverters in the shunt active power

Shweta Gautam; Rajesh Gupta

2010-01-01

15

SVM algorithm of three-level NPC inverter  

Microsoft Academic Search

On the basis of presenting the principles of space vector modulation (svm) of three-level neutral point clamped (NPC) inverter, an approach to implementation of SVM is proposed. The dwell times of vectors are calculated according to the volt-second balancing. A triangle is adopted to compare with three switching points. The three switching points are determined by the dwell times. According

Shanmei Cheng; Yajun Liu; Bing Wu

2008-01-01

16

A Multi-Output Series Resonant Inverter with Asymmetrical Voltage-Cancellation Control for Induction-Heating Cooking Appliances  

Microsoft Academic Search

This paper presents and analyzes the asymmetrical voltage-cancellation (AVC) control, for a multi-output series resonant inverter. It is applied to the multiple-burner induction-heating cooking appliances. Some common approaches use several single-output inverters or a single-output inverter multiplexing the loads along the time periodically. By specifying a multi-output series-resonant high frequency inverter, a new inverter is obtained fulfilling the requirements. The

S. H. Hosseini; A. Y. Goharrizi; E. Karimi

2006-01-01

17

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

18

A Space Vector PWM Scheme for Multilevel Inverters Based on Two-Level Space Vector PWM  

Microsoft Academic Search

Multilevel inverters are increasingly being used in high-power medium voltage applications due to their superior performance compared to two-level inverters. Among various modulation techniques for a multilevel inverter, the space vector pulsewidth modulation (SVPWM) is widely used. However, the implementation of the SVPWM for a multilevel inverter is complicated. The complexity is due to the difficulty in determining the location

Amit Kumar Gupta; Ashwin M. Khambadkone

2006-01-01

19

A new simplified space-vector PWM method for three-level inverters  

Microsoft Academic Search

In this paper, a new simplified space-vector pulse width modulation (SVPWM) method for a three-level inverter is proposed. This method is based on the simplification of the space-vector diagram of a three-level inverter into that of a two-level inverter. If simplified by the proposed method, all the remaining procedures necessary for the three-level SVPWM are done like conventional two-level inverter

Jae Hyeong Seo; Chang Ho Choi; Dong Seok Hyun

2001-01-01

20

The analysis and comparison of carrier-based PWM methods for 3-level inverter  

Microsoft Academic Search

This paper provides the analysis and comparison of carrier-based PWM methods for 3-level inverter. Up to now, there were few papers dealing with harmonic characteristics of various modulation indexes in the 3-level inverter. Therefore, the PWM methods for the 3-level inverter need be analyzed and compared. The current harmonics of a 3-level inverter is compared with those of conventional 2-level

Dong-Hyun Kim; Dae-Wook Kang; Yo-Han Lee; Dong-Seok Hyun

2000-01-01

21

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

22

Modular design of soft-switching circuits for two-level and three-level inverters  

Microsoft Academic Search

This paper presents a negative-bus auxiliary resonant circuit (NBARC) and novel mirror symmetrical pair of resonant link modules for soft commutation of two-level and three-level inverters. The NBARC topology reduces the power device counts and requires low device power ratings. While the basic NBARC resonant circuit is conceived and analyzed for zero-voltage switching (ZVS) of two-level inverters, the topology and

Jie Chang; Jun Hu

2006-01-01

23

Trinary Hybrid 81Level Multilevel Inverter for Motor Drive With Zero Common-Mode Voltage  

Microsoft Academic Search

This paper proposes a trinary hybrid 81-level multilevel inverter for motor drive. Benefiting from the trinary hybrid topology of the inverter, 81-level voltages per phase can be synthesized with the fewest components. Bidirectional DC-DC converters are used not only to inject power to the DC links of the inverter but also to absorb power from some DC links in cases

Yu Liu; Fang Lin Luo

2008-01-01

24

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

25

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

26

The study and realization of three-level SVPWM algorithm for high power inverter  

Microsoft Academic Search

A novel simplified space-vector pulse width modulation (SVPWM) algorithm for high power three-level inverter is analyzed in this paper. The space-vector module algorithm of two-level inverter is applied to that of three-level inverter using DSP and FPGA. A 22Kw and a 1000kW three phase asynchronous motor are taken as experimental subject in lab and field respectively. The experiment results show

Yaofei Han; Xiaohong Fan; Zhangfei Zhao

2011-01-01

27

Research on neutral-point potential balancing for three-level NPC voltage source inverter  

Microsoft Academic Search

A significant problem with neutral-point-clamped three-level inverters is the fluctuation in the neutral-point voltage. When three-level inverter is loaded, the neutral-point voltage leads to the distortion on output voltage space-vector waveform of the inverter. A novel and simple judge rule based on the virtual space-vector is introduced. The mathematics models of neutral-point circuit and neutral-point potential are developed while the

Cungang Hu; Qunjing Wang; Guoli Li

2008-01-01

28

Connecting two wind turbine generators to the grid using only one three level NPC inverter  

Microsoft Academic Search

This paper explores the possibility of connecting two Wind Turbine Generators (WTG) to the grid using a single three level inverter. In the proposed system the rectified output of one WTG is connected across the upper dc-link capacitor of a standard diode clamped three level inverter. Similarly the rectified output of the other WTG is connected across the lower capacitor.

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

2010-01-01

29

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

30

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

31

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

32

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

33

Square wave control of 3-level NPC inverter for large capacity high-speed drive systems  

Microsoft Academic Search

This paper presents an improved method to achieve the high control performance of 3-level inverter for large capacity high-speed drive systems. Usually, due to the limit switching frequency of high voltage high power devices, the output frequency of the inverter is low in most cases. To achieve higher output frequency, the square wave modulation (SWM) is adopted. However, the use

Haishan Li; Yaohua Li

2005-01-01

34

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

National Technical Information Service (NTIS)

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 ...

J. N. Chiasson

2006-01-01

35

Dead-time effects in voltage source inverter fed multi-phase AC motor drives and their compensation  

Microsoft Academic Search

Inverter dead-time effects have been investigated in detail in the past for three-phase drives supplied from a three-phase voltage source inverter (VSI). A similar study has never been conducted in conjunction with multi-phase (more than three phases) drives, supplied from multi-phase VSIs. Regardless of the type of ac machine and its number of phases, the power supply of the drive

M. Jones; D. Dujic; E. Levi; S. N. Vukosavic

2009-01-01

36

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

37

Large capacity high performance 3-level GTO inverter system for steel main rolling mill drives  

Microsoft Academic Search

This paper proposes a high performance 10 MVA 3-level GTO inverter system for steel main rolling mill drives, which consists of a three-level power converter, a three-level inverter and two series-connected DC-link capacitors with a neutral point. To realize this system, newly developed 6-inch 6 kV-6 kA GTOs have been applied first in the world. A novel regenerative snubber circuit

Hideo Okayama; Ryohei Uchida; Masato Koyama; S. Mizoguchi; Shinzo Tamai; H. Ogawa; T. Fujii; Yasuhito Shimomura

1996-01-01

38

Parametric Design of Five-Level Active NPC Inverter  

NASA Astrophysics Data System (ADS)

This paper describes the loss analysis and capacitor designing method for an active neutral-point-clamped (ANPC) multilevel inverter. The ANPC circuit topology is a combination of a neutral-point-clamp circuit and flying capacitor circuit topologies. This circuit requires lesser number of components than conventional multilevel converters. Loss analysis is performed using mathematical expressions. The analysis results of the losses agreed with the experimental results.

Kashihara, Yugo; Itoh, Jun-Ichi

39

Simulation of five-level five-phase SVPWM voltage source inverter  

Microsoft Academic Search

Multilevel voltage-fed inverters with space vector pulse width modulation strategy are gained importance in high power high performance industrial drive applications. Multi-phase machines and drives is a topic of growing relevance in recent years, and it presents many challenging issues that still need further research. Multilevel multiphase technology combines the benefits of both technologies. This paper proposes a new simplified

M. M. Irfan; P. H. K. Prasad; P. Venugopal Rao

2010-01-01

40

Three-level NPC inverter with IGCT for high power AC drives  

Microsoft Academic Search

This paper present a high power three-level NPC inverter with the Integrated Gate-Commutated Thyristor (IGCT) devices. The power circuit consisted of a 12-pulse diodes rectifier and three-level NPC inverter with IGCT. A valid SVPWM control strategy filled with a TMS320F2407 DSP controller is proposed to improve power quality, reduce total harmonic distortion and overcome the problem of the minimum pulse

Shutian Zhang; Qiongxuan Ge; Yaohua Li

2008-01-01

41

A General Space Vector PWM Algorithm for a Multilevel Inverter Including Operation in Overmodulation Range, with a Detailed Modulation Analysis for a 3-level NPC Inverter  

Microsoft Academic Search

This paper proposes a simple space vector PWM algorithm for a multilevel inverter, which (a) can cover sinusoidal and overmodulation mode (b) can easily determine the location of reference vector and calculate the on-times. The proposed scheme is explained for a 3-level neutral point clamped inverter with operation in sinusoidal and overmodulation modes. The scheme can be easily extended to

A. K. Gupta; A. M. Khambadkone

2005-01-01

42

The circuit-level decoupling modulation strategy for three-level neutral-point-clamped (TL-NPC) inverter  

Microsoft Academic Search

In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes the controller design much simpler. The decoupling principle including the driving signal synthesis and the neutral point potential variation are

Zhe Zhang; Ole C. Thomsen; Michael A. E. Andersen

2011-01-01

43

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

44

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

45

A new control strategy to balance neutral-point voltage in three-level NPC inverter  

Microsoft Academic Search

The three-level neutral-point-clamped (NPC) inverter has attracted significant interest for high power\\/voltage applications, due to its significant advantages. A drawback of NPC inverter is that it is prone to voltage drifts and low-frequency voltage ripples of the neutral-point. In this paper, a novel control strategy of neutral-point balancing under SVPWM-based switching strategy is proposed which can be generally applied for

Xinchun Lin; Shan Gao; Jinda Li; He Lei; Yong Kang

2011-01-01

46

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

47

Design and control of a grid-connected three-phase 3-level NPC inverter for Building Integrated Photovoltaic systems  

Microsoft Academic Search

This paper presents the design and control of a grid-connected three-phase 3-level Neutral Point Clamped (NPC) inverter for Building Integrated Photovoltaic (BIPV) systems. The system consists of a PV array, boost DC\\/DC converter, 3-level NPC inverter, LC filter and the grid. The 3-level NPC inverter is designed without a galvanic isolation transformer and its current controller is developed to minimize

Youngroc Kim; Hanju Cha; Byeong-Mun Song; Kwang Y. Lee

2012-01-01

48

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

49

DSP based space vector PWM for three-level inverter with DC-link voltage balancing  

Microsoft Academic Search

The authors describe a novel PWM (pulse width modulation) method for a three-level inverter considering the DC link capacitor balancing problem. Each voltage vector on the space vector plane is classified in relation to the charging\\/discharging action of DC capacitors, and a novel modulation method is suggested based on the voltage vector selection principle. The algorithm was implemented on the

Hyo L. Liu; Nam S. Choi; Gyu H. Cho

1991-01-01

50

Dynamic analysis of hybrid wind\\/diesel system with three-level inverter  

Microsoft Academic Search

Hybrid systems combining wind energy conversion systems and diesel generators are considered one of the alternatives to feed demands at lower energy cost and acceptable reliability. Due to different sources of fluctuating electrical power, the power delivered to the load contains different orders of harmonics. A three-level inverter is designed to suppress the fifth-harmonic of the phase voltage. The operation

Fadia M. A. Ghali; Shawki H. Arafah

2002-01-01

51

A three level NPC inverter with neutral point voltage balancing for induction motors Direct Torque Control  

Microsoft Academic Search

In this paper, we present a new Direct Torque Control (DTC) scheme for induction motors using a three-level neutral point clamped (NPC) voltage source inverter (VSI). In order to develop high dynamic performances, we propose a new approach, in which we enhance the responses of the torque and the flux with optimal switching strategies. Serious problems caused by significant fluctuations

Hamza Alloui; Abderrahmane Berkani; Hacene Rezine

2010-01-01

52

Traction system for an EV based on induction motor and 3-level NPC inverter multilevel converters  

Microsoft Academic Search

This work presents the modeling of the dynamics of an electric vehicle (EV). Then, by using a typical driving cycle, the parameters for the motor drive system and other drive train components are determined. The proposed drive system is based on an induction motor being supplied by a 3-level NPC inverter. The speed control is based on a constant V\\/Hz

M. A. Gonza?lez; M. F. Escalante

2010-01-01

53

A simplified space -vector PWM for three level inverters applied to passive and motor load  

Microsoft Academic Search

Advances in power electronics technology allowed the wide investigation of multilevel converters that provide high safety voltages with less harmonic components compared to the two-level structures .Because of prominent advantages like more utilization of input voltage, flexibility in switching the legs of three phase inverters and easy method of improving spectral performance and easy digital implantation, space vector modulation (SVPWM)

P. M. Meshram; Dipesh Hanote; M. M. Renge

2009-01-01

54

PWM inverter technology  

NASA Astrophysics Data System (ADS)

The use of pulse-width-modulated (PWM) inverter technology by on-line uninterruptible power supplies (UPSs) of 250 VA-750 kVA rating improves transient performance, lowers harmonic distortion, and enhances nonlinear load performance. An account is presently given of the means employed for optimization of a PWM inverter used in a multi-kHz UPS. By using computer modeling to optimize the feedback control loop, the best level of response was furnished, while minimizing switching losses and achieving the highest level of efficiency.

Perra, Andre

1992-04-01

55

Virtual-Flux Direct Power Control for Mains Connected Three-Level NPC Inverter Systems  

Microsoft Academic Search

This paper proposes a control strategy which extends the virtual-flux direct power control traditionally employed for the conventional two-level VSI to a three-level NPC inverter. This topology generates a higher number of output voltage levels, increasing the flexibility for selecting an appropriate voltage vector. The mid-point potential is controlled according to the direction of the mid-point current and the sign

L. A. Serpa; J. W. Kolar

2007-01-01

56

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

57

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

Microsoft Academic Search

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

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

2009-01-01

58

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

Microsoft Academic Search

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

Zhang Yingchao; Zhao Zhengming; Lu Ting; Jin Liping

2010-01-01

59

An novel deadbeat control method for cctive power filters with three-level NPC inverter  

Microsoft Academic Search

Three-level NPC inverter has been put into practical use for years especially in high voltage high power grid. This paper researches three-level active power filters(APF). In this paper the mathematical model in d-q coordinates is presented for 3-phase 3-wire APFs. The dead-beat control scheme is obtained by using the state equations. Canceling the delay of one sampling period and providing

Yingjie He; Jinjun Liu; Jian Tang; Zhaoan Wang; Yunping Zou

2008-01-01

60

Low-Frequency Sea Level Variability and the Inverted Barometer Effect  

Microsoft Academic Search

For a dynamical interpretation of sea level records, estimates are needed of the isostatic, or so-called inverted barometer, signals (ib) associated with the ocean response to atmospheric loading. Seasonal and longer-period ib signals are evaluated over the global ocean for the period 1958-2000 using monthly sea level pressure fields from two different atmospheric reanalyses. Variability and linear trends in ib

Rui M. Ponte

2006-01-01

61

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

2013-03-01

62

A fast algorithm for three-level SVPWM in NPC inverters based on traditional three-level SPWM  

Microsoft Academic Search

A fast algorithm for three-level space vector pulse wide modulation (SVPWM) in neutral point clamped (NPC) inverters based on traditional three-level sinusoidal pulse wide modulation (SPWM) is proposed. The acting time relation of each state in each phase is got by deeply researching the similarities and differences of three-level SPWM and SVPWM. This algorithm can realize all kinds of state

Li Ning; Wang Yue; Jiang Yingwei; Wang Zhaoan

2010-01-01

63

Overmodulation strategy of NPC type 3-level inverter for traction drives  

Microsoft Academic Search

This paper proposes an overmodulation method for improving the voltage utilization of NPC type 3-level inverter for traction drives. The conventional railway vehicle has used a vector control to MI=0.907 and a slip-frequency control from MI=0.907 to the six-step mode. The slip-frequency control has less output torque dynamics than the vector control. In this paper, the linear region of NPC

Jaemoon Lee; Jaeho Choi; Yasuyuki Nishida

2007-01-01

64

DC-DC converter connected to three-level NPC inverter for renewable energy sources application  

Microsoft Academic Search

This work presents a simulation analysis of several DC-DC converters applied to a three-level three-phase NPC inverter, while driving an induction motor with a load torque proportional to the square of the speed. The purpose is to identify practical solutions which can suit rural applications fed by renewable sources. Two topologies are proposed. The analysis is carried out through PSCAD\\/EMTDCtrade

Felipe J. C. Padilha; Walter I. Suemitsu; Maria D. Bellar

2008-01-01

65

Modeling and simulation of a STATCOM system based on 3-level NPC inverter using dynamic phasors  

Microsoft Academic Search

This work presents a study on the modeling of a STATCOM (static synchronous compensator), which is based on a 3-level neutral point clamped (NPC) inverter. This STATCOM is connected to a scale-down power system in order to verify its validity. Furthermore, a novel modeling method-dynamic phasors modeling method is introduced and applied to this scale-down power system. This approach is

Qingru Qi; Chang Yu; Chan Ka Wai; Yixin Ni

2004-01-01

66

Harmonic modeling of single-phase three-level hysteresis inverters  

Microsoft Academic Search

The paper derives a closed-form analytical approximation of the output current harmonic spectrum for the three-level single-phase inverters under the action of hysteresis current control. The error current harmonic spectrum is directly calculated from the system and controller parameters. The analytical approach consists of deriving the instantaneous frequency of the error current and then approximating the error current by a

Ahmad Albanna; C. J. Hatziadoniu

2009-01-01

67

Novel Switching Sequences for a Space-Vector-Modulated Three-Level Inverter  

Microsoft Academic Search

A three-level inverter produces six active vectors, each of normalized magnitudes 1, 0.866, and 0.5, besides a zero vector. The vectors of relative length 0.5 are termed pivot vectors. The three nearest voltage vectors are usually used to synthesize the reference vector. In most continuous pulsewidth-modulation (PWM) schemes, the switching sequence begins from a pivot vector and ends with the

Soumitra Das; G. Narayanan

2012-01-01

68

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

69

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

70

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

Microsoft Academic Search

The interest here is in using a single DC power source to construct a 3-phase 5-level cascade multilevel inverter to be used as a drive for a PM traction motor. The 5-level inverter consists of a standard 3-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg, which use a capacitor as a DC

John N. Chiasson; Burak Ozpineci; Leon M. Tolbert

2007-01-01

71

Physical timing models of small-geometry CMOS inverters and multi-input NAND/NOR gates and their applications  

NASA Astrophysics Data System (ADS)

Physical timing models for small-geometry CMOS inverters and multi-input NAND/NOR gates have been developed. In the model formulation, the rise/fall time interval of the gate output voltage is divided into two regions according to the operating region of each MOSFET. The complete large-signal equivalent circuit is then constructed and linearized. By using the Modified-Dominant-Pole-Dominant-Zero method, the effective dominant pole in each region is found and the waveform function of the output voltage is approximated by a single-pole response. Finally, rise/fall times and delay times are formulated. As compared with SPICE simulation and experimental results, the maximum error of the developed timing models is 15% for CMOS inverters and multi-input NAND/NOR gates with different channel dimensions, capacitive loads, device parameters and input excitations. Application examples have been presented to demonstrate the efficiency of the developed timing models in timing verification and logic hazard detection. Moreover, based upon the time models, it is seen that a quasi-constant-voltage scaling law has an optimal figure of merit combining speed, area and reliability. In addition, the optimal width ratio of small-geometry CMOS inverters depends on the ratio of effective channel modulation factors rather than the mobility ratio. Reasonable accuracy, less CPU time and memory requirement, and wide applicable ranges make the developed timing models quite feasible in many applications.

Chung-Yu Wu; Jen-Sheng Hwang

1989-06-01

72

Multi-purpose grid-tied inverter with smart grid capabilities  

NASA Astrophysics Data System (ADS)

Distributed energy storages play an important role in increasing the reliability and efficiency of the grid through means of peak load shaving, grid voltage support, and grid frequency support. It is important to have distributed energy storages that can utilize the functionalities of the modern smart grid to operate more effectively. The grid-tied inverter is one of the major components in a distributed energy storage that controls the power transfer between the grid and an energy storage device. In this research, a grid-tied inverter that can be used in distributed energy storage applications was designed, developed, and tested. This grid-tied inverter was designed with the capability to control both reactive and active power flow in either direction. The grid-tied inverter is equipped with communication capabilities so it can be remotely controlled by commands sent through a smart grid network. For demonstrative purposes, a user interface was developed to control and monitor the operation of the grid-tied inverter. Finally the operation of the grid-tied inverter was evaluated in accordance to IEEE 1547, the Standard for Interconnecting Distributed Resources with Electric Power Systems.

Liyanagedera, Chamika Mihiranga

73

Direct torque control of induction motor: Simulation results using two-level and diode clamped multilevel inverter  

Microsoft Academic Search

Development in multilevel converters has provided better option as power converter for high-power applications. These converters synthesize the output voltage waveform from several steps of dc input source which approaches to sinusoidal waveform and minimizes the harmonic distortions. This paper presents the application of two-level inverter and diode clamped multilevel inverter for direct torque control of 3-phase induction motor drive.

U. V. Patil; H. M. Suryawanshi; M. M. Renge

2010-01-01

74

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

75

Analysis, Simulation and DSP Based Implementation of Asymmetric Three-Level Single-Phase Inverter in Solar Power System  

Microsoft Academic Search

Switching-mode single-phase DC-AC inverters have been widely used in many applications such as AC motor drivers and uninterrupted power supply systems. Among various control techniques, pulse-width-modulation (PWM) is the most effective one generally used to regulate the magnitude as well as frequency of the converter’s output voltage. In this thesis, an open-loop asymmetric three-level inverter with a modified PWM approach

Yi Tian

2007-01-01

76

A Simple Space Vector PWM Scheme to Operate a Three-Level NPC Inverter at High Modulation Index Including Overmodulation Region, With Neutral Point Balancing  

Microsoft Academic Search

Three-level neutral point clamped (NPC) inverter is a widely used topology of multilevel inverters. However, the neutral point fluctuates for certain switching states. At low modulation index, the fluctuations can be compensated using redundant switching states. But, at higher modulation index and in overmodulation region, the neutral point fluctuation deteriorates the performance of the inverter. This paper proposes a simple

Amit Kumar Gupta; Ashwin M. Khambadkone

2007-01-01

77

A simple space vector PWM scheme to operate a three-level NPC inverter at high modulation index including over-modulation region, with neutral point balancing  

Microsoft Academic Search

Multilevel inverters are being increasingly used for high-power medium-voltage applications. Three-level neutral point clamped (NPC) topology is most widely used topology of multilevel inverters. However, at higher modulation index, particularly in over-modulation region, the neutral point fluctuation deteriorates the performance of the inverter. Furthermore, operating the inverter at lower modulation index implies that it is operated at lower voltages only,

Amit Kumar Gupta; Ashwin M. Khambadkone

2005-01-01

78

Printed Inverted-F Monopole Antenna for Internal MultiBand Mobile Phone Antenna  

Microsoft Academic Search

This study applied planar inverted-F monopole antenna to design the 7-frequency mobile antennas with the characteristics of imperceptibility, miniaturized simple production, and low cost. The entire antenna contained the sizes of the ground plane 95 × 45 × 0.8 mm 3 and the radiator 22.5 × 45 mm 2 . The simulation results show the five frequency bands to cover

Pang-Chun Tsai; Ding-Bing Lin; Hsin-Piao Lin; I-Tseng Tang; Peng-Su Chen

2011-01-01

79

Multi-Radiating-Element Printed Inverted-F Antenna With Independent Resonant Frequencies for Bandwidth Enhancement  

Microsoft Academic Search

This letter demonstrates a simple yet very effective method of bandwidth enhancement for popular printed inverted-F antennas (PIFAs). An additional radiating element is printed on the other side of the substrate, on the same side as the partially modified ground plane. Together with the primary radiating element, these provide different three electrical paths. The bandwidth of the antenna can be

Il-Young Oh; Sang-Hyuk Wi; Yongshik Lee; Jong-Gwan Yook

2010-01-01

80

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

81

Implementation of a reduced order stator-flux observer for three level NPC inverter-fed induction motor drive  

Microsoft Academic Search

This paper presents a three-level neutral point clamped (NPC) inverter fed induction motor for high power traction applications in Indian Railway Technology. This drive is operated under direct torque control (DTC) method, and it is well known for faster torque and flux control system. This method is simple to implement but DTC do not show good performance in low speed

Ranjan K. Behera; S. K. Parida; S. Behera; S. P. Das

2010-01-01

82

Progressive natural balance of neutral-point voltage of three-level NPC inverter with a modified SVM scheme  

Microsoft Academic Search

It is well known that the neutral point voltage of three-level NPC (neutral point clamped) inverter tends to deviate during operation. The voltage deviation can cause uneven voltage distribution among switching devices and additional harmonic distortion. The problem is normally mitigated by a closed loop control of the neutral point voltage. In this paper, the problem is fully analyzed from

C. Liu; B. Wu; D. Xu; N. Zargari; S. Rizzo

2006-01-01

83

An optimized algorithm for torque oscillation reduction in DTC-induction motor drives using 3-level NPC inverter  

Microsoft Academic Search

The paper presents a direct torque control DTC for induction motor drive using a 3-level NPC inverter. The control is optimized for torque oscillation reduction. The control is described evidencing the good performance validated by means of simulation. The results are reported and discussed in the paper.

G. Brando; R. Rizzo

2004-01-01

84

A sliding mode controller based DTC of 3 level NPC inverter fed induction motor employing space vector modulation technique  

Microsoft Academic Search

This paper presents the space vector modulation (SVM) based direct torque control (DTC) of induction motor fed by a three level neutral point clamped (NPC) inverter. The SVM DTC system avoids the use of the hysteresis controllers and the look up table which are usually used in the classical DTC scheme. A novel sliding mode controller (SMC) is proposed which

Thalakola Vamsee Kiran; Jinka Amarnath

2012-01-01

85

6 kV\\/1800 kVA medium voltage drive with three-level NPC inverter using IGCTs  

Microsoft Academic Search

This paper presents a 6 kV motor drive consisting of a 24-pulse rectifier and a three-level neutral-point-clamped (NPC) inverter using IGCTs. It is suitable for feeding standard industrial motors. Experimental results from the industrial installation show that the design and the implementation are successful.

Wenhua Liu; Qiang Song; Xiaorong Xie; Yuanhua Chen; Gangui Yan

2003-01-01

86

Analysis of an inverter-supplied multi-winding transformer with a full-wave rectifier at the output  

NASA Astrophysics Data System (ADS)

This paper deals with the magnetic analysis of an inverter-supplied multi-winding transformer frequently used in resistance spot welding applications. The basic structure of the analyzed system consists of an inverter, a single-phase transformer with two secondary windings and a full-wave rectifier mounted at the output of the transformer, which assure a very short rise time of the welding current. The disturbing current spikes often appear in the transformer's primary in the steady-state operation, which can activate the over-current protection switch-off of the system. The results of numerical analysis performed on the nonlinear model of the discussed system have shown that very strong magnetic saturation of the transformer's iron core, caused by the interaction among the different ohmic resistances of secondary windings and different characteristics of the output rectifier diodes, provokes unwanted current spikes. Magnetic saturation could be efficiently eliminated using very simple passive method proposed in this paper. All findings are confirmed by systematic analysis numerically and experimentally.

Klop?i?, Beno; Dolinar, Drago; Štumberger, Gorazd

87

Equalization of dc bus voltage in three-level NPC half-brige inverters for PV applications by even harmonics injection or fundamental phase modulation  

Microsoft Academic Search

The issue of dynamic equalization of the dc bus voltages unbalance is considered in the case of single-phase split-capacitor three-level neutral-point-clamped (NPC) half- bridge inverters for photovoltaic (PV) inverters. The lack of a proper equalization strategy would lead to a rapid drift of dc bus voltages, causing stability problems to the inverter output current control loop and eventually to failure

Roberto Petrella; Nicola Buonocunto; Alessandro Revelant; Piero Stocco

2011-01-01

88

DC bus voltage equalization in single-phase split-capacitor three-level neutral-point-clamped half-bridge inverters for PV applications  

Microsoft Academic Search

In this paper the issue of dynamic equalization of the dc bus voltages unbalance is considered in the case of single-phase split-capacitor three-level neutral-point-clamped (NPC) half-bridge inverters for photovoltaic (PV) inverters. The lack of a proper equalization strategy would lead to a rapid drift of dc bus voltages, causing stability problems to the inverter output current control loop and eventually

Roberto Petrella; Nicola Buonocunto; Alessandro Revelant; Piero Stocco

2011-01-01

89

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

90

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

91

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

92

New Multi-Level Codes over GF(q).  

National Technical Information Service (NTIS)

Set partitioning to multi-dimensional signal spaces over GF(q), particularly GF sup q-1(q) and GF sup q (q), and show how to construct both multi-level block codes and multi-level trellis codes over GF(q). Two classes of multi-level (n, k, d) block codes ...

J. Wu D. J. Costello

1990-01-01

93

Multi-resolution time-domain and level-set techniques for multi-domain\\/multi-physics\\/multi-phase simulations  

Microsoft Academic Search

In this paper, we present various techniques for the modeling of multi-domain\\/multi-physics and multi-phase high-frequency problems. The deployment of Multiresolution time-domain principles and of level-set based multi-phase simulation leads to a new generation of computationally efficient tools that could potentially bridge the gap between Maxwell, solid-state and solid\\/liquid-interface equations. Numerous examples of microelectromechanical, carbon-nanotube and liquid electronics will be presented

A Traille; M. M Tentzeris

2011-01-01

94

A grid-connected PV system with power quality improvement based on boost + dual-level four-leg inverter  

Microsoft Academic Search

Comparing single-stage grid-connected photovoltaic (PV) system with power quality improvement, in this paper, a high-capacity three-phase four-wire grid-connected PV system based on Boost converter + dual-level four-leg inverter is proposed, which not only allows a wide range of input voltage, but also compensates unbalance current of the local load comparing three-phase three-wire PV system. This paper explains the control principle

Jing Li; Fang Zhuo; Xianwei Wang; Lin Wang; Song Ni

2009-01-01

95

Study on neutral-point voltage balance of 3-level NPC inverter in 3-phase 4-wire system  

Microsoft Academic Search

Problem of neutral-point voltage unbalance is a key issue for 3-phase 4-wire 3-level NPC inverter. This paper analyzes the relationship between the neutral point voltage and the neutral point current. Neutral-point voltage problem is transformed into neutral-point current problem. Then value of neutral-point current under balanced and unbalanced load condition is calculated. According to the mathematical analysis, a neutral point

Wenping Zhang; Xiao Li; Chengrui Du; Xiaotian Wu; Guoqiao Shen; Dehong Xu

2010-01-01

96

A new modulation strategy for capacitor voltage balancing in three-level NPC inverters based on matrix converter theory  

Microsoft Academic Search

This paper presents a new modulation strategy for capacitor voltage balancing in three-level neutral-point-clamped inverters by applying the matrix converter theory to eliminate the low frequency oscillation of the neutralpoint voltage and current. The proposed modulation method controls the neutral-point current without affecting the averaged output voltage and current. The behavior of the new modulation technique turns out to be

Apichart Saengseethong; Somboon Sangwongwanich

2010-01-01

97

A neutral-point potential balancing algorithm for three-level NPC inverters using analytically injected zero-sequence voltage  

Microsoft Academic Search

Based on the zero-sequence component of the reference voltages, this paper comprehensively analyzes the neutral-point variation and balancing control for three-level neutral-point-clamped inverter. An analytical method is proposed to accurately calculate the injected zero-sequence voltage for NP balancing. Based on the analytical analysis, the limitation of NP balancing control is revealed and the NP-fully-controllable region is presented. A real-time NP

Qiang Song; Wenhua Liu; Qingguang Yu; Xiaorong Xie; Zhonghong Wang

2003-01-01

98

Probabilistic Multi-Scale, Multi-Level, Multi-Disciplinary Analysis and Optimization of Engine Structures  

NASA Technical Reports Server (NTRS)

Aircraft engines are assemblies of dynamically interacting components. Engine updates to keep present aircraft flying safely and engines for new aircraft are progressively required to operate in more demanding technological and environmental requirements. Designs to effectively meet those requirements are necessarily collections of multi-scale, multi-level, multi-disciplinary analysis and optimization methods and probabilistic methods are necessary to quantify respective uncertainties. These types of methods are the only ones that can formally evaluate advanced composite designs which satisfy those progressively demanding requirements while assuring minimum cost, maximum reliability and maximum durability. Recent research activities at NASA Glenn Research Center have focused on developing multi-scale, multi-level, multidisciplinary analysis and optimization methods. Multi-scale refers to formal methods which describe complex material behavior metal or composite; multi-level refers to integration of participating disciplines to describe a structural response at the scale of interest; multidisciplinary refers to open-ended for various existing and yet to be developed discipline constructs required to formally predict/describe a structural response in engine operating environments. For example, these include but are not limited to: multi-factor models for material behavior, multi-scale composite mechanics, general purpose structural analysis, progressive structural fracture for evaluating durability and integrity, noise and acoustic fatigue, emission requirements, hot fluid mechanics, heat-transfer and probabilistic simulations. Many of these, as well as others, are encompassed in an integrated computer code identified as Engine Structures Technology Benefits Estimator (EST/BEST) or Multi-faceted/Engine Structures Optimization (MP/ESTOP). The discipline modules integrated in MP/ESTOP include: engine cycle (thermodynamics), engine weights, internal fluid mechanics, cost, mission and coupled structural/thermal, various composite property simulators and probabilistic methods to evaluate uncertainty effects (scatter ranges) in all the design parameters. The objective of the proposed paper is to briefly describe a multi-faceted design analysis and optimization capability for coupled multi-discipline engine structures optimization. Results are presented for engine and aircraft type metrics to illustrate the versatility of that capability. Results are also presented for reliability, noise and fatigue to illustrate its inclusiveness. For example, replacing metal rotors with composites reduces the engine weight by 20 percent, 15 percent noise reduction, and an order of magnitude improvement in reliability. Composite designs exist to increase fatigue life by at least two orders of magnitude compared to state-of-the-art metals.

Chamis, Christos C.; Abumeri, Galib H.

2000-01-01

99

Multi level programming Paradigm for Extreme Computing  

NASA Astrophysics Data System (ADS)

Abstract: In order to propose a framework and programming paradigms for post-petascale computing, on the road to exascale computing and beyond, we introduced new languages, associated with a hierarchical multi-level programming paradigm, allowing scientific end-users and developers to program highly hierarchical architectures designed for extreme computing. In this paper, we explain the interest of such hierarchical multi-level programming paradigm for extreme computing and its well adaptation to several large computational science applications, such as for linear algebra solvers used for reactor core physic. We describe the YML language and framework allowing describing graphs of parallel components, which may be developed using PGAS-like language such as XMP, scheduled and computed on supercomputers. Then, we propose experimentations on supercomputers (such as the "K" and "Hooper" ones) of the hybrid method MERAM (Multiple Explicitly Restarted Arnoldi Method) as a case study for iterative methods manipulating sparse matrices, and the block Gauss-Jordan method as a case study for direct method manipulating dense matrices. We conclude proposing evolutions for this programming paradigm.

Petiton, S.; Sato, M.; Emad, N.; Calvin, C.; Tsuji, M.; Dandouna, M.

2014-06-01

100

Dead-time compensation of 3-level NPC inverter for medium voltage IGCT drive system  

Microsoft Academic Search

In most cases, it is essential to insert a delay time in the switching signals to avoid the damage of the power electronic devices and prevent the shoot-through of the DC-link. This causes the dead-time effect and it can be minimized to improve the performance of inverters. In this paper, a novel method, which can eliminate the deviation of the

Haishan Li; Yaohua Li; Qiongxuan Ge

2004-01-01

101

Performance comparison of a new current regulator for 3-level NPC inverter for sinusoidal and non-sinusoidal current tracking applications  

Microsoft Academic Search

In this paper, a new current regulator is applied for a 3-level NPC inverter to achieve both current regulation and neutral-point voltage balance. The performance of the proposed current regulator is validated for both sinusoidal current tracking, such as for a 3-level NPC inverter based motor drive application, and also for non-sinusoidal current tracking, such as for active filter application.

Jun Li; Subhashish Bhattacharya; Alex Huang

2008-01-01

102

Control of cascaded transformer multilevel inverter based DSTATCOM  

Microsoft Academic Search

In this paper, the design of a distribution static compensator (DSTATCOM) based on cascaded transformer multilevel inverter is proposed. The topology requires controlling only a common dc storage capacitor. Two-level ramp-comparison current control method is extended for the multilevel inverter using phase-shifted multi-carrier PWM. The method provides equal switching stress and power handling for all the cascaded units. The net

Rajesh Gupta; Arindam Ghosh; Avinash Joshi

2007-01-01

103

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

104

Application of Balancing Circuit for DC-Link Voltages Balance in a Single-Phase Diode-Clamped Inverter With Two Three-Level Legs  

Microsoft Academic Search

This paper presents investigations of dc-link voltages balance with the use of a passive RLC circuit in a single-phase diode-clamped inverter composed of two three-level legs. Applica- tion of the balancing circuit in the diode-clamped inverter needs proper PWM generation but the modulation method is the same for both in the balanced and unbalanced state. This method of dc-link voltages

Robert Stala

2011-01-01

105

Safety Stock Analysis in a MultiLevel Inventory System  

Microsoft Academic Search

In this paper a model is presented for determination of the expected annual total cost of inventory for a multi-level inventory system. The model permits identification of the safety stock levels needed to minimize the expected annual total cost for a multi-level inventory system, such as distributed warehouses. An example of the application of the model is given.

M. K. Salameh; J. W. Schmidt

1984-01-01

106

A Design for Linking Tests of a Multi-Level, Multi-Form Achievement Series.  

ERIC Educational Resources Information Center

Traditionally, comparable content-area forms and levels of a multi-level, multi-form achievement test series have been equated using the equipercentile method. There is some evidence to indicate, however, that better procedures are needed. A linking procedure is being used to equate simultaneously 40 different test forms of an achievement test:…

Lenke, Joanne M.; Canner, Jane M.

107

Propagation of twin light pulses under magneto-optical switching operations in a four-level inverted-Y atomic medium  

NASA Astrophysics Data System (ADS)

Propagation dynamics of twin laser pulses through a cold four-level inverted-Y atomic medium is investigated theoretically via switching on and off an external magnetic field under the application of a strong driving field. By numerically solving the coupled Bloch-Maxwell equations for atom and field simultaneously on a spacetime grid, our spatio-temporal results clearly show that dynamic control of twin-pulse propagation and magneto-optic dual switching operation are possible in such an inverted-Y system. The proposed scheme may be used for the design of magneto-optic switching and magneto-optic storage devices.

Li, Jiahua; Yu, Rong; Si, Liugang; Yang, Xiaoxue

2010-03-01

108

Multi-Level Sequential Pattern Mining Based on Prime Encoding  

NASA Astrophysics Data System (ADS)

Encoding is not only to express the hierarchical relationship, but also to facilitate the identification of the relationship between different levels, which will directly affect the efficiency of the algorithm in the area of mining the multi-level sequential pattern. In this paper, we prove that one step of division operation can decide the parent-child relationship between different levels by using prime encoding and present PMSM algorithm and CROSS-PMSM algorithm which are based on prime encoding for mining multi-level sequential pattern and cross-level sequential pattern respectively. Experimental results show that the algorithm can effectively extract multi-level and cross-level sequential pattern from the sequence database.

Lianglei, Sun; Yun, Li; Jiang, Yin

109

Squeezed light from conventionally pumped multi-level lasers  

NASA Technical Reports Server (NTRS)

We have calculated the amplitude squeezing in the output of several conventionally pumped multi-level lasers. We present results which show that standard laser models can produce significantly squeezed outputs in certain parameter ranges.

Ralph, T. C.; Savage, C. M.

1992-01-01

110

Modelling and control of three-phase PWM voltage source rectifiers- five-level NPC voltage source inverter-induction machine system  

Microsoft Academic Search

The three phase five-level Neutral Point Clamped (NPC) source voltage inverter (VSI) is a good topology for high voltage and high power applications where no semiconductor devices are available. However, it has an inherent problem of the midpoint (neutral point) balance. As consequence, the four capacitor voltages of the input DC voltage source of this converter are not equal, leading

R. Guedouani; B. Fiala; E. M. Berkouk; M. S. Boucherit

2010-01-01

111

MultiLevel Current Reinjection CSC for STATCOM Application  

Microsoft Academic Search

A multi-level current reinjection concept, already shown to provide acceptable harmonic reduction with fewer switching components than the conventional multi-level schemes, is described in this paper with reference to its performance when operated as a STATCOM. PSCAD\\/EMTDC is used to illustrate the steady state and fast dynamic response to system changes, both under symmetrical and asymmetrical terminal voltage conditions.

Y. H. Liu; N. R. Watson; J. Arrillaga; L. B. Perera

2006-01-01

112

STATCOM Performance of A MultiLevel Voltage Reinjection Converter  

Microsoft Academic Search

A multi-level voltage reinjection concept, already shown to provide acceptable harmonic reduction with fewer switching components than the conventional multi-level schemes, is described in this paper with reference to its performance when operated as a STATCOM. EMTDC-PSCAD is used to illustrate the steady state and fast dynamic response to system changes, both under symmetrical and asymmetrical terminal voltage conditions

Y. H. Liu; J. Arrillaga; N. R. Watson

2005-01-01

113

Collision Dynamics Model of a Multi-Level Train.  

National Technical Information Service (NTIS)

In train collisions, multi-level rail passenger vehicles can deform in modes that are different from the behavior of single level cars. The deformation in single level cars usually occurs at the front end during a collision. In one particular incident, a ...

B. Perlman D. Tyrell M. Priante

2006-01-01

114

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

115

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

116

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

117

Multi-Level Trellis Coded Modulation and Multi-Stage Decoding.  

National Technical Information Service (NTIS)

Several constructions for multi-level trellis codes are presented and many codes with better performance than previously known codes are found. These codes provide a flexible trade-off between coding gain, decoding complexity, and decoding delay. New mult...

D. J. Costello J. Wu S. Lin

1990-01-01

118

Multi-level multi-domain simulations: a new approach to multi-scale multi-physics descriptions  

NASA Astrophysics Data System (ADS)

There are a number of modeling challenges posed by space weather numerical simulations. Most of them arise from the multi-scale and multi-physics aspects of the problem. The multiple scales dramatically increase the requirements, in terms of computational resources, because of the need to carry large scale simulations with the proper small-scales resolution. Lately, many suggestions have been made to overcome this difficulty by using various refinement methods which consist in splitting the domain into regions of different resolutions. The multiple physics are generally treated in a similar way: interfaces separate the regions where different equations are solved. We present here an innovative approach based on the coexistence of several levels of description, which differ either by their resolutions or by their physics. Instead of interacting through interfaces, these levels are all entirely simulated and are interlocked over the complete extension of their overlapping area. This scheme has been applied to a two-dimensional implicit Particle in Cell code. Some results of magnetic reconnection simulations are presented and we also discuss the optimal implementation of this scheme on very large clusters.

Beck, Arnaud; Innocenti, M. E.; Lapenta, Giovanni; Markidis, Stefano

2012-10-01

119

Multi-Level Selective Classes for Gifted Students  

ERIC Educational Resources Information Center

Research was undertaken to examine the level of support and general attitudes towards multi-level selective classes for gifted students amongst the staff and parents of an independent (non-government) boys' Preparatory school, located in Adelaide, South Australia. Questionnaires were sent to all parents and staff in the Preparatory school and…

Henderson, Lesley

2007-01-01

120

A portable runtime interface for multi-level memory hierarchies  

Microsoft Academic Search

We present a platform independent runtime interface for moving data and computation through parallel machines with multi-level memory hierarchies. We show that this interface can be used as a compiler target and can be implemented easily and efficiently on a variety of platforms. The interface design allows us to compose multiple runtimes, achieving portability across machines with multiple memory levels.

Mike Houston; Ji-Young Park; Manman Ren; Timothy J. Knight; Kayvon Fatahalian; Alex Aiken; William J. Dally; Pat Hanrahan

2008-01-01

121

Multi-Level Captioning: Alternatives that Match the Viewers' Abilities.  

ERIC Educational Resources Information Center

The Multi-Level Linguistic Captioning Project at public television station WGBH in Boston developed a method of captioning that controls vocabulary and idiomatic expressions, syntax, and inference at each of three captioning levels (simplest language, greater sophistication, and most difficult). Examples are provided along with background…

Montandon, Betsy

1982-01-01

122

On the concept of dynamic multi-level simulation  

Microsoft Academic Search

This paper proposes a new concept - dynamic multi-level simulation, also termed zooming, which may considerably enhance the speed and efficiency of simulation. The concept has been implemented and verified in RDV [GS84], an experimental prototype rule-based design verification system designed at Stanford University. Simulation at a lower level such as gate-level is usually time consuming while functional simulation is

Sumit Ghosh

1986-01-01

123

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

124

Multi-level fusion for networked ground sensors  

NASA Astrophysics Data System (ADS)

False alarms from individual sensors and duplicate detections from sensors in close proximity provide a user with inaccurate and superfluous information. Responding to all of these detections distracts the user, and also wastes system resources including bandwidth and storage capacity. Fusion can reduce these implications of an unattended sensor system and can occur on three different levels: multi-modal fusion of multiple transducer-based algorithms (including PIR, magnetic, seismic, acoustic, video, and biological/chemical) within a single remote ground sensor to provide a single detection; multi-sensor fusion which combines the detections of several remote ground sensors in a network; and multi-resource fusion which combines multi-modal and multi-sensor fusion with other resources such as historical, media, statistical, and user-defined information. Each level of fusion may be used together or separately to allow for increased sensitivity and a low false alarm rate while conserving power, bandwidth, storage capacity, and user interaction. This paper will describe the design and usage of each level of fusion in a networked unattended ground sensor system.

Knobler, Ronald

2006-06-01

125

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

126

A new SVPWM method for single-phase three-level NPC inverter and the control method of neutral point voltage balance  

Microsoft Academic Search

A space vector PWM (SVPWM) algorithm is proposed for the single-phase three-level NPC inverter, and the cause of the imbalance of the capacitor voltage in DC-side is analyzed. In order to lower the switching loss and avoid the abrupt change of output voltage vectors, an optimal SVPWM algorithm is proposed, it makes use of five-vectors modulation in which the positive

Zhang Zhi; Xie Yun-xiang; Huang Wei-ping; Le Jiang-yuan; Chen Lin

2009-01-01

127

The nearest three virtual space vector PWM - a modulation for the comprehensive neutral-point balancing in the three-level NPC inverter  

Microsoft Academic Search

This letter presents a new modulation approach for the complete control of the neutral-point voltage in the three-level three-phase neutral-point-clamped voltage source inverter. The new modulation approach, based on the virtual space vector concept, guarantees the balancing of the neutral-point voltage for any load (linear or nonlinear) over the full range of converter output voltage and for all load power

Sergio Busquets-Monge; Josep Bordonau; Dushan Boroyevich; Sergio Somavilla

2004-01-01

128

LQ control of a three-phase four-wire shunt active power filter based on three-level NPC inverter  

Microsoft Academic Search

This paper presents the design and implementation of a linear quadratic regulator (LQR) with Integral action (LQIR) for a three-phase four-wire shunt active power filter using a three-level neutral point clamped inverter (SAF-NPC). The integral action is added so as to cancel the steady state errors for reference tracking or disturbance rejection knowing that the standard LQR provides only proportional

Bachir Kedjar; Kamal Al-Haddad

2008-01-01

129

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 circuit for a five-level diode-clamped inverter intended for a medium-voltage motor drive. This circuit consists of two unidirectional choppers and a single coupled inductor with two galvanically-isolated windings. The inductor is prominent in producing no DC magnetic flux inside the magnetic core because the individual DC magnetic fluxes generated by the two windings are

Kazunori Hasegawa; Hirofumi Akagi

2009-01-01

130

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

131

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

132

SABLE: A tool for generating structured, multi-level simulations  

Microsoft Academic Search

SABLE (Structure And Behavior Linking Environment) is a system currently being developed at Stanford to support structured, multi-level behavior specification and simulation of digital systems. SABLE accepts information about the nesting and interconnectivity of components, and combines it with descriptions of their behavior, which are written in a new language called ADLIB (A Design Language for Indicating Behavior). ADLIB allows

Dwight Hill; Willam vanCleemput

1979-01-01

133

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

134

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

135

The performance of the multilevel converter topologies for PV inverter  

Microsoft Academic Search

This paper discusses the performance of a 5-level ANPC inverter for PV system which is evaluated by using the optimize design method. In addition, the performance of a 5-level ANPC inverter is then compared with the conventional 2-level inverter, 3-level NPC inverter and 3-level T-type NPC inverter. From the comparison results, within the range of switching frequency from 1 kHz

Yugo Kashihara; Jun-ichi Itoh

2012-01-01

136

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

137

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

138

Multi-level data hiding for digital image and video  

NASA Astrophysics Data System (ADS)

Previous works on data hiding generally targeted on a specific tradeoff between capacity and robustness. This results in overestimation of the processing noise under some situations and/or underestimation under some other situations, hence limits the overall performance. In this paper, we propose a multi-level data hiding scheme which is able to convey secondary data in high rate when noise is not severe and can also convey some data reliably under heavy distortion. The proposed scheme is motivated by a two- category classification of embedding schemes and by a study on detection performance of spread spectrum watermarking. The multi- level data hiding has been successfully applied to both digital image and video, and can be used for applications such as copy control.

Wu, Min; Yu, Hong H.; Gelman, Alex

1999-11-01

139

Fast Level Set Multi-View Stereo on Graphics Hardware  

Microsoft Academic Search

In this paper, we show the importance and feasibility of much faster multi-view stereo reconstruction algorithms re- lying almost exclusively on graphics hardware. Reconstruc- tion algorithms have been steadily improving in the last few years and several state-of-the-art methods are nowa- days reaching a very impressive level of quality. However all these modern techniques share a very lengthy computa- tional

Patrick Labatut; Renaud Keriven; Jean-philippe Pons

2006-01-01

140

A collaborative travel service portal with multi-level authentication  

Microsoft Academic Search

This article presents a collaborative travel portal with ecommerce and operation services based on multi-level authentication. The portal provides composite ecommerce service for tourists and distributed operation services for a virtual travel enterprise. The virtual enterprise is kind of dynamic coalition, and reorganized by tourism-related cross-regional business agencies. The portal has been developed based on two years of survey and

Yinsheng Li; Haifeng Xie; Mu Zhu; Bing Dong; Kuo-ming Chao

2009-01-01

141

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

142

Controllable generation and propagation of ultraslow optical solitons via parameters management in a five-level hyper inverted-Y atomic system  

NASA Astrophysics Data System (ADS)

The dynamics of generation and propagation of ultraslow optical solitons in a lifetime-broadened five-level hyper inverted-Y atomic system are investigated. Due to the novel absorption and dispersion properties of this system which provide the necessary ingredients for making the probe field propagate nearly transparent in three regimes, the generation of bright or dark optical solitons can be controlled with parameters management by actively manipulating the dispersion, the nonlinearity and the gain (absorption coefficient) via adjusting the corresponding one-, two- and three-photon detunings and the Rabi frequencies.

Si, Liu-Gang; Lü, Xin-You; Li, Jia-Hua; Hao, Xiangying; Wang, Meng

2009-11-01

143

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

2009-06-01

144

Stream, Inverted  

NASA Technical Reports Server (NTRS)

27 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the inverted, eroded remains of a channel -- now standing as a complex ridge that runs across the middle of this scene -- in dust-mantled terrain west of Sinus Meridiani, Mars. The original channel might have been carved by running water, but too little detail remains today to provide any certainty as to whether water was the culprit.

Location near: 5.6oN, 7.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Northern Spring

2006-01-01

145

Power inverters  

DOEpatents

Power inverters include a frame and a power module. The frame has a sidewall including an opening and defining a fluid passageway. The power module is coupled to the frame over the opening and includes a substrate, die, and an encasement. The substrate includes a first side, a second side, a center, an outer periphery, and an outer edge, and the first side of the substrate comprises a first outer layer including a metal material. The die are positioned in the substrate center and are coupled to the substrate first side. The encasement is molded over the outer periphery on the substrate first side, the substrate second side, and the substrate outer edge and around the die. The encasement, coupled to the substrate, forms a seal with the metal material. The second side of the substrate is positioned to directly contact a fluid flowing through the fluid passageway.

Miller, David H. (Redondo Beach, CA); Korich, Mark D. (Chino Hills, CA); Smith, Gregory S. (Woodland Hills, CA)

2011-11-15

146

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

147

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

148

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

149

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

150

Multi-Level Analysis of Pulsed Detonation Engines  

NASA Technical Reports Server (NTRS)

The present study explores some issues concerning the operational performance of pulsed detonation engines. Zero-, one- and two-dimensional, transient models are employed in a synergistic manner to elucidate the various characteristics that can be expected from each level of analysis. The zero-dimensional model provides rapid parametric trends that help to identify the global characteristics of pulsed detonation engines. The one-dimensional model adds key wave propagation issues that are omitted in the zero-dimensional model and helps to assess its limitations. Finally, the two-dimensional model allows estimates of the first-order multi-dimensional effects and provides an initial multi-dimensional end-correction for the one-dimensional model. The zero-dimensional results indicate that the pulsed detonation engine is competitive with a rocket engine when exhausting to vacuum conditions. At finite back pressures, the PDE out-performs the rocket if the combustion pressure rise from the detonation is added to the chamber pressure in the rocket. If the two peak pressures are the same, the rocket performance is higher. Two-dimensional corrections added to the one-dimensional model result in a modest improvement in predicted specific impulse over the constant pressure boundary condition.

Ebrahimi, Houshang B.; Mohanraj, Rajendran; Merkle, Charles L.

2001-01-01

151

Development of the Multi-Level Seismic Receiver (MLSR)  

SciTech Connect

The Advanced Geophysical Technology Department (6114) and the Telemetry Technology Development Department (2664) have, in conjunction with the Oil Recovery Technology Partnership, developed a Multi-Level Seismic Receiver (MLSR) for use in crosswell seismic surveys. The MLSR was designed and evaluated with the significant support of many industry partners in the oil exploration industry. The unit was designed to record and process superior quality seismic data operating in severe borehole environments, including high temperature (up to 200{degrees}C) and static pressure (10,000 psi). This development has utilized state-of-the-art technology in transducers, data acquisition, and real-time data communication and data processing. The mechanical design of the receiver has been carefully modeled and evaluated to insure excellent signal coupling into the receiver.

Sleefe, G.E.; Engler, B.P.; Drozda, P.M.; Franco, R.J.; Morgan, J.

1995-02-01

152

A Multi-Level Parallelization Concept for High-Fidelity Multi-Block Solvers  

NASA Technical Reports Server (NTRS)

The integration of high-fidelity Computational Fluid Dynamics (CFD) analysis tools with the industrial design process benefits greatly from the robust implementations that are transportable across a wide range of computer architectures. In the present work, a hybrid domain-decomposition and parallelization concept was developed and implemented into the widely-used NASA multi-block Computational Fluid Dynamics (CFD) packages implemented in ENSAERO and OVERFLOW. The new parallel solver concept, PENS (Parallel Euler Navier-Stokes Solver), employs both fine and coarse granularity in data partitioning as well as data coalescing to obtain the desired load-balance characteristics on the available computer platforms. This multi-level parallelism implementation itself introduces no changes to the numerical results, hence the original fidelity of the packages are identically preserved. The present implementation uses the Message Passing Interface (MPI) library for interprocessor message passing and memory accessing. By choosing an appropriate combination of the available partitioning and coalescing capabilities only during the execution stage, the PENS solver becomes adaptable to different computer architectures from shared-memory to distributed-memory platforms with varying degrees of parallelism. The PENS implementation on the IBM SP2 distributed memory environment at the NASA Ames Research Center obtains 85 percent scalable parallel performance using fine-grain partitioning of single-block CFD domains using up to 128 wide computational nodes. Multi-block CFD simulations of complete aircraft simulations achieve 75 percent perfect load-balanced executions using data coalescing and the two levels of parallelism. SGI PowerChallenge, SGI Origin 2000, and a cluster of workstations are the other platforms where the robustness of the implementation is tested. The performance behavior on the other computer platforms with a variety of realistic problems will be included as this on-going study progresses.

Hatay, Ferhat F.; Jespersen, Dennis C.; Guruswamy, Guru P.; Rizk, Yehia M.; Byun, Chansup; Gee, Ken; VanDalsem, William R. (Technical Monitor)

1997-01-01

153

Multi-level Expression Design Language: Requirement level (MEDL-R) system evaluation  

NASA Technical Reports Server (NTRS)

An evaluation of the Multi-Level Expression Design Language Requirements Level (MEDL-R) system was conducted to determine whether it would be of use in the Goddard Space Flight Center Code 580 software development environment. The evaluation is based upon a study of the MEDL-R concept of requirement languages, the functions performed by MEDL-R, and the MEDL-R language syntax. Recommendations are made for changes to MEDL-R that would make it useful in the Code 580 environment.

1980-01-01

154

A discontinuous PWM scheme for lowering the switching frequency and losses in a 3-phase 6-switch 3\\/5-level PWM VSI using a 3-limb inductor  

Microsoft Academic Search

Standard interleaved 3-level pwm schemes used in multilevel 3-phase inverters such as the NPC are shown not to be suitable for multi-level inverters using a 3-limb coupled inductor. This paper illustrates how a standard discontinuous 3-level pwm scheme can be modified to provide an appropriate excitation for a 3\\/5 level 6-switch coupled inductor inverter (CII). The pwm reference signals and

John Salmon; Jeff Ewanchuk

2012-01-01

155

Realistic mass ratio magnetic reconnection simulations with the Multi Level Multi Domain method  

NASA Astrophysics Data System (ADS)

Space physics simulations with the ambition of realistically representing both ion and electron dynamics have to be able to cope with the huge scale separation between the electron and ion parameters while respecting the stability constraints of the numerical method of choice. Explicit Particle In Cell (PIC) simulations with realistic mass ratio are limited in the size of the problems they can tackle by the restrictive stability constraints of the explicit method (Birdsall and Langdon, 2004). Many alternatives are available to reduce such computation costs. Reduced mass ratios can be used, with the caveats highlighted in Bret and Dieckmann (2010). Fully implicit (Chen et al., 2011a; Markidis and Lapenta, 2011) or semi implicit (Vu and Brackbill, 1992; Lapenta et al., 2006; Cohen et al., 1989) methods can bypass the strict stability constraints of explicit PIC codes. Adaptive Mesh Refinement (AMR) techniques (Vay et al., 2004; Fujimoto and Sydora, 2008) can be employed to change locally the simulation resolution. We focus here on the Multi Level Multi Domain (MLMD) method introduced in Innocenti et al. (2013) and Beck et al. (2013). The method combines the advantages of implicit algorithms and adaptivity. Two levels are fully simulated with fields and particles. The so called "refined level" simulates a fraction of the "coarse level" with a resolution RF times bigger than the coarse level resolution, where RF is the Refinement Factor between the levels. This method is particularly suitable for magnetic reconnection simulations (Biskamp, 2005), where the characteristic Ion and Electron Diffusion Regions (IDR and EDR) develop at the ion and electron scales respectively (Daughton et al., 2006). In Innocenti et al. (2013) we showed that basic wave and instability processes are correctly reproduced by MLMD simulations. In Beck et al. (2013) we applied the technique to plasma expansion and magnetic reconnection problems. We showed that notable computational time savings can be achieved. More importantly, we were able to correctly reproduce EDR features, such as the inversion layer of the electric field observed in Chen et al. (2011b), with a MLMD simulation at a significantly lower cost. Here, we present recent results on EDR dynamics achieved with the MLMD method and a realistic mass ratio.

Innocenti, Maria Elena; Beck, Arnaud; Lapenta, Giovanni; Markidis, Stefano

2014-05-01

156

Harmonic analysis and FPGA implementation of SHE controlled three phase CHB 11-level inverter in MV drives using deterministic and stochastic optimization techniques.  

PubMed

With the advancements in semiconductor technology, high power medium voltage (MV) Drives are extensively used in numerous industrial applications. Challenging technical requirements of MV Drives is to control multilevel inverter (MLI) with less Total harmonic distortion (%THD) which satisfies IEEE standard 519-1992 harmonic guidelines and less switching losses. Among all modulation control strategies for MLI, Selective harmonic elimination (SHE) technique is one of the traditionally preferred modulation control technique at fundamental switching frequency with better harmonic profile. On the other hand, the equations which are formed by SHE technique are highly non-linear in nature, may exist multiple, single or even no solution at particular modulation index (MI). However, in some MV Drive applications, it is required to operate over a range of MI. Providing analytical solutions for SHE equations during the whole range of MI from 0 to 1, has been a challenging task for researchers. In this paper, an attempt is made to solve SHE equations by using deterministic and stochastic optimization methods and comparative harmonic analysis has been carried out. An effective algorithm which minimizes %THD with less computational effort among all optimization algorithms has been presented. To validate the effectiveness of proposed MPSO technique, an experiment is carried out on a low power proto type of three phase CHB 11- level Inverter using FPGA based Xilinx's Spartan -3A DSP Controller. The experimental results proved that MPSO technique has successfully solved SHE equations over all range of MI from 0 to 1, the %THD obtained over major range of MI also satisfies IEEE 519-1992 harmonic guidelines too. PMID:24010030

Vesapogu, Joshi Manohar; Peddakotla, Sujatha; Kuppa, Seetha Rama Anjaneyulu

2013-01-01

157

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

158

A cost benefit operator for efficient multi level genetic algorithm searches  

Microsoft Academic Search

In this paper we present a novel cost benefit operator that assists multi level genetic algorithm searches. Through the use of the cost benefit operator, it is possible to dynamically constrain the search of the base level genetic algorithm, to suit the user's requirements. Initially we review meta-evolutionary (multi-level genetic algorithm) approaches. We note that the current literature has abundant

George G. Mitchell; Barry Mcmullin; James Decraene

2007-01-01

159

Dynamic, multi-level network models of clinical trials.  

PubMed

While networks models have often been applied to complex biological systems, they are increasingly being implemented to investigate clinical questions. Clinical trials have been studied extensively by traditional statistical methods but never, to our knowledge, using networks. We obtained data for 6,847 clinical trials from five "Nervous System Diseases" (NSD) and five "Behaviors and Mental Disorders" (BMD) from the clinicaltrials.gov registry. We constructed networks of diseases and interventions for visualization and analysis using Cytoscape software. To standardize nomenclature and enable multi-level annotation, we used MeSH and UMLS terms. We then constructed separate BMD and NSD networks to study dynamics over time. To assess how topology features related to clinical significance, we constructed a sub-network of Multiple Sclerosis and Alzheimer's trials and identified which trials had been published in high-profile medical journals. We found that the BMD network has evolved into a large, decentralized topology and does not distinctly reflect the five diseases by which it was defined, while the NSD network does, though other diseases and sub-phenotypes have emerged as areas of research. We also found that high-profile trials have distinctive network characteristics. Future work is needed to address mathematical questions such as scale-dependence of network features, clinical questions such as trial design optimization, and methodological questions such as data quality improvement. PMID:21121031

Sorani, Marco D; Manley, Geoffrey T; Claude Hemphill, J; Baranzini, Sergio E

2011-01-01

160

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

161

A multi-level assessment methodology for determining the potential for groundwater contamination by pesticides  

Microsoft Academic Search

A multi-level pesticide assessment methodology has been developed to permit regulatory personnel to undertake a variety of assessments on the potential for pesticide used in agricultural areas to contaminate the groundwater regime at an increasingly detailed geographical scale of investigation. A multi-level approach accounts for a variety of assessment objectives and detail required in the assessment, the restrictions on the

A. S. Crowe; W. G. Booty

1995-01-01

162

A MultiLevel Transaction Approach to Federated DBMS Transaction Management  

Microsoft Academic Search

Transaction management in federated database management systems (FDBMS) is compared with multi-level transaction management. An FDBMS has global and local transaction management and can therefore be viewed as a multi-level system. In order to cope properly with local transactions, a dynamic conflict relation between global subtransactions is introduced. By exploiting the knowledge about the context of the conflicts between global

Hans-jörg Schek; Gerhard Weikum; Werner Schaad

1991-01-01

163

Multi-system, multi-signal GNSS-reflectometry for sea level observations  

NASA Astrophysics Data System (ADS)

Information on sea level and its changes are important in connection to global change processes. For centuries sea level has been observed with coastal tide gauges and since some decades with satellite altimetry. Furthermore, during recent years also the application of GNSS-reflectometry for sea level observations has been developed. Various methods exist, using ground-based, airborne and space-borne systems, and using different analysis methods. We present results from a dedicated GNSS-based tide gauge installed at the Onsala Space Observatory at the Swedish west coast. This installation consists of two sets of commercially-off-the-shelf GNSS equipment, including geodetic-type choke-ring antennae and geodetic-type receivers. The two antennae are mounted on a beam extending in southward direction over the coastline. The antennae are aligned along the local vertical with one antenna facing toward zenith direction and the other facing toward nadir. The zenith-looking antenna is Right-Hand-Circular-Polarised (RHCP) while the nadir-looking antenna is Left-Hand-Circular-Polarised (LHCP). The zenith-looking antenna receives predominantly the direct RHCP satellite signals, while the nadir-looking antenna receives predominantly signals that are reflected off the sea surface and thus have changed polarisation to LHCP in the reflection process. The GNSS-receivers are connected to one antenna each and individually record multi-frequency signals of several GNSS. The recorded data can be analysed in different ways to derive information on the sea level and its variation. For example, data from both receivers can be analysed together applying geodetic-type phase-delay analysis with a single-difference and/or double-difference strategy. These analysis methods determine the baseline between the two antennae, which is proportional to the height of the installation above the sea surface. Another analysis method exploits the multipath oscillations in the recorded Signal-to-Noise Ratio (SNR) data observed with the zenith-looking antenna/receiver to determine the distance between the sea surface and the antenna. The different approaches have advantages and disadvantages, and they can be combined with standard positioning of the zenith-looking antenna to give absolute sea level information. In the presentation we describe the installation, the analysis methods and present the corresponding results. The focus is in particular on GPS and GLONASS observations in both L-band frequency bands, and the result obtained are from the different analysis approaches are compared with independently derived sea level observations from a co-located traditional tide gauge. Our results show that GPS and GLONASS phase-delay analysis method using signals in the L1 and L2 frequency bands gives a root-mean-square (RMS) agreement on the order of 3-4 cm when compared to independently observed sea level data. The corresponding results derived from the SNR-analysis method are worse by a factor of about 1.5 and 3 for the L1 and L2 frequency bands, respectively. However, the SNR-method appears to have advantages in conditions of high sea surface roughness. References: Löfgren J, Haas R, Scherneck H-G, Bos M (2011) Three months of local sea level derived from reflected GNSS signals. Radio Science, 46 (RS0C05) Larson K, Löfgren J, Haas R (2013) Coastal Sea Level Measurements Using a Single Geodetic GPS Receiver. Advances in Space Research, 51 (8) pp. 1301-1310.

Löfgren, Johan; Haas, Rüdiger

2014-05-01

164

Multi-Level Recording in Erasable Phase-Change Media by Light Intensity Modulation.  

National Technical Information Service (NTIS)

Multi-level recording has advantage of increasing the recording density without extensively altering the current optic configuration. In this paper, a new four-level recording phase-change disk using three-recording layers was demonstrated. By modulating ...

H. P. Shieh Y. L. Chen

2000-01-01

165

Recent advances in multilevel converter\\/inverter topologies and applications  

Microsoft Academic Search

Multilevel converters and inverters have become the enabling power conversion technology for high voltage high power applications in today's power systems and large motor drives. Although the neutral-point clamped (NPC, a 3-level) inverter was invented in 1979, the multilevel concept was not formally established until the early 1990s when the diode-clamped multilevel inverter, the capacitor-clamped (or flying capacitor) multilevel inverter,

Fang Z. Peng; Wei Qian; Dong Cao

2010-01-01

166

Multi-scale dynamic human fatigue detection with feature level fusion  

Microsoft Academic Search

Driver fatigue is a significant reason for many traffic accidents. We propose a novel multi-scale dynamic feature with feature level fusion for driver fatigue detection from facial image sequences. First, Gabor filters are employed to extract multi-scale and multi-orientation features from each image. Features of the same scale are then fused according to a fusion rule to produce a single

Xiao Fan; Yanfeng Sun; Baocai Yin

2008-01-01

167

MultiLevel Modeling of Dyadic Data in Sport Sciences: Conceptual, Statistical, and Practical Issues  

Microsoft Academic Search

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 non-technical manner. A database of 66 athletes regrouped in

Patrick Gaudreau; Marie-Claude Fecteau; Stéphane Perreault

2010-01-01

168

PRML Detection of MultiLevel DVD Channels with Run-Length-Limited Modulation  

Microsoft Academic Search

Multi-level optical recording using run-length- limited (RLL) modulation is a novel method to significantly increase the information recording density without changing optical or mechanical parameters. In this paper, the experimental results of four-level RLL modulation on read-only digital versatile discs (DVD-ROM) are introduced. Since multi-level readout signals have heavy inter-symbol interferences (ISI), partial-response maximum-likelihood (PRML) detection scheme is proposed for

Hua Hu; Longfa Pan

2007-01-01

169

Asymptotic Capacity and Optimal Precoding Strategy of MultiLevel Precode & Forward in Correlated Channels  

Microsoft Academic Search

We analyze a multi-level MIMO relaying system where a multiple-antenna transmitter sends data to a multiple- antenna receiver through several relay levels, also equipped with multiple antennas. Assuming correlated fading in each hop, each relay receives a faded version of the signal transmitted by the previous level, performs precoding on the received signal and retransmits it to the next level.

Nadia Fawaz; Keyvan Zarifi; Merouane Debbah; David Gesbert

2008-01-01

170

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

171

The Development and Evaluation of Multi-Level Assessment Framework for Analyzing Online Interaction  

ERIC Educational Resources Information Center

Interaction is one of the key variables involved in successful online learning. Previous studies analyzing online interaction are limited in their ability to reveal dynamic aspects of interaction in online learning environments. The aim of this study is to develop and test the multi-level assessment framework for analyzing multi-facets of online…

Song, Hae-Deok; Yonkers, Virginia

2004-01-01

172

Toward multi-level modeling of robotic sensor networks: a case study in acoustic event monitoring  

Microsoft Academic Search

Modeling and simulation can be powerful tools for analyzing multi-agent systems, such as networked robotic systems and sensor networks. In this paper, it is shown concretely how instances of both these elements fit into a general methodology for multi-level modeling, providing insight into system dynamics. Use of the resulting general framework is illustrated through appli- cation to a specific sample

Christopher M. Cianci; Thomas Lochmatter; Jim Pugh; Alcherio Martinoli

2007-01-01

173

Multi-party d-Level Quantum Secret Sharing Scheme  

NASA Astrophysics Data System (ADS)

We develop a multiparty quantum secret sharing (QSS) scheme of classical messages based on arbitrary dimensional multi-particle Greenberger-Horne-Zeilinger (GHZ) states. This scheme can be implemented using only local operations, e.g. generalized Z gate and Hadamard gate, and classical communication (LOCC) between participants. The security of the present scheme against exterior eavesdropping and interior dishonest party has been analyzed and confirmed. Moreover, we discuss the possibility of successful sharing of classical messages in the realistic situation where our QSS scheme is carried out in generalized Pauli channels.

Xiao, Heling; Gao, Jingliang

2013-06-01

174

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

175

Multi Level Single Linkage Method for Unconstrained and Constrained Global Optimization,  

National Technical Information Service (NTIS)

The more successful methods for unconstrained global optimization of an arbitrary multimodal objective function are of a stochastic nature and involve a combination of sampling and local search techniques. In the class, the recently developed Multi Level ...

A. H. G. Rinnooy Kan G. T. Timmer

1985-01-01

176

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

EPA Science Inventory

Recent studies have been conducted to evaluate different sampling techniques for determining VOC concentrations in groundwater. Samples were obtained using multi-level and traditional sampling techniques in three monitoring wells at the Raymark Superfund site in Stratford, CT. Ve...

177

Asymmetrical DC Link Voltage Configuration for a Diode-Clamped Inverter  

NASA Astrophysics Data System (ADS)

There is a trade off between a number of output voltage levels and the reliability and efficiency of a multilevel converter. A new configuration of diode-clamped multilevel inverters with a different combination of DC link capacitors voltage has been proposed in this paper. Two different symmetrical and asymmetrical unequal arrangements for a four-level diode-clamped inverter have been compared, in order to find an optimum arrangement with lower switching losses and optimised output voltage quality. The simulation and hardware results for a four-level inverter show that the asymmetrical configuration can obtain more output voltage levels with the same number of components compared with a conventional four-level inverter and this will lead to the reduction of the harmonic content of the output voltage. A new family of multi-output DC-DC converters with a simple control strategy has been utilised as a front-end converter to supply the DC link capacitor voltages for the optimised configuration.

Nami, Alireza; Zare, Firuz; Ghosh, Arindam

178

A Novel Switching Sequence Design for Five-Level NPC\\/H-Bridge Inverters with Improved Output Voltage Spectrum and Minimized Device Switching Frequency  

Microsoft Academic Search

This paper presents a novel flexible 3-segment switching sequence for the space vector modulation (SVM) of high-power multilevel converters. The switching sequence is optimized for the improvement of harmonic spectrum and the minimization of device switching frequency. Compared to other commonly used switching sequences, the output voltage spectrum of the proposed scheme shows higher inverter equivalent switching frequencies and lower

Zhongyuan Cheng; Bin Wu

2006-01-01

179

A Novel Switching Sequence Design for Five-Level NPC\\/H-Bridge Inverters With Improved Output Voltage Spectrum and Minimized Device Switching Frequency  

Microsoft Academic Search

This paper presents a novel switching sequence design for the space-vector modulation of high-power multilevel converters. The switching sequences are optimized for the improvement of harmonic spectrum and the minimization of device switching frequency. Compared to other commonly used switching sequences, the output spectrum of the proposed design shows higher inverter equivalent switching frequency. Meanwhile, the device switching frequency is

Zhongyuan Cheng; Bin Wu

2007-01-01

180

PHIL Inverter Test Report: Analysis of High-Penetration Levels of PV into the Distribution Grid in California - March 12-March 16, 2012.  

National Technical Information Service (NTIS)

This test report analyzes the results of power hardware-in-the-loop (PHIL) simulation testing of a 500 kW Satcon photovoltaic (PV) inverter. The tests were conducted at the Center for Advanced Power Systems (CAPS) at Florida State University (FSU) from Ma...

M. Kromer

2013-01-01

181

Inverted Perspectives: Triggering Change  

Microsoft Academic Search

Albert Einstein imagined riding a beam of light and discovered relativity. Jonas Salk imagined being a polio virus and discovered a vaccine. Nobel Laureate Richard Feynman discovered new ways of thinking about physics by imagining himself immersed in a messy fog of electrons. In each instance, an inverted perspective triggered a great discovery. Now invert the traditional healthcare universe, and

Tom Munnecke; Robert M. Kolodner

182

Fabrication of a MultiLevel Lens Using Independent-Exposure Lithography and FAB Plasma Etching  

Microsoft Academic Search

Recently, a micro lens is need for the micro optical system requiring thin thickness. A multi-level lens can be adaptable to satisfy the requirement of this purpose. In this study, an independent-exposure of electron beam lithography and FAB plasma etching method are presented for the fabrication of a multi-level lens. The advantages of the method are the non-repetitive process and

Do Kyun Woo; Kazuhiro Hane; Cha Bum Lee; Sun Kyu Lee

2007-01-01

183

MultiLevel Fuzzy Score Fusion for Client Specific Linear Discriminant Analysis Based Face Authentication System  

Microsoft Academic Search

A client specific linear discriminant analysis (CSLDA) based face authentication system has been developed with multi-level fuzzy score fusion. The CSLDA method provides two measures for authentication: distance to the client (Client Score) and distance to the mean of impostors (Impostor Score). A two-level multi-sample score fusion method has been proposed. A fuzzy inference module has also been developed to

Babak Rezaei Rowshan; Marzuki Bin Khalid; Rubiyah Yusof

2008-01-01

184

Recovery of muscle strength following multi-level orthopaedic surgery in diplegic cerebral palsy  

Microsoft Academic Search

Muscle strength changes following multi-level surgery in cerebral palsy and the impact of rehabilitation on functional recovery are largely unknown. The aim of this study was to quantify lower limb muscle strength changes in children with spastic diplegia after multi-level orthopaedic surgery and to compare the efficacy of progressive resistance strengthening (RS) versus active exercise (AE).Twenty children with spastic diplegia

Maria Seniorou; Nicky Thompson; Marian Harrington; Tim Theologis

2007-01-01

185

Trans-Z-source inverters  

Microsoft Academic Search

This paper extends the impedance-source (Z-source) inverters concept to the transformer based Z-source (trans-Z-source) inverters. The original Z-source inverter (ZSI) employs an impedance network of two inductors and two capacitors connected in a special arrangement to interface the dc source and the inverter bridge. It has overcome the conceptual limitations of the traditional voltage-source inverter and the current-source inverter. In

Wei Qian; Fang Zheng Peng; Honnyong Cha

2010-01-01

186

The European Union: an evolving system of multi-level governance ... or government?  

Microsoft Academic Search

The majority of European scholars accept that the European Union (EU) operates at several different administrative levels and exhibits some features of ' governance' . However, they disagree, often fundamentally, about the precise relationships between activities at different levels. This article critically examines the popular claim that the EU has evolved into a system of multi-level governance as opposed to

Andrew Jordan

2001-01-01

187

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

188

Integrated Inverter And Battery Charger  

NASA Technical Reports Server (NTRS)

Circuit combines functions of dc-to-ac inversion (for driving ac motor in battery-powered vehicle) and ac-to-dc conversion (for charging battery from ac line when vehicle not in use). Automatically adapts to either mode. Design of integrated inverter/charger eliminates need for duplicate components, saves space, reduces weight and cost of vehicle. Advantages in other applications : load-leveling systems, standby ac power systems, and uninterruptible power supplies.

Rippel, Wally E.

1988-01-01

189

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

190

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

191

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

192

Target identification using relative level in multi-talker listening.  

PubMed

Previous studies have suggested that listeners can identify words spoken by a target talker amidst competing talkers if they are distinguished by their spatial location or vocal characteristics. This "direct" identification of individual words is distinct from an "indirect" identification based on an association with other words (call-signs) that uniquely label the target. The present study assessed listeners' ability to use differences in presentation level between a target and overlapping maskers to identify target words. A new sentence was spoken every 800?ms by an unpredictable talker from an unpredictable location. Listeners reported color and number words in a target sentence distinguished by a unique call-sign. When masker levels were fixed, target words could be identified directly based on their relative level. Speech-reception thresholds (SRTs) were low (-12.9 dB) and were raised by 5 dB when direct identification was disrupted by randomizing masker levels. Thus, direct identification is possible using relative level. The underlying psychometric functions were monotonic even when relative level was a reliable cue. In a further experiment, indirect identification was prevented by removing the unique call-sign cue. SRTs did not change provided that other cues were available to identify target words directly. Thus, direct identification is possible without indirect identification. PMID:23654395

Kitterick, Pádraig T; Clarke, Emmet; O'Shea, Charlotte; Seymour, Josephine; Summerfield, A Quentin

2013-05-01

193

A latent-variable marginal method for multi-level incomplete binary data  

PubMed Central

Incomplete multi-level data arise commonly in many clinical trials and observational studies. Because of multi-level variations in this type of data, appropriate data analysis should take these variations into account. A random effects model can allow for the multi-level variations by assuming random effects at each level, but the computation is intensive because high-dimensional integrations are often involved in fitting models. Marginal methods such as the inverse probability weighted generalized estimating equations can involve simple estimation computation, but it is hard to specify the working correlation matrix for multi-level data. In this paper, we introduce a latent variable method to deal with incomplete multi-level data when the missing mechanism is missing at random, which fills the gap between the random effects model and marginal models. Latent variable models are built for both the response and missing data processes to incorporate the variations that arise at each level. Simulation studies demonstrate that this method performs well in various situations. We apply the proposed method to an Alzheimer’s disease study.

Chen, Baojiang; Zhou, Xiao-Hua

2013-01-01

194

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

195

Multi-leveled objects: color as a case study  

PubMed Central

The paper presents color as a case study for the analysis of phenomena that pertain to several levels of reality and are typically framed by different sciences and disciplines. Color, in fact, is studied by physics, biology, phenomenology, and esthetics, among others. Our thesis is that color is a different entity for each level of reality, and that for this reason color generates different observables in the epistemologies of the different sciences. By analyzing color as a paradigmatic case of an entity naturally spreading over different levels of reality, the paper raises the question as to whether making explicit the usually implicit ontological assumptions embedded within the different observables exploited by the different sciences may eventually clarify some of the difficulties of developing a comprehensive theory of color.

Albertazzi, Liliana; Poli, Roberto

2014-01-01

196

a Decision Level Fusion Method for Object Recognition Using Multi-Angular Imagery  

NASA Astrophysics Data System (ADS)

Spectral similarity and spatial adjacency between various kinds of objects, shadow and occluded areas behind high rise objects as well as complex relationships lead to object recognition difficulties and ambiguities in complex urban areas. Using new multi-angular satellite imagery, higher levels of analysis and developing a context aware system may improve object recognition results in these situations. In this paper, the capability of multi-angular satellite imagery is used in order to solve object recognition difficulties in complex urban areas based on decision level fusion of Object Based Image Analysis (OBIA). The proposed methodology has two main stages. In the first stage, object based image analysis is performed independently on each of the multi-angular images. Then, in the second stage, the initial classified regions of each individual multi-angular image are fused through a decision level fusion based on the definition of scene context. Evaluation of the capabilities of the proposed methodology is performed on multi-angular WorldView-2 satellite imagery over Rio de Janeiro (Brazil).The obtained results represent several advantages of multi-angular imagery with respect to a single shot dataset. Together with the capabilities of the proposed decision level fusion method, most of the object recognition difficulties and ambiguities are decreased and the overall accuracy and the kappa values are improved.

Tabib Mahmoudi, F.; Samadzadegan, F.; Reinartz, P.

2013-09-01

197

Comparing multi-target trackers on different force unit levels  

NASA Astrophysics Data System (ADS)

Consider the problem of tracking a set of moving targets. Apart from the tracking result, it is often important to know where the tracking fails, either to steer sensors to that part of the state-space, or to inform a human operator about the status and quality of the obtained information. An intuitive quality measure is the correlation between two tracking results based on uncorrelated observations. In the case of Bayesian trackers such a correlation measure could be the Kullback-Leibler difference. We focus on a scenario with a large number of military units moving in some terrain. The units are observed by several types of sensors and "meta-sensors" with force aggregation capabilities. The sensors register units of different size. Two separate multi-target probability hypothesis density (PHD) particle filters are used to track some type of units (e.g., companies) and their sub-units (e.g., platoons), respectively, based on observations of units of those sizes. Each observation is used in one filter only. Although the state-space may well be the same in both filters, the posterior PHD distributions are not directly comparable -- one unit might correspond to three or four spatially distributed sub-units. Therefore, we introduce a mapping function between distributions for different unit size, based on doctrine knowledge of unit configuration. The mapped distributions can now be compared -- locally or globally -- using some measure, which gives the correlation between two PHD distributions in a bounded volume of the state-space. To locate areas where the tracking fails, a discretized quality map of the state-space can be generated by applying the measure locally to different parts of the space.

Sidenbladh, Hedvig; Svenson, Pontus; Schubert, Johan

2004-08-01

198

A multi level control architecture for a pneumatic robotic leg  

Microsoft Academic Search

The paper describes the control architecture and the motion strategy of a five degrees of freedom robotic leg. The prototype realized is pneumatically actuated, so the control strategy is specifically designed in order to ensure a proper stability during the motion. The control architecture is composed of a three level feedback loop that allows a three dimensional trajectory generation, directly

Giovanni Muscato; Giacomo Spampinato

2005-01-01

199

Multi-level functionality of social media in the aftermath of the Great East Japan Earthquake.  

PubMed

This study examines the multi-level functionalities of social media in the aftermath of the Great East Japan Earthquake of 11 March 2011. Based on a conceptual model of multi-level story flows of social media (Jung and Moro, 2012), the study analyses the multiple functionalities that were ascribed to social media by individuals, organisations, and macro-level social systems (government and the mass media) after the earthquake. Based on survey data, a review of Twitter timelines and secondary sources, the authors derive five functionalities of social media: interpersonal communications with others (micro level); channels for local governments; organisations and local media (meso level); channels for mass media (macro level); information sharing and gathering (cross level); and direct channels between micro-/meso- and macro-level agents. The study sheds light on the future potential of social media in disaster situations and suggests how to design an effective communication network to prepare for emergency situations. PMID:24905811

Jung, Joo-Young; Moro, Munehito

2014-07-01

200

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

201

Locality management using multiple SPMs on the MultiLevel Computing Architecture  

Microsoft Academic Search

The Multi-Level Computing Architecture (MLCA) is a novel system-on-chip architecture for embedded systems designed to exploit task-level and instruction-level parallelism in multimedia applications (7). The MLCA provides a unique two-level pro- gramming model that simplifies the development of embedded ap- plications. To cope with increasing intra-system communication delays, we introduce a distributed memory version of the MLCA where separate storage

Ahmed M. Abdelkhalek; Tarek S. Abdelrahman

2006-01-01

202

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

203

Multi-phase permittivity reconstruction in electrical capacitance tomography by level-set methods  

Microsoft Academic Search

In this article, the numerical methods of reconstructing the permittivity profile of multi-phase material flow from data collected in electrical capacitance tomography (ECT) are presented. Under the assumption that multi-phase permittivity distributions are piecewise-constant functions, we develop iterative reconstruction algorithms by level-set methods that provide estimates for the interfaces and permittivity values simultaneously. Our formulation is based on the minimization

Weifu Fang

2007-01-01

204

Comparison of Traditional Inverters and Z-Source Inverter  

Microsoft Academic Search

In this paper, three different inverters-traditional PWM inverter, dc\\/dc boosted PWM inverter, and Z-source inverter were investigated and compared using fuel cell vehicle and photovoltaic domestic application as examples. Total switching device power, passive component requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power,

Miaosen Shen; Alan Joseph; Jin Wang; Fang Z. Peng; Donald J. Adams

2005-01-01

205

Clock Shift and Interstate Coherence of Multi-Level Atoms  

NASA Astrophysics Data System (ADS)

In contrast to two-level atoms, the interstate coherence of both three-level bosons and fermions contributes to the collisional frequency shift of internal transitions in a cold homogeneous gas. In particular, the measured contact shift of the b- c ( a- d) hyperfine transition in 3D atomic hydrogen in the presence of incoherently populated state a ( b) yields the difference a t - a s =30(5) pm between the triplet and singlet s-wave scattering lengths, which is a factor of 2 smaller than the previous result. The dynamic contact shift of the b- c resonance due to the Rabi oscillations between the coherently populated states a and b under the simultaneous continuous excitation of the a- b transition can explain the low-temperature electron-nuclear double resonance spectra of 2D hydrogen. The role of field inhomogeneity, spin diffusion, relaxation and recombination is discussed.

Safonov, A. I.; Safonova, I. I.; Yasnikov, I. S.

2011-02-01

206

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

207

A Bayesian Multi-Level Factor Analytic Model of Consumer Price Sensitivities across Categories  

ERIC Educational Resources Information Center

Identifying price sensitive consumers is an important problem in marketing. We develop a Bayesian multi-level factor analytic model of the covariation among household-level price sensitivities across product categories that are substitutes. Based on a multivariate probit model of category incidence, this framework also allows the researcher to…

Duvvuri, Sri Devi; Gruca, Thomas S.

2010-01-01

208

A game-theoretic multi-level optimization model for control of an international biofuel market  

Microsoft Academic Search

This paper presents a game theoretic multi-level optimization model that aims to control the international biofuel market, driving it towards the desired scenario. The resulting model gives an interpretation of the different scenarios that could face real world energy systems. The upper level decision maker, an international body, aims to maximize the total amount of biofuel that is locally produced

Ivan Dale U. Barilea; Jimmie Neil C. Kang; Raymond R. Tan

2011-01-01

209

Performance of multi level error correction in binary holographic memory  

NASA Technical Reports Server (NTRS)

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 as a function of the defect area fraction, which showed a strong influence on data integrity. Average area fractions exceeding one quarter of the bit area caused unrecoverable errors. Efficient use of the available data density was discussed. .

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

2004-01-01

210

Multi-level 3D implementation of thermo-pneumatic pumping on centrifugal microfluidic CD platforms.  

PubMed

Thermo-pneumatic (TP) pumping is a method employing the principle of expanding heated air to transfer fluids back towards the CD center on the centrifugal microfluidic CD platform. While the TP features are easy to fabricate as no moving parts are involved, it consumes extra real estate on the CD, and because heating is involved, it introduces unnecessary heating to the fluids on the CD. To overcome these limitations, we introduce a multi-level 3D approach and implement forced convection heating. In a multi-level 3D CD, the TP features are relocated to a separate top level, while the microfluidic process remains on a lower bottom level. This allows for heat shielding of the fluids in the microfluidic process level, and also improve usage of space on the CD. To aid in future implementations of TP pumping on a multi-level 3D CD, studies on the effect of heat source setting, and the effect of positioning the TP feature (it distance from the CD center) on CD surface heating are also presented. In this work, we successfully demonstrate a multi-level 3D approach to implement TP pumping on the microfluidic CD platform. PMID:24110985

Thio, Tzer Hwai Gilbert; Ibrahim, Fatimah; Al-Faqheri, Wisam; Soin, Norhayati; Abdul Kahar, Maria Kahar Bador; Madou, Marc

2013-01-01

211

Fabrication and characterization of multi-level hierarchical surfaces.  

PubMed

A nanostructured surface may exhibit low adhesion or high adhesion depending upon fibrillar density, and it presents the possibility of realizing eco-friendly surface structures with desirable adhesion by mimicking the mechanics of fibrillar adhesive surfaces of biological systems. The current research uses a patterning technique to fabricate smart adhesion surfaces: one-, two- and three-level hierarchical synthetic adhesive structure surfaces with various fibrillar densities and diameters. The contact angles and contact angle hysteresis were measured to characterize the wettability. A conventional and a glass ball attached to an atomic force microscope (AFM) tip were used to obtain the adhesive forces via force-distance curves and to study the buckling behavior of a single fiber on the hierarchical structures. PMID:23285631

Bhushan, Bharat; Lee, Hyungoo

2012-01-01

212

Equalizer design for clock recovery based on multi-level optical disk using signal waveform modulation  

NASA Astrophysics Data System (ADS)

With smaller pits and lands in multi-level optical disks using signal waveform modulation than those in DVD disks, the ISI and nonlinear attenuation of the read-out signal become more serious. One ordinary way is using an equalizer at sample rate 1/T, we proposed one method of designing the equalizer in fixed sample rate with digital interpolation. According to the analysis of the multi-level optical disk channel, we get the target frequency-response cure and implement it with seven order FIR filter. From the result of the read out experiment with multi-level optical disk, the clock of the RF signal could be recovered with the proposed equalizer.

Shao, Meng; Pei, Jing; Yang, Bo

2013-12-01

213

Displacement measurement with multi-level spiral phase filtering in speckle interferometry  

NASA Astrophysics Data System (ADS)

A multi-level spiral phase filter is proposed in electronic speckle pattern interferometry (ESPI) for out-of-plane displacement measurements. This filter generates a particular kind of speckle pattern that results from the convolution of standard speckles with the filter point spread function (Fourier transform). We shall refer to it as a vortex-filtered speckle pattern (VF-SP). It is shown here that if unresolved and fully developed VF-SPs are generated, then each speckle contains embedded phase terms which can be controlled by the multi-level spiral filter rotation. This mechanism effectively allows the application of standard phase extraction procedures for displacement measurements. Numerical simulations of an interferometer working with VF-SPs were done to verify this technique. Experimental validation was achieved with an out-of-plane electronic speckle pattern interferometer, in which an Liquid Crystal on Silicon (LCoS) was used to generate the multi-level spiral phase filters.

Aguilar, Alberto; Dávila, Abundio; Landgrave, J. E. A.

2014-01-01

214

Multi-level manual and autonomous control superposition for intelligent telerobot  

NASA Technical Reports Server (NTRS)

Space telerobots are recognized to require cooperation with human operators in various ways. Multi-level manual and autonomous control superposition in telerobot task execution is described. The object model, the structured master-slave manipulation system, and the motion understanding system are proposed to realize the concept. The object model offers interfaces for task level and object level human intervention. The structured master-slave manipulation system offers interfaces for motion level human intervention. The motion understanding system maintains the consistency of the knowledge through all the levels which supports the robot autonomy while accepting the human intervention. The superposing execution of the teleoperational task at multi-levels realizes intuitive and robust task execution for wide variety of objects and in changeful environment. The performance of several examples of operating chemical apparatuses is shown.

Hirai, Shigeoki; Sato, T.

1989-01-01

215

Squeezed light from multi-level closed-cycling atomic systems  

NASA Technical Reports Server (NTRS)

Amplitude squeezing is calculated for multi-level closed-cycling atomic systems. These systems can last without atomic population inversion in any atomic bases. Maximum squeezing is obtained for the parameters in the region of lasing without inversion. A practical four-level system and an ideal three-level system are presented. The latter system is analyzed in some detail and the mechanism of generating amplitude squeezing is discussed.

Xiao, Min; Zhu, Yi-Fu

1994-01-01

216

A multi-level solution algorithm for steady-state Markov chains  

NASA Technical Reports Server (NTRS)

A new iterative algorithm, the multi-level algorithm, for the numerical solution of steady state Markov chains is presented. The method utilizes a set of recursively coarsened representations of the original system to achieve accelerated convergence. It is motivated by multigrid methods, which are widely used for fast solution of partial differential equations. Initial results of numerical experiments are reported, showing significant reductions in computation time, often an order of magnitude or more, relative to the Gauss-Seidel and optimal SOR algorithms for a variety of test problems. The multi-level method is compared and contrasted with the iterative aggregation-disaggregation algorithm of Takahashi.

Horton, Graham; Leutenegger, Scott T.

1993-01-01

217

Changing drug users' risk environments: peer health advocates as multi-level community change agents.  

PubMed

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. PMID:19326208

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

2009-06-01

218

Multi-focus and multi-level techniques for visualization and analysis of networks with thematic data  

NASA Astrophysics Data System (ADS)

Information-rich data sets bring several challenges in the areas of visualization and analysis, even when associated with node-link network visualizations. This paper presents an integration of multi-focus and multi-level techniques that enable interactive, multi-step comparisons in node-link networks. We describe NetEx, a visualization tool that enables users to simultaneously explore different parts of a network and its thematic data, such as time series or conditional probability tables. NetEx, implemented as a Cytoscape plug-in, has been applied to the analysis of electrical power networks, Bayesian networks, and the Enron e-mail repository. In this paper we briefly discuss visualization and analysis of the Enron social network, but focus on data from an electrical power network. Specifically, we demonstrate how NetEx supports the analytical task of electrical power system fault diagnosis. Results from a user study with 25 subjects suggest that NetEx enables more accurate isolation of complex faults compared to an especially designed software tool.

Cossalter, Michele; Mengshoel, Ole J.; Selker, Ted

2013-01-01

219

PRML detection of multi-level run-length limited DVD system  

NASA Astrophysics Data System (ADS)

Multi-level optical recording using run-length-limited (RLL) modulation is a novel method to significantly increase the information recording density without changing optical or mechanical parameters. In this paper, the experimental results of four-level RLL modulation on read-only digital versatile discs (DVD-ROM) are introduced. A new DC-free 4-level RLL (2, 8) code with code rate of 8/10 (bits/symbol) is designed, and a partialresponse maximum-likelihood (PRML) detector is adopted to evaluate the detection performance of multi-level readout signals. By analyzing and comparing the simulation performances of different PRML schemes, we conclude that PR(1, 2, 2, 2, 1) target is preferred to be applied in four-level RLL modulation DVD channels.

Hu, Hua; Pan, Longfa; Ni, Yi

2008-03-01

220

Combined multi-gene analysis at the RNA and protein levels in single FFPE tissue sections.  

PubMed

Novel approaches of individualized medicine require rapid analyses of comprehensive multi-gene expression patterns both at the RNA and protein levels. Optimally these analyses are achieved with minimal amounts of tissues, which are derived from routine procedures of clinical diagnostics. We demonstrate the parallel analyses of gene expression of six different genes at the RNA and protein levels in two consecutive sections of routinely processed FFPE tissues. This was achieved by combination of multi-epitope-ligand cartography (MELC) and fully automatically magnetic bead-based RNA extraction and subsequent qRT-PCR analysis. Our work provides proof-of-principle that comprehensive analyses of multi-gene expression patterns can be achieved by the combination of these two high content technologies. This may provide new perspectives for the determination of pathogenic gene expression in the framework of individualized medicine. PMID:23583336

Ostalecki, Christian; Konrad, Andreas; Thurau, Elisabeth; Schuler, Gerold; Croner, Roland S; Pommer, Ansgar J; ael Stürzl, Mich

2013-08-01

221

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

222

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

223

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

224

Graduate Attribute Attainment in a Multi-Level Undergraduate Geography Course  

ERIC Educational Resources Information Center

We investigated students' perceptions of graduate attributes in a multi-level (second and third year) geography course. A case study with mixed methodology was employed, with data collected through focus groups and a survey. We found that undergraduate geography students can identify the skills, knowledge and attributes that are developed…

Mager, Sarah; Spronken-Smith, Rachel

2014-01-01

225

Measurement of Low Level Explosives Reaction in Gauged MultiDimensional Steven Impact Tests  

Microsoft Academic Search

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.

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

2001-01-01

226

Direct modular multi-level converter for gearless low-speed drives  

Microsoft Academic Search

The suitability of the direct modular multi-level converter for high power, low speed, gear- and transformerless drives is investigated. Control methods which optimize the capacitor voltage ripple are presented, analyzed and verified in simulation. I. INTRODUCTION Gears are unwelcome in high power low speed electric drive applications such as marine propulsion, SAG mills, hydro power, mine hoists, conveyors, wind turbines

A. J. Korn; M. Winkelnkemper; P. Steimer; J. W. Kolar

2011-01-01

227

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

228

Fast approximation of synthesized frequency response functions with automated multi-level substructuring (AMLS)  

Microsoft Academic Search

This paper presents an industrial validation case to evaluate the efficiency of automated multi-level substructuring (AMLS). This relatively new technique allows analysis of large structures up to frequencies where conventional methods are too computationally expensive. The finite element model of an industrial-sized passenger vehicle will be subjected to the substructuring procedure of AMLS. The global response will then be presented

P. Ragnarsson; T. Van Gaal; B. Pluymers; S. Donders; D. Vandepitte; W. Desmet

2011-01-01

229

Error correction for multi-level NAND flash memory using Reed-Solomon codes  

Microsoft Academic Search

Prior research efforts have been focusing on using BCH codes for error correction in multi-level cell (MLC) NAND flash memory. However, BCH codes often require highly parallel implementations to meet the throughput requirement. As a result, large area is needed. In this paper, we propose to use Reed-Solomon (RS) codes for error correction in MLC flash memory. A (828, 820)

Bainan Chen; Xinmiao Zhang; Zhongfeng Wang

2008-01-01

230

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...

231

Humanoid motion planning using multi-level DOF exploitation based on randomized method  

Microsoft Academic Search

This paper addresses a multi-level exploitation of degree of freedom (DOF), for humanoid motion planning based on a randomized method. The improvement of autonomy and mobility is required so that humanoid robot can perform tasks in various environments. Although a humanoid robot has many DOFs, all of them do not have to be controlled depending on the situation and the

Eiichi Yoshida

2005-01-01

232

The MultiLevel Supervision Model and the Interplay Between Clinical Supervision and Psychotherapy  

Microsoft Academic Search

When supervisees attempt to protect themselves form the probing nature of their supervisors, they claim that they are in supervision and not psychotherapy. Without an adequate framework to view the distinctions between psychotherapy and supervision, the result is often a diffusion of boundaries. The multi-level supervision model is a design format that synthesizes variables which share common ground with psychotherapy.

Larry Laveman

1995-01-01

233

Multi level RTS in proton irradiated CMOS image sensors manufactured in deep submicron technology  

Microsoft Academic Search

A new automated method able to detect multi level random telegraph signals in pixel arrays and to extract their main characteristics is presented. The proposed method is applied to several proton irradiated pixel arrays manufactured using a 0.18 ?m CMOS process dedicated to imaging. Despite the large proton energy range and the large fluence range used, similar exponential RTS amplitude

V. Goiffon; G. R. Hopkinson; P. Magnan; F. Bernard; G. Roland; O. Saint-Pe

2008-01-01

234

Aircraft Fault Detection and Classification Using MultiLevel Immune Learning Detection  

Microsoft Academic Search

This work is an extension of a recently developed software tool called MILD (Multi-level Immune Learning Detection), which implements a negative selection algorithm for anomaly and fault detection that is inspired by the human immune system. The immunity-based approach can detect a broad spectrum of known and unforeseen faults. We extend MILD by applying a neural network classifier to identify

Derek Wong; Scott Poll

235

Quality time tradeoff operator for designing efficient multi level genetic algorithms  

Microsoft Academic Search

We present a novel cost benefit operator that assists multi levelgenetic algorithm searches. Through the use of the cost benefitoperator, it is possible to dynamically constrain the search of thebase level genetic algorithms, to suit the users requirements. We note that the current literature has abundant studies on metaevolutionary GAs, however these approaches have not identifiedan efficient approach to the

George G. Mitchell; Barry Mcmullin; James Decraene; Ciaran Kelly

2007-01-01

236

Multi-level optimization of a beam-like space truss utilizing a continuum model  

NASA Technical Reports Server (NTRS)

A continuous beam model is developed for approximate analysis of a large, slender, beam-like truss. The model is incorporated in a multi-level optimization scheme for the weight minimization of such trusses. This scheme is tested against traditional optimization procedures for savings in computational cost. Results from both optimization methods are presented for comparison.

Yates, K.; Gurdal, Z.; Thangjitham, S.

1992-01-01

237

A read-monitored write circuit for 1T1M multi-level memristor memories  

Microsoft Academic Search

Technology migration into nano and molecular scales has led to the design of several hybrid CMOS\\/nano logic and memory architectures that aim to achieve high device density with low power consumption. The discovery of the memristor has further enabled the realization of denser nanoscale memory and logic systems by facilitating the implementation of multi-level logic. In this work we propose

Harika Manem; Garrett S. Rose

2011-01-01

238

Multi-Level Analysis Methodology. Final Report, November 1976-June 1978  

ERIC Educational Resources Information Center

This final report describes a research project in sociology of education. The general objective of the project was to develop a framework for analyzing and conceptualizing multi-level social processes that will allow researchers to examine and represent school and classroom socialization structures and their effects. The framework is based on a…

Fennessey, James; Karweit, Nancy

239

Real time information processing I: Techniques for multi-level programming with real time constraints  

Microsoft Academic Search

THE COMPLEXITY and response time constraints of future military data systems has prompted the development of priority interrupt equipment to supplement supervisory programs in multi-level program control. The analysis of machine time requirements for a given program set is straightforward. A detailed discussion of the analysis and a description of the interrupt control linkage will be presented.

J. F. Couleur; R. R. Smith; D. L. Bahrs

1962-01-01

240

New automatic multi-level thresholding technique for segmentation of thermal images  

Microsoft Academic Search

A new wavelet-based automatic multi-level thresholding technique is proposed. The new technique is a generalized version of the method proposed by Olivo [1]. Olivo [1] proposed using a set of dilated wavelets to convolve with the histogram of an image. For each scale, a set of thresholds was determined automatically based on the rules he proposed. However, Olivo did not

Jung-shiong Chang; Hong-yuan Mark Liao; Maw-kae Hor; Jun-wei Hsieh; Ming-yang Chern

1997-01-01

241

Reliability and failure analysis study of multi-die embedded micro wafer level packages  

Microsoft Academic Search

Main objective of this study is to design and development of multi-die embedded micro wafer level packages (EMWLP) reliability test vehicles. Such as, the laterally placed die EMWLP and the vertically stacked thin die EMWLP. For reliability evaluation, EMWLPs have been subjected to both environmental and mechanical reliability tests as per JEDEC standards. These reliability tests include highly accelerated stress

V. N. Sekhar; V. S. Rao; Gaurav Sharma; Ranjan Rajoo; S. T. M. Ling; Khong Chee Houe; Chong Ser Choong; Cheng Cheng Kuo

2010-01-01

242

A MultiLevel Approach to Interlingual MT: Defining the Interface between Representational Languages  

Microsoft Academic Search

This paper describes a multi-level design, i.e., a non-uniform approach to interlingual machinetranslation (MT), in which distinct representational languages are used for differenttypes of knowledge. We demonstrate that a linguistically-motivated "division of labor"across multiple representation levels has not complicated, but rather has readily facilitated,the identification and construction of systematic relations at the interface between eachlevel. Our approach assumes an interlingua...

Bonnie J. Dorr; Clare R. Voss

1996-01-01

243

A multi-level study on employee voice: Evidence from a chain of retail stores  

Microsoft Academic Search

The objective of this research is to examine the joint influence of both organizational characteristics and individual personality\\u000a on employee voice. Employing a multi-level design, data from a chain of retail stores were collected for hypothesis testing.\\u000a A total of 267 employees from 59 stores participated in this study. The results offered support for the individual-level relationships\\u000a among proactive personality,

Jian Liang; Jing Tang

2010-01-01

244

Late Cretaceous sea-level changes in Tunisia: a multi-disciplinary approach  

Microsoft Academic Search

A multi-disciplinary study of sea-level and climate proxies, including bulk rock and clay mineral compositions, carbon isotopes, total organic carbon (TOC), Sr\\/Ca ratios, and macro- and microfaunal associations, reveals seven major sea-level regressions in the southwestern Tethys during the last 10 million years of the Cretaceous: late Campanian (c. 74.2 Ma, 73.4-72.5 Ma and 72.2-71.7 Ma), early Maastrich- tian (70.7-70.3

LIANGQUAN LI; GERTA KELLER; THIERRY ADATTE; WOLFGANG STINNESBECK

2000-01-01

245

Modulation Code and PRML Detection for MultiLevel Run-Length-Limited DVD Channels  

Microsoft Academic Search

Multi-level run-length-limited (ML-RLL) modulation on optical storage channels is a promising method to increase the recording density effectively. In this paper, some experimental results of 4-level RLL modulation on digital versatile disc (DVD) read-only discs are firstly presented. A new DC-free 4-ary RLL (2.8) code with code rate of 8\\/10 (bits\\/symbol) is designed, and partial-response maximum-likelihood (PRML) detection is used

Hua Hu; Duanyi Xu; Longfa Fan

2006-01-01

246

Optimizing service-level and relevant cost for a stochastic multi-item cyclic production system  

Microsoft Academic Search

A multi-item make-to-order production system in a stochastic environment is analyzed. Assuming a common cycle production approach, the impact of safety stock, cycle time, demand, processing time and setup time on service-level and total relevant cost (holding, setup and backorder cost) is determined. To illustrate this relationship a trajectory for the service-level with respect to the relevant cost (holding and

Herbert Jodlbauer; Sonja Reitner

2012-01-01

247

A Bayesian MultiLevel Factor Analytic Model of Consumer Price Sensitivities Across Categories  

Microsoft Academic Search

Identifying price sensitive consumers is an important problem in marketing. We develop a Bayesian multi-level factor analytic\\u000a model of the covariation among household-level price sensitivities across product categories that are substitutes. Based on\\u000a a multivariate probit model of category incidence, this framework also allows the researcher to model overall price sensitivity\\u000a (i.e., indicated by higher-order factor scores) as a function

Sri Devi Duvvuri; Thomas S. Gruca

2010-01-01

248

Enabling multi-level relevance feedback on PubMed by integrating rank learning into DBMS  

PubMed Central

Background Finding relevant articles from PubMed is challenging because it is hard to express the user's specific intention in the given query interface, and a keyword query typically retrieves a large number of results. Researchers have applied machine learning techniques to find relevant articles by ranking the articles according to the learned relevance function. However, the process of learning and ranking is usually done offline without integrated with the keyword queries, and the users have to provide a large amount of training documents to get a reasonable learning accuracy. This paper proposes a novel multi-level relevance feedback system for PubMed, called RefMed, which supports both ad-hoc keyword queries and a multi-level relevance feedback in real time on PubMed. Results RefMed supports a multi-level relevance feedback by using the RankSVM as the learning method, and thus it achieves higher accuracy with less feedback. RefMed "tightly" integrates the RankSVM into RDBMS to support both keyword queries and the multi-level relevance feedback in real time; the tight coupling of the RankSVM and DBMS substantially improves the processing time. An efficient parameter selection method for the RankSVM is also proposed, which tunes the RankSVM parameter without performing validation. Thereby, RefMed achieves a high learning accuracy in real time without performing a validation process. RefMed is accessible at http://dm.postech.ac.kr/refmed. Conclusions RefMed is the first multi-level relevance feedback system for PubMed, which achieves a high accuracy with less feedback. It effectively learns an accurate relevance function from the user’s feedback and efficiently processes the function to return relevant articles in real time.

2010-01-01

249

An inverter/controller subsystem optimized for photovoltaic applications  

NASA Technical Reports Server (NTRS)

Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy.

Pickrell, R. L.; Osullivan, G.; Merrill, W. C.

1978-01-01

250

A multi-phase level set framework for source reconstruction in bioluminescence tomography  

SciTech Connect

We propose a novel multi-phase level set algorithm for solving the inverse problem of bioluminescence tomography. The distribution of unknown interior source is considered as piecewise constant and represented by using multiple level set functions. The localization of interior bioluminescence source is implemented by tracing the evolution of level set function. An alternate search scheme is incorporated to ensure the global optimal of reconstruction. Both numerical and physical experiments are performed to evaluate the developed level set reconstruction method. Reconstruction results show that the proposed method can stably resolve the interior source of bioluminescence tomography.

Huang Heyu; Qu Xiaochao; Liang Jimin [Life Sciences Research Center, School of Life Sciences and Technology, Xidian University, Xi'an, Shaanxi 710071 (China); He Xiaowei [Life Sciences Research Center, School of Life Sciences and Technology, Xidian University, Xi'an, Shaanxi 710071 (China); School of Information Science and Technology, Northwest University, Xi'an 710069 (China); Chen Xueli; Yang Da'an [Life Sciences Research Center, School of Life Sciences and Technology, Xidian University, Xi'an, Shaanxi 710071 (China); Tian Jie [Life Sciences Research Center, School of Life Sciences and Technology, Xidian University, Xi'an, Shaanxi 710071 (China); Institute of Automation, Chinese Academy of Sciences, Beijing 100190 (China)], E-mail: tian@ieee.org

2010-07-01

251

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

2003-01-01

252

Inverting the Achievement Pyramid  

ERIC Educational Resources Information Center

Attempting to invert the pyramid to improve student achievement and increase all students' chances for success is not a new endeavor. For decades, educators have strategized, formed think tanks, and developed school improvement teams to find better ways to improve the achievement of all students. Currently, the No Child Left Behind Act (NCLB) is…

White-Hood, Marian; Shindel, Melissa

2006-01-01

253

Contactless Phase Inverter.  

National Technical Information Service (NTIS)

The report introduces a contactless phase inverter consisting of basic and compensating coils mounted beside a sliding support coated with a current-conducting material. To increase the stability of the angle of phase shift, the amplitude of the output vo...

V. P. Deninskin Y. M. Shkarlet

1967-01-01

254

Power MOSFET for Inverter,  

National Technical Information Service (NTIS)

A new type of power MOSFET optimum for inverter applications has been developed. It is a power MOSFET with an on-chip free-wheeling di/dt resistance and L load switching resistance, which are defects of conventional devices, of more than 10 times that of ...

K. Sakurai N. Fujisawa T. Fujihira

1988-01-01

255

Control and stability of power inverters feeding renewable power to weak AC grids with no or low mechanical inertia  

Microsoft Academic Search

The number of power inverter installations feeding renewable energy to AC grids is worldwide increasing. The type of inverter used depends on the power level and on the AC system conditions at the terminal connection point. Line-commutated inverters need sufficient short circuit power. Self-commutated inverters can even operate without an existing grid. In both the cases the mechanical inertia decreases

W. Kuehn

2009-01-01

256

A prospective, multi-method, multi-disciplinary, multi-level, collaborative, social-organisational design for researching health sector accreditation [LP0560737  

PubMed Central

Background Accreditation has become ubiquitous across the international health care landscape. Award of full accreditation status in health care is viewed, as it is in other sectors, as a valid indicator of high quality organisational performance. However, few studies have empirically demonstrated this assertion. The value of accreditation, therefore, remains uncertain, and this persists as a central legitimacy problem for accreditation providers, policymakers and researchers. The question arises as to how best to research the validity, impact and value of accreditation processes in health care. Most health care organisations participate in some sort of accreditation process and thus it is not possible to study its merits using a randomised controlled strategy. Further, tools and processes for accreditation and organisational performance are multifaceted. Methods/design To understand the relationship between them a multi-method research approach is required which incorporates both quantitative and qualitative data. The generic nature of accreditation standard development and inspection within different sectors enhances the extent to which the findings of in-depth study of accreditation process in one industry can be generalised to other industries. This paper presents a research design which comprises a prospective, multi-method, multi-level, multi-disciplinary approach to assess the validity, impact and value of accreditation. Discussion The accreditation program which assesses over 1,000 health services in Australia is used as an exemplar for testing this design. The paper proposes this design as a framework suitable for application to future international research into accreditation. Our aim is to stimulate debate on the role of accreditation and how to research it.

Braithwaite, Jeffrey; Westbrook, Johanna; Pawsey, Marjorie; Greenfield, David; Naylor, Justine; Iedema, Rick; Runciman, Bill; Redman, Sally; Jorm, Christine; Robinson, Maureen; Nathan, Sally; Gibberd, Robert

2006-01-01

257

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

PubMed Central

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.

2013-01-01

258

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

PubMed

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. PMID:23900554

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

2013-01-01

259

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

260

Non-inverting heliostat study  

Microsoft Academic Search

Implications of employing a non-inverting heliostat design with a lower capital cost relative to an inverting design are considered from three standpoints: (1) effects of dust buildup, corresponding cleaning frequencies, and resultant cleaning costs; (2) effects of hail impact; and (3) reflected beam safety issues. It is concluded that elimination of the inverting stow hardware and addition of reflector provides

J. B. Blackmon

1979-01-01

261

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

262

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

PubMed Central

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.

Roberts, Sarah C.M.

2014-01-01

263

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

2012-07-01

264

[Study on multi-level fractal features extraction method of breast mass].  

PubMed

Breast mass is women's common disease, and it seriously affects the health of women. Accurate detection and location of the mass will greatly improve the precision of the diagnosis of the breast disease. Studies have shown that the organizational structure and surface roughness of the mass constitute the texture features of mass and it is an important basis for distinguishing the mass. In this paper, a multi-level fractal features extraction method is proposed, and, moreover, the fractal feature vector of the suspicious lesions has been established, thus realizing the feature extraction and analysis of the mammary gland. Finally, the result of classification with the support vector machine (SVM) was given. 110 mammograms are extracted and classified with an accuracy of 90%. The results showed that the multi-level fractal features extraction and classification methods proposed in this paper could improve the accuracy of mass detection and could be effective for the early diagnosis of the disease. PMID:23858747

Ke, Li; Zhang, Xue; Kang, Yan

2013-04-01

265

Fabrication of multi-level carbon nanotube arrays with adjustable patterns  

NASA Astrophysics Data System (ADS)

Multi-level carbon nanotube (CNT) arrays with adjustable patterns were prepared by a combination of the breath figure (BF) process and chemical vapor deposition. Polystyrene-b-poly(acrylic acid)/ferrocene was dissolved in carbon disulfide and cast onto a Si substrate covered with a transmission electron microscope grid in saturated relative humidity. A two-level microporous hybrid film with a block copolymer skeleton formed on the substrate after evaporation of the organic solvent and water. One level of ordered surface features originates from the contour of the hard templates; while the other level originates from the condensation of water droplets (BF arrays). Ultraviolet irradiation effectively cross-linked the polymer matrix and endowed the hybrid film with improved thermal stability. In the subsequent pyrolysis, the incorporated ferrocene in the hybrid film was oxidized and turned the polymer skeleton into the ferrous inorganic micropatterns. Either the cross-linked hybrid film or the ferrous inorganic micropatterns could act as a template to grow the multi-level CNT patterns, e.g. isolated and honeycomb-structured CNT bundle arrays perpendicular to the substrate.Multi-level carbon nanotube (CNT) arrays with adjustable patterns were prepared by a combination of the breath figure (BF) process and chemical vapor deposition. Polystyrene-b-poly(acrylic acid)/ferrocene was dissolved in carbon disulfide and cast onto a Si substrate covered with a transmission electron microscope grid in saturated relative humidity. A two-level microporous hybrid film with a block copolymer skeleton formed on the substrate after evaporation of the organic solvent and water. One level of ordered surface features originates from the contour of the hard templates; while the other level originates from the condensation of water droplets (BF arrays). Ultraviolet irradiation effectively cross-linked the polymer matrix and endowed the hybrid film with improved thermal stability. In the subsequent pyrolysis, the incorporated ferrocene in the hybrid film was oxidized and turned the polymer skeleton into the ferrous inorganic micropatterns. Either the cross-linked hybrid film or the ferrous inorganic micropatterns could act as a template to grow the multi-level CNT patterns, e.g. isolated and honeycomb-structured CNT bundle arrays perpendicular to the substrate. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr11191d

Gong, Jianliang; Sun, Lichao; Zhong, Yawen; Ma, Chunyin; Li, Lei; Xie, Suyuan; Svrcek, Vladimir

2011-12-01

266

Pulse number control of electrical resistance for multi-level storage based on phase change  

Microsoft Academic Search

Phase change nonvolatile memory devices composed of SeSbTe chalcogenide semiconductor thin film were fabricated. The resistivity of the SeSbTe system was investigated to apply to multi-level data storage. The chalcogenide semiconductor acts as a programmable resistor that has a large dynamic range. The resistance of the chalcogenide semiconductor can be set to intermediate resistances between the amorphous and crystalline states

K. Nakayama; M. Takata; T. Kasai; A. Kitagawa; J. Akita

2007-01-01

267

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

Microsoft Academic Search

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

Paul A. Taylor; Stewart A. Silling; D. A. Hughes; D. J. Bammann; M. L. Chiesa

1997-01-01

268

An adaptive, multi-level method for elliptic boundary value problems  

NASA Technical Reports Server (NTRS)

Subroutine PLTMG is a FORTRAN program for solving self-adjoint elliptic boundary value problems in general regions of R-squared. It is based on a piecewise linear triangle finite element method, an adaptive grid refinement procedure, and a multi-level iterative method to solve the resulting sets of linear equations. This paper describes the method and presents some numerical results and comparisons.

Bank, R. E.; Sherman, A. H.

1981-01-01

269

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

270

Using if-then-else DAGs for MultiLevel Logic Minimization  

Microsoft Academic Search

This article describes the use of if-then-else dags for multi-level logic minimization.A new canonical form for if-then-else dags, analogous to Bryant's canonical form forbinary decision diagrams (bdds), is introduced. Two-cuts are defined for binary decisiondiagrams, and a relationship is exhibited between general if-then-else expressions and thetwo-cuts of a bdd for the same function. The canonical form is based on representing

Kevin Karplus

1989-01-01

271

The simulation research of STATCOM based on cascaded multi-level converter  

Microsoft Academic Search

Cascaded multi-level converter based STATCOM (CMC-STATCOM), with a topology of modular-cascaded structure, has a wide prospect of applications in both transmission and distribution system. Under the background of application of STATCOM in high voltage power grid, there are many advantages of CMC-STATCOM compared with other kinds of STATCOM. On the basis of mathematical model of main topology, the states feedback

Xuefeng Liang; Yonghai Xu; Xiaolu Chen; Chunlin Guo

2011-01-01

272

A framework for meta-level control in multi-agent systems  

Microsoft Academic Search

Sophisticated agents operating in open environments must make decisions that efficiently trade off the use of their limited resources between dynamic deliberative actions and domain actions. This is the meta-level control problem for agents operating in resource-bounded multi-agent environments. Con- trol activities involve decisions on when to invoke and the amount to effort to put into scheduling and coordination of

Anita Raja; Victor R. Lesser

2007-01-01

273

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

274

A level set simulation of dendritic solidification of multi-component alloys  

NASA Astrophysics Data System (ADS)

A level set method combining features of front tracking methods and fixed domain methods is presented to model microstructure evolution in the solidification of multi-component alloys. Phase boundaries are tracked by solving the multi-phase level set equations. Diffused interfaces are constructed from these tracked phase boundaries using the level set functions. Based on the assumed diffused interfaces, volume-averaging techniques are applied for energy, species and momentum transport. Microstructure evolution in multi-component alloy systems is predicted using realistic material parameters. The methodology avoids the difficulty of parameter identification needed in other diffused interface models, and allows easy application to various practical alloy systems. Techniques including fast marching, narrow band computing and adaptive meshing are utilized to speed up computations. Several numerical examples are considered to validate the method and examine its potential for modeling solidification of practical alloy systems. These examples include two- and three-dimensional solidification of a binary alloy in an undercooled melt, a study of planar/cellular/dendritic transition in the solidification of a Ni-Cu alloy, and eutectic and peritectic solidification of an Fe-C system. Adaptive mesh refinement in the rapidly varying interface region makes the method practical for coupling the microstructure evolution at the meso-scale with buoyancy driven flow in the macro-scale, which is shown in the solidification of a Ni-Al-Ta ternary alloy.

Tan, Lijian; Zabaras, Nicholas

2007-01-01

275

Developing the evidence-base for Safe Communities: a multi-level, partly randomised, controlled trial.  

PubMed

Safe Communities, representing a global activation of the public health logic, may be strengthened through theoretical, methodological and empirical support. In the spirit of this Special Issue that aims to analyse the achievements and challenges inherent to Safe Communities, we offer our contribution in the form of a methodology of a multi-country child safety, peace and health promotion study. The study, situated within an African-centred initiative called Ukuphepha - an isiZulu word meaning demonstrating African safety - is underpinned by four theoretical claims that frame injury and violence prevention as a multi-disciplinary issue to be addressed through a suite of interventions to family and extended social systems. The interventions, sensitive to the priorities of each participating country, have been informed by the literature on effective interventions and the authors' joint experiences of community development. The study is designed as a population-based, multi-level, multi-intervention partly randomised controlled trial, and there are potentially 24 participant communities representing South Africa, Mozambique, Egypt, Zambia, Uganda, Bangladesh, Malaysia and Australia - over three commencement phases. Whereas process evaluation will focus on community engagement, impact evaluation will consider risk and protective factors, and outcome evaluation will examine the overall effectiveness of the interventions. Notwithstanding the many challenges, the study will provide insights into the methodology and mechanisms of ecologically-oriented interventions that locate injury and violence prevention as an activity arising from safety, peace and health promotion. PMID:22873717

Seedat, M; McClure, R; Suffla, S; van Niekerk, A

2012-01-01

276

Multi-level determinants of parasitic fly infection in forest passerines.  

PubMed

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. PMID:23874408

Manzoli, Darío Ezequiel; Antoniazzi, Leandro Raúl; Saravia, María José; Silvestri, Leonardo; Rorhmann, David; Beldomenico, Pablo Martín

2013-01-01

277

A single phase multilevel inverter using switched series\\/parallel DC voltage sources  

Microsoft Academic Search

A novel multilevel inverter with a small number of switching devices is proposed. It consists of an H-bridge and an inverter which outputs multilevel voltage by switching the dc voltage sources in series and in parallel. The proposed inverter can output more number of voltage levels in the same number of the switching devices by using this conversion. The number

Youhei Hinago; Hirotaka Koizumi

2009-01-01

278

Rehabilitation of a patient with a rare multi-level isthmic spondylolisthesis: a case report  

PubMed Central

A rare multi–level isthmic spondylolisthesis was discovered in a young male patient following an acute onset of low back pain. The prevalence of spondylolisthesis in the adult population is low and it is believed that the prevalence of multiple level spondylolisthesis is even rarer. A combination of onset of ambulation, hereditary factors, and sports involving hyper-extension of the spine are predisposing factors. Conservative treatment such as chiropractic manipulation and rehabilitation of the spine are first treatment options before surgical intervention is considered. The clinical presentations, radiographic features, treatment options including rehabilitation methods are discussed.

Wong, Leong C

2004-01-01

279

Conservative treatment of boundary interfaces for overlaid grids and multi-level grid adaptations  

NASA Technical Reports Server (NTRS)

Conservative algorithms for boundary interfaces of overlaid grids are presented. The basic method is zeroth order, and is extended to a higher order method using interpolation and subcell decomposition. The present method, strictly based on a conservative constraint, is tested with overlaid grids for various applications of unsteady and steady supersonic inviscid flows with strong shock waves. The algorithm is also applied to a multi-level grid adaptation in which the next level finer grid is overlaid on the coarse base grid with an arbitrary orientation.

Moon, Young J.; Liou, Meng-Sing

1989-01-01

280

A Multi-Level Approach to Outreach for Geologic Sequestration Projects  

USGS Publications Warehouse

Public perception of carbon capture and sequestration (CCS) projects represents a potential barrier to commercialization. Outreach to stakeholders at the local, regional, and national level is needed to create familiarity with and potential acceptance of CCS projects. This paper highlights the Midwest Geological Sequestration Consortium (MGSC) multi-level outreach approach which interacts with multiple stakeholders. The MGSC approach focuses on external and internal communication. External communication has resulted in building regional public understanding of CCS. Internal communication, through a project Risk Assessment process, has resulted in enhanced team communication and preparation of team members for outreach roles. ?? 2009 Elsevier Ltd. All rights reserved.

Greenberg, S. E.; Leetaru, H. E.; Krapac, I. G.; Hnottavange-Telleen, K.; Finley, R. J.

2009-01-01

281

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

282

A multi-level assessment methodology for determining the potential for groundwater contamination by pesticides.  

PubMed

A multi-level pesticide assessment methodology has been developed to permit regulatory personnel to undertake a variety of assessments on the potential for pesticide used in agricultural areas to contaminate the groundwater regime at an increasingly detailed geographical scale of investigation. A multi-level approach accounts for a variety of assessment objectives and detail required in the assessment, the restrictions on the availability and accuracy of data, the time available to undertake the assessment, and the expertise of the decision maker. The level 1: regional scale is designed to prioritize districts having a potentially high risk for groundwater contamination from the application of a specific pesticide for a particular crop. The level 2: local scale is used to identify critical areas for groundwater contamination, at a soil polygon scale, within a district. A level 3: soil profile scale allows the user to evaluate specific factors influencing pesticide leaching and persistence, and to determine the extent and timing of leaching, through the simulation of the migration of a pesticide within a soil profile. Because of the scale of investigation, limited amount of data required, and qualitative nature of the assessment results, the level 1 and level 2 assessment are designed primarily for quick and broad guidance related to management practices. A level 3 assessment is more complex, requires considerably more data and expertise on the part of the user, and hence is designed to verify the potential for contamination identified during the level 1 or 2 assessment. The system combines environmental modelling, geographical information systems, extensive databases, data management systems, expert systems, and pesticide assessment models, to form an environmental information system for assessing the potential for pesticides to contaminate groundwater. PMID:24202345

Crowe, A S; Booty, W G

1995-05-01

283

An integrated multi-source JDL high-level fusion architecture using recombinant cognition synthesis  

NASA Astrophysics Data System (ADS)

High-Level fusion systems based on the JDL model are relatively immature. Current solutions lack a comprehensive ability to manage multi-source data in a multi-dimensional vector space, and generally do not integrate collection to action models in a cohesive thread. Recombinant Cognition Synthesis (RCS) leverages best-of-breed techniques with a geospatial, temporal and semantic data model to provide a unified methodology that recombines multi-source data with analytic and predictive algorithms to synthesize actionable intelligence. This architecture framework enables the traversal of entity relationships at different level of granularities and the discovery of latent knowledge, thereby facilitating the domain problem analysis and the development of a Course-of-Action to mitigate adversarial threats. RCS also includes process refinement techniques to achieve superior information dominance, by incorporating specialized metadata. This comprehensive and unified methodology delivers enhanced utility to the intelligence analyst, and addresses key issues of relevancy, timeliness, accuracy, and uncertainty by providing metrics via feedback loops within the RCS infrastructure that augment the efficiency and effectiveness of the end-to-end fusion processing chain.

Solano, Marco A.; Ekwaro-Osire, Stephen; Tanik, Murat M.

2009-04-01

284

Low-power multi-chip module and board-level links for data transfer  

SciTech Connect

Advanced device technologies such as Vertical Cavity Surface-Emitting Lasers (VCSELs) and diffractive micro lenses can be obtained with novel packaging techniques to allow low-power interconnection of parallel optical signals. These interconnections can be realized directly on circuit boards, in a multi-chip module format, or in packages that emulate electrical connectors. For applications such as stacking of Multi-Chip Module (MCM) layers, the links may be realized in bi-directional form using integrated diffractive microlenses. In the stacked MCM design, consumed electrical power is minimized by use of a relatively high laser output from high efficiency VCSELs, and a receiver design that is optimized for low power, at the expense of dynamic range. Within certain constraints, the design may be extended to other forms such as board-level interconnects.

Carson, R.F.; Hardin, T.L.; Warren, M.E.; Lear, K.L.; Lovejoy, M.L.; Seigal, P.K.; Craft, D.C. [Sandia National Labs., Albuquerque, NM (United States); Enquist, P.J. [Research Triangle Inst., Research Triangle Park, NC (United States)

1997-03-01

285

Parallel of low-level computer vision algorithms on a multi-DSP system  

NASA Astrophysics Data System (ADS)

Parallel hardware becomes a commonly used approach to satisfy the intensive computation demands of computer vision systems. A multiprocessor architecture based on hypercube interconnecting digital signal processors (DSPs) is described to exploit the temporal and spatial parallelism. This paper presents a parallel implementation of low level vision algorithms designed on multi-DSP system. The convolution operation has been parallelized by using redundant boundary partitioning. Performance of the parallel convolution operation is investigated by varying the image size, mask size and the number of processors. Experimental results show that the speedup is close to the ideal value. However, it can be found that the loading imbalance of processor can significantly affect the computation time and speedup of the multi- DSP system.

Liu, Huaida; Jia, Pingui; Li, Lijian; Yang, Yiping

2011-04-01

286

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

287

Performance Enhancement of Embedded System Based Multilevel Inverter Using Genetic Algorithm  

NASA Astrophysics Data System (ADS)

This paper presents an optimal solution for eliminating pre specified order of harmonics from a stepped waveform of a multilevel inverter topology with equal dc sources. The main challenge of solving the associated non linear equation which are transcendental in nature and therefore have multiple solutions is the convergence of the relevant algorithms and therefore an initial point selected considerably close to the exact solution is required. The paper describes an efficient genetic algorithm that reduces significantly the computational burden resulting in fast convergence. An objective function describing a measure of effectiveness of eliminating selected order of harmonics while controlling the fundamental component is derived. The performance of cascaded multilevel inverter is compared based on computation of switching angle using Genetic Algorithm as well as conventional Newton Raphson approach. A significant improvement in harmonic profile is achieved in the GA based approach. A nine level cascaded multi level inverter is simulated in MATLAB Simulink and a proto type model has been fabricated to validate the simulation results.

Perumal, Maruthu Pandi; Nanjudapan, Devarajan

2011-07-01

288

Gas cooled traction drive inverter  

DOEpatents

The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.

Chinthavali, Madhu Sudhan

2013-10-08

289

Embedded EZ-Source Inverters  

Microsoft Academic Search

Z-source inverters are recent topological options proposed for buck-boost energy conversion with a number of possible voltage- and current-type circuitries already reported in the literature. Comparing them, a common feature noted is their inclusion of an LC impedance network, placed between the dc input source and inverter bridge. This impedance network allows the output end of a voltage-type Z-source inverter

Poh Chiang Loh; Feng Gao; Frede Blaabjerg

2010-01-01

290

Improved multi-level protein-protein interaction prediction with semantic-based regularization  

PubMed Central

Background Protein–protein interactions can be seen as a hierarchical process occurring at three related levels: proteins bind by means of specific domains, which in turn form interfaces through patches of residues. Detailed knowledge about which domains and residues are involved in a given interaction has extensive applications to biology, including better understanding of the binding process and more efficient drug/enzyme design. Alas, most current interaction prediction methods do not identify which parts of a protein actually instantiate an interaction. Furthermore, they also fail to leverage the hierarchical nature of the problem, ignoring otherwise useful information available at the lower levels; when they do, they do not generate predictions that are guaranteed to be consistent between levels. Results Inspired by earlier ideas of Yip et al. (BMC Bioinformatics 10:241, 2009), in the present paper we view the problem as a multi-level learning task, with one task per level (proteins, domains and residues), and propose a machine learning method that collectively infers the binding state of all object pairs. Our method is based on Semantic Based Regularization (SBR), a flexible and theoretically sound machine learning framework that uses First Order Logic constraints to tie the learning tasks together. We introduce a set of biologically motivated rules that enforce consistent predictions between the hierarchy levels. Conclusions We study the empirical performance of our method using a standard validation procedure, and compare its performance against the only other existing multi-level prediction technique. We present results showing that our method substantially outperforms the competitor in several experimental settings, indicating that exploiting the hierarchical nature of the problem can lead to better predictions. In addition, our method is also guaranteed to produce interactions that are consistent with respect to the protein–domain–residue hierarchy.

2014-01-01

291

Multi-level bootstrap analysis of stable clusters in resting-state fMRI.  

PubMed

A variety of methods have been developed to identify brain networks with spontaneous, coherent activity in resting-state functional magnetic resonance imaging (fMRI). We propose here a generic statistical framework to quantify the stability of such resting-state networks (RSNs), which was implemented with k-means clustering. The core of the method consists in bootstrapping the available datasets to replicate the clustering process a large number of times and quantify the stable features across all replications. This bootstrap analysis of stable clusters (BASC) has several benefits: (1) it can be implemented in a multi-level fashion to investigate stable RSNs at the level of individual subjects and at the level of a group; (2) it provides a principled measure of RSN stability; and (3) the maximization of the stability measure can be used as a natural criterion to select the number of RSNs. A simulation study validated the good performance of the multi-level BASC on purely synthetic data. Stable networks were also derived from a real resting-state study for 43 subjects. At the group level, seven RSNs were identified which exhibited a good agreement with the previous findings from the literature. The comparison between the individual and group-level stability maps demonstrated the capacity of BASC to establish successful correspondences between these two levels of analysis and at the same time retain some interesting subject-specific characteristics, e.g. the specific involvement of subcortical regions in the visual and fronto-parietal networks for some subjects. PMID:20226257

Bellec, Pierre; Rosa-Neto, Pedro; Lyttelton, Oliver C; Benali, Habib; Evans, Alan C

2010-07-01

292

Implications of multi-scale sea level and climate variability for coastal resources  

USGS Publications Warehouse

While secular changes in regional sea levels and their implications for coastal zone management have been studied extensively, less attention is being paid to natural fluctuations in sea levels, whose interaction with a higher mean level could have significant impacts on low-lying areas, such as wetlands. Here, the long record of sea level at Key West, FL is studied in terms of both the secular trend and the multi-scale sea level variations. This analysis is then used to explore implications for the Everglades National Park (ENP), which is recognized internationally for its ecological significance, and is the site of the largest wetland restoration project in the world. Very shallow topographic gradients (3–6 cm per km) make the region susceptible to small changes in sea level. Observations of surface water levels from a monitoring network within ENP exhibit both the long-term trends and the interannual-to-(multi)decadal variability that are observed in the Key West record. Water levels recorded at four long-term monitoring stations within ENP exhibit increasing trends approximately equal to or larger than the long-term trend at Key West. Time- and frequency-domain analyses highlight the potential influence of climate mechanisms, such as the El Niño/Southern Oscillation and the North Atlantic Oscillation (NAO), on Key West sea levels and marsh water levels, and the potential modulation of their influence by the background state of the North Atlantic Sea Surface Temperatures. In particular, the Key West sea levels are found to be positively correlated with the NAO index, while the two series exhibit high spectral power during the transition to a cold Atlantic Multidecadal Oscillation (AMO). The correlation between the Key West sea levels and the NINO3 Index reverses its sign in coincidence with a reversal of the AMO phase. Water levels in ENP are also influenced by precipitation and freshwater releases from the northern boundary of the Park. The analysis of both climate variability and climate change in such wetlands is needed to inform management practices in coastal wetland zones around the world.

Karamperidou, Christina; Engel, Victor; Lall, Upmanu; Stabenau, Erik; Smith, Thomas J., III

2013-01-01

293

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

294

[Narrow band multi-region level set method for remote sensing image].  

PubMed

Massive redundant contours happen when the classical Chan-Vese (C-V) model is used to segment remote sensing images, which have interlaced edges. What's more, this model can't segment homogeneous objects with multiple regions. In order to overcome this limitation of C-V model, narrow band multiple level set method is proposed. The use of N-1 curves is required for the segmentation of N regions and each curve represents one region. First, the level set model to establish an independent multi-region region can eliminate the redundant contours and avoids the problems of vacuum and overlap. Then, narrow band approach to level set method can reduce the computational cost. Experimental results of remote image verify that our model is efficient and accurate. PMID:22242504

Fang, Jiang-Xiong; Tu, En-Mei; Yang, Jie; Jia, Zhen-Hong; Nikola, Kasabov

2011-11-01

295

Monitoring Lake Level Variations in Yangtze River Basin Derived from Multi- Mission Satellite Altimetry  

NASA Astrophysics Data System (ADS)

Several satellite altimetry missions have been launched during the past decades and have demonstrated the accuracy level and the effectiveness of satellite altimetry as a technique to monitor water level variations of inland water bodies. The objective of the present study is to detect the water level fluctuations from a multi- mission approach for a better understanding of the behavior over long periods and obtain a better time resolution when overlaps exist, while trying to improve the accuracy improvement. We choose several major freshwater lakes located in the Yangtze River basin in China: Dongting Lake, Poyang Lake, Chao Lake, Hongze Lake and Taihu Lake. The altimetry data are obtained from the complete missions of Envisat, Topex and Jason-2. The timeseries of each target lake is achieved under the consideration of the error assessment between different missions.

Wu, Geli; Tourian, Mohammad; Sneeuw, Nico

2014-05-01

296

Automatic detection of multi-level acetowhite regions in RGB color images of the uterine cervix  

NASA Astrophysics Data System (ADS)

Uterine cervical cancer is the second most common cancer among women worldwide. Colposcopy is a diagnostic method used to detect cancer precursors and cancer of the uterine cervix, whereby a physician (colposcopist) visually inspects the metaplastic epithelium on the cervix for certain distinctly abnormal morphologic features. A contrast agent, a 3-5% acetic acid solution, is used, causing abnormal and metaplastic epithelia to turn white. The colposcopist considers diagnostic features such as the acetowhite, blood vessel structure, and lesion margin to derive a clinical diagnosis. STI Medical Systems is developing a Computer-Aided-Diagnosis (CAD) system for colposcopy -- ColpoCAD, a complex image analysis system that at its core assesses the same visual features as used by colposcopists. The acetowhite feature has been identified as one of the most important individual predictors of lesion severity. Here, we present the details and preliminary results of a multi-level acetowhite region detection algorithm for RGB color images of the cervix, including the detection of the anatomic features: cervix, os and columnar region, which are used for the acetowhite region detection. The RGB images are assumed to be glare free, either obtained by cross-polarized image acquisition or glare removal pre-processing. The basic approach of the algorithm is to extract a feature image from the RGB image that provides a good acetowhite to cervix background ratio, to segment the feature image using novel pixel grouping and multi-stage region-growing algorithms that provide region segmentations with different levels of detail, to extract the acetowhite regions from the region segmentations using a novel region selection algorithm, and then finally to extract the multi-levels from the acetowhite regions using multiple thresholds. The performance of the algorithm is demonstrated using human subject data.

Lange, Holger

2005-04-01

297

Four quasi-Z-Source inverters  

Microsoft Academic Search

In this paper, theoretical results are shown for several novel inverters. These inverters are similar to the Z-source inverters presented in previous works, but have several advantages, including in some combination; lower component ratings, reduced source stress, reduced component count and simplified control strategies. Like the Z-source inverter, these inverters are particularly suited for applications which require a large range

Joel Anderson; F. Z. Peng

2008-01-01

298

VLBI-resolution radio-map algorithms: Performance analysis of different levels of data-sharing on multi-socket, multi-core architectures  

NASA Astrophysics Data System (ADS)

A broad area in astronomy focuses on simulating extragalactic objects based on Very Long Baseline Interferometry (VLBI) radio-maps. Several algorithms in this scope simulate what would be the observed radio-maps if emitted from a predefined extragalactic object. This work analyzes the performance and scaling of this kind of algorithms on multi-socket, multi-core architectures. In particular, we evaluate a sharing approach, a privatizing approach and a hybrid approach on systems with complex memory hierarchy that includes shared Last Level Cache (LLC). In addition, we investigate which manual processes can be systematized and then automated in future works. The experiments show that the data-privatizing model scales efficiently on medium scale multi-socket, multi-core systems (up to 48 cores) while regardless of algorithmic and scheduling optimizations, the sharing approach is unable to reach acceptable scalability on more than one socket. However, the hybrid model with a specific level of data-sharing provides the best scalability over all used multi-socket, multi-core systems.

Tabik, S.; Romero, L. F.; Mimica, P.; Plata, O.; Zapata, E. L.

2012-09-01

299

Push pull microfluidics on a multi-level 3D CD.  

PubMed

A technique known as thermo-pneumatic (TP) pumping is used to pump fluids on a microfluidic compact disc (CD) back towards the CD center against the centrifugal force that pushes liquids from the center to the perimeter of the disc. Trapped air expands in a TP air chamber during heating, and this creates positive pressure on liquids located in chambers connected to that chamber. While the TP air chamber and connecting channels are easy to fabricate in a one-level CD manufacturing technique, this approach provides only one way pumping between two chambers, is real-estate hungry and leads to unnecessary heating of liquids in close proximity to the TP chamber. In this paper, we present a novel TP push and pull pumping method which allows for pumping of liquid in any direction between two connected liquid chambers. To ensure that implementation of TP push and pull pumping also addresses the issue of space and heating challenges, a multi-level 3D CD design is developed, and localized forced convection heating, rather than infra-red (IR) is applied. On a multi-level 3D CD, the TP features are placed on a top level separate from the rest of the microfluidic processes that are implemented on a lower separate level. This approach allows for heat shielding of the microfluidic process level, and efficient usage of space on the CD for centrifugal handling of liquids. The use of localized forced convection heating, rather than infra-red (IR) or laser heating in earlier implementations allows not only for TP pumping of liquids while the CD is spinning but also makes heat insulation for TP pumping and other fluidic functions easier. To aid in future implementations of TP push and pull pumping on a multi-level 3D CD, study on CD surface heating is also presented. In this contribution, we also demonstrate an advanced application of pull pumping through the implementation of valve-less switch pumping. PMID:23774994

Thio, Tzer Hwai Gilbert; Ibrahim, Fatimah; Al-Faqheri, Wisam; Moebius, Jacob; Khalid, Noor Sakinah; Soin, Norhayati; Kahar, Maria Kahar Bador Abdul; Madou, Marc

2013-08-21

300

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

301

Comparison of traditional inverters and Z-source inverter for fuel cell vehicles  

Microsoft Academic Search

In This work, three different inverters: traditional PWM inverter, DC\\/DC boosted PWM inverter, and Z-source inverter for fuel cell vehicles were investigated. Total switching device power of each of these inverters was calculated. For purposes of comparison, an example of the total switching device power, requirement of passive components, efficiency, and the constant power speed ratio of the different inverters

Miaosen Shen; Alan Joseph; Jin Wang; Fang Z. Peng; D. J. Adams

2004-01-01

302

Power losses of multiphase inverters  

Microsoft Academic Search

Multiphase drives are particularly attractive in medium and high-power applications such as railway and naval propulsion systems. In the most modern drives, a multiphase machine is driven by an IGBT inverter. This paper focuses the theoretical calculation of the power losses in multiphase inverters with an odd number of phases. This analysis could be useful for a preliminary assessment of

L. Zarri; M. Marano; M. Bonavoglia; D. Casadei

2010-01-01

303

The crescentic inverted scarf osteotomy  

Microsoft Academic Search

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. (The Journal of Foot & Ankle Surgery 42(1):48–50, 2003)

Todd O'Brien

2003-01-01

304

Multivariate Cutoff Level Analysis (MultiCoLA) of large community data sets  

PubMed Central

High-throughput sequencing techniques are becoming attractive to molecular biologists and ecologists as they provide a time- and cost-effective way to explore diversity patterns in environmental samples at an unprecedented resolution. An issue common to many studies is the definition of what fractions of a data set should be considered as rare or dominant. Yet this question has neither been satisfactorily addressed, nor is the impact of such definition on data set structure and interpretation been fully evaluated. Here we propose a strategy, MultiCoLA (Multivariate Cutoff Level Analysis), to systematically assess the impact of various abundance or rarity cutoff levels on the resulting data set structure and on the consistency of the further ecological interpretation. We applied MultiCoLA to a 454 massively parallel tag sequencing data set of V6 ribosomal sequences from marine microbes in temperate coastal sands. Consistent ecological patterns were maintained after removing up to 35–40% rare sequences and similar patterns of beta diversity were observed after denoising the data set by using a preclustering algorithm of 454 flowgrams. This example validates the importance of exploring the impact of the definition of rarity in large community data sets. Future applications can be foreseen for data sets from different types of habitats, e.g. other marine environments, soil and human microbiota.

Gobet, Angelique; Quince, Christopher; Ramette, Alban

2010-01-01

305

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

306

Multi-Level Interval Estimation for Locating damage in Structures by Using Artificial Neural Networks  

SciTech Connect

A new analysis technique, called multi-level interval estimation method, is developed for locating damage in structures. In this method, the artificial neural networks (ANN) analysis method is combined with the statistics theory to estimate the range of damage location. The ANN is multilayer perceptron trained by back-propagation. Natural frequencies and modal shape at a few selected points are used as input to identify the location and severity of damage. Considering the large-scale structures which have lots of elements, multi-level interval estimation method is developed to reduce the estimation range of damage location step-by-step. Every step, estimation range of damage location is obtained from the output of ANN by using the method of interval estimation. The next ANN training cases are selected from the estimation range after linear transform, and the output of new ANN estimation range of damage location will gained a reduced estimation range. Two numerical example analyses on 10-bar truss and 100-bar truss are presented to demonstrate the effectiveness of the proposed method.

Pan Danguang; Gao Yanhua; Song Junlei [School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083 (China)

2010-05-21

307

Multi-level Simulation of a Real Time Vibration Monitoring System Component  

NASA Technical Reports Server (NTRS)

This paper describes the development of a custom built Digital Signal Processing (DSP) printed circuit board designed to implement the Advanced Real Time Vibration Monitoring Subsystem proposed by Marshall Space Flight Center (MSFC) Transportation Directorate in 2000 for the Space Shuttle Main Engine Advanced Health Management System (AHMS). This Real Time Vibration Monitoring System (RTVMS) is being developed for ground use as part of the AHMS Health Management Computer-Integrated Rack Assembly (HMC-IRA). The HMC-IRA RTVMS design contains five DSPs which are highly interconnected through individual communication ports, shared memory, and a unique communication router that allows all the DSPs to receive digitized data fiom two multi-channel analog boards simultaneously. This paper will briefly cover the overall board design but will focus primarily on the state-of-the-art simulation environment within which this board was developed. This 16-layer board with over 1800 components and an additional mezzanine card has been an extremely challenging design. Utilization of a Mentor Graphics simulation environment provided the unique board and system level simulation capability to ascertain any timing or functional concerns before production. By combining VHDL, Synopsys Software and Hardware Models, and the Mentor Design Capture Environment, multiple simulations were developed to verify the RTVMS design. This multi-level simulation allowed the designers to achieve complete operability without error the first time the RTVMS printed circuit board was powered. The HMC-IRA design has completed all engineering and deliverable unit testing. P

Robertson, Bryan A.; Wilkerson, Delisa

2005-01-01

308

Multi-level Simulation of a Real Time Vibration Monitoring System Component  

NASA Technical Reports Server (NTRS)

This paper describes the development of a custom built Digital Signal Processing (DSP) printed circuit board designed to implement the Advanced Real Time Vibration Monitoring Subsystem proposed by MSFC Transportation Directorate in 2000 for the Space Shuttle Main Engine Advanced Health Management System (AHMS). This Real Time Vibration Monitoring System (RTVMS) is being developed for ground use as part of the AHMS Health Management Computer-Integrated Rack Assembly (HMC-IRA). The HMC-IRA RTVMS design contains five DSPs which are highly interconnected through individual communication ports, shared memory, and a unique communication router that allows all the DSPs to receive digitized data from two multi-channel analog boards simultaneously. This paper will briefly cover the overall board design but will focus primarily on the state-of-the-art simulation environment within which this board was developed. This 16-layer board with over 1800 components and an additional mezzanine card has been an extremely challenging design. Utilization of a Mentor Graphics simulation environment provided the unique board and system level simulation capability to ascertain any timing or functional concerns before production. By combining VHDL, Synopsys Software and Hardware Models, and the Mentor Design Capture Environment, multiple simulations were developed to verify the RTVMS design. This multi-level simulation allowed the designers to achieve complete operability without error the first time the RTVMS printed circuit board was powered. The HMCIRA design has completed all engineering unit testing and the deliverable unit is currently under development.

Roberston, Bryan; Wilkerson, DeLisa

2004-01-01

309

Readout system of multi-level run-length-limited read-only disc  

NASA Astrophysics Data System (ADS)

The Radio Frequency (RF) signal of the Multi-Level Run-Length-Limited (ML-RLL) read-only disc is different from that of DVD, so the readout system of the ML-RLL read-only disc is built specially. The readout system of the ML-RLL read-only disc can realize servo control, RF signal readout and so on. The readout system consists of Digital Versatile Disc (DVD) traverse, analog front-end and digital processing part. Analog front-end can realize front-end amplification of the output signal of the optical pick-up and power drive of mechanism. Digital processing part mainly consists of digital circuits, which functions are the servo controlling, demodulation and decoding of RF signal, general control and so on. The whole system is implemented on two Field Programmable Gate Array (FPGA) chips and the experimental results show a good performance. We tested the important signals, and experimental results are also given to verify the performance of this development platform, which meets the controlling and detecting requirements to multi-level read-only disc completely. The Bit Error Rate (SER) can achieve below 10-4.

Wang, Hequn; Xu, Haizheng; Pan, Longfa; Yan, Mingming

2008-12-01

310

System and Method for Regulating Resonant Inverters.  

National Technical Information Service (NTIS)

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 resonan...

L. D. Stevanovic R. A. Zane

2004-01-01

311

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

312

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

313

Multi-level governance: The way forward for European illicit drug policy?  

PubMed

Illicit drug policy has long been an area that has attracted international policy intervention, however, the European Union has declared it an area of subsidiarity, leaving ultimate control to national governments. Nevertheless, European Union preoccupation with the illicit drug issue and international drug trafficking and organised crime concerns have ensured that continued and increased cooperation in illicit drug policy is never off the agenda. This article examines the history of European integration in contrasting areas of policy and considers both the desirability and the viability of an increasingly harmonised drug policy for Europe. Finally, it proposes a model of integrated illicit drug policy that is strongly connected to developing patterns of European social policy, calling on multi-level governance and close involvement at the level of the citizen. PMID:18061875

Chatwin, Caroline

2007-12-01

314

Study of Multi-level Characteristics for 3D Vertical Resistive Switching Memory  

PubMed Central

Three-dimensional (3D) integration and multi-level cell (MLC) are two attractive technologies to achieve ultra-high density for mass storage applications. In this work, a three-layer 3D vertical AlO?/Ta2O5-x/TaOy resistive random access memories were fabricated and characterized. The vertical cells in three layers show good uniformity and high performance (e.g. >1000X HRS/LRS windows, >1010 endurance cycles, >104?s retention times at 125°C). Meanwhile, four level MLC is demonstrated with two operation strategies, current controlled scheme (CCS) and voltage controlled scheme (VCS). The switching mechanism of 3D vertical RRAM cells is studied based on temperature-dependent transport characteristics. Furthermore, the applicability of CCS and VCS in 3D vertical RRAM array is compared using resistor network circuit simulation.

Bai, Yue; Wu, Huaqiang; Wu, Riga; Zhang, Ye; Deng, Ning; Yu, Zhiping; Qian, He

2014-01-01

315

Influence of multi-level impurities on the dynamics of ultrashort electromagnetic pulses in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Based on Maxwell's equations, we study the propagation of an ultrashort electromagnetic pulse through an array of carbon nanotubes with multi-level impurities. The effective equation for the vector potential of the electromagnetic field is first derived analytically and then solved numerically. We subsequently analyze the dependence of the pulse shape on the parameters of the energy spectrum of impurities, and more precisely on the impurity levels. Our analysis predicts a significant decrease in the pulse amplitude during the transient, which is associated with the competitive effects of dispersion and other nonlinear effects. We also uncover the effects of the hopping integrals and band gap of deep impurities on the pulse tail decay.

Zhukov, Alexander V.; Bouffanais, Roland; Konobeeva, Natalia N.; Belonenko, Mikhail B.; George, Thomas F.

2014-05-01

316

Fusing iris and palmprint at image level for multi-biometrics verification  

NASA Astrophysics Data System (ADS)

The phase-based image matching is effective for both iris and palm recognition tasks. Hence, we can expect that the approach may be useful for multimodal biometric system having palmprint and iris recognition capabilities. This paper investigates the fusion of palmprint and iris biometric at image level. A new image fusion algorithm named Baud limited image product (BLIP) especially for phase-based image matching is proposed. Based on this, a new multi-biometric fusion scheme at image level that combines BLIP and phase-based image matching is proposed. The effective region of iris and palm images are first extracted respectively, then they are fused into one small size image using BLIP, finally matched with the template using phase-based image matching to get a score. The experimental results show that this new scheme can not only improve the system accuracy performance, but also reduce the memory size used to store the template and time consumed by the matching.

Liu, Jingwang; Hou, Yan; Wang, Jingyan; Li, Yongping; Wang, Quanquan; Man, Jiaju; Xie, Honglan; He, Jianhua

2011-12-01

317

The University of Minnesota Pathway Prediction System: multi-level prediction and visualization  

PubMed Central

The University of Minnesota Pathway Prediction System (UM-PPS, http://umbbd.msi.umn.edu/predict/) is a rule-based system that predicts microbial catabolism of organic compounds. Currently, its knowledge base contains 250 biotransformation rules and five types of metabolic logic entities. The original UM-PPS predicted up to two prediction levels at a time. Users had to choose a predicted product to continue the prediction. This approach provided a limited view of prediction results and heavily relied on manual intervention. The new UM-PPS produces a multi-level prediction within an acceptable time frame, and allows users to view prediction alternatives much more easily as a directed acyclic graph.

Gao, Junfeng; Ellis, Lynda B. M.; Wackett, Lawrence P.

2011-01-01

318

Multi-region level set image segmentation based on image energy separation model  

NASA Astrophysics Data System (ADS)

This paper presents a multi-region level set image segmentation method based on image energy separation model. The image feature is extracted by using the image energy decomposition method. We represent the regions by the level set functions with constraint. The coupled Partial Differential Equations (PDE) related to the minimization of the functional are considered through a dynamical scheme. A modified region competition factor is adopted to speed up the cure evolution functions, it also guarantees no vacuum and non-overlapping between the neighbor regions. Several experiments are conducted on both synthetic images and natural image. The results illustrate that the proposed multiregion segmentation method is fast and less sensitive to the initializations.

Yin, Xue-Min; Yan, Hong; Yao, Yu-Hua; Guo, Jian-Ping; Zhong, Chong-Fa; Zhang, Zhe; Wei, Yi

2013-07-01

319

Health, policy and geography: Insights from a multi-level modelling approach?  

PubMed Central

Improving the health and wellbeing of citizens ranks highly on the agenda of most governments. Policy action to enhance health and wellbeing can be targeted at a range of geographical levels and in England the focus has tended to shift away from the national level to smaller areas, such as communities and neighbourhoods. Our focus is to identify the potential for targeting policy interventions at the most appropriate geographical levels in order to enhance health and wellbeing. The rationale is that where variations in health and wellbeing indicators are larger, there may be greater potential for policy intervention targeted at that geographical level to have an impact on the outcomes of interest, compared with a strategy of targeting policy at those levels where relative variations are smaller. We use a multi-level regression approach to identify the degree of variation that exists in a set of health indicators at each level, taking account of the geographical hierarchical organisation of public sector organisations. We find that for each indicator, the proportion of total residual variance is greatest at smaller geographical areas. We also explore the variations in health indicators within a hierarchical level, but across the geographical areas for which public sector organisations are responsible. We show that it is feasible to identify a sub-set of organisations for which unexplained variation in health indicators is significantly greater relative to their counterparts. We demonstrate that adopting a geographical perspective to analyse the variation in indicators of health at different levels offers a potentially powerful analytical tool to signal where public sector organisations, faced increasingly with many competing demands, should target their policy efforts. This is relevant not only to the English context but also to other countries where responsibilities for health and wellbeing are being devolved to localities and communities.

Castelli, Adriana; Jacobs, Rowena; Goddard, Maria; Smith, Peter C.

2013-01-01

320

Health, policy and geography: insights from a multi-level modelling approach.  

PubMed

Improving the health and wellbeing of citizens ranks highly on the agenda of most governments. Policy action to enhance health and wellbeing can be targeted at a range of geographical levels and in England the focus has tended to shift away from the national level to smaller areas, such as communities and neighbourhoods. Our focus is to identify the potential for targeting policy interventions at the most appropriate geographical levels in order to enhance health and wellbeing. The rationale is that where variations in health and wellbeing indicators are larger, there may be greater potential for policy intervention targeted at that geographical level to have an impact on the outcomes of interest, compared with a strategy of targeting policy at those levels where relative variations are smaller. We use a multi-level regression approach to identify the degree of variation that exists in a set of health indicators at each level, taking account of the geographical hierarchical organisation of public sector organisations. We find that for each indicator, the proportion of total residual variance is greatest at smaller geographical areas. We also explore the variations in health indicators within a hierarchical level, but across the geographical areas for which public sector organisations are responsible. We show that it is feasible to identify a sub-set of organisations for which unexplained variation in health indicators is significantly greater relative to their counterparts. We demonstrate that adopting a geographical perspective to analyse the variation in indicators of health at different levels offers a potentially powerful analytical tool to signal where public sector organisations, faced increasingly with many competing demands, should target their policy efforts. This is relevant not only to the English context but also to other countries where responsibilities for health and wellbeing are being devolved to localities and communities. PMID:23849280

Castelli, Adriana; Jacobs, Rowena; Goddard, Maria; Smith, Peter C

2013-09-01

321

A Multi-Level Model of Information Seeking in the Clinical Domain  

PubMed Central

Objective: Clinicians often have difficulty translating information needs into effective search strategies to find appropriate answers. Information retrieval systems employing an intelligent search agent that generates adaptive search strategies based on human search expertise could be helpful in meeting clinician information needs. A prerequisite for creating such systems is an information seeking model that facilitates the representation of human search expertise. The purpose of developing such a model is to provide guidance to information seeking system development and to shape an empirical research program. Design: The information seeking process was modeled as a complex problem-solving activity. After considering how similarly complex activities had been modeled in other domains, we determined that modeling context-initiated information seeking across multiple problem spaces allows the abstraction of search knowledge into functionally consistent layers. The knowledge layers were identified in the information science literature and validated through our observations of searches performed by health science librarians. Results: A hierarchical multi-level model of context-initiated information seeking is proposed. Each level represents (1) a problem space that is traversed during the online search process, and (2) a distinct layer of knowledge that is required to execute a successful search. Grand strategy determines what information resources will be searched, for what purpose, and in what order. The strategy level represents an overall approach for searching a single resource. Tactics are individual moves made to further a strategy. Operations are mappings of abstract intentions to information resource-specific concrete input. Assessment is the basis of interaction within the strategic hierarchy, influencing the direction of the search. Conclusion: The described multi-level model provides a framework for future research and the foundation for development of an automated information retrieval system that uses an intelligent search agent to bridge clinician information needs and human search expertise.

Hung, Peter W.; Johnson, Stephen B.; Kaufman, David R.; Mendonca, Eneida A.

2008-01-01

322

Small Area and Individual Level Predictors of Physical Activity in Urban Communities: A Multi-Level Study in Stoke on Trent, England  

PubMed Central

Reducing population physical inactivity has been declared a global public health priority. We report a detailed multi-level analysis of small area indices and individual factors as correlates of physical activity in deprived urban areas. Multi-level regression analysis was used to investigate environmental and individual correlates of physical activity. Nine individual factors were retained in the overall model, two related to individual intentions or beliefs, three to access to shops, work or fast food outlets and two to weather; age and gender being the other two. Four area level indices related to: traffic, road casualties, criminal damage and access to green space were important in explaining variation in physical activity.

Cochrane, Thomas; Davey, Rachel C.; Gidlow, Chris; Smith, Graham R.; Fairburn, Jon; Armitage, Christopher J.; Stephansen, Hilde; Speight, Svetlana

2009-01-01

323

Switched Inductor Z-Source Inverter  

Microsoft Academic Search

On the basis of the classical Z-source inverter, this paper presents a developed impedance-type power inverter that is termed the switched inductor (SL) Z-source inverter. To enlarge voltage adjustability, the proposed inverter employs a unique SL impedance network to couple the main circuit and the power source. Compared with the classical Z-source inverter, the proposed inverter increases the voltage boost

Miao Zhu; Kun Yu; Fang Lin Luo

2010-01-01

324

Changes in Vertebral Strain Energy Correlate With Increased Presence of Schmorl's Nodes in Multi-Level Lumbar Disk Degeneration.  

PubMed

Patients with skipped-level disk degeneration (SLDD) were recently reported as having a higher prevalence of Schmorl's nodes than patients with contiguous multi-level disk degeneration (CMDD). Fourteen versions of a nonlinear finite element model of a lumbar spine, representing different patterns of single and multi-level disk degeneration, were simulated under physiological loading. Results show that vertebral strain energy is a possible predictor in the development of Schmorl's nodes. The analysis also shows evidence that the development of Schmorl's nodes may be highly dependent on the location of the degeneration disk, with a higher prevalence at superior levels of the lumbar spine. PMID:24671562

Von Forell, Gregory A; Nelson, Todd G; Samartzis, Dino; Bowden, Anton E

2014-06-01

325

Testing of a single cell cylindrical inverted converter  

NASA Astrophysics Data System (ADS)

A Cylindrical Inverted Converter (CIC), made by Lutch, with the emitter on the outside was tested in a vacuum furnace supplying radiant heat to the emitter outer surface. The collector, coaxial with the emitter, has an integral heat pipe with sodium as the working fluid, which carries the heat dissipated in the collector to a radiating area with a coating of alumina and sub-stoichiometric TiO2. The CIC is a proof-of-principle device which will lead to the development of multi-cell inverted converter assemblies for space solar power systems. The thermionic performance at emitter temperatures of 1800 and 1900 K is presented. .

Desplat, Jean-Louis

2002-01-01

326

A new 7.2kV medium voltage 3-Level-NPC inverter using 6.5kV-IGBTs  

Microsoft Academic Search

The SINAMICS GM150 IGBT, a new 3-level-neutral-point-clamped (3L-NPC) Voltage-Source- Converter (VSC) with series-connected 6.5 kV-IGBTs for industrial Medium Voltage Drives is presented. It covers the output voltage range from 6 kV up to 7.2 kV without the need for a step-up output transformer. The SINAMICS GM150 IGBT is based on the proven basic design of its predecessor SIMOVERT MV while

Christian Dietrich; Swen Gediga; Marc Hiller; Rainer Sommer; Hans Tischmacher

2007-01-01

327

Identifying technique systematics by multi-technique combination at observation level  

NASA Astrophysics Data System (ADS)

The accuracy of the International Terrestrial Reference Frame (ITRF) is limited by the accuracy of the individual techniques contributing to it. Thus identifying technique specific systematics is a crucial step to mitigate technique specific errors and to improve the ITRF solution. The Navigation Support Office (HSO-GN) at ESOC has the capabilities to do a multi-technique combination at the observation level using its software package NAPEOS. We include all satellite geodetic techniques (SLR, DORIS and GPS/GLONASS) in one solution. This allows us to combine the ILRS, IDS and IGS reference frames by using "space-ties". Of course these space-ties are not perfectly known but nevertheless they allow for a rigorous combination of the different reference frames. The combined processing at the observation level allows to directly estimate inter-technique biases, as space-ties. Comparing the combined solution to the individual technique dependent solutions will help to identify technique dependent effects. In our presentation will give an overview of this multi-technique combination approach at observation level. We processed data of the entire year 2011. We included all observation provided by GPS and GLONASS but also LEO satellites (like e.g. Jason-2, SPOT, Cryosat, LAGEOS, Etalon) in one and the same parameter estimation process. We solve not only for integer ambiguities of the GPS satellites but also for those of the Jason-2 satellite, which is also providing GPS phase observations on two frequencies. We will show the benefits of such a rigorous approach and discuss the technique-specific systematics and its impact on the combination.

Otten, Michiel; Flohrer, Claudia; Springer, Tim; Enderle, Werner

2014-05-01

328

Multi-level stressor analysis from the DNA/biochemical level to community levels in an urban stream and integrative health response (IHR) assessments.  

PubMed

The objectives of this study were to identify multi-level stressors at the DNA/biochemical level to the community level in fish in an urban stream and to develop an integrative health response (IHR) model for ecological health diagnosis. A pristine control site (S (c) ) and an impacted site (S (i) ) were selected from among seven pre-screened sites studied over seven years. Various chemical analyses indicated that nutrient enrichment (Nitrogen, Phosphorus) and organic pollution were significantly greater (t > 8.783, p < 0.01) at the S (i) site compared to the S (c) site. Single-cell gel electrophoresis (comet assays) of DNA-level impairment indicated significantly (t = 5.678, p < 0.01) greater tail intensity, expressed as % tail-DNA, at the S (i) site and genotoxic responses were detected in the downstream reach. Ethoxyresorufin-O-deethylase (EROD) assays, as a physiological bioindicator, were 2.8-fold higher (p < 0.05, NK-test after ANOVA) at the S (i) site. Tissue analysis using a necropsy-based health assessment index (NHAI) showed distinct internal organ disorders in three tissues, i.e., liver, kidney, and gill, at the S (i) site. Population-level analysis using the sentinel species Zacco platypus showed that the regression coefficient (b) was 3.012 for the S (i) site and 2.915 for the S (c) site, indicating population skewness in the downstream reach. Community-level health was impaired at the S (i) site based on an index of biological integrity (IBI), and physical habitat modifications were identified by a qualitative habitat evaluation index (QHEI). Overall, the model values for the integrative health response (IHR), developed using the star plot approach, were 3.22 (80.5%) at the S (c) site and 0.74 (18.5%) at the S (i) site, indicating that, overall, ecological health impairments were evident in the urban reach. Our study was based on multi-level approaches using biological organization and the results suggest that there is a pivotal point of linkage between mechanistic understanding and real ecological consequences of environmental stressors. PMID:23043344

Lee, Jae Hoon; Kim, Joon Ha; Oh, Hee-Mock; An, Kwang-Guk

2013-01-01

329

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

330

Threshold inverter quantizer based comparator for artificial silicon retina  

Microsoft Academic Search

This paper deals with the analysis of the comparator circuit for CMOS technology using inverters. The CMOS based cascaded\\u000a comparator, worked on the level of threshold setting of CMOS transistors referred as Threshold Inverter Quantizer, TIQ. TIQ\\u000a has many advantages over the conventional op-amp based comparator and hence can be effectively use for processing the optical\\u000a signals for the application

Yashwant Vitthalrao Chavan; D. K. Mishra

331

Towards Consistent Characterization of Quality and Uncertainty in Multi-sensor Aerosol Level 3 Satellite Data  

NASA Astrophysics Data System (ADS)

Climate models and various environmental monitoring and protection applications have been increasingly relying on satellite measurements. However, the user communities generally prefer not to deal with the complexities and peculiarities of Level 2 (swath) data from the different sensors. Instead, these users seek good quality gridded contiguous (no gaps) satellite data (Level 3), with uncertainties provided for each grid cell. There are various issues in quality and uncertainty associated with Level 3 satellite data, for which other communities (e.g., sea-surface temperature and precipitation) have developed specific solutions, based on their multi-satellite/sensor/year experience. The aerosol community will also benefit from addressing these issues and leveraging the lessons learned from other communities. Our objective is to develop a framework for aerosol data users to systematically characterize, capture, and provision quality and uncertainties in Level 3 satellite data. In particular, we note the semantic differences in quality/bias/uncertainty at the pixel, granule, product, and record levels. We outline various factors contributing to uncertainty or error budget: (1) physical factors (e.g., instrument, retrieval algorithm, aerosol spatial and temporal variability); (2) input errors associated with ancillary data used by the retrieval algorithm; (3) classification errors resulting from erroneous flagging of the data; (4) simulation errors resulting from the geophysical model used for the retrieval; and (5) sampling errors resulting from the averaging within the retrieval footprint. We describe the errors introduced by Level 2 to Level 3 and Level 3 to Level 4 processing steps, including gridding, aggregation, merging and analysis algorithm errors (e.g., representation, bias correction, and gap interpolation). We outline various methods for propagating (1) validation results from just a few points to global data uncertainty and (2) calibration and algorithm uncertainties to Level 3 gridded data. We attempt to capture requirements for quality vs. coverage for the needs of different communities. Finally, we address the question of how to label Level 3 data as validated. The larger community goal is to come up with recommendations for consistent generation of Levels 3 and 4 aerosol products, and consistent characterization of quality and uncertainty.

Leptoukh, G. G.

2010-12-01

332

A multi-level strategy for anticipating future glacier lake formation and associated hazard potentials  

NASA Astrophysics Data System (ADS)

In the course of glacier retreat, new glacier lakes can develop. As such lakes can be a source of natural hazards, strategies for predicting future glacier lake formation are important for an early planning of safety measures. In this article, a multi-level strategy for the identification of overdeepened parts of the glacier beds and, hence, sites with potential future lake formation, is presented. At the first two of the four levels of this strategy, glacier bed overdeepenings are estimated qualitatively and over large regions based on a digital elevation model (DEM) and digital glacier outlines. On level 3, more detailed and laborious models are applied for modeling the glacier bed topography over smaller regions; and on level 4, special situations must be investigated in-situ with detailed measurements such as geophysical soundings. The approaches of the strategy are validated using historical data from Trift Glacier, where a lake formed over the past decade. Scenarios of future glacier lakes are shown for the two test regions Aletsch and Bernina in the Swiss Alps. In the Bernina region, potential future lake outbursts are modeled, using a GIS-based hydrological flow routing model. As shown by a corresponding test, the ASTER GDEM and the SRTM DEM are both suitable to be used within the proposed strategy. Application of this strategy in other mountain regions of the world is therefore possible as well.

Frey, H.; Haeberli, W.; Linsbauer, A.; Huggel, C.; Paul, F.

2010-02-01

333

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.

334

MKEM: a Multi-level Knowledge Emergence Model for mining undiscovered public knowledge  

PubMed Central

Background Since Swanson proposed the Undiscovered Public Knowledge (UPK) model, there have been many approaches to uncover UPK by mining the biomedical literature. These earlier works, however, required substantial manual intervention to reduce the number of possible connections and are mainly applied to disease-effect relation. With the advancement in biomedical science, it has become imperative to extract and combine information from multiple disjoint researches, studies and articles to infer new hypotheses and expand knowledge. Methods We propose MKEM, a Multi-level Knowledge Emergence Model, to discover implicit relationships using Natural Language Processing techniques such as Link Grammar and Ontologies such as Unified Medical Language System (UMLS) MetaMap. The contribution of MKEM is as follows: First, we propose a flexible knowledge emergence model to extract implicit relationships across different levels such as molecular level for gene and protein and Phenomic level for disease and treatment. Second, we employ MetaMap for tagging biological concepts. Third, we provide an empirical and systematic approach to discover novel relationships. Results We applied our system on 5000 abstracts downloaded from PubMed database. We performed the performance evaluation as a gold standard is not yet available. Our system performed with a good precision and recall and we generated 24 hypotheses. Conclusions Our experiments show that MKEM is a powerful tool to discover hidden relationships residing in extracted entities that were represented by our Substance-Effect-Process-Disease-Body Part (SEPDB) model.

2010-01-01

335

Multi-level polysilicon surface-micromachining technology: Applications and issues  

SciTech Connect

Polysilicon surface micromachining is a technology for manufacturing Micro-Electro-Mechanical Systems (MEMS) which has, as its basis, the manufacturing methods and tool sets used to manufacture the integrated electronic circuit. This paper describes a three-level mechanical-polysilicon surface-micromachining technology and includes a discussion of the advantages of this level of process complexity along with issues which affect device fabrication and performance. Historically, the primary obstacles to multi-level polysilicon fabrication were related to the severe wafer topography generated by the repetition of film depositions and etching. The introduction of Chemical Mechanical Polishing (CMP) to surface micromachining has largely removed these issues and opened significant avenues for device complexity. Several examples of three-level devices with the benefits of CMP are presented. Of primary hindrance to the widespread use of polysilicon surface micromachining, and in particular microactuation mechanisms, are issues related to the device surfaces. The closing discussion examines the potential of several latter and post-fabrication processes to circumvent or to directly alleviate the surface problems.

Sniegowski, J.J.

1996-08-01

336

The learner's perspective in GP teaching practices with multi-level learners: a qualitative study  

PubMed Central

Background Medical students, junior hospital doctors on rotation and general practice (GP) registrars are undertaking their training in clinical general practices in increasing numbers in Australia. Some practices have four levels of learner. This study aimed to explore how multi-level teaching (also called vertical integration of GP education and training) is occurring in clinical general practice and the impact of such teaching on the learner. Methods A qualitative research methodology was used with face-to-face, semi-structured interviews of medical students, junior hospital doctors, GP registrars and GP teachers in eight training practices in the region that taught all levels of learners. Interviews were audio-recorded and transcribed. Qualitative analysis was conducted using thematic analysis techniques aided by the use of the software package N-Vivo 9. Primary themes were identified and categorised by the co-investigators. Results 52 interviews were completed and analysed. Themes were identified relating to both the practice learning environment and teaching methods used. A practice environment where there is a strong teaching culture, enjoyment of learning, and flexible learning methods, as well as learning spaces and organised teaching arrangements, all contribute to positive learning from a learners’ perspective. Learners identified a number of innovative teaching methods and viewed them as positive. These included multi-level learner group tutorials in the practice, being taught by a team of teachers, including GP registrars and other health professionals, and access to a supernumerary GP supervisor (also termed “GP consultant teacher”). Other teaching methods that were viewed positively were parallel consulting, informal learning and rural hospital context integrated learning. Conclusions Vertical integration of GP education and training generally impacted positively on all levels of learner. This research has provided further evidence about the learning culture, structures and teaching processes that have a positive impact on learners in the clinical general practice setting where there are multiple levels of learners. It has also identified some innovative teaching methods that will need further examination. The findings reinforce the importance of the environment for learning and learner centred approaches and will be important for training organisations developing vertically integrated practices and in their training of GP teachers.

2014-01-01

337

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

338

A multi-level pore-water sampler for permeable sediments  

USGS Publications Warehouse

The construction and operation of a multi-level piezometer (multisampler) designed to collect pore water from permeable sediments up to 230 cm below the sediment-water interface is described. Multisamplers are constructed from 1 1/2 inch schedule 80 PVC pipe. One-quarter-inch flexible PVC tubing leads from eight ports at variable depths to a 1 1/2 inch tee fitting at the top of the PVC pipe. Multisamplers are driven into the sediments using standard fence-post drivers. Water is pumped from the PVC tubing with a peristaltic pump. Field tests in Banana River Lagoon, Florida, demonstrate the utility of multisamplers. These tests include collection of multiple samples from the permeable sediments and reveal mixing between shallow pore water and overlying lagoon water.

Martin, J. B.; Hartl, K. M.; Corbett, D. R.; Swarzenski, P. W.; Cable, J. E.

2003-01-01

339

Information theoretic partitioning and confidence based weight assignment for multi-classifier decision level fusion in hyperspectral target recognition applications  

Microsoft Academic Search

There is a growing interest in using multiple sources for automatic target recognition (ATR) applications. One approach is to take multiple, independent observations of a phenomenon and perform a feature level or a decision level fusion for ATR. This paper proposes a method to utilize these types of multi-source fusion techniques to exploit hyperspectral data when only a small number

S. Prasad; L. M. Bruce

2007-01-01

340

Retrieval of Surface Directional Reflectance and Hemispherical Albedo Using Multi-angle Measurements, I. Ground Level Observations  

NASA Technical Reports Server (NTRS)

Knowledge of the directional reflectance properties of natural surfaces such as soils and vegetation canopies is essential for classification studies and canopy model inversions. Atmospheric correction schemes, using various levels of approximation, are described to retrieve surface bidirectional reflectance factors (BRFs) and directional-hemispherical reflectances (albedos) from multi-angle radiance measurements taken at ground level.

Martonchik, J. V.

1993-01-01

341

Multi-level aspects of social cohesion of secondary schools and pupils' feelings of safety.  

PubMed

BACKGROUND. School safety and corresponding feelings of both pupils and school staff are beginning to receive more and more attention. The social cohesion characteristics of a school may be useful in promoting feelings of safety, particularly in pupils. AIMS. To conceptualize theoretically, and check empirically a two-level model of social cohesion between and within schools, in order to explain a pupil's feelings of safety at school. SAMPLES. Data were collected aided by a national Dutch survey in secondary education carried out via the Internet. In 2008, digital questionnaires were completed by about 78,800 pupils, 6,200 teachers and educational support staff, and 600 school managers. METHODS. Data were checked for reliability and representativity. Social cohesion was indicated by self-reported measures of individual pupils and by aggregating scale and item scores of school managers, teachers, and other support staff within schools. Multi-level analysis using individual pupil data and school-level data was performed using MLwiN. RESULTS. A pupil's age, educational attainment level, experience of mild physical violence, prosocial rules of conduct and joint control of these rules, and school measures against playing truant, show positive influences on a pupil's feelings of safety at school. Negative influences are exerted by not feeling most at home in The Netherlands, peers taking drugs and weapons into school, and by experiencing social violence, severe physical violence, and sexual violence. Negative school effects exist simultaneously in severe physical violence experienced by teachers and other staff, and in curriculum differentiation applied by teachers and other staff; a positive school effect is school size. Some interaction effects between pupil and school-level variables were explored. CONCLUSIONS. The variance at school level is relatively low compared with the variance at pupil level. However, a much higher percentage of variance at school level than at pupil level is explained with respect to the pupils' feelings of safety at school. The resulting two-level model also reflects the streaming of pupils in Dutch secondary schools. To improve school safety, the national results emphasize the need to enhance prosocial behaviour rules and to enhance the shared control of these rules between teachers and pupils. They also emphasize the need for the school to take measures that prevent truancy and redefine curriculum differentiation procedures. National educational policy and research can combine efforts to assist schools in developing reliable and valid procedures to increase effectively safety in and around schools. PMID:21770911

Mooij, Ton; Smeets, Ed; de Wit, Wouter

2011-09-01

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

Evaluation of Recent Residential Inverters.  

National Technical Information Service (NTIS)

Seven residential utility-interactive inverters for photovoltaic power systems have been evaluated at MIT Laboratory and at the Northeast Residential Experiment Station (NE RES). Two, a Windworks Gemini and an Abacus Sunverter, have been reported on previ...

B. E. Nichols

1982-01-01

344

On the utility of the multi-level algorithm for the solution of nearly completely decomposable Markov chains  

NASA Technical Reports Server (NTRS)

Recently the Multi-Level algorithm was introduced as a general purpose solver for the solution of steady state Markov chains. In this paper, we consider the performance of the Multi-Level algorithm for solving Nearly Completely Decomposable (NCD) Markov chains, for which special-purpose iteractive aggregation/disaggregation algorithms such as the Koury-McAllister-Stewart (KMS) method have been developed that can exploit the decomposability of the the Markov chain. We present experimental results indicating that the general-purpose Multi-Level algorithm is competitive, and can be significantly faster than the special-purpose KMS algorithm when Gauss-Seidel and Gaussian Elimination are used for solving the individual blocks.

Leutenegger, Scott T.; Horton, Graham

1994-01-01

345

Comparison of Traditional Inverters and Z Source Inverter for Fuel Cell Vehicles  

Microsoft Academic Search

In this paper, three different inverters: conventional pulsewidth modulation (PWM) inverter, dc-dc boosted PWM inverter, and Z-source inverter were investigated and compared for fuel cell vehicle application. Total switching device power, passive components requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power, requirement of

Miaosen Shen; Alan Joseph; Jin Wang; Fang Z. Peng; Donald J. Adams

2007-01-01

346

iqr: a tool for the construction of multi-level simulations of brain and behaviour.  

PubMed

The brain is the most complex system we know of. Despite the wealth of data available in neuroscience, our understanding of this system is still very limited. Here we argue that an essential component in our arsenal of methods to advance our understanding of the brain is the construction of artificial brain-like systems. In this way we can encompass the multi-level organisation of the brain and its role in the context of the complete embodied real-world and real-time perceiving and behaving system. Hence, on the one hand, we must be able to develop and validate theories of brains as closing the loop between perception and action, and on the other hand as interacting with the real world. Evidence is growing that one of the sources of the computational power of neuronal systems lies in the massive and specific connectivity, rather than the complexity of single elements. To meet these challenges-multiple levels of organisation, sophisticated connectivity, and the interaction of neuronal models with the real-world-we have developed a multi-level neuronal simulation environment, iqr. This framework deals with these requirements by directly transforming them into the core elements of the simulation environment itself. iqr provides a means to design complex neuronal models graphically, and to visualise and analyse their properties on-line. In iqr connectivity is defined in a flexible, yet compact way, and simulations run at a high speed, which allows the control of real-world devices-robots in the broader sense-in real-time. The architecture of iqr is modular, providing the possibility to write new neuron, and synapse types, and custom interfaces to other hardware systems. The code of iqr is publicly accessible under the GNU General Public License (GPL). iqr has been in use since 1996 and has been the core tool for a large number of studies ranging from detailed models of neuronal systems like the cerebral cortex, and the cerebellum, to robot based models of perception, cognition and action to large-scale real-world systems. In addition, iqr has been widely used over many years to introduce students to neuronal simulation and neuromorphic control. In this paper we outline the conceptual and methodological background of iqr and its design philosophy. Thereafter we present iqr's main features and computational properties. Finally, we describe a number of projects using iqr, singling out how iqr is used for building a "synthetic insect". PMID:20502987

Bernardet, Ulysses; Verschure, Paul F M J

2010-06-01

347

Recent developments in wafer-level fabrication of micro-optical multi-aperture imaging systems  

NASA Astrophysics Data System (ADS)

Micro-optical systems, that utilize multiple channels for imaging instead of a single one, are frequently discussed for ultra-compact applications such as digital cameras. The strategy of their fabrication differs due to different concepts of image formation. Illustrated by recently implemented systems for multi-aperture imaging, typical steps of wafer-level fabrication are discussed in detail. In turn, the made progress may allow for additional degrees of freedom in optical design. Pressing ahead with very short overall lengths and multiple diaphragm array layers, results in the use of extremely thin glass substrates down to 100 microns in thickness. The desire for a wide field of view for imaging has led to chirped arrays of microlenses and diaphragms. Focusing on imaging quality, aberrations were corrected by introducing toroidal lenslets and elliptical apertures. Such lenslets had been generated by thermal reflow of lithographic patterned photoresist and subsequent molding. Where useful, the system's performance can be further increased by applying aspheric microlenses from reactive ion etching (RIE) transfer or by achromatic doublets from superimposing two moldings with different polymers. Multiple diaphragm arrays prevent channel crosstalk. But using simple metal layers may lead to multiple reflections and an increased appearance of ghost images. A way out are low reflecting black matrix polymers that can be directly patterned by lithography. But in case of environmental stability and high resolution, organic coatings should be replaced by patterned metal coatings that exhibit matched antireflective layers like the prominent black chromium. The mentioned components give an insight into the fabrication process of multi-aperture imaging systems. Finally, the competence in each step decides on the overall image quality.

Leitel, R.; Dannberg, P.; Brückner, A.; Bräuer, A.

2011-09-01

348

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

349

Principal's Leadership as a Critical Factor for School Performance: Evidence from Multi?Levels of Primary Schools  

Microsoft Academic Search

This study aims to investigate how principal's leadership is related to school performance in terms of multi?level indicators such as school's organizational characteristics, teachers’ group?level and individual?level performances, and students’ performances. In the study, strong leadership represents that a principal can be supportive and foster participation for teachers, can develop clear goals and policies and hold people accountable for results,

Yin Cheong Cheng

1994-01-01

350

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, 2010 CFR

...Seating Area of a Multi-Level Car Complying With Window Location Requirements-çç 238.113 and 238.114 2A Figure 2A to Subpart B of Part 238 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL...

2009-10-01

351

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, 2010 CFR

...Seating Area of a Multi-Level Car Complying With Window Location Requirements-çç 238.113 and 238.114 2B Figure 2B to Subpart B of Part 238 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL...

2010-10-01

352

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, 2010 CFR

...Seating Area of a Multi-Level Car Complying With Window Location Requirements-çç 238.113 and 238.114 2B Figure 2B to Subpart B of Part 238 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL...

2009-10-01

353

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, 2010 CFR

...Seating Area of a Multi-Level Car Complying With Window Location Requirements-çç 238.113 and 238.114 2A Figure 2A to Subpart B of Part 238 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL...

2010-10-01

354

A spectral-Lagrangian Boltzmann solver for a multi-energy level gas  

NASA Astrophysics Data System (ADS)

In this paper a spectral-Lagrangian method is proposed for the full, non-linear Boltzmann equation for a multi-energy level gas typical of a hypersonic re-entry flow. Internal energy levels are treated as separate species and inelastic collisions (leading to internal energy excitation and relaxation) are accounted for. The formulation developed can also be used for the case of a gas mixture made of monatomic gases without internal energy (where only elastic collisions occur). The advantage of the spectral-Lagrangian method lies in the generality of the algorithm in use for the evaluation of the elastic and inelastic collision operators, as well as the conservation of mass, momentum and energy during collisions. The latter is realized through the solution of constrained optimization problems. The computational procedure is based on the Fourier transform of the partial elastic and inelastic collision operators and exploits the fact that these can be written as weighted convolutions in Fourier space with no restriction on the cross-section model. The feasibility of the proposed approach is demonstrated through numerical examples for both space homogeneous and in-homogeneous problems. Computational results are compared with those obtained by means of the DSMC method in order to assess the accuracy of the proposed spectral-Lagrangian method.

Munafò, Alessandro; Haack, Jeffrey R.; Gamba, Irene M.; Magin, Thierry E.

2014-05-01

355

Participatory System Science: Multi-Level Comprehension Through a Game-like Process  

NASA Astrophysics Data System (ADS)

Participatory System Science: Multi-Level Comprehension Through a Game-like Process We built a time-series game that permits the player to make water management decisions concerning the Skagit River (north-central Washington state) every five years for 60 years. This work was inspired by the integrative efforts of the Skagit Climate Science Consortium and the Climate Impacts Group at the University of Washington. Our principle guiding concepts have been - Construct a reasonable system description with -- wherever possible -- Events / Consequences rendered both visually and in terms of financial impact. - Base the system description on peer reviewed publications - Emphasize both connection and absence of connection between player Actions and subsequent Consequences in the catchment basin. Player choices center around dam flow levels and steps to mitigate negative impacts of sediment transport into the lower (populated) reaches of the Skagit River and into Puget Sound (levees, new dams, estuary restoration, etcetera). With this work we hope to explore scientific results in public awareness by engaging the game Player as a problem solver.

Fatland, D. R.; Kuntz, L.

2012-12-01

356

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

357

Personality, adrenal steroid hormones, and resilience in maltreated children: A multi-level perspective  

PubMed Central

In this multi-level investigation, resilience in adaptive functioning among maltreated and nonmaltreated low-income children (N = 677) was examined in relation to the regulation of two stress-responsive adrenal steroid hormones, cortisol and dehydroepiandosterone (DHEA), as well as the personality constructs of ego resiliency and ego control. Maltreatment status was not related to differences in average levels of morning or afternoon cortisol or DHEA. However, lower morning cortisol was related to higher resilient functioning, but only in nonmaltreated children. In contrast, among physically abused children, high morning cortisol was related to higher resilient functioning. Morning and afternoon DHEA was negatively related to resilient functioning. Although diurnal change in cortisol was not related to resilience, for DHEA, maltreated children with high resilience showed an atypical rise in DHEA from morning to afternoon. Morning and afternoon cortisol/DHEA ratios were positively related to resilient functioning, but did not interact with maltreatment status. Ego resiliency and ego control strongly differentiated maltreated and nonmaltreated children, and the personality variables were substantially predictive of resilience. When considered together, demonstrated effects of personality, cortisol, and DHEA maintained independent contributions in predicting resilience among high-risk youth.

Cicchetti, Dante; Rogosch, Fred A.

2012-01-01

358

A Multi-Fractal approach to soil thin sections in gray levels.  

NASA Astrophysics Data System (ADS)

In the environment, as it is complex flows where Reynold number is quite high due to non-linear interactions in flows, several scales are developed. This type of hierarchy is detected in velocities as well as in the structure of scalar fields, as temperatures, tracer concentrations, density, etc. In these cases is interesting to relate in some way the geometrical o topological characteristics observed in flow images with their physical properties and dynamics. In the last decades many scientist has been applying fractal analysis to these types of images extracting several fractal dimensions for different intensity intervals. This type of analysis is what we call Multi-Fractal. We are going to apply the same method to soil image thin sections in gray levels. A first step will be to select which intervals of gray levels should be choosing in this new context and with which criteria. The next point will be which range of scales should be selected to extract the fractal dimension applying the box-counting method. A discussion about the interpretations and implications of the results will be show.

Lozano, I. S.; Nuñez, A. M.; Benito, R. M.; Tarquis, A. M.

2010-05-01

359

RAETRAD model extensions for radon entry into multi-level buildings with basements or crawl spaces  

SciTech Connect

The RAETRAD model was generalized to characterize radon generation and movement from soils and building materials into multi-level buildings with basements or crawl spaces. With the generalization, the model retains its original simplicity and ease of use. The model calculates radon entry rates that are consistent with measurements published for basement test structures at Colorado State University, confirming approximately equal contributions from diffusion and pressure-driven air flow at indoor-outdoor air pressure differences of {Delta}P{sub i-o} = -3.5 Pa. About one-fourth of the diffusive radon entry comes from concrete slabs and three-fourths comes from the surrounding soils. Calculated radon entry rates with and without a barrier over floor-wall shrinkage cracks generally agree with Colorado State University measurements when a sustained pressure of {Delta}P{sub i-o} = -2 Pa is used to represent calm wind (<1 m, s{sup -1}) conditions. Calculated radon distributions in a 2-level house also are consistent with published measurements and equations.

Nielson, K.K.; Rogers, V.C.; Rogers, V.; Holt, R.B. [Rogers and Associates Engineering Corp., Salt Lake City, UT (United States)

1997-10-01

360

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 {open_quotes}realities{close_quotes} lead to identical images, a single image cannot reveal the particular reality which was the truth. MSI techniques attempt to resolve some of these ambiguities by appropriately coupling complementary images to eliminate possible inverse mappings. What constitutes the best MSI technique is dependent on the given application domain, available sensors, and task requirements. 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) {open_quotes}detail enhancement,{close_quotes} wherein the relative information content of the original images is less rich than the desired representation; (2) {open_quotes}data enhancement,{close_quotes} wherein the MSI techniques are concerned with improving the accuracy of the data rather than either increasing or decreasing the level of detail; and (3) {open_quotes}conceptual enhancement,{close_quotes} 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.

Baker, J.E.

1994-09-01

361

Modeling fuzzy multi-period production planning and sourcing problem with credibility service levels  

NASA Astrophysics Data System (ADS)

A great deal of research has been done on production planning and sourcing problems, most of which concern deterministic or stochastic demand and cost situations and single period systems. In this paper, we consider a new class of multi-period production planning and sourcing problem with credibility service levels, in which a manufacturer has a number of plants and subcontractors and has to meet the product demand according to the credibility service levels set by its customers. In the proposed problem, demands and costs are uncertain and assumed to be fuzzy variables with known possibility distributions. The objective of the problem is to minimize the total expected cost, including the expected value of the sum of the inventory holding and production cost in the planning horizon. Because the proposed problem is too complex to apply conventional optimization algorithms, we suggest an approximation approach (AA) to evaluate the objective function. After that, two algorithms are designed to solve the proposed production planning problem. The first is a PSO algorithm combining the AA, and the second is a hybrid PSO algorithm integrating the AA, neural network (NN) and PSO. Finally, one numerical example is provided to compare the effectiveness of the proposed two algorithms.

Lan, Yan-Fei; Liu, Yan-Kui; Sun, Gao-Ji

2009-09-01

362

Who is Subjected to Coercive Measures as a Psychiatric Inpatient? A Multi-Level Analysis  

PubMed Central

Background: For a reduction in the use of coercive interventions it will be necessary to identify patients at risk. The aim of this study was to explore the impact of basic patient characteristics at admission, history within 24 hours before admission, and living conditions on the risk of experiencing coercive measures, controlling for ward characteristics in a multi-level approach. Methods: Patient characteristics of 3389 patients (1920 women) who had received inpatient treatment in 2007, data relating to coercive measures, and ward characteristics were extracted from the clinical basic documentation. Results: Patients with aggressive behaviour in the 24 hours prior to admission had a three times higher risk of coercive measures compared to non-aggressive patients. Severity of illness increased the risk of coercion markedly. With each level of severity, the risk of coercion was doubled. Voluntariness of stay appeared to be the best protective factor against coercive measures. If a patient stayed voluntarily, this reduced the risk of coercion by more than two thirds. No impact was found for living conditions. Conclusions: To identify patients at risk, it is most important to intensively monitor patients with aggressive behaviour prior to admission and patients with a greater severity of psychopathological symptoms.

Flammer, E; Steinert, T; Eisele, F; Bergk, J; Uhlmann, C

2013-01-01

363

On The Invertibility Of Invisible Watermarking Techniques  

Microsoft Academic Search

In this paper we address the invertibility of invisible watermarking schemes for resolving rightful ownerships, and present attacks which can cause confusion to rightful claims. We shall show that non-invertibility is a necessary but not sufficient condition in resolving ownership disputes. We then define quasi-invertible watermarking schemes, and, present analysis that links invertibility and quasi-invertibility to some classes of watermarking

Scott Craver

1997-01-01

364

Multi-Level Building Reconstruction for Automatic Enhancement of High Resolution Dsms  

NASA Astrophysics Data System (ADS)

In this article a multi-level approach is proposed for reconstruction-based improvement of high resolution Digital Surface Models (DSMs). The concept of Levels of Detail (LOD) defined by CityGML standard has been considered as basis for abstraction levels of building roof structures. Here, the LOD1 and LOD2 which are related to prismatic and parametric roof shapes are reconstructed. Besides proposing a new approach for automatic LOD1 and LOD2 generation from high resolution DSMs, the algorithm contains two generalization levels namely horizontal and vertical. Both generalization levels are applied to prismatic model of buildings. The horizontal generalization allows controlling the approximation level of building footprints which is similar to cartographic generalization concept of the urban maps. In vertical generalization, the prismatic model is formed using an individual building height and continuous to included all flat structures locating in different height levels. The concept of LOD1 generation is based on approximation of the building footprints into rectangular or non-rectangular polygons. For a rectangular building containing one main orientation a method based on Minimum Bounding Rectangle (MBR) in employed. In contrast, a Combined Minimum Bounding Rectangle (CMBR) approach is proposed for regularization of non-rectilinear polygons, i.e. buildings without perpendicular edge directions. Both MBRand CMBR-based approaches are iteratively employed on building segments to reduce the original building footprints to a minimum number of nodes with maximum similarity to original shapes. A model driven approach based on the analysis of the 3D points of DSMs in a 2D projection plane is proposed for LOD2 generation. Accordingly, a building block is divided into smaller parts according to the direction and number of existing ridge lines. The 3D model is derived for each building part and finally, a complete parametric model is formed by merging all the 3D models of the individual parts and adjusting the nodes after the merging step. In order to provide an enhanced DSM, a surface model is provided for each building by interpolation of the internal points of the generated models. All interpolated models are situated on a Digital Terrain Model (DTM) of corresponding area to shape the enhanced DSM. Proposed DSM enhancement approach has been tested on a dataset from Munich central area. The original DSM is created using robust stereo matching of Worldview-2 stereo images. A quantitative assessment of the new DSM by comparing the heights of the ridges and eaves shows a standard deviation of better than 50cm.

Arefi, H.; Reinartz, P.

2012-07-01

365

Multi-level tree analysis of pulmonary artery/vein trees in non-contrast CT images  

NASA Astrophysics Data System (ADS)

Diseases like pulmonary embolism and pulmonary hypertension are associated with vascular dystrophy. Identifying such pulmonary artery/vein (A/V) tree dystrophy in terms of quantitative measures via CT imaging significantly facilitates early detection of disease or a treatment monitoring process. A tree structure, consisting of nodes and connected arcs, linked to the volumetric representation allows multi-level geometric and volumetric analysis of A/V trees. Here, a new theory and method is presented to generate multi-level A/V tree representation of volumetric data and to compute quantitative measures of A/V tree geometry and topology at various tree hierarchies. The new method is primarily designed on arc skeleton computation followed by a tree construction based topologic and geometric analysis of the skeleton. The method starts with a volumetric A/V representation as input and generates its topologic and multi-level volumetric tree representations long with different multi-level morphometric measures. A new recursive merging and pruning algorithms are introduced to detect bad junctions and noisy branches often associated with digital geometric and topologic analysis. Also, a new notion of shortest axial path is introduced to improve the skeletal arc joining two junctions. The accuracy of the multi-level tree analysis algorithm has been evaluated using computer generated phantoms and pulmonary CT images of a pig vessel cast phantom while the reproducibility of method is evaluated using multi-user A/V separation of in vivo contrast-enhanced CT images of a pig lung at different respiratory volumes.

Gao, Zhiyun; Grout, Randall W.; Hoffman, Eric A.; Saha, Punam K.

2012-02-01

366

New Types of Sea-Going MultiHull Ships with Superior Comfort Level and Safety  

Microsoft Academic Search

Multi-hull vessels of various types have inherently larger deck area, higher safety, and better seaworthiness than conventional monohulls. Multi-hulls are very well suited for passenger transportation and are a dominant force on the fast ferry market. Several advanced concepts of multi- hulls with small water-plane area hulls are considered in this paper. New relatively small ship types could expand fast

Victor Dubrovsky; Konstantin Matveev

367

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

368

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

369

Target recognition for the two color IR imaging system based on the multi-classifiers decision level fusion  

Microsoft Academic Search

Aim at the problem of Automatic Target Recognition (ATR) for the two color IR imaging system, presented a method for the IR dual band image target recognition based on multi- classifiers decision level fusion. This method firstly inputted all kinds of feature vectors of the target image into these relevant classifiers respectively to get the likelihood ratio of the target

Li Qiuhua; Lei Bin; Du Yi

2011-01-01

370

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

371

Application of digital image processing technology in the data restoring process of multi-level digital holographic storage  

Microsoft Academic Search

Firstly, this paper introduces the concept of multi-level digital holographic storage. Then, application of digital image processing technology is brought forward in the data restoring process of digital holographic storage. Information in the reconstructed digital images collected from CCD camera is enhanced through digital image processing technology and threshold decision is gone on so as to decreasing bit error ratio

Lihua Fang; Yonqing Gong; Liguang Fang; Qing Wang

2006-01-01

372

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

373

Putting Poverty in Political Context: A MultiLevel Analysis of Adult Poverty across 18 Affluent Democracies  

Microsoft Academic Search

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 individual characteristics and structural context. For each standard deviation increase

David Brady; Andrew S. Fullerton; Jennifer Moren Cross

2009-01-01

374

Considering a multi-level approach to understanding maintenance of global coherence in adults with aphasia.  

PubMed

BACKGROUND: Discourse is a naturally occurring, dynamic form of communication. Coherence is one aspect of discourse and is a reflection of the listener's ability to interpret the overall meaning conveyed by the speaker. Adults with aphasia may present with impaired maintenance of global coherence, which, in turn, may contribute to their difficulties in overall communicative competence. AIMS: The aim of the study was to determine if microlinguistic processes contribute to maintenance of global coherence in adults with and without aphasia. METHOD AND PROCEDURES: Participants included 15 adults with aphasia (PWA) and 15 healthy controls (HC). Study participants told stories conveyed in wordless picture books. The discourse samples were transcribed and then analyzed for percent of information units produced, lexical diversity, syntactic complexity, and maintenance of global coherence. OUTCOMES AND RESULTS: Several linear regression models were carried out to investigate the relationship among the microlinguistic and macrolinguistic measures. For the control group, percent of information units conveyed was a significant predictor of maintenance of global coherence for stories told. For the aphasia group, percent of information units conveyed and lexical diversity were significant predictors of maintenance of global coherence for stories told. CONCLUSIONS: Results indicated that microlinguistic processes contribute to the maintenance of global coherence in stories told by adults with aphasia. These findings have important clinical implications for using a multi-level discourse model for analyzing discourse ability in adults with aphasia and measuring individual response to treatment. PMID:22962509

Wright, Heather Harris; Capilouto, Gilson J

2012-01-01

375

Opportunities in multi dimensional trace metal imaging: Taking copper associated disease research to the next level  

PubMed Central

Copper plays an important role in numerous biological processes across all living systems predominantly because of its versatile redox behavior. Cellular copper homeostasis is tightly regulated and disturbances lead to severe disorders such as Wilson disease (WD) and Menkes disease. Age related changes of copper metabolism have been implicated in other neurodegenerative disorders such as Alzheimer’s disease (AD). The role of copper in these diseases has been topic of mostly bioinorganic research efforts for more than a decade, metal-protein interactions have been characterized and cellular copper pathways have been described. Despite these efforts, crucial aspects of how copper is associated with AD, for example, is still only poorly understood. To take metal related disease research to the next level, emerging multi dimensional imaging techniques are now revealing the copper metallome as the basis to better understand disease mechanisms. This review will describe how recent advances in X-ray fluorescence microscopy and fluorescent copper probes have started to contribute to this field specifically WD and AD. It furthermore provides an overview of current developments and future applications in X-ray microscopic methodologies.

Vogt, Stefan; Ralle, Martina

2012-01-01

376

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

377

Considering a multi-level approach to understanding maintenance of global coherence in adults with aphasia  

PubMed Central

Background Discourse is a naturally occurring, dynamic form of communication. Coherence is one aspect of discourse and is a reflection of the listener's ability to interpret the overall meaning conveyed by the speaker. Adults with aphasia may present with impaired maintenance of global coherence, which, in turn, may contribute to their difficulties in overall communicative competence. Aims The aim of the study was to determine if microlinguistic processes contribute to maintenance of global coherence in adults with and without aphasia. Method and Procedures Participants included 15 adults with aphasia (PWA) and 15 healthy controls (HC). Study participants told stories conveyed in wordless picture books. The discourse samples were transcribed and then analyzed for percent of information units produced, lexical diversity, syntactic complexity, and maintenance of global coherence. Outcomes and Results Several linear regression models were carried out to investigate the relationship among the microlinguistic and macrolinguistic measures. For the control group, percent of information units conveyed was a significant predictor of maintenance of global coherence for stories told. For the aphasia group, percent of information units conveyed and lexical diversity were significant predictors of maintenance of global coherence for stories told. Conclusions Results indicated that microlinguistic processes contribute to the maintenance of global coherence in stories told by adults with aphasia. These findings have important clinical implications for using a multi-level discourse model for analyzing discourse ability in adults with aphasia and measuring individual response to treatment.

Wright, Heather Harris; Capilouto, Gilson J.

2012-01-01

378

CMT: A Constrained Multi-Level Thresholding Approach for ChIP-Seq Data Analysis  

PubMed Central

Genome-wide profiling of DNA-binding proteins using ChIP-Seq has emerged as an alternative to ChIP-chip methods. ChIP-Seq technology offers many advantages over ChIP-chip arrays, including but not limited to less noise, higher resolution, and more coverage. Several algorithms have been developed to take advantage of these abilities and find enriched regions by analyzing ChIP-Seq data. However, the complexity of analyzing various patterns of ChIP-Seq signals still needs the development of new algorithms. Most current algorithms use various heuristics to detect regions accurately. However, despite how many formulations are available, it is still difficult to accurately determine individual peaks corresponding to each binding event. We developed Constrained Multi-level Thresholding (CMT), an algorithm used to detect enriched regions on ChIP-Seq data. CMT employs a constraint-based module that can target regions within a specific range. We show that CMT has higher accuracy in detecting enriched regions (peaks) by objectively assessing its performance relative to other previously proposed peak finders. This is shown by testing three algorithms on the well-known FoxA1 Data set, four transcription factors (with a total of six antibodies) for Drosophila melanogaster and the H3K4ac antibody dataset.

Rezaeian, Iman; Rueda, Luis

2014-01-01

379

Multi-level Dynamical Systems: Connecting the Ruelle Response Theory and the Mori-Zwanzig Approach  

NASA Astrophysics Data System (ADS)

In this paper we consider the problem of disentangling multi-level systems by connecting the seemingly unrelated approaches of the Mori-Zwanzig projection operator technique and of the Ruelle response theory, for which we propose a new derivation. In a previous paper we have shown that by using the Ruelle response theory it is possible to construct a surrogate dynamics for the slow variables only such that the expectation value of any observable agrees, up to second order, to its expectation evaluated on the full dynamics, where both slow and fast variables are involved. We prove here, using a Dyson expansion, that such surrogate dynamics agree up to second order to the effective dynamics one can derive by expanding perturbatively the Mori-Zwanzing projection operator, which creates, instead, an accurate representation of the trajectories of the slow variables. In the case of e.g. geophysical fluid dynamics, this implies that the parametrizations of unresolved processes suited for prediction (numerical weather forecast) and those suited for the representation of long term statistical properties (climate) are closely related, if one takes into account, in addition to the widely adopted stochastic forcing, the usually neglected memory effects. This bears relevance for the current trend of aiming at seamless prediction.

Wouters, J.; Lucarini, V.

2012-12-01

380

A dedicated database system for handling multi-level data in systems biology  

PubMed Central

Background Advances in high-throughput technologies have enabled extensive generation of multi-level omics data. These data are crucial for systems biology research, though they are complex, heterogeneous, highly dynamic, incomplete and distributed among public databases. This leads to difficulties in data accessibility and often results in errors when data are merged and integrated from varied resources. Therefore, integration and management of systems biological data remain very challenging. Methods To overcome this, we designed and developed a dedicated database system that can serve and solve the vital issues in data management and hereby facilitate data integration, modeling and analysis in systems biology within a sole database. In addition, a yeast data repository was implemented as an integrated database environment which is operated by the database system. Two applications were implemented to demonstrate extensibility and utilization of the system. Both illustrate how the user can access the database via the web query function and implemented scripts. These scripts are specific for two sample cases: 1) Detecting the pheromone pathway in protein interaction networks; and 2) Finding metabolic reactions regulated by Snf1 kinase. Results and conclusion In this study we present the design of database system which offers an extensible environment to efficiently capture the majority of biological entities and relations encountered in systems biology. Critical functions and control processes were designed and implemented to ensure consistent, efficient, secure and reliable transactions. The two sample cases on the yeast integrated data clearly demonstrate the value of a sole database environment for systems biology research.

2014-01-01

381

Semantic segmentation based on multi-stage region-level clustering  

NASA Astrophysics Data System (ADS)

In the field of remote-sensed image segmentation, it is very important to obtain semantic results. However, in high resolution remote sensed images, different complex patterns always have components with the same spectrum, which makes it rather difficult to extract such patterns only through traditional clustering methods. In this paper, a novel multi-stage region-level clustering method is proposed to solve this problem. Firstly, the initial oversegmentation is obtained by using the Mean Shift algorithm, based on which a region adjacent graph (RAG) is built; Then, FCM is employed to get the spectral-based segmentation result; After that, the context clues for each region is calculated according to the label and size of neighboring regions, followed by the second FCM clustering on each set of regions with the same label to distinct regions with the same spectrum but belongs to different objects; Rearranging all of these clustering results to form the finial processing unit, this algorithm goes a step further to calculate more accurate context clues, and use the third FCM to obtain the final segmentation result. Experiments on the high resolution remote-sensed images have shown the superiority to the competitions.

Liu, Guoying; Zhou, Hongyu

2013-10-01

382

Planar wire array performance scaling at multi-MA levels on the Saturn generator.  

SciTech Connect

A series of twelve shots were performed on the Saturn generator in order to conduct an initial evaluation of the planar wire array z-pinch concept at multi-MA current levels. Planar wire arrays, in which all wires lie in a single plane, could offer advantages over standard cylindrical wire arrays for driving hohlraums for inertial confinement fusion studies as the surface area of the electrodes in the load region (which serve as hohlraum walls) may be substantially reduced. In these experiments, mass and array width scans were performed using tungsten wires. A maximum total radiated x-ray power of 10 {+-} 2 TW was observed with 20 mm wide arrays imploding in {approx}100 ns at a load current of {approx}3 MA, limited by the high inductance. Decreased power in the 4-6 TW range was observed at the smallest width studied (8 mm). 10 kJ of Al K-shell x-rays were obtained in one Al planar array fielded. This report will discuss the zero-dimensional calculations used to design the loads, the results of the experiments, and potential future research to determine if planar wire arrays will continue to scale favorably at current levels typical of the Z machine. Implosion dynamics will be discussed, including x-ray self-emission imaging used to infer the velocity of the implosion front and the potential role of trailing mass. Resistive heating has been previously cited as the cause for enhanced yields observed in excess of jxB-coupled energy. The analysis presented in this report suggests that jxB-coupled energy may explain as much as the energy in the first x-ray pulse but not the total yield, which is similar to our present understanding of cylindrical wire array behavior.

Chuvatin, Alexander S. (Laboratoire du Centre National de la Recherche Scientifique Ecole Polytechnique, Palaiseau, France); Jones, Michael; Vesey, Roger Alan; Waisman, Eduardo M.; Esaulov, Andrey A. (University of Nevada, Reno, NV); Ampleford, David J.; Kantsyrev, Victor Leonidovich (University of Nevada, Reno, NV); Cuneo, Michael Edward; Rudakov, L. I. (Icarus Research Inc., Bethesda, MD); Coverdale, Christine Anne; Jones, Brent Manley; Safronova, Alla S. (University of Nevada, Reno, NV)

2007-10-01

383

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

384

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

385

Multi-target controller of three-level NPC based VSC-HVDC transmission system and Its RTDS simulation  

Microsoft Academic Search

This paper builds the dynamic mathematic model of the three-level Neutral Point Diode Clamped (NPC) converter, discusses the fundamental principles of the active and reactive power control for three-level Voltage Source Converter based HVDC (VSC-HVDC) system. To fully utilize the controllability of VSC-HVDC, multi-target controller is developed to control AC and DC system respectively. Improved sine wave PWM (ISPWM) technique

Jianhua Zhang; Sheng Li; Jingfu Shang; Weiwei Zhao; Chunye Li

2008-01-01

386

Negative differential resistance and pulsed current induced multi-level resistivity switching in charge ordered and disordered manganites  

Microsoft Academic Search

We have investigated direct and pulsed current induced electroresistance in two manganites with different electronic and magnetic ground states: charge-orbital ordered 50 % Ca doped NdMnO3 and 50 % Mn doped LaNiO3. It has been shown that negative differential resistance observed at high current density in these compounds is related to Joule heating. However, bi-level and multi-level resistivity switching induced

A. Rebello; R. Mahendiran

2008-01-01

387

Health Behavior Change Models for HIV Prevention and AIDS Care: Practical Recommendations for a Multi-Level Approach.  

PubMed

: Despite increasing recent emphasis on the social and structural determinants of HIV-related behavior, empirical research and interventions lag behind, partly because of the complexity of social-structural approaches. This article provides a comprehensive and practical review of the diverse literature on multi-level approaches to HIV-related behavior change in the interest of contributing to the ongoing shift to more holistic theory, research, and practice. It has the following specific aims: (1) to provide a comprehensive list of relevant variables/factors related to behavior change at all points on the individual-structural spectrum, (2) to map out and compare the characteristics of important recent multi-level models, (3) to reflect on the challenges of operating with such complex theoretical tools, and (4) to identify next steps and make actionable recommendations. Using a multi-level approach implies incorporating increasing numbers of variables and increasingly context-specific mechanisms, overall producing greater intricacies. We conclude with recommendations on how best to respond to this complexity, which include: using formative research and interdisciplinary collaboration to select the most appropriate levels and variables in a given context; measuring social and institutional variables at the appropriate level to ensure meaningful assessments of multiple levels are made; and conceptualizing intervention and research with reference to theoretical models and mechanisms to facilitate transferability, sustainability, and scalability. PMID:25007194

Kaufman, Michelle R; Cornish, Flora; Zimmerman, Rick S; Johnson, Blair T

2014-08-15

388

An Automated Method for Segmenting White Matter Lesions through Multi-Level Morphometric Feature Classification with Application to Lupus  

PubMed Central

We demonstrate an automated, multi-level method to segment white matter brain lesions and apply it to lupus. The method makes use of local morphometric features based on multiple MR sequences, including T1-weighted, T2-weighted, and fluid attenuated inversion recovery. After preprocessing, including co-registration, brain extraction, bias correction, and intensity standardization, 49 features are calculated for each brain voxel based on local morphometry. At each level of segmentation a supervised classifier takes advantage of a different subset of the features to conservatively segment lesion voxels, passing on more difficult voxels to the next classifier. This multi-level approach allows for a fast lesion classification method with tunable trade-offs between sensitivity and specificity producing accuracy comparable to a human rater.

Scully, Mark; Anderson, Blake; Lane, Terran; Gasparovic, Charles; Magnotta, Vince; Sibbitt, Wilmer; Roldan, Carlos; Kikinis, Ron; Bockholt, Henry J.

2009-01-01

389

Delineating Reactive Natural Attenuation Zones: Multi-level Sampling in an Ammonium Plume  

NASA Astrophysics Data System (ADS)

Current natural attenuation monitoring involves observing concentrations along some transect parallel to flow, often in long--screened observation wells. Vertically integrated geochemical signals essentially compresses 3D-problems into 2D ones and the loss of process resolution does not allow for robust plume transport prediction. On the other hand, a monitoring approach that is based on process quantification will yield field data necessary for current natural attenuation assessment and allow more accurate prediction to plume behaviour. To quantify these spatially discrete processes, the resolution of sampling points must be higher to delineate reactive zones, that account for the bulk of natural attenuation. These reactive zones are dependent on aquifer properties, contaminant type, redox zonation and other factors. In many cases, the plume fringe will be the most active zone, because influx of certain nutrients necessary to support bacteria will be greatest in these zones. Most importantly, consortia of degrading bacteria are dependent on supply of electron--acceptors such as dissolved {O2} and nitrate from background ground water and recharge; electron--acceptors are rapidly consumed at the fringes and concentrations decrease significantly towards the centre of the plume. Thus, if a process--based approach is to be achieved, one has to focus not only on the overall extent and mass of a contaminant plume, but, more importantly, on a sound analysis of the most reactive zones. The site of a former coal processing plant in the UK was chosen as a field site where the afore--mentioned hypothesis is currently being investigated by means of two recently installed multi--level samplers. Previous investigations have located an ammonium plume at the site with outwash from the thick unsaturated zone as ongoing source since the demolition of the actual plant in 1970. The conceptual model drawn from the analysis of these data shows that certain zones exhibit higher rates of degradation than others, but the extent of these zones and rates of degradation could not be determined with the sampling methods used in previous investigations. Spacing between the sampling ports in the newly installed multi--level samplers is 25cm across the top fringe of the plume, and the ground water is analysed for contaminants, general redox chemistry of the aquifer, and isotopes. The analysis of groundwater samples from a first sampling round performed in late summer 2003 shows that i) nitrification is ongoing at the upper fringe in a zone about 0.5m thick, but concentrations of nitrate encountered at the ports across the fringe are higher that derived from the degradation of available ammonium; ii) concentrations of electron--donors and --acceptors change rapidly in the fringe--zone; iii) inside the plume, different processes are prevalent than at the upper fringe; iv) a trend in the isotopic composition appears to indicate a distinct consumption of carbon and sulphate by microbial activity, but these data are not unequivocal and should only be used as supportive evidence.

Hüttmann, A.; Wilson, R. D.; Thornton, S. F.; Lerner, D. N.

2003-12-01

390

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

2011-10-01

391

Socioeconomic Status and the Health of Youth: A Multi-level, Multi-domain Approach to Conceptualizing Pathways  

PubMed Central

Previous research has clearly established associations between low socioeconomic status (SES) and poor youth physical health outcomes. This article provides an overview of the main pathways through which low SES environments come to influence youth health. We focus on two of the most prevalent chronic health problems in youth today, asthma and obesity. We review and propose a model that encompasses (1) multiple levels of influence, including the neighborhood, family and person level, (2) both social and physical domains in the environment, and finally (3) dynamic relationships between these factors. A synthesis of existing research and our proposed model draw attention to the notion of adverse physical and social exposures in youth’s neighborhood environments altering family characteristics and youth psychosocial and behavioral profiles, thereby increasing youth’s risk for health problems. We also note the importance of acknowledging reciprocal influences across levels and domains (e.g., between family and child) that create self-perpetuating patterns of influence that further accentuate the impact of these factors on youth health. Finally, we document that factors across levels can interact (e.g., environmental pollution levels with child stress) to create unique, synergistic effects on youth health. Our model stresses the importance of evaluating influences on youth’s physical health not in isolation but in the context of the broader social and physical environments in which youth live. Understanding the complex relationships between the factors that link low SES to youth’s long-term health trajectories is necessary for the creation and implementation of successful interventions and policies to ultimately reduce health disparities.

Schreier, Hannah M. C.; Chen, Edith

2012-01-01

392

Assessment and quantification of post-weaning multi-systemic wasting syndrome severity at farm level.  

PubMed

Post-weaning multi-systemic wasting syndrome (PMWS) causes major economic losses for the English pig industry and severity of clinical signs and economic impact vary considerably between affected farms. We present here a novel approach to quantify severity of PMWS based on morbidity and mortality data and presence of porcine circovirus type 2 (PCV2). In 2008-2009, 147 pig farms across England, non-vaccinating for PCV2, were enrolled in a cross-sectional study. Factor analysis was used to generate variables representing biologically meaningful aspects of variation among qualitative and quantitative morbidity variables. Together with other known variables linked to PMWS, the resulting factors were included in a principal component analysis (PCA) to derive an algorithm for PMWS severity. Factor analysis resulted in two factors: Morbidity Factor 1 (MF1) representing mainly weaner and grower morbidity, and Morbidity Factor 2 (MF2) which mainly reflects variation in finisher morbidity. This indicates that farms either had high morbidity mainly in weaners/growers or mainly in finishers. Subsequent PCA resulted in the extraction of one component representing variation in MF1, post-weaning mortality and percentage of PCV2 PCR positive animals. Component scores were normalised to a value range from 0 to 10 and farms classified into: non or slightly affected farms with a score <4, moderately affected farms with scores 4-6.5 and highly affected farms with a score >6.5. The identified farm level PMWS severities will be used to identify risk factors related to these, to assess the efficacy of PCV2 vaccination and investigating the economic impact of potential control measures. PMID:21036410

Alarcon, Pablo; Velasova, Martina; Werling, Dirk; Stärk, Katharina D C; Chang, Yu-Mei; Nevel, Amanda; Pfeiffer, Dirk U; Wieland, Barbara

2011-01-01

393

Enhancing K-12 Ocean Science Education Through Multi-level Partnership  

NASA Astrophysics Data System (ADS)

This paper highlights the results of long-term collaborations between the University of South Florida's College of Marine Science (CMS) and the Pinellas County school district (22nd largest nationally) to advance and improve K-12 Earth/Ocean science education. The 12-year mission of Education and Public Outreach (EPO) in the College of Marine Science has been to meaningfully integrate ocean science research and science learning to enhance K-12 education for teachers and students. Our interactive and interdisciplinary programs include research cruises, field trips, authentic research projects, satellite broadcasts, and web-based technologies. This paper will focus on two programs, the Oceanography Camp for Girls and Teachers and Project Oceanography. We will address impact of these programs, what works, the role and value of partnerships, sustainability and future initiatives. An especially critical aspect of EPO is partnerships. Our partners include people, scientific facilities, community, and donors. Financial partnerships provide sustainability and continuity. For example, private donors have built a series of endowments to support the Oceanography Camp for Girls currently valued at over \\$1 million. Given the recent shift in state and federal funding priorities, private funding is a vital element of successful EPO programs. To date, marine science EPO partnerships have included 34 state agencies, universities, private research laboratories, schools, and museums; 75 scientist, advanced graduate students and teachers as co-instructors; 4 television stations and 2 production companies; and over 2,000,000 participants in 7 countries. Multi-level partnerships are enhancing K-12 classrooms around the world with relevant ocean science content and resources to further science interests, ocean awareness, and informed decision making.

Greely, T. M.; Coble, P.; Betzer, P. R.

2003-12-01

394

Refined multi-level methodology in parallel computing environment for BWR RIA analysis  

NASA Astrophysics Data System (ADS)

Best-estimate methodologies in boiling water reactor can reduce the traditional conservative thermal margins imposed on the designs and during the operation of this type of nuclear reactors. Traditional operating thermal margins are obtained based on simplified modeling techniques that are supplemented with the required dose of conservatism. For instance, much more realistic transient pin peaking distributions can be predicted by applying a dehomogenization algorithm, based on a flux reconstruction scheme which uses nodal results during both steady state and transient calculation at each time step. A subchannel analysis module for obtaining thermal margins supplements the calculation approach used. A multi-level methodology to extend the TRAC-BF1/NEM coupled code capability to obtain the transient fuel rod response has been implemented. To fulfill the development requirements some improved neutronic models were implemented into the NEM solution algorithm, namely the pin power reconstruction capability, and the simulation of a dynamic scram. The obtained results were coupled to a subchannel analysis module: COBRA-TF T-H subchannel analysis code. The objective of the pin power reconstruction capability of NEM is to locate the most limiting node (axial region of assembly/channel) within the core. The power information obtained from the NEM 3D neutronic calculation is used by the hot channel analysis module (COBRA-TF). COBRA-TF needs also the T-H conditions at the boundary nodes. This information is provided by TRACBF1 T-H system analysis code. The Subchannel analysis module uses this information to re-calculate the fluid, thermal and hydraulics conditions in the most limiting node (axial region of assembly/channel) within the core.

Solis-Rodarte, Jorge

395

Possible Problems: Inverted, Flat, or Pierced Nipples  

MedlinePLUS

... Flat, or Pierced Nipples Ages & Stages Listen Possible Problems: Inverted, Flat, or Pierced Nipples Article Body Inverted ... a lesser extent flat nipples, can create a problem during breastfeeding by making it more difficult for ...

396

Inverters for Uninterruptible Power Supplies  

Microsoft Academic Search

The synthesis of the principal types of inverters that are best suited for static uninterruptible power supplies (UPS) is sought. From this synthesis a range of apparatus is evolved that will satisfy present and future needs. For each point of this range new solutions are indicated; their development is tied with the technological evolution of the components. The reliability and

Robert Chauprade

1977-01-01

397

Minimally Invasive Multi-Level Posterior Lumbar Interbody Fusion Using a Percutaneously Inserted Spinal Fixation System : Technical Tips, Surgical Outcomes  

PubMed Central

Objective There are technical limitations of multi-level posterior pedicle screw fixation performed by the percutaneous technique. The purpose of this study was to describe the surgical technique and outcome of minimally invasive multi-level posterior lumbar interbody fusion (PLIF) and to determine its efficacy. Methods Forty-two patients who underwent mini-open PLIF using the percutaneous screw fixation system were studied. The mean age of the patients was 59.1 (range, 23 to 78 years). Two levels were involved in 32 cases and three levels in 10 cases. The clinical outcome was assessed using the visual analog scale (VAS) and Low Back Outcome Score (LBOS). Achievement of radiological fusion, intra-operative blood loss, the midline surgical scar and procedure related complications were also analyzed. Results The mean follow-up period was 25.3 months. The mean LBOS prior to surgery was 34.5, which was improved to 49.1 at the final follow up. The mean pain score (VAS) prior to surgery was 7.5 and it was decreased to 2.9 at the last follow up. The mean estimated blood loss was 238 mL (140-350) for the two level procedures and 387 mL (278-458) for three levels. The midline surgical scar was 6.27 cm for two levels and 8.25 cm for three level procedures. Complications included two cases of asymptomatic medial penetration of the pedicle border. However, there were no signs of neurological deterioration or fusion failure. Conclusion Multi-level, minimally invasive PLIF can be performed effectively using the percutaneous transpedicular screw fixation system. It can be an alternative to the traditional open procedures.

Kim, Hyeun Sung; Park, Keun Ho; Ju, Chag Il; Lee, Seung Myung; Shin, Ho

2011-01-01

398

Hybrid multilevel inverter with single DC source  

Microsoft Academic Search

A hybrid multilevel inverter model based on PSIM and MATLAB\\/SIMULINK is presented in this paper. It consists of a standard 3-leg inverter (one leg for each phase) and H-bridge in series with each inverter leg. The inverter can be used in hybrid electric vehicles (HEV) and electric vehicles (EV). The co-simulation model is employed in order to take full advantage

Haiwen Liu; Leon M. Tolbert; Burak Ozpineci; Zhong Du

2008-01-01

399

Update on SIC-Based Inverter Technology  

SciTech Connect

This paper presents a study of silicon carbide (SiC) technology which includes device characterization and modeling, inverter simulation, and test results for several prototype inverters. The static and dynamic characteristics of discrete devices and half bridge modules are presented. Test results of a 55 kW hybrid inverter with SiC Schottky diodes and an 18 kW all-SiC inverter using SiC JFETs and Schottky diodes are demonstrated.

Chinthavali, Madhu Sudhan [ORNL; Zhang, Hui [ORNL; Tolbert, Leon M [ORNL; Ozpineci, Burak [ORNL

2009-01-01

400

A New Multi-phase Level Set Framework for 3D Medical Image Segmentation Based on TPBG.  

PubMed

In this paper, we propose a new multi-phase level set framework for 3D medical image segmentation to deal with the limitation of 2-phase segmentation algorithms using one level set. By developing the technique of painting the background with average gray level of the object (TPBG) and reusing the active contours model without edges [1] which is 2-phase one, we are able to obtain more than two segments (n-1 times for n phases, n>1). Following the philosophy of dichotomy, we illustrate the efficiency of the proposed framework by segmenting a 3D medical image into more than two segments step by step. PMID:17280951

Zheng, Gang; Li, Yuanlu; Wang, Huinan

2005-01-01

401

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

402

Multi-objective regionalisation for lake level simulation, the case of Lake Tana in the Upper Blue Nile, Ethiopia  

NASA Astrophysics Data System (ADS)

The aim in this study is to simulate lake levels of Lake Tana by solving the water balance at daily time step. Since 42% of the basin is ungauged regionalisation procedures are applied. We examine the predictive capability of a regionalisation approach that combines multi-objective calibration of a simple conceptual model and multi regression analyses to establish relations between model parameters and catchment characteristics. Recently few studies are presented on lake level simulation of Lake Tana. In these studies the water balance of the lake is closed by estimation of runoff contributions from ungauged catchments. Studies partly relied on simple ad-hoc procedures of area comparison to estimate runoff from ungauged catchments. In this study a regional model is developed that relies on principles of similarity of catchments. For runoff modelling the HVB-96 model is selected while multi-objective model calibration is by a Monte Carlo procedure. Assessment of the lake water balance was established by comparing measured to estimated lake levels. Results of daily lake level simulation show a water balance closure term of 85 mm and a relative volume error of 2.17%. Results show runoff from ungauged catchments of 527 mm per year for the simulation period 1994 to 2003 that is approximately 30% of Lake Tana stream flow inflow. Compared to previous works this closure term is smallest.

Rientjes, T. H. M.; Perera, B. U. J.; Haile, A. T.; Reggiani, P.

2010-09-01

403

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

404

Security of Invertible Media Authentication Schemes Revisited  

Microsoft Academic Search

Dittmann, Katzenbeisser, Schallhart and Veith (IACR ePrint 2004) intro- duced the notion of invertible media authentication schemes, embedding authentication data in media objects via invertible watermarks. These invertible watermarks allow to recover the original media object (given a secret encryption key), as required for example in some medical applications where the distortion must be removable. Here we revisit the approach

Daniel Dönigus; Stefan Endler; Marc Fischlin; Andreas Hülsing; Patrick Jäger; Anja Lehmann; Sergey Podrazhansky; Sebastian Schipp; Erik Tews; Sven Vowe; Matthias Walthart; Frederik Weidemann

2007-01-01

405

Synchronous operation of dual-inverter-based photovoltaic system with low DC-voltages  

Microsoft Academic Search

Novel method of synchronized pulsewidth modulation (PWM) has been disseminated for control of cascaded (dual) inverters of photovoltaic installation with relatively low DC-voltages of two insulated photovoltaic panels, operating under condition of low level of solar irradiance. Control regimes are characterized by overmodulation control modes of two inverters in this case. Algorithms of synchronized PWM provide continuous voltage synchronization both

G. Griva; V. Oleschuk

2010-01-01

406

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

407

A 24 MVA inverter using IGCT series connection for medium voltage applications  

Microsoft Academic Search

This paper describes a 24 MVA inverter utilizing the series connection of three IGCTs per switch position in a three-level neutral point clamped inverter topology. The electrical design, especially focused on one phase leg, as well as experimental results, are shown

A. Nagel; S. Bernet; P. K. Steimer; O. Apeldoorn

2001-01-01

408

Multi-level multi-domain algorithm implementation for two-dimensional multiscale particle in cell simulations  

NASA Astrophysics Data System (ADS)

There are a number of modeling challenges posed by space weather simulations. Most of them arise from the multiscale and multiphysics aspects of the problem. The multiple scales dramatically increase the requirements, in terms of computational resources, because of the need of performing large scale simulations with the proper small-scales resolution. Lately, several suggestions have been made to overcome this difficulty by using various refinement methods which consist in splitting the domain into regions of different resolutions separated by well defined interfaces. The multiphysics issues are generally treated in a similar way: interfaces separate the regions where different equations are solved. This paper presents an innovative approach based on the coexistence of several levels of description, which differ by their resolutions or, potentially, by their physics. Instead of interacting through interfaces, these levels are entirely simulated and are interlocked over the complete extension of the overlap area. This scheme has been applied to a parallelized, two-dimensional, Implicit Moment Method Particle in Cell code in order to investigate its multiscale description capabilities. Simulations of magnetic reconnection and plasma expansion in vacuum are presented and possible implementation options for this scheme on very large systems are also discussed.

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

2014-08-01

409

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

410

Feature-Level Fusion by Multi-Objective Binary Particle Swarm Based Unbiased Feature Selection for Optimized Sensor System Design  

Microsoft Academic Search

The performance of recognition systems in intelligent sensor technology can often be improved by using the combined information of several different measurement results, i.e., signal processing and feature computation, of single-sensor and\\/or multi-sensor information. However, the large dimensional data caused by feature-level fusion imposes an accuracy problem on classification tasks, due to some irrelevant and\\/or redundant features. For this reason,

Kuncup Iswandy; Andreas Koenig

2006-01-01

411

Multi-physics power-drive-level dependant equivalent circuit models extraction for electro-mechanical resonators  

Microsoft Academic Search

This paper discusses multi -physics modeling methodology for the design and analysis of integrated crystal oscillators based on power-waves formulation. Conventional Barkhausen oscillation conditions criterion is derived in terms of reflection coefficients. Necessity of power-drive-level dependant equivalent circuit models derivation for electromechanical resonators is investigated in order to build bridging connections between more than one energy domain (mechanical, electrical, acoustics,

Sidina Wane; Damienne Bajon

2011-01-01

412

MultiLevel Seismic Performance Assessment of a Damage-protected Beam-column Joint with Internal Lead Dampers  

Microsoft Academic Search

2007 NZSEE Conference ABSTRACT: A multi-level seismic performance assessment is performed on a near full scale beam-column subassembly. The physical model is taken from a 3D exterior connection of a jointed precast concrete frame structure that is designed for damage avoidance. Unbonded post-tensioned prestress is provided by high-alloy high-strength thread-bars. Draped and straight tendon profiles are used in the transverse

K. M. Solberg; B. A. Bradley; G. W. Rodgers; J. B. Mander; R. P. Dhakal; J. G. Chase

413

An integrated approach for climate-change impact analysis and adaptation planning under multi-level uncertainties. Part I: Methodology  

Microsoft Academic Search

In this study, a large-scale integrated modeling system (IMS) was developed for supporting climate-change impact analysis and adaptation planning under multi-level uncertainties. A number of methodologies were seamlessly incorporated within IMS, including fuzzy-interval inference method (FIIM), inexact energy model (IEM), and uncertainty analysis. The system could (i) encompass multiple technologies, energy resources, and sub-sectors, and climate change impact analysis into

Y. P. Cai; G. H. Huang; Q. Tan; Z. F. Yang

2011-01-01

414

On the use of a hierarchical multi-level building block basis function scheme in periodic plasmonic structures  

NASA Astrophysics Data System (ADS)

A Volumetric Method of Moments algorithm is applied to predict the plasmonic responses of chiral metamaterials. This algorithm is based on the use of a multi-level building block basis function scheme, in combination with a dedicated Kummer transformation in the calculation of periodic Green's functions. The validity of the algorithm is demonstrated by analyzing a Ninja Star periodic structure. A good agreement can be found between simulation and experiment.

Zheng, X.; Valev, V. K.; Volskiy, V.; Vandenbosch, Guy A. E.; Moshchalkov, V. V.

2014-05-01

415

The relationship of work unit contextual factors to leader-member exchange: A multi-level theoretical and empirical investigation  

Microsoft Academic Search

The Leader-Member Exchange model (LMX) has not been adequately explored via multi-level analysis, even though its propositions warrant such examination. The theory has been proposed to have both within-group effects as well as between-group effects. Also, the relationship between LMX and performance has been equivocal, and researchers have called for the exploration of moderating variables to understand these conflicting findings.

Claudia C. Cogliser

1997-01-01

416

An Ultrahigh-Speed Low-Power DAC Using InP HBTs for MultiLevel Optical Transmission Systems  

Microsoft Academic Search

This paper presents an ultrahigh-speed low-power digital-to-analog converter (DAC) for multi-level optical transmission systems. To achieve both high-speed and low-power operation, we used a simple R-2R ladder-based current-steering architecture and devised a timing alignment technique. The 6-bit DAC test chip was fabricated with our InP HBT technology, which yields a peak ft of 175 GHz and a peak fmax of

Munehiko Nagatani; Hideyuki Nosaka; Shogo Yamanaka; Kimikazu Sano; Koichi Murata

2010-01-01

417

Estimating stream discharge using stage and multi-level acoustic Doppler velocimetry  

NASA Astrophysics Data System (ADS)

For temperate region countries with small or moderately sized streams, such as those in Denmark, seasonal weed growth imposes a significant temporal change of the stage-discharge relation. In the past such problems were often avoided by using hydraulic structures, however, firm ecology based restrictions prevent that hydraulic structures are made at the discharge stations presently. As a consequence, the nonlinear drift in weed density and structure adds a significant uncertainty to the hydrograph. Furthermore, the expected increase in extreme discharge situations due to climate changes in the Northern part of Europe may further violate a stable relation between stage and discharge in streams. Extreme high flow situations cause abrupt rise in stage, and consequently weed can be partly uprooted and partly bend down along the bed, thereby changing the conveyance of the stream. In addition, extreme high flow situations can cause the streams to flood the banks. If these hydraulic changes occur in between direct measurements of discharge they are not detected or accounted for in the stage-discharge relation, and the hydrograph can be significantly biased. The objective of this research is to investigate how both seasonal and short duration changes in weed distribution and abrupt changes in stage are recognized in the stream's velocity gradient. It is examined whether the use of multi-level acoustic Doppler velocimetry can provide an improved method for hydrograph estimation with lower uncertainty than traditional stage-discharge methods. In this presentation we shall present results from a study where, at two sites in Denmark, the stream velocity field has been mapped by the use of three Acoustic Doppler Velocity Meter (ADVM) instruments. The ADVM instruments are mounted in three different depths, continuously measuring horizontal average water velocities. Velocity and stage data are selected from one summer and two winter periods, and a method for converting velocity and stage data to discharge will be presented. The estimated discharges are compared with control measurements of discharge obtained from an Acoustic Doppler Current Profiler (ADCP) and with discharge values derived by the Danish Water Authority by traditional stage-discharge analysis. The novelty of this approach is that the velocity gradient is implemented as a marker for hydraulic changes in the hydrograph estimation, without explicit use of cross sectional area and cross sectional average velocity. The initial results show good agreement between the ADCP discharge measurements and the discharge values predicted from the stage-velocity method and suggest superiority of the stage-velocity method during abrupt changes in stage.

Poulsen, J. B.; Rasmussen, K.; Ledet Jensen, J.; Bering Ovesen, N.

2011-12-01

418

Thermal Study of Inverter Components: Preprint  

SciTech Connect

Thermal histories of inverter components were collected from operating inverters from several manufacturers and three locations. The data were analyzed to determine thermal profiles, the dependence on local conditions, and to assess the effect on inverter reliability. Inverter temperatures were shown to increase with the power dissipation of the inverters, follow diurnal and annual cycles, and have a dependence on wind speed. An accumulated damage model was applied to the temperature profiles and an example of using these data to predict reliability was explored.

Sorensen, N. R.; Thomas, E. V.; Quintana, M. A.; Barkaszi, S.; Rosenthal, A.; Zhang, Z.; Kurtz, S.

2012-06-01

419

Multi-level sexual selection: individual and family-level selection for mating success in a historical human population.  

PubMed

Precopulatory sexual selection is the association between fitness and traits associated with mate acquisition. Although sexual selection is generally recognized to be a powerful evolutionary force, most investigations are limited to characters belonging to individuals. A broader multilevel perspective acknowledges that individual fitness can be affected by aspects of mating success that are characters of groups, such as families. Parental mating success in polygynous or polyandrous human societies may exemplify traits under group-level sexual selection. Using fitness measures that account for age-structure, I measure multilevel selection for mate number over 55 years in a human population with declining rates of polygyny. Sexual selection had three components: individual-level selection for ever-mating (whether an individual mated) and individual- and family-level selection for polyandry and polygyny. Family- and individual-level selection for polygyny was equally strong, three times stronger than family-level selection for polyandry and more than an order of magnitude stronger than individual-level selection for polyandry. However, individual-level selection for polyandry and polygyny was more effective at explaining relative fitness variance than family-level selection. Selection for ever-mating was the most important source of sexual selection for fitness; variation for ever-mating explained 23% of relative fitness variance. PMID:23730758

Moorad, Jacob A

2013-06-01

420

PREVENTION OF INVERTER VOLTAGE TRIPPING IN HIGH DENSITY PV GRIDS  

Microsoft Academic Search

In distribution grids with a high density of Photovoltaic Systems, excessive voltage rise because of reverse energy flows may occur, resulting in annoying off and on tripping of overvoltage relays. In this paper, it is proposed to prevent this undesired behaviour by reducing the power output from the PV inverters gradually in terms of grid voltage level. As there is

K. De Brabandere; A. Woyte; R. Belmans; J. Nijs

421

Sensitivity of Aerosol MultiSensor Daily Data Intercomparison to Level 3 Dataday Definition  

Microsoft Academic Search

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

Gregory Leptoukh; David Lary; Chritopher Lynnes; Suhung Shen

2010-01-01

422

System-level multi-target drug discovery from natural products with applications to cardiovascular diseases.  

PubMed

The term systems pharmacology describes a field of study that uses computational and experimental approaches to broaden the view of drug actions rooted in molecular interactions and advance the process of drug discovery. The aim of this work is to stick out the role that the systems pharmacology plays across the multi-target drug discovery from natural products for cardiovascular diseases (CVDs). Firstly, based on network pharmacology methods, we reconstructed the drug-target and target-target networks to determine the putative protein target set of multi-target drugs for CVDs treatment. Secondly, we reintegrated a compound dataset of natural products and then obtained a multi-target compounds subset by virtual-screening process. Thirdly, a drug-likeness evaluation was applied to find the ADME-favorable compounds in this subset. Finally, we conducted in vitro experiments to evaluate the reliability of the selected chemicals and targets. We found that four of the five randomly selected natural molecules can effectively act on the target set for CVDs, indicating the reasonability of our systems-based method. This strategy may serve as a new model for multi-target drug discovery of complex diseases. PMID:24792224

Zheng, Chunli; Wang, Jinan; Liu, Jianling; Pei, Mengjie; Huang, Chao; Wang, Yonghua

2014-08-01

423

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

Microsoft Academic Search

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

1994-01-01

424

Multi-Media Input to a Foundation ESP Course at University Level.  

ERIC Educational Resources Information Center

The Organized Career Orientation Course was written to help Bahraini secondary school leavers prepare for the job market by equipping them with relevant language skills such as note taking and report writing. The strong point of the course is the multi-media input and the fact that it is student-centered. Two learning methods were piloted. Results…

Al-Ahmed, Fatima H.

2000-01-01

425

OptCom: A Multi-Level Optimization Framework for the Metabolic Modeling and Analysis of Microbial Communities  

PubMed Central

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.

Zomorrodi, Ali R.; Maranas, Costas D.

2012-01-01

426

Using hidden multi-state Markov models with multi-parameter volcanic data to provide empirical evidence for alert level decision-support  

NASA Astrophysics Data System (ADS)

For the purposes of eruption forecasting and hazard mitigation, a volcanic crisis may be represented as a staged progression of states of unrest, each with its own timescale and likelihood of transition to other states (or to climactic eruption). If the state conditions can be interpreted physically, e.g., in terms of advancing materials failure, this knowledge could be used directly to inform decisions on alert level setting. A multi-state Markov process provides one simple model for defining states and for estimating rates of switching between states. However, for eruptive processes, such states are not directly observable and must be inferred from latent markers, such as seismic activity, gas output, deformation rates, etc., some of which may be contradictory. Interpretations of uncertain data will be liable to error, so a model is needed which can simultaneously estimate both elements: the transition likelihood of a hidden process and the probabilities of state misclassification. We describe the concept and underlying principles of continuous-time hidden Markov models and demonstrate them in a decision-support context with a preliminary working implementation using MULTIMO data. Where multi-parameter streams of raw, processed or conditioned data of different kinds are available, these can be input in near real-time to appropriate hidden multi-state Markov models, the outputs of each providing their own objective analyses of eruptive state in probabilistic terms. These separate, multiple indicators of state can then be input into a Bayesian Belief Network framework for weighing and combining them as different strands of evidence, together with other observations, data, interpretations and expert judgment.

Aspinall, W. P.; Carniel, R.; Jaquet, O.; Woo, G.; Hincks, T.

2006-05-01

427

Inverting amplifier genetic circuit performance.  

PubMed

A synthetic genetic circuit has been designed whose topology and function echo those of an electronic inverting amplifier. Several variants of this circuit have been built in our laboratory. This paper reports on the testing of one of these variants and contributes to the field both in terms of evaluating the specific amplifier performance and in terms of providing a methodology for performance evaluation of analog genetic circuits. An input source was created and partially calibrated. It was then used to test the circuit through both fluorometer measurements and flow cytometry. In the discussion, consideration is given to cellular loading by the synthetic circuits and the resulting impact on circuit performance. Models developed earlier are compared with the experimental results. The circuit does indeed perform as an inverting amplifier. PMID:17947009

Nagaraj, S; Davies, S W

2006-01-01

428

High spatial resolution water level time series in the Florida Everglades wetlands using multi-track ALOS PALSAR data  

NASA Astrophysics Data System (ADS)

Wetland InSAR (Interferometric Synthetic Aperture Radar) observations provide very high-resolution maps of water level changes that cannot be obtained by any terrestrial technique. We recently developed the Small Temporal Baseline Subset (STBAS) approach, which combines single-track InSAR and stage (water level) observations to generate high-resolution absolute water level time series maps. However, the temporal resolution of produced time series is coarse compared with in-situ stage observation and, hence, the usefulness of these maps is rather limited. To compensate for the low temporal resolution weakness of space-based water level time series, we propose using a multi-track STBAS technique, which utilizes all available Synthetic Aperture Radar (SAR) observations acquired over a certain wetland area. We use a four-year long L-band ALOS PALSAR dataset acquired during 2007-2011 to test the proposed method over the Water Conservation Area 1 (WCA1) in the Everglades wetlands, south Florida (USA). A total of 37 images acquired with four tracks were collected. Daily water level data at 12 stage stations, which are monitored by the Everglades Depth Estimation Network (EDEN) in WCA1 area, were used to calibrate the InSAR-derived water level data. The proposed multi-track approach yielded a significant improvement of temporal resolution, which is dependent on the SAR satellite revisit cycle. Instead of the 46-day repeat orbit of ALOS, the multi-track method produces water level maps with temporal resolution of only 7 days. A quality control analysis of the methods indicates that the average root mean square error (RMSE) of the differences between stage water level and retrieved water level by InSAR technique is 4.0 cm. The end products of absolute water level time series with improved temporal and very high spatial resolutions can be used as excellent constraints for high-resolution wetland flow models. Furthermore, the next generation of SAR satellites has been designed with shorter revisit cycles, which will provide temporally denser maps of water level changes. Fig. 1. Comparison between stage (solid line) and InSAR (circle: 148 track, cross: 149 track, diamond: 464 track and square: 465 track) determined water level time series.

Hong, S.; Wdowinski, S.

2013-05-01

429

Simulations of magnetic reconnection with Parsek2D-MLMD, a new Multi Level Multi Domain (MLMD) Implicit Moment Method (IMM) Particle in Cell (PIC) code  

NASA Astrophysics Data System (ADS)

The kinetic simulation of intrinsically multi scale processes such as magnetic reconnection events with realistic mass ratios is a daunting task for explicit Particle In Cell (PIC) codes, which require to use resolutions of the order of the electron Debye length even when simulating dramatically bigger domains. As an example, a simulation of reconnection in the magnetotail, with domain sizes of the order of 20 di x 10 di (? 7.2 106 m x 3.6 106 m, with di being the ion skin depth) and a resolution of ?D,e= 687 m, with ?D,e the electron Debye length, requires the astounding number of 10500 x 5240 cells. Higher grid spacings can be used if the simulation is performed with an implicit PIC code, which substitutes a much less strict accuracy constraint to the stability constraint of explicit PIC codes. The same reconnection problem as before can be simulated, with an implicit PIC code resolving the scale of interest of de /2 instead of the electron Debye length (de is the electron skin depth), with the much more manageable number of 1920 x 958 cells. However, an even smaller number of cells can be used if, instead of using the same, high resolution on the entire domain, the domain to simulate is divided into subdomains each resolved with a grid spacing related to the physical scale of interest in the specific subdomain. In the case of reconnection, the division which immediately springs to mind is between electron diffusion region, ion diffusion region and outer region, where resolutions respectively of the order of fractions of the electron skin depth, of the ion skin depth and bigger can be used. We present here a new Multi Level Multi Domain (MLMD) Implicit Moment Method (IMM) Particle In Cell (PIC) code, Parsek2D-MLMD, able to perform simulations of magnetic reconnection where the expensive high resolutions are used only when needed, while the rest of the domain is simulated with grid spacings chosen according to the local scales of interest. The major difference between the MLMD method we present and the already existing Adaptive Mesh Refinement (AMR) methods (apart for the use of an implicit algorithm, to the authors' knowledge never employed before in PIC AMR methods) is the fact that all levels are fully simulated in fields and particles, while most of the existing AMR methods simulate particles only at the most refined levels. This simplifies the treatment of particles at the interface between the levels, an operation particularly delicate in presence of the strong localized currents that develop during reconnection. The interlocking of the levels simulated at different resolution is guaranteed through the interpolation of boundary conditions from the coarse to the refined levels, the projection of the refined fields from the refined to the coarse levels and the generation of the particles at the boundaries of the refined levels from the corresponding particle distribution at the coarse levels. Test simulations of reconnection events across the interlocked grids in 2D will be presented, together with performance considerations.

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

2012-12-01

430

Effective switching frequency multiplier inverter  

DOEpatents

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

Su, Gui-Jia (Oak Ridge, TN); Peng, Fang Z. (Okemos, MI)

2007-08-07

431

Gripper deploying and inverting linkage  

DOEpatents

An end effector deploying and inverting linkage. The linkage comprises an air cylinder mounted in a frame or tube, a sliding bracket next to the air cylinder, a stopping bracket depending from the frame and three, pivotally-attached links that are attached to the end effector and to each other in such a way as to be capable of inverting the end effector and translating it laterally. The first of the three links is a straight element that is moved up and down by the shaft of the air cylinder. The second link is attached at one end to the stopping bracket and to the side of the end effector at the other end. The first link is attached near the middle of the second, sharply angled link so that, as the shaft of the air cylinder moves up and down, the second link rotates about an axis perpendicular to the frame and inverts and translates the end effector. The rotation of the second link is stopped at both ends when the link engages stops on the stopping bracket. The third link, slightly angled, is attached to the sliding bracket at one end and to the end of the end effector at the other. The third helps to control the end effector in its motion.

Minichan, R.L.; Killian, M.A.

1993-03-02

432

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

433

Multi-level spinal fusion and postoperative prevertebral thickness increase the risk of dysphagia after anterior cervical spine surgery.  

PubMed

The present study aimed to determine the risk factors for dysphagia after anterior cervical spinal surgery. We reviewed clinical records of 45 patients after anterior cervical spinal surgery to identify the factors that influence dysphagia symptoms, and followed up the symptoms using a one-on-one telephone survey. The risk of dysphagia was greater in the anterior cervical discectomy and fusion group than in the anterior artificial disc insertion group, and in the group who underwent multi-level rather than single-level surgery. There were greater differences in prevertebral soft tissue thickness within 48 hours of surgery in patients with dysphagia than in patients without dysphagia at 1 month, 3 months, and 6 months after surgery, but these differences were not significant. The risk of dysphagia was significantly higher in patients who had their highest operative levels at C3 or C4 compared to those with their highest levels at C5 to C7. PMID:21798743

Kang, Si Hyun; Kim, Don-Kyu; Seo, Kyung Mook; Kim, Kyung-Tae; Kim, Yong-Baeg

2011-10-01

434

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

435

Multi-temporal, high spatial resolution water level monitoring of the Everglades  

Microsoft Academic Search

Water level information in South Florida's Everglades is very important for understanding the hydrology of this fragile ecosystem. Currently water levels are determined by a dense stage (water level) network providing high spatial resolution observation. However, because there are a finite number of stage stations in Everglades, water levels in areas located between stage stations can only be estimated by

S. Hong; S. Wdowinski; S. Kim

2008-01-01

436

Balancing HRM: the psychological contract of employees : A multi-level study  

Microsoft Academic Search

Purpose – This study aims to “bridge” two streams of HRM research: organisation level research on HRM and performance and individual level research on employee work perceptions and behavioural performance. This study seeks to analyse the value of organisation level HRM practices for individual level employees' assessment of the degree of violation of their psychological contracts. It also aims to

Mariëlle Sonnenberg; Bas Koene; Jaap Paauwe

2011-01-01

437

Risk factors of alcohol problem drinking among female bar/hotel workers in Moshi, Tanzania: a multi-level analysis.  

PubMed

There is limited information on alcohol problem drinking, which has been associated with sexually transmitted infections (STIs), including HIV, among female bar/hotel workers in Africa. This paper aimed to identify the individual- and facility-level determinants of alcohol problem drinking in this setting. Problem drinking was defined based on the CAGE alcohol screening scale. Multi-level logistic regression was used to identify individual- and facility-level factors associated with problem drinking. About 37.3% of women (N = 1629) were classified as having probable or definite problem drinking. In multi-level analysis, main characteristics associated with problem drinking included: having 3-4 partners in the past 5 years compared to having 1-2, used a condom in the last sex comparing to non-use, history of transactional sex, having more pregnancies, and facilities whose employees do not live on the premises. Interventions which combine alcohol and sexual risk reduction counseling are urgently needed in this population. PMID:21082340

Ao, Trong Thanh-Hoang; Sam, Noel; Kiwelu, Ireen; Mahal, Ajay; Subramanian, S V; Wyshak, Grace; Kapiga, Saidi

2011-02-01

438

Multiple degree of freedom inverted pendulum dynamics: Modeling, computation, and experimentation  

NASA Astrophysics Data System (ADS)

A pendulum is statically unstable in its upright inverted state due to the Earth's gravitational attraction which points downward. However, with proper forcing, the pendulum can be stabilized in its upright inverted state. Special interest is on periodic vertical forcing applied to the pendulum's base to stabilize it around the upright inverted equilibrium. Many researchers have studied how to stabilize the system by varying various parameters, in particular its amplitude and frequency. Most have focused on the single degree of freedom inverted pendulum case, which with linear assumption can be described via Mathieu's equation. The system stability can then be characterized by Floquet theory. Our focus is on searching for the periodic solutions inside the linearly stable region of the pendulum's inverted state when the pendulum is under proper periodic forcing. Our research shows that under appropriate excitation by controlling the forcing amplitude and frequency, the pendulum can maintain certain periodic orbits around its inverted state which we characterize in a systematic way. In this thesis, we applied four different kinds of geometric realizations of the system response: system time traces, system phase portraits, three dimensional views of the system phase portrait as a function of input forcing, and the system's power spectral density diagram. By analyzing these four diagrams simultaneously, we characterize different kinds of multi-frequency periodic behavior around the pendulum's inverted state. To further discuss the effect of the nonlinearity, we applied perturbation techniques using the normalized forcing amplitude as a perturbation parameter to carry out the approximate periodic solutions on a single degree of freedom inverted pendulum nonlinear model. We also discuss the multiple degree of freedom inverted pendulum system. Both numerical simulation and experiments were performed and detailed comparisons are discussed. Our numerical simulations show close qualitative agreement with experiments.

Chen, Cheng-Yuan Jerry

439

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

440

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

441

A Multi-level Entry and Exit Programme in Geratology (Applied Gerontology): An Evaluation.  

ERIC Educational Resources Information Center

Interviews, observations, and evaluative audits assessed a multiprofession, multilevel program in applied gerontology for health and social work practitioners. Teaching and assessing simultaneously at the diploma of higher education and master's degree levels enabled shared learning at both levels. (SK)

Wade, Sian; Thompson-Lynch, Annie

2000-01-01

442

Multi-scale environmental accounting: methodological lessons from the application of NAMEA at sub-national levels.  

PubMed

Extending the application of integrated environmental and economic accounts from the national to the local level of government serves several purposes. They can be used not only as an instrument for communicating on the state of the environment and reporting the results of policies, but also as an operational tool - for setting the objectives and designing policies - if made available to the local authorities who have responsibility over the administration of natural resources, land use and conservation policies. The aim of the paper is to test the feasibility of applying hybrid flow accounts at the intermediate and local government levels. As an illustration, NAMEA for air emissions and wastes is applied to a Region, a Province and a Municipality, thus covering the three nested levels of local government in Italy. The study identifies the main issues raised by multi-scale environmental accounting and provides an applied discussion of feasible solutions. PMID:24141065

Dalmazzone, Silvana; La Notte, Alessandra

2013-11-30

443

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

2012-01-01

444

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

445

Design and comparison of medium voltage multi-level converters for industry applications  

Microsoft Academic Search

This paper describes the design of a (2.3 kV, 2.4 MVA) two-level -, three-level - neutral point clamped -, three-level - flying capacitor - and four-level - flying capacitor - voltage source converter on the basis of state-of-the-art 6.5 kV, 3.3 kV and 2.5 kV IGBTs. The semiconductor loss distribution, design, and costs of semiconductors and passive components are compared

Dietmar Krug; Mariusz Malinowski; Steffen Bernet

2004-01-01

446

Sensitivity of Aerosol Multi-Sensor Daily Data Intercomparison to the Level 3 Dataday Definition.  

National Technical Information Service (NTIS)

Topics include: why people use Level 3 products, why someone might go wrong with Level 3 products, differences in L3 from different sensors, Level 3 data day definition, MODIS vs. MODIS, AOD MODIS Terra vs. Aqua in Pacific, AOD Aqua MODIS vs. MISR correla...

C. Lynnes D. Lary G. Leptoukh S. Shen

2010-01-01

447

Multi-Level Analysis of the Determinants of Receipt of Clinical Preventive Services Among Reproductive-Age Women  

PubMed Central

Background We investigate the impact of individual- and county-level contextual variables on women’s receipt of a comprehensive panel of preventive services in a region that includes both urban and rural communities. Methods Outcome variables were: a screening and vaccination index (a count of Papanicolaou test, blood pressure check, lipid panel, sexually transmitted infections or HIV test, and influenza vaccination received in the past 2 years) and a preventive counseling index (a count of topics discussed in the past 2 years: smoking and tobacco, alcohol or drugs, violence and safety, pregnancy planning or contraception, diet/nutrition, and sexually transmitted infections). Contextual covariates from the Area Resource File (2004-2005) were appended to prospective survey data from the Central Pennsylvania Women’s Health Study. Individual-level variables included predisposing, enabling, and need-based measures. Contextual variables included community characteristics and healthcare resources, including a measure of primary care physician density specifically designed for this study of women’s preventive care. Multi-level analyses were performed. Results We found low overall use of preventive services. In multi-level models, individual-level factors predicted receipt of both screening and vaccinations and counseling services; significant predictors differed for each index. One contextual variable (primary care physician density) predicted receipt of screenings and vaccinations. Conclusions Women’s receipt of preventive services was determined primarily by individual-level variables. Different variables predicted receipt of screening and vaccination versus counseling services. A contextual measure, primary care physician density, predicted receipt of preventive screenings and vaccinations. Individual variability in women’s receipt of counseling services is largely explained by psychosocial factors and seeing an obstetrician-gynecologist.

McCall-Hosenfeld, Jennifer S.; Weisman, Carol S.; Camacho, Fabian; Hillemeier, Marianne M.; Chuang, Cynthia H.

2012-01-01

448

Inverting ZCS Switched-Capacitor Bidirectional Converter  

Microsoft Academic Search

The proposed inverting type zero-current switching switched-capacitor (ZCS SC) DC\\/DC converters are a new type of bi-directional power flow control conversion schemes. They possess high efficiency, low EMI emission and current stress features for the proposed quasi-resonant switched-capacitor inverting converters. A family of inverting type zero-current switching switched-capacitor bi-directional converters is presented, which can improve the current stress problem during

Yaung-Shung Lee; Yin-Yuan Chiu; Ming-Wang Cheng

2006-01-01

449

Multilevel Inverters for Electric Vehicle Applications  

Microsoft Academic Search

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 electromagnet ic interference (EMI) and common- mode voltage; and (3) make an EV more accessible\\/safer and open wiring possible for most of

Leon M. Tolbert; Fang Z. Peng; Thomas G. Habetler

2009-01-01

450

Multilevel inverters for electric vehicle applications  

Microsoft Academic Search

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

Leon M. Tolbert; Fang Z. Peng; Thomas G. Habetler

1998-01-01

451

On the Invertibility of Invisible Watermarking Techniques  

Microsoft Academic Search

In this paper we address the invertib ility of invisible wa- termarking schemes for resolving rightful ownerships, and present attacks which can cause confusion to rightful claims. We shall show that non-invertib ility is a necessary but not sufficient condition in resolving ownership disputes. We then definequasi-invertible watermarking schemes, and, present analysis that links invertibility and quasi-invertibility to some classes

S. Carver; Nasir D. Memon; Boon-lock Yeo; Minerva M. Yeung

1997-01-01

452

Switching inverters and converters for power conversion  

US Patent & Trademark Office Database

A switching inverter having two single-ended EF.sub.2 inverter sections coupled together with a shared ground and partially shared tunable resonant network that is coupled to at least one load, wherein each inverter section comprises a switching section, and wherein the shared tunable network section allows independent tuning of an impedance seen by the corresponding switching section thereby independently tuning even and odd harmonics of the switching frequency.

2011-04-12

453

Inverted papilloma in the sphenoethmoidal recess.  

PubMed

Inverted papilloma is a nasal benign tumor that usually arises from the lateral nasal wall, especially from the middle meatus. It has high local invasive likelihood, high recurrence rates and malignancy potential. Sphenoethmoidal recess involvement is rare and is usually due to sphenoid sinus primary disease. In the literature, no case of isolated sphenoethmoidal recess inverted papilloma has been reported yet. The present report describes an exceptional location of inverted papilloma, arising from the sphenoethmoid recess, without involving the sphenoid sinus. PMID:18392518

Kosugi, Eduardo Macoto; Santos, Rodrigo de Paula; Ganança, Fernando Freitas; Tangerina, Rodrigo de Paiva; Suguri, Vinícius Magalhães; Yamaoka, Wellington Yugo; Gregório, Luis Carlos

2008-01-01

454

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, 2010 CFR

...of a Multi-Level Car Complying with Window Location and Staggering Requirements-çç 238.113 and 238.114 2 Figure 2 to Subpart B of Part 238 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL...

2010-10-01

455

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, 2010 CFR

...of a Multi-Level Car Complying with Window Location and Staggering Requirements-çç 238.113 and 238.114 2 Figure 2 to Subpart B of Part 238 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL...

2009-10-01

456

GAD: A 12GS\\/s CMOS 4-bit A\\/D converter for an equalized multi-level link  

Microsoft Academic Search

A 4-bit 12-GSample\\/sec A\\/D converter (GAD) has been fabricated in a 0.25-?m CMOS process to investigate the design of an equalized multi-level link. Clocked differential amplifiers were used to sample the input, followed by high-speed comparators with current-summed offset cancellation. Input bandwidth was measured at 2.5 GHz. Eight 1.5-GSample\\/sec flash A\\/D converters were interleaved to achieve the aggregate sample rate

William Ellersick; Chih-Kong Ken Yang; Mark Horowitz; William Dally

1999-01-01

457

Improvement of the multi-level cell performance by a soft program method in flash memory devices  

NASA Astrophysics Data System (ADS)

A soft program method is proposed for charge-trap flash (CTF) memory devices. By adding a subsequent small positive gate pulse after main Fowler-Nordheim (FN) injection programming, early charge loss is greatly reduced. The multi-level cell performance as well as the initial flat-band voltage (VFB) instability can thereby be improved by removing the trapped electrons at the shallow traps in the blocking oxide layer. The proposed soft program method is a simple but very effective way to improve the fast retention property without changing the memory structure, especially for cases where the ?-value of the blocking oxide is high.

Park, Jong Kyung; Lee, Ki-Hong; Pyi, Seung Ho; Lee, Seok-Hee; Cho, Byung Jin

2014-04-01

458

Familial inverted duplication 7p  

SciTech Connect

A 10-month-old female with developmental delay and failure to thrive was referred for genetic evaluation as part of an adoption assessment. Physical exam showed a mildly beaked nose and clinodactyly, but otherwise nothing remarkable. Chromosome analysis showed an inverted duplication of the p12.2{r_arrow}p13 portion of chromosome 7(46,XX,dup(7)(p13p12.2)). The proposita`s older brother, mother, and grandmother were cognitively delayed and had the same chromosome 7 duplication. A review of the literature showed no other cases involving this exact duplication. 5 refs., 3 figs., 1 tab.

Schaefer, G.B.; Novak, K.; Steele, D. [Univ. of Nebraska Medical School, Omaha, NE (United States)] [and others

1995-03-27

459

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

460

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

461

Species composition of a soil invertebrate multi-species test system determines the level of ecotoxicity.  

PubMed

A soil multi-species, SMS, experimental test system consisting of the natural microbial community, five collembolan species and a predatory mite along with either Enchytraeus crypticus or the earthworm Eisenia fetida were exposed to ?-cypermethrin. A comparison of the performance of these two types of SMSs is given to aid the development of a standard test system. E. fetida had a positive effect on the majority of the species, reducing the negative insecticide effect. E. fetida affected the species sensitivity and decreased the degradation of the insecticide due to the organic matter incorporation of earthworm food. After 8 weeks, the EC50 was 0.76 mg kg(-1) for enchytraeids and ranged between 2.7 and 18.9 mg kg(-1) for collembolans, more sensitive than previously observed with single species. Changes observed in the community structure and function illustrates the strength of a multi-species test system as an ecotoxicological tool compared to single species tests. PMID:24201037

Sechi, Valentina; D'Annibale, Alessandra; Maraldo, Kristine; Johansen, Anders; Bossi, Rossana; Jensen, John; Krogh, Paul Henning

2014-01-01

462

Harmonics Study and Comparison of Z-source Inverter with Traditional Inverters  

Microsoft Academic Search

This paper presents an Impedance Source Inverter for A.C electrical drives. The impedance source inverter employs a unique impedance network couple with inverter main circuit and rectifier. By controlling the shoot-through duty cycle, the z-source inverter system using MOSFETS provide ride-through capability during voltage sags, reduces line harmonics, improves power factor and high reliability, and extends output voltage range. Analysis,

B. Justus Rabi; R. Arumugam

2005-01-01

463

A Class of Quasi-Z-Source Inverters  

Microsoft Academic Search

In this paper, theoretical results are shown for several novel inverters. These inverters are similar to the Z- source inverters presented in previous works, but have several advantages, including in some combination; lower component ratings, reduced source stress, reduced component count and simplified control strategies. Like the Z-Source inverter, these inverters are particularly suited for applications which require a large

Joel Anderson; F. Z. Peng

2008-01-01

464

Inverted OLEDs for flexible displays  

NASA Astrophysics Data System (ADS)

We reported a couple of methods to improve electron injection from the ITO electrode, thereby to fabricate efficient inverted bottom emission organic light emitting diodes (IBOLEDs). The first method is to use an n-doped electron transporting layer (ETL) as the electron inj