Three-Phase Cascaded Multilevel Inverter Using Power Cells With Two Inverter Legs in Series

NARCIS (Netherlands)

Waltrich, G.; Barbi, I.

2010-01-01

In this paper, a modular three-phase multilevel inverter specially suited for electrical drive applications is proposed. Unlike the cascaded H-bridge inverter, this topology is based on power cells connected in cascade using two inverter legs in series. A detailed analysis of the structure and the

A New Structure Based on Cascaded Multilevel Converter for Variable Speed Wind Turbine

DEFF Research Database (Denmark)

Deng, Fujin; Chen, Zhe

2010-01-01

An alternative structure for variable speed wind turbine, using multiple permanent magnet synchronous generators (PMSGs) drive-train configuration and cascaded multilevel converter is proposed in this paper. This study presents a power electronic solution for the wind turbine. A transformer......-less cascaded multilevel converter interface based on PMSGs is developed to synthesize a desired high ac sinusoidal output voltage. The benefits of high power and high ac voltage make this structure possible to be applied in the wind power generation. In addition, the bulky transformer could be omitted....... A simulation model of 10 MW variable speed wind turbine based on PMSGs developed in PSCAD/EMTDC is presented. The dynamic performance of grid-connected wind turbine is analyzed. Simulation results shows that the proposed structure may be attractive in wind power generation....

Artifact removal from EEG signals using adaptive filters in cascade

Science.gov (United States)

Garcés Correa, A.; Laciar, E.; Patiño, H. D.; Valentinuzzi, M. E.

2007-11-01

Artifacts in EEG (electroencephalogram) records are caused by various factors, like line interference, EOG (electro-oculogram) and ECG (electrocardiogram). These noise sources increase the difficulty in analyzing the EEG and to obtaining clinical information. For this reason, it is necessary to design specific filters to decrease such artifacts in EEG records. In this paper, a cascade of three adaptive filters based on a least mean squares (LMS) algorithm is proposed. The first one eliminates line interference, the second adaptive filter removes the ECG artifacts and the last one cancels EOG spikes. Each stage uses a finite impulse response (FIR) filter, which adjusts its coefficients to produce an output similar to the artifacts present in the EEG. The proposed cascade adaptive filter was tested in five real EEG records acquired in polysomnographic studies. In all cases, line-frequency, ECG and EOG artifacts were attenuated. It is concluded that the proposed filter reduces the common artifacts present in EEG signals without removing significant information embedded in these records.

Artifact removal from EEG signals using adaptive filters in cascade

International Nuclear Information System (INIS)

Garces Correa, A; Laciar, E; Patino, H D; Valentinuzzi, M E

2007-01-01

Artifacts in EEG (electroencephalogram) records are caused by various factors, like line interference, EOG (electro-oculogram) and ECG (electrocardiogram). These noise sources increase the difficulty in analyzing the EEG and to obtaining clinical information. For this reason, it is necessary to design specific filters to decrease such artifacts in EEG records. In this paper, a cascade of three adaptive filters based on a least mean squares (LMS) algorithm is proposed. The first one eliminates line interference, the second adaptive filter removes the ECG artifacts and the last one cancels EOG spikes. Each stage uses a finite impulse response (FIR) filter, which adjusts its coefficients to produce an output similar to the artifacts present in the EEG. The proposed cascade adaptive filter was tested in five real EEG records acquired in polysomnographic studies. In all cases, line-frequency, ECG and EOG artifacts were attenuated. It is concluded that the proposed filter reduces the common artifacts present in EEG signals without removing significant information embedded in these records

Artifact removal from EEG signals using adaptive filters in cascade

Energy Technology Data Exchange (ETDEWEB)

Garces Correa, A [Gabinete de TecnologIa Medica, Facultad de Ingenieria, Universidad Nacional de San Juan (Argentina); Laciar, E [Gabinete de TecnologIa Medica, Facultad de Ingenieria, Universidad Nacional de San Juan (Argentina); Patino, H D [Instituto de Automatica, Facultad de Ingenieria, Universidad Nacional de San Juan (Argentina); Valentinuzzi, M E [Instituto Superior de Investigaciones Biologicas (INSIBIO), UNT-CONICET, Tucuman (Argentina)

2007-11-15

Artifacts in EEG (electroencephalogram) records are caused by various factors, like line interference, EOG (electro-oculogram) and ECG (electrocardiogram). These noise sources increase the difficulty in analyzing the EEG and to obtaining clinical information. For this reason, it is necessary to design specific filters to decrease such artifacts in EEG records. In this paper, a cascade of three adaptive filters based on a least mean squares (LMS) algorithm is proposed. The first one eliminates line interference, the second adaptive filter removes the ECG artifacts and the last one cancels EOG spikes. Each stage uses a finite impulse response (FIR) filter, which adjusts its coefficients to produce an output similar to the artifacts present in the EEG. The proposed cascade adaptive filter was tested in five real EEG records acquired in polysomnographic studies. In all cases, line-frequency, ECG and EOG artifacts were attenuated. It is concluded that the proposed filter reduces the common artifacts present in EEG signals without removing significant information embedded in these records.

Multi-level cascaded DC/DC converters for PV applications

Directory of Open Access Journals (Sweden)

Ahmed A.A. Hafez

2015-12-01

Full Text Available A robust multi-level cascaded DC/DC system for Photovoltaic (PV application is advised in this article. There are three PV generators, each is coupled to a half-bridge buck cell. Each PV-generator–buck-converter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal and abnormal conditions was comprehensively investigated. Internal Model Control (IMC technique was adopted for tuning the controllers. An elaborate switching modulation strategy was used to reduce the current ripple and inductor size, while maintaining high efficiency. Annotative, simple and robust remedial strategies were proposed to mitigate different anticipated faults. Comprehensive simulation results in Matlab environment were illustrated for corroborating the performance of the advised cascaded DC/DC system under normal/abnormal conditions. The proposed system enjoys the merits of independency, reduced volumetric dimensions and improved efficiency. Furthermore, the system is inherently fault-tolerant.

DSP Control of Line Hybrid Active Filter

DEFF Research Database (Denmark)

Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.

2005-01-01

Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter...... is studied for current harmonic compensation. The hybrid filter is formed by a single tuned Le filter and a small-rated power active filter, which are directly connected in series without any matching transformer. Thus the required rating of the active filter is much smaller than a conventional standalone...... active filter. Simulation and experimental results obtained in laboratory confirmed the validity and effectiveness of the control....

THD Minimization from H-Bridge Cascaded Multilevel Inverter Using Particle Swarm Optimization Technique

Directory of Open Access Journals (Sweden)

MUDASIR AHMED MEMON

2017-01-01

Full Text Available In this paper, PSO (Particle Swarm Optimization based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform.

THD minimization from h-bridge cascaded multilevel inverter using particle swarm optimization technique

International Nuclear Information System (INIS)

Memon, M.A.; Memon, S.; Khan, S.

2017-01-01

In this paper, PSO (Particle Swarm Optimization) based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion) and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform. (author)

Hybrid Filter Membrane

Science.gov (United States)

Laicer, Castro; Rasimick, Brian; Green, Zachary

2012-01-01

Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

Grid Connection of Wave Power Farm Using an N-Level Cascaded H-Bridge Multilevel Inverter

Directory of Open Access Journals (Sweden)

Rickard Ekström

2013-01-01

Full Text Available An N-level cascaded H-bridge multilevel inverter is proposed for grid connection of large wave power farms. The point-absorber wave energy converters are individually rectified and used as isolated DC-sources. The variable power characteristics of the wave energy converters are discussed, and a method of mitigating this issue is demonstrated. The complete power control system is given in detail and has been experimentally verified for a single-phase setup of the 9-level inverter. Theoretical expressions of the power sharing between multilevel cells are derived and show good correspondence with the experimental results.

Cascaded holographic polymer reflection grating filters for optical-code-division multiple-access applications.

Science.gov (United States)

Kostuk, Raymond K; Maeda, Wendi; Chen, Chia-Hung; Djordjevic, Ivan; Vasic, Bane

2005-12-10

We evaluate the use of edge-illuminated holographic Bragg filters formed in phenanthrenequinone-doped poly(methyl methacrylate) for optical-code-division multiple-access (OCDMA) coding and decoding applications. Experimental cascaded Bragg filters are formed to select two different wavelengths with a fixed distance between the gratings and are directly coupled to a fiber-measurement system. The configuration and tolerances of the cascaded gratings are shown to be practical for time-wavelength OCDMA applications.

Hybrid dual gate ferroelectric memory for multilevel information storage

KAUST Repository

Khan, Yasser; Caraveo-Frescas, Jesus Alfonso; Alshareef, Husam N.

2015-01-01

Here, we report hybrid organic/inorganic ferroelectric memory with multilevel information storage using transparent p-type SnO semiconductor and ferroelectric P(VDF-TrFE) polymer. The dual gate devices include a top ferroelectric field

Multilevel Hybrid Chernoff Tau-Leap

KAUST Repository

Moraes, Alvaro

2016-01-06

Markovian pure jump processes can model many phenomena, e.g. chemical reactions at molecular level, protein transcription and translation, spread of epidemics diseases in small populations and in wireless communication networks, among many others. In this work [6] we present a novel multilevel algorithm for the Chernoff-based hybrid tauleap algorithm. This variance reduction technique allows us to: (a) control the global exit probability of any simulated trajectory, (b) obtain accurate and computable estimates for the expected value of any smooth observable of the process with minimal computational work.

Multilevel Hybrid Chernoff Tau-Leap

KAUST Repository

Moraes, Alvaro

2015-01-07

Markovian pure jump processes can model many phenomena, e.g. chemical reactions at molecular level, protein transcription and translation, spread of epidemics diseases in small populations and in wireless communication networks, among many others. In this work [6] we present a novel multilevel algorithm for the Chernoff-based hybrid tauleap algorithm. This variance reduction technique allows us to: (a) control the global exit probability of any simulated trajectory, (b) obtain accurate and computable estimates for the expected value of any smooth observable of the process with minimal computational work.

Multilevel Hybrid Chernoff Tau-Leap

KAUST Repository

Moraes, Alvaro

2014-01-06

Markovian pure jump processes can model many phenomena, e.g. chemical reactions at molecular level, protein transcription and translation, spread of epidemics diseases in small populations and in wireless communication networks, among many others. In this work [6] we present a novel multilevel algorithm for the Chernoff-based hybrid tauleap algorithm. This variance reduction technique allows us to: (a) control the global exit probability of any simulated trajectory, (b) obtain accurate and computable estimates for the expected value of any smooth observable of the process with minimal computational work.

Synthesis of Cascadable DDCC-Based Universal Filter Using NAM

Directory of Open Access Journals (Sweden)

Huu-Duy Tran

2015-08-01

Full Text Available A novel systematic approach for synthesizing DDCC-based voltage-mode biquadratic universal filters is proposed. The DDCCs are described by infinity-variables’ models of nullor-mirror elements which can be used in the nodal admittance matrix expansion process. Applying the proposed method, the obtained 12 equivalent filters offer the following features: multi-input and two outputs, realization of all five standard filter functions, namely lowpass, bandpass, highpass, notch and allpass, high-input impedance, employing only grounded capacitors and resistors, orthogonal controllability between pole frequency and quality factor, and cascadable, low active and passive sensitivities. The workability of some synthesized filters is verified by HSPICE simulations to demonstrate the feasibility of the proposed method.

Multilevel Converter by Cascading Two-Level Three-Phase Voltage Source Converter

Directory of Open Access Journals (Sweden)

Abdullrahman A. Al-Shamma’a

2018-04-01

Full Text Available This paper proposes a topology using isolated, cascaded multilevel voltage source converters (VSCs and employing two-winding magnetic elements for high-power applications. The proposed topology synthesizes 6 two-level, three-phase VSCs, so the power capability of the presented converter is six times the capability of each VSC module. The characteristics of the proposed topology are demonstrated through analyzing its current relationships, voltage relationships and power capability in detail. The power rating is equally shared among the VSC modules without the need for a sharing algorithm; thus, the converter operates as a single three-phase VSC. The comparative analysis with classical neutral-point clamped, flying capacitor and cascaded H-bridge exhibits the superior features of fewer insulated gate bipolar transistors (IGBTs, capacitor requirement and fewer diodes. To validate the theoretical performance of the proposed converter, it is simulated in a MATLAB/Simulink environment and the results are experimentally demonstrated using a laboratory prototype.

Fault-Tolerant Control for a Flexible Group Battery Energy Storage System Based on Cascaded Multilevel Converters

Directory of Open Access Journals (Sweden)

Junhong Song

2018-01-01

Full Text Available A flexible group battery energy storage system (FGBESS based on cascaded multilevel converters is attractive for renewable power generation applications because of its high modularity and high power quality. However, reliability is one of the most important issues and the system may suffer from great financial loss after fault occurs. In this paper, based on conventional fundamental phase shift compensation and third harmonic injection, a hybrid compensation fault-tolerant method is proposed to improve the post-fault performance in the FGBESS. By adjusting initial phase offset and amplitude of injected component, the optimal third harmonic injection is generated in an asymmetric system under each faulty operation. Meanwhile, the optimal redundancy solution under each fault condition is also elaborated comprehensively with a comparison of the presented three fault-tolerant strategies. This takes full advantage of battery utilization and minimizes the loss of energy capacity. Finally, the effectiveness and feasibility of the proposed methods are verified by results obtained from simulations and a 10 kW experimental platform.

Vehicle Sideslip Angle Estimation Based on Hybrid Kalman Filter

Directory of Open Access Journals (Sweden)

Jing Li

2016-01-01

Full Text Available Vehicle sideslip angle is essential for active safety control systems. This paper presents a new hybrid Kalman filter to estimate vehicle sideslip angle based on the 3-DoF nonlinear vehicle dynamic model combined with Magic Formula tire model. The hybrid Kalman filter is realized by combining square-root cubature Kalman filter (SCKF, which has quick convergence and numerical stability, with square-root cubature based receding horizon Kalman FIR filter (SCRHKF, which has robustness against model uncertainty and temporary noise. Moreover, SCKF and SCRHKF work in parallel, and the estimation outputs of two filters are merged by interacting multiple model (IMM approach. Experimental results show the accuracy and robustness of the hybrid Kalman filter.

Multi-parameter studies of environmental aerosols with cascade track filters

International Nuclear Information System (INIS)

Ensinger, W.; Guo, S.-L.; Vater, P.; Brandt, R.

2005-01-01

Aerosols in the air in a factory processing nuclear reactor fuel material were collected by using cascade Kapton track filters with outer pore sizes of 12.8, 4.0 and 1.0μm consecutively and a conventional filter of glass fiber being behind to collect all aerosol particles left-over. The volume of air passed through the filters was measured by a flow meter. The weight of aerosol particles on each filter was obtained by the weight difference of the filter before and after collection of aerosol particles. α-activity on each filter was measured with a methane gas flow proportional counter. The sizes and elemental compositions of aerosol particles on the filters were analyzed by using a scanning electron microscope and an electron microprobe. Special attention was given to uranium aerosol particles. The median sizes of uranium aerosol particles were obtained being 1.97, 1.33 and 0.72μm on the first, second and third filter, respectively. The median size of all the uranium aerosol particles on the three track filters was 1.25μm

A hybrid plasmonic waveguide terahertz quantum cascade laser

Energy Technology Data Exchange (ETDEWEB)

Degl' Innocenti, Riccardo, E-mail: rd448@cam.ac.uk; Shah, Yash D.; Wallis, Robert; Klimont, Adam; Ren, Yuan; Jessop, David S.; Beere, Harvey E.; Ritchie, David A. [Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2015-02-23

We present the realization of a quantum cascade laser emitting at around 2.85 THz, based on a hybrid plasmonic waveguide with a low refractive index dielectric cladding. This hybrid waveguide design allows the performance of a double-metal waveguide to be retained, while improving the emission far-field. A set of lasers based on the same active region material were fabricated with different metal layer thicknesses. A detailed characterization of the performance of these lasers revealed that there is an optimal trade-off that yields the best far-field emission and the maximum temperature of operation. By exploiting the pure plasmonic mode of these waveguides, the standard operation conditions of a double-metal quantum cascade laser were retrieved, such that the maximum operating temperature of these devices is not affected by the process. These results pave the way to realizing a class of integrated devices working in the terahertz range which could be further exploited to fabricate terahertz on-chip circuitry.

Fault diagnosis method based on FFT-RPCA-SVM for Cascaded-Multilevel Inverter.

Science.gov (United States)

Wang, Tianzhen; Qi, Jie; Xu, Hao; Wang, Yide; Liu, Lei; Gao, Diju

2016-01-01

Thanks to reduced switch stress, high quality of load wave, easy packaging and good extensibility, the cascaded H-bridge multilevel inverter is widely used in wind power system. To guarantee stable operation of system, a new fault diagnosis method, based on Fast Fourier Transform (FFT), Relative Principle Component Analysis (RPCA) and Support Vector Machine (SVM), is proposed for H-bridge multilevel inverter. To avoid the influence of load variation on fault diagnosis, the output voltages of the inverter is chosen as the fault characteristic signals. To shorten the time of diagnosis and improve the diagnostic accuracy, the main features of the fault characteristic signals are extracted by FFT. To further reduce the training time of SVM, the feature vector is reduced based on RPCA that can get a lower dimensional feature space. The fault classifier is constructed via SVM. An experimental prototype of the inverter is built to test the proposed method. Compared to other fault diagnosis methods, the experimental results demonstrate the high accuracy and efficiency of the proposed method. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

An Unscented Kalman-Particle Hybrid Filter for Space Object Tracking

Science.gov (United States)

Raihan A. V, Dilshad; Chakravorty, Suman

2018-03-01

Optimal and consistent estimation of the state of space objects is pivotal to surveillance and tracking applications. However, probabilistic estimation of space objects is made difficult by the non-Gaussianity and nonlinearity associated with orbital mechanics. In this paper, we present an unscented Kalman-particle hybrid filtering framework for recursive Bayesian estimation of space objects. The hybrid filtering scheme is designed to provide accurate and consistent estimates when measurements are sparse without incurring a large computational cost. It employs an unscented Kalman filter (UKF) for estimation when measurements are available. When the target is outside the field of view (FOV) of the sensor, it updates the state probability density function (PDF) via a sequential Monte Carlo method. The hybrid filter addresses the problem of particle depletion through a suitably designed filter transition scheme. To assess the performance of the hybrid filtering approach, we consider two test cases of space objects that are assumed to undergo full three dimensional orbital motion under the effects of J 2 and atmospheric drag perturbations. It is demonstrated that the hybrid filters can furnish fast, accurate and consistent estimates outperforming standard UKF and particle filter (PF) implementations.

Multi-floor cascading ferroelectric nanostructures: multiple data writing-based multi-level non-volatile memory devices

Science.gov (United States)

Hyun, Seung; Kwon, Owoong; Lee, Bom-Yi; Seol, Daehee; Park, Beomjin; Lee, Jae Yong; Lee, Ju Hyun; Kim, Yunseok; Kim, Jin Kon

2016-01-01

Multiple data writing-based multi-level non-volatile memory has gained strong attention for next-generation memory devices to quickly accommodate an extremely large number of data bits because it is capable of storing multiple data bits in a single memory cell at once. However, all previously reported devices have failed to store a large number of data bits due to the macroscale cell size and have not allowed fast access to the stored data due to slow single data writing. Here, we introduce a novel three-dimensional multi-floor cascading polymeric ferroelectric nanostructure, successfully operating as an individual cell. In one cell, each floor has its own piezoresponse and the piezoresponse of one floor can be modulated by the bias voltage applied to the other floor, which means simultaneously written data bits in both floors can be identified. This could achieve multi-level memory through a multiple data writing process.Multiple data writing-based multi-level non-volatile memory has gained strong attention for next-generation memory devices to quickly accommodate an extremely large number of data bits because it is capable of storing multiple data bits in a single memory cell at once. However, all previously reported devices have failed to store a large number of data bits due to the macroscale cell size and have not allowed fast access to the stored data due to slow single data writing. Here, we introduce a novel three-dimensional multi-floor cascading polymeric ferroelectric nanostructure, successfully operating as an individual cell. In one cell, each floor has its own piezoresponse and the piezoresponse of one floor can be modulated by the bias voltage applied to the other floor, which means simultaneously written data bits in both floors can be identified. This could achieve multi-level memory through a multiple data writing process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07377d

Hybrid Models of Alternative Current Filter for Hvdc

Directory of Open Access Journals (Sweden)

Ufa Ruslan A.

2017-01-01

Full Text Available Based on a hybrid simulation concept of HVDC, the developed hybrid AC filter models, providing the sufficiently full and adequate modeling of all single continuous spectrum of quasi-steady-state and transient processes in the filter, are presented. The obtained results suggest that usage of the hybrid simulation approach is carried out a methodically accurate with guaranteed instrumental error solution of differential equation systems of mathematical models of HVDC.

Hybrid Cascading Outage Analysis of Extreme Events with Optimized Corrective Actions

Energy Technology Data Exchange (ETDEWEB)

Vallem, Mallikarjuna R.; Vyakaranam, Bharat GNVSR; Holzer, Jesse T.; Samaan, Nader A.; Makarov, Yuri V.; Diao, Ruisheng; Huang, Qiuhua; Ke, Xinda

2017-10-19

Power system are vulnerable to extreme contingencies (like an outage of a major generating substation) that can cause significant generation and load loss and can lead to further cascading outages of other transmission facilities and generators in the system. Some cascading outages are seen within minutes following a major contingency, which may not be captured exclusively using the dynamic simulation of the power system. The utilities plan for contingencies either based on dynamic or steady state analysis separately which may not accurately capture the impact of one process on the other. We address this gap in cascading outage analysis by developing Dynamic Contingency Analysis Tool (DCAT) that can analyze hybrid dynamic and steady state behavior of the power system, including protection system models in dynamic simulations, and simulating corrective actions in post-transient steady state conditions. One of the important implemented steady state processes is to mimic operator corrective actions to mitigate aggravated states caused by dynamic cascading. This paper presents an Optimal Power Flow (OPF) based formulation for selecting corrective actions that utility operators can take during major contingency and thus automate the hybrid dynamic-steady state cascading outage process. The improved DCAT framework with OPF based corrective actions is demonstrated on IEEE 300 bus test system.

Digital Simulation of a Hybrid Active Filter - An Active Filter in Series with a Shunt Passive Filter

OpenAIRE

Sitaram, Mahesh I; Padiyar, KR; Ramanarayanan, V

1998-01-01

Active filters have long been in use for the filtering of power system load harmonics. In this paper, the digital simulation results of a hybrid active power filter system for a rectifier load are presented. The active filter is used for filtering higher order harmonics as the dominant harmonics are filtered by the passive filter. This reduces the rating of the active filter significantly. The DC capacitor voltage of the active filter is controlled using a PI controller.

Multilevel hybrid Chernoff tau-leap

KAUST Repository

Moraes, Alvaro

2015-04-08

In this work, we extend the hybrid Chernoff tau-leap method to the multilevel Monte Carlo (MLMC) setting. Inspired by the work of Anderson and Higham on the tau-leap MLMC method with uniform time steps, we develop a novel algorithm that is able to couple two hybrid Chernoff tau-leap paths at different levels. Using dual-weighted residual expansion techniques, we also develop a new way to estimate the variance of the difference of two consecutive levels and the bias. This is crucial because the computational work required to stabilize the coefficient of variation of the sample estimators of both quantities is often unaffordable for the deepest levels of the MLMC hierarchy. Our method bounds the global computational error to be below a prescribed tolerance, TOL, within a given confidence level. This is achieved with nearly optimal computational work. Indeed, the computational complexity of our method is of order O(TOL−2), the same as with an exact method, but with a smaller constant. Our numerical examples show substantial gains with respect to the previous single-level approach and the Stochastic Simulation Algorithm.

Multilevel hybrid Chernoff tau-leap

KAUST Repository

Moraes, Alvaro; Tempone, Raul; Vilanova, Pedro

2015-01-01

In this work, we extend the hybrid Chernoff tau-leap method to the multilevel Monte Carlo (MLMC) setting. Inspired by the work of Anderson and Higham on the tau-leap MLMC method with uniform time steps, we develop a novel algorithm that is able to couple two hybrid Chernoff tau-leap paths at different levels. Using dual-weighted residual expansion techniques, we also develop a new way to estimate the variance of the difference of two consecutive levels and the bias. This is crucial because the computational work required to stabilize the coefficient of variation of the sample estimators of both quantities is often unaffordable for the deepest levels of the MLMC hierarchy. Our method bounds the global computational error to be below a prescribed tolerance, TOL, within a given confidence level. This is achieved with nearly optimal computational work. Indeed, the computational complexity of our method is of order O(TOL−2), the same as with an exact method, but with a smaller constant. Our numerical examples show substantial gains with respect to the previous single-level approach and the Stochastic Simulation Algorithm.

A cascaded two-step Kalman filter for estimation of human body segment orientation using MEMS-IMU.

Science.gov (United States)

Zihajehzadeh, S; Loh, D; Lee, M; Hoskinson, R; Park, E J

2014-01-01

Orientation of human body segments is an important quantity in many biomechanical analyses. To get robust and drift-free 3-D orientation, raw data from miniature body worn MEMS-based inertial measurement units (IMU) should be blended in a Kalman filter. Aiming at less computational cost, this work presents a novel cascaded two-step Kalman filter orientation estimation algorithm. Tilt angles are estimated in the first step of the proposed cascaded Kalman filter. The estimated tilt angles are passed to the second step of the filter for yaw angle calculation. The orientation results are benchmarked against the ones from a highly accurate tactical grade IMU. Experimental results reveal that the proposed algorithm provides robust orientation estimation in both kinematically and magnetically disturbed conditions.

Advanced configuration of hybrid passive filter for reactive power and harmonic compensation.

Science.gov (United States)

Kececioglu, O Fatih; Acikgoz, Hakan; Sekkeli, Mustafa

2016-01-01

Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. Simulation results show that performance of reactive power and harmonic compensation with advanced hybrid passive filter is better than conventional hybrid passive filters.

Filtering in Hybrid Dynamic Bayesian Networks

Science.gov (United States)

Andersen, Morten Nonboe; Andersen, Rasmus Orum; Wheeler, Kevin

2000-01-01

We implement a 2-time slice dynamic Bayesian network (2T-DBN) framework and make a 1-D state estimation simulation, an extension of the experiment in (v.d. Merwe et al., 2000) and compare different filtering techniques. Furthermore, we demonstrate experimentally that inference in a complex hybrid DBN is possible by simulating fault detection in a watertank system, an extension of the experiment in (Koller & Lerner, 2000) using a hybrid 2T-DBN. In both experiments, we perform approximate inference using standard filtering techniques, Monte Carlo methods and combinations of these. In the watertank simulation, we also demonstrate the use of 'non-strict' Rao-Blackwellisation. We show that the unscented Kalman filter (UKF) and UKF in a particle filtering framework outperform the generic particle filter, the extended Kalman filter (EKF) and EKF in a particle filtering framework with respect to accuracy in terms of estimation RMSE and sensitivity with respect to choice of network structure. Especially we demonstrate the superiority of UKF in a PF framework when our beliefs of how data was generated are wrong. Furthermore, we investigate the influence of data noise in the watertank simulation using UKF and PFUKD and show that the algorithms are more sensitive to changes in the measurement noise level that the process noise level. Theory and implementation is based on (v.d. Merwe et al., 2000).

Comparison of zero-sequence injection methods in cascaded H-bridge multilevel converters for large-scale photovoltaic integration

DEFF Research Database (Denmark)

Yu, Yifan; Konstantinou, Georgios; Townsend, Christopher David

2017-01-01

to maintain three-phase balanced grid currents with unbalanced power generation. This study theoretically compares power balance capabilities of various zero-sequence injection methods based on two metrics which can be easily generalised for all CHB applications to PV systems. Experimental results based......Photovoltaic (PV) power generation levels in the three phases of a multilevel cascaded H-bridge (CHB) converter can be significantly unbalanced, owing to different irradiance levels and ambient temperatures over a large-scale solar PV power plant. Injection of a zero-sequence voltage is required...... on a 430 V, 10 kW, three-phase, seven-level cascaded H-bridge converter prototype confirm superior performance of the optimal zero-sequence injection technique....

Assay of hybrid ribonuclease using a membrane filter-immobilized synthetic hybrid: application to the human leukemic cell

International Nuclear Information System (INIS)

Papaphilis, A.D.; Kamper, E.F.

1985-01-01

A method for assaying hybrid ribonuclease has been devised which utilizes as substrate the synthetic hybrid [ 3 H]polyriboadenylic acid [poly(rA)]:polydeoxythymidylic acid [poly(dT)] immobilized on the solid matrix of nitrocellulose filters. The hybridization on filter of [ 3 H]poly(rA) to poly(dT) has been explored in terms of efficacy of the process and the response of the product to RNase H. A pulse of uv irradiation of poly(dT) while in dry state on the filter increased its firm binding to the filter in a concentration-dependent manner, resulting in a concomitant increase of the yield of hybrid formation. The filter-immobilized hybrid was 95% resistant to RNase A but sensitive to RNase H. When stored in toluene in the cold the hybrid maintained its stability for over 6 months, as judged by its resistance to RNase A. The method offers a number of advantages over assays that use solution hybrids as substrates and was readily applicable in the screening of leukemic patients, in the leukocytes of which it has demonstrated increased RNase H levels

Hybrid dual gate ferroelectric memory for multilevel information storage

KAUST Repository

Khan, Yasser

2015-01-01

Here, we report hybrid organic/inorganic ferroelectric memory with multilevel information storage using transparent p-type SnO semiconductor and ferroelectric P(VDF-TrFE) polymer. The dual gate devices include a top ferroelectric field-effect transistor (FeFET) and a bottom thin-film transistor (TFT). The devices are all fabricated at low temperatures (∼200°C), and demonstrate excellent performance with high hole mobility of 2.7 cm2 V-1 s-1, large memory window of ∼18 V, and a low sub-threshold swing ∼-4 V dec-1. The channel conductance of the bottom-TFT and the top-FeFET can be controlled independently by the bottom and top gates, respectively. The results demonstrate multilevel nonvolatile information storage using ferroelectric memory devices with good retention characteristics.

Control Strategy of Active Power Filter Based on Modular Multilevel Converter

Science.gov (United States)

Xie, Xifeng

2018-03-01

To improve the capacity, pressure resistance and the equivalent switching frequency of active power filter (APF), a control strategy of APF based on Modular Multilevel Converter (MMC) is presented. In this Control Strategy, the indirect current control method is used to achieve active current and reactive current decoupling control; Voltage Balance Control Strategy is to stabilize sub-module capacitor voltage, the predictive current control method is used to Track and control of harmonic currents. As a result, the harmonic current is restrained, and power quality is improved. Finally, the simulation model of active power filter controller based on MMC is established in Matlab/Simulink, the simulation proves that the proposed strategy is feasible and correct.

Design of High-Voltage Switch-Mode Power Amplifier Based on Digital-Controlled Hybrid Multilevel Converter

Directory of Open Access Journals (Sweden)

Yanbin Hou

2016-01-01

Full Text Available Compared with conventional Class-A, Class-B, and Class-AB amplifiers, Class-D amplifier, also known as switching amplifier, employs pulse width modulation (PWM technology and solid-state switching devices, capable of achieving much higher efficiency. However, PWM-based switching amplifier is usually designed for low-voltage application, offering a maximum output voltage of several hundred Volts. Therefore, a step-up transformer is indispensably adopted in PWM-based Class-D amplifier to produce high-voltage output. In this paper, a switching amplifier without step-up transformer is developed based on digital pulse step modulation (PSM and hybrid multilevel converter. Under the control of input signal, cascaded power converters with separate DC sources operate in PSM switch mode to directly generate high-voltage and high-power output. The relevant topological structure, operating principle, and design scheme are introduced. Finally, a prototype system is built, which can provide power up to 1400 Watts and peak voltage up to ±1700 Volts. And the performance, including efficiency, linearity, and distortion, is evaluated by experimental tests.

State of Charge Balancing Control of a Multi-Functional Battery Energy Storage System Based on a 11-Level Cascaded Multilevel PWM Converter

DEFF Research Database (Denmark)

Wang, Songcen; Teodorescu, Remus; Máthé, Lászlo

2015-01-01

This paper focuses on modeling and SOC (State of Charge) balancing control of lithium-ion battery energy storage system based on cascaded multilevel converter for both grid integration and electric vehicle propulsion applications. The equivalent electrical circuit model of lithium-ion battery...

Cascaded Kalman and particle filters for photogrammetry based gyroscope drift and robot attitude estimation.

Science.gov (United States)

Sadaghzadeh N, Nargess; Poshtan, Javad; Wagner, Achim; Nordheimer, Eugen; Badreddin, Essameddin

2014-03-01

Based on a cascaded Kalman-Particle Filtering, gyroscope drift and robot attitude estimation method is proposed in this paper. Due to noisy and erroneous measurements of MEMS gyroscope, it is combined with Photogrammetry based vision navigation scenario. Quaternions kinematics and robot angular velocity dynamics with augmented drift dynamics of gyroscope are employed as system state space model. Nonlinear attitude kinematics, drift and robot angular movement dynamics each in 3 dimensions result in a nonlinear high dimensional system. To reduce the complexity, we propose a decomposition of system to cascaded subsystems and then design separate cascaded observers. This design leads to an easier tuning and more precise debugging from the perspective of programming and such a setting is well suited for a cooperative modular system with noticeably reduced computation time. Kalman Filtering (KF) is employed for the linear and Gaussian subsystem consisting of angular velocity and drift dynamics together with gyroscope measurement. The estimated angular velocity is utilized as input of the second Particle Filtering (PF) based observer in two scenarios of stochastic and deterministic inputs. Simulation results are provided to show the efficiency of the proposed method. Moreover, the experimental results based on data from a 3D MEMS IMU and a 3D camera system are used to demonstrate the efficiency of the method. © 2013 ISA Published by ISA All rights reserved.

Electrically heated particulate filter regeneration methods and systems for hybrid vehicles

Science.gov (United States)

Gonze, Eugene V.; Paratore, Jr., Michael J.

2010-10-12

A control system for controlling regeneration of a particulate filter for a hybrid vehicle is provided. The system generally includes a regeneration module that controls current to the particulate filter to initiate regeneration. An engine control module controls operation of an engine of the hybrid vehicle based on the control of the current to the particulate filter.

Turbulence-cascade interaction noise using an advanced digital filter method

OpenAIRE

Gea Aguilera, Fernando; Gill, James; Zhang, Xin; Nodé-Langlois, Thomas

2016-01-01

Fan wakes interacting with outlet guide vanes is a major source of noise in modern turbofan engines. In order to study this source of noise, the current work presents two-dimensional simulations of turbulence-cascade interaction noise using a computational aeroacoustic methodology. An advanced digital filter method is used for the generation of isotropic synthetic turbulence in a linearised Euler equation solver. A parameter study is presented to assess the influence of airfoil thickness, mea...

Hybrid Non-Isolated and Non Inverting Nx Interleaved DC-DC Multilevel Boost Converter for Renewable Energy Applications

DEFF Research Database (Denmark)

Bhaskar, Mahajan Sagar; Kulkarni, Rishi M.; Padmanaban, Sanjeevi Kumar

2016-01-01

In this paper hybrid non isolated/ non inverting Nx interleaved DC-DC multilevel Boost Converter for renewable energy applications is presented. The presented hybrid topology is derived from the conventional interleaved converter and the Nx Multilevel boost converter. In renewable energy...... applications, generated energy cannot be directly used at application end. In most of the cases it needs to be stepped up with DC-DC converter at operating voltage levels as per the requirement of the application. Though conventional boost converter can theoretically be used for this purpose, but obtaining...

Hybrid Multilevel Monte Carlo Simulation of Stochastic Reaction Networks

KAUST Repository

Moraes, Alvaro

2015-01-01

even more, we want to achieve this objective with near optimal computational work. We first introduce a hybrid path-simulation scheme based on the well-known stochastic simulation algorithm (SSA)[3] and the tau-leap method [2]. Then, we introduce a Multilevel Monte Carlo strategy that allows us to achieve a computational complexity of order O(T OL−2), this is the same computational complexity as in an exact method but with a smaller constant. We provide numerical examples to show our results.

Filtering and control of stochastic jump hybrid systems

CERN Document Server

Yao, Xiuming; Zheng, Wei Xing

2016-01-01

This book presents recent research work on stochastic jump hybrid systems. Specifically, the considered stochastic jump hybrid systems include Markovian jump Ito stochastic systems, Markovian jump linear-parameter-varying (LPV) systems, Markovian jump singular systems, Markovian jump two-dimensional (2-D) systems, and Markovian jump repeated scalar nonlinear systems. Some sufficient conditions are first established respectively for the stability and performances of those kinds of stochastic jump hybrid systems in terms of solution of linear matrix inequalities (LMIs). Based on the derived analysis conditions, the filtering and control problems are addressed. The book presents up-to-date research developments and novel methodologies on stochastic jump hybrid systems. The contents can be divided into two parts: the first part is focused on robust filter design problem, while the second part is put the emphasis on robust control problem. These methodologies provide a framework for stability and performance analy...

Four-branch Star Hybrid Power Filter for Three-phase Four-wire Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Teodorescu, Remus; Rodriguez, Pedro

2008-01-01

and derives fundamental concepts about the control of the resulting hybrid power filter. From this analysis, a specifc implementation of a three-phase four-wire hybrid power filter is presented as an illustrative application of the filtering topology. An extensive evaluation using simulation and experimental......This paper presents a new concept for filtering current harmonics in three-phase four-wire networks. The four-branch star (FBS) filtering topology presented in this work is characterized by a particular layout consisting of single-phase inductances and capacitors. Via this layout, a power filter...

Aircraft Detection from VHR Images Based on Circle-Frequency Filter and Multilevel Features

Directory of Open Access Journals (Sweden)

Feng Gao

2013-01-01

Full Text Available Aircraft automatic detection from very high-resolution (VHR images plays an important role in a wide variety of applications. This paper proposes a novel detector for aircraft detection from very high-resolution (VHR remote sensing images. To accurately distinguish aircrafts from background, a circle-frequency filter (CF-filter is used to extract the candidate locations of aircrafts from a large size image. A multi-level feature model is then employed to represent both local appearance and spatial layout of aircrafts by means of Robust Hue Descriptor and Histogram of Oriented Gradients. The experimental results demonstrate the superior performance of the proposed method.

Advanced configuration of hybrid passive filter for reactive power and harmonic compensation

OpenAIRE

Kececioglu, O. Fatih; Acikgoz, Hakan; Sekkeli, Mustafa

2016-01-01

Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. ...

Multiple-image authentication with a cascaded multilevel architecture based on amplitude field random sampling and phase information multiplexing.

Science.gov (United States)

Fan, Desheng; Meng, Xiangfeng; Wang, Yurong; Yang, Xiulun; Pan, Xuemei; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

2015-04-10

A multiple-image authentication method with a cascaded multilevel architecture in the Fresnel domain is proposed, in which a synthetic encoded complex amplitude is first fabricated, and its real amplitude component is generated by iterative amplitude encoding, random sampling, and space multiplexing for the low-level certification images, while the phase component of the synthetic encoded complex amplitude is constructed by iterative phase information encoding and multiplexing for the high-level certification images. Then the synthetic encoded complex amplitude is iteratively encoded into two phase-type ciphertexts located in two different transform planes. During high-level authentication, when the two phase-type ciphertexts and the high-level decryption key are presented to the system and then the Fresnel transform is carried out, a meaningful image with good quality and a high correlation coefficient with the original certification image can be recovered in the output plane. Similar to the procedure of high-level authentication, in the case of low-level authentication with the aid of a low-level decryption key, no significant or meaningful information is retrieved, but it can result in a remarkable peak output in the nonlinear correlation coefficient of the output image and the corresponding original certification image. Therefore, the method realizes different levels of accessibility to the original certification image for different authority levels with the same cascaded multilevel architecture.

Hybrid Plasma Reactor/Filter for Transportable Collective Protection Systems

Energy Technology Data Exchange (ETDEWEB)

Josephson, Gary B.; Tonkyn, Russell G.; Frye, J. G.; Riley, Brian J.; Rappe, Kenneth G.

2011-04-06

Pacific Northwest National Laboratory (PNNL) has performed an assessment of a Hybrid Plasma/Filter system as an alternative to conventional methods for collective protection. The key premise of the hybrid system is to couple a nonthermal plasma (NTP) reactor with reactive adsorption to provide a broader envelope of protection than can be provided through a single-solution approach. The first step uses highly reactive species (e.g. oxygen radicals, hydroxyl radicals, etc.) created in a nonthermal plasma (NTP) reactor to destroy the majority (~75% - 90%) of an incoming threat. Following the NTP reactor an O3 reactor/filter uses the O3 created in the NTP reactor to further destroy the remaining organic materials. This report summarizes the laboratory development of the Hybrid Plasma Reactor/Filter to protect against a ‘worst-case’ simulant, methyl bromide (CH3Br), and presents a preliminary engineering assessment of the technology to Joint Expeditionary Collective Protection performance specifications for chemical vapor air purification technologies.

Swarm Intelligence for Optimizing Hybridized Smoothing Filter in Image Edge Enhancement

Science.gov (United States)

Rao, B. Tirumala; Dehuri, S.; Dileep, M.; Vindhya, A.

In this modern era, image transmission and processing plays a major role. It would be impossible to retrieve information from satellite and medical images without the help of image processing techniques. Edge enhancement is an image processing step that enhances the edge contrast of an image or video in an attempt to improve its acutance. Edges are the representations of the discontinuities of image intensity functions. For processing these discontinuities in an image, a good edge enhancement technique is essential. The proposed work uses a new idea for edge enhancement using hybridized smoothening filters and we introduce a promising technique of obtaining best hybrid filter using swarm algorithms (Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO) and Ant Colony Optimization (ACO)) to search for an optimal sequence of filters from among a set of rather simple, representative image processing filters. This paper deals with the analysis of the swarm intelligence techniques through the combination of hybrid filters generated by these algorithms for image edge enhancement.

Removal of Iron and Manganese Using Cascade Aerator and Limestone Roughing Filter

Directory of Open Access Journals (Sweden)

Mohd Sanusi Azrin

2016-01-01

Full Text Available Combination between oxidation and filtration can be used for removing iron and manganese from groundwater especially when the concentrations of these metals were high. This study focused on the effectiveness of the cascade aerator and the size of the limestone filter media to remove iron and manganese from groundwater. Water samples used for this study were collected from orphanage home, Rumah Nur Kasih, Taiping. Universiti Sains Malaysia (USM has provided a tube well of 15 m depth and 150 mm diameter for the orphanage home. However, the water cannot be used for domestic consumption due to high amount of iron and manganese at 6.48 and 1.9 mg/L which exceeded the drinking water standard of 0.3 and 0.1 mg/L respectively. Using laboratory physical model, the study has shown that the removals of iron and manganese have reduce the concentration until 0.17 and 0.2 mg/L respectively. Thus, the results from this study which utilize cascade aerator and limestone roughing filter could be implemented on site for the community to use the ground water for domestic purposes.

Hybrid Micro-Electro-Mechanical Tunable Filter

Science.gov (United States)

2007-09-01

and polymer hybrid actuator and applications as a tunable filter in telecom and in IR chemical detector,” in Micromachining and Microfabrication...consistently achieved. At this temperature, SU8 - SU-8 bonding withstood subsequent processing steps, resulting in a 57% bond yield and an overall 30

A hybrid active filter for damping of harmonic resonance in industrial power systems

OpenAIRE

Fujita, Hideaki; Yamasaki, Takahiro; Akagi, Hirofumi

1998-01-01

This paper proposes a hybrid active filter for damping of harmonic resonance in industrial power systems. The hybrid filter consists of a small-rated active filter and a 5th tuned passive filter. The active filter is characterized by detecting the 5th harmonic current flowing into the passive filter. It is controlled in such a way as to behave as a negative or positive resistor by adjusting a feedback gain from a negative to positive value, and vice versa. The negative resistor presented by t...

Active RC filter based implementation analysis part of two channel hybrid filter bank

Directory of Open Access Journals (Sweden)

Stojanović Vidosav

2014-01-01

Full Text Available In the present paper, a new design method for continuous-time powersymmetric active RC filters for Hybrid Filter Bank (HFB is proposed. Some theoretical properties of continious-time power-symmetric filters bank in a more general perspective are studied. This includes the derivation of a new general analytical form, and a study of poles and zeros locations in s-plane. In the proposed design method the analytic solution of filter coefficients is solved in sdomain using only one nonlinear equation Finally, the proposed approximation is compared to standard approximations. It was shown that attenuation and group delay characteristic of the proposed filter lie between Butterworth and elliptic characteristics. [Projekat Ministarstva nauke Republike Srbije, br. 32009TR

Voltage Harmonics Mitigation through Hybrid Active Power Filter

Directory of Open Access Journals (Sweden)

Anwer Ali Sahito

2016-01-01

Full Text Available Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion of 18.91 and 7.61% in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter is proposed to reduce these THD values below 5% as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5%.

Modified-hybrid optical neural network filter for multiple object recognition within cluttered scenes

Science.gov (United States)

Kypraios, Ioannis; Young, Rupert C. D.; Chatwin, Chris R.

2009-08-01

Motivated by the non-linear interpolation and generalization abilities of the hybrid optical neural network filter between the reference and non-reference images of the true-class object we designed the modifiedhybrid optical neural network filter. We applied an optical mask to the hybrid optical neural network's filter input. The mask was built with the constant weight connections of a randomly chosen image included in the training set. The resulted design of the modified-hybrid optical neural network filter is optimized for performing best in cluttered scenes of the true-class object. Due to the shift invariance properties inherited by its correlator unit the filter can accommodate multiple objects of the same class to be detected within an input cluttered image. Additionally, the architecture of the neural network unit of the general hybrid optical neural network filter allows the recognition of multiple objects of different classes within the input cluttered image by modifying the output layer of the unit. We test the modified-hybrid optical neural network filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. The filter is shown to exhibit with a single pass over the input data simultaneously out-of-plane rotation, shift invariance and good clutter tolerance. It is able to successfully detect and classify correctly the true-class objects within background clutter for which there has been no previous training.

Extended SVM algorithms for multilevel trans-Z-source inverter

Directory of Open Access Journals (Sweden)

Aida Baghbany Oskouei

2016-03-01

Full Text Available This paper suggests extended algorithms for multilevel trans-Z-source inverter. These algorithms are based on space vector modulation (SVM, which works with high switching frequency and does not generate the mean value of the desired load voltage in every switching interval. In this topology the output voltage is not limited to dc voltage source similar to traditional cascaded multilevel inverter and can be increased with trans-Z-network shoot-through state control. Besides, it is more reliable against short circuit, and due to several number of dc sources in each phase of this topology, it is possible to use it in hybrid renewable energy. Proposed SVM algorithms include the following: Combined modulation algorithm (SVPWM and shoot-through implementation in dwell times of voltage vectors algorithm. These algorithms are compared from viewpoint of simplicity, accuracy, number of switching, and THD. Simulation and experimental results are presented to demonstrate the expected representations.

Design and control of hybrid active power filters

CERN Document Server

Lam, Chi-Seng

2014-01-01

Design and Control of Hybrid Active Power Filters presents an overview of the current quality problems and their compensators. To get a balance between the system cost and performance, hybrid active power filters (HAPFs) are valuable. The book presents the coverage of resonance phenomena prevention capability, filtering performance and system robustness analysis of HAPF; nonlinear inverter current slope characteristics and their linear operation region requirement analysis of the hysteresis PWM for the HAPF; minimum inverter capacity design procedure of HAPF, adaptive dc-link voltage controller for the HAPF and the real design example of a 220V 10kVA HAPF, in which the system performance analysis method, minimum dc voltage deduction concept and adaptive dc voltage idea can be further extended into the other active compensators, such as APF, static synchronous compensator STATCOM, etc. This book will benefit researchers, graduate students, and electrical power engineers in the field of power-quality compensati...

Hybrid viscous damper with filtered integral force feedback control

DEFF Research Database (Denmark)

Høgsberg, Jan; Brodersen, Mark L.

2016-01-01

In hybrid damper systems active control devices are usually introduced to enhance the performance of otherwise passive dampers. In the present paper a hybrid damper concept is comprised of a passive viscous damper placed in series with an active actuator and a force sensor. The actuator motion...... is controlled by a filtered integral force feedback strategy, where the main feature is the filter, which is designed to render a damper force that in a phase-plane representation operates in front of the corresponding damper velocity. It is demonstrated that in the specific parameter regime where the damper...

A Transformerless Hybrid Active Filter Capable of Complying with Harmonic Guidelines for Medium-Voltage Motor Drives

Science.gov (United States)

Kondo, Ryota; Akagi, Hirofumi

This paper presents a transformerless hybrid active filter that is integrated into medium-voltage adjustable-speed motor drives for fans, pumps, and compressors without regenerative braking. The authors have designed and constructed a three-phase experimental system rated at 400V and 15kW, which is a downscaled model from a feasible 6.6-kV 1-MW motor drive system. This system consists of the hybrid filter connecting a passive filter tuned to the 7th harmonic filter in series with an active filter that is based on a three-level diode-clamped PWM converter, as well as an adjustable-speed motor drive in which a diode rectifier is used as the front end. The hybrid filter is installed on the ac side of the diode rectifier with no line-frequency transformer. The downscaled system has been exclusively tested so as to confirm the overall compensating performance of the hybrid filter and the filtering performance of a switching-ripple filter for mitigating switching-ripple voltages produced by the active filter. Experimental results verify that the hybrid filter achieves harmonic compensation of the source current in all the operating regions from no-load to the rated-load conditions, and that the switching-ripple filter reduces the switching-ripple voltages as expected.

Narrow line-width Tm3+ doped double-clad silica fiber laser based on in-line cascade biconical tapers filter

International Nuclear Information System (INIS)

Tian, Y; Zhao, J Q; Wang, W; Wang, Y Z; Gao, W

2010-01-01

Narrow line-width 793 nm laser diode cladding pumped Tm 3+ doped double cladding silica fiber laser with in-line four concatenated tapers filter was reported for the first time to our knowledge. These cascade tapers located 3.6 cm from the output end of the fiber laser was fabricated by heating and stretching method. The taper's transmitted power response as a function of wavelength was described by using local mode coupling theory and successive tapers filter model. The wavelength filter function of the in-line cascade tapers in a linear cavity fiber laser was demonstrated, and the experimental result agreed with these theories. The maximum output laser power was 736 mW, corresponding to single peak of laser spectrum with narrow line-width of ∼ 60 pm

Efficiency Improvement of Three-Phase Cascaded H-Bridge Multilevel Inverters for Photovoltaic Systems

Directory of Open Access Journals (Sweden)

Nuntawat Thitichaiworakorn

2016-01-01

Full Text Available Medium-scale photovoltaic (PV systems using cascaded H-bridge multilevel inverters have a capability to perform individual maximum power point tracking (MPPT for each PV panel or each small group of panels, resulting in minimization of both power losses from panel mismatch and effect of partial shading. They also provide high power quality, modularity, and possibility of eliminating dc-dc boost stage and line-frequency transformer. However, each PV panel in the system is subjected to a double-line-frequency voltage ripple at the dc-link which reduces the MPPT efficiency. This paper proposes a dc-link voltage ripple reduction by third-harmonic zero-sequence voltage injection for improving the MPPT efficiency. Moreover, a control method to achieve individual MPPT control of each inverter cell is also presented. The validity and effectiveness of the proposed methods were verified by computer simulation.

Hybrid-source impedance network and its generalized cascading concepts

DEFF Research Database (Denmark)

Li, Ding; Gao, Feng; Loh, Poh Chiang

2009-01-01

Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters, with another three types summarized...... for current-type inverters. These impedance networks can in principle be combined into a single generic network entity, before generalized cascading concepts are proposed for connecting multiple of them together to form energy converters with a higher output voltage gain and other unique advantages...

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Science.gov (United States)

Wu, Jiayang; Moein, Tania; Xu, Xingyuan; Moss, David J.

2018-04-01

We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

An adaptive deep-coupled GNSS/INS navigation system with hybrid pre-filter processing

Science.gov (United States)

Wu, Mouyan; Ding, Jicheng; Zhao, Lin; Kang, Yingyao; Luo, Zhibin

2018-02-01

The deep-coupling of a global navigation satellite system (GNSS) with an inertial navigation system (INS) can provide accurate and reliable navigation information. There are several kinds of deeply-coupled structures. These can be divided mainly into coherent and non-coherent pre-filter based structures, which have their own strong advantages and disadvantages, especially in accuracy and robustness. In this paper, the existing pre-filters of the deeply-coupled structures are analyzed and modified to improve them firstly. Then, an adaptive GNSS/INS deeply-coupled algorithm with hybrid pre-filters processing is proposed to combine the advantages of coherent and non-coherent structures. An adaptive hysteresis controller is designed to implement the hybrid pre-filters processing strategy. The simulation and vehicle test results show that the adaptive deeply-coupled algorithm with hybrid pre-filters processing can effectively improve navigation accuracy and robustness, especially in a GNSS-challenged environment.

Hybrid Active Filter with Variable Conductance for Harmonic Resonance Suppression in Industrial Power Systems

DEFF Research Database (Denmark)

Lee, Tzung-Lin; Wang, Yen-Ching; Li, Jian-Cheng

2015-01-01

Unintentional series and/or parallel resonances, due to the tuned passive filter and the line inductance, may result in severe harmonic distortion in the industrial power system. This paper presents a hybrid active filter to suppress harmonic resonance and reduce harmonic distortion as well...... expensive. A reasonable trade-off between filtering performances and cost is to use the hybrid active filter. Design consideration are presented and experimental results are provided to validate effectiveness of the proposed method. Furthermore, this paper discusses filtering performances on line impedance...

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Directory of Open Access Journals (Sweden)

Jiayang Wu

2018-04-01

Full Text Available We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI nanowires implemented by cascaded Sagnac loop reflector (CSLR resonators. We investigate mode splitting in these standing-wave (SW resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

Battery pack state of charge balancing algorithm for cascaded H-Bridge multilevel converters

DEFF Research Database (Denmark)

Máthé, Lászlo; Burlacu, Paul Dan; Schaltz, Erik

2016-01-01

For most of the Multilevel Converter (MC) applications a commonly discussed issue is the maintenance of balance between the energy storage elements from the SubModules (SM). In applications where a battery pack is also part of the SM storage, such as STATCOMs or motor drives, the SM voltage...... is not in linear relation with the State Of Charge (SOC) of the entire battery; thus, the balancing becomes more cumbersome. A method to balance the SOC of the battery packs in a system using cascaded H-Bridge is proposed in this paper. The method uses nearest level control followed by sorting and selection based...... on the SOC of the battery packs. Based on the simulation results the number of switching is reduced considerably compared to the method where the phase shifted PWM is used. In addition, the time needed to achieve the balanced SOC is also reduced. The proposed method has been verified through experiments...

Fast lossless compression via cascading Bloom filters.

Science.gov (United States)

Rozov, Roye; Shamir, Ron; Halperin, Eran

2014-01-01

Data from large Next Generation Sequencing (NGS) experiments present challenges both in terms of costs associated with storage and in time required for file transfer. It is sometimes possible to store only a summary relevant to particular applications, but generally it is desirable to keep all information needed to revisit experimental results in the future. Thus, the need for efficient lossless compression methods for NGS reads arises. It has been shown that NGS-specific compression schemes can improve results over generic compression methods, such as the Lempel-Ziv algorithm, Burrows-Wheeler transform, or Arithmetic Coding. When a reference genome is available, effective compression can be achieved by first aligning the reads to the reference genome, and then encoding each read using the alignment position combined with the differences in the read relative to the reference. These reference-based methods have been shown to compress better than reference-free schemes, but the alignment step they require demands several hours of CPU time on a typical dataset, whereas reference-free methods can usually compress in minutes. We present a new approach that achieves highly efficient compression by using a reference genome, but completely circumvents the need for alignment, affording a great reduction in the time needed to compress. In contrast to reference-based methods that first align reads to the genome, we hash all reads into Bloom filters to encode, and decode by querying the same Bloom filters using read-length subsequences of the reference genome. Further compression is achieved by using a cascade of such filters. Our method, called BARCODE, runs an order of magnitude faster than reference-based methods, while compressing an order of magnitude better than reference-free methods, over a broad range of sequencing coverage. In high coverage (50-100 fold), compared to the best tested compressors, BARCODE saves 80-90% of the running time while only increasing space

Cancellation of neutral current harmonics by using a four-branch star hybrid filter

DEFF Research Database (Denmark)

Blaabjerg, Frede; Rodriguez, Pedro; Candela, I.

2008-01-01

filtering topology to a three-phase four-wire system. An extensive evaluation using simulation and experimental results are conducted in this work to validate the good performance of the proposed solution for canceling current harmonics flowing through the neutral conductor.......This paper presents a new technique for filtering current harmonics in three-phase four-wire networks based on the usage of a four-branch star (FBS) filter topology. Based on single-phase inductors and capacitors, the specific layout of the FBS filter topology allows achieving a power filter...... is improved by integrating a power converter into its structure. This paper analyzes the FBS topology and presents fundamental concepts regarding the control of a generic FBS hybrid power filter. A neutral current hybrid power filter and var compensator is presented as an illustrative example applying the FBS...

Flat microwave photonic filter based on hybrid of two filters

International Nuclear Information System (INIS)

Qi, Chunhui; Pei, Li; Ning, Tigang; Li, Jing; Gao, Song

2010-01-01

A new microwave photonic filter (MPF) hybrid of two filters that can realize both multiple taps and a flat bandpass or bandstop response is presented. Based on the phase character of a Mach–Zehnder modulator (MZM), a two taps finite impulse response (FIR) filter is obtained as the first part. The second part is obtained by taking full advantage of the wavelength selectivity of the fiber Bragg grating (FBG) and the gain of a erbium-doped fiber (EDF). Combining the two filters, the flat bandpass or bandstop response is realized by changing the coupler's factor k, the reflectivity of FBG1 R 1 or the gain of the EDF g. Optimizing the system parameters, a flat bandpass response with amplitude depth of more than 45 dB is obtained at k = 0.5, R 1 = 0.33, g = 10, and a flat bandstop response is also obtained at k = 0.4, R 1 = 0.5, g = 2. In addition, the free-spectral range (FSR) can be controlled by changing the length of the EDF and the length difference between two MZMs. The method is proved feasible by some experiments. Such a method offers realistic solutions to support future radio-frequency (RF) optical communication systems

A design of cascade control system and adaptive load compensator for battery/ultracapacitor hybrid energy storage-based direct current microgrid

International Nuclear Information System (INIS)

Pavković, Danijel; Lobrović, Mihael; Hrgetić, Mario; Komljenović, Ante

2016-01-01

Highlights: • Battery/ultracapacitor storage is considered for a direct-current microgrid. • Microgrid voltage cascade control system with load compensator is designed. • Current references are allocated so that ultracapacitor takes on transient loads. • Adaptive Kalman filter-based estimator is used for indirect load compensation. • Control strategy has been verified on a downscaled hardware-in-the-loop setup. - Abstract: A control system design based on an actively-controlled battery/ultracapacitor hybrid energy storage system suitable for direct current microgrid energy management purposes is presented in this paper. The proposed cascade control system arrangement is based on the superimposed proportional–integral voltage controller designed according to Damping Optimum criterion and a zero-pole canceling feed-forward load compensator aimed at voltage excursion suppression under variable load conditions. The superimposed controller commands the inner battery and ultracapacitor current control loops through a dynamic current reference distribution scheme, wherein the ultracapacitor takes on the highly-dynamic (transient) current demands, and the battery covers for steady-state loads. In order to avoid deep discharges of the ultracapacitor module, it is equipped with an auxiliary state-of-charge controller. Finally, for those applications where load is not measured, an adaptive Kalman filter-based load compensator is proposed and tested. The presented control strategy has been implemented on the low-cost industrial controller unit, and its effectiveness has been verified by means of simulations and experiments for the cases of abrupt load changes and quasi-stochastic load profiles using a downscaled battery/ultracapacitor hardware-in-the-loop experimental setup.

Identification of DNA viruses by membrane filter hybridization.

OpenAIRE

Stålhandske, P; Pettersson, U

1982-01-01

The use of membrane filter hybridization for the identification of DNA viruses is described. We designed and used a procedure for identification of herpes simplex virus. This method can discriminate between herpes simplex virus types 1 and 2 in a simple way.

Improved hybrid information filtering based on limited time window

Science.gov (United States)

Song, Wen-Jun; Guo, Qiang; Liu, Jian-Guo

2014-12-01

Adopting the entire collecting information of users, the hybrid information filtering of heat conduction and mass diffusion (HHM) (Zhou et al., 2010) was successfully proposed to solve the apparent diversity-accuracy dilemma. Since the recent behaviors are more effective to capture the users' potential interests, we present an improved hybrid information filtering of adopting the partial recent information. We expand the time window to generate a series of training sets, each of which is treated as known information to predict the future links proven by the testing set. The experimental results on one benchmark dataset Netflix indicate that by only using approximately 31% recent rating records, the accuracy could be improved by an average of 4.22% and the diversity could be improved by 13.74%. In addition, the performance on the dataset MovieLens could be preserved by considering approximately 60% recent records. Furthermore, we find that the improved algorithm is effective to solve the cold-start problem. This work could improve the information filtering performance and shorten the computational time.

Vector Directional Distance Rational Hybrid Filters for Color Image Restoration

Directory of Open Access Journals (Sweden)

L. Khriji

2005-12-01

Full Text Available A new class of nonlinear filters, called vector-directional distance rational hybrid filters (VDDRHF for multispectral image processing, is introduced and applied to color image-filtering problems. These filters are based on rational functions (RF. The VDDRHF filter is a two-stage filter, which exploits the features of the vector directional distance filter (VDDF, the center weighted vector directional distance filter (CWVDDF and those of the rational operator. The filter output is a result of vector rational function (VRF operating on the output of three sub-functions. Two vector directional distance (VDDF filters and one center weighted vector directional distance filter (CWVDDF are proposed to be used in the first stage due to their desirable properties, such as, noise attenuation, chromaticity retention, and edges and details preservation. Experimental results show that the new VDDRHF outperforms a number of widely known nonlinear filters for multi-spectral image processing such as the vector median filter (VMF, the generalized vector directional filters (GVDF and distance directional filters (DDF with respect to all criteria used.

A Hybrid Extended Kalman Filter as an Observer for a Pot-Electro-Magnetic Actuator

International Nuclear Information System (INIS)

Schmidt, Simon; Mercorelli, Paolo

2017-01-01

This paper deals with an application in which a hybrid extended Kalman Filter (HEKF) is used to estimate state variables in a U-shaped electro-magnetic actuator to be used in mechanical systems. In this context a hybrid Kalman Filter is the one which switches between different models. The paper proposes a hybrid model for an extended Kalman Filter to be used as an observer to estimate the state and to control the force of the actuator. Applications include position, velocity and force control in automotive, engine and manufacturing systems. This work is focused on the estimation of state variables of the actuator. Simulated results show the effectiveness of the proposed approach. (paper)

Design of Passive Power Filter for Hybrid Series Active Power Filter using Estimation, Detection and Classification Method

Science.gov (United States)

Swain, Sushree Diptimayee; Ray, Pravat Kumar; Mohanty, K. B.

2016-06-01

This research paper discover the design of a shunt Passive Power Filter (PPF) in Hybrid Series Active Power Filter (HSAPF) that employs a novel analytic methodology which is superior than FFT analysis. This novel approach consists of the estimation, detection and classification of the signals. The proposed method is applied to estimate, detect and classify the power quality (PQ) disturbance such as harmonics. This proposed work deals with three methods: the harmonic detection through wavelet transform method, the harmonic estimation by Kalman Filter algorithm and harmonic classification by decision tree method. From different type of mother wavelets in wavelet transform method, the db8 is selected as suitable mother wavelet because of its potency on transient response and crouched oscillation at frequency domain. In harmonic compensation process, the detected harmonic is compensated through Hybrid Series Active Power Filter (HSAPF) based on Instantaneous Reactive Power Theory (IRPT). The efficacy of the proposed method is verified in MATLAB/SIMULINK domain and as well as with an experimental set up. The obtained results confirm the superiority of the proposed methodology than FFT analysis. This newly proposed PPF is used to make the conventional HSAPF more robust and stable.

Tunable and switchable all-fiber comb filter using a PBS-based two-stage cascaded Mach-Zehnder interferometer

Science.gov (United States)

Luo, Zhi-Chao; Luo, Ai-Ping; Xu, Wen-Cheng

2011-08-01

We propose and demonstrate a novel tunable and switchable all-fiber comb filter by employing a polarization beam splitter (PBS)-based two-stage cascaded Mach-Zehnder (M-Z) interferometer. The proposed comb filter consists of a rotatable polarizer, a fiber PBS, a non-3-dB coupler and a 3-dB coupler. By simply adjusting the polarization state of the input light, the dual-function of channel spacing tunable and wavelength switchable (interleaving) operations can be efficiently obtained. The theoretical analysis is verified by the experimental results. A comb filter with both the channel spacing tunable from 0.18 nm to 0.36 nm and the wavelength switchable functions is experimentally demonstrated.

A novel static frequency converter based on multilevel cascaded H-bridge used for the startup of synchronous motor in pumped-storage power station

Energy Technology Data Exchange (ETDEWEB)

Wang Feng, E-mail: sjtuwfeng@hotmail.co [Key Lab of Control of Power Transmission and Transformation, Ministry of Education, Department of Electrical Engineering, Shanghai Jiaotong University, Minhang District, Shanghai 200240 (China); Jiang Jianguo, E-mail: jiang@sjtu.edu.c [Key Lab of Control of Power Transmission and Transformation, Ministry of Education, Department of Electrical Engineering, Shanghai Jiaotong University, Minhang District, Shanghai 200240 (China)

2011-05-15

Research highlights: {yields} A novel Static Frequency Converter (SFC) based on multilevel cascaded H-bridge (CHB) topology is proposed and used for the reversible pump-generating units in pumped-storage power station. {yields} The novel SFC based on CHB has compact configuration, low current harmonic distortion and fast speed response. {yields} Rotor position and Grid connection are realized successfully by the novel SFC. -- Abstract: A novel static frequency converter (SFC) is proposed and is used firstly to start the reversible pump-generating units in pumped-storage power station. Multilevel cascaded H-bridge (CHB) topology and Insulated Gate Bipolar Transistor (IGBT) are applied in the novel SFC. In comparison with the conventional SFC adopting load-commutated inverter (LCI) which is composed of silicon-controlled rectifier (SCR), the novel one has plenty of advantages such as compact configuration, low current harmonic distortion and fast speed response, and these advantages have been verified during 2-year operation at Xiang Hong Dian Pumped-storage power station in China. This application shows that the novel SFC greatly enhances the reliability and success rate of connecting to grid for starting up the pump-generating units. The principle, characteristic and performance of the novel SFC are described in this paper, and some key issues related to the startup of the units of the pumped-storage power station are also presented.

The Power Quality Compensation Strategy for Power Distribution System Based on Hybrid Parallel Active Power Filters

Directory of Open Access Journals (Sweden)

Rachid DEHINI

2010-12-01

Full Text Available In this paper, the main aim is to confront the performance of shunt active power filter (SAPF and the shunt hybrid active power filter (SHAPF to achieve flexibility and reliability of the filter devices. Both of the two devices used the classical proportional-integral controller for pulse generation to trigger the inventers MOSFET’s. In the adopted hybrid active filter there is a passive power filter with high power rating to filter the low order harmonies and one active filter with low power rating to filter the other high order harmonies. In order to investigate the effectiveness of (SHAPF, the studies have been accomplished using simulation with the MATLAB-SIMULINK. The results show That (SHAPF is more effective than (SAPF, and has lower cost.

A novel power control strategy of Modular Multi-level Converter in HVDC-AC hybrid transmission systems for passive networks

DEFF Research Database (Denmark)

Hu, Zhenda; Wu, Rui; Yang, Xiaodong

2014-01-01

With the development of High Voltage DC Transmission (HVDC) technology, there will be more and more HVDC-AC hybrid transmission system in the world. A basic challenge in HVDC-AC hybrid transmission systems is to optimize the power sharing between DC and AC lines, which become more severe when sup...... control strategy of Modular Multi-level Converter in VSC-HVDC, which can optimize converter output power according to passive network loading variation. Proposal method is studied with a case study of a VSC-HVDC AC hybrid project by PSCAD/EMTDC simulations....

Analysis and integration of multilevel inverter configuration with boost converters in a photovoltaic system

International Nuclear Information System (INIS)

Prabaharan, N.; Palanisamy, K.

2016-01-01

Highlights: • Integration of MLI with boost converters in photovoltaic system including MPPT. • Results are taken for different irradiations and different temperature condition. • Proposed system is tested with sudden step changes from standard test condition. • Analysis of switching losses and conduction loss is discussed. • Theoretical calculation of % THD using asymptotic formula is discussed. - Abstract: This paper proposes a single phase multilevel inverter configuration that conjoins three series connected full bridge inverter and a single half bridge inverter for renewable energy application especially photo-voltaic system. This configuration of multilevel inverter reduces the value of total harmonic distortion. The half bridge inverter utilized in the proposed configuration increases the output voltage level to nearly twice the output voltage level of a conventional cascaded H-bridge multilevel inverter. This higher output voltage level is generated with lesser number of power semiconductor switches compared to conventional configuration, thus reducing the total harmonic distortion and switching losses. The effectiveness of the proposed configuration is illustrated by replacing the isolated DC sources in multilevel inverter with individual photo-voltaic panels using separate perturb and observer based maximum power point tracking and boost converters. The verification of the proposed system is demonstrated successfully using MATLAB/Simulink based simulation with different irradiation and temperature conditions. Also, the transient operation of the system is verified with results depicted using step change in standard test condition. In the proposed system, total harmonic distortion of the output voltage is 9.85% without using passive filters and 3.91% with filter inductance. Theoretical calculation of the power losses and total harmonic distortion with mathematical equations are discussed. Selective experimental results are presented to prove the

Temperature Compensated Strain Sensor Based on Cascaded Sagnac Interferometers and All-Solid Birefringent Hybrid Photonic Crystal Fibers

DEFF Research Database (Denmark)

Gu, Bobo; Yuan, Wu; He, Sailing

2012-01-01

We demonstrate a temperature compensated strain sensor with two cascaded Sagnac interferometers, that provide strain sensing and temperature compensation, respectively. The Sagnac interferometers use an all-solid hybrid photonic crystal fiber with stress-induced birefringence. The stress-induced ...

Multilevel structures of Li3V2(PO4)3/phosphorus-doped carbon nanocomposites derived from hybrid V-MOFs for long-life and cheap lithium ion battery cathodes

Science.gov (United States)

Wang, Zhaoyang; He, Wen; Zhang, Xudong; Yue, Yuanzheng; Liu, Jinhua; Zhang, Chuanjiang; Fang, Leyong

2017-10-01

The Li3V2(PO4)3/phosphorus-doped carbon (LVP/P-C) nanocomposites with multilevel structures (such as spheroidal, foam, prism and flower-like structures) are synthesized via one-pot in-situ synthesis using hybrid vanadium metal-organic frameworks (V-MOFs) as precursor. The structure and morphology of the LVP/P-C nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, Raman, X-ray diffraction and element mapping. The results show that the multilevel structures are generated from the assemblies of the hybrid surfactant templates in the glass fiber drawing wastewater (GFDW) and the hybrid V-MOFs. The structure of LVP/P-C nanocomposite is controlled by V-MOFs. The nanocomposites exhibit a long service life, a discharge capacity of 65 mA h g-1 at 10 C with 90% capacity retention after 1100 cycles. The high cycling stability is attributed to the multilevel structures, which is ideal for making rechargeable lithium ion batteries. More importantly, our results have demonstrated that GFDW can be transformed into treasure of multilevel structure nanocomposites for cheap Li ion batteries.

A hybrid filtering method based on a novel empirical mode decomposition for friction signals

International Nuclear Information System (INIS)

Li, Chengwei; Zhan, Liwei

2015-01-01

During a measurement, the measured signal usually contains noise. To remove the noise and preserve the important feature of the signal, we introduce a hybrid filtering method that uses a new intrinsic mode function (NIMF) and a modified Hausdorff distance. The NIMF is defined as the difference between the noisy signal and each intrinsic mode function (IMF), which is obtained by empirical mode decomposition (EMD), ensemble EMD, complementary ensemble EMD, or complete ensemble EMD with adaptive noise (CEEMDAN). The relevant mode selecting is based on the similarity between the first NIMF and the rest of the NIMFs. With this filtering method, the EMD and improved versions are used to filter the simulation and friction signals. The friction signal between an airplane tire and the runaway is recorded during a simulated airplane touchdown and features spikes of various amplitudes and noise. The filtering effectiveness of the four hybrid filtering methods are compared and discussed. The results show that the filtering method based on CEEMDAN outperforms other signal filtering methods. (paper)

Joint compensation scheme of polarization crosstalk, intersymbol interference, frequency offset, and phase noise based on cascaded Kalman filter

Science.gov (United States)

Zhang, Qun; Yang, Yanfu; Xiang, Qian; Zhou, Zhongqing; Yao, Yong

2018-02-01

A joint compensation scheme based on cascaded Kalman filter is proposed, which can implement polarization tracking, channel equalization, frequency offset, and phase noise compensation simultaneously. The experimental results show that the proposed algorithm can not only compensate multiple channel impairments simultaneously but also improve the polarization tracking capacity and accelerate the convergence speed. The scheme has up to eight times faster convergence speed compared with radius-directed equalizer (RDE) + Max-FFT (maximum fast Fourier transform) + BPS (blind phase search) and can track up polarization rotation 60 times and 15 times faster than that of RDE + Max-FFT + BPS and CMMA (cascaded multimodulus algorithm) + Max-FFT + BPS, respectively.

Cascaded K-means convolutional feature learner and its application to face recognition

Science.gov (United States)

Zhou, Daoxiang; Yang, Dan; Zhang, Xiaohong; Huang, Sheng; Feng, Shu

2017-09-01

Currently, considerable efforts have been devoted to devise image representation. However, handcrafted methods need strong domain knowledge and show low generalization ability, and conventional feature learning methods require enormous training data and rich parameters tuning experience. A lightened feature learner is presented to solve these problems with application to face recognition, which shares similar topology architecture as a convolutional neural network. Our model is divided into three components: cascaded convolution filters bank learning layer, nonlinear processing layer, and feature pooling layer. Specifically, in the filters learning layer, we use K-means to learn convolution filters. Features are extracted via convoluting images with the learned filters. Afterward, in the nonlinear processing layer, hyperbolic tangent is employed to capture the nonlinear feature. In the feature pooling layer, to remove the redundancy information and incorporate the spatial layout, we exploit multilevel spatial pyramid second-order pooling technique to pool the features in subregions and concatenate them together as the final representation. Extensive experiments on four representative datasets demonstrate the effectiveness and robustness of our model to various variations, yielding competitive recognition results on extended Yale B and FERET. In addition, our method achieves the best identification performance on AR and labeled faces in the wild datasets among the comparative methods.

4Nx Non-Isolated and Non-Inverting Hybrid Interleaved Multilevel Boost Converter Based on VLCIm Cell and Cockroft Walton Voltage Multiplier for Renewable Energy Applications

DEFF Research Database (Denmark)

Bhaskar, Mahajan Sagar; Padmanaban, Sanjeevikumar; Blaabjerg, Frede

2016-01-01

In this treatise, 4Nx hybrid Non Inverting & Non Isolated (NI-NI) DC-DC interleaved multi-level boost converter (4Nx IMBC) for renewable energy applications is proposed. The proposed 4Nx IMBC is derived by coalescing the feature of 2Nx DC-DC Interleaved Multi-level Boost Converter (2Nx IMBC), vol...... or transformers. Simulations results of proposed circuitry are presented which verify the analysis, function, working modes & feasibility of proposed circuitry converter.......In this treatise, 4Nx hybrid Non Inverting & Non Isolated (NI-NI) DC-DC interleaved multi-level boost converter (4Nx IMBC) for renewable energy applications is proposed. The proposed 4Nx IMBC is derived by coalescing the feature of 2Nx DC-DC Interleaved Multi-level Boost Converter (2Nx IMBC...... applicable at user end its DC voltage magnitude needs to be incremented with high conversion. Existing and recently proposed DC-DC converter are not sufficiently expert to employ practically, because of stability issues, high duty cycle and high ripple in the output. To overcome the conversion ratio problem...

Multi-vehicle detection with identity awareness using cascade Adaboost and Adaptive Kalman filter for driver assistant system.

Science.gov (United States)

Wang, Baofeng; Qi, Zhiquan; Chen, Sizhong; Liu, Zhaodu; Ma, Guocheng

2017-01-01

Vision-based vehicle detection is an important issue for advanced driver assistance systems. In this paper, we presented an improved multi-vehicle detection and tracking method using cascade Adaboost and Adaptive Kalman filter(AKF) with target identity awareness. A cascade Adaboost classifier using Haar-like features was built for vehicle detection, followed by a more comprehensive verification process which could refine the vehicle hypothesis in terms of both location and dimension. In vehicle tracking, each vehicle was tracked with independent identity by an Adaptive Kalman filter in collaboration with a data association approach. The AKF adaptively adjusted the measurement and process noise covariance through on-line stochastic modelling to compensate the dynamics changes. The data association correctly assigned different detections with tracks using global nearest neighbour(GNN) algorithm while considering the local validation. During tracking, a temporal context based track management was proposed to decide whether to initiate, maintain or terminate the tracks of different objects, thus suppressing the sparse false alarms and compensating the temporary detection failures. Finally, the proposed method was tested on various challenging real roads, and the experimental results showed that the vehicle detection performance was greatly improved with higher accuracy and robustness.

A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters.

Science.gov (United States)

Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

2015-11-10

We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies.

Cascaded Mach-Zehnder wavelength filters in silicon photonics for low loss and flat pass-band WDM (de-)multiplexing.

Science.gov (United States)

Horst, Folkert; Green, William M J; Assefa, Solomon; Shank, Steven M; Vlasov, Yurii A; Offrein, Bert Jan

2013-05-20

We present 1-to-8 wavelength (de-)multiplexer devices based on a binary tree of cascaded Mach-Zehnder-like lattice filters, and manufactured using a 90 nm CMOS-integrated silicon photonics technology. We demonstrate that these devices combine a flat pass-band over more than 50% of the channel spacing with low insertion loss of less than 1.6 dB, and have a small device size of approximately 500 × 400 µm. This makes this type of filters well suited for application as WDM (de-)multiplexer in silicon photonics transceivers for optical data communication in large scale computer systems.

Four-switch hybrid power filter working with six-fold switching symmetry

Czech Academy of Sciences Publication Activity Database

Klíma, J.; Tlustý, J.; Škramlík, Jiří; Valouch, Viktor

2011-01-01

Roč. 56, č. 4 (2011), s. 433-446 ISSN 0001-7043 Institutional research plan: CEZ:AV0Z20570509 Keywords : component minimized hybrid power filter * control strategy * analytical model Subject RIV: JA - Electronics ; Optoelectronics, Electric al Engineering

Molecular evidence for increased regulatory conservation during metamorphosis, and against deleterious cascading effects of hybrid breakdown in Drosophila

Directory of Open Access Journals (Sweden)

Artieri Carlo G

2010-03-01

Full Text Available Abstract Background Speculation regarding the importance of changes in gene regulation in determining major phylogenetic patterns continues to accrue, despite a lack of broad-scale comparative studies examining how patterns of gene expression vary during development. Comparative transcriptional profiling of adult interspecific hybrids and their parental species has uncovered widespread divergence of the mechanisms controlling gene regulation, revealing incompatibilities that are masked in comparisons between the pure species. However, this has prompted the suggestion that misexpression in adult hybrids results from the downstream cascading effects of a subset of genes improperly regulated in early development. Results We sought to determine how gene expression diverges over development, as well as test the cascade hypothesis, by profiling expression in males of Drosophila melanogaster, D. sechellia, and D. simulans, as well as the D. simulans (♀ × D. sechellia (♂ male F1 hybrids, at four different developmental time points (3rd instar larval, early pupal, late pupal, and newly-emerged adult. Contrary to the cascade model of misexpression, we find that there is considerable stage-specific autonomy of regulatory breakdown in hybrids, with the larval and adult stages showing significantly more hybrid misexpression as compared to the pupal stage. However, comparisons between pure species indicate that genes expressed during earlier stages of development tend to be more conserved in terms of their level of expression than those expressed during later stages, suggesting that while Von Baer's famous law applies at both the level of nucleotide sequence and expression, it may not apply necessarily to the underlying overall regulatory network, which appears to diverge over the course of ontogeny and which can only be ascertained by combining divergent genomes in species hybrids. Conclusion Our results suggest that complex integration of regulatory

Shunt hybrid active power filter for harmonic mitigation: A practical ...

Indian Academy of Sciences (India)

The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels shunt Hybrid Active ...

Hybrid recursive active filters for duplexing in RF transmitter front-ends

Science.gov (United States)

Gottardo, Giuseppe; Donati, Giovanni; Musolff, Christian; Fischer, Georg; Felgentreff, Tilman

2016-08-01

Duplex filters in modern base transceiver stations shape the channel in order to perform common frequency division duplex operations. Usually, they are designed as cavity filters, which are expensive and have large dimensions. Thanks to the emerging digital technology and fast digital converters, it is possible to transfer the efforts of designing analog duplex filters into digital numeric algorithms applied to feedback structures, operating on power. This solution provides the shaping of the signal spectrum directly at the output of the radio frequency (RF) power amplifiers (PAs) relaxing the transmitter design especially in the duplexer and in the antenna sections. The design of a digital baseband feedback applied to the analog power RF amplifiers (hybrid filter) is presented and verified by measurements. A model to describe the hybrid system is investigated, and the relation between phase and resonance peaks of the resulting periodic band-pass transfer function is described. The stability condition of the system is analyzed using Nyquist criterion. A solution involving a number of digital feedback and forward branches is investigated defining the parameters of the recursive structure. This solution allows the closed loop system to show a periodic band pass with up to 500 kHz bandwidth at the output of the RF amplifier. The band-pass magnitude reaches up to 17 dB selectivity. The rejection of the PA noise in the out-of-band frequencies is verified by measurements. The filter is tested with a modulated LTE (Long Term Evolution) signal showing an ACPR (Adjacent Channel Power Ratio) enhancement of 10 dB of the transmitted signal.

Interfacial symmetry of Co–Alq_3–Co hybrid structures for effective spin filtering

International Nuclear Information System (INIS)

Lam, Tu-Ngoc; Lai, Yu-Ling; Chen, Chih-Han; Chen, Po-Hung; Wei, Der-Hsin; Lin, Hong-Ji; Chen, C.T.; Sheu, Jeng-Tzong; Hsu, Yao-Jane

2015-01-01

Graphical abstract: - Highlights: • The spin interface at Alq_3/Co and Co/Alq_3 contacts was examined. • An interfacial symmetry was determined at Co–Alq_3–Co interfaces. • Spin-polarized N orbitals are induced within the Co atop Alq_3 hybridized interface. • The spin-filter role at the top contact interface of Alq_3/Co is proved. • Effective spin-filtering at Co–Alq_3–Co contacts was elucidated. - Abstract: Understanding the interfacial behavior at FM-OSC-FM hybrid structures for both the bottom contact (Alq_3 adsorption on Co, Co/Alq_3) and the top contact (Co atop Alq_3, Alq_3/Co) is crucial for efficient spin filtering with transport of spin-polarized charge carriers through these interfaces. X-ray photoelectron spectroscopy (XPS) spectra indicate a symmetry of charge transfer from Co to Alq_3 and the corresponding orbital hybridization to a certain extent at both contacts. The alignment of energy levels at both Alq_3/Co and Co/Alq_3 heterostructures is depicted with ultraviolet photoelectron spectroscopy (UPS). Through magnetic images acquired with a X-ray photoemission electron microscope (XPEEM), the strong hybridization of the top contact presents no micromagnetic domain but still shows magnetic coupling, to some extent, to the bottom contact in the Co–Alq_3–Co trilayer structure. Measurements of X-ray magnetic circular dichroism (XMCD) demonstrate the induced spin-polarization of non-magnetic Alq_3 at both contacts, proving Alq_3 a unique and promising organic material for spin filtering in OSV.

Multi-vehicle detection with identity awareness using cascade Adaboost and Adaptive Kalman filter for driver assistant system.

Directory of Open Access Journals (Sweden)

Baofeng Wang

Full Text Available Vision-based vehicle detection is an important issue for advanced driver assistance systems. In this paper, we presented an improved multi-vehicle detection and tracking method using cascade Adaboost and Adaptive Kalman filter(AKF with target identity awareness. A cascade Adaboost classifier using Haar-like features was built for vehicle detection, followed by a more comprehensive verification process which could refine the vehicle hypothesis in terms of both location and dimension. In vehicle tracking, each vehicle was tracked with independent identity by an Adaptive Kalman filter in collaboration with a data association approach. The AKF adaptively adjusted the measurement and process noise covariance through on-line stochastic modelling to compensate the dynamics changes. The data association correctly assigned different detections with tracks using global nearest neighbour(GNN algorithm while considering the local validation. During tracking, a temporal context based track management was proposed to decide whether to initiate, maintain or terminate the tracks of different objects, thus suppressing the sparse false alarms and compensating the temporary detection failures. Finally, the proposed method was tested on various challenging real roads, and the experimental results showed that the vehicle detection performance was greatly improved with higher accuracy and robustness.

Hybrid three-dimensional variation and particle filtering for nonlinear systems

International Nuclear Information System (INIS)

Leng Hong-Ze; Song Jun-Qiang

2013-01-01

This work addresses the problem of estimating the states of nonlinear dynamic systems with sparse observations. We present a hybrid three-dimensional variation (3DVar) and particle piltering (PF) method, which combines the advantages of 3DVar and particle-based filters. By minimizing the cost function, this approach will produce a better proposal distribution of the state. Afterwards the stochastic resampling step in standard PF can be avoided through a deterministic scheme. The simulation results show that the performance of the new method is superior to the traditional ensemble Kalman filtering (EnKF) and the standard PF, especially in highly nonlinear systems

Enhanced Pedestrian Navigation Based on Course Angle Error Estimation Using Cascaded Kalman Filters.

Science.gov (United States)

Song, Jin Woo; Park, Chan Gook

2018-04-21

An enhanced pedestrian dead reckoning (PDR) based navigation algorithm, which uses two cascaded Kalman filters (TCKF) for the estimation of course angle and navigation errors, is proposed. The proposed algorithm uses a foot-mounted inertial measurement unit (IMU), waist-mounted magnetic sensors, and a zero velocity update (ZUPT) based inertial navigation technique with TCKF. The first stage filter estimates the course angle error of a human, which is closely related to the heading error of the IMU. In order to obtain the course measurements, the filter uses magnetic sensors and a position-trace based course angle. For preventing magnetic disturbance from contaminating the estimation, the magnetic sensors are attached to the waistband. Because the course angle error is mainly due to the heading error of the IMU, and the characteristic error of the heading angle is highly dependent on that of the course angle, the estimated course angle error is used as a measurement for estimating the heading error in the second stage filter. At the second stage, an inertial navigation system-extended Kalman filter-ZUPT (INS-EKF-ZUPT) method is adopted. As the heading error is estimated directly by using course-angle error measurements, the estimation accuracy for the heading and yaw gyro bias can be enhanced, compared with the ZUPT-only case, which eventually enhances the position accuracy more efficiently. The performance enhancements are verified via experiments, and the way-point position error for the proposed method is compared with those for the ZUPT-only case and with other cases that use ZUPT and various types of magnetic heading measurements. The results show that the position errors are reduced by a maximum of 90% compared with the conventional ZUPT based PDR algorithms.

Optimal hybrid renewable energy design in autonomous system using Modified Electric System Cascade Analysis and Homer software

International Nuclear Information System (INIS)

Zahboune, Hassan; Zouggar, Smail; Krajacic, Goran; Varbanov, Petar Sabev; Elhafyani, Mohammed; Ziani, Elmostafa

2016-01-01

Highlights: • New approach to integrate the Pinch Analysis illustrated. • Total annual cost and loss of power supply probability are the objective functions. • The new Hybrid Cascade Table to determine the optimal system design. • The performances of the new method are compared with Homer Pro. - Abstract: In this paper, a method for designing hybrid electricity generation systems is presented. It is based on the Modified Electric System Cascade Analysis method. The Power Pinch analysis is used as a guideline for development of an isolated power supply system, which consists of photovoltaic panels, wind turbines and energy storage units. The design procedure uses a simulation model, developed using MATLAB/SIMULINK and applies the developed algorithms for obtaining an optimal design. A validation of the Modified Electric System Cascade Analysis method is performed by comparing the obtained results with those from the Homer Pro software. The procedure takes as inputs hourly wind speed, solar radiation, demands, as well as cost data, for the generation and storage facilities. It is also applied to minimize the loss of power supply probability and to minimize the number of storage units. The algorithm has been demonstrated with a case study on a site in Oujda city, with daily electrical energy demand of 18.7 kWh, resulting in a combination of photovoltaic panels, wind turbine and batteries at minimal cost. The results from the Modified Electric System Cascade Analysis and HOMER Pro show that both tools successfully identified the optimal solution with difference of 0.04% in produced energy, 5.4% in potential excess of electricity and 0.07% in the cost of the energy.

Efficiency Analysis of the access method with the cascading Bloom filter to the data warehouse on the parallel computing platform

Science.gov (United States)

Grigoriev, Yu A.; Proletarskaya, V. A.; Ermakov, E. Yu; Ermakov, O. Yu

2017-10-01

A new method was developed with a cascading Bloom filter (CBF) for executing SQL queries in the Apache Spark parallel computing environment. It includes the representation of the original query in the form of several subqueries, the development of a connection graph and the transformation of subqueries, the definition of connections where it is necessary to use Bloom filters, the representation of the graph in terms of Spark. On the example of the query Q3 of the TPC-H test, full-scale experiments were carried out, which confirmed the effectiveness of the developed method.

Federalism and multilevel governance

NARCIS (Netherlands)

van der Wusten, H.; Agnew, J.; Mamadouh, V.; Secor, A.J.; Sharp, J.

2015-01-01

Federalism and multilevel governance both emphasize polycentricity in governing arrangements. With their different intellectual pedigrees, these concepts are discussed in two separate sections. Fragments are now increasingly mixed up in hybrid forms of governance that also encompass originally

Study on control of defect mode in hybrid mirror chirped porous silicon photonic crystal

Science.gov (United States)

Chen, Ying; Luo, Pei; Han, Yangyang; Cui, Xingning; He, Lei

2018-03-01

Based on the optical resonance principle and the tight-binding theory, a hybrid mirror chirped porous silicon photonic crystal is proposed. The control of the defect mode in hybrid mirror chirped porous silicon photonic crystal is studied. Through the numerical simulation, the control regulations of the defect modes resulted by the number of the periodical layers for the fundamental unit and the cascading number of the chirped structures are analyzed, and the split and the degeneration of the defect modes resulted by the change of the relative location between the mirror structures and the quasi-mirror structures are discussed. The simulation results show that the band gap would be broadened with the increase of the chirp quantity and the layer number of unilateral chirp. Adjusting the structural parameters of the hybrid mirror structure, the multimode characteristics will occur in the band gap. The more the cascading number of the chirped units, the more the number of the filtering channels will be. In addition, with the increase of the relative location between the mirror structures and the quasi-mirror structures, the degeneration of the defect modes will occur and can obtain high Q value. The structure can provide effective theoretical references for the design the multi-channel filters and high Q value sensors.

A Hybrid Multilevel Storage Architecture for Electric Power Dispatching Big Data

Science.gov (United States)

Yan, Hu; Huang, Bibin; Hong, Bowen; Hu, Jing

2017-10-01

Electric power dispatching is the center of the whole power system. In the long run time, the power dispatching center has accumulated a large amount of data. These data are now stored in different power professional systems and form lots of information isolated islands. Integrating these data and do comprehensive analysis can greatly improve the intelligent level of power dispatching. In this paper, a hybrid multilevel storage architecture for electrical power dispatching big data is proposed. It introduces relational database and NoSQL database to establish a power grid panoramic data center, effectively meet power dispatching big data storage needs, including the unified storage of structured and unstructured data fast access of massive real-time data, data version management and so on. It can be solid foundation for follow-up depth analysis of power dispatching big data.

Electric control of wave vector filtering in a hybrid magnetic-electric-barrier nanostructure

Science.gov (United States)

Kong, Yong-Hong; Lu, Ke-Yu; He, Ya-Ping; Liu, Xu-Hui; Fu, Xi; Li, Ai-Hua

2018-06-01

We theoretically investigate how to manipulate the wave vector filtering effect by a traverse electric field for electrons across a hybrid magnetic-electric-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe and a Schottky-metal stripe on top and bottom of a GaAs/Al x Ga1- x As heterostructure, respectively. The wave vector filtering effect is found to be related closely to the applied electric field. Moreover, the wave vector filtering efficiency can be manipulated by changing direction or adjusting strength of the traverse electric field. Therefore, such a nanostructure can be employed as an electrically controllable electron-momentum filter for nanoelectronics applications.

Kalman Filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry.

Science.gov (United States)

Zhang, Yuxin; Chen, Shuo; Deng, Kexin; Chen, Bingyao; Wei, Xing; Yang, Jiafei; Wang, Shi; Ying, Kui

2017-01-01

To develop a self-adaptive and fast thermometry method by combining the original hybrid magnetic resonance thermometry method and the bio heat transfer equation (BHTE) model. The proposed Kalman filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry, abbreviated as KalBHT hybrid method, introduced the BHTE model to synthesize a window on the regularization term of the hybrid algorithm, which leads to a self-adaptive regularization both spatially and temporally with change of temperature. Further, to decrease the sensitivity to accuracy of the BHTE model, Kalman filter is utilized to update the window at each iteration time. To investigate the effect of the proposed model, computer heating simulation, phantom microwave heating experiment and dynamic in-vivo model validation of liver and thoracic tumor were conducted in this study. The heating simulation indicates that the KalBHT hybrid algorithm achieves more accurate results without adjusting λ to a proper value in comparison to the hybrid algorithm. The results of the phantom heating experiment illustrate that the proposed model is able to follow temperature changes in the presence of motion and the temperature estimated also shows less noise in the background and surrounding the hot spot. The dynamic in-vivo model validation with heating simulation demonstrates that the proposed model has a higher convergence rate, more robustness to susceptibility problem surrounding the hot spot and more accuracy of temperature estimation. In the healthy liver experiment with heating simulation, the RMSE of the hot spot of the proposed model is reduced to about 50% compared to the RMSE of the original hybrid model and the convergence time becomes only about one fifth of the hybrid model. The proposed model is able to improve the accuracy of the original hybrid algorithm and accelerate the convergence rate of MR temperature estimation.

Pulse design for multilevel systems by utilizing Lie transforms

Science.gov (United States)

Kang, Yi-Hao; Chen, Ye-Hong; Shi, Zhi-Cheng; Huang, Bi-Hua; Song, Jie; Xia, Yan

2018-03-01

We put forward a scheme to design pulses to manipulate multilevel systems with Lie transforms. A formula to reverse construct a control Hamiltonian is given and is applied in pulse design in the three- and four-level systems as examples. To demonstrate the validity of the scheme, we perform numerical simulations, which show the population transfers for cascaded three-level and N -type four-level Rydberg atoms can be completed successfully with high fidelities. Therefore, the scheme may benefit quantum information tasks based on multilevel systems.

Logarithmic r-θ mapping for hybrid optical neural network filter for multiple objects recognition within cluttered scenes

Science.gov (United States)

Kypraios, Ioannis; Young, Rupert C. D.; Chatwin, Chris R.; Birch, Phil M.

2009-04-01

θThe window unit in the design of the complex logarithmic r-θ mapping for hybrid optical neural network filter can allow multiple objects of the same class to be detected within the input image. Additionally, the architecture of the neural network unit of the complex logarithmic r-θ mapping for hybrid optical neural network filter becomes attractive for accommodating the recognition of multiple objects of different classes within the input image by modifying the output layer of the unit. We test the overall filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. Logarithmic r-θ mapping for hybrid optical neural network filter is shown to exhibit with a single pass over the input data simultaneously in-plane rotation, out-of-plane rotation, scale, log r-θ map translation and shift invariance, and good clutter tolerance by recognizing correctly the different objects within the cluttered scenes. We record in our results additional extracted information from the cluttered scenes about the objects' relative position, scale and in-plane rotation.

Hybrid power filter for advanced power quality in industrial systems

Czech Academy of Sciences Publication Activity Database

Švec, J.; Müller, Z.; Kasembe, A. G.; Tlustý, J.; Valouch, Viktor

2013-01-01

Roč. 103, october 2013 (2013), s. 157-167 ISSN 0378-7796 R&D Projects: GA AV ČR IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Institutional support: RVO:61388998 Keywords : hybrid power filter * power quality * industrial system Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.595, year: 2013 http://www.sciencedirect.com/science/article/pii/S0378779613001417

Cascaded impedance networks for NPC inverter

DEFF Research Database (Denmark)

Li, Ding; Gao, Feng; Loh, Poh Chiang

2010-01-01

they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

Interfacial symmetry of Co–Alq{sub 3}–Co hybrid structures for effective spin filtering

Energy Technology Data Exchange (ETDEWEB)

Lam, Tu-Ngoc [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China); Lai, Yu-Ling; Chen, Chih-Han [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC (China); Chen, Po-Hung [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Wei, Der-Hsin; Lin, Hong-Ji; Chen, C.T. [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC (China); Sheu, Jeng-Tzong, E-mail: jtsheu@faculty.nctu.edu.tw [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China); Hsu, Yao-Jane, E-mail: yjhsu@nsrrc.org.tw [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC (China); Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

2015-11-01

Graphical abstract: - Highlights: • The spin interface at Alq{sub 3}/Co and Co/Alq{sub 3} contacts was examined. • An interfacial symmetry was determined at Co–Alq{sub 3}–Co interfaces. • Spin-polarized N orbitals are induced within the Co atop Alq{sub 3} hybridized interface. • The spin-filter role at the top contact interface of Alq{sub 3}/Co is proved. • Effective spin-filtering at Co–Alq{sub 3}–Co contacts was elucidated. - Abstract: Understanding the interfacial behavior at FM-OSC-FM hybrid structures for both the bottom contact (Alq{sub 3} adsorption on Co, Co/Alq{sub 3}) and the top contact (Co atop Alq{sub 3}, Alq{sub 3}/Co) is crucial for efficient spin filtering with transport of spin-polarized charge carriers through these interfaces. X-ray photoelectron spectroscopy (XPS) spectra indicate a symmetry of charge transfer from Co to Alq{sub 3} and the corresponding orbital hybridization to a certain extent at both contacts. The alignment of energy levels at both Alq{sub 3}/Co and Co/Alq{sub 3} heterostructures is depicted with ultraviolet photoelectron spectroscopy (UPS). Through magnetic images acquired with a X-ray photoemission electron microscope (XPEEM), the strong hybridization of the top contact presents no micromagnetic domain but still shows magnetic coupling, to some extent, to the bottom contact in the Co–Alq{sub 3}–Co trilayer structure. Measurements of X-ray magnetic circular dichroism (XMCD) demonstrate the induced spin-polarization of non-magnetic Alq{sub 3} at both contacts, proving Alq{sub 3} a unique and promising organic material for spin filtering in OSV.

New multilevel inverter with reduction of switches and gate driver

Energy Technology Data Exchange (ETDEWEB)

Banaei, M.R., E-mail: m.banaei@azaruniv.ed [Electrical Engineering Department, Faculty of Engineering, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of); Salary, E. [Electrical Engineering Department, Faculty of Engineering, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of)

2011-02-15

This paper presents a novel topology for symmetrical cascade multilevel converter. The proposed circuit consists of series connected sub multilevel converters units and it can generate DC voltage levels similar to other topologies. The proposed topology results in reduction of switches number, losses, installation area and converter cost. This converter has been used in a Dynamic Voltage Restorer (DVR). Simulation results carried out by MATLAB/SIMULINK show the voltage injection capability of converter and the efficiency of its controller in compensating voltage sag and swell.

Is cascade reinforcement likely when sympatric and allopatric populations exchange migrants?

Science.gov (United States)

Yukilevich, Roman; Aoki, Fumio

2016-04-01

When partially reproductively isolated species come back into secondary contact, these taxa may diverge in mating preferences and sexual cues to avoid maladaptive hybridization, a process known as reinforcement. This phenomenon often leads to reproductive character displacement (RCD) between sympatric and allopatric populations of reinforcing species that differ in their exposure to hybridization. Recent discussions have reinvigorated the idea that RCD may give rise to additional speciation between conspecific sympatric and allopatric populations, dubbing the concept "cascade reinforcement." Despite some empirical studies supporting cascade reinforcement, we still know very little about the conditions for its evolution. In the present article, we address this question by developing an individual-based population genetic model that explicitly simulates cascade reinforcement when one of the hybridizing species is split into sympatric and allopatric populations. Our results show that when sympatric and allopatric populations reside in the same environment and only differ in their exposure to maladaptive hybridization, migration between them generally inhibits the evolution of cascade by spreading the reinforcement alleles from sympatry into allopatry and erasing RCD. Under these conditions, cascade reinforcement only evolved when migration rate between sympatric and allopatric populations was very low. This indicates that stabilizing sexual selection in allopatry is generally ineffective in preventing the spread of reinforcement alleles. Only when sympatric and allopatric populations experienced divergent ecological selection did cascade reinforcement evolve in the presence of substantial migration. These predictions clarify the conditions for cascade reinforcement and facilitate our understanding of existing cases in nature.

Proposal of a resonant controller for a three phase four wire grid-connected shunt hybrid filter

DEFF Research Database (Denmark)

Candela, J. I.; Rodriguez, P.; Luna, A.

2009-01-01

This paper present a three-phase four wire hybrid filter able to perform a selective cancellation of harmonic currents based on resonant controllers. As it will be shown in this work, this kind of control permits to enhance the bandwidth of the filter controller, without hindering the stability...

High-order UWB pulses scheme to generate multilevel modulation formats based on incoherent optical sources.

Science.gov (United States)

Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

2013-11-18

We present a high-order UWB pulses generator based on a microwave photonic filter which provides a set of positive and negative samples by using the slicing of an incoherent optical source and the phase inversion in a Mach-Zehnder modulator. The simple scalability and high reconfigurability of the system permit a better accomplishment of the FCC requirements. Moreover, the proposed scheme permits an easy adaptation to pulse amplitude modulation, bi phase modulation, pulse shape modulation and pulse position modulation. The flexibility of the scheme for being adaptable to multilevel modulation formats permits to increase the transmission bit rate by using hybrid modulation formats.

Localness of energy cascade in hydrodynamic turbulence, II. Sharp spectral filter

Energy Technology Data Exchange (ETDEWEB)

Aluie, Hussein [Los Alamos National Laboratory; Eyink, Gregory L [JOHNS HOPKINS UNIV.

2009-01-01

We investigate the scale-locality of subgrid-scale (SGS) energy flux and interband energy transfers defined by the sharp spectral filter. We show by rigorous bounds, physical arguments, and numerical simulations that the spectral SGS flux is dominated by local triadic interactions in an extended turbulent inertial range. Interband energy transfers are also shown to be dominated by local triads if the spectral bands have constant width on a logarithmic scale. We disprove in particular an alternative picture of 'local transfer by nonlocal triads,' with the advecting wavenumber mode at the energy peak. Although such triads have the largest transfer rates of all individual wavenumber triads, we show rigorously that, due to their restricted number, they make an asymptotically negligible contribution to energy flux and log-banded energy transfers at high wavenumbers in the inertial range. We show that it is only the aggregate effect of a geometrically increasing number of local wavenumber triads which can sustain an energy cascade to small scales. Furthermore, nonlocal triads are argued to contribute even less to the space-average energy flux than is implied by our rigorous bounds, because of additional cancellations from scale-decorrelation effects. We can thus recover the -4/3 scaling of nonlocal contributions to spectral energy flux predicted by Kraichnan's abridged Lagrangian-history direct-interaction approximation and test-field model closures. We support our results with numerical data from a 512{sup 3} pseudospectral simulation of isotropic turbulence with phase-shift dealiasing. We also discuss a rigorous counterexample of Eyink [Physica D 78, 222 (1994)], which showed that nonlocal wavenumber triads may dominate in the sharp spectral flux (but not in the SGS energy flux for graded filters). We show that this mathematical counter example fails to satisfy reasonable physical requirements for a turbulent velocity field, which are employed in our

Organic/inorganic hybrid filters based on dendritic and cyclodextrin "nanosponges" for the removal of organic pollutants from water.

Science.gov (United States)

Arkas, Michael; Allabashi, Roza; Tsiourvas, Dimitris; Mattausch, Eva-Maria; Perfler, Reinhard

2006-04-15

Long-alkyl chain functionalized poly(propylene imine) dendrimer, poly(ethylene imine) hyperbranched polymer, and beta-cyclodextrin derivatives, which are completely insoluble in water, have the property of encapsulating organic pollutants from water. Ceramic porous filters can be impregnated with these compounds resulting in hybrid organic/ inorganic filter modules. These hybrid filter modules were tested for the effective purification of water, by continuous filtration experiments, employing a variety of water pollutants. It has been established that polycyclic aromatic hydrocarbons (PAHs) can be removed very efficiently (more than 95%), and final concentrations of several ppb (microg/ L) are easily obtained. Representatives of the pollutant group of trihalogen methanes (THMs), monoaromatic hydrocarbons (BTX), and pesticides (simazine) can also be removed (>80%), although the filters are saturated considerably faster in these cases.

Multi-level and hybrid modelling approaches for systems biology.

Science.gov (United States)

Bardini, R; Politano, G; Benso, A; Di Carlo, S

2017-01-01

During the last decades, high-throughput techniques allowed for the extraction of a huge amount of data from biological systems, unveiling more of their underling complexity. Biological systems encompass a wide range of space and time scales, functioning according to flexible hierarchies of mechanisms making an intertwined and dynamic interplay of regulations. This becomes particularly evident in processes such as ontogenesis, where regulative assets change according to process context and timing, making structural phenotype and architectural complexities emerge from a single cell, through local interactions. The information collected from biological systems are naturally organized according to the functional levels composing the system itself. In systems biology, biological information often comes from overlapping but different scientific domains, each one having its own way of representing phenomena under study. That is, the different parts of the system to be modelled may be described with different formalisms. For a model to have improved accuracy and capability for making a good knowledge base, it is good to comprise different system levels, suitably handling the relative formalisms. Models which are both multi-level and hybrid satisfy both these requirements, making a very useful tool in computational systems biology. This paper reviews some of the main contributions in this field.

New hybrid genetic particle swarm optimization algorithm to design multi-zone binary filter.

Science.gov (United States)

Lin, Jie; Zhao, Hongyang; Ma, Yuan; Tan, Jiubin; Jin, Peng

2016-05-16

The binary phase filters have been used to achieve an optical needle with small lateral size. Designing a binary phase filter is still a scientific challenge in such fields. In this paper, a hybrid genetic particle swarm optimization (HGPSO) algorithm is proposed to design the binary phase filter. The HGPSO algorithm includes self-adaptive parameters, recombination and mutation operations that originated from the genetic algorithm. Based on the benchmark test, the HGPSO algorithm has achieved global optimization and fast convergence. In an easy-to-perform optimizing procedure, the iteration number of HGPSO is decreased to about a quarter of the original particle swarm optimization process. A multi-zone binary phase filter is designed by using the HGPSO. The long depth of focus and high resolution are achieved simultaneously, where the depth of focus and focal spot transverse size are 6.05λ and 0.41λ, respectively. Therefore, the proposed HGPSO can be applied to the optimization of filter with multiple parameters.

Using variable DC sources in order to improve the voltage quality of a multilevel STATCOM with low frequency modulation

DEFF Research Database (Denmark)

Dowlatabadi, Mohammadkazem Bakhshizadeh; Najjar, Mohammad; Blaabjerg, Frede

2016-01-01

In this paper, a Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) method, which utilizes adjustable dc links, is presented for a Static Synchronous Compensator (STATCOM) based on Cascaded H-Bridge (CHB) multilevel converter. The proposed switching algorithm is able to fix the capac......In this paper, a Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) method, which utilizes adjustable dc links, is presented for a Static Synchronous Compensator (STATCOM) based on Cascaded H-Bridge (CHB) multilevel converter. The proposed switching algorithm is able to fix...... unequal dc link voltages more levels at the output is achievable compared to the symmetrical multilevel converters that could be used in enhancing the power quality, while keeping the switching frequency near the fundamental (the maximum switching frequency can be kept below 150 Hz). The validity...

Hybrid Adaptive Multilevel Monte Carlo Algorithm for Non-Smooth Observables of Itô Stochastic Differential Equations

KAUST Repository

Rached, Nadhir B.

2014-01-06

A new hybrid adaptive MC forward Euler algorithm for SDEs with singular coefficients and non-smooth observables is developed. This adaptive method is based on the derivation of a new error expansion with computable leading order terms. When a non-smooth binary payoff is considered, the new adaptive method achieves the same complexity as the uniform discretization with smooth problems. Moreover, the new developed algorithm is extended to the multilevel Monte Carlo (MLMC) forward Euler setting which reduces the complexity from O(TOL-3) to O(TOL-2(log(TOL))2). For the binary option case, it recovers the standard multilevel computational cost O(TOL-2(log(TOL))2). When considering a higher order Milstein scheme, a similar complexity result was obtained by Giles using the uniform time stepping for one dimensional SDEs, see [2]. The difficulty to extend Giles’ Milstein MLMC method to the multidimensional case is an argument for the flexibility of our new constructed adaptive MLMC forward Euler method which can be easily adapted to this setting. Similarly, the expected complexity O(TOL-2(log(TOL))2) is reached for the multidimensional case and verified numerically.

Hybrid Adaptive Multilevel Monte Carlo Algorithm for Non-Smooth Observables of Itô Stochastic Differential Equations

KAUST Repository

Rached, Nadhir B.; Hoel, Haakon; Tempone, Raul

2014-01-01

A new hybrid adaptive MC forward Euler algorithm for SDEs with singular coefficients and non-smooth observables is developed. This adaptive method is based on the derivation of a new error expansion with computable leading order terms. When a non-smooth binary payoff is considered, the new adaptive method achieves the same complexity as the uniform discretization with smooth problems. Moreover, the new developed algorithm is extended to the multilevel Monte Carlo (MLMC) forward Euler setting which reduces the complexity from O(TOL-3) to O(TOL-2(log(TOL))2). For the binary option case, it recovers the standard multilevel computational cost O(TOL-2(log(TOL))2). When considering a higher order Milstein scheme, a similar complexity result was obtained by Giles using the uniform time stepping for one dimensional SDEs, see [2]. The difficulty to extend Giles’ Milstein MLMC method to the multidimensional case is an argument for the flexibility of our new constructed adaptive MLMC forward Euler method which can be easily adapted to this setting. Similarly, the expected complexity O(TOL-2(log(TOL))2) is reached for the multidimensional case and verified numerically.

Simulasi Filter Pasif Dan Perbandingan Unjuk Kerjanya Dengan Filter Aktif Dan Filter Aktif Hibrid Dalam Meredam Harmonisa Pada Induction Furnace

OpenAIRE

Tanoto, Yusak; Limantara, Limboto; Khandy Lestanto, Khristian

2005-01-01

This paper describe about simulation of Passive Filter in analysis to reduce harmonics that happened in a load such as vacuum casting induction furnace 9 kW, 13.8 kVA, 200V, 3 Ph, 50/60 Hz, also gives comparison with Hybrid Active Filter and Active Filter which made satisfaction result on the previous research. The best result achieved on the use of Hybrid Active Filter on %ITHD for 4.27 % and %VTHD for 3.83%, while Active Filter gave on %ITHD for 5.14 % and %VTHD for 3.82%. There ...

Hybrid extended particle filter (HEPF) for integrated inertial navigation and global positioning systems

International Nuclear Information System (INIS)

Aggarwal, Priyanka; Syed, Zainab; El-Sheimy, Naser

2009-01-01

Navigation includes the integration of methodologies and systems for estimating time-varying position, velocity and attitude of moving objects. Navigation incorporating the integrated inertial navigation system (INS) and global positioning system (GPS) generally requires extensive evaluations of nonlinear equations involving double integration. Currently, integrated navigation systems are commonly implemented using the extended Kalman filter (EKF). The EKF assumes a linearized process, measurement models and Gaussian noise distributions. These assumptions are unrealistic for highly nonlinear systems like land vehicle navigation and may cause filter divergence. A particle filter (PF) is developed to enhance integrated INS/GPS system performance as it can easily deal with nonlinearity and non-Gaussian noises. In this paper, a hybrid extended particle filter (HEPF) is developed as an alternative to the well-known EKF to achieve better navigation data accuracy for low-cost microelectromechanical system sensors. The results show that the HEPF performs better than the EKF during GPS outages, especially when simulated outages are located in periods with high vehicle dynamics

A Hybrid Approach using Collaborative filtering and Content based Filtering for Recommender System

Science.gov (United States)

Geetha, G.; Safa, M.; Fancy, C.; Saranya, D.

2018-04-01

In today’s digital world, it has become an irksome task to find the content of one's liking in an endless variety of content that are being consumed like books, videos, articles, movies, etc. On the other hand there has been an emerging growth among the digital content providers who want to engage as many users on their service as possible for the maximum time. This gave birth to the recommender system comes wherein the content providers recommend users the content according to the users’ taste and liking. In this paper we have proposed a movie recommendation system. A movie recommendation is important in our social life due to its features such as suggesting a set of movies to users based on their interest, or the popularities of the movies. In this paper we are proposing a movie recommendation system that has the ability to recommend movies to a new user as well as the other existing users. It mines movie databases to collect all the important information, such as, popularity and attractiveness, which are required for recommendation. We use content-based and collaborative filtering and also hybrid filtering, which is a combination of the results of these two techniques, to construct a system that provides more precise recommendations concerning movies.

Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition.

Science.gov (United States)

Portalupi, Simone Luca; Widmann, Matthias; Nawrath, Cornelius; Jetter, Michael; Michler, Peter; Wrachtrup, Jörg; Gerhardt, Ilja

2016-11-25

Hybrid quantum systems integrating semiconductor quantum dots (QDs) and atomic vapours become important building blocks for scalable quantum networks due to the complementary strengths of individual parts. QDs provide on-demand single-photon emission with near-unity indistinguishability comprising unprecedented brightness-while atomic vapour systems provide ultra-precise frequency standards and promise long coherence times for the storage of qubits. Spectral filtering is one of the key components for the successful link between QD photons and atoms. Here we present a tailored Faraday anomalous dispersion optical filter based on the caesium-D 1 transition for interfacing it with a resonantly pumped QD. The presented Faraday filter enables a narrow-bandwidth (Δω=2π × 1 GHz) simultaneous filtering of both Mollow triplet sidebands. This result opens the way to use QDs as sources of single as well as cascaded photons in photonic quantum networks aligned to the primary frequency standard of the caesium clock transition.

Passive Reactor Compensated Cascaded H-Bridge Multilevel LC-StatCom

DEFF Research Database (Denmark)

Farivar, Glen; Townsend, Christopher David; Hredzak, Branislav

2017-01-01

The cascaded H-bridge (CHB) low-capacitance StatCom (LC-StatCom) has a limited operating area in the inductive region compared to a conventional StatCom's V–I characteristic. This limitation for operation in the inductive region is considered to be the biggest disadvantage of CHB LC-StatCom. In t...

A fast Gaussian filtering algorithm for three-dimensional surface roughness measurements

International Nuclear Information System (INIS)

Yuan, Y B; Piao, W Y; Xu, J B

2007-01-01

The two-dimensional (2-D) Gaussian filter can be separated into two one-dimensional (1-D) Gaussian filters. The 1-D Gaussian filter can be implemented approximately by the cascaded Butterworth filters. The approximation accuracy will be improved with the increase of the number of the cascaded filters. A recursive algorithm for Gaussian filtering requires a relatively small number of simple mathematical operations such as addition, subtraction, multiplication, or division, so that it has considerable computational efficiency and it is very useful for three-dimensional (3-D) surface roughness measurements. The zero-phase-filtering technique is used in this algorithm, so there is no phase distortion in the Gaussian filtered mean surface. High-order approximation Gaussian filters are proposed for practical use to assure high accuracy of Gaussian filtering of 3-D surface roughness measurements

A fast Gaussian filtering algorithm for three-dimensional surface roughness measurements

Science.gov (United States)

Yuan, Y. B.; Piao, W. Y.; Xu, J. B.

2007-07-01

The two-dimensional (2-D) Gaussian filter can be separated into two one-dimensional (1-D) Gaussian filters. The 1-D Gaussian filter can be implemented approximately by the cascaded Butterworth filters. The approximation accuracy will be improved with the increase of the number of the cascaded filters. A recursive algorithm for Gaussian filtering requires a relatively small number of simple mathematical operations such as addition, subtraction, multiplication, or division, so that it has considerable computational efficiency and it is very useful for three-dimensional (3-D) surface roughness measurements. The zero-phase-filtering technique is used in this algorithm, so there is no phase distortion in the Gaussian filtered mean surface. High-order approximation Gaussian filters are proposed for practical use to assure high accuracy of Gaussian filtering of 3-D surface roughness measurements.

One-Level or Multilevel Interbody Fusion for Multilevel Lumbar Degenerative Diseases: A Prospective Randomized Control Study with a 4-Year Follow-Up.

Science.gov (United States)

Li, Tiefeng; Shi, Lei; Luo, Yibin; Chen, Deyu; Chen, Yu

2018-02-01

The treatment of multilevel lumbar degenerative disease (LDD) is complicated and challenging, and the optimal surgical strategy remains controversial. To compare the differences in clinical and radiologic outcomes and in complications after 1-level interbody fusion versus multilevel interbody fusion for the treatment of multilevel LDD. A total of 100 patients with multilevel LDD were randomized in a 1:1 ratio into the 1-level interbody fusion group or the multilevel interbody fusion group. Clinical and radiologic results and major complications in the 2 groups were analyzed. Clinical outcomes were assessed using the Visual Analog Scale for radicular and back pain, the Oswestry Disability Index, and the short-form 36 physical score. Clinical status was assessed by the Whitecloud classification. Radiologic evaluation included assessment of lumbar lordosis, pelvic incidence, and sacral slope. There were no significant differences in clinical and radiologic results between the 2 groups. Procedure duration and intraoperative blood loss were significantly greater in the multilevel interbody fusion group than in the 1-level interbody fusion group; the multilevel interbody fusion group also had greater incidences of temporary nerve root palsy, wound infection, and adjacent segment disease. A hybrid technique including 1-level interbody fusion and multilevel posterolateral fusion is recommended for patients with multilevel LDD. Copyright © 2017 Elsevier Inc. All rights reserved.

Error rate performance of narrowband multilevel CPFSK signals

Science.gov (United States)

Ekanayake, N.; Fonseka, K. J. P.

1987-04-01

The paper presents a relatively simple method for analyzing the effect of IF filtering on the performance of multilevel FM signals. Using this method, the error rate performance of narrowband FM signals is analyzed for three different detection techniques, namely limiter-discriminator detection, differential detection and coherent detection followed by differential decoding. The symbol error probabilities are computed for a Gaussian IF filter and a second-order Butterworth IF filter. It is shown that coherent detection and differential decoding yields better performance than limiter-discriminator detection and differential detection, whereas two noncoherent detectors yield approximately identical performance.

Multilevel Image Segmentation Based on an Improved Firefly Algorithm

Directory of Open Access Journals (Sweden)

Kai Chen

2016-01-01

Full Text Available Multilevel image segmentation is time-consuming and involves large computation. The firefly algorithm has been applied to enhancing the efficiency of multilevel image segmentation. However, in some cases, firefly algorithm is easily trapped into local optima. In this paper, an improved firefly algorithm (IFA is proposed to search multilevel thresholds. In IFA, in order to help fireflies escape from local optima and accelerate the convergence, two strategies (i.e., diversity enhancing strategy with Cauchy mutation and neighborhood strategy are proposed and adaptively chosen according to different stagnation stations. The proposed IFA is compared with three benchmark optimal algorithms, that is, Darwinian particle swarm optimization, hybrid differential evolution optimization, and firefly algorithm. The experimental results show that the proposed method can efficiently segment multilevel images and obtain better performance than the other three methods.

Analytical Modeling and Simulation of Four-Switch Hybrid Power Filter Working with Sixfold Switching Symmetry

Czech Academy of Sciences Publication Activity Database

Tlustý, J.; Škramlík, Jiří; Švec, J.; Valouch, Viktor

2012-01-01

Roč. 2012, č. 292178 (2012), s. 1-17 ISSN 1024-123X Institutional support: RVO:61388998 Keywords : analytical modeling * four-switch hybrid power filter * sixfold switching symmetry Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.383, year: 2012 http://www.hindawi.com/journals/mpe/2012/292178/

Design of low complexity sharp MDFT filter banks with perfect reconstruction using hybrid harmony-gravitational search algorithm

Directory of Open Access Journals (Sweden)

V. Sakthivel

2015-12-01

Full Text Available The design of low complexity sharp transition width Modified Discrete Fourier Transform (MDFT filter bank with perfect reconstruction (PR is proposed in this work. The current trends in technology require high data rates and speedy processing along with reduced power consumption, implementation complexity and chip area. Filters with sharp transition width are required for various applications in wireless communication. Frequency response masking (FRM technique is used to reduce the implementation complexity of sharp MDFT filter banks with PR. Further, to reduce the implementation complexity, the continuous coefficients of the filters in the MDFT filter banks are represented in discrete space using canonic signed digit (CSD. The multipliers in the filters are replaced by shifters and adders. The number of non-zero bits is reduced in the conversion process to minimize the number of adders and shifters required for the filter implementation. Hence the performances of the MDFT filter bank with PR may degrade. In this work, the performances of the MDFT filter banks with PR are improved using a hybrid Harmony-Gravitational search algorithm.

New Integrated Multilevel Converter for Switched Reluctance Motor Drives in Plug-in Hybrid Electric Vehicles with Flexible Energy Conversion

DEFF Research Database (Denmark)

Gan, Chun; Wu, Jianhua; Hu, Yihua

2017-01-01

This paper presents an integrated multilevel converter of switched reluctance motors (SRMs) fed by a modular front-end circuit for plug-in hybrid electric vehicle (PHEV) applications. Several operating modes can be achieved by changing the on-off states of the switches in the front-end circuit......, the battery can be charged by the external AC source or generator when the vehicle is in standstill condition. The SRM-based PHEV can operate at different speeds by coordinating power flow from the generator and battery. Simulation in MATLAB/Simulink and experiments on a three-phase 12/8 SRM confirm...

Filter-Adapted Fluorescent In Situ Hybridization (FA-FISH) for Filtration-Enriched Circulating Tumor Cells.

Science.gov (United States)

Oulhen, Marianne; Pailler, Emma; Faugeroux, Vincent; Farace, Françoise

2017-01-01

Circulating tumor cells (CTCs) may represent an easily accessible source of tumor material to assess genetic aberrations such as gene-rearrangements or gene-amplifications and screen cancer patients eligible for targeted therapies. As the number of CTCs is a critical parameter to identify such biomarkers, we developed fluorescent in situ hybridization (FISH) for CTCs enriched on filters (filter-adapted-FISH, FA-FISH). Here, we describe the FA-FISH protocol, the combination of immunofluorescent staining (DAPI/CD45) and FA-FISH techniques, as well as the semi-automated microscopy method that we developed to improve the feasibility and reliability of FISH analyses in filtration-enriched CTC.

Hybrid Multilevel Monte Carlo Simulation of Stochastic Reaction Networks

KAUST Repository

Moraes, Alvaro

2015-01-07

Stochastic reaction networks (SRNs) is a class of continuous-time Markov chains intended to describe, from the kinetic point of view, the time-evolution of chemical systems in which molecules of different chemical species undergo a finite set of reaction channels. This talk is based on articles [4, 5, 6], where we are interested in the following problem: given a SRN, X, defined though its set of reaction channels, and its initial state, x0, estimate E (g(X(T))); that is, the expected value of a scalar observable, g, of the process, X, at a fixed time, T. This problem lead us to define a series of Monte Carlo estimators, M, such that, with high probability can produce values close to the quantity of interest, E (g(X(T))). More specifically, given a user-selected tolerance, TOL, and a small confidence level, η, find an estimator, M, based on approximate sampled paths of X, such that, P (|E (g(X(T))) − M| ≤ TOL) ≥ 1 − η; even more, we want to achieve this objective with near optimal computational work. We first introduce a hybrid path-simulation scheme based on the well-known stochastic simulation algorithm (SSA)[3] and the tau-leap method [2]. Then, we introduce a Multilevel Monte Carlo strategy that allows us to achieve a computational complexity of order O(T OL−2), this is the same computational complexity as in an exact method but with a smaller constant. We provide numerical examples to show our results.

A hybrid filter to mitigate harmonics caused by nonlinear load and resonance caused by power factor correction capacitor

Science.gov (United States)

Adan, N. F.; Soomro, D. M.

2017-01-01

Power factor correction capacitor (PFCC) is commonly installed in industrial applications for power factor correction (PFC). With the expanding use of non-linear equipment such as ASDs, power converters, etc., power factor (PF) improvement has become difficult due to the presence of harmonics. The resulting capacitive impedance of the PFCC may form a resonant circuit with the source inductive reactance at a certain frequency, which is likely to coincide with one of the harmonic frequency of the load. This condition will trigger large oscillatory currents and voltages that may stress the insulation and cause subsequent damage to the PFCC and equipment connected to the power system (PS). Besides, high PF cannot be achieved due to power distortion. This paper presents the design of a three-phase hybrid filter consisting of a single tuned passive filter (STPF) and shunt active power filter (SAPF) to mitigate harmonics and resonance in the PS through simulation using PSCAD/EMTDC software. SAPF was developed using p-q theory. The hybrid filter has resulted in significant improvement on both total harmonic distortion for voltage (THDV) and total demand distortion for current (TDDI) with maximum values of 2.93% and 9.84% respectively which were within the recommended IEEE 519-2014 standard limits. Regarding PF improvement, the combined filters have achieved PF close to desired PF at 0.95 for firing angle, α values up to 40°.

Hybrid Multi-objective Forecasting of Solar Photovoltaic Output Using Kalman Filter based Interval Type-2 Fuzzy Logic System

DEFF Research Database (Denmark)

Hassan, Saima; Ahmadieh Khanesar, Mojtaba; Hajizadeh, Amin

2017-01-01

Learning of fuzzy parameters for system modeling using evolutionary algorithms is an interesting topic. In this paper, two optimal design and tuning of Interval type-2 fuzzy logic system are proposed using hybrid learning algorithms. The consequent parameters of the interval type-2 fuzzy logic...... system in both the hybrid algorithms are tuned using Kalman filter. Whereas the antecedent parameters of the system in the first hybrid algorithm is optimized using the multi-objective particle swarm optimization (MOPSO) and using the multi-objective evolutionary algorithm Based on Decomposition (MOEA...

Multilevel techniques for Reservoir Simulation

DEFF Research Database (Denmark)

Christensen, Max la Cour

The subject of this thesis is the development, application and study of novel multilevel methods for the acceleration and improvement of reservoir simulation techniques. The motivation for addressing this topic is a need for more accurate predictions of porous media flow and the ability to carry...... Full Approximation Scheme) • Variational (Galerkin) upscaling • Linear solvers and preconditioners First, a nonlinear multigrid scheme in the form of the Full Approximation Scheme (FAS) is implemented and studied for a 3D three-phase compressible rock/fluids immiscible reservoir simulator...... is extended to include a hybrid strategy, where FAS is combined with Newton’s method to construct a multilevel nonlinear preconditioner. This method demonstrates high efficiency and robustness. Second, an improved IMPES formulated reservoir simulator is implemented using a novel variational upscaling approach...

Multilevel Bloom Filters for P2P Flows Identification Based on Cluster Analysis in Wireless Mesh Network

Directory of Open Access Journals (Sweden)

Xia-an Bi

2015-01-01

Full Text Available With the development of wireless mesh networks and distributed computing, lots of new P2P services have been deployed and enrich the Internet contents and applications. The rapid growth of P2P flows brings great pressure to the regular network operation. So the effective flow identification and management of P2P applications become increasingly urgent. In this paper, we build a multilevel bloom filters data structure to identify the P2P flows through researches on the locality characteristics of P2P flows. Different level structure stores different numbers of P2P flow rules. According to the characteristics values of the P2P flows, we adjust the parameters of the data structure of bloom filters. The searching steps of the scheme traverse from the first level to the last level. Compared with the traditional algorithms, our method solves the drawbacks of previous schemes. The simulation results demonstrate that our algorithm effectively enhances the performance of P2P flows identification. Then we deploy our flow identification algorithm in the traffic monitoring sensors which belong to the network traffic monitoring system at the export link in the campus network. In the real environment, the experiment results demonstrate that our algorithm has a fast speed and high accuracy to identify the P2P flows; therefore, it is suitable for actual deployment.

Enhancement of DFIG-Wind Turbine’s LVRT capability using novel DVR based Odd-nary Cascaded Asymmetric Multi-Level Inverter

Directory of Open Access Journals (Sweden)

A.D. Falehi

2017-06-01

Full Text Available One of the most prominent issues relevant to Doubly Fed Induction Generator (DFIG is augmentation of its Low Voltage Ride Through (LVRT capability. Dynamic Voltage Restorer (DVR is a series kind of Distributed-Flexible AC Transmission Systems (D-FACTS that is here occupied to preserve the DFIG from the voltage sag whenever a fault to be occurred in the power system. Multi-Level Inverter (MLI is the beating-heart of DVR with unique responsibility of synthesizing a staircase sinusoidal voltage from the DC voltage sources. In this regard, it is immensely important a high performance and cost-effective MLI to be embedded into the DVR. In this paper, a novel MLI is introduced to provide a staircase sinusoidal voltage with high level numbers against less switch numbers as compared to the other kinds of MLIs. By adding the bi-directional switches and capacitors of sub-MLI as well as amount of DC sources, the held forth MLI can also operate as so-called “Odd-nary” Cascaded Asymmetric Multi-Level Inverter (OCAMLI. The performance of proposed DVR based on OCAMLI i.e., DVR-OCAMLI has been thoroughly evaluated under deep and shallow balanced and unbalanced voltage sags so that its LVRT capability to be cleared up. To more scrutinize the performance of DVR-OCAMLI, it has been withal dealt with under severe and slight voltage swells as well as harmonic voltage. The accuracy and performance of DVR-OCAMLI has been furthermore compared with conventional DVR. To sum up, the relevant analytical study along with the simulation results has transparently corroborated the performance of OCAMLI as compared to other MLIs. Meanwhile, the DVR-OCAMLI has significantly compensated deep and shallow symmetric and asymmetric voltage sags to enhance the LVRT capability of DFIG; correspondingly, the severe and slight symmetric and asymmetric voltage swells as well as voltage harmonic have been exceptionally compensated as compared to conventional DVR.

Hybrid vs Adaptive Ensemble Kalman Filtering for Storm Surge Forecasting

Science.gov (United States)

Altaf, M. U.; Raboudi, N.; Gharamti, M. E.; Dawson, C.; McCabe, M. F.; Hoteit, I.

2014-12-01

Recent storm surge events due to Hurricanes in the Gulf of Mexico have motivated the efforts to accurately forecast water levels. Toward this goal, a parallel architecture has been implemented based on a high resolution storm surge model, ADCIRC. However the accuracy of the model notably depends on the quality and the recentness of the input data (mainly winds and bathymetry), model parameters (e.g. wind and bottom drag coefficients), and the resolution of the model grid. Given all these uncertainties in the system, the challenge is to build an efficient prediction system capable of providing accurate forecasts enough ahead of time for the authorities to evacuate the areas at risk. We have developed an ensemble-based data assimilation system to frequently assimilate available data into the ADCIRC model in order to improve the accuracy of the model. In this contribution we study and analyze the performances of different ensemble Kalman filter methodologies for efficient short-range storm surge forecasting, the aim being to produce the most accurate forecasts at the lowest possible computing time. Using Hurricane Ike meteorological data to force the ADCIRC model over a domain including the Gulf of Mexico coastline, we implement and compare the forecasts of the standard EnKF, the hybrid EnKF and an adaptive EnKF. The last two schemes have been introduced as efficient tools for enhancing the behavior of the EnKF when implemented with small ensembles by exploiting information from a static background covariance matrix. Covariance inflation and localization are implemented in all these filters. Our results suggest that both the hybrid and the adaptive approach provide significantly better forecasts than those resulting from the standard EnKF, even when implemented with much smaller ensembles.

Control strategies of active filters in the context of power conditioning

DEFF Research Database (Denmark)

Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.

2005-01-01

performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter is studied for current harmonic compensation. The hybrid filter is formed by a single tuned LC filter per phase and a small-rated power three-phase active filter......Active Power Filters have been intensively explored in the past decade. Various topologies and control schemes have been documented aiming at reducing the cost and improving the performance of the compensation system. Hybrid active filters inherit the efficiency of passive filters and the improved......, which are directly connected in series without any matching transformer. The required rating of the active filter is much smaller than a conventional standalone active filter would be. No additional switching-ripple filter is required for the hybrid filter because the LC filter functions not only...

Design and Comparison of Cascaded H-Bridge, Modular Multilevel Converter, and 5-L Active Neutral Point Clamped Topologies for Motor Drive Applications

Energy Technology Data Exchange (ETDEWEB)

Marzoughi, Alinaghi [Virginia Tech, Blacksburg, VA (United States). Center for Power Electronics Systems; Burgos, Rolando [Virginia Tech, Blacksburg, VA (United States). Bradley Dept. of Electrical and Computer Engineering; Boroyevich, Dushan [Virginia Tech, Blacksburg, VA (United States). Bradley Dept. of Electrical and Computer Engineering; Xue, Yaosuo [Siemens Corporate Research, Princeton, NJ (United States). Power Electronics Dept.

2018-03-01

This paper presents the design procedure and comparison of converters currently used in medium-voltage high-power motor drive applications. For this purpose, the cascaded H-bridge (CHB), modular multilevel converter (MMC), and five-level active neutral point clamped (5-L ANPC) topologies are targeted. The design is performed using 1.7-kV insulated gate bipolar transistors (IGBTs) for CHB and MMC converters, and utilizing 3.3- and 4.5-kV IGBTs for 5-L ANPC topology as normally done in industry. The comparison is done between the designed converter topologies at three different voltage levels (4.16, 6.9, and 13.8 kV, with only the first two voltage levels in case of the 5-L ANPC) and two different power levels (3 and 5 MVA), in order to elucidate the dependence of different parameters on voltage and power rating. Finally, the comparison is done from several points of view such as efficiency, capacitive energy storage, semiconductor utilization, parts count (for measure of reliability), and power density.

Multi-tap complex-coefficient incoherent microwave photonic filters based on optical single-sideband modulation and narrow band optical filtering.

Science.gov (United States)

Sagues, Mikel; García Olcina, Raimundo; Loayssa, Alayn; Sales, Salvador; Capmany, José

2008-01-07

We propose a novel scheme to implement tunable multi-tap complex coefficient filters based on optical single sideband modulation and narrow band optical filtering. A four tap filter is experimentally demonstrated to highlight the enhanced tuning performance provided by complex coefficients. Optical processing is performed by the use of a cascade of four phase-shifted fiber Bragg gratings specifically fabricated for this purpose.

Reconfigurable Mixed Mode Universal Filter

Directory of Open Access Journals (Sweden)

Neelofer Afzal

2014-01-01

Full Text Available This paper presents a novel mixed mode universal filter configuration capable of working in voltage and transimpedance mode. The proposed single filter configuration can be reconfigured digitally to realize all the five second order filter functions (types at single output port. Other salient features of proposed configuration include independently programmable filter parameters, full cascadability, and low sensitivity figure. However, all these features are provided at the cost of quite large number of active elements. It needs three digitally programmable current feedback amplifiers and three digitally programmable current conveyors. Use of six active elements is justified by introducing three additional reduced hardware mixed mode universal filter configurations and its comparison with reported filters.

Triple Line-Voltage Cascaded VIENNA Converter Applied as the Medium-Voltage AC Drive

Directory of Open Access Journals (Sweden)

Jia Zou

2018-04-01

Full Text Available A novel rectifier based on a triple line-voltage cascaded VIENNA converter (LVC-VC was proposed. Compared to the conventional cascaded H-bridge converters, the switch voltage stress is lower, and the numbers of switches and dc capacitors are fewer under similar operating conditions in the proposed new multilevel converter. The modeling and control for the LVC-VC ware presented. Based on the analysis of the operation principle of the new converter, the power factor correction of the proposed converter was realized by employing a traditional one-cycle control strategy. The minimum average value and maximum harmonic components of the dc-link voltages of the three VIENNA rectifier modules ware calculated. Three VIENNA dc-link voltages were unbalanced under the unbalanced load conditions, so the zero sequence current was injected to the three inner currents for balancing three VIENNA dc-link voltages. Simulation and the results of the experiment verified the availability of the new proposed multilevel converter and the effectiveness of the corresponding control strategy applied.

Gaussian shaping filter for nuclear spectrometry

International Nuclear Information System (INIS)

Menezes, A.S.C. de.

1980-01-01

A theorical study of a gaussian shaping filter, using Pade approximation, for using in gamma spectroscopy is presented. This approximation has proved superior to the classical cascade RC integrators approximation in therms of signal-to-noise ratio and pulse simmetry. An experimental filter was designed, simulated in computer, constructed, and tested in the laboratory. (author) [pt

Ultrasensitive Faraday cage-type electrochemiluminescence assay for femtomolar miRNA-141 via graphene oxide and hybridization chain reaction-assisted cascade amplification.

Science.gov (United States)

Lu, Jing; Wu, Lin; Hu, Yufang; Wang, Sui; Guo, Zhiyong

2018-06-30

In this study, a novel electrochemiluminescence (ECL) biosensor for sensitive detection of femtomolar miRNA-141 was constructed on the basis of Faraday cage-type strategy via graphene oxide (GO) and hybridization chain reaction (HCR)-assisted cascade amplification. A capture probe (CP) was immobilized on Fe 3 O 4 @SiO 2 @Au nanoparticles as capture unit, which could catch the miRNA-141, and the immobilization of the signal unit (Ru(phen) 3 2+ -HCR/GO) was allowed via nucleic acid hybridization. The prepared biosensor exhibited two advantages for signal amplification: firstly, GO could lap on the electrode surface directly, extending Outer Helmholtz Plane (OHP) of the sensor due to the large surface area and good electronic transport property; secondly, HCR-assisted cascade amplification was designed by anchoring all HCR products on the GO surface, then embedding Ru(phen) 3 2+ as a signal readout pathway. All these signal molecules could take part in electrochemical reactions, thus further enhancing the ECL signal drastically. Therefore, the proposed sensor constructed by integrating HCR with Faraday cage-type strategy displayed an ultrasensitive detection platform for the miRNA-141 with a low detection limit of 0.03 fM. In addition, this proposed biosensor provides a universal platform for analysis of other microRNAs. Copyright © 2018 Elsevier B.V. All rights reserved.

On-chip single photon filtering and multiplexing in hybrid quantum photonic circuits.

Science.gov (United States)

Elshaari, Ali W; Zadeh, Iman Esmaeil; Fognini, Andreas; Reimer, Michael E; Dalacu, Dan; Poole, Philip J; Zwiller, Val; Jöns, Klaus D

2017-08-30

Quantum light plays a pivotal role in modern science and future photonic applications. Since the advent of integrated quantum nanophotonics different material platforms based on III-V nanostructures-, colour centers-, and nonlinear waveguides as on-chip light sources have been investigated. Each platform has unique advantages and limitations; however, all implementations face major challenges with filtering of individual quantum states, scalable integration, deterministic multiplexing of selected quantum emitters, and on-chip excitation suppression. Here we overcome all of these challenges with a hybrid and scalable approach, where single III-V quantum emitters are positioned and deterministically integrated in a complementary metal-oxide-semiconductor-compatible photonic circuit. We demonstrate reconfigurable on-chip single-photon filtering and wavelength division multiplexing with a foot print one million times smaller than similar table-top approaches, while offering excitation suppression of more than 95 dB and efficient routing of single photons over a bandwidth of 40 nm. Our work marks an important step to harvest quantum optical technologies' full potential.Combining different integration platforms on the same chip is currently one of the main challenges for quantum technologies. Here, Elshaari et al. show III-V Quantum Dots embedded in nanowires operating in a CMOS compatible circuit, with controlled on-chip filtering and tunable routing.

Time-area efficient multiplier-free filter architectures for FPGA implementation

DEFF Research Database (Denmark)

Shajaan, Mohammad; Nielsen, Karsten; Sørensen, John Aasted

1995-01-01

Simultaneous design of multiplier-free filters and their hardware implementation in Xilinx field programmable gate array (XC4000) is presented. The filter synthesis method is a new approach based on cascade coupling of low order sections. The complexity of the design algorithm is 𝒪 (filter o...

A nine-level hybrid symmetric cascaded multilevel converter for ...

Indian Academy of Sciences (India)

Indrajit Sarkar

The proposed converter is capable of producing nine output voltage levels by using the ... induction motor drive system in MATLAB/Simulink environment. A laboratory prototype is ..... The power loss distribution among the switches S11, S13,.

Penalty-free transmission at 10 Gbit/s through 40 cascaded 1-nm arrayed waveguide multiplexers

DEFF Research Database (Denmark)

Nissov, Morten; Jørgensen, Bo Foged; Pedersen, Rune Johan Skullerud

1997-01-01

Cascaded optical add-drop multiplexers (OADM) and optical cross connects (OXC) are key components in optical wavelength-division multiplex networks. OADMs with filtering of the passing signals and OXCs can be constructed by the use of wavelength-division multiplexers. Cascadability of multiplexers...

Design of switched-capacitor filter circuits using low gain amplifiers

CERN Document Server

Serra, Hugo Alexandre de Andrade

2015-01-01

This book describes the design of switched-capacitor filter circuits using low gain amplifiers and demonstrates some techniques that can minimize the effects of parasitic capacitances during the design phase. Focus is given in the design of low-pass and band-pass SC filters, and how higher order filters can be achieved using cascaded biquadratic filter sections. The authors also describe a low voltage implementation of a low-pass SC filter.

Optical image encryption using QR code and multilevel fingerprints in gyrator transform domains

Science.gov (United States)

Wei, Yang; Yan, Aimin; Dong, Jiabin; Hu, Zhijuan; Zhang, Jingtao

2017-11-01

A new concept of GT encryption scheme is proposed in this paper. We present a novel optical image encryption method by using quick response (QR) code and multilevel fingerprint keys in gyrator transform (GT) domains. In this method, an original image is firstly transformed into a QR code, which is placed in the input plane of cascaded GTs. Subsequently, the QR code is encrypted into the cipher-text by using multilevel fingerprint keys. The original image can be obtained easily by reading the high-quality retrieved QR code with hand-held devices. The main parameters used as private keys are GTs' rotation angles and multilevel fingerprints. Biometrics and cryptography are integrated with each other to improve data security. Numerical simulations are performed to demonstrate the validity and feasibility of the proposed encryption scheme. In the future, the method of applying QR codes and fingerprints in GT domains possesses much potential for information security.

Hybrid Adaptive Filter development for the minimisation of transient fluctuations superimposed on electrotelluric field recordings mainly by magnetic storms

Directory of Open Access Journals (Sweden)

A. Konstantaras

2006-01-01

Full Text Available The method of Hybrid Adaptive Filtering (HAF aims to recover the recorded electric field signals from anomalies of magnetotelluric origin induced mainly by magnetic storms. An adaptive filter incorporating neuro-fuzzy technology has been developed to remove any significant distortions from the equivalent magnetic field signal, as retrieved from the original electric field signal by reversing the magnetotelluric method. Testing with further unseen data verifies the reliability of the model and demonstrates the effectiveness of the HAF method.

Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

International Nuclear Information System (INIS)

Deng Yang; Liu Yuan; Gao Dingshan

2011-01-01

We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

Multi-objective Design Method for Hybrid Active Power Filter

Science.gov (United States)

Yu, Jingrong; Deng, Limin; Liu, Maoyun; Qiu, Zhifeng

2017-10-01

In this paper, a multi-objective optimal design for transformerless hybrid active power filter (HAPF) is proposed. The interactions between the active and passive circuits is analyzed, and by taking the interactions into consideration, a three-dimensional objective problem comprising of performance, efficiency and cost of HAPF system is formulated. To deal with the multiple constraints and the strong coupling characteristics of the optimization model, a novel constraint processing mechanism based on distance measurement and adaptive penalty function is presented. In order to improve the diversity of optimal solution and the local searching ability of the particle swarm optimization (PSO) algorithm, a chaotic mutation operator based on multistage neighborhood is proposed. The simulation results show that the optimums near the ordinate origin of the three-dimension space make better tradeoff among the performance, efficiency and cost of HAPF, and the experimental results of transformerless HAPF verify the effectiveness of the method for multi-objective optimization and design.

Examining Brain Morphometry Associated with Self-Esteem in Young Adults Using Multilevel-ROI-Features-Based Classification Method

Directory of Open Access Journals (Sweden)

Bo Peng

2017-05-01

Full Text Available Purpose: This study is to exam self-esteem related brain morphometry on brain magnetic resonance (MR images using multilevel-features-based classification method.Method: The multilevel region of interest (ROI features consist of two types of features: (i ROI features, which include gray matter volume, white matter volume, cerebrospinal fluid volume, cortical thickness, and cortical surface area, and (ii similarity features, which are based on similarity calculation of cortical thickness between ROIs. For each feature type, a hybrid feature selection method, comprising of filter-based and wrapper-based algorithms, is used to select the most discriminating features. ROI features and similarity features are integrated by using multi-kernel support vector machines (SVMs with appropriate weighting factor.Results: The classification performance is improved by using multilevel ROI features with an accuracy of 96.66%, a specificity of 96.62%, and a sensitivity of 95.67%. The most discriminating ROI features that are related to self-esteem spread over occipital lobe, frontal lobe, parietal lobe, limbic lobe, temporal lobe, and central region, mainly involving white matter and cortical thickness. The most discriminating similarity features are distributed in both the right and left hemisphere, including frontal lobe, occipital lobe, limbic lobe, parietal lobe, and central region, which conveys information of structural connections between different brain regions.Conclusion: By using ROI features and similarity features to exam self-esteem related brain morphometry, this paper provides a pilot evidence that self-esteem is linked to specific ROIs and structural connections between different brain regions.

L-L multilevel boost converter topology for renewable energy applications

DEFF Research Database (Denmark)

Bhaskar, Mahajan Sagar; Padmanaban, Sanjeevikumar; Fedák, Viliam

2017-01-01

; such as a photovoltaic (PV) system with a Multilevel Inverter (MLI), electrical drives, automotive, hybrid electric cars etc. The proposed topology is derived by attaching the Cockcroft Walton (CW) multiplier to an upper L-converter of the LL topology of XY family. The mode of operation of L-LMBC with mathematical...

Bearing-Only Formation Control for Cascade Multirobots

Directory of Open Access Journals (Sweden)

Qing Han

2016-01-01

Full Text Available A new formation control method is proposed, which is used to queue multirobots in a single-direction cascade structure. In the cascade formation, each robot is a follower for the previous robot and a leader for the next robot, and the robots in the middle act as both leader and follower. The follower robot can only observe the bearing information of the leader robot. The observability of the cascade leader-follower formation is studied, which shows that the bearing-only observation meets the observability conditions required for the nonlinear system. Based on the bearing-only observations, the unscented Kalman filter (UKF is employed for the state estimation of the leader and the follower robots at all levels, which enables the real-time movement control of the follower robots via the input-output feedback control. Simulation results demonstrate that the proposed approach can efficiently control the formation of multirobots as desired.

Implementation of fault tolerant control for modular multilevel converter using EtherCAT communication

DEFF Research Database (Denmark)

Burlacu, Paul Dan; Mathe, Laszlo; Rejas, Marcos

2015-01-01

Modular Multilevel Converter (MMC) is very promising technology this days. It offers fault tolerant capabilities and ensures high efficiency with low output voltage harmonic content which results in need for smaller filter size. A disadvantage of the system is that the control becomes more...

Five Performance Enhancements for Hybrid Hash Join

National Research Council Canada - National Science Library

Graefe, Goetz

1992-01-01

.... We discuss five performance enhancements for hybrid hash join algorithms, namely data compression, large cluster sizes and multi-level recursion, role reversal of build and probe inputs, histogram...

Multi-level restricted maximum likelihood covariance estimation and kriging for large non-gridded spatial datasets

KAUST Repository

Castrillon, Julio

2015-11-10

We develop a multi-level restricted Gaussian maximum likelihood method for estimating the covariance function parameters and computing the best unbiased predictor. Our approach produces a new set of multi-level contrasts where the deterministic parameters of the model are filtered out thus enabling the estimation of the covariance parameters to be decoupled from the deterministic component. Moreover, the multi-level covariance matrix of the contrasts exhibit fast decay that is dependent on the smoothness of the covariance function. Due to the fast decay of the multi-level covariance matrix coefficients only a small set is computed with a level dependent criterion. We demonstrate our approach on problems of up to 512,000 observations with a Matérn covariance function and highly irregular placements of the observations. In addition, these problems are numerically unstable and hard to solve with traditional methods.

A new cascade NN based method to short-term load forecast in deregulated electricity market

International Nuclear Information System (INIS)

Kouhi, Sajjad; Keynia, Farshid

2013-01-01

Highlights: • We are proposed a new hybrid cascaded NN based method and WT to short-term load forecast in deregulated electricity market. • An efficient preprocessor consist of normalization and shuffling of signals is presented. • In order to select the best inputs, a two-stage feature selection is presented. • A new cascaded structure consist of three cascaded NNs is used as forecaster. - Abstract: Short-term load forecasting (STLF) is a major discussion in efficient operation of power systems. The electricity load is a nonlinear signal with time dependent behavior. The area of electricity load forecasting has still essential need for more accurate and stable load forecast algorithm. To improve the accuracy of prediction, a new hybrid forecast strategy based on cascaded neural network is proposed for STLF. This method is consists of wavelet transform, an intelligent two-stage feature selection, and cascaded neural network. The feature selection is used to remove the irrelevant and redundant inputs. The forecast engine is composed of three cascaded neural network (CNN) structure. This cascaded structure can be efficiently extract input/output mapping function of the nonlinear electricity load data. Adjustable parameters of the intelligent feature selection and CNN is fine-tuned by a kind of cross-validation technique. The proposed STLF is tested on PJM and New York electricity markets. It is concluded from the result, the proposed algorithm is a robust forecast method

Hybrid Adaptive Multilevel Monte Carlo Algorithm for Non-Smooth Observables of Itô Stochastic Differential Equations

KAUST Repository

Rached, Nadhir B.

2013-12-01

The Monte Carlo forward Euler method with uniform time stepping is the standard technique to compute an approximation of the expected payoff of a solution of an Itô SDE. For a given accuracy requirement TOL, the complexity of this technique for well behaved problems, that is the amount of computational work to solve the problem, is O(TOL-3). A new hybrid adaptive Monte Carlo forward Euler algorithm for SDEs with non-smooth coefficients and low regular observables is developed in this thesis. This adaptive method is based on the derivation of a new error expansion with computable leading-order terms. The basic idea of the new expansion is the use of a mixture of prior information to determine the weight functions and posterior information to compute the local error. In a number of numerical examples the superior efficiency of the hybrid adaptive algorithm over the standard uniform time stepping technique is verified. When a non-smooth binary payoff with either GBM or drift singularity type of SDEs is considered, the new adaptive method achieves the same complexity as the uniform discretization with smooth problems. Moreover, the new developed algorithm is extended to the MLMC forward Euler setting which reduces the complexity from O(TOL-3) to O(TOL-2(log(TOL))2). For the binary option case with the same type of Itô SDEs, the hybrid adaptive MLMC forward Euler recovers the standard multilevel computational cost O(TOL-2(log(TOL))2). When considering a higher order Milstein scheme, a similar complexity result was obtained by Giles using the uniform time stepping for one dimensional SDEs. The difficulty to extend Giles\\' Milstein MLMC method to the multidimensional case is an argument for the flexibility of our new constructed adaptive MLMC forward Euler method which can be easily adapted to this setting. Similarly, the expected complexity O(TOL-2(log(TOL))2) is reached for the multidimensional case and verified numerically.

Weighted hybrid technique for recommender system

Science.gov (United States)

Suriati, S.; Dwiastuti, Meisyarah; Tulus, T.

2017-12-01

Recommender system becomes very popular and has important role in an information system or webpages nowadays. A recommender system tries to make a prediction of which item a user may like based on his activity on the system. There are some familiar techniques to build a recommender system, such as content-based filtering and collaborative filtering. Content-based filtering does not involve opinions from human to make the prediction, while collaborative filtering does, so collaborative filtering can predict more accurately. However, collaborative filtering cannot give prediction to items which have never been rated by any user. In order to cover the drawbacks of each approach with the advantages of other approach, both approaches can be combined with an approach known as hybrid technique. Hybrid technique used in this work is weighted technique in which the prediction score is combination linear of scores gained by techniques that are combined.The purpose of this work is to show how an approach of weighted hybrid technique combining content-based filtering and item-based collaborative filtering can work in a movie recommender system and to show the performance comparison when both approachare combined and when each approach works alone. There are three experiments done in this work, combining both techniques with different parameters. The result shows that the weighted hybrid technique that is done in this work does not really boost the performance up, but it helps to give prediction score for unrated movies that are impossible to be recommended by only using collaborative filtering.

A phase-equalized digital multirate filter for 50 Hz signal processing

Energy Technology Data Exchange (ETDEWEB)

Vainio, O. [Tampere University of Technology, Signal Processing Laboratory, Tampere (Finland)

1997-12-31

A new multistage digital filter is proposed for 50 Hz line frequency signal processing in zero-crossing detectors and synchronous power systems. The purpose of the filter is to extract the fundamental sinusoidal signal from noise and impulsive disturbances so that the output is accurately in phase with the primary input signal. This is accomplished with a cascade of a median filter, a linear-phase FIR filter, and a phase corrector. A 10 kHz output timing resolution is achieved by up-sampling with a customized interpolation filter. (orig.) 15 refs.

dq-Frame Cascaded Delayed Signal Cancellation-Based PLL

DEFF Research Database (Denmark)

Golestan, Saeed; Ramezani, Malek; Guerrero, Josep M.

2015-01-01

on their position in the PLL structure. Inspired from the concept of delayed signal cancellation (DSC), the idea of cascaded DSC (CDSC) has recently been introduced as an effective solution to improve the performance of the PLL under adverse grid conditions. However, the focus has been on the application of CDSC...... operator as the pre-filtering stage of PLL, and little work has been conducted on its application as the in-loop filtering stage of PLL. This paper provides a detailed analysis and design of dqCDSC-PLL (PLL with in-loop dq-frame CDSC operator). The study is started with an overview of this PLL...

The Influence of Optical Filtering on the Noise Performance of Microwave Photonic Phase Shifters Based on SOAs

DEFF Research Database (Denmark)

Lloret, Juan; Ramos, Francisco; Xue, Weiqi

2011-01-01

Different optical filtering scenarios involving microwave photonic phase shifters based on semiconductor optical amplifiers are investigated numerically as well as experimentally with respect to noise performance. Investigations on the role of the modulation depth and number of elements in cascad...... shifting stages are also carried out. Suppression of the noise level by more than 5 dB has been achieved in schemes based on band-pass optical filtering when three phase shifting stages are cascaded....

ANALYSIS OF THE STRATEGY OF BREEDING OF TOMATO WITH DGENES FOR MULTILEVEL NARROWSHELVE HYDROPONIC SYSTEM

OpenAIRE

I. T. Balashova; S. M. Sirota; E. G. Kozar

2015-01-01

Using the sporophyte selection accelerates in three times the breeding process of new tomato forms with dgenes for the multilevel narrow-shelve hydroponic technology. Analysis two breeding approaches is presented in this paper: the individual selection of recombinant forms from populations and the target hybridization. The target hybridization increases the productivity of the plant and the weight of one fruit in two times.

Multilevel hybrid split-step implicit tau-leap

KAUST Repository

Ben Hammouda, Chiheb

2016-06-17

In biochemically reactive systems with small copy numbers of one or more reactant molecules, the dynamics is dominated by stochastic effects. To approximate those systems, discrete state-space and stochastic simulation approaches have been shown to be more relevant than continuous state-space and deterministic ones. In systems characterized by having simultaneously fast and slow timescales, existing discrete space-state stochastic path simulation methods, such as the stochastic simulation algorithm (SSA) and the explicit tau-leap (explicit-TL) method, can be very slow. Implicit approximations have been developed to improve numerical stability and provide efficient simulation algorithms for those systems. Here, we propose an efficient Multilevel Monte Carlo (MLMC) method in the spirit of the work by Anderson and Higham (SIAM Multiscal Model. Simul. 10(1), 2012). This method uses split-step implicit tau-leap (SSI-TL) at levels where the explicit-TL method is not applicable due to numerical stability issues. We present numerical examples that illustrate the performance of the proposed method. © 2016 Springer Science+Business Media New York

Tunable First-Order Resistorless All-Pass Filter with Low Output Impedance

Directory of Open Access Journals (Sweden)

Parveen Beg

2014-01-01

Full Text Available This paper presents a voltage mode cascadable single active element tunable first-order all-pass filter with a single passive component. The active element used to realise the filter is a new building block termed as differential difference dual-X current conveyor with a buffered output (DD-DXCCII. The filter is thus realized with the help of a DD-DXCCII, a capacitor, and a MOS transistor. By exploiting the low output impedance, a higher order filter is also realized. Nonideal and parasitic study is also carried out on the realised filters. The proposed DD-DXCCII filters are simulated using TSMC the 0.25 µm technology.

Tunable first-order resistorless all-pass filter with low output impedance.

Science.gov (United States)

Beg, Parveen

2014-01-01

This paper presents a voltage mode cascadable single active element tunable first-order all-pass filter with a single passive component. The active element used to realise the filter is a new building block termed as differential difference dual-X current conveyor with a buffered output (DD-DXCCII). The filter is thus realized with the help of a DD-DXCCII, a capacitor, and a MOS transistor. By exploiting the low output impedance, a higher order filter is also realized. Nonideal and parasitic study is also carried out on the realised filters. The proposed DD-DXCCII filters are simulated using TSMC the 0.25 µm technology.

A cascade of classifiers for extracting medication information from discharge summaries

Directory of Open Access Journals (Sweden)

Halgrim Scott

2011-07-01

Full Text Available Abstract Background Extracting medication information from clinical records has many potential applications, and recently published research, systems, and competitions reflect an interest therein. Much of the early extraction work involved rules and lexicons, but more recently machine learning has been applied to the task. Methods We present a hybrid system consisting of two parts. The first part, field detection, uses a cascade of statistical classifiers to identify medication-related named entities. The second part uses simple heuristics to link those entities into medication events. Results The system achieved performance that is comparable to other approaches to the same task. This performance is further improved by adding features that reference external medication name lists. Conclusions This study demonstrates that our hybrid approach outperforms purely statistical or rule-based systems. The study also shows that a cascade of classifiers works better than a single classifier in extracting medication information. The system is available as is upon request from the first author.

The analysis and application of a new hybrid pollutants forecasting model using modified Kolmogorov-Zurbenko filter.

Science.gov (United States)

Li, Peizhi; Wang, Yong; Dong, Qingli

2017-04-01

Cities in China suffer from severe smog and haze, and a forecasting system with high accuracy is of great importance to foresee the concentrations of the airborne particles. Compared with chemical transport models, the growing artificial intelligence models can simulate nonlinearities and interactive relationships and getting more accurate results. In this paper, the Kolmogorov-Zurbenko (KZ) filter is modified and firstly applied to construct the model using an artificial intelligence method. The concentration of inhalable particles and fine particulate matter in Dalian are used to analyze the filtered components and test the forecasting accuracy. Besides, an extended experiment is made by implementing a comprehensive comparison and a stability test using data in three other cities in China. Results testify the excellent performance of the developed hybrid models, which can be utilized to better understand the temporal features of pollutants and to perform a better air pollution control and management. Copyright © 2017 Elsevier B.V. All rights reserved.

Combining the multilevel fast multipole method with the uniform geometrical theory of diffraction

Directory of Open Access Journals (Sweden)

A. Tzoulis

2005-01-01

Full Text Available The presence of arbitrarily shaped and electrically large objects in the same environment leads to hybridization of the Method of Moments (MoM with the Uniform Geometrical Theory of Diffraction (UTD. The computation and memory complexity of the MoM solution is improved with the Multilevel Fast Multipole Method (MLFMM. By expanding the k-space integrals in spherical harmonics, further considerable amount of memory can be saved without compromising accuracy and numerical speed. However, until now MoM-UTD hybrid methods are restricted to conventional MoM formulations only with Electric Field Integral Equation (EFIE. In this contribution, a MLFMM-UTD hybridization for Combined Field Integral Equation (CFIE is proposed and applied within a hybrid Finite Element - Boundary Integral (FEBI technique. The MLFMM-UTD hybridization is performed at the translation procedure on the various levels of the MLFMM, using a far-field approximation of the corresponding translation operator. The formulation of this new hybrid technique is presented, as well as numerical results.

Hybrid unscented particle filter based state-of-charge determination for lead-acid batteries

International Nuclear Information System (INIS)

Shen, Yanqing

2014-01-01

Accurate prediction of cell SOC (state of charge) is important for the safety and functional capabilities of the battery energy storage application system. This paper presents a hybrid UPF (unscented particle filter) based SOC determination combined model for batteries. To simulate the entire dynamic electrical characteristics of batteries, a novel combined state space model, which takes current as a control input and let SOC and two constructed parameters as state variables, is advanced to represent cell behavior. Besides that, an improved UPF method is used to evaluate cell SOC. Taking lead-acid batteries for example, we apply the established model for test. Results show that the evolved combined state space cell model simulates battery dynamics robustly with high accuracy and the prediction value based on the improved UPF method converges to the real SOC very quickly within the error of±2%. - Highlights: • This paper introduces a hybrid UPF based SOC determination model for batteries. • The evolved model takes SOC and two constructed parameters as state variables. • The combined state space cell model simulates battery dynamics robustly. • NLMS based method is employed to lessen search space and fasten convergence process. • Novel model converges to the real SOC robustly and quickly with fewer particles

Hybrid PV/wind system with quinary asymmetric inverter without increasing DC-link number

Directory of Open Access Journals (Sweden)

Aida Baghbany Oskouei

2016-06-01

Full Text Available This paper suggests quinary asymmetric inverter with coupled inductors and transformer, and uses it in hybrid system including photovoltaic (PV and wind. This inverter produces twenty-five-level voltage in addition to merits of multilevel inverter, has only one DC source. Then, it is adequate for hybrid systems, which prevents increasing DC-link and makes control of system easy. Proposed structure also provides isolation in the system and the switch numbers are reduced in this topology compared with other multilevel structures. In this system, battery is used as backup, where PV and wind have complementary nature. The performance of proposed inverter and hybrid system is validated with simulation results using MATLAB/SIMULINK software and experimental results based PCI-1716 data acquisition system.

Multi-level programming paradigm for extreme computing

International Nuclear Information System (INIS)

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

2013-01-01

In order to propose a framework and programming paradigms for post peta-scale computing, on the road to exa-scale 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. (authors)

Plasma simulation studies using multilevel physics models

International Nuclear Information System (INIS)

Park, W.; Belova, E.V.; Fu, G.Y.

2000-01-01

The question of how to proceed toward ever more realistic plasma simulation studies using ever increasing computing power is addressed. The answer presented here is the M3D (Multilevel 3D) project, which has developed a code package with a hierarchy of physics levels that resolve increasingly complete subsets of phase-spaces and are thus increasingly more realistic. The rationale for the multilevel physics models is given. Each physics level is described and examples of its application are given. The existing physics levels are fluid models (3D configuration space), namely magnetohydrodynamic (MHD) and two-fluids; and hybrid models, namely gyrokinetic-energetic-particle/MHD (5D energetic particle phase-space), gyrokinetic-particle-ion/fluid-electron (5D ion phase-space), and full-kinetic-particle-ion/fluid-electron level (6D ion phase-space). Resolving electron phase-space (5D or 6D) remains a future project. Phase-space-fluid models are not used in favor of delta f particle models. A practical and accurate nonlinear fluid closure for noncollisional plasmas seems not likely in the near future

Simultaneous Estimation of Model State Variables and Observation and Forecast Biases Using a Two-Stage Hybrid Kalman Filter

Science.gov (United States)

Pauwels, V. R. N.; DeLannoy, G. J. M.; Hendricks Franssen, H.-J.; Vereecken, H.

2013-01-01

In this paper, we present a two-stage hybrid Kalman filter to estimate both observation and forecast bias in hydrologic models, in addition to state variables. The biases are estimated using the discrete Kalman filter, and the state variables using the ensemble Kalman filter. A key issue in this multi-component assimilation scheme is the exact partitioning of the difference between observation and forecasts into state, forecast bias and observation bias updates. Here, the error covariances of the forecast bias and the unbiased states are calculated as constant fractions of the biased state error covariance, and the observation bias error covariance is a function of the observation prediction error covariance. In a series of synthetic experiments, focusing on the assimilation of discharge into a rainfall-runoff model, it is shown that both static and dynamic observation and forecast biases can be successfully estimated. The results indicate a strong improvement in the estimation of the state variables and resulting discharge as opposed to the use of a bias-unaware ensemble Kalman filter. Furthermore, minimal code modification in existing data assimilation software is needed to implement the method. The results suggest that a better performance of data assimilation methods should be possible if both forecast and observation biases are taken into account.

Simultaneous estimation of model state variables and observation and forecast biases using a two-stage hybrid Kalman filter

Directory of Open Access Journals (Sweden)

V. R. N. Pauwels

2013-09-01

Full Text Available In this paper, we present a two-stage hybrid Kalman filter to estimate both observation and forecast bias in hydrologic models, in addition to state variables. The biases are estimated using the discrete Kalman filter, and the state variables using the ensemble Kalman filter. A key issue in this multi-component assimilation scheme is the exact partitioning of the difference between observation and forecasts into state, forecast bias and observation bias updates. Here, the error covariances of the forecast bias and the unbiased states are calculated as constant fractions of the biased state error covariance, and the observation bias error covariance is a function of the observation prediction error covariance. In a series of synthetic experiments, focusing on the assimilation of discharge into a rainfall-runoff model, it is shown that both static and dynamic observation and forecast biases can be successfully estimated. The results indicate a strong improvement in the estimation of the state variables and resulting discharge as opposed to the use of a bias-unaware ensemble Kalman filter. Furthermore, minimal code modification in existing data assimilation software is needed to implement the method. The results suggest that a better performance of data assimilation methods should be possible if both forecast and observation biases are taken into account.

A hybrid robust fault tolerant control based on adaptive joint unscented Kalman filter.

Science.gov (United States)

Shabbouei Hagh, Yashar; Mohammadi Asl, Reza; Cocquempot, Vincent

2017-01-01

In this paper, a new hybrid robust fault tolerant control scheme is proposed. A robust H ∞ control law is used in non-faulty situation, while a Non-Singular Terminal Sliding Mode (NTSM) controller is activated as soon as an actuator fault is detected. Since a linear robust controller is designed, the system is first linearized through the feedback linearization method. To switch from one controller to the other, a fuzzy based switching system is used. An Adaptive Joint Unscented Kalman Filter (AJUKF) is used for fault detection and diagnosis. The proposed method is based on the simultaneous estimation of the system states and parameters. In order to show the efficiency of the proposed scheme, a simulated 3-DOF robotic manipulator is used. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

DEFF Research Database (Denmark)

Bache, Morten; Bang, Ole; Zhou, Binbin

2010-01-01

-matching point is located in the absorption region of the crystal, effectively absorbing the generated dispersive wave. By calculating the phase-matching curves for typically used frequency conversion crystals, we point out that the mid-IR absorption in the crystal in many cases automatically will filter away....... The beating between the dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering around the dispersive wave peak results in near......We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum...

Magnetic field sensor based on cascaded microfiber coupler with magnetic fluid

Energy Technology Data Exchange (ETDEWEB)

Mao, Lianmin; Su, Delong; Wang, Zhaofang [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Pu, Shengli, E-mail: shlpu@usst.edu.cn [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zeng, Xianglong [The Key Lab of Specialty Fiber Optics and Optical Access Network, Shanghai University, Shanghai 200072 (China); Lahoubi, Mahieddine [Laboratory L.P.S., Department of Physics, Faculty of Sciences, Badji-Mokhtar Annaba University, Annaba 23000 (Algeria)

2016-09-07

A kind of magnetic field sensor based on cascaded microfiber coupler with magnetic fluid is proposed and experimentally demonstrated. The magnetic fluid is utilized as the cladding of the fused regions of the cascaded microfiber coupler. As the interference valley wavelength of the sensing structure is sensitive to the ambient variation, considering the magnetic-field-dependent refractive index of magnetic fluid, the proposed structure is employed for magnetic field sensing. The effective coupling length for each coupling region of the as-fabricated cascaded microfiber coupler is 6031 μm. The achieved sensitivity is 125 pm/Oe, which is about three times larger than that of the previously similar structure based on the single microfiber coupler. Experimental results indicate that the sensing sensitivity can be easily improved by increasing the effective coupling length or cascading more microfiber couplers. The proposed magnetic field sensor is attractive due to its low cost, immunity to electromagnetic interference, as well as high sensitivity, which also has the potentials in other tunable all-fiber photonic devices, such as filter.

Attenuation of spurious responses in electromechanical filters

Energy Technology Data Exchange (ETDEWEB)

Olsson, Roy H.; Hietala, Vincent M.

2018-04-10

A spur cancelling, electromechanical filter includes a first resonator having a first resonant frequency and one or more first spurious responses, and it also includes, electrically connected to the first resonator, a second resonator having a second resonant frequency and one or more second spurious responses. The first and second resonant frequencies are approximately identical, but the first resonator is physically non-identical to the second resonator. The difference between the resonators makes the respective spurious responses different. This allows for filters constructed from a cascade of these resonators to exhibit reduced spurious responses.

Climate technology transfer at the local, national and global levels: analyzing the relationships between multi-level structures

NARCIS (Netherlands)

Tessema Abissa, Fisseha; Tessema Abissa, Fisseha

2014-01-01

This thesis examines the relationships between multi-leveled decision structures for climate technology transfer through an analysis of top-down macro-policy and bottom-up micro-implementation. It examines how international climate technology transfer policy under the UNFCCC filters down to the

Selective Harmonic Elimination in Asymmetric Cascaded Multilevel Inverters Using a New Low-frequency Strategy for Photovoltaic Applications

DEFF Research Database (Denmark)

Dowlatabadi, Mohammadkazem Bakhshizadeh; Iman-Eini, Hossein; Blaabjerg, Frede

2015-01-01

Asymmetric multilevel inverters with a main and auxiliary power circuit can yield maximum number of voltage levels against the number of semiconductor devices. Most of the output power will be produced by the main inverter, which works at low frequency and the auxiliary inverters only improve the...

A New Modular Multilevel Converter with Integrated Energy Storage

DEFF Research Database (Denmark)

Trintis, Ionut; Munk-Nielsen, Stig; Teodorescu, Remus

2011-01-01

applications. Furthermore, this solution can interconnect a DC and AC grid with bidirectional power flow, where both of them can receive or generate excess power to the third source integrated in each converter sub-module. This particularity enables the converter usage as a high voltage UPS system......This paper introduces a new modular converter with integrated energy storage based on the cascaded half-bridge modular multilevel converter with common DC bus. It represents a complete modular solution with power electronics and energy storage building blocks, for medium and high voltage...... in the future HVDC meshed grids. Its functionality and flexibility makes the converter independent on the energy storage unit characteristic. The converter concept with its basic functions and control schemes are described and evaluated in this paper....

Treatment of breast cancer with simultaneous integrated boost in hybrid plan technique. Influence of flattening filter-free beams

Energy Technology Data Exchange (ETDEWEB)

Bahrainy, Marzieh; Kretschmer, Matthias; Joest, Vincent; Kasch, Astrid; Wuerschmidt, Florian; Dahle, Joerg; Lorenzen, Joern [Radiologische Allianz, Hamburg (Germany)

2016-05-15

The present study compares in silico treatment plans using hybrid plan technique during hypofractionated radiation of mammary carcinoma with simultaneous integrated boost (SIB). The influence of 6 MV photon radiation in flattening filter free (FFF) mode against the clinical standard flattening filter (FF) mode is to be examined. RT planning took place with FF and FFF radiation plans for 10 left-sided breast cancer patients. Hybrid plans were realised with two tangential IMRT fields and one VMAT field. The dose prescription was in line with the guidelines in the ARO-2010-01 study. The dosimetric verification took place with a manufacturer-independent measurement system. Required dose prescriptions for the planning target volumes (PTV) were achieved for both groups. The average dose values of the ipsi- and contralateral lung and the heart did not differ significantly. The overall average incidental dose to the left anterior descending artery (LAD) of 8.24 ± 3.9 Gy in the FFF group and 9.05 ± 3.7 Gy in the FF group (p < 0.05) were found. The dosimetric verifications corresponded to the clinical requirements. FFF-based RT plans reduced the average treatment time by 17 s/fraction. In comparison to the FF-based hybrid plan technique the FFF mode allows further reduction of the average LAD dose for comparable target volume coverage without adverse low-dose exposure of contralateral structures. The combination of hybrid plan technique and 6 MV photon radiation in the FFF mode is suitable for use with hypofractionated dose schemes. The increased dose rate allows a substantial reduction of treatment time and thus beneficial application of the deep inspiration breath hold technique. (orig.) [German] Vergleich der ''In-silico''-Bestrahlungsplaene der klinisch etablierten Hybridplan-Technik bei hypofraktionierter Bestrahlung des Mammakarzinoms mit simultan integriertem Boost (SIB). Untersucht wird der Einfluss von 6MV-Photonenstrahlung im Flattening-Filter

Automatic Classification Using Supervised Learning in a Medical Document Filtering Application.

Science.gov (United States)

Mostafa, J.; Lam, W.

2000-01-01

Presents a multilevel model of the information filtering process that permits document classification. Evaluates a document classification approach based on a supervised learning algorithm, measures the accuracy of the algorithm in a neural network that was trained to classify medical documents on cell biology, and discusses filtering…

Modeling, simulation, and design of SAW grating filters

Science.gov (United States)

Schwelb, Otto; Adler, E. L.; Slaboszewicz, J. K.

1990-05-01

A systematic procedure for modeling, simulating, and designing SAW (surface acoustic wave) grating filters, taking losses into account, is described. Grating structures and IDTs (interdigital transducers) coupling to SAWs are defined by cascadable transmission-matrix building blocks. Driving point and transfer characteristics (immittances) of complex architectures consisting of gratings, transducers, and coupling networks are obtained by chain-multiplying building-block matrices. This modular approach to resonator filter analysis and design combines the elements of lossy filter synthesis with the transmission-matrix description of SAW components. A multipole filter design procedure based on a lumped-element-model approximation of one-pole two-port resonator building blocks is given and the range of validity of this model examined. The software for simulating the performance of SAW grating devices based on this matrix approach is described, and its performance, when linked to the design procedure to form a CAD/CAA (computer-aided design and analysis) multiple-filter design package, is illustrated with a resonator filter design example.

Multilevel modeling using R

CERN Document Server

Finch, W Holmes; Kelley, Ken

2014-01-01

A powerful tool for analyzing nested designs in a variety of fields, multilevel/hierarchical modeling allows researchers to account for data collected at multiple levels. Multilevel Modeling Using R provides you with a helpful guide to conducting multilevel data modeling using the R software environment.After reviewing standard linear models, the authors present the basics of multilevel models and explain how to fit these models using R. They then show how to employ multilevel modeling with longitudinal data and demonstrate the valuable graphical options in R. The book also describes models fo

Cascaded Subpatch Networks for Effective CNNs.

Science.gov (United States)

Jiang, Xiaoheng; Pang, Yanwei; Sun, Manli; Li, Xuelong

2017-05-12

Conventional convolutional neural networks use either a linear or a nonlinear filter to extract features from an image patch (region) of spatial size Hx W (typically, H is small and is equal to W, e.g., H is 5 or 7 ). Generally, the size of the filter is equal to the size Hx W of the input patch. We argue that the representational ability of equal-size strategy is not strong enough. To overcome the drawback, we propose to use subpatch filter whose spatial size hx w is smaller than Hx W . The proposed subpatch filter consists of two subsequent filters. The first one is a linear filter of spatial size hx w and is aimed at extracting features from spatial domain. The second one is of spatial size 1x 1 and is used for strengthening the connection between different input feature channels and for reducing the number of parameters. The subpatch filter convolves with the input patch and the resulting network is called a subpatch network. Taking the output of one subpatch network as input, we further repeat constructing subpatch networks until the output contains only one neuron in spatial domain. These subpatch networks form a new network called the cascaded subpatch network (CSNet). The feature layer generated by CSNet is called the csconv layer. For the whole input image, we construct a deep neural network by stacking a sequence of csconv layers. Experimental results on five benchmark data sets demonstrate the effectiveness and compactness of the proposed CSNet. For example, our CSNet reaches a test error of 5.68% on the CIFAR10 data set without model averaging. To the best of our knowledge, this is the best result ever obtained on the CIFAR10 data set.

Hybrid context aware recommender systems

Science.gov (United States)

Jain, Rajshree; Tyagi, Jaya; Singh, Sandeep Kumar; Alam, Taj

2017-10-01

Recommender systems and context awareness is currently a vital field of research. Most hybrid recommendation systems implement content based and collaborative filtering techniques whereas this work combines context and collaborative filtering. The paper presents a hybrid context aware recommender system for books and movies that gives recommendations based on the user context as well as user or item similarity. It also addresses the issue of dimensionality reduction using weighted pre filtering based on dynamically entered user context and preference of context. This unique step helps to reduce the size of dataset for collaborative filtering. Bias subtracted collaborative filtering is used so as to consider the relative rating of a particular user and not the absolute values. Cosine similarity is used as a metric to determine the similarity between users or items. The unknown ratings are calculated and evaluated using MSE (Mean Squared Error) in test and train datasets. The overall process of recommendation has helped to personalize recommendations and give more accurate results with reduced complexity in collaborative filtering.

Study of multilevel inverters with extended functions; Estudio de inversores multinivel con funciones ampliadas

Energy Technology Data Exchange (ETDEWEB)

Miranda Vidales, Homero

2007-06-15

compensation of harmonics, regulation, etc.; therefore it is necessary to realize a study that allows extending the functions of the active filter in such a way that it is equipment able to realize other type of functions. In this work it is studied a multilevel converter with cells in cascade for extended functions, where the main function is in the power stage of the active filter of current. In addition, two possibilities are studied that allow extend their operation as a STATCOM and a filter with regenerative capacity. The study implies to propose one or several control schemes for each one of the functions, either in an independent way or altogether. Chapter II presents an analysis of the asymmetric hybrid topology with relation 3:1 in the DC sources. This converter is used in the power stage of the active filter. Also a scheme is proposed to obtain the reference current. In this chapter the design of two control schemes is approached which are based on the theory of the linear and non-lineal control. In Chapter III the extended functions of the multilevel converter are studied. First a study is presented on the function as STATCOM. For this function a control scheme is proposed which allows simultaneously realizing the function of active filter and STATCOM. In the second part the multilevel inverter with regeneration capacity is studied. In this part of the chapter a modification of the structure is realized that helps to perform this function. Chapter IV contains the discussions and conclusions of the results obtained in the thesis. In the last part of the chapter some future lines of investigation are commented and finally the articles derived from this thesis are shown. Six appendixes are also included that complement the work of the thesis. These appendixes contain a series of studies on the topologies of the multilateral inverters, modulation techniques, the stationary frame of reference, design of the inverter, criterion for the selection of components and

IMPLEMENTATION AND COMPARISON OF DIFFERENT CIC FILTER STRUCTURE FOR DECIMATION

Directory of Open Access Journals (Sweden)

M. Madheswaran

2013-06-01

Full Text Available This paper briefs an implementation of different CIC filter architectures for decimation. The different decimation filter structures are implemented using cascaded integrator-comb filter to work for the down sampling ratio of 8. The prototype is designed with MATLAB Simulink model and it is converted to VHDL code using Xilinx system generator. Prototype is implemented in Virtex V- XC5VLX110T-3ff1136 FPGA kit and simulation results and device utilization reports are generated and tabulated. Finally different architectures are compared using number of used LUTs, Registers, Power consumption etc.

Adaptive filters and internal models: multilevel description of cerebellar function.

Science.gov (United States)

Porrill, John; Dean, Paul; Anderson, Sean R

2013-11-01

Cerebellar function is increasingly discussed in terms of engineering schemes for motor control and signal processing that involve internal models. To address the relation between the cerebellum and internal models, we adopt the chip metaphor that has been used to represent the combination of a homogeneous cerebellar cortical microcircuit with individual microzones having unique external connections. This metaphor indicates that identifying the function of a particular cerebellar chip requires knowledge of both the general microcircuit algorithm and the chip's individual connections. Here we use a popular candidate algorithm as embodied in the adaptive filter, which learns to decorrelate its inputs from a reference ('teaching', 'error') signal. This algorithm is computationally powerful enough to be used in a very wide variety of engineering applications. However, the crucial issue is whether the external connectivity required by such applications can be implemented biologically. We argue that some applications appear to be in principle biologically implausible: these include the Smith predictor and Kalman filter (for state estimation), and the feedback-error-learning scheme for adaptive inverse control. However, even for plausible schemes, such as forward models for noise cancellation and novelty-detection, and the recurrent architecture for adaptive inverse control, there is unlikely to be a simple mapping between microzone function and internal model structure. This initial analysis suggests that cerebellar involvement in particular behaviours is therefore unlikely to have a neat classification into categories such as 'forward model'. It is more likely that cerebellar microzones learn a task-specific adaptive-filter operation which combines a number of signal-processing roles. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multi-timescale power and energy assessment of lithium-ion battery and supercapacitor hybrid system using extended Kalman filter

Science.gov (United States)

Wang, Yujie; Zhang, Xu; Liu, Chang; Pan, Rui; Chen, Zonghai

2018-06-01

The power capability and maximum charge and discharge energy are key indicators for energy management systems, which can help the energy storage devices work in a suitable area and prevent them from over-charging and over-discharging. In this work, a model based power and energy assessment approach is proposed for the lithium-ion battery and supercapacitor hybrid system. The model framework of the lithium-ion battery and supercapacitor hybrid system is developed based on the equivalent circuit model, and the model parameters are identified by regression method. Explicit analyses of the power capability and maximum charge and discharge energy prediction with multiple constraints are elaborated. Subsequently, the extended Kalman filter is employed for on-board power capability and maximum charge and discharge energy prediction to overcome estimation error caused by system disturbance and sensor noise. The charge and discharge power capability, and the maximum charge and discharge energy are quantitatively assessed under both the dynamic stress test and the urban dynamometer driving schedule. The maximum charge and discharge energy prediction of the lithium-ion battery and supercapacitor hybrid system with different time scales are explored and discussed.

Plasma simulation studies using multilevel physics models

International Nuclear Information System (INIS)

Park, W.; Belova, E.V.; Fu, G.Y.; Tang, X.Z.; Strauss, H.R.; Sugiyama, L.E.

1999-01-01

The question of how to proceed toward ever more realistic plasma simulation studies using ever increasing computing power is addressed. The answer presented here is the M3D (Multilevel 3D) project, which has developed a code package with a hierarchy of physics levels that resolve increasingly complete subsets of phase-spaces and are thus increasingly more realistic. The rationale for the multilevel physics models is given. Each physics level is described and examples of its application are given. The existing physics levels are fluid models (3D configuration space), namely magnetohydrodynamic (MHD) and two-fluids; and hybrid models, namely gyrokinetic-energetic-particle/MHD (5D energetic particle phase-space), gyrokinetic-particle-ion/fluid-electron (5D ion phase-space), and full-kinetic-particle-ion/fluid-electron level (6D ion phase-space). Resolving electron phase-space (5D or 6D) remains a future project. Phase-space-fluid models are not used in favor of δf particle models. A practical and accurate nonlinear fluid closure for noncollisional plasmas seems not likely in the near future. copyright 1999 American Institute of Physics

Dispersion induced penalty for a 1xN passive interferometric optical MUX/DEMUX and its reduction using all-pass filters

DEFF Research Database (Denmark)

Leick, Lasse; Peucheret, Christophe

2002-01-01

The cascadability of 1timesN passband flattened interferometer DEMUX is investigated numerically. The passband flattening process results in detrimental dispersion induced penalty at 10 Gbit/s which can be significantly reduced with all-pass filters on the input arm......The cascadability of 1timesN passband flattened interferometer DEMUX is investigated numerically. The passband flattening process results in detrimental dispersion induced penalty at 10 Gbit/s which can be significantly reduced with all-pass filters on the input arm...

Filter paper inhibits in vitro protocorm-like body formation in hybrid Cymbidium and reduces synseed germination, but buffers the negative impact of antibiotics

Directory of Open Access Journals (Sweden)

TEIXEIRA DA SILVA JAIME A.

2014-06-01

Full Text Available Only few studies in the plant tissue culture literature have examined the impact of filter paper on in vitro plant organogenesis. In this study, using a model plant, hybrid Cymbidium Twilight Moon ‘Day Light’, the impact of a single or double layer of Advantec #2 or Whatman #1 filter paper on new protocorm-like body (neo-PLB formation on Teixeira Cymbidium (TC medium was examined for half-PLBs (transgenic and non-transgenic, PLB-derived transverse thin cell layers (tTCLs, and PLB synseeds. In addition, the response of half-PLBs or tTCLs to two antibiotics (kanamycin and cefotaxime, commonly used in plant genetic transformation studies was investigated either directly on gelled medium or on filter paper-overlaid medium. Filter paper negatively affected most growth and developmental parameters of all the explants tested, both transgenic and non-transgenic. A double sheet of filter paper had a significantly (P ≤ 0.05 more negative impact than a single sheet, relative to the control values (i.e., no filter paper. Kanamycin inhibited neo-PLB formation on TC medium, the negative impact being greater on a single layer than on a double layer of filter paper, i.e., filter paper buffered the growth-inhibiting characteristics of kanamycin. Up to 100 mg/l, cefotaxime showed no apparent negative effects on neo-PLBs formation and growth, although hyperhydricity was observed when filter paper was not used.

Filtering in hybrid dynamic Bayesian networks

DEFF Research Database (Denmark)

Andersen, Morten Nonboe; Andersen, Rasmus Ørum; Wheeler, Kevin

2004-01-01

for inference. We extend the experiment and perform approximate inference using The Extended Kalman Filter (EKF) and the Unscented Kalman Filter (UKF). Furthermore, we combine these techniques in a 'non-strict' Rao-Blackwellisation framework and apply it to the watertank system. We show that UKF and UKF in a PF...... framework outperform the generic PF, EKF and EKF in a PF framework with respect to accuracy and robustness in terms of estimation RMSE (root-mean-square error). Especially we demonstrate the superiority of UKF in a PF framework when our beliefs of how data was generated are wrong. We also show...... that the choice of network structure is very important for the performance of the generic PF and the EKF algorithms, but not for the UKF algorithms. Furthermore, we investigate the influence of data noise in the watertank simulation. Theory and implementation is based on the theory presented in (v.d. Merwe et al...

Short-term hydro generation scheduling of Three Gorges–Gezhouba cascaded hydropower plants using hybrid MACS-ADE approach

International Nuclear Information System (INIS)

Mo, Li; Lu, Peng; Wang, Chao; Zhou, Jianzhong

2013-01-01

Highlights: • MACS and ADE algorithms are hybridized as MACS-ADE method for solving STHGS problem. • An adaptive mutation is integrated into the proposed algorithm to avoid premature convergence. • MACS and ADE are run in parallel in search of better solution. • Several effective heuristic strategies are designed for dealing with various constraints of STHGS problem. - Abstract: Short-term hydro generation scheduling (STHGS) aims at determining optimal hydro generation scheduling to obtain minimum water consumption for one day or week while meeting various system constraints. In this paper, the STHGS problem is decomposed into two sub-problems: (i) unit commitment (UC) sub-problem; (ii) economic load dispatch (ELD) sub-problem. Then, we present a hybrid algorithm based on multi ant colony system (MACS) and differential evolution (DE) for solving the STHGS problem. First, MACS is used for dealing with UC sub-problem. A set of cooperating ant colonies cooperate to choose the unit state over the scheduled time horizon. Then, the adaptive differential evolution (ADE) is used to solve ELD sub-problem. MACS and ADE are run in parallel with adjusting their solutions in search of a better solution. Meanwhile, local and global pheromone updating rules in MACS and adaptive dynamic parameter adjusting strategy in DE are applied for enhancing the search ability of MACS-ADE. Finally, the proposed method is implemented to solve STHGS problem of Three Gorges–Gezhouba cascaded hydropower plants to verify the feasibility and effectiveness. Compared with other established methods, the simulation results reveal that the proposed MACS-ADE approach has the best convergence property, computational efficiency with less water consumption

PULSE MODULATION POWER AMPLIFIER WITH ENHANCED CASCADE CONTROL METHOD

DEFF Research Database (Denmark)

1998-01-01

a single local feedback path A (7) with a lowpass characteristic and local forward blocks B¿1? or B (3, 4). The leads to a much improved system with a very low sensitivity to errors in the switching power stage. In the second preferred embodiment of the invention the control structure is extended...... and feedback path A to determine stable self-oscillating conditions. An implemented 250W example MECC digital power amplifier has proven superior performance in terms of audio performance (0.005 % distortion, 115 dB dynamic range) and efficiency (92 %).......A digital switching power amplifier with Multivariable Enhanced Cascade Controlled (MECC) includes a modulator, a switching power stage and a low pass filter. In the first preferred embodiment an enhanced cascade control structure local to the switching power stage is added, characterised by having...

Current Harmonics Cancellation in Three-Phase Four-Wire Systems by Using a Four-Branch Star Filtering Topology

DEFF Research Database (Denmark)

Rodriguez, Pedro; Candela, J. I.; Luna, A.

2009-01-01

This paper presents a new solution for filtering current harmonics in three-phase four-wire networks. The original four-branch star (FBS) filter topology presented in this paper is characterized by a particular layout of single-phase inductances and capacitors, without using any transformer......, a specific implementation of a three-phase four-wire hybrid power filter is presented as an illustrative application of the filtering topology. An extensive evaluation using simulation and experimental results from a DSP-based laboratory prototype is conducted in order to verify and validate the good...... only passive components are employed, or as a hybrid filter, when its behavior is improved by integrating a power converter into the filter structure. The paper analyzes the proposed topology, and derives fundamental concepts about the control of the resulting hybrid power filter. From this analysis...

EUROPEAN INTEGRATION: A MULTILEVEL PROCESS THAT REQUIRES A MULTILEVEL STATISTICAL ANALYSIS

Directory of Open Access Journals (Sweden)

Roxana-Otilia-Sonia HRITCU

2015-11-01

Full Text Available A process of market regulation and a system of multi-level governance and several supranational, national and subnational levels of decision making, European integration subscribes to being a multilevel phenomenon. The individual characteristics of citizens, as well as the environment where the integration process takes place, are important. To understand the European integration and its consequences it is important to develop and test multi-level theories that consider individual-level characteristics, as well as the overall context where individuals act and express their characteristics. A central argument of this paper is that support for European integration is influenced by factors operating at different levels. We review and present theories and related research on the use of multilevel analysis in the European area. This paper draws insights on various aspects and consequences of the European integration to take stock of what we know about how and why to use multilevel modeling.

Learning High-Order Filters for Efficient Blind Deconvolution of Document Photographs

KAUST Repository

Xiao, Lei; Wang, Jue; Heidrich, Wolfgang; Hirsch, Michael

2016-01-01

by small-scale high-order structures, we propose to learn a multi-scale, interleaved cascade of shrinkage fields model, which contains a series of high-order filters to facilitate joint recovery of blur kernel and latent image. With extensive experiments

Lifted linear phase filter banks and the polyphase-with-advance representation

Energy Technology Data Exchange (ETDEWEB)

Brislawn, C. M. (Christopher M.); Wohlberg, B. E. (Brendt E.)

2004-01-01

A matrix theory is developed for the noncausal polyphase-with-advance representation that underlies the theory of lifted perfect reconstruction filter banks and wavelet transforms as developed by Sweldens and Daubechies. This theory provides the fundamental lifting methodology employed in the ISO/IEC JPEG-2000 still image coding standard, which the authors helped to develop. Lifting structures for polyphase-with-advance filter banks are depicted in Figure 1. In the analysis bank of Figure 1(a), the first lifting step updates x{sub 0} with a filtered version of x{sub 1} and the second step updates x{sub 1} with a filtered version of x{sub 0}; gain factors 1/K and K normalize the lowpass- and highpass-filtered output subbands. Each of these steps is inverted by the corresponding operations in the synthesis bank shown in Figure 1(b). Lifting steps correspond to upper- or lower-triangular matrices, S{sub i}(z), in a cascade-form decomposition of the polyphase analysis matrix, H{sub a}(z). Lifting structures can also be implemented reversibly (i.e., losslessly in fixed-precision arithmetic) by rounding the lifting updates to integer values. Our treatment of the polyphase-with-advance representation develops an extensive matrix algebra framework that goes far beyond the results of. Specifically, we focus on analyzing and implementing linear phase two-channel filter banks via linear phase lifting cascade schemes. Whole-sample symmetric (WS) and half-sample symmetric (HS) linear phase filter banks are characterized completely in terms of the polyphase-with-advance representation. The theory benefits significantly from a number of new group-theoretic structures arising in the polyphase-with-advance matrix algebra from the lifting factorization of linear phase filter banks.

Emitter signal separation method based on multi-level digital channelization

Science.gov (United States)

Han, Xun; Ping, Yifan; Wang, Sujun; Feng, Ying; Kuang, Yin; Yang, Xinquan

2018-02-01

To solve the problem of emitter separation under complex electromagnetic environment, a signal separation method based on multi-level digital channelization is proposed in this paper. A two-level structure which can divide signal into different channel is designed first, after that, the peaks of different channels are tracked using the track filter and the coincident signals in time domain are separated in time-frequency domain. Finally, the time domain waveforms of different signals are acquired by reverse transformation. The validness of the proposed method is proved by experiment.

hybrid modulation scheme fo rid modulation scheme fo dulation

African Journals Online (AJOL)

eobe

control technique is done through simulations and ex control technique .... HYBRID MODULATION SCHEME FOR CASCADED H-BRIDGE INVERTER CELLS. C. I. Odeh ..... and OR operations. Referring to ... MATLAB/SIMULINK environment.

Harmonic Resonance Damping with a Hybrid Compensation System in Power Systems with Dispersed Generation

DEFF Research Database (Denmark)

Chen, Zhe; Pedersen, John Kim; Blaabjerg, Frede

2004-01-01

A hybrid compensation system consisting of an active filter and a group of distributed passive filters has been studied previously. The passive filters are used for each distorting load or Dispersed Generation (DG) unit to remove major harmonics and provide reactive power compensation. The active...... filter is connected in parallel with the distributed passive filters and loads/DGs to correct the system unbalance and remove the remaining harmonic components. The effectiveness of the presented compensation system has also been demonstrated. This paper studies the performance of the hybrid compensation...... demonstrated that the harmonic resonance can be damped effectively. The hybrid filter system is an effective compensation system for dispersed generation systems. In the compensation system, the passive filters are mainly responsible for main harmonic and reactive power compensation of each individual load/ DG...

Miniaturized high-temperature superconducting multiplexer with cascaded quadruplet structure

Science.gov (United States)

Xu, Zhang; Jingping, Liu; Shaolin, Yan; Lan, Fang; Bo, Zhang; Xinjie, Zhao

2015-06-01

In this paper, compact high temperature superconducting (HTS) multiplexers are presented for satellite communication applications. The first multiplexer consists of an input coupling node and three high-order bandpass filters, which is named triplexer. The node is realized by a loop microstrip line instead of conventional T-junction to eliminate the redundant susceptance due to combination of three filters. There are two eight-pole band-pass filters and one ten-pole band-pass filter with cascaded quadruplet structure for realizing high isolation. Moreover, the triplexer is extended to a multiplexer with six channels so as to verify the expansibility of the suggested approach. The triplexer is fabricated using double-sided YBa2Cu3O7 thin films on a 38 × 25 mm2 LaAlO3 substrate. The experimental results, when compared with those ones from the T-junction multiplexer, show that our multiplexer has lower insertion loss, smaller sizes and higher isolation between any two channels. Also, good agreement has been achieved between simulations and measurements, which illustrate the effectiveness of our methods for the design of high performance HTS multiplexers.

A hybrid nudging-ensemble Kalman filter approach to data assimilation. Part I: application in the Lorenz system

Directory of Open Access Journals (Sweden)

Lili Lei

2012-05-01

Full Text Available A hybrid data assimilation approach combining nudging and the ensemble Kalman filter (EnKF for dynamic analysis and numerical weather prediction is explored here using the non-linear Lorenz three-variable model system with the goal of a smooth, continuous and accurate data assimilation. The hybrid nudging-EnKF (HNEnKF computes the hybrid nudging coefficients from the flow-dependent, time-varying error covariance matrix from the EnKF's ensemble forecasts. It extends the standard diagonal nudging terms to additional off-diagonal statistical correlation terms for greater inter-variable influence of the innovations in the model's predictive equations to assist in the data assimilation process. The HNEnKF promotes a better fit of an analysis to data compared to that achieved by either nudging or incremental analysis update (IAU. When model error is introduced, it produces similar or better root mean square errors compared to the EnKF while minimising the error spikes/discontinuities created by the intermittent EnKF. It provides a continuous data assimilation with better inter-variable consistency and improved temporal smoothness than that of the EnKF. Data assimilation experiments are also compared to the ensemble Kalman smoother (EnKS. The HNEnKF has similar or better temporal smoothness than that of the EnKS, and with much smaller central processing unit (CPU time and data storage requirements.

Testing Group Mean Differences of Latent Variables in Multilevel Data Using Multiple-Group Multilevel CFA and Multilevel MIMIC Modeling.

Science.gov (United States)

Kim, Eun Sook; Cao, Chunhua

2015-01-01

Considering that group comparisons are common in social science, we examined two latent group mean testing methods when groups of interest were either at the between or within level of multilevel data: multiple-group multilevel confirmatory factor analysis (MG ML CFA) and multilevel multiple-indicators multiple-causes modeling (ML MIMIC). The performance of these methods were investigated through three Monte Carlo studies. In Studies 1 and 2, either factor variances or residual variances were manipulated to be heterogeneous between groups. In Study 3, which focused on within-level multiple-group analysis, six different model specifications were considered depending on how to model the intra-class group correlation (i.e., correlation between random effect factors for groups within cluster). The results of simulations generally supported the adequacy of MG ML CFA and ML MIMIC for multiple-group analysis with multilevel data. The two methods did not show any notable difference in the latent group mean testing across three studies. Finally, a demonstration with real data and guidelines in selecting an appropriate approach to multilevel multiple-group analysis are provided.

Performance Analysis of ZigBee Wireless Networks for AAL through Hybrid Ray Launching and Collaborative Filtering

Directory of Open Access Journals (Sweden)

Peio Lopez-Iturri

2016-01-01

Full Text Available This paper presents a novel hybrid simulation method based on the combination of an in-house developed 3D ray launching algorithm and a collaborative filtering (CF technique, which will be used to analyze the performance of ZigBee-based wireless sensor networks (WSNs to enable ambient assisted living (AAL. The combination of Low Definition results obtained by means of a deterministic ray launching method and the application of a CF technique leads to a drastic reduction of the time and computational cost required to obtain accurate simulation results. The paper also reports that this kind of AAL indoor complex scenario with multiple wireless devices needs a thorough and personalized radioplanning analysis as radiopropagation has a strong dependence on the network topology and the specific morphology of the scenario. The wireless channel analysis performed by our hybrid method provides valuable insight into network design phases of complex wireless systems, typical in AAL-oriented environments. Thus, it results in optimizing network deployment, reducing overall interference levels, and increasing the overall system performance in terms of cost reduction, transmission rates, and energy efficiency.

Characterizing the continuously acquired cardiovascular time series during hemodialysis, using median hybrid filter preprocessing noise reduction.

Science.gov (United States)

Wilson, Scott; Bowyer, Andrea; Harrap, Stephen B

2015-01-01

The clinical characterization of cardiovascular dynamics during hemodialysis (HD) has important pathophysiological implications in terms of diagnostic, cardiovascular risk assessment, and treatment efficacy perspectives. Currently the diagnosis of significant intradialytic systolic blood pressure (SBP) changes among HD patients is imprecise and opportunistic, reliant upon the presence of hypotensive symptoms in conjunction with coincident but isolated noninvasive brachial cuff blood pressure (NIBP) readings. Considering hemodynamic variables as a time series makes a continuous recording approach more desirable than intermittent measures; however, in the clinical environment, the data signal is susceptible to corruption due to both impulsive and Gaussian-type noise. Signal preprocessing is an attractive solution to this problem. Prospectively collected continuous noninvasive SBP data over the short-break intradialytic period in ten patients was preprocessed using a novel median hybrid filter (MHF) algorithm and compared with 50 time-coincident pairs of intradialytic NIBP measures from routine HD practice. The median hybrid preprocessing technique for continuously acquired cardiovascular data yielded a dynamic regression without significant noise and artifact, suitable for high-level profiling of time-dependent SBP behavior. Signal accuracy is highly comparable with standard NIBP measurement, with the added clinical benefit of dynamic real-time hemodynamic information.

Design and Analysis of Stepped DC Link Hybrid Converter for Solar PV Systems

Directory of Open Access Journals (Sweden)

R. Uthirasamy

2017-09-01

Full Text Available A structure of single phase DC Link Multilevel H-Bridge Inverter (DCLMLHBI is proposed for symmetrical Photo Voltaic (PV systems. Voltage stress across the inverter switches, Power Spectral Density (PSD, voltage and current harmonics are reduced in the proposed configuration. Compared with conventional 13-level Cascaded Multilevel Inverter (CMLI configuration, the proposed system configuration is structured with less number of series connected power switches and gate drive circuits. None of the passive components are utilized in the proposed inverter configuration, which highlight the significance of the proposed system. The performance parameters are investigated through Phase Opposition Pulse Width Modulation (POD-PWM switching scheme and its results are validated with computer simulation and prototype hardware models.

Cascaded-cavity Fabry-Perot interferometer for simultaneous measurement of temperature and strain with cross-sensitivity compensation

Science.gov (United States)

Tian, Jiajun; Jiao, Yuzhu; Ji, Shaobo; Dong, Xiaolong; Yao, Yong

2018-04-01

We propose and demonstrate a fiber sensor for simultaneous temperature and strain measurements. The proposed sensor is implemented by a cascaded-cavity Fabry-Perot (FP) fiber interferometer. The two cascaded FP cavities comprise a micro-air-cavity in a hollow-core tube fiber and a micro-silica-cavity in a standard single-mode fiber. To separate the interference spectrum of each FP cavity, the total spectrum is filtered in the frequency domain through band-pass filters, whose central frequencies were predesigned based on the relationship between the spatial frequency and free spectral range of each FP cavity. The different cross-sectional areas and thermal-optic coefficients of the two FP cavities confer different sensitivities to temperature and strain. Both parameters were measured simultaneously by tracking the wavelength shifts in the filtered interference spectra of the FP cavities. Moreover, the temperature-strain cross-sensitivity was compensated by solving a sensitivity-coefficient matrix equation for the two cavities, using the calibrated temperatures and strains. Other advantages of the proposed sensor are simple fabrication and an all-fiber structure. Owing to these properties, the proposed sensor is potentially applicable to real sensing applications.

Defect production in simulated cascades: Cascade quenching and short-term annealing

International Nuclear Information System (INIS)

Heinisch, H.L.

1983-01-01

Defect production in displacement cascades in copper has been modeled using the MARLOWE code to generate cascades and the stochastic annealing code ALSOME to simulate cascade quenching and short-term annealing of isolated cascades. Quenching is accomplished by using exaggerated values for defect mobilities and for critical reaction distances in ALSOME for a very short time. The quenched cascades are then short-term annealed with normal parameter values. The quenching parameter values were empirically determined by comparison with results of resistivity measurements. Throughout the collisional, quenching and short-term annealing phases of cascade development, the high energy cascades continue to behave as a collection of independent lower energy lobes. For recoils above about 30 keV the total number of defects and the numbers of free defects scale with the damage energy. As the energy decreases from 30 keV, defect production varies with the changing nature of the cascade configuration, resulting in more defects per unit damage energy. The simulated annealing of a low fluence of interacting cascades revealed an interstitial shielding effect on depleted zones during Stage I recovery. (orig.)

Non Isolated and Non-Inverting Cockcroft Walton Multiplier Based Hybrid 2Nx Interleaved Boost Converter For Renewable Energy Applications

DEFF Research Database (Denmark)

Bhaskar, Mahajan Sagar; Padamanaban, Sanjeevi Kumar; Blaabjerg, Frede

2016-01-01

In this paper hybrid non isolated and non-invertingCockcroft-Walton multiplier based 2Nx InterleavedBoost converter (2Nx IBC) for renewable energy applications is presented. The presented hybrid boost converter topology is derived from non-inverting Nx Multilevel Boost Converter (Nx MBC......) and inverting Nx Multilevel Boost Converter (Nx MBC). In renewable energy applications, generated voltage needs to be stepped up with high conversion ratio using a DC-DC converter at voltage levels as per the application requirement. The advantages of the presentedtopology of interleaved converter are high...

A non-conventional isotope separation cascade without any mixing: net cascade

International Nuclear Information System (INIS)

Zeng Shi; Jiang Dongjun; Ying Zhengen

2012-01-01

A component has different concentrations in the incoming flows at a confluent point in all existing isotope separations cascades for multi-component isotope separation and mixing is inevitable, which results in deterioration of separation performance of the separation cascade. However, realization of no-mixing at a confluent point is impossible with a conventional cascade. A non-conventional isotope separation cascade, net cascade, is found to be able to realize no mixings for all components at confluent points, and its concept is further developed here. No-mixing is fulfilled by requiring symmetrical separation of two specified key components at every stage, and the procedure of realizing no-mixing is presented in detail. Some properties of net cascade are investigated preliminarily, and the results demonstrated the no-mixing property is indeed realized. Net cascade is the only separation cascade that so far possesses the no-mixing property. (authors)

Analytically solvable chaotic oscillator based on a first-order filter

Energy Technology Data Exchange (ETDEWEB)

Corron, Ned J.; Cooper, Roy M.; Blakely, Jonathan N. [Charles M. Bowden Laboratory, Aviation and Missile Research, Development and Engineering Center, U.S. Army RDECOM, Redstone Arsenal, Alabama 35898 (United States)

2016-02-15

A chaotic hybrid dynamical system is introduced and its analytic solution is derived. The system is described as an unstable first order filter subject to occasional switching of a set point according to a feedback rule. The system qualitatively differs from other recently studied solvable chaotic hybrid systems in that the timing of the switching is regulated by an external clock. The chaotic analytic solution is an optimal waveform for communications in noise when a resistor-capacitor-integrate-and-dump filter is used as a receiver. As such, these results provide evidence in support of a recent conjecture that the optimal communication waveform for any stable infinite-impulse response filter is chaotic.

Realisation of low-voltage square-root-domain all-pass filters

Directory of Open Access Journals (Sweden)

Farooq A. Khanday

2013-10-01

Full Text Available Novel l ow-voltage first-order and second-order square-root-domain all-pass filters derived systematically by means of transfer function decomposition and state -space synthesis techniques are proposed. The employment of only a few geometric-mean cells and grounded capacitors permits the circuits to absorb shunt parasitic capacitances, which is desirable for production in monolithic form . The circuits enjoy the features of electronic adjustment of frequency characteristics, wider dynamic range and low-voltage environment operation. The filters are employed to design high-order all-pass filters using cascade approach. First-order low-pass and second-order band-pass filters, being the inherited building blocks of the proposed low-order all-pass filters are also discussed. The behaviour of the filters is evaluated through simulations using Taiwan semiconductor manufacturing company 0.25 μm level-3 complementary metal oxide semiconductor process parameters, where the most important performance factors are considered.

Exact Turbulence Law in Collisionless Plasmas: Hybrid Simulations

Science.gov (United States)

Hellinger, P.; Verdini, A.; Landi, S.; Franci, L.; Matteini, L.

2017-12-01

An exact vectorial law for turbulence in homogeneous incompressible Hall-MHD is derived and tested in two-dimensional hybrid simulations of plasma turbulence. The simulations confirm the validity of the MHD exact law in the kinetic regime, the simulated turbulence exhibits a clear inertial range on large scales where the MHD cascade flux dominates. The simulation results also indicate that in the sub-ion range the cascade continues via the Hall term and that the total cascade rate tends to decrease at around the ion scales, especially in high-beta plasmas. This decrease is like owing to formation of non-thermal features, such as collisionless ion energization, that can not be retained in the Hall MHD approximation.

Delta-Connected Cascaded H-Bridge Multilevel Converters for Large-Scale Photovoltaic Grid Integration

DEFF Research Database (Denmark)

Yu, Yifan; Konstantinou, Georgios; Townsend, Christopher D.

2017-01-01

The cascaded H-bridge (CHB) converter is becoming a promising candidate for use in next generation large-scale photovoltaic (PV) power plants. However, solar power generation in the three converter phase-legs can be significantly unbalanced, especially in a large geographically-dispersed plant....... The power imbalance between the three phases defines a limit for the injection of balanced three-phase currents to the grid. This paper quantifies the performance of, and experimentally confirms, the recently proposed delta-connected CHB converter for PV applications as an alternative configuration...... for large-scale PV power plants. The required voltage and current overrating for the converter is analytically developed and compared against the star-connected counterpart. It is shown that the delta-connected CHB converter extends the balancing capabilities of the star-connected CHB and can accommodate...

A generalized model via random walks for information filtering

Energy Technology Data Exchange (ETDEWEB)

Ren, Zhuo-Ming, E-mail: zhuomingren@gmail.com [Department of Physics, University of Fribourg, Chemin du Musée 3, CH-1700, Fribourg (Switzerland); Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, ChongQing, 400714 (China); Kong, Yixiu [Department of Physics, University of Fribourg, Chemin du Musée 3, CH-1700, Fribourg (Switzerland); Shang, Ming-Sheng, E-mail: msshang@cigit.ac.cn [Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, ChongQing, 400714 (China); Zhang, Yi-Cheng [Department of Physics, University of Fribourg, Chemin du Musée 3, CH-1700, Fribourg (Switzerland)

2016-08-06

There could exist a simple general mechanism lurking beneath collaborative filtering and interdisciplinary physics approaches which have been successfully applied to online E-commerce platforms. Motivated by this idea, we propose a generalized model employing the dynamics of the random walk in the bipartite networks. Taking into account the degree information, the proposed generalized model could deduce the collaborative filtering, interdisciplinary physics approaches and even the enormous expansion of them. Furthermore, we analyze the generalized model with single and hybrid of degree information on the process of random walk in bipartite networks, and propose a possible strategy by using the hybrid degree information for different popular objects to toward promising precision of the recommendation. - Highlights: • We propose a generalized recommendation model employing the random walk dynamics. • The proposed model with single and hybrid of degree information is analyzed. • A strategy with the hybrid degree information improves precision of recommendation.

A generalized model via random walks for information filtering

International Nuclear Information System (INIS)

Ren, Zhuo-Ming; Kong, Yixiu; Shang, Ming-Sheng; Zhang, Yi-Cheng

2016-01-01

There could exist a simple general mechanism lurking beneath collaborative filtering and interdisciplinary physics approaches which have been successfully applied to online E-commerce platforms. Motivated by this idea, we propose a generalized model employing the dynamics of the random walk in the bipartite networks. Taking into account the degree information, the proposed generalized model could deduce the collaborative filtering, interdisciplinary physics approaches and even the enormous expansion of them. Furthermore, we analyze the generalized model with single and hybrid of degree information on the process of random walk in bipartite networks, and propose a possible strategy by using the hybrid degree information for different popular objects to toward promising precision of the recommendation. - Highlights: • We propose a generalized recommendation model employing the random walk dynamics. • The proposed model with single and hybrid of degree information is analyzed. • A strategy with the hybrid degree information improves precision of recommendation.

Multi-Modality Cascaded Convolutional Neural Networks for Alzheimer's Disease Diagnosis.

Science.gov (United States)

Liu, Manhua; Cheng, Danni; Wang, Kundong; Wang, Yaping

2018-03-23

Accurate and early diagnosis of Alzheimer's disease (AD) plays important role for patient care and development of future treatment. Structural and functional neuroimages, such as magnetic resonance images (MRI) and positron emission tomography (PET), are providing powerful imaging modalities to help understand the anatomical and functional neural changes related to AD. In recent years, machine learning methods have been widely studied on analysis of multi-modality neuroimages for quantitative evaluation and computer-aided-diagnosis (CAD) of AD. Most existing methods extract the hand-craft imaging features after image preprocessing such as registration and segmentation, and then train a classifier to distinguish AD subjects from other groups. This paper proposes to construct cascaded convolutional neural networks (CNNs) to learn the multi-level and multimodal features of MRI and PET brain images for AD classification. First, multiple deep 3D-CNNs are constructed on different local image patches to transform the local brain image into more compact high-level features. Then, an upper high-level 2D-CNN followed by softmax layer is cascaded to ensemble the high-level features learned from the multi-modality and generate the latent multimodal correlation features of the corresponding image patches for classification task. Finally, these learned features are combined by a fully connected layer followed by softmax layer for AD classification. The proposed method can automatically learn the generic multi-level and multimodal features from multiple imaging modalities for classification, which are robust to the scale and rotation variations to some extent. No image segmentation and rigid registration are required in pre-processing the brain images. Our method is evaluated on the baseline MRI and PET images of 397 subjects including 93 AD patients, 204 mild cognitive impairment (MCI, 76 pMCI +128 sMCI) and 100 normal controls (NC) from Alzheimer's Disease Neuroimaging

Hybrid compensation arrangement in dispersed generation systems

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim

2005-01-01

This paper presents a hybrid compensation system consisting of an active filter and distributed passive filters. In the system, each individual passive filter is connected to a distortion source and designed to eliminate main harmonics and supply reactive power for the distortion source, while...... filter system consisting of distributed passive filters and an active filter....... the active filter is responsible for the correction of the system unbalance and the cancellation of the remaining harmonics. The paper also analyzes the effects of the circuit configuration on the system impedance characteristics and consequently the effectiveness of the filter system. Simulation studies...

Nonlinear Control Structure of Grid Connected Modular Multilevel Converters

DEFF Research Database (Denmark)

Hajizadeh, Amin; Norum, Lars; Ahadpour Shal, Alireza

2017-01-01

in the prediction step in order to preserve the stochastic characteristics of a nonlinear system. In order to design adaptive robust control strategy and nonlinear observer, mathematical model of MMC using rotating d-q theory has been used. Digital time-domain simulation studies are carried out in the Matlab......This paper implements nonlinear control structure based on Adaptive Fuzzy Sliding Mode (AFSM) Current Control and Unscented Kalman Filter (UKF) to estimate the capacitor voltages from the measurement of arm currents of Modular Multilevel Converter (MMC). UKF use nonlinear unscented transforms....../Simulink environment to verify the performance of the overall proposed control structure during different case studies....

On-Chip Hardware for Cell Monitoring: Contact Imaging and Notch Filtering

Science.gov (United States)

2005-07-07

a polymer carrier. Spectrophotometer chosen and purchased for testing optical filters and materials. Characterization and comparison of fabricated...reproducibility of behavior. Multi-level SU8 process developed. Optimization of actuator for closing vial lids and development of lid sealing technology is...bending angles characterized as a function of temperature in NaDBS solution. " Photopatternable polymers are a viable interim packaging solution; through

Defect production in simulated cascades: cascade quenching and short-term annealing

International Nuclear Information System (INIS)

Heinisch, H.L.

1982-01-01

Defect production in high energy displacement cascades has been modeled using the computer code MARLOWE to generate the cascades and the stochastic computer code ALSOME to simulate the cascade quenching and short-term annealing of isolated cascades. The quenching is accomplished by using ALSOME with exaggerated values for defect mobilities and critical reaction distanes for recombination and clustering, which are in effect until the number of defect pairs is equal to the value determined from resistivity experiments at 4K. Then normal mobilities and reaction distances are used during short-term annealing to a point representative of Stage III recovery. Effects of cascade interactions at low fluences are also being investigated. The quenching parameter values were empirically determined for 30 keV cascades. The results agree well with experimental information throughout the range from 1 keV to 100 keV. Even after quenching and short-term annealing the high energy cascades behave as a collection of lower energy subcascades and lobes. Cascades generated in a crystal having thermal displacements were found to be in better agreement with experiments after quenching and annealing than those generated in a non-thermal crystal

Protective Controller against Cascade Outages with Selective Harmonic Compensation Function

Science.gov (United States)

Abramovich, B. N.; Kuznetsov, P. A.; Sychev, Yu A.

2018-05-01

The paper presents data on the power quality and development of protective devices for the power networks with distributed generation (DG).The research has shown that power quality requirements for DG networks differ from conventional ones. That is why main tendencies, protective equipment and filters should be modified. There isa developed algorithm for detection and prevention of cascade outages that can lead to the blackoutin DG networks and there was a proposed structural scheme for a new active power filter for selective harmonics compensation. Analysis of these theories and equipment led to the development of protective device that could monitor power balance and cut off non-important consumers. The last part of the article describes a microcontroller prototype developed for connection to the existing power station control center.

Hybrid Systems Based on Layered Silicate and Organic Dyes for Cascade Energy Transfer

Czech Academy of Sciences Publication Activity Database

Belušáková, S.; Lang, Kamil; Bujdák, J.

2015-01-01

Roč. 119, č. 38 (2015), s. 21784-21794 ISSN 1932-7447 Institutional support: RVO:61388980 Keywords : Cascade energy transfers * Multicomponent films * Resonance energy transfer * Spectral properties * Steady state fluorescence * Time-resolved fluorescence spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 4.509, year: 2015

Restriction Cascade Exponential Amplification (RCEA) assay with an attomolar detection limit: a novel, highly specific, isothermal alternative to qPCR.

Science.gov (United States)

Ghindilis, Andrey L; Smith, Maria W; Simon, Holly M; Seoudi, Ihab A; Yazvenko, Nina S; Murray, Iain A; Fu, Xiaoqing; Smith, Kenneth; Jen-Jacobson, Linda; Xu, Shuang-Yong

2015-01-13

An alternative to qPCR was developed for nucleic acid assays, involving signal rather than target amplification. The new technology, Restriction Cascade Exponential Amplification (RCEA), relies on specific cleavage of probe-target hybrids by restriction endonucleases (REase). Two mutant REases for amplification (Ramp), S17C BamHI and K249C EcoRI, were conjugated to oligonucleotides, and immobilized on a solid surface. The signal generation was based on: (i) hybridization of a target DNA to a Ramp-oligonucleotide probe conjugate, followed by (ii) specific cleavage of the probe-target hybrid using a non-immobilized recognition REase. The amount of Ramp released into solution upon cleavage was proportionate to the DNA target amount. Signal amplification was achieved through catalysis, by the free Ramp, of a restriction cascade containing additional oligonucleotide-conjugated Ramp and horseradish peroxidase (HRP). Colorimetric quantification of free HRP indicated that the RCEA achieved a detection limit of 10 aM (10(-17) M) target concentration, or approximately 200 molecules, comparable to the sensitivity of qPCR-based assays. The RCEA assay had high specificity, it was insensitive to non-specific binding, and detected target sequences in the presence of foreign DNA. RCEA is an inexpensive isothermal assay that allows coupling of the restriction cascade signal amplification with any DNA target of interest.

Photonic bandpass filter characteristics of multimode SOI waveguides integrated with submicron gratings.

Science.gov (United States)

Sah, Parimal; Das, Bijoy Krishna

2018-03-20

It has been shown that a fundamental mode adiabatically launched into a multimode SOI waveguide with submicron grating offers well-defined flat-top bandpass filter characteristics in transmission. The transmitted spectral bandwidth is controlled by adjusting both waveguide and grating design parameters. The bandwidth is further narrowed down by cascading two gratings with detuned parameters. A semi-analytical model is used to analyze the filter characteristics (1500  nm≤λ≤1650  nm) of the device operating in transverse-electric polarization. The proposed devices were fabricated with an optimized set of design parameters in a SOI substrate with a device layer thickness of 250 nm. The pass bandwidth of waveguide devices integrated with single-stage gratings are measured to be ∼24  nm, whereas the device with two cascaded gratings with slightly detuned periods (ΔΛ=2  nm) exhibits a pass bandwidth down to ∼10  nm.

Catalytic pleat filter bags for combined particulate separation and nitrogen oxides removal from flue gas streams

International Nuclear Information System (INIS)

Park, Young Ok; Choi, Ho Kyung

2010-01-01

The development of a high temperature catalytically active pleated filter bag with hybrid filter equipment for the combined removal of particles and nitrogen oxides from flue gas streams is presented. A special catalyst load in stainless steel mesh cartridge with a high temperature pleated filter bag followed by optimized catalytic activation was developed to reach the required nitrogen oxides levels and to maintain the higher collection efficiencies. The catalytic properties of the developed high temperature filter bags with hybrid filter equipment were studied and demonstrated in a pilot scale test rig and a demonstration plant using commercial scale of high temperature catalytic pleated filter bags. The performance of the catalytic pleated filter bags were tested under different operating conditions, such as filtration velocity and operating temperature. Moreover, the cleaning efficiency and residual pressure drop of the catalyst loaded cartridges in pleated filter bags were tested. As result of theses studies, the optimum operating conditions for the catalytic pleated filter bags are determined. (author)

Conceptualising Multilevel Regulation in the EU: A Legal Translation of Multilevel Governance?

NARCIS (Netherlands)

Chowdhury, Nupur; Wessel, Ramses A.

2012-01-01

How should we conceive of regulation in the European context? This paper attempts to answer this by developing multilevel regulation as a theoretical concept. The basic aim of the paper is to explore the difference and convergence between regulation and governance and develop multilevel governance

Novel Resistorless First-Order Current-Mode Universal Filter Employing a Grounded Capacitor

Directory of Open Access Journals (Sweden)

R. Arslanalp

2011-09-01

Full Text Available In this paper, a new bipolar junction transistor (BJT based configuration for providing first-order resistorless current-mode (CM all-pass, low-pass and high-pass filter responses from the same configuration is suggested. The proposed circuit called as a first-order universal filter possesses some important advantages such as consisting of a few BJTs and a grounded capacitor, consuming very low power and having electronic tunability property of its pole frequency. Additionally, types of filter response can be obtained only by changing the values of current sources. The suggested circuit does not suffer from disadvantages of use of the resistors in IC process. The presented first-order universal filter topology does not need any passive element matching constraints. Moreover, as an application example, a second-order band-pass filter is obtained by cascading two proposed filter structures which are operating as low-pass filter and high-pass one. Simulations by means of PSpice program are accomplished to demonstrate the performance and effectiveness of the developed first-order universal filter.

Multilevel corporate environmental responsibility.

Science.gov (United States)

Karassin, Orr; Bar-Haim, Aviad

2016-12-01

The multilevel empirical study of the antecedents of corporate social responsibility (CSR) has been identified as "the first knowledge gap" in CSR research. Based on an extensive literature review, the present study outlines a conceptual multilevel model of CSR, then designs and empirically validates an operational multilevel model of the principal driving factors affecting corporate environmental responsibility (CER), as a measure of CSR. Both conceptual and operational models incorporate three levels of analysis: institutional, organizational, and individual. The multilevel nature of the design allows for the assessment of the relative importance of the levels and of their components in the achievement of CER. Unweighted least squares (ULS) regression analysis reveals that the institutional-level variables have medium relationships with CER, some variables having a negative effect. The organizational level is revealed as having strong and positive significant relationships with CER, with organizational culture and managers' attitudes and behaviors as significant driving forces. The study demonstrates the importance of multilevel analysis in improving the understanding of CSR drivers, relative to single level models, even if the significance of specific drivers and levels may vary by context. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multilevel geometry optimization

Science.gov (United States)

Rodgers, Jocelyn M.; Fast, Patton L.; Truhlar, Donald G.

2000-02-01

Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol.

Practical Gammatone-Like Filters for Auditory Processing

Directory of Open Access Journals (Sweden)

R. F. Lyon

2007-12-01

Full Text Available This paper deals with continuous-time filter transfer functions that resemble tuning curves at particular set of places on the basilar membrane of the biological cochlea and that are suitable for practical VLSI implementations. The resulting filters can be used in a filterbank architecture to realize cochlea implants or auditory processors of increased biorealism. To put the reader into context, the paper starts with a short review on the gammatone filter and then exposes two of its variants, namely, the differentiated all-pole gammatone filter (DAPGF and one-zero gammatone filter (OZGF, filter responses that provide a robust foundation for modeling cochlea transfer functions. The DAPGF and OZGF responses are attractive because they exhibit certain characteristics suitable for modeling a variety of auditory data: level-dependent gain, linear tail for frequencies well below the center frequency, asymmetry, and so forth. In addition, their form suggests their implementation by means of cascades of N identical two-pole systems which render them as excellent candidates for efficient analog or digital VLSI realizations. We provide results that shed light on their characteristics and attributes and which can also serve as “design curves” for fitting these responses to frequency-domain physiological data. The DAPGF and OZGF responses are essentially a “missing link” between physiological, electrical, and mechanical models for auditory filtering.

A novel electrochemical sensor for lead ion based on cascade DNA and quantum dots amplification

International Nuclear Information System (INIS)

Tang, Shurong; Lu, Wei; Gu, Fang; Tong, Ping; Yan, Zhiming; Zhang, Lan

2014-01-01

A new enzyme-free and ultrasensitive electrochemical Pb 2+ biosensor was developed. By coupling the DNA-assisted cascade of hybridization reaction with the quantum dots (QDs) for signal amplification, a detection limit as low as 6.1 pM can be obtained for Pb 2+ . In this study, the “8-17” DNAzyme was used for specific recognition of Pb 2+ . In the presence of Pb 2+ , the DNAzyme was activated and cleaved the substrate strand. And then, the hybridization between the linker probe and signal probe was initiated, which resulted in formation of a long cascade DNA structure as well as assemble of numerous QDs at last. By the use of magnetic beads, the free signal probe can be easily removed by external magnetic field. After acid lysis, a great amount of redox cations can be released from the QDs and eventually result in significantly amplified electrochemical signals. This method is highly sensitive, selective and simple without the participation of any protein based enzyme (nuclease), thereby holds great potential for real sample analysis

Multilevel Models: Conceptual Framework and Applicability

Directory of Open Access Journals (Sweden)

Roxana-Otilia-Sonia Hrițcu

2015-10-01

Full Text Available Individuals and the social or organizational groups they belong to can be viewed as a hierarchical system situated on different levels. Individuals are situated on the first level of the hierarchy and they are nested together on the higher levels. Individuals interact with the social groups they belong to and are influenced by these groups. Traditional methods that study the relationships between data, like simple regression, do not take into account the hierarchical structure of the data and the effects of a group membership and, hence, results may be invalidated. Unlike standard regression modelling, the multilevel approach takes into account the individuals as well as the groups to which they belong. To take advantage of the multilevel analysis it is important that we recognize the multilevel characteristics of the data. In this article we introduce the outlines of multilevel data and we describe the models that work with such data. We introduce the basic multilevel model, the two-level model: students can be nested into classes, individuals into countries and the general two-level model can be extended very easily to several levels. Multilevel analysis has begun to be extensively used in many research areas. We present the most frequent study areas where multilevel models are used, such as sociological studies, education, psychological research, health studies, demography, epidemiology, biology, environmental studies and entrepreneurship. We support the idea that since hierarchies exist everywhere, multilevel data should be recognized and analyzed properly by using multilevel modelling.

Improved efficiency in organic/inorganic hybrid solar cells by interfacial modification of ZnO nanowires with small molecules

International Nuclear Information System (INIS)

Chang, Sehoon; Park, Hyesung; Cheng, Jayce J; Rekemeyer, Paul H; Gradečak, Silvija

2014-01-01

We demonstrate improved photovoltaic performance of ZnO nanowire/poly(3-hexylthiophene) (P3HT) nanofiber hybrid devices using an interfacial modification of ZnO nanowires. Formation of cascade energy levels between the ZnO nanowire and P3HT nanofiber was achieved by interfacial modification of ZnO nanowires using small molecules tetraphenyldibenzoperiflanthene (DBP) and 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI). The successful demonstration of improved device performance owing to the cascade energy levels by small molecule modification is a promising approach toward highly efficient organic/inorganic hybrid solar cells. (paper)

A generalized model via random walks for information filtering

Science.gov (United States)

Ren, Zhuo-Ming; Kong, Yixiu; Shang, Ming-Sheng; Zhang, Yi-Cheng

2016-08-01

There could exist a simple general mechanism lurking beneath collaborative filtering and interdisciplinary physics approaches which have been successfully applied to online E-commerce platforms. Motivated by this idea, we propose a generalized model employing the dynamics of the random walk in the bipartite networks. Taking into account the degree information, the proposed generalized model could deduce the collaborative filtering, interdisciplinary physics approaches and even the enormous expansion of them. Furthermore, we analyze the generalized model with single and hybrid of degree information on the process of random walk in bipartite networks, and propose a possible strategy by using the hybrid degree information for different popular objects to toward promising precision of the recommendation.

Cascade Storage and Delivery System for a Multi Mission Space Exploration Vehicle (MMSEV)

Science.gov (United States)

Yagoda, Evan; Swickrath, Michael; Stambaugh, Imelda

2012-01-01

NASA is developing a Multi Mission Space Exploration Vehicle (MMSEV) for missions beyond Low Earth Orbit (LEO). The MMSEV is a pressurized vehicle used to extend the human exploration envelope for Lunar, Near Earth Object (NEO), and Deep Space missions. The Johnson Space Center is developing the Environmental Control and Life Support System (ECLSS) for the MMSEV. The MMSEV s intended use is to support longer sortie lengths with multiple Extra Vehicular Activities (EVAs) on a higher magnitude than any previous vehicle. This paper presents an analysis of a high pressure oxygen cascade storage and delivery system that will accommodate the crew during long duration Intra Vehicular Activity (IVA) and capable of multiple high pressure oxygen fills to the Portable Life Support System (PLSS) worn by the crew during EVAs. A cascade is a high pressure gas cylinder system used for the refilling of smaller compressed gas cylinders. Each of the large cylinders are filled by a compressor, but the cascade system allows small cylinders to be filled without the need of a compressor. In addition, the cascade system is useful as a "reservoir" to accommodate low pressure needs. A regression model was developed to provide the mechanism to size the cascade systems subject to constraints such as number of crew, extravehicular activity duration and frequency, and ullage gas requirements under contingency scenarios. The sizing routine employed a numerical integration scheme to determine gas compressibility changes during depressurization and compressibility effects were captured using the Soave-Redlich-Kwong (SRK) equation of state. A multi-dimensional nonlinear optimization routine was used to find the minimum cascade tank system mass that meets the mission requirements. The sizing algorithms developed in this analysis provide a powerful framework to assess cascade filling, compressor, and hybrid systems to design long duration vehicle ECLSS architecture. 1

Multilevel geometry optimization

Energy Technology Data Exchange (ETDEWEB)

Rodgers, Jocelyn M. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Fast, Patton L. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Truhlar, Donald G. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)

2000-02-15

Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol. (c) 2000 American Institute of Physics.

Multilevel models applications using SAS

CERN Document Server

Wang, Jichuan; Fisher, James F

2011-01-01

This book covers a broad range of topics about multilevel modeling. The goal is to help readers to understand the basic concepts, theoretical frameworks, and application methods of multilevel modeling. It is at a level also accessible to non-mathematicians, focusing on the methods and applications of various multilevel models and using the widely used statistical software SAS®. Examples are drawn from analysis of real-world research data.

Multiscale Hybrid Nonlocal Means Filtering Using Modified Similarity Measure

Directory of Open Access Journals (Sweden)

Zahid Hussain Shamsi

2015-01-01

Full Text Available A new multiscale implementation of nonlocal means filtering (MHNLM for image denoising is proposed. The proposed algorithm also introduces a modification of the similarity measure for patch comparison. Assuming the patch as an oriented surface, the notion of a normal vectors patch is introduced. The inner product of these normal vectors patches is defined and then used in the weighted Euclidean distance of intensity patches as the weight factor. The algorithm involves two steps: the first step is a multiscale implementation of an accelerated nonlocal means filtering in the discrete stationary wavelet domain to obtain a refined version of the noisy patches for later comparison. The next step is to apply the proposed modification of standard nonlocal means filtering to the noisy image using the reference patches obtained in the first step. These refined patches contain less noise, and consequently the computation of normal vectors and partial derivatives is more precise. Experimental results show equivalent or better performance of the proposed algorithm compared to various state-of-the-art algorithms.

A Decoupling Control Method for Shunt Hybrid Active Power Filter Based on Generalized Inverse System

Directory of Open Access Journals (Sweden)

Xin Li

2017-01-01

Full Text Available In this paper, a novel decoupling control method based on generalized inverse system is presented to solve the problem of SHAPF (Shunt Hybrid Active Power Filter possessing the characteristics of 2-input-2-output nonlinearity and strong coupling. Based on the analysis of operation principle, the mathematical model of SHAPF is firstly built, which is verified to be invertible using interactor algorithm; then the generalized inverse system of SHAPF is obtained to connect in series with the original system so that the composite system is decoupled under the generalized inverse system theory. The PI additional controller is finally designed to control the decoupled 1-order pseudolinear system to make it possible to adjust the performance of the subsystem. The simulation results demonstrated by MATLAB show that the presented generalized inverse system strategy can realise the dynamic decoupling of SHAPF. And the control system has fine dynamic and static performance.

Hybrid Cubature Kalman filtering for identifying nonlinear models from sampled recording: Estimation of neuronal dynamics.

Science.gov (United States)

Madi, Mahmoud K; Karameh, Fadi N

2017-01-01

Kalman filtering methods have long been regarded as efficient adaptive Bayesian techniques for estimating hidden states in models of linear dynamical systems under Gaussian uncertainty. Recent advents of the Cubature Kalman filter (CKF) have extended this efficient estimation property to nonlinear systems, and also to hybrid nonlinear problems where by the processes are continuous and the observations are discrete (continuous-discrete CD-CKF). Employing CKF techniques, therefore, carries high promise for modeling many biological phenomena where the underlying processes exhibit inherently nonlinear, continuous, and noisy dynamics and the associated measurements are uncertain and time-sampled. This paper investigates the performance of cubature filtering (CKF and CD-CKF) in two flagship problems arising in the field of neuroscience upon relating brain functionality to aggregate neurophysiological recordings: (i) estimation of the firing dynamics and the neural circuit model parameters from electric potentials (EP) observations, and (ii) estimation of the hemodynamic model parameters and the underlying neural drive from BOLD (fMRI) signals. First, in simulated neural circuit models, estimation accuracy was investigated under varying levels of observation noise (SNR), process noise structures, and observation sampling intervals (dt). When compared to the CKF, the CD-CKF consistently exhibited better accuracy for a given SNR, sharp accuracy increase with higher SNR, and persistent error reduction with smaller dt. Remarkably, CD-CKF accuracy shows only a mild deterioration for non-Gaussian process noise, specifically with Poisson noise, a commonly assumed form of background fluctuations in neuronal systems. Second, in simulated hemodynamic models, parametric estimates were consistently improved under CD-CKF. Critically, time-localization of the underlying neural drive, a determinant factor in fMRI-based functional connectivity studies, was significantly more accurate

Hybrid Cubature Kalman filtering for identifying nonlinear models from sampled recording: Estimation of neuronal dynamics

Science.gov (United States)

2017-01-01

Kalman filtering methods have long been regarded as efficient adaptive Bayesian techniques for estimating hidden states in models of linear dynamical systems under Gaussian uncertainty. Recent advents of the Cubature Kalman filter (CKF) have extended this efficient estimation property to nonlinear systems, and also to hybrid nonlinear problems where by the processes are continuous and the observations are discrete (continuous-discrete CD-CKF). Employing CKF techniques, therefore, carries high promise for modeling many biological phenomena where the underlying processes exhibit inherently nonlinear, continuous, and noisy dynamics and the associated measurements are uncertain and time-sampled. This paper investigates the performance of cubature filtering (CKF and CD-CKF) in two flagship problems arising in the field of neuroscience upon relating brain functionality to aggregate neurophysiological recordings: (i) estimation of the firing dynamics and the neural circuit model parameters from electric potentials (EP) observations, and (ii) estimation of the hemodynamic model parameters and the underlying neural drive from BOLD (fMRI) signals. First, in simulated neural circuit models, estimation accuracy was investigated under varying levels of observation noise (SNR), process noise structures, and observation sampling intervals (dt). When compared to the CKF, the CD-CKF consistently exhibited better accuracy for a given SNR, sharp accuracy increase with higher SNR, and persistent error reduction with smaller dt. Remarkably, CD-CKF accuracy shows only a mild deterioration for non-Gaussian process noise, specifically with Poisson noise, a commonly assumed form of background fluctuations in neuronal systems. Second, in simulated hemodynamic models, parametric estimates were consistently improved under CD-CKF. Critically, time-localization of the underlying neural drive, a determinant factor in fMRI-based functional connectivity studies, was significantly more accurate

Multilevel models for longitudinal data

OpenAIRE

Fiona Steele

2008-01-01

Repeated measures and repeated events data have a hierarchical structure which can be analysed by using multilevel models. A growth curve model is an example of a multilevel random-coefficients model, whereas a discrete time event history model for recurrent events can be fitted as a multilevel logistic regression model. The paper describes extensions to the basic growth curve model to handle auto-correlated residuals, multiple-indicator latent variables and correlated growth processes, and e...

Equalization of Loudspeaker and Room Responses Using Kautz Filters: Direct Least Squares Design

Directory of Open Access Journals (Sweden)

Karjalainen Matti

2007-01-01

Full Text Available DSP-based correction of loudspeaker and room responses is becoming an important part of improving sound reproduction. Such response equalization (EQ is based on using a digital filter in cascade with the reproduction channel to counteract the response errors introduced by loudspeakers and room acoustics. Several FIR and IIR filter design techniques have been proposed for equalization purposes. In this paper we investigate Kautz filters, an interesting class of IIR filters, from the point of view of direct least squares EQ design. Kautz filters can be seen as generalizations of FIR filters and their frequency-warped counterparts. They provide a flexible means to obtain desired frequency resolution behavior, which allows low filter orders even for complex corrections. Kautz filters have also the desirable property to avoid inverting dips in transfer function to sharp and long-ringing resonances in the equalizer. Furthermore, the direct least squares design is applicable to nonminimum-phase EQ design and allows using a desired target response. The proposed method is demonstrated by case examples with measured and synthetic loudspeaker and room responses.

Interband cascade lasers

International Nuclear Information System (INIS)

Vurgaftman, I; Meyer, J R; Canedy, C L; Kim, C S; Bewley, W W; Merritt, C D; Abell, J; Weih, R; Kamp, M; Kim, M; Höfling, S

2015-01-01

We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron–hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3–6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm −2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT. (topical review)

Functional Blocks and Biquadratic ARC Filters using Transimpedance Amplifiers

Directory of Open Access Journals (Sweden)

R. Sarman

1997-04-01

Full Text Available The aims of the article are design and analysis of modern circuits including high performance functional blocks and biquadratic filters using transimpedance amplifiers. Here are given various types of these circuits, that works in classical voltage, current or hybrid mode. In this paper are also compared various possibilities of connection of single amplifier filters as for reduction of influence of transimpedance amplifier parasitic elements.

Functional Blocks and Biquadratic ARC Filters using Transimpedance Amplifiers

OpenAIRE

R. Sarman; R. Prokop; T. Dostal

1997-01-01

The aims of the article are design and analysis of modern circuits including high performance functional blocks and biquadratic filters using transimpedance amplifiers. Here are given various types of these circuits, that works in classical voltage, current or hybrid mode. In this paper are also compared various possibilities of connection of single amplifier filters as for reduction of influence of transimpedance amplifier parasitic elements.

The use of linear programming techniques to design optimal digital filters for pulse shaping and channel equalization

Science.gov (United States)

Houts, R. C.; Burlage, D. W.

1972-01-01

A time domain technique is developed to design finite-duration impulse response digital filters using linear programming. Two related applications of this technique in data transmission systems are considered. The first is the design of pulse shaping digital filters to generate or detect signaling waveforms transmitted over bandlimited channels that are assumed to have ideal low pass or bandpass characteristics. The second is the design of digital filters to be used as preset equalizers in cascade with channels that have known impulse response characteristics. Example designs are presented which illustrate that excellent waveforms can be generated with frequency-sampling filters and the ease with which digital transversal filters can be designed for preset equalization.

A multigrid solution method for mixed hybrid finite elements

Energy Technology Data Exchange (ETDEWEB)

Schmid, W. [Universitaet Augsburg (Germany)

1996-12-31

We consider the multigrid solution of linear equations arising within the discretization of elliptic second order boundary value problems of the form by mixed hybrid finite elements. Using the equivalence of mixed hybrid finite elements and non-conforming nodal finite elements, we construct a multigrid scheme for the corresponding non-conforming finite elements, and, by this equivalence, for the mixed hybrid finite elements, following guidelines from Arbogast/Chen. For a rectangular triangulation of the computational domain, this non-conforming schemes are the so-called nodal finite elements. We explicitly construct prolongation and restriction operators for this type of non-conforming finite elements. We discuss the use of plain multigrid and the multilevel-preconditioned cg-method and compare their efficiency in numerical tests.

Modeling of cascade and sub-cascade formation at high pka energies in irradiated fusion structural materials

International Nuclear Information System (INIS)

Ryazanov, A.; Metelkin, E.V.; Semenov, E.A.

2007-01-01

Full text of publication follows: A new theoretical model is developed for the investigations of cascade and sub-cascade formation in fusion structural materials under fast neutron irradiation at high primary knock atom (PKA) energies. Under 14 MeV neutron irradiation especially of light fusion structural materials such as Be, C, SiC materials PKA will have the energies up to 1 MeV. At such high energies it is very difficult to use the Monte Carlo or molecular dynamic simulations. The developed model is based on the analytical consideration of elastic collisions between displaced moving atoms into atomic cascades produced by a PKAs with the some kinetic energy obtained from fast neutrons. The Tomas-Fermy interaction potential is used for the describing of elastic collisions between moving atoms. The suggested model takes into account also the electronic losses for moving atoms between elastic collisions. The self consistent criterion for sub-cascade formation is suggested here which is based on the comparison of mean distance between two consequent PKA collisions and size of sub-cascade produced by PKA. The analytical relations for the most important characteristics of cascades and sub-cascade are determined including the average number of sub-cascades per one PKA in the dependence on PKA energy, the distance between sub-cascades and the average cascade and sub-cascade sizes as a function of PKA energy. The developed model allows determining the total numbers, distribution functions of cascades and sub-cascades in dependence on their sizes and generation rate of cascades and sub-cascades for different fusion neutron energy spectra. Based on the developed model the numerical calculations for main characteristics of cascades and sub-cascades in different fusion structural materials are performed using the neutron flux and PKA energy spectra for fusion reactors: ITER and DEMO. The main characteristics for cascade and sub-cascade formation are calculated here for the

Design of a Narrow Bandwidth Bandpass Filter Using Compact Spiral Resonator with Chirality

Directory of Open Access Journals (Sweden)

Weiping Li

2016-01-01

Full Text Available In this article, a compact narrow-bandpass filter with high selectivity and improved rejection level is presented. For miniaturization, a pair of double negative (DNG cells consisting of quasi-planar chiral resonators are cascaded and electrically loaded to a microstrip transmission line; short ended stubs are introduced to expand upper rejection band. The structure is analyzed using equivalent circuit models and simulated based on EM simulation software. For validation, the proposed filter is fabricated and measured. The measured results are in good agreement with the simulated ones. By comparing to other filters in the references, it is shown that the proposed filter has the advantage of skirt selectivity and compact size, so it can be integrated more conveniently in modern wireless communication systems and microwave planar circuits.

New Gain Controllable Resistor-less Current-mode First Order Allpass Filter and its Application

Directory of Open Access Journals (Sweden)

W. Jaikla

2012-04-01

Full Text Available New first order allpass filter (APF in current mode, constructed from 2 CCCCTAs and grounded capacitor, is presented. The current gain and phase shift can be electronically /orthogonally controlled. Low input and high output impedances are achieved which make the circuit to be easily cascaded to the current-mode circuit without additional current buffers. The operation of the proposed filter has been verified through simulation results which confirm the theoretical analysis. The application example as current-mode quadrature oscillator with non-interactive current control for both of oscillation condition and oscillation frequency is included to show the usability of the proposed filter.

Atom-atom collision cascades localization

International Nuclear Information System (INIS)

Kirsanov, V.V.

1980-01-01

The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

Focus-based filtering + clustering technique for power-law networks with small world phenomenon

Science.gov (United States)

Boutin, François; Thièvre, Jérôme; Hascoët, Mountaz

2006-01-01

Realistic interaction networks usually present two main properties: a power-law degree distribution and a small world behavior. Few nodes are linked to many nodes and adjacent nodes are likely to share common neighbors. Moreover, graph structure usually presents a dense core that is difficult to explore with classical filtering and clustering techniques. In this paper, we propose a new filtering technique accounting for a user-focus. This technique extracts a tree-like graph with also power-law degree distribution and small world behavior. Resulting structure is easily drawn with classical force-directed drawing algorithms. It is also quickly clustered and displayed into a multi-level silhouette tree (MuSi-Tree) from any user-focus. We built a new graph filtering + clustering + drawing API and report a case study.

Compact and Wide Stopband Lowpass Filter Using Open Complementary Split Ring Resonator and Defected Ground Structure

Directory of Open Access Journals (Sweden)

S. S. Karthikeyan

2015-09-01

Full Text Available A compact (0.16 λg x 0.08 λg and wide stop¬band lowpass filter design using open complementary split ring resonator (OCSRR and defected ground structure (DGS is presented in this paper. Low pass filter is con-structed using two cascaded stages of OCSRR. Since the rejection bandwidth of the OCSRR is narrow, tapered dumbbell shaped DGS section is placed under the OCSRR to enhance the bandwidth. The cutoff frequency (fc of the proposed lowpass filter is 1.09 GHz. The rejection band¬width of the filter covers the entire ultra wideband spec¬trum. Hence the spurious passband suppression is achieved up to 10 fc. The designed filter has been fabri¬cated and validated by experimental results

Universal Voltage Conveyor and its Novel Dual-Output Fully-Cascadable VM APF Application

Directory of Open Access Journals (Sweden)

Norbert Herencsar

2017-03-01

Full Text Available This letter presents a novel realization of a voltage-mode (VM first-order all-pass filter (APF with attractive features. The proposed circuit employs a single readily available six-terminal active device called as universal voltage conveyor (UVC and only grounded passive components, which predict its easy monolithic integration with desired circuit simplicity. The auxiliary voltage input (W and output (ZP, ZN terminals of the device fully ensure easy cascadability of VM APF, since the input and output terminal impedances are theoretically infinitely high and zero, respectively. Moreover, thanks to mutually inverse outputs of the UVC, the proposed filter simultaneously provides both inverting and non-inverting outputs from the same configuration. All of these features make the UVC a unique active device currently available in the literature. The behavior of the filter was experimentally measured using the readily available UVC-N1C 0520 chip, which was produced in cooperation with ON Semiconductor Czech Republic, Ltd.

A multilevel adaptive reaction-splitting method for SRNs

KAUST Repository

Moraes, Alvaro

2015-01-07

In this work, we present a novel multilevel Monte Carlo method for kinetic simulation of stochastic reaction networks specifically designed for systems in which the set of reaction channels can be adaptively partitioned into two subsets characterized by either “high” or “low” activity. To estimate expected values of observables of the system, our method bounds the global computational error to be below a prescribed tolerance, within a given confidence level. This is achieved with a computational complexity of order O (TOL-2).We also present a novel control variate technique which may dramatically reduce the variance of the coarsest level at a negligible computational cost. Our numerical examples show substantial gains with respect to the standard Stochastic Simulation Algorithm (SSA) by Gillespie and also our previous hybrid Chernoff tau-leap method.

Characterizing the continuously acquired cardiovascular time series during hemodialysis, using median hybrid filter preprocessing noise reduction

Directory of Open Access Journals (Sweden)

Wilson S

2015-01-01

Full Text Available Scott Wilson,1,2 Andrea Bowyer,3 Stephen B Harrap4 1Department of Renal Medicine, The Alfred Hospital, 2Baker IDI, Melbourne, 3Department of Anaesthesia, Royal Melbourne Hospital, 4University of Melbourne, Parkville, VIC, Australia Abstract: The clinical characterization of cardiovascular dynamics during hemodialysis (HD has important pathophysiological implications in terms of diagnostic, cardiovascular risk assessment, and treatment efficacy perspectives. Currently the diagnosis of significant intradialytic systolic blood pressure (SBP changes among HD patients is imprecise and opportunistic, reliant upon the presence of hypotensive symptoms in conjunction with coincident but isolated noninvasive brachial cuff blood pressure (NIBP readings. Considering hemodynamic variables as a time series makes a continuous recording approach more desirable than intermittent measures; however, in the clinical environment, the data signal is susceptible to corruption due to both impulsive and Gaussian-type noise. Signal preprocessing is an attractive solution to this problem. Prospectively collected continuous noninvasive SBP data over the short-break intradialytic period in ten patients was preprocessed using a novel median hybrid filter (MHF algorithm and compared with 50 time-coincident pairs of intradialytic NIBP measures from routine HD practice. The median hybrid preprocessing technique for continuously acquired cardiovascular data yielded a dynamic regression without significant noise and artifact, suitable for high-level profiling of time-dependent SBP behavior. Signal accuracy is highly comparable with standard NIBP measurement, with the added clinical benefit of dynamic real-time hemodynamic information. Keywords: continuous monitoring, blood pressure

Novel Family of modified qZS buck-boost multilevel inverters with reduced switch count

DEFF Research Database (Denmark)

Husev, Oleksandr; Strzelecki, Ryszard; Blaabjerg, Frede

2015-01-01

This paper describes a novel family of modified quasi-Z-source buck-boost multilevel inverters with reduced switch count. The inverters are derived by means of the modified inverter configuration with quasi-Z-source networks. The main benefits of the proposed solutions lie in the increased amount...... of levels with all possible sequences: reduced THD, reduced voltage stress on the transistors and size of the output filter. Also their modulation techniques are proposed and described. Simulation results have confirmed all theoretical predictions. The pros and cons are discussed in the conclusions....

Advancing multilevel thinking and methods in HRM research

NARCIS (Netherlands)

Renkema, Maarten; Meijerink, Jeroen Gerard; Bondarouk, Tatiana

2016-01-01

Purpose Despite the growing belief that multilevel research is necessary to advance HRM understanding, there remains a lack of multilevel thinking – the application of principles for multilevel theory building. The purpose of this paper is to propose a systematic approach for multilevel HRM

Truncation correction for oblique filtering lines

International Nuclear Information System (INIS)

Hoppe, Stefan; Hornegger, Joachim; Lauritsch, Guenter; Dennerlein, Frank; Noo, Frederic

2008-01-01

State-of-the-art filtered backprojection (FBP) algorithms often define the filtering operation to be performed along oblique filtering lines in the detector. A limited scan field of view leads to the truncation of those filtering lines, which causes artifacts in the final reconstructed volume. In contrast to the case where filtering is performed solely along the detector rows, no methods are available for the case of oblique filtering lines. In this work, the authors present two novel truncation correction methods which effectively handle data truncation in this case. Method 1 (basic approach) handles data truncation in two successive preprocessing steps by applying a hybrid data extrapolation method, which is a combination of a water cylinder extrapolation and a Gaussian extrapolation. It is independent of any specific reconstruction algorithm. Method 2 (kink approach) uses similar concepts for data extrapolation as the basic approach but needs to be integrated into the reconstruction algorithm. Experiments are presented from simulated data of the FORBILD head phantom, acquired along a partial-circle-plus-arc trajectory. The theoretically exact M-line algorithm is used for reconstruction. Although the discussion is focused on theoretically exact algorithms, the proposed truncation correction methods can be applied to any FBP algorithm that exposes oblique filtering lines.

Energetic particle parallel diffusion in a cascading wave turbulence in the foreshock region

Directory of Open Access Journals (Sweden)

F. Otsuka

2007-09-01

Full Text Available We study parallel (field-aligned diffusion of energetic particles in the upstream of the bow shock with test particle simulations. We assume parallel shock geometry of the bow shock, and that MHD wave turbulence convected by the solar wind toward the shock is purely transverse in one-dimensional system with a constant background magnetic field. We use three turbulence models: a homogeneous turbulence, a regular cascade from a large scale to smaller scales, and an inverse cascade from a small scale to larger scales. For the homogeneous model the particle motions along the average field are Brownian motions due to random and isotropic scattering across 90 degree pitch angle. On the other hand, for the two cascade models particle motion is non-Brownian due to coherent and anisotropic pitch angle scattering for finite time scale. The mean free path λ_|| calculated by the ensemble average of these particle motions exhibits dependence on the distance from the shock. It also depends on the parameters such as the thermal velocity of the particles, solar wind flow velocity, and a wave turbulence model. For the inverse cascade model, the dependence of λ_|| at the shock on the thermal energy is consistent with the hybrid simulation done by Giacalone (2004, but the spatial dependence of λ_|| is inconsistent with it.

A hybrid filtering approach for storage optimization in main-memory cloud database

Directory of Open Access Journals (Sweden)

Ghada M. Afify

2015-11-01

Full Text Available Enterprises and cloud service providers face dramatic increase in the amount of data stored in private and public clouds. Thus, data storage costs are growing hastily because they use only one single high-performance storage tier for storing all cloud data. There’s considerable potential to reduce cloud costs by classifying data into active (hot and inactive (cold. In the main-memory databases research, recent works focus on approaches to identify hot/cold data. Most of these approaches track tuple accesses to identify hot/cold tuples. In contrast, we introduce a novel Hybrid Filtering Approach (HFA that tracks both tuples and columns accesses in main-memory databases. Our objective is to enhance the performance in terms of three dimensions: storage space, query elapsed time and CPU time. In order to validate the effectiveness of our approach, we realized its concrete implementation on Hekaton, a SQL’s server memory-optimized engine using the well-known TPC-H benchmark. Experimental results show that the proposed HFA outperforms Hekaton approach in respect of all performance dimensions. In specific, HFA reduces the storage space by average of 44–96%, reduces the query elapsed time by average of 25–93% and reduces the CPU time by average of 31–97% compared to the traditional database approach.

A high temperature superconductor notch filter for the Sardinia Radio Telescope

Science.gov (United States)

Bolli, Pietro; Cresci, Luca; Huang, Frederick; Mariotti, Sergio; Panella, Dario

2018-04-01

A High Temperature Superconductor filter operating in the C-band between 4200 and 5600 MHz has been developed for one of the radio astronomical receivers of the Sardinia Radio Telescope. The motivation was to attenuate an interference from a weather radar at 5640 MHz, whose power level exceeds the linear region of the first active stages of the receiver. A very sharp transition after the nominal maximum passband frequency is reached by combining a 6th order band-pass filter with a 6th order stop-band. This solution is competitive with an alternative layout based on a cascaded triplet filter. Three units of the filter have been measured with two different calibration approaches to investigate pros and cons of each, and data repeatability. The final performance figures of the filters are: ohmic losses of the order of 0.15-0.25 dB, matching better than -15 dB, and -30 dB attenuation at 5640 MHz. Finally, a more accurate model of the connection between external connector and microstrip shows a better agreement between simulations and experimental data.

Mechanisms of cascade collapse

International Nuclear Information System (INIS)

Diaz de la Rubia, T.; Smalinskas, K.; Averback, R.S.; Robertson, I.M.; Hseih, H.; Benedek, R.

1988-12-01

The spontaneous collapse of energetic displacement cascades in metals into vacancy dislocation loops has been investigated by molecular dynamics (MD) computer simulation and transmission electron microscopy (TEM). Simulations of 5 keV recoil events in Cu and Ni provide the following scenario of cascade collapse: atoms are ejected from the central region of the cascade by replacement collision sequences; the central region subsequently melts; vacancies are driven to the center of the cascade during resolidification where they may collapse into loops. Whether or not collapse occurs depends critically on the melting temperature of the metal and the energy density and total energy in the cascade. Results of TEM are presented in support of this mechanism. 14 refs., 4 figs., 1 tab

Short-term cascaded hydroelectric system scheduling based on chaotic particle swarm optimization using improved logistic map

Science.gov (United States)

He, Yaoyao; Yang, Shanlin; Xu, Qifa

2013-07-01

In order to solve the model of short-term cascaded hydroelectric system scheduling, a novel chaotic particle swarm optimization (CPSO) algorithm using improved logistic map is introduced, which uses the water discharge as the decision variables combined with the death penalty function. According to the principle of maximum power generation, the proposed approach makes use of the ergodicity, symmetry and stochastic property of improved logistic chaotic map for enhancing the performance of particle swarm optimization (PSO) algorithm. The new hybrid method has been examined and tested on two test functions and a practical cascaded hydroelectric system. The experimental results show that the effectiveness and robustness of the proposed CPSO algorithm in comparison with other traditional algorithms.

Multirate Digital Filters Based on FPGA and Its Applications

International Nuclear Information System (INIS)

Sharaf El-Din, R.M.A.

2013-01-01

Digital Signal Processing (DSP) is one of the fastest growing techniques in the electronics industry. It is used in a wide range of application fields such as, telecommunications, data communications, image enhancement and processing, video signals, digital TV broadcasting, and voice synthesis and recognition. Field Programmable Gate Array (FPGA) offers good solution for addressing the needs of high performance DSP systems. The focus of this thesis is on one of the basic DSP functions, namely filtering signals to remove unwanted frequency bands. Multi rate Digital Filters (MDFs) are the main theme here. Theory and implementation of MDF, as a special class of digital filters, will be discussed. Multi rate digital filters represent a class of digital filters having a number of attractive features like, low requirements for the coefficient word lengths, significant saving in computation and storage requirements results in a significant reduction in its dynamic power consumption. This thesis introduces an efficient FPGA realization of a multi rate decimation filter with narrow pass-band and narrow transition band to reduce the frequency sample rate by factor of 64 for noise thermometer applications. The proposed multi rate decimation filter is composed of three stages; the first stage is a Cascaded Integrator Comb (CIC) decimation filter, the second stage is a two-coefficient Half-Band (HB) filter and the last stage is a sharper transition HB filter. The frequency responses of individual stages as well as the overall filter response have been demonstrated with full simulation using MATLAB. The design and implementation of the proposed MDF on FPGA (XILINX Virtex XCV800 BG432-4), using VHSIC Hardware Description Language (VHDL), has been introduced. The implementation areas of the proposed filter stages are compared. Using CIC-HB technique saves 18% of the design area, compared to using six stages HB decimation filters.

Multi-level damage identification with response reconstruction

Science.gov (United States)

Zhang, Chao-Dong; Xu, You-Lin

2017-10-01

Damage identification through finite element (FE) model updating usually forms an inverse problem. Solving the inverse identification problem for complex civil structures is very challenging since the dimension of potential damage parameters in a complex civil structure is often very large. Aside from enormous computation efforts needed in iterative updating, the ill-condition and non-global identifiability features of the inverse problem probably hinder the realization of model updating based damage identification for large civil structures. Following a divide-and-conquer strategy, a multi-level damage identification method is proposed in this paper. The entire structure is decomposed into several manageable substructures and each substructure is further condensed as a macro element using the component mode synthesis (CMS) technique. The damage identification is performed at two levels: the first is at macro element level to locate the potentially damaged region and the second is over the suspicious substructures to further locate as well as quantify the damage severity. In each level's identification, the damage searching space over which model updating is performed is notably narrowed down, not only reducing the computation amount but also increasing the damage identifiability. Besides, the Kalman filter-based response reconstruction is performed at the second level to reconstruct the response of the suspicious substructure for exact damage quantification. Numerical studies and laboratory tests are both conducted on a simply supported overhanging steel beam for conceptual verification. The results demonstrate that the proposed multi-level damage identification via response reconstruction does improve the identification accuracy of damage localization and quantization considerably.

Panel Data with Cross-Sectional Dependence Characterized by a Multi-Level Factor Structure

DEFF Research Database (Denmark)

Rodríguez-Caballero, Carlos Vladimir

A panel data model with a multi-level cross-sectional dependence is proposed. The factor structure is driven by top-level common factors as well as non-pervasive factors. I propose a simple method to filter out the full factor structure that overcomes limitations in standard procedures which may...... mix up both levels of unobservable factors and may hamper the identification of the model. The model covers both stationary and non-stationary cases and takes into account other relevant features that make the model well suited to the analysis of many types of time series frequently addressed...

Cascade ultrafiltering of 210Pb and 210Po in freshwater using a tangential flow filtering system

International Nuclear Information System (INIS)

Ohtsuka, Y.; Takaku, Y.; Hisamatsu, S.; Inaba, J.; Yamamoto, M.

2006-01-01

A rapid method was developed using ultrafilters with a tangential flow filtering system for molecular size separation of naturally occurring 210 Pb and 210 Po in a freshwater sample. Generally, ultrafiltering of a large volume water sample for measuring the nuclides was too time consuming and not practical. The tangential flow filtering system made the filtering time short enough to adapt for in-situ ultrafiltering the large volume sample. In this method, a 20 liter water sample was at first passed through the 0.45 μm pore size membrane filter immediately after sample collection to obtain suspended particle matter [>0.45 μm particulate fraction (PRT)]. Two ultrafilters (Millipore Pellicon 2 R ) were used sequentially. The nuclides in the filtrate were separated into three fractions: high molecular mass (100 kDa-0.45μm; HMM), low molecular mass (10 k-100 kDa; LMM) and ionic ( 210 Pb and 210 Po in an oligotrophic lake, Lake Towada located in the northern area of Japan. (author)

Learning optimal embedded cascades.

Science.gov (United States)

Saberian, Mohammad Javad; Vasconcelos, Nuno

2012-10-01

The problem of automatic and optimal design of embedded object detector cascades is considered. Two main challenges are identified: optimization of the cascade configuration and optimization of individual cascade stages, so as to achieve the best tradeoff between classification accuracy and speed, under a detection rate constraint. Two novel boosting algorithms are proposed to address these problems. The first, RCBoost, formulates boosting as a constrained optimization problem which is solved with a barrier penalty method. The constraint is the target detection rate, which is met at all iterations of the boosting process. This enables the design of embedded cascades of known configuration without extensive cross validation or heuristics. The second, ECBoost, searches over cascade configurations to achieve the optimal tradeoff between classification risk and speed. The two algorithms are combined into an overall boosting procedure, RCECBoost, which optimizes both the cascade configuration and its stages under a detection rate constraint, in a fully automated manner. Extensive experiments in face, car, pedestrian, and panda detection show that the resulting detectors achieve an accuracy versus speed tradeoff superior to those of previous methods.

Multilevel marketing společnosti Amway

OpenAIRE

Drozdková, Markéta

2010-01-01

This thesis analyses effectiveness and principles of multilevel marketing as a possible way of selling products and services. Theoretical part describes basis of marketing and direct selling, which is the basis of multilevel marketing. The thesis also states illegal forms of selling that misuse the advantages of multilevel marketing. Pracical part applies gained knowledge on Amway corporation and it atteds to operation of the company, which is evaluated by SWOT analysis.

Fading Kalman filter-based real-time state of charge estimation in LiFePO_4 battery-powered electric vehicles

International Nuclear Information System (INIS)

Lim, KaiChin; Bastawrous, Hany Ayad; Duong, Van-Huan; See, Khay Wai; Zhang, Peng; Dou, Shi Xue

2016-01-01

Highlights: • Real-time battery model parameters and SoC estimation with novel method is proposed. • Cascading filtering stages are used for parameters identification and SoC estimation. • Optimized fading Kalman filter is implemented for SoC estimation. • Accurate SoC estimation is validated in UDDS load profile experiment. • This approach is suitable for BMS in EV applications due to its simplicity. - Abstract: A novel online estimation technique for estimating the state of charge (SoC) of a lithium iron phosphate (LiFePO_4) battery has been developed. Based on a simplified model, the open circuit voltage (OCV) of the battery is estimated through two cascaded linear filtering stages. A recursive least squares filter is employed in the first stage to dynamically estimate the battery model parameters in real-time, and then, a fading Kalman filter (FKF) is used to estimate the OCV from these parameters. FKF can avoid the possibility of large estimation errors, which may occur with a conventional Kalman filter, due to its capability to compensate any modeling error through a fading factor. By optimizing the value of the fading factor in the set of recursion equations of FKF with genetic algorithms, the errors in estimating the battery’s SoC in urban dynamometer driving schedules-based experiments and real vehicle driving cycle experiments were below 3% compared to more than 9% in the case of using an ordinary Kalman filter. The proposed method with its simplified model provides the simplicity and feasibility required for real-time application with highly accurate SoC estimation.

Single DV-DXCCII Based Voltage Controlled First Order All-pass Filter with Inverting and Non-inverting responses

Directory of Open Access Journals (Sweden)

B Chaturvedi

2015-12-01

Full Text Available In this paper, a new voltage controlled first order all-pass filter is presented. The proposed circuit employs a single differential voltage dual-X second generation current conveyor (DV-DXCCII and a grounded capacitor only. The proposed all-pass filter provides both inverting and non inverting voltage-mode outputs from the same configuration simultaneously without any matching condition. Non-ideal analysis along with sensitivity analysis is also investigated. The proposed circuit has low active and passive sensitivities. As an application the proposed all-pass filter is connected in cascade to get higher order filter. The theoretical results are validated thorough PSPICE simulations using TSMC 0.18µm CMOS process parameters.

An Efficient Recommendation Filter Model on Smart Home Big Data Analytics for Enhanced Living Environments

Science.gov (United States)

Chen, Hao; Xie, Xiaoyun; Shu, Wanneng; Xiong, Naixue

2016-01-01

With the rapid growth of wireless sensor applications, the user interfaces and configurations of smart homes have become so complicated and inflexible that users usually have to spend a great amount of time studying them and adapting to their expected operation. In order to improve user experience, a weighted hybrid recommender system based on a Kalman Filter model is proposed to predict what users might want to do next, especially when users are located in a smart home with an enhanced living environment. Specifically, a weight hybridization method was introduced, which combines contextual collaborative filter and the contextual content-based recommendations. This method inherits the advantages of the optimum regression and the stability features of the proposed adaptive Kalman Filter model, and it can predict and revise the weight of each system component dynamically. Experimental results show that the hybrid recommender system can optimize the distribution of weights of each component, and achieve more reasonable recall and precision rates. PMID:27754456

An Efficient Recommendation Filter Model on Smart Home Big Data Analytics for Enhanced Living Environments

Directory of Open Access Journals (Sweden)

Hao Chen

2016-10-01

Full Text Available With the rapid growth of wireless sensor applications, the user interfaces and configurations of smart homes have become so complicated and inflexible that users usually have to spend a great amount of time studying them and adapting to their expected operation. In order to improve user experience, a weighted hybrid recommender system based on a Kalman Filter model is proposed to predict what users might want to do next, especially when users are located in a smart home with an enhanced living environment. Specifically, a weight hybridization method was introduced, which combines contextual collaborative filter and the contextual content-based recommendations. This method inherits the advantages of the optimum regression and the stability features of the proposed adaptive Kalman Filter model, and it can predict and revise the weight of each system component dynamically. Experimental results show that the hybrid recommender system can optimize the distribution of weights of each component, and achieve more reasonable recall and precision rates.

An Efficient Recommendation Filter Model on Smart Home Big Data Analytics for Enhanced Living Environments.

Science.gov (United States)

Chen, Hao; Xie, Xiaoyun; Shu, Wanneng; Xiong, Naixue

2016-10-15

With the rapid growth of wireless sensor applications, the user interfaces and configurations of smart homes have become so complicated and inflexible that users usually have to spend a great amount of time studying them and adapting to their expected operation. In order to improve user experience, a weighted hybrid recommender system based on a Kalman Filter model is proposed to predict what users might want to do next, especially when users are located in a smart home with an enhanced living environment. Specifically, a weight hybridization method was introduced, which combines contextual collaborative filter and the contextual content-based recommendations. This method inherits the advantages of the optimum regression and the stability features of the proposed adaptive Kalman Filter model, and it can predict and revise the weight of each system component dynamically. Experimental results show that the hybrid recommender system can optimize the distribution of weights of each component, and achieve more reasonable recall and precision rates.

Hybrid-Source Impedance Networks

DEFF Research Database (Denmark)

Li, Ding; Gao, Feng; Loh, Poh Chiang

2010-01-01

Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... for current-type inverters. These impedance networks can in principle be combined into two generic network entities, before multiple of them can further be connected together by applying any of the two proposed generalized cascading concepts. The resulting two-level and three-level inverters implemented using...

Modeling of cascade and sub-cascade formation at high PKA energies in irradiated fusion structural materials

International Nuclear Information System (INIS)

Ryazanov, A.I.; Metelkin, E.V.; Semenov, E.V.

2009-01-01

A new theoretical model is developed for the investigations of cascade and sub-cascade formation in fusion structural materials under fast neutron irradiation at high primary knock-on atom energies. Light fusion structural materials: such as Be, C and SiC under 14 MeV neutron irradiation in fusion reactor will have the primary knock-on atoms with the energies up to 1 MeV. It is very difficult to use at such high energies the Monte-Carlo or molecular dynamic simulations [H.L. Heinisch, B.N. Singh, Philos. Mag. A67 (1993) 407; H.L. Heinisch, B.N. Singh, J. Nucl. Mater. 251 (1997) 77]. The developed model is based on the analytical consideration of elastic collisions between displaced moving atoms produced by primary knock-on atoms with some kinetic energies obtained from fast neutrons and crystal lattice atoms. The Thomas-Fermi interaction potential is used here for the description of these elastic atomic collisions. The suggested model takes into account also the electronic losses for moving atoms between elastic collisions. The self-consistent criterion for sub-cascade formation is suggested here which is based on the comparison of mean distance of primary knock-on atoms between consequent collisions of them with the target atoms and a size of sub-cascade produced by moving secondary knock-on atoms produced in such collisions. The analytical relations for the most important characteristics of cascades and sub-cascades are determined including the average number of sub-cascades per one primary knock-on atom in the dependence on its energy, the distance between sub-cascades and the average cascade and sub-cascade sizes. The developed model allows determining the total numbers, distribution functions of cascades and sub-cascades in dependence on their sizes and generation rate of cascades and sub-cascades for the different fusion neutron energy spectra. On the basis of this developed model the numerical calculations for main characteristics of cascades and sub-cascades

A Container-based Trusted Multi-level Security Mechanism

Directory of Open Access Journals (Sweden)

Li Xiao-Yong

2017-01-01

Full Text Available Multi-level security mechanism has been widely applied in the military, government, defense and other domains in which information is required to be divided by security-level. Through this type of security mechanism, users at different security levels are provided with information at corresponding security levels. Traditional multi-level security mechanism which depends on the safety of operating system finally proved to be not practical. We propose a container-based trusted multi-level security mechanism in this paper to improve the applicability of the multi-level mechanism. It guarantees multi-level security of the system through a set of multi-level security policy rules and trusted techniques. The technical feasibility and application scenarios are also discussed. The ease of realization, strong practical significance and low cost of our method will largely expand the application of multi-level security mechanism in real life.

Full Gradient Solution to Adaptive Hybrid Control

Science.gov (United States)

Bean, Jacob; Schiller, Noah H.; Fuller, Chris

2017-01-01

This paper focuses on the adaptation mechanisms in adaptive hybrid controllers. Most adaptive hybrid controllers update two filters individually according to the filtered reference least mean squares (FxLMS) algorithm. Because this algorithm was derived for feedforward control, it does not take into account the presence of a feedback loop in the gradient calculation. This paper provides a derivation of the proper weight vector gradient for hybrid (or feedback) controllers that takes into account the presence of feedback. In this formulation, a single weight vector is updated rather than two individually. An internal model structure is assumed for the feedback part of the controller. The full gradient is equivalent to that used in the standard FxLMS algorithm with the addition of a recursive term that is a function of the modeling error. Some simulations are provided to highlight the advantages of using the full gradient in the weight vector update rather than the approximation.

High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities.

Science.gov (United States)

Zhang, Xiangao; Shao, Mingzhen; Zeng, Xiaoqi

2016-10-18

In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly. Furthermore, by modulating the geometrical parameters appropriately, Fano resonances with high sensitivities to the changes in refractive index can be realized. A maximum figure of merit (FoM) value of 74.3 is obtained. Considerable applications for this work can be found in bio/chemical sensors with excellent performance and other nanophotonic integrated circuit devices such as optical filters, switches and modulators.

High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities

Directory of Open Access Journals (Sweden)

Xiangao Zhang

2016-10-01

Full Text Available In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly. Furthermore, by modulating the geometrical parameters appropriately, Fano resonances with high sensitivities to the changes in refractive index can be realized. A maximum figure of merit (FoM value of 74.3 is obtained. Considerable applications for this work can be found in bio/chemical sensors with excellent performance and other nanophotonic integrated circuit devices such as optical filters, switches and modulators.

Comparison of Field Measurements and EMT Simulation Results on a Multi-Level STATCOM for Grid Integration of London Array Wind Farm

DEFF Research Database (Denmark)

Glasdam, Jakob Bærholm; Kocewiak, Lukasz; Hjerrild, Jesper

2014-01-01

of the evaluation of the simulation models of the OWPP components. The purpose of this paper is to develop and validate an electromagnetic transient (EMT) generic model of the modular multi-level cascaded converter (MMCC) STATCOM based on comparison with field measurements. For this purpose, measurement data have...... been acquired on a commercial ±50 MVAr state-of-the-art (SOA) MMCC STATCOM. The STATCOM is located at the point of common connection (PCC) at the world’s largest OWPP, London Array (LAOWPP). According to the authors’ knowledge, the presented paper will be the first of its kind to compare a detailed...

Hybrid Approach To Steganography System Based On Quantum Encryption And Chaos Algorithms

Directory of Open Access Journals (Sweden)

ZAID A. ABOD

2018-01-01

Full Text Available A hybrid scheme for secretly embedding image into a dithered multilevel image is presented. This work inputs both a cover image and secret image, which are scrambling and divided into groups to embedded together based on multiple chaos algorithms (Lorenz map, Henon map and Logistic map respectively. Finally, encrypt the embedded images by using one of the quantum cryptography mechanisms, which is quantum one time pad. The experimental results show that the proposed hybrid system successfully embedded images and combine with the quantum cryptography algorithms and gives high efficiency for secure communication.

Multiscale infrared and visible image fusion using gradient domain guided image filtering

Science.gov (United States)

Zhu, Jin; Jin, Weiqi; Li, Li; Han, Zhenghao; Wang, Xia

2018-03-01

For better surveillance with infrared and visible imaging, a novel hybrid multiscale decomposition fusion method using gradient domain guided image filtering (HMSD-GDGF) is proposed in this study. In this method, hybrid multiscale decomposition with guided image filtering and gradient domain guided image filtering of source images are first applied before the weight maps of each scale are obtained using a saliency detection technology and filtering means with three different fusion rules at different scales. The three types of fusion rules are for small-scale detail level, large-scale detail level, and base level. Finally, the target becomes more salient and can be more easily detected in the fusion result, with the detail information of the scene being fully displayed. After analyzing the experimental comparisons with state-of-the-art fusion methods, the HMSD-GDGF method has obvious advantages in fidelity of salient information (including structural similarity, brightness, and contrast), preservation of edge features, and human visual perception. Therefore, visual effects can be improved by using the proposed HMSD-GDGF method.

Multi-Level iterative methods in computational plasma physics

International Nuclear Information System (INIS)

Knoll, D.A.; Barnes, D.C.; Brackbill, J.U.; Chacon, L.; Lapenta, G.

1999-01-01

Plasma physics phenomena occur on a wide range of spatial scales and on a wide range of time scales. When attempting to model plasma physics problems numerically the authors are inevitably faced with the need for both fine spatial resolution (fine grids) and implicit time integration methods. Fine grids can tax the efficiency of iterative methods and large time steps can challenge the robustness of iterative methods. To meet these challenges they are developing a hybrid approach where multigrid methods are used as preconditioners to Krylov subspace based iterative methods such as conjugate gradients or GMRES. For nonlinear problems they apply multigrid preconditioning to a matrix-few Newton-GMRES method. Results are presented for application of these multilevel iterative methods to the field solves in implicit moment method PIC, multidimensional nonlinear Fokker-Planck problems, and their initial efforts in particle MHD

Cascade annealing: an overview

International Nuclear Information System (INIS)

Doran, D.G.; Schiffgens, J.O.

1976-04-01

Concepts and an overview of radiation displacement damage modeling and annealing kinetics are presented. Short-term annealing methodology is described and results of annealing simulations performed on damage cascades generated using the Marlowe and Cascade programs are included. Observations concerning the inconsistencies and inadequacies of current methods are presented along with simulation of high energy cascades and simulation of longer-term annealing

Multilevel Workflow System in the ATLAS Experiment

CERN Document Server

Borodin, M; The ATLAS collaboration; Golubkov, D; Klimentov, A; Maeno, T; Vaniachine, A

2015-01-01

The ATLAS experiment is scaling up Big Data processing for the next LHC run using a multilevel workflow system comprised of many layers. In Big Data processing ATLAS deals with datasets, not individual files. Similarly a task (comprised of many jobs) has become a unit of the ATLAS workflow in distributed computing, with about 0.8M tasks processed per year. In order to manage the diversity of LHC physics (exceeding 35K physics samples per year), the individual data processing tasks are organized into workflows. For example, the Monte Carlo workflow is composed of many steps: generate or configure hard-processes, hadronize signal and minimum-bias (pileup) events, simulate energy deposition in the ATLAS detector, digitize electronics response, simulate triggers, reconstruct data, convert the reconstructed data into ROOT ntuples for physics analysis, etc. Outputs are merged and/or filtered as necessary to optimize the chain. The bi-level workflow manager - ProdSys2 - generates actual workflow tasks and their jobs...

Kalman filter data assimilation: targeting observations and parameter estimation.

Science.gov (United States)

Bellsky, Thomas; Kostelich, Eric J; Mahalov, Alex

2014-06-01

This paper studies the effect of targeted observations on state and parameter estimates determined with Kalman filter data assimilation (DA) techniques. We first provide an analytical result demonstrating that targeting observations within the Kalman filter for a linear model can significantly reduce state estimation error as opposed to fixed or randomly located observations. We next conduct observing system simulation experiments for a chaotic model of meteorological interest, where we demonstrate that the local ensemble transform Kalman filter (LETKF) with targeted observations based on largest ensemble variance is skillful in providing more accurate state estimates than the LETKF with randomly located observations. Additionally, we find that a hybrid ensemble Kalman filter parameter estimation method accurately updates model parameters within the targeted observation context to further improve state estimation.

Kalman filter data assimilation: Targeting observations and parameter estimation

International Nuclear Information System (INIS)

Bellsky, Thomas; Kostelich, Eric J.; Mahalov, Alex

2014-01-01

This paper studies the effect of targeted observations on state and parameter estimates determined with Kalman filter data assimilation (DA) techniques. We first provide an analytical result demonstrating that targeting observations within the Kalman filter for a linear model can significantly reduce state estimation error as opposed to fixed or randomly located observations. We next conduct observing system simulation experiments for a chaotic model of meteorological interest, where we demonstrate that the local ensemble transform Kalman filter (LETKF) with targeted observations based on largest ensemble variance is skillful in providing more accurate state estimates than the LETKF with randomly located observations. Additionally, we find that a hybrid ensemble Kalman filter parameter estimation method accurately updates model parameters within the targeted observation context to further improve state estimation

ADielectric Multilayer Filter for Combining Photovoltaics with a Stirling Engine for Improvement of the Efficiency of Solar Electricity Generation

Institute of Scientific and Technical Information of China (English)

寿春晖; 骆仲泱; 王涛; 沈伟东; ROSENGARTEN Gary; 王诚; 倪明江; 岑可法

2011-01-01

In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications. The optical performance of this 78-layer interference filter constructed by TiOx and SiO2 is presented. A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed. The calculated results show the advantages of this spectrally selective method for solar power generation.%In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications.The optical performance of this 78-layer interference filter constructed by TiOx and SiO2 is presented.A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed.The calculated results show the advantages of this spectrally selective method for solar power generation.

Integrated Broadband Quantum Cascade Laser

Science.gov (United States)

Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

2016-01-01

A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

Voltage harmonics mitigation through hybrid active power filer

International Nuclear Information System (INIS)

Sahito, A.A.; Tunio, S.M.; Khizer, A.N.

2016-01-01

Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion) of 18.91 and 7.61 percentage in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter) is proposed to reduce these THD values below 5 percentage as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5 percentage. (author)

Multi-Level Secure Local Area Network

OpenAIRE

Naval Postgraduate School (U.S.); Center for Information Systems Studies Security and Research (CISR)

2011-01-01

Multi-Level Secure Local Area Network is a cost effective, multi-level, easy to use office environment leveraging existing high assurance technology. The Department of Defense and U.S. Government have an identified need to securely share information classified at differing security levels. Because there exist no commercial solutions to this problem, NPS is developing a MLS LAN. The MLS LAN extends high assurance capabilities of an evaluated multi-level secure system to commercial personal com...

Comparative study of microcontroller controlled four-wire voltage and current source shunt active power filters

Energy Technology Data Exchange (ETDEWEB)

Pettersson, S.

2009-07-01

During the past two decades, active power filters have increasingly grown their popularity as a viable method for improving electric power quality. The main reasons for this have been the advent of fast self-commutating solid-state devices, the progression of digital technology and the improved sensor technology. Four-wire active power filters provide an efficient solution for improving the quality of supply in grounded three-phase systems or three-phase systems with neutral conductors, which are commonly used for powering residential, office and public buildings. Four-wire active power filters are applicable in compensating current harmonics, reactive power, neutral current and load phase imbalance.This thesis presents a comparative study of microcontroller controlled four-wire voltage and current source shunt active power filters. The study includes two voltage source topologies and a current source topology with two different dc-link energy storage structures, which are compared on the basis of their filtering properties, filtering performance and efficiency. The obtained results are used for determining the suitability of current source technology for four-wire active power filtering and finding the most viable four-wire shunt active power filter topology. One commonly recognized disadvantage of the current source active power filter has always been the bulky dc-link inductor. To reduce the size of the dc-link inductor, an alternative dc-link structure for current source active power filters was introduced in the late 80's. The hybrid energy storage consists of both inductive and capacitive energy storage elements, two diodes and two controllable semiconductor switching devices. Since the capacitive element is used as a main storage unit, the inductance of the dc-link inductor can be considerably reduced. However, the original dc current control method proposed is not able to utilize the full potential of the hybrid energy storage and the inductance

Hybrid winding concept for toroids

DEFF Research Database (Denmark)

Schneider, Henrik; Andersen, Thomas; Knott, Arnold

2013-01-01

and placement machinery. This opens up the possibility for both an automated manufacturing process and an automated production process of toroidal magnetics such as power inductors, filtering inductors, air core inductors, transformers etc. Both the proposed hybrid and the common wire wound winding...

Multilevel parallel strategy on Monte Carlo particle transport for the large-scale full-core pin-by-pin simulations

International Nuclear Information System (INIS)

Zhang, B.; Li, G.; Wang, W.; Shangguan, D.; Deng, L.

2015-01-01

This paper introduces the Strategy of multilevel hybrid parallelism of JCOGIN Infrastructure on Monte Carlo Particle Transport for the large-scale full-core pin-by-pin simulations. The particle parallelism, domain decomposition parallelism and MPI/OpenMP parallelism are designed and implemented. By the testing, JMCT presents the parallel scalability of JCOGIN, which reaches the parallel efficiency 80% on 120,000 cores for the pin-by-pin computation of the BEAVRS benchmark. (author)

Modeling, Development and Control of Multilevel Converters for Power System Application =

Science.gov (United States)

Vahedi, Hani

The main goal of this project is to develop a multilevel converter topology to be useful in power system applications. Although many topologies are introduced rapidly using a bunch of switches and isolated dc sources, having a single-dc-source multilevel inverter is still a matter of controversy. In fact, each isolated dc source means a bulky transformer and a rectifier that have their own losses and costs forcing the industries to avoid entering in this topic conveniently. On the other hand, multilevel inverters topologies with single-dc-source require associated controllers to regulate the dc capacitors voltages in order to have multilevel voltage waveform at the output. Thus, a complex controller would not interest investors properly. Consequently, developing a single-dc-source multilevel inverter topology along with a light and reliable voltage control is still a challenging topic to replace the 2-level inverters in the market effectively. The first effort in this project was devoted to the PUC7 inverter to design a simple and yet efficient controller. A new modelling is performed on the PUC7 inverter and it has been simplified to first order system. Afterwards, a nonlinear cascaded controller is designed and applied to regulate the capacitor voltage at 1/3 of the DC source amplitude and to generate 7 identical voltage levels at the output supplying different type of loads such as RL or rectifier harmonic ones. In next work, the PUC5 topology is proposed as a remedy to the PUC7 that requires a complicated controller to operate properly. The capacitor voltage is regulated at half of dc source amplitude to generate 5 voltage levels at the output. Although the 7-level voltage waveform is replaced by a 5-level one in PUC5 topology, it is shown that the PUC5 needs a very simple and reliable voltage balancing technique due to having some redundant switching states. Moreover, a sensor-less voltage balancing technique is designed and implemented on the PUC5 inverter

Modeling Multi-Level Systems

CERN Document Server

Iordache, Octavian

2011-01-01

This book is devoted to modeling of multi-level complex systems, a challenging domain for engineers, researchers and entrepreneurs, confronted with the transition from learning and adaptability to evolvability and autonomy for technologies, devices and problem solving methods. Chapter 1 introduces the multi-scale and multi-level systems and highlights their presence in different domains of science and technology. Methodologies as, random systems, non-Archimedean analysis, category theory and specific techniques as model categorification and integrative closure, are presented in chapter 2. Chapters 3 and 4 describe polystochastic models, PSM, and their developments. Categorical formulation of integrative closure offers the general PSM framework which serves as a flexible guideline for a large variety of multi-level modeling problems. Focusing on chemical engineering, pharmaceutical and environmental case studies, the chapters 5 to 8 analyze mixing, turbulent dispersion and entropy production for multi-scale sy...

Conjugation of cascades

International Nuclear Information System (INIS)

San Martin, Jesus; Rodriguez-Perez, Daniel

2009-01-01

Presented in this work are some results relative to sequences found in the logistic equation bifurcation diagram, which is the unimodal quadratic map prototype. All of the different saddle-node bifurcation cascades, associated with every last appearance p-periodic orbit (p=3,4,5,...), can also be generated from the very Feigenbaum cascade. In this way it is evidenced the relationship between both cascades. The orbits of every saddle-node bifurcation cascade, mentioned above, are located in different chaotic bands, and this determines a sequence of orbits converging to every band-merging Misiurewicz point. In turn, these accumulation points form a sequence whose accumulation point is the Myrberg-Feigenbaum point. It is also proven that the first appearance orbits in the n-chaotic band converge to the same point as the last appearance orbits of the (n + 1)-chaotic band. The symbolic sequences of band-merging Misiurewicz points are computed for any window.

Computationally efficient video restoration for Nyquist sampled imaging sensors combining an affine-motion-based temporal Kalman filter and adaptive Wiener filter.

Science.gov (United States)

Rucci, Michael; Hardie, Russell C; Barnard, Kenneth J

2014-05-01

In this paper, we present a computationally efficient video restoration algorithm to address both blur and noise for a Nyquist sampled imaging system. The proposed method utilizes a temporal Kalman filter followed by a correlation-model based spatial adaptive Wiener filter (AWF). The Kalman filter employs an affine background motion model and novel process-noise variance estimate. We also propose and demonstrate a new multidelay temporal Kalman filter designed to more robustly treat local motion. The AWF is a spatial operation that performs deconvolution and adapts to the spatially varying residual noise left in the Kalman filter stage. In image areas where the temporal Kalman filter is able to provide significant noise reduction, the AWF can be aggressive in its deconvolution. In other areas, where less noise reduction is achieved with the Kalman filter, the AWF balances the deconvolution with spatial noise reduction. In this way, the Kalman filter and AWF work together effectively, but without the computational burden of full joint spatiotemporal processing. We also propose a novel hybrid system that combines a temporal Kalman filter and BM3D processing. To illustrate the efficacy of the proposed methods, we test the algorithms on both simulated imagery and video collected with a visible camera.

Multi-level molecular modelling for plasma medicine

International Nuclear Information System (INIS)

Bogaerts, Annemie; Khosravian, Narjes; Van der Paal, Jonas; Verlackt, Christof C W; Yusupov, Maksudbek; Kamaraj, Balu; Neyts, Erik C

2016-01-01

Modelling at the molecular or atomic scale can be very useful for obtaining a better insight in plasma medicine. This paper gives an overview of different atomic/molecular scale modelling approaches that can be used to study the direct interaction of plasma species with biomolecules or the consequences of these interactions for the biomolecules on a somewhat longer time-scale. These approaches include density functional theory (DFT), density functional based tight binding (DFTB), classical reactive and non-reactive molecular dynamics (MD) and united-atom or coarse-grained MD, as well as hybrid quantum mechanics/molecular mechanics (QM/MM) methods. Specific examples will be given for three important types of biomolecules, present in human cells, i.e. proteins, DNA and phospholipids found in the cell membrane. The results show that each of these modelling approaches has its specific strengths and limitations, and is particularly useful for certain applications. A multi-level approach is therefore most suitable for obtaining a global picture of the plasma–biomolecule interactions. (paper)

Characterization Of Improved Binary Phase-Only Filters In A Real-Time Coherent Optical Correlation System

Science.gov (United States)

Flannery, D.; Keller, P.; Cartwright, S.; Loomis, J.

1987-06-01

Attractive correlation system performance potential is possible using magneto-optic spatial light modulators (SLM) to implement binary phase-only reference filters at high rates, provided the correlation performance of such reduced-information-content filters is adequate for the application. In the case studied here, the desired filter impulse response is a rectangular shape, which cannot be achieved with the usual binary phase-only filter formulation. The correlation application problem is described and techniques for synthesizing improved filter impulse response are considered. A compromise solution involves the cascading of a fixed amplitude-only weighting mask with the binary phase-only SLM. Based on simulations presented, this approach provides improved impulse responses and good correlation performance, while retaining the critical feature of real-time variations of the size, shape, and orientation of the rectangle by electronic programming of the phase pattern in the SLM. Simulations indicate that, for at least one very challenging input scene clutter situation, these filters provide higher correlation signal-to-noise than does "ideal" correlation, i.e. using a perfect rectangle filter response.

General oscillation damping analysis of the L-C filter circuit in the high-power rectifying power supply

International Nuclear Information System (INIS)

Xu Weihua; Chen Yonghao; Wu Junshuan; Kuang Guangli

1998-06-01

Rectifier circuit is the most popular converter. For the ripple demand of high-power load, the L-C filter with invert 'L' type has been used universally. Due to the influence of the second-order link, damped oscillation will occur with proper condition while the circuit state is changed. The ideal cascade damping condition and the parallel one can be obtained easily. Generally, the damping condition of the step response of the L-C filter circuit is induced, and the discussion is given

Design of adaptive filter amplifier in UV communication based on DSP

Science.gov (United States)

Lv, Zhaoshun; Wu, Hanping; Li, Junyu

2016-10-01

According to the problem of the weak signal at receiving end in UV communication, we design a high gain, continuously adjustable adaptive filter amplifier. Based on proposing overall technical indicators and analyzing its working principle of the signal amplifier, we use chip LMH6629MF and two chips of AD797BN to achieve three-level cascade amplification. And apply hardware of DSP TMS320VC5509A to implement digital filtering. Design and verification by Multisim, Protel 99SE and CCS, the results show that: the amplifier can realize continuously adjustable amplification from 1000 to 10000 times without distortion. Magnification error is <=%4@1000 10000. And equivalent input noise voltage of amplification circuit is <=6 nV/ √Hz @30KHz 45KHz, and realizing function of adaptive filtering. The design provides theoretical reference and technical support for the UV weak signal processing.

Invited Article: Narrowband terahertz bandpass filters employing stacked bilayer metasurface antireflection structures

Science.gov (United States)

Chang, Chun-Chieh; Huang, Li; Nogan, John; Chen, Hou-Tong

2018-05-01

We experimentally demonstrate high-performance narrowband terahertz (THz) bandpass filters through cascading multiple bilayer metasurface antireflection structures. Each bilayer metasurface, consisting of a square array of silicon pillars with a self-aligned top gold resonator-array and a complementary bottom gold slot-array, enables near-zero reflection and simultaneously close-to-unity single-band transmission at designed operational frequencies in the THz spectral region. The THz bandpass filters based on stacked bilayer metasurfaces allow a fairly narrow, high-transmission passband, and a fast roll-off to an extremely clean background outside the passband, thereby providing superior bandpass performance. The demonstrated scheme of narrowband THz bandpass filtering is of great importance for a variety of applications where spectrally clean, high THz transmission over a narrow bandwidth is desired, such as THz spectroscopy and imaging, molecular detection and monitoring, security screening, and THz wireless communications.

Trophic structure of the benthic invertebrate community in the littoral zone of a mountain cascade system

Directory of Open Access Journals (Sweden)

M. Prus

2002-02-01

Full Text Available The cascade of Solina/Myczkowce dam reservoirs situated in the West Carpathian Mts was investigated. The cascade consists of two reservoirs, the upper one built 35 yr ago on the San and Solinka Rivers of 2100 ha area separated from another one, of 190 ha area, with hypolimnion cold water supplied from the upper one.

The offshore zone was investigated monthly (6 sites of upper, 3 sites of lower reservoir using a tube bottom sampler. Besides numbers, biomass and biodiversity indices, the proportion of predators, plant/detritus-feeders and filter-feeders was assessed.

In upper reservoir Solina, with a lack of filter-feeders, a clear preponderance of plant-detritus feeders was observed. Predators, consisting mostly of leeches and hydranchnellids were present. In lower reservoir Myczkowce, all three trophic classes were present in the first year of study in almost equal proportions and in 1998 with slight preponderance of plant/detritus feeders was observed.

The Oligochaeta/Chironomidae index in both reservoirs was low, indicating low degree of eutrophication. Only one site in Solina reservoir (near a fish culture and one in Myczkowce (influenced by tourist activity showed a high value of this index.

Multilevel Modulation formats for Optical Communication

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee

2008-01-01

This thesis studies the use of multilevel modulation formats for optical communication systems. Multilevel modulation is an attractive method of increasing the spectral efficiency of optical communication systems. Various modulation formats employing phase modulation, amplitude modulation...... or a combination of the two have been studied. The use of polarization multiplexing (PolMux) to double the bit rate has also been investigated. The impact of transmission impairments such as chromatic dispersion, self phase modulation and cross phase modulation has been investigated. The feasibility of multilevel...... modulation for network oriented scenarios has been demonstrated....

Active flywheel control for hybrid vehicle; Compensation active des pulsations de couple dans un vehicule hybride

Energy Technology Data Exchange (ETDEWEB)

Tnani, S.; Coirault, P.; Champenois, G. [Ecole Superieure d' Ingenieurs, Lab. d' Automatique et d' Informatique Industrielle, 86 - Poitiers (France)

2005-01-01

In the paper, the authors propose a novel control strategy of torque ripple on hybrid vehicle. The combustion engine ripple's are reduced by using an active filter and an AC machine which is mounted on the crank-shaft to generate on inverse torque sequence. The control strategy is based on a multi-objectives state feedback synthesis. A complete modelling of the hybrid propulsion of the vehicle is achieved. Simulation results highlight the interest of the control scheme. (authors)

Energy cascades in Canada

Energy Technology Data Exchange (ETDEWEB)

Hayden, A. C.; Brown, T. D.

1979-03-15

Combining energy uses in a cascade can result in significant overall reductions in fuel requirements. The simplest applications for a cascade are in the recovery of waste heat from existing processes using special boilers or turbines. Specific applications of more-complex energy cascades for Canada are discussed. A combined-cycle plant at a chemical refinery in Ontario is world leader in energy efficiency. Total-energy systems for commercial buildings, such as one installed in a school in Western Canada, offer attractive energy and operating cost benefits. A cogeneration plant proposed for the National Capital Region, generating electricity as well as steam for district heating, allows the use of a low-grade fossil fuel (coal), greatly improves energy-transformation efficiency, and also utilizes an effectively renewable resource (municipal garbage). Despite the widespread availability of equipment and technology of energy cascades, the sale of steam and electricity across plant boundaries presents a barrier. More widespread use of cascades will require increased cooperation among industry, electric utilities and the various levels of government if Canada is to realize the high levels of energy efficiency potential available.

Multilevel index decomposition analysis: Approaches and application

International Nuclear Information System (INIS)

Xu, X.Y.; Ang, B.W.

2014-01-01

With the growing interest in using the technique of index decomposition analysis (IDA) in energy and energy-related emission studies, such as to analyze the impacts of activity structure change or to track economy-wide energy efficiency trends, the conventional single-level IDA may not be able to meet certain needs in policy analysis. In this paper, some limitations of single-level IDA studies which can be addressed through applying multilevel decomposition analysis are discussed. We then introduce and compare two multilevel decomposition procedures, which are referred to as the multilevel-parallel (M-P) model and the multilevel-hierarchical (M-H) model. The former uses a similar decomposition procedure as in the single-level IDA, while the latter uses a stepwise decomposition procedure. Since the stepwise decomposition procedure is new in the IDA literature, the applicability of the popular IDA methods in the M-H model is discussed and cases where modifications are needed are explained. Numerical examples and application studies using the energy consumption data of the US and China are presented. - Highlights: • We discuss the limitations of single-level decomposition in IDA applied to energy study. • We introduce two multilevel decomposition models, study their features and discuss how they can address the limitations. • To extend from single-level to multilevel analysis, necessary modifications to some popular IDA methods are discussed. • We further discuss the practical significance of the multilevel models and present examples and cases to illustrate

Cascade reactor: introduction

International Nuclear Information System (INIS)

Pitts, J.H.

1985-01-01

Cascade is a concept for an ultrasafe, highly efficient, easily built reactor to convert inertial-confinement fusion energy into electrical power. The Cascade design includes a rotating double-cone-shaped chamber in which a moving, 1-m-thick ceramic granular blanket is held against the reactor wall by centrifugal action. The granular material absorbs energy from the fusion reactions. Accomplishments this year associated with Cascade included improvements to simplify chamber design and lower activation. The authors switched from a steel chamber wall to one made from silicon-carbide (SiC) panels held in compression by SiC-fiber/Al-composite tendons that gird the chamber both circumferentially and axially. The authors studies a number of heat-exchanger designs and selected a gravity-flow cascade design with a vacuum on the primary side. This design allows granules leaving the chamber to be transported to the heat exchangers using their own peripheral speed. The granules transfer their thermal energy and return to the chamber gravitationally: no vacuum locks or conveyors are needed

Hybrid Kalman and unscented Kalman filters for INS/GPS integrated system considering constant lever arm effect

Institute of Scientific and Technical Information of China (English)

常国宾; 柳明

2015-01-01

In inertial navigation system (INS) and global positioning system (GPS) integrated system, GPS antennas are usually not located at the same location as the inertial measurement unit (IMU) of the INS, so the lever arm effect exists, which makes the observation equation highly nonlinear. The INS/GPS integration with constant lever arm effect is studied. The position relation of IMU and GPS’s antenna is represented in the earth centered earth fixed frame, while the velocity relation of these two systems is represented in local horizontal frame. Due to the small integration time interval of INS, i.e. 0.1 s in this work, the nonlinearity in the INS error equation is trivial, so the linear INS error model is constructed and addressed by Kalman filter’s prediction step. On the other hand, the high nonlinearity in the observation equation due to lever arm effect is addressed by unscented Kalman filter’s update step to attain higher accuracy and better applicability. Simulation is designed and the performance of the hybrid filter is validated.

Analysis of the efficiency of a hybrid foil tunnel heating system

Science.gov (United States)

Kurpaska, Sławomir; Pedryc, Norbert

2017-10-01

The paper analyzes the efficiency of the hybrid system used to heat the foil tunnel. The tested system was built on the basis of heat gain in a cascade manner. The first step is to heat the water in the storage tank using the solar collectors. The second stage is the use of a heat pump (HP) in order to heat the diaphragm exchangers. The lower HP heat source is a cascade first stage buffer. In the storage tank, diaphragm exchangers used for solar collectors and heat pumps are installed. The research was carried out at a research station located in the University of Agriculture in Cracow. The aim was to perform an analysis of the efficiency of a hybrid system for the heating of a foil tunnel in the months from May to September. The efficiency of the entire hybrid system was calculated as the relation of the effect obtained in reference to the electrical power used to drive the heat pump components (compressor drive, circulation pump), circulation pumps and fans installed in the diaphragm heaters. The resulting effect was the amount of heat supplied to the interior of the object as a result of the internal air being forced through the diaphragm exchangers.

Hybrid Robust Control Law with Disturbance Observer for High-Frequency Response Electro-Hydraulic Servo Loading System

Directory of Open Access Journals (Sweden)

Zhiqing Sheng

2016-04-01

Full Text Available Addressing the simulating issue of the helicopter-manipulating booster aerodynamic load with high-frequency dynamic load superimposed on a large static load, this paper studies the design of the robust controller for the electro-hydraulic loading system to realize the simulation of this kind of load. Firstly, the equivalent linear model of the electro-hydraulic loading system under assumed parameter uncertainty is established. Then, a hybrid control scheme is proposed for the loading system. This control scheme consists of a constant velocity feed-forward compensator, a robust inner loop compensator based on disturbance observer and a robust outer loop feedback controller. The constant velocity compensator eliminates most of the extraneous force at first, and then the double-loop cascade composition control strategy is employed to design the compensated system. The disturbance observer–based inner loop compensator further restrains the disturbances including the remaining extraneous force, and makes the actual plant tracking a nominal model approximately in a certain frequency range. The robust outer loop controller achieves the desired force-tracking performance, and guarantees system robustness in the high frequency region. The optimized low-pass filter Q(s is designed by using the H∞ mixed sensitivity optimization method. The simulation results show that the proposed hybrid control scheme and controller can effectively suppress the extraneous force and improve the robustness of the electro-hydraulic loading system.

Cascade quantum teleportation

Institute of Scientific and Technical Information of China (English)

ZHOU Nan-run; GONG Li-hua; LIU Ye

2006-01-01

In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

Multilevel sequential Monte-Carlo samplers

KAUST Repository

Jasra, Ajay

2016-01-01

Multilevel Monte-Carlo methods provide a powerful computational technique for reducing the computational cost of estimating expectations for a given computational effort. They are particularly relevant for computational problems when approximate distributions are determined via a resolution parameter h, with h=0 giving the theoretical exact distribution (e.g. SDEs or inverse problems with PDEs). The method provides a benefit by coupling samples from successive resolutions, and estimating differences of successive expectations. We develop a methodology that brings Sequential Monte-Carlo (SMC) algorithms within the framework of the Multilevel idea, as SMC provides a natural set-up for coupling samples over different resolutions. We prove that the new algorithm indeed preserves the benefits of the multilevel principle, even if samples at all resolutions are now correlated.

Multilevel sequential Monte-Carlo samplers

KAUST Repository

Jasra, Ajay

2016-01-05

Multilevel Monte-Carlo methods provide a powerful computational technique for reducing the computational cost of estimating expectations for a given computational effort. They are particularly relevant for computational problems when approximate distributions are determined via a resolution parameter h, with h=0 giving the theoretical exact distribution (e.g. SDEs or inverse problems with PDEs). The method provides a benefit by coupling samples from successive resolutions, and estimating differences of successive expectations. We develop a methodology that brings Sequential Monte-Carlo (SMC) algorithms within the framework of the Multilevel idea, as SMC provides a natural set-up for coupling samples over different resolutions. We prove that the new algorithm indeed preserves the benefits of the multilevel principle, even if samples at all resolutions are now correlated.

Cascade theory in isotopic separation processes; Theorie des cascades en separation isotopique

Energy Technology Data Exchange (ETDEWEB)

Agostini, J P

1994-06-01

Three main areas are developed within the scope of this work: - the first one is devoted to fundamentals: separative power, value function, ideal cascade and square cascade. Applications to two main cases are carried out, namely: Study of binary isotopic mix, Study of processes with a small enrichment coefficient. - The second one is devoted to cascade coupling -high-flux coupling (more widely used and better known) as well as low-flux coupling are presented and compared to one another. - The third one is an outlook on problems linked to cascade transients. Those problem are somewhat intricate and their interest lies mainly into two areas: economics where the start-up time may have a large influence on the interests paid during the construction and start-up period, military productions where the start-up time has a direct bearing on the production schedule. (author). 50 figs. 3 annexes. 12 refs. 6 tabs.

New hybrid technique for impulsive noise suppression in OFDM systems

International Nuclear Information System (INIS)

Mirza, A.; Zeb, A.; Sheikh, S.A.

2017-01-01

In this paper, a new hybrid technique employing RS (Reed Solomon) coding and adaptive filter for impulsive noise suppression in OFDM (Orthogonal Frequency Division Multiplexing) systems is presented. Adaptive filter creates a more accurate estimate of the original OFDM signal after impulsive noise cancellation. The residual impulsive noise is further mitigated by RS decoder in the second stage of proposed technique. Three members of adaptive filters family i.e. NLMS (Normalized Least Mean Square) algorithm, RLS (Recursive Least Square) algorithm and Bhagyashri algorithm are tested with RS decoder in the proposed hybrid technique. Furthermore, the results in terms of steady state MSE (Mean Square Error) reduction, BER (Bit Error Rate) improvement and SNR (Signal to Noise Ratio) enhancement confirm the effectiveness of the proposed dual faceted technique when compared with the recently reported techniques in literature. (author)

A functional hybrid memristor crossbar-array/CMOS system for data storage and neuromorphic applications.

Science.gov (United States)

Kim, Kuk-Hwan; Gaba, Siddharth; Wheeler, Dana; Cruz-Albrecht, Jose M; Hussain, Tahir; Srinivasa, Narayan; Lu, Wei

2012-01-11

Crossbar arrays based on two-terminal resistive switches have been proposed as a leading candidate for future memory and logic applications. Here we demonstrate a high-density, fully operational hybrid crossbar/CMOS system composed of a transistor- and diode-less memristor crossbar array vertically integrated on top of a CMOS chip by taking advantage of the intrinsic nonlinear characteristics of the memristor element. The hybrid crossbar/CMOS system can reliably store complex binary and multilevel 1600 pixel bitmap images using a new programming scheme. © 2011 American Chemical Society

Multilevel modelling: Beyond the basic applications.

Science.gov (United States)

Wright, Daniel B; London, Kamala

2009-05-01

Over the last 30 years statistical algorithms have been developed to analyse datasets that have a hierarchical/multilevel structure. Particularly within developmental and educational psychology these techniques have become common where the sample has an obvious hierarchical structure, like pupils nested within a classroom. We describe two areas beyond the basic applications of multilevel modelling that are important to psychology: modelling the covariance structure in longitudinal designs and using generalized linear multilevel modelling as an alternative to methods from signal detection theory (SDT). Detailed code for all analyses is described using packages for the freeware R.

M2 FILTER FOR SPECKLE NOISE SUPPRESSION IN BREAST ULTRASOUND IMAGES

Directory of Open Access Journals (Sweden)

E.S. Samundeeswari

2016-11-01

Full Text Available Breast cancer, commonly found in women is a serious life threatening disease due to its invasive nature. Ultrasound (US imaging method plays an effective role in screening early detection and diagnosis of Breast cancer. Speckle noise generally affects medical ultrasound images and also causes a number of difficulties in identifying the Region of Interest. Suppressing speckle noise is a challenging task as it destroys fine edge details. No specific filter is designed yet to get a noise free BUS image that is contaminated by speckle noise. In this paper M2 filter, a novel hybrid of linear and nonlinear filter is proposed and compared to other spatial filters with 3×3 kernel size. The performance of the proposed M2 filter is measured by statistical quantity parameters like MSE, PSNR and SSI. The experimental analysis clearly shows that the proposed M2 filter outperforms better than other spatial filters by 2% high PSNR values with regards to speckle suppression.

Versatile current-mode universal biquadratic filter using DO-CCIIs

Science.gov (United States)

Chen, Hua-Pin

2013-07-01

In this article, a new three-input and three-output versatile current-mode universal biquadratic filter is proposed. The circuit employs three dual-output current conveyors (DO-CCIIs) as active elements together with three grounded resistors and two grounded capacitors. The proposed configuration exhibits low-input impedance and high-output impedance which is important for easy cascading in the current-mode operations. It can be used as either a single-input and three-output or three-input and two-output circuit. In the operation of single-input and three-output circuit, the lowpass, bandpass and bandreject can be realised simultaneously, while the highpass filtering response can be easily obtained by connecting appropriated output current directly without using addition stages. In the operation of three-input and two-output circuit, all five generic filtering functions can be easily realised by selecting different three input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no component matching conditions or inverting-type input current signals are imposed. All the passive and active sensitivities are low. HSPICE simulation results based on using TSMC 0.18 µm 1P6M CMOS process technology and supply voltages ±0.9 V to verify the theoretical analysis.

A new hybrid-FBP inversion algorithm with inverse distance backprojection weight for CT reconstruction

Energy Technology Data Exchange (ETDEWEB)

Narasimhadhan, A.V.; Rajgopal, Kasi

2011-07-01

This paper presents a new hybrid filtered backprojection (FBP) algorithm for fan-beam and cone-beam scan. The hybrid reconstruction kernel is the sum of the ramp and Hilbert filters. We modify the redundancy weighting function to reduce the inverse square distance weighting in the backprojection to inverse distance weight. The modified weight also eliminates the derivative associated with the Hilbert filter kernel. Thus, the proposed reconstruction algorithm has the advantages of the inverse distance weight in the backprojection. We evaluate the performance of the new algorithm in terms of the magnitude level and uniformity in noise for the fan-beam geometry. The computer simulations show that the spatial resolution is nearly identical to the standard fan-beam ramp filtered algorithm while the noise is spatially uniform and the noise variance is reduced. (orig.)

Estimation method of state-of-charge for lithium-ion battery used in hybrid electric vehicles based on variable structure extended kalman filter

Science.gov (United States)

Sun, Yong; Ma, Zilin; Tang, Gongyou; Chen, Zheng; Zhang, Nong

2016-07-01

Since the main power source of hybrid electric vehicle(HEV) is supplied by the power battery, the predicted performance of power battery, especially the state-of-charge(SOC) estimation has attracted great attention in the area of HEV. However, the value of SOC estimation could not be greatly precise so that the running performance of HEV is greatly affected. A variable structure extended kalman filter(VSEKF)-based estimation method, which could be used to analyze the SOC of lithium-ion battery in the fixed driving condition, is presented. First, the general lower-order battery equivalent circuit model(GLM), which includes column accumulation model, open circuit voltage model and the SOC output model, is established, and the off-line and online model parameters are calculated with hybrid pulse power characteristics(HPPC) test data. Next, a VSEKF estimation method of SOC, which integrates the ampere-hour(Ah) integration method and the extended Kalman filter(EKF) method, is executed with different adaptive weighting coefficients, which are determined according to the different values of open-circuit voltage obtained in the corresponding charging or discharging processes. According to the experimental analysis, the faster convergence speed and more accurate simulating results could be obtained using the VSEKF method in the running performance of HEV. The error rate of SOC estimation with the VSEKF method is focused in the range of 5% to 10% comparing with the range of 20% to 30% using the EKF method and the Ah integration method. In Summary, the accuracy of the SOC estimation in the lithium-ion battery cell and the pack of lithium-ion battery system, which is obtained utilizing the VSEKF method has been significantly improved comparing with the Ah integration method and the EKF method. The VSEKF method utilizing in the SOC estimation in the lithium-ion pack of HEV can be widely used in practical driving conditions.

High-Input Impedance Voltage-Mode Multifunction Filter with Four Grounded Components and Only Two Plus-Type DDCCs

Directory of Open Access Journals (Sweden)

Hua-Pin Chen

2010-01-01

Full Text Available This paper introduces a novel voltage-mode multifunction biquadratic filter with single input and four outputs using two plus-type differential difference current conveyors (DDCCs and four grounded passive components. The filter can realize inverting highpass, inverting bandpass, noninverting lowpass, and noninverting bandpass filter responses, simultaneously. It still maintains the following advantages: (i using grounded capacitors attractive for integration and absorbing shunt parasitic capacitance, (ii using grounded resistors at all X terminals of DDCCs suitable for the variations of filter parameters and absorbing series parasitic resistances at all X terminals of DDCCs, (iii high-input impedance good for cascadability, (iv no need to change the filter topology, (v no need to component-matching conditions, (vi low active and passive sensitivity performances, and (vii simpler configuration due to the use of plus-type DDCCs only. HSPICE and MATLAB simulations results are provided to demonstrate the theoretical analysis.

Design and optimization of cascaded DCG based holographic elements for spectrum-splitting PV systems

Science.gov (United States)

Wu, Yuechen; Chrysler, Benjamin; Pelaez, Silvana Ayala; Kostuk, Raymond K.

2017-09-01

In this work, the technique of designing and optimizing broadband volume transmission holograms using dichromate gelatin (DCG) is summarized for solar spectrum-splitting application. Spectrum splitting photovoltaic system uses a series of single bandgap PV cells that have different spectral conversion efficiency properties to more fully utilize the solar spectrum. In such a system, one or more high performance optical filters are usually required to split the solar spectrum and efficiently send them to the corresponding PV cells. An ideal spectral filter should have a rectangular shape with sharp transition wavelengths. DCG is a near ideal holographic material for solar applications as it can achieve high refractive index modulation, low absorption and scattering properties and long-term stability to solar exposure after sealing. In this research, a methodology of designing and modeling a transmission DCG hologram using coupled wave analysis for different PV bandgap combinations is described. To achieve a broad diffraction bandwidth and sharp cut-off wavelength, a cascaded structure of multiple thick holograms is described. A search algorithm is also developed to optimize both single and two-layer cascaded holographic spectrum splitters for the best bandgap combinations of two- and three-junction SSPV systems illuminated under the AM1.5 solar spectrum. The power conversion efficiencies of the optimized systems under the AM1.5 solar spectrum are then calculated using the detailed balance method, and shows an improvement compared with tandem structure.

A Compact UWB Band-Pass Filter Using Embedded Circular Slot Structures for Improved Upper Stop-band Performance

DEFF Research Database (Denmark)

Shen, Ming; Ren, Jian; Mikkelsen, Jan Hvolgaard

2016-01-01

structures into the ring resonator. This is different from conventional designs using cascaded bandstop/low-pass filters for stop-band response suppression, which usually leads to big circuit sizes. And hence the proposed approach can reduce the circuit size significantly. A prototype filter with a compact...... size (13.6 mm×6.75 mm) has been implemented for experimental validation. The measured results show a −3 dB frequency band from 3.4 GHz to 11.7 GHz and > 20 dB upper stop-band suppression from 12.5 GHz to 20GHz....

Performance analysis of a photovoltaic-thermochemical hybrid system prototype

International Nuclear Information System (INIS)

Li, Wenjia; Ling, Yunyi; Liu, Xiangxin; Hao, Yong

2017-01-01

Highlights: •A modular photovoltaic-thermochemical hybrid system prototype is proposed. •Net solar-electric efficiency up to 41% is achievable. •Stable solar power supply is achievable via convenient energy storage. •The modular design facilitates the scalability of the hybrid system. -- Abstract: A solar photovoltaic (PV) thermochemical hybrid system consisting of a point-focus Fresnel concentrator, a PV cell and a methanol thermochemical reactor is proposed. In particular, a reactor capable of operating under high solar concentration is designed, manufactured and tested. Studies on both kinetic and thermodynamic characteristics of the reactor and the system are performed. Analysis of numerical and experimental results shows that with cascaded solar energy utilization and synergy among different forms of energy, the hybrid system has the advantages of high net solar-electric efficiency (up to 41%), stable solar energy power supply, solar energy storage (via syngas) and flexibility in application scale. The hybrid system proposed in this work provides a potential solution to some key challenges of current solar energy utilization technologies.

A solar receiver-storage modular cascade based on porous ceramic structures for hybrid sensible/thermochemical solar energy storage

Science.gov (United States)

Agrafiotis, Christos; de Oliveira, Lamark; Roeb, Martin; Sattler, Christian

2016-05-01

The current state-of-the-art solar heat storage concept in air-operated Solar Tower Power Plants is to store the solar energy provided during on-sun operation as sensible heat in porous solid materials that operate as recuperators during off-sun operation. The technology is operationally simple; however its storage capacity is limited to 1.5 hours. An idea for extending this capacity is to render this storage concept from "purely" sensible to "hybrid" sensible/ thermochemical one, via coating the porous heat exchange modules with oxides of multivalent metals for which their reduction/oxidation reactions are accompanied by significant heat effects, or by manufacturing them entirely of such oxides. In this way solar heat produced during on-sun operation can be used (in addition to sensibly heating the porous solid) to power the endothermic reduction of the oxide from its state with the higher metal valence to that of the lower; the thermal energy can be entirely recovered by the reverse exothermic oxidation reaction (in addition to sensible heat) during off-sun operation. Such sensible and thermochemical storage concepts were tested on a solar-irradiated receiver- heat storage module cascade for the first time. Parametric studies performed so far involved the comparison of three different SiC-based receivers with respect to their capability of supplying solar-heated air at temperatures sufficient for the reduction of the oxides, the effect of air flow rate on the temperatures achieved within the storage module, as well as the comparison of different porous storage media made of cordierite with respect to their sensible storage capacity.

Cascading costs: an economic nitrogen cycle.

Science.gov (United States)

Moomaw, William R; Birch, Melissa B L

2005-09-01

The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrified to N(2). We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single ton of nitrogen can cascade through the system, the costs also cascade. Therefore evaluating the benefits of mitigating a ton of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that ton would cascade. The analysis reveals that it is most cost effective to remove a ton of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

Contingency Analysis of Cascading Line Outage Events

Energy Technology Data Exchange (ETDEWEB)

Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

2011-03-01

As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

Evaluation of methods for extraction of the volitional EMG in dynamic hybrid muscle activation

Directory of Open Access Journals (Sweden)

Mizrahi Joseph

2006-11-01

Full Text Available Abstract Background Hybrid muscle activation is a modality used for muscle force enhancement, in which muscle contraction is generated from two different excitation sources: volitional and external, by means of electrical stimulation (ES. Under hybrid activation, the overall EMG signal is the combination of the volitional and ES-induced components. In this study, we developed a computational scheme to extract the volitional EMG envelope from the overall dynamic EMG signal, to serve as an input signal for control purposes, and for evaluation of muscle forces. Methods A "synthetic" database was created from in-vivo experiments on the Tibialis Anterior of the right foot to emulate hybrid EMG signals, including the volitional and induced components. The database was used to evaluate the results obtained from six signal processing schemes, including seven different modules for filtration, rectification and ES component removal. The schemes differed from each other by their module combinations, as follows: blocking window only, comb filter only, blocking window and comb filter, blocking window and peak envelope, comb filter and peak envelope and, finally, blocking window, comb filter and peak envelope. Results and conclusion The results showed that the scheme including all the modules led to an excellent approximation of the volitional EMG envelope, as extracted from the hybrid signal, and underlined the importance of the artifact blocking window module in the process. The results of this work have direct implications on the development of hybrid muscle activation rehabilitation systems for the enhancement of weakened muscles.

Improvement of a thermoelectric and vapour compression hybrid refrigerator

International Nuclear Information System (INIS)

Astrain, D.; Martínez, A.; Rodríguez, A.

2012-01-01

This paper presents the improvement in the performance of a domestic hybrid refrigerator that combines vapour compression technology for the cooler and freezer compartments, and thermoelectric technology for a new compartment. The heat emitted by the Peltier modules is discharged into the freezer compartment, forming a cascade refrigeration system. This configuration leads to a significant improvement in the coefficient of operation. Thus, the electric power consumption of the modules and the refrigerator decreases by 95% and 20% respectively, with respect to those attained with a cascade refrigeration system connected with the cooler compartment. The optimization process is based on a computational model that simulates the behaviour of the whole refrigerator. Two prototypes have been built and tested. Experimental results indicate that the temperature of the new compartment is easily set up at any value between 0 and −4 °C, the oscillation of this temperature is always lower than 0.4 °C, and the electric power consumption is low enough to include this hybrid refrigerator into energy efficiency class A, according European rules and regulations. - Highlights: ► Optimization of a vapour compression and thermoelectric hybrid refrigerator. ► Two prototypes built and tested. Computational model for the whole refrigerator. ► Electric power consumption of the modules and the refrigerator 95% and 20% lower. ► New compartment refrigerated with thermoelectric technology. ► Inner temperature adjustable from 0 to −4 °C. Oscillations lower than ±0.2 °C.

Thermo-mechanical analysis of a user filter assembly for undulator/wiggler operations at the Advanced Photon Source

International Nuclear Information System (INIS)

Nian, H.L.T.; Kuzay, T.M.; Collins, J.; Shu, D.; Benson, C.; Dejus, R.

1996-01-01

This paper reports a thermo-mechanical study of a beamline filter (user filter) for undulator/wiggler operations. It is deployed in conjunction with the current commissioning window assembly on the APS insertion device (ID) front ends. The beamline filter at the Advanced Photon Source (APS) will eventually be used in windowless operations also. Hence survival and reasonable life expectancy of the filters under intense insertion device (ID) heat flu are crucial to the beamline operations. To accommodate various user requirements, the filter is configured to be a multi-choice type and smart to allow only those filter combinations that will be safe to operate with a given ring current and beamline insertion device gap. However, this paper addresses only the thermo-mechanical analysis of individual filter integrity and safety in all combinations possible. The current filter design is configured to have four filter frames in a cascade with each frame holding five filters. This allows a potential 625 total filter combinations. Thermal analysis for all of these combinations becomes a mammoth task considering the desired choices for filter materials (pyrolitic graphite and metallic filters), filter thicknesses, undulator gaps, and the beam currents. The paper addresses how this difficult task has been reduced to a reasonable effort and computational level. Results from thermo-mechanical analyses of the filter combinations are presented both in tabular and graphical format

Simulation of concentration spikes in cascades

International Nuclear Information System (INIS)

Wood, H.G.

2006-01-01

Research has been conducted to investigate the maximum possible enrichment that might be temporarily achieved in a facility that is producing enriched uranium for fuel for nuclear power reactors. The purpose is to provide information to evaluate if uranium enrichment facilities are producing 235 U enriched within declared limits appropriate for power reactors or if the facilities are actually producing more highly enriched uranium. The correlation between feed rate and separation factor in a gas centrifuge cascade shows that as flow decreases, the separation factor increases, thereby, creating small amounts of higher enriched uranium than would be found under optimum design operating conditions. The research uses a number of cascade enrichment programs to model the phenomenon and determine the maximum enrichment possible during the time transient of a gas centrifuge cascade. During cascade start-up, the flow through the centrifuges begins at lower than centrifuge design stage flow rates. Steady-state cascade models have been used to study the maximum 235 U concentrations that would be predicted in the cascade. These calculations should produce an upper bound of product concentrations expected during the transient phase of start-up. Due to the fact that there are different ways in which to start a cascade, several methods are used to determine the maximum enrichment during the time transient. Model cascades were created for gas centrifuges with several product to .feed assay separation factors. With this information, the models were defined and the equilibrium programs were used to determine the maximum enrichment level during the time transient. The calculations predict in a cascade with separation factor 1.254 designed to produce enriched uranium for the purpose of supplying reactor fuel, it would not be unreasonable to see some 235 U in the range of 12-15%. Higher assays produced during the start-up period might lead inspectors to believe the cascade is being

Improved selectivity towards NO₂ of phthalocyanine-based chemosensors by means of original indigo/nanocarbons hybrid material.

Science.gov (United States)

Brunet, J; Pauly, A; Dubois, M; Rodriguez-Mendez, M L; Ndiaye, A L; Varenne, C; Guérin, K

2014-09-01

A new and original gas sensor-system dedicated to the selective monitoring of nitrogen dioxide in air and in the presence of ozone, has been successfully achieved. Because of its high sensitivity and its partial selectivity towards oxidizing pollutants (nitrogen dioxide and ozone), copper phthalocyanine-based chemoresistors are relevant. The selectivity towards nitrogen dioxide results from the implementation of a high efficient and selective ozone filter upstream the sensing device. Thus, a powdered indigo/nanocarbons hybrid material has been developed and investigated for such an application. If nanocarbonaceous material acts as a highly permeable matrix with a high specific surface area, immobilized indigo nanoparticles are involved into an ozonolysis reaction with ozone leading to the selective removal of this analytes from air sample. The filtering yields towards each gas have been experimentally quantified and establish the complete removal of ozone while having the concentration of nitrogen dioxide unchanged. Long-term gas exposures reveal the higher durability of hybrid material as compared to nanocarbons and indigo separately. Synthesis, characterizations by many complementary techniques and tests of hybrid filters are detailed. Results on sensor-system including CuPc-based chemoresistors and indigo/carbon nanotubes hybrid material as in-line filter are illustrated. Sensing performances will be especially discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Stability of cascade search

Energy Technology Data Exchange (ETDEWEB)

Fomenko, Tatiana N [M. V. Lomonosov Moscow State University, Faculty of Computational Mathematics and Cybernetics, Moscow (Russian Federation)

2010-10-22

We find sufficient conditions on a searching multi-cascade for a modification of the set of limit points of the cascade that satisfy an assessing inequality for the distance from each of these points to the initial point to be small, provided that the modifications of the initial point and the initial set-valued functionals or maps used to construct the multi-cascade are small. Using this result, we prove the stability (in the above sense) of the cascade search for the set of common pre-images of a closed subspace under the action of n set-valued maps, n{>=}1 (in particular, for the set of common roots of these maps and for the set of their coincidences). For n=2 we obtain generalizations of some results of A. V. Arutyunov; the very statement of the problem comes from a recent paper of his devoted to the study of the stability of the subset of coincidences of a Lipschitz map and a covering map.

Implementation of High Time Delay Accuracy of Ultrasonic Phased Array Based on Interpolation CIC Filter.

Science.gov (United States)

Liu, Peilu; Li, Xinghua; Li, Haopeng; Su, Zhikun; Zhang, Hongxu

2017-10-12

In order to improve the accuracy of ultrasonic phased array focusing time delay, analyzing the original interpolation Cascade-Integrator-Comb (CIC) filter, an 8× interpolation CIC filter parallel algorithm was proposed, so that interpolation and multichannel decomposition can simultaneously process. Moreover, we summarized the general formula of arbitrary multiple interpolation CIC filter parallel algorithm and established an ultrasonic phased array focusing time delay system based on 8× interpolation CIC filter parallel algorithm. Improving the algorithmic structure, 12.5% of addition and 29.2% of multiplication was reduced, meanwhile the speed of computation is still very fast. Considering the existing problems of the CIC filter, we compensated the CIC filter; the compensated CIC filter's pass band is flatter, the transition band becomes steep, and the stop band attenuation increases. Finally, we verified the feasibility of this algorithm on Field Programming Gate Array (FPGA). In the case of system clock is 125 MHz, after 8× interpolation filtering and decomposition, time delay accuracy of the defect echo becomes 1 ns. Simulation and experimental results both show that the algorithm we proposed has strong feasibility. Because of the fast calculation, small computational amount and high resolution, this algorithm is especially suitable for applications with high time delay accuracy and fast detection.

Genetic algorithm based separation cascade optimization

International Nuclear Information System (INIS)

Mahendra, A.K.; Sanyal, A.; Gouthaman, G.; Bera, T.K.

2008-01-01

The conventional separation cascade design procedure does not give an optimum design because of squaring-off, variation of flow rates and separation factor of the element with respect to stage location. Multi-component isotope separation further complicates the design procedure. Cascade design can be stated as a constrained multi-objective optimization. Cascade's expectation from the separating element is multi-objective i.e. overall separation factor, cut, optimum feed and separative power. Decision maker may aspire for more comprehensive multi-objective goals where optimization of cascade is coupled with the exploration of separating element optimization vector space. In real life there are many issues which make it important to understand the decision maker's perception of cost-quality-speed trade-off and consistency of preferences. Genetic algorithm (GA) is one such evolutionary technique that can be used for cascade design optimization. This paper addresses various issues involved in the GA based multi-objective optimization of the separation cascade. Reference point based optimization methodology with GA based Pareto optimality concept for separation cascade was found pragmatic and promising. This method should be explored, tested, examined and further developed for binary as well as multi-component separations. (author)

MISO Current-mode Biquad Filter with Independent Control of Pole Frequency and Quality Factor

Directory of Open Access Journals (Sweden)

W. Jaikla

2012-09-01

Full Text Available This article presents a three-inputs single-output biquadratic filter performing completely standard functions: low-pass, high-pass, band-pass, band-reject and all-pass functions, based on current controlled current conveyor transconductance amplifier (CCCCTA. The quality factor and pole frequency can be electronically/independently tuned via the input bias current. The proposed circuit uses 2 CCCCTAs and 2 grounded capacitors without external any resistors which is very suitable to further develop into an integrated circuit. The filter does not require double input current signal. Each function response can be selected by suitably selecting input signals with digital method. Moreover, the circuit possesses high output impedance which would be an ideal choice for current-mode cascading. The PSPICE simulation results are included to verify the workability of the proposed filter. The given results agree well with the theoretical anticipation.

A Repetitive Control Scheme Aimed at Compensating the 6k + 1 Harmonics for a Three-Phase Hybrid Active Filter

DEFF Research Database (Denmark)

Luo, Zhaoxu; Su, Mei; Yang, Jian

2016-01-01

these disadvantages, many repetitive controllers with reduced delay time have been proposed, which can selectively compensate the odd harmonics or 6k±1 harmonics with delay time reduced to T0/2 and T0/3,repectively. To further study in this area, this paper proposes an improved repetitive scheme implemented...... in stationary reference frame, which only compensates the 6k+1 harmonics (e.g. -5, +7, -11, +13) in three-phase systems and reduces the time delay to T0/6 . So compared with the earlier reduced delay time repetitive controllers, the robustness and transient performance is further improved, the waste of control...... effort is reduced, and the possibility of amplifying and even injecting any harmonic noises into system is avoided to the greatest extent. Moreover, the proposed repetitive scheme is used in the control of a three-phase hybrid active power filter. The experimental results validate the effectiveness...

A hybrid model of primary radiation damage in crystals

International Nuclear Information System (INIS)

Samarin, S.I.; Dremov, V.V.

2009-01-01

The paper offers a hybrid model which combines molecular dynamics and Monte Carlo (MD+MC) methods to describe primary radiation damage in crystals, caused by particles whose energies are no higher than several tens of keV. The particles are tracked in accord with equations of motion with account for pair interaction. The model also considers particle interaction with the mean-field potential (MFP) of the crystal. Only particles involved in cascading are tracked. Equations of motion for these particles include dissipative forces which describe energy exchange between cascade particles and electrons. New particles - the atoms of the crystal in the cascade region - have stochastic parameters (phase coordinates); they are sampled by the Monte Carlo method from the distribution that describes the classic canonical ensemble of non-interacting particles subjected to the external MFP. The introduction of particle interaction with the MFP helps avoid difficulties related to crystal stability and the choice of an adequate interparticle interaction potential in the traditional MD methods. Our technique is many times as fast as the traditional MD methods because we consider only particles which are involved in cascading and apply special methods to speedup the calculation of forces by accounting for the short-range pair potential used

Ion-implantation dense cascade data

International Nuclear Information System (INIS)

Winterbon, K.B.

1983-04-01

A tabulation is given of data useful in estimating various aspects of ion-implantation cascades in the nuclear stopping regime, particularly with respect to nonlinearity of the cascade at high energy densities. The tabulation is restricted to self-ion implantation. Besides power-cross-section cascade dimensions, various material properties are included. Scaling of derived quantities with input data is noted, so one is not limited to the values assumed by the author

A multilevel-ROI-features-based machine learning method for detection of morphometric biomarkers in Parkinson's disease.

Science.gov (United States)

Peng, Bo; Wang, Suhong; Zhou, Zhiyong; Liu, Yan; Tong, Baotong; Zhang, Tao; Dai, Yakang

2017-06-09

Machine learning methods have been widely used in recent years for detection of neuroimaging biomarkers in regions of interest (ROIs) and assisting diagnosis of neurodegenerative diseases. The innovation of this study is to use multilevel-ROI-features-based machine learning method to detect sensitive morphometric biomarkers in Parkinson's disease (PD). Specifically, the low-level ROI features (gray matter volume, cortical thickness, etc.) and high-level correlative features (connectivity between ROIs) are integrated to construct the multilevel ROI features. Filter- and wrapper- based feature selection method and multi-kernel support vector machine (SVM) are used in the classification algorithm. T1-weighted brain magnetic resonance (MR) images of 69 PD patients and 103 normal controls from the Parkinson's Progression Markers Initiative (PPMI) dataset are included in the study. The machine learning method performs well in classification between PD patients and normal controls with an accuracy of 85.78%, a specificity of 87.79%, and a sensitivity of 87.64%. The most sensitive biomarkers between PD patients and normal controls are mainly distributed in frontal lobe, parental lobe, limbic lobe, temporal lobe, and central region. The classification performance of our method with multilevel ROI features is significantly improved comparing with other classification methods using single-level features. The proposed method shows promising identification ability for detecting morphometric biomarkers in PD, thus confirming the potentiality of our method in assisting diagnosis of the disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantum Cascade Laser-Based Photoacoustic Sensor for Trace Detection of Formaldehyde Gas

Directory of Open Access Journals (Sweden)

Pietro Mario Lugarà

2009-04-01

Full Text Available We report on the development of a photoacoustic sensor for the detection of formaldehyde (CH2O using a thermoelectrically cooled distributed-feedback quantum cascade laser operating in pulsed mode at 5.6 mm. A resonant photoacoustic cell, equipped with four electret microphones, is excited in its first longitudinal mode at 1,380 Hz. The absorption line at 1,778.9 cm-1 is selected for CH2O detection. A detection limit of 150 parts per billion in volume in nitrogen is achieved using a 10 seconds time constant and 4 mW laser power. Measurements in ambient air will require water vapour filters.

Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems.

Science.gov (United States)

Möritz, M; Peters, H; Nipko, B; Rüden, H

2001-07-01

The capability of air filters (filterclass: F6, F7) to retain airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused air filters. The number of airborne bacteria and molds before and behind the filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry ( 12 degrees C) outdoor air conditions air filters led to a marked reduction of airborne microorganism concentrations (bacteria by approximately 70% and molds by > 80%). However, during long periods of high relative humidity (> 80% R. H.) a proliferation of bacteria on air filters with subsequent release into the filtered air occurred. These microorganisms were mainly smaller than 1.1 microns therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the air filters to 80% R. H. (mean of 3 days), e.g. by using preheaters in front of air filters in HVAC-systems.

A Viola-Jones based hybrid face detection framework

Science.gov (United States)

Murphy, Thomas M.; Broussard, Randy; Schultz, Robert; Rakvic, Ryan; Ngo, Hau

2013-12-01

Improvements in face detection performance would benefit many applications. The OpenCV library implements a standard solution, the Viola-Jones detector, with a statistically boosted rejection cascade of binary classifiers. Empirical evidence has shown that Viola-Jones underdetects in some instances. This research shows that a truncated cascade augmented by a neural network could recover these undetected faces. A hybrid framework is constructed, with a truncated Viola-Jones cascade followed by an artificial neural network, used to refine the face decision. Optimally, a truncation stage that captured all faces and allowed the neural network to remove the false alarms is selected. A feedforward backpropagation network with one hidden layer is trained to discriminate faces based upon the thresholding (detection) values of intermediate stages of the full rejection cascade. A clustering algorithm is used as a precursor to the neural network, to group significant overlappings. Evaluated on the CMU/VASC Image Database, comparison with an unmodified OpenCV approach shows: (1) a 37% increase in detection rates if constrained by the requirement of no increase in false alarms, (2) a 48% increase in detection rates if some additional false alarms are tolerated, and (3) an 82% reduction in false alarms with no reduction in detection rates. These results demonstrate improved face detection and could address the need for such improvement in various applications.

Hadron cascades produced by electromagnetic cascades

International Nuclear Information System (INIS)

Nelson, W.R.; Jenkins, T.M.; Ranft, J.

1986-12-01

A method for calculating high energy hadron cascades induced by multi-GeV electron and photon beams is described. Using the EGS4 computer program, high energy photons in the EM shower are allowed to interact hadronically according to the vector meson dominance (VMD) model, facilitated by a Monte Carlo version of the dual multistring fragmentation model which is used in the hadron cascade code FLUKA. The results of this calculation compare very favorably with experimental data on hadron production in photon-proton collisions and on the hadron production by electron beams on targets (i.e., yields in secondary particle beam lines). Electron beam induced hadron star density contours are also presented and are compared with those produced by proton beams. This FLUKA-EGS4 coupling technique could find use in the design of secondary beams, in the determination high energy hadron source terms for shielding purposes, and in the estimation of induced radioactivity in targets, collimators and beam dumps

Cascade Organic Solar Cells

KAUST Repository

Schlenker, Cody W.

2011-09-27

We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

Cascade Organic Solar Cells

KAUST Repository

Schlenker, Cody W.; Barlier, Vincent S.; Chin, Stephanie W.; Whited, Matthew T.; McAnally, R. Eric; Forrest, Stephen R.; Thompson, Mark E.

2011-01-01

We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

Comparison of Several Modes in Simple ARC Second-Order Filter

Directory of Open Access Journals (Sweden)

A. I. Rybin

1994-07-01

Full Text Available In this paper the popular, multiple-feedback, ARC single opamp, highpass second-order filter is proposed in several types of modes, namely voltage, current and hybrid ones. These modes are studied and compared in detail. Computer experimental results are given supporting the theory.

The multilevel governance of migration and integration

NARCIS (Netherlands)

Scholten, P.; Penninx, R.; Garcés–Mascareñas, B.; Penninx, R.

2016-01-01

This chapter focuses on migration and integration as multilevel policy issues and explores the consequences in terms of multilevel governance. Immigration policymaking has been characterized by continued struggle between national governments and the EU about the amount of discretion states have in

Voltage-Mode All-Pass Filters Including Minimum Component Count Circuits

Directory of Open Access Journals (Sweden)

Sudhanshu Maheshwari

2007-01-01

Full Text Available This paper presents two new first-order voltage-mode all-pass filters using a single-current differencing buffered amplifier and four passive components. Each circuit is compatible to a current-controlled current differencing buffered amplifier with only two passive elements, thus resulting in two more circuits, which employ a capacitor, a resistor, and an active element, thus using a minimum of active and passive component counts. The proposed circuits possess low output impedance, and hence can be easily cascaded for voltage-mode systems. PSPICE simulation results are given to confirm the theory.

Pupil filter design by using a Bessel functions basis at the image plane.

Science.gov (United States)

Canales, Vidal F; Cagigal, Manuel P

2006-10-30

Many applications can benefit from the use of pupil filters for controlling the light intensity distribution near the focus of an optical system. Most of the design methods for such filters are based on a second-order expansion of the Point Spread Function (PSF). Here, we present a new procedure for designing radially-symmetric pupil filters. It is more precise than previous procedures as it considers the exact expression of the PSF, expanded as a function of first-order Bessel functions. Furthermore, this new method presents other advantages: the height of the side lobes can be easily controlled, it allows the design of amplitude-only, phase-only or hybrid filters, and the coefficients of the PSF expansion can be directly related to filter parameters. Finally, our procedure allows the design of filters with very different behaviours and optimal performance.

Shunt hybrid active power filter for harmonic mitigation: A practical ...

Indian Academy of Sciences (India)

shunt HAPF, APF is connected in series with PPF and the whole system is connected in parallel to the load. ... LC filter, it will force a fundamental reactive current to flow into it. ..... Since SHAPF is operating as a boost rectifier, d.c. voltage.

Multilevel security for relational databases

CERN Document Server

Faragallah, Osama S; El-Samie, Fathi E Abd

2014-01-01

Concepts of Database Security Database Concepts Relational Database Security Concepts Access Control in Relational Databases      Discretionary Access Control      Mandatory Access Control      Role-Based Access Control Work Objectives Book Organization Basic Concept of Multilevel Database Security IntroductionMultilevel Database Relations Polyinstantiation      Invisible Polyinstantiation      Visible Polyinstantiation      Types of Polyinstantiation      Architectural Consideration

Cascaded Bragg scattering in fiber optics.

Science.gov (United States)

Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

2013-01-15

We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

Information filtering on coupled social networks.

Science.gov (United States)

Nie, Da-Cheng; Zhang, Zi-Ke; Zhou, Jun-Lin; Fu, Yan; Zhang, Kui

2014-01-01

In this paper, based on the coupled social networks (CSN), we propose a hybrid algorithm to nonlinearly integrate both social and behavior information of online users. Filtering algorithm, based on the coupled social networks, considers the effects of both social similarity and personalized preference. Experimental results based on two real datasets, Epinions and Friendfeed, show that the hybrid pattern can not only provide more accurate recommendations, but also enlarge the recommendation coverage while adopting global metric. Further empirical analyses demonstrate that the mutual reinforcement and rich-club phenomenon can also be found in coupled social networks where the identical individuals occupy the core position of the online system. This work may shed some light on the in-depth understanding of the structure and function of coupled social networks.

Cascade redox flow battery systems

Science.gov (United States)

Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

2014-07-22

A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

Tunable microwave photonic filter free from baseband and carrier suppression effect not requiring single sideband modulation using a Mach-Zenhder configuration.

Science.gov (United States)

Mora, José; Ortigosa-Blanch, Arturo; Pastor, Daniel; Capmany, José

2006-08-21

We present a full theoretical and experimental analysis of a novel all-optical microwave photonic filter combining a mode-locked fiber laser and a Mach-Zenhder structure in cascade to a 2x1 electro-optic modulator. The filter is free from the carrier suppression effect and thus it does not require single sideband modulation. Positive and negative coefficients are obtained inherently in the system and the tunability is achieved by controlling the optical path difference of the Mach-Zenhder structure.

Bowtie filter and water calibration in the improvement of cone beam CT image quality

International Nuclear Information System (INIS)

Li Minghui; Dai Jianrong; Zhang Ke

2010-01-01

Objective: To evaluate the improvement of cone beam CT (CBCT) image quality by using bewtie filter (F 1 ) and water calibration. Methods: First the multi-level gain calibration of the detector panel with the method of Cal 2 calibration was performed, and the CT images of CATPHAN503 with F 0 and bowtie filter were collected, respectively. Then the detector panel using water calibration kit was calibrated, and images were acquired again. Finally, the change of image quality after using F 1 and (or) water calibration method was observed. The observed indexes included low contrast visibility, spatial uniformity, ring artifact, spatial resolution and geometric accuracy. Results: Comparing with the traditional combination of F 0 filter and Cal 2 calibration, the combination of bowtie filter F 1 and water calibration improves low contrast visibility by 13.71%, and spatial uniformity by 54. 42%. Water calibration removes ring artifacts effectively. However, none of them improves spatial resolution and geometric accuracy. Conclusions: The combination of F 1 and water calibration improves CBCT image quality effectively. This improvement is aid to the registration of CBCT images and localization images. (authors)

Multihopping Multilevel Clustering Heterogeneity-Sensitive Optimized Routing Protocol for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Muhammad Aslam

2017-01-01

Full Text Available Effective utilization of energy resources in Wireless Sensor Networks (WSNs has become challenging under uncertain distributed cluster-formation and single-hop intercluster communication capabilities. So, sensor nodes are forced to operate at expensive full rate transmission power level continuously during whole network operation. These challenging network environments experience unwanted phenomena of drastic energy consumption and packet drop. In this paper, we propose an adaptive immune Multihopping Multilevel Clustering (MHMLC protocol that executes a Hybrid Clustering Algorithm (HCA to perform optimal centralized selection of Cluster-Heads (CHs within radius of centrally located Base Station (BS and distributed CHs selection in the rest of network area. HCA of MHMLC also produces optimal intermediate CHs for intercluster multihop communications that develop heterogeneity-aware economical links. This hybrid cluster-formation facilitates the sensors to function at short range transmission power level that enhances link quality and avoids packet drop. The simulation environments produce fair comparison among proposed MHMLC and existing state-of-the-art routing protocols. Experimental results give significant evidence of better performance of the proposed model in terms of network lifetime, stability period, and data delivery ratio.

Boundary based on exchange symmetry theory for multilevel simulations. I. Basic theory.

Science.gov (United States)

Shiga, Motoyuki; Masia, Marco

2013-07-28

In this paper, we lay the foundations for a new method that allows multilevel simulations of a diffusive system, i.e., a system where a flux of particles through the boundaries might disrupt the primary region. The method is based on the use of flexible restraints that maintain the separation between inner and outer particles. It is shown that, by introducing a bias potential that accounts for the exchange symmetry of the system, the correct statistical distribution is preserved. Using a toy model consisting of non-interacting particles in an asymmetric potential well, we prove that the method is formally exact, and that it could be simplified by considering only up to a couple of particle exchanges without a loss of accuracy. A real-world test is then made by considering a hybrid MM(∗)/MM calculation of cesium ion in water. In this case, the single exchange approximation is sound enough that the results superimpose to the exact solutions. Potential applications of this method to many different hybrid QM/MM systems are discussed, as well as its limitations and strengths in comparison to existing approaches.

Multilevel optimization algorithms and applications

CERN Document Server

Pardalos, Panos; Värbrand, Peter

1998-01-01

Researchers working with nonlinear programming often claim "the word is non­ linear" indicating that real applications require nonlinear modeling. The same is true for other areas such as multi-objective programming (there are always several goals in a real application), stochastic programming (all data is uncer­ tain and therefore stochastic models should be used), and so forth. In this spirit we claim: The word is multilevel. In many decision processes there is a hierarchy of decision makers, and decisions are made at different levels in this hierarchy. One way to handle such hierar­ chies is to focus on one level and include other levels' behaviors as assumptions. Multilevel programming is the research area that focuses on the whole hierar­ chy structure. In terms of modeling, the constraint domain associated with a multilevel programming problem is implicitly determined by a series of opti­ mization problems which must be solved in a predetermined sequence. If only two levels are considered, we have ...

Implementation of High Time Delay Accuracy of Ultrasonic Phased Array Based on Interpolation CIC Filter

Directory of Open Access Journals (Sweden)

Peilu Liu

2017-10-01

Full Text Available In order to improve the accuracy of ultrasonic phased array focusing time delay, analyzing the original interpolation Cascade-Integrator-Comb (CIC filter, an 8× interpolation CIC filter parallel algorithm was proposed, so that interpolation and multichannel decomposition can simultaneously process. Moreover, we summarized the general formula of arbitrary multiple interpolation CIC filter parallel algorithm and established an ultrasonic phased array focusing time delay system based on 8× interpolation CIC filter parallel algorithm. Improving the algorithmic structure, 12.5% of addition and 29.2% of multiplication was reduced, meanwhile the speed of computation is still very fast. Considering the existing problems of the CIC filter, we compensated the CIC filter; the compensated CIC filter’s pass band is flatter, the transition band becomes steep, and the stop band attenuation increases. Finally, we verified the feasibility of this algorithm on Field Programming Gate Array (FPGA. In the case of system clock is 125 MHz, after 8× interpolation filtering and decomposition, time delay accuracy of the defect echo becomes 1 ns. Simulation and experimental results both show that the algorithm we proposed has strong feasibility. Because of the fast calculation, small computational amount and high resolution, this algorithm is especially suitable for applications with high time delay accuracy and fast detection.

Cascade of links in complex networks

Energy Technology Data Exchange (ETDEWEB)

Feng, Yeqian; Sun, Bihui [Department of Management Science, School of Government, Beijing Normal University, 100875 Beijing (China); Zeng, An, E-mail: anzeng@bnu.edu.cn [School of Systems Science, Beijing Normal University, 100875 Beijing (China)

2017-01-30

Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

Cascade of links in complex networks

International Nuclear Information System (INIS)

Feng, Yeqian; Sun, Bihui; Zeng, An

2017-01-01

Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

A cascade autocatalytic strand displacement amplification and hybridization chain reaction event for label-free and ultrasensitive electrochemical nucleic acid biosensing.

Science.gov (United States)

Chen, Zhiqiang; Liu, Ying; Xin, Chen; Zhao, Jikuan; Liu, Shufeng

2018-04-23

Herein, an autocatalytic strand displacement amplification (ASDA) strategy was proposed for the first time, which was further ingeniously coupled with hybridization chain reaction (HCR) event for the isothermal, label-free and multiple amplification toward nucleic acid detection. During the ASDA module, the target recognition opens the immobilized hairpin probe (IP) and initiates the annealing of the auxiliary DNA strand (AS) with the opened IP for the successive polymerization and nicking reaction in the presence of DNA polymerase and nicking endonuclease. This induces the target recycling and generation of a large amount of intermediate DNA sequences, which can be used as target analogy to execute the autocatalytic strand displacement amplification. Simultaneously, the introduced AS strand can propagate the HCR between two hairpins (H1 and H2) to form a linear DNA concatamer with cytosine (C)-rich loop region, which can facilitate the in-situ synthesis of silver nanoclusters (AgNCs) as electrochemical tags for further amplification toward target responses. With current cascade ASDA and HCR strategy, the detection of target DNA could be achieved with a low detection limit of about 0.16 fM and a good selectivity. The developed biosensor also exhibits the distinct advantages of flexibility and simplicity in probe design and biosensor fabrication, and label-free electrochemical detection, thus opens a promising avenue for the detection of nucleic acid with low abundance in bioanalysis and clinical biomedicine. Copyright © 2018 Elsevier B.V. All rights reserved.

Junction-type photonic crystal waveguides for notch- and pass-band filtering

KAUST Repository

Shahid, Naeem

2011-01-01

Evolution of the mode gap and the associated transmission mini stop-band (MSB) as a function of photonic crystal (PhC) waveguide width is theoretically and experimentally investigated. The change of line-defect width is identified to be the most appropriate way since it offers a wide MSB wavelength tuning range. A high transmission narrow-band filter is experimentally demonstrated in a junction-type waveguide composed of two PhC waveguides with slightly different widths. The full width at half maximum is 5.6 nm; the peak transmission is attenuated by only ∼5 dB and is ∼20 dB above the MSBs. Additionally, temperature tuning of the filter were also performed. The results show red-shift of the transmission peak and the MSB edges with a gradient of dλ/dT = 0.1 nm/°C. It is proposed that the transmission MSBs in such junction-type cascaded PhC waveguides can be used to obtain different types of filters. © 2011 Optical Society of America.

Fault detection and diagnosis in asymmetric multilevel inverter using artificial neural network

Science.gov (United States)

Raj, Nithin; Jagadanand, G.; George, Saly

2018-04-01

The increased component requirement to realise multilevel inverter (MLI) fallout in a higher fault prospect due to power semiconductors. In this scenario, efficient fault detection and diagnosis (FDD) strategies to detect and locate the power semiconductor faults have to be incorporated in addition to the conventional protection systems. Even though a number of FDD methods have been introduced in the symmetrical cascaded H-bridge (CHB) MLIs, very few methods address the FDD in asymmetric CHB-MLIs. In this paper, the gate-open circuit FDD strategy in asymmetric CHB-MLI is presented. Here, a single artificial neural network (ANN) is used to detect and diagnose the fault in both binary and trinary configurations of the asymmetric CHB-MLIs. In this method, features of the output voltage of the MLIs are used as to train the ANN for FDD method. The results prove the validity of the proposed method in detecting and locating the fault in both asymmetric MLI configurations. Finally, the ANN response to the input parameter variation is also analysed to access the performance of the proposed ANN-based FDD strategy.

Design of multiplier-less sharp non-uniform cosine modulated filter banks for efficient channelizers in software defined radio

Directory of Open Access Journals (Sweden)

Shaeen Kalathil

2016-03-01

Full Text Available Forthcoming software defined radios require filter banks which satisfy stringent specifications efficiently with low implementation complexity. Cosine modulated filter banks (CMFB have simple and efficient design procedure. The different wireless standards have different channel spacing or bandwidths and hence demand non-uniform decomposition of subbands. The non-uniform CMFB can be obtained from a uniform CMFB in a simple and efficient approach by merging the adjacent channels of the uniform CMFB. Very narrow transition width filters with low complexity can be achieved using frequency response masking (FRM filter as prototype filter. The complexity is further reduced by the multiplier-less realization of filter banks in which the least number of signed power of two (SPT terms is achieved by representing the filter coefficients using canonic signed digit (CSD representation and then optimizing using suitable modified meta-heuristic algorithms. Hybrid meta-heuristic algorithms are used in this paper. A hybrid algorithm combines the qualities of two meta-heuristic algorithms and results in improved performances with low implementation complexity. Highly frequency selective filter banks characterized by small passband ripple, narrow transition width and high stopband attenuation with non-uniform decomposition of subbands can be designed with least the implementation complexity, using this approach. A digital channelizer can be designed for SDR implementations, using the proposed approach. In this paper, the non-uniform CMFB is designed for various existing wireless standards.

Automatic Semiconductor Wafer Image Segmentation for Defect Detection Using Multilevel Thresholding

Directory of Open Access Journals (Sweden)

Saad N.H.

2016-01-01

Full Text Available Quality control is one of important process in semiconductor manufacturing. A lot of issues trying to be solved in semiconductor manufacturing industry regarding the rate of production with respect to time. In most semiconductor assemblies, a lot of wafers from various processes in semiconductor wafer manufacturing need to be inspected manually using human experts and this process required full concentration of the operators. This human inspection procedure, however, is time consuming and highly subjective. In order to overcome this problem, implementation of machine vision will be the best solution. This paper presents automatic defect segmentation of semiconductor wafer image based on multilevel thresholding algorithm which can be further adopted in machine vision system. In this work, the defect image which is in RGB image at first is converted to the gray scale image. Median filtering then is implemented to enhance the gray scale image. Then the modified multilevel thresholding algorithm is performed to the enhanced image. The algorithm worked in three main stages which are determination of the peak location of the histogram, segmentation the histogram between the peak and determination of first global minimum of histogram that correspond to the threshold value of the image. The proposed approach is being evaluated using defected wafer images. The experimental results shown that it can be used to segment the defect correctly and outperformed other thresholding technique such as Otsu and iterative thresholding.

The comparison of extraction of energy in two-cascade and one-cascade targets

Energy Technology Data Exchange (ETDEWEB)

Dolgoleva, G. V., E-mail: dolgg@list.ru [National Research Tomsk State University, 36, Lenin Ave., 634050, Tomsk (Russian Federation); Ponomarev, I. V., E-mail: wingof17@mail.ru [Moscow State University, Department of Mechanics and Mathematics, 1, Vorobyovy Gory, Moscow,119961 (Russian Federation)

2016-01-15

The paper is devoted to numerical designing of cylindrical microtargets on the basis of shock-free compression. When designing microtargets for the controlled thermonuclear fusion, the core tasks are to select geometry and make-up of layers, and the law of energy embedding as well, which allow receiving of “burning” of deuterium- tritium mix, that is, the existence of thermonuclear reactions of working area. Yet, the energy yield as a result of thermonuclear reactions has to be more than the embedded energy (the coefficient of amplification is more than a unit). So, an important issue is the value of the embedded energy. The purpose of the present paper is to study the extraction of energy by working DT area in one-cascade and two-cascade targets. A bigger extraction of energy will contribute to a better burning of DT mix and a bigger energy yield as a result of thermonuclear reactions. The comparison of analytical results to numerical calculations is carried out. The received results show advantages of a two-cascade target compared to a one-cascade one.

Shunt hybrid active power filter for harmonic mitigation: A practical ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels ...

An Improved Iris Recognition Algorithm Based on Hybrid Feature and ELM

Science.gov (United States)

Wang, Juan

2018-03-01

The iris image is easily polluted by noise and uneven light. This paper proposed an improved extreme learning machine (ELM) based iris recognition algorithm with hybrid feature. 2D-Gabor filters and GLCM is employed to generate a multi-granularity hybrid feature vector. 2D-Gabor filter and GLCM feature work for capturing low-intermediate frequency and high frequency texture information, respectively. Finally, we utilize extreme learning machine for iris recognition. Experimental results reveal our proposed ELM based multi-granularity iris recognition algorithm (ELM-MGIR) has higher accuracy of 99.86%, and lower EER of 0.12% under the premise of real-time performance. The proposed ELM-MGIR algorithm outperforms other mainstream iris recognition algorithms.

Scalable Adaptive Multilevel Solvers for Multiphysics Problems

Energy Technology Data Exchange (ETDEWEB)

Xu, Jinchao [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mathematics

2014-11-26

In this project, we carried out many studies on adaptive and parallel multilevel methods for numerical modeling for various applications, including Magnetohydrodynamics (MHD) and complex fluids. We have made significant efforts and advances in adaptive multilevel methods of the multiphysics problems: multigrid methods, adaptive finite element methods, and applications.

Experimental study of flow through compressor Cascade

Directory of Open Access Journals (Sweden)

Satyam Panchal

2017-09-01

Full Text Available The objective of this research work is to study the behaviour of flow at the inlet, within the blade passage and at the exit of a compressor cascade. For this purpose, a cascade with six numbers of aerofoil blades was designed and constructed. The cascade was fitted on the cascade test tunnel. Out of six blades two were instrumented for measuring the pressure distribution on the pressure and suction surface. The blades had a parabolic camber line, with a maximum camber position at 40% of the chord from the leading edge of the blade. The profile of the blade was C4, height of the blade was 160 mm, chord length was 80 mm, camber angle was 45° and stagger angle was 30°. Similarly, the length of the cascade was 300 mm, span was 160 mm, pitch was 60 mm, the actual chord of the cascade was 80 mm, the axial chord of the cascade was 70 mm, the stagger angle of the cascade was 30° and the pitch-chord ratio was 0.75. The data was taken and analyzed at −500% of the axial chord before the cascade, −25% of the axial chord before the leading edge, 25%, 50%, 75% and 150% of the axial chord from the leading edge of the blade. The readings were taken from the cascade wall to the mid span position along the pitch wise direction. The angle of incidence was also changed during the experiment and varied from i=−50°, −30°, −10° to 5°.

Ant colony optimisation-direct cover: a hybrid ant colony direct cover technique for multi-level synthesis of multiple-valued logic functions

Science.gov (United States)

Abd-El-Barr, Mostafa

2010-12-01

The use of non-binary (multiple-valued) logic in the synthesis of digital systems can lead to savings in chip area. Advances in very large scale integration (VLSI) technology have enabled the successful implementation of multiple-valued logic (MVL) circuits. A number of heuristic algorithms for the synthesis of (near) minimal sum-of products (two-level) realisation of MVL functions have been reported in the literature. The direct cover (DC) technique is one such algorithm. The ant colony optimisation (ACO) algorithm is a meta-heuristic that uses constructive greediness to explore a large solution space in finding (near) optimal solutions. The ACO algorithm mimics the ant's behaviour in the real world in using the shortest path to reach food sources. We have previously introduced an ACO-based heuristic for the synthesis of two-level MVL functions. In this article, we introduce the ACO-DC hybrid technique for the synthesis of multi-level MVL functions. The basic idea is to use an ant to decompose a given MVL function into a number of levels and then synthesise each sub-function using a DC-based technique. The results obtained using the proposed approach are compared to those obtained using existing techniques reported in the literature. A benchmark set consisting of 50,000 randomly generated 2-variable 4-valued functions is used in the comparison. The results obtained using the proposed ACO-DC technique are shown to produce efficient realisation in terms of the average number of gates (as a measure of chip area) needed for the synthesis of a given MVL function.

A SLAM based on auxiliary marginalised particle filter and differential evolution

Science.gov (United States)

Havangi, R.; Nekoui, M. A.; Teshnehlab, M.; Taghirad, H. D.

2014-09-01

FastSLAM is a framework for simultaneous localisation and mapping (SLAM) using a Rao-Blackwellised particle filter. In FastSLAM, particle filter is used for the robot pose (position and orientation) estimation, and parametric filter (i.e. EKF and UKF) is used for the feature location's estimation. However, in the long term, FastSLAM is an inconsistent algorithm. In this paper, a new approach to SLAM based on hybrid auxiliary marginalised particle filter and differential evolution (DE) is proposed. In the proposed algorithm, the robot pose is estimated based on auxiliary marginal particle filter that operates directly on the marginal distribution, and hence avoids performing importance sampling on a space of growing dimension. In addition, static map is considered as a set of parameters that are learned using DE. Compared to other algorithms, the proposed algorithm can improve consistency for longer time periods and also, improve the estimation accuracy. Simulations and experimental results indicate that the proposed algorithm is effective.

A cascade model of information processing and encoding for retinal prosthesis.

Science.gov (United States)

Pei, Zhi-Jun; Gao, Guan-Xin; Hao, Bo; Qiao, Qing-Li; Ai, Hui-Jian

2016-04-01

Retinal prosthesis offers a potential treatment for individuals suffering from photoreceptor degeneration diseases. Establishing biological retinal models and simulating how the biological retina convert incoming light signal into spike trains that can be properly decoded by the brain is a key issue. Some retinal models have been presented, ranking from structural models inspired by the layered architecture to functional models originated from a set of specific physiological phenomena. However, Most of these focus on stimulus image compression, edge detection and reconstruction, but do not generate spike trains corresponding to visual image. In this study, based on state-of-the-art retinal physiological mechanism, including effective visual information extraction, static nonlinear rectification of biological systems and neurons Poisson coding, a cascade model of the retina including the out plexiform layer for information processing and the inner plexiform layer for information encoding was brought forward, which integrates both anatomic connections and functional computations of retina. Using MATLAB software, spike trains corresponding to stimulus image were numerically computed by four steps: linear spatiotemporal filtering, static nonlinear rectification, radial sampling and then Poisson spike generation. The simulated results suggested that such a cascade model could recreate visual information processing and encoding functionalities of the retina, which is helpful in developing artificial retina for the retinally blind.

A new hybrid model optimized by an intelligent optimization algorithm for wind speed forecasting

International Nuclear Information System (INIS)

Su, Zhongyue; Wang, Jianzhou; Lu, Haiyan; Zhao, Ge

2014-01-01

Highlights: • A new hybrid model is developed for wind speed forecasting. • The model is based on the Kalman filter and the ARIMA. • An intelligent optimization method is employed in the hybrid model. • The new hybrid model has good performance in western China. - Abstract: Forecasting the wind speed is indispensable in wind-related engineering studies and is important in the management of wind farms. As a technique essential for the future of clean energy systems, reducing the forecasting errors related to wind speed has always been an important research subject. In this paper, an optimized hybrid method based on the Autoregressive Integrated Moving Average (ARIMA) and Kalman filter is proposed to forecast the daily mean wind speed in western China. This approach employs Particle Swarm Optimization (PSO) as an intelligent optimization algorithm to optimize the parameters of the ARIMA model, which develops a hybrid model that is best adapted to the data set, increasing the fitting accuracy and avoiding over-fitting. The proposed method is subsequently examined on the wind farms of western China, where the proposed hybrid model is shown to perform effectively and steadily

Dust characterisation for hot gas filters

Energy Technology Data Exchange (ETDEWEB)

Dockter, B.; Erickson, T.; Henderson, A.; Hurley, J.; Kuehnel, V.; Katrinak, K.; Nowok, J.; O`Keefe, C.; O`Leary, E.; Swanson, M.; Watne, T. [University of North Dakota, Grand Forks, ND (United States). Energy and Environmental Research Center (UNDEERC)

1998-03-01

Hot gas filtration to remove particulates from the gas flow upstream of the gas turbine is critical to the development of many of the advanced coal-fired power generation technologies such as the Air Blown Gasification Cycle (ABGC), a hybrid gasification combined cycle being developed in the UK. Ceramic candle filters are considered the most promising technology for this purpose. Problems of mechanical failure and of `difficult-to-clean` dusts causing high pressure losses across the filter elements need to be solved. The project investigated the behaviour of high-temperature filter dusts, and the factors determining the ease with which they can be removed from filters. The high-temperature behaviour of dusts from both combustion and gasification systems was investigated. Dust samples were obtained from full-scale demonstration and pilot-scale plant operating around the world. Dust samples were also produced from a variety of coals, and under several different operating conditions, on UNDEERC`s pilot-scale reactor. Key factors affecting dust behaviour were examined, including: the rates of tensile strength developing in dust cakes; the thermochemical equilibria pertaining under filtration conditions; dust adhesivity on representative filter materials; and the build-up and cleaning behaviour of dusts on representative filter candles. The results obtained confirmed the importance of dust temperature, dust cake porosity, cake liquid content, and particle size distribution in determining the strength of a dust cake. An algorithm was developed to indicate the likely sticking propensity of dusts as a function of coal and sorbent composition and combustion conditions. This algorithm was incorporated into a computer package which can be used to judge the degree of difficulty in filter cleaning that can be expected to arise in a real plant based on operating parameters and coal analyzes. 6 figs.

Experimental researches and comparison on aerodynamic parameters and cleaning efficiency of multi-level multi-channel cyclone

Directory of Open Access Journals (Sweden)

Aleksandras Chlebnikovas

2015-10-01

Full Text Available Multi-level multi-channel cyclone – the lately designed air cleaning device that can remove ultra-fine 20 μm particulatematter (PM from dusted air and reach over 95% of the overall cleaning efficiency. Multi-channel cyclone technology is based on centrifugal forces and has the resulting additional filtering process operation. Multi-level structure of cyclone allows to achieve higher air flow cleaning capacity at the same dimensions of the device, thus saving installation space required for the job, production and operating costs. Studies have examined the air flow parameters change in one–, two– and three–levels multichannel cyclone. These constructions differ according to the productivity of cleaned air under the constant peripheral and transitional (50/50 case air flow relations. Accordance with the results of air flow dynamics – velocity distribution of multi-channel cyclone, aerodynamic resistance and efficiency can be judged on the flow turbulence, the flow channel cross-section and select the most appropriate application. Cleaning efficiency studies were carried out using fine granite and wood ashes PM. The maximum cleaning efficiency was 93.3%, at an average of 4.5 g/m3, the aerodynamic resistance was equal to 1525 Pa.

An improved AE detection method of rail defect based on multi-level ANC with VSS-LMS

Science.gov (United States)

Zhang, Xin; Cui, Yiming; Wang, Yan; Sun, Mingjian; Hu, Hengshan

2018-01-01

In order to ensure the safety and reliability of railway system, Acoustic Emission (AE) method is employed to investigate rail defect detection. However, little attention has been paid to the defect detection at high speed, especially for noise interference suppression. Based on AE technology, this paper presents an improved rail defect detection method by multi-level ANC with VSS-LMS. Multi-level noise cancellation based on SANC and ANC is utilized to eliminate complex noises at high speed, and tongue-shaped curve with index adjustment factor is proposed to enhance the performance of variable step-size algorithm. Defect signals and reference signals are acquired by the rail-wheel test rig. The features of noise signals and defect signals are analyzed for effective detection. The effectiveness of the proposed method is demonstrated by comparing with the previous study, and different filter lengths are investigated to obtain a better noise suppression performance. Meanwhile, the detection ability of the proposed method is verified at the top speed of the test rig. The results clearly illustrate that the proposed method is effective in detecting rail defects at high speed, especially for noise interference suppression.

Performance analysis of three-dimensional-triple-level cell and two-dimensional-multi-level cell NAND flash hybrid solid-state drives

Science.gov (United States)

Sakaki, Yukiya; Yamada, Tomoaki; Matsui, Chihiro; Yamaga, Yusuke; Takeuchi, Ken

2018-04-01

In order to improve performance of solid-state drives (SSDs), hybrid SSDs have been proposed. Hybrid SSDs consist of more than two types of NAND flash memories or NAND flash memories and storage-class memories (SCMs). However, the cost of hybrid SSDs adopting SCMs is more expensive than that of NAND flash only SSDs because of the high bit cost of SCMs. This paper proposes unique hybrid SSDs with two-dimensional (2D) horizontal multi-level cell (MLC)/three-dimensional (3D) vertical triple-level cell (TLC) NAND flash memories to achieve higher cost-performance. The 2D-MLC/3D-TLC hybrid SSD achieves up to 31% higher performance than the conventional 2D-MLC/2D-TLC hybrid SSD. The factors of different performance between the proposed hybrid SSD and the conventional hybrid SSD are analyzed by changing its block size, read/write/erase latencies, and write unit of 3D-TLC NAND flash memory, by means of a transaction-level modeling simulator.

A comparison of methods for cascade prediction

OpenAIRE

Guo, Ruocheng; Shakarian, Paulo

2016-01-01

Information cascades exist in a wide variety of platforms on Internet. A very important real-world problem is to identify which information cascades can go viral. A system addressing this problem can be used in a variety of applications including public health, marketing and counter-terrorism. As a cascade can be considered as compound of the social network and the time series. However, in related literature where methods for solving the cascade prediction problem were proposed, the experimen...

Computer simulation of displacement cascades in copper

International Nuclear Information System (INIS)

Heinisch, H.L.

1983-06-01

More than 500 displacement cascades in copper have been generated with the computer simulation code MARLOWE over an energy range pertinent to both fission and fusion neutron spectra. Three-dimensional graphical depictions of selected cascades, as well as quantitative analysis of cascade shapes and sizes and defect densities, illustrate cascade behavior as a function of energy. With increasing energy, the transition from production of single compact damage regions to widely spaced multiple damage regions is clearly demonstrated

Blind Source Parameters for Performance Evaluation of Despeckling Filters

Directory of Open Access Journals (Sweden)

Nagashettappa Biradar

2016-01-01

Full Text Available The speckle noise is inherent to transthoracic echocardiographic images. A standard noise-free reference echocardiographic image does not exist. The evaluation of filters based on the traditional parameters such as peak signal-to-noise ratio, mean square error, and structural similarity index may not reflect the true filter performance on echocardiographic images. Therefore, the performance of despeckling can be evaluated using blind assessment metrics like the speckle suppression index, speckle suppression and mean preservation index (SMPI, and beta metric. The need for noise-free reference image is overcome using these three parameters. This paper presents a comprehensive analysis and evaluation of eleven types of despeckling filters for echocardiographic images in terms of blind and traditional performance parameters along with clinical validation. The noise is effectively suppressed using the logarithmic neighborhood shrinkage (NeighShrink embedded with Stein’s unbiased risk estimation (SURE. The SMPI is three times more effective compared to the wavelet based generalized likelihood estimation approach. The quantitative evaluation and clinical validation reveal that the filters such as the nonlocal mean, posterior sampling based Bayesian estimation, hybrid median, and probabilistic patch based filters are acceptable whereas median, anisotropic diffusion, fuzzy, and Ripplet nonlinear approximation filters have limited applications for echocardiographic images.

Blind Source Parameters for Performance Evaluation of Despeckling Filters.

Science.gov (United States)

Biradar, Nagashettappa; Dewal, M L; Rohit, ManojKumar; Gowre, Sanjaykumar; Gundge, Yogesh

2016-01-01

The speckle noise is inherent to transthoracic echocardiographic images. A standard noise-free reference echocardiographic image does not exist. The evaluation of filters based on the traditional parameters such as peak signal-to-noise ratio, mean square error, and structural similarity index may not reflect the true filter performance on echocardiographic images. Therefore, the performance of despeckling can be evaluated using blind assessment metrics like the speckle suppression index, speckle suppression and mean preservation index (SMPI), and beta metric. The need for noise-free reference image is overcome using these three parameters. This paper presents a comprehensive analysis and evaluation of eleven types of despeckling filters for echocardiographic images in terms of blind and traditional performance parameters along with clinical validation. The noise is effectively suppressed using the logarithmic neighborhood shrinkage (NeighShrink) embedded with Stein's unbiased risk estimation (SURE). The SMPI is three times more effective compared to the wavelet based generalized likelihood estimation approach. The quantitative evaluation and clinical validation reveal that the filters such as the nonlocal mean, posterior sampling based Bayesian estimation, hybrid median, and probabilistic patch based filters are acceptable whereas median, anisotropic diffusion, fuzzy, and Ripplet nonlinear approximation filters have limited applications for echocardiographic images.

Cascade Error Projection Learning Algorithm

Science.gov (United States)

Duong, T. A.; Stubberud, A. R.; Daud, T.

1995-01-01

A detailed mathematical analysis is presented for a new learning algorithm termed cascade error projection (CEP) and a general learning frame work. This frame work can be used to obtain the cascade correlation learning algorithm by choosing a particular set of parameters.

Hybrid VAR compensator with improved efficiency

Directory of Open Access Journals (Sweden)

V. V. Burlaka

2015-03-01

Full Text Available In modern electrical networks thyristor-switched capacitors (TSC are most used devices for VAR compensation. These devices don’t contain rotating parts and mechanical contacts, provide a stepwise control of reactive power and no generation of harmonics to the network. However, with the help of TSC it’s not possible to ensure smooth control of reactive power and capacitor banks (CB are exposed to the negative impact of higher harmonic components of the network voltage. Hybrid VAR compensator don’t have such drawbacks. It consists of active filter (AF and capacitor bank with discrete regulation. The main drawback of such systems is the necessity of accessing all six terminals of CB, while most of them are manufactured with three terminals, internally delta-connected. In the article, the topology and control system of hybrid VAR compensator free from beforementioned drawback, is proposed. The control system provides operating modes of overcompensation or undercompensation reactive power. VAR distribution regulator performs redistribution of reactive power between active filter and capacitor banks with the condition to minimize active filter’s power. Scheme of the hybrid VAR compensator, which includes a three-phase three-terminal delta-connected capacitor banks, is shown. Proposed approach allows to provide smooth control of reactive power, isolate the capacitor bank from harmonic currents and use a more effective low-voltage power components

Teaching Multilevel Adult ESL Classes. ERIC Digest.

Science.gov (United States)

Shank, Cathy C.; Terrill, Lynda R.

Teachers in multilevel adult English-as-a-Second-Language classes are challenged to use a variety of materials, activities, and techniques to engage the interest of the learners and assist them in their educational goals. This digest recommends ways to choose and organize content for multilevel classes, explains grouping strategies, discusses a…

Multilevel Higher-Order Item Response Theory Models

Science.gov (United States)

Huang, Hung-Yu; Wang, Wen-Chung

2014-01-01

In the social sciences, latent traits often have a hierarchical structure, and data can be sampled from multiple levels. Both hierarchical latent traits and multilevel data can occur simultaneously. In this study, we developed a general class of item response theory models to accommodate both hierarchical latent traits and multilevel data. The…

Ultrarelativistic cascades and strangeness production

International Nuclear Information System (INIS)

Kahana, D.E.; Kahana, S.H.

1998-02-01

A two phase cascade, LUCIFER II, developed for the treatment of ultra high energy Ion-Ion collisions is applied to the production of strangeness at SPS energies. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the CERN SPS

Realization of nuclear track filters and their applications to the study of environmental aerosol samples

International Nuclear Information System (INIS)

Guo Shilun

1993-01-01

Detailed study of the behaviours of radon decay products requires the knowledge of environmental aerosols. A combination of devices and instruments have been tested to be superior in study of aerosol characteristics. Nuclear track filters and cascade track filter impactor are basic devices, which bring the functions of α -spectrometer, scanning electron microscope and electron microprobe into full play. This paper describes how to use these devices and instruments to collect aerosols, to determine aerosol radioactivity, size distribution and elemental compositions and to determine the concentration of aerosols in air as a function of aerosol sizes, which are important parameters in dominating the interactions between aerosol and radon decay products. (author). 15 refs, 7 figs

Improving the precision of the keyword-matching pornographic text filtering method using a hybrid model.

Science.gov (United States)

Su, Gui-yang; Li, Jian-hua; Ma, Ying-hua; Li, Sheng-hong

2004-09-01

With the flooding of pornographic information on the Internet, how to keep people away from that offensive information is becoming one of the most important research areas in network information security. Some applications which can block or filter such information are used. Approaches in those systems can be roughly classified into two kinds: metadata based and content based. With the development of distributed technologies, content based filtering technologies will play a more and more important role in filtering systems. Keyword matching is a content based method used widely in harmful text filtering. Experiments to evaluate the recall and precision of the method showed that the precision of the method is not satisfactory, though the recall of the method is rather high. According to the results, a new pornographic text filtering model based on reconfirming is put forward. Experiments showed that the model is practical, has less loss of recall than the single keyword matching method, and has higher precision.

Correlated evolution of male and female reproductive traits drive a cascading effect of reinforcement in Drosophila yakuba

Science.gov (United States)

Comeault, Aaron A.; Venkat, Aarti; Matute, Daniel R.

2016-01-01

Selection against maladaptive hybridization can drive the evolution of reproductive isolation in a process called reinforcement. While the importance of reinforcement in evolution has been historically debated, many examples now exist. Despite these examples, we typically lack a detailed understanding of the mechanisms limiting the spread of reinforced phenotypes throughout a species' range. Here we address this issue in the fruit fly Drosophila yakuba, a species that hybridizes with its sister species D. santomea and is undergoing reinforcement in a well-defined hybrid zone on the island of São Tomé. Within this region, female D. yakuba show increased postmating-prezygotic (gametic) isolation towards D. santomea when compared with females from allopatric populations. We use a combination of natural collections, fertility assays, and experimental evolution to understand why reinforced gametic isolation in D. yakuba is confined to this hybrid zone. We show that, among other traits, D. yakuba males from sympatric populations sire fewer progeny than allopatric males when mated to allopatric D. yakuba females. Our results provide a novel example of reinforcement acting on a postmating-prezygotic trait in males, resulting in a cascade of reproductive isolation among conspecific populations. PMID:27440664

Fabrication of Activated Rice Husk Charcoal by Slip Casting as a Hybrid Material for Water Filter Aid

International Nuclear Information System (INIS)

Tuaprakone, T; Wongphaet, N; Wasanapiarnpong, T

2011-01-01

Activated charcoal has been widely used as an odor absorbent in household and water purification industry. Filtration equipment for drinking water generally consists of four parts, which are microporous membrane (porous alumina ceramic or diatomite, or porous polymer), odor absorbent (activated carbon), hard water treatment (ion exchange resin), and UV irradiation. Ceramic filter aid is usually prepared by slip casting of alumina or diatomite. The membrane offers high flux, high porosity and maximum pore size does not exceed 0.3 μm. This study investigated the fabrication of hybrid activated charcoal tube for water filtration and odor absorption by slip casting. The suitable rice husk charcoal and water ratio was 48 to 52 wt% by weight with 1.5wt% (by dry basis) of CMC binder. The green rice husk charcoal bodies were dried and fired between 700-900 deg. C in reduction atmosphere. The resulting prepared slip in high speed porcelain pot for 60 min and sintered at 700 deg. C for 1 h showed the highest specific surface area as 174.95 m 2 /g. The characterizations of microstructure and pore size distribution as a function of particle size were investigated.

Fabrication of Activated Rice Husk Charcoal by Slip Casting as a Hybrid Material for Water Filter Aid

Science.gov (United States)

Tuaprakone, T.; Wongphaet, N.; Wasanapiarnpong, T.

2011-04-01

Activated charcoal has been widely used as an odor absorbent in household and water purification industry. Filtration equipment for drinking water generally consists of four parts, which are microporous membrane (porous alumina ceramic or diatomite, or porous polymer), odor absorbent (activated carbon), hard water treatment (ion exchange resin), and UV irradiation. Ceramic filter aid is usually prepared by slip casting of alumina or diatomite. The membrane offers high flux, high porosity and maximum pore size does not exceed 0.3 μm. This study investigated the fabrication of hybrid activated charcoal tube for water filtration and odor absorption by slip casting. The suitable rice husk charcoal and water ratio was 48 to 52 wt% by weight with 1.5wt% (by dry basis) of CMC binder. The green rice husk charcoal bodies were dried and fired between 700-900 °C in reduction atmosphere. The resulting prepared slip in high speed porcelain pot for 60 min and sintered at 700 °C for 1 h showed the highest specific surface area as 174.95 m2/g. The characterizations of microstructure and pore size distribution as a function of particle size were investigated.

Fabrication of Activated Rice Husk Charcoal by Slip Casting as a Hybrid Material for Water Filter Aid

Energy Technology Data Exchange (ETDEWEB)

Tuaprakone, T; Wongphaet, N; Wasanapiarnpong, T, E-mail: tonggogo@hotmail.com [Research Unit of Advanced Ceramic, Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok (Thailand)

2011-04-15

Activated charcoal has been widely used as an odor absorbent in household and water purification industry. Filtration equipment for drinking water generally consists of four parts, which are microporous membrane (porous alumina ceramic or diatomite, or porous polymer), odor absorbent (activated carbon), hard water treatment (ion exchange resin), and UV irradiation. Ceramic filter aid is usually prepared by slip casting of alumina or diatomite. The membrane offers high flux, high porosity and maximum pore size does not exceed 0.3 {mu}m. This study investigated the fabrication of hybrid activated charcoal tube for water filtration and odor absorption by slip casting. The suitable rice husk charcoal and water ratio was 48 to 52 wt% by weight with 1.5wt% (by dry basis) of CMC binder. The green rice husk charcoal bodies were dried and fired between 700-900 deg. C in reduction atmosphere. The resulting prepared slip in high speed porcelain pot for 60 min and sintered at 700 deg. C for 1 h showed the highest specific surface area as 174.95 m{sup 2}/g. The characterizations of microstructure and pore size distribution as a function of particle size were investigated.

Inferring network structure from cascades

Science.gov (United States)

Ghonge, Sushrut; Vural, Dervis Can

2017-07-01

Many physical, biological, and social phenomena can be described by cascades taking place on a network. Often, the activity can be empirically observed, but not the underlying network of interactions. In this paper we offer three topological methods to infer the structure of any directed network given a set of cascade arrival times. Our formulas hold for a very general class of models where the activation probability of a node is a generic function of its degree and the number of its active neighbors. We report high success rates for synthetic and real networks, for several different cascade models.

[Sizes of bacterial cells in soils determined by cascade filtration technique].

Science.gov (United States)

Polianskaia, L M; Gorodnichev, R B; Zviagintsev, D G

2013-01-01

This paper studies the number of bacteria in typical chernozem and mountain-meadow soil by the traditional method and the cascade filtration technique. The total number of bacteria in these soils, which was obtained in filters of different diameters during filtering the suspension of a certain amount, is 1.5-5 times higher than that obtained by the traditional method. In the structure of the bacterial biomass in both soils, the biomass of bacterial cells with a diameter of 0.38-0.43 microm was dominating by 8-90%. In the typical chernozem, the biomass of cells with a diameter of 0.17 microm was slightly more than 1%; in the mountain-meadow soil, the percentage of the biomass of cells with a diameter of 0.17 microm increased by 5%. The average volume and diameter of the bacteria in the studied soils were calculated. In typical chernozem, the average volume of bacterial cells was equal to 0.0046 microm3 and the diameter was 0.206 microm. In the mountain-meadow soils, these values were slightly lower, 0.0038 microm3 and 0.194 microm, respectively. The biomass of the bacterial cells, which is usually calculated based on the cell volume of 0.1 microm3, is overestimated by about five times when counting the number on the filters. The percentage of the real biomass of soil bacteria is traditionally much lower than that estimated.

Versatile tunable current-mode universal biquadratic filter using MO-DVCCs and MOSFET-based electronic resistors.

Science.gov (United States)

Chen, Hua-Pin

2014-01-01

This paper presents a versatile tunable current-mode universal biquadratic filter with four-input and three-output employing only two multioutput differential voltage current conveyors (MO-DVCCs), two grounded capacitors, and a well-known method for replacement of three grounded resistors by MOSFET-based electronic resistors. The proposed configuration exhibits high-output impedance which is important for easy cascading in the current-mode operations. The proposed circuit can be used as either a two-input three-output circuit or a three-input single-output circuit. In the operation of two-input three-output circuit, the bandpass, highpass, and bandreject filtering responses can be realized simultaneously while the allpass filtering response can be easily obtained by connecting appropriated output current directly without using additional stages. In the operation of three-input single-output circuit, all five generic filtering functions can be easily realized by selecting different three-input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no inverting-type input current signals are imposed. All the passive and active sensitivities are low. Postlayout simulations were carried out to verify the functionality of the design.

Versatile Tunable Current-Mode Universal Biquadratic Filter Using MO-DVCCs and MOSFET-Based Electronic Resistors

Directory of Open Access Journals (Sweden)

Hua-Pin Chen

2014-01-01

Full Text Available This paper presents a versatile tunable current-mode universal biquadratic filter with four-input and three-output employing only two multioutput differential voltage current conveyors (MO-DVCCs, two grounded capacitors, and a well-known method for replacement of three grounded resistors by MOSFET-based electronic resistors. The proposed configuration exhibits high-output impedance which is important for easy cascading in the current-mode operations. The proposed circuit can be used as either a two-input three-output circuit or a three-input single-output circuit. In the operation of two-input three-output circuit, the bandpass, highpass, and bandreject filtering responses can be realized simultaneously while the allpass filtering response can be easily obtained by connecting appropriated output current directly without using additional stages. In the operation of three-input single-output circuit, all five generic filtering functions can be easily realized by selecting different three-input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no inverting-type input current signals are imposed. All the passive and active sensitivities are low. Postlayout simulations were carried out to verify the functionality of the design.

Abnormal cascading failure spreading on complex networks

International Nuclear Information System (INIS)

Wang, Jianwei; Sun, Enhui; Xu, Bo; Li, Peng; Ni, Chengzhang

2016-01-01

Applying the mechanism of the preferential selection of the flow destination, we develop a new method to quantify the initial load on an edge, of which the flow is transported along the path with the shortest edge weight between two nodes. Considering the node weight, we propose a cascading model on the edge and investigate cascading dynamics induced by the removal of the edge with the largest load. We perform simulated attacks on four types of constructed networks and two actual networks and observe an interesting and counterintuitive phenomenon of the cascading spreading, i.e., gradually improving the capacity of nodes does not lead to the monotonous increase in the robustness of these networks against cascading failures. The non monotonous behavior of cascading dynamics is well explained by the analysis on a simple graph. We additionally study the effect of the parameter of the node weight on cascading dynamics and evaluate the network robustness by a new metric.

Particle filtering with path sampling and an application to a bimodal ocean current model

International Nuclear Information System (INIS)

Weare, Jonathan

2009-01-01

This paper introduces a recursive particle filtering algorithm designed to filter high dimensional systems with complicated non-linear and non-Gaussian effects. The method incorporates a parallel marginalization (PMMC) step in conjunction with the hybrid Monte Carlo (HMC) scheme to improve samples generated by standard particle filters. Parallel marginalization is an efficient Markov chain Monte Carlo (MCMC) strategy that uses lower dimensional approximate marginal distributions of the target distribution to accelerate equilibration. As a validation the algorithm is tested on a 2516 dimensional, bimodal, stochastic model motivated by the Kuroshio current that runs along the Japanese coast. The results of this test indicate that the method is an attractive alternative for problems that require the generality of a particle filter but have been inaccessible due to the limitations of standard particle filtering strategies.

Multilevel Cultural Issues

NARCIS (Netherlands)

van Herk, H.; Fischer, Ronald; van Herk, Hester; Torelli, Carlos J.

2017-01-01

Multi-level structures are omnipresent. Consumers live in geographical locations, shop in specific stores, or are members of clubs. Consumers who belong to the same group share characteristics and are expected to be more similar than consumers belonging to another group. In data analysis this

Gas separation performance of tapered cascade with membrane

International Nuclear Information System (INIS)

Ohno, Masayoshi; Morisue, Tetsuo; Ozaki, Osamu; Miyauchi, Terukatsu.

1978-01-01

Membrane gas separation cascades are analyzed at steady state. The method of calculating the flow rate and concentration profiles in the cascade are examined, using formulas expressing the various membrane separation cell characteristics. The method adopted is applicable to relatively high concentrations and separation factors. Considerations are further given on the steady state performance of four theoretical forms of cascade: (a) with common value of cut for all stages, (b) with symmetric separation cells, (c) with no mixing at the junction at each stage, and (d) ideal cascade. The analysis showed that, with membrane cells, the ideal cascade would have a pressure ratio varying from stage to stage. The symmetric separation cascade would provide a separation performance lower than the ideal cascade on account of the mixing at the junctions of streams possessing different concentrations, whereas the cut and separation factor of the no-mixing cascade requiring minimum membrane area exhibits zig-zag curves when plotted against stage number. Both these circumstances contribute to the lower separation performance obtained with these two forms as compared with the ideal cascade, and results in larger total membrane area; but these semi-ideal forms retain the advantage of easy practical treatment with their pressure ratio common to all stages. (auth.)

Ultrarelativistic cascades and strangeness production

Energy Technology Data Exchange (ETDEWEB)

Kahana, D.E. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.

1998-08-24

A two-phase cascade code, LUCIFER II, developed for the treatment of ultra high energy-ion-ion collisions is applied to the production of strangeness at SPS energies {radical}(s)=17-20. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy-ion experiments at the CERN SPS. (orig.) 26 refs.

Ultrarelativistic cascades and strangeness production

International Nuclear Information System (INIS)

Kahana, D.E.; Kahana, S.H.

1998-01-01

A two-phase cascade code, LUCIFER II, developed for the treatment of ultra high energy-ion-ion collisions is applied to the production of strangeness at SPS energies √(s)=17-20. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy-ion experiments at the CERN SPS. (orig.)

MAPK cascades in guard cell signal transduction

Directory of Open Access Journals (Sweden)

Yuree eLee

2016-02-01

Full Text Available Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions.

Low-Loss Hollow Waveguide Fibers for Mid-Infrared Quantum Cascade Laser Sensing Applications

Directory of Open Access Journals (Sweden)

James A. Harrington

2013-01-01

Full Text Available We report on single mode optical transmission of hollow core glass waveguides (HWG coupled with an external cavity mid-IR quantum cascade lasers (QCLs. The QCL mode results perfectly matched to the hybrid HE11 waveguide mode and the higher losses TE-like modes have efficiently suppressed by the deposited inner dielectric coating. Optical losses down to 0.44 dB/m and output beam divergence of ~5 mrad were measured. Using a HGW fiber with internal core size of 300 µm we obtained single mode laser transmission at 10.54 µm and successful employed it in a quartz enhanced photoacoustic gas sensor setup.

Defect accumulation under cascade damage conditions

DEFF Research Database (Denmark)

Trinkaus, H.; Singh, B.N.; Woo, C.H.

1994-01-01

in terms of this reaction kinetics taking into account cluster production, dissociation, migration and annihilation at extended sinks. Microstructural features which are characteristic of cascade damage and cannot be explained in terms of the conventional single defect reaction kinetics are emphasized......There is now ample evidence from both experimental and computer simulation studies that in displacement cascades not only intense recombination takes place but also efficient clustering of both self-interstitial atoms (SIAs) and vacancies. The size distributions of the two types of defects produced...... reactions kinetics associated with the specific features of cascade damage is described, with emphasis on asymmetries between SIA and vacancy type defects concerning their production, stability, mobility and interactions with other defects. Defect accumulation under cascade damage conditions is discussed...

Multi-level converter with auxiliary resonant-commutated pole

NARCIS (Netherlands)

Dijkhuizen, F.R.; Duarte, J.L.; Groningen, van W.D.H.

1998-01-01

The family of multi-level power converters offers advantages for high-power, high-voltage systems. A multi-level nested-cell structure has the attractive feature of static and dynamic voltage sharing among the switches. This is achieved by using clamping capacitors (floating capacitors) rather than

A multilevel evolutionary framework for sustainability analysis

Directory of Open Access Journals (Sweden)

Timothy M. Waring

2015-06-01

Full Text Available Sustainability theory can help achieve desirable social-ecological states by generalizing lessons across contexts and improving the design of sustainability interventions. To accomplish these goals, we argue that theory in sustainability science must (1 explain the emergence and persistence of social-ecological states, (2 account for endogenous cultural change, (3 incorporate cooperation dynamics, and (4 address the complexities of multilevel social-ecological interactions. We suggest that cultural evolutionary theory broadly, and cultural multilevel selection in particular, can improve on these fronts. We outline a multilevel evolutionary framework for describing social-ecological change and detail how multilevel cooperative dynamics can determine outcomes in environmental dilemmas. We show how this framework complements existing sustainability frameworks with a description of the emergence and persistence of sustainable institutions and behavior, a means to generalize causal patterns across social-ecological contexts, and a heuristic for designing and evaluating effective sustainability interventions. We support these assertions with case examples from developed and developing countries in which we track cooperative change at multiple levels of social organization as they impact social-ecological outcomes. Finally, we make suggestions for further theoretical development, empirical testing, and application.

Cascade Error Projection: An Efficient Hardware Learning Algorithm

Science.gov (United States)

Duong, T. A.

1995-01-01

A new learning algorithm termed cascade error projection (CEP) is presented. CEP is an adaption of a constructive architecture from cascade correlation and the dynamical stepsize of A/D conversion from the cascade back propagation algorithm.

Multilevel sparse functional principal component analysis.

Science.gov (United States)

Di, Chongzhi; Crainiceanu, Ciprian M; Jank, Wolfgang S

2014-01-29

We consider analysis of sparsely sampled multilevel functional data, where the basic observational unit is a function and data have a natural hierarchy of basic units. An example is when functions are recorded at multiple visits for each subject. Multilevel functional principal component analysis (MFPCA; Di et al. 2009) was proposed for such data when functions are densely recorded. Here we consider the case when functions are sparsely sampled and may contain only a few observations per function. We exploit the multilevel structure of covariance operators and achieve data reduction by principal component decompositions at both between and within subject levels. We address inherent methodological differences in the sparse sampling context to: 1) estimate the covariance operators; 2) estimate the functional principal component scores; 3) predict the underlying curves. Through simulations the proposed method is able to discover dominating modes of variations and reconstruct underlying curves well even in sparse settings. Our approach is illustrated by two applications, the Sleep Heart Health Study and eBay auctions.

Multi-level trellis coded modulation and multi-stage decoding

Science.gov (United States)

Costello, Daniel J., Jr.; Wu, Jiantian; Lin, Shu

1990-01-01

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 multi-level trellis coded modulation schemes using generalized set partitioning methods are developed for Quadrature Amplitude Modulation (QAM) and Phase Shift Keying (PSK) signal sets. New rotationally invariant multi-level trellis codes which can be combined with differential encoding to resolve phase ambiguity are presented.

Noise propagation in two-step series MAPK cascade.

Directory of Open Access Journals (Sweden)

Venkata Dhananjaneyulu

Full Text Available Series MAPK enzymatic cascades, ubiquitously found in signaling networks, act as signal amplifiers and play a key role in processing information during signal transduction in cells. In activated cascades, cell-to-cell variability or noise is bound to occur and thereby strongly affects the cellular response. Commonly used linearization method (LM applied to Langevin type stochastic model of the MAPK cascade fails to accurately predict intrinsic noise propagation in the cascade. We prove this by using extensive stochastic simulations for various ranges of biochemical parameters. This failure is due to the fact that the LM ignores the nonlinear effects on the noise. However, LM provides a good estimate of the extrinsic noise propagation. We show that the correct estimate of intrinsic noise propagation in signaling networks that contain at least one enzymatic step can be obtained only through stochastic simulations. Noise propagation in the cascade depends on the underlying biochemical parameters which are often unavailable. Based on a combination of global sensitivity analysis (GSA and stochastic simulations, we developed a systematic methodology to characterize noise propagation in the cascade. GSA predicts that noise propagation in MAPK cascade is sensitive to the total number of upstream enzyme molecules and the total number of molecules of the two substrates involved in the cascade. We argue that the general systematic approach proposed and demonstrated on MAPK cascade must accompany noise propagation studies in biological networks.

Short-Term Planning of Hybrid Power System

Science.gov (United States)

Knežević, Goran; Baus, Zoran; Nikolovski, Srete

2016-07-01

In this paper short-term planning algorithm for hybrid power system consist of different types of cascade hydropower plants (run-of-the river, pumped storage, conventional), thermal power plants (coal-fired power plants, combined cycle gas-fired power plants) and wind farms is presented. The optimization process provides a joint bid of the hybrid system, and thus making the operation schedule of hydro and thermal power plants, the operation condition of pumped-storage hydropower plants with the aim of maximizing profits on day ahead market, according to expected hourly electricity prices, the expected local water inflow in certain hydropower plants, and the expected production of electrical energy from the wind farm, taking into account previously contracted bilateral agreement for electricity generation. Optimization process is formulated as hourly-discretized mixed integer linear optimization problem. Optimization model is applied on the case study in order to show general features of the developed model.

Proposed Novel Multiphase-Multilevel Inverter Configuration for Open-End Winding Loads

DEFF Research Database (Denmark)

Padamanaban, Sanjeevi Kumar; Wheeler, Patrick; Blaabjerg, Frede

2016-01-01

This paper presents a new multiphase-multilevel inverter configuration for open-winding loads and suitable for medium power (low-voltage/high-current) applications such as `More Electric Aircraft'. Modular structure comprised of standard dual three-phase voltage source inverter (VSI) along with one...... is developed in this work and overcomes the complexity of standard space vector modulations, easy for real implementation purposes in digital processors. Proposed six-phase multilevel inverter configuration generates multilevel outputs with benefit in comprises with standard multilevel inverter topologies...

Assessment on tracking error performance of Cascade P/PI, NPID and N-Cascade controller for precise positioning of xy table ballscrew drive system