• Title/Summary/Keyword: parallel test

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Parallel Model Feature Extraction to Improve Performance of a BCI System (BCI 시스템의 성능 개선을 위한 병렬 모델 특징 추출)

  • Chum, Pharino;Park, Seung-Min;Sim, Kwee-Bo
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.11
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    • pp.1022-1028
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    • 2013
  • It is well knowns that based on the CSP (Common Spatial Pattern) algorithm, the linear projection of an EEG (Electroencephalography) signal can be made to spaces that optimize the discriminant between two patterns. Sharing disadvantages from linear time invariant systems, CSP suffers from the non-stationary nature of EEGs causing the performance of the classification in a BCI (Brain-Computer Interface) system to drop significantly when comparing the training data and test data. The author has suggested a simple idea based on the parallel model of CSP filters to improve the performance of BCI systems. The model was tested with a simple CSP algorithm (without any elaborate regularizing methods) and a perceptron learning algorithm as a classifier to determine the improvement of the system. The simulation showed that the parallel model could improve classification performance by over 10% compared to conventional CSP methods.

Wind-tunnel study of wake galloping of parallel cables on cable-stayed bridges and its suppression

  • Li, Yongle;Wu, Mengxue;Chen, Xinzhong;Wang, Tao;Liao, Haili
    • Wind and Structures
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    • v.16 no.3
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    • pp.249-261
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    • 2013
  • Flexible stay cables on cable-stayed bridges are three-dimensional. They sag and flex in the complex wind environment, which is a different situation to ideal rigid cylinders in two-dimensional wind flow. Aerodynamic interference and the response characteristics of wake galloping of full-scale parallel cables are potentially different due to three-dimensional flows around cables. This study presents a comprehensive wind tunnel investigation of wake galloping of parallel stay cables using three-dimensional aeroelastic cable models. The wind tunnel study focuses on the large spacing instability range, addressing the effects of cable separation, wind yaw angle, and wind angle of attack on wake galloping response. To investigate the effectiveness of vibration suppression measures, wind tunnel studies on the transversely connected cable systems for two types of connections (flexibility and rigidity) at two positions (mid-span and quarter-span) were also conducted. This experimental study provides useful insights for better understanding the characteristics of wake galloping that will help in establishing a guideline for the wind-resistant design of the cable system on cable-stayed bridges.

Optimum Failure Prediction Model of Steam Generator Tube with Two Parallel Axial Through-Wall Cracks (두개의 평행한 축방향 관통균열이 존재하는 증기발생기 세관의 최적 파손예측모델)

  • Lee, Jin-Ho;Song, Myung-Ho;Choi, Young-Hwan;Kim, Nak-Cheol;Moon, Seong-In;Kim, Young-Jin
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1186-1191
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    • 2003
  • The 40% of wall criterion, which is generally used for the plugging of steam generator tubes, may be applied only to a single crack. In the previous study, a total of 9 failure models were introduced to estimate the local failure of the ligament between cracks and the optimum coalescence model of multiple collinear cracks was determined among these models. It is, however, known that parallel axial cracks are more frequently detected during an in-service inspection than collinear axial cracks. The objective of this study is to determine the plastic collapse model which can be applied to the steam generator tube containing two parallel axial through-wall cracks. Nine previously proposed local failure models were selected as the candidates. Subsequently interaction effects between two adjacent cracks were evaluated to screen them. Plastic collapse tests for the plate with two parallel through-wall cracks and finite element analyses were performed for the determination of the optimum plastic collapse model. By comparing the test results with the prediction results obtained from the candidate models, a plastic zone contact model was selected as an optimum model.

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Optimum Global Failure Prediction Model of Inconel 600 Thin Plate with Two Parallel Through-Wall Cracks

  • Moon Seong In;Kim Young Jin;Lee Jin Ho;Song Myung Ho;Choi Young Hwan
    • Nuclear Engineering and Technology
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    • v.36 no.4
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    • pp.316-326
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    • 2004
  • The $40\%$ of wall criterion, which is generally used for the plugging of steam generator tubes, is applied only to a single crack. In a previous study, a total number of 9 failure models were proposed to estimate the local failure of the ligament between cracks, and the optimum coalescence model of multiple collinear cracks was determined among these models. It is, however known that parallel axial cracks are more frequently detected than collinear axial cracks during an in-service inspection. The objective of this study is to determine the plastic collapse model that can be applied to steam generator tubes containing two parallel axial through-wall cracks. Three previously proposed local failure models were selected as the candidates. Subsequently, the interaction effects between two adjacent cracks were evaluated to screen them. Plastic collapse tests for the plate with two parallel through-wall cracks and finite element analyses were performed to determine the optimum plastic collapse model. By comparing the test results with the prediction results obtained from the candidate models, a COD base model was selected as an optimum model.

Design and Control of a Wearable Robot (Wearable Robot Arm의 제작 및 제어)

  • Jeong, Youn-Koo;Kim, Yoon-Kyong;Kim, Kyung-Hwan;Park, Jong-Oh
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.277-282
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    • 2001
  • As human-friendly robot techniques improve, the concept of the wearability of robotic arms becomes important. A master arm that detects human arm motion and provides virtual forces to the operator is an embodied concept of a wearable robotic arm. In this study, we design a 7 DOF wearable robotic arm with high joint torques. An operator wearing this robotic arm can move around freely because this robotic arm was designed to have its fixed point at the shoulder part of the operator. The proposed robotic arm uses parallel mechanisms at the shoulder part and the wrist part on the model of the human muscular structure of an upper limb. To reduce the computational load in solving the forward kinematics and to prevent singularity motions of the parallel mechanism, yawing motion of the parallel mechanisms was separated using a slip ling mechanism. The total weight of the proposed robotic arm is about 4 kg. An experimental result of force tracking test for the pneumatic control system and an application example for VR robot are described to show the validity of the robot.

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Performance Analysis of Anti-islanding Function for Grid-connected PV Inverter Systems under Parallel Connections (병렬운전하는 계통연계형 태양광 발전용 인버터의 단독운전 검출 성능 분석)

  • Jung, Young-Seok;Yu, Byung-Gyu;Kang, Gi-Hwa
    • Journal of the Korean Solar Energy Society
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    • v.33 no.5
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    • pp.34-40
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    • 2013
  • Islanding phenomenon of photovoltaic system is undesirable because it leads to a safety hazard to utility service personnel and may cause damage to power generation and power supply facilities as a result of unsynchronized re-closure. Anti-islanding protection is an important technical requirement for grid-connected PV system. Until now, various anti-islanding methods for detecting and preventing islanding of photovoltaic and other distributed generations have been proposed. Most of them are focusing on the anti-islanding performance of single PV system according to the related international and domestic standard test procedures. There are few studies on the islanding phenomenon for multiple photovoltaic operation in parallel. This paper presents performance analysis of anti-islanding function for grid-connected PV inverter systems when several PV inverters are connected in parallel.

Uncertainty and Compensation on the cell for Measurement of the Solid Permittivity Materials (고체 유전율 측정용 cell의 불확도 분석과 보상)

  • Kim, Han-Jun;Kang, Jeon-Hong;Yu, Kwang-Min;Hyun, Lee-Sei;Koo, Kyung-Wan;Han, Sang-Ok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.482-483
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    • 2007
  • For measurement of dielectric constants, the commercial parallel plate electrodes system with guard-ring electrode have been widely used up to now. The capacitance derived from the parallel plate electrodes capacitor with guard-ring electrode is calculated by the equation of ($C={\epsilon}\;{\cdot}\;\frac{area\;of\;electrod}{distance\;between\;electrodes}$). Therefore, in parallel plate electrode capacitor, the diameter of the guarded electrode, the gap size between guarded electrode and guard ring, and distance between two active electrode should be measured precisely to calculate dielectric constants from the measured capacitance. Consequently their mechanical measurement uncertainties are directly contributed. Especially the air-gap between the electrodes and dielectric specimen at the system must be existed and the measurement error derived from the air-gap is impossible to evaluate as measurement uncertainties. In this study, we analyze the uncertainty of the commercial dielectric constant test cell using 3 kinds CRMs.

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A PARALLEL PRECONDITIONER FOR GENERALIZED EIGENVALUE PROBLEMS BY CG-TYPE METHOD

  • MA, SANGBACK;JANG, HO-JONG
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.5 no.2
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    • pp.63-69
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    • 2001
  • In this study, we shall be concerned with computing in parallel a few of the smallest eigenvalues and their corresponding eigenvectors of the eigenvalue problem, $Ax={\lambda}Bx$, where A is symmetric, and B is symmetric positive definite. Both A and B are large and sparse. Recently iterative algorithms based on the optimization of the Rayleigh quotient have been developed, and CG scheme for the optimization of the Rayleigh quotient has been proven a very attractive and promising technique for large sparse eigenproblems for small extreme eigenvalues. As in the case of a system of linear equations, successful application of the CG scheme to eigenproblems depends also upon the preconditioning techniques. A proper choice of the preconditioner significantly improves the convergence of the CG scheme. The idea underlying the present work is a parallel computation of the Multi-Color Block SSOR preconditioning for the CG optimization of the Rayleigh quotient together with deflation techniques. Multi-Coloring is a simple technique to obatin the parallelism of order n, where n is the dimension of the matrix. Block SSOR is a symmetric preconditioner which is expected to minimize the interprocessor communication due to the blocking. We implemented the results on the CRAY-T3E with 128 nodes. The MPI(Message Passing Interface) library was adopted for the interprocessor communications. The test problems were drawn from the discretizations of partial differential equations by finite difference methods.

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Equivalent Parallel Capacitance Cancellation of Common Mode Chokes Using Negative Impedance Converter for Common Mode Noise Reduction

  • Dong, Guangdong;Zhang, Fanghua
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1326-1335
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    • 2019
  • Common mode (CM) chokes are a crucial part in EMI filters for mitigating the electromagnetic interference (EMI) of switched-mode power supplies (SMPS) and for meeting electromagnetic compatibility standards. However, the parasitic capacitances of a CM choke deteriorate its high frequency filtering performance, which results in increases in the design cycle and cost of EMI filters. Therefore, this paper introduces a negative capacitance generated by a negative impedance converter (NIC) to cancel the influence of equivalent parallel capacitance (EPC). In this paper, based on a CM choke equivalent circuit, the EPCs of CM choke windings are accurately calculated by measuring their impedance. The negative capacitance is designed quantitatively and the EPC cancellation mechanisms are analyzed. The impedance of the CM choke in parallel with negative capacitances is tested and compared with the original CM choke using an impedance analyzer. Moreover, a CL type CM filter is added to a fabricated NIC prototype, and the insertion loss of the prototype is measured to verify the cancellation effect. The prototype is applied to a power converter to test the CM conducted noise. Both small signal and EMI measurement results show that the proposed technique can effectively cancel the EPCs and improve the CM filter's high frequency filtering performance.

Parallelization of a Purely Functional Bisimulation Algorithm

  • Ahn, Ki Yung
    • Journal of the Korea Society of Computer and Information
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    • v.26 no.1
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    • pp.11-17
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    • 2021
  • In this paper, we demonstrate a performance boost by parallelizing a purely functional bisimulation algorithm on a multicore processor machine. The key idea of this parallelization is exploiting the referential transparency of purely functional programs to minimize refactoring of the original implementation without any parallel constructs. Both original and parallel implementations are written in Haskell, a purely functional programming language. The change from the original program to the parallel program is minuscule, maintaining almost original structure of the program. Through benchmark, we show that the proposed parallelization doubles the performance of the bisimulation test compared to the original non-parallel implementation. We also shaw that similar performance boost is also possible for a memoized version of the bisimulation implementation.