• Title/Summary/Keyword: Active State

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Shunt Active Filter for Multi-Level Inverters Using DDSRF with State Delay Controller

  • Rajesh, C.R.;Umayal, S.P.
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.863-870
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    • 2018
  • The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

A Study on IMM-PDAF based Sensor Fusion Method for Compensating Lateral Errors of Detected Vehicles Using Radar and Vision Sensors (레이더와 비전 센서를 이용하여 선행차량의 횡방향 운동상태를 보정하기 위한 IMM-PDAF 기반 센서융합 기법 연구)

  • Jang, Sung-woo;Kang, Yeon-sik
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.8
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    • pp.633-642
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    • 2016
  • It is important for advanced active safety systems and autonomous driving cars to get the accurate estimates of the nearby vehicles in order to increase their safety and performance. This paper proposes a sensor fusion method for radar and vision sensors to accurately estimate the state of the preceding vehicles. In particular, we performed a study on compensating for the lateral state error on automotive radar sensors by using a vision sensor. The proposed method is based on the Interactive Multiple Model(IMM) algorithm, which stochastically integrates the multiple Kalman Filters with the multiple models depending on lateral-compensation mode and radar-single sensor mode. In addition, a Probabilistic Data Association Filter(PDAF) is utilized as a data association method to improve the reliability of the estimates under a cluttered radar environment. A two-step correction method is used in the Kalman filter, which efficiently associates both the radar and vision measurements into single state estimates. Finally, the proposed method is validated through off-line simulations using measurements obtained from a field test in an actual road environment.

A Study on the Crevice Corrosion for Ferritic Stainless Steel by Micro Capillary Tube Method

  • Na Eun-Young;Ko Jae-Yong;Baik Shin-Young
    • Journal of the Korean Electrochemical Society
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    • v.7 no.4
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    • pp.179-182
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    • 2004
  • The aim of this study is to investigate the initiation and propagation of crevice corrosion for ferritic stainless steel in artificial crevice based on micro capillary tube method. The 430 stainless steel in artificial crevice is potentiostatically polarized in different sodium chloride solutions. Potentiodynamic and potentiostatic polarization data were measured in situ. The potentials in the crevice were measured by depth profile using the 0.04 mm diameter micro capillary tube inserted in the crevice. The potentials in the crevice ranged from -220 mV to -360 mV vs SCE from opening to bottom of crevice, which are lower than the external surface potential, -200 mV vs SCE. Such a potential drop induced the change of the metal surface state from passive to active. The surface of metal is located in passive state in -200 mV but the inner surface keeps active state below -220 mV, Thus these results show that the It drop mechanism in the crevice was more objective for evaluation and the method was easier to reproduce. Therefore the potential drop is one of the reasons for crevice corrosion by measuring the potentials in narrow crevice with a new micro measuring system.

Gust Response Alleviation of a Three-dimensional Flexible Wing using Sliding Mode Control (슬라이딩 모드 제어기법을 이용한 3차원 유연날개 돌풍응답 제어)

  • Lee, Sang-Wook;Suk, Jinyoung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.220-225
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    • 2013
  • In this study, active control system using sliding mode control method is presented to achieve the gust response alleviation of a three-dimensional flexible wing model. For this purpose, aeroservoelastic model which is composed of aeroelastic plant, control surface actuator model, and gust model depicting the atmospheric turbulence is formulated in the state space. The aerodynamic force generated by the motion of a trailing edge control surface of a flexible wing is made use of as control means. An active control system combining state feedback sliding mode controller and state estimator based on measured responses such as wing tip acceleration and wing root strain is designed for gust response alleviation of a flexible wing aeroservoelastic model. The performance of the controller designed is demonstrated via numerical simulation for the representative flexible wing model under gust loading conditions.

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A Study on the 3-phase 13.2 kV Solid State Transformer for the DC Distribution (직류 배전망 연계를 위한 3상 13.2kV급 반도체 변압기 시스템에 대한 연구)

  • Jeong, Dong-Keun;Yun, Hyeok-Jin;Park, Si-Ho;Kim, Ho-Sung;Kim, Myoung-Ho;Ryu, Myung-Hyo;Baek, Ju-Won
    • The Transactions of the Korean Institute of Power Electronics
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    • v.26 no.5
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    • pp.315-324
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    • 2021
  • A solid state transformer (SST) that can interface an MVAC of three-phase 13.2 kV and a 1.5 kV DC distribution. SST consists of an AC/DC converter and a DC/DC converter with a high-frequency isolation transformer (HFIT). The AC/DC converter consists of cascaded NPC full-bridge to cope with the MVAC. The DC/DC converter applies a quad active bridge (QAB) topology to reduce the number of the HFIT. Topology analysis and controller design for this specific structure are discussed. In addition, the insulation of HFIT used in DC/DC converters is considered. The discussion is validated using a 300 kVA three-phase SST prototype.

Energy-saving optimization on active disturbance rejection decoupling multivariable control

  • Da-Min Ding;Hai-Ma Yang;Jin Liu;Da-Wei Zhang;Xiao-Hui Jiang
    • Nuclear Engineering and Technology
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    • v.55 no.3
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    • pp.850-860
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    • 2023
  • An industrial control process multiple-input multiple-output (MIMO) coupled system is analyzed in this study as an example of a Loss of Coolant Accident (LOCA) simulation system. Ordinary control algorithms can complete the steady state of the control system and even reduce the response time to some extent, but the entire system still consumes a large amount of energy after reaching the steady state. So a multivariable decoupled energy-saving control method is proposed, and a novel energy-saving function (economic function, Eco-Function) is specially designed based on the active disturbance rejection control algorithm. Simulations and LOCA simulation system tests show that the Eco-function algorithm can cope with the uncertainty of the multivariable system's internal parameters and external disturbances, and it can save up to 67% of energy consumption in maintaining the parameter steady state.

A Secure Active Packet Transfer using Cryptographic Techniques (암호 기술을 이용한 안전한 능동 패킷 전송)

  • 김영수;나중찬;손승원
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.12 no.2
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    • pp.135-145
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    • 2002
  • Active networks represent a new approach to network architecture. Nodes(routers, switches, etc.) can perform computations on user data, while packets can carry programs to be executed on nodes and potentially change the state of them. While active networks provide a flexible network iufrastructure, they are more complex than traditional networks and raise considerable security problems. Nodes are Public resources and are essential to the proper and contract running of many important systems. Therefore, security requirements placed upon the computational environment where the code of packets will be executed must be very strict. Trends of research for active network security are divided into two categories: securing active nodes and securing active packets. For example, packet authentication or monitoring/control methods are for securing active node, but some cryptographic techniques are for the latter. This paper is for transferring active packets securely between active nodes. We propose a new method that can transfer active packets to neighboring active nodes securely, and execute executable code included in those packets in each active node. We use both public key cryptosystem and symmetric key cryptosystem in our scheme

Substrate Ground State Binding Energy Concentration Is Realized as Transition State Stabilization in Physiological Enzyme Catalysis

  • Britt, Billy Mark
    • BMB Reports
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    • v.37 no.5
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    • pp.533-537
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    • 2004
  • Previously published kinetic data on the interactions of seventeen different enzymes with their physiological substrates are re-examined in order to understand the connection between ground state binding energy and transition state stabilization of the enzyme-catalyzed reactions. When the substrate ground state binding energies are normalized by the substrate molar volumes, binding of the substrate to the enzyme active site may be thought of as an energy concentration interaction; that is, binding of the substrate ground state brings in a certain concentration of energy. When kinetic data of the enzyme/substrate interactions are analyzed from this point of view, the following relationships are discovered: 1) smaller substrates possess more binding energy concentrations than do larger substrates with the effect dropping off exponentially, 2) larger enzymes (relative to substrate size) bind both the ground and transition states more tightly than smaller enzymes, and 3) high substrate ground state binding energy concentration is associated with greater reaction transition state stabilization. It is proposed that these observations are inconsistent with the conventional (Haldane) view of enzyme catalysis and are better reconciled with the shifting specificity model for enzyme catalysis.

The study on Failover subsystem of SCADA system (SCADA 시스템의 FAILOVER SUBSYSTEM에 관한 연구)

  • Kim, Young-Tae;Cho, Nam-Bin
    • Proceedings of the KIEE Conference
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    • 1999.07b
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    • pp.835-837
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    • 1999
  • Failover subsystem of computer consists four modes In this paper, These modes will be discussed in more detail. - dual computer mode - failover mode - single computer mode - standby synchronization mode we have suggested the method of dual/redunancy configulation of server computer. Failover is activated by the standby computer, active computer receives a failover request across the inter-computer link immediatly. The active computer controls the scada system and maintains the current state in it's data base and channel system safety.

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