• Title/Summary/Keyword: Adaptive mechanism

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A Study on the Parameter Adaptive Current Controlled PWM Inverter for AC Drives. (교류전동기를 위한 Parameter Adaptive Control 방식의 PWM 인버터에 관한 연구)

  • 황영문;안진우
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.4
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    • pp.259-266
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    • 1987
  • In order to drive motor control system precisely, the motor is to be controlled by mmfs and current with sinusoidal waveforms. In this paper the Delta Modulation (DM) Technique is used for generating PWM pulse with sinusoidal waveform. However the motor currents yet contain odd harmonics due to leakage inductances, speed and exitation. To reduce harmonics, the parameter adaptive control method is introduced. That is, Req.C parameter of Delta Modulator is controlled adaptively by parameter adaptor. The adaptive signal is achieved by the difference between motor current and reference waveform, and this signal is converted to the voltage commend signal by adaptive mechanism. The test reslts show that this system is operated smoothly over a wide range of motor speed and motor current is controlled to be sinusoidal waveform adaptively.

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Posterior density estimation for structural parameters using improved differential evolution adaptive Metropolis algorithm

  • Zhou, Jin;Mita, Akira;Mei, Liu
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.735-749
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    • 2015
  • The major difficulty of using Bayesian probabilistic inference for system identification is to obtain the posterior probability density of parameters conditioned by the measured response. The posterior density of structural parameters indicates how plausible each model is when considering the uncertainty of prediction errors. The Markov chain Monte Carlo (MCMC) method is a widespread medium for posterior inference but its convergence is often slow. The differential evolution adaptive Metropolis-Hasting (DREAM) algorithm boasts a population-based mechanism, which nms multiple different Markov chains simultaneously, and a global optimum exploration ability. This paper proposes an improved differential evolution adaptive Metropolis-Hasting algorithm (IDREAM) strategy to estimate the posterior density of structural parameters. The main benefit of IDREAM is its efficient MCMC simulation through its use of the adaptive Metropolis (AM) method with a mutation strategy for ensuring quick convergence and robust solutions. Its effectiveness was demonstrated in simulations on identifying the structural parameters with limited output data and noise polluted measurements.

Design of Reliable Adaptive Fitter with Fault Tolerance Using DSP (DSP를 이용한 고장허용을 갖는 신뢰 적응 필터 설계)

  • 유동완;이전우;서보혁
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.50 no.1
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    • pp.8-13
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    • 2001
  • LMS algorithm has been used for plant identifier and noise cancellation. This algorithm has been researched for performance enhancement of filtering. The design and development of a reliable system has been becoming a key issue in industry field because the reliability of a system is considered as an important factor to perform the system's function successfully. And the computing with reliability and fault tolerance is a important factor in the case of aviation, system communication, and nuclear plant. This paper presents design of reliable adaptive filter with fault tolerance. Generally, redundancy is used for reliability. In this case it needs computing or circuit for voting mechanism, or fault detection. Therefore it has simple computing, and practicality for application. And in this paper, reliability of adaptive filter is analyzed. The effectiveness of the proposed adaptive filter is demonstrated to the case studies of plant identifier and noise cancellation by using DSP.

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MRAS Based Speed Estimator for Sensorless Vector Control of a Linear Induction Motor with Improved Adaptation Mechanisms

  • Holakooie, Mohammad Hosein;Taheri, Asghar;Sharifian, Mohammad Bagher Bannae
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1274-1285
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    • 2015
  • This paper deals with model reference adaptive system (MRAS) speed estimators based on a secondary flux for linear induction motors (LIMs). The operation of these estimators significantly depends on an adaptation mechanism. Fixed-gain PI controller is the most common adaptation mechanism that may fail to estimate the speed correctly in different conditions, such as variation in machine parameters and noisy environment. Two adaptation mechanisms are proposed to improve LIM drive system performance, particularly at very low speed. The first adaptation mechanism is based on fuzzy theory, and the second is obtained from an LIM mechanical model. Compared with a conventional PI controller, the proposed adaptation mechanisms have low sensitivity to both variations of machine parameters and noise. The optimum parameters of adaptation mechanisms are tuned using an offline method through chaotic optimization algorithm (COA) because no design criterion is given to provide these values. The efficiency of MRAS speed estimator is validated by both numerical simulation and real-time hardware-in-the-loop (HIL) implementations. Results indicate that the proposed adaptation mechanisms improve performance of MRAS speed estimator.

A Branch Prediction Mechanism With Adaptive Branch History Length for FAFF Information Processing (농림수산식품분야 정보처리를 위한 적응하는 분기히스토리 길이를 갖는 분기예측 메커니즘)

  • Ko, K.H.;Cho, Y.I.
    • Journal of Practical Agriculture & Fisheries Research
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    • v.13 no.1
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    • pp.3-17
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    • 2011
  • Pipelines of processor have been growing deeper and issue widths wider over the years. If this trend continues, branch misprediction penalty will become very high. Branch misprediction is the single most significant performance limiter for improving processor performance using deeper pipelining. Therefore, more accurate branch predictor becomes an essential part of modem processors for FAFF(Food, Agriculture, Forestry, Fisheries)Information Processing. In this paper, we propose a branch prediction mechanism, using variable length history, which predicts using a bank having higher prediction accuracy among predictions from five banks. Bank 0 is a bimodal predictor which is indexed with the 12 least significant bits of the branch PC. Banks 1,2,3 and 4 are predictors which are indexed with different global history bits and the branch PC. In simulation results, the proposed mechanism outperforms gshare predictors using fixed history length of 12 and 13, up to 6.34% in prediction accuracy. Furthermore, the proposed mechanism outperforms gshare predictors using best history lengths for benchmarks, up to 2.3% in prediction accuracy.

Adaptive Admission Control Mechanism in Differentiated Services Network (인터넷 차별 서비스 망에서 적응적 연결 수락 제어 메커니즘)

  • 이준화;양미정;이우섭;김상하
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.12
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    • pp.83-93
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    • 2003
  • Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

A Study on Production Mechanism of Meta-Knowledge for Effectively Managing Contents and Models (컨텐츠 및 모델의 효과적 관리를 위한 메타-지식 생성 메커니즘 연구)

  • Kim, Chul-Soo
    • The KIPS Transactions:PartB
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    • v.8B no.5
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    • pp.441-446
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    • 2001
  • On global interconnectivity, the activation of real-time and worldwide contents will permeate and impact all aspects of day-to-day life well throughout this century. In managing contents and models, we too will see the impact of this rapidly changing environment. The real time availability of contents pertaining to a companys supply chain through means of the Internet and mobile networks(e.g., the IMT-2000) will necessitate a change in decision-making processes for effective management of contents and models. To increase the availability of many contents and models, a management system should have adaptive function in proving adequate content and model for companies. In the respect of management of contents and models, this paper discusses a production mechanism of meta-knowledge for effectively managing contents and models. Through two experimental analyses with the production mechanism, it is proven that the system enabling adaptive contents and models provision goes beyond existing ones in view of efficiency of management of contents and models in the wire and wireless networks.

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Adaptive Contention Window Mechanism for Enhancing Throughput in HomePlug AV Networks (HomePlug AV 네트워크에서의 성능 향상을 위한 적응적 Contention Window 조절 방식)

  • Yoon, Sung-Guk;Yun, Jeong-Kyun;Kim, Byung-Seung;Bahk, Sae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.5B
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    • pp.318-325
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    • 2008
  • HomePlug AV(HPAV) is the standard for distribution of Audio/video content as well as data within the home by using the power line. It uses a hybrid access mechanism that combines TDMA with CSMA/CA for MAC technology. The CSMA/CA protocol in HPAV has two main control blobs that can be used for access control: contention window(CW) size and deferral counter(DC). In this paper, we extensively investigate the impacts of CW and DC on performance through simulations, and propose an adaptive mechanism that adjusts the CW size to enhance the throughput in HPAV MAC. We find that the CW size is more influential on performance than the DC. Therefore, to make controlling the network easier, our proposal uses a default value of DC and adjusts the CW size. Our scheme simply increases or decreases the CW size if the network is too busy or too idle, respectively, We compare the performance of our proposal with those of the standard and other competitive schemes in terms of throughput and fairness. Our simulation and analysis results show that our adaptive CW mechanism performs very well under various scenarios.

The Mediating Effect of Empathy on the Relationship between Cultural Intelligence and Intercultural Adaptation in Intercultural Service Encounters

  • KONG, Lan Lan;MA, Zhi Qiang;JI, Sung Ho;LI, Jin
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.2
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    • pp.169-180
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    • 2020
  • Globalization has led to a dramatic increase in intercultural service encounters between services providers and customers from diverse cultural backgrounds. This paper explores the causal relationship between service employees‟ cultural intelligence and adaptive sales behavior in intercultural service encounters, and the mediating effect of cognitive and emotional empathy on this relationship. A quantitative survey methodology was utilized to collect data on 341 salespeople at duty-free shops located on Jeju Island, Korea. Data analysis was conducted using SPSS 18 and Amos 18. The results show that cultural intelligence has a significant impact on cognitive empathy, emotional empathy, and adaptive sales behavior. Cognitive empathy has a positive impact on adaptive sales behavior, whereas the relationship between emotional empathy and adaptive sales behavior is not significant. Additionally, cognitive empathy mediates the relationship of cultural intelligence and adaptive sales behavior. This study has useful managerial implications for employee selection, training, and development in service firms engaged in intercultural service encounters. This study extends prior research on intercultural service encounters by exploring the direct impact of cultural intelligence on intercultural adaptation and the mediating effect of empathy, suggesting the presence of a cognitive mechanism that plays a key role in the impact of cultural intelligence on adaptive sales behavior.

The Relationship among a Father's Rough-and-Tough Play, Child's Emotional Expressiveness and Adaptive Emotional Regulation: The Moderated Mediation Effect of a Father's Play Participation Attitud (아버지의 거친신체놀이, 유아의 정서표현성과 적응적 정서조절의 관계: 아버지 놀이참여태도의 조절된 매개효과)

  • Jihyun Oh
    • Korean Journal of Childcare and Education
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    • v.19 no.1
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    • pp.23-41
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    • 2023
  • Objective: The purpose of this study is to explain in detail the factors of the father's play interaction that predict children's adaptive emotional regulation. This study examined the moderated mediation effect of a father's rough-and-tough play toward a child's emotional expressiveness and the father's play participation attitude on the child's adaptive emotional regulation. Methods: The study participants included 309 fathers of children aged from 3 to 5 years. Data were analyzed using models of the PROCESS Macro. Results: As a result of this research, the relationship of the father's rough-and-tough play with the child's adaptive emotional regulation was that this was indeed mediated by the child's negative emotional expressiveness. Additionally, the father's responsive and fun play attitude moderated the relationship between the father's rough-and-tough play and the child's adaptive emotional regulation. Further, the father's responsive and fun play attitude according to level had a moderated mediation effect. Conclusion/Implications: These results are meaningful in that they derives a mechanism for why and how a father's rough-and-tough play affects children's adaptive emotional regulation.