Further Results on Robust Delay-range-dependent Stability Criteria for Uncertain Neural Networks with Interval Time-varying Delay

Pin-Lin Liu 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5

The problem of robust delay-range-dependent stability analysis of neural networks (NNs) with interval time-varying delay in a given range is investigated in this paper. The relationship between time-varying delay and its lower and upper bounds is taken into account when estimating the upper bound of the Lyapunov functional derivative. By defining a more general type of Lyapunov functionals, some new less conservative delay-dependent stability criteria are established in terms of linear matrix inequalities (LMIs), which can be computed and optimized easily. Meanwhile, the computational complexity of newly obtained stability conditions is reduced because fewer variables are involved. Finally, through four well-known numerical examples used in other literature, it will be shown that proposed stability criteria achieve the improvements over existing ones, as well as the effectiveness of the proposed idea.

Acoustic noise measurement in counter-rotating propellers

Pin Liu,Fumiha Odo,Tengen Murakami,Toshiaki Kanemoto 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

The acoustic noise and flow condition of tandem propellers in a horizontal axis-type tidal stream power unit, which is composed of counter-rotating propellers and double-rotational armature-type generator without traditional stators, were experimentally investigated. The front and rear propellers rotate in opposite directions and drive the inner and outer armatures, respectively; the rotational torque of the front propeller coincides with the torque of the rear propeller. The front blade profile exerts a great effect on noise generation from the tandem propellers, but the effect of the rear blade profile is comparatively small. The sound pressure level is largely concentrated at low frequencies, and most predominant frequencies can be predicted by Hanson’s method. These predominant frequencies are mainly caused by the tip vortex shedding from the front and rear blades in the counter-rotating propellers. The vortex shedding from the front blade does not affect the rear blade. As a result, the acoustic noise is weakened as long as the diameter of the rear propeller is smaller than the diameter of the front propeller.

Further Improvement on Delay-derivative-dependent Stochastic Stability Criteria for Markovian Jumping Neutral-type Interval Time-varying Delay Systems with Mixed Delays

Pin-Lin Liu 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.8

This paper is concerned with the problem of delay-derivative-dependent stability analysis for Markovian jumping neutral-type interval time-varying delay systems with mixed delays. The first, based on the LyapunovKrasovskii stability theory for functional differential equations and the linear matrix inequality approach, a delayrange-dependent condition for neutral-type Markovian jumping systems (NMJSs) with time-varying delays is obtained, which can guarantee global asymptotical stability of these NMJSs. Unlike the previous methods, the upper bound of the discrete delay and neutral delay derivative is taken into consideration even if this upper bound is larger than or equal to 1 (h˙(t) < 1, τ˙(t) < 1). It is proved that the obtained results are less conservative than the existing ones. In our result, the time-varying delays are only assumed to be bounded. This has undoubtedly extended its application range. To better handle the problem on stability for neutral control systems, in which time-varying delaywas involved, a stability criterion with less conservatism was put forward. Moreover, because our results in thispaper are all based on the linear matrix inequality (LMI) approach, we can utilize Matlab’s LMI Control Toolboxto verify the global stability of correlation systems conveniently. As far as we are aware, this paper seems to be thefirst to discuss stability problems for neutral-type Markovian jumping systems with delay-derivative-dependenceand delay-range-dependence.

Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan

Liu, Pin,Shiomi, Norimasa,Kinoue, Yoichi,Setoguchi, Toshiaki,Jin, Ying-Zi Korean Society for Fluid machinery 2014 International journal of fluid machinery and syste Vol.7 No.2

In order to clarify the effect of inlet bellmouth size of semi-opened type axial fan on its performance and flow fields around rotor, fan test and flow field measurements using hotwire anemometer were carried out for 6 kinds of bellmouth size. As results of fan test, the shaft power curve hardly changed, even if the bellmouth size changed. On the other hand, the pressure-rise near best efficiency point became small with the bellmouth size decreasing. Therefore, the value of maximum efficiency became small as the bellmouth size decreased. As results of flow field measurements at fan inlet, the main flow region with large meridional velocity existed near blade tip when the bellmouth size was large. As bellmouth size became smaller, the meridional velocity at fan inlet became smaller and the one at outside of blade tip became larger. As results of flow field measurements at fan outlet, the main flow region existed near rotor hub side.

Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan

Pin Liu,Norimasa Shiomi,Yoichi Kinoue,瀨戶口俊明,Yingzi Jin 한국유체기계학회 2014 International journal of fluid machinery and syste Vol.7 No.2

In order to clarify the effect of inlet bellmouth size of semi-opened type axial fan on its performance and flow fields around rotor, fan test and flow field measurements using hotwire anemometer were carried out for 6 kinds of bellmouth size. As results of fan test, the shaft power curve hardly changed, even if the bellmouth size changed. On the other hand, the pressure-rise near best efficiency point became small with the bellmouth size decreasing. Therefore, the value of maximum efficiency became small as the bellmouth size decreased. As results of flow field measurements at fan inlet, the main flow region with large meridional velocity existed near blade tip when the bellmouth size was large. As bellmouth size became smaller, the meridional velocity at fan inlet became smaller and the one at outside of blade tip became larger. As results of flow field measurements at fan outlet, the main flow region existed near rotor hub side.

FLOW CONDITION AROUND COUNTER ROTATING TYPE PROPELLERS FOR TIDAL STREAM POWER UNIT

Pin LIU,Xuesong WEI,Bin HUANG,Toshiaki KANEMOTO 한국신재생에너지학회 2015 AFORE Vol.2015 No.11

Further Improvement on Delay-range-dependent Stability Criteria for Delayed Recurrent Neural Networks with Interval Time-varying Delays

Pin-Lin Liu 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3

This paper considers the problem of delay-range-dependent stability analysis for a class of delayed recurrent neural networks (DRNNs) with a time-varying delay in a range. Based on the Lyapunov-Krasovskii functional and derive the time derivative of this with integral inequality approach (IIA), new delay- dependent stability criteria for the system are established in terms of linear matrix inequalities (LMIs), which can be solved easily by various efficient convex optimization algorithms. Information about the lower bound of the delay is fully used in the Lyapunov functional. Two examples are given to illustrate the effectiveness and the reduced conservatism of the proposed results.

중국의 전자증거규칙 ―Kuaibo 사례를 중심으로―

류품신 ( Liu Pin Xin ) 아세아여성법학연구소 2017 아세아여성법학 Vol.20 No.-

Kuaibo 사례에서 양측 당사자가 주장하는 사건의 주요 쟁점은 서버와 음란영상물이라는 두 가지 중요 증거의 취득과 보관을 둘러싼 부분에 관한 것으로, 그 핵심 쟁점은 전자증거의 인증문제이다. 즉, 이 두 증거가 피고인과 관계가 있는 것인지에 관한 것이다. 본 사건의 심리에는 중국에서 2010년초 제정된 전자증거인증규칙(電子證据鑒眞規則)을 적용하여야 한다. 국제적으로 통용되는 규칙과 비교해 보면, 중국의 동규칙은 “자아인증(自我鑒眞)”과 “독특한 특징의 확정(獨特特征的確認)”방법에 결함이 존재하며, 많은 부분을 필기기록의 심사와 사건의 내막을 알고 있는 사람들의 법정증언에 의존하고 있다는 점, 그리고 증거라벨제도와 인증추정제도가 아직 건립되어 있지 않고, 인증불능의 법률결과의 설정부족 등의 결함을 내포하고 있다. Kuaibo 사례에서 전자증거인증의 문제는 여전히 규칙의 결함에서 기인한다고 할 수 있다. 비록 Kuaibo사례에서 법원은 새롭게 검증을 위탁하는 방법을 시도함으로써 이를 보완하였으나, 이러한 방법도 유효한 인증이라고 할 수 없으며, 또한 인증규칙의 본래 취지에 위배된다 할 것이다. 최근 중국에서 소위 <양고일부 전자증거규칙(兩高一部電子證据規則)>이 새로이 시행된 후, 전자증거의 인증방법과 법적 결과 등에 있어서 많은 발전을 이루게되어 Kuaibo 사례에서와 같은 증거에 관한 인증문제는 더 이상 발생하지 않도록 방지할 수 있게 되었으나, 동 규칙은 여전히 많은 부분에 있어 부단히 개혁해야 하는 임무도 남겨 두게 되었다. In the Qvod Player (Kuaibo) case, the prosecutors and the defendants had a main dispute on the procedures when collecting and preserving two essential evidences, i.e. the servers and the obscene videos. The prosecutors must show that they are authentic with sufficient evidence. The trial of the case shall apply an authentication rule for digital evidence which has been preliminarily developed in China since 2010. Compared with foreign countries, China’s authentication rules lack the methods of self-authentication and confirmation of distinctive characteristics, rely more on the transcripts and less on the court appearance, fail to establish the labeling evidence authentication and the authentication by presumption systems, and have no legal consequence for failing to authenticate evidence. In the Qvod Player (Kuaibo) case, the authentication issue is the reflection of the rule’s defects. Although the court decided to ask a help from forensic expert’s opinion as a corroborative evidence, this method is insufficient to authenticate the evidence. Such practice is also contrary to the authentication rules of digital evidence. Though the newly formulated Provisions on Several Issues Concerning the Collection, Extraction, Review and Determination of Electronic Data in the Handling of Criminal Cases made a great progress in the method of authentication and the legal consequence, which will avoid the Qvod Player (Kuaibo) case’s problem, it is still not enough. The authentication rules of digital evidence in China still need to be improved.

Characteristics Analysis of Sub-Synchronous Oscillation Caused by DFIG Wind Farm Integrated Into MMC-HVDC System

Lv Pin,Zhai Yuelin,Su Xunwen,Xu Donghui,Liu Lulu,Liu Ziyang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

With the increasing share of renewable energy such as wind energy in power system, flexible DC transmission technology has become an important way to effectively absorb wind energy. But the problem of synchronous sub-synchronous oscillation becomes more and more serious. To reduce the influence of sub-synchronous oscillation on interconnected systems, a Controller for energy conversion system is proposed. It is used to control the synchronous operation of the doubly-fed fan and the rectifier station to connect the doubly-fed wind farm. First, based on the impedance method, a doubly-fed wind farm and multi-module impedance model considering AC/DC dynamic coupling are established. The control energy conversion of wind power generation system, rectifier station and inverter station is designed. Second, according to Nyquist curve and impedance stability criterion, the change of system stability in the process of adjusting controller parameters is observed. Third, the system structure is simulated by MATLAB software. The effectiveness of the controller in the converter station at both ends of MMC is verified. The results show that the new controller can effectively suppress the current offset caused by SSO, and thus improve the power system stability.

Selection of the Approach for Producing a Weighting Scheme for the CSR Evaluation Framework

Pin-Chao Liao,Jiawei Xue,Bingsheng Liu,Dongping Fang 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

Corporate Social Responsibility (CSR) performance is key to project success in the construction industry. Although evaluation tools for CSR have been developed in previous studies, their weighting schemes are easily distorted by inputs from experts with different backgrounds, reducing the reliability of the benchmarking results. This study aims to identify the most suitable approach for a process-based evaluation framework of CSR management (CSR-EF) with a structurally, theoretically valid weighting scheme. The authors compared three approaches for weighting development and chose one that minimizes the heterogeneity of inputs from experts with various backgrounds (e.g., culture, profession, and education levels). The sensitivity of the weighting scheme and the metric priority, along withthe robustness of the scheme, were examined. Contractors’ CSR management was evaluated using the proposed CSR-EF and the results were cross-examined by practitioners from various backgrounds. Results indicated that the Analytic Network Process was the ideal method for developing the CSR-EF weighting scheme. The results providein sights for the development of weighting schemes for multi-criteria decision making. The proposed Equivalent Absolute Deviation (EAD) approach can also be used to examine the robustness of the weighting approach.