how-net 망의 관계그물 표시법

Zhou Qiang,Feng Songyan 한국어정보학회 2002 한국어정보학 Vol.5ㆍ6 No.-

An Improved Poincaré-like Carleman Linearization Approach for Power System Nonlinear Analysis

Zhou-Qiang Wang,Qi Huang,Chang-hua Zhang 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.2

In order to improve the performance of analysis, it is important to consider the nonlinearity in power system. The Carleman embedding technique (linearization procedure) provides an effective approach in reduction of nonlinear systems. In the approach, a group of differential equations in which the state variables are formed by the original state variables and the vector monomials one can build with products of positive integer powers of them, is constructed. In traditional Carleman linearization technique, the tensor matrix is truncated to form a square matrix, and then regular linear system theory is used to solve the truncated system directly. However, it is found that part of nonlinear information is neglected when truncating the Carleman model. This paper proposes a new approach to solve the problem, by combining the Poincare transformation with the Carleman linearization. Case studies are presented to verify the proposed method. Modal analysis shows that, with traditional Carleman linearization, the calculated contribution factors are not symmetrical, while such problems are avoided in the improved approach.

Research on non-uniform pressure pulsation of the diffuser in a nuclear reactor coolant pump

Zhou, Qiang,Li, Hongkun,Pei, Lin,Zhong, Zuowen Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

The nuclear reactor coolant pump transferring heat energy inherently brings with it the unsteady flow and inevitably threatens to the safe operation of the pump unit, especially with the pressure pulsation induced by the rotor-stator interaction. In this paper, the characteristics of pressure pulsation of the diffuser in a nuclear reactor coolant pump were investigated by the numerical simulation with experimental validation. Pressure pulsation signals measured synchronously from sensors mounted on the radial diffuser of a model pump were analyzed via Welch's method. Frequency components induced by the rotor-stator interaction can be revealed by the diameter mode analysis method. The pressure pulsation of the diffuser is dominated by the blade passing frequency and its harmonics, which are free from the effect of flow rate and rotational speed while the corresponding amplitudes are easily affected by different operational conditions and measuring positions. The non-uniformity is much more affected by the rotational speed than the flow rate. This research is helpful for further work to reduce the pressure pulsation for the reactor coolant pump.

Numerical studies on non-shear and shear flows past a 5:1 rectangular cylinder

Qiang Zhou,Shuyang Cao,Zhiyong Zhou 한국풍공학회 2013 한국풍공학회지 Vol.17 No.4

Large Eddy Simulations (LES) were carried out to investigate the aerodynamic characteristics of a rectangular cylinder with side ratio B/D=5 at Reynolds number Re=22,000 (based on cylinder thickness). Particular attention was devoted to the effects of velocity shear in the oncoming flow. Time-averaged and unsteady flow patterns around the cylinder were studied to enhance understanding of the effects of velocity shear. The simulation results showed that the Strouhal number has no significant variation with oncoming velocity shear, while the peak fluctuation frequency of the drag coefficient becomes identical to that of the lift coefficient with increase in velocity shear. The intermittently-reattached flow that features the aerodynamics of the 5:1 rectangular cylinder in non-shear flow becomes more stably reattached on the high-velocity side, and more stably separated on the low-velocity side. Both the mean and fluctuating drag coefficients increase slightly with increase in velocity shear. The mean and fluctuating lift and moment coefficients increase almost linearly with velocity shear. Lift force acts from the high-velocity side to the low-velocity side, which is similar to that of a circular cylinder but opposite to that of a square cylinder under the same oncoming shear flow.

Shaking table test and numerical analysis of a combined energy dissipation system with metallic yield dampers and oil dampers

Zhou, Qiang,Lu, Xilin Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.2

A shaking table test on a three-story one-bay steel frame model with metallic yield dampers and their parallel connection with oil dampers is carried out to study the dynamic characteristics and seismic performance of the energy dissipation system. It is found from the test that the combined energy dissipation system has favorable reducing vibration effects on structural displacement, and the structural peak acceleration can not evidently be reduced under small intensity seismic excitations, but in most cases the vibration reduction effect is very good under large intensity seismic excitations. Test results also show that stiffness of the energy dissipation devices should match their damping. Dynamic analysis method and mechanics models of these two dampers are proposed. In the analysis method, the force-displacement relationship of the metallic yield damper is represented by an elastic perfectly plastic model, and the behavior of the oil damper is simulated by a velocity and displacement relative model in which the contributions of the oil damper to the damping force and stiffness of the system are considered. Validity of the analytical model and the method is verified through comparison between the results of the shaking table test and numerical analysis.

Research on the Group-type of High Voltage Electric Field Measurement Safety Distance Caution Apparatus

Qiang Zhou,Wei He,Songnong Li,Xingzhe Hou 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.8

This paper introduces a kind of research and application of group-type of high voltage electric field measurement and safety distance caution apparatus based on wireless communication technology, the group-type caution apparatus is combined with a master and multiple slaves, in which the slaves are used to measure electric field and the master is used to monitor the slaves. The master keeps the real-time wireless communication with the slaves, realizing the safety dual monitoring of the high voltage working environment and guaranteeing the personnel safety of live working man. Conduct a working performance test on the site of Chongqing Rongchang 500kV Hongban transmission line I about the stability and accuracy. The test results show that the designer of group-type of HV electric field measurement and safety distance caution apparatus can work stably in the strong electric field environment, besides, it has a good performance in both safety distance exceeding alarm and wireless communication.

A Wolf Colony Search Algorithm Based on the Complex Method for Uninhabited Combat Air Vehicle Path Planning

Qiang Zhou,Yongquan Zhou,Xin Chen 보안공학연구지원센터 2014 International Journal of Hybrid Information Techno Vol.7 No.1

Numerical studies on non-shear and shear flows past a 5:1 rectangular cylinder

Zhou, Qiang,Cao, Shuyang,Zhou, Zhiyong Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.4

Large Eddy Simulations (LES) were carried out to investigate the aerodynamic characteristics of a rectangular cylinder with side ratio B/D=5 at Reynolds number Re=22,000 (based on cylinder thickness). Particular attention was devoted to the effects of velocity shear in the oncoming flow. Time-averaged and unsteady flow patterns around the cylinder were studied to enhance understanding of the effects of velocity shear. The simulation results showed that the Strouhal number has no significant variation with oncoming velocity shear, while the peak fluctuation frequency of the drag coefficient becomes identical to that of the lift coefficient with increase in velocity shear. The intermittently-reattached flow that features the aerodynamics of the 5:1 rectangular cylinder in non-shear flow becomes more stably reattached on the high-velocity side, and more stably separated on the low-velocity side. Both the mean and fluctuating drag coefficients increase slightly with increase in velocity shear. The mean and fluctuating lift and moment coefficients increase almost linearly with velocity shear. Lift force acts from the high-velocity side to the low-velocity side, which is similar to that of a circular cylinder but opposite to that of a square cylinder under the same oncoming shear flow.

Adsorption equilibrium, kinetics and mechanism studies of mercury on coal-fired fly ash

Qiang Zhou,Yufeng Duan,Chun Zhu,Jun Zhang,Min She,Hongqi Wei,Yaguang Hong 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.7

Fly ash samples were collected from the electrostatic precipitator (ESP) of a 600MW pulverized coal boiler firing Zhungeer bituminous coal in China to evaluate and explore its mercury adsorption capacity and mechanism. Samples characterization was conducted to feature their morphologies correlated to mercury content, and experimental studies on mercury adsorption in a fixed-bed apparatus were carried out to further verify its mercury adsorption availability. Based on the experimental data, adsorption isotherm was modeled with Langmuir, Freundlich, and Temkin equations. Adsorption kinetic analysis was also performed. The results show that mercury content of fly ash samples is associated with particle size, unburned carbon content and functional groups of Al-O/Si-O or Si-O-Si/Si-O-Al tetrahedron on fly ash. Increase of initial mercury concentration is beneficial to promote mercury adsorption due to the enhancement of mercury diffusion force onto the fly ash surface, mercury intraparticle diffusion rate and initial mercury adsorption rate. Fly ash with medium size displays better mercury adsorption capacity. Smaller particle size results in higher specific surface area, but brings about low specific surface area utilization rate for mercury adsorption. Freundlich isotherm equation presents better fitting result, indicating that fly ash surface is non-uniform. Mercury adsorption on fly ash at 120 oC is mainly physisorption enhanced by chemisorption with ΔG at −36.73 kJ/mol. The pseudo-first-order kinetic model can describe the adsorption process more accurately and predict mercury adsorption capacity of fly ash preferably, showing that mercury adsorption on fly ash surface in fixed-bed is controlled dominantly by external mass transfer.

신출 당 황제와 황후 공양석 고찰

저우종치앙 ( Zhou Zhong Qiang ) 중국사학회 2017 中國史硏究 Vol.109 No.-

서안(西安)에서 새로 발견된 당(唐)나라 황제와 황후에게 올리는 공양경당(供養經幢)의 선각(線刻) 예불도는 북위(北魏) 용문(龍門) 석굴빈양중동(賓陽中洞)과 북위 공현(鞏縣) 석굴 제1굴 등의 뒤를 이은 구조와 양식이다. 이것은 당대 황제와 황후 예불도로는 지금까지 발견된 유일한 예불도 석각이다. 본고는 이 예불도에 대하여 이 그림에 있는 제후와 관료들이 누구인지, 위진남북조 이래 용문석굴이나 운강석굴의 도상과의 연관성은 어떠한지를 문헌자료와의 연계분석을 통해 조명함으로써 향후 이 분야 연구에 참고자료가 될 수 있기를 지향하였다.