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Cai D.,Henan Electrical Power Survey And Design Institute | Xiao H.,Henan Electrical Power Survey And Design Institute
Proceedings - 2016 6th International Conference on Instrumentation and Measurement, Computer, Communication and Control, IMCCC 2016 | Year: 2016

In the sliding bearing-rotor system, the rotor is influenced by the nonlinear oil film force, which makes the system dynamic response under the influence of coupling faults more complicated. Therefore, in this paper, a coupling rubbing model of the rotor system with sliding bearing was proposed, which fully considered the influence of oil film force, and contained the coupling fault of unbalance, misalignment and rubbing. The simulation analysis was implemented, and the experimental study was carried out on the rotor test rig. Then, the vibration response was obtained and processed by the multi differential empirical mode decomposition. The vibration signals of simulation and experiment were compared, and the decomposed result was analyzed. The accuracy and effectiveness of the proposed model was demonstrated. © 2016 IEEE.

Cai D.,Henan Electrical Power Survey And Design Institute | Xiao H.,Henan Electrical Power Survey And Design Institute
Proceedings - 2016 6th International Conference on Instrumentation and Measurement, Computer, Communication and Control, IMCCC 2016 | Year: 2016

The vibration fault identification is a significant process of the reliability analysis for large rotating machine, and the accuracy of identification results depends on the effectiveness of extracted fault symptoms directly. For the vibration symptoms extraction, the time-frequency domain analysis has been widely utilized. Empirical Mode Decomposition (EMD) is one of the most typical time-frequency method, but its performance is effected by the mode mixing problem. In this paper, a novel coupled EMD is proposed, and utilized to the vibration signal decomposition. In the CEMD, the differential vibration signal was obtained and decomposed by EMD, and then, the results were integrated and couple decomposed by EMD. After decomposition, the energy distribution vectors were extracted as the fault symptoms. At last, the obtained vibration symptoms were taken as input, and the classifier was utilized to identify the different kinds of faults for the large rotating machine. The proposed method was applied into the actual fault identification for the rolling element bearings, and the results demonstrated that, CEMD can improve the mode mixing problem significantly, while the energy distribution symptoms has the advantages of high universality and strong separability, and the vibration faults can be identified more accurately with higher efficiency.

Zhao W.,North China University of Water Conservancy and Electric Power | Zheng X.,Henan Electrical Power Survey And Design Institute
Advanced Materials Research | Year: 2012

Numerical investigation of large thick and low Reynolds airfoil of wind turbines by mounting indented Gurney flaps was carried out. The influenced rules of the position of Gurney flaps on the aerodynamic performance of airfoil under same height of flaps were achieved, and the optimal position of Gurney flap was presented. At last, the mechanism of wind turbine performance controlled by Gurney flap was discussed. The results can provide the theoretical guidance and technical support to wind turbines control in practical engineering. © (2012) Trans Tech Publications, Switzerland.

Liu J.,Ryerson University | Liu M.,Henan Electrical Power Survey And Design Institute | Zhu Z.,Hohai University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2012

This paper presents an experimental investigation on soil deformation around uplift plate anchors in sand by using digital image correlation (DIC). The experimental setup consists of a camera, loading frame, plexiglass mold, and computer, which is developed to capture soil deformation during anchor uplifting. A series of model tests are performed to investigate the influence of particle size, soil density, and anchor embedment depth on soil deformation. A set of images captured during anchor uplifting are used to calculate soil displacement fields by DIC. The failure surface is studied by tracking the points with maximum shear strain values. On the basis of this study, it is found that soil deformation and the pullout resistance of plate anchors are substantially influenced by soil density and anchor embedment depth, whereas particle size within the studied range has limited influence. In dense sand, the shape of the failure surface changes from a truncated cone above a shallow anchor to a combined shape of a curved cone and a truncated cone for a deep anchor. In contrast, in loose sand a cone-shaped failure surface is formed within the soil mass above a shallow anchor; however, no failure surface is observed for a deep anchor, where the compressibility of soil is the dominating factor that influences the behavior of deep plate anchors in loose sand. © 2012 American Society of Civil Engineers.

Bai H.-K.,Henan Electric Power Company | Li G.-S.,Henan Electrical Power Survey And Design Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The 220 kV electrical network short-circuit current level enhances quickly along with unceasing enhancement of electrical network structure, open-loop operation mode must be carried out gradually to lower the 220 kV electrical network short-circuit current level. But in the process of electrical network open-loop it often contradicts with some planned electrical network projects. This paper describes the fundamental principles as well as the main method of open-loop. Taking Zhengzhou 500 kV/220 kV electromagnetic ring for example, in accordance with its present situation and long-term network planning, open-loop operation is progressively implemented and the rationality of Zhengzhou long-term network plan has been simultaneously verified. This paper puts forward the idea of using the open-loop planning studies to verify the rationality of electrical network planning, which not only unifies the network planning and open-loop planning rationally to guide the development of electrical network, but also avoids unnecessary construction to save investment.

Bai H.-K.,Henan Electric Power Company | Li G.-S.,Henan Electrical Power Survey And Design Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

Along with electrical network structure's unceasing enhancement, the short-circuit current level of 220 kV electrical network enhances quickly, to further lower the short-circuit current level, open-loop operation mode must be carried out gradually. When the structure of 500 kV and 220 kV power grid is still not perfect, open-loop operation is often difficult to achieve. This paper proposes a weak open-loop mode, takes Sanmenxia power grid in Henan as an example, and explains this kinds of open-loop form. Conclusion is that the use of weak open-loop way is better than the completely open-loop mode in the transitional period, and it can provide a new mode to safe and reliable operation of power grids.

Chen L.,Henan Electrical Power Survey And Design Institute
Applied Mechanics and Materials | Year: 2013

The failure of elastic perfect cylinders under uniform external pressure is caused by circumferential buckling. The effects of the cylinder length, of the restraining conditions at boundaries and of the length of the pressurized zone all have great influences on the critical buckling load. In the European Standard for Shells EN 1993-1-6 (2007), the critical circumferential buckling stress is obtained by introducing an external buckling factor which takes the influence of different boundary conditions into account. However, the restraint of the meridional rotation at boundaries was not considered separately for the factor. For short cylinders, any restraint of the boundaries affects the buckling mode and buckling strength greatly. In this paper, the effect of meridional end rotations on the buckling strength of short cylinders was studied. The pre-buckling membrane stress state given by membrane theory was assumed for all the analyses. © (2013) Trans Tech Publications, Switzerland.

Chen L.,Henan Electrical Power Survey And Design Institute | Rotter J.M.,University of Edinburgh
Engineering Structures | Year: 2012

Cylindrical shells subjected to non-uniform wind pressure display different buckling behaviours from those of cylinders under uniform external pressure. At different aspect ratios, quite varied and complex buckling patterns occur: the results of linear and nonlinear buckling analysis can also be quite different. By contrast, cylinders under uniform external pressure always experience circumferential buckling and are little affected by changes in geometry, except in very short cylinders or changed boundary conditions.This paper presents a wide-ranging study of anchored stocky and intermediate length cylindrical shells of uniform thickness under wind pressure. Its aim is to produce useful information for the design of silos and anchored tanks against buckling under wind. The finite element analyses indicate that both linear and nonlinear analyses predict the circumferential compression buckling mode in stocky cylinders. For intermediate cylinders, pre-buckling ovalization of the cross-section has an important influence on the buckling strength. Empirical expressions are developed to relate the linear and nonlinear critical stagnation pressures under wind to the classical critical value for uniform external pressure. The effects of yielding and imperfection sensitivity are also briefly explored. © 2012 Elsevier Ltd.

Chen L.,Henan Electrical Power Survey And Design Institute
Applied Mechanics and Materials | Year: 2014

The cylindrical shells under global bending with different geometric parameters display different failure behavior. The size of typical buckles under axial compressive stress regimes is rather small and extends over a very small zone, with the axial compressive stress reaching the critical value. The first estimate of the elastic buckling strength in bending is the condition in which the most compressed fiber reaches the buckling stress for uniform axial compression. For short cylinders, local bifurcation buckling occurs at the middle of the most compressed side of the shell, and geometric nonlinearity has a little effect on the buckling strength, while for medium-length and long cylinders, the geometric nonlinearity and the ovalization of the cross-section should be considered. This paper explores the failure behavior in elastic cylinders in pure bending. © (2014) Trans Tech Publications, Switzerland.

Yao Y.,Henan Electrical Power Survey And Design Institute | Chen S.-S.,Henan Electrical Power Survey And Design Institute
Physica A: Statistical Mechanics and its Applications | Year: 2014

Recent research has identified the heterogeneity as crucial for the evolution of cooperation in spatial population. However, the influence of heterogeneous noise is still lacking. Inspired by this interesting question, in this work, we try to incorporate heterogeneous noise into the evaluation of utility, where only a proportion of population possesses noise, whose range can also be tuned. We find that increasing heterogeneous noise monotonously promotes cooperation and even translates the full defection phase (of the homogeneous version) into the complete cooperation phase. Moreover, the promotion effect of this mechanism can be attributed to the leading role of cooperators who have the heterogeneous noise. These type of cooperators can attract more agents penetrating into the robust cooperator clusters, which is beyond the text of traditional spatial reciprocity. We hope that our work may shed light on the understanding of the cooperative behavior in the society. © 2014 Elsevier B.V. All rights reserved.

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