A thermo-mechanical damage constitutive model for deep rock considering brittleness-ductility transition characteristics

This paper developed a statistical damage constitutive model for deep rock by considering the effects of external load and thermal treatment temperature based on the distortion energy.The model parameters were determined through the extremum features of stress−strain curve.Subsequently,the model predictions were compared with experimental results of marble samples.It is found that when the treatment temperature rises,the coupling damage evolution curve shows an S-shape and the slope of ascending branch gradually decreases during the coupling damage evolution process.At a constant temperature,confining pressure can suppress the expansion of micro-fractures.As the confining pressure increases the rock exhibits ductility characteristics,and the shape of coupling damage curve changes from an S-shape into a quasi-parabolic shape.This model can well characterize the influence of high temperature on the mechanical properties of deep rock and its brittleness-ductility transition characteristics under confining pressure.Also,it is suitable for sandstone and granite,especially in predicting the pre-peak stage and peak stress of stress−strain curve under the coupling action of confining pressure and high temperature.The relevant results can provide a reference for further research on the constitutive relationship of rock-like materials and their engineering applications.

回归主体的美术教育——美术教育之潜意识研究

中国以往的美术教育多注目于美术本体和功用目的。随着美术教育的改革,育人价值被关注和提倡,使其指向最终完善人格的教育目的。回归主体的美术教育才是达到人格完善的最高层次的教育。美术教育之潜意识研究具有理论和心理学依据;美术的本质、美本身和美术创作决定潜意识和美术教育关系密切,潜意识在美术教育中的改变是可能和有价值的,美术教育借潜意识来塑造人格;潜意识的秩序感和统合力以及主体的神经机能、潜力、天赋和创造力共同实现美术教育主体的回归。

Vibration control of pedestrian-bridge vertical dynamic coupling interaction based on biodynamic model

The human-induced vertical vibration serviceability of low-frequency and lightweight footbridges is studied based on the moving mass-spring-damper（MMSD） biodynamic model, and the mass damper（TMD） with different optimal model parameters being used to control the vertical vibration.First, the MMSD biodynamic model is employed to simulate the pedestrians, and the time-varying control equations of the vertical dynamic coupling system of the pedestrian-bridgeTMD are established with the consideration of pedestrianbridge dynamic interaction; and the equations are solved by using the Runge-Kutta-Felhberg integral method with variable step size. Secondly, the footbridge dynamic response is calculated under the model of pedestrian-structure dynamic interaction and the model of moving load when the pedestrian pace frequency is consistent with the natural frequency of footbridge. Finally, a comparative study and analysis are made on the control effects of the vertical dynamic coupling system in different optimal models of the TMD. The calculation results show that the pedestrian-bridge dynamic interaction cannot be ignored when the vertical human-induced vibration serviceability of low-frequency and light-weight footbridge is evaluated. The TMD can effectively reduce the vibration under the resonance of pedestrian-bridge, and TMD parameters are recommended for the determination by the Warburton optimization model.

COUPLED DYNAMIC CHARACTERISTICS AND CONTROL OF ROTOR-CONICAL MAGNETIC BEARING SYSTEM

The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freedom (five-DOF) rotor-conical electromagnetic bearing system is made, and the influence of the coupled characteristics on the system optimal controller is analyzed.

Hologamous integrating strategies for incipient fault diagnosis of transformer

This paper studied an integrative fault diagnostic system on the power transformer. On-line monitor items were grounded current of iron core, internal partial discharge and oil dissolved gas. Diagnostic techniques were simple rule-based judgment, fuzzy logistic reasoning and neural network distinguishing. Considering that much faults information was interactional, intellectualized diagnosis was implemented based on integrating the neural network with the expert system. Hologamous integrating strategies were materialized by information-based integrating monitor devices, shared information database on several levels and fusion diagnosis software along thought patterns. The expert system practiced logic thought by logistic reasoning. The neural network realized image thought by model matching. Creative conclusion was educed by their integrating. The diagnosis example showed that the integrative diagnostic system was reasonable and practical.

如何衡量经理人的领导力

为什么某位主管不论是接受什么任务总能圆满达成,而有些主管不断耗费资源却又毫无建树,甚至被下属深恶痛绝?这些问题。

Power System Simulation Laboratory of EPRI of China

The Power System Simulation Lab constructed specifically for the Three Gorges AC/DC hybrid transmissionstudy is equipped mainly with a real-time power system simulator, which can jointly operate with existing TNA andHVDC Simulator respectively. Appraised by the State Power Corporation 3 years ago, this Lab was proved reachinginternational advanced level. Several large-scaled power system studies, such as the "Simplified Three Gorges PowerSystem Study" have achieved good results.[

The Effect of Hydrostatic Pressure Fields on the Dispersion Characteristics of Fluid-shell Coupled System

The effect of hydrostatic pressure on the vibration dispersion characteristics of fluid-shell coupled structures was studied.Both fluid-loaded cylindrical shells and fluid-filled cylindrical shells were considered.Numerical analysis was applied to solve the dispersion equations for shells filled with or loaded with fluid at various hydrostatic pressures.The results for external pressure showed that non-dimensional axial wave numbers are nearly independent when the pressure is below the critical level.The influence of internal pressure on wave numbers was found significant for the real branch s=1 and the complex branches of dispersion curves.The presence of internal pressure increased the cut on frequencies for the branch s=1 for high order wave modes.

The bond graph model of planar flexible multibody mechanical systems and its dynamic principle

In order to increase the efficiency and reliability of the dynamic analysis for flexible planar linkage containing the coupling of multi-energy domains, a method based on bond graph is introduced. From the viewpoint of power conservation, the peculiar property of bond graph multiport element MTF is discussed. The procedure of modeling planar flexible muhibody mechanical systems by bond graphs and its dynamic principle are deseribed. To overcome the algebraic difficulty brought by differential causality anti nonlinear junction structure, the constraint forces at joints can be considered as unknown effort sources and added to the corresponding O-junctions of system bond graph model. As a result, the automatic modeling on a computer is realized. The validity of the procedure is illustrated by a practical example.

Novel flexible hybrid electric system and adaptive online-optimal energy management controller for plug-in hybrid electric vehicles

In order to achieve the improvement of the driving comfort and energy efficiency,an new e-CVT flexible full hybrid electric system(E2FHS) is proposed,which uses an integrated main drive motor and generator to take the place of the original automatic or manual transmission to realize the functions of continuously variable transmission(e-CVT).The design and prototype realization of the E2FHS system for a plug-in hybrid vehicle(PHEV) is performed.In order to analyze and optimize the parameters and the power flux between different parts of the E2FHS,simulation software is developed.Especially,in order to optimize the performance of the energy economy improvement of the E2FHS,the effect of the different energy management controllers is investigated,and an adaptive online-optimal energy management controller for the E2FHS is built and validated by the prototype PHEV.

Hyperchaos behaviors and chaos synchronization of two unidirectional coupled simplified Lorenz systems

To design a hyperchaotic generator and apply chaos into secure communication, a linear unidirectional coupling control is applied to two identical simplified Lorenz systems. The dynamical evolution process of the coupled system is investigated with variations of the system parameter and coupling coefficients. Particularly, the influence of coupling strength on dynamics of the coupled system is analyzed in detail. The range of the coupling strength in which the coupled system can generate hyperchaos or realize synchronization is determined, including phase portraits, Lyapunov exponents, and Poincare section. And the critical value of the system parameter between hyperchaos and synchronization is also found with fixed coupled strength. In addition, abundant dynamical behaviors such as four-wing hyperchaotic, two-wing chaotic, single-wing coexisting attractors and periodic orbits are observed and chaos synchronization error curves are also drawn by varying system parameter c. Numerical simulations are implemented to verify the results of these investigations.

Compound control for speed and tension multivariable coupling system of reversible cold strip mill

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.

Operation control strategy of series-parallel hydraulic hybrid vehicle

A series-parallel hydraulic hybrid system applied to public buses is put torwaro, ano parameters of key components are analyzed and determined. Energy management strategy based on logic thresh- old is designed which is aimed at efficient operation of the overall system considering the operational characteristic of the components and taking the curves of engine, hydraulic pump/motor and hydrau- lic pump as the main design basis; regenerative control strategy which makes regenerative brake sys- tem and frictional brake system work harmoniously is designed to raise recovery rate of regenerative brake energy. System dynamic modeling and simulation results show that the energy control strategy designed here is able to adapt system to changes of working condition and switch the operating mode reasonably. The regenerative braking control strategy is effective in raising the utilization of energy and improving fuel economy.

Dynamic simulation and optimal control strategy for a parallel hybrid hydraulic excavator

The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI (proportion integral) control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.

Optimization of Wind-Marine Hybrid Power System Configuration Based on Genetic Algorithm

Multi-energy power systems can use energy generated from various sources to improve power generation reliability.This paper presents a cost-power generation model of a wind-tide-wave energy hybrid power system for use on a remote island,where the configuration is optimized using a genetic algorithm.A mixed integer programming model is used and a novel object function,including cost and power generation,is proposed to solve the boundary problem caused by existence of two goals.Using this model,the final optimized result is found to have a good fit with local resources.

Research and practice of designing hydro/ photovoltaic hybrid power system in microgrid

Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.

A Coupled Hybrid Lattice: Its Related Continuous Equation and Symmetries

The hybrid lattice, known as a discrete Korteweg-de Vries (KdV) equation, is found to be a discrete modified Korteweg-de Vries (mKdV) equation in this paper. The coupled hybrid lattice, which is pointed to be a discrete coupled KdV system, is also found to be discrete form of a coupled mKdV systems. Delayed differential reduction system and pure difference systems are derived from the coupled hybrid system by means of the symmetry reduction approach. Cnoidal wave, positon and negaton solutions for the coupled hybrid system are proposed.

Preference of Chaotic Synchronization in a Coupled Laser System

In a coupled laser system, the dynamics of the receiving laser is investigated when two separate transmitting lasers are injected into the receiving laser with different coupling strengths. It is shown that the phenomenon of preference of chaotic synchronization appears under appropriate coupling conditions. The receiving laser will entrain the pulses of either one or both transmitting lasers when the coupling is strong while it keeps its own dynamics when the coupling is weak.

Damping controller design based on FO-PID-EMA in VSC HVDC system to improve stability of hybrid power system

Wind energy sources have different structures and functions from conventional power plants in the power system.These resources can affect the exchange of active and reactive power of the network.Therefore,power system stability will be affected by the performance of wind power plants,especially in the event of a fault.In this paper,the improvement of the dynamic stability in power system equipped by wind farm is examined through the supplementary controller design in the high voltage direct current(HVDC)based on voltage source converter(VSC)transmission system.In this regard,impacts of the VSC HVDC system and wind farm on the improvement of system stability are considered.Also,an algorithm based on controllability(observability)concept is proposed to select most appropriate and effective coupling between inputs-outputs(IO)signals of system in different work conditions.The selected coupling is used to apply damping controller signal.Finally,a fractional order PID controller(FO-PID)based on exchange market algorithm(EMA)is designed as damping controller.The analysis of the results shows that the wind farm does not directly contribute to the improvement of the dynamic stability of power system.However,it can increase the controllability of the oscillatory mode and improve the performance of the supplementary controller.

Application of data fusion method to fault diagnosis of nuclear power plant

The work condition of nuclear power plant (NPP) is very bad, which makes ithas faults easily. In order to diagnose (he faults real time, the fusion diagnosis system is built.The data fusion fault diagnosis system adopts data fusion method and divides the fault diagnosisinto three levels, which are data fusion level, feature level and decision level. The feature leveluses three parallel neural networks whose structures are the same. The purpose of using neuralnetworks is mainly to get basic probability assignment ( BPA) of D-S evidence theory, and the neuralnetworks in feature level are used for local diagnosis. D-S evidence theory is adopted to integratethe local diagnosis results in decision level. The reactor coolant system is the study object andwe choose 2# steam generator U-tubes break of the reactor coolant system as a diagnostic example.The experiments prove that the fusion diagnosis system can satisfy the fault diagnosis requirementof complicated system, and verify that the fusion fault diagnosis system can realize the faultdiagnosis of NPP on line timely.