Abstract:To identify individual partial discharges(PD)signals produced by multiple insulation defects in gas insolated switchgear (GIS),this paper analyses the mechanism of propagation and mixing of multiple PD electromagnetic wave signals in GIS cylinder and proposes the convolutive mixing model to describe it for a separation algorithm to acquire individual PD signals. With the non-stationary property,mixing PD signals are changed at time domain into a set consisting of short-time stationary PD signals and then the Molgedey-Schuster decorrelation approach is employed to separate these stationary PD signals at frequency domain. The correlation of the envelope of separated PD signals in this set is used to reconstruct PD signals to realize the separation of non-stationary UHF PD mixtures. The effective separation of actual UHF PD mixing signals validates the assumption of convolutive mixing process in GIS and also offers a new approach to the identification of mixing PD signals by external ultra-high frequency detection scheme from multiple insulation defects in GIS.

Abstract:This paper summarizes the requirements of standards for aircraft power supply firstly,and then points out that the input current harmonic and output DC voltage ripple should be considered seriously when designing three-phase power factor correction (PFC)for aircraft under variable line frequency and unbalanced line supply. Based on reviewing the topologies for aircraft three-phase PFC,three typical topologies,i.e. three-phase pulse width modulation (PWM)rectifier,traditional shunt active power filter (APF)and generalized APF,are picked up. A unified single-phase equivalent model is developed for comparing the harmonic suppression performance of the three active PFC schemes. And the switching stress is also calculated for evaluating their efficiency and power density. Three 5 kW PFC are designed by employing each of the three selected schemes. Simulation is carried out to verify the correctness of the theoretical analysis. The theory and simulation results indicate that the generalized APF topology shows the most technical merit for aircraft three-phase PFC. Future research works on generalized APF are also pointed out,which are solving the uncontrollability of its DC output voltage and optimal designing the filter inductors.

Abstract:Aiming to solve the problem of nonlinear uncertainties LuGre dynamic friction and non-symmetric dead zone in the robot,this paper presents a sliding mode robust robot control algorithm,compensates for the uncertainties of robot manipulator respectively LuGre dynamic friction with fuzzy radial base function (RBF)neural network and asymmetrical dead zone with fuzzy logic,trains parameters of nonlinear dynamic friction and asymmetrical dead zone real-timely and adaptively,to achieve an accurate reproduction of the actual robot system,and proves the Lyapunov stability of the algorithm. The simulation of a two-degree-of-freedom robot manipulator proves that the algorithm improves the trajectory tracking accuracy,the control torque stability and friction torque stability of the robot. Meanwhile,it is found that control moment pulse compensation error,rhombus attractor in the kinetic properties of the friction model of robot manipulator,and lacking of dead zone compensation cause nonlinear kinetic phenomena,such as limit cycle oscillation of control system. And the estimation of ε in the dead zone inverse model plays a decisive role in the accuracy of the system.

Abstract:A purely torsional dynamic model of multi-stage planetary gear trains is developed to investigate the dynamic characteristics of the transmission system in shield machine cutter drive. In the model,phase difference between mesh stiffness and error among each stage caused by different initial mesh positions is considered,and other factors such as component bearing stiffness,time-varying mesh stiffness and error are considered as well. Inherent characteristic analysis shows there are more unique and diverse vibration modes in multi-stage planetary gear trains than in single-stage planetary gear trains. Through dynamic response analysis,time-domain and frequency-domain response of dynamic meshing force of each stage is obtained. As the frequency of exciting force of medium-speed and high-speed stage is in proximity to the natural frequency of the system,harmonic resonance tends to occur,which needs to be paid great attention to. Dynamic factors of each stage are also computed and prepare the ground for the dynamic optimizing design of planetary gear trains.

Abstract:Slag water surface evaporation phenomenon exists in the system of water cooling slag removal. The authors study the relationship between slag water (which is from the JINJIE power plant in Shaanxi)surface evaporation rate and the relative humidity(40%~90%)and the water surface temperature(35-75 ℃),which at an atmospheric pressure and the wind speed is 0.5 m/s,and then obtains an empirical equation. The experiment measures three kinds of concentrations of the slag water surface evaporation rate,and compares the measuring results with those of the pure water surface evaporation rate at the same experimental conditions. According to the comparison results,the authors analyze underlying causes of slag water evaporation from the thermodynamic point of view,that is surface temperature and composition and content changed the surface free energy,thus affects the slag water surface evaporation rate. It is found that water surface evaporation rate is 1.1~1.2 times of the rate of slag water when the temperature is over 50 ℃,while the water surface evaporation rate is slightly higher than that of slag water when the temperature is lower than 50 ℃,and the slag water surface evaporation rate changes in 10% in a certain concentration range.

Abstract:An experimental investigation using electric heating method is carried out to explore the effect of tilt angle and heat flux on heat losses of a fully opened cylindrical cavity receiver. Two cases are examined,i.e. all walls of cavity heated and only the bottom wall (opposite wall of opening)heated. For both cases,the walls are heated at a constant heat flux. The empirical correlations of Nusselt numbers of natural convection and radiation heat losses versus the Grashof number,tilt angle and corresponding heat loss flux are proposed. The results show that,with constant input power,the natural convection heat loss of receiver decreases as the tilt angle increases while the conduction heat loss and the radiation heat loss increase slightly. When the heat flux of natural convection heat loss keeps constant,Nusselt number for determining the natural convection heat loss reduces with increasing tilt angle. However,when the heat flux of radiation heat loss remains constant,the tilt angle has very little effect on the Nusselt number for determining the radiation heat loss. Also,there is a certain difference of heat loss performance between two cases,and the wall heating location has a relatively samll influence on the radiation heat loss in comparison with on the natural convection heat loss.

Abstract:In view of the widely used masonry structure in village buildings,we propose a simply constructed energy dissipation technology in a feasible way,which is experimented with a model at the ratio of 1 to 4 on the shaking table. Through an analysis of the process and results of the experiment,it is found that this technology can protect the building from damage in need of repair and assure the building’s basic functions in a minor seismic scale. When the input mesa peak acceleration is 0.465g,equal to PGA of 0.31g (7.5 degree)of the original building,the energy dissipation system begins to take effects and effectively reduces the damage of the masonry structures from a bigger seismic scale. When the input mesa peak acceleration is increased to 0.6g,equal to PGA of 0.4g (8 degree),the energy dissipation system is severely damaged,but the masonry structure doesn’t collapse.

Abstract:For the foreign monopoly of current non-contact tonometry technology and the disadvantage of domestic existing technology,we develop a new type of non-contact tonometry system base on equilibrium principle and aerostatic technology. The system adopts ARM9 S3C2440A as the core,mainly including flotation measurement module,control module,human-computer interaction and communication interface module. The flotation measurement module could finish the signal acquisition and measurement on CCD camera,pressure sensor,and optical signals of corneal reflection that the control module mainly controlled the supply gas pressure of centered gas chamber. When the developed system is used to measure human intraocular pressure,the measured values show that there is only less than 6.01% repeatability error. Compared with the imported non-contact tonometry,the absolute error between two equipments’ measured IOP values is also no more than 1.3m mHg,which shows that the system could detect the intraocular pressure of people quickly and easily.

Abstract:The coupled thermal and solutal capillary convection subjected to radial temperature gradient in a shallow annular pool with free surface is investigated by using asymptotical analysis and the solution is obtained in the core region. The influences of Soret effect and buoyant force on fluid flow are analyzed. The results show that when the solutal capillary force and the buoyancy induced by the ununiform distribution of solute concentration are not considered, the asymptotic solution is the same as the asymptotic solution of pure thermocapillary-buoyancy convention or thermocapillary convection in a shallow annular pool. The influence of the buoyancy on the fluid flow is slight and the coupled thermal and solutal capillary forces play a dominant role in the convection in shallow annular pool. When the coupled forces are in the same direction, the flow is reinforced. Otherwise, the flows suppress each other.

Abstract:To obtain the best outburst prediction index of rock cross-cut coal uncovering slotted by pulsed water jet,the effects of the rigidity coefficient’s measured value and the initial velocity of gas diffusion to the integrative indexes D and K are analyzed based on the dynamic evolution of coal crake field under water jet. Thus the integrative indexes D and K are excluded. A grey relation model of outburst prediction indexes(K1,S and P)from 7 coal mine’ rock cross-cut coal uncovering in Chongqing,Sichuan and Henan is set up. And the grey relation degrees of the 3 prediction indexes to outburst hazard are calculated by using grey relational analysis method. The results show that the outburst hazard can be more accurately reflected by the cuttings desorption index K1 when a cross-cut coal uncovering slotted by pulsed water jet,and it should be considered as the best outburst prediction index.

Abstract:The reliability level of tool magazine is an important indicator to show how advanced a horizontal machining center is. To more effectively promote the reliability level of tool magazine,a new method combining importance and structure optimization is introduced. Taking tool magazine of a horizontal machinging as object, the fault tree of a tool magazine is established based on 35 failure data obtained from a horizontal machining center. Important levels of elementary events are calculated by fault tree analysis,and the order of importance is determined based on importance values. An improved design of structural reliability for elementary events with great importance is made according to failure principles and tool changing process. The feasibility of the improved design is verified by the designer of the tool magazine.

Abstract:Direct torque control(DTC)of space vector modulation fed by dual frequency inverter is studied in order to solve the problems of large torque,big flux ripples and inconstant switching frequency of conventional DTC in large power occasions. On the basis of conventional DTC,factors affecting flux and torque ripples are analyzed and the space voltage vector mathematical model of induction motor is deduced,which is implemented by S-function. Based on dual frequency theory,the system is supplied by cascaded inverters to decrease losses. The high frequency unit is in charge of improving the dynamic performance of the system,whose switching current is relatively low；while the low frequency unit is in charge of energy delivery,whose switching frequency is far lower than that of the high frequency unit. The simulation results illustrate that by using this program,the system has a better performance in both dynamic and static performance,and the electromagnetic torque ripple,flux ripple and switching losses are significantly reduced. Thus the system efficiency is improved and suitable for medium and large power occasions.

Abstract:By analyzing a certain once through boiler’s FR/FW control system,a new control scheme based on growing and pruning dynamic recurrent fuzzy neural network (GAP-DRFNN)is proposed. This GAP-DRFNN can synthetically study main relative state parameters about FR/FW control,so as to calculate the optimal FR/FW by using least temperature deviation value of outlet of moisture separator as its training signal. As the data of current main relative state parameters input,GAP-DRFNN through structure learning can automatically increase and pruning neurons,and adjust the parameters and the recurrent weight of neural network dynamically based on stochastic gradient descent algorithm. The experimental results show the good performance for the system in variable conditions and this scheme’s celerity and precise on FR/FW control,it has better quality than traditional PID control method.

Abstract:In order to decrease the manufacture cost of all-terrain vehicles rapidly and effectively,a finite element model for the frame structure of all-terrain vehicles is built by using pre-processing software HyperMesh. The correctness of the model is verified by computing the freedom mode of all-terrain vehicles with Optisturct solver and contrasting it with existing test results. Through applying Optistruct solver and Fatigue to analyze stress distribution,deform and fatigue life of the frame under multi-conditions,and combining with sensitivity analysis results,the lightweight project of the frame is put forward. The validity of this lightweight project is identified after analyzing the optimized frame structure intensity and the fatigue life. The lightweight result show that the frame structure is lightened 6.6063 kg. At the same time,it shows that the structure optimization efficiency and the lightweight effect are enhanced by sensitivity analysis.

Abstract:MOS field effect transistor(FET) with Dog Bone shape gate is a symmetric layout structure with hardened radiation-total-dose effect (RTDE). In order to calculate its equivalent aspect ratio, it is divided into a regular MOS FET (host MOS) and two parasitic MOS FETs (edge MOS) in parallel. The model of this device is constructed in Silvaco TCAD software, then a fitted formula of the equivalent aspect ratio is derived based on the simulation of drain current with respect to the width and length of host MOS, and overlap width between polysilicon and active area of edge MOS. The comparison between the fitted formula and measurements of sample transistors taped out in CSMC 0.5 μm DPTM CMOS mixed-signal process indicates the fitted formula for equivalent aspect ratio of Dog Bone Gate MOS FET matches the measurement.

Abstract:Single RC columns are used to investigate the influence of fault distance, vertical and horizontal acceleration spectral ratio, initial axial load ratio, fundamental period and shear span ratio on shear resistant behavior of RC columns. Eighteen-velocity pulse-like earthquake records divided into three-fault distance from Chi-Chi earthquake are used as excitations to execute nonlinear dynamic time history analysis. The results demonstrate that axial velocity pulse-like earthquake action has evident effects on the shear resistant performance of RC columns. Shear-resistant behavior factor decreases with the increase of spectral ratio, and medium initial axial load ratio and fault distance, shear span ratio and near fault distance (0~10 km) have coupling influence on the shear-resistant behavior of RC columns. Finally, nonlinear regression analysis of analytical data in the present study is carried out and empirical approach considering different effect of these factors is proposed.

Abstract:A novel image fusion method based on image segmentation and stationary wavelet transform (SWT) is proposed to improve the visual effect of fused infrared and visible light images. Infrared image is firstly separated into object and background region utilizing Otsu combined with edge detection. Then a multiresolution decomposition using SWT is made to the background region of the infrared image and the visible light image. Neighborhood spatial frequency and absolute value are adopted as fusion rules in low-frequency and high-frequency coefficients. The background fused image is reconstructed by inverse SWT. The final infrared and visible light fused image is obtained by fusing the background fused image and the object region of infrared image base on weighted fusion rule. The experimental results show that the object information of the infrared image is obviously highlighted and the scene information of the visible light image is well represented. The visual effect of fused image is improved efficiently by utilizing the proposed method. The proposed method works better than the traditional Laplacian Pyramid and wavelet transform fusion algorithms in terms of standard deviation, comentropy and mutual information. Experimental results verify its effectiveness.

Abstract:To quantitatively study the distribution curve of CNC machines, the Weibull linear regression using the failure data of CNC machines is analyzed. As the result of analyzing WPP(Weibull probability plot), the failure rate distribution curve which includes early failure period and random failure period is established by piecewise twofold Weibull model. The establish method of the model and the process of parameter estimated by maximum likelihood are explained. The correctness of the model is verified by comparing the lasting time of early failure period with the actual situation. The optimization warranty of CNC machines is obtained by an object function which is established by the model.

Abstract:A low-complexity blind adaptive receiver for ultra-wideband (UWB) systems in the presence of both multiple access interference (MAI) and inter symbol interference (ISI) is proposed, which is composed of two stages. In the first stage, a reduced-rank algorithm based on the multi-stage Wiener filter (MSWF) is considered to suppress the MAI and extract multi-path components. Channel estimation using the projection approximation subspace tracking with deflation (PASTd) algorithm and multi-path combining are then performed to further enhance the signal to interference plus noise ratio (SINR) of the desired user in the second stage. The simulation results show that the proposed receiver exhibits reasonably good bit error ratio (BER) performance compared with those of matched filter, conventional Rake receiver, decorrelating Rake receiver and adaptive receiver based on constant modulus algorithm (CMA). Moreover, it has faster convergence speed and less complexity.

Abstract:This paper presents a data-mining-based beam pumping unit process modeling and parameters optimization method to solve the problem of inefficiency and energy-intensive of beam pumping unit. The ideality of process parameters is one of the main factors influencing system efficiency and energy consumption, while the effectiveness of mode plays a key role in process parameters choosing. Beam pumping unit system is a complicated nonlinear system, and is hardly to be precisely described by precise mathematical models. Generalized regression neural network (GRNN), which is powerful in nonlinear mapping and generalization, is suitable for nonlinear systems. Therefore, GRNN is proposed to model the beam pumping unit in this paper, and the experimental results show that the fitness is good. Then the trained model is applied to optimize the decision parameters by vector evaluated particle swarm optimization based on Pareto (VEPSO-BP), and at last the resulting parameters are applied to the production. Experimental results show that after using the optimal parameters, the efficiencies and energy consumptions increase more than 6.6% and decrease more than 4.1% respectively, which illustrates the feasibility and effectiveness of the proposed method.

Abstract:Making use of the meeting opportunity raised by the movement of nodes, the messages are transmitted with the manner of “store-carry-forward” in opportunistic network. So these networks have a feature of longer delay than conventional ad hoc network. Current routing schemes try their best to deliver packet but leading to definitely network delay and are based on random movement model. According to the social character of nodes in network, the distributed predicting scheme on the expectation of meeting time between nodes is proposed; moreover, according to the estimating results, the relay node can be selected reasonably. With this manner, the message can be forwarded to the destination. Simulations show that the proposed estimating method is accurate; furthermore, comparing with the widely used routing mechanism, the performance on the delay can be improved more than 30%.

Abstract:Fuzzy control variable weight method of multi-factor decision-making adaptive deficit round robin scheduling algorithm (VWADRR), an improved deficit round robin(DRR) scheduling algorithm is put forward. It’s used in the circumstance of scheduling multiple multi-media data streams. It bases on multi-factor decision-making in the fuzzy control theory, specific to the use of the variable weight method. It’s adaptive for output channel bandwidth and buffer size of each input queues. Variable weight method makes decisions based on these two factors, that is, to determine the QN as variable in DRR. Considering the time of each packet sent, it reduces the packet delay. It effective uses buffers and bandwidth in the heavy network traffic situation, significantly reduces the possibility of buffer depletion, also smoothes burst.

Abstract:A method of detecting the signal frequency which is disturbed by the noise based on the autonomous chaotic system is proposed. A signal with noise was added to an autonomous chaotic system, and then a negative feedback was imposed to it. The feedback gain was appropriately adjusted, so as to let the noisy system orbit be a limit cycle. The number of times that the orbit went directly through a plane was calculated by loop phase technology, and the vibration frequency was found according to it. The frequency of system is determined by the frequency of the test signal, yet free from noise, so the frequency of the test signal is the vibration frequency of the system. Simulation results further demonstrate the effectiveness of the method.

Abstract:Dynamic behavioral evaluation is a hot research topic. In this paper, we take pilot behavioral evaluation for example, and propose a dynamic behavioral evaluation method based on “air-combat average time” + “dominant situation” + “air-combat credibility”. The features of this method are:1)the reasoning from “maneuver” to “maneuver” is introduced, viz., according to the current maneuvers, derive the next maneuver;2)multi-thread simulation is used, viz., each pilot is simulated by a thread, and each thread can conduct flight decision, flight dynamics solution and tactical maneuver, independently;3)weighting air-combat credibility computation formula, viz., in computing the air-combat credibility, the times of “dominant situation” and “equal situation” of each part and their weights are considered. The whole evaluation method is easy to implement; the efficiency of the algorithm is high; and the practicability of the project is strong. The experimental results show the dynamic behavioral evaluation method proposed in this paper is novel and effective.