高可靠性“三双”接线与配电自动化适应性分析及配置研究

现阶段,配电自动化建设作为提升电网供电可靠性的手段已被供电企业广泛认可。配电自动化是实现故障快速定位、隔离以及供电恢复,从而提高供电可靠性的重要手段,近年来已经取得了大量的研究成果。据测算“三双”接线模式的理论供电可靠率可以达到 99.9998%,为电网供电可靠性的提高提供了有力的技术支撑。但关于高可靠性的“三双”接线模式能否与配电自动化系统统筹建设,如何将其与《导则》供电可靠性要求更加有效地结合起来,尚无相关研究。基于此,本篇文章对高可靠性“三双”接线与配电自动化适应性分析及配置进行研究,以供参考。

液力变矩器在工程机械上的应用和发展

介绍目前应用于工程机械上的液力变矩器的几种类型 。

Novel disturbance compensating dynamic positioning of dredgers based on adaptive backstepping

In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and compensated for by the adaptive method without extra sensors on dredging equipment,and the control mechanism is simplified.Adaptive control is used to compensate for the reaction and environmental disturbances on the dredger,so the dredger can maintain the desired position with a minimum error and shock.The proposed adaptive robust controller guarantees the global asymptotic stability of the closed-loop system and rapid position tracking of the dredger.The simulation results show that the proposed controller has superior performance in position tracking and robustness to large disturbances.

Motion connectivity-based initial video object extraction

In order to obtain the initial video objects from the video sequences, an improved initial video object extraction algorithm based on motion connectivity is proposed. Moving objects in video sequences are highly connected and structured, which makes motion connectivity an advanced feature for segmentation. Accordingly, after sharp noise elimination, the cumulated difference image, which exhibits the coherent motion of the moving object, is adaptively thresholded. Then the maximal connected region is labeled, post-processed and output as the final segmenting mask. Hence the initial video object is effectively extracted. Comparative experimental results show that the proposed algorithm extracts the initial video object automatically, promptly and properly, thereby achieving satisfactory subjective and objective performance.

Design of robust fuzzy controller for ship course-tracking based on RBF network and backstepping approach

This study presents an adaptive fuzzy neural network (FNN) control system for the ship steering autopilot. For the Norrbin ship steering mathematical model with the nonlinear and uncertain dynamic characteristics, an adaptive FNN control system is designed to achieve high-precision track control via the backstepping approach. In the adaptive FNN control system, a FNN backstepping controller is a principal controller which includes a FNN estimator used to estimate the uncertainties, and a robust controller is designed to compensate the shortcoming of the FNN backstepping controller. All adaptive learning algorithms in the adaptive FNN control system are derived from the sense of Lyapunov stability analysis, so that system-tracking stability can be guaranteed in the closed-loop system. The effectiveness of the proposed adaptive FNN control system is verified by simulation results.

Unified Vibration Suppression and Compliance Control for Flexible Joint Robot

An adaptive control scheme is presented,which can simultaneously realize vibration suppression and compliance control for flexible joint robot(FJR).The proposed control scheme provides a unified formulation for both vibration suppression mode,where FJR tracks the desired position with little vibration,and compliance mode,in which FJR presents passive.Instead of designing multiple controllers and switching between them,both modes are integrated into a single controller,and the transition between two modes is smooth and stable.The stability of the closed-loop system is theoretically proven via the Lyapunov method,with the considering the dynamics uncertainties in both link side and motor side.Simulation results are presented to illustrate good performances of the proposed control scheme.

Development of the Embedded Protective Device Based on ARM

An embedded protective device for 35kV power line is worked out based on Philips’ LPC2292 ARM MCU. Several aspects such as embedded design technique adopted in the system framework, application of adaptive theory in data acquisition, Board Support Packet (BSP) developing and task dispatching related to operating system are discussed. Both hardware and software framework of the system are given. Advanced hardware platform and software development environment is applied in design of the system, with the advanced co-design technology.

Fault-Tolerant Control of Nonlinear Systems Based on Fuzzy Neural Networks

Due to its great potentisl value in theory and application, fault-tolerant control atrategies of nonlinear systems, especially combining with intelligent control methods, have been a focus in the academe. A fault-tolerant control method based on fuzzy neural networks was presented for nonlinear systems in this paper. The fault parameters were designed to detect the fault, adaptive updating method was introduced to estimate and track fault, and fuzzy neural networks were used to adjust the fault parameters and construct automated fault diagnosis. And the fault compeusation control force, which was given by fault estimation, was used to realize adaptive fault-tolerant control. This framework leaded to a simple structure, an accurate detection, and a high robusmess. The simulation results in induction motor show that it is still able to work well with high dynamic performance and control precision under the condition of motor parameters＇ variation fault and load torque disturbance.

A Secure-Efficient Data Collection Algorithm Based on Self-Adaptive Sensing Model in Mobile Internet of Vehicles

Existing research on data collection using wireless mobile vehicle network emphasizes the reliable delivery of information.However,other performance requirements such as life cycle of nodes,stability and security are not set as primary design objectives.This makes data collection ability of vehicular nodes in real application environment inferior.By considering the features of nodes in wireless IoV,such as large scales of deployment,volatility and low time delay,an efficient data collection algorithm is proposed for mobile vehicle network environment.An adaptive sensing model is designed to establish vehicular data collection protocol.The protocol adopts group management in model communication.The vehicular sensing node in group can adjust network sensing chain according to sensing distance threshold with surrounding nodes.It will dynamically choose a combination of network sensing chains on basis of remaining energy and location characteristics of surrounding nodes.In addition,secure data collection between sensing nodes is undertaken as well.The simulation and experiments show that the vehicular node can realize secure and real-time data collection.Moreover,the proposed algorithm is superior in vehicular network life cycle,power consumption and reliability of data collection by comparing to other algorithms.

Dynamic Control of a Flexible Shaft Mounted in Adaptive or Active Bearing

The dynamic behavior of rotors is highly influenced by bearing characteristics. In previous works, the authors have shown that it may be beneficial to adapt the bearing behavior to the shaft behavior. Several adaptive and active components will be developed in this paper in order to control the shaft dynamical amplitude. Different models of hydrodynamic bearings behavior are described. The Reynolds equation resolution may be done by numerical or analytical solutions. A physical analysis of the equation of thin films will identify the most sensitive parameters. The shaft flexibility is taking into account by a modal approach. The fluid-structure coupling process is a simulation, step by step, of the rotor behavior. At each step, the nonlinear fluid force is numerically calculated to obtain the unbalanced shaft response. The results, presented in this paper, concern the dynamic response of unbalanced shaft mounted in adaptive or active bearings： bearings with variable clearance, variable viscosity or variable housing speed. It is shown that the fluid bearing parameters must be adapted to the rotor speed （in particular near or far a critical speed）. Then, the paper presents a new kind of active bearing. It works with a mechanical control of the housing position. Several parameters are tested and compared. The robustness of the dynamic control parameters is presented. In conclusion, the bearing adaptation could be very useful to control the shaft dynamic. This limits the effect of the critical speed, in particular by diminishing the shaft amplitude and the dynamic forces transmitted to the housing.

Dynamic characteristic analysis of whole machine tools based on Kriging model

In order to study the variation of machine tools’dynamic characteristics in the manufacturing space,a Kriging approximate model is proposed.Finite element method(FEM)is employed on the platform of ANSYS to establish finite element(FE)model with the dynamic characteristic of combined interface for a milling machine,which is newly designed for producing aero engine blades by a certain enterprise group in China.The stiffness and damping of combined interfaces are adjusted by using adaptive simulated annealing algorithm with the optimizing software of iSIGHT in the process of FE model update according to experimental modal analysis(EMA)results.The Kriging approximate model is established according to the finite element analysis results utilizing orthogonal design samples by taking into account of the range of configuration parameters.On the basis of the Kriging approximate model,the response surfaces between key response parameter and configuration parameters are obtained.The results indicate that configuration parameters have great effects on dynamic characteristics of machine tools,and the Kriging approximate model is an effective and rapid method for estimating dynamic characteristics of machine tools in the manufacturing space.

An adaptive handoff management for fault tolerant mobile computing

Due to the mobility of mobile hosts,checkpoints and message logs of the computing process may disperseover different mobile support stations in the checkpointing and rollback recovery protocol for mobilecomputing.Three existing checkpoint handoff schemes do not give well consideration to the efficiency offailure-free process execution and the recovery speed of the failure process at the same time.A dynamicadaptive handoff management of the checkpointing and rollback recovery protocol for mobile computing isproposed in this paper.According to the individual feature and current state of each mobile host,differentimplementations are selected dynamically to complete the handoff process upon the handoff event.Performance analyses show that the proposed handoff management incurs a low loss of performance duringfailure-free and achieves a quick recovery upon the process fault.

A Nonparametric Approach to Foreground Detection in Dynamic Backgrounds

Foreground detection is a fundamental step in visual surveillance.However,accurate foreground detection is still a challenging task especially in dynamic backgrounds.In this paper,we present a nonparametric approach to foreground detection in dynamic backgrounds.It uses a history of recently pixel values to estimate background model.Besides,the adaptive threshold and spatial coherence are introduced to enhance robustness against false detections.Experimental results indicate that our approach achieves better performance in dynamic backgrounds compared with several approaches.

Adaptive associative classification with emerging frequent patterns

In this paper, we propose an enhanced associative classification method by integrating the dynamic property in the process of associative classification. In the proposed method, we employ a support vector machine（SVM） based method to refine the discovered emerging ~equent patterns for classification rule extension for class label prediction. The empirical study shows that our method can be used to classify increasing resources efficiently and effectively.

影响机械通气患者撤机后果的因素分析

目的 研究自动适应性支持通气(ASV)和双水平气道正压通气(BiPAP)两种通气模式对撤机后果的影响,并比较常规撤机指标对机械通气患者撤机的预测价值.方法 60例需机械通气的患者随机分两组:ASV组(n=27)和BiPAP组(n=33).床旁监测呼吸频率(RR)、潮气量(VT)、分钟通气量(VE)、阻力(R)、顺应性(C);在自主呼吸试验30 min时分别测定RR、VT并计算浅快呼吸指数(RSB).结果 两组平均带机时间分别为ASV(5.9±2.4)d;BiPAP(6.6±3.0)d.与BiPAP组相比,ASV组患者RSB较低[(68±19)次/(min·L)vs(80±22)次/(min·L),P＜0.05],VT较高[(387±73)ml vs(339±64)ml,P＜0.05)],而撤机成功率无显著性提高(81.5% vs 78.8%,P＞0.05).以撤机后果作为因变量进行Logistic回归分析显示:只有RSB与机械通气时间(DMV)是回归模型中有显著性的两个指标.常规撤机指标RSB、RR、VE和VT的ROC曲线显示RSB的曲线下面积最大.结论 ASV和BiPAP是两种较好的通气模式,二者具有相似的撤机后果.ASV在预防浅快呼吸和操作简单两方面优于BiPAP.RSB在预测撤机后果上优于常规撤机指标,对呼吸机撤离有一定指导意义.

Analysis of the constraint relation between ground and self-adaptive mobile mechanism of a transformable wheel-track robot

To maneuver in unstructured terrains where the ground might be soft, hard, flat or rough, a transformable wheel-track robot (NEZA-I) with a self-adaptive mobile mechanism is proposed and developed. The robot consists of a control system unit, two symmetric transformable wheel-track (TWT) units, and a rear-wheel unit. The TWT unit is the main mobile mechanism for the NEZA-I robot, with the rear-wheel unit acting as an assistant mechanism. Driven only by one servomotor, each TWT unit can efficiently select between track mode and wheel mode for optimal locomotion, autonomously switching locomotion mode and track configuration with changes in the terrain. In this paper, the mechanism structure, the self-adaptive drive system, the locomotion mode and posture of the NEZA-I robot are presented, the kinematic relation of the inside parts of the TWT unit is analysed, and the mathematic model of the constraint relation between the mobile mechanism and the ground, abbreviated to "MGCR model" is set up for the NEZA-I robot to go through some typical unstructured environments. The mechanism parameters, which influence the self-adaptability of the NEZA-I robot, are found and optimized. Basic experiments show that the mobile mechanism has the self-adaptability to navigate in unstructured terrains and has superior obstacle-negotiating performance, and that the MGCR model and the analysis method of mechanism parameters are reasonable. From a mechanism point of view, it can provide an idea for research on the adaptive control of the robot.