A novel hybrid adaptive collaborative approach based on particle swarm optimization and local search for dynamic optimization problems

This paper proposes a novel hybrid approach based on particle swarm optimization and local search, named PSOLS, for dynamic optimization problems. In the proposed approach, a swarm of particles with fuzzy social-only model is frequently applied to estimate the location of the peaks in the problem landscape. Upon convergence of the swarm to previously undetected positions in the search space, a local search agent (LSA) is created to exploit the respective region. Moreover, a density control mechanism is introduced to prevent too many LSAs crowding in the search space. Three adaptations to the basic approach are then proposed to manage the function evaluations in the way that are mostly allocated to the most promising areas of the search space. The first adapted algorithm, called HPSOLS, is aimed at improving PSOLS by stopping the local search in LSAs that are not contributing much to the search process. The second adapted, algorithm called CPSOLS, is a competitive algorithm which allocates extra function evaluations to the best performing LSA. The third adapted algorithm, called CHPSOLS, combines the fundamental ideas of HPSOLS and CPSOLS in a single algorithm. An extensive set of experiments is conducted on a variety of dynamic environments, generated by the moving peaks benchmark, to evaluate the performance of the proposed approach. Results are also compared with those of other state-of-the-art algorithms from the literature. The experimental results indicate the superiority of the proposed approach.     

Hopf Bifurcation Research of Hydraulic Turbine Governing System with a Saturation Nonlinearity

A nonlinear mathematical model for hydro turbine governing system with saturation nonlinearity in small perturbation has been proposed with all the essential components, i.e. turbine, PID type governor with saturation part and generator included in the model. Existence, stability and direction of Hopf bifurcation of an example HTGS are investigated in detail and presented in forms of bifurcation diagrams and time waveforms. The analysis show that a supercritical Hopf bifurcation may exist in hydraulic turbine systems in some certain conditions. Moreover, the dynamic behavior of system with different parameters such as T_w, T_ab, T_y and K are studied extensively. An example with numerical simulations is presented to illustrate the theoretical results. The researches provide a reasonable explanation for the Hopf phenomenon happened in operation of hydroelectric generating unit.     

Development and evaluation of BCI for operating VR flight simulator based on desktop VR equipment

Advancement of brain-computer interface (BCI) has shown its applications in various scenarios, including flight control. Flight simulator is a crucial part for aircraft design or experiment. Desktop virtual reality (VR)-based flight is a perfect choice for overcoming existing problems in head-mounted VR flight simulations, such as dizziness and isolation, which make interaction and sharing very difficult. In this paper, a BCI based on the steady-state visual evoked potential paradigm and a VR flight simulator were developed and integrated. The performance of the developed system was evaluated quantitatively for comparative studies. Experimental results show that the developed system is very convenient and suitable for VR flight simulations. The average operating accuracies with plane and VR visual stimuli are 81.6% and 86.8%, respectively. The VR visual stimuli can improve the average operating accuracy by 5.2% compared with the plane visual stimuli.     

High Speed Aircraft Robust Fuzzy Controller Design Based on H∞ Performance

The dynamics of the high-speed vehicle (HSV) is partially or completely unknown because of various reasons, such as modeling errors, in-flight failure, and external disturbances. In this paper, a global stability robust fuzzy controller is designed to control the flight F-16 with uncertain perturbation. For the desired H output-feedback controllers, a necessary and sufficient condition of quadratic stability is derived with the well-established results of the Lyapunov stability theory and nonnegative matrix. The controllers not only guarantee the global asymptotically stability of the resultant closed-loop system with external disturbance and parameter perturbation, but also have a desired H performance in a large flight envelop (LFE).     

The measurement and analysis of micro bonding force for electroplated CBN grinding wheels based on response surface methodology

The superabrasive (e.g. CBN or diamond) grain dislodgement occurrence on the wheel surface due to insufficient bonding force is the major failure phenomena in the grinding process with electroplated grinding tools. This failure leads to the abrupt increase of load on the immediate grains, accelerating more grain dislodgement on wheel surface. Ultimately, the aggregated grain dislodgement causes the workpiece profile accuracy degradation and catastrophic wheel sharpness loss. Therefore, the provision of sufficient and uniform micro bonding force all through the wheel surface is the critical task in electroplated superabrasive grinding wheel design. Considering the complexity in the micro bonding force enabling factors, e.g. the grain shape, dimensional size, spatial orientation, and bond layer thickness, it is vital to establish the quantitative and comprehensive relationship between these factors with the micro bonding force for optimal electroplated grinding wheel design. In this paper, an inclined micro-thread turning test is developed to measure the single grain micro bonding force. In addition, the finite element model of single CBN grain bonding force is established and validated to simulate the grain dislodgement. Finally, the response surface methodology (RSM) is applied to build the comprehensive correlation of the bonding force with its dimensional size, spatial orientation, and bond layer thickness. Therefore, the optimal bonding condition through regressed prediction model is identified to provide the quantitative basis for the electroplated CBN grinding wheels design, which indicates that the bonding force can be predicted for specific wheel manufacturing parameters and improved by related variable adjustment.     

基于转换模块的空间即插即用综合电子系统研究

针对空间即插即用技术特点,本文研究了一种转换模块,实现了将传统航天器单机向具有标准即插即用接口与驱动的标准单机的转换。文中给出了转换模块的主要功能、信息交互流程、基本组成和工作流程,在以上基础上,给出了转换模块的研制方案,包括功能组成、各部分之间的功能与关系与基本协议组成等。最后介绍了基于转换模块的空间即插即用验证系统的开发与测试,详细介绍了验证系统的组成、功能、特点,给出了利用FPGA与ARM开发的转换模块,给出了详细的测试内容,验证了基于转换模块的空间即插即用技术的可行性与技术特点。     

红外诱饵对成像制导导弹影响规律研究

在复杂对抗环境下,目标通过投放红外诱饵干扰红外成像导引头的识别与跟踪,从而影响导弹的精确制导,通过对不同影响因素的分析,揭示红外诱饵对成像导弹的作用机理,总结红外诱饵对导弹制导导引的影响规律。首先建立了红外诱饵、目标及导弹制导的链路仿真模型,在分析总结红外诱饵的主要影响因素基础上,分别评估了红外诱饵的投放距离、导引头图像目标识别时间及多颗诱饵弹投放间隔等因素对导弹制导导引的影响,给出了各因素对制导系统及导引系统影响的仿真结果,总结分析红外诱饵对红外成像导弹的影响机理及影响规律。     

基于亚像元坐标的像素频率误差补偿方法

详细介绍了一种星敏感器像素频率误差补偿方法并结合实际实验数据对其补偿效果进行验证。首先依据阈值分割的星点提取算法,分析了像素频率误差产生的几个主要原因。然后改进原有的星点质心定位点扩散函数,提出了一种基于亚像元坐标的像素频率误差补偿方法。最后通过星敏感器微步距实验,与正弦曲线法比较。实验结果表明:在视场中心区域,使用该方法对采样点补偿后像素频率误差减少了65.2%,优于正弦曲线法的52.7%;使用视场中心的误差补偿公式对视场边缘的采样点补偿,像素频率误差减少58.7%,优于正弦曲线法的41.9%。由实验结果可得:较之于正弦曲线法,该误差修正方法不仅具有更好的误差补偿效果,而且在视场范围内具有较强的通用性。     

伺服阀滑阀副叠合量气动测量方法研究

滑阀副叠合量是衡量伺服阀品质的重要指标,叠合量过大则伺服阀出现死区,叠合量过小则容易引起伺服阀零位不稳定。滑阀副叠合量为微米级别,精确检测是伺服阀生产制造的难点也是关键环节,由于滑阀副的结构导致不容易用传统方法测量,通过有限元分析及理论推导介绍了滑阀副气动测量的原理和实现方法,并依此成功制作了气动配磨台,实现了滑阀副叠合量精确测量。     

Experiment and analysis of the neutralization of the electron cyclotron resonance ion thruster

An electron cyclotron resonance ion thruster must emit an electron current equivalent to its ion beam current to prevent the thruster system from being electrically charged.This operation is defined as neutralization.The factors which influence neutralization are categorized into the ion beam current parameters,the neutralizer input parameters,and the neutralizer position.To understand the mechanism of neutralization,an experiment and a calculation study on how these factors influence thruster neutralization are presented.The experiment results show that the minimum bias voltage of the neutralizer was-60 V at the ion beam current of 80 mA for the argon propellant,and a critical gas flow rate existed,below which the coupling voltage increased sharply.Based on the experiment,the neutralization was analyzed by means of a onedimensional calculation model.The computation results show that the coupling voltage was influenced by the beam divergence and the negative potential zone near the grids.