Recovery of single event upset in advanced complementary metal-oxide semiconductor static random access memory cells

Using computer-aided design three-dimensional （3D） simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings. It cannot exhibit the recovery effect. It is also indicated that the upset linear energy transfer （LET） threshold is kept constant while the recovery LET threshold increases as the spacing increases. Additionally, the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect, thus strengthening the recovery ability.

Optimal Load Balancing Leveling Method for Multi-leg Flexible Platforms

The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs,the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads.These problems make it quite complex and time consuming to level such a multi-leg platform.Based on rigid body kinematics,an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform,then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs.Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration,an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem.By taking advantage of the concept of supporting stiffness matrix,a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform.At the end,with the concept of supporting stiffness matrix and static transmissibility matrix,an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously.Three numerical examples are given out to illustrate the performance of proposed methods.This paper proposes a method which can effectively quantify all of the legs’ extension at the same time,achieve geometric leveling and legs’ loads balancing simultaneously.By using the proposed methods,the stability,precision and efficiency of auto-leveling control process can be improved.

Optimal setting and placement of FACTS devices using strength Pareto multi-objective evolutionary algorithm

This work proposes a novel approach for multi-type optimal placement of flexible AC transmission system(FACTS) devices so as to optimize multi-objective voltage stability problem. The current study discusses a way for locating and setting of thyristor controlled series capacitor(TCSC) and static var compensator(SVC) using the multi-objective optimization approach named strength pareto multi-objective evolutionary algorithm(SPMOEA). Maximization of the static voltage stability margin(SVSM) and minimizations of real power losses(RPL) and load voltage deviation(LVD) are taken as the goals or three objective functions, when optimally locating multi-type FACTS devices. The performance and effectiveness of the proposed approach has been validated by the simulation results of the IEEE 30-bus and IEEE 118-bus test systems. The proposed approach is compared with non-dominated sorting particle swarm optimization(NSPSO) algorithm. This comparison confirms the usefulness of the multi-objective proposed technique that makes it promising for determination of combinatorial problems of FACTS devices location and setting in large scale power systems.

Applications of Localized Phase Compensation Method to Design a Stabilizer in a Multi-machine Power System

为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局部模振荡。第2个实例是就地补偿设计附加在静态同步补偿器（static synchronous compensator,STATCOM）上的稳定器,抑制多机电力系统中的区域模振荡,并给出在一个16机电力系统中的应用计算和仿真结果。

STATICS ANALYSIS AND OPENGL BASED 3D SIMULATION OF COLLABORATIVE RECONFIGURABLE PLANETARY ROBOTS

Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configuration of the two-robot, and to find some restrictions of kinematics for the cooperation. Methods Multirobot cooperation theory is used in the whole study process. Inverse kinematics of the robot is used to form a desired configuration in the cooperation process. Static equations are established to analyze the relations between the friction factor, the configuration of robots and the maximum height of a stair. Kinematics analysis is used to find the restrictions of the two collaborative robots in position, velocity and acceleration. Results 3D simulation shows that the two cooperative robots can climb up a stair under the condition of a certain height and a certain friction factor between robot wheel and the surface of the stair. Following the restrictions of kinematics, the climbing mission is fulfilled successfully and smoothly. Conclusion The maximum height of a stair, which the two cooperative robots can climb up, is involved in the configuration of robots, friction factor between the stair and the robots. The most strict restriction of the friction factor does not appear in the horizontal position. In any case, the maximum height is smaller than half of the distance between the centroid of robot1 with the centroid of robot2. However, the height can be higher than the radius of one robot wheel, which profit from the collaboration.

Analysis of Optimization for Preliminary Design of Multi-Component Mooring Systems

Multi-component mooring systems become widely used in deep water position-keeping of drilling and production platforms. However, versatile materials make it difficult to design appropriate mooring lines made of several segments. Based on catenary equations of a multi-component mooring line at a specific water depth, this paper establishes a minimum model for designing this kind of lines. The model is solved by Genetic Algorithm and Multi-Objective Planning respectively. The model is verified by its application to a practical mooring design assignment—a quasi-static analysis for a large semi-submersible. The optimal result is finally obtained with the aid of design graphs.

Static Optimization of a Compliant Vertical Access Riser

The compliant vertical access riser (CVAR) is a new riser concept with good compliance;it can significantly reduce operating costs by eliminating the need for additional machines to operate wells directly on the platform.In this study,we determined the optimal riser parameters in terms of the stress and riser weight by optimizing the CVAR,and we compared the optimization resuits.A two-dimensional nonlinear static CVAR model was deduced according to the principles of virtual work and variation,and the model was verified using MATLAB.Design of experiments and Kriging method were used to reduce the number of sample calculations and improve the modeling accuracy.An appropriate selection of the multi-objective optimization problem (MOP) and the non-dominated sorting genetic algorithm helped to optimize the CVAR design.The non-dominated sorting genetic algorithm Ⅱ was used to solve the Pareto frontier of the optimization model in order to provide decision makers with more choices for the optimization results.After optimizing the riser parameters,the geometry of the riser was smoother,and the stress and stress differences were greatly reduced;the maximum equivalent stresses at the top and bottom were reduced by 36.6% and 44%,respectively.In addition,the stress difference in the buoyancy block area was reduced by 20.9%,and the weight of the riser was increased significantly by 28.1%.

Bucket Group Effect of the Composite Multi-bucket Structure

As a novel type of foundation in beach and shallow sea, the bucket structure is especially suitable for complex conditions such as soft clay ground and the worse types of sea environments. In this paper, the bearing capacity of a multi-bucket structure is studied by experiments with a single bucket and four-bucket foundation in a saturated sand layer. Based on the experimental data and numerical analysis results, the bearing capacity behavior and the bucket group effect are compared and analyzed. Furthermore, some influential factors, such as the soil type, the ratio of length to diameter L/D, the ratio of the bucket spacing to the bucket diameter S/D, and the bucket number are introduced and their effects on the multi-bucket structural capacity are investigated. The vertical static capacity adjustment factor is introduced to evaluate the bucket group effects of the multi-bucket foundation.

长联大跨钢桁梁桥-无砟轨道静动力适应性研究

研究目的:为研究高速铁路长联大跨钢桁梁桥铺设无砟轨道的适应性,本文以我国首座铺设无砟轨道的长联大跨钢桁梁桥-郑济高铁黄河特大桥为研究对象,基于梁轨相互作用原理建立钢桁梁桥-无砟轨道精细化非线性分析模型,分析无缝线路强度、变形协调性、轨道静态铺设精度指标的变化规律,研究钢桁梁桥-无砟轨道静力适应性;基于车桥耦合动力学理论建立车-轨-桥耦合动力学模型,分析不同温度下的车桥耦合振动及行车性能,研究钢桁梁桥-无砟轨道动力适应性。研究结论:(1)长联大跨钢桁梁桥-无砟轨道体系的无缝线路强度、变形协调性、轨道静态不平顺及行车性能指标等指标均满足规范要求,静动力适应性表现良好;(2)温度梯度对无砟轨道层间压缩量、扣件滑移量影响显著,与整体温差相比,分别增大了51.08%和50.00%;(3)温度梯度劣化轨道静态中短波不平顺,与整体温差相比,10 m弦长、30 m基线长指标分别增大了144.12%和76.06%,60 m弦长指标基本不变;(4)温度梯度对轮重减载率影响显著,对脱轨系数、横向轮轨力等其他安全性和舒适度指标影响较小。

立式加工中心龙门架的多步复合优化设计

为了提高立式加工中心的静动态特性,通过模态分析与谐响应分析对机床整机进行薄弱环节的识别,发现龙门架结构设计不合理,导致机床在竖直方向存在较大变形。针对龙门架的不合理设计,对其采用拓扑优化与二维截面优化相结合的方法确定材料分布情况;并基于MOGA遗传算法,以龙门架质量、最大静变形量与第1阶固有频率为优化目标,对其关键尺寸进行多目标参数优化;再将优化结果与原型进行对比验证。结果表明,龙门架的最大静变形量减小了34.61%,质量减小了7.64%,第1阶固有频率提高了6.54%;整机在X、Y和Z这3个方向的最大振幅均有所降低,各波峰的位置均有不同程度的后移,提高了加工中心整机的静动态综合性能;验证了龙门架的优化效果。

底部填芯多节段预制拼装空心桥墩抗震性能试验研究

为提高预应力连接预制节段拼装桥墩的抗震性能及施工便捷性,设计了一种底部填芯多节段预制拼装空心桥墩并进行了抗震试验研究。提出了该新型预制节段拼装桥墩填芯高度设计方法,设计了底部填芯预制节段拼装桥墩缩尺模型并开展了拟静力试验测试。基于试验结果分析了该新型桥墩在水平循环往复作用下的裂缝发展过程、失效模式、滞回性能、延性性能、耗能能力及桥墩接缝的开口大小等抗震性能。研究结果表明:所发展的底部填芯多节段预制拼装空心桥墩的失效模式为底部节段混凝土局部压溃,但范围较小,所提填芯高度的设计方法可行,可以使桥墩实现预期失效模式。该新型桥墩具有较小的残余位移、优异的耗能能力与延性性能,这表明此桥墩具有优异的抗震性能。

基于MEA-BP神经网络的多孔质轴承参数优化

为了提高圆盘类多孔质静压止推轴承的静态特性,采用思维进化算法(MEA)优化反向传播(BP)神经网络,创建圆盘类多孔质静压止推轴承静态特性的预测模型,完成轴承静态承载力、静刚度以及耗气量的高精度预测,其预测误差分别低于2%、5%以及5%。基于此模型,以最大化静态承载力和静刚度、最小化耗气量为优化目标值,采用遗传算法对轴承的多孔质参数组合进行多目标优化,实现轴承参数的快速优化设计。优化结果表明:此轴承静态承载力提高了64.53%,静刚度提高了31.93%,耗气量降低了56.52%。

基于核空间联合稀疏表示和指数平滑的多基地水下小目标识别

针对多基地水下小目标分类识别问题,本文提出了一种基于核空间联合稀疏表示和指数平滑的多基地水下小目标识别方法 .对水下目标多角度散射信号提取6种典型的具有信息互补性和关联性的特征,提出一种随机森林(Random Forest,RF)和最小冗余最大相关(minimum Redundancy and Maximum Relevance,mRMR)相结合的特征选择方法(RF-mRMR),得出综合的特征重要性排序结果 .通过实验得出分类模型所需的最优特征子集,达到降低数据处理复杂度和提高目标分类结果的目的 .为了捕捉到数据中的高阶结构,在联合稀疏表示模型的基础上,使用核函数将线性不可分的特征数据映射到高维核特征空间.为了充分挖掘稀疏重构后包含在残差波段中的有用信息,使用指数平滑公式对具有一定意义的残差信息进行再利用,最后由核特征空间下的最小误差准则判定目标的类别.应用本文提出的方法对4类目标的海试数据进行识别,结果表明,相较于其他7种对比算法,本文提出的改进方法具有更好的分类性能,而且大多数情况下,本文提出的算法在双基地声呐模式下具有比单基地声呐更高的识别准确率和更低的虚警率.

基于静动态综合估计的无人机蜂群态势感知技术

随着军用无人机技术的快速发展,其作战体系也逐渐从无人机单机作战向蜂群作战转变。为了实现入侵无人机蜂群的反制,亟需探索面向无人机蜂群入侵场景的态势感知技术。目前,无人机蜂群态势感知领域主要在整体概念层面研究态势感知的技术与模型,缺乏具体应用场景下的态势感知技术与仿真平台。本文面向分布式作战战术场景与哈里斯鹰的合围狩猎方式,引入了无人机蜂群的进攻阵型与仿鹰群的无人机蜂群协同攻击模型,使用到达时间差定位算法与联合概率数据关联滤波器获得无人机蜂群轨迹信息,并将无人机蜂群战场态势划分为静态态势与动态态势,分别表示对战场某个时刻态势的理解与战场未来趋势的推断。在此基础上,本文提出了一种基于静动态综合估计的无人机蜂群态势感知技术,涵盖基于模糊规则评价的静态态势感知以及基于蜂群预测推断的动态态势感知。同时,搭建了三维无人机蜂群态势感知仿真平台,实现了入侵无人机蜂群的运动学建模、定位跟踪、战场态势感知以及误差分析等过程,验证了所提态势感知技术的有效性。

两种不同结构静铁芯电磁阀静态电磁力对比分析

为了比较螺线管式静铁芯电磁阀与极柱式静铁芯电磁阀产生的静态电磁力的大小与适用场景,首先建立了两种静铁芯的有限元模型,并通过实验进行了模型的验证;然后对比了两种结构在不同电流、不同气隙下的静态电磁力及静铁芯散热情况。由仿真结果得出,在同等外形体积下,螺线管式静铁芯电磁阀随着线圈电流的增加电磁力稳步增大,但电流过大时线圈温度过高,电流40 A工况下线圈温度达186.2℃,适用于小电流小行程的工作环境;而极柱式静铁芯电磁阀随着线圈的电流增加电磁力上升的速率更快,电磁力也更大,裸露的单层线圈保证了散热,电流40 A工况下温度仅为51.1℃,适用于大电流大行程的工作环境。同时极柱式静铁芯电磁阀电磁力随着极柱数的增加先增大后减小。同等条件下,六级柱式静铁芯电磁阀产生的电磁力最大。可为新品高速电磁阀静铁芯的设计提供理论指导。

多维力传感器静态标定装置的研究进展

为保证多维力传感器测量准确度,必须对该传感器进行静态标定,因此研究多维力传感器静态标定装置具有重要意义。首先,从多维力传感器静态标定需求出发,按工作原理将目前国内外主流使用的多维力传感器静态标定装置划分为静重式和叠加式这两类。然后,介绍了砝码式、杠杆式、自动式这三种静重式多维力传感器静态标定装置和液压式、龙门式、试验机式、移动平台式、电机式这五种叠加式多维力传感器静态标定装置的工作原理,对各种装置的国内外研究现状和存在不足分别进行了评述,并分析对比了各种装置的关键技术特点及优缺点。最后,从通用性、重复性、多维力模拟能力、成本效益等方面对多维力传感器静态标定装置进行了展望,指出了装置的设计和实施面临的挑战。该研究为后续多维力传感器静态标定装置的研创提供了参考。

环形多孔气体静压止推轴承静态性能研究

为提升气体静压止推轴承的静态性能,设计一种新型环形多孔气体静压止推轴承。依据气体润滑原理、采用有限体积法对环形多孔气体静压止推轴承的三维物理模型进行数值模拟,研究节流器上节流孔数量、直径、分布方式和供气压力对气体静压止推轴承静态性能的影响。结果表明:节流孔数量对环形气体静压止推轴承的承载力影响显著,但孔数增加到一定程度后承载力增速放缓;节流孔直径对承载刚度影响较大,随着节流孔直径逐渐减小最佳刚度逐渐增大;节流孔排布方式和供气压力对气体静压止推轴承的静态性能均有明显影响。

一种简单的低成本航姿系统标定及修正方法

在对低成本航姿系统进行加速度计与磁力计的标定中,通常磁力计的信噪比更低,仅使用椭球拟合法标定传感器误差参数结果是不够精确的;为了提高标定结果的准确性,提出了一种在多位置条件下基于椭球拟合约束和点积法的误差参数标定及修正方法;首先,在静态多位置下获取15对低噪声的测量数据并进行椭球拟合标定,其次,用补偿后的磁力计数据分布特征构建椭球约束条件,通过点积法计算地磁矢量与水平面夹角,并以其均方差来量化修正效果,对磁力计中可观性差的轴间不正交误差参数和传感器间非对准误差参数进行修正,最终提升标定效果;仿真和实测的试验结果表明,在同等椭球拟合约束下,该方法相比于独立使用椭球拟合法和点积不变法,地磁矢量与水平面夹角的均方差下降了25%以上,且具有简单易用的特点。

多直流馈入受端电网的最大受电能力估计方法

为保证多直流馈入受端电网稳定运行,提出一种静态稳定约束下多直流馈入受端电网的最大受电能力估计方法。首先,基于奇异值理论推导出多直流馈入受端电网静态电压稳定约束;然后,在考虑静态电压稳定性约束的情况下,建立多直流馈入受端电网优化调度模型;接着,给出一种计及静态电压稳定约束的优化调度模型分段线性求解方法,并基于该方法给出最大受电能力估计方法;最后,通过修改的IEEE39节点系统验证本文所提方法的有效性。

新型桨叶控制系统优化设计研究

针对一种新型桨叶控制系统的活塞开展多目标优化设计研究。首先,建立了活塞的有限元模型,通过静力学分析,确定活塞具有轻量化的潜力;其次,以质量最小、最大位移最小、最大应力最小为优化目标,以结构参数为设计变量,以强度和刚度安全为约束条件,并采用Box-Behnken试验设计结合响应面法建立了优化目标函数的代理模型;然后,采用NSGA-Ⅱ算法进行求解,根据设计变量的优化结果得到优化后的活塞模型;最后,通过对优化后模型进行静力学分析,并与初始模型对比,在保证最大应力和位移均在允许范围内的情况下,活塞质量减小了约22%。通过对优化后模型进行屈曲分析,证明其压杆稳定性良好,验证了该优化设计方法的有效性,为新型桨叶控制系统的高性能设计提供技术基础。