弹道跟踪数据的节省参数模型及应用

讨论多设备跟踪同一弹道的数据融合问题。首先给出弹道参数,测元真实信号和测量误差的节省参数模型,由此,得到弹道跟踪数据的节省参数模型。据此研究了测元加权方法。提出了基于残差和基于估精度的测元遴选准则。该方法能明显提高弹道跟踪数据精度,同时还可以对弹道跟踪系统进行精度鉴定。     

OPNET建模机制的研究

在目前的网络规划和设计中,网络仿真软件已成为科研和工程技术人员进行网络建模必备的研发工具.本文介绍了一个功能强大的网络建模和仿真工具OPNET,系统研究了OPNET的三层建模机制,即网络建模、节点建模和进程建模.描述了使用OPNET进行网络仿真研究的基本步骤.最后通过一个实例,论证了OPNET在具体网络规划和设计中的应用,为研究网络仿真技术及利用OPNET进行网络规划和设计提供了重要依据.     

高超声速飞行器准平衡滑翔自适应制导方法

针对高超声速飞行器同时满足终端约束及过程约束的再入滑翔制导问题,提出了一种全新的准平衡滑翔自适应制导方法．该方法充分利用升力式再入飞行中的准平衡滑翔现象,并以准平衡滑翔条件（QEGC）为核心,一方面,利用QEGC的特定弹道形式实现对终端速度及射程的精确解析预测;另一方面,借助QEGC将传统预测类制导方法难以处理的飞行过程约束转化为攻角约束．该算法不依赖于标准轨迹,实现了制导指令倾侧角及攻角均采用解析公式实时解算,使制导方法具备了自适应能力．CAV-H飞行器制导实例仿真表明,该制导方法能够导引飞行器平衡滑翔飞行,满足终端约束和过程约束,并且对任务临时改变具有自适应性．该制导方法的鲁棒性通过Monte Carlo仿真得到验证．     

升阻比对可重复使用运载器爬升特性影响

针对地面助推水平发射的两级入轨空天飞行器,以一级可重复使用运载器气动特性和爬升弹道特性耦合研究为目标,基于二维三自由度弹道方程,通过计算较系统地分析了运载器升阻比对其分离点速度、高度、弹道倾角、动压、最大过载等一系列参数的影响,并与垂直爬升弹道进行了比较.计算结果表明升力爬升弹道较垂直爬升弹道可获得更高的分离点速度,且在小推重比条件下差别尤为明显.同时,通过提高升阻比,可有效提升分离点高度、减小分离点动压以及全弹道最大过载等,并可大幅拓宽分离点弹道倾角的调节范围.最后对地面助推水平发射方式及对应最佳弹道方案进行了讨论,并提出了气动布局设计的关键需求.     

我国首次空间交会对接远距离导引方案设计与飞行验证

针对交会对接任务远距离导引,分析了远距离导引的主要任务及导引控制策略、测控通信支持等方面的需求,进行了远距离导引方案设计,并给出了在我国首次空间交会对接任务中的验证情况.     

无人机群协同跟踪地面多目标导引方法研究

多机协同目标跟踪是无人机系统的典型任务之一.由于军事任务的集群性,在实际中常需要跟踪多个不同的目标.如何使用尽量少的无人机对多个目标实施有效跟踪,以提高系统鲁棒性和定位精度,是一个重要的研究课题.本文针对复杂环境下无人机群协同跟踪地面多目标过程中的关键问题进行研究,设计了复杂环境下无人机群协同跟踪多目标系统架构,提出了考虑遮蔽区域机群跟踪多目标动态分组算法、自适应多模型无迹卡尔曼粒子滤波融合算法和障碍条件下机群协同目标跟踪运动快速导引方法.通过仿真试验和飞行试验,验证了本文方法的有效性.最后,对该领域的下一步研究方向进行了展望.     

基于改进蚁群算法的移动机器人路径规划

为了提高移动机器人在复杂静态环境下快速、精确地实现避障路径规划的能力,在蚁群算法的基础上进行改进,采用最优一最差蚂蚁系统,并且引入最差路径信息素自适应参数以更好地寻找全局最优解。搜索过程中引入起点终点引导函数,优先搜索距离起点远而距终点近的节点。为提高算法的实用性,运用几何方法对路径进行修正处理。从而实现了机器人的快速、精确路径规划。通过计算机仿真研究表明：该算法具有较强的实用性,能明显改善路径规划性能,并且算法简单有效。     

时变能量网络建模与分析

不同类型的能源系统通过能量转换设备(感应电动机、离心泵等)相互耦合,研究能源系统的动态特性及其仿真方法对综合能源系统优化设计及性能分析具有重要的实际意义.为对时变能量网络进行建模和分析,本文从能量本质的角度出发,通过深入探讨能量传递及转换机理,分别建立时变传递线(管)路和能量转换设备的能量网络等值模型.在时变能量网络模型的基础上,提出通过构建时变能量网络方程(包括状态方程和输出方程)对综合能源系统的动态特性进行建模仿真的分析方法,最后通过具体算例对本文所提分析方法的有效性及实用性进行验证.本文的研究内容为时变能量网络的建模、分析、优化及规划奠定了基础.     

弹道中段目标回波平动补偿与微多普勒提取

该文针对弹道目标回波微多普勒过大或过小时平动补偿和微多普勒提取问题,提出了一种时域处理方法.该方法通过多级延迟共轭相乘处理实现平动补偿,通过调整延迟时间实现微多普勒缩放,并根据信号能量差异使用Hough变换进行各信号分量的逐次分离和微多普勒的逐次提取.理论分析和仿真实验均表明:本文方法可以有效进行多分量弹道目标复合运动回波信号平动补偿和微多普勒提取,显著提高雷达探测微动结构的能力.     

蓄压式燃气发生器内弹道分析与预计

针对我国姿态控制和轨道控制液体火箭发动机推进荆输送系统，围绕蓄压式燃气发生器内弹道预计开展研究。探讨了喷管在超临界状态和亚临界状态下其内部燃气流动的变化规律；分析了燃气发生器工作结束后在对流换热和稳态导热条件下燃气发生器和储气瓶内高温燃气与外界环境的换热过程；编写了内弹道计算程序，在试验论证的基础上，表明该程序可初步预计蓄压式燃气发生器内弹道性能。     

Forecasting with an econometric model: The issue of judgemental adjustment

The paper outlines the current state of forecasting with an econometric model. After briefly distinguishing econometric techniques from other statistical approaches and arguing the advantages of this approach the paper concentrates on the issue of judgemental adjustments to models for forecasting purposes. Two types of adjustment are distinguished and the conditions under which each is justified are stated. Guidance in the use of adjustment is offered through a review of considerations in an actual forecasting situation.     

单目视频运动目标轨迹三维重建的平滑约束法

提出了利用单目视频重建运动目标三维轨迹的平滑约束方法.通过引入平滑约束,得到重建运动目标三维轨迹的无约束最优化模型,进而推导出其闭式最优解.提出的平滑约束是对运动目标三维轨迹的本质约束,更具一般性,可以反映目标运动的连续、渐变与平滑特性,与基于离散余弦变换基和多项式基等预先定义基约束相比具有更强的适应性,同时能够直接应用于部分观测数据缺失的情形.给出了单目视频轨迹重建问题的几何解释,并对轨迹重建问题中的唯一性进行分析.仿真和真实单目视频序列上的实验证明了提出方法的有效性和先进性.     

商用车ABS预测控制方法研究

针对商用车制动过程中存在的强烈非线性和模型不确定性问题,建立了整车七自由度转向制动状态空间模型,提出了一种非线性连续预测控制方法,设计了基于滑移率的ABS非线性预测控制器.在控制器设计中,利用泰勒级数展开对系统状态进行适当的截尾处理,获得了系统预测模型,并将ABS路面识别算法引入参考轨迹设计,提出了多路面下的参考轨迹模型.当路况发生变化时,参考轨迹也发生相应的变化,而且在系统中引入了积分反馈,以增强系统的鲁棒性.仿真研究表明,当ABS存在建模误差、载荷变化和干扰时,该非线性预测控制器仍能够获得良好的动态响应和鲁棒性.     

External synchronization of two dynamical systems with uncertain parameters

External synchronization is addressed as two or more dynamical systems with synchronous motions, which is also regarded as master-slave system. In this paper, two dynamical systems, one employs a hysteretic term to model the friction phenomenon, the other involves a hardening stiffness component with the third order of displacement due to flexible deformation, are controlled to converge to the same trajectory. The control strategy is extended from feedback control for all parameters known to adaptive contro...     

Boltzmann's ergodic hypothesis

Summary Boltzmann's ergodic hypothesis is usually understood as the assumption that the trajectory of an isolated mechanical system runs through all states compatible with the total energy of the system. This understanding of Boltzmann stems from the Ehrenfests' review of the foundations of statistical mechanics in 1911. If Boltzmann's work is read with any attention, it becomes impossible to ascribe to him the claim that one single trajectory would fill the whole of state space. He admitted a continuous number of different possible mechanical trajectories. Ergodicity was formulated as the condition that only one integral of motion, the total energy, is preserved in time. The two reasons for this are external disturbing forces and collisions within the system. Boltzmann found it difficult to ascribe ergodic behavior to a single system where the theoretical dependence on initial conditions, though never observed, has to be admitted as possible. To circumvent the dependence, he invented the concept of a microcanonical ensemble.     

A conformationally isoformic thermophilic protein with high kinetic unfolding barriers

The basis for the stability of thermophilic proteins is of fundamental interest for extremophile biology. We investigated the folding and unfolding processes of the homotetrameric Thermoanaerobacter brockii alcohol dehydrogenase (TBADH). TBADH subunits were 4.8 kcal/mol less stable towards guanidinium chloride (GdmCl) unfolding compared to urea, indicating ionic modulation of TBADH stability. Strongly denaturing conditions promoted mono-exponential unfolding kinetics with linear dependence on denaturant concentration. Here TBADH unfolded >40-fold slower when extrapolated from urea as compared to GdmCl unfolding. A marked unfolding hysteresis was shown when comparing refolding and unfolding in urea. An unusual biphasic unfolding trajectory with an exceptionally slow phase at intermediate concentrations of GdmCl and urea was also observed. We advocate that TBADH forms two distinctly different tetrameric isoforms, and likely an ensemble of native states. This unusual supramolecular folding behavior has been shown responsible for formation of amyloidotic yeast prion strains and can have functional importance for TBADH. Received 9 November 2007; received after revision 19 December 2007; accepted 8 January 2008     

Cyclic CMP (cytidine 3′,5′-monophosphate) suppresses changes in human sperm amplitude of lateral head displacement and hyperactivation

Summary The dibutyryl analog of cCMP suppressed sperm amplitude of lateral head displacement and hyperactivation. Sperm motility was inhibited by dibutyryl cCMP with a shift toward less linear trajectory sperm movements. The results suggest a role of cCMP as an inhibitory signal on sperm motility patterns related to sperm capacitation.     

可移动可弯曲输送机转向油缸控制方法研究

以可移动可弯曲输送机为研究对象,对输送机转弯过程中油缸的控制方法进行探讨。建立整机虚拟样机后,依次记录牵引车转弯角度;计算牵引车轨迹;计算各转向油缸对应伸出时间与位移;控制器控制辅助转向;最后完成轨迹跟踪。仿真分析证明该控制方法正确可行。     

Cyclic CMP (cytidine 3',5'-monophosphate) suppresses changes in human sperm amplitude of lateral head displacement and hyperactivation

The dibutyryl analog of cCMP suppressed sperm amplitude of lateral head displacement and hyperactivation. Sperm motility was inhibited by dibutyryl cCMP with a shift toward less linear trajectory sperm movements. The results suggest a role of cCMP as an inhibitory signal on sperm motility patterns related to sperm capacitation.     

Intermediate targets and segmental pathfinding

Neurons must often extend axons over fairly long distances, making multiple changes in their trajectory of growth before arriving at their final target. It has become clear that as growth cones navigate these complex projections, they typically extend toward a number of intermediate targets before they contact their final target. Recent work from a variety of systems has identified intermediate targets that seem to play similar roles in vertebrate and invertebrate nervous system development. From these examples it appears that a general model of axon guidance can be proposed whereby neurons are guided to their targets segmentally. Within each segment, an intermediate target appears to be the primary target for growth cone recognition and thus the completion of the journey to the final target is determined by a series of successful segmental pathfinding decisions.