Analysis and approximation of performance bound for two-observer bearings-only tracking

This paper presents the analytic recursive formulas of Cramér-Rao lower bound (CRLB) for the switching models system, in which the target moves either with a constant velocity or with a constant speed and a constant turn rate. For the case of two-observer bearings-only maneuvering target tracking, a reliable maneuver detection method is investigated and then utilized to approximate the theoretic CRLB. Finally, to demonstrate the agreement between the approximated CRLB using the proposed maneuver detection method and the theoretic one, a large number of Monte-Carlo runs under different maneuvering scenarios are conducted. Correctness of the analytic recursive formulas of CRLB and effectiveness of the proposed maneuver detection method are verified from these simulations.     

目标运动分析的前向与后向测距测速算法

目标运动分析中测距测速的精度与目标在空间的距离以及运动方式有关,为了提高目标在相向运动和相背运动下的距离和速度的估值精度,提出了前向和后向测距测速的概念,在此基础上给出了前向后向混合算法,对距离和速度的估计精度进行了理论分析。该算法利用目标航迹上前面的M个到达时间（TOA）和后面的N个TOA对当前位置的距离和速度进行估计,兼顾了算法性能和估值的时间延时特性。仿真结果验证了前向后向混合算法的性能总是好于同样数据量的前向或后向算法的性能。     

纯方位目标定位观测器轨迹的 快速优化算法

在移动传感器网络中,观测器与目标的相对位置对目标的定位性能有重要的影响.为了提高目标的定位精度,提出了一种观测器运动轨迹的优化算法.算法把目标均方位置误差作为优化对象,使用扩展卡尔曼滤波器估计目标的位置.算法以目标和观测器的方位分布关系为基础,减小了观测器最优位置的搜索范围.仿真结果表明,使用多个观测器进行目标定位,滤波收敛速度快,定位误差小.最后给出了单个和多个观测器的"最优"运动规则.     

多基阵纯方位非机动目标跟踪可观测性研究

可观测性分析是跟踪系统进行目标跟踪的前提和基础,只有满足可观测条件才能对系统进行正确求解,从而实现对目标的有效跟踪。针对多(三部或以上)基阵纯方位非机动目标跟踪系统的非线性特点,将观测方程伪线性化后,应用线性系统可观测性判定定理对系统的可观测性进行系统分析,并得到该系统的可观测性判定条件,仿真验证了所得结论的正确性。     

The effects of platform motion and target orientation on the performance of trackball manipulation

The trackball has been widely employed as a control/command input device on moving vehicles, but few studies have explored the effects of platform motion on its manipulation. Fewer still have considered this issue in designing the user interface and the arrangement of console location and orientation simultaneously. This work describes an experiment carried out to investigate the performance of trackball users on a simple point-and-click task in a motion simulator. By varying the orientation of onscreen targets, the effect of cursor movement direction on performance is investigated. The results indicate that the platform motion and target orientation both significantly affect the time required to point and click, but not the accuracy of target selection. The movement times were considerably longer under rolling and pitching motions and for targets located along the diagonal axes of the interface. Subjective evaluations carried out by the participants agree with these objective results. These findings could be used to optimise console and graphical menu design for use on maritime vessels.

Statement of Relevance: In military situations, matters of life or death may be decided in milliseconds. Any delay or error in classification and identification will thus affect the safety of the ship and its crew. This study demonstrates that performance of manipulating a trackball is affected by the platform motion and target orientation. The results of the present study can guide the arrangement of consoles and the design of trackball-based graphical user interfaces on maritime vessels.     

The effects of platform motion and target orientation on the performance of trackball manipulation

The trackball has been widely employed as a control/command input device on moving vehicles, but few studies have explored the effects of platform motion on its manipulation. Fewer still have considered this issue in designing the user interface and the arrangement of console location and orientation simultaneously. This work describes an experiment carried out to investigate the performance of trackball users on a simple point-and-click task in a motion simulator. By varying the orientation of onscreen targets, the effect of cursor movement direction on performance is investigated. The results indicate that the platform motion and target orientation both significantly affect the time required to point and click, but not the accuracy of target selection. The movement times were considerably longer under rolling and pitching motions and for targets located along the diagonal axes of the interface. Subjective evaluations carried out by the participants agree with these objective results. These findings could be used to optimise console and graphical menu design for use on maritime vessels. STATEMENT OF RELEVANCE: In military situations, matters of life or death may be decided in milliseconds. Any delay or error in classification and identification will thus affect the safety of the ship and its crew. This study demonstrates that performance of manipulating a trackball is affected by the platform motion and target orientation. The results of the present study can guide the arrangement of consoles and the design of trackball-based graphical user interfaces on maritime vessels.     

Fundamental properties of infinite trees

Infinite trees naturally arise in the formalization and the study of the semantics of programming languages. This paper investigates some of their combinatorial and algebraic properties that are especially relevant to semantics.This paper is concerned in particular with regular and algebraic infinite trees, not with regular or algebraic sets of infinite trees. For this reason most of the properties stated in this work become trivial when restricted either to finite trees or to infinite words.It presents a synthesis of various aspects of infinite trees, investigated by different authors in different contexts and hopes to be a unifying step towards a theory of infinite trees that could take place near the theory of formal languages and the combinatorics of thefree monoid.     

Fundamental properties of quaternion spinors

The interior structure of arbitrary sets of quaternion units is analyzed using general methods of the theory of matrices. It is shown that the units are composed of quadratic combinations of fundamental objects having a dual mathematical meaning as spinor couples and dyads locally describing 2D surfaces. A detailed study of algebraic relationships between the spinor sets belonging to different quaternion units is suggested as an initial step aimed at producing a self-consistent geometric image of spinor-surface distribution on the physical 3D space background.     

Overlay architectures for file distribution: Fundamental performance analysis for homogeneous and heterogeneous cases

Peer-to-peer networks have been commonly used for tasks such as file sharing or file distribution. We study a class of cooperative file distribution systems where a file is broken up into many chunks that can be downloaded independently. The different peers cooperate by mutually exchanging the different chunks of the file, each peer being client and server at the same time. While such systems are already in widespread use, little is known about their performance and scaling behavior. We develop analytic models that provide insights into how long it takes to deliver a file to N clients given a distribution architecture. Our results indicate that even for the case of heterogeneous client populations it is possible to achieve download times that are almost independent of the number of clients and very close to optimal.     

卫星搜索移动目标问题中的目标运动预测方法研究

目标运动参数未知给移动目标搜索计划编制引入了不确定性,降低了卫星的侦察效能.为了降低不确定性和优化卫星的搜索方案,在采用贝叶斯规则对目标概率分布更新的基础上,提出一种基于高斯分布的目标转移概率密度函数,并绐出相应的转移计算方法.采用最大发现概率和与最大覆盖作为搜索策略,建立移动目标搜索仿真场景.结果显示,该方法能够减少卫星搜索计划制定过程中的不确定性,降低了搜索的盲目性,提高了卫星的效能.     

雷达目标特征信号与运动模式的相关性研究

空中目标的运动模式与自身姿态紧密相关,进而与目标特征信号也存在相关性.首先分析不同运动模式下目标姿态角变化率,然后推导姿态敏感雷达特征信号表示,包括雷达散射截面(RCS)、角闪烁线偏差与横向分辨多普勒像,接着以两散射点组成的简单目标为例,推导得到了上述特征信号与目标姿态角变化率之间的关系式,从而建立了目标特征信号与运动模式之间的联系,最后通过对多散射点复杂目标特征信号的仿真验证了理论分析的正确性,结果表明利用雷达特征信号区分目标不同运动模式是可行的,所得结论对基于特征信号的运动模式辨识、机动检测以及机动目标跟踪和拦截等研究具有重要意义.     

Fundamental operational laws of computer system performance

Summary A number of laws are derived which establish relationships between throughput, response time, device utilization, space-time products and various other factors related to computer system performance. These laws are obtained through the operational method of computer system analysis. The operational method, which is formally introduced in this paper, differs significantly from the conventional stochastic modeling approach and is based on a set of concepts that correspond naturally and directly to observed properties of real computer systems. The operational laws presented in this paper apply with complete precision to all collections of observational data, and they are similar to fundamental laws found in other areas of engineering and applied science.A preliminary version of this paper was published in the Proceedings of the IFIP/ACM SIGMETRICS International Symposium on Computer Performance Modeling, Measurement and Evaluation, Cambridge (Mass.) March 1976, p. 200–210     

Fundamental properties of reset control systems

Reset controllers are linear controllers that reset some of their states to zero when their input is zero. We are interested in their feedback connection with linear plants, and in this paper we establish fundamental closed-loop properties including stability and asymptotic tracking. This paper considers more general reset structures than previously considered, allowing for higher-order controllers and partial-state resetting. It gives a testable necessary and sufficient condition for quadratic stability and links it to both uniform bounded-input bounded-state stability and steady-state performance. Unlike previous related research, which includes the study of impulsive differential equations, our stability results require no assumptions on the evolution of reset times.     

目标运动要素解算方法的研究

提出了适用于水下目标运动要素估算的最小二乘估计和Kalman滤波估计模型 ,本模型被用于航空反潜作战中目标运动要素估算 ,取得了较好的效果。     

Optimal sensor placement and motion coordination for target tracking

This work studies optimal sensor placement and motion coordination strategies for mobile sensor networks. For a target-tracking application with range sensors, we investigate the determinant of the Fisher Information Matrix and compute it in the 2D and 3D cases, characterizing the global minima in the 2D case. We propose motion coordination algorithms that steer the mobile sensor network to an optimal deployment and that are amenable to a decentralized implementation. Finally, our numerical simulations illustrate how the proposed algorithms lead to improved performance of an extended Kalman filter in a target-tracking scenario.     

iSCSI Target研究与性能测试

为了实现廉价,高效的iSCSI Target,分析了iSCSI协议的核心内容.在此基础上,对iSCSI Target的数据传输率和CPU利用率等方面的性能进行了详细的测试.分析了CPU利用率、数据块大小、Initiator台数和其它一些因素对Target性能的影响,并且验证了所得的结论,提出了一个改进iSCSI Target性能的假设.实验结果表明,影响Target性能的因素有很多,需要综合考虑来提高Target性能.     

Electrofluidic displays: Fundamental platforms and unique performance attributes

Abstract— Electrofluidic displays transpose brilliant pigment dispersions between a fluid reservoir of small viewable area and a channel of large viewable area. Recent progress in the technology, a new multi‐stable device architecture, and a novel approach for segmented displays that can display pigment without the optical losses of pixel borders is reported. The fundamental aspects of electrofluidics that make it compelling for the next generation of e‐paper products is reviewed.     

Effects of uncoupled motion on performance

OBJECTIVES: To determine whether human exposure to vehicle motion specifically affects performance on a similar, yet uncorrelated, driving task and to observe the motion/simulator sickness symptoms that were associated with the real vehicle motion and the driving task. BACKGROUND: Past research has shown uncoupled motion can affect a person's performance on a task as well as induce motion sickness. METHODS: Ten participants (age range = 19-25 years) completed an uncorrelated driving task while seated in a stationary real vehicle and a moving real vehicle. RESULTS: The results show participants took longer to complete the motion condition, t(9) = 1.96, p < .05, and were less accurate, t(9) = 3.73, p < .05. Scores for the Motion Sickness Assessment Questionnaire, t(9) = 3.37, p < .05, and the Simulator Sickness Questionnaire, t(9) = 3.30, p < .05, were significantly higher during the motion condition. CONCLUSIONS: Performance on the task was degraded and motion sickness heightened during the motion condition. APPLICATION: This research has potential implications for military-related tasks such as operating a command and control station or controlling a remote vehicle while simultaneously being a passenger in a real vehicle, as well as for civilian applications such as interacting with a moving map navigation system while driving a car.