3．7AGeV~（16）O与核乳胶碰撞的靶核碎裂

本文报告３．７ＡＧｅＶ１６Ｏ与核乳胶碰撞的靶核碎裂的实验结果，并与２００ＡＧｅＶ１６Ｏ相应的结果作比较。给出了靶核碎片多重数分布，及其与弹核碎片之间的关联，以及靶核各类碎片之间的关联。     

3．7AGeV~（16）O与核乳胶碰撞的相对论性粒子发射

报告３．７ＡＧｅＶ１６Ｏ与核乳胶碰撞的弹核α粒于和Ｈ碎片的多重数分布，以及簇射粒子的多重数分布及其与靶核碎片和弹核碎片之间的关联．     

200AGeV~(16)O与乳胶作用的弹核碎裂

本文报告200 A GeV ~(16)O与核乳胶相互作用的弹核碎裂的实验结果,给出了电磁离解事例和核反应事例的百分比,碎片电荷分布,及核反应事例的氦碎片多重数分布,讨论了描述碰撞强烈程度的量。     

原子核乳胶中靶核重碎片径迹的结构

本文研究低能碳离子的径迹宽度对电荷和速度的依赖关系,并给出了低能碳离子在 NIKFI-BR2型核乳胶中的电离损失——动能和射程——动能曲线,为靶核重碎片能谱的测定提供了依据.     

科学家提出预言超重核Qα值的新方法

中科院近代物理所原子核理论组研究人员近期研究了超重核衰变能之间存在的关联以及对称能对于超重核Qα值同位旋依赖性的影响,提出了一个描述邻近超重核α衰变能之间的关联和预言超重核Qα值的简单公式：     

14.6AGcV~(16)O与核乳胶靶相互作用中的靶核碎裂与射弹碎裂

本文报告和分析了14.6 A GeV ~(16)O与核乳胶靶相互作用的实验数据.结果表明,在高能重离子碰撞中,靶核碎裂有能量无关和射弹大小无关特性;射弹碎裂也具有能量无关特性;靶核热化过程存在“饱和效应”.     

高能~（16）O和~（32）S碎裂中的条件矩关联

实验得到了３．７ＡＧｅＶ１６Ｏ、２００ＡＧｅＶ１６Ｏ和２００ＡＧｅＶ３２Ｓ在核乳胶中碎裂的碎片电荷分布的条件矩，观测到条件矩间呈对数关联，且关联行为本身对不同入射能量、不同弹核大小和不同反应机制没有太大差别。     

基于核偏最小二乘回归的顾客满意度指数模型

本文将核偏最小二乘方法引入顾客满意度指数模型,既保持了偏最小二乘方法对样本数据的分布没有要求的特点,有效地处理自变量之间的多重共线性,又能利用核函数的非线性映射能力,较好地反映顾客满意度与各影响因素之间的非线性关系。     

问专家

正如果月球爆炸,会怎么样?首先,月球会怎么爆炸?它可能会由于受到巨大的外力冲击而被瓦解,例如一个能量足够强的正面碰撞。将产生什么样的碎片由撞击的具体情况所决定,高速撞击会产生大量的蒸汽,然后会迅速重新凝结成数十亿块冰。如果是低速碰撞,产生的碎片大小可能会从几十到数百千米不等,大量的碎片会被熔化。盘旋在月球和地球之间的碎片是不稳定的,     

填数趣题四则

打碎花瓶是常有的事,人们一般将其一扔了事,不曾思考过什么。这里头有规律吗?答案是肯定的。丹麦科学家雅各布·博尔则是将碎片按大小排列并称过质量之后,碎片重量之间有着严谨的倍数关系:最大碎片与次大碎片,次大碎片与中等碎片,中等碎片与较小的碎片,它们之间的比例均为16∶1     

The dynamics of nuclear reactions

The dynamics of nuclear reactions are surveyed on an elemental basis with emphasis upon the c.g. system of coordinate axes. Corrections are given for angular distributions, angular straggling, and thin target straggling.     

Finite-time distributed localization and multi-orbit circumnavigation with bearing-only measurements

This paper investigates the localization and circumnavigation problem of a stationary target by multiple agents with multi-orbit within finite time. The agents can only obtain their own positions and the bearing information of the target. They are required to travel along their prescribed trajectories in three-dimensional (3-D) space and circumnavigate the target. First, a novel finite-time distributed positional estimator, using bearing-only measurements, is developed for agents to localize the target. Afterward, with the estimate of the target position, a distributed control law is designed to steer the agents to circumnavigate the target on different orbits with any preconcerted angular spacing distribution pattern within finite time. Simultaneously, the corresponding stability and convergence analyses are presented. Finally, simulation results are provided to demonstrate the effectiveness of the theoretical results.     

Finite-time target localization and multicircular circumnavigation with bearing-only measurements

This paper studies the finite-time localization and multicircular circumnavigation problem of an unknown stationary target via a networked multi-agent system using bearing-only measurements. To enhance the convergence rate of estimation, a novel estimator is developed to enable the agent to localize the target in finite time. At the same time, with the estimated target position, a distributed controller is designed such that the agents circumnavigate the target along different orbits with any prescribed angular spacing in finite time. In terms of Lyapunov theory and cascade control strategy, finite-time stability of the overall system including the estimator and controller are analyzed rigorously. Besides, the proposed algorithms guarantee that the agents can keep a safe distance from the target in the whole movement process, and high angular velocity can be avoided even if the circumnavigation radius becomes small. Finally, to corroborate the theoretical results, two simulation examples are given.     

Cooperative localization and circumnavigation of multiple targets with bearing-only measurements

This paper studies the multi-target localization and circumnavigation problem for a networked multi-agent system using bearing-only measurements. A more general case that only some of the agents are responsible for measuring the bearing angles with respect to the targets is considered. First, a novel estimator is developed for the agents to locate the targets collaboratively, based on which the geometric center of multi-target is reconstructed by each agent. Then, an estimator-based distributed controller is proposed to steer the agents, such that they can enclose the targets along different circles centered at the geometric center of multi-target with any desired angular spacing. By using Lyapunov stability theory, graph theory and consensus algorithm, global exponential stability of the overall system is analyzed rigorously. Besides, it is proved that bounded angular velocity of each agent and collision avoidance between the target and agent can be guaranteed in the whole movement process. Finally, numerical simulations are given to corroborate the theoretical results.     

On the equivalence of pursuer strategies and the lack of nash equilibrium in a visibility pursuit-evasion game

This work addresses a finite-time visibility-based target tracking problem. The aim of the pursuer is to keep the evader within its field of view, while the evader wants to escape the pursuer’s surveillance. Some main contributions of the work are the following: (1) It is proven that minimizing the travel time is equivalent to maximizing the definite integral of the angular speed of the border of the pursuer visibility region. (2) Using Euclidean geometry and set theory methods, the optimality of the player trajectories is demonstrated. (3) It is shown that the motion strategies provided in previous works are not always in Nash equilibrium.     

Introducing structure management in automatic reference resolution: An XML-based approach

References to parts of structured documents use their structure to locate the piece of document which is the reference target. On the other hand, XML has become an increasingly important language for structured documents. One of its most important related languages is XPath, the language that permits fragments of XML documents to be selected. In this article we present a methodology, and an application case, to automatically extract and solve references to fragments of structured documents. This approach combines structure manipulation and information extraction, to enhance reference extraction tools by improving the precision of the references extracted. We take advantage of XML markup to locate the position within the structure in which the references are found. The use of XPath, one of the most important XML related languages, for reference resolution is original: the resolution tool automatically builds XPath expressions. This proposal is inspired (and implemented) from our work with legislative documents.     

Robust tracking-surveillance and landing over a mobile target by quasi-integral-sliding mode and Hopf bifurcation

This paper addresses the problem of a robust UAV tracking, surveillance and landing of a mobile ground target. The translational and angular dynamics of the vehicle are affected by bounded uncertainties; a Quasi-Integral Sliding Mode control is designed to obtain robustness from nearly the initial time. The flying mission considers three different dynamics of movement: the take-off to the desired altitude, the relative circular surveillance motion around the mobile ground target and eventually precise landing over the ground vehicle. This paper introduces a novel dynamic motion planning generator to perform such tracking maneuvers. It is based on the solution of a second order nonlinear differential equation, whose solution is force to move in a set of new parameterized ‘Bifurcation Sliding Mode Surfaces’ that exploit the Hopf Bifurcation properties to change the dynamic around the equilibrium point. A temporal switching technique is introduced for changing between three different bifurcation sliding surfaces at different time intervals. To illustrate that the quadcopter effectively performs the desired maneuvers, a computer animation is provided at the end of the paper.     

Finite-time sliding mode attitude control for rigid spacecraft without angular velocity measurement

The continuous finite-time nonsingular terminal sliding mode (NTSM) attitude tracking control for rigid spacecraft is investigated. Firstly, a finite-time attitude controller combined with a new adaptive update law is designed. Different from existing controllers, the proposed controller is inherently continuous and the chattering is effectively reduced. Then, an adaptive model-free finite-time state observer (AMFFTSO) and an angular velocity calculation algorithm (AVCA) are developed to estimate the unknown angular velocity. The unique feature of the proposed method is that the finite-time estimation of angular velocity is achieved and no prior knowledge of quaternion derivative upper bound is needed. Next, based on the estimated angular velocity, a finite-time attitude controller with only attitude measurement is developed. Finally, some simulations are presented and the effectiveness of the proposed control scheme is illustrated.     

An optimum non-circular chainwheel design for a bicycle drive system

A new and systematic approach for the analysis and simulation of a non-circular chainwheel in a bicycle drive system is presented. The proposed leg-bicycle model is based on a five-bar linkage and explicit expressions for the kinematics and kinetics are derived. The generated shape of the chainwheel is smoothed to an ellipse, for practical reasons. The performance of this elliptical chainwheel is assessed by comparing the joint moments, leg angular accelerations, crank angular velocities, crank angular accelerations and output forces with those of a conventional circular chainwheel. The results suggest combining the elliptical and circular chainwheels into a single unit, in order to accommodate a wide range of pedalling speeds. At low speeds, the elliptical chainwheel is engaged, but as the speed increases, a switch over to the circular chainwheel is recommended.