基于闪动快门的互补序列对的运动模糊图像复原

针对传统曝光模式下运动模糊图像复原的病态性问题,提出了一种基于闪动快门互补序列对的运动模糊图像复原方法 .分析了闪动快门成像原理及其码字序列在频域的相关特性,结合编码序列对之间的信息互补特点,引入Golay互补序列生成理论,构建长度适中的二进制闪动快门互补序列对.互补序列对的联合调制传递函数在频域上实现了信息互补,其曲线对比单码字的调制函数具有更大的最小值和更小的方差值,且其构成了峰值-谷值对应,保证了互补图像序列能够相互补偿由于运动模糊所造成的空间信息损失.引入全变分正则化模型,构造一体化的多帧图像去模糊复原算法框架,实现清晰图像的有效获取.搭建了运动目标实拍仿真成像平台,开展了仿真和实拍运动模糊复原实验.实验结果表明,该方法能够更好地保留场景细节信息,获得高质量的运动模糊复原结果,有效改善复原过程中的负效应.相较于其他几种运动目标成像获取方式,该方法复原图像具有更好的主客观评价结果 .     

基于元胞传输模型的楼梯区域行人运动

针对楼梯区域行人运动进行观测实验,获得行人上下楼过程中的运动数据,通过对数据进行整理与分析,绘制不同过程中流量-密度变化关系图.通过对流密关系图进行定量分析,掌握楼梯区域行人运动特征,并改进原有元胞传输模型,提出楼梯行人运动模型,仿真模拟行人运动过程.模型中,引入势能修正系数,利用异向行人对元胞势能的影响来改变行人的路径选择;引入流量修正系数,描述不同的物理参数对元胞边界最大流量的影响;引入偏移系数,修正移动规则,增强优先方向对行人路径选择行为的影响.然后,通过比较仿真结果与实验数据,对模型及引入参数进行验证和校准.最后,利用校正模型,模拟研究楼梯区域对向行人运动过程,并对势能修正参数进行了灵敏度分析,进一步研究模型参数对行人运动的影响.研究表明,该模型可以模拟刻画楼梯区域行人运动过程,同时验证了楼梯区域行人集散效率跟行人到达率与行人路径选择有关.     

拉伸试验系统的设计

介绍了一套工程力学试验模拟操作系统,该系统使用计算机和数据采集系统,不仅能够完成一般的工程力学实验,而且还可以模拟复杂的工程力学实验,该系统集教学演示,科研开发,工程计算,模拟分析于一体,可广泛用于教学和工程实际。     

基于Mathematica数学软件的玻尔共振实验综合研究

对单自由度线性机械振动的研究常采用玻尔共振仪进行测量与分析,但结合该仪器进行受迫振动过程模拟仿真的研究还较少.本论文采用Mathematica数学软件编写相关仿真程序,对玻尔共振仪受迫振动的幅频特性、相频特性进行数值模拟与解析模拟,并将模拟结果与实验结果进行精度分析,从而对数值模拟和解析模拟两种仿真算法进行优劣分析.此外还使用Mathematica数学软件突破玻尔共振仪的现有实验条件功能局限,通过建立整个振动动力学过程的相图、频谱曲线等,从而可以更为深入地研究机械振动规律,拓展Mathematica数学软件在实验分析中的应用范围.     

轴系运动的数学仿真与轴系误差

进行光电仪器轴系分析与仿真时，将瞄准线看作一个单位向量，用多级旋转变换的方法模拟轴系运动，获得瞄准线的运动位置，实现轴系运动的数学仿真，进行轴系的运动误差分析。PIOGRAM图是一种有效的数学工具，它可以清晰直观地表现这种运动模拟过程和轴系原始误差的产生与传递过程．     

用Mathematica求解线性3自由度系统微振动问题

借助数学软件Mathematica,用矩阵方法对线性3自由度系统微振动问题进行了计算和讨论,并模拟了此力学系统的运动.通过与在普通物理实验室中的实验结果进行对比,在忽略空气阻力和弹簧质量的情况下,其仿真结果更能展现线性3自由度系统的微振动情况.其动画很好地演示了线性3自由度系统的振动情况,使初学者对此模型有非常直观的认识,有助于加深对3自由度系统的认识.     

基于弦振动的混沌实验装置研制

弦振动混沌实验装置主要由非线性振动平台、电子装置与电路系统、虚拟仪器3部分组成.实验装置利用NI myDAQ数据采集卡,结合LabVIEW虚拟仪器实现实时动态测量实验数据,结果与Matlab仿真模拟基本一致,可直观观察和定量研究该系统周期运动与混沌运动的相互转换过程.     

全向凝视红外跟踪系统半实物仿真研究

 为解决全向凝视红外多目标跟踪系统室内调试时无合作目标配合实验难题,提出一种红外多目标半实物仿真系统。该系统由多个可控热源组成,每个热源包括均匀加热的平板和温控装置。改变光栏大小和温度分布,模拟不同距离、不同大小的目标。热源安装在三维运动的载体上,以不同速度、方向运动可模拟不同目标的运动轨迹。对3个红外模拟目标600帧图像的采集和处理,实现了航迹重迭、交叉和分离的全过程仿真,验证了本实验平台的模拟精度。     

基于Geant4的卢瑟福散射计算机模拟

利用Geant4对卢瑟福散射实验进行仿真模拟,改变模拟过程中的相关参数以达到不同实验条件的要求。对模拟过程中收集的数据进行分析得到的结果符合卢瑟福散射关系式。这说明利用计算机模拟卢瑟福散射实验是可行的。本文中的实验对大学物理实验教学的开展有很大的意义。     

基于Virtools的平抛运动仿真实验的设计与实现

三维仿真实验能够模拟逼真的实验场景和现象帮助学生理解复杂的物理原理,并激发学生的学习兴趣.但是,专业的研究团队制作的商业仿真实验软件售价太高,无法在课堂推广.本研究小组将以Virtools仿真软件为开发平台制作出一系列的虚拟仿真实验.本论文以平抛运动实验为例,介绍了平抛运动仿真实验的制作过程,主要包括分析与设计、模型的构建、交互功能设计和作品发布四个步骤.在论文的最后部分,介绍了仿真实验在课堂实践的成效并对物理仿真实验的发展前景进行了展望.     

Unsteady processes in machines

Couplings in machines and mechanisms always have play and friction. While under loading, stick-slip phenomena and impact events can take place. Such processes are modeled as multibody systems whose structure is time variant or unsteady. The time-variant number of degrees of freedom is due to stick-slip contacts. The coupling characteristics become unsteady, for instance there exist jumps in the loads, if impacts occur. For establishing a uniform theory for such phenomena we use a Lagrangian approach connecting the additional constraint equations and the equations of motion by Lagrange multipliers, which are proportional to the constraint forces. Stick-slip and impact events are evaluated by indicator functions leading to special numerical algorithms for the search of switching points. Contact problems are formulated as a complementarity problem which can be solved by efficient algorithms. The theory is applied to rattling in gears, impact drilling machines, turbine blade dampers, and a woodpecker toy. In some of these applications, chaos as a result of bifurcations is possible, which results from variations in the parameters. (c) 1994 American Institute of Physics.     

The Depinning Transition in Presence of Disorder: A Toy Model

We introduce a toy model, which represents a simplified version of the problem of the depinning transition in the limit of strong disorder. This toy model can be formulated as a simple renormalization transformation for the probability distribution of a single real variable. For this toy model, the critical line is known exactly in one particular case and it can be calculated perturbatively in the general case. One can also show that, at the transition, there is no fixed distribution accessible by renormalization which corresponds to a disordered fixed point. Instead, both our numerical and analytic approaches indicate a transition of infinite order (of the Berezinskii–Kosterlitz–Thouless type). We give numerical evidence that this infinite order transition persists for the problem of the depinning transition with disorder on the hierarchical lattice.     

Nonlinear non-extensive approach for identification of structured information

The problem of separating structured information representing phenomena of differing natures is considered. A structure is assumed to be independent of the others if can be represented in a complementary subspace. When the concomitant subspaces are well separated the problem is readily solvable by a linear technique. Otherwise, the linear approach fails to correctly discriminate the required information. Hence, a non-extensive approach is proposed. The resulting nonlinear technique is shown to be suitable for dealing with cases that cannot be tackled by the linear one.     

The Decay of Unstable Noncommutative Solitons

 We study the classical decay of unstable scalar solitons in noncommutative field theory in 2+1 dimensions. This can, but does not have to, be viewed as a toy model for the decay of D-branes in string theory. In the limit that the noncommutativity parameter θ is infinite, the gradient term is absent, there are no propagating modes and the soliton does not decay at all. If θ is large, but finite, the rotationally symmetric decay channel can be described as a highly excited nonlinear oscillator weakly coupled to a continuum of linear modes. This system is closely akin to those studied in the context of discrete breathers. We here diagonalize the linear problem and compute the decay rate to first order using a version of Fermi's Golden Rule, leaving a more rigorous treatment for future work. Received: 16 January 2003 / Accepted: 21 March 2003 Published online: 7 May 2003 Communicated by H. Araki, D. Buchholz, and K. Fredenhagen     

Two-dimensional perturbations in a scalar model for shear banding

We present an analytical study of a toy model for shear banding, without normal stresses, which uses a piecewise linear approximation to the flow curve (shear stress as a function of shear rate). This model exhibits multiple stationary states, one of which is linearly stable against general two-dimensional perturbations. This is in contrast to analogous results for the Johnson-Segalman model, which includes normal stresses, and which has been reported to be linearly unstable for general two-dimensional perturbations. This strongly suggests that the linear instabilities found in the Johnson-Segalman can be attributed to normal stress effects.     

Fast time-evolution method for dynamical systems

A fast time-evolution method is developed for systems for which the dynamical behavior can be reduced to the eigenvector/eigenvalue problem. The method does not use the eigenvectors/eigenvalues themselves and is based on a polynominal expansion of the formal operator solution in the eigenfrequency domain. It is complementary to the standard time-integration approaches and allows one to calculate or simulate the state of a system at arbitrary times. The time evolution of, e.g., classical harmonic atomic systems and quantum systems described by linear Hamiltonians can be treated by this method.     

Time-Domain Mapping of Electromagnetic Ray Movement Inside 2D Anisotropic Region

The paper presents the extension of the time-domain mapping method applied to 2D billiard problem inside an anisotropic region bounded by ellipse [1]. In this paper, it has been considered the ray movement inside 2D anisotropic region bounded by arbitrary differentiable curve. It has been proved that the problem can be one-to-one mapped onto 2D mathemeatical billiard problem inside the region possessing isotropic properties by linear transformation of group velocity hodograph and boundary with the same coefficient, which is equal to anisotropy of the ray group velocity, simultaneously. The main features of the ray movement inside 2D anistropic region are discussed.     

Displacement-noise-free gravitational-wave detection with a single Fabry-Perot cavity: A toy model

We propose a detuned Fabry-Perot cavity, pumped through both the mirrors, as a toy model of the gravitational-wave (GW) detector partially free from displacement noise of the test masses. It is demonstrated that the noise of cavity mirrors can be eliminated, but the one of lasers and detectors cannot. The isolation of the GW signal from displacement noise of the mirrors is achieved in a proper linear combination of the cavity output signals. The construction of such a linear combination is possible due to the difference between the reflected and transmitted output signals of detuned cavity. We demonstrate that in low-frequency region the obtained displacement-noise-free response signal is much stronger than the -limited sensitivity of displacement-noise-free interferometers recently proposed by S. Kawamura and Y. Chen. However, the loss of the resonant gain in the noise cancelation procedure results is the sensitivity limitation of our toy model by displacement noise of lasers and detectors.     

Clifford Space as a Generalization of Spacetime: Prospects for QFT of Point Particles and Strings

The idea that spacetime has to be replaced by Clifford space (C-space) is explored. Quantum field theory (QFT) and string theory are generalized to C-space. It is shown how one can solve the cosmological constant problem and formulate string theory without central terms in the Virasoro algebra by exploiting the peculiar pseudo-Euclidean signature of C-space and the Jackiw definition of the vacuum state. As an introduction into the subject, a toy model of the harmonic oscillator in pseudo-Euclidean space is studied.     

Classical Behavior After a Phase Transition: I. Classical Order Parameters

We analyze the onset of classical field configurations after a phase transition. Firstly, we motivate the problem by means of a toy model in quantum mechanics. Subsequently, we consider a scalar field theory in which the system-field interacts with its environment, represented both by further scalar fields and by its own short-wavelength modes. We show that for very rapid quenches, the order parameter can be treated classically by the time taken for it to achieve its ground state values (spinodal time).