A time saving algorithm for the Monte Carlo method of Metropolis

A time saving algorithm for the Monte Carlo method of Metropolis is presented. The technique is tested with different potential models and number of particles. The coupling of the method with neighbor lists, linked lists, Ewald sum and reaction field techniques is also analyzed. It is shown that the proposed algorithm is particularly suitable for computationally heavy intermolecular potentials.     

Marking algorithm of distinguishing three traffic load states with two encoding states for pre-congestion notification

Pre-congestion notification (PCN) gives an early warning of congestion by marking packets to protect the quality of service of inelastic flows. PCN defines two rates per link: admissible rate (AR) and supportable rate (SR), which divide the PCN traffic load into three states, “no pre-congestion,” “AR pre-congestion,” and “SR pre-congestion.” PCN admission control and flow termination control operate in accordance with these three states. However, only two PCN encoding states, unmarked and PCN marked, can be used due to the requirement of PCN encoding to survive tunneling through a currently used IPsec tunnel. We propose a marking algorithm, which uses the two encoding states, for distinguishing the three states of PCN traffic load. We also propose new admission and flow termination controls, which are based on the proposed marking algorithm, and evaluate their performance. Markings that require fewer PCN encoding states are preferable because the remaining encoding state can be used for a newly added PCN-based control in the future. Furthermore, distinguishing more states with fewer encoding states benefits not only PCN but also general marking techniques because header fields are limited; thus, valuable.     

Minimum-error discrimination between two sets of similarity-transformed quantum states

Using the equality form of the necessary and sufficient conditions introduced in Jafarizadeh (Phys Rev A 84:012102 (9 pp), 2011), minimum error discrimination between states of the two sets of equiprobable similarity transformed quantum qudit states is investigated. In the case that the unitary operators describing the similarity transformations are generating sets of two irreducible representations and the states fulfill a certain constraint, the optimal set of measurements and the corresponding maximum success probability of discrimination are determined in closed form. In the cases that they are generating sets of reducible representations, there exist no closed-form formula in general, but the procedure can be applied properly in each case provided that the states obey some constraints. Finally, we give the maximum success probability of discrimination and optimal measurement operators for some important examples of mixed quantum states, such as generalized Bloch sphere m-qubit states, qubit states and their three special cases.     

A pseudo-linear time algorithm for the optimal discrete speed minimizing energy consumption

Discrete Event Dynamic Systems - We consider the classical problem of minimizing off-line the total energy consumption required to execute a set of n real-time jobs on a single processor with a...     

A dynamic programming algorithm for the distance between two finite areas

The problems of speech recognition and orthographic word correction have been greatly mitigated by the use of dynamic programming techniques for finding the distance between two finite sequences. This paper extends the technique into two dimensions, and presents an algorithm for finding the distance between two finite areas. Applications of the algorithm are suggested.     

An algorithm for finding the intersection lines between two B-spline surfaces

A divide-and-conquer algorithm is presented for finding all the intersection lines between two B-spline surfaces. Each surface is organized as an $\text{n-}\text{branch}$ tree. For each intersection line, an initial point is detected after a depth-first search along one tree, ie the host tree. Extrapolation methods are then used to trace the entire length of the line, thus the line appears naturally in a continuous form. Efficiency of the algorithm is achieved by the employment of an adaptive division strategy and by the careful choice of the representation basis of the patches on both surfaces.     

基于三维小波低频域的彩色视频盲水印算法

视频水印技术是保护数字视频版权的一种有效方法。提出一种基于3D DWT的彩色视频水印算法,按场景以16帧划分视频,在各子段YCbCr颜色空间上对Y分量进行二级三维小波变换,利用三维小波低频帧间系数相近而不相同的特性进行水印嵌入,并实现了水印的盲提取。实验结果表明,该算法在保证含水印视频图像质量的同时具备良好的鲁棒性,对各种视频几何攻击及MPEG压缩均具有较强的抵抗能力。     

基于车头时距交通信号的模糊控制系统的研究

提出了一种基于车头时距的绿灯时间修正算法的交通流模糊控制方案,该方案在自适应模糊控制算法的基础上,增加了绿灯时间修正算法模块,从而对绿信比进行了优化,并用Matlab软件进行了仿真研究。仿真结果表明,在相同的交通环境下,该方法比未进行绿信比优化的自适应模糊控制系统方案有效。     

行星式搅拌釜内固液混合时间的数值计算

行星式搅拌装置内搅拌桨的运动轨迹复杂,对固体颗粒与高黏度聚合物熔体的混合效果较好。混合时间是表征搅拌釜内流体混合状况、评定搅拌釜效率的重要参数之一。利用FLUENT软件数值模拟一种行星式搅拌釜内高黏固液两相混合过程,采用传统混合时间定义方法和体积分数法2种方法计算搅拌桨不同自转转速的混合时间,并将2种方法的计算结果进行比较;采用体积分数法计算搅拌桨不同安装高度时的混合时间。计算中采用欧拉模型,使用动网格技术,利用FLUENT的用户自定义函数确定搅拌桨的速度。数值计算结果表明,采用选取监测点计算混合时间的方法,不同监测点的混合时间有较大差异,为保证全釜内混合均匀,应选取混合时间最长的监测点;选取监测点和体积分数2种混合时间计算方法得到的混合时间基本相同;随着搅拌桨自转转速的提高,混合时间明显缩短;采用釜底加料方式,搅拌桨安装高度从20mm提高到60mm时混合时间缩短。     

Estimations of the errors between the evolving states generated by two Hamiltonians with the same initial state

Time evolution of a quantum system is described by Schrödinger equation with initial pure state, or von Neumann equation with initial mixed state. In this paper, we estimate the error between the evolving states generated by two Hamiltonians with the same initial pure state. Secondly, according to the method of operator–vector correspondence, we give a relation of the Schrödinger equation and von Neumann equation and then estimate the error between the evolving states generated by two Hamiltonians with the same initial mixed state.     

Effect of geometry on fluid mixing of the rhombic micromixers

A planar micromixer with rhombic microchannels and a converging-diverging element has been proposed for its effective mixing. Both CFD-ACE numerical simulations and experiments were used to design and investigate the effect of three parameters (number of rhombi, turning angle and absence or presence of the converging-diverging element) on mixing. Mixing efficiency is dependent upon Reynolds number and geometrical parameters. Through the results of numerical simulation, it is evident that smaller turning angle (α), higher Reynolds number and increasing number of rhombi will result in better fluid mixing due to the occurrence of larger recirculation. The large recirculation is beneficial for both the increased interfacial contact area between two species and the convective mixing. In the numerical simulations, mixing efficiency of 99% was achieved with a most efficient system consisting of three-rhombus mixer with a converging-diverging element at α = 30° and Re = 200. An experimental mixing efficiency of about 94% has been obtained with the same design parameters. As expected, it is lower than the theoretical efficiency but is still very effective. A micromixer with such design can be potentially useful in the future applications of rapid and high throughput mixing.     

差分进化算法的交叉概率因子递增策略研究

为了有效地控制差分进化算法的全局搜索和局部搜索,基于递增交叉概率因子的基本思想,在已有的自适应二次变异差分进化算法的基础上,提出了开口向下抛物线、开口向上抛物线和指数曲线3种非线性的交叉概率因子递增策略,并用4种经典函数对它进行测试。测试结果表明,对于多数连续优化问题,在初始参数相同的情况下,凹函数递增策略优于线性策略,而线性优于凸函数策略。凹函数递增策略能够在不影响收敛精度的情况下较大幅度地提高差分进化算法的收敛速度。     

二维三温能量方程求解 MPI-OpenMP 并行算法研究

二维三温能量方程的求解是惯性约束聚变（ICF）的核心问题。随着 ICF 问题规模的不断扩大和计算机性能的飞速提升,现有的并行算法和软件包已经不再适用。提出了二维三温能量方程的 MPI-OpenMP 并行求解算法,该算法上层使用 MPI 进程进行通信,下层使用 OpenMP 多线程进行核心计算,不但能够适应大规模问题的求解,而且还表现出很好的扩展性和加速比。实验表明,算法在网格规模大小为106的实际物理模型的模拟求解中,48个 MPI 进程192个 OpenMP 线程可以得到39．53倍的加速比;并且随着参与计算的处理器核数的增加,加速比将大幅度地提高。     

Molecular orbital model of the influence of interaction between O2 and aluminosilicate sites on the triplet–singlet energy gap and reactivity

The behavior of O₂ molecule in models of acid aluminosilicate sites on any kind of material was investigated using reliable QM ab initio calculations. The triplet–singlet energy gap of isolated O₂ was calculated at confident levels of theory with different basis sets as a reference. Models of aluminosilicate active sites interacting with oxygen in their singlet and triplet electronic states were considered for two kinds of O₂ arrangements. Geometry optimizations were performed on both non-corrected and corrected BSSE potential energy surfaces, realizing that good modeling of heavy atom–hydrogen interactions is sensitive to BSSE corrections during these processes. Energies were further evaluated at higher level of theory to test tendencies. Singlet oxygen appears more attractive to active aluminosilicate sites than those calculated with triplet oxygen, indicating a source of oxidative efficiency for designed nanostructures containing such molecular residues. It was clearly seen that aluminosilicate groups, appearing ubiquitously in several materials, could reduce the O₂ triplet–singlets energy gap by at least 10 kJ/mol. Some elegant features of oxygen interactions with such sites were further analyzed by means of the atoms in molecules (AIM) theory.     

Finding the minimum vertex distance between two disjoint convex polygons in linear time

Let V = v₁, v₂, …, v_m and W = w₁, w₂, …, w_n be two linearly separable convex polygons whose vertices are specified by their cartesian coordinates in order. An algorithm with O(m + n) worst-case time complexity is described for finding the minimum euclidean distance between a vertex v₁ in V and a vertex w_j in W. It is also shown that the algorithm is optimal.     

最短有限整定时间的一种算法

用状态空间数学模型描述的多变量离散系统中，对输入向量无约束条件，任意的初始状态X（0）在最短调整时间内回到原点的问题，对于分析和设计离散系统，起着很重要的作用。本文将给出准确计算最短整定时间的一种方法。     

A weakly universal cellular automaton on the pentagrid with two states

In this paper, we prove that there is a weakly universal cellular automaton on the pentagrid with two states. This paper improves in some sense a previous result with three states. Both results make use of a la Moore neighbourhood. However, the result with three states is rotation invariant while the result of the present paper is not. In both cases, at each step of the computation, the set of non quiescent states has always infinitely many cycles.