Reduced Models for Efficient CCS Verification

Verification of a concurrent system can be accomplished by model checking the properties on a structure representing the system; this structure is, in general, a transition system which contains a prohibitive number of states. In this paper, we apply a method to reduce the state explosion problem by pointing out the events of the system to be ignored on the basis of the property to be verified. We evaluate the method by means of a real application used as a case study: the system is specified by a CCS program, then the program is reduced by means of syntactic rules; afterwards, the corresponding transition system is built by means of a non-standard operational semantics, which performs further reductions during the construction. Prototype tools perform both kinds of reductions; finally the required properties are checked by means of the model checkers of the CWB-NC.     

Nonoverlapped view management for augmented reality by tabletop projection

Augmented reality (AR) by a projector allows for the easy association of information by labeling the objects. When a projector is installed above a workspace and pointed downward, supportive information can be presented; however, the label will be deformed if the object is nonplanar. Also, a label might be projected in a region where it is hidden by the object, i.e., a blind area. In this paper, we propose a view management technique to allow interpretation by improving the legibility of the information. We propose the nonoverlapped gradient descent (NGD) method, which determines the position of a newly added label by avoiding overlap with the surrounding labels and linkage lines. The issues of presenting in a shadow or blind area are also addressed by estimating these areas based on the approximation of objects as a simple solid. The results of an experiment show that the visibility of the labels was improved by using this method.     

Parallel algorithm for calculation of the exact partition function of a lattice polymer

We develop a parallel algorithm that calculates the exact partition function of a lattice polymer, by enumerating the number of conformations for each energy level. An efficient parallelization of the calculation is achieved by classifying the conformations according to the shape of the box spanned by a conformation, and enumerating only those in a given box at a time. The calculation time for each box is reduced by preventing the conformations related by symmetries from being generated more than once. The algorithm is applied to study the collapse transition of a lattice homopolymer on a square lattice, by calculating the specific heat for chain lengths up to 36.     

Dragging motion of a two-link mobile manipulator with large pull force through singular configuration: theoretical analysis and experimental verification

This paper reveals the advantageous feature of singular configuration for a two-link mobile manipulator by theoretical analysis, numerical simulations and experiments. When a mobile manipulator drags a heavy object on a flat floor, a large pull force is required to overcome the friction force between the object and the floor. In the motion obtained by numerical optimization, unlike humans, a two-link mobile manipulator pulls the object with a large force by passing through singular configuration. We analyze theoretically the force applied to the object by the manipulator under several assumptions, and show that a large pull force can be generated near singular configuration from the energy stored in the manipulator. The feasibility of the motion obtained by numerical optimization is also shown by experimental results.     

Distributed self-healing control in SONET

This paper proposes a distributed self-healing architecture which contains two self-healing techniques. In this proposal, a path restoration by Self-Healing Ring (SHR) and a path restoration by Dynamic Self-Healing (DSH) algorithm are jointly applied in a network. In the architecture, SHR is applied for a part of a path which is terminated by an Add-Drop Multiplexer (ADM), and DSH is applied for another part of a path which is terminated by two Digital Cross-Connect Systems (DCSs). Based on the architecture, DSH can be applied for a part of a path which is terminated by an ADM. Next, a network design algorithm is described in order to optimize the amount of spare capacity. As a result, spare capacity reduction is realized by using the algorithm for a network where the proposed architecture is applied.     

On the coordinator's rule for Fast Paxos

Fast Paxos is an algorithm for consensus that works by a succession of rounds, where each round tries to decide a value v that is consistent with all past rounds. Rounds are started by a coordinator process and consistency is guaranteed by the rule used by this process for the selection of v and by the properties of process sets called quorums. We show a simplified version of this rule for the specific case where the quorums are defined by the cardinality of these process sets. This rule is of special interest for implementors of the algorithm.     

Approximation by fat arcs and fat biarcs

A general discussion of the including approximation of a curve by a fat arc is given followed by an algorithm for constructing an including fat arc for a parametric Bézier curve. An example of applying the algorithm is given. The results for a fat arc are then used to develop an including approximation for a curve segment using a fat biarc. An algorithm for a fat biarc including approximation is provided followed by examples of Bézier curves being included by a fat biarc.     

A depth-coherence scanline algorithm for displaying curved surfaces

A scanline algorithm is presented which generates a realistic picture of a solid object bounded by curved surfaces. Externally, a surface is described by parametric equations. The internal representation is comprised of meshes of cubic splines which may be subdivided. Memory is saved by delaying subdivision, and by using a novel garbage collection technique. Time is saved by exploiting depth coherence. A viewpoint and scanline fix a cross-section represented as a set of curves. There are usually only a few of these to compare, and the curve nearest the viewer often remains nearest over much of its length.     

A hierarchical mixture model for clustering three-way data sets

Three-way data sets occur when various attributes are measured for a set of observational units in different situations. Examples are genotype by environment by attribute data obtained in a plant experiment, individual by time point by response data in a longitudinal study, and individual by brand by attribute data in a market research survey. Clustering observational units (genotypes/individuals) by means of a special type of the normal mixture model has been proposed. An implicit assumption of this approach is, however, that observational units are in the same cluster in all situations. An extension is presented that makes it possible to relax this assumption and that because of this may yield much simpler clustering solutions. The proposed extension—which includes the earlier model as a special case—is obtained by adapting the multilevel latent class model for categorical responses to the three-way situation, as well as to the situation in which responses include continuous variables. An efficient EM algorithm for parameter estimation by maximum likelihood is described and two empirical examples are provided.     

自动对焦显微镜系统设计及仿真

设计了一种基于条纹投影的自动对焦显微镜系统。通过红外光源将光栅掩膜板投射到被测物表面,用于对焦判断。通过白光光源进行系统照明。使用带通滤光片分离出由红外光源投射的光栅像,并由线阵CCD采集,用于离焦量和离焦方向的判断。由白光光源照射得到被测物的像,并由面阵CCD接受用于直接观测。使用Tracepro对设计的系统进行仿真,分析得到适用于线阵CCD采集的光栅图的一维清晰度评价函数,并使用系统对不同被测物进行仿真对焦实验与误差分析。仿真结果表明,本系统可对不同被测物进行自动对焦。     

Towards a Possibilistic Logic Handling of Preferences

The classical way of encoding preferences in decision theory is by means of utility or value functions. However agents are not always able to deliver such a function directly. In this paper, we relate three different ways of specifying preferences, namely by means of a set of particular types of constraints on the utility function, by means of an ordered set of prioritized goals expressed by logical propositions, and by means of an ordered set of subsets of possible choices reaching the same level of satisfaction. These different expression modes can be handled in a weighted logical setting, here the one of possibilistic logic. The aggregation of preferences pertaining to different criteria can then be handled by fusing sets of prioritized goals. Apart from a better expressivity, the benefits of a logical representation of preferences are to put them in a suitable format for reasoning purposes, or for modifying them.     

Enhanced locomotive and drilling microrobot using precessional and gradient magnetic field

We propose a new electromagnetic actuation (EMA) system for an intravascular microrobot with steering, locomotion and drilling functions. The EMA system consists of 3 pairs of Helmholtz coil and 1 pair of Maxwell coil. Generally, Helmholtz coils can align a microrobot in a desired direction by generating a uniform magnetic flux. If the uniform magnetic field generated by Helmholtz coils can be rotated, a microrobot with Helmholtz coils can also be rotated. On the other hand, a Maxwell coil, which generates a constant gradient magnetic flux, can supply the propulsion force for the microrobot. A microrobot actuated by the proposed EMA system has a spiral shaped body containing two magnets with different magnetization directions. With the proposed EMA system, the microrobot can move to the target region and perform drilling there by the precessional magnetic field of the Helmholtz coil pairs. The propulsion force for the microrobot is produced by the gradient magnetic field generated by the Maxwell coil pair. The moving velocity and the drilling performance of the microrobot can be increased by the propulsion force of the Maxwell coil pair. Through various tests, the feasibility and enhancement of the microrobot actuated by the proposed EMA system were verified.     

Solving the resolution-free SAT problem by submodel propagation in linear time

We present a method, called Unicorn-SAT, based on submodel propagation, which solves the resolution-free SAT problem in linear time. A formula is resolution-free if there are no two clauses which differ only in one variable, i.e., each clause is blocked for each literal in it. A resolution-free formula is satisfiable or it contains the empty clause. For such a restricted formula we can find a model in linear time by submodel propagation. Submodel propagation is hyper-unit propagation by a submodel generated from a minimal clause. Hyper-unit propagation is unit propagation simultaneously by literals, as unit clauses, of a partial assignment. We obtain a submodel, i.e., a part of the model, by negation of a neighbor-resolution-mate of a minimal clause, which is a clause with the smallest number of literals in the formula. We obtain a neighbor-resolution-mate of a clause by negating one literal in it. By submodel propagation we obtain a formula which has fewer variables and clauses and remains resolution-free. Therefore, we can obtain a model by joining the submodels while we perform submodel propagation recursively until the formula becomes empty.     

超空泡航行器稳定性分析及其非线性切换控制

超空泡航行器在航行过程中绝大部分被超空泡包裹,必然面临着航行器与空泡剧烈非线性作用力带来的稳定控制困难.针对超空泡航行器的控制问题,本文以Dzielski提出的航行器模型为研究对象.首先通过一系列系统变换使其成为线性系统环节和非线性环节反馈连接的形式,运用圆判据定理利用系统Nyquist曲线给出了系统绝对稳定的充分条件;而后结合工程实际,分析了极点约束对系统性能的影响,为进一步改善系统性能,提出了加入非线性激励来削弱系统固有非线性特性的切换控制策略.仿真结果表明,超空化航行器在极点约束情况下完全可以通过非线性切换控制达到系统对所有非线性特性的绝对稳定,且对于滑行力存在不确定性的情况切换控制依然有效.     

Process specification generation from communications service specifications

This paper proposes an algorithm for generating process specifications from communications service specifications described by a graph grammar. In this work, it is assumed that a communications system consists of homogeneous processes and that there is no global database. Processes that share a relationship form a global state, and a communications service defines global state transitions caused by inputs to the processes. A global state is represented by a labeled directed graph and a global state transition is described by a graph replacement rule. A process specification is regarded as a distributed algorithm whose purpose is to achieve the global state transitions described by the graph replacement rules. The communication time complexity of the generated distributed algorithm does not depend on the number of graph replacement rules.     

一道数字排列题算法演示的C#实现

编程解决实际问题,不仅通过大量的编程实践,掌握一定的编程技巧,同时也需要找到解决问题的正确方案。通过一道数字排列题的解决演示,灵活运用C#语言编程实现该问题算法的可视化演示。     

规则向量投影算法──一种归纳机器学习方法

为了支持在事实不完全或不充分环境中的有效推理，作者提出了一种归纳机器学习方法，并设计了一个规则向量投影算法，使用木文介绍的算法可对原始知识实行归纳，生成含一系列全新分类概念和推理路经的网络知识库，基于该知识库的机器推理系统，在作出诊断决策时所需事实量可大为减少，因此在信息量不足的情况下仍能具有很高的推理性能．     

Finite-Volume-Particle Methods for Models of Transport of Pollutant in Shallow Water

We present a new hybrid numerical method for computing the transport of a passive pollutant by a flow. The flow is modeled by the Saint-Venant system of shallow water equations and the pollutant propagation is described by a transport equation. The idea behind the new finite-volume-particle (FVP) method is to use different schemes for the flow and the pollution computations: the shallow water equations are numerically integrated using a finite-volume scheme, while the transport equation is solved by a particle method. This way the specific advantages of each scheme are utilized at the right place. This results in a significantly enhanced resolution of the computed solution     

Image reconstruction from in-line Fresnel holograms by using coherent background elimination

Image reconstruction from in-line Fresnel holograms by eliminating a coherent background is studied by computer simulation. The coherent background is calculated by averaging an intensity of a recorded hologram. The quality of the reconstructed image is measured by using a ratio of peak signal to noise. In comparison with the conventional reconstruction method, the results show that the background elimination can improve significantly the quality of the reconstructed images. The text was submitted by the authors in English.