Numerical algorithms for two-dimensional dynamic frictional problems

Conventional integration schemes for the equations of motion encounter numerical problems near transitions between stick and slip in two-dimensional frictional contact problems. Here we explore the dynamical behaviour close to these transitions and develop analytical patches that can be used to develop a state-variable algorithm, where the system toggles between states of stick and slip.     

视图增量计算的延迟部分补偿算法

为解决异步传播算法中视图增量计算时间过长、占用系统资源过多及某些错误补偿问题,提出了在数据源上进行延迟部分补偿的算法.该算法要求获取数据源的基表增量时记下增量的事务时间,在实化视图层记录已用于视图增量计算的基表增量的最大事务提交时间.当计算实化视图新的增量时,比较同一个数据源在实化视图层上的记录时间与增量子查询的执行时间,如果这段时间基表产生新的增量,则进行补偿查询.补偿过程采用单个数据源上的时间进行比较,避免了全局时间问题,也解决了现有部分补偿算法可能产生的错误.该算法利用基表之间的主外码约束来减少计算次数,提高计算效率.分析和实验表明,该算法在计算效率和正确性方面都有所提高.     

Rope loading in frictional systems

The subject of this paper is the analysis of the maximum loading of ties in multiband frictional systems. Systems like these occur in different branches of mechanical engineering; they are commonly used for passengers elevators. Although the rope system of the elevator contains rockers, in order to equalize the loading of the separate bands, remarkable differences in loading do occur.

Conditions of static equilibrium of the rope system, having the form of inequalities, have been found. Programming methods have been applied, to find the maximum loading of ropes which can occur in different multiband systems. Results of the analysis have been compared with the results of experiments.     

Two-dimensionally quantized friction observed with two-dimensional frictional force microscope

Using a two-dimensional frictional force microscope, we studied the two-dimensional nature of the atomic scale friction between a Si₃N₄ sharp tip and a cleaved graphite surface, which is composed of only C atoms and is a good conductor. As a result, we observed the two-dimensionally quantized friction with the lattice periodicity of the graphite surface, similarly to mica, MoS₂ and NaF surfaces. Thus quantized friction occurs at material surfaces which are composed of not only some elements but also of a single element, and the quantized friction does not depend on the conductivity of the surface.     

Active damping of frictional self-vibrations in systems with a cubic characteristic of the frictional force

Analytical solutions are obtained for the laws of damping of self-vibrations that ensure the stability and uniqueness of self-vibration regimes with minimal intensity.     

基于晶体增长分类算法的个性化在线服务

为给用户提供精确的个性化信息服务,提出了一种晶体增长分类算法,以此对网络上的信息资源进行分类。晶体增长分类算法利用反复提取原型向量的方式来聚合信息。其中,原型向量的提取根据输入的搜索关键词及其上下文关系,通过径向基函数神经网络完成。原型向量反复提取过程反映了一种树型关系,而每个阶段的结果形成树型目录的一个节点。信息分类结束后,形成一个树型目录。在此目录的基础上,结合在线服务技术和用户需求,以向导的方式对信息进行二次匹配,从而保证个性化信息服务的精确度。另外,所提算法也具有合理的计算复杂度,且实验结果验证了算法的有效性和可行性。     

Low-distortion resistive anodes for two-dimensional position-sensitive MCP systems

Microchannel plates (MCPs) are frequently employed with resistive anodes to detect charged particles or photons and yield analog signals from which event positions can be decoded. We discuss an anode geometry devised by C.W. Gear that offers theoretically distortionless encoding of Cartesian event positions into pulse charge ratios. Electron beam images taken with such an anode are shown, and confirm the usefulness of the approach.     

二维一刀切装箱问题的两阶段启发式算法

对用于二维带排样问题的Heuristic Recursive算法进行了调整,给出同一层中两个相邻浪费区域在满足一刀切约束下是否可合并的判定定理。构造了二维带排样问题的多递归层算法,并将它与一维装箱问题的最优匹配递减算法相结合,提出适应二维一刀切非旋转装箱问题的两阶段算法。在500组标准测试案例的基础上,与多种算法进行了比较。实验结果表明,所提算法在绝大多数测试案例上能够获得更好的排样布局。     

Training and assignment of multi-skilled workers for implementing seru production systems

Confronted with high variety and low volume market demands, many companies, especially the Japanese electronics manufacturing companies, have reconfigured their conveyor assembly lines and adopted seru production systems. Seru production system is a new type of work-cell-based manufacturing system. A lot of successful practices and experience show that seru production system can gain considerable flexibility of job shop and high efficiency of conveyor assembly line. In implementing seru production, the multi-skilled worker is the most important precondition, and some issues about multi-skilled workers are central and foremost. In this paper, we investigate the training and assignment problem of workers when a conveyor assembly line is entirely reconfigured into several serus. We formulate a mathematical model with double objectives which aim to minimize the total training cost and to balance the total processing times among multi-skilled workers in each seru. To obtain the satisfied task-to-worker training plan and worker-to-seru assignment plan, a three-stage heuristic algorithm with nine steps is developed to solve this mathematical model. Then, several computational cases are taken and computed by MATLAB programming. The computation and analysis results validate the performances of the proposed mathematical model and heuristic algorithm.     

Novel streak-resolving algorithm for particle streak velocimetry

In this paper, a novel streak-resolving algorithm is proposed for particle streak velocimetry (PSV) to resolve velocity fields for a single image frame with multiple particle streaks. A model streak function, which was based on the temporal integral of the particle image intensity moving along its trajectory during the exposure period, was approximated using a multivariable least-square fit procedure to reconstruct the streak information and the corresponding particle trajectory. Lagrangian tracking was achieved, and the velocities were evaluated by differentiating the resolved particle trajectory with respect to time. Two types of flows, accelerating parallel flow and the rotational flow of Hill’s vortex, were used to generate synthetic streaks for the performance tests. Three types of relative error were defined and used to evaluate the performance of the algorithm in terms of statistical mean and standard deviation (SD) errors. The accuracy of the fitted streak parameters, such as particle image intensity and diameter, were also evaluated and compared. The results reveal that the error and SD were low if the image noise is below 1.0%; for noise levels of 5.0%, the error was up to 10% with an SD of up to 12%. The error and SD of the particle image intensity and particle image diameter for both flow types were also 0%–7% for clean and up to 12% for noisy images. The processing results for experimental streak images of flow past a cylinder reveal that these images can be resolved using the proposed algorithm with a residual mean error of 4.38 and an SD of 9.48. These results suggest that the proposed novel approach can be used to resolve velocity fields with only a single image frame and without expensive hardware for high-speed imaging and thus is suitable for diverse applications.     

An exact algorithm for self-calibration of two-dimensional precision metrology stages

We describe an algorithm that can achieve exact self-calibration for high-precision two-dimensional (2-D) metrology stages. Previous attempts to solve this problem have often given nonexact or impractical solutions. Self-calibration is the procedure of calibrating a metrology stage by an artifact plate whose mark positions are not precisely known. By assuming rigidness of the artifact plate, this algorithm extracts the stage error map from comparison of three different measurement views of the plate. The algorithm employs the orthogonal Fourier series to expand the stage error map, which allows fast numerical computation. When there is no random measurement noise, this algorithm exactly calibrates the stage error at those sites sampled by the mark array. In the presence of random measurement noise, the algorithm introduces a calibration error of about the same size as the random measurement noise itself, which is the limit to be achieved by any self-calibration algorithm. The algorithm has been verified by computer simulation with and without random measurement noise. Other possible applications of this algorithm are also discussed.     

Hybrid of ANN with genetic algorithm for optimization of frictional vibration joining process of plastics

Complex shapes of plastics can be realized by joining techniques. Newer method of joining of plastics is necessitated by the industries due to the requirement such as reduced processing time and improved strength. Frictional vibration joining of plastics is a newer method where the heat generated by the third body at the interface of joining members is utilized for joining. The present study attempts to use the Taguchi method for frictional vibration joining of plastic plates. The effectiveness of the Taguchi method lies in clarifying the factor that dominates complex interactions in frictional vibration welding. The factors are (1) frequency of tool vibrating across the work piece, (2) feed of the work piece against the tool, and (3) clamping force at the joint interface. This study describes a new method of selection of process parameters for obtaining optimal weld tensile strength. Genetic algorithm was used to optimize the parameters for the process. Artificial neural network (ANN) was used to establish the relationship between the input/output parameters of the process. The established ANN is then suitably integrated with the optimization technique. This hybrid technique of ANN and genetic algorithm is effectively used to obtain optimal joint strength.     

A two-dimensional polarization interferometry based parallel scan angular surface plasmon resonance biosensor

We describe a two-dimensional polarization interferometry based parallel scan angular surface plasmon resonance (SPR) biosensing technique. The method of line-shaped light illumination and parallel scan offers a high throughput. The simultaneous record of SPR angular spectrum enables the system to be unaffected by the time-dependent variation of the light source. The polarization interferometry technique lowers the minimum of the SPR dip and thereby reduces the noise related to the light intensity. Refractive index resolutions of 1.4 × 10(-6) refractive index unit (RIU) under normal condition and 4.6 × 10(-7) RIU under a more time-consuming condition are achieved in our angle interrogation based sensor. Meanwhile, a manually prepared DNA microarray has been detected, showing the potential applications of this technique in microarray analysis.     

适用于矩形图像的新二维映射图像加密算法

针对目前的图像加密方法大多只局限于对方形图像进行加密的特点,提出了一种同时适用于方形图像和矩形图像的加密算法.将基于图像分割的新二维映射用于图像位置置乱,将含有混沌映射的扩散函数用于图像灰度置乱,从而得到一种位置置乱和灰度置乱相结合的图像加密算法.实验仿真结果表明,该算法能够很好地实现对任意大小的方形和矩形图像进行加密,且具有密钥空间大(1015～1030),密钥敏感性强以及能够抵御统计和已知明文攻击等优点,基本满足图像加密的有效性和安全性要求.     

A new heuristic algorithm for a class of two-dimensional bin-packing problems

Due to the diversification of customer’ demands, cutting and packing enterprises need to arrange production plans flexibly. This paper proposes a heuristic algorithm to help enterprises make cutting or packing plans. With this algorithm, a class of different customer demands are considered, such as orientation of items and cutting style. The idea of this heuristic algorithm is from the dynamic programming idea by aggregating states to avoid the explosion of the number of states. The advantages of this algorithm are its flexibility, competitive computation time, and performance with respect to metaheuristics.     

On the aspect of implementing solutions for information support of industrial plant control systems

The authors of this paper look at the aspect of engineering information systems for planning and scheduling operations of an industrial plant. The authors propose to introduce new steps to the engineering process which include functional modelling, elaboration of an initial request for proposal (or RFP) for a functional model, development of functional models and algorithms, and elaboration of a software specification. The engineering step-by-step process is presented as an entity set model. The authors introduce a system functionality design formula which includes business rules, business logic, project roles, and visualization. An example of a machining shop with repeated machining operations is used to demonstrate the effect of introduction of new design stages. The simulation software AnyLogic was chosen as a visualization tool to demonstrate all the functionalities of the new system. AnyLogic enabled to implement all the roles of the information system. Elaboration of the functional model took place along with development of an RFP for implementation of an information system as part of an automation package of an industrial plant. As a result of the functional model demonstration, certain drawbacks were identified in the project, and recommendations were provided on how to eliminate them.     

一种基于时空信息的多目标检测新算法

运动目标检测是计算机视觉中进行信息提取的关键技术之一.为了克服传统帧间差分法检测出的目标不完整的缺点,提出了一种基于时空信息的视频图像中多目标检测新算法.该算法将帧间差分得到的图像序列的时间信息和帧间边缘差分得到的图像空间信息结合起来检测图像中的运动目标,同时利用形态学闭运算和近区域合并方法进一步强化图像中的空间信息,利用小区域去除的方法去除图像中的噪声影响.最后通过3组实验对其有效性进行了验证,实验结果证明,其检测效果与传统算法相比有较大改善.     

Open optimization in two-dimensional lathe control systems

Optimization of turning in a numerically controlled lathe with open control of the cutting speed and closed control of the supply improves the operational efficiency in constantly changing conditions. An algorithm is proposed for determining the most economical cutting speed.     

柔性制造系统中生产调度问题求解的一种符号算法

讨论了基于有序二叉决策图的有界Petri网符号分析,给出了其中镜像计算的一种新算法,进而建立了柔性制造系统生产调度问题的符号有序二叉决策图求解算法.该算法在求解过程中通过对状态空间及其搜索过程中相关数据的有序二叉决策图表示,避免了状态和搜索的显示枚举,实现了隐式高效操作,进而改善了算法的计算性能.仿真实验表明了算法的有效性.