Modal disparity enhancement through optimal insertion of nonstructural masses

Stiffness variation can be generated in a structure by the systematic application and removal of tension in cables connecting points in the structure. This strategy has been shown to result in modal disparity, a property of the combined structure and cable system that allows vibration energy to flow from one set of modes to another. This facilitates the design of simplified strategies for modal control of flexible structures using only a few selected modes. For some structures, however, cable tension switching may not result in sufficient modal disparity, and, in such cases, the rate of energy transfer across modes may not be sufficient to ensure rapid vibration suppression. Here, it is shown that such difficulty can be alleviated by the insertion of a few nonstructural masses. A procedure is outlined for determining the optimal location of these masses. Simulation results are presented to illustrate vibration control in a 3-D frame.     

分割式Montgomery模乘运算的线性高基心动阵列新结构

本文基于提高并行性、加速模乘的思想,利用分割操作数的方法,提出了分割式Montgomery模乘算法（PMMM）,并且基于C．D.Walter发明的心动阵列结构,提出了新的线性高基心动阵列模乘结构,较好地实现了PMMM。对于基r（r=2^w）的n位模乘运算,Walter使用（n＋1）（n＋2）个PF来实现Montgomery模乘,我们用n＋2个PE实现Montgomery模乘,最大并行性为Walter的2倍。将此结构应用于模幂运算,仅需一次预计算便可使得非平方模乘的输入输出延迟为walter中的1/2,且平方模乘延迟与其相当,从而提高了模幂的运算速度。当然,考虑到对速度和硬件资源的不同需求,我们也给出了使用n/2＋1个PE来计算模乘、模幂的实现算法,并做出了相应的数据分析。     

Elliptic curve based hardware architecture using cellular automata

This study presents an efficient division architecture using restricted irreducible polynomial on elliptic curve cryptosystem (ECC), based on cellular automata. The most expensive arithmetic operation in ECC is division, which is performed by multiplying the inverse of a multiplicand. The proposed architecture is highly regular, expandable, and has reduced latency and hardware complexity. The proposed architecture can be efficiently used in the hardware design of crypto-coprocessors.     

Adaptive compensation for infinite number of actuator failures or faults

It is both theoretically and practically important to investigate the problem of accommodating infinite number of actuator failures or faults in controlling uncertain systems. However, there is still no result available in developing adaptive controllers to address this problem. In this paper, a new adaptive failure/fault compensation control scheme is proposed for parametric strict feedback nonlinear systems. The techniques of nonlinear damping and parameter projection are employed in the design of controllers and parameter estimators, respectively. It is proved that the boundedness of all closed-loop signals can still be ensured in the case with infinite number of failures or faults, provided that the time interval between two successive changes of failure/fault pattern is bounded below by an arbitrary positive number. The performance of the tracking error in the mean square sense with respect to the frequency of failure/fault pattern changes is also established. Moreover, asymptotic tracking can be achieved when the total number of failures and faults is finite.     

挠性航天器鲁棒后步滑模姿态跟踪及主动振动控制

针对挠性航天器姿态跟踪及振动抑制问题,提出一种双回路鲁棒控制方法.首先,采用滑模控制与后步法设,计了姿态跟踪控制器,基于Lyapunov方法分析系统的渐近稳定性,并从实际应用角度考虑了反作用飞轮的动态特性;其次,为抑制挠性结构的振动,采用压电智能材料作为敏感器和作动器,设计了应变速率反馈补偿器.仿真结果表明,所提方法在保证完成姿态跟踪任务的同时,能有效抑制挠性附件的振动.     

无线传感网络的非分簇拓扑控制方法研究

无线传感网络通常由能量受限、通信半径较小的传感器节点构成,其中拓扑控制是重要的工程问题。提出了一种基于元胞自动机的非分簇的拓扑控制算法,与传统分簇方法的区别在于本方法试图通过牺牲小部分拓扑连通度和覆盖度来换取更长的系统生存时间。基于元胞自动机模型的研究表明,节点的状态转移规则对系统整体性能起决定作用,在一些规则下系统拓扑呈现稳定变化,符合对无线传感网络拓扑控制的要求。进一步探讨了该机制在工程上的具体实现问题,并与LEACH算法进行了对比,验证了以拓扑性能换取生存时间的设想。     

Recent trends in flexible automated manufacturing

In recent years, an important change in developing and implementing manufacturing systems can be observed in all industrialized countries. Due to intense international competition and the growth of personnel costs, companies are forced to use systems with a higher level of automation. At the same time, an increasing number of product variation—caused by adapting the products to customer requirements—demand more flexibility of machine tools and manufacturing systems.Basic types of computer-controlled flexible automated manufacturing systems will be shown and characterized by their special ranges of application. A planning procedure is presented which includes selecting a suitable systems structure such as; transfer line or flexible manufacturing system or automated manufacturing cell, and for determinating every single machine tool within the system. Examples of several new computer-controlled manufacturing systems which have been planned by the above planning procedure are presented with special regard to the evaluation of the system's economic performance.Finally, some rules are given for measuring the economic performance of automated manufacturing or assembly systems including automation of the handling functions.     

Characterization of real time iterative array by alternating device

In this paper, we show that real time k-dimensional iterative arrays are equivalent through reverse to real time one-way alternating k-counter automata.     

A machine level based-similarity coefficient for forming manufacturing cells

In cellular manufacturing literature, early work heavily focused on the use of routers as a way of forming product families and manufacturing cells. later, several measures of similarity among machines and parts have been proposed by different authors. Similarity coefficients use more data in addition to the machines visited. In this paper, a new similarity coefficient is proposed which incorporates not only the type of machines but also the level (number) of machines required. The potential benefits of the proposed similarity coefficient is demonstrated with an example problem using three clustering algorithms namely, SLINK, ALINK and CLINK. The results obtained by using this new similarity coefficient are compared with those of the Jaccard's Similarity Coefficient.     

Design of cellular structures for optimum efficiency of heat dissipation

Metal cellular material is a new material attractive for its light weight and potential multifunctionality. In the present paper, we study cylindrical structures made of linear metal cellular material. The outer surface of the cylindrical structure is subjected to thermal boundary condition, and cooling fluid is forced through the cylinder to remove heat through the inner cell walls. Optimum design aims at maximization of heat dissipation efficiency under prescribed flow pressure. Two classes of design variables, relative density, and local aperture distribution of cellular material are to be determined by optimization under given total material volume constraints. Although similar to the structural topology optimization concept of material distribution, our formulation results in a structure with realistic cellular material of finite-sized aperture. Numerical results for different cross-sectional shapes and thermal boundary conditions are presented. Interestingly, our present formulation leads to optimum designs for cellular structures that mimic natural biomaterials. We discuss in general the guideline for cellular structure design to maximize heat dissipation efficiency based on insights from these optimization results.     

机器人柔性装配单元仿真建模的研究

机器人柔性装配单元是柔性装配系统的重要组成单元，如何协调和控制单元内的各种物流过程一直是单元设计的难点，本文通过分析ＲＦＡＣ的特点，对影响单元运行的物流过程及其相互作用的逻辑关系进行了研究，建立了ＲＦＡＣ的物流仿真模型，并对ＲＦＡＣ的物流评价方法进行了探讨。     

面向通讯同步的多处理器阵列重构

从多处理器阵列中获取所需大小并且同步通讯性能优良的子阵列,是高性能拓扑重构的核心问题之一。基于不同的逻辑列剔除策略提出了3种面向通讯同步的拓扑重构算法:基于分治思想剔除逻辑列的重构算法(SCA_01),该算法能够使被优化的逻辑列相对均匀地分布在物理阵列中;优先剔除长逻辑列的贪心重构算法(SCA_02),该算法能够使被优化的逻辑列的长链接总数最少;基于分治与长链接数的混成重构算法(SCA_03),该算法将某一区域内的最长逻辑列剔除,且尽可能将剩余逻辑列均匀分布在物理阵列中。同时,对逻辑阵列的最大通讯延时给出了下界的求解算法。实验结果表明,3种算法在故障率小于1%、逻辑列的剔除率超过20%时,算法重构出的逻辑阵列的通讯延时特别接近计算出的性能下界。在多数情况下SCA_01优于SCA_02和SCA_03,而后两者的性能相近。在小阵列上且故障率与剔除率较小时,SCA_02具有性能优势,但在大阵列上SCA_03具有优势。在32×32的阵列上,SCA_01构造的阵列产生的通讯延时较SCA_02和SCA_03产生的延时平均减少25%,并且运行速度也提升了19.4%。     

A reconfigurable computing framework for multi-scale cellular image processing

Cellular computing architectures represent an important class of computation that are characterized by simple processing elements, local interconnect and massive parallelism. These architectures are a good match for many image and video processing applications and can be substantially accelerated with Reconfigurable Computers. We present a flexible software/hardware framework for design, implementation and automatic synthesis of cellular image processing algorithms. The system provides an extremely flexible set of parallel, pipelined and time-multiplexed components which can be tailored through reconfigurable hardware for particular applications. The most novel aspects of our framework include a highly pipelined architecture for multi-scale cellular image processing as well as support for several different pattern recognition applications. In this paper, we will describe the system in detail and present our performance assessments. The system achieved speed-up of at least 100× for computationally expensive sub-problems and 10× for end-to-end applications compared to software implementations.     

改进的蒙哥马利算法及其模乘法器实现

模乘运算的速度决定了公钥加密系统和众多通信系统的系统性能。通过分析Walter等学者对蒙哥马利算法的研究成果,得到运算精简基2-MMM算法,实现基于运算精简算法的线性脉动阵列模乘法器。在验证改进算法正确性后,对模乘法器进行功能仿真和综合。用TSMC 0.18 μm标准单元库综合,可以工作在200 MHz时钟下,等效单元为42 k门,完成1 024 bit模乘法运算需     

The design of a flexible machining cell for small batch production

This paper discusses the conceptual design of a manufacturing cell for a small batch manufacturer. The cell produces small parts with dimensional tolerances of $\text{±0.005}$ inch (0.13 mm) using a minimum of machining equipment. The proposed cell can run unattended for a moderate period of time (e.g., overnight). The cell design emphasizes near-term technology and uses off-the-shelf items where possible. The design philosophy is to partition the cell components and control programs into modules according to their function. The resulting cell is easily integrated into a larger system and is readily modified or expanded as more sophisticated equipment and techniques become available.     

某摩托车发动机FMC的经济换线方案仿真分析

如何选择合理的换线方案是目前许多柔性生产单元中存在的关键问题。以某摩托车发动机零部件的柔性生产单元为研究背景,提出了一种基于系统仿真的换线问题研究方法。通过换线类型的划分和换线表的制作,辅助指派换线任务。为提高换线仿真模型的通用性,以生产系统元素、换线控制逻辑与相关数据信息分离的原则为指导,采用面向对象方法,实现了换线仿真模型的模块化。以生产周期和换线成本为评价指标,基于仿真数据确定出了不同生产任务下的最佳换线方案,并验证了该方法的可行性和有效性。     

Development of bacteria foraging optimization algorithm for cell formation in cellular manufacturing system considering cell load variations

The cellular manufacturing system (CMS) is considered as an efficient production strategy for batch type production. The CMS relies on the principle of grouping machines into machine cells and grouping machine parts into part families on the basis of pertinent similarity measures. The bacteria foraging optimization (BFO) algorithm is a modern evolutionary computation technique derived from the social foraging behavior of Escherichia coli bacteria. Ever since Kevin M. Passino invented the BFO, one of the main challenges has been the employment of the algorithm to problem areas other than those of which the algorithm was proposed. This paper investigates the first applications of this emerging novel optimization algorithm to the cell formation (CF) problem. In addition, for this purpose matrix-based bacteria foraging optimization algorithm traced constraints handling (MBATCH) is developed. In this paper, an attempt is made to solve the cell formation problem while considering cell load variations and a number of exceptional elements. The BFO algorithm is used to create machine cells and part families. The performance of the proposed algorithm is compared with a number of algorithms that are most commonly used and reported in the corresponding scientific literature such as K-means clustering, the C-link clustering and genetic algorithm using a well-known performance measure that combined cell load variations and a number of exceptional elements. The results lie in favor of better performance of the proposed algorithm.