Computerized tolerance analysis of disk cam mechanisms with a roller follower

The tolerance analysis is one of the key elements of design and manufacturing of cam mechanisms. This paper presents a computerized method for analyzing the tolerances in disk cam mechanisms with a roller follower. By employing the concept of simulated higher-pair contact analysis, the kinematic deviation of the follower motion arising from the tolerance amount of each design parameter can be determined numerically. The offset translating roller follower and the oscillating roller follower cases are given to illustrate the proposed method. The tolerance analysis results show that, owing to the combined effects of various design parameters, the position accuracy of the follower motion may degrade considerably. But, the tolerance amounts of the design parameters may also have a compensating effect to enhance the relative accuracy of the follower motion between its high and low dwell positions. Hence, it is possible to find the optimal tolerance combination for balancing the kinematic accuracy and the tolerance amounts of disk cam mechanisms with a roller follower.     

An analysis of algorithm-based fault tolerance techniques

We introduce a unified checksum scheme for the LU decomposition, Gaussian elimination with pairwise pivoting, and the QR decomposition. The purpose is to detect and locate a transient error during a systolic array computation. We show how to represent the error as a rank-one perturbation to the original data, so that we need not worry when the error occurred. Finally, we perform a floating point error analysis to determine the effects of rounding errors on the checksum scheme.     

Performance evaluation of fault tolerance techniques in grid computing system

As fault tolerance is the ability of a system to perform its function correctly even in the presence of faults. Therefore, different fault tolerance techniques (FTTs) are critical for improving the efficient utilization of expensive resources in high performance grid computing systems, and an important component of grid workflow management system.This paper presents a performance evaluation of most commonly used FTTs in grid computing system. In this study, we considered different system centric parameters, such as throughput, turnaround time, waiting time and network delay for the evaluation of these FTTs. For comprehensive evaluation we setup various conditions in which we vary the average percentage of faults in a system, along with different workloads in order to find out the behavior of FTTs under these conditions. The empirical evaluation shows that the workflow level alternative task techniques have performance priority on task level checkpointing techniques. This comparative study will help to grid computing researchers in order to understand the behavior and performance of different FTTs in detail.     

Analyzing the techniques that improve fault tolerance of aggregation trees in sensor networks

Sensor networks are finding significant applications in large scale distributed systems. One of the basic operations in sensor networks is in-network aggregation. Among the various approaches to in-network aggregation, such as gossip and tree, including the hash-based techniques, the tree-based approaches have better performance and energy-saving characteristics. However, sensor networks are highly prone to failures. Numerous techniques suggested in the literature to counteract the effect of failures have not been carefully analyzed. In this paper, we focus on the performance of these tree-based aggregation techniques in the presence of failures. First, we identify a fault model that captures the important failure traits of the system. Then, we analyze the correctness of simple tree aggregation with our fault model. We then use the same fault model to analyze the techniques that utilize redundant trees to improve the variance. The impact of techniques for maintaining the correctness under faults, such as rebuilding or locally fixing the tree, is then studied under the same fault model. We also do the cost-benefit analysis of using the hash-based schemes which are based on FM sketches. We conclude that these fault tolerance techniques for tree aggregation do not necessarily result in substantial improvement in fault tolerance.     

Computerized clinical simulations

The technique involved in designing a clinical simulation problem for the allied health field of Respiratory Therapy is described. The structure, content and scoring categories are discussed. A sample program is provided illustrating a programming technique in BASIC (Beginners' All Purpose Symbolic Instruction Code) which includes a sample flowchart.     

Computerized video work measurement

In recent years developments in the area of Work Measurement focusing on the Motion-Time study have effectively attempted to design around the human problem through predetermined methods and standard times for generalized word elements. Basic time study equipment has not changed in concept since the days of F. W. Taylor and the Gilbreths in the sense that a stop watch and clip board are still the tools of the Time Study engineer.Several years ago, the course in Work Measurement taught at the University of Notre Dame began the use of video tape recordings in the laboratory providing feedback to the students on their mistakes made in the Work Measurement labs. From this use of the VTR for basic filmed recording of activities the system has progressed to the point where the computer can be used as the basis for studying the video tape for motion analysis and the motion time study in both an elemental type study as well as a work sampling study. Random access and digital read-out equipment oriented around the video taped work activity of an individual or a group provides a sophisticated means to detail time study or Work Sampling analyses.A digital control unit has been designed and constructed to interface between a remote computer and a local keyboard terminal connected to the video tape recorder and its video timing generator. The industrial engineer can enter at the keyboard his evaluations of the activities reviewed on the VTR. Timing information is automatically extracted from the video image and transmitted to the computer together with the keyboard data for subsequent data processing and report generation.An experimental system as presently in use by several companies on a beginning basis and the laboratory advances made are discussed in this paper.     

Computerized facility layout design

The paper describes a computerized facility layout designer, COMLAD II, for plant layout development. Besides developing an efficient layout, COMLAD II has useful features which allow fixing the departments, changing the shape of the departments and changing the length and width dimensions of the overall layout.     

Computerized draughting in education

Companies selling computerized draughting systems report a dramatic increase in sales and serious enquiries this year. Such systems are now economically viable and may well become standard equipment in large and medium drawing offices. In education it is almost impossible to justify the high capital cost of such equipment. The paper describes a draughting package, mounted on a desk-top computer, which has many of the features of a commercial ‘turn-key’ system. University students are well motivated by the opportunity to use the system as part of a course in Engineering Drawing and a gradual extension of its use is planned.     

智能电脑刺绣集成环境ICEE

运用图像处理技术、超媒体技术和专家系统、基于实例推理等人工智能技术,设计并实现了智能电脑刺绣集成环境ＩＣＥＥ,它将刺绣编程、图案装配和刺绣知识咨询等系统集成在一起,实现了图案设计、输入、编程、优化和数据转换的一体和自动化能产生高质量的绣品数据样板,提高电脑刺绣的效率。     

伺服控制系统的计算机实现

以工业控制计算机作为人机界面及数据处理的主要手段,构建了伺服控制系统的核心部分,采用了计算机技术对控制器进行数字化处理,提高了系统的控制精度,简化了参数的调整过程。改善人机环境,达到操作的方便。     

Computerized correction of phonographic errors

When computers are confronted with text (C.A.I., lexicography, machine translation, information retrieval, office automation, etc.) spelling-error bottlenecks greatly decrease the efficiency of systems. In this paper, we demonstrate how spelling errors can be efficiently handled from an algorithmic, computer science point of view. We first show that the various types of spelling errors must receive different treatments, and we especially focus on phonographic errors, on which relatively little work has been done. We provide some quantitative data on the phonographic structure of language and develop a mathematical framework for modeling the various types of errors, including phonographic ones. Finally, we outline an application to fast retrieval of misspelt words in dictionaries, which can be implemented in natural-language interfaces to make computers interact more gracefully with non-specialists.Jean Veronis is a researcher in the Groupe Représentation et Traitement des Connaissances at the Centre National de la Recherche Scientifique in Marseille.     

微机控制微电极伏安仪

本文将 APPLE-Ⅱ计算机与电化学系统联机,研制了微机控制的微电极伏安仪。该仪器除能做稳态实验外,还可以进行结果计算和处理。其电势扫描速度达到几十伏/秒,能用于较快速电势扫描的研究。自动化程度大大提高。