The OPIT system I. A file-handling scheme for data in large applications programs

The OPIT program is briefly described. OPIT is a basis-set-optimising, self-consistent field, molecular orbital program for calculating properties of closed shell ground states of atoms and molecules. A file handling technique is then put forward which enables core storage to be used efficiently in large FORTRAN scientific applications programs. Hashing and list processing techniques, of the type frequently used in writing system software and computer operating systems, are here applied to the creation of data files (integral label and value lists etc.). Files consist of a chained series of blocks which may exist in core or on backing store or both. Efficient use of core store is achieved and the processes of file deletion, file re-writing and garbage collection of unused blocks can be easily arranged. The scheme is exemplified with reference to the OPIT program.A subsequent paper will describe a job scheduling scheme for large programs of this sort.     

Job shop scheduling optimization in real-time production control

An optimization algorithm using simulation as an evaluation procedure of the criterion to obtain an optimal schedule of jobs within a workshop is presented. The algorithm, which is recommended for middle-size problems, is embedded in a dedicated minicomputer-based practical system meant for real time production control in a discrete part manufacturing system environment.     

900吨大型架桥机自动控制系统的设计与应用

介绍了900吨大型架桥机自动控制系统的结构组成、控制功能、控制方式、系统软件设计以及系统操作和实际应用效果。     

新型汽车检测控制系统调度算法

为提高汽车检测控制系统车辆调度的效率和质量,对现有的基于共享文件、winsocket的调度算法进行了分析比较,提出了一种结合winsocket与网络数据库的新型车辆检测调度算法。设计了调度表,用于主控机对工位机的调度、状态监控。给出了详细的调度实现过程,工位机的检测过程信息通过winsocket传送至主控机。实际应用表明,该算法提高了系统运行的稳定性与检测数据传输的实时性和可靠性。     

Job shop scheduling heuristics for sequence dependent setups

In this paper we develop a more realistic algorithm which addresses the job shop scheduling problem with sequence dependent setup times, and some complex constraints such as multiple machines, multiple resources, and alternate routes; then, we evaluate the performance of the algorithm relative to the performance criteria used in the real world shops. To illustrate the potential impact of addressed problem, we simulate the scheduling jobs using three different approaches under a variety of conditions. Experimental designs are used to find the difference among these approaches, and to justify the value of the more realistic approach.     

Job scheduling methods for reducing waiting time variance

Minimizing Waiting Time Variance (WTV) is a job scheduling problem where we schedule a batch of n$n$ jobs, for servicing on a single resource, in such a way that the variance of their waiting times is minimized. Minimizing WTV is a well known scheduling problem, important in providing Quality of Service (QoS) in many industries. Minimizing the variance of job waiting times on computer networks can lead to stable and predictable network performance. Since the WTV minimization problem is NP-hard, we develop two heuristic job scheduling methods, called Balanced Spiral and Verified Spiral, which incorporate certain proven properties of optimal job sequences for this problem. We test and compare our methods with four other job scheduling methods on both small and large size problem instances. Performance results show that Verified Spiral gives the best performance for the scheduling methods and problems tested in this study. Balanced Spiral produces comparable results, but at less computational cost. During our investigation we discovered a consistent pattern in the plot of WTV over mean of all possible sequences for a set of jobs, which can be used to evaluate the sacrifice of mean waiting time while pursuing WTV minimization.     

Design of a computerized scheduling system for best rule analysis and control

A Computerized Scheduling System (CSS) for a gear box manufacturing plant has been developed to simulate a specific manufacturing facility and to analyse conditions that identify bottlenecks during the production process. The model, based partly on practical experience and partly on theoretical work, allows the analyst to concentrate on a single entity (such as a job) and the sequence of events and activities that undergoes as it “passes through” the system. The CSS makes use of actual company data regarding individual machines and operators, and incorporates interarrival times, job types, tasks for each job, routings for the different job types and process time for each job type and specific task. Also, the model provides information on output — average total delay in queue, average number in queue, average utilization and average delay in queue. Although the resultant model was constructed for the application on hand, the principles employed can be extended to include procedures encountered in similar manufacturing environments.     

Job scheduling in a partitionable mesh using a two-dimensionalbuddy system partitioning scheme

The job scheduling problem in a partitionable mesh-connected system in which jobs require square meshes and the system is a square mesh whose size is a power of two is discussed. A heuristic algorithm of time complexity O(n(log n+log p)), in which n is the number of jobs to be scheduled and p is the size of the system is presented. The algorithm adopts the largest-job-first scheduling policy and uses a two-dimensional buddy system as the system partitioning scheme. It is shown that, in the worst case, the algorithm produces a schedule four times longer than an optimal schedule, and, on the average, schedules generated by the algorithm are twice as long as optimal schedules     

A system of personal computer control programs for tapping experiments

A system of control and measuring programs on IBM-PC or compatible computers was developed to explore the precision and accuracy of a subject's timing mechanisms in sensorimotor behavior. Various rhythmic patterns composed of several accentuated and non-accentuated tones which the subject has to follow or to reproduce by finger tapping can be designed. All parameters of the stimulus tones, i.e., duration, pitch and inter-tone pause, in a pattern are variable. Two parallel, independent responses can be monitored simultaneously as well. In this way, the mutual influence of responses of two subjects or two responses of one subject can be analyzed. The programs are written in MODULA-2, the output data are in the ASCII format and can be processed by any common statistical package.     

Knowledge based system for scheduling and control of an automated manufacturing cell

Cell Manager (Cm) is a prototype knowledge based system for real-time control and short-term planning of an automated manufacturing facility. It uses background of mathematical programming, simulation, and heuristic search. The Cm engine allows tracking of time related events and facts in discrete or continuous time. The use of Cm is illustrated on a cell that processes discrete batches of parts. There are four workstations and the material handling system consists of automated guided vehicles.     

A sampling monitor for applications programs

Periodic location counter sampling is a well-known technique for conducting performance measurements on operating systems. It is also extremely useful for applications programs. This paper describes a set of interface conventions for such a monitor. SPY, a monitor obeying these conventions, has been implemented on three different computers.     

测长、称重测量控制系统的设计与应用

主要介绍了攀成伊红石油钢管有限责任公司石油套管车丝线测长、称重测量控制系统的设计与应用。     

Hierarchical scheduling in an intelligent environmental control system

This paper describes the design and implementation of a hierarchical scheduling subsystem and graphical user interface in an intelligent environmental control system. The hierarchical scheduling system is capable of managing all environmental events occurring in widely different time scales as specified by the user. We employ a knowledge representation scheme called a system entity structure to specify the environmental schedules in a hierarchical fashion. A system entity structure called TAL (Timed Action Language) is developed. TAL organizes a family of all possible long-/mid-/short-term schedules from which a specific schedule can be pruned by the user through graphical interface.Research was done while the author was a member of the Environmental Research Lab, University of Arizona. A Preliminary version of the paper was presented at 2nd International Conference on Industrial & Engineering Applications of AI and Expert System [5].     

Some applications of randomized algorithms for control system design

In this paper a few “difficult” problems related to simultaneous stabilization of three plants (equivalent to a certain problem related to unit interpolation in H_∞) have been addressed through the framework of randomized algorithms. These problems which were proposed by Blondel (Simultaneous Stabilization of Linear Systems, Springer, Berlin, 1994) and Blondel and Gevers (Math. Control Signals Systems 6 (1994) 135) concern the existence of a controller.     

Bounds for convex variational programming problems arising in power system scheduling and control

The convex variational programming problem has been found of practical importance to power system scheduling and control. Convex variational programming problems are closely related to the convex programming problems treated by Kuhn and Tucker [8]. Among their positive attributes are the absence of difficulties with weak relative minima and with saddle-point or conjugate-point conditions. As a result it is feasible to develop dual-variational problems and to provide estimates for bracketing the extreme value of the functional of the variational problem when gradient or successive approximations methods are employed for determination of near optimal control schedules. This paper develops necessary and sufficient conditions for the optimal control schedule and a means for numerically determining bounds to the extreme value of the functional. Applications are given to the problem of hydrothermal power system coordination.     

CPU scheduling and memory management for interactive real-time applications

In this paper, we propose, design, implement, and evaluate a CPU scheduler and a memory management scheme for interactive soft real-time applications. Our CPU scheduler provides a new CPU reservation algorithm that is based on the well-known Constant Bandwidth Server (CBS) algorithm but is more flexible in allocating the CPU time to multiple concurrently-executing real-time applications. Our CPU scheduler also employs a new multicore scheduling algorithm, extending the Earliest Deadline First to yield Window-constraint Migrations (EDF-WM) algorithm, to improve the absolute CPU bandwidth available in reservation-based systems. Furthermore, we propose a memory reservation mechanism incorporating a new paging algorithm, called Private-Shared-Anonymous Paging (PSAP). This PSAP algorithm allows interactive real-time applications to be responsive under memory pressure without wasting and compromising the memory resource available for contending best-effort applications. Our evaluation demonstrates that our CPU scheduler enables the simultaneous playback of multiple movies to perform at the stable frame-rates more than existing real-time CPU schedulers, while also improves the ratio of hard-deadline guarantee for randomly-generated task sets. Furthermore, we show that our memory management scheme can protect the simultaneous playback of multiple movies from the interference introduced by memory pressure, whereas these movies can become unresponsive under existing memory management schemes.     

The optimal decentralized control of a large power system: Load and frequency control

The load and frequency control of a multi-area interconnected power system is studied. In this problem, the system is assumed to be subject to unknown constant disturbances, and it is desired to obtain, if possible, robust decentralized controllers so that the frequency and tieline/net-area power flow of the power system are regulated. The problem is solved by using some structural results recently obtained in decentralized control, in conjunction with a parameter optimization method which minimizes the dominant eigenvalue of the closed-loop system. A class of minimum order robust decentralized controllers which solves this general multi-area load and frequency control problem is obtained. Application of these results is then made to solve the load and frequency control problem for a power system consisting of nine synchronous machines (described by a 119th-order system). It is shown that the load and frequency controller obtained in this case is not likely to be significantly improved by using more complex controllers; in particular, it is shown that the conventional controller, used in regulating the net-area power flow of a system, is not likely to be significantly improved upon by using more complex controllers.     

Multithreading programs: guidelines for DCE applications

Multithreading provides a popular mechanism for achieving concurrency, but managing that concurrency can daunt even experienced programmers. The authors offer a tutorial on using threads safely and effectively in an RPC-supported, distributed environment