Setup Phase Research Articles

The Setup Phase of Project Open Book: A Report to the Commission on Preservation and Access on the Status of an Effort to Convert Microfilm to Digital Imagery

Article The Setup Phase of Project Open Book: A Report to the Commission on Preservation and Access on the Status of an Effort to Convert Microfilm to Digital Imagery was published on January 1, 1994 in the journal Microform & Digitization Review (volume 23, issue 3).

The computer generation of multinomial random variates

The generation of random variates from the multinomial distribution is often required in simulation studies involving methods for the analysis of discrete data. Although several methods have been proposed, comprehensive comparisons of the various algorithms have not been previously carried out. This paper describes seven methods for multinomial variate generation and compares them with respect to the criteria of accuracy, set-up time, simplicity of implementation, storage requirements, and generation time. Based on the results of an extensive empirical study, the Brown and Bromberg ( Amer. Statist. 38, 1984) two-stage procedure is generally the fastest algorithm, but requires a complicated set-up phase and extensive storage requirements. The conditional distribution method using the modal binomial variate generator of Kemp ( Commun. Statist.—Theor. Meth. 15, 1986) is shown to be a good all-purpose algorithm, in that it has wide applicability, does not require a set-up phase and extensive storage, and is reasonably competitive with the Brown—Bromberg algorithm in terms of generation time.

Multiple Communication in Multihop Radio Networks

Two tasks of communication in a multihop synchronous radio network are considered: Point-to-point communication and broadcast (sending a message to all nodes of a network). Efficient protocols for both problems are presented. Even though the protocols are probabilistic, it is shown how to acknowledge messages deterministically. Let n, D, and $\Delta $ be the number of nodes, the diameter and the maximum degree of our network, respectively. Both protocols require a setup phase in which a BFS tree is constructed. This phase takes $O((n + D\log n)\log \Delta )$ time. After the setup, k point-to-point transmissions require $O((k + D)\log \Delta )$ time on the average. Therefore the network allows a new transmission every $O(\log \Delta )$ time slots. Also, k broadcasts require an average of $O((k + D)\log \Delta \log n)$ time. Hence the average throughput of the network is a broadcast every $O(\log \Delta \log n)$ time slots. Both protocols pipeline the messages along the BFS tree. They are always successful on the graph spanned by the BFS tree. Their probabilistic behavior refers only to the running time. Using the above protocols the ranking problem is solved in $O(n\log n\log \Delta )$ time. The performance analysis of both protocols constitutes a new application of queueing theory.

Constructing protocols with alternative functions

The author describes a method for designing communication protocols which can perform several distinct functions, but are limited to the execution of one function at a time. The construction of such a protocol consists of two steps: (1) developing a component protocol for each function to be included, and (2) integrating the components into the target protocol. The integration involves the resolution of potential component competition and process synchronization problems. A sufficient condition for the safety of the integrated protocol is also discussed. This design method is simple to use and promotes reuse of existing protocols. The construction of two protocols-the call setup phase of a data link control protocol and a portion of the CCITT's X.21 Recommendation-is demonstrated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On the System Setup and the Scheduling Problem in a Flexible Manufacturing System (FMS)

In this paper we present a model which unifies several existing models with respect to two phases of the planning process of a Flexible Manufacturing System. These phases are the system setup phase and the scheduling phase and in literature they usually are considered separately. We give a mathematical formulation encompassing both phases. From this formulation several existing approaches can be deduced. We also describe some heuristic methods for our model and present the computational results.

Intelligent Forms Processing

The automatic reading of optically scanned forms consists of two major components: extraction of the data image from the form and interpretation of the image as coded alphanumerics. The second component is also known as optical character recognition, or OCR. We have implemented a method for entry of a wide variety of forms that contain machine-printed data and that are often produced in business environments. The function, called Intelligent Forms Processing (IFP), accepts conventional forms that call for information to be printed in designated blank areas, but in which the information may exceed boundaries due to poor registration during printing. The human eye easily accommodates data that impinge on form boundaries or on background text; however, the same powers of discrimination applied to machine processing pose a technical challenge. The IFP system uses a setup phase to create a model of each form that is to be read. Scanned forms containing data are compared against the matching form model. Special algorithms are employed to extract data fields while removing background printing (e.g., form lines) intersecting the data. The extracted data images are interpreted by an OCR process that reads typical monospace fonts. New fonts may be added easily in a separate design mode. If the data are alphabetic, a lexicon may be assembled to define the possible entries.

Flow control schemes and delay/loss tradeoff in ATM networks

Performance and flow control mechanisms, which represent ATM (asynchronous transfer mode) flexibility, are discussed. To control performance, delay- and/or loss-sensitive service classes, and two mechanisms to realize these classes, are proposed. It is shown that it is possible to have better performance than with other mechanisms, such as no-class distinction or simple priority methods. It is further suggested that this performance controllability results in the provision of multiple logical services, including quasi-STM (synchronous transfer mode; compatible with circuit switching), by an ATM network. ATM flow control is based on a call-oriented resource allocation mechanism similar to circuit switching. The concepts of call/line bit rate ratio and multiplexing degree are seen to be significant for efficient use of resources. When the network handles calls with large call/line bit rate ratios, user-specified flow control parameters at the call setup phase are important for resource assignment. The definition of two types of maximum throughput of each call and its usage for resource management are proposed. >

Non-linear coupling effects on the relaxation process in the reversed field pinch

The relaxation process in the reversed field pinch has been studied extensively with three-dimensional magnetohydrodynamic simulations. It is found that the non-linear coupling between multiple helicity modes plays a leading role in the relaxation process. Specifically, the (m; n)=(0; 1) island is excited as a result of non-linear coupling between the linearly unstable m=l modes, with a toroidal mode number difference of one. The m=0 island is then subject to axisymmetric non-linear reconnection whereby reversed flux is effectively generated in the outer region. It should be noted that although the axisymmetric non-linear reconnection of m=0 island is the dominant relaxation process, helical non-linear reconnection of linearly unstable m=l modes also plays some role in the relaxation of the whole system. It is also found that through this multiple helicity relaxation process, Taylor's minimum energy state is realized. The simulation results are generally consistent with experimental observations in the sustainment phase. This indicates that the multiple helicity relaxation process is of fundamental importance in the maintenance of the reversed field during the sustainment phase as well as in the self-reversal during the set-up phase. The relation between relaxation and aspect ratio has also been examined and it is found that the relaxation process is not strongly affected by the aspect ratio.

Iterative solution of the global element equations

A previous paper [4]discussed in detail techniques for setting up the defining equations for the Global Element Method for elliptic partial differential equations, and sketched an iterative method for their solution. For a calculation in two-dimensions using M elements (with a basis of degree N - 1 in each element), operation counts of O( MN 4) were achieved for both set-up and solution phases. Timings were included demonstrating this count for the set-up, but not the solution, phase. In this paper we describe a modified and simpler version of the iterative solution scheme and report timings obtained with an exploratory implementation of the scheme. These demonstrate the rapid convergence and O( MN 4) behaviour predicted for it.

Total radiation measurements in the ETA-BETA II experiment

The dependence of the measured radiation losses in ETA-BETA II on plasma density and plasma current rise time is discussed. A high-density limit is found, corresponding to large radiation. Above this limit, burning through the light impurities (mainly oxygen) does not take place and a cold, radiation-dominated discharge is obtained. This high-density limit scales with the plasma current, indicating a lower limit on the I/N parameter similar to the tokamak high-density limit. With longer current rise times the radiation energy loss during the set-up phase increases about linearly with rise time, corresponding always to about 50% of the total energy losses during this phase.