An aggregative technique to obtain an improved approximation of the equilibrium vector of a Markov chain with a nearly completely decomposable transition matrix is presented. The technique is demonstrated on a model o...
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An aggregative technique to obtain an improved approximation of the equilibrium vector of a Markov chain with a nearly completely decomposable transition matrix is presented. The technique is demonstrated on a model of a multiprogrammed computer system.
This paper introduces a new concept regarding information processing in general, but more specifically inter-process communication (IPC) and semantic information processing, where a controlled environment is essential...
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This paper introduces a new concept regarding information processing in general, but more specifically inter-process communication (IPC) and semantic information processing, where a controlled environment is essential in order to overcome various problems such as deadlocks. The emphasis here is on communication management and the tools necessary for the user to control the IPC environment at both intra- and inter-process levels. The IPC system developed in C is also discussed in detail.
This paper considers the programming of passive (cold and warm standbys) and active replicated systems in Ada 95. We show that it is relatively easy to develop systems which act as standbys using the facilities provid...
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This paper considers the programming of passive (cold and warm standbys) and active replicated systems in Ada 95. We show that it is relatively easy to develop systems which act as standbys using the facilities provided by the language and the Distributed systems Annex. Arguably, active replication in Ada 95 can be supported in a manner which is transparent to the application. However, this is implementation-dependent, requires a complex distributed consensus algorithm (or a carefully chosen subset of the language to be used) and has little flexibility. We therefore consider two extensions to the Distributed systems Annex to help give the application programmer more control. The first is a via a new categorization pragma which specifies that a RCI package can be replicated in more than one partition. The second is through the introduction of a coordinated type which has a single primitive operation. Objects which are created from extensions to coordinated types can be freely replicated across the distributed system. When the primitive operation is called, the call is posted to all sites where a replica resides, effectively providing a broadcast (multicast) facility. We also consider extensions to the partition communication subsystem which implement these new features.
We show how properties of an interesting class of imperative programs can be calculated by means of relational modeling and symbolic computation. The ideas of [5, 26] are implemented using symbolic computations based ...
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We show how properties of an interesting class of imperative programs can be calculated by means of relational modeling and symbolic computation. The ideas of [5, 26] are implemented using symbolic computations based on Maple [30].
GU12QAD-3D is graphical user interface developed in Visual Basic (VB) version 6.0 to prepare input for the QAD-CGPIC program. QAD-CGPIC is a FORTRAN code that combines QAD-CGGP (RSICC-CCC-493, USA) and PICTURE [Irving...
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GU12QAD-3D is graphical user interface developed in Visual Basic (VB) version 6.0 to prepare input for the QAD-CGPIC program. QAD-CGPIC is a FORTRAN code that combines QAD-CGGP (RSICC-CCC-493, USA) and PICTURE [Irving, D.C., Morrison, G.W., 1970. PICTURE-an aid in debugging GEOM input data, ORNL-TM-2892] for neutron and gamma-ray shielding calculations by the point kernel method in a consistent fashion to utilize the capabilities of two independent codes. The FORTRAN code calculates fast neutron and gamma-ray penetration through various shield configurations defined by combinatorial geometry specifications. It has provision to estimate buildup factor either from Geometric Progression (GP) coefficients (ANS-6.4.3, 1990) or from Capos'. Capabilities of the FORTRAN code is extended by modifying it to handle off-centred multiple identical sources. Several standard tests of inputs are carried out to validate the modified code. The FORTRAN code executable is created with a Lahey compiler. The user interface facilitates interactive viewing of the geometry of the system with online context sensitive help. Inputs for several practical problems relating to nuclear fuel reprocessing labs are provided. The software runs on Pentium III computers under windows environment and is transmitted in one CD. The software can be obtained from Radiation Safety Information and Computational Centre (RSICC), ORNL, USA with code package identification number CCC-697. (c) 2005 Elsevier Ltd. All rights reserved.
Evaluating the performance of local area networks is a major concern of the research community and organizations that install this type of network. In data processing applications, sorting is one of the most important...
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Evaluating the performance of local area networks is a major concern of the research community and organizations that install this type of network. In data processing applications, sorting is one of the most important and frequently performed operations, because database operations can be performed efficiently on sorted files. The efficiency of sorting algorithms in local networks, therefore, plays a significant role in determining overall network performance. This paper evaluates four alternate methods of performing external sort in common-bus local networks. Each method has five steps: interrupt and synchronization, network data transfer by packets, local sorting, global sorting, and output. The execution time for each method is calculated for four cases using different overlaps among the time components. Each method is evaluated by observing its behavior at different network speeds, file sizes, network sizes, page sizes, I/O times, and interrupt and synchronization times. This paper shows how changing the value of these variables affects the performance of the sorting algorithms. These observations are useful in designing sorting algorithms and other general, parallel algorithms for common-bus local networks.
Programmers usually type characters on a keyboard to enter, test, and debug computer programs. More than 30 years ago researchers began augmenting those characters with diagram but pure ASCII text is still the ubiquit...
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Programmers usually type characters on a keyboard to enter, test, and debug computer programs. More than 30 years ago researchers began augmenting those characters with diagram but pure ASCII text is still the ubiquitous standard. This article argues that these attempts to make programming more visual have failed to become mainstream because they are too conservative. Various radical syntaxes for programs are shown to be feasible and offer many advantages over the state of the art.
We present a simple algorithm for emulating an N -processor CROW PRAM on an N -ode butterfly. Each step of the PRAM is emulated in time O (log N ) with high probability, using FIFO queues of size O (1) at each node. T...
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We present a simple algorithm for emulating an N -processor CROW PRAM on an N -ode butterfly. Each step of the PRAM is emulated in time O (log N ) with high probability, using FIFO queues of size O (1) at each node. The only use of randomization is in selecting a hash function to distribute the shared address space of the PRAM onto the nodes of the butterfly. The routing itself is both deterministic and oblivious, and messages are combined without the use of associative memories or explicit sorting. As a corollary we improve the result of Pippenger by routing permutations with bounded queues in logarithmic time, without the possibility of deadlock. Besides being optimal, our algorithm has the advantage of extreme simplicity and is readily suited for use in practice.
A method of evaluating recursively defined functions which uses two (or more) stacks is described in this paper. This method is designed to reduce the stack storage needed and requires simpler ‘linkage’ information ...
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A method of evaluating recursively defined functions which uses two (or more) stacks is described in this paper. This method is designed to reduce the stack storage needed and requires simpler ‘linkage’ information than the single stack method. In addition, a study of ‘go-to’ (or iterative) type recursive definitions is made and it is shown that these require bounded stack storage for their evaluation.
One of the disadvantages of Microsoft's disk operating system MS-DOS TM is its restriction to only one process running at a time. Consequently the integration of standard application programs to more complex appli...
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One of the disadvantages of Microsoft's disk operating system MS-DOS TM is its restriction to only one process running at a time. Consequently the integration of standard application programs to more complex application systems is rather limited. This paper shows how to use Modula-2 for integrating several standard MS-DOS applications. To perform this task, a Modula supervisor program implements a shell between application, MS-DOS operating system and BIOS (basic input output system). This shell provides all services needed for loading and executing programs as concurrent processes as well as a communication environment for these processes.
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