Composite programs: hierarchical construction, circularity, anddeadlocks

A graph-oriented, nonprocedural development environment in which composite programs are constructed by coupling a collection of existing component programs, the interfaces of which are defined by a fixed number of input ports and output ports, is discussed. It is shown that when the coupling graph is cyclic there is the possibility of a deadlock. A system that permits hierarchical construction of programs while testing, using a simple algebraic procedure, the resulting composite programs for communication deadlocks is presented. A decomposition-based approach to cycle enumeration is described. A formal graph-theoretic model of communication behavior for a class of atomic programs is presented. The model is then used to derive necessary and sufficient conditions for a deadlock to arise in a cycle. Techniques for dealing with deadly cycles (once identified) and improving the efficiency of their execution, once the cycles have been resolved, are described     

A set of programs for analysis of kinetic and equilibrium data

A program package that can be used for analysis of a wide range of kinetic and equilibrium data is described. The four programs were written in Turbo Pascal and run on PC, XT, AT and compatibles. The first of the programs allows the user to fit data with 16 predefined and one user-defined function, using two different non-linear least-squares procedures. Two additional programs are used to test both the evaluation of model functions and the least-squares fits. One of these programs uses two simple procedures to generate a Gaussian-distributed random variable that is used to simulate the experimental error of measurements. The last program simulates kinetics described by differential equations that cannot be solved analytically, using numerical integration. This program helps the user to judge the validity of steady-state assumptions or treatment of kinetic measurements as relaxations.     

基于串口通信的DSP应用程序在线升级方法

为解决特殊场合DSP程序升级困难的问题,以TMS320F28035为例,介绍了一种基于串口通信的适合于TMS320C2000系列DSP实现程序更新的在线升级方法。描述了该在线升级方法的基本思想和实现步骤,给出了关键部分的程序代码。实验证明,该方法简单可靠,可用于嵌入式设备软件程序的升级更新中。     

Structured data in structural analysis software

This paper discusses the use of computer data structures in finite-element structural analysis programs. A number of data structure types that have been shown to be useful in such programs are introduced and described. A simple finite-element model is used to demonstrate how the given set of data structure types naturally lend themselves to developing software for the model. Different methods of implementing data structures in the context of a program are discussed.     

Automatic generation of self-scheduling programs

Techniques are described for the automatic generation of self-scheduling parallel programs. Both scheduling algorithms and the concurrent components of applications are expressed in a high-level concurrent language. Partitioning and data dependency information are expressed by simple control statements, which may be generated either automatically or manually. A self-scheduling compiler, implemented as a source-to-source transformation, takes application code, control statements, and scheduling routines and generates a new program that can schedule its own execution on a parallel computer. The approach has several advantages compared to previous proposals. It generates programs that are portable over a wide range of parallel computers. There is no need to embed special control structures in application programs. The use of a high-level language to express applications and scheduling algorithms facilitates the development, modification, and reuse of parallel programs     

Algebra manipulating programs for structural analogies

Two computer programs are described for solving sets of simultaneous equations with coefficients in the form of algebraic expressions.Both programs retain the algebraic nature of these coefficients throughout, although the methods of storage and solution are entirely different. The problems which the programs were originally designed to solve relate to regular structures, for which modular stiffness matrix equations can be written. The coefficients of these matrices are expressions of simple algebraic quantities and finite difference operators. These operators are transformed into differential operators by the programs, the output giving continuum approximations to the structures. Other applications of the programs are discussed.     

Reasoning about time in higher-level language software

A methodology for specifying and providing assertions about time in higher-level-language programs is described. The approach develops three ideas: the distinction between, and treatment of, both real-time and computer times; the use of upper and lower bounds on the execution times of program elements; and a simple extension of Hoare logic to include the effects of the passage of real-time. Schemas and examples of timing bounds and assertions are presented for a variety of statement types and programs, such as conventional sequential programs including loops, time-related statements such as delay, concurrent programs with synchronization, and software in the presence of interrupts. Examples of assertions that are proved include deadlines, timing invariants for periodic processes, and the specification of time-based events such as those needed for the recognition of single and double clicks from a mouse button     

Parallel program design using high-level Petri nets

Petri nets are proposed as a general-purpose design and modelling tool for parallel programs. The advantages of Petri nets for this purpose are discussed, and a solution to the Dining Philosophers problem is developed using simple Place-Transition nets. The limitations of Place-Transition nets are described, and the Dining Philosophers problem is used to illustrate how Coloured Petri nets can overcome these limitations. A more complex example of a Coloured Petri net is then given, and it is shown how a collection of processes in the Occam programming language can be developed directly from the properties of the net. Another Petri net model of a simple process farm is given, and a solution is developed in Parallel C: this further highlights the suitability of Petri nets as a design tool for parallel programs.     

Studies in the theory of algebraic models of programs with procedures

Algebraic models of programs with procedures extend algebraic models of programs that are free of procedures (simple models of programs). A specific feature of both types of models is that they are built for some formalization of software programs. Models of programs are intended for studying functional equivalence of formalized programs and constructing wide sets of equivalent transformations of programs. Two basic problems in the theory of algebraic models of programs are the equivalence problem and the problem of building complete systems of equivalent transformations. An increasing interest in models of programs with procedures is due to the abundance of results obtained for simple models of programs. The most suitable model of programs with procedures is a gateway model. A remarkable feature of these models is that every such model is induced by some simple model of programs. This paper gives a survey of the latest results obtained for gateway models of programs.     

Lambda-hoisting: A transformation technique for fully lazy evaluation of functional programs

Lambda-hoisting is a technique for transforming functional programs into ones suitable for fully lazy evaluation. The proposed method has a great advantage in generating efficient code for conventional computers. The basic idea of lambda-hoisting is described with remarks on similar techniques, and a simple algorithm is presented in a formal way.     

Generation of interactive displays from FORTRAN using the PDP - 10/LDS-1 computer graphics system

The PDP-10/LDS-1 combination is a powerful and versatile computer graphics system. A package of programs described here permits the generation of displays and interaction with them by means of simple calls from FORTRAN programs. This makes computer graphics available to individuals who know a little FORTRAN but no assembler language. It serves also as a useful introduction to the LDS-1 for experienced programmers who intend to learn the assembler language and to write their own programs Experience with the language has shown that it is learnable quickly by the class of users at which it is aimed. In addition, the same package has been used by more experienced programmers as a powerful research tool in the study of conformations of biological macromolecules, such as proteins, DNA and RNA.     

An object oriented user interface for analysis of biological data

In a previous paper we described a self-documented file and a collection of general purpose programs or tools that facilitates the management and analysis of biological data. The tools can be specified in a pipeline to accomplish a specific analysis task. However, we found that it was difficult for investigators to learn the UNIX command language for specifying pipelines, specify selection tasks through a command language, and visualize the data as they were transformed and rearranged. To alleviate these problems we developed an object-oriented user interface for the pipeline programs. The system consists of four major programs for visualization: Vedit, Vgraf, Vscan, and V spread. Vedit is a simple text editor, Vgraf is a flexible graphics program, Vscan facilitates scanning graphically through large files, and Vspread provides spreadsheet-like capabilities. To demonstrate how the visualization programs are used together to accomplish the needed analysis we describe two case studies and then discuss how well the system accomplished the goals of visualization, short learning curve, and user adaptability.     

CODE: a unified approach to parallel programming

The authors describe CODE (computation-oriented display environment), which can be used to develop modular parallel programs graphically in an environment built around fill-in templates. It also lets programs written in any sequential language be incorporated into parallel programs targeted for any parallel architecture. Broad expressive power was obtained in CODE by including abstractions of all the dependency types that occur in the widely used parallel-computation models and by keeping the form used to specify firing rules general. The CODE programming language is a version of generalized dependency graphs designed to encode the unified parallel-computation model. A simple example is used to illustrate the abstraction level in specifying dependencies and how they are separated from the computation-unit specification. The most important CODE concepts are described by developing a declarative, hierarchical program with complex firing rules and multiple dependency types     

Reanalysing structures with small modifications

A simple method developed for reanalysing slightly modified structures is outlined. The computational process is described and examples of application using two computer programs released by the Highway Engineering Computer Branch of the Department of Transport are presented.     

A simple efficient hidden line algorithm

A simple efficient hidden line algorithm for finite element models is described. The algorithm is general purpose, requires minimal computer storage, and can easily be added to existing plot programs. The routine does not require angle determination, trigonometric functions, or elaborate bookkeeping schemes. Detailed flowcharts and a listing of the computer code are presented.     

A developed system based on nature-inspired algorithms for DNA motif finding process

In this paper, recent algorithms are suggested to repair the issue of motif finding. The proposed algorithms are cuckoo search, modified cuckoo search and finally a hybrid of gravitational search and particle swarm optimization algorithm. Motif finding is the technique of handling expressive motifs successfully in huge DNA sequences. DNA motif finding is important because it acts as a significant function in understanding the approach of gene regulation. Recent results of existing motifs finding programs display low accuracy and can not be used to find motifs in different types of datasets. Practical tests are implemented first on synthetic datasets and then on benchmark real datasets that are based on nature-inspired algorithms. The results revealed that the hybridization of gravitational search algorithm and particle swarm algorithms provides higher precision and recall values and provides average enhancement of F-score up to 0.24, compared to other existing algorithms and tools, and also that cuckoo search and modified cuckoo search have been able to successfully locate motifs in DNA sequences.

     

The design of a real-time operating system for a minicomputer. part II

Part II of the paper discusses elaborations of the simple system described in Part I. These are aimed at making the system more secure, allowing it to support larger programs and lightening the drudgery of coding for it.     

Simplified data structure for analysing mechanisms using character handling techniques

This paper introduces the program SIMPLA¹ for the kinematic analysis of planar linkages. It uses character manipulation subroutines to allow the program to be written with maximum emphasis placed on the user's finding the input data structure easy to understand. Very complex planar linkages may be described using an extremely simple and familiar form of input data. This avoids the usual extended period of acclimatization to the peculiarities of most other linkage programs. The program, which is written in Fortran, includes extensive data checking routines and a self-explanatory conversational feature which assists the user to produce a self-consistent input data set. It has been used successfully on an IBM/370 computer. The methods for writing programs using these character manipulation subroutines are described.