High-level Computer Language Research Articles

Understanding the Modelling and Analysis of a Shunt Active Power Filter Using MATLAB/Simulink

This paper deals with the modelling and analysis of a shunt active power filter by the use of a MATLAB/Simulink program. The modelling approach adopted in the paper is graphical in nature, as opposed to mathematical models embedded in code using a high-level computer language. The model is presented clearly and in a detailed manner, targetted especially at postgraduate students. The performance of the active power filter is illustrated by considering a 400 kV A, six-pulse, fully controlled bridge rectifier supplied from a typical distribution system via a rectifier transformer.

Development of a web‐based mass transfer processes laboratory: System development and implementation

AbstractA web‐based environment is utilized as a means to introduce advanced mass transfer processes concepts in environmental engineering and science courses. System development and implementation is presented, including detailed descriptions of the techniques employed to link software written in high‐level computer languages such as C++ and FORTRAN to an internet‐based, user‐friendly graphical user interface for both program input and output. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 25–39, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10036

Modeling and analysis of custom power systems by PSCAD/EMTDC

This paper addresses the timely issue of modeling and analysis of custom power controllers, a new generation of power electronics-based equipment aimed at enhancing the reliability and quality of power flows in low-voltage distribution networks. The modeling approach adopted in the paper is graphical in nature, as opposed to mathematical models embedded in code using a high-level computer language. The well-developed graphic facilities available in an industry standard power system package, namely PSCAD/EMTDC, are used to conduct all aspects of model implementation and to carry out extensive simulation studies. Graphics-based models suitable for electromagnetic transient studies are presented for the following three custom power controllers: the distribution static compensator (D-STATCOM), the dynamic voltage restorer (DVR), and the solid-state transfer switch (SSTS). Comprehensive results are presented to assess the performance of each device as a potential custom power solution. The paper is written in a tutorial style and aimed at the large PSCAD/EMTDC user base.

Modeling and Analysis of Custom Power Systems by PSCAD/EMTDC

This paper addresses the timely issue of modeling and analysis of custom power controllers, a new generation of power electronics-based equipment aimed at enhancing the reliability and quality of power flows in low-voltage, distribution networks [2],[3]. The modeling approach adopted in this article is graphical in nature, as opposed to mathematical models embedded in code using a high-level computer language. The well-developed graphic facilities available in an industry standard power system package, namely, PSCAD/EMTDC, are used to conduct all aspects of model implementation and to carry out extensive simulation studies. Graphics-based models suitable for electromagnetic transient studies are presented for the following three custom power controllers: the distribution static compensator (D-STATCOM), the dynamic voltage restorer (DVR), and the solid-state transfer switch (SSTS). Comprehensive results are presented to assess the performance of each device as a potential custom power solution. The paper is written in a tutorial style and aimed at the large PSCAD/EMTDC user base.

Analysis of tracer tests with simple spreadsheet models

Interpretations of tracer tests involve matching field data by the use of computer simulation programs. As the complexity of the simulator model increases, the number of trial runs needed to fit field data satisfactorily increases rapidly. The conventional fitting procedure can thus become cumbersome and can involve prohibitive computer costs. This study presents a new methodology that is devised to model tests in heterogeneous formations. These rigorous simulators written in high-level computer languages are replaced by simple response functions generated in spreadsheet software. Matching the tracer data now involves function evaluations rather than full simulator runs, resulting in a large reduction in computing time. Analyzing laboratory tracer tests shows the uses of spreadsheet models. Advantages and disadvantages of the technique are discussed.

Construction of complex reaction systems—III. An example: alkylation of olefins

The modeling of complex reaction systems is necessary in the design and analysis of many chemical processes, such as fermentation, polymerization, and petroleum refining. We have designed a high level computer language, the Reaction Description Language, to easily and transparently describe generic reaction sites and the transformation of the reactants to products. The compiled reactions are submitted to a network generator, which iteratively applies the reactions to the reactants to form the complete reaction network. The Reaction Description Language, RDL, can be used to describe any type of reaction. Therefore, it is not limited to a specific type of reaction system. Here, we present a variety of reaction networks using reaction types from the alkylation of olefins. The effect of changing the reactants, reaction types, and pruning rules is examined.

Modern Fortran revived as the language of scientific parallel computing

The Fortran (FORmula TRANslating) computer language was the result of a project begun by John Backus at IBM in 1954. The goal of this project was to provide a way for programmers to express mathematical formulas through a formalism that computers could translate into machine instructions. Initially there was a great deal of skepticism about the efficacy of such a scheme. “How,’’ the scientists asked, “would anyone be able to tolerate the inefficiencies that would result from compiled code?’’ But, as it turned out, the first compilers were surprisingly good, and programmers were able, for the first time, to express mathematics in a high-level computer language. Fortran has evolved continually over the years in response to the needs of users, particularly in the areas of mathematical expressivity, program maintainability, hardware control (such as I/O), and, of course, code optimizations. In the meantime, other languages such as C and C11 have been designed to better meet the nonmathematical aspects of software design, such as graphical interfaces and complex logical layouts. These languages have caught on and have gradually begun to erode the scientific/engineering Fortran code base. By the 1980s, pronouncements of the “death of Fortran” prompted language designers to propose extensions to Fortran that would incorporate the best features of other high-level languages and, in addition, provide new levels of mathematical expressivity popular on supercomputers such as the CYBER 205 and the CRAY systems. This language became standardized as Fortran 90 (ISO/IEC 1539: 1991; ANSI X3.1981992). At the present time, Fortran 95, which includes many of the parallelization features of High Performance Fortran discussed later in this paper, is in the final stages of standardization. It is not yet clear whether the modernization of Fortran can, of itself, stem the C tide. However, I will demonstrate in this paper that modern Fortran is a viable mainstream language for parallelism. It is true that parallelism is not yet part of the scientific programming mainstream. However, it seems likely that, with the scientists’ never-ending thirst for affordable performance, parallelism will become much more common—especially

A Method to Assess Analytical Uncertainties Over Large Concentration Ranges With Reference to Volatile Organics in Water

AbstractThe uncertainty associated with a volatile organic concentration measurement is a function of variability and bias introduced at the various levels of sample handling: collection, storage, and analysis. During the past decade, sampling materials and the development and/or improvement of sampling protocols have been the subject of considerable research activity. As a result, in cases of samples properly handled, the analytical variability can be the dominant source of uncertainty in a given concentration value. Here analytical variability refers to any error that might arise during analysis, including the detector response error and any sample handling errors common to both standards and samples. This can be a particular concern for field analyses by gas chromatography (GC), Well‐established statistical methods are available to estimate analytical uncertainty from linear calibration curves, but these methods are poorly suited for the analysis of volatile organics because organic samples frequently require instrument calibration (usually GC) over several orders of magnitude in concentration. If a single linear calibration curve is used to determine sample concentrations and uncertainties, then unrealistically large uncertainties may be assigned to low concentration samples. However, the methods can be adopted for extended concentration range calibration curves by breaking the overall calibration line down into smaller sub‐calibration lines that span smaller ranges. These can then be examined and used selectively to determine concentrations with more appropriate uncertainties attached. The method of multiple callbration line analysis described here is suitable for programming with any high level computer language. It can be used to calculate meaningful analytical uncertainty values for any substance analyzed over a wide range in concentrations (i.e., an order of magnitude or more).

Passenger‐Terminal Simulation Model

The development of a high-level computer language designed to simulate passenger terminals is described. This language is used to represent the operation of passenger terminals in terms of the number of passengers arriving, being served and queueing at the various terminal facilities. It may be utilized in performance and capacity assessment of terminal buildings. Passenger terminal flows are simulated by assuming that passenger movements may be represented by fluid flowing through a system of interconnected reservoirs, which correspond to terminal components. Paxgraphs, functions describing passenger arrivals as a function of time before flight departure or after flight arrival, are used to generate passenger flows for user-defined discrete time intervals, typically ranging from one to five minutes. The simulation analyzes the movement of passengers through the predetermined paths within the terminal. It is assumed that there is a condition of continuity between consecutive facilities in a path: the output of the upstream component is the input of the downstream component. The operation of terminal facilities is simulated by calculating output flows and queue lengths given input flows, queue lengths and service characteristics at the end of discrete time intervals. Seven pre-programmed models have been developed to simulate terminal components, the passenger-greeter and passenger-bag matching processes, and the departure public concourse and ancillary facilities. Each model calculates output flow and queue length through expressions specifically developed to represent the functioning of a class of terminal components. It is assumed that processors operate under FIFO discipline; the capacity of a congested server is divided between flows of different flights proportionally to their volumes and the queue is served before the new arrivals. The terminal simulation language is simple to use, easy to learn and flexible. New classes of terminal components may be defined and models that fail to simulate facilities accurately may be modified or replaced. The capabilities of the proposed approach are demonstrated through a simulation of Terminal One at Toronto International Airport on a typical day. The results of this simulation are shown to be similar to those produced by the Transport Canada simulation model.

High-level language computer viruses— a new threat?

Companion viruses have not received as much attention as their non-companion counterparts. To some extent this is due to the fact that only a small percentage of the computer viruses released into the computing world have been companion viruses. However, this may change in the near future. Companion viruses do not have size restrictions that non-companion viruses have. Thus, these viruses can be programmed to perform more actions. These actions may be to steal corporate data as well as circumvent anti-viral programs. This paper discusses these types of virus and several detection techniques.

GRPP, a scientific programming language preprocessor designed using lex and yacc

There have been many advances in the functionality and usefulness of high level computer languages since the early incarnations of FORTRAN. The recent trend towards structured and object oriented languages has given the scientific programmer very sophisticated tools for developing applications motivated by data, procedure, and reusability. However, in many areas of scientific and numerical software development, what is needed most is a programming language possessing the basic grammar familiar from analytical discussions of the field of study. The use of lex and yacc for developing specialized computer dialects or languages provide a powerful means of injecting the customary analytic notation and grammar into a scientific programming project. A general relativity preprocessor, grpp, is presented as such an application of lex and yacc to extend C style computer languages to handle tensor analysis in a manner consistent with that which is taught to students of general relativity, differential geometry, and tensor analysis. As an application demonstrating the usefulness of grpp, the fully relativistic four‐dimensional trajectory of a test particle around a Kerr black hole is calculated using a very simple to follow, bug‐free program taken straight out of any text on general relativity or differential geometry.

An improved method of scaling for real-time signal processing applications

Implementing digital signal processing algorithms using fixed-point arithmetic is a difficult task, involving trade-offs to balance the efficiency and noise performance of a given realization. One of the most important components of such design is to minimize the noise generated by quantization and over flow effects. This is generally accomplished by the scaling of signals and coefficients in the fixed-point realization based upon knowledge of signal features and statistics. This paper presents a new method for structuring this design task. It uses a model based on scaled-fractional numbers to simplify both the concepts required to realize fixed-point arithmetic versions of algorithms, as well as the real effort required for such implementations. This model has been implemented as a data type in a high level computer language to allow direct implementation of fixed-point arithmetic versions of algorithms.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A simple Gauss-Newton procedure for covariance structure analysis with high-level computer languages

An implementation of the Gauss-Newton algorithm for the analysis of covariance structures that is specifically adapted for high-level computer languages is reviewed. With this procedure one need only describe the structural form of the population covariance matrix, and provide a sample covariance matrix and initial values for the parameters. The gradient and approximate Hessian, which vary from model to model, are computed numerically. Using this approach, the entire method can be operationalized in a comparatively small program. A large class of models can be estimated, including many that utilize functional relationships among the parameters that are not possible in most available computer programs. Some examples are provided to illustrate how the algorithm can be used.

Global optimization of univariate Lipschitz functions: I. Survey and properties

We consider the following global optimization problems for a univariate Lipschitz functionf defined on an interval [a, b]: Problem P: find a globally optimal value off and a corresponding point; Problem Pź: find a globallyź-optimal value off and a corresponding point; Problem Q: localize all globally optimal points; Problem Qź: find a set of disjoint subintervals of small length whose union contains all globally optimal points; Problem Qź: find a set of disjoint subintervals containing only points with a globallyź-optimal value and whose union contains all globally optimal points. We present necessary conditions onf for finite convergence in Problem P and Problem Q, recall the concepts necessary for a worst-case and an empirical study of algorithms (i.e., those ofpassive and ofbest possible algorithms), summarize and discuss algorithms of Evtushenko, Piyavskii-Shubert, Timonov, Schoen, Galperin, Shen and Zhu, presenting them in a simplified and uniform way, in a high-level computer language. We address in particular the problems of using an approximation for the Lipschitz constant, reducing as much as possible the expected length of the region of indeterminacy which contains all globally optimal points and avoiding remaining subintervals without points with a globallyź-optimal value. New algorithms for Problems Pź and Qź and an extensive computational comparison of algorithms are presented in a companion paper.

Using dBASE to write PENNAME, a computer key to common Penicillium species

dBASE III Plus™ computer software includes a high level computer language as well as a database management program. dBASE possesses advantages for key construction, including simple entry of raw data, effective user interaction in the selection of outputs, and ready comparison of included species with unknowns. This paper describes the use of dBASE in the construction of PENNAME, a new computer key to common Penicillium species.

Overdetermined Celestial Fix by Iteration

A celestial fix which minimizes the sum of the squares of the sextant altitude residuals is presented as an alternative to constructing lines of position (LOPs) from azimuths and altitude differences. It is especially applicable to multiple sights, from one or several celestial bodies, providing covariance estimates for the longitude and latitude and a basis for discarding wild readings. The iterative algorithm which replaces the sight reduction tables can be programmed in a high-level computer language and is very robust with respect to the observer's initially guessed position. A fix from a series of sun altitudes taken for an hour after sunrise is presented as an example. Geometry makes this particular fix highly accurate in longitude and inaccurate in latitude, while the low sun angles make it liable to refraction error.

Microcomputer based differential diagnosis of dysmorphic syndromes.

Dysmorphic syndromes are characterized by associations of physical abnormalities depending in its diagnosis on the recognition of a particular pattern. Because of their multiplicity, the rarity of some of them, and the frequency of new reports, computerized data bases have proved useful as powerful tools assisting in the differential diagnosis. The role of artificial intelligence methods, in particular Expert Systems, as promising tools in helping physicians to perform a clinical diagnosis is underlined. Using a high level computer language presently used in the artificial intelligence field (Prolog), a microcomputer based system for the differential diagnosis of dysmorphic syndromes is described. Its capabilities and simplicity of use, derived from an efficient and attractive computer interface, are underlined. The need of performance assessment by evaluating its accuracy and usefulness before its introduction into genetic clinical practice is stressed. Finally, for the completeness of the knowledge base, the need of cooperation between international centers is emphasized.

Design of a computer-controlled electroanalytical system

A dedicated high-level computer language has been written for use with a computer-controlled electroanalytical system. The language can be compiled to produce executable machine code modules, and provides considerable flexibility in the design of experiments. The compiled modules can be linked to programs in other high-level languages, allowing very complex strategies to be implemented. The language is sufficiently general to allow extension to the control of other types of analytical instrumentation.

Future role of high level languages in power system control centers

Four short reports are presented, each dealing with the attributes of different high-level computer languages and how they might perform in the specific application of a utility energy control center. The reports deal specifically with Fortran, Ada, Pascal, and the C environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Appearance-potential spectroscopy and work function

Methods and procedures are described which permit the use of a commercial scanning Auger microprobe (SAM) to obtain work-function measurements at the geometrical resolution routinely achieved in surface composition determinations. The work function is estimated by the appearance potential for secondary electrons. The need for auxiliary circuitry has been eliminated by the development of methods to access the existing interface between the SAM and its computer control. High-level computer languages are used to obtain coincident appearance potential and Auger spectra. A discussion of the relationship between appearance potential and work function is presented. It is shown that the difference between work function and appearance potential depends on the radius R of a work-function patch and the vertical distance to the surface potential barrier maximum, x*. For small x*/R the appearance potential is a good estimate of work function. The technique is illustrated by results obtained from surfaces with nonuniform coverages of residual gases.