bluuebunny/crossref_metadata_2025_split huggingface dataset:
Digital simulation of adjustable-frequency ac motor drives
Authors: Murphy John M.D. 
Published: March 2008

Simulation techniques are very useful in designing static adjustable-frequency ac drive systems and in evaluating alternative control strategies for them. This paper outlines the basic principles of the modern dc-link static frequency converter, and then describes the implementation of a digital simulation of a complete drive system. The principal components of the drive are programmed as FORTRAN subroutines. The main program uses the IBM Continuous System Model ing Program (CSMP), which is translated into FORTRAN and combined with the FORTRAN subroutines. Harmonics in the output waveform of the frequency converter can cause design and operating problems under steady-state as well as transient conditions. These problems are discussed and illustrated by results from simulation runs.
The microprocessor CPU: some unique features
Authors: Leventhal Lance A. 
Published: March 2008

This article will briefly describe some of the special features of standard single-chip MOS micro processors. Although these devices are very similar to larger central processing units (CPUs), technolo gical and packaging limitations as well as the needs of some common applications have created some differ ences. An understanding of these differences can often help users decide if microprocessors will be suitable for their applications. We shall not discuss the general features of CPU architecture. Many adequate descriptions of those features are available.1,2 Instead, we shall briefly describe the functions of CPUs and then concentrate on the implementation of those functions in micropro cessors.
Moving pictures show simulation to user
Authors: Palme Jacob 
Published: March 2008

One of the most difficult problems with a simulation program is to gain confidence in the accurateness and reliability of the model. If the program is to be used for important decisions, the decision-makers must feel sure that they can depend on the model. To do this, they have to understand what is happening in the program. One way of making the users of the simulation more sure about what is happening in the program is to show what is happening during a simulation as a "moving picture" on a terminal. This can easily be done on a simple standard alphanumeric display ter minal. Our experience is that the extra programming effort is small and that the gain in understanding of the model is high both for the programmer himself and for his client.
A digital computation technique for radar scene simulation
Authors: Holtzman Julian C. , Stiles Josephine A. , Frost Victor S. , Kaupp Verne H. , Komp Edward E. 
Published: March 2008

This paper describes the Point Scattering Model (PSM) for radar-image simulation and its digital implement ation. The model applies to radar images of real and hypothesized scenes. Simulated radar images of real scenes produced via the PSM correlate very favorably with actual radar images of the same scenes. The simulation model requires information about the terrain in the form of a "ground truth data base" and radar backscatter data. Simulated radar images are compared with actual radar images of the same terrain. Flowcharts of the digital im plementation of the PSM are given. A major part of the computing consists of independent parallel tasks and is well adapted to processing on a network of microcomputers. The authors hope that readers of this paper can suggest new configurations of the parallel processing equipment suitable for the rapid and economical execution of programs like those described in the paper.
Modelling heat flow and thermal stress in ingot casting
Authors: Morgan K. , Lewis R.W. , Seetharamu K.N. 
Published: March 2008

Using the finite-element method, we develop a model of heat flow and thermal stress in ingot casting. The model takes into account the intimate contact of ingot and mould in the initial stages and the pres ence of the air gap thereafter, and it handles the effect of the type of lubricant used. The model is general and can deal with different types of bound ary conditions and with variations in material properties. The model is a stress model capable of taking into account time-dependent effects such as creep and of predicting the development of thermal stress fields. To validate the model, simulation results for a particular problem are compared with the correspond ing results obtained by other workers and with experimental data.
Exchange - rate adjustment in a multicurrency monetary system
Authors: Mushin Jeremy D. 
Published: March 2008

A multination monetary system like the European Monetary System (EMS) is intended to concentrate trade and employment within the block of member na tions by stabilising internal exchange rates. Each member nation accepts a defined responsibility for intervention by its central bank to maintain exchange rates within a specified band. Since intermember exchange rates are affected by changes in the ex change rates of individual member currencies with respect to major currencies outside the block, monetary systems like the EMS use a formula to allo cate responsibility among the member nations for counteracting such exogenous disturbances of inter- block exchange rates. Though the rules for assigning responsibility for intervention are clearly stated, their consequences to the member nations are not. For this reason, a simulation model of the EMS was built. (It could, of course, be adapted to represent any similar sys tem.) This paper describes the results of a simula tion study of the EMS based on this model. The study was undertaken to increase understanding of the impact on EMS members of the external economic environment, of changes in the number of members of the EMS, and of changes in their relative trading importance. Simulation was used because the EMS is too complex for conventional mathematical analysis.
Use of the Fisher Exact Probability Test in surface-to-air missile (SAM) countermeasures evaluations
Authors: Borden Andrew G. 
Published: March 2008

In testing the effectiveness of countermeasures against surface- to-air missile (SAM) systems, the important statistic is the pro portion of simulated missiles whose closest approach to a target is outside the lethal radius of the missile. Small samples are common. The Fisher Exact Probability Test can be used in this situation. The Fisher Test with Tocher's correction is the uniformly most powerful one-tailed test for differences between two proportions.
SCS Activities: Help us close the loop
Authors: Marr George R. 
Published: March 2008

SCS Activities are intended to bring growth and vitality to our organization. Activity vice presidents are Society of ficers charged with insuring the development and effec tiveness of Activities. Activities are special interest groups — as simple as that, each one a group of people organized around an idea that is of importance to simulation and of interest to the So ciety membership.
A simulation analysis of an updated version of the assigned-slot listen-before-transmission protocol
Authors: Alshammari Saud A. , Rakes Terry R. , Sen Arun 
Published: March 2008

Two situations can occur which would cause computers (or nodes) to transmit messages at the same time. In the first case, both nodes see an idle link and immediately start to send their messages. In the second case, they both see the end of a message transmitted by a third node and again begin sending simulta neously. Both of these situations result in a garbled message called a collision. Protocols, or handshaking rules between nodes, can either handle collisions after they occur and direct re-transmission, or they can schedule messages and avoid collisions. This paper updates a protocol called the assigned-slot listen- before-transmission scheme by incorporating collision detection capability and the use of message queues. A simulation model of a local area network is used to gauge the performance of this protocol and test its sensitivity to packet length, node groupings, and a range of traffic throughputs.
A PROLOG simulator for interactive flexible manufacturing systems control
Authors: Fan I.S. , Sackett P.J. 
Published: March 2008

A simulation model of an in-line Flexible Manufacturing System has been built using the declarative computer programming lan guage PROLOG. The model is a vehicle for the study of dynamic responses of Flexible Manufacturing System control. Animation of system status and powerful user interaction are essential for this application. A simple but effective structure has been formulated in PROLOG as a core kernel of the simulator. The decision making process is modelled as a set of functional queues. Partitioning of the de cision functions permits modeling of complex peer-to-peer co ordinated decision making in non-trivial control environments. This offers many advantages over traditional manufacturing simu lation systems. The authors describe appropriate strategies for the realization of acceptable computational performance while retaining the powerful benefits of the PROLOG environment. The result is a practical operational system which features an incremental de velopment upgrade path, quick prototyping, fast and clearly understood code changes.
A computer simulation model for the study of police patrol deployment
Authors: Kern Gary M. 
Published: March 2008

Simulation models have been suggested as a means of assist ing patrol administrators making deployment decisions. The simulation model reported here allows the administrator to study the performance of several complex dispatching tactics including multiple unit dis patching, preemption, and in tersector dispatching. Environmental variables, such as interarrival and service times, can be set to reflect any number of possible probability distributions. Sample reports generated by the model are presented, as is information regarding the model's verification.
Efficient simulation experiments for comparing communication network routing algorithms
Authors: Shaikh Muzaffar A. , Althouse Edwin L. 
Published: March 2008

In this paper, we propose efficient statistical designs of simulation experiments and statistical methods for systematically comparing communica tion network routing algorithms via simulation. The design of experiments technique establishes the minimum number of observations or simulation runs without losing much information needed to gain insight into the real world system. Statistical models use this efficient set of observations in providing (1) insight into the intrinsic behavior of the algorithm (i.e., sensitivity of the algorithm to changes in factors), (2) a statistical basis for com paring alternate algorithms that perform common functions, and (3) predictor equations that can be used to predict algorithm performance for the user- specified values of influencing factors. The empha sis in the paper is on the use of statistical testing and comparison methods in a simulation setting and not on the nature of algorithms themselves. These methods should pave the way for perform ance analysis of other algorithms as well. The testing environment includes a parameter- driven simulator which has the capability to modularly include alternate routing algorithms one at a time. The model generates a threat scenario which transforms into the generation of appropriate messages. The impact analysis of five influencing factors on three measures of perform ance is proposed.
Simulation of a flexible arm robot for space station applications
Authors: Janssen Paul J. , Harrand Vincent J. , Wessling Francis C. , Choudry Amar 
Published: March 2008

A Flexible Arm Robot (FAR), which could be attached to the Space Station, could be used for reaching many locations in the vicinity of the Space Station without the need for astronauts in space suits to perform extravehicu lar activity. FAR is a tube-shaped robot consisting of many stacked segments which are individually controllable. Each segment has six degrees of freedom. Because this robot has many degrees of freedom, new algorithms were needed to control it. A graphical model and a mathe matical model (direct and inverse kinematics) of FAR have been developed. Based on these two models, a software package for simulating this Flexible Arm Robot on a computer system has been made. FAR and the two models are briefly described in this paper.
A pilot study of the impact of animation on decision-making
Authors: Henz Luehrmann Monica A. , Byrkett Donald L. 
Published: March 2008

Recent years have seen the intro duction and growth of graphical animation in simulation. Animation is frequently extolled for its use as a debugging aid, as a communication aid, and as a decision aid. This paper reports on a pilot study that was undertaken to measure the impact of animation as a decision aid. Two versions of a simulation model of a flexible manufacturing system were developed; one with animation and one without. Subjects were given a problem scenario involving a design decision concerning the flexible manufactur ing system. Half were given the animated simulation model as a tool to assist in the design decision and half were given the nonanimated simulation model. The assignment of subjects to type of simulation model was made randomly. The results of the experiment are presented in terms of five variables: decision quality, decision speed, task performance, problem comprehen sion, and viewer preference. Based on this pilot study, suggestions are made for improving the experimen tal design of future studies.
A real-time distributed simulation of PBX with software reuse
Authors: Chang Carl K. , Chang Young-Fu , Aoyama Mikio 
Published: March 2008

Rapid prototyping has proven to be a promising way of accomplish ing a feasibility study. It cuts costs and reduces the complexity of the development of real-time distributed systems. UICPBX is a simulator of Private Branch eXchange (PBX), an important member in the family of telephone switching systems. It has been prototyped using the C language in a SUN workstation environment under UNIX. During the development of UICPBX, techniques of software reusability have been applied. First, a software hierarchy with three layers (kernel, basic supp orting and calling functions) is employed according to the functional charac teristics of the application system. Secondly, a software library is established to provide an effective environment to support reuse of functions developed at the middle (basic supporting) layer of the software hierarchy. The powerful high-resolution, bit-mapped graphic screen of SUN workstations facilitates effective process monitor ing and visualization of multiple real-time tasks.
Optimal dynamic scheduling of a power generation system to satisfy multiple criteria
Authors: Forouzbakhsh Farshid , Deiters Robert M. , Kermanshahi Bahman S. 
Published: March 2008

A computer algorithm for the optimal scheduling of generators in a power system is presented and tested. The algorithm, based on goal programming, automatically and dynami cally schedules the output of each generator in the system for optimal operation. The optimal operation can take into consideration multiple objectives such as economy, security, and reduction of pollution as well as practical constraints. To validate and test the algorithm, an example system of 5 generators, 10 busses, and 11 transmission lines is optimized for two objec tives: minimal generation cost and minimal emission of nitrous oxides (NOx). Hourly changes in total power demand in the range of 90% to 110% are considered together with a constraint of maximum permissible total NOx emission. Other practical equality and inequality constraints are incorporated into the optimiza tion algorithm. The simulation results demonstrate that the outputs of the generators can be changed smoothly and dynamically. Furthermore, using the algorithm, computer control is practicable either by direct on-line optimization or by using the feasible operation region generated as a small data-base by off-line computation.
Simulating management's earnings-per-share forecasts
Authors: Cameron Alex B. 
Published: March 2008

This study attempts to simulate management's earnings per-share forecasts using six naive time series models. The results indicate two (random walk and random walk with a drift) of the six models were significantly more accurate than the other four models in simulating management's earnings forecast. Both exhibited a tendency to consistently underforecast earnings, and it was hypoth esized that this could be due to an inherent bias in the data. The results for the remainingfour models were not as favorable. The two submartingales and the simple linear trend models exhibited a high degree of variability in accuracy and significant biases based on the magnitude of the forecast. The arithmetic average model appeared to be unbiased but exhibited a high degree of variability. The results of the study indicate that it may be possible to simulate management's earnings forecasts using relatively naive mathemati cal models.
SCS Industry Technology Award Presented at Duke-EPRI Mobile Simulator Dedication Ceremony
Authors: Sharon Ariel 
Published: March 2008

On The Road To Excellence: Operating excellence is essential if utilities are to successfully meet the challenge of an increasingly competitive future. Operators must have the knowledge and skills to operate plants with perfection. Replica simulators have been used to train nuclear power plant operators for over 15 years. However, high cost and lack of flexibility have limited the use of simulators by the fossil generation industry. The Duke-EPRI Mobile Simulator represents a breakthrough in cost and flexibility which makes near-replica simulators affordable, compact and mobile. Duke Power Company, the Electric Power Research Institute, TRAX Corporation, and Westinghouse Electric Corporation teamed to produce a trailer-mounted simulator that includes a complete Westinghouse control system "simulated" by a process model developed by TRAX Corporation. The simulator can be loaded with different control systems and process models to provide near-replica training at various plants. Duke power will use the mobile simulator to provide operator training and controls engineering for all of its fossil plants, yielding estimated benefits of over $175 million during the next 15 years. The benefits will be realized in the areas of reduced operator preventable trips, reduced commissioning time for control system replacements, quicker start ups, and improved maneuvering capability.
Knowledge Based Simulation Systems - A Review
Authors: Merkuryeva Galina V. , Merkuryev Yury A. 
Published: March 2008

The paper presents a review in the field of knowledge based simulation systems (KBSS). Development and application of such systems allow the user to perform simulation studies without special training in programming languages, simulation theory, and other skills related to simulation project realization. KBSS architecture, programming paradigms and development tools are considered. Problem areas and characteristics of the main applications of KBSS are described. More than 50 examples of research and commercial systems are given in the tables. Quality assurance techniques which may be used in KBSS are considered. They support tools for model reduction and parallel processing techniques. The perspectives for KBSS development are discussed. Among them are support of both on-line digital control, simulation modelling and data base management, development of parallel and distributed systems, fuzzy simulation environment development, combination of the expert system capabilities with potential for adaptation by artificial neural nets. Bibliography includes 168 references.
The Sampling of Domestic Wool for Shrinkage Determination
Authors: Burns Robert H. 
Published: March 2008

The terms shrinkage, yield, and clean content are de fined. The methods of obtaining shrinkages on lots of wool are explained. The research work completed with wool shrinkage tests in the past is reviewed. The method of selecting the sub-lot and the samples from the sub-lot is described, and the methods of scouring at the laboratory and the mill are explained. The shrink ages of the small samples are compared with those of the sub-lot and the entire lot. The grading and sorting of the sub-lots are compared with that of the entire lots. The grading of 10 bags, of five bags, and of every nth fleece is compared to that of an entire clip. The grading of the first bag sheared from each band is found usually to be coarser than that of the last bag sheared from each band, and the cause is explained. Figures are given for the percentage of grease in the scoured wool. The variations in shrinkage of samples drawn by different operators, and between the first and fourth samples drawn are given, and are found not to be significant.
Some Mechanical Factors Influencing Size Application
Authors: Yelland William E. 
Published: March 2008

Results presented in this article indicate that (1) at higher slashing speeds warps of 150 denier 40 filament bright viscose pick up less size than at lower speeds when the warp is completely im mersed in the size mix by means of an immersion roll. (2) The use of a blanket on the squeeze roll (or of fewer weights on the squeeze roll) causes more size to be taken up by the warp than when the squeeze roll is bare. No difference in size dis tribution on the yarn was detected in this case. The use of a blanket on the squeeze roll also increases the drying requirements of the warp.
Factors Influencing Flocculation and Precipitation. Influence of Initial Particle Size
Authors: Beavers Ellington M. , Magoffin James E. , Cameron Frank K. 
Published: March 2008

It has been found that the following properties of flocculated suspensions of bentonite are dependent upon initial degree of dis persion : (a) the shape and form of the floc produced; and conse quently, (b). the rate of settling of the dispersed phase through a given distance; (c) the extent to which the particle charge is low ered by a fixed amount of coagulating agent; (d) the adsorbability and solubility effect. A general equation has been developed for the type of "com pression settling" observed here, which has been shown to be ap plicable to these data. Some of the physical properties of the suspending media have been studied, and it has been suggested that still other variable factors (possibly changes of surface phase), which should be in vestigated, have an integral part in the flooculation process. The various factors studied are discussed as to their influence on flocculation, and previously observed sedimentation behavior of similar suspensions is explainable on the basis of the conclusions drawn.