bluuebunny/crossref_metadata_2025 huggingface dataset:
Vocational Training in France and Britain: the Building Trades
Authors: Prais S.J. , Steedman Hilary
Published: March 2007

The emphasis placed in Germany on vocational training and education was explored in previous studies by the Institute. These drew attention to: the greater numbers with vocational qualifications there than in Britain; the generally broader scope of German training, leading to greater adaptability in the face of technological progress; more extensive preparation at school for subsequent training; and the consequences for productivity (see National Institute Economic Review, August 1983 and February and May 1985). This article presents the first of a series of similar comparisons for France and Britain, with particular attention to French full-time vocational secondary schools for 14-17 year olds.
Labour Costs in Manufacturing
Authors: Ray G.F.
Published: March 2007

Comparative industrial labour costs have been analysed in three previous articles contained in earlier issues of this Review. Each time the analyses were based on the same Swedish publication, which contains hourly wages, social charges and total labour costs for most of the OECD countries, and converts them into a common currency using official exchange rates. This provides an acceptable starting point for international comparison since the products of manufacturing industries compete on international markets on the basis of these exchange rates.
The Decline of Primary Producer Power
Authors: Ray G.F.
Published: March 2007

The middle years of this decade will go down in economic history as a period when primary products hit rock bottom, whatever method is used to illustrate their real value or purchasing power. There have been hardly any exceptions to this general decline. Petroleum (by far the most important primary product), foodstuffs, agricultural industrial materials, minerals and metals all shared the same fate, though the extent of their losses differed. The only exception has been coffee, owing to unusually adverse weather conditions.
Modelling the Behaviour of Export Volumes of Manufactures: an Evaluation of the Performance of Different Measures of International Competitiveness
Authors: Anderton R. , Dunnett A.
Published: March 2007

The objective of this note is to compare the econometric performance of several different equations which attempt to model the behaviour of export volumes of manufactured goods. Such equations usually explain export volumes in terms of an index of world economic activity and an index of competitiveness. This note concentrates on the issue of competitiveness; namely, how should competitiveness be defined and measured when employed in an export volumes equation?
New Measures of British Service Outputs
Authors: Smith A.D.
Published: March 2007

Official statistics suggest that over the last two decades the commercial service sector has grown rapidly both in absolute terms and relative to the rest of the British economy. Given the importance of service activities, and the fact that many of them are notoriously difficult to quantify, it is desirable that the reliability of service output measures be subject to scrutiny and, where possible, improvement. Accordingly this article presents some alternative output measures which have been compiled for financial, recreational and catering services, and compares the picture which emerges, for the economy as a whole and for individual service industries, with, that portrayed by official data.
Productivity Levels in British and German Manufacturing Industry
Authors: O'Mahony Mary
Published: March 2007

Relative levels of labour productivity are estimated to have been about 22 per cent higher in German than in British manufacturing in 1987. The German productivity advantage was most pronounced in non-electrical engineering, vehicles and metals. The British performance was relatively better in food, drink and tobacco and textiles and productivity levels appear to be about equal in the two countries in chemicals and electrical engineering. About 80 per cent of the productivity gap in aggregate manufacturing can be accounted for by differences in the levels of both physical and human capital. The aggregate productivity ratio of 22 per cent is lower than that found for 1968. The time pattern of relative productivity in the intervening two decades shows a considerable increase in the 1970s followed by a rapid narrowing of the productivity gap in the 1980s.
Supply Side Reform and UK Economic Growth: What Happened To The Miracle?
Authors: Oulton Nicholas
Published: March 2007

Two institutions have retarded UK productivity growth in the post-war period: industrial relations and education. The failings of both were largely addressed in the 1980s. The productivity improvement of the 1980s was genuine and was largely due to the reduction in union power brought about by the trade union legislation of the 1980s. The 1980s and 1990s have also seen large falls in the proportion of the labour force which is unqualified and rises in enrolment rates in further and higher education, changes which tend to increase long-run growth. But two factors have obscured the extent o f the improvement. First, the whole climate for economic growth is less favourable than it was in the so-called Golden Age prior to the first oil shock in 1973. Second, UK macroeconomic policy compares poorly with other OECD countries: booms have been shorter and recessions longer, so that microeconomic success has been masked by macroeconomic failure.
Closing The UK Competitiveness Gap
Authors: Eltis Walter , Higham David
Published: March 2007

This paper is developed from the presentation given by Walter Eltis at the National Institute's seminar ‘Industrial Productivity and Competitiveness' held in London on 23 May 1995. It sets out the approach underlying the UK Government's 1994 and 1995 White Papers on competitiveness and begins by reviewing the debate on the meaning of national competitiveness. The White Papers define competitiveness as the ability to raise living standards and argue that, contrary to the views of some leading economists, competitiveness is a useful guide to policy because of the emphasis on national benchmarking. It then explains that the analytical basis of the Government's approach—which identifies ten key influences on competitiveness—lies in the theoretical and empirical analysis of economic growth (including ‘new’ growth theory) and on detailed studies of the sources of productivity differences across countries. Finally, it considers the role of privatisation, inward investment, the growth of small firms and labour market policies in improving UK performance. The paper concludes that, although three quarters of the productivity gap with French and Germany industry appears to have been closed since 1979, productivity in both manufacturing and services still lags behind those in the leading West European countries.
The BAH Particle in Brunei English
Authors: Conrad A. , Ozòg K. , Martin Peter W.
Published: March 2007

The variety of English used in Negara Brunei Darussalam is largely unresearched. It has similarities with other Southeast Asian varieties, most noticeably Singapore and Malaysia, but there are im portant differences. One such difference is the particle bah, which we recognise as one of the salient features of Brunei English. In order to understand the particle it is important to look at its use in both Brunei Malay and in the local variety of English. The literature on particles in Singapore and Malaysian Englishes, as well as the limited literature on bah in Malay is reviewed. An analysis of the particle is attempted based on data collected from spontaneous speech, tape- recordings, questionnaires and informant comment. While a discus sion of the syntactic behaviour of bah is deemed necessary, pro minence is given to a discussion of its functional behaviour. We con clude that the particle is extremely versatile and very different in most aspects to the la/lah of Singapore and Malaysia. A further con clusion is that the use of bah plays an important role in signifying membership of the Brunei speech community.
Perspectives on Cultural and Individual Determinants of Teaching Style
Authors: Kennedy Judith
Published: March 2007

Douglas Barnes and Denis Schemilt (1974) have distinguished between 'Transmission and Interpretation' Teachers. It may be that this distinction (assuming that we accept it) has its origins in an indi vidual's sense of autonomy or 'locus of control' (Rotter 1965) which may, in turn, be culturally determined. The concept of locus of con trol refers to the extent to which an individual sees his behaviour as being initiated by factors within himself (an internal locus of control), or how far he sees it as determined by external forces (an external locus of control).

In order to investigate any possible relationship between a teacher's or individual's position on the Transmission-Interpretation dimension, his locus of control and culture, a pilot study was con ducted by means of a questionnaire with two groups of undergraduate (B.Ed.) students - one group from Malaysia and one from the UK.

Implications of the results for teacher education and the in troduction of new methodologies are discussed.
A new line of high-accuracy computing elements based on modern semiconductor technology by
Authors: Giloi W.K. , Waldschmidt K.
Published: March 2007

The computing elements for nonlinear operations presented in this paper are a combination of analog and digital components which combine the advantages of both techniques: large bandwidth and continuous representation of variables provided by analog techniques with accuracy and stability provided by digital techniques. The basic principle underlying these elements is to approximate functions by an appropriate power series, leading to a segmentation technique in which break-point values are calculated at high accuracy by operational digital-to-analog converters, while an interpolating increment is generated by medium-precision analog components.

A whole family of high-precision multipliers, dividers, resolvers, and digitally settable function generators based on this principle will be described, as will the standard modules of which these computing elements are composed. Measured accuracies and bandwidths will be given. The new devices have good thermal stability.
Solving stiff differential equations in the simulation of physical systems
Authors: Bui Tien D.
Published: March 2007

Computer simulation of dynamic systems often requires the solution of a set of stiff ordinary differential equations. The solution involves the eigenvalues of the Jacobian matrix. The greater the spread in eigenvalues, the more time-consuming the solutions become if one uses standard numerical techniques. In many cases, the differential equations are so stiff that accurate numerical solutions are unecon omic. In this paper we propose new techniques for solving stiff differential equations. These algo rithms are based on implicit Runge-Kutta procedures with complete error estimates. Experiments show that the new techniques are superior to Gear's method for solving mathematical models for real sys tems in chemical engineering, biology, and laser kinetics.
Can a Shorter Workweek Reduce Unemployment?
Authors: Henize John
Published: March 2007

A simulation model of the West German economy is being used to evaluate alternative policies for attacking the unemployment problem by reducing normal working hours. This paper reports the analysis of five policies to assess their effect on unemployment, on finances, on inflation, and on the overall economy of the country.

The model includes feedback paths that have been neglected in much of the current literature, and it has yielded many surprising results. One is that a 5% reduction of the workweek would have little effect on real aggregate demand for goods and services, whether or not workers were compensated fully for the reduction in hours. Simulation results were that such a reduction in hours increased employment 3.6% if hourly pay remained unchanged and 4.4% if workers were compensated for lost wages. Not sur prisingly, the latter alternative was the more in flationary of the two. A 2.5% annual reduction in working hours was very effective in reducing unemployment.

The paper goes on to discuss deficiencies in economic theory, their relation to modeling, and practical problems in forecasting. It concludes with observa tions on the role of simulation in establishing public policy.
A Second-Generation Model of Timber Harvesting
Authors: Hines Gail S. , Webster Dennis B. , Goulet Daniel V. , Sirois Donald L.
Published: March 2007

Increased demand for wood and wood products coupled with changes in timber harvesting systems in the Southeastern United States from a labor-intensive to a more costly, almost totally mechanized opera tion requires optimal use of harvesting equipment. Simulation can provide an inexpensive tool for evaluating harvesting procedures or use of new equipment.

Existing harvesting simulation models were evaluated and found to be insufficiently documented and diffi cult for one lacking computer experience to use. No consensus of what constitutes the essential elements of a model exists.

This paper presents the design criteria for a new second-generation model that will be modular, user- oriented, and uniform in the level of detail it provides.
Interactive simulation on a microcomputer
Authors: Ellison David , Herschdorfer Irma , Wilson Jean Tunnicliffe
Published: March 2007

The Apple II microcomputer provides powerful facili ties for the writing and execution of both discrete and continuous simulations. Interactive BASIC allows rapid development of new models, while color graphics provides results that are easy to analyze. Came paddles can allow the user to change parameters and control the simulation as it runs. Two new simula tion executives allow both the modeler and the user ready access to the facilities of the computer and the simulation, while preventing the user from making unreasonable or impossible changes. Despite its limited language facilities and relatively low speed, the microcomputer has obvious advantages in user inter action, model development, optimization, and analysis and presentation of results. Many of the microcom puter's limitations, furthermore, will soon disappear as more powerful languages and faster processors become available.
Applying software engineering to simulation
Authors: Sheppard Sallie
Published: March 2007

Software engineering is a collection of techniques for developing and maintaining large programs. New techniques are necessary because techniques that work for small programs are inadequate for designing, coding, testing, and maintaining large systems. Although some software engineering techniques require special computerized tools, many are easy to apply and can be used by simulationists working in any environment. In particular, simula tionists can take advantage of chief programmer teams, structured walkthroughs, structured analysis and design, software develop ment systems, structured programming, standardized coding con ventions, and top-down testing.
RSMM: A network language for modeling pollutants in river systems
Authors: Rao Narasinga B. , Standridge Charles R. , Schnoor Jerald L.
Published: March 2007

Predicting the steady state distribution of pollutants in rivers is important for water quality managers. A new simulation lan guage, the River System Modeling Methodology (RSMM), helps users construct simulation models for analyzing river pollution. In RSMM, a network of nodes and branches represents a river system. Nodes represent elements such as junctions, dams, withdrawals, and pollutant sources; branches represent homo geneous river segments, or reaches.

The RSMM processor is a GASP V program. Models can employ either the embedded Streeter-Phelps equations or user supplied equations. The user describes the network diagram with GASP- like input cards.

RSMM outputs may be printed or stored in an SDL™* database. An interface between SDL and DISSPLA provides high quality graphical output.
SNAP/SOS: A package for simulating and analyzing safeguards systems
Authors: Grant Floyd H. , Polito Joseph , Sabuda Jerome
Published: March 2007

The effective analysis of safeguards systems at nuclear facilities requires significant effort. The Safeguards Network Analysis Pro cedure (SNAP) and the SNAP Operating System (SOS) reduce that effort to a manageable level. SNAP provides a detailed analysis of site safeguards for tactical evaluation. SOS helps the analyst organize and manage the SNAP effort effectively. SOS provides a database for model storage, automatic model genera tion, and computer graphics. The SOS/SNAP combination is a working example of a simulation system including executive- level control, database system, and facilities for model creation, editing, and output analysis.
Implementing a portable FORTRAN Uniform (0,1) generator
Authors: Marse Ken , Roberts Stephen D.
Published: March 2007

The implementation and testing of a portable FORTRAN routine is described which utilizes a well-known random number generator to produce Uniform (0,1) values. The implementa tion techniques illustrate the advantages of a well-tested por table algorithm and expose some problems which commonly occur in the generation of Uniform (0, 1) numbers for applica tion areas such as simulation. These problems include the pit falls of using machine-dependent random number generators with unknown characteristics typically supplied with computer system software. The excellent global statistical properties of the generator used in this routine are documented and local testing of the Uniform (0,1) values produced is provided. An additional routine is described which enables the user to obtain indepen dent streams of values. Fifteen streams are rated for their per formance on uniformity and independence tests. The provid ed seed values enable the user to select streams with the desired properties for a particular application.
Chip level modeling and simulation
Authors: Armstrong James R.
Published: March 2007

An approach to the modeling of LSI devices at the chip level is described. The complexity of these devices requires that higher level modeling techniques be developed. However, it is impor tant to preserve as much model accuracy as possible when developing high level models. In the approach described here, the chip level models are used to simulate not only device microoperations and internal memory, but also detailed inter face timing requirements. Modeling of such interface timing specifications as set up time, hold time, and minimum pulse width are possible. A modeling example is presented. Opera tion of the complete simulator is described. Two research ap plications of chip level modeling are discussed and an evalua tion of this approach to modeling and simulation is given.
Simulation based design of hydraulic servo-controlled apparatus for damping measurement
Authors: Foster Colin G. , Hooker Robert J.
Published: March 2007

An apparatus for the measurement of damping properties of materials under biaxial stress conditions utilizes three electro- hydraulic servo-systems to apply fluctuating internal, external, and axial pressures to a hollow cylindrical specimen. The ar rangement imposes difficulties with respect to specimen loading, system interactions, stability and control. An analog simulation was conducted as a direct step in the design procedure in order to prove the feasibility of the apparatus, to provide guidance in the choice of design parameters, and to investigate system operating conditions and procedures.

The simulation and its use with respect to both design and opera tion of the apparatus are described. In the simulation, account is taken of servo-valve characteristics, fluid leakage paths, specimen deflection, chamber volumes, and fluid compressibil ity. The (successful) performance of the apparatus as built is also described, and the similarity of simulated and actual behaviour is apparent.
Microcomputer implementation of simulation benchmarks in heat-transfer and dynamic process analysis
Authors: Jacques Michael St.
Published: March 2007

In order to foster a better understanding of realistic microcom puter capability, a diverse group of mathematical models, writ ten in FORTRAN, are considered from the standpoint of run ning efficiency. Benchmark results are reported for a variety of computer systems including a mainframe, two minicomputers, and two microcomputers.

A description of the simulations, which cover a wide range of complexity, is included. One of the models is a dynamic, two- component material balance of a paper machine. Eleven variable level chests (tanks), a number of intricate controls, and about one hundred stream equations make this model comprehen sive enough to be generally associated with a mainframe, or with very powerful minicomputer systems. Another dynamic simula tion emulates the thermal and stress behavior of flat, injection- molded parts during cooling. It is representative of models based on the one-dimensional, transient heat-conduction equation. Also considered is a steady-state, finite-difference model for prediction of temperature profiles in shell and tube heat ex changers. This simulation employs an efficient, sparse-matrix technique similar to equation solution methods found in finite- element software. Other less comprehensive models, often used as subroutines in process analysis and control, are examined. These include a pump curve versus system resistance search, and a control valve position versus flow computation. Both of these subroutines use iterative solution techniques.

The advantages and disadvantages of using the microcomputer are discussed. A range of bounds is established on the feasibil ity of implementing and using a model on a microcomputer in terms of real simulations and run times. The results of this work are very encouraging and indicate a definite place for the microcomputer in simulation work.
Simulation modeling for hospital bed planning
Authors: Dumas M. Barry
Published: March 2007

A computer simulation model was developed to address the problem of allocating beds to hospital services, by bed type and sex. The model, written in Simscript II.5, was designed to per mit experimentation with and evaluation of bed usage policies and admissions rules as well as allocation plans.

Using the model, hospital beds at the Mount Sinai Medical Center, New York City, were reallocated. Incorporated in this reallocation was the creation of a new service. Also developed was a revised elective admissions reservation board. An altered view of measures of performance was another outcome.

Discussion in this paper will center around the allocation prob lem, the simulation model, the performance measures, the hos pital configurations, the experiments and the results obtained.
A practical methodology for ambulance location
Authors: Uyeno Dean H. , Seeberg C.
Published: March 2007

An ambulance location system was created for the British Co lumbia Provincial Ambulance Service. It was applied in the Capital Regional District (an area of about 937 square miles). The system helps administrators locate ambulances to improve response to calls.

The system consists of three parts: a means to reduce data to manageable proportions, a P-Median model for the determina tion of rough locations, and a computer simulation model for fine tuning of locations. The system worked well. The method of data reduction proved both practical and efficient. The rough locations provided by the P-Median model provided an excellent starting solution. The simulation model was shown to be ac curate in comparison with actual Capital Regional District data. The model was used with confidence to do a number of useful experiments concerning optimal ambulance locations and system response to changes in demand levels.

The validated system was used to answer many "what if" ques tions such as those that follow:

Are vehicles located in the best manner?

If we move one unit to reduce complaints from area A, how will this affect service in area B?

If we get more units, should we locate them incremen tally or would it be better to relocate all bases?

How much can we hedge against expected future demands?

How should we space shifts?

How should we determine the number of crews per shift?
Modeling the USA-USSR arms race
Authors: Don Ward Michael
Published: March 2007

A continuous time simulation model of the arms expenditures and arms stockpiles of the Soviet Union (USSR) and the United States (US) from 1951 through 1978 is developed in this article. This model suggests that contemporary superpowers react primarily to comparisons between their weapons stockpiles and those of their perceived opponents, rather than to the military budgets of their perceived opponents. The parameters for this model - which is developed in a system of ordinary differen tial equations - have been estimated by coupling a nonlinear least squares minimization algorithm, NL2SOL, with the solu tion trajectories of the differential equation system. The predic tions of the model are quite close to the actual data series, with standard errors of the estimates for each individual equation being quite small. In contrast to some public opinion and con siderable scholarly research, the results provide strong confirma tion for the proposition that there is a current arms race between the US and the USSR. The US and the USSR each try to achieve or maintain a lead over the other in the stock of weapons- both the conventional and strategic - which each possesses. Stability analysis of the systems of equations suggests that the system may require approximately 3,000 years to return to the steady state, once it had been pushed off the stability trajectories.
The Simulation of Logical Networks (SLN)
Authors: Roberts Stephen D. , Klein Robert W.
Published: March 2007

SLN (Simulation of Logical Networks) is a new simulation language designed specifically to provide concepts and facilities needed to model and simulate logical networks. Logical networks provide a convenient and natural means of expressing decision processes when a general-purpose discrete-event simulation facil ity is unnecessary. SLN accepts a node and branch description of a logical network and automatically handles the construction and execution of the simulation. FORTRAN can be mixed with the SLN statements with few restrictions. SLN is highly efficient, simulating only logical networks and working as a preprocessor generating FORTRAN source which can be compiled, linked, and executed. The SLN library includes facilities for generating random variates, collecting and reporting statistics, monitoring simulation execution, and tailoring the simulation output. SLN is portable and designed for use in an environment lacking a modeling tradition.
A new method for the computation of digital filter coefficients - Part II
Authors: Forsythe William
Published: March 2007

This is the second part of a two-part paper which describes a new method for computing the coefficients of a digital algorithm designed to emulate the performance of any given continuous transfer function. It is based upon the Taylor series expansion, is easily applied, and is shown to have considerable advantages over the use of the bilinear transform with which it is compared in a number of examples.
Adaptive perturbation control with feedforward compensation for robot manipulators
Authors: Lee C. S. George , Myung Jin Chung
Published: March 2007

An adaptive perturbation control can track a time-based joint trajectory as closely as possible for all times over a wide range of manipulator motion and payloads. The adaptive control is based on the linearized perturbation equations in the vicinity of a nominal trajectory. The highly coupled nonlinear dynamic equations of a manipulator are expanded in the vicinity of a nominal trajectory to obtain the perturbation equations. The controlled system is characterized by feedforward and feedback components which can be computed separately and simulta neously. Given the joint trajectory set points, the feedforward component computes the corresponding nominal torques from the Newton-Euler equations of motion to compensate for all the interactions between joints. The feedback component, consisting of recursive least square identification and an optimal adaptive self-tuning control algorithm for the linearized system, computes the perturbation torques which reduce the position and veloc ity errors of the manipulator along the nominal trajectory. Because of the parallel structure, computations of the adaptive control may be implemented in low-cost microprocessors. This adaptive control strategy reduces the manipulator control prob lem from a nonlinear control to controlling a linear control system about a desired trajectory. Computer simulation results demonstrated its applicability to a three-joint PUMA robot arm.
Developing generalized reactor modules for a process simulator
Authors: Upadhye R.S. , Anselmo K.J. , Schiesser W.E.
Published: March 2007

Reactors, essential in chemical process simulation, are complex equipment characterized by simultaneous heat, mass and momentum transfer, and by chemical reactions. Traditionally, reactors have been modeled on an individual basis determined by the reactor type and the application. A process simulator, however, requires complete reactor capabilities; the classical ap proach leads to a bewildering array of special reactor unit modules both expensive to develop and to maintain.

Consequently, the authors have developed the concept of generalized reactor modules; this paper presents the concept and a methodology for implementing it. Conceptually, reactor simulation is divided into six parts: equipment, stoichiometry, kinetics, data, mathematical software and executive routine. The conservation and equilibrium relationships are built into the equipment modules; system stoichiometry and reaction kinetics are user defined; kinetic parameter data are either input by the user or can be read from a user-specified kinetic data file; quality mathematical software from commerically available packages is used to solve the model equations; and the executive routine puts all these pieces together, manages the calculations scheme, and outputs the desired results. Carberry' and Levenspiel2 discuss models for various reactor types as well as the reaction kinetics needed in these models; they also address the important issue of how these idealized models can be used to simulate real reactors.

This approach has been applied in developing several reactor modules for a process simulator. These include steady state CSTR, plug flow, and dispersion reactors and a transient tubular dispersion reactor with continuous catalyst deactivation. Research and process engineers use these modules to simulate reactors with arbitrary stoichiometry, kinetics and kinetic data.

An important feature of all these modules is that quality, commercially available software was used wherever possible. This allowed more time to be devoted to model formulation and user support and to quickly develop very sophisticated modules which are easily maintained.
On the interpretation of variables
Authors: Kleijnen Jack P. C.
Published: March 2007

Correct usage is discussed for concepts and terminology in various types of models, namely simulation, regression, and user's mental models. Therefore, a strict distinction is made between variables and parameters; also, different measurement scales are distinguished. Relationships with validation, risk analysis, sen sitivity analysis, optimization and control are investigated.
A disaggregate population model of China
Authors: Qifan Wang  , Sterman John D.
Published: March 2007

A disaggregate population model of China is presented: the age structure is represented by one-year cohorts; urban and rural populations are distinguished; birth and death rates, family size, life expectancy, and other demographic variables are determined endogenously. The model can be used to analyze population problems and to project population size, the age structure, the adult labor force, the elderly population, and so on. The model can be used in two modes: to project the consequences of various exogenous fertility levels and to determine endogenously birth rates and fertility by economic inputs such as food supply, GDP, and services. Socioeconomic factors important in the demo graphic transition are incorporated into the model, such as the effect of perceived life expectancy on fertility, the effects of tradi tional values, and the ability of government to influence family fertility choices. Policies and programs designed to control population growth, such as delayed marriage age, improved con traception, and restrictions on family size can be evaluated.

Required inputs are industrial, service, and food output per worker, and also the level of pollution. The model should be thought of as a component of a comprehensive planning model which generates these inputs endogenously.

Based on the system dynamics approach to modeling complex systems, the model is implemented in the DYNAMO simulation language.
Discrete-event simulation of load point interruptions
Authors: Fong C.C.
Published: March 2007

A discrete-event simulation system has been created for obtain ing probability distributions of load point reliability indices in an electricity supply system. The modeled behavior of transmis sion components includes temporary and permanent faults, com mon mode faults, maintenance, switching after permanent fault, breaker failure to open, closing of normally opened breakers, and fluctuating weather environment. Also, the simulation system can study the effect of parameter uncertainty when there is limited component outage data or weather data.
Selecting random number seeds in practice
Authors: Kleijnen Jack P. C.
Published: March 2007

A pseudorandom number generator, such as a multiplicative con gruential generator, depends on its initial value or seed. The com puter may select a seed using its internal clock. Alternatively the simulation analyst may use Fishman's tables with seeds spaced 100 000 apart. Theoretically, the concepts of sampling with and without replacement are involved. Practical problems arise if con secutive simulation runs cannot be made in a single terminal session. The user may select the simplest option. Runs for dif ferent systems may use common seeds to decrease the variability; then the internal clock is an impractical source since its inter nal (binary) representation must be saved.
A distributed parameter system simulator
Authors: Aaltonen Matti , Tanttu Juha T. , Pohjolainen Seppo A.
Published: March 2007

A simple and easy-to-use computer simulator (TDP) t for distrib uted parameter systems is presented. The simulator is based on commercially available TWODEPEP (a partial differential equa tion solver), to which measurement and control software mod ules have been added. The possibility to speed up computation with an attached processor is discussed. Finally, two simulation examples are presented.
Production based language simulation of Petri nets
Authors: Bauman Ron , Turano Tom A.
Published: March 2007

Petri net models are often of limited usefulness because the sys tems they represent are too complex to be represented in a clear manner. By using a Production Based Language simulation, the number of elements that must be explicitly drawn in the net diagram can be greatly reduced. A simulation such as this sim plifies the net without compromising the integrity of the model itself. This is demonstrated here by the OPS5 Production Based Language simulation of a communications protocol Petri net. Using this simulation and an error generator, an automated method of testing the protocol is shown.
CORTISIM: A complex dynamical model of the cortisol regulation system
Authors: Abraham Ralph H. , Garfinkel Alan
Published: March 2007

The concept of complex dynamical systems is an outgrowth of the mathematical theory of nonlinear dynamical systems, devel oped in the context of physiological modeling. This paper de scribes an exemplary application of this new modeling strategy to the cortisol regulation system, along with some preliminary results of its simulation. The eventual intent of this project is the creation of a research tool for endocrine physiology.
Simulation of nonlinear distributed parameter systems on the connection machine
Authors: Kogan Boris Y. , Karplus Walter J. , Pang Alex T.
Published: March 2007

The recently introduced Connection Machine, CM-2, is a multiprocessor with massive parallelism. Fully expanded, the CM-2 consists of 64K processing elements connected in a hypercube topology. Each processing element contains a single-bit arithmetic and logic unit as well as up to 256K bits of local memory. Operation is in the SIMD mode with a single control unit controlling all the processors. In this paper the application of a quarter CM-2 (16K processing elements) to the simulation of excitable media is described. Excitable media are distributed parameter systems, charac terized by nonlinear partial differential equations, containing distributed sources of energy. Excitable media arise in biological systems (e.g. heart muscles), chemical processes and a variety of other application areas. The implementation of a mathematical model for the heart muscle on the CM-2 permitted the generation of very interesting computational results.
The Identification and Estimation of Phenolic Fungicides in Mildewproof Materials
Authors: Hilton Clifford L.
Published: March 2007

An ultraviolet spectrophotometric method has been developed for the analysis of many of the commercial phenolic fungicides. Accuracy and precision of ± 3% have been obtained. The ultraviolet absorption spectra of twelve compounds (thirty commercial fungicides) have been included.
Mechanics of Elastic Performance of Textile Materials
Authors: Platt Milton M. , Klein William G. , Hamburger Walter J.
Published: March 2007

Theoretical analyses are given of the effects of fiber properties and yarn structure on singles yarn bending rigidity, assuming the fibers to be elastically isotropic and to exhibit linear stress—strain behavior. The two extreme cases of complete freedom and no freedom of relative fiber motion are analyzed.

The effects on yarn rigidity of fiber dimensions, fiber stiffness, torsional to bending rigidity ratio, yarn density, size, twist, fiber clustering, and prior relaxation treatments are analytically investigated.

1. Where freedom of fiber motion prevails, yarn rigidity is equal to the sum of fiber bending rigidities geometrically modified by yarn twist in a manner such that twist increases produce decreases in yarn rigidity.

2. For most practical yarns, residual torsional stresses produce only a minor influence (increase) in yarn rigidity.

3. Relaxation of twisting stresses prior to yarn bending alters very slightly the effects of yarn twist on rigidity. Conaequently only changes in fiber modulus produced by relaxation are of significance.

4. Fiber clustering, i.e., the aggregate action of groups of fibers, produces marked increases in yarn rigidity, roughly proportional to the number of fibers per cluster.

5. The extreme case of fiber clustering, i.e., no freedom of relative fiber motion, results in rigidity of the order of the number of fibers in the yarn divided by the yarn packing factor times the rigidity obtained when freedom of motion prevails. The rigidity of blended yarns is discussed, and the interaction of gross yarn structure, properties of the fibers being blended, and their spatial distributions qualitatively analyzed.

1. For a uniform blend distribution, total rigidity is determined from the summative rigidities of the fibers, modified by yarn twist to the same proportionate extent as is a self-fiber yarn.

2. Location of fibers in a nonuniform blend determines not only the yarn rigidity but also its variation with twist. Generally, when stiffer fibers predominate in the core of the yarn, less rapid decreases in rigidity with twist increases take place than in a uniform blend ; the converse is true when the stiffer fibers are present in the yarn sheath.

3. Changes in fiber location resulting from twist or blend changes can significantly affect yarn rigidity.
Physical Properties of Wool Fibers at Various Regains
Authors: Haly A.R. , Feughelman M.
Published: March 2007

The paper reports determinations of stress changes which take place in wool fibers held at constant extension of 1.5 or 10% and subjected to various relative humidity changes. Stresses may be very different according as equilibrium at a given relative humidity is approached by absorption or desorption of water by the fiber. At 1.5% strain, when approach was by absorption, for all relative humidities used the stress fell to a level lower than when the fiber was in water and then increased. A qualitative explanation is given in terms of changes analogous to sol-gel transformations.
Some Theoretical Considerations of Cellulose Cross-Linking
Authors: Garden John L. , Steele Richard
Published: March 2007

Much available chemical evidence supports the hypothesis that covalent cross-linking is the best way to improve the resilience of cellulosic fabrics. This paper reviews the theories relating physical properties to cross-linking in rubbery polymers and shows that they apply in some qualitative aspects to cellulose. Particularly, the observed changes in swelling, solubility, modulus, tensile strength, and resilience are consistent with these theories.

On the basis of published data, the concentration of intermolecular cross links is esti mated ; it is found that at least every twenty-fifth accessible anhydroglucose unit has to be intermolecularly cross-linked when maximum crease recovery values are attained. In rubbery polymers, substantial changes in mechanical properties are obtained at much lower levels of cross-linking. This difference between cellulose and rubbers in response to cross-linking is probably due to the polar nature of cellulose.
Studies in the Light Absorption of Dyes.1
Authors: Giles C.H. , Rahman S.M.K. , Smith D.
Published: March 2007

A linear relation between the logarithm of the color concentration of a diffusely reflect ing colored surface and its reflectance density is derived as a simple extension of Beer's law and confirmed experimentally using a variety of dyed fabrics.

The experimental results indicate that Beer's law is not usually obeyed by the dye present in dyed materials, probably on account of the presence of adsorbed dye aggre gates. It is in fact only obeyed by true solutions or by suspensions of particles of con stant size distribution.

The application of Beer's law to transmission and reflection systems is discussed, and it is shown that a more general relation is obtained by substituting for c, the color con centration factor in the Beer's law formula, the empirical factor ( c/1 +acx ). where a and x are constants (probably functions of the refractive index difference between the dye and surrounding medium), and x is a simple fraction.

In a test with dyed viscose rayon fabrics it is shown that about 20% of the reflected light is specutarty reflected from the surfaces of lightly dyed fibers.
Aqueous Jet Scouring of Raw Wool
Authors: Anderson C.A. , Poulter I.J.
Published: March 2007

Removal of grease and dirt from raw wool packed on a wire mesh conveyer and jetted with aqueous solutions of detergents has been investigated. Grease removal de pends on detergent type and concentration, solution temperature, jet pressure, and number of jettings. Using a nonionic detergent with alkaline builder at 65° C, the following sequence reduces the grease content below 1%: detergent jet, squeeze; deter gent jet, squeeze; rinse jet, squeeze. Visual examination of the scoured wool shows that the original staples are almost undisturbed after being jetted and squeezed. A comparison of scoured fabrics shows that wool is less damaged in jet scouring at 85° C than in conventional aqueous scouring at 50° C.
Studies in Wool Yellowing
Authors: Kirkpatrick A. , Maclaren J.A.
Published: March 2007

Disulfide groups in wool have been converted to thioether groups by reduction and subsequent alkylation. In this way wool fabric that contained only 7-19%, of the original cystine content and that were almost identical in appearance with untreated fabrics were prepared.

The rates of yellowing of these fabrics and of controls that were alkylated without prior reduction were studied under conditions of heat, hot alkali, and uv irradiation. The rate of yellowing of the modified wools was at least as great as that of untreated wool, and this suggests that the decomposition of disulfide groups is not of major importance in the yellowing process.
Electron Microscopic Observations on Cellulose Graft Copolymers: Radiation Induced Rayon-Styrene Graft Copolymers1
Authors: Kaeppner Werner M. , Huang Robert Y-M.
Published: March 2007

Three types of commercial rayon (Fortisan, high-tenacity tire yarn, and modifier- type, high wet modulus yarn) were grafted with styrene, using the direct radiation method with gamma-rays from Co-60. The grafted filaments were examined in the electron microscope to investigate their morphology and fine structure, the location and distribution of polystyrene in the fiber, and whether the polystyrene was truly grafted.

In all three grafted fibers, the polystyrene was distributed throughout the cross sec tion of the filament and also appeared on the surface. As a result, the filaments expanded isometrically during grafting, but retained their original shape. The polystyrene grafted to the surface of the filament followed the original surface striations of the rayon and appeared as protruding ridges and valleys, rather than as uniform surface layers. The polystyrene inside the filament could not be removed hy exhaustive extraction of the intact yarn with benzene, but some of it could be removed by extracting the ultra-thin cross sections (ca. 500 Å thick) used for electron microscopic observations. The main portion of these ultri-thin sections was insoluble in solvents for both polystyrene and cellulose and is considered to be a true cellulose-styrene graft.

The changes induced in the fine structure of the cross sections by alternate extraction with solvents for polystyrene and cellulose were followed, using the electron microscope. From a macroscopic viewpoint, it was concluded that the styrene grafted rayons are homogeneous. At a molecular level, however, they consist of a gross heterogeneous mixture of polystyrene homopolymer, cellulose, and true cellulose-styrene graft co polymer.
A Study of the Mechanism of Loop Formation on Weft-Knitting Machinery
Authors: Knapton James J. F. , Munden Dennis L.
Published: March 2007

A detailed study was made of the effects of yarn friction on the magnitude of the tensions developed in the knitting zone of the standard weft-knitting machine and the in fluence of these tensions on loop formation and fabric quality. Variations in loop length of ±10% due to changes in yarn friction may be experienced at given cam settings and input tensions and these variations can be explained by the phenomenon of "robbing-back."

A geometrical model of loop formation is suggested as a means of mathematically predicting the values of the developed tensions, and the position and magnitude of the maximum knitting tensions Tk within the knitting zone, knowing the coefficient of yarn friction μ. This analysis suggests that the knitted loop length depends on the position of Tk rather than on the magnitude of Tk, but that fabric holes and "press-offs" are caused by Tk exceeding the breaking load of the yarn. For high values of μ, Tk exceeds the breaking load more readily than for low values. It is predicted that redesign of the conventional cam system to decrease the number of yarn/metal contact surfaces may reduce the values of Tk by 70% for high-friction yarns and by 50% for low-friction yarns, for the same cam setting and input tension.