摘要:

AbstractSeveral methods have been proposed in order to perform an analysis of mu1ticomponent exponential decay curves. Most of them tend to determine a combination of 6 Dirac distributions, which are difficult to be got from a computer.Instead of this set of Dirac distributions, an already proposed method allowed to obtain their integral, which is a sum of Heaviside step-like functions, each step of which providing simultaneously the amplitude and relaxation time of the corresponding exponential component.A comparison of the two types of methods makes appear some improvements of accuracy for results obtained with Heaviside’s steps. Theoretical reasons are given for them.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759722

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractFrom our own investigations it is seen as a trend to use small and low-cost computer systems for the interactive simulation of small and medium size continuous dynamic syetems. Such simulation systems can be used where previously an an logue computer had been applied, as a greater range of flexibility is available. The LSI-II from DIGITAL with a dual floppy disc and graphical outputs has been chosen to build a powerful simulation system. THTSIM is a software package that can be used in this system and that offers som usefull extensions, in addition to the normal facilities of a“hands-on”interactive block diagram orientated simulation language. THTSIM also accepts a bond graph as a model input, and stored data from previous simulation runs or from real processes can be used. Frequency analysis is possible by means of an FFT algorithm. To create multi-run facilities, for example for parameter estimation, the main functions of the program are also FORTRAN callable. TBTSIM is written in PDP-II assembler language, and by means of conditional assemblies a load module can be generated for either a stand-alone processor without mass-storage or for systems based on the RT-II or RSX-II operating system. A FORTRAN version is available too.Planned developments for the near future are discussed, including the use of p rsonal computers with acceptable graphics and calculation performance and the use of the PASCAL language.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760440

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThermodynamic Bond Graphs (TBG) are introduced, which are based on the thermodynamic state-space concept, but are extended to the Hamiltonian state-space of usual Bond Graphs by the sympletic gyrator (SGY). After the definition of physical domains, the SGY is shown to be an interdomain coupler, which can be eliminated by the definition of dual components, thus resulting in the usual Bond Graph concept. Not all domains of the TBG are coupled to another by an SGY however, and in usual Bond Graphs this is demonstrated by the fact that thermal and chemical (material) inductances do not exist. The main advantage of the TBG-concept is the possibility of systematic modeling of open (or convective) systems, which is based on a new definition of the effort of the material domain, to be called“total material potential”. To demonstrate this, the TBG is successfully applied to a compressible, one-dimensional matter-flow, which convects momentum and heat (entropy).

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760441

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractA pendulum of three meter length, which can be controlled in three perpendicular axes, is used in experiments for strap-down navigation components. In the first measurements with accelerometers attached to the pendulum not only the pendulum frequency but also some higher frequencies were detected. By means of modelling and simulation the causes of the higher frequencies are found.In this contribution the modelling techniques and some simulation results will be described. It will be shown how the bond graph modelling technique can give a clear description of the system not only for the two dimensional case, with rotation around ono axis, but also for the case where the pendulum is controlled at the three axes.First the model will be restricted for clearity roasons, to one axis. The general set up of the pendulum and drive system will be shown, then step by step the model is extended. Adding torsion in the drive axis will show the first additional frequency. A simple model of the pendulum construction showing the bending of this construction will add higher frequencies to the system.Finally the model for the three dimensional movement will be treated. The bond graph of such a system shows clearly all the interactions in tho system. It can be concluded that the system tic way of setting up a model of a rotating body is one of the advantages using bond graphs.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760442

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThe bond graph method allows to generate the dynamic model of a large gas distribution system in form of linear algebraic equations directly. A further advantage is the possibility to treat environmental effects more easily as with classical methods.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760443

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractA very powerful tool in the analysis of large complex systems is a piotorial representation of the system by a directed graph. This teobnique is widely used as a struotural tool e.g. in system dynamios modeling. In this paper a oomputer package to unscramble and layout diagrams of feedbaok loops is presented. The computer time and sp oe bounds are direotly proportional to the number of vertioes in the graph. A heuristio prooedure is used to minimize the number of crossings as far as possible.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760444

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

SummaryThere is a large number of languages and packages available for the simulation of discrete systems. They are referred to in this paper as simulators. Simulators can be divided into simulation languages, which require a special compiler, e.g. GPSS (8), and packages, which are written in a high level programming language, e.g. GASP (22).We start by introducing a classification of simulators, and placing the best known simulators in this classification.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760445

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractGenerally the modelling process starts with a natural language specification of hypotheses and assumptions being the result of the analysis of the real system. The paper describes the attempt to combine the natural language spefication of model hypotheses and the model development, i.e. design and generation of a basic model version realized by a natural language oriented modelling system. It enables in general the application of system dynamics models. The user involved with the development of analytlcal planning models is led by the system; that monitors the user’s activities and supports him by a dialogue to define complete assumptions of model components, to alter model parameters or the model structure. to produce an output, etc. The system is written in FORTRAN IV implemented on an IBM VM/370-158.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760446

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractSIMUL is an interactive equation-oriented language for simulation of continuous-time systems on minicomputers; it has designed for a rmximum case of programming and use, allowing the user to write his equations in standard rmthematical form and to control the simulation runs by simple commands. This paper describes the main features of the language and progroTmling system, and it gives two examples illustrating the use of SIMUL and its capabilities, especially the prograTmling of multiruns simulation studies and the use of indexed variables in case of discretized partial differential equations.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760447

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThis simulation program, which emploies a block-oriented language, is used to simulate not only continuous systems but also sampled-data systems and DDC-systems.The simulation of sampled-data systems can be performed by means of special blocks to model linear and nonlinear difference equations. In case of linear difference equations this can be done by the use of only one block.According to the recent evolution, which preferably uses microprocessors in DDC-systems, the computation of such a difference equation can be simulated with respect to the restricted accuracy which is due to the data representation in fixed-point computations.Also the computing time can be taken in account in the simulation.Furthermore, it is possible to simulate the resolution of AID-converters and D/A-converters in DOC-systems in a practical manner.The use of DASP in simulating DDC-systems is shown by an example, which emphasizes the necessity to consider the restrictions resulting from practical realization.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11760448

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor