The man-machine cooperative systems design constitutes a significant concern in a great number of fields and in particular in industrial engineering, where the control-command systems are numerous. In this article we ...
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ISBN:
(纸本)9781581136159
The man-machine cooperative systems design constitutes a significant concern in a great number of fields and in particular in industrial engineering, where the control-command systems are numerous. In this article we propose an original approach, which leads towards a dynamic allocation of actions between man and machine. After the problem presentation and comparison with existing work, we describe our proposal based on an original modelling and an algorithm of distribution which can be used in various contexts. This one allows in particular a dynamic allocation of actions to the man and the machine in relation with expressed aims. The purpose of design of such systems is to find a global performance in relation with the human actor capabilities and those of the machine.
Although it is well known that the enforced flow of dielectric liquids over a solid interface can give rise to charge separation with the resulting accumulation of static charges, the underlying physics is complex. Th...
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Although it is well known that the enforced flow of dielectric liquids over a solid interface can give rise to charge separation with the resulting accumulation of static charges, the underlying physics is complex. The incidence of streaming electrification in large transformers (and other industrial equipment) has generated the need for both an understanding and mathematical description of the physics. modelling of the phenomena is needed since the mechanisms do not readily scale so that small-scale laboratory experiments cannot be used to predict performance. This contribution chronicles the development of both steady-state and transient descriptions of the streaming electrification process. The nature of the phenomenon is such that appropriate assumptions and approximations need to be made. As a consequence, it is also important to include some experimental verification of the outcomes; at least in qualitative form. The entrainment of charge from the interface Helmholtz layer also intimately involves the flow of the liquid. A description of the flow regimes and a transient solution of the flow through a duct are thus an integral part of the modelling effort The utility of the steady-state model developed is demonstrated by application to an oil-cellulose system typical of a large core-form transformer. The method advocated takes advantage of the repeat duct arrangement in such units. The results presented allow the internal behaviour of such a unit to be studied in considerable depth, and provide insight into the complex interplay between generation and relaxation in circumstances when flow rates, temperature, external fields and influent charge are changed.
It is surprising that polymers such as polyolefins, composed only of carbon and hydrogen atoms in very simple configurations, can be used in so diverse applications as human bone prosthetic implants, gas pipelines, ca...
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It is surprising that polymers such as polyolefins, composed only of carbon and hydrogen atoms in very simple configurations, can be used in so diverse applications as human bone prosthetic implants, gas pipelines, car bumpers, synthetic fibers, and plastic films. The reason for such versatility is that microstructural. characteristics of polyolefins, such as distributions of molecular weight, chemical composition (or short-chain branching), and long-chain branching, have an enormous impact on their macroscopic properties and applications. Therefore, it is of utmost importance that these microstructural. details be well understood and properly described with fundamental models. This manuscript reviews the state-of-the-art mathematicalmodelling techniques for describing the microstructure of polyolefins produced by coordination polymerization. (C) 2001 Elsevier Science Ltd. All rights reserved.
The objective of the paper is to present a mathematical model for analysis of prestressed cable structures with flexible contour beam. The proposed numerical procedures are based on a discrete scheme according to the ...
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The objective of the paper is to present a mathematical model for analysis of prestressed cable structures with flexible contour beam. The proposed numerical procedures are based on a discrete scheme according to the finite element method. A reliable model of the interaction of the flexible contour beam with the cable network enables the achievement of more efficient solutions in the design analysis. Geometrical nonlinearity is accounted for in the cable net substructure and the contour beam is modelled by linear beam elements. Equations are solved by iterative methods and explicit time integration. The described numerical technique has been employed to model prestressing, static and dynamic behaviour. Theoretical results have been compared to experimental data and used in practical applications. (C) 2001 Civil-Comp Ltd. and Elsevier Science Ltd. All rights reserved.
This article is aimed at introducing the theory of reference frames in mathematical psychology to the control theory community and to point out its relevance in understanding the differences between biological and eng...
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This article is aimed at introducing the theory of reference frames in mathematical psychology to the control theory community and to point out its relevance in understanding the differences between biological and engineering control systems. As an example, we discuss the problem of human posture control and point out how the reference frames theory lead to a natural solution which is in agreement with everyday observations on how a child learns to do posture control. (C) 2001 Elsevier Science Ltd. All rights reserved.
Stress-strain data obtained from animal and human tissue have several applications including medical diagnosis, assisting in surgical instrument design and the production of realistic computer-based simulators for tra...
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Stress-strain data obtained from animal and human tissue have several applications including medical diagnosis, assisting in surgical instrument design and the production of realistic computer-based simulators for training in minimal access surgery. Such data may also be useful for corroborating mathematical models of tissue response. This paper presents data obtained from ex-vivo and in-vivo tissue indentation tests using a small indentor that is similar to instruments used in minimal access surgery. In addition, uniform stress tests provide basic material property data, via an exponential stress-strain law, to allow a finite element method to be used to predict the response for the non-uniform stresses produced by the small indentor. Data are obtained from harvested pig liver and spleen using a static compliance probe. Data for human liver are obtained from volunteer patients, undergoing minor open surgery, using a sterile hand-held compliance probe. All the results demonstrate highly non-linear stress-strain behaviour. Pig spleen is shown to be much more compliant than pig liver with mean elastic moduli of 0.11 and 4.0 MPa respectively. The right lobe of human liver had a mean elastic modulus of about 0.27 MPa. However, a single case of a diseased liver had a mean modulus of 0.74 MPa - nearly three times the stiffness. It was found that an exponential stress-strain law could accurately fit uniform stress test data and that subsequent finite element modelling for non-uniform stress around a small indentor matched measured force characteristics. (C) 2001 Elsevier Science B.V. All rights reserved.
High-speed robotics is growing fast as a new research and application field, with more and more demanding requirements actually posed to robots' builders;sometimes the design of brand new mechanical architectures ...
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ISBN:
(纸本)0780367367
High-speed robotics is growing fast as a new research and application field, with more and more demanding requirements actually posed to robots' builders;sometimes the design of brand new mechanical architectures is needed (eg. lightweight parallel machines) but, if possible, reengineering of existing models will provide more economical solutions. This is presently the case of the CO2 High Speed Cartesian robot produced by Campetella Robotic Center, that is already characterised by good dynamic performances but has been chosen by the producer for a re-engineering that should allow it to meet even more advanced targets. First experimental tests showed that some important interventions were needed for the upgrade, therefore a full dynamic modelling has been performed by the University of Ancona to try to get the best of the existing hardware during the reengineering phase. The simple mechanical architecture of the Cartesian robot allowed to outline a typical modelling approach that took profit of the full integration of the used software packages;a campaign of experimental measures has been performed for the validation of the mathematical models and to assess the dynamic behaviour of the mechanical structure through modal testing.
A mathematical approach has been developed to account for the dynamic behaviour of the conducting shell caused by soil ionisation. The experimental studies indicate that once the threshold electric field is exceeded, ...
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A mathematical approach has been developed to account for the dynamic behaviour of the conducting shell caused by soil ionisation. The experimental studies indicate that once the threshold electric field is exceeded, soil ionisation occurs with a statistical time delay, and the developed model incorporates this feature. The maximum radius of the conducting region was found to be proportional to the peak magnitude of the applied voltage. The analytical model proposed in this paper is implemented on a Mathcad platform. Satisfactory agreement was obtained between the experimental results and the model predictions.
A complete mathematical model for describing high voltage DC vacuum circuit breakers is presented. The model takes into account the effects of the external commutation circuit on the behaviour of vacuum arc. It also i...
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A complete mathematical model for describing high voltage DC vacuum circuit breakers is presented. The model takes into account the effects of the external commutation circuit on the behaviour of vacuum arc. It also incorporates equations representing the physics of DC diffuse vacuum arc. Experimental verification shows good agreement between the simulated results and the practical response.
The problem which is described is associated with the modelling and simulation of a water supply system consisting of a sequence of pumping stations, delivering water through pipelines to intermediate storage reservoi...
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The problem which is described is associated with the modelling and simulation of a water supply system consisting of a sequence of pumping stations, delivering water through pipelines to intermediate storage reservoirs. behaviour of the system is investigated by slow movement of fluid flow around steady-state operating point. Head losses changing nonlinearly with water flowrates in pipes are represented by the Darcy-Weisbach and the Hazen-Williams methods with roughness dependent friction coefficients. Pumps are represented with second order nonlinear function depending on their speed and pumped water flowrate. The city of Gaziantep Water Supply System is considered in the Case Study. The original pump characteristics obtained from the pump manufacturer are used for the mathematical equivalent of the pumps. Roughness dependent friction factors are calculated for different methods using bisection numerical solution method and the results are given and compared. The major losses obtained with the Darcy-Weisbach and the Hazen-Williams methods are presented and compared with local losses. The simulation results and real plant measured data are compared.
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