A large increase in the power required on-board automobiles is expected in the years to come. More complex electric networks will then be required to provide adequate reliability and minimal fuel consumption. The scop...
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A large increase in the power required on-board automobiles is expected in the years to come. More complex electric networks will then be required to provide adequate reliability and minimal fuel consumption. The scope of this study is to present a model for an automotive battery introduced in a software package that is developed to simulate current and future electrical architecture. This model is based on an evaluation of battery e.m.f., over-voltage and capacitive behaviour. A description is given of the test protocol used to develop laws and to validate the model. The model is tested successfully both in starting phases and under real vehicle running conditions.
Based on thermodynamics and kinetics, a new mathematical model was developed to calculate the CCT diagrams and the transformation kinetics in low carbon niobium steels, in which the effect of deformation on the degree...
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Based on thermodynamics and kinetics, a new mathematical model was developed to calculate the CCT diagrams and the transformation kinetics in low carbon niobium steels, in which the effect of deformation on the degree of supercooling was taken into account. The undercooling caused by deformation is the major reason for the increase of the starting transition temperature during continuous cooling. The critical cooling rate of bainite formation is within 2--5 ℃s for the studied niobium steels and deformation is suitable for the occurrence of pearlite. The ferrite volume fraction increases with the increase of the austenite boundary area, and decreases with the increase of the cooling rate. The calculated CCT diagrams and the volume fraction of each phase are in good agreement with the measurements.
A mathematical model of an unheated biogas plant described in this paper can be used to predict biogas generation at any given;geographical location by using laboratory experimental data of methane gas generation at d...
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A mathematical model of an unheated biogas plant described in this paper can be used to predict biogas generation at any given;geographical location by using laboratory experimental data of methane gas generation at different values of temperature and retention time. So, this model obviates the need for repeating field experiments at different geographical locations. The introduction of new concepts of equivalent temperature and biogas coefficient help to convert laboratory data into field data and minimize the necessity of conducting field experiments. Further, retention time and size of the biogas plant for a given daily requirement of biogas are optimized through life cycle economic analysis. The model has been elaborated by calculating results for biogas generation with cattle dung in a fixed dome type biogas plant located at Ludhiana. Results are presented for various values of daily biogas requirement and cost of feedstock. (C) 1997 Elsevier Science Ltd.
The scarcity of hourly solar radiation data for locations in Vietnam presents difficulties in using simulation packages for assessing the potential of solar energy systems in that country. This paper describes a compu...
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The scarcity of hourly solar radiation data for locations in Vietnam presents difficulties in using simulation packages for assessing the potential of solar energy systems in that country. This paper describes a computer model to generate daily and hourly solar radiation sequences from monthly average daily radiation values, or monthly average daily sunshine hour data. The resulting model has been tested in a number of ways. The statistics of the real and generated sequences were compared. Also the two data sequences have been used in simulation packages and design program such as f-chart and the performance of solar hot water system for the two cases compared. The results of these comparisons are also reported in this paper.
Transmembrane acid-base fluxes affect the intracellular pH and unstirred layer pH around a superfused biological preparation. In this paper the factors influencing the unstirred layer pH and its gradient are studied. ...
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Transmembrane acid-base fluxes affect the intracellular pH and unstirred layer pH around a superfused biological preparation. In this paper the factors influencing the unstirred layer pH and its gradient are studied. An analytical expression of the unstirred layer pH gradient in steady state is derived as a function of simultaneous transmembrane fluxes of (weak) acids and bases with the dehydration reaction of carbonic acid in equilibrium. Also a multicompartment computer model is described consisting of the extracellular bulk compartment, different unstirred layer compartments and the intracellular compartment. With this model also transient changes and the influence of carbonic anhydrase (CA) can be studied. The analytical expression and simulations with the multicompartment model demonstrate that in steady state the unstirred layer pH and its gradient are influenced by the size and type of transmembrane flux of acids and bases, their dissociation constant and diffusion coefficient, the concentration, diffusion coefficient and type of mobile buffers and the activity and location of CA. Similar principles contribute to the amplitude of the unstirred layer pH transients. According to these models an immobile buffer does not influence the steady-state pH, but reduces the amplitude of pH transients especially when these are fast. The unstirred layer pH provides useful information about transmembrane acid-base fluxes. This paper gives more insight how the unstirred layer pH and its transients can be interpreted. Methodological issues are discussed.
A computer model of the stem cell population is presented. Proliferation control is achieved solely in this model by a feedback, which changes the flow of cells from the G0 state into the G1 phase according to the amo...
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A computer model of the stem cell population is presented. Proliferation control is achieved solely in this model by a feedback, which changes the flow of cells from the G0 state into the G1 phase according to the amount of the DNA synthesizing S phase cells. Behavior of the model was compared with experimental data available about the CFUs (colony-forming units - spleen) cell population. A reasonable agreement between simulation results and experimental data could be obtained provided that some cells do not pass through the G0 state during their cell cycle. Necessity to establish the seeding efficiency of the spleen colony technique arose when experimental CFUs data showing pluripotential stem cells response to hydroxyurea damage were compared with results obtained from the model.
Introduction: Following atrial premature beats, the AV node may exhibit sustained reentrant tachyarrhythmias, isolated echo beats, or discontinuities in the recovery curve (the plot of conduction time versus atrial cy...
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Introduction: Following atrial premature beats, the AV node may exhibit sustained reentrant tachyarrhythmias, isolated echo beats, or discontinuities in the recovery curve (the plot of conduction time versus atrial cycle length). A computer model was used to examine the hypothesis that spatial variation of AV nodal passive electrical resistance may account for these phenomena. Methods and Results: A computer model of a rectangular lattice of electrotonically linked elements whose ionic kinetics simulated nodal ionic flux was developed. The model showed that there exists a resistance value that minimizes the effective refractory period, because high resistance prevents depolarization of distal elements, while low resistance allows leakage of depolarizing current by electrotonic transmission, preventing activation of proximal elements. High resistances stabilized reentry by slowing conduction. Simulations incorporating equal resistance values between elements predicted increased AV nodal conduction times with increasing prematurity of atrial impulses. A model with a gradual change in resistance between fibers produced discontinuities and tachycardia, but not both simultaneously. Uniform anisotropy produced preferential transverse block, leading to echo beats and ''fast-slow'' tachycardia, but not recovery curve discontinuities. Nonuniform anisotropy could produce reentry, but tachycardia often occurred without discontinuities. Dividing the lattice into two electrotonically linked parallel pathways with different resistance values (''dual pathway model'') predicted recovery curve discontinuities, echo beats, and tachycardia. At critical atrial cycle lengths, only the (high resistance) slow pathway conducted antegradely, while the fast pathway conducted retrogradely, to generate the typical ''slow-fast'' tachycardia. Responses of the dual pathway model to ablation were consistent with clinical data, including the previous observation of a decrease in fast pathway effect
An efficient way of determining some of the glazing related variables is described, thus enabling thermal performance to be considered easily at the early design stage when inexpensive measures of heating and cooling ...
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An efficient way of determining some of the glazing related variables is described, thus enabling thermal performance to be considered easily at the early design stage when inexpensive measures of heating and cooling can be advocated and tested.
This paper aims to use the prototype system of the Internet of Things to study the computer model of display design, combined with the transmission principle of the Internet of Things technology, and use the computer ...
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This paper aims to use the prototype system of the Internet of Things to study the computer model of display design, combined with the transmission principle of the Internet of Things technology, and use the computer digital technology to simulate. This paper proposes to use the Internet of Things technology combined with the application of computer, network 4/5G and other technologies in the prototype system of the Internet of Things, combined with art, trade and other traditional display design, to study the computer model of display design. Compared to traditional IoT devices, the combination of IoT technology, computers and networks has a higher speed in terms of data transmission. The results of the global Internet of Things development scale in recent years show that in 2016-2020, the global Internet of Things scale reached $200 billion from $70 billion, and China's Internet of Things employees reached 16 million.
Electrocardiologic criteria of left ventricular enlargement do not take into consideration the eventuality of asymmetric hypertrophy. Since experimental techniques for production of this condition are not available, c...
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Electrocardiologic criteria of left ventricular enlargement do not take into consideration the eventuality of asymmetric hypertrophy. Since experimental techniques for production of this condition are not available, computer modeling was utilized to study its electrocardiologic manifestations. A computer model of human ventricles with analytically defined geometry, consisting of 142 000 elements (1.2 mm spatial resolution), was used to produce models of circumscribed hypertrophies by increasing the wall thickness to 150% in various regions of the free left ventricular wall, the septum and the apex. Gradients of simulated transmembrane action potentials were utilized to compute resultant heart vectors at any instant of ventricular activation and recovery, as well as time courses of their characteristics and planar projections of vectorgraphic loops. Involvement of the septum and/or the anterior wall decreased the maximum QRS vector magnitude, an opposite effect resulted from involvement of the lateral and posterior wall segments. Directional vector changes predicted the diagnostic value of S waves in precordial leads. Asymmetric hypertrophy did not produce abnormal Q waves. The maximum T vector increased in hypertrophy of any part of the free wall along with an increase of the spatial angle between maximum QRS and T vectors. The results of this study may be useful for refinement of electrocardiographic and vectorcardiographic diagnostic criteria of asymmetric left ventricular hypertrophy.
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