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This paper defines a group partitioning model with the view to improving the load balancing in a distributed system. Using modelling and simulation, we analyze the impact of this new partitioning technique on load balancing strategies. We show that a strategy based on group preference gives efficient results.

The Earth's trapped radiation belts were discovered at the beginning of the space age and were immediately recognised as a considerable hazard to space missions. Consequently, considerable effort was invested in building models of the trapped proton and electron populatinos, culminating in the NASA AP-8 and AE-8 models which have been the de facto standards since the seventies. The CRRES mission has demonstrated that the trapped radiation environment is much more complex than the static environment described by the old models. Spatial and especially temporal variations were shown to be much more important that previously thought, and to require more complex models than those in use at that time. Such models are now becoming available, but they are limited in spatial or temporal coverage, and no global, dynamic, trapped radiation belt model is forthcoming. It is therefore vital to co-ordinate future modelling efforts in order to develop new standard models.

The galactic (GCRs) and anomalous (ACRs) cosmic rays form the lower parts of the planetary ionospheres. For this purpose analytical and numerical spectra for cosmic particles are necessary. Our knowledge of GCR modulation in the solar system was greatly enhanced thanks to the heliospheric missions, Voyagers 1 and 2, Pioneer 10 and Ulysses. In this paper, a new model for the calculation of the GCR and ACR element differential spectra D(E) on the basis of satellite measurements is created. This computed analytical model gives a practical possibility for investigation of experimental data from measurements of GCR and ACR component. The contribution of GCRs and ACRs to the ionization of the atmospheres of outer planets Uranus, Neptune and Pluto increases drastically.

The basic kinematic behaviour of a threshold switch in a system with a sparse population is investigated. We determine the basic quantities such as the number probability density function, the survival probability, the characteristic switching time, and the response to external triggering of the switch. The modelling approach is then extended to systems with response retardation, which, it is argued, may improve the stability of the switch.

Computer modelling, due to it saving time and money, has been widely used in industrial simulation. The present model, which is based on the Shercliff-Ashby methodology for the ageing of aluminum alloys, can be used to predict the yield strength (or hardness) of Al-Mg-Si alloys for the artificial ageing temperature below the solvus temperature as a function of time. With suitable input data, this model can be applied to most Al-Mg-Si alloys, wrought or cast. In the present model, input data for aluminium alloys of A356, A357 and 6061 is taken from the open literature, and then the unknown constants are calibrated from these data. After calibration, the ageing curves are constructed for different isothermal ageing temperatures. Finally, experimentally ageing heat treatments at different temperatures for casting alloys of A356 were done to validate the model.

With increasing requirements of distributed software systems, software agents are becoming a mainstream technology for software engineering and data management. Scalability and adaptability are two key challenges that must be addressed. In this work a new model is introduced for building large-scale distributed software systems with high dynamics, using a hierarchy of homogeneous agents that has the capability of service discovery. The performance of the agent system can be improved using different combinations of optimisation strategies. A modelling and simulation environment has been developed to aid the performance evaluation process. Two case studies are given and simulation results are included that show the impact of the agent mobility and the choice of performance optimisation strategies on the overall system performance.

This paper presents a simplified model of 2D torsional micromirror for control design. The micromirror system is modeled as a two inputs two outputs (TITO) system with nonlinear electrostatic torques, which are coupled with the two inputs and the two tilt angles. The coupling property of the electrostatic torques makes it difficult to design the control law. To surmount the problem, a new model based on extracting the dominant nonlinear terms and Taylor's expansion is proposed. The micromirror system together with the simplified model is coded in Matlab™ S-function. The simulation result shows that the model is feasible for control design.

The Hellenic Open University has embarked on a large-scale effort to enhance its textbook-based material with content that demonstrably supports the basic tenets of distance learning. The challenge is to set up a framework that allows for the production-level creation, distribution and consumption of content, and at the same time, evaluate the effort in terms of technological, educational and organizational knowledge gained. This paper presents a model of the educational process that is used as a development backbone and argues about its conceptual and technical practicality at large.

High Pressure (HP) Processing has turned out to be very effective in prolonging the shelf life of some food. This paper deals with the modelling and simulation of the effect of the combination of high pressure and thermal treatments on food processing, focusing on the inactivation of certain enzymes. The behavior and stability of the proposed models are checked by various numerical examples. Furthermore, various simplified versions of these models are presented and compared with each other in terms of accuracy and computational time. The models developed in this paper provide a useful tool to design suitable industrial equipments and optimize the processes.

Video surveillance is one of the most active research topics in the computer vision due to the increasing need for security. Although surveillance systems are getting cheaper, the cost of having human operators to monitor the video feed can be very expensive and inefficient. To overcome this problem, the automated visual surveillance system can be used to detect any suspicious activities that require immediate action. The framework of a video surveillance system encompasses a large scope in machine vision, they are background modelling, object detection, moving objects classification, tracking, motion analysis, and require fusion of information from the camera networks. This paper reviews recent techniques used by researchers for detection of moving object detection and tracking in order to solve many surveillance problems. The features and algorithms used for modelling the object appearance and tracking multiple objects in outdoor and indoor environment are also reviewed in this paper. This paper summarizes the recent works done by previous researchers in moving objects tracking for single camera view and multiple cameras views. Nevertheless, despite of the recent progress in surveillance technologies, there still are challenges that need to be solved before the system can come out with a reliable automated video surveillance.

One of the greatest problems facing theoretical scientists and modellers is the difficulty of presenting results to managers in a form that can be understood and utilized by them while retaining as much as possible of the scientific content. Many managers have limited scientific expertise and they are often unfamiliar with theoretical approaches. They are also reluctant to share their decision-making responsibilities with scientists, who may not be familiar with all the factors they have to deal with. This often makes it difficult for scientific advisors to function effectively.

An alternative is to use expert systems technology to let managers access the scientific expertise relevant to the decision-making process without requiring direct personal interaction with scientific advisors. This is particularly appropriate for environmental management situations where managers in remote locations may not have easy access to scientists in relevant fields. We have therefore been developing a Decision Support System (DSS) as a tool for communicating scientific advice to managers. This paper addresses the general issues behind using Decision Support Systems in this way and discusses some of the problems involved.

Although a computer program cannot be expected to represent more than a fraction of the expertise of real scientists, the DSS approach appears to have several advantages; these include the ability to deliver a degree of expertise in remote and isolated regions, and, perhaps most important, a chance for managers to access scientific resources in a private environment which lets them explore various options without having to justify their eventual actions to scientists who may not fully appreciate all the pressures which bear on their decisions.

We attempt to model the circulation of the Feline Immunodeficiency Virus (FIV), a retrovirus analogous to the HIV, within populations of domestic cats. Domestic cats exhibit different patterns of population dynamics, social behaviour and reproductive strategies. In fact, cats can be either solitary or living in large social groups, with many intermediate states.

The aim of the presented model is to provide a conceptualization of the mechanisms of FIV spreading rather than to be a predictive tool. As one of our goals is to integrate easily new informations when available, and to remain simple and close to the biological reality, parameters, such as sex, age classes and dispersion, have been incorporated successively. This model can also be adapted to different types of cat populations by simple changes, as it could be to other host populations. A study of the stability of the model has been done. Based on available data, values of two parameters has been estimated: the carrying capacity and the transmission rate. Results are in good accordance with biological data.

Some of the vector-borne infections with public health importance involve an animal reservoir. This work describes, through a compartimental model, the dynamics of leishmaniasis considering the interactions between the three populations involved, namely the sandfly, the domestic dog (as the principal intermediate host), and the human population. An expression for the Basic Reproduction Ratio (R₀), which takes into account the time delay representing the extrinsic incubation period of the parasite in the vector, is presented. Numerical simulation, equilibrium and stability analysis provided insights into the transmission dynamics of the infection that can help in the design of control strategies.

There are many models in phyllotaxis concerned with optimality principles which are apparently equivalent. The important problem of showing the equivalence of the models has been underlined but not addressed yet. This paper addresses the general problem of determining up to which point we have equivalence. The viewpoint adopted is the one of the outcomes of the models, of what they generate, and of what they don't, at least in their actual states. It will be emphasized too that models in phyllotaxis can be compared at many different levels, and that their biological supports can spring from many of these levels.

From the linear, nonlinear optical and laser properties of GdCOB:Nd and YCOB:Nd self-frequency doubling crystals, we have found that the slow laser wave at 1060 nm has a higher emission cross-section than the fast one in the whole locus of SH phase matching, meaning that self-frequency doubling should be possible on this whole locus. We have pointed out that the phase matching direction for maximum nonlinear optical coefficient d_eff is far from the one for maximum laser emission cross-section. The question of optimum direction for the self-frequency doubling laser was solved with a complete laser modelling. The maximum value of the SH yield occurs at a polar angle θ=68° for GdCOB:Nd, that is to say, close to the value of the optimum nonlinear optical coefficient d_eff. For YCOB:Nd, the polar angle at maximum SH yield is shifted at 72°, that is to say, towards the direction of the largest laser emission cross-section. In both cases, we can notice a larger "angular acceptance" on the locus of phase matching for the self-frequency doubling laser than for extra-cavity single pass frequency doubling.

So far, the commonly used optical parametric oscillators (OPOs) relying on ${\chi }^{(2)}$ nonlinearity in the bulk materials have been extensively investigated both theoretically and experimentally, but not enough attention has been paid to OPOs based on ${\chi }^{(3)}$ nonlinearity in optical fibers. In this paper, a singly resonant fiber optical parametric oscillator (FOPO) is theoretically studied and its main aspects are simulated. Also, impacts of various parameters including the pump and signal wavelengths, the fiber length and dispersion as well as the input coupler on the conversion efficiency of the FOPO are investigated. Finally, the simulation results are compared with the available experimental data and a very good agreement is obtained.

The sagittal plane, which Pauwels regarded as being of no importance for the hip, was studied in the whole body with respect to posture while walking. After a preliminary study, which confirmed the importance of the sagittal plane for the hip, we performed a 3-dimensional modelling of the hip using the finite element method, with the aim of studying the resultant force exerted at the centre of the coxofemoral joint and of analysing the actions of the muscles from the efforts recorded. On the basis of these findings, we represented the overall mechanical problem of the hip in schematic terms as a variable dynamic balance. The results of this work also allowed us to establish in detail the impact of optimisation on the muscular actions and the impact of variations in displacement and the acceleration of the partial centre of gravity on the results recorded. Finally, the isolated hip model was developed, with the aims of allowing us to study the relations existing between variations in the angle of femoral anteversion and variations in forces, and of making a contribution to anthropological studies of the structures of locomotion through the ages.

Understanding Diabetes

Prediabetes: The Gap between the Onset of Disease and Initiation of Treatment.

Diabetes: A Dietitian’s Perspective.

Use of Modelling for Better Diabetes Care.

No More Highs and Lows with Toujeo®: A New and Improved Insulin Injection.

This paper demonstrates that multi-agent systems have the capacity to model a region in all its complexity. An example is developed to show that these tools are not only capable of spatializing and distributing the behaviour of individuals, but above all, that they allow individuals to integrate different perceptions of space as well as the constraints imposed on them by a community. A dialectic is established between individuals, spaces and society, which is used to simulate a region using clearly defined social representations and spatial practices, which are suitable for testing our geographical theories and hypotheses.

In this review, we present some designs of CNTFET-based circuits, already proposed by us, and critically examine them here. For some of these, we compare the performance of proposed circuits both in CNTFET and CMOS technology. For the CNTFET model, we use a compact, semi-empirical model, already proposed by us and briefly recalled, while, for the MOSFET model, we use the BSIM4 one of the ADS library. Moreover in some design examples, we compare our results with those obtained using the Stanford model. All simulations are carried out using the software advanced design system (ADS), which is compatible with the Verilog-A programming language.