In this Letter, the genesis of spike-wave activity-a hallmark of many generalized epileptic seizures-is investigated in a reduced mean-field model of human neural activity. Drawing upon brain modelling and dynamical s...
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In this Letter, the genesis of spike-wave activity-a hallmark of many generalized epileptic seizures-is investigated in a reduced mean-field model of human neural activity. Drawing upon brain modelling and dynamical systems theory, we demonstrate that the thalamic circuitry of the system is crucial for the generation of these abnormal rhythms, observing that the combination of inhibition from reticular nuclei and excitation from the cortical signal, interplay to generate the spike-wave oscillation. The mechanism revealed provides an explanation of why approaches based on linear stability and Heaviside approximations to the activation function have failed to explain the phenomena of spike-wave behaviour in mean-field models. A mathematical understanding of this transition is a crucial step towards relating spiking network models and mean-field approaches to human brain modelling. (c) 2006 Elsevier B.V. All rights reserved.
It is generally accepted that human error, particularly in design, causes a significant proportion of structural failures. It is necessary to understand the 'micro' (or single task) behaviour of human errors b...
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It is generally accepted that human error, particularly in design, causes a significant proportion of structural failures. It is necessary to understand the 'micro' (or single task) behaviour of human errors before the entire system can be modelled. Reported herein is a description of proposed mathematical models of error occurrence that are suitable for use in a human Reliability Analysis (HRA). These models may be used to provide error rate information. These models are fitted to realistic error occurrence data. The data was obtained from practising professional engineers and the tasks performed were cognitive;namely, calculation, table look-up and ranking tasks. These tasks are commonly encountered in typical design calculations. It was found that error occurrence behaviour is characterised by variation of error rates between individuals and, to a lesser extent, correlation of error rates for individuals. The effect of response time and experience were also examined. A comparison of the effect on structural reliability (for a typical structural design task) for error occurrence (based on the proposed models) is also reported.
作者：
Enab, YMFaculty of Engineering
Automatic Control & Computer Engineering Department El-Mansoura University El-Mansoura Egypt
The reason for the present upsurge of interest in intelligent control is that the present generation of control systems are incapable, to a greater or lesser extent, of dealing with problems of a certain complexity. F...
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The reason for the present upsurge of interest in intelligent control is that the present generation of control systems are incapable, to a greater or lesser extent, of dealing with problems of a certain complexity. Fortunately, the human operator (HO) is often expert in keeping the complex control systems on the right track. In this paper a method for controller design has been investigated based on a concept of developing a mathematical model for HO behaviour. The method treats HO behaviour as a dynamic process by itself, transformed from the unknown dynamics of the ship to be controlled. The method of controller design entails observing the human controller, constructing a model of the human controller, and using that model as a basis for an automatic control system. During the observation phase the HO controls the ship and the data representing the state of the ship and human actions are registered. During the modelling phase, a human operator behaviour model (HOBM) is constructed as a neural network and its parameters are estimated. During the testing phase, the HOBM controls the ship and its performance is evaluated under the observation phase conditions and completely different conditions. The method has been successfully applied using computer simulation for the ship steering problem.
The paper presents the problems related to mathematicalmodelling of two-phase turbulent flows. The presented model includes charging of PVC particles being a result of collision with a pipe wall, as well as influence...
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The paper presents the problems related to mathematicalmodelling of two-phase turbulent flows. The presented model includes charging of PVC particles being a result of collision with a pipe wall, as well as influence of non-homogeneous field and external forces on aerodynamics of particles. The model served for the analysis of behaviour of dielectric particles flowing in the electric field and interactions of particular forces on the particle.
Over the past decade, studying animal behaviour with the help of computer vision has become more popular. Replacing human observers by computer vision lowers the cost of data collection and therefore allows to collect...
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Over the past decade, studying animal behaviour with the help of computer vision has become more popular. Replacing human observers by computer vision lowers the cost of data collection and therefore allows to collect more extensive datasets. However, the majority of available computer vision algorithms to study animal behaviour is highly tailored towards a single research objective, limiting possibilities for data reuse. In this perspective, pose-estimation in combination with animal tracking offers opportunities to yield a higher level representation capturing both the spatial and temporal component of animal behaviour. Such a higher level representation allows to answer a wide variety of research questions simultaneously, without the need to develop repeatedly tailored computer vision algorithms. In this paper, we first cope with several weaknesses of current pose-estimation algorithms and thereafter introduce KeySORT (Keypoint Simple and Online Realtime Tracking). KeySORT deploys an adaptive Kalman filter to construct tracklets in a bounding-box free manner, significantly improving the temporal consistency of detected keypoints. In this paper, we focus on pose estimation in cattle, but our methodology can easily be generalised to any other animal species. Our algorithm is able to detect up to 80% of the ground truth keypoints with high accuracy, with only a limited drop in performance when daylight recordings are compared to nightvision recordings. Moreover, by using KeySORT to construct skeletons, the temporal consistency of generated keypoint coordinates was largely improved, offering opportunities with regard to automated behaviour monitoring of animals.
Various mathematical models describing thickener behaviour have been published. These models have found limited use so far and few if any have proven dynamic capability. Under industry sponsorship, CSIRO has undertake...
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Various mathematical models describing thickener behaviour have been published. These models have found limited use so far and few if any have proven dynamic capability. Under industry sponsorship, CSIRO has undertaken to develop and validate a dynamic mathematical model describing thickner behaviour. Novel instrumentation has enabled measurement of the sediment density profile and settling rates and densities of flocculated aggregates in samples taken from the thickener. These data have been used as input to the model to establish a physical basis for appropriate parameters. This paper review the relevant literature and describes the current modelling approach and experimental methods used for validation. Typical data are presented and a comparison is made of the model output with plant data. It is anticipated that a satisfactorily validated model will be used on the plant to simulate start-up dynamics, alternative operating and control strategies and to optimize flocculant usage.
Mathematics-based computational mechanics involves idealization in going from the observed behaviour of a system into mathematical equations representing the underlying mechanics of that behaviour. Idealization may le...
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Mathematics-based computational mechanics involves idealization in going from the observed behaviour of a system into mathematical equations representing the underlying mechanics of that behaviour. Idealization may lead mathematical models that exclude certain aspects of the complex behaviour that may be significant. An alternative approach is data-centric modelling that constitutes a fundamental shift from mathematical equations to data that contain the required information about the underlying mechanics. However, purely data-centric methods often fail for infrequent events and large state changes. In this article, a new hybrid modelling framework is proposed to improve accuracy in simulation of real-world systems. In the hybrid framework, a mathematical model is complemented by information-based components. The role of informational components is to model aspects which the mathematical model leaves out. The missing aspects are extracted and identified through Autoprogressive Algorithms. The proposed hybrid modelling framework has a wide range of potential applications for natural and engineered systems. The potential of the hybrid methodology is illustrated through modelling highly pinched hysteretic behaviour of beam-to-column connections in steel frames.
This paper aims at developing a new methodology based on finite element (FE) techniques with a combination of several other methods to extend the component-based design philosophy of EC3 to the cyclic behaviour of end...
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This paper aims at developing a new methodology based on finite element (FE) techniques with a combination of several other methods to extend the component-based design philosophy of EC3 to the cyclic behaviour of end plate connection. In the first part, the experimental procedure for studying the behaviour of an isolated T-stub as the main component of an end plate connection under monotonic and cyclic loading is presented. The second part comprises the four steps necessary to build the analytical model. Firstly the monotonic and secondly the cyclic FE models of these specimens are discussed and validated. Then, a mathematical energy balance model is developed to reproduce the cyclic response. This model is the basis of a mechanical model which predicts the behaviour of a T-stub which constitutes the main component of connections. With these data, a spring model is used to predict the moment rotation curve for an isolated end plate connection. (C) 2000 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved.
In this work, we develop mathematical models describing the interactions between human papillomavirus (HPV)-infected cells and the immune system. We start with simple models in order to capture the most important feat...
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In this work, we develop mathematical models describing the interactions between human papillomavirus (HPV)-infected cells and the immune system. We start with simple models in order to capture the most important features of such interactions. Then, we proceed to consider fundamental immunological characteristics for the models. For the numerical counterpart, we develop and implement efficient numerical discretizations of our models in order to illustrate the behavior of the schemes using different initial conditions, which represent the degree of infection of the disease. Understanding such interactions is of paramount importance for the prevention and the potential eradication of the infection. One main goal of this research is to analyze how and under what circumstances the immune system succeeds in eliminating HPV-infected cells.
作者：
LISTER, GGCRL
Dawley Road Hayes Middlesex UB3 1HH UK
Numerical modelling of plasma systems is proving an increasingly valuable tool in the understanding of fundamental processes in reactors for surface engineering applications. The present paper discusses some of the fu...
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Numerical modelling of plasma systems is proving an increasingly valuable tool in the understanding of fundamental processes in reactors for surface engineering applications. The present paper discusses some of the fundamental physical and mathematical models used to describe plasma behaviour and their range of validity and applicability to plasma reactors. A number of specific examples which illustrate the way in which these methods may be implemented to model plasmas in dc and rf diode reactors and plasma 'ball' microwave reactors are described, with comparison between numerical results, diagnostic measurements and experimental observations from the published literature.
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