A Web surfer model incorporating topic continuity

This paper describes a surfer model which incorporates information about topic continuity derived from the surfer's history. Therefore, unlike earlier models, it captures the interrelationship between categorization (context) and ranking of Web documents simultaneously. The model is mathematically formulated. A scalable and convergent iterative procedure is provided for its implementation. Its different characteristic features, as obtained from the joint probability matrix, and their significance in Web intelligence are mentioned. Experiments performed on Web pages obtained from WebBase confirm the superiority of the model.     

A model for database allocation incorporating a concurrency controlmechanism

The impact of incorporating a specific concurrency control mechanism (CCM) into the file allocation problem (FAP) is discussed. Depending on the specific CCM use, the communication flows in a network will vary. To allocate data optimally, one must identify the exact communication flows in the network. It is this aspect that has been ignored in past research on the FAP. A linear mixed-integer programming model formulated for the FAP is given. The model incorporates the WRITE LOCKS ALL-READ LOCKS ONE mechanism for concurrency control. A special algorithm based on the implicit representation of variable upper bounds is developed to solve the model. Detailed analysis for various configurations of a network is performed. Several potential applications for the model are identified     

A system for articulated tracking incorporating a clothing model

In this paper an approach for motion capture of dressed people is presented. A cloth draping method is incorporated in a silhouette based motion capture system. This leads to a simultaneous estimation of pose, joint angles, cloth draping parameters and wind forces. An error functional is formalized to minimize the involved parameters simultaneously. This allows for reconstruction of the underlying kinematic structure, even though it is covered with fabrics. Finally, a quantitative error analysis is performed. Pose results are compared with results obtained from a commercially available marker based tracking system. The deviations have a magnitude of three degrees which indicates a reasonably stable approach.     

A nonlinear model of center-wound rolls incorporating refined boundary conditions

This article presents a novel approach for determining the displacement, strains and stresses developed in a center-wound roll. The approach consists of a nonlinear model and some refined boundary conditions. The investigation starts with a linear, displacement-based formulation and refined boundary conditions previously developed by the author. The choice of displacement-based formulation, unlike the stress-, or strain-based counterpart, allows for easy determination of relative and absolute displacements, and stress and strain components caused by the relative displacement and by the wound-in stress. The refined boundary conditions, on the other hand, take into account radial displacement compatibility at the core-roll interface, as well as between the current outer surface of the roll and the next wound-on lap, resulting in relaxation of the wound-in stress, or the loss of it. Conventional boundary conditions, on the contrast, consider only radial displacement compatibility at the core-roll interface. The nonlinear model incorporates nonlinear radial modulus of elasticity of the wound roll. It is linearized lap-by-lap, translating the nonlinear problem into a series of linear equations of banded structure. A number of examples are chosen to demonstrate that the approach is accurate, rather simple, able to account for wound-in stress loss and capable of updating web thickness. Furthermore, it can accommodate any form of nonlinear radial modulus of elasticity and any profile of wound-in stress.     

A cardiac pacemaker model incorporating frequency control by the autonomic nervous system

An electronic model of a cardiac pacemaker cell is developed from a study of the Hodgkin—.Huxley equations describing the dynamic behaviour of excitable tissue membranes. The model is based on the functional hypothesis that the controlling factor is the leakage conductance of the membrane to sodium ions and that this is increased by stimulation of the sympathetic nerves and decreased by stimulation of the parasympathetic nerves. The resulting model shows close agreement with experimental results obtained by Levy and Ziesko on the heart of the anaesthetised dog. The model forms part of an circulatory-parameter analogue of the human circulatory system currently being constructed as an aid to studying the manner in which the parameters and control loops of this system adapt to prolonged periods of heavy exercise.     

A model of legal reasoning with cases incorporating theories and values

Reasoning with cases has been a primary focus of those working in AI and law who have attempted to model legal reasoning. In this paper we put forward a formal model of reasoning with cases which captures many of the insights from that previous work. We begin by stating our view of reasoning with cases as a process of constructing, evaluating and applying a theory. Central to our model is a view of the relationship between cases, rules based on cases, and the social values which justify those rules. Having given our view of these relationships, we present our formal model of them, and explain how theories can be constructed, compared and evaluated. We then show how previous work can be described in terms of our model, and discuss extensions to the basic model to accommodate particular features of previous work. We conclude by identifying some directions for future work.     

融入学习者模型在线学习资源协同过滤推荐方法

在线教育存在“信息迷航”问题,而传统的信息推荐方法往往忽视教育的主体—学习者的特征。本文依据教育教学理论,根据在线教育平台中的学习者相关数据,研究构建了适用于在线学习资源个性化推荐的学习者模型。以协同过滤推荐方法为切入点,融合学习者模型中的静态特征和动态特征对协同过滤方法进行改进,建立融入学习者模型的在线学习资源协同过滤推荐方法。以2020年3~7月时间段的东北石油大学“C程序设计”课程学生的真实学习数据和行为数据为数据集,对本文提出的方法进行验证和对比,最后证明本文提出的方法在性能上均优于对比方法。     

Model-based assessment of insulin sensitivity of glucose disposal and endogenous glucose production from double-tracer oral glucose tolerance test

A new mathematical model of short-term glucose regulation by insulin is proposed to exploit the oral glucose tolerance test (OGTT), which is commonly used for clinical diagnosis of glucose intolerance and diabetes. Contributions of endogenous and exogenous sources to measured plasma glucose concentrations have been separated by means of additional oral administration and constant intravenous infusion of glucose labeled with two different tracers. Twelve type 2 diabetic patients (7 males and 5 females) and 10 control subjects (5 males and 5 females) with normal glucose tolerance and matched body mass index (BMI) participated in this study. Blood samples for measurement of concentrations/activity of unlabeled and double-tracer glucose and insulin were collected every 15 min for 3 h following the oral glucose load. A minimal model combined with non-linear mixed-effects population parameter estimation has been devised to characterize group-average and between-patient variability of: (i) gastrointestinal glucose absorption; (ii) endogenous glucose production (EGP), and (iii) glucose disposal rate. Results indicate that insulin-independent glucose clearance does not vary significantly with gender or diabetic state and that the latter strongly affects, as expected, insulin-dependent clearance (insulin sensitivity). Inhibition of EGP, interpreted in terms of variations from basal of insulin concentrations, does not appear to be affected by diabetes but rather by BMI, i.e. by the degree of obesity. This study supports the utility of a minimal modelling approach, combined with population parameter estimation, to characterize glucose absorption, production and disposition during double-tracer OGTT experiments. The model provides a means for planning further experiments to validate the new hypothesis on the influence of individual factors, such as BMI and diabetes, on glucose appearance and disappearance, and for designing new simplified clinical tests.     

A distributed model of water balance in the Motueka catchment,New Zealand

A distributed water balance model is used to simulate the soil moisture regime of the Motueka catchment. The model is a major simplification of the Distributed Hydrology–Vegetation–Soil Model (DHVSM) with modifications suitable for the study area. The model was applied at 25-m resolution with a 1-day time-step for 10 years. The simulated hydrograph showed good correspondence with the observed hydrograph and there was good agreement of simulated and measured mean annual discharges (57.3 m³ s⁻¹ as compared with 58.7 m³ s⁻¹). Five different land cover scenarios were used to predict the effects of vegetation change on the hydrological regime: (1) current land cover; (2) prehistoric land cover; (3) maximum pine planting; (4) pine trees on easy slopes; and (5) pine trees on steep slopes. The pine scenarios all reduced the mean annual flow by about 2 m³ s⁻¹, while the prehistoric scenario reduced the mean annual flow by about 6 m³ s⁻¹. The pine scenarios (3, 4, and 5) reduced the 7-day 5-year low flow from 7.4 m³ s⁻¹ to between 6.5 m³ s⁻¹ and 6.8 m³ s⁻¹, respectively; and the prehistoric scenario reduced the 7-day 5-year low flow to 5.3 m³ s⁻¹.     

SWBACROS: A model for the estimation of the water balance of a cropped soil

The mathematical model SWBACROS (Simulation of the Water BAlance of a CROpped Soil) is presented. The model is based on the numerical solution of the partial differential equation which describes the unsaturated transient water flow in a heterogeneous soil in the presence of a crop. The equation is solved by the Douglas - Jones predictor-corrector method or by the implicit method. Output of the model includes water content and pressure head profiles with respect to time and also fluxes through top and bottom boundary, actual evaporation and actual transpiration. Input data include climatological data necessary for the computation of the potential evapotranspiration by the modified Penman method, rainfall and/or irrigation data and the definition of the different horizons of the soil profile. The model uses the Rosenbrock method to solve the soil parameters estimation problem. Depending on the available information the sum of the squares of the errors of moisture content and pressure head can be chosen as objective function. Estimation of parameters in any horizon(s) is allowed.The model is applied in a soil cultivated with cotton in Central Greece with data collected from 15 April, 1990 to 10 September, 1990. It is also compared with the well known model SWATRE (Belmans et al., 1983). The results are very satisfactory.     

A passive movement method for parameter estimation of a musculo-skeletal arm model incorporating a modified hill muscle model

In this paper we present an experimental method of parameterising the passive mechanical characteristics of the bicep and tricep muscles in vivo, by fitting the dynamics of a two muscle arm model incorporating anatomically meaningful and structurally identifiable modified Hill muscle models to measured elbow movements. Measurements of the passive flexion and extension of the elbow joint were obtained using 3D motion capture, from which the elbow angle trajectories were determined and used to obtain the spring constants and damping coefficients in the model through parameter estimation. Four healthy subjects were used in the experiments. Anatomical lengths and moment of inertia values of the subjects were determined by direct measurement and calculation. There was good reproducibility in the measured arm movement between trials, and similar joint angle trajectory characteristics were seen between subjects. Each subject had their own set of fitted parameter values determined and the results showed good agreement between measured and simulated data. The average fitted muscle parallel spring constant across all subjects was 143 N/m and the average fitted muscle parallel damping constant was 1.73 Ns/m. The passive movement method was proven to be successful, and can be applied to other joints in the human body, where muscles with similar actions are grouped together.     

A novel nonlinear ensemble forecasting model incorporating GLAR and ANN for foreign exchange rates

In this study, we propose a novel nonlinear ensemble forecasting model integrating generalized linear auto-regression (GLAR) with artificial neural networks (ANN) in order to obtain accurate prediction results and ameliorate forecasting performances. We compare the new model's performance with the two individual forecasting models—GLAR and ANN—as well as with the hybrid model and the linear combination models. Empirical results obtained reveal that the prediction using the nonlinear ensemble model is generally better than those obtained using the other models presented in this study in terms of the same evaluation measurements. Our findings reveal that the nonlinear ensemble model proposed here can be used as an alternative forecasting tool for exchange rates to achieve greater forecasting accuracy and improve prediction quality further.     

纳米级MOSFET亚阈值区电流特性模型

基于纳米级金属氧化物半导体场效应晶体管(MOSFET)器件结构,从基本的漂移扩散方程出发,分别建立了亚阈值区漏极电流模型和栅极电流模型。其中将频率与偏置依赖性的影响显式地体现在模型中。通过对比分析发现亚阈值区漏极电流模型具有等比例缩小的可行性,栅极电流具有跟随性和频率依赖性。同时将所建模型的仿真结果与实验结果进行了比较,验证了模型准确性。     

A new general glucose homeostatic model using a proportional-integral-derivative controller

The glucose-insulin system is a challenging process to model due to the feedback mechanisms present, hence the implementation of a model-based approach to the system is an on-going and challenging research area. A new approach is proposed here which provides an effective way of characterising glycaemic regulation. The resulting model is built on the premise that there are three phases of insulin secretion, similar to those seen in a proportional-integral-derivative (PID) type controller used in engineering control problems. The model relates these three phases to a biological understanding of the system, as well as the logical premise that the homeostatic mechanisms will maintain very tight control of the system. It includes states for insulin, glucose, insulin action and a state to simulate an integral function of glucose. Structural identifiability analysis was performed on the model to determine whether a unique set of parameter values could be identified from the available observations, which should permit meaningful conclusions to be drawn from parameter estimation. Although two parameters--glucose production rate and the proportional control coefficient--were found to be unidentifiable, the former is not a concern as this is known to be impossible to measure without a tracer experiment, and the latter can be easily estimated from other means. Subsequent parameter estimation using Intravenous Glucose Tolerance Test (IVGTT) and hyperglycaemic clamp data was performed and subsequent model simulations have shown good agreement with respect to these real data.     

A multicompartment model for open-loop control of glucose in insulin-dependent diabetics

This paper describes a model that has been developed for individually adjusted therapy management in insulin-dependent diabetics. The multicompartment model considers all relevant aspects of glucose kinetics and its dependence on insulin. The structure of the model reflects that of the physiological system. Its parameters can be classified into (a) general parameters that are independent of the individual, (b) classifying parameters that are related systematically to the individual, and (c) distinguishing parameters. Classifying parameters allow a very convenient adjustment to relevant features of the individual like sex, age, body weight and length. The model can be employed in open-loop control for the calculation of insulin dosages. It allows the prediction of the system's behaviour as well as the consideration of predictable disturbance variables, e.g. food intake and physical exercise.     

Structure of equilibrium time-varying trajectories in the Lucas endogenous growth model

A family of time-varying equilibrium trajectories in the well-known Lucas endogenous economic growth model is studied. The equilibrium trajectories are shown to differ not only in level, but also in long-term growth rate under a certain combination of parameters.     

Microeconomic model of residential location incorporating life cycle and social expectations

This paper is focused on the dynamics of residential location decisions based on the microeconomic theory of urban land use, in which we assume that each property is assigned to the agent with the highest bid. The agents' behavior includes expectations of their future based on the life cycle or social influence processes, which are anticipated or solved using a hypothesis of imitation of the behavior of other households currently living in those situations. Relocation decisions are then modeled, incorporating expected utilities by means of transition probabilities among households. An imitation multi-objective bid function is postulated for each alternative location depending on the expected income per unit of time, the current household value of amenities and the expected value obtained by the imitated agent in this location. A multinomial logit model is assumed to calculate the location equilibrium, where willingness to pay is determined by dwelling characteristics and spatial socioeconomic segregation (location externalities). Numerical examples and simulations are presented using linear bid functions to explain the proposed modeling approach and the impact of imitation on the dynamics of residential segregation.     

A promotive structural balance model based on reinforcement learning for signed social networks

Neural Computing and Applications - To solve the structural balance problem in signed social networks, a number of structural balance models have been developed. However, these models neglect the...