Simple Tuning Rules for Integrating Processes with Large Time Delay

In the present article, controllers of the modified Smith predictor are designed for pure integrating, integrating plus first order and double integrating processes with large time delays. The direct synthesis approach is used to tune the set point tracking controller. Suitable values of the desired closed loop time constant that satisfies both robust stability and robust performance conditions are provided based on extensive simulation studies. The PD controller, which is used for load disturbance rejection, is designed so as to achieve a specified slope (ψ) of the Nyquist curve at the gain crossover frequency. The gain crossover frequency that corresponds to a phase margin of 45 degrees is suggested for all three considered integrating processes. Furthermore, ψ is recommended as 45 degrees for double integrating processes and 90 degrees for pure integrating and integrating plus first order process models. Two simulation examples are considered to illustrate the usefulness of the proposed tuning rules.     

Challenges in Continental River Dynamics

Continental River Dynamics (CRD) is herein defined as modelling the flow dynamics in all channels of a continental-scale river basin using the physics-based Saint-Venant equations. At the boundary of hydraulics and hydrology, CRD requires significant collaborative efforts to make new progress. Six constraints and seven challenges are identified in the areas of dynamics, dimensionality, resolution, uncertainty, model coupling, and data availability. Three key short-term needs for CRD are identified as (1) scaling up Saint-Venant river models to continental scales, (2) standards for integrating river and hydrology models, and (3) methods for effective use of lidar data and synthetic methods for approximating geometry for 1D dynamic models. An over-arching need for comprehensive data collection programs for river geometry is discussed.     

Linking perception and action through motivation and affect

Research into cognitive architectures is described within a framework spanning major issues in artificial intelligence and cognitive science. Earlier work on motivation is extended with a cognitive model of reasoning which, together with an affective mechanism, enables consistent decision-making across a variety of cognitive and reactive processes. Cognition involves the control of behaviour within both external and internal environments. The control of behaviour is vital to an autonomous system as it acts to further its goals. Except in the most spartan of environments, the potential available information and associated combinatorics in a perception, cognition, and action sequence can tax even the most powerful agents. The affect magnitude concept solves some problems with BDI models, and allows for adaptive decision-making over a number of tasks in different domains. The cognitive and affective components are brought together using motivational constructs. The generic cognitive model can adapt to different environments and tasks as it makes use of motivational models to direct reactive and situated processes.     

多尺度集值决策信息系统

集值信息系统中的对象的属性值多值化,可以实现对复杂信息更全面的刻画.在传统的集值信息系统中,每个属性只有一个尺度.但在具体应用中,人们往往需要在不同的尺度上处理和分析数据.为此,将多尺度信息系统的粒度转换函数引入集值信息系统中,建立多尺度集值信息系统的理论框架,并讨论该系统的不同尺度间信息粒、粗糙集的关系.在此基础上,...     

The Pythagopod

In 1967 lecture at Yale Architecture School Anne Tyng discussed integrating the five Pythagorean solids into a single shape and suggested the shape as an architectural solid. Christopher Glass aims to sphere the cube in the manner of Buckminster Fuller, but with reference not only to the engineering models he uses but to the cultural models of the Pythagorean proportions as well. The author has developed computer models of the resulting plan at least two scales: the original glass house and a smaller hermitage pod.     

PC机群环境下最短路径并行算法的研究

本文在PC机群环境下,研究了最短路径并行算法。在非循环图网络模型和强连通随机网络模型上对算法的加速比和并行效率进行了实验研究,讨论了在PC机群环境中提高并行性能的方法及不同网络规模和网络模型下算法的加速比和效率。     

归约算法统一描述

归约算法在并行计算中应用广泛,目前有很多归约算法应用于不同的情形。这些归约算法各不相同, 逻辑拓扑是 造成区别的关键 。为了统一描述归约算法,揭示它们的共性,给出了一个逻辑拓扑的定义及其性质。在此基础上,给出了归约算法的统一描述,以利于对归约算法的理解,从而设计适应不同应用和环境的归约算法。该描述也可视为可集成不同语义的归约算法框架,从而有助于设计具有新语义的归约算法。本质上,该统一描述是一个归约算法形式定义,有助于验证归约算法的正确性。     

Informing the evaluation and design of technology in intentional work environments through a focus on artefacts and implicit theories

Observation and analysis of work and computer systems in context can provide valuable information for the evaluation, design and further development of computer systems; however, there are still questions regarding the analysis and utilization of information from field studies. In particular, from a design viewpoint, it is necessary to be able to move from the extensive observational data that is often collected during a field study to information that is relevant for design. In this paper, we discuss the use of theories and models of human–machine interaction to guide the analysis of information gathered during field studies, and illustrate the application of an artefact-based theory with the results from two different and independently conducted case studies. This approach was valuable in structuring information collected in flexible environments, in which models that rely on the normative procedures found in more causal environments may be less useful. In addition to shaping the interpretation of data from the two studies, the use of an artefact-based theory also proved useful in integrating results across the two field studies, to suggest more domain-independent design criteria.     

Flexible real-time mobile robotic architecture based on behavioural models

Behaviour-based models have been widely used to represent mobile robotic systems, which operate in uncertain dynamic environments and combine information from several sensory sources. The specification of complex mobile robotic applications is performed in such models by combining deliberative goal-oriented planning with reactive sensor driven operations. Consequently, the design of mobile robotic architectures requires the combination of time-constrained activities with deliberate time-consuming components. Furthermore, the temporal requirements of the reactive activities are variable and dependent on the environment (i.e. recognition processes) and/or on application parameters (i.e. process frequencies depend on robot speed).In this paper, a real-time mobile robotic architecture to cope with the functional and variable temporal characteristics of behaviour-based mobile robotic applications is proposed. Run-time flexibility is a main feature of the architecture that supports the variability of the temporal characteristics of the workload. The system has to be adapted to the environmental conditions, by adjusting robot control parameters (i.e. speed) or the system load (i.e. computational time), and take actions depending on it. This influence is focused on the ability of the system to select the appropriate activity to be executed depending on the available time, and, to change its behaviour depending on the environmental information. The flexibility of the system is allowed thanks to the definition of a real-time task model and the design of adaptation mechanisms for the regulation of the reactive load.The improvement of the robot quality of service (QoS) is another important aspect discussed in the paper. The architecture incorporates a quality of service manager (QoSM) that allows dynamically monitor analyse and improve the robot performances. Depending on the internal state, on the environment and on the objectives, the robot performance requirements vary (i.e. when the environment is overloaded, global map processes generating high-quality maps are required). The QoSM receives the performance requirements of the robot, and by adjusting the reactive load, the system enables the necessary slack time to schedule the more suitable deliberative processes and hence fulfilling the robot QoS. Moreover, the deliberative load can be scheduled by different heuristic strategies that provide answers of varying quality.     

A meta-model for formulating knowledge-based models of software development

In this paper, we introduce a knowledge-based meta-model which serves as a unified resource model for integrating characteristics of major types of objects appearing in software development models (SDMs). The URM consists of resource classes and a web of relations that link different types of resources found in different kinds of models of software development. The URM includes specialized models for software models for software systems, documents, agents, tools, and development processes. The URM has served as the basis for integrating and interoperating a number of process-centered CASE environments. The major benefit of the URM is twofold: First, it forms a higher level of abstraction supporting SDM formulation that subsumes many typical models of software development objects. Hence, it enables a higher level of reusability for existing support mechanisms of these models. Second, it provides a basis to support complex reasoning mechanisms that address issues across different types of software objects. To explore these features, we describe the URM both formally and with a detailed example, followed by a characterization of the process of SDM composition, and then by a characterization of the life cycle of activities involved in an overall model formulation process.     

The contribution of learner characteristics in the development of computer-based adaptive learning environments

The development of learner models takes an active part in upcoming adaptive learning environments. The purpose of learner models is to drive personalization based on learner and learning characteristics that are considered as important for the learning process, such as cognitive, affective and behavioral variables. Despite the huge amount of theoretical propositions of learner characteristics considered as relevant for learner models, practical payoffs are rather sparse. This study aims to overview the empirical research on the mere value of learner models in the development of adaptive learning environments. The results show that a lot of high-quality studies are situated in a rather shattered research field, building few bridges from theory to practice. We conclude with the call for a theory or framework integrating current and past research results that is able to guide theory-based and systematic empirical research having concrete hypotheses on the merits of learner characteristics in adaptive learning environments.     

HEMET: mathematical model of biochemical pathways for simulation and prediction of HEpatocyte METabolism

Many computer studies and models have been developed in order to simulate cell biochemical pathways. The difficulty of integrating all the biochemical reactions that occur in a cell in a single model is the main reason for the poor results in the prediction and simulation of cell behaviour under different chemical and physical stimuli. In this paper we have translated biochemical reactions into differential equations for the development of modular model of metabolism of a hepatocyte cultured in static and standard conditions (in a plastic multiwell placed in an incubator at 37 degrees C with 5% of CO(2)). Using biochemical equations and energetic considerations a set of non-linear differential equations has been derived and implemented in Simulink((R)). This set of equations mimics some of the principal metabolic pathways of biomolecules present in the culture medium. The software platform developed is subdivided into separate modules, each one describing a different metabolic pathway; they constitute a library which can be used for developing new modules and models to project, predict and validate cell behaviour in vitro.     

A framework for process–solution analysis in collaborative learning environments

One of the most challenging aspects of computer-supported collaborative learning (CSCL) research is automation of collaboration and interaction analysis in order to understand and improve the learning processes. It is particularly necessary to look in more depth at the joint analysis of the collaborative process and its resulting product. In this article, we present a framework for comprehensive analysis in CSCL synchronous environments supporting a problem-solving approach to learning. This framework is based on an observation–abstraction–intervention analysis life-cycle and consists of a suite of analysis indicators, procedures for calculating indicators and a model of intervention based on indicators. Analysis indicators are used to represent the collaboration and knowledge building process at different levels of abstraction, and to characterize the solution built using models of the application domain, the problems to solve and their solutions. The analysis procedures combine analysis of actions and dialogue with analysis of the solution. In this way, the process and the solution are studied independently as well as together, enabling the detection of correlations between them. In order to exemplify and test the framework, the methodological process underlying the framework was followed to guide the implementation of the analysis subsystems of two existing CSCL environments. In addition, a number of studies have been conducted to evaluate the framework's approach, demonstrating that certain modes of collaborating and working imply particular types of solutions and vice versa.     

结合图像数据和HMM模型的卫星传播仿真

实质上信号在信道由于外加噪声和多径效应的影响,接收端所接到的信号是完全随机的,因此大多数的传播模型都是采用统计的方法建立的。根据卫星通信信道传播的特性,掌握在不同环境下信道特性的变化情形,并进一步建立一个准确的信道特性预测模型,来评估不同的用户环境下信号衰落情况。利用隐马尔可夫模型(Hidden Markov Models,HMMs)的统计方法,结合用户所在位置的环境图像来建立预测模型,仿真结果表明,可以得到不错的预测结果。     

Voice: synergy in design and integration

Validating Open System Architecture in Industrial CIM Environments (Voice) is a series of ESPRIT projects addressing computer-integrated manufacturing systems and environments. Voice I was created to experiment with and validate the concepts, methods, and tools for integrating processes in computer-integrated-manufacturing systems and environments, and for optimizing manufacturing systems. One of its major accomplishments was the development of McCIM, the first online implementation of an open-system architecture, Cimosa, for CIM, McCIM uses Petri nets and an integration strategy based on evolution and incremental development to rapidly prototype actual manufacturing systems. The Cimosa architecture and the use of McCIM to validate the Cimosa modeling framework and integrating infrastructure are discussed