基于定量模型的定性控制

本文定义了定性量及定性运算,对模型中含有不确定性因素的非线性系统给出了基于定量模型的定性控制方法。文中首先给出控制的“期望曲线”,然后对对象输出及其它重要项做定性划分,而后利用不精确模型,运用定性运算,求取控制的定性值以使对象输出逼近“期望曲线”,最后实时控制时对控制量自学习调整,所设计系统品质优良。     

带有目标偏好的最大成功联盟生成算法*

资源结盟博弈(CRGs)研究均假设每个agent可以响应所有目标,即使目标不在其感兴趣的子目标集内.针对此问题,文中提出带有目标偏好的CRGs模型,即每个agent只愿意把自己的有限资源贡献给自己的兴趣集中的目标.此外,设计基于二维二进制编码的最大成功联盟生成算法,并提出编码修正启发式算法解决多个目标竞争同一agent资源可能引起的的资源冲突.最后,通过与已有相关算法的对比实验验证文中算法的有效性.     

Conformance Testing of Hybrid Systems with Qualitative Reasoning Models

Embedded systems are of growing importance in industry. For example, in a today's vehicle a huge number of embedded and communicating systems can be found. Exhaustive testing of such systems is a requirement, because changes after delivery and use are expensive and sometimes even impossible. In this paper we propose the use of qualitative models, which are an abstraction of quantitative physical models, for test case generation and test execution. In particular, we show how Simulink models from which control programs are automatically extracted can be tested with respect to qualitative models. Since Simulink models are heavily used in industry, the approach is of practical interest.     

Structural Shape Indexing with Feature Generation Models

Structural indexing is a potential approach to efficient classification and retrieval of image patterns with respect to a very large number of models. This technique is based on the idea of distributing features associated with model identifiers over a large data structure prepared for a model set, along with classification by voting for models with reference to the extracted features. Essential problems caused by mapping image features to discrete indices are that indexing is sensitive to noise, scales of observation, and local shape deformations, and thata prioriknowledge and feature distributions of corrupted instances are not available for each class when a large number of training data are not presented. To cope with these problems, shape feature generation techniques are incorporated into structural indexing. An analysis of feature transformations is carried out for some particular types of shape deformations, leading to feature generation rules composed of a small number of distinct cases. The rules are exploited to generate features that can be extracted from deformed patterns caused by noise and local shape deformations. In both processes of model database organization and classification, the generated features by the transformation rules are used for structural indexing and voting, as well as the features actually extracted from contours. The effectiveness of the proposed method is demonstrated by experimental trials with a large number of sample data. Furthermore, its application to shape retrieval from image databases is mentioned. The shape feature generation significantly improves the classification accuracy and efficiency.     

Learning Qualitative Models of Dynamic Systems

The automated construction of dynamic system models is an important application area for ILP. We describe a method that learns qualitative models from time-varying physiological signals. The goal is to understand the complexity of the learning task when faced with numerical data, what signal processing techniques are required, and how this affects learning. The qualitative representation is based on Kuipers' QSIM. The learning algorithm for model construction is based on Coiera's GENMODEL. We show that QSIM models are efficiently PAC learnable from positive examples only, and that GENMODEL is an ILP algorithm for efficiently constructing a QSIM model. We describe both GENMOEL which performs RLGG on qualitative states to learn a QSIM model, and the front-end processing and segmenting stages that transform a signal into a set of qualitative states. Next we describe results of experiments on data from six cardiac bypass patients. Useful models were obtained, representing both normal and abnormal physiological states. Model variation across time and across different levels of temporal abstraction and fault tolerance is explored. The assumption made by many previous workers that the abstraction of examples from data can be separated from the learning task is not supported by this study. Firstly, the effects of noise in the numerical data manifest themselves in the qualitative examples. Secondly, the models learned are directly dependent on the initial qualitative abstraction chosen.     

Solution of Nonlinear Rational Expectations Models with Applications toFinite-Horizon Life-Cycle Models of Consumption

This paper considers the solution of nonlinear rationalexpectations models resulting from the optimality conditions of afinite-horizon intertemporal optimization problem satisfying Bellman'sprinciple of optimality (and possibly involving inequality constraints). Abackward recursive procedure is used to characterize and solve thetime-varying optimal decision rules generally associated with these models.At each stage of these backward recursions, either an analytical ornumerical solution of the optimality conditions is required. When ananalytical solution is not possible, a minimum weighted residual approach isused. The solution technique is illustrated using a life-cycle model ofconsumption under labor income and interest rate uncertainties (and possiblyinvolving liquidity constraints). Approximate numerical solutions areprovided and compared with certainty-equivalent solutions and, whenpossible, with exact solutions.     

Approximate Solution of Queueing Models

A variety of phenomena and interactions defy exact analytic modeling. Approximation can provide a reasonably accurate solution of a realistic model and is computationally inexpensive.     

定性方向关系模型研究进展

空间关系形式化模型的发展是空间推理、地理信息系统(GIS)、机器人导航等领域的一个非常重要的研究内容,近年来受到相关领域研究者的极大重视。空间对象的方向关系模型的研究已经取得了一定的进展。本文介绍了近年来空间对象的方向关系形式化模型的主要研究内容、研究方法和研究进展,对已有的方向关系模型做了比较,并探讨了目前存在的问题和今后的发展方向。     

车辆产生仿真模型

从满足交通仿真需求角度分析了车辆产生模块建模的特点,提出了详细的车辆产生仿真模型,该模型能准确细致地仿真初始车辆产生的全过程,为交通仿真模型真实的反映路网交通状态奠定了基础.     

定性立体形状表达和建模方法

概念设计在整个产品开发过程中的地位越来越重要,计算机辅助概念设计是计算机辅助设计的发展方向之一。传统的产品建模技术由于不能在产品开发的初期阶段很好地为产品的设计服务,因此有必要研究和开发面向产品概念设计的新的产品建模方法。本文介绍了一种基于领域和领域关系的定性立体形状表达方法和建模方法。该方法满足了概念设计对形状表达的要求,并能简化定性立体构筑过程。     

Multi-Agent Constraint Systems with Preferences: Efficiency, Solution Quality, and Privacy Loss

In this paper, we consider multi-agent constraint systems with preferences, modeled as soft constraint systems in which variables and constraints are distributed among multiple autonomous agents. We assume that each agent can set some preferences over its local data, and we consider two different criteria for finding optimal global solutions: fuzzy and Pareto optimality. We propose a general graph-based framework to describe the problem to be solved in its generic form. As a case study, we consider a distributed meeting scheduling problem where each agent has a pre-existing schedule and the agents must decide on a common meeting that satisfies a given optimality condition. For this scenario we consider the topics of solution quality, search efficiency, and privacy loss, where the latter pertains to information about an agent's pre-existing meetings and available time-slots. We also develop and test strategies that trade efficiency for solution quality and strategies that minimize information exchange, including some that do not require inter-agent comparisons of utilities. Our experimental results demonstrate some of the relations among solution quality, efficiency, and privacy loss, and provide useful hints on how to reach a tradeoff among these three factors. In this work, we show how soft constraint formalisms can be used to incorporate preferences into multi-agent problem solving along with other facets of the problem, such as time and distance constraints. This work also shows that the notion of privacy loss can be made concrete so that it can be treated as a distinct, manipulable factor in the context of distributed decision making.     

Acquiring Both Constraint and Solution Preferences in Interactive Constraint Systems

Constraints are useful to model many real-life problems. Soft constraints are even more useful, since they allow for the use of preferences, which are very convenient in many real-life problems. In fact, most problems cannot be precisely defined by using hard constraints only.However, soft constraint solvers usually can only take as input preferences over constraints, or variables, or tuples of domain values. On the other hand, it is sometimes easier for a user to state preferences over entire solutions of the problem.In this paper, we define an interactive framework where it is possible to state preferences both over constraints and over solutions, and we propose a way to build a system with such features by pairing a soft constraint solver and a learning module, which learns preferences over constraints from preferences over solutions. We also describe a working system which fits our framework, and uses a fuzzy constraint solver and a suitable learning module to search a catalog for the best products that match the user's requirements.     

点度精确的随机网络模型

文章针对Waxman模型提出了两种使用方便、平均点度精确的网络模型:PD1和PD2。并对几种主要模型通过实验进行了对比。结果表明,新方法产生的随机网络几乎在任何尺寸下都很接近实际的网络。同时,文中方法可使网络节点的平均点度非常精确,几乎等于预设的度。     

Web服务选择中偏好不确定问题的研究

应用偏好进行服务选择是Web领域的重要研究方向.在偏好研究中,偏好信息的获得是一个复杂的过程,特别是获取的过程涉及到普通的非专家用户.获取的偏好经常会遇到偏好不完整、偏好冲突的问题,在实际应用中带来很多的问题.文中以条件偏好表示工具CP-net建模用户的偏好,总结了CP-net中出现的不确定性,定义了偏好不完整、偏好冲突.提出了CP-net对应的结果集合上的最优关系与弱化的最优关系.通过CP-net与对应最优关系的分析,提出了CP-net交运算.在此基础上,提出了解决CP-net中不确定问题的方法,并对这个方法进行了优化.最后的实验证明了文中所提出方法的正确性和有效性.     

实体模型的多分辨率中轴生成

针对模型降维的需要,提出一种实体模型的多分辨率中轴生成方法.首先根据模型的层次寻找模型中需要细化的部分,并据此对边界进行体素化;其次使用距离蔓延的方法计算多分辨率体素的距离;最后根据体素的距离计算出多分辨率的中轴体素.实验结果表明,该方法可以以低时间空间代价生成高质量的多分辨率中轴.     

Explanation-Based Scenario Generation for Reactive System Models

Reactive systems control many useful and complex real-world devices. Tool-supported specification modeling helps software engineers design such systems correctly. One such tool, a scenario generator, constructs an input event sequence for the spec model that reaches a state satisfying given criteria. It can uncover counterexamples to desired safety properties, explain feature interactions in concrete terms to requirements analysts, and even provide online help to end users learning how to use a system. However, while exhaustive search algorithms such as model checkers work in limited cases, the problem is highly intractable for the functionally rich models that correspond naturally to complex systems engineers wish to design. This paper describes a novel heuristic approach to the problem that is applicable to a large class of infinite state reactive systems. The key idea is to piece together scenarios that achieve subgoals into a single scenario achieving the conjunction of the subgoals. The scenarios are mined from a library captured independently during requirements acquisition. Explanation-based generalization then abstracts them so they may be coinstantiated and interleaved. The approach is implemented, and I present the results of applying the tool to 63 scenario generation problems arising from a case study of telephony feature validation.     

SIGNAL模型多线程代码生成研究

反应式系统是指与环境不断发生交互的控制系统。这类系统通过接收外部环境输入,对输入进行计算,并将计算结果反馈到外部环境来控制系统的行为。同步语言是一种规约反应式系统的建模语言,同步语言的优势在于支持形式化验证和精确的代码自动生成。面向多时钟同步语言SIGNAL,提出了一种SIGNAL模型到多线程Java代码生成过程。该代码生成过程基于以下3种中间结构:同步时钟卫式操作、卫式操作和带划分的卫式操作。将整个代码生成过程分为4个主要转化步骤,给出每一步转化规则。最后对空客A340的警报系统进行实例分析,评估生成代码的正确性。多线程Java代码生成可以为SIGNAL模型在分布式和多核体系下的应用提供支撑。     

A Hybrid Metaheuristic for the Efficient Solution of GARCH with Trend Models

GARCH with trend models represent an efficient tool for the analysis of different commodities via testing for a linear trend in the volatilities. However, to obtain the volatility of a given time series an instance from a particular class of scalar optimization problems (SOPs) has to be solved which still represents a challenge for existing solvers. We propose here a novel algorithm for the efficient numerical solution of such global optimization problems. The algorithm, DE–N, is a hybrid of Differential Evolution and the Newton method. The latter is widely used for the treatment of GARCH related models, but cannot be used as standalone algorithm in this case as the SOPs contain many local minima. The algorithm is tested and compared to some state-of-the-art methods on a benchmark suite consisting of 42 monthtly agricultural commodities series of the Mexican Consumer Price Index basket as well as on two series related to international prices. The results indicate that DE–N is highly competitive and that it is able to reliably solve SOPs derived from GARCH with trend models.