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1.
In this paper, we propose a cell-centered finite volume method for advective and normal flows on polyhedron meshes which is second-order accurate in space and time for smooth solutions. In order to overcome a time restriction caused by CFL condition, an implicit time discretization of inflow fluxes and an explicit time discretization of outflow fluxes are used in an iterative procedure. For an efficient computation, an 1-ring face neighborhood structure is introduced. Since it is limited to access unknown variables in an 1-ring face neighborhood structure, an iterative procedure is proposed to resolve the limitation of assembled linear system. Two types of gradient approximations, an inflow-based gradient and an average-based gradient, are studied and compared from the point of numerical accuracy. Numerical schemes are tested for an advective and a normal flow of level-set functions illustrating a behavior of the proposed method for an implicit tracking of a smooth and a piecewise smooth interface.  相似文献   

2.
In this paper, by considering the notion of an MV-algebra, we consider a relationship between rough sets and MV-algebra theory. We introduce the notion of rough ideal with respect to an ideal of an MV-algebra, which is an extended notion of ideal in an MV-algebra, and we give some properties of the lower and the upper approximations in an MV-algebra.  相似文献   

3.
Seated computer work results in prolonged static loading, which has been associated with the development of musculoskeletal disorders. A popular alternative to sitting on an office chair while performing computer work is to sit on an exercise ball. Sitting on an exercise ball might affect static and dynamic aspects of working posture. We monitored posture, muscle activation and spinal shrinkage in 10 females performing a 1-h typing task, while sitting on an office chair with armrests and while sitting on an exercise ball. Sitting on an exercise ball resulted in 33% more trunk motion and in 66% more variation in lumbar EMG. Both of these findings can be considered to be an advantage for the exercise ball. However, the fifth percentile and average lumbar EMG were also higher when sitting on an exercise ball, with 38% and 78%, respectively. In addition, more spinal shrinkage occurred when sitting on an exercise ball than when sitting on an office chair. Arm flexion was reduced, but trapezius activation was unaffected when sitting on an exercise ball. It is concluded that the advantages with respect to physical loading of sitting on an exercise ball may not outweigh the disadvantages.  相似文献   

4.
Emmanuel Moulay 《Automatica》2008,44(11):2981-2984
In this paper, we provide an explicit homogeneous feedback control with the requirement that a control Lyapunov function exists for an affine control system and satisfies an homogeneous condition. We use a modified version of the Sontag formula to achieve our main goal. Moreover, we prove that the existence of an homogeneous control Lyapunov function for an homogeneous affine system leads to an homogeneous closed-loop system by using the previous feedback control.  相似文献   

5.
提出了以Intranet为基础 ,针对企业的实际现状 ,为企业进行管理咨询 ,选择适合企业的经营管理模式 ,并将其融入系统中 ,建立企业的集成化信息系统的设想。并以上海精艺纺织制品厂为实例 ,介绍了基于B/S架构的企业集成化信息系统的整体框架  相似文献   

6.
在用PowerBuilder开发数据库应用程序时,经常需要配置ODBC数据源.手工配置ODBC不符合专业软件的要求,本文给出了一个在Windows系统中自动配置ODBC数据源的方法.  相似文献   

7.
XML Schema Definition (XSD) is the logical schemas of an XML model, but there is no standard format for the conceptual schema of an XML model. Therefore, we propose an XML Tree Model (XTM) as an XML conceptual schema for representing data semantics in a diagram, and also as an XML data model validator for confirming the data semantics required by users. An XTM consists of hierarchical nodes representing all the elements, and the data relationships among elements within the XSD. A rule-based algorithm and an information capacity with pre- and post-conditions are developed as the methodology for reverse engineering. The proposed algorithm consists of two rules: General Information Transformation and Data Semantic Recovering to construct an XTM. Users can draw an XTM with data relationships among elements as a result of the reverse engineering.  相似文献   

8.
《国际计算机数学杂志》2012,89(3-4):171-188
The node-visit optimal (NVO) and the space-cost optimal (SCO) height-balanced (HB) 2-3 brother trees are defined. The characterization of the NVO HB 2-3 brother trees is developed. This characterization leads to a linear-time algorithm for constructing an NVO HB 2-3 brother tree for an ordered set of keys. The minimum space-cost of an N-key NVO HB2-3 brother tree and the space-cost of an N-key SCO HB 2-3 brother tree is analysed. It is shown that the minimum space-cost of an NVO HB 2-3 brother tree is never more than one plus the space-cost of an SCO HB 2-3 brother tree. Further, the minimum node-visit cost of an SCO HB 2-3 brother tree is at most one plus the node-visit cost of an NVO HB 2-3 brother tree. It is also shown that there exists an HB 2-3 brother tree which is both SCO and NVO for just over half the possible values of keys. Finally, an outline for constructing an SCO HB 2-3 brother tree is presented.  相似文献   

9.
The component’s interaction points with the external world play a fundamental role in the specification of an application’s architecture. Current software architecture approaches consider an interaction point as an atomic element in the specification of interconnections, despite the complexity of its structure and the attached behavior. It is not possible in current component models to deal separately with an element of an interaction point when such an element is needed alone for specifying a specific logic. To support such logic and the specification of a wide range of early ideas in the process of elaborating a software system, the Integrated Approach to Software Architecture (IASA) uses an interaction point model which provides facilities to manipulate any structural or behavioral element defining an interaction point. In addition, such facilities represent the fundamental foundation of the native support by IASA of Aspect Oriented Software Architectures (AOSA) specifications.  相似文献   

10.
In this article an interface between a high-level specification of a system and a logic controller of that system is developed. The interface is based on a number of rules to transform an IDEF0 specification into an intermediate-level Petri-net-based controller and to transform the intermediate specification into a ladder logic program which can be run on a PLC. These rules could be used as a basis for developing an expert system to handle the interface. Such an expert system provides an environment for rapid prototyping and analysis of controllers.  相似文献   

11.
In this paper, we introduce an approximate model and propose a piecewise optimisation method to simplify the expression of optimal control for an uncertain linear quadratic optimal control problem. First, we consider an optimal control problem of uncertain linear quadratic model under optimistic value criterion. Based on the equation of optimality, we deduce an analytic expression of optimal control. Then, we study an approximate model with control parameter and propose a piecewise optimisation method for solving the optimal parameter of such an approximate model. As an application, a four-wheel steering vehicle optimal control problem is given to show the utility of the proposed approximate model and the efficiency of the proposed piecewise optimisation method.  相似文献   

12.
协议测试中的互操作性测试是保证不同厂商通信设备之间能够正确实施互操作的主要工程测试方法。针对互操作性测试过程中缺乏形式化测试框架和测试方法指导而导致无法保证测试可靠性的问题,在介绍ETSI定义的通用互操作性测试模型基础上,提出一个基于互操作性状态机的互操作性测试方法。通过一个面向IPsec VPN的互操作性测试实例表明该方法的有效性和可行性。  相似文献   

13.
张盛  李芳 《中文信息学报》2015,29(1):163-169
微博作为一种新兴媒体,已经在人们生活中扮演了一种不可或缺的角色。如何从大量微博中抽取出有意义的评价对象并识别出正确的情感倾向显得越来越重要。本文在传统的CRF模型基础上,提出了两步CRF模型及迭代两步CRF模型,对评价对象和极性进行抽取。两步CRF模型在COAE2014评测语料上取得了0.505的F值,迭代两步CRF模型通过不断增加训练语料,提高了召回率,使得F值达到了0.513,同时提高了模型的稳定性。实验对比了当前主流的几种方法,结果证明了本文提出的方法是行之有效的。  相似文献   

14.
This paper investigates an observer‐based event‐triggered control problem of singularly perturbed systems with saturating actuator. A strategy that consists of an observer‐based controller (OBC) and an event‐triggered mechanism (ETM) is considered. Firstly, sufficient conditions, which guarantee that the saturated SPSs are asymptotically stable excluding Zeno phenomenon, are derived via constructing an ε‐dependent Lyapunov‐Krasovskii functional. Then, the OBC and ETM are designed simultaneously based on the aforementioned criteria. Furthermore, an estimate of the basin of attraction and an ε‐bound are given by solving an optimization problem in the form of LMIs. Finally, an electric circuit system and a numerical example are presented to demonstrate the merits of the obtained method.  相似文献   

15.
基于蕴涵的区间值直觉模糊粗糙集   总被引:3,自引:0,他引:3  
张植明 《控制与决策》2010,25(4):614-618
提出一种基于区间值直觉模糊蕴涵的区间值直觉模糊粗糙集模型.首先,介绍了区间值直觉模糊集、区间值直觉模糊关系和区间值直觉模糊逻辑算子的概念;然后,利用区间值直觉模糊三角模和区间值直觉模糊蕴涵,在区间值直觉模糊近似空间中定义了区间值直觉模糊集的上近似和下近似;最后,给出并证明了这些近似算子的一些性质.  相似文献   

16.
近几年来,MCM技术在许多方面应用越来越广泛,本文着重介绍了MCMX工艺的实现过程,并以54HCT04为例,用倒装焊的方法,制造出了具有一定功能的电路模块。  相似文献   

17.
By analogy with a Software Requirements Specification (SRS), it is argued that a Method Requirements Specification (MRS) should be introduced in method engineering. It shares with the SRS the property of implementation-independence. This means that an MRS must be an instance of an abstract metamodel and not of a technical metamodel like GOPRR (Graph, Object, Property, Relationship, and Role). The MRS is then translated to be an instantiation of a technical metamodel. We develop a representation system for an MRS and describe an automated process for instantiating a technical metamodel with an MRS. This instantiation is used to produce the actual method which is then given to a metaCASE to produce a CASE tool. Thus, we propose a method engineering approach rooted in the MRS.  相似文献   

18.
目前的研究认为人工智能的核心是数据、算法和算力,但因素在形成人工智能系统过程中是必不可少的。论文针对人工系统中的数据、算力、算法和因素的各自作用,及其相互关系进行了探讨和论证。从人工系统的内涵出发,描述人工系统的发展过程,认为目前和今后的人工系统必将具有人工智能特征,而实现人工系统要充分考虑上述四方面的相互作用。研究结果表明:数据是人工系统辨识因素的基础,也是形成算法的基础;因素是人工系统控制自然系统的方法及算法所需变量;算法体现了因素与数据关系,可描述人工系统结构;算力是解算算法的能力,也需考虑数据和因素的特征。因此因素在人工系统建立过程中与数据、算法和算力具有相同的重要性。它们具有明显的作用关系,且普遍存在于各个学科,是形成各学科理论基础体系的关键。  相似文献   

19.
VALENCE is an interactive visualisation controlled by live brainwave monitoring. We used a wireless EEG headset to monitor the player's alpha waves (an indicator of relaxation) and valence (an indicator of emotion or arousal). The game world is an emergent system of attractive and repulsive forces responding to EEG input.  相似文献   

20.
We have established a technique for changing part of an active layer of an oxide semiconductor (OS) to a transparent electrode in order to achieve an aperture ratio of 50% or higher and a bezel width of 1 mm in an fringe field switching (FFS) mode LCD panel with a high resolution of 513 ppi. Furthermore, we have prototyped an LCD panel by examining a driving mode that enables low‐frequency driving.  相似文献   

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