A model-driven approach to content repurposing

The multimedia metamodel defines platform-independent multimedia concepts, opening the way for novel approaches to designing content repurposing solutions. Designers can use the metamodel to create content and add metadata to existing content, simplifying content analysis and repurposing. This model-driven approach and proposed design solutions are useful not only for many multimedia designers and researchers, where the model-driven tools can help them create better multimedia interfaces, but also for lecturers and students of multimedia courses. In the latter case, the unified multimedia metamodel offers context for sometimes subtle relationships between multimedia concepts. The metamodel can also facilitate the collaborative creation of broader knowledge about multimedia phenomena. In our future work, we plan to extend the proposed metamodel and include domains from related fields, such as user modeling and intelligent tutoring systems that deal with high-level user models. We are also designing multimodal test environments, reusable multimedia components, and data mining tools for evaluating various aspects of multimedia and multimodal communication.     

Design of computer controlled combustion engines

Globalization and growing new markets, as well as increasing emission and fuel consumption requirements, force the car manufacturers and their suppliers to develop new engine control strategies in shorter time periods. This can mainly be reached by development tools and an integrated hardware and software environment enabling rapid implementation and testing of advanced engine control algorithms.

The structure of a rapid control prototyping (RCP) system is explained, which allows fast measurement signal evaluation, and rapid prototyping of advanced engine control algorithms. A hardware-in-the-loop simulator for diesel engine control design is illustrated, simulation results for a 40 tons truck are presented. Providing efficient engine models for the proposed development tools, a dynamic local linear neural network approach is explained and applied for modelling the NO_x emission characteristics of a 1.9 l direct injection diesel engine. Furthermore the application of a RCP system is exemplified by the application of combustion pressure based closed-loop ignition timing control for a SI engine. Experimental results are shown for a 1.0 l SI engine on a dynamic engine test stand.     

试验设计与仿真相结合构造集成电路元模型的方法研究

集成电路的设计与优化常需要指标与参数简单、直接的模型,即电路的元模型.本文将试验设计与计算机仿真相结合构造集成电路的元模型.讨论了构造元模型中使用的4种试验设计类型与3种模型.结合低功耗集成运算放大器性能指标静态功耗元模型的构造,分析比较了不同方法的各自特点.从结果可以看出,将拉丁超立方抽样与Kriging模型相结合最适合仿真试验中的电路元模型的构造.     

Tool spare management for a single manufacturing cell

This paper uses an L₁₈ orthogonal array design to study and analyze the tool spare management of a single manufacturing cell. The single manufacturing cell operates with two dissimilar workheads. A polynomial regression metamodel approach is developed for machine availability (average equipment utilization) and for the average server utilization. The models presented for these two performance measures are implemented in a decision framework to determine the optimum combinations of spare tools and repair levels. A numerical example is used to illustrate this important concept.     

An Architecture to Define Graphical Metaphors for Metamodels

Domain-Specific Modeling is advancing with tools such as GME (Generic Modeling Environment) and MetaEdit+ among others. The key feature of these tools is that the modeling ontology is close to the problem so that solutions can be designed or developed in a specific domain, where the analyst or the developer is an expert. MOMENT is a model management platform that permits the definition of domain-specific models following an algebraic approach. In this paper, we present an architecture to integrate MOMENT into an industrial visual modeling environment so that their graphical capabilities can be used to visually define algebraic models. To achieve this goal, we identify the common elements of a visual modeling environment, as well as the associations between them and the formal elements of the MOMENT platform. These associations are stored in the same platform using it as a UML-like repository. An implementation for a specific modeling environment has been developed. This solution is presented by defining a graphical view (a graphical metaphor) for a specific algebraic metamodel through its interfaces.     

基于遗传算法的Kriging元模型及其在模拟集成电路优化设计中的应用

提出了建立电路Kriging元模型,并与遗传算法相结合确定电路参数,优化电路的方法.相对传统多项式回归模型,Kriging模型更适合电路仿真的实验类型;利用遗传算法,解决了基于Kriging元模型电路系统的全局优化问题.最后将该方法应用于带隙基准电路设计,取得令人满意的结果.     

基于NARX非线性辨识技术的航空发动机嵌入式机载模型计算机实现

针对航空发动机控制系统中机载模型难以实现的问题,设计一种将NARX非线性辨识模型移植入嵌入式高性能处理器从而实现机载模型的方法。应用NARX非线性辨识技术,对某型涡扇发动机试车数据进行系统辨识并建立实时建模;接着,将辨识模型通过代码生成技术载入TMS320C6747控制模块;最后,经过适当接口修改,完成机载模型计算机的实现并对其进行实验验证。结果表明,所辨识模型具有较高精度,且载入DSP平台后精度可达92%,满足航空发动机系统对机载模型的要求。     

Goal-seeking problem in discrete event systems simulation

For most complex stochastic systems such as microelectronic systems, the Mean Time To Failure (MTTF) is not available in analytical form. We resort to Monte-Carlo Simulation (MCS) to estimate MTTF function for some specific values of underlying density function parameter(s). MCS models, although simpler than a real-world system, are still a very complex way of relating input parameter(s) to MTTF. This study develops a polynomial model to be used as an auxiliary to a MCS model. The estimated metamodel is a Taylor expansion of the MTTF function in the neighborhood of the nominal value for the parameter(s). The Score Function methods estimate the needed sensitivities (i.e. gradient, Hessian, etc.) of the MTTF function with respect to the input parameter in a single simulation run. The explicit use of this metamodel is the target-setting problem in Taguchi's product design concept: given a desired target MTTF value, find the input parameter(s). A stochastic approximation algorithm of the Robbins-Monro type uses a linear metamodel to estimate the necessary controllable input parameter within a desired accuracy. The potential effectiveness is demonstrated by simulating a reliability system with a known analytical solution.     

基于本体的语义Web服务注册平台研究

提出了一种基于本体的语义Web服务注册模型,结合Jena实现语义Web服务的语义查询和推理.应用元模型互操作框架(MFI)中的本体注册元模型标准,以实现与其他注册模型的语义互操作,并给出了一个基于该模型的语义Web服务注册平台.     

基于发动机平均值模型的控制仿真

针对发动机平均值模型进行控制仿真以验证所设计的控制策略对发动机控制的有效性,首先在MATLAB／Simulink中建立发动机的平均值模型,其次分别建立PID控制器和模糊PID控制器对发动机平均值模型进行控制仿真,最后对两种控制器的仿真结果进行比较分析。通过最后的仿真结果可以看出两种控制器都可以稳定控制发动机模型,但模糊PID控制器具有更好的控制效果。发动机是一个非线性、时滞的动力学系统,而模糊控制不需要了解被控对象的特性,故它能精确控制发动机模型。     

基于元模型的复杂航电系统建模

针对当前综合模块化航空电子系统( IMA)开发中存在的问题,提出了一种基于元模型的航电系统建模方法.该方法充分利用了基于特征的元建模理论,通过合理划分和描述构成整体的各部分及其相互关系,构建航电系统领域的元模型.通过建模工具将元模型解释成面向领域的建模语言,在此基础上可构建具体的航电系统模型.以航电系统为实施对象进行了...     

Rule-Based Security Capabilities Matching for Web Services

A primary problem for security aware Web service discovery is how to discover security capabilities of Web services and how these security capabilities can be matched with security requirements of various requesters. Presently, most approaches are based on syntactic matching, which is prone to result in false negative because of lacking of semantics. In this paper, we propose a rule-based approach to decide whether security capabilities match security requirements. Based on a semantic model of security policy, security capabilities are inferred from security policy of Web services. General Web service security ontology is proposed to semantically model security requirements of various service requesters. The architecture of rule-based matching engine is also presented to describe the whole matching process. The prototype system and case study show that the proposed approach is flexible and feasible.     

基于Google搜索引擎的原理及使用

在网络时代,信息检索主要通过Internet搜索引擎进行。Internet提供了多种不同的检索工具,对用户最重要的就是熟悉这些工具的性能,掌握检索技巧,提高检索的命中率。在此从搜索引擎的工作原理开始,介绍了Google搜索引擎的使用方法,包括关键词的选择和几个检索的技巧,如逻辑检索、通配符检索等,能更快、更准确地获得所需要的信息。     

A multi-layered policy generation and management engine for semantic policy mapping in clouds

The long awaited cloud computing concept is a reality now due to the transformation of computer generations. However, security challenges have become the biggest obstacles for the advancement of this emerging technology. A well-established policy framework is defined in this paper to generate security policies which are compliant to requirements and capabilities. Moreover, a federated policy management schema is introduced based on the policy definition framework and a multi-level policy application to create and manage virtual clusters with identical or common security levels. The proposed model consists in the design of a well-established ontology according to security mechanisms, a procedure which classifies nodes with common policies into virtual clusters, a policy engine to enhance the process of mapping requests to a specific node as well as an associated cluster and matchmaker engine to eliminate inessential mapping processes. The suggested model has been evaluated according to performance and security parameters to prove the efficiency and reliability of this multi-layered engine in cloud computing environments during policy definition, application and mapping procedures.     

基于XML和关系型数据库的分布式通用工作流引擎

针对关键业务的应用开发离不开工作流技术的支持。通过对关键业务的实际开发需求的分析，在传统的关系数据库的基础上。结合XHL的结构化、层次化的特征，提出了一个适用于关键业务开发的基于XHL和关系型数据库的分布式通用工作流引擎的框架结构。此工作流模型由信息模型和控制模型两部分组成。文中详细地给出了相关的信息模型和控制模型的设计原理以及具体的表示和实现方法。其原型已经应用于实际系统中，实践证明，利用此工作流引擎可以显著地缩短关键业务的开发周期。     

Requirements for the application of ECUs in e-mobility originally qualified for gasoline cars

Electronic control units (ECUs) are widely spread over the automotive industry with lots of applications. At this time more than 100 ECUs are used in a medium-sized vehicle. Development, test and qualification of ECUs are time and cost extensive. That is why they are often used in more than one generation and more than one model of vehicles. Present ECUs are developed and qualified for vehicles with combustion engines. Since the introduction of hybrid and fully electrical cars the requirements on the ECUs changed drastically. With respect to the engine ECUs temperature maxima is lower. On the other hand due to charging the batteries and other continuous voltage stresses, the time of operation (active and passive) is massively growing. The central question is: Is it possible to use ECUs qualified for gasoline car in electric cars without any reliability risks?To answer this question we start with a comparison of mission profiles of electrical cars and combustion engine cars. Based on the mission profiles we show the different requirements on the electronics robustness and use time. Afterwards we investigate the qualification process of an exemplary ECU from a combustion engine car and identify differences in comparison to the hybrid and fully electrical variant. As an example, a measurement of temperatures in a car driven under reasonably realistic conditions indicates the influence of the combustion engine on the thermal behaviour of the electronics as a key driver for failures. We provide a generic procedure that can be used for the design of future ECUs and compare it with expected temperature distributions in electric cars. Based on our results recommendations for the applicability of the use of existing ECUs in electric cars are discussed.     

油机室送风机自动控制电路设计

油机的正常运行要求油机室必须有良好的通风,对于不能满足通风要求的油机室需要安装送风机强制送风,但目前大多油机室的送风机都是手动控制。文章介绍了一种自行设计的控制电路,能够达到市电供电时风机停止,油机供电时风机自动运行,同时附带了手动控制开关的功能。     

用于稳定激光功率的数字控制系统

在冷原子干涉仪的研究中,常采用三个拉曼光脉冲实现对原子束的相干操控(分束、反射和合束)。拉曼激光的功率抖动会引起Rabi频率的变化,从而带来严重的干涉相移噪声。这些噪声对用于高精度转动加速度测量的冷原子干涉仪来说是不可忽略的系统噪声,因此实现拉曼激光的功率稳定对于实现高精度原子干涉是至关重要的。采用声光调制器(AOM)作为执行器,设计了一套用于稳定激光功率的数字控制系统。在对AOM进行系统辨识和控制器仿真设计的基础上,利用Labview程序实现了激光功率稳定的PID控制。测试结果表明,在测量时间为1 h情况下,激光功率的不稳定度由系统闭环前的1.67%降低到了系统闭环后的0.19%,极大地提高了干涉信号的稳定性,同时也降低了系统噪声。     

Analysis of electromagnetic scattering from a cavity with a complextermination by means of a hybrid ray-FDTD method

The electromagnetic modeling of engine cavities is a very difficult task because the electrical size of the cavity is very large, while the engine termination is geometrically complex. High-frequency techniques can adequately model the cavity, but perform poorly when applied to the termination. Low-frequency techniques are currently infeasible for such large geometries because of the large memory and computation time requirements. The authors present a hybrid method which combines the most attractive features of the lowand high-frequency techniques. The finite-difference time-domain (FDTD) method is applied to the small region surrounding the termination. The remainder of the cavity is modeled with ray methods. To validate this method, they consider two-dimensional cavities with complex terminations. Their results are compared against those found from a hybrid combination of the modal method and the method of moments