A novel change feature-based approach to predict the impact of current proposed engineering change

The past engineering change (EC) knowledge can be reused to evaluate the impact of current proposed EC, which is gradually accepted as an effective strategy for engineers to handle EC businesses in enterprises. However, the existing approaches to evaluate EC impact are still time-consuming and complex. So this paper proposes a novel change feature-based approach to predict the impact of current proposed EC. Firstly, the related concepts of change feature are defined. Secondly, the working flow of proposed approach is introduced. Afterwards, a mathematical model is constructed for the prediction of EC impact. Finally, an application case verifies the feasibility of the proposed approach, and the evaluation against two state-of-the-art approaches (namely Mehta’s approach and k-Nearest Neighbor approach) has been done. The results of evaluation show that our approach is better than the two approaches in terms of three indexes: (a) the success rate of prediction, (b) the time of prediction, and (c) the loss function.     

Integration of engineering change objects in product data management databases to support engineering change analysis

This study proposes a product data management (PDM) database that can support engineering change analysis (ECA). It can integrate ECA with the existing main product development process managed by PDM systems. Since engineering change (EC) history is a key EC data element that enables ECA, this study extends PDM databases to represent the EC history with existing entities for ECs and associated products and their product structures. To show the feasibility of the proposed PDM database, this study integrates a prototype PDM system with on-line analytical processing (OLAP) tools and a data mining module for ECA. It also applies the implemented tools to two typical ECA applications, EC evaluation and EC propagation problems. The illustrative application examples show that the proposed PDM database can support ECA through multidimensional data analysis with OLAP and data mining with association rules.     

基于有向图的工程变更传播分析的研究

论文提出了基于有向图的工程变更传播分析方法;开发了采用该方法进行 工程变更分析的软件系统;分析了工程变更中零件变更的传播、协调、吸收和控制等主要问 题;提出了传播模图和传播实图的概念;阐述了传播模图的数据结构、生成算法和使用它引 导工程变更分析的过程。该文用传播实图记录零件变更的传播范围及各个变更零件的变更计 划与影响评估;提出了案例的建立和重用方法,促进历史变更经验使用。使用这种方法和系 统,可以使工程变更分析与评估更加严密、高效。     

企事业过程工程环境EPMS的资源组织结构研究与实现

分析了目前企事业过程工程环境资源组织结构现状，给出了将EPMS的单层资源组织结构扩展为多层资源组织结构的原理及实现，对其它的过程工程环境具有一定的借鉴作用。     

Development of a web-based system for engineering change management

Engineering changes (ECs) are changes and/or modifications in forms, fits, functions, materials, dimensions, etc., of products and constituent components. ECs usually induce a series of downstream changes. Multiple disciplines and responsibilities are therefore involved in managing ECs. Previous investigations conducted by the authors and other researchers have shown that paper-based and standalone computerised EC management (ECM) systems have limited support for such intensive teamwork and close communication. This paper proposes to establish a web-based framework that supports ECM procedures and activities. A web-based ECM system is able to provide better information sharing, simultaneous data access and processing and more prompt communication and feedback. The amount of paperwork and the throughput time of managing ECs are significantly reduced while the effectiveness and the efficiency are substantially improved. This paper focuses on discussing the issues of design, development, and implementation of this prototype web-based ECM system.     

Assessment of process improvement from organizational change

In order to enhance their performance, many organizations have initiated change projects. However, management is reluctant to initiate them due to their enterprise-wide impact and costs that are higher than those of traditional system development projects. Thus, there is a need to assess the value of the redesigned process of a successfully implemented organizational change projects. The purpose of this study was therefore to assess process improvement from organizational change in the areas of resource utilization and allocation and cycle time and cost reduction. The candidate process and design alternatives were identified from organizational requirements analysis. The variables and their relations were defined to perform task activity analysis, bottleneck analysis, cycle cost analysis, and resource utilization analysis. A case study of a manufacturing company indicated that the assessment method was a promising approach for identifying alternative processes that leads to better organizational performance.     

云计算环境下兼顾买卖双方利益的双向拍卖资源分配算法

针对当前云计算环境下的资源分配算法不能充分考虑买卖双方利益的问题,本文提出了一种适用于云计算环境的组合双向拍卖资源分配模型。首先,初始化云经纪人列表和供应商报价列表,拍卖人通知拍卖参与者拍卖开始;然后,根据属性值按升序排序云经纪人请求和云服务供应商报价列表,从而确定投标获胜者;最后,获胜的云经纪人向相关云服务供应商发送任务并支付费用,云服务商执行任务。仿真实验使用CloudSim原型化,在基于Java的仿真云环境中从经济角度进行了效率评估。仿真结果表明,本文模型适用于云环境中的资源分配,在经济上非常有效。相比其他的现有模型,本文模型更能鼓励参与者在买卖双方公平公正的前提下根据真实估值竞购资源。     

并行工程中工程更改的管理及应用实例

文章对并行工程环境下工程更改管理的需求作了分析,将工程更改分类为有意更改和无意更改两种不同的类型,并分别对它们进行了过程建模。指出若干的工程更改管理的方法,作为验证,给出了铁路货车产品设计中工程更改的实例。     

An attribute-based and object-oriented approach with system implementation for change impact analysis in variant product design

Variant product design is critical to the continued survival of a product in the demand-changing market. As variant product design involves numerous and concurrent attempts at requirement and product modification, a change impact analysis (CIA) becomes essential in order to capture both the potential and contextual impacts of a change proposal, and thereby ensure the consistency of the product’s integrated content throughout the process of carrying out any changes. In this regard, this paper presents an attribute-based, object-oriented approach for effectively and comprehensively performing the CIA tasks in variant product design. This approach models the integrated content of a product by characterizing its components and associated requirements with attributes and linkages. It then features an object-oriented change propagation design in order to handle the dynamic and recursive CIA loops. This approach is also able to show the collective impact when multiple changes are attempted. A computerized prototype, EPCII_EC, is implemented in order to realize the approach, and an illustrative product case with a comparative evaluation is provided in order to validate the work. Issues and limitations of this study are also discussed and suggestions are provided for future studies.     

Capturing and reusing knowledge in engineering change management: A case of automobile development

The development of complex products, such as automobiles, involves engineering changes that frequently require redesigning or altering the products. Although it has been found that efficient management of knowledge and collaboration in engineering changes is crucial for the success of new product development, extant systems for engineering changes focus mainly on storing documents related to the engineering changes or simply automating the approval processes, while the knowledge that is generated from collaboration and decision-making processes may not be captured and managed easily. This consequently limits the use of the systems by the participants in engineering change processes. This paper describes a model for knowledge management and collaboration in engineering change processes, and based on the model, builds a prototype system that demonstrates the model’s strengths. We studied a major Korean automobile company to analyze the automobile industry’s unique requirements regarding engineering changes. We also developed domain ontologies from the case to facilitate knowledge sharing in the design process. For achieving efficient retrieval and reuse of past engineering changes, we used a case-based reasoning (CBR) with a concept-based similarity measure.

A step toward STEP-compatible engineering data management: the data models of product structure and engineering changes

In an iterative design process, there is a large amount of engineering data to be processed. Well-managed engineering data can ensure the competitiveness of companies in the competitive market. It has been recognized that a product data model is the basis for establishing engineering database. To fully support the complete product data representation in its life cycle, an international product data representation and exchange standard, STEP, is applied to model the representation of a product. In this paper, the architecture of an engineering data management (EDM) system is described, which consists of an integrated product database. There are six STEP-compatible data models constructed to demonstrate the integratibility of EDM system using common data modeling format. These data models are product definition, product structure, shape representation, engineering change, approval, and production scheduling. These data models are defined according to the integrated resources of STEP/ISO 10303 (Parts 41-44), which support a complete product information representation and a standard data format. Thus, application systems, such as CAD/CAM and MRP systems, can interact with the EDM system by accessing the database based on the STEP data exchange standard.     

产品与供应链协同演进系统变更设计研究进展

产品与供应链协同演进系统是智能制造领域极为关心的一类复杂系统,变更设计又是降本增效、抵御意外风险、提高产品质量和用户满意度的重要手段.本文综述近年来产品与供应链协同演进系统变更设计研究所取得的最新进展.首先阐明产品与供应链协同演进系统变更设计的基本概念,剖析产品与供应链协同演进系统的本质,介绍变更设计的内涵、起因、过程及内容.其次,重点概括产品与供应链协同设计和变更效应传播两大范畴,主要归纳协同设计与变更效应传播分析、预测及控制等研究现状.最后,根据产品与供应链协同演进系统的复杂特性,指出该系统变更设计研究的开放问题,展望该研究的发展趋势.     

Remote sensing change detection tools for natural resource managers: Understanding concepts and tradeoffs in the design of landscape monitoring projects

Remote sensing provides a broad view of landscapes and can be consistent through time, making it an important tool for monitoring and managing protected areas. An impediment to broader use of remote sensing science for monitoring has been the need for resource managers to understand the specialized capabilities of an ever-expanding array of image sources and analysis techniques. Here, we provide guidelines that will enable land managers to more effectively collaborate with remote sensing scientists to develop and apply remote sensing science to achieve monitoring objectives. We first describe fundamental characteristics of remotely sensed data and change detection analysis that affect the types and range of phenomena that can be tracked. Using that background, we describe four general steps in natural resource remote sensing projects: image and reference data acquisition, pre-processing, analysis, and evaluation. We emphasize the practical considerations that arise in each of these steps. We articulate a four-phase process that guides natural resource and remote sensing specialists through a collaborative process to articulate goals, evaluate data and options for image processing, refine or eliminate unrealistic paths, and assess the cost and utility of different options.     

A fast HTML web page change detection approach based on hashing and reducing the number of similarity computations

This paper describes a fast HTML web page detection approach that saves computation time by limiting the similarity computations between two versions of a web page to nodes having the same HTML tag type, and by hashing the web page in order to provide direct access to node information. This efficient approach is suitable as a client application and for implementing server applications that could serve the needs of users in monitoring modifications to HTML web pages made over time, and that allow for reporting and visualizing changes and trends in order to gain insight about the significance and types of such changes. The detection of changes across two versions of a page is accomplished by performing similarity computations after transforming the web page into an XML-like structure in which a node corresponds to an open–close HTML tag. Performance and detection reliability results were obtained, and showed speed improvements when compared to the results of a previous approach.     

Comparison of simulation models in terms of quantity and allocation of land change

Our article illustrates how to compare the outputs from models that simulate transitions among categories through time. We illustrate the concepts by comparing two land change models: Land Change Modeler and Cellular Automata Markov. We show how the modeling options influence the quantity and allocation of simulated transitions, and how to compare output maps from pairs of model runs with respect to a reference map of transitions during the validation interval. We recommend that the first step is to assess the quantity of each transition and to determine the cause of the variation in quantity among model runs. The second step is to assess the allocation of transitions and to determine the cause of the variation in allocation among model runs. The separation of quantity and allocation of the transitions is a helpful approach to communicate how models work and to describe pattern validation.     

基于多智能体与GIS城市土地利用变化仿真研究*

摘要：为动态模拟城市土地利用变化,以复杂适应系统理论为基础,通过集成多智能体、GIS和元胞自动机建立城市发展模型,并以Repast和 ArcGIS为基础设计实现了城市土地利用动态模拟系统,并以广州市番禺区为例进行了仿真实验。仿真结果表明,该方法是一种模拟土地利用变化的有效方法,可以为城市建设、管理和规划工作提供辅助决策支持。     

Characterizing the state and processes of change in a dynamic forest environment using hierarchical spatio-temporal segmentation

Discrete changes in forest abundance, distribution, and productivity are readily detectable using a number of remotely sensed data sources; however, continuous changes such as growth and succession processes are more difficult to monitor. In this research we explore the potential of spectral trajectories generated from a 35-year (1973-2008) time-series of Landsat imagery to characterize change processes in a dynamic forest environment in northwestern Alberta, Canada. We propose a method of hierarchical spatio-temporal segmentation that enables the characterization of change processes that are spatially diffuse and temporally imprecise. Calibrated imagery from Landsat sensors are radiometrically normalized and two metrics derived from the Tasseled Cap Transformation components, greenness and brightness, are used to generate the Tasseled Cap Angle (TCA). The TCA is a measure of the proportion of vegetation to non-vegetation (the occupation state), and its derivative, the Process Indicator (PI), is a measure of change in this proportion through time. These indices condense information from the visible and near-infrared wavelengths, and facilitate lengthy time series analysis of forest landscape change using data from all Landsat sensors.A combination of the original TCA and its derivative sequence are input to a three level hierarchical segmentation process with the highest and lowest levels defining homogeneous objects at the initial and final date, and the intermediate level identifying trajectories with similar change processes. The development through time of the TCA and PI are described, and the spatial and temporal associations of processes are statistically assessed using the Moran's Index.A full range of change types were identified on the landscape, from stand replacing disturbances to more subtle growth and succession processes. Results indicate that the study area is in a constant state of change, and maintains a high average proportion of vegetation to non-vegetation. The amount of total landscape modified per decade increased from 18% and 14% in the 1970s and 1980s respectively, to more than 30% and 33% in the 1990s and 2000s. On average, the proportion of vegetation to non-vegetation was increasing prior to 1981, decreasing between 1981 and 1997, and increasing post-1997. There was a high degree of spatial autocorrelation amongst change processes, with a maximum Moran's I of 0.79 in 1973; landscape change became more spatially disperse and widespread after 1981. Temporal correlation of change processes was observed locally, with the period 1990-1995 having the most persistent change.     

基于热调度消纳风电的户式相变蓄热电采暖热容量研究

传统研究方法在研究户式相变蓄热电采暖热容量时,准确性很低。为了解决这一问题,基于热调度消纳风电提出了一种新的户式相变蓄热电采暖热容量研究方法,首先通过系统备用功率分析了热电模式下户式相变蓄热系统接纳风电能力,进而给出了风电供热调度模型,该模型根据显热蓄热热容量,潜能蓄热热容量和化学反应蓄热三种户式相变蓄热方式进行电采暖热容量研究。与传统研究方法进行实验对比,结果表明,给出的方法准确率可以达到99.82%,传统的研究方法准确率为90.53%,所提方法误差率更小,具有更广阔的发展空间。     

Comparing three global parametric and local non-parametric models to simulate land use change in diverse areas of the world

This paper compares one global parametric land use change model, the artificial neural network – based Land Transformation Model, with two local non-parametric models: a classification and regression tree and multivariate adaptive regression spline model. We parameterized these three models with identical data from different regions of the world; one region undergoing extensive agricultural expansion (East Africa), another region where forests are re-growing (Muskegon River Watershed in the United States), and a third region where urbanization is prominent (South-Eastern Wisconsin in the United States). Independent training data and testing data were used to train and calibrate each model, respectively. Comparisons of simulated maps from the three kinds of land use change patterns were made using conventional goodness-of-fit metrics in land use change science. The results of temporal and spatial comparison of the data mining models show that the artificial neural network outperformed all other models in a short-time interval (East Africa; 5 years) and for coarse resolution data (East Africa; 1 km); however, the three data mining models obtained similar accuracies in a long-time interval (Muskegon River Watershed; 20 years) and for fine resolution data with large numbers of cells (Muskegon River Watershed; 30 m). Furthermore, the results showed that the probability of agriculture gain was more likely in locations closer to towns and large cities in East Africa, urbanization was more likely in locations closer to roads and urban areas in South-Eastern Wisconsin and the probability of forest gain was more likely in locations closer to the forest and shrub land cover and farther away from roads in Muskegon River Watershed.