多装配特征影响下的装配质量特性预测方法

针对现有产品装配过程中一次装配成功率难以保证的问题,以灰熵关联分析与粒子群—BP神经网络为建模工具,采用灰熵关联分析对装配特征进行筛选,找出影响产品装配质量的关键装配特征,缩减预测模型的规模,应用粒子群—BP神经网络实现产品装配质量的预测.以某型外圆磨床的砂轮架装配为例,验证了该方法的有效性.     

Design and manufacturing of sheet-metal parts: Using features to aid process planning and resolve manufacturability problems

This paper describes an integrated system for the design and production of sheet-metal parts. We have identified some important features for the sheet-metal bending process. These features are automatically generated as the design progresses. After the designs are complete, our automatic process planning system uses the features and generates new ones to aid the production of plans with near-minimum manufacturing costs. Finally, these plans are used to produce parts on an automatic bending system.Once a plan is generated, it can be used to manufacture the part, and to provide feedback to design and other factory systems. The application of features and the potential feature interaction problems are discussed. Several key manufacturing problems are also considered and the result of planning is used to resolve these problems. By solving these feature interaction problems and often practical manufacturing issues, we are able to plan and manufacture the majority of the parts we have tested less than one hour after the flat patterns are prepared.     

CAD mesh model simplification with assembly features preservation

This paper aims to investigate a CAD mesh model simplification method with assembly features preservation, in order to satisfy the requirement of assembly field for the information of 3D model. The proposed method simplifies a CAD mesh model as follows. Firstly, the notion of ＂conjugation＂ is incorporated into the definition of assembly features, with the purpose of benefitting the downstream applications such as assembly features recognition and preservation. Subsequently, the attributed adjacency graphs （AAGs） of the region- level-represented parts are established. The assembly features are automatically recognized by searching for conjugated subgraphs of every two AAGs based on subgraph isomorphism algorithm. In order to improve the efficiency of assembly features recognition, the characteristics of conjugated subgraphs are adopted to initialize the mapping matrix, and the ＂verifying while matching strategy＂ is used to verify the validity of every two newly founded vertices which are correspondingly matched. Then, simplified CAD mesh model with assembly features preserved is constructed after suppressing the common form features. The method is applied successfully to simplify the CAD mesh model with assembly features well preserved. Moreover, the tradeoff between the cost of time for conjugated subgraphs matching and the complexity of the to-be-matched parts is proven to be almost linear.     

Multiple domain feature mapping: a methodology based on deep models of features

In the research described in this paper, an approach that utilizes deep models of features to transform a component design represented by neutral features into domain-specific features has been developed. The neutral features are known as feature-oriented generic shapes (FOGSs). The proposed approach provides the flexibility needed to represent both the deep and shallow knowledge required in feature mapping. A deep model of a feature is represented in the form of a face connectivity graph (FCG) that embodies deep knowledge about its geometry, while other non-geometrical information can be represented as rules or procedural functions. By comparing the original faces of a product model with those of the resultant evaluated boundary model, faces of interest can be easily extracted and described using FCGs. A FCG can then be examined to determine its class and the relevant parameters for applications in such domains as process planning. The mapping shell is designed with layered architecture that makes it highly appropriate for implementation using blackboard technology.     

C — an alternative to assembly programming

The recent increase in popularity of the programming language c is explained, and similarities between c and both high- and low-level languages are pointed out. In particular, a comparison is drawn with assembly language programming. Advantages and disadvantages of programming in c are highlighted. The c compiler written by Whitesmiths is treated in some detail. Various examples of its use are given.     

An Introduction to Algorithms and Numerical Methods Using Common Software

Jean Brangé describes an approach using Photoshop, VRML and C4D to allow architecture students to manipulate geometric and algebraic formulas, recursion, random functions, statistics, splines, the fourth dimension and other complex mathematical concepts.     

Reverse innovative design — an integrated product design methodology

Today’s product designer is being asked to develop high quality, innovative products at an ever increasing pace. To meet this need, an intensive search is underway for advanced design methodologies that facilitate the acquisition of design knowledge and creative ideas for later reuse. Additionally, designers are embracing a wide range of 3D digital design applications, such as 3D digitization, 3D CAD and CAID, reverse engineering (RE), CAE analysis and rapid prototyping (RP). In this paper, we propose a reverse engineering innovative design methodology called Reverse Innovative Design (RID). The RID methodology facilitates design and knowledge reuse by leveraging 3D digital design applications. The core of our RID methodology is the definition and construction of feature-based parametric solid models from scanned data. The solid model is constructed with feature data to allow for design modification and iteration. Such a construction is well suited for downstream analysis and rapid prototyping. In this paper, we will review the commercial availability and technological developments of some relevant 3D digital design applications. We will then introduce three RE modelling strategies: an autosurfacing strategy for organic shapes; a solid modelling strategy with feature recognition and surface fitting for analytical models; and a curve-based modelling strategy for accurate reverse modelling. Freeform shapes are appearing with more frequency in product development. Since their “natural” parameters are hard to define and extract, we propose construction of a feature skeleton based upon industrial or regional standards or by user interaction. Global and local product definition parameters are then linked to the feature skeleton. Design modification is performed by solving a constrained optimization problem. A RID platform has been developed and the main RE strategies and core algorithms have been integrated into SolidWorks as an add-in product called ScanTo3D. We will use this system to demonstrate our RID methodology on a collection of innovative consumer product design examples.     

Geometric and form feature recognition tools applied to a design for assembly methodology

The paper presents geometric tools for an automated Design for Assembly (DFA) assessment system. For each component in an assembly a two step features search is performed: firstly (using the minimal bounding box) mass, dimensions and symmetries are identified allowing the part to be classified, according to DFA convention, as either rotational or prismatic; secondly form features are extracted allowing an effective method of mechanised orientation to be determined. Together these algorithms support the fuzzy decision support system, of an assembly-orientated CAD system known as FuzzyDFA.     

Using requirement-functional-logical-physical models to support early assembly process planning for complex aircraft systems integration

The assembly line process planning connects product design and manufacturing through translating design information to assembly integration sequence. The assembly integration sequence defines the aircraft system components installation and test precedence of an assembly process. This activity is part of the complex systems integration and verification process from a systems engineering view. In this paper, the complexity of modern aircraft is defined by classifying aircraft system interactions in terms of energy flow, information data, control signals and physical connections. At the early conceptual design phase of assembly line planning, the priority task is to understand these product complexities, and generate the installation and test sequence that satisfies the designed system function and meet design requirements. This research proposes a novel method for initial assembly process planning that accounts for both physical and functional integrations. The method defines aircraft system interactions by using systems engineering concepts based on traceable RFLP (Requirement, Functional, Logical and Physical) models and generate the assembly integration sequence through a structured approach. The proposed method is implemented in an industrial software environment, and tested in a case study. The result shows the feasibility and potential benefits of the proposed method.     

Modelling and simulation of fabrication and assembly plants: an object-driven approach

This paper presents the technical characteristics and methodologies underlying the computer-aided modelling and simulation of fabrication and assembly plants through an object-driven approach. The paper is organized in four main sections. The first and second sections discuss the needs for model integration and then outline the modelling and simulation approach used. The third and fourth sections illustrate an application of the approach for modelling and simulating a specific fabrication and assembly plant.     

Evaluating different strategies to achieve the highest geometric quality in self-adjusting smart assembly lines

Digital twin-driven productions have opened great opportunities to increase the efficiency and quality of production processes. Smart assembly lines are one of these opportunities in which the effects of geometric variations of the mating parts on the assemblies can be minimized. These assembly lines utilize different techniques, including selective assembly and locator adjustments, to improve the geometric quality. This paper signifies that the achievable improvements through these techniques are highly dependent on the utilized fixture layout for the assembly process. Hence, different design methods and productions that can be followed in a smart assembly line are discussed. Furthermore, different scenarios are applied to two industrial sample cases from the automotive industry. The aptest design strategy for each improvement technique is determined. Moreover, the strategy that can result in the highest geometric quality of assemblies through a smart assembly line is defined.     

Geometric skeleton computation enabling concurrent product engineering and assembly sequence planning

This paper introduces a novel modelling approach to geometric skeleton computation enabling concurrent product engineering and assembly sequence planning. Current engineering vision has recently moved towards new modelling and management paradigms to maintain competitive edges all along the product lifecycle. Consistent with concurrent engineering and design for X stakes, this recent shift promotes cross-X and knowledge-intensive philosophies in the product development process, principally focused on lifecycle engineering.The main objective of this research is to integrate assembly process engineering information and knowledge in the early phases of the product development process in a top-down and proactive manner, in order to provide a geometric skeleton-based assembly context for designers. The definition of the product and its related assembly sequence requires both the enhancement and the entire understanding of product relationships between the various product components, and its related assembly rationale. As a consequence, this new modelling approach highlights the need to integrate various stakeholders’ viewpoints involved in the beginning of the product lifecycle. In such a context, earlier work has achieved the early generation of an optimal assembly sequence in the product development process, before the product geometry is completely defined. As a result, previous research has made possible to control and bind the product modelling phase through an assembly oriented product structure.The aim of the proposed approach is to compute and define a geometric skeleton model based on product relational information and the early-defined assembly sequence. The proposed approach–called SKeLeton geometry-based Assembly Context Definition (SKL-ACD)–enables the control of the product modelling phase by introducing skeleton entities consistent with product relationships and assembly sequence planning information. A prototype application within a CAD tool has been developed for aiding geometric skeleton computation and generation. Lastly, an industrial case study is introduced to highlight the feasibility and the relevance of the proposed modelling approach.     

面向对象的建模语言面面观

面向对象的编程技术及其语言的发展,引起了软件工程方法 的变革,简述了面向对象方法与传统方法的不同,介绍当前几种流行的面向对象的建模方法 ,分析了建模辅助工具应具有的基本功能,最后推荐两种性能较好的建模辅助工具。     

Internet-enabled real-time collaborative assembly modeling via an e-Assembly system: status and promise

Collaborative CAD systems enabling collaboration in computer-aided design processes among distributed designers are gaining more and more attention. Yet, such systems, especially in support of collaborative assembly modeling, are hardly achievable. Targeting this gap, this paper addresses an Internet-enabled real-time collaborative assembly modeling system, named e-Assembly. This emerging system allows a group of geographically dispersed designers to jointly build an assembly model in real time over the Internet. In particular, this paper proposes a new assembly representation, called Collaborative Assembly Representation, for Internet-based collaborative assembly modeling. Also, collaborative assembly constraint satisfaction is addressed based on three coordination rules embedded in e-Assembly. Furthermore, the system architecture and realization of e-Assembly are provided. Finally, a prototypic implementation of e-Assembly is presented for demonstration and discussion.     

Introduction to an integrated methodology for development and implementation of enterprise information systems

An integrated methodology for successful development and implementation of enterprise information systems is developed. This paper describes the methodology and defines five components and one repository which can be customized with business scenarios and patterns according to various business environments. Five components consist of information strategy planning, economic justification and measurement, enterprise information system appraisal, package software evaluation, and unified modeling tools. They characterize the methodology through its entire road map. Also, case studies are provided to prove its practical values.     

Proposed features of an online examination interface design and its optimal values

User Interface Design is an essential part of any software application. Accordingly, online examination is an equally important system within eLearning. Consequently, online examination design features are a significant factor in enhancing exam efficiency as well as convenience for examinees. Nine main design features are generally applied in the online exam, namely font (i.e., type, size, colour, and style), background colour, sound alert, questions group, time counters, and number of questions per page. The values of these features are closely related to user characteristics, whether relating to the physical, cognitive, psychomotor, demographics or experience. Our experiment was conducted on 119 students to identify the commonly preferred online examination design. The results show that the students had variations in their choice of online exam interface design, where students preferred to group questions by Topic and then by Type. The most popular font type was Arial with a size of 14 or 12 and using regular font style. Moreover, white background and black text were the most preferred. Most of the students selected 5 and 3 questions/page respectively. Countdown Timer was the most preferred time counter. Regarding sound alert, the 15 and 5 min remains were the most selected by students.     

Using an entity model to drive physical database design

Logical relational database design, because of its implementation-independent nature, has been successfully formalized. Physical relational database design, because of its implementation-dependent nature, has remained largely unformalized and disconnected, not only from logical design but also from conceptual database design. The paper suggests a model for the physical design process that has proven useful in a number of practical development projects. The model demonstrates that a seamless join between conceptual, logical and physical design work is feasible. It illustrates how the process of annotating a conceptual model with physical detail provides a useful framework for driving the process of physical relational database design.     

联合多通道特征与最小二乘决策的人脸反欺诈方法

为了应对大量的欺诈攻击,如照片攻击和视频攻击,提出了一种基于多通道特征与最小二乘法决策的人脸反欺诈方法。一方面,将人脸在不同颜色空间分量上的梯度特征进行加权融合。另一方面,为了提高实验的鲁棒性,引入BSIF纹理特征与CNN的卷积特征,并用最小二乘法对分类的结果进行最优的决策判断。实验在replay-attack和CASIA两个数据集上进行测试,其中在replay-attack数据集上的EER和HTER分别降低到了3.52%与4.63%,在CASIA数据集上的EER和HTER分别降低到了6.02%和6.45%,与目前最优的算法有一定的竞争力,表明该方法对不同方式的欺诈攻击有较好的检测效果。     

Reconfiguration of assembly systems: From conveyor assembly line to serus

Confronted with the dynamic and complex market environments, the traditional conveyor assembly line can no longer meet customers’ demands effectively. The way of reconfiguring conveyor assembly line to a more flexible manufacturing system has been attracting considerable attention both in the academics and production practices. Seru system, also called assembly cell system, is regarded as one of the most successful innovations of manufacturing system in reconfiguring conveyor assembly line. Such a manufacturing system merges considerable flexibility of job shops and high efficiency of conveyor assembly lines to some extent. In this paper, we investigate the problem of how to reconfigure conveyor assembly line to serus. A comprehensive mathematical model incorporating two issues of how many serus should be established and how many workers should be assigned to each seru is developed. Then the model is investigated by an industrial case and compared to Kaku's model with respect to the selected plan. The computation results validate that the proposed model is more suitable to analyze the reconfiguration problems from conveyor assembly line to serus.