21世纪塑性加工面临的挑战──对几个问题的看法

在２１世纪即将到来之际，塑性加工面临严峻的挑战。企业的主要领导者和主要技术人员应从指导思想与哲理上、技术上、运营方式上以及人材培养等方面做好充分准备。作者在本文中对下述几方面的问题进行了探讨，提出作者的粗浅看法，供同行们讨论。这些方面包括市场导向、柔性化、自动化策略、准时制与精良生产、并行工程、集成化与智能化、人的因素、教育与培训等。     

Association-Based Active Access Control models with balanced scalability and flexibility

In existing Active Access Control (AAC) models, the scalability and flexibility of security policy specification should be well balanced, especially: (1) authorizations to plenty of tasks should be simplified; (2) team workflows should be enabled; (3) fine-grained constraints should be enforced. To address this issue, a family of Association-Based Active Access Control (ABAAC) models is proposed. In the minimal model ABAAC₀, users are assigned to roles while permissions are assigned to task-role associations. In a workflow case, to execute such an association some users assigned to its component role will be allocated. The association's assigned permissions can be performed by them during the task is running in the case. In ABAAC₁, a generalized association is employed to extract common authorizations from multiple associations. In ABAAC₂, a fine-grained separation of duty (SoD) is enforced among associations. In the maximal model ABAAC₃, all these features are integrated, and similar constraints can be specified more concisely. Using a software workflow, case validation is performed. Comparison with a representative association based AAC model and the most scalable AAC model so far indicates that: (1) enough scalability is achieved; (2) without decomposition of a task, different permissions can be authorized to multiple roles in it; (3) separation of more fine-grained duties than roles and tasks can be enforced.     

制造系统柔性评价方法研究

深入分析评价制造系统柔性的基本要求,并介绍柔性熵的概念,建立评价系统柔性的数学模型。通过实例分析,证明该模型对评价制造系统柔性有一定的价值。     

基于解释器技术的注塑模CAD系统研究

针对传统泣塑模CAD系统的缺陷，提出并分析了新型注塑模系统的总体设计方案和3DMCAD／CAM系统构建语言，由此实现了柔性化注塑模CAD系统，包括模架、抽芯机构、浇口套等机构及其孔型的信息获取、自动生成、更新和删除。     

Problem-Solving Base Building under Uncertainty and Ambiguity: Multiple-Case Study on an Airport Expansion Program

This multiple-case study induces alternative strategies to coordinate the overlap of tasks to detail and physically execute base building with tasks to conceptualize the business-critical fit out. Base-building subsystems provide service space for occupancy, whereas fit-out subsystems make the space functional. Our empirical findings on problem-solving base-building design under uncertainty and ambiguity stem from a number of projects in an airport expansion program. They suggest that base-building subsystems show low sensitivity to incremental changes in fit out as their definitions are seldom optimized to eliminate slack. Yet, base-building subsystems show high sensitivity to radical changes in fit out when the architectures of the two subsystems are integral to one another. Three strategies for problem-solving base building stand out: (1) iterate design when preliminary information about fit out is ambiguous, or precise but unstable; (2) physically decouple the architectures of base building and fit out; and (3) design buffers in base building when preliminary information about fit out lacks precision but it is not ambiguous. These buffers can be designed out if uncertainties in fit out resolve favorably before starting the physical execution for base building.     

轿车车身结构概念模型中接头的模拟

提出了"接头单元”的概念,以车身某一立柱上接头为例,计算了接头柔度,并研究了在车身结构概念模型中模拟接头的方法.此外,还分析了接头柔度对整车刚度的影响.     

欠驱动柔性机器人的动力学建模与耦合特性

运用有限元法,建立具有柔性杆的欠驱动机器人的动力学一般模型。以此模型为基础,分析系统的主动与被动关节的加速度耦合和被动关节与驱动力矩的动力学耦合效应,并针对欠驱动柔性机器人,提出柔性杆弹性变形分别与主动关节、被动关节动力学耦合的新指标。将欠驱动柔性机器人的被动关节加速度耦合和力矩耦合仿真结果与刚性系统相比较,在某个驱动器位置,柔性系统得到较大的耦合值,说明此时柔性系统更加有利于能量的传递,体现了杆件的弹性变形对系统动力学特性的影响。同时,数值仿真还表明这些动力学耦合指标对欠驱动机器人的结构设计、位形设计、驱动装置位置及系统控制都具有重要意义。     

单柱立式车床挠度误差补偿

对于西门子公司的８８０Ｔ等尚没有设置悬臂梁挠度误差补偿功能的数控系统，利用其既有软件资源，通过ＰＬＣ编程可实现挠度误差补偿。文章介绍了挠度误差补偿程序的编程方法以及在ＣＫＸ１５０００立式车床上的实施举例。     

Decarbonization of electricity requires market-based demand flexibility

To effectively decarbonize the electric sector, utilities will need to address the growing load shape challenges driven by the variability of many renewable resources. Behind-the-meter solutions, such as energy efficiency, demand response, electrification and storage, will play an important role in grid stability, but only if they can deliver changes in demand that meet the time and locational needs of the grid. This article will discuss how smart meter interval data, combined with open source methods and software, provide transparent measurement of savings load shapes (resource curves) that enable the integration of demand flexibility into energy, capacity and carbon markets, and as a transmission and distribution resource. This allows utilities to procure demand flexibility in the same way they procure other resources by leveraging a price signal and pay-for-performance to drive innovation and attract private investment.     

Flexibility in manufacturing: A survey

This article is an attempt to survey the vast literature on flexibility in manufacturing that has accumulated over the last 10 to 20 years. The survey begins with a brief review of the classical literature on flexibility in economics and organization theory, which provides a background for manufacturing flexibility. Several kinds of flexibilities in manufacturing are then defined carefully along with their purposes, the means to obtain them, and some suggested measurements and valuations. Then we examine the interrelationships among the several flexibilities. Various empirical studies and analytical/optimization models dealing with these flexibilities are reported and discussed. The article concludes with suggestions for some possible future research directions.