单元化制造系统中的生产计划与控制

制造单元是为加工制造一个或几个在结构和工艺上有一定相似性的产品族或组成产品的零件族而建立的生产单位.以制造单元为基础,实施产品或零部件的生产则成为单元化制造,而单元化制造系统是应用单元化制造的理念建立和运行的信息化生产系统的总称.其多采用数控机床和数控加工中心等数控设备,在计算机的统一管理和控制管理之下进行多品种、中小批量产品的加工制造,是目前比较先进的制造系统.实施单元化制造可以简化管理,减少零件流动,缩短生产准备时间,缩短产品制造周期,提高生产率和产品质量.     

利用计算机辅助制造的加工模拟提高产品加工质量

目前南车青岛四方机车车辆股份有限公司制造的高速列车,其许多产品零部件具有形状复杂的空间曲面。为了保证产品良好的运行可靠性,获得符合设计要求的机械加工零部件,在制造中采用了计算机辅助制造加工模拟的方法,并通过控制制造现场运行流程获得了合格的产品质量。     

一种面向制造企业全面集成的虚拟制造系统体系结构

面对制造环境、制造产品、制造系统和制造过程本身的复杂性,要求制造企业对不断变化的制造环境做出快速反应、不断调整和优化企业自身的运作,以更快的速度、最低的价格向用户提供高质量的产品。本文提出通过虚拟制造对制造企业进行全面集成,使其能够根据市场变化进行自我调节、自我完善、自我改造和自我发展。在对虚拟制造系统功能进行分析的基础上,提出了一种虚拟制造系统的体系结构,并对其关键技术进行了讨论。     

制造服务逻辑关系确定方法研究

Web服务环境下,为了快速建立制造服务链,提出了一种制造服务逻辑关系的确定方法。首先分析了产品结构、制造任务和制造服务三者之间的关系,提出了基于产品结构建立制造服务链的过程,然后论述了制造任务时序关系的确定方法,定义了基于产品结构的制造服务分类模型,最后给出了制造服务逻辑关系的确定规则。     

虚拟制造

编辑寄语:虚拟制造技术VMT(Virtual Manufacturing Technology)是20世纪80年代后期提出并得到迅速发展的一个新思想。它是以虚拟现实和仿真技术为基础,对产品的设计、生产过程统一建模,在计算机上对产品从设计、加工和装配、检验、使用等整个生命周期进行模拟和仿真。采用虚拟制造技术,可以在产品的设计     

材料成型与控制工程模具制造的工艺技术分析

现代多种制造业都将材料成型和控制工程模具制造技术作为基础,例如汽车制造、家电制造等等,材料成型和控制工程模具制造技术为其提供各个零部件,可以说,材料成型技术和控制工程模具制造技术直接决定了产品的技术水准,它是机械制造质量与水平的重要影响因素.在本文当中,笔者将着重对材料成型与控制工程模具制造工艺概念、金属与非金属材料的成型和控制工程模具制造工艺三个方面进行阐述和分析.     

一种面向制造企业全面集成的虚拟制造系统体系结构

面对制造环境，制造产品，制造系统和制造过程本身的复杂性，要求制造企业对不断变化的制造环境做出快速反应、不断调整和优化企业自身的运作，以更快的速度，最低的价格用提供高质量的产品。     

汽车供应链之重

融入全球产业链的中国汽车零部件制造企业,产品创新能力亟待提升。融入全球产业链的中国汽车零部件制造企业,产品创新能力亟待提升。     

面向云制造模式的制造资源协作支撑平台分析

随着产品复杂度的提高和更短的生产周期要求,单个制造企业资源和能力无法满足要求。应依托第三方制造资源协作平台,实现各企业分布式制造资源和服务的共享和协作。研究面向云制造模式的制造资源协作平台的架构、功能和运作机制,为构建制造云提供有效的基础设施解决方案。     

我国汽车制造机械加工技术发展现状

本文介绍了我国汽车制造机械加工工业的现状和发达国家的先进的汽车制造机械加工技术的发展动向,说明了汽车零部件机械加工技术和设备的特征,阐述了高速加工技术发展趋势及应用前景。     

基于家具企业信息化的家具编码系统的研究

根据家具行业的实际情况,利用成组技术,提出了家具产品、五金件和零部件的编码原则和实现方法,分析了编码系统实现可以给企业带来的效益。     

多级网络编码方案

目前安全网络编码的研究有信息论安全和密码学安全两种方法。信息论安全的编码方案中,中继节点编码主要是使用随机线性网络编码（RLNC）生成编码矩阵,但是此方法并不能保证生成的矩阵一定满秩,从而影响方案的解码率。提出了一个多级网络编码（MLNC）方案,该方案通过在源端使用对角矩阵对消息进行编码,以降低编码复杂度;在中继节点,让入度大于等于2的节点作为编码节点,使用多级的网络编码使混淆效果更好,编码节点随机生成满秩的下三角矩阵和上三角矩阵,用它们的乘积作为编码矩阵,这样能保证编码矩阵满秩,接收节点可以成功解码。Matlab仿真结果表明,MLNC编码矩阵达到k-安全概率优于RLNC编码矩阵,并证明MLNC方案满足信息论安全。     

An automated coding and classification system with supporting database for effective design of manufacturing systems

The philosophy of group technology (GT) is an important concept in the design of flexible manufacturing systems and manufacturing cells. Group technology is a manufacturing philosophy that identifies similar parts and groups them into families. Beside assigning unique codes to these parts, group technology developers intend to take advantage of part similarities during design and manufacturing processes. GT is not the answer to all manufacturing problems, but it is a good management technique with which to standardize efforts and eliminate duplication. Group technology classifies parts by assigning them to different families based on their similarities in: (1) design attributes (physical shape and size), and/or (2) manufacturing attributes (processing sequence). The manufacturing industry today is process focused; departments and sub units are no longer independent but are interdependent. If the product development process is to be optimized, engineering and manufacturing cannot remain independent any more: they must be coordinated. Each sub-system is a critical component within an integrated manufacturing framework. The coding and classification system is the basis of CAPP and the functioning and reliability of CAPP depends on the robustness of the coding system. The proposed coding system is considered superior to the previously proposed coding systems, in that it has the capability to migrate into multiple manufacturing environments. This article presents the design of a coding and classification system and the supporting database for manufacturing processes based on both design and manufacturing attributes of parts. An interface with the spreadsheet will calculate the machine operation costs for various processes. This menu-driven interactive package is implemented using dBASE-IV. Part Family formation is achieved using a KAMCELL package developed in TURBO Pascal.     

联合编码开销与安全性能的网络编码优化方案

网络编码技术在提高网络吞吐量和传输效率等方面具有很大优势,但该技术需要在节点处进行额外编码操作,增加了编码开销。针对在保证最大多播速率的前提下,降低编码开销的同时兼顾网络编码安全程度的问题,现提出一种联合编码开销与安全性能的网络编码优化方案。该方案首先在基于预选择机制的小生境遗传算法的基础上加入了预处理机制。其次,构建了新的适应度函数。最后采用了一种更科学的种群规模的确定方式。仿真结果表明,该算法比传统的基于遗传算法的网络编码优化方案在收敛时间、进化代数、编码开销和安全程度四个方面更具优势。     

Protection of intellectual property based on a skeleton model in product design collaboration

As markets are globalized and competition among companies increases, corporations strive to remain competitive by focusing their abilities on key parts of a new product, while outsourcing remaining parts to other companies. In these circumstances, relationships with business partners with regard to product design are not rigid and vertical, but rather, flexible and horizontal; thus, partners today can be competitors in the future. Therefore, the intellectual property of a participating company should be protected from other collaborating companies during the product design process. However, this safeguard should not be an obstacle to product design collaboration itself. As a solution to this problem, we propose a method to share a skeleton model among collaborating companies. By using this model, participating companies can share essential data required for the detail design of those components of a product for which they are responsible, while ensuring security of their intellectual property. The feasibility of the proposed method has been demonstrated through experiments in a development scenario involving a tub component of a washing machine.     

A data-check based distributed storage model for storing hot temporary data

For the purpose of ensuring data security, traditional systems have widely used redundancy backup to store multiple copies of data. Multiple copies technology has high reliability, but also has the disadvantage of high redundancy storage and low space utilization. On the contrary, EC (Erasure Coding) technology has a high utilization rate of storage space, but the overhead of coding, decoding and data reconstruction is great. So, this paper demonstrates a data backup method based on XOR checksum being suitable for storing hot temporary data, which first splits the data into two parts and then performs the XOR operation of the two parts to generate another part of the data. Finally, the XOR checksum stores the three data parts into different nodes. The checksum not only ensures the security of data but also saves the storage space, thus improving the performance of reading and writing. This strategy achieves a mutual backup between the three nodes in order to ensure data security. Because there is only one copy of original data in the system, this model resolves the data inconsistency problem reasonably and simplifies the data version control existing in the redundancy backup model. Actual data test results show that, compared with the current mainstream Cassandra redundant backup model, the performance of a data backup model based on the XOR checksum proposed and implemented in this paper has been significantly improved: the reading performance improves by an average of 10%, and the writing performance improves by an average of 30%.     

整合有USB KEY的无线上网卡设计

提出一种USB无线上网卡和USB KEY二合一的产品设计,详细介绍了系统的硬件结构和软件流程。设计中将USB KEY功能模块合理地划分在基带处理器和专用安全芯片两个部分中,利用USB Bulk_Only传输协议完成主机与USB设备上虚拟CD-ROM设备的命令应答和数据交换。该产品有效地降低了产品硬件成本,提高了用户使用便捷性。     

窃听攻击下子空间码的安全性

子空间码与随机线性网络编码相结合的网络系统具有编译码复杂度低、无需附加编码矢量和非相干通信等优点,曾被用于网络纠错。针对子空间码在窃听攻击下的安全性能,将攻击者猜测信源消息的成功概率作为子空间码的安全性度量。基于Cai和Yeung提出的网络窃听模型,采用线性代数和组合学方法,定量计算了攻击者的猜测概率并得到了闭式解。分析结果表明,子空间码具有概率意义下的弱安全性,但与许多完美安全或弱安全编码方案相比,子空间码具有复杂度低、灵活性高、拓扑不受限、可对抗多边窃听等优势,因此子空间码适用于计算受限且安全性能要求不高的应用。     

Seven pernicious kingdoms: a taxonomy of software security errors

Taxonomies can help software developers and security practitioners understand the common coding mistakes that affect security. The goal is to help developers avoid making these mistakes and more readily identify security problems whenever possible. Because developers today are by and large unaware of the security problems they can (unknowingly) introduce into code, a taxonomy of coding errors should provide a real tangible benefit to the software security community. Although the taxonomy proposed here is incomplete and imperfect, it provides an important first step. It focuses on collecting common errors and explaining them in a way that makes sense to programmers. This new taxonomy is made up of two distinct kinds of sets, which we're stealing from biology: a phylum (a type of coding error, such as illegal pointer value) and a kingdom (a collection of phyla that shares a common theme, such as input validation and representation). Both kingdoms and phyla naturally emerge from a soup of coding rules relevant to enterprise software, and it's for this reason that this taxonomy is likely to be incomplete and might lack certain coding errors. In some cases, it's easier and more effective to talk about a category of errors than to talk about any particular attack. Although categories are certainly related to attacks, they aren't the same as attack patterns.     

单钥密码体制与纠错码的构造研究

纠错码与密码的结合是代数编码理论和密码学发展的必然产物.介绍了单钥体制的一般构造及分析单钥体制安全性的3种攻击方法,讨论了两种基于纠错码理论的单钥分组密码体制,建立了一种同时具有检错和对消息认证,保密功能的新的单钥体制.该体制不仅保留了Rao-Nam体制的优点,而且比Rao-Nam体制有更多的优越性和更强的实用性.