Reliability modeling for consecutive k-out-of-n: F systems with local load-sharing components subject to dependent degradation and shock processes

Traditional k-out-of-n models assume that the components are independent, while recent research studies assume that the components are dependent caused by global load-sharing characteristic. In this paper, we investigate the consecutive k-out-of-n systems with dependent components by local load-sharing characteristic. The work load and shock load on failed components will be equally shared by adjacent components, so the components tend to fail consecutively. Consequently, the components degradation processes may be diverse, since their degradation rate (dependent on work load) and abrupt degradation (dependent on shock load) become unequal because of local load-sharing effect. Furthermore, the system failure will be path-dependent on the failure sequences of components, which results in that the same system states may have different system failure probabilities. This new dependence makes the system reliability model more complex. In this work, an analytical model that can be solved numerically is derived to compute the reliability with this complex dependence. The developed model is demonstrated by a cable-strut system in the suspension bridge. The results show that the reliability decreases significantly when the new dependence is considered.     

An efficient document classification model using an improved back propagation neural network and singular value decomposition

This paper proposed a new improved method for back propagation neural network, and used an efficient method to reduce the dimension and improve the performance. The traditional back propagation neural network (BPNN) has the drawbacks of slow learning and is easy to trap into a local minimum, and it will lead to a poor performance and efficiency. In this paper, we propose the learning phase evaluation back propagation neural network (LPEBP) to improve the traditional BPNN. We adopt a singular value decomposition (SVD) technique to reduce the dimension and construct the latent semantics between terms. Experimental results show that the LPEBP is much faster than the traditional BPNN. It also enhances the performance of the traditional BPNN. The SVD technique cannot only greatly reduce the high dimensionality but also enhance the performance. So SVD is to further improve the document classification systems precisely and efficiently.     

数字化技术在民机设计中的应用与探究

该文以虚拟现实技术、三维建模技术、可视化后处理技术、数字化平台、平面艺术等方面举例分析,提出计算机数字化技术的发展为民机设计的研发、设计、技术论证、市场宣传等工作带来新的研究形式和工作方法,使民机设计的过程更科学、更人性、更高效。民机作为高端产品的代表,集中的体现了我国科技的发展方向。同时,民机的最大价值是推向市场,得到客户的广泛认可并获得良好的口碑。这对于提高我国民机事业的国际竞争力是至关重要的。     

民用飞机电气负载自动管理技术的研究

多电飞机和全电飞机等设计理念的出现,使得飞机的配电系统出现了用电负载多,用电需求各异,供配电模式多样等新特点,常规的配电方式已无法满足系统的功能需求及安全性需求;独立提出了一套在通用的配电系统架构下,实施电气负载自动管理技术的方案;并分析和归纳了该方案实施的各环节中,所应遵循的原则及可采用的方法;最后,通过应用举例,说明了该方案实施的可行性;可为如何在民用飞机上实施电气负载自动管理技术提供重要参考。     

An end-to-end tabular information-oriented causality event evolutionary knowledge graph for manufacturing documents

Industrial tabular information extraction and its semantic fusion with text (ITIESF) is of great significance in converting and fusing industrial unstructured data into structured knowledge to guide cognitive intelligence analysis in the manufacturing industry. A novel end-to-end ITIESF approach is proposed to integrate tabular information and construct a tabular information-oriented causality event evolutionary knowledge graph (TCEEKG). Specifically, an end-to-end joint learning strategy is presented to mine the semantic information in tables. The definition and modeling method of the intrinsic relationships between tables with their rows and columns in engineering documents are provided to model the tabular information. Due to this, an end-to-end joint entity relationship extraction method for textual and tabular information from engineering documents is proposed to construct text-based knowledge graphs (KG) and tabular information-based causality event evolutionary graphs (CEEG). Then, a novel NSGCN (neighborhoods sample graph convolution network)-based entity alignment is proposed to fuse the cross-knowledge graphs into a unified knowledge base. Furthermore, a translation-based graph structure-driven Q&A (question and answer) approach is designed to respond to cause analysis and problem tracing. Our models can be easily integrated into a prototype system to provide a joint information processing and cognitive analysis. Finally, the approach is evaluated by employing the aerospace machining documents to illustrate that the TCEEKG can considerably help workers strengthen their skills in the cause-and-effect analysis of machining quality issues from a global perspective.     

一种基于DOORS的软件需求开发过程优化方法

需求过程是整个软件生存周期中非常重要的一个阶段。因为需求开发过程和需求管理过程的差异,需求开发工具和需求管理工具的选择也可能不同。由此需要将软件需求从需求文档录入至专业需求管理工具的数据库。对此,提出一种基于DOORS的软件需求开发过程优化方法,定义需求文档的编制格式,并开发基于DXL脚本语言的转换插件,最后方便地将RTF格式的需求文档导入至DOORS数据库,能够快速有效地实现需求开发和需求管理之间的衔接。     

Synthesis of new rare earth containing ternary laminar Sc2PbC ceramic

In this paper, we combine rare earth element Sc and lead-containing MAX to predict a new ternary layered MAX phase Sc₂PbC. Sc₂PbC with a purity of 87.40 wt% was successfully synthesized by spark plasma sintering, and its crystal structure and atomic positions were obtained by X-ray diffraction (XRD). The Rietveld refinement results show that Sc₂PbC belongs to a typical MAX phase P6₃/mmc (No.194) space group with lattice parameters of a = 3.4003(7) Å and c = 14.7475(3) Å, where Sc atom is located at (1/3, 2/3, 0.57958), Pb atom is located at (1/3, 2/3, 1/4), and C atom is located at (0, 0, 0). At the same time, we observed the typical MAX phase layered microstructure in Sc₂PbC bulk using a scanning electron microscope (SEM). In addition, the proportion of elements measured by energy dispersive spectroscopy (EDS) is within the allowable error range, which confirms that Sc₂PbC is a new MAX phase compound.     

民用运输类飞机的设计组织要求

对于民用运输类飞机,国内外民航当局越来越依赖于飞机主制造商的设计组织体系,以更有效地确保飞机满足适航及环境保护要求并持续保持适航性.文中从定义开始探讨了民用运输类飞机设计取证对于设计组织及设计保证系统的要求,明确了设计保证系统必须具备包括设计职能、适航职能及独立监控职能在内的三大职能.同时,作为型号设计的提供者,为确保型号设计的适航性,供应商必须被视为主制造商设计保证系统的延伸,并且应建立与主制造商之间的接口程序.     

New Knowledge Network Evaluation Method for Design Rationale Management

Current design rationale(DR) systems have not demonstrated the value of the approach in practice since little attention is put to the evaluation method of DR knowledge. To systematize knowledge management process for future computer-aided DR applications, a prerequisite is to provide the measure for the DR knowledge. In this paper, a new knowledge network evaluation method for DR management is presented. The method characterizes the DR knowledge value from four perspectives, namely, the design rationale structure scale, association knowledge and reasoning ability, degree of design justification support and degree of knowledge representation conciseness. The DR knowledge comprehensive value is also measured by the proposed method. To validate the proposed method, different style of DR knowledge network and the performance of the proposed measure are discussed. The evaluation method has been applied in two realistic design cases and compared with the structural measures. The research proposes the DR knowledge evaluation method which can provide object metric and selection basis for the DR knowledge reuse during the product design process. In addition, the method is proved to be more effective guidance and support for the application and management of DR knowledge.