Because of the complex constraint effects among layers in multi-layered metallic bellows hydroforming,the stress concentration and defects such as wrinkling and fracture may easily occur.It is a key to reveal the defo...Because of the complex constraint effects among layers in multi-layered metallic bellows hydroforming,the stress concentration and defects such as wrinkling and fracture may easily occur.It is a key to reveal the deformation behaviors in order to obtain a sound product.Based on the ABAQUS platform,a 3 D-FE model of the four-layered U-shaped metallic bellow hydroforming process is established and validated by experiment.The stress and strain distributions,wall thickness variations and bellow profiles of each layer in the whole process,including bulging,folding and springback stages,are studied.Then deformation behaviors of bellows under different forming conditions are discussed.It is found that the wall thinning degrees of different layer vary after hydroforming,and is the largest for the inner layer and smallest for the outer layer.At folding stage,the wall thinning degree of the crown point increases lineally,and the difference among layers increases as the process going.The displacements of the crown point decrease from the inner layer to the outer layer.After springback,the U-shaped cross section changes to a tongue shape,the change of convolution pitch is much larger than the change of convolution height,and the springback values of the inner layer are smaller than the outer layer.An increase in the internal pressure and die spacing cause the maximum wall thinning degree and springback increase.With changing of process parameters,bellows with deep convolution are easily encountered wall thinning during hydroforming and convolution distortion after springback.This research is helpful for precision forming of multi-layered bellows.展开更多
Owing to continuous production lines with large amount of consecutive controls, various control signals and huge logistic relations, this paper introduced the methods and principles of the development of knowledge bas...Owing to continuous production lines with large amount of consecutive controls, various control signals and huge logistic relations, this paper introduced the methods and principles of the development of knowledge base in a fault diagnosis expert system that was based on machine learning by the four-layer perceptron neural network. An example was presented. By combining differential function with not differential function and back propagation of error with back propagation of expectation, the four-layer perceptron neural network was established. And it was good for solving such a bottleneck problem in knowledge acquisition in expert system and enhancing real-time on-line diagnosis. A method of synthetic back propagation was designed, which broke the limit to non-differentiable function in BP neural network.展开更多
This paper explains an integrated production inventory supply chain model,which consists of a supplier,a manufacturer and a retailer under two-level credit period.One is manufacturer’s credit period offered by the su...This paper explains an integrated production inventory supply chain model,which consists of a supplier,a manufacturer and a retailer under two-level credit period.One is manufacturer’s credit period offered by the supplier,and other is retailer’s credit period offered by the manufacturer.Here,the manufacturer replenishes raw materials from the supplier and produces non-deteriorating products in some cycles of equal length.It is noted that here four inventory structures have been considered to show the flow of the materials as either raw materials or finished products from supplier to retailer via manufacturer.Also in this model,manufacturer’s imperfect production has been considered.Here imperfect items are not repairable.The retailer receives good finished products from the manufacturer and sells these to his/her customers during some cycles of equal length in total time horizon.Our main objective is to find the optimal number of production and business cycles of the manufacturer such that the integrated system can get the maximum profit.The above discussed model is elaborated with the help of a numerical example,and a sensitivity analysis is done with respect to some parameters used in this model.展开更多
等级保护2.0(以下简称“等保2.0”)对数据中心信息安全架构提出了合规与技术要求。文章构建四层联动架构模型,涵盖网络安全、计算环境、应用数据与安全运营4个层面,通过引入零信任访问控制、虚拟化隔离机制、数据全生命周期防护及安全...等级保护2.0(以下简称“等保2.0”)对数据中心信息安全架构提出了合规与技术要求。文章构建四层联动架构模型,涵盖网络安全、计算环境、应用数据与安全运营4个层面,通过引入零信任访问控制、虚拟化隔离机制、数据全生命周期防护及安全编排自动化响应(Security Orchestration Automation and Response,SOAR)机制,提出了一套面向等保2.0的优化实施方案。实验结果表明,优化架构在检测率、响应效率、资源占用等关键指标上相较传统架构均有显著提升。因此,优化架构具备良好的工程适配性与合规落地能力。展开更多
基金the funds of the National Natural Science Foundation of China(No.51875456)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2019JM-450)+3 种基金the Young Talent fund of University Association for Science and Technology in Shaanxi,China(No.20170518)the Key Laboratory of Advanced Manufacture Technology for Automobile Parts(Chongqing University of Technology),Ministry of Education(No.2018KLMT03)Materials Science and Engineering provincial-level superior discipline funding project of Xi'an Shiyou Universitythe Program for Young Innovative Research Team in Xi'an Shiyou University(No.2015QNKYCXTD02)。
摘要Because of the complex constraint effects among layers in multi-layered metallic bellows hydroforming,the stress concentration and defects such as wrinkling and fracture may easily occur.It is a key to reveal the deformation behaviors in order to obtain a sound product.Based on the ABAQUS platform,a 3 D-FE model of the four-layered U-shaped metallic bellow hydroforming process is established and validated by experiment.The stress and strain distributions,wall thickness variations and bellow profiles of each layer in the whole process,including bulging,folding and springback stages,are studied.Then deformation behaviors of bellows under different forming conditions are discussed.It is found that the wall thinning degrees of different layer vary after hydroforming,and is the largest for the inner layer and smallest for the outer layer.At folding stage,the wall thinning degree of the crown point increases lineally,and the difference among layers increases as the process going.The displacements of the crown point decrease from the inner layer to the outer layer.After springback,the U-shaped cross section changes to a tongue shape,the change of convolution pitch is much larger than the change of convolution height,and the springback values of the inner layer are smaller than the outer layer.An increase in the internal pressure and die spacing cause the maximum wall thinning degree and springback increase.With changing of process parameters,bellows with deep convolution are easily encountered wall thinning during hydroforming and convolution distortion after springback.This research is helpful for precision forming of multi-layered bellows.
摘要Owing to continuous production lines with large amount of consecutive controls, various control signals and huge logistic relations, this paper introduced the methods and principles of the development of knowledge base in a fault diagnosis expert system that was based on machine learning by the four-layer perceptron neural network. An example was presented. By combining differential function with not differential function and back propagation of error with back propagation of expectation, the four-layer perceptron neural network was established. And it was good for solving such a bottleneck problem in knowledge acquisition in expert system and enhancing real-time on-line diagnosis. A method of synthetic back propagation was designed, which broke the limit to non-differentiable function in BP neural network.
基金This research work was supported by Council of Scientific and Industrial Research,Human Resource Development Group,India(No.25(0276)/17/EMR-II).
摘要This paper explains an integrated production inventory supply chain model,which consists of a supplier,a manufacturer and a retailer under two-level credit period.One is manufacturer’s credit period offered by the supplier,and other is retailer’s credit period offered by the manufacturer.Here,the manufacturer replenishes raw materials from the supplier and produces non-deteriorating products in some cycles of equal length.It is noted that here four inventory structures have been considered to show the flow of the materials as either raw materials or finished products from supplier to retailer via manufacturer.Also in this model,manufacturer’s imperfect production has been considered.Here imperfect items are not repairable.The retailer receives good finished products from the manufacturer and sells these to his/her customers during some cycles of equal length in total time horizon.Our main objective is to find the optimal number of production and business cycles of the manufacturer such that the integrated system can get the maximum profit.The above discussed model is elaborated with the help of a numerical example,and a sensitivity analysis is done with respect to some parameters used in this model.
摘要等级保护2.0(以下简称“等保2.0”)对数据中心信息安全架构提出了合规与技术要求。文章构建四层联动架构模型,涵盖网络安全、计算环境、应用数据与安全运营4个层面,通过引入零信任访问控制、虚拟化隔离机制、数据全生命周期防护及安全编排自动化响应(Security Orchestration Automation and Response,SOAR)机制,提出了一套面向等保2.0的优化实施方案。实验结果表明,优化架构在检测率、响应效率、资源占用等关键指标上相较传统架构均有显著提升。因此,优化架构具备良好的工程适配性与合规落地能力。