检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

射频前端快上升沿电磁脉冲防护电路仿真分析

安全与电磁兼容 2024年第1期 46-51页

作者：刘振磊刘卫东柳扬方庆园石家庄铁道大学河北省电磁环境效应与信息处理重点实验室

针对强电磁脉冲极易通过射频前端进入电子设备内部对敏感电子器件造成伤害的问题,设计了一款工作于C波段的射频前端快上升沿电磁脉冲防护电路。电路采用PIN二极管级联的方式构建四级防护电路,同时引入高通滤波器抑制工作频段以下信号,... 详细信息

针对强电磁脉冲极易通过射频前端进入电子设备内部对敏感电子器件造成伤害的问题,设计了一款工作于C波段的射频前端快上升沿电磁脉冲防护电路。电路采用PIN二极管级联的方式构建四级防护电路,同时引入高通滤波器抑制工作频段以下信号,防止其对设备造成干扰。仿真结果表明,通过控制PIN二极管的偏置电压和电流,可实现对电磁脉冲的快速响应;经过逐级削减输入功率,可有效降低尖峰泄漏;在工作频段内,防护电路可将4 kV的快沿方波脉冲限制在2 V以下,其响应时间小于1 ns,插入损耗小于0.146 dB,驻波比小于1.413,回波损耗小于-15.329 dB,且可有效降低尖峰泄漏,对工作在C波段的卫星电视地面通信设备抵御强电磁脉冲的侵扰具有较好的效果。

关键词：尖峰泄漏 PIN二极管射频前端快上升沿电磁脉冲

Improving Joint Features and Mechanical Properties of Pinless Fiction Stir Welding of Alcald 2A12-T4 Aluminum Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2016年第12期32卷 1372-1377页

作者： zhenlei liu Hutao Cui Shude Ji Minqiang Xu Xiangchen Meng Harbin Institute of Technology Deep Space Exploration Research Center Faculty of Aerospace Engineering Shenyang Aerospace University

As a new solid state welding,pinless friction stir welding（PFSW） can be used to join thin-wall *** this study,four new pinless tools with different groove distributions were designed and manufactured in order to enrich technological storage of PFSW and obtain sound joint with high quality of alclad 2A12-T4 *** results show that the small-obliquity tool is detrimental to the transfer of plasticized materials,resulting in the formation of kissing bond *** the through-groove tool or the large-curvature tool,bigger flashes form on the joint surface and alclad layer is observed in the nugget zone（NZ）,deteriorating mechanical *** with the above-mentioned three tools,using the six-groove tool with rational curvature and obliquity can not only yield sound joint with small flashes and thickness reduction,but also prevent alclad from flowing into NZ,which has potential to weld thin alclad aluminum ***,the tensile strength and elongation of joint using the six-groove tool reach the maximum values of 362 MPa and 8.3%,up to 85.1% and 64% of BM.

关键词： Pinless friction stir welding Groove distribution 2A12-T4 aluminum alloy Macrostructures Mechanical property

Active-passive radial-additive friction stir repairing of mechanical hole out of dimension tolerance of AZ31 magnesium alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第9期11卷 3186-3199页

作者： Hua liu zhenlei liu Shude Ji Yumei Yue Zhibo Dong Changlong Chen College of Aerospace Engineering Shenyang Aerospace UniversityShenyang 110136China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

In order to avoid the depth increasing of repaired hole and eliminate the super-fine grain band in stir zone by radial-additive friction stir repairing(R-AFSR), a solid-state repairing technique of active-passive radial-additive friction stir repairing(AP-RAFSR) assisted by the truncated cone-shaped filling material was proposed in this study. The mechanical hole out of dimension tolerance of AZ31 magnesium alloy was chosen as the repaired object. The results indicated that the AP-RAFSR process rather than the R-AFSR process avoided the kissing bond in the bottom of the repairing interface under the condition of the tool pin length equal to the height of the standard mechanical *** continuously-distributed and large-length super-fine grain bands were eliminated in the stir zone by AP-RAFSR. The maximum tensile and compressive-shear strengths of repaired hole by AP-RAFSR reached 190.6 MPa and 138.9 MPa at 1200 rpm respectively, which were equivalent to 97.7% and 89.6% of those of the standard mechanical hole. This AP-RAFSR process assisted by the truncated cone-shaped filling material provides a new technique to obtain a no-depth-increasing, defect-free and high-strength repaired mechanical hole.

关键词： Active-passive radial-additive friction stir repairing Mechanical hole out of dimension tolerance Numerical simulation Microstructure Mechanical properties

Development of a procedure for estimating the parameters of mechanistic VOC emission source models from chamber testing data

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2021年第2期14卷 269-282页

作者： zhenlei liu Andreas Nicolai Marc Abadie Menghao Qin John Grunewald Jianshun Zhang Department of Mechanical and Aerospace Engineering Syracuse UniversitySyracuseUSA Dresden University of Technology DresdenGermany University of La Rochelle La RochelleFrance Technical University of Denmark Kongens LyngbyDenmark School of Architecture and Urban Planning Nanjing UniversityNanjingChina

In order to evaluate the impacts of volatile organic compounds(VOCs)emissions from building materials on the indoor air quality beyond the standard chamber test conditions and test period,mechanistic emission source models have been developed in the ***,very limited data are available for the required model parameters including the initial concentration(C_(m0)),in-material diffusion coefficient(D_(m)),partition coefficient(Kma),and convective mass transfer coefficient(k_(m)).In this study,a procedure was developed for estimating the model parameters by using VOC emission data from standard small chamber *** the procedure,initial values of the model parameters were refined by multivariate regression analysis of the measured emission *** verify the procedure and estimate its uncertainty,simulated chamber test data were generated by adding 10% experimental uncertainties on the theoretical curve from the analytical solution to a mechanistic emission *** the procedure was applied to the generated data to estimate the model *** indicated that estimates converged to the original parameter values used for the data generation and the error of estimated parameters D_(m1)C_(m0) and K_(ma) were within±10%,±23%,and±25%of the true values,*** procedure was further demonstrated by applying it to estimate the model parameters from real chamber test *** application of the procedure would result in a database of mechanistic source model parameters for assessing the impact of VOC emissions on indoor pollution load,which are essential input data for evaluating the effectiveness of various indoor air quality(IAQ)design and control strategies as well as the energy required for meeting given IAQ requirements.

关键词： building materials volatile organic compounds(VOCs) emission source model indoor air quality building energy efficiency

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于虚拟现实的火星车路径规划方法

计算机应用 2024年第S1期44卷 273-276页

作者：刘震磊王丹朱万安倪浩添李月月沈阳航空航天大学航空宇航学院沈阳110136 空军航空维修技术学院航空机械制造学院长沙410124

火星表面巡视探测具有环境复杂、资源受限等特点,火星车自主避障路径规划是在火星车运动能力约束下,综合安全性和效率,规划能够安全抵达目标位置的最优路径,对开展火星探测具有重要意义。针对火星车路径规划问题,提出一种基于虚拟现实... 详细信息

火星表面巡视探测具有环境复杂、资源受限等特点,火星车自主避障路径规划是在火星车运动能力约束下,综合安全性和效率,规划能够安全抵达目标位置的最优路径,对开展火星探测具有重要意义。针对火星车路径规划问题,提出一种基于虚拟现实技术的火星车路径规划方法。首先,在分析火星数字高程模型(DEM)数据、坡度处数据、粗糙度数据和阶梯地形数据的基础上,建立火星环境危险度地图;其次,设计集成危险度函数的改进A*算法,在虚拟现实开发引擎Unity3D中开发火星车路径规划系统;最后,对路径规划算法进行仿真验证。实验结果表明,与传统A*算法相比,改进A*算法的危险度显著降低,有效提高了火星车行驶的安全性,验证了虚拟现实技术在火星车路径规划的可行性。

关键词：虚拟现实火星探测路径规划火星车改进A*算法

Influences of Synthesis Conditions on the Formation of Methotrexate Intercalated Layered Double Hydroxides by Exfoliation-reassembly Route

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2019年第5期35卷 901-907页

作者： liu zhenlei JIA Qingyang ZHAO Xiufen LI Shuping SHEN Jian LI Xiaodong Jiangsu Key Laboratory of Biofunctional Material College of Chemistry and Material ScienceNanjing Normal UniversityNanjing 210023P.R.China

The intercalation of methotrexate(MTX) into layered double hydroxides(LDHs) via an exfoliation-reassembly process was performed and the resulting hybrids were then characterized by X-ray difEractiometry( XRD), Fourier transform infrared(FTIR) spectroscopy, thermogravimetry(TG) and differential scanning calorimetry(DSC), etc. In the synthesis procedure, LDHs particles were firstly delaminated, and the reassembly process was performed to get MTX intercalated LDH(MTX/LDHs) hybrids. Tlie reassembly conditions, such as reassembly time and diflerent reassembly solvent, were studied emphatically. It was fbimd that 20 min is the optimum time and formamide is the most suitable solvent in the reassembly process. At last, the controlled release property and the drug-loading capacity were examined emphatically to reveal that MTX/LDHs hybrids reassembled in fomiamide exhibit the highest drug-loading capacity. The cytotoxicity of the hybrids was estimated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-/7-tetrazolium bromide, thiazolyl blue tetrazolium bromide(MTT) assays on the human lung cancer cells(A549), with the results showing that MTX/LDHs hybrids have effective suppress role on the proliferation of cancer cells, and tlie hybrids obtained from the formamide solution present much better anticancer efleet than the other samples.

关键词： Methotrexatum Layered double hydroxide Exfoliation-reassembly process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

智能工厂MINI制造单元虚拟仿真平台开发

现代信息科技 2024年第16期8卷 172-177页

作者：刘静娴刘震磊朱万安邵鑫雨郭靖玮沈阳航空航天大学航空宇航学院辽宁沈阳110136

针对航空薄壁件在加工中易变形、工件振动、耗时长的现状,提出了基于Unity3D的智能工厂MINI制造单元虚拟仿真平台的设计方案,解决了薄壁叶片在实际生产过程中效率低下,质量参差不齐的问题。通过智能工厂MINI制造单元的虚拟仿真验证结果... 详细信息

针对航空薄壁件在加工中易变形、工件振动、耗时长的现状,提出了基于Unity3D的智能工厂MINI制造单元虚拟仿真平台的设计方案,解决了薄壁叶片在实际生产过程中效率低下,质量参差不齐的问题。通过智能工厂MINI制造单元的虚拟仿真验证结果表明,智能工厂MINI制造单元不仅能够完成航空薄壁件的批量加工,大大提高其生产效率,还能通过Unity3D的虚拟仿真技术,降低生产成本和潜在的风险,推动航空制造业向智能化方向发展。

关键词：智能工厂虚拟现实 MINI制造单元平台开发

在线全文

学校读者我要写书评

暂无评论

超临界CO_(2)海底管道材料设计研究

电焊机 2024年第4期54卷 98-103页

作者：李晔朱加祥付现桥陈紫苑李子茂刘振雷中国石油工程建设有限公司华北分公司河北任丘062522

随着CO_(2)海底封存技术的势在必行,海底超临界CO_(2)输送管道应用应运而生。为指导海底超临界CO_(2)管道的设计,通过分析超临界CO_(2)腐蚀性确定海底管道的腐蚀裕量,通过分析海底管道的特殊安装方式及服役特点结合超临界CO_(2)的泄压特... 详细信息

随着CO_(2)海底封存技术的势在必行,海底超临界CO_(2)输送管道应用应运而生。为指导海底超临界CO_(2)管道的设计,通过分析超临界CO_(2)腐蚀性确定海底管道的腐蚀裕量,通过分析海底管道的特殊安装方式及服役特点结合超临界CO_(2)的泄压特性,得出钢管的强度、硬度、塑性变形、韧性等力学性能设计指标。同时建立了超临界CO_(2)海底管道断裂控制计算方法,并指出现有方法存在的问题及后续的研究重点。

关键词：超临界CO_(2) 韧性断裂海底管道力学性能

维普期刊数据库博看期刊

基于TQWT及SVM算法的有载分接开关带电检测技术研究

在线全文

学校读者我要写书评

暂无评论

变压器 2024年第2期61卷 44-50页

作者：栾兰吕腾飞姜良刚王培仑刘振雷时培征山东电工电气集团数字科技有限公司山东济南250022

在变压器带电情况下,有载分接开关(OLTC)振动信号可反应其运行状态。对振动信号特征参量进行提取分析和故障诊断可辅助实现变压器健康状态预警。本文采用优化后的小波包算法:品质因子可调小波变换算法(TQWT)提取检测装置获取的振动信号... 详细信息

在变压器带电情况下,有载分接开关(OLTC)振动信号可反应其运行状态。对振动信号特征参量进行提取分析和故障诊断可辅助实现变压器健康状态预警。本文采用优化后的小波包算法:品质因子可调小波变换算法(TQWT)提取检测装置获取的振动信号有效信息,克服小波滤波器导致的频率混淆现象,消除频率折叠,有效提高特征参量的准确性。通过支持向量机算法(SVM)对振动特征信号进行故障类型识别。在此基础上研制有载分接开关带电检测装置,实现了对有载分接开关运行状态量的现场检测和分类,大幅度减少了现场检修人员工作量,提高检修人员工作效率。

关键词：有载分接开关特征提取故障诊断 TQWT SVM