检索结果-南通市图书馆

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

单站水下方位频率机动目标运动分析方法

声学学报 2024年第4期49卷 683-695页

作者：孙大军张艺翱滕婷婷胡哲健哈尔滨工程大学水声技术全国重点实验室哈尔滨150001 工业和信息化部海洋信息获取与安全工信部重点实验室(哈尔滨工程大学) 哈尔滨150001 哈尔滨工程大学水声工程学院哈尔滨150001

水下方位频率机动目标运动分析常需已知中心频率先验信息且存在机动检测错误等,因此提出了一种基于方位与多线谱信息融合的自适应无迹卡尔曼滤波算法。该算法将方位与多线谱频率信息融合处理,重新构建了方位−多线谱目标运动分析模型。... 详细信息

水下方位频率机动目标运动分析常需已知中心频率先验信息且存在机动检测错误等,因此提出了一种基于方位与多线谱信息融合的自适应无迹卡尔曼滤波算法。该算法将方位与多线谱频率信息融合处理,重新构建了方位−多线谱目标运动分析模型。将中心频率信息引入状态向量中构建实时迭代估计,同时引入了自适应时变渐消因子,实时调整过程噪声协方差矩阵使其适应机动目标。仿真与海试数据处理结果表明,所提方法的机动目标运动分析性能最优,其目标运动分析结果能以最快的速度逼近克拉美罗下界。

关键词：目标运动分析多线谱信息融合机动目标跟踪无迹卡尔曼滤波渐消因子

在线全文

学校读者我要写书评

暂无评论

多折角梯形台面折纸夹层结构的冲击防护性能

爆炸与冲击 2024年第4期44卷 34-46页

作者：何远鹏王凌峰杨秋松李哲健郝洪陈文苏广州大学工程抗震研究中心广东广州510006 广东省地震工程与应用技术重点实验室广东广州510006 科廷大学土木与机械工程学院基础设施监测与防护研究中心澳大利亚珀斯

多折角梯形台面折纸(truncated square pyramid,TSP)作为新型折叠结构,具有良好的抗冲击、能量吸收特性并具有模块化易加工的特点。基于此结构模块化形成了单层以及多层夹层板,利用空气炮试验装置研究了背板无支撑的夹层结构以及覆层结... 详细信息

多折角梯形台面折纸(truncated square pyramid,TSP)作为新型折叠结构,具有良好的抗冲击、能量吸收特性并具有模块化易加工的特点。基于此结构模块化形成了单层以及多层夹层板,利用空气炮试验装置研究了背板无支撑的夹层结构以及覆层结构,在不同冲击工况、边界条件下结构的冲击防护性能以及吸能特性。通过测量、对比单层夹层结构的位移时程及冲击后的失效模式,对抗冲击性能进行了评估。利用装于背板的多点压力传感器装置,测量冲击作用下覆层结构对背板不同位置的传递力时程,研究不同工况下的缓冲性能。对于背板无支撑夹层工况,背板的残余位移随冲击速度的增大而增大。对于覆层工况,双层覆层有较好的能量吸收和抗冲击性能,相比于单层表现出更充分的芯层利用率。此外,冲击位置通过改变模块单元的变形模式对覆层结构动态响应产生显著影响,尤其影响传递力峰值和峰值出现时间。研究结果可为TSP防护结构的工程设计和应用提供参考。

关键词：折叠结构覆层结构空气炮冲击动态响应抗冲击性能

Unveiling the mechanism of yttrium significantly improving high-temperature oxidation resistance of super-austenitic stainless steel S32654

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第20期115卷 103-114页

作者： Shucai Zhang Huabing Li zhouhua Jiang Hao Feng zhejian Wen Junyu Ren Peide Han School of Metallurgy Northeastern UniversityShenyang 110819China Key Laboratory for Ecological Metallurgy of Multimetallic Ores(Ministry of Education) Shenyang 110819China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China

Aiming at serious catastrophic oxidation problem of super-austenitic stainless steel S32654,the influence of different rare earth elements on its oxidation behavior was comparatively investigated at 1200℃.The mechanism of Y significantly improving high-temperature oxidation resistance of S32654 was *** results demonstrated that Y played much better beneficial roles than Ce and La in the initial formation of oxide layer:(1)Y promoted Cr segregation to steel surface to combine with O;(2)its preferential oxidation provided nucleation cores for Cr_(2)O_(3).Both roles jointly promoted the selective oxidation of Cr and then the formation of protective Cr-rich oxide *** provided good prerequisites for inhibiting the formation and volatilization of MoO_(3).Additionally,Y cation segregation to oxide grain boundaries further promoted the selective oxidation of Cr and Si to form more protective oxide *** beneficial roles of Y essentially eliminated the synergistic effects of MoO_(3) volatilization and lamellar Cr_(2)N precipitation on catastrophic ***,the oxidation resistance of Y-bearing S32654 was improved by 22%–45%.

关键词： Super-austenitic stainless steel Rare earth elements Yttrium Oxidation MoO_(3)volatilization Cr_(2)N precipitation

Preparation of unidirectional porous AlN ceramics via the combination of freeze casting and combustion synthesis

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第5期100卷 161-168页

作者： Zhilei Wei zhejian Zhang Xiaoyu Zhang Zhiyuan Li Tao Li Jiabin Hu Shunjian Xu Zhongqi Shi State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical and Electrical Engineering Xinyu UniversityXinyu 338000China

Unidirectional porous AlN ceramics(UP-AlNs)have attracted great attention for their wide applications in catalyst supports,filters and composite ***,traditional fabrication processes usually require high temperature and long production ***,UP-AlNs were successfully fabricated via the combination of tertiary butyl alcohol(TBA)-based freeze casting and combustion synthesis route using Al and AlN powders as raw *** microstructure,open porosity,thermal conductivity and compressive strength of UP-AlNs can be manipulated by synergistically regulating the AlN diluent content and Al/AlN solid loading of the freezing *** optimal UP-AlNs exhibited controllable structure wavelength(λ)and open porosity in a wide range of 21.1-47.1μm and 54.2%-86.0%,*** addition,the corresponding products also possessed anisotropic thermal conductivity and compressive *** novel route for the fabrication of UP-AlNs has the advantages of low cost,energy-saving and high efficiency,which shows significant promise for industrial applications.

关键词： AlN Freeze casting Combustion synthesis Thermal conductivity Compressive strength

Continuous SiC skeleton reinforced highly oriented graphite flake composites with high strength and specific thermal conductivity

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2022年第3期11卷 403-413页

作者： Xiaoyu ZHANG Wenqi XIE Lan SUN Zhilei WEI zhejian ZHANG Yuanyuan ZHU Jiabin HU Shenghe WANG Zhongqi SHI State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China State Grid Anhui Electric Power Co. Ltd.Hefei230061China

Highly oriented graphite-based composites have attracted great attention because of their high thermal conductivity(TC),but the low mechanical properties caused by the inhomogeneous distribution and discontinuity of reinforcements restrict the wide ***,continuous SiC ceramic skeleton reinforced highly oriented graphite flake(SiC/GF)composites were successfully prepared by combining vacuum filtration and spark plasma *** effect of SiC concentration on the microstructure,flexural strength,and thermophysical properties of the composites was *** GF grains in the composites exhibited high orientation with a Lotgering factor of>88%when the SiC concentration was≤30 wt%,and the SiC skeleton became continuous with the SiC concentration reaching 20 wt%.The formation of continuous SiC skeleton improved the flexural strength of the composites effectively while keeping the TC in a high ***,the composites with 30 wt%SiC exhibited the flexural strength up to 105 MPa,and the specific TC reaching 0.118 W·m^(2)·K^(−1)·*** composites with excellent flexural strength and thermophysical properties showed significant promise for thermal management applications.

关键词： ceramics composite materials high orientation flexural strength heat conduction

在线全文

学校读者我要写书评

暂无评论

具有界面复合活性层的高效纳滤膜构筑与性能

化学反应工程与工艺 2024年第2期40卷 116-125页

作者：邱杰孙哲建钱杰帖金鑫詹晓力张庆华浙江大学化学工程与生物工程学院杭州310058 浙江中烟工业有限责任公司杭州310008 浙江大学东海实验室浙江舟山316000

纳滤膜技术已广泛应用于水处理过程,但在长期运行过程中仍面临渗透通量下降和污染结垢等问题。本研究在多孔基材上将氨基功能化类沸石咪唑酯骨架-8(AZIF-8)与海藻酸钠(SA)水凝胶网络结合,构筑有机-无机纳米复合活性层高效凝胶网络,制... 详细信息

纳滤膜技术已广泛应用于水处理过程,但在长期运行过程中仍面临渗透通量下降和污染结垢等问题。本研究在多孔基材上将氨基功能化类沸石咪唑酯骨架-8(AZIF-8)与海藻酸钠(SA)水凝胶网络结合,构筑有机-无机纳米复合活性层高效凝胶网络,制备渗透性强、抗污染性能优异的复合纳滤膜(SAZM)。AZIF-8与SA水凝胶结合可以很好地克服纳米材料的团聚与相容性问题。杂化纳米凝胶网络赋予纳滤膜强的亲水性和抗污染性,为水分子的传输提供便捷路径。研究表明,SAZM对二价盐Na_(2)SO_(4)表现出稳定的截留性能,渗透通量从4.1×10^(-2)L/(m^(2)·h·k Pa)增加到16.3×10^(-2)L/(m^(2)·h·k Pa),提升297.6%。在牛血清白蛋白污染性实验中, SAZM表现出优异的抗污染性能,通量恢复率达95.1%。

关键词：纳滤膜纳米复合水凝胶抗污染脱盐

Preparation and anisotropic thermophysical properties of SiC honeycomb/Al-Mg-Si composite via spontaneous infiltration

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2019年第2期29卷 177-183页

作者： zhejian Zhang Zhongqi Shi Biguo Yang Bangzhi Ge Xiaoyu Zhang Yajie Guo State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Engineering Research Center of Transportation Materials of Ministry of Education School of Materials Science and Engineering Chang'an University

The SiC honeycomb/Al-Mg-Si composite with interpenetrated microstructure was prepared by spontaneous infiltration of Al-8 wt%Mg-7 wt%Si alloy into directional porous SiC honeycomb served as reinforcement. The microstructure and anisotropic thermophysical properties of this composite were also examined. The results showed that the initial microstructure of the SiC honeycomb can be retained and the as-prepared SiC honeycomb/Al-Mg-Si composite exhibited significantly anisotropic characteristics. Meanwhile, the alloying treatment on the Al matrix can avoid the generation of Al;C;and promote the wettability between Al and ***,the directional porous SiC honeycomb with such a low ceramic content（19 vol.%） made it possible for the composite to have a higher thermal conductivity(138.3 W/（m?K）) in the axial direction and a lower coefficient of thermal expansion(11.40 × 10;/K) in the radial *** influences of the SiC honeycomb reinforcement on the anisotropic thermophysical properties were also studied by the theoretical models in comparing with the experimental results.

关键词： SiC honeycomb Al-Mg-Si alloy Spontaneous infiltration Anisotropy Thermophysical properties

单船拖曳可控源电磁数据自适应分频匹配滤波消噪方法

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

地球物理学报 2023年第4期66卷 1732-1742页

作者：崔扬刘洋殷长春王典惠哲剑吉林大学地球探测科学与技术学院长春130026

海洋可控源电磁法(MCSEM,Marine Controlled-Source Electromagnetic Method)是一种工业化的主动源海洋电磁勘探方法,近年来在海底油气资源探测中收效显著,通过测量海底地下介质的电阻率变化,能够有效降低地震勘探方法的多解性.MCSEM的... 详细信息

海洋可控源电磁法(MCSEM,Marine Controlled-Source Electromagnetic Method)是一种工业化的主动源海洋电磁勘探方法,近年来在海底油气资源探测中收效显著,通过测量海底地下介质的电阻率变化,能够有效降低地震勘探方法的多解性.MCSEM的工作方式主要有单船拖曳与双船拖曳两类.单船拖曳信号具有强时变特征,近、中、远收发距信号强度变化极大.由于海水环境较为复杂,数据受到洋流、背景场、仪器等多种因素干扰,使得小收发距数据信噪比较高,中、远收发距数据信噪比较低,因此MCSEM数据随机干扰压制方法的研究难点在于适应数据的强时变特征.本文利用发射机数据与接收机数据的时间(空间)和频率对应关系,提出基于正则化条件和衰减函数约束的自适应分频匹配滤波方法.该方法首先通过计算原始接收机数据基频的振幅随偏移距变化(MVO,Magnitude Versus Offset)曲线获取衰减函数,然后利用该衰减函数将发射机所有频点数据进行振幅衰减,减低MCSEM发射机与接收机数据对应振幅的强时变差异,最后利用基于整形正则化条件的自适应匹配滤波方法压制接收机数据中的强振幅随机噪声.模型数据与实际数据的处理结果表明,本文提出的方法能够有效压制MCSEM数据中不同收发距的随机噪声干扰,保护具有强时变特征的接收机数据,提升整体数据质量.

关键词：海洋可控源电磁方法单船拖曳随机噪声压制衰减函数自适应分频匹配滤波

维普期刊数据库博看期刊

Oxidative Stress before and after Operation in Patients with Chronic Cholecystitis Containing Gallstone

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2000年第4期13卷 254-262页

作者： zhou JUN FU , CHEN PENG , YANG JIN LU +, ZHU YOU GEN + PENG CHENG HONG , AND WU YU LIAN  The 2nd Affiliated Hospital, Medical College of zhejiang University, 88 Jiefang Road, Hangzhou, 310009, zhejian 浙江大学浙江杭州 31 0 0 0 9 浙江金华市人民医院浙江京华 32 1 0 0 0

To study the relationship of oxidative, antioxidative constituents and antioxidases in blood with chronic cholecystitis containing gallstone, levels of lipoperoxides (LPO), nitric oxide (NO), vitamin C(VC), vitamin E (VE) and β carotene (β CAR) in plasma as well as level of LPO, activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH Px) in erythrocytes were investigated by spectrophotometric assay in 107 patients with this condition (PCg) and 100 healthy volunteers (HVs). Compared with HVs group, the average value of LPO and NO in plasma and that of LPO in erythrocytes of PCg group were significantly increased ( P <0.0001), while that of VC, VE and β CAR in plasma and the average activities of SOD, CAT and GSH Px in erythrocytes were significantly decreased ( P <0.0001). Linear regression and correlation analysis for 107 preoperative PCg showed that the value of LPO and NO in plasma and that of LPO in erythrocytes of PCg gradually increased ( P <0.0001), representing a significant linear positive correlation. The value of VC, VE and β CAR in plasma and that of SOD, CAT and GSH Px in erythrocytes of PCg gradually decreased ( P <0.0001), representing a significant linear negative correlation. Stepwise regression and correlation analysis for 107 preoperative PCg suggested that the closest correlation was observed between the course of disease and the value of NO and VC in plasma and that of SOD, GSH Px and LPO in erythrocytes, r =0.7306, F =32.1408, P <0.0001. Compared with the preoperative PCg group, the average value of LPO and NO in plasma and that of LPO in erythrocytes of the postoperative PCg group were significantly decreased ( P <0.0001). Furthermore, the average value of VC in plasma and that of SOD, CAT and GSH Px in erythrocytes of the postoperative PCg group were significantly increased ( P <0.0001), whereas no significant difference was found between their average value of VE and β CAR in pla

关键词： Wang with Chronic Cholecystitis Containing Gallstone Oxidative Stress before and after Operation in Patients