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

重力流关阀极限水锤特征及阀门关闭规律研究

中国给水排水 2024年第13期40卷 49-54页

作者：李朋宇俞晓东王开朗陈楠王皓臻河海大学水利水电学院江苏南京210098

长距离重力流输水工程关阀水锤是威胁管道系统安全的重要因素之一。首先分析了重力流关阀的极限水锤特征,将重力流末端关阀产生的极限水锤特征分为两个阶段,第一阶段为静水头值的恢复段,此段管线压力呈上升趋势,上升速率受关阀速率控制... 详细信息

长距离重力流输水工程关阀水锤是威胁管道系统安全的重要因素之一。首先分析了重力流关阀的极限水锤特征,将重力流末端关阀产生的极限水锤特征分为两个阶段,第一阶段为静水头值的恢复段,此段管线压力呈上升趋势,上升速率受关阀速率控制;第二阶段为水锤压力的波动段,当管线压力恢复到静水头值后,水锤波特征逐渐明显,压力最大值受到该段关阀速率控制。进一步推导了极限水锤压力最大值的理论计算公式,并结合水锤特征解释了长距离重力流输水工程最大关阀水锤压力取决于第二阶段关阀规律。再以某实际长距离重力流输水工程为例,模拟末端关阀过渡过程,分析不同关阀规律下系统的水锤压力,验证了重力流关阀水锤特征和理论计算公式,并在此基础上提出了分阶段关阀速率和折点开度的选择方法。

关键词：重力流极限水锤关阀规律压力

Mg对Al-22Si-10Ni合金组织和热学性能的影响

在线全文

学校读者我要写书评

暂无评论

铸造 2024年第2期73卷 174-179页

作者：李鹏宇张瑜璐李乙庚隋明冉南邵骏杜军华南理工大学材料科学与工程学院广东广州510640

Al-22Si-10Ni合金具有较高的导热性和较低的热膨胀特性,但硬度偏低,对其进行Mg合金化,研究Mg对该合金凝固组织和热学性能的影响。研究显示,Mg的加入主要影响合金的末期凝固进程,合金凝固末期反应由Al-Si-Al3Ni三元共晶反应向Al-Si-Mg2S... 详细信息

Al-22Si-10Ni合金具有较高的导热性和较低的热膨胀特性,但硬度偏低,对其进行Mg合金化,研究Mg对该合金凝固组织和热学性能的影响。研究显示,Mg的加入主要影响合金的末期凝固进程,合金凝固末期反应由Al-Si-Al3Ni三元共晶反应向Al-Si-Mg2Si三元共晶反应转变;热处理促进Mg_(2)Si析出,少量Mg加入后Al-22Si-10Ni合金的热导率小幅上升,继续添加Mg后,热导率出现下降;Mg对合金热膨胀系数影响较小,可显著提升合金的硬度。Al-22Si-10Ni-0.5Mg合金表现出优异的综合性能,其室温热导率130.3 W/(m·K),25~100℃范围内平均热膨胀系数为13×10^(-6)/K,硬度达到HV144,性能较为接近喷射沉积制备的高含量Al-50Si合金,具有成为电子封装用材料的潜能。

关键词： Al-22Si-10Ni合金凝固特性热导率热膨胀系数硬度

在线全文

学校读者我要写书评

暂无评论

硫酸法烷基化装置存在的腐蚀问题与解决措施

全面腐蚀控制 2024年第1期38卷 119-124页

作者：尚智李朋宇杨富淋大连西太平洋石油化工有限公司辽宁大连116600 沈阳中科韦尔腐蚀控制技术有限公司辽宁沈阳110000

大连某石化公司硫酸法烷基化装置自2013年重新投产运行以来,多个系统及部位发生过硫酸腐蚀泄漏,严重影响装置的安全平稳生产。根据各部位腐蚀情况,研究各腐蚀形成的机理,分析出现腐蚀的原因,制定有针对性的解决方案及措施,通过材质升级... 详细信息

大连某石化公司硫酸法烷基化装置自2013年重新投产运行以来,多个系统及部位发生过硫酸腐蚀泄漏,严重影响装置的安全平稳生产。根据各部位腐蚀情况,研究各腐蚀形成的机理,分析出现腐蚀的原因,制定有针对性的解决方案及措施,通过材质升级、保护优化、设备设施升级改造等手段,减少了装置腐蚀情况的发生。

关键词：硫酸法烷基化硫酸腐蚀材料解决措施

Polyhydroxylated eudesmane sesquiterpenoids and sesquiterpenoid glucoside from the flower buds of Tussilago farfara

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2022年第4期20卷 301-308页

作者： li yu-peng YANG Kang MENG Hui SHEN Tao ZHANG Hua School of Biological Science and Technology University of JinanJinan 250022China Key Laboratory of Chemical Biology(MOE) School of Pharmaceutical SciencesShandong UniversityJinan 250012China

Chemical fractionation of the n-BuOH partition,which was generated from the EtOH extract of the flower buds of Tussilago farfara,afforded a series of polar constituents including four new sesquiterpenoids(1-4),one new sesquiterpenoid glucoside(5)and one known analogue(6)of the eudesmane type,as well as five known quinic acid derivatives(7-11).Structures of the new compounds were unambiguously characterized by detailed spectroscopic analyses,with their absolute configurations being established by A-ray crystallography,electronic circular dichroism(ECD)calculation and induced ECD *** inhibitory effect of all the isolates against LPS-induced NO production in murine RAW264.7 macrophages was evaluated,with isochlorogenic acid A(7)showing significant inhibitory activity.

关键词： Tussilago farfara Eudesmane sesquiterpenoid Anti-inflammation NO production inhibition Quinic acid derivative

Fourth-order phase-field modeling for brittle fracture in piezoelectric materials

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

Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 837-856页

作者： yu TAN Fan peng Chang liU Daiming peng Xiangyu li State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Science Chang'an UniversityXi'an 710064China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Failure analyses of piezoelectric structures and devices are of engineering and scientific *** this paper,a fourth-order phase-field fracture model for piezoelectric solids is developed based on the Hamilton *** typical electric boundary conditions are involved in the present model to characterize the fracture behaviors in various physical situations.A staggered algorithm is used to simulate the crack *** polynomial splines over hierarchical T-meshes(PHT-splines)are adopted as the basis function,which owns the *** numerical simulations are performed to study the influence of the electric boundary conditions and the applied electric field on the fracture behaviors of piezoelectric *** electric boundary conditions may influence crack paths and fracture loads *** present research may be helpful for the reliability evaluation of the piezoelectric structure in the future applications.

关键词： isogeometric analysis(IGA) brittle fracture fourth-order phase-field model piezoelectric solid

Machine Learning-based Identification of Contaminated Images in light Curve Data Preprocessing

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第4期24卷 287-295页

作者： Hui li Rong-Wang li peng Shu yu-Qiang li yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Space Object and Debris Observation Chinese Academy of SciencesNanjing 210023China

Attitude is one of the crucial parameters for space objects and plays a vital role in collision prediction and debris *** light curves to determine attitude is the most commonly used *** photometric observations,outliers may exist in the obtained light curves due to various ***,preprocessing is required to remove these outliers to obtain high quality light *** statistical analysis,the reasons leading to outliers can be categorized into two main types:first,the brightness of the object significantly increases due to the passage of a star nearby,referred to as“stellar contamination,”and second,the brightness markedly decreases due to cloudy cover,referred to as“cloudy contamination.”The traditional approach of manually inspecting images for contamination is time-consuming and ***,we propose the utilization of machine learning methods as a *** Neural Networks and SVMs are employed to identify cases of stellar contamination and cloudy contamination,achieving F1 scores of 1.00 and 0.98 on a test set,*** also explore other machine learning methods such as ResNet-18 and light Gradient Boosting Machine,then conduct comparative analyses of the results.

关键词： techniques:image processing methods:data analysis light pollution

在线全文

学校读者我要写书评

暂无评论

全断面硬岩隧道掘进机岩体状态智能识别技术

建筑机械 2024年第8期 108-111页

作者：裴成元李鹏宇杨晨张娜新疆水发建设集团有限公司新疆乌鲁木齐830000 中铁工程装备集团有限公司河南郑州450016

全断面硬岩隧道掘进机在隧道施工领域应用广泛,如何快速对掌子面在掘岩体进行感知和识别成为行业研究热点。文章尝试2种方法开展研究:通过收集地质和施工大数据,建立岩机模型实时获取在掘岩体力学信息;基于机器视觉技术,对渣土进行图像... 详细信息

全断面硬岩隧道掘进机在隧道施工领域应用广泛,如何快速对掌子面在掘岩体进行感知和识别成为行业研究热点。文章尝试2种方法开展研究:通过收集地质和施工大数据,建立岩机模型实时获取在掘岩体力学信息;基于机器视觉技术,对渣土进行图像分析,构建围岩等级模型。对2种方法进行了总结,并对下一步研究方向进行了讨论。

关键词：岩体识别岩机模型渣片识别

Room-temperature ferroelectricity in van der Waals SnP_(2)S_(6)

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

Frontiers of physics 2024年第4期19卷 113-123页

作者： Chaowei He Jiantian Zhang li Gong peng yu State Key Laboratory of Optoelectronic Materials and Technologies Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices Nanotechnology Research Center School of Materials Science and EngineeringSun Yat-sen UniversityGuangzhou 510275China Instrumental Analysis and Research Center Sun Yat-sen UniversityGuangzhou 510275China

Two-dimensional(2D)ferroelectric materials,which possess electrically switchable spontaneous polarization and can be easily integrated with semiconductor technologies,is of utmost importance in the advancement of high-integration low-power *** the experimental discovery of certain 2D ferroelectric materials such as CuInP2S6 and In2Se3,achieving stable ferroelectricity at room temperature in these materials continues to present a significant ***,stable ferroelectric order at room temperature in the 2D limit is demonstrated in van der Waals SnP_(2)S_(6) atom layers,which can be fabricated via mechanical exfoliation of bulk SnP_(2)S_(6) *** polarization is observed in thin SnP_(2)S_(6) of~7 ***,a van der Waals ferroelectric field-effect transistor(Fe-FET)with ferroelectric SnP_(2)S_(6) as top-gate insulator and ptype WTe0.6Se1.4 as the channel was designed and fabricated successfully,which exhibits a clear clockwise hysteresis loop in transfer characteristics,demonstrating ferroelectric properties of SnP_(2)S_(6) atomic *** addition,a multilayer graphene/SnP_(2)S_(6)/multilayer graphene van der Waals vertical heterostructure phototransistor was also fabricated successfully,exhibiting improved optoelectronic performances with a responsivity(R)of 2.9 A/W and a detectivity(D)of 1.4×10^(12) *** results show that SnP_(2)S_(6) is a promising 2D ferroelectric material for ferroelectric-integrated low-power 2D devices.

关键词： two-dimensional ferroelectric materials ferroelectric fieldeffect transistors photodetectors

Research on the mechanism of the two-dimensional ultrasonic surface burnishing process to enhance the wear resistance for aluminum alloy

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

Friction 2024年第3期12卷 490-509页

作者： Zhen-yu ZHOU Qiu-Yang ZHENG yu li Cong DING Guang-Jian peng Zhong-yu PIAO College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Special Purpose Equipment and Advanced Processing Technology Ministry of Education and Zhejiang ProvinceZhejiang University of TechnologyHangzhou 310014China

The gradient nanostructure is machined on the aluminum(Al)alloy by the two-dimensional ultrasonic surface burnishing process(2D-USBP).The mechanism of why the gradient nanostructure enhances wear resistance is *** mechanical properties and microstructure characterization for the gradient nanostructure are performed by operating a nanoindenter,transmission electron microscopy(TEM),and electron backscattered diffraction(EBSD).Dry wear tests are performed on the samples before and after machining to evaluate the wear resistance and *** effect of the gradient nanostructure on the wear resistance is explored by developing the crystal plasticity(CP)finite element and molecular dynamics(MD)*** characterization results show that the 2D-USBP sample prepared a gradient structure of~600μm thick on the aluminum surface,increasing the surface hardness from 1.13 to 1.71 GPa and reducing the elastic modulus from 78.84 to 70.14 *** optimization of the surface microstructure and the increase of the mechanical properties effectively enhance the wear resistance of the sample,with 41.20%,39.07%,and 54.58% of the wear scar areas for the 2D-USBP treated samples to the original samples under 5,10,and 15 N loads,*** gradient nanostructure hinders the slip of dislocations inside the sample during the wear process and reduces the size and scope of plastic deformation;meanwhile,the resistance to deformation,adhesion,and crack initiation and propagation of the sample surface is improved,resulting in enhanced wear resistance.

关键词： structural superlubricity lattice registry elastic deformation strained solitons crystal plasticity molecular dynamics simulations