检索结果-南通市图书馆

气体雾化过程中涉及颗粒形貌和空心颗粒形成的金属液滴变形和破碎数值模拟

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2024年第7期34卷 2074-2094页

作者：汪鹏黎兴刚周香林陈志培王淼辉甘萍任晓娜余志勇北京科技大学新金属材料国家重点实验北京100083 中机新材料研究院(郑州)有限公司郑州450001 南方科技大学材料科学与工程系深圳518055 北京科技大学材料科学与工程学院北京100083 中国联合重型燃气轮机技术有限公司北京100016

采用考虑液滴冷却和凝固的流体体积(VOF)方法模拟金属液滴在气体雾化过程中的变形和破碎。建立典型粉末形貌和液滴破碎行为之间的相关性,以指导球形粉末颗粒的制备。结果显示,当增加液滴的气动力与黏性力的比值时,球形颗粒的形成得到加... 详细信息

采用考虑液滴冷却和凝固的流体体积(VOF)方法模拟金属液滴在气体雾化过程中的变形和破碎。建立典型粉末形貌和液滴破碎行为之间的相关性,以指导球形粉末颗粒的制备。结果显示,当增加液滴的气动力与黏性力的比值时,球形颗粒的形成得到加强;然而,当减小这个比值时,预期的液滴破碎模型将被改变或仅仅只发生液滴的变形。从空心颗粒的形成和演变过程的数值模拟中观察到几种典型的情况,例如,开放的空心液膜的形成、液膜封闭、气泡的离心和气泡的脱离。通过提高气体速度或液滴温度,实现较高的非平衡拉普拉斯压力或较低的粘性力,促使气泡从液滴内部分离。

关键词：液滴破碎空心颗粒颗粒形貌黏性力金属粉末气体雾化

Deposition behavior of multi-particle impact in cold spraying process

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 635-640页

作者： xiang-lin zhou xiang-kun Wu Hui-hua Guo Jian-guo Wang Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science mad Technology Beijing Beijing 100083 China

In the practical cold-spraying process, a number of particles impact onto a substrate and then form a coating. To study the deformation behavior and multi-particle interactions, single-particle, two-particle, and three-particle impacts were simulated using the ANSYS/LS-DYNA version 970. A copper coating was prepared and scanning electron microscopy （SEM） was employed to analyze the microstructures of the powders and the coating. Numerical results reveal that the critical deposition velocity is 600 m/s for a copper particle/copper substrate. The particles deform more fully due to multi-particle interactions, such as tamping, interlocking, and extrusion effects. The compression ratio increases from 40% to 70% as a result of the tamping effect. This is beneficial for achieving the cold-sprayed coating. The multi-particle morphology and compression ratio in the experiment are consistent with those of simulation results. Based on these results, the coating of high performance can be prepared through selecting appropriate parameters and suitable pre-treatment processes.

关键词： spraying deposition interfaces particle interactions bonding simulation

Synthesis of nanocrystalline NiCrC alloy feedstock powders for thermal spraying by cryogenic ball milling

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2009年第1期16卷 77-83页

作者： Kai Tao xiang-lin zhou Hua Cui Han-bin Chen Yong-bing Li Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Nanocrystalline NiCrC alloy powders with a qualified particle size distribution for thermal spraying were synthesized using the cryogenic ball milling （cryomilling） method. The morphology, microstructure, size distribution, and phase transformation of the powders were characterized by scanning electron microscopy （SEM）, laser scattering for particle size analysis, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. After cryomilling for 20 h, the average grain size of the as-milled powders approached a constant value of 30 nm by XRD measurement. The average particle size slightly increased from 17.5 to 20.3 μm during the 20-h milling. About 90vol% of the powders satisfied the requirement for thermal spraying with the particle dimension of 10-50 μm, and most of the powders exhibited spherical morphology, which were expected to have good fluidity during thermal spraying. The Cr2O3 phase formed during the cryornilling process as revealed in the XRD spectra, which was expected to enhance the thermal stability of the as-milled powders during the followed thermal spraying or other heat treatment.

关键词： cryomilling nanocrystalline feedstock powder particle size distribution nickel chromium alloy

Stability of NiCrAlY coating/titanium alloy system under pure thermal exposure

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2017年第8期36卷 659-665页

作者： Xiao-Min Peng An-Ru Wu Li-Jun Dong You-Rui Tao Wei-Guo Gao xiang-lin zhou State Key Laboratory of Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China School of Mechanical Engineering Hunan Institute of EngineeringXiangtan 411101China

In this paper,NiCrAlY coating was deposited on TC4 titanium alloy using arc ion plating,and the stability of NiCrAlY coating/TC4 substrate system under pure thermal exposure was analyzed in a wide temperature *** the thermal exposure,β→γ′→γphase transformation takes place in the NiCrAlY *** NiCrAlY coating phases totally decompose above the allotropic transformation temperature of *** allotropic transformation ofα-Ti to β-Ti of the substrate significantly influences the stability of NiCrAlY coating/TC4 substrate *** coating elements are mainly consumed by interfacial reactions below the allotropic transformation temperature of *** the allotropic transformation temperature of TC4,NiCrAlY coating elements are mainly consumed by element dissolution in β-*** NiCrAlY coating totally degrades for the dissolution of coating elements in the substrate to form thickβ-Ti stabilized layer.

关键词： NiCrAlY coating Titanium alloy Stability Pure thermal exposure Degradation

Ballistic performance of spaced multi-ply soft fabrics: Experimental and numerical investigation

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第4期34卷 143-155页

作者： Zhongwei Zhang Xiaoning Yang Yuan lin Ziming Xiong Yuhang xiang Yi zhou Mingyang Wang State Key Laboratory of Explosion&Impact and Disaster Prevention&Mitigation Army Engineering University of PLANanjing 210007China School of Mechanical Engineering Nanjing University of Science&TechnologyNanjing 210007China State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200China Postdoctoral Station of Civil Engineering Army Engineering University of PLANanjing 210007China

It has been reported that the ply gap influences the ballistic resistance of spaced multi-ply fabric systems,but its working mechanism was not well-understood. This paper reports the experimental and numerical approaches and results of an investigation on the mechanisms that enable the improved ballistic performance of spaced multi-ply systems. Penetration tests were performed over a range of impact velocities ranging from 200 m/s to 400 m/s. The results confirmed that the ply gap is beneficial to the energy absorption capability of the systems. This is because the front plies tend to absorb more energy when they are not immediately constrained by the rear plies. During a ballistic event, the gap relieves the reflection of the compressive pulse, prolonging the projectile engagement time with the front plies;on the other hand, the rear plies become increasingly less active in dissipating energy as the gap *** the gap is sufficiently widened to avoid any interference between the plies before the failure of the front ply, the responses of the whole system no longer vary. It was also found that the ballistic performance of the spaced systems is influenced by ply thickness, impact velocity, and the stacking order of the ply gap.

关键词： Energy absorption capability Ply gap Ballistic performance The front ply The rear ply

Global Dynamic Responses and Progressive Failure of Submerged Floating Tunnel Under Cable Breakage Conditions

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第4期38卷 676-688页

作者： zhou xiang-bo QIAO Dong-sheng WANG Ming TANG Guo-qiang LU lin OU Jinping State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

The Submerged Floating Tunnel(SFT)relies on a tensioned mooring system for precise *** sudden breakage of a single cable can trigger an immediate alteration in the constraint conditions of the tube,inducing a transient heave response within the structure along with a transient increase in cable tension experienced by adjacent *** more severe cases,this may even lead to a progressive failure culminating in the global destruction of the *** study used ANSYS/AQWA to establish a numerical model of the entire length SFT for the hydrodynamic response analysis,and conducted a coupled calculation of the dynamic responses of the SFT-mooring line model based on Orca Flex to study the global dynamic responses of the SFT at the moment of cable breakage and the redistribution of cable internal *** most unfavorable position for SFT cable breakage was identified,the influence mechanism of cable breakage at different positions on the global dynamic response was revealed,and the progressive chain failure pattern caused by localized cable breakage are also clarified.

关键词： submerged floating tunnel cable breakage global dynamic responses progressive failure

Miniaturized power detection module operating in millimeter wave band

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2024年第2期22卷 69-76页

作者： xiang zhou Zhi-Yong Zhong School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu611731China

The miniaturized broadband detection module can be embedded into the microwave application system such as the front end of the transmitter to detect the power or other parameters in real *** is highly prospective in military and scientific *** this paper,a broadband power detection module operating at 26.5 GHz-40.0 GHz is designed by using low-barrier Schottky diode as the detector and a comparator for threshold *** module can dynamically detect the power range between-10 dBm and 10 dBm with the detection accuracy of 0.1 ***,the temperature compensation circuit is also applied to improve the measurement *** a result,the resulted error low to±1 dB in the temperature range of -55℃ to +85℃ is *** designed module is encapsulated by a Kovar alloy with a small volume of 9 mm×6 mm×3 *** endows the designed module the advantages of small size,easy integration,and low cost,and even it is applicable to high-reliability environments such as satellites.

关键词： Diode Miniaturization Power detection Temperature compensation

Fracture sealing performance of granular lost circulation materials at elevated temperature:A theoretical and coupled CFD-DEM simulation study

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

Petroleum Science 2024年第1期21卷 567-581页

作者： Chong lin Qi-Cong Xu Lie-xiang Han Gao Li Hai He Hong-ling zhou Ji-Ping She CCDC Drilling&Production Technology Research Institute Guanghan618300SichuanChina State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina College of Materials Science and Engineering Chongqing UniversityChongqing400044China State Key Lab of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology) Chengdu610059SichuanChina College of Energy Chengdu University of TechnologyChengdu610059SichuanChina

Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)*** circulation material(LCM)is a regular preventive and remedial measure for lost ***,conventional LCMs seem ineffective in high-temperature *** may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature *** understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in *** summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling *** conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing *** results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid ***,softer,and less frictional LCM particles have lower bridging probability and slower bridging *** particles tend to form dual-particle bridges rather than single-particle *** result in a deeper,tighter,but unstable sealing *** drilling fluid viscosity leads to faster and shallower sealing zones.

关键词： Geothermal well drilling HTHP formationLost circulation material CFD-DEM Fracture sealing

A chromosome-level genome assembly for Chinese plum‘Wushancuili'reveals the molecular basis of its fruit color and susceptibility to rain-cracking

在线全文

学校读者我要写书评

暂无评论

Horticultural Plant Journal 2024年第3期10卷 672-688页

作者： Kun zhou Jingwen Wang lin Pan Fang xiang Yi zhou Wei Xiong Ming Zeng Donald Grierson Wenbin Kong lingyu Hu Wanpeng Xi College of Horticulture and Landscape Architecture Southwest UniversityChongqing 400715China Key Laboratory of Agricultural Biosafety and Green Production of Upper Yangtze River(Ministry of Education) Southwest UniversityChongqing 400715China Department of Pomology Chongqing Agricultural Technology Extension StationChongqing 401420China Plant and Crop Sciences Division School of BiosciencesUniversity of NottinghamSutton Bonington CampusLoughborough LE125RDUK Wuxi Economical Crop Technology Extension Station Chongqing 405800China

Chinese plum(Prunus salicina lindl.)originates from China and makes a large contribution to the global production of *** ***‘Wushancuili'has a green coloration and high fruit quality and is economically important in eliminating poverty and protecting ecology in the Yangtze River Three Gorges ***,rain-induced cracking(rain-cracking,literally skin cracking caused by rain)is a limitation to‘Wushancuili'fruit production and causes severe *** study reported a high-quality‘Wushancuili'genome assembly consisting of a 302.17-Mb sequence with eight pseudo-chromosomes and a contig N50 of 23.59 Mb through the combination of Illumina sequencing,Pacific Biosciences HiFiⅢsequencing,and high-throughput chromosome conformation capture technology.A total of 25109 protein-coding genes are predicted and 54.17%of the genome is composed of repetitive sequences.‘Wushancuili'underwent a remarkable orthoselection during *** identification revealed that loss-of-function in four core MYB10 genes results in the anthocyanin deficiency and absence of red color,revealing the green coloration due to the residual high chlorophyll in fruit ***,the occurrence of cracking is assumed to be closely associated with cell wall modification and frequently rain-induced pathogen enrichment through transcriptomic *** loss of MYB10 genes might render fruit more susceptible to pathogen-mediated cracking by weakening the epidermal strength and reactive oxygen species(ROS)*** findings provided fundamental knowledge regarding fruit coloration and rain-cracking and will facilitate genetic improvement and cultivation management in Chinese plums.

关键词： Chinese plum Fruit coloration Fruit epidermis Genome MYB10 Rain-cracking