检索结果-南通市图书馆

Microstructural Evolutions and Mechanical Properties of Energetic Al_(1) (TiZrNbTaMoCr)_(15) High-Entropy Alloys

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 620-632页

作者： xuan-Hong Cai Zhen-Hua Wang Ben Niu Jin-Feng li qing Wang Show authors Key Laboratory of Materials Modification By Laser Ion and Electron Beams(Ministry of Education)Engineering Research Center of High Entropy Alloy Materials(Liaoning Province)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Institute of Materials China Academy of Engineering PhysicsMianyang621908China

The present study focuses on investigating the microstructural evolutions and mechanical properties of energetic Al_(1)(TiZrNbTaMoCr)_(15) refractory high-entropy alloys with the different heat treatments at low Al content state. It is found that even with a reduction in the Al content, the strength of these alloys remains unaffected at room temperature and high temperature, while the plasticity improves significantly. In particular, the coherent BCC/B_(2) microstructure with needle-like B_(2) nanoprecipitates dispersed into the BCC matrix is formed in 873 K-aged Al_(1)Ti_(6)Zr_(2)Nb_(3)Ta_(3)Mo_(0.5)Cr_(0.5) alloy. Therefore, this alloy exhibits the highest compression yield strength (σ_(YS) = 1333 and 717 MPa) at room temperature and 1073 K, respectively. After 973 K-aged, the coherent BCC/B_(2) microstructure underwent destabilization, and the B_(2) phase transforms into the brittle Zr5Al3 phase which then coarsens and dominates the microstructure of S3-AlTa_(3) alloy after 1073 K-aged. Moreover, these current alloys exhibit exceptionally high theoretical exothermic enthalpy (ΔH), surpassing 11606 J·g^(−1), which highlights their significant potential as innovative high-performance energetic structural materials.

关键词： Refractory high-entropy alloy Coherent microstructure Mechanical property Exothermic enthalpy

Trustworthy Assurance of Service Interoperation in Cloud Environment

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

International Journal of Automation and computing 2011年第3期8卷 297-308页

作者： Bing li Bu-qing Cao Kun-Mei Wen Rui-xuan li State Key Laboratory of Software Engineering Wuhan University Wuhan 430072 PRC School of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 PRC School of Computer Science and Engineering Hunan University of Science and Technology Xiangtan 411201 PRC

Cloud computing can be realized by service interoperation and its essence is to provide cloud services through network. The development of effective methods to assure the trustworthiness of service interoperation in cloud environment is a very important problem. The essence of cloud security is trust and trust management. Combining quality of service （QoS） with trust model, this paper constructs a QoS-aware and quantitative trust-model that consists of initial trust value, direct trust value, and recommendatory trust value of service, making the provision, discovery, and aggregation of cloud services trustworthy. Hence, it can assure trustworthiness of service interoperation between users and services or among services in cloud environment. At the same time, based on this model, service discovery method based on QoS-aware and quantitative trust-model （TQoS-WSD） is proposed, which makes a solid trust relationship among service requestor, service provider and service recommender, and users can find trustworthy service whose total evaluation value is higher. Corapared to QoS-based service discovery （QoS-WSD） method, it is proved by the experiment for TQoS-WSD method that more accurate result of service discovery will be achieved by service requestor, while reasonable time cost is increased. Meanwhile, TQoS-WSD method strongly resists the effect of service discovery by untrustworthy QoS values and improves service invocation success-rate and thus assures trustworthiness of services interoperation.

关键词： Quality of service (QoS) trust service discovery service interoperation service invocation success-rate cloud computing.

Precise Deviations for Discrete Ensembles

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2023年第8期39卷 1580-1596页

作者： Wen xuan CHEN Fu qing GAO School of Mathematics and Statistics Wuhan UniversityWuhan 430072P.R.China

We consider precise deviations for discrete ***β=2 case,we first establish an asymptotic formula of the Christoffel–Darboux kernel of the discrete orthogonal polynomials on an infinite regular lattice with weight e^(−NV(x)).Then we use the asymptotic formula to get the precise deviations of the extreme value for corresponding ensemble.

关键词： Discrete ensemble precise deviation random growth model Riemann-Hilbert problem

Efficient query processing framework for big data warehouse： an almost join-free approach

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2015年第2期9卷 224-236页

作者： Huiju WANG Xiongpai QIN xuan ZHOU Furong li Zuoyan QIN qing ZHU Shan WANG DEKE Lab (Renmin University of China) Beijing 100872 China School of Information Renmin University of China Beijing 100872 China School of Computing National University of Singapore Singapore 117417 Singapore

The rapidly increasing scale of data warehouses is challenging today＇s data analytical technologies. A con- ventional data analytical platform processes data warehouse queries using a star schema -- it normalizes the data into a fact table and a number of dimension tables, and during query processing it selectively joins the tables according to users＇ demands. This model is space economical. However, it faces two problems when applied to big data. First, join is an expensive operation, which prohibits a parallel database or a MapReduce-based system from achieving efficiency and scalability simultaneously. Second, join operations have to be executed repeatedly, while numerous join results can actually be reused by different queries. In this paper, we propose a new query processing frame- work for data warehouses. It pushes the join operations par- tially to the pre-processing phase and partially to the post- processing phase, so that data warehouse queries can be transformed into massive parallelized filter-aggregation oper- ations on the fact table. In contrast to the conventional query processing models, our approach is efficient, scalable and sta- ble despite of the large number of tables involved in the join. It is especially suitable for a large-scale parallel data ware- house. Our empirical evaluation on Hadoop shows that our framework exhibits linear scalability and outperforms some existing approaches by an order of magnitude.

关键词： data warehouse large scale TAMP join-free,multi-version schema

Mucosal lesions of the upper gastrointestinal tract in patients with ulcerative colitis:A review

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2021年第22期27卷 2963-2978页

作者： Yan Sun Zhe Zhang Chang-qing Zheng li-xuan Sang Department of Gastroenterology Shengjing Hospital of China Medical UniversityShenyang 110022Liaoning ProvinceChina

Ulcerative colitis(UC)is a chronic,nonspecific,relapsing inflammatory bowel *** colorectum is considered the chief target organ of UC,whereas upper gastrointestinal(UGI)tract manifestations are ***,emerging evidence has suggested that UC presents complications in esophageal,stomachic,and duodenal mucosal ***,UC-related UGI tract manifestations are varied and frequently silenced or ***,the endoscopic and microscopic characteristics of UGI tract complicated with UC are ***,UGI involvement may be ignored by many *** addition,no standard criteria have been established for patients with UC who should undergo ***,specific treatment recommendations may be needed for patients with UC-associated UGI ***,we review the esophageal,gastric,and duodenal mucosal lesions of the UC-associated UGI tract,as well as the potential pathogenesis and therapy.

关键词： Ulcerative colitis Upper gastrointestinal tract Inflammatory bowel disease Endoscopic and microscopic manifestations

A mechanically robust egg white hydrogel scaffold with excellent biocompatibility by three-step green processing

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

Science China(Technological Sciences) 2022年第7期65卷 1599-1612页

作者： WEI Zhen-Zhen DONG xuan ZHANG Yu-qing School of Biology and Basic Medical Sciences Medical CollegeSoochow UniversitySuzhou 215123China College of Chemistry Chemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China

Egg white(EW) is one of the most common and high-quality nutritional proteins. A novel three-step green processing technology is constructed to process homogeneous EW into a mechanically robust EW hydrogel scaffold(EWHS) with excellent biocompatibility. The homogeneous EW is first treated with stream to form a hydrogel, then slowly dehydrated to form a fragile and almost transparent EW glass, and finally annealed into an EWHS. The EWHS is water-insoluble, wet soft and translucent and has a porous network structure, and its pore size distribution is between 0.1–1.0 μm. The tensile strength in wet state is as high as 5.0 MPa, the elongation at break is about 93%, and the swelling rate is about 85%. The order of the enzymatically residual rate of these EWHSs is pepsin > neutral protease > papain> trypsin > alkaline protease. Mouse L929 cells can adhere,proliferate, and grow well on the EWHSs. After EWHS was implanted in rats for three weeks, the levels of IL-6, TNF-α, and NF-κB inflammatory factors did not change significantly in comparison with the pseudo-operated and normal groups. This novel EW hydrogel biomaterial has potential applications in medical 3 D tissue engineering materials, such as tendons, soft tissues, and in vivo implants.

关键词： egg white hydrogel scaffolds dehydration heat treatment mechanical properties swelling rate

同方期刊数据库

Containment of high-speed rotating disk fragments

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第9期13卷 665-673页

作者： Hai-jun xuan Lu-lu liU Yi-ming FENG qing HE Juan-juan li High-Speed Rotating Machinery Laboratory Institllte of Chemical MachineryFacldly of EngineeringZhejiang UniversityHangzhou 310027China

Disk burst accidents sometimes happen in *** avoid tragic consequences,aeroengine casings must have sufficient containment *** and simulations need to be conducted to study the impact,distortion,and perforation caused by disk burst and which may give important clues to potential failure *** paper presents some containment tests of high-speed rotating disk fragments,in which the original disks were burst into three equal fragments within a predetermined rotating speed *** failure modes of the containment casing varied significantly with the thickness of the containment ***,tearing,tensile fracture,and large plastic stretching deformation occurred in a thin-walled containment casing,while a thick-walled casing could contain disk fragments and withstand large plastic *** simulations were carried out to study the impact process and failure modes *** agreement was found between the results of the simulations and the tests.

关键词： Aeroengine Disk fragments Engine casing Containment capability Numerical simulation

Escape probability for isotropic emitters near Kerr black hole with astrometric

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第5期76卷 128-133页

作者： Yu-xuan Han qing-Hua Zhu qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesNo.19A Yuquan RoadBeijing 100049China Department of Physics Chongqing UniversityChongqing 401331China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study UCASHangzhou 310024China

The paper investigates the escape probability for isotropic emitters near a Kerr black *** propose a new approach to obtain the escape probability in a general manner,going beyond previous case-by-case *** approach is based on studies of the black hole shadow with astrometric observable and can be applied to emitters with an arbitrary 4-velocities and locations,even to the emitters outside of the equatorial *** also consider representative examples illustrating how escape probabilities vary with distance,velocity,and inclination ***,this new approach provides an effective method for studying escape probabilities near Kerr black holes.

关键词： Kerr black hole photon escape probability isotropic emitters

Particle simulations on propagation and resonance of lower hybrid wave launched by phased array antenna in linear devices

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2022年第7期24卷 119-128页

作者： Guanghui ZHU qing li xuan SUN Jianyuan XIAO Jiangshan ZHENG Hang li College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060People's Republic of China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026People's Republic of China School of Physics Beihang UniversityBeijing 100191People's Republic of China

In this work, we performed first-principles electromagnetic-kinetic simulations to study a phased antenna array and its interaction with deuterium plasmas within the lower hybrid range of frequency. We first gave wave accessibility and resonance results, which agree well with theoretical prediction. In addition, we further investigated the antenna power spectrum with different antenna phases in the presence of the plasma and compared it with that in a vacuum,which directly indicates wave coupling and plasma absorption. Furthermore, for the case with zero phasing difference, our simulation results show that, albeit the launch is away from the accessibility region, tunneling effect and mode conversion occurred, which enhanced coupling and absorption. Moreover, consistent interactions between the injected wave and the plasma concerning various antenna phase differences are shown. We presented the inchoate response of the plasma in terms of the launching directions. Our results could be favorable for the engineering design of wave heating experiments with a tunable phased antenna array in linear devices, such as simple magnetic mirrors or tandem mirrors.

关键词： LHW phased array antenna tunneling mode conversion particle-in-cell simulation