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Deformation characteristics and inertial effect of complex aluminum alloy sheet part under impact hydroforming:experiments and numerical analysis

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Advances in Manufacturing 2023年第2期11卷 311-328页

作者： Liang-Liang Xia Shi-Hong Zhang Yong Xu Shuai-feng Chen boris b.Khina Artur I.Pokrovsky Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016People's Republic of China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230000People's Republic of China Physical-Technical Institute National Academy of Science of Belarus220141MinskBelarus

Impact hydroforming(IHf),as a novel sheet metal forming technology with the advantages of high strain rate forming and flexible liquid loading,is highly suitable for efficiently manufacturing aluminum complex-shaped sheet *** this paper,deformation characteristics of complex sheet parts under IHf are systematically *** mechanical properties of 2024 aluminum alloy under a wide range of strain rates(10-3 s-1–3.3×103 s-1)were *** indicated that the elongation of 2024 aluminum alloy was improved by 116.01%under strain rates of 3.306-×-103 s-1,referring to 10-3 ***,a complex-shaped part with symmetrical and asymmetrical structures was *** deformation characteristics of sheet and role of inertial effect under IHf were investigated with well-developed solid–liquid coupling finite element(SLC-fE)model with high *** deformation tendency is found for symmetrical structure with notably prior deformation at central zone,showing a“bulging”profile at initial forming ***,synchronous deformation is presented for asymmetrical structure with a“flat”***,distinctive inertial effect was observed at different positions change for both symmetrical and asymmetrical structures,in which lower values were resulted at their central ***,the inertial effect evolved with the impacting ***,larger difference of inertial effect was observed with increasing impacting speed.

关键词： 2024 aluminum alloy Impact hydroforming High strain rate Inertial effect

Microstructure Dependent fatigue Cracking Resistance of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy

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Journal of Materials Science & Technology 2012年第7期28卷 614-621页

作者： Z.M. Song L.M. Lei b. Zhang X. Huang G.R Zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China AVIC Commercial Aircraft Engine Co. Ltd. Shanghai 200241 China Titanium Alloys Laboratory Beijing Institute of Aeronautical Materials Beijing 100095 China Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education School of Materials and MetallurgyNortheastern University Shenyang 110819 China

fatigue cracking behavior from a notch was investigated at room temperature for ***-3.5Mo-1.5Zr- 0.3Si （TClI） alloys with four different microstructures obtained at different cooling rates from the β transus temperature. It was found that the alloy with lamellar structures consisting of α/β lamellae or acicular α＇ martensite laths had a higher fatigue crack initiation threshold from the notch, while the bimodal structure with coarse a grain had a lower fatigue cracking resistance. The alloy with α/β lamellar structure showed a higher fatigue crack growth resistance. The length scales of the microstructures were characterized to correlate with fatigue cracking behavior. fatigue cracking mechanism related to microstructures was discussed.

关键词： Ti alloy fatigue crack initiation Crack propagation Microstructure

Comparing Operational Efficiency of Mobile Operators in brazil, Russia, India and China

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China & World Economy 2009年第5期17卷 104-120页

作者： Chun-Hsiung Liao Diána b.González Department of Communication and Transportation Management and Institute of Telecommunications Management National Cheng Kung University Institute of International Management National Cheng Kung University

Using partial factor productivity and data envelopment analysis approaches, this study measures and compares the operational efficiency of the 10 dominant mobile operators in brazil, Russia, India and China （bRIC） between 2002 and 2006. The results of data envelopment analysis indicate that the two leading brazilian mobile operators, Vivo and TIM, are fully efficient throughout the entire period of study, however, Indian mobile operators are the least efficient among bRIC operators. Interestingly, the findings of this study verify that full operational efficiency can be achieved by operators with large revenues, such as China Unicorn, and by other, y with medium and small revenues, such as Hvo, TIM and Oi. Partial faetor productivity demonstrates that 3 of the 4 brazilian mobile operators, Vivo, TIM and Oi, have remarkable productivity ratios, and that the state-owned operator, China Unicom, has the highest revenue per capital expenditure among bRIC operators. In contrast, Indian mobile operators ＇productivity ratios are generally low compared to other bRIC mobile carriers.

关键词： bRIC data envelopment analysis mobile operator operational efficiency partial factor productivity

Multidimensional modeling of the stenosed carotid artery: A novel CAD approach accompanied by an extensive lumped model

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Acta Mechanica Sinica 2014年第2期30卷 259-273页

作者： A.Kashefi M.Mahdinia b.firoozabadi M.Amirkhosravi G.Ahmadi M.S.Saidi Department of Mechanical Engineering Sharif University of Technology Department of Mechanical Engineering University of California Berkeley faculty of Engineering Department of Mechanical EngineeringSharif University of Technology faculty of Engineering Department of Mechanical and Aeronautical EngineeringClarkson University

This study describes a multidimensional 3D/lumped parameter（LP） model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the entire arterial network（48 arteries） was developed including the effect of vessel diameter tapering and the parameterization of resistance, conductor and inductor variables. A computer aided-design（CAD） algorithm was proposed to effciently handle the coupling of two or more 3D models with the LP model, and substantially lessen the coupling processing time. Realistic boundary conditions and Navier-Stokes equations in healthy and stenosed models of carotid artery bifurcation（CAb） were used to investigate the unsteady Newtonian blood flow velocity distribution in the internal carotid artery（ICA）. The present simulation results agree well with previous experimental and numerical studies. The outcomes of a pure LP model and those of the coupled 3D healthy model were found to be nearly the same in both cases. Concerning the various analyzed 3D zones, the stenosis growth in the ICA was not found as a crucial factor in determining the absorbing boundary *** paper demonstrates the advantages of coupling local and systemic models to comprehend physiological diseases of the cardiovascular system.

关键词： Hemodynamic 3D/LP coupling CAD Realis-tic boundary conditions Carotid artery bifurcation Stenosis

Erasure coding for distributed storage: an overview

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Science China(Information Sciences) 2018年第10期61卷 7-51页

作者： S.b.bALAJI M.Nikhil KRISHNAN Myna VAJHA Vinayak RAMKUMAR birenjith SASIDHARAN P.Vijay KUMAR Department of Electrical Communication Engineering Indian Institute of Science Ming Hsieh Department of Electrical Engineering University of Southern California

In a distributed storage system, code symbols are dispersed across space in nodes or storage units as opposed to time. In settings such as that of a large data center, an important consideration is the efficient repair of a failed node. Efficient repair calls for erasure codes that in the face of node failure,are efficient in terms of minimizing the amount of repair data transferred over the network, the amount of data accessed at a helper node as well as the number of helper nodes contacted. Coding theory has evolved to handle these challenges by introducing two new classes of erasure codes, namely regenerating codes and locally recoverable codes as well as by coming up with novel ways to repair the ubiquitous Reed-Solomon code. This survey provides an overview of the efforts in this direction that have taken place over the past decade.

关键词： distributed storage regenerating codes locally recoverable codes codes with locality erasure codes node repair

ERRATUM A TOPOLOGICALLY MIXING MAP WITH TRIVIAL ROTATION SET

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Annals of Differential Equations 1996年第4期12卷 502-503页

作者： f. H. Ghane & b. Honary(ferdowsi University of Mashhad, P. O. box 1159-91775, Mashhad)

We showed in [G. H], if f is a Cr-topologically mixing map of the circle (r ≥0),then its rotation set will be non-trivial. but this statement is only satisfied for generic(open and dense) subset of all Cr-topologically mixing maps of the circle (r≥0). Here,we present another proof of the above statement. Moreover, we introduce a topologicallymixing map of the circle with trivial rotation set.

关键词： ERRATUM A TOPOLOGICALLY MIXING MAP WITH TRIVIAL ROTATION SET

Phase angle obtained by bioelectrical impedance analysis independently predicts mortality in patients with cirrhosis

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World Journal of Hepatology 2017年第7期9卷 401-408页

作者： Giliane belarmino Maria Cristina Gonzalez Raquel S Torrinhas Priscila Sala Wellington Andraus Luiz Augusto Carneiro D'Albuquerque Rosa Maria R Pereira Valéria f Caparbo Graziela R Ravacci Lucas Damiani Steven b Heymsfield Dan L Waitzberg Department of Gastroenterology Surgical DivisionFaculdade de Medicina da Universidade de Sao Paulo Postgraduate Program in Health and behavior Universidade Católica de Pelotas Pennington biomedical Research Center Laboratory of.b.ne Metabolism Rheumatology DivisionFaculdade de Medicina da Universidade de Sao Paulo Research Institute Hospital do Coracao de Sao Paulo

AIM To evaluate the prognostic value of the phase angle(PA)obtained from bioelectrical impedance analysis(bIA) for mortality prediction in patients with cirrhosis. METHODS In total, 134 male cirrhotic patients prospectively completed clinical evaluations and nutritional assessment by bIA to obtain PAs during a 36-mo follow-up period. Mortality risk was analyzed by applying the PA cutoff point recently proposed as a malnutrition marker(PA ≤ 4.9°) in Kaplan-Meier curves and multivariate Cox regression models. RESULTS The patients were divided into two groups according to the PA cutoff value(PA > 4.9°, n = 73; PA ≤ 4.9°, n = 61). Weight, height, and body mass index were similar in both groups, but patients with PAs > 4.9° were younger and had higher mid-arm muscle circumference, albumin, and handgrip-strength values and lower severe ascites and encephalopathy incidences, interleukin(IL)-6/IL-10 ratios and C-reactive protein levels than did patients with PAs ≤ 4.9°(P ≤ 0.05). forty-eight(35.80%) patients died due to cirrhosis, with a median of 18 mo(interquartile range, 3.3-25.6 mo) follow-up until death. Thirty-one(64.60%) of these patients were from the PA ≤ 4.9° group. PA ≤ 4.9° significantly and independently affected the mortality model adjusted for Model for End-Stage Liver Disease score and age(hazard ratio = 2.05, 95%CI: 1.11-3.77, P = 0.021). In addition, Kaplan-Meier curves showed that patients with PAs ≤ 4.9° were significantly more likely to die. CONCLUSION In male patients with cirrhosis, the PA ≤ 4.9° cutoff was associated independently with mortality and identified patients with worse metabolic, nutritional, and disease progression profiles. The PA may be a useful and reliable bedside tool to evaluate prognosis in cirrhosis.

关键词： bioelectrical impedance analysis body composition Phase angle Nutritional assessment Liver disease Cirrhosis Mortality

Influence of addition of Gr_p/Al_2O_(3p )with SiC_p on wear properties of aluminum alloy 6061-T6 hybrid composites via friction stir processing

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Transactions of Nonferrous Metals Society of China 2013年第5期23卷 1275-1280页

作者： A.DEVARAJU A.KUMAR b.KOTIVEERACHARI Department of Mechanical Engineering National Institute of Technology

Aluminum alloy base surface hybrid composites were f.b.icated by incorporating with mixture of （SiC＋Gr） and （SiC＋Al2O3） particles of 20 μm in average size on an aluminum alloy 6061-T6 plate using friction stir processing （fSP）. Microstructures of.b.th the surface hybrid composites revealed that SiC, Gr and Al2O3 are uniformly dispersed in the nugget zone （NZ）. It was observed that the addition of Gr particles rather than Al2O3 particles with SiC particles, decreases the microhardness but immensely increases the dry sliding wear resistance of aluminum alloy 6061-T6 surface hybrid composite. The observed microhardness and wear properties are correlated with microstructures and worn micrographs.

关键词： aluminum alloy hybrid composite friction stir processing wear solid lubricant microstructure

CR6-interacting factor-1 contributes to osteoclastogenesis by inducing receptor activator of nuclear factor κb ligand after radiation

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World Journal of Stem Cells 2020年第3期12卷 222-240页

作者： Li-Xin Xiang Qian Ran Li Chen Yang Xiang feng-Jie Li Xiao-Mei Zhang Yan-Ni Xiao Ling-Yun Zou Jiang f Zhong Shengwen Calvin Li Zhong-Jun Li Laboratory Medicine Center Department of Blood TransfusionLab of Radiation BiologyThe Second Affiliated HospitalThird Military Medical UniversityChongqing400037China Department of Otolaryngology Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCA 90033United States bioinformatics Center College of Basic Medical SciencesThird Military Medical UniversityChongqing 400038China CHOC Children’s Research Institute Children’s Hospital of Orange CountyUniversity of CaliforniaIrvineCA 92868United States

bACKGROUND Radiation induces rapid bone loss and enhances bone resorption and adipogenesis, leading to an increased risk of.b.ne fracture. There is still a lack of effective preventive or therapeutic method for irradiation-induced bone *** activator of nuclear factor κb ligand(RANKL) provides the crucial signal to induce osteoclast differentiation and plays an important role in bone resorption. However, the mechanisms of radiation-induced osteoporosis are not fully *** To investigate the role of CR6-interacting factor-1(Crif1) in osteoclastogenesis after radiation and its possible *** C57 bL/6 mice were exposed to Co-60 gamma rays and received 5 Gy of wholebody sublethal irradiation at a rate of 0.69 Gy/min. for in vitro study, mouse bone marrow mesenchymal stem/stromal cells(bM-MSCs) were irradiated with Co-60 at a single dose of 9 Gy. for osteoclast induction, monocyte-macrophage RAW264.7 cells were cocultured with mouse bM-MSCs for 7 d. Clus Pro and Inter Pro Surf were used to investigate the interaction interface in Crif1 and protein kinase cyclic adenosine monophosphate(c AMP)-activited catalytic subunit alpha complex. Virtual screening using 462608 compounds from the Life Chemicals database around His120 of Crif1 was carried out using the program Autodock_vina. A tetrazolium salt(WST-8) assay was carried out to study the toxicity of compounds to different cells, including human bM-MSCs, mouse bMMSCs, and Vero *** Crif1 expression increased in bone marrow cells after radiation in *** of Crif1 in mouse bM-MSCs and radiation exposure could increase RANKL secretion and promote osteoclastogenesis in vitro. Deletion of Crif1 in bM-MSCs could reduce both adipogenesis and RANKL expression,resulting in the inhibition of osteoclastogenesis. Deletion of Crif1 in RAW264.7 cells did not affect the receptor activator of nuclear factor κb expression or osteoclast differentiation. following treatment with protein

关键词： Irradiation Osteoporosis bone marrow Mesenchymal stem cells Monocyte macrophage bone