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STUDY ON PROPERTIES OF PULSE ELECTRODEPOSITED RE-Ni-W-P-SiC COMPOSITE COATINGS

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Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 111-116页

作者： z.C. guo X.Y. zhu R.D. Xu Faculty of Materials and Metallurgical Engineering Kunming University of Science and Technology Kunming 650093 China

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE （rare earth）-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6.

关键词： frequency duty cycle electrodeposition RE-Ni-W-P-SiC composite coating

MICROSTRUCTURES AND PROPERTIES OF RECIPROCATINGLY EXTRUDED Mg-6.4zn-1.1Y ALLOYS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： z.M. zhang C.J. Xu X.F. guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral Mg3 Yzn6 quasicrystalline phase can be produced in Mg-zn- Y system alloys when a proper amount of zn and Y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast Mg-6.4zn-1.1 Y alloy are analyzed. The microstructure of the as-cast Mg-6.4zn-1.1 Y alloy consists of the α-Mg solid solution, icosahedral Mg3Yzn6 quasicrystal, and Mg3 Y2zn3 and Mgzn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, Mg3 Y2 zn3 and Mgzn2 phases dissolved into the matrix, whereas, Mg3 Yzn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 MPa, 258.2 MPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast Mg-6.4zn-1.1 Y alloy, particularly for elongation. The high performance of the Mg-6.4zn-1.1 Y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion Mg-zn- Y alloy Icosahedral quasicrystal

Convergence of ADMM for multi-block nonconvex separable optimization models

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Frontiers of Mathematics in China 2017年第5期12卷 1139-1162页

作者： Ke guo Deren HAN David z. W. WANG Tingting WU School of Mathematical Sciences and Key Laboratory for NSLSCS of Jiangsu Province Nanjing Normal University Nanjing 210023 China School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore 639798 Singapore School of Science Nanjing University of Posts and Telecommunications Nanjing 210023China

For solving minimization problems whose objective function is the sum of two functions without coupled variables and the constrained function is linear, the alternating direction method of multipliers （ADMM） has exhibited its efficiency and its convergence is well understood. When either the involved number of separable functions is more than two, or there is a nonconvex function~ ADMM or its direct extended version may not converge. In this paper, we consider the multi-block *** optimization problems with linear constraints and absence of convexity of the involved component functions. Under the assumption that the associated function satisfies the Kurdyka- Lojasiewicz inequality, we prove that any cluster point of the iterative sequence generated by ADMM is a critical point, under the mild condition that the penalty parameter is sufficiently large. We also present some sufficient conditions guaranteeing the sublinear and linear rate of convergence of the algorithm.

关键词： Nonconvex optimization separable structure alternating directionmethod of rnultip!iers (.ADMM) Kurdyka-Lojasiewicz inequality

Palaeoskapha sichuanensis gen. et sp. nov. (Menispermaceae) from the Eocene Relu Formation in western Sichuan, West China

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植物分类学报 2007年第4期45卷 576-582页

作者： Frederic M. b. JACQUES guo Shuang-Xing Museum National d＇Histoire Naturelle D~partement Histoire de la Terre CP 38 UMR 5143 - USM 0203 8 rue Buffon 75231 Pads Cedex 05 France Nanjmg Institute of Geology and Palaeontology the Chinese Academy of Sciences Nanjing 210008 China Kunming lnstitute of botany the Chinese Academy of Sciences Ktmming 650204 China

Palaeoskapha sichuanensis gen. et sp. nov. of Menispermaceae is described here for the first time based on a well preserved fossil fruit. The specimen was found in the Relu Formation of western Sichuan, West China. The specimen, straight, boat-shaped endocarp with large ventral condyle, clearly belongs to the tribe Tinosporeae. The wide aperture of the double condyle, combined with a whole shape not deeply invaginated, indicates a genus different from what was already known to science for this tribe. This fossil widens the distribution of the tribe during Eocene from North America and Europe to Asia, where it was formerly unknown.

关键词：防已科始新世四川群系新种植物化石果实

Air purifier or fresh air system?A comparison of energy consumption and cost in urban China residential buildings

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Science China(Technological Sciences) 2024年第9期67卷 2637-2647页

作者： guo Yong SUN zhiWei WESCHLER Louise b zHANG YinPing Department of building Science Tsinghua UniversityBeijing 100084China beijing Key Laboratory of Indoor Air Quality Evaluation and Control Beijing 100084China Independent Researcher Colts Neck 07722NJUSA

Chinese urban residential buildings face serious indoor air quality *** purification systems(e.g.,air purifiers,fresh air systems)that supply fresh air or purify indoor air are widely used in residential buildings to improve indoor air *** the challenges of energy conservation and emission reduction,it is urgent to guide residents on choosing appropriate air purification *** key problem is how to identify the best air purification system with the lowest energy consumption or operating *** of air purification systems have rarely been conducted on the premise that they should deliver air such that the main indoor pollutant concentrations all meet air quality *** ignored in comparisons are the increased filtration resistance caused by dust accumulation on the filter and the cost of filter *** this study,we propose a method to compare residential air purification systems based on energy consumption and total cost,and we provide methods to select air purification systems in China's different climatic *** used a standard two-person bedroom as the example,and determined the most suitable(minimum cost or energy consumption)air purification systems for the capital cities of the provinces in Chinese mainland.

关键词： IAQ fresh air system air purifier energy consumption cost

Evolution of the Microstructure and Strength in the Nugget zone of Friction Stir Welded SiCp/Al-Cu-Mg Composite

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Journal of Materials Science & Technology 2014年第1期30卷 54-60页

作者： D.Wang b.L.Xiao Q.z.Wang z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences University of Science and Technology of China

A 6 mm-thick SiCp/2009AI composite plate was successfully joined by friction stir welding （FSW） using an ultrahard material tool to investigate the evolution of the microstructure and the strength in the nugget zone （Nz）. While some SiC particles were broken up during FSW, most of them rotated in the matrix. Large compound particles on the interfaces were broken off during FSW, whereas the amorphous layer and small compound particles remained on the interfaces. The dynamically recrystallized AI grains nucleated on the surface of fractured SiC particles during FSW, forming nano-sized grains around the SiC particles. The yield strength of the Nz decreased slightly due to the variation in the size, shape, and distribution of the SiC particles. The clean interfaces were beneficial to the load transfer between SiC particles and AI matrix and then increased the ultimate tensile strength of the Nz.

关键词： Metal-matrix composites Friction stir welding Microstructure Mechanical properties

Non-alcoholic fatty liver disease: What has changed in the treatment since the beginning?

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World Journal of Gastroenterology 2014年第39期20卷 14219-14229页

作者： bülent baran Filiz Akyüz Division of Gastroenterohepatology Department of Internal Medicine Istanbul University Istanbul Faculty of Medicine Capa 34093 Istanbul Turkey

Non-alcoholic fatty liver disease(NAFLD) is an umbrella term to describe the entire spectrum of this common liver disease. In patients with NAFLD, especially those with non-alcoholic steatohepatitis(NASH), most often have one or more components of the metabolic syndrome, but this is not universal. Although most patients with NAFLD share many clinical features, only a subset of patients develops significant liver inflammation and progressive fibrosis. On the other hand, not all patients with NASH exhibit insulin resistance. NASH can be seen in patients who are lean and have no identifiable risk factors. Many clinical studies have tried numerous drugs and alternative medicine, however, investigators have failed to identify a safe and effective therapy for patients with NASH. As summarized, the heterogeneity of pathogenic pathways in individual patients with NASH may warrant the development of an individualized treatment according to the underlying pathogenic pathway. The differentiation of pathogenetic targets may require the development of diagnostic and prognostic biomarkers, and the identification of genetic susceptibilities. At present, evidence-based medicine provides only a few options including life-style modifications targeting weight loss, pioglitazone and vitamin E in non-diabetic patients with biopsy-proven NASH.

关键词： Non-alcoholic steatohepatitis Pathogenesis Inflammation Fibrosis Life-style changes Pharmacologic treatment

A Parallel boundary Element Formulation for Tracking Multiple Particle Trajectories in Stoke’s Flow for Microfluidic Applications

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Computer Modeling in Engineering & Sciences 2015年第3期104卷 227-249页

作者： z.Karakaya b.baranoglu b.Çetin A.Yazici Computer Engng.Dept. Atilim UniversityTurkey Manufacturing Engng.Dept. Atilim UniversityTurkey Microfluidics & Lab-on-a-chip Research Group Mech.Engng.Dept.Bilkent UniversityTurkey Software Engng.Dept. Atilim UniversityTurkey

A new formulation for tracking multiple particles in slow viscous flow for microfluidic applications is *** method employs the manipulation of the boundary element matrices so that finally a system of equations is obtained relating the rigid body velocities of the particle to the forces applied on the *** formulation is specially designed for particle trajectory tracking and involves successive matrix multiplications for which SMP(Symmetric multiprocessing)parallelisation is *** is observed that present formulation offers an efficient numerical model to be used for particle tracking and can easily be extended for multiphysics simulations in which several physics involved.

关键词： boundary Element Method particle tracking Stoke's flow parallel computing

Achieving ultrahigh strength and ductility in high-entropy alloys via dual precipitation

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Journal of Materials Science & Technology 2023年第35期166卷 67-77页

作者： J.M.guo b.C.zhou S.Qiu H.J.Kong M.C.Niu J.H.Luan T.L.zhang H.Wu z.b.Jiao Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong KongChina The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China Department of Materials Science and Engineering City University of Hong KongHong KongChina State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

The strength-ductility trade-offhas been a longstanding dilemma in metallic *** we report an innovative approach to achieve a high strength-ductility synergy via dual precipitation of sheared and bypassed precipitates.(Ni_(2) Co_(2) FeCr)_(96-x) Al_(4) Nb_(x)(at.%)alloys strengthened by nanoscale L12 particles and Laves precipitates were selected as a model for this study,and their precipitate microstructures and mechanical properties were thoroughly *** dual-precipitation-strengthened alloys exhibit a yield strength of more than 1400 MPa,an ultimate tensile strength of over 1800 MPa,and a uniform elon-gation of 18%,thus achieving a high strength-ductility *** analysis reveals that the nanoscale L1_(2) precipitates contribute to the strength via the particle shearing mechanism,whereas the Laves phase provides the strengthening through the Orowan bypass *** study of deformation microstruc-tures shows that the L1_(2) precipitates are sheared by stacking faults,which facilitates long-range disloca-tion gliding through the *** a result,deformation induces the formation of hierarchical stacking fault networks and immobile Lomer-Cottrell locks,which effectively enhance the work hardening ca-pability and plastic stability,thereby resulting in a high ductility at high strength *** are piled-up against the interface between the Laves precipitates and matrix,which increases the work hardening capability at the early stages of plastic deformation but causes stress *** dual precipitation strategy may be useful for many other alloys for achieving superior mechanical properties for technological applications.

关键词： High-entropy alloy Dual precipitation Precipitation strengthening Deformation mechanism