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Improved multi-orientation dispersion of short carbon fibers in aluminum matrix composites prepared with Square crucible by mechanical stirring

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Journal of Materials Science & Technology 2020年第5期40卷 81-87页

作者： Guanglong Li Yingdong Qu Yaohua Yang Qiwen Zhou Xishi Liu Rongde Li School of Materials Science and Engineering Shenyang University of TechnologyShenyang110870China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China

In order to improve the strength of short carbon fibers reinforced aluminum matrix(Csf/Al)composite,the dispersion of short carbon fibers with multi-orientation was controlled with a Square crucible by mechanical stirring.The three-dimensional flow field models of liquid aluminum melt in the Square/round crucibles were established and calculated,and the results were compared.The calculated results show that turbulent flow could be induced both in the Square and round crucible,while the non-axisymmetric structure of the Square crucible results in higher turbulent kinetic energy in the melt.Therefore,the uniformity and multi-orientation dispersion of the short fibers can be improved by the intensive turbulent flow in the Square crucible,which will be increased by increasing the rotational velocity.The distribution of the short carbon fibers in the aluminum matrix prepared under different rotation velocities in Square crucible was experimentally investigated.With the increase of stirring velocity,the multi-orientation dispersion of the short fibers in the composites increased gradually.The experimental results are consistent with the calculation results.The tensile testing results show that the strength of the Csf/Al composite can reach 172 MPa when the rotational velocity is 1000 rpm,and it is 48.3%higher than that prepared by the round crucible under the same conditions,which results from the improved multi-orientation dispersion of short carbon fibers in aluminum matrix.

关键词： Square crucible Short carbon fibers Aluminum matrix composite Mechanical stirring Multi-orientation dispersion

Weighted estimates for bilinear Square functions with non-smooth kernels and commutators

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Frontiers of Mathematics in China 2020年第1期15卷 1-20页

作者： Rui BU Zunwei FU Yandan ZHANG Department of Mathematics Qingdao University of Science and TechnologyQingdao 266061China School of Mathematics and Statistics Linyi UniversityLinyi 276005China School of Mathematical Sciences Qufu Normal UniversityQufu 273100China

Under weaker conditions on the kernel functions,we discuss the boundedness of bilinear Square functions associated with non-smooth kernels on the product of weighted Lebesgue spaces.Moreover,we investigate the weighted boundedness of the commutators of bilinear Square functions(with symbols which are BMO functions and their weighted version,respectively)on the product of Lebesgue spaces.As an application,we deduce the corresponding boundedness of bilinear Marcinkiewicz integrals and bilinear Littlewood-Paley^-functions.

关键词： Bilinear Square function non-smooth kernel weight commutator BMO function

Effect of Richardson Number on Unsteady Mixed Convection in a Square Cavity Partially Heated From Below

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Fluid Dynamics & Materials Processing 2019年第2期15卷 89-105页

作者： Sacia Kachi Fatima-zohra Bensouici Nawel Ferroudj Saadoun Boudebous Faculty of Process Engineering University of Salah Boubnider Constantine 3Algeria Faculty of Sciences and Applied Sciences University of Larbi BenM'hidiOum el BouaghiAlgeria

The objective of the present study is to analyze the laminar mixed convection in a Square cavity with moving cooled vertical sidewalls.A constant flux heat source with relative length l is placed in the center of the lower wall while all the other horizontal sides of the cavity are considered adiabatic.The numerical method is based on a finite difference technique where the spatial partial derivatives appearing in the governing equations are discretized using a high order scheme,and time advance is dealt with by a fourth order Runge Kutta method.The Richardson number(Ri),which represents the relative importance of the natural and forced convection,is chosen as the bifurcation parameter.The effect of this non-dimensional number on the behavior of the fluid flow and the heat transfer is analyzed.Although the geometry and boundary conditions concerning the velocity and the temperature are symmetrical with respect to the vertical axis passing through the center of the cavity,the results show the existence of symmetric and asymmetric flow structures,varying according to the considered value of the Richardson number.

关键词： Richardson number mixed convection Square cavity finite difference method bifurcation

Syntactical analysis of the accessibility and sociability of a Square in the Kuala Lumpur City Center

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Frontiers of Architectural Research 2017年第4期6卷 456-468页

作者： Hossein Safaria Fataneh Fakouri Moridani Department of Architecture Rasht Branch Islamic Azad University Rasht Iran School of Graduate Studies and Technical Complex Islamic Azad University of Rasht Branch LahUan 44158-84715 Iran

The lack of visibility and the difficulty in developing a cognitive map may be particularly important in wayfinding and in categories where the use of accessibility and sociability will provide a Square suggestion in the Kuala Lumpur City Center Park (KLCC). This study attempted to examine the existing structure within the vicinity of KLCC and the transformations of its vicinity based on a Square suggestion through morphological analysis using axial analysis and observa-tions. The axial analysis shows how the accessibility of the Square has shifted within the city and compares it with an existing park. Moreover, a Square suggestion can provide context for the Petronas Twin Towers as a landmark and symbolic building. A Square, as a regular geometry, can aid in improving the configuration of the vicinity of KLCC. Consequently, this research is useful to architects, tourism managers, and urban designers because it demonstrates the importance of effective factors in sustaining accessible and sociable space, such as a Square.

关键词： Square Geometry Sociability Accessibility Kuala Lumpur City Center

Empty-nest elderly:mahjong and Chinese Square dance for improving the cognitive function in the community

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Frontiers of Nursing 2019年第1期6卷 71-76页

作者： Yue Zhang Marcia A.Petrini School of Health Science Wuhan University Chiang Mai University

Objective: The elderly population has proliferated worldwide. The empty-nest family pattern has become predominant among the aging people, and they are more vulnerable to the development of cognitive disorders. However, there is no standardized service in the community nursing care that includes procedures on how to improve the cognitive function of the elderly. Meanwhile, the booming number of empty-nest elderly stimulates the community nurses to assume the responsibility for their care. All of these bring more difficulties and opportunities for community nurses who are dedicated to the prevention of geriatric cognitive disorders.Methods: The authors reviewed the literature related to "empty-nest elderly", "cognitive function","mahjong",and "Chinese Square dance" in the Elsevier, Web of Science(WOS), China National Knowledge Infrastructure(CNKI), Springer and PubMed databases. The study illustrates the utility possibility of an efficient and straightforward method for improving the cognitive function among the elderly in the context of community nursing care in China and even in the rest of the world.Results: Mental and physical activity contributes to cognitive fitness and may be beneficial in delaying cognitive decline. Mental activities, such as playing mahjong, and physical activities, such as the Chinese Square dance, are common Chinese activities. Both of them can affect cognitive function in some way.Conclusions: China is experiencing one of its most severe aging problems. Community health personnel and related professionals may consider using mahjong and Chinese Square dance to promote psychological health in empty-nest elderly individuals in the community.

关键词： empty-nest elderly cognitive function mahjong Chinese Square dance

High-pseudocapacitance of porous and Square NiO@NC nanosheets for high-performance lithium-ion batteries

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Rare Metals 2021年第6期40卷 1451-1458页

作者： Ze-Lin Cai Zi-Lin Peng Meng-Qi Wang Jia-Yan Wu Hao-Sen Fan Yu-Fei Zhang School of Chemistry and Chemical Engineering Guangzhou UniversityGuangzhou 510006China School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou 510006China

Layered nickel oxides have been focused with intense research interests as high-performance lithium-ion batterie(LIB)anode.However,it is hard to obtain few layered nickel oxides material directly as it easily forms bulk material with the strong interaction between the interlayer.In this work,two-dimensional(2 D)nickel-based coordination polymers were successfully prepared according to aqueous phase copolymerization approach.And then uniform carbondoped NiO nanosheets were successfully obtained from facile solution assembly and post-thermal treatment.The detailed electrochemical testing shows that the uniform NiO nanocrystals encapsulated into porous N-doped carbon(NiO@NC)nanosheets present much higher rate capability with the discharge specific capacity of 782.7 mAh·g^(-1) at high current density of 2.0 A·g^(-1) than pure NiO(690 mAh·g^(-1)).It also shows long-term cycling performance with 91%retention after 50 cycles at 1.0 A·g^(-1).The high rate capability,cycling stability and the easy synthesis make NiO@NC nanosheets as a promising candidate for LIB anode and build up new way for the fabrication of metal oxides anode materials.

关键词： Anode Batteries Square NiO@NC nanosheets Pseudocapacitive

The Surface Profile of Laser Peening with Square Spots

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稀有金属材料与工程 2011年第S4期40卷 240-242页

作者： Zou S K1,2,Cao Z W1,Che Z G1,Li B21National Key Laboratory for Power Beam Processing Technologies,Beijing Aeronautical Manufacturing Technology Research Institute,Bei-jing 100024,China2Schoool of Mechanical of Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China Beijing Aeronaut Mfg Technol Res Inst Natl Key Lab Power Beam Proc Technol Beijing 100024 Peoples R China Huazhong Univ Sci & Technol Sch Mech Sci & Engn Wuhan 430074 Peoples R China

The surface profile of laser peened stainless steel was researched in this paper,a special lens was used to convert circle laser spot to Square spot,the difference of surface profile obtained by laser peening with circle laser spot was compared with that with Square laser spot.Laser peened zone showed steep depression at the edge with Square spot,but the surface in the shocked zone was very smooth.With suitable overlapped rate,Square spot can produce smoother surface profile than circle spot,and laser peening with Square spot is more effective than circle spot.

关键词： laser peening surface profile residual stress Square spot

Mean Square Average Generalized Consensus of Multi-Agent Systems Under Time-Delays and Stochastic Disturbances

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Journal of Systems Science & Complexity 2019年第2期32卷 588-599页

作者： QIU Li GUO Liuxiao LIU Jia School of Science Jiangnan University

Compared with the traditional consensus problem, this paper deals with the mean Square average generalized consensus(MSAGC) of multi-agent systems under fixed directed topology, where all agents are affected by stochastic disturbances. Distributed protocol depending on delayed time information from neighbors is designed. Based on Lyapunov stability theory, together with results from matrix theory and It o s derivation theory, the linear matrix inequalities approach is used to establish sufficient conditions to ensure MSAGC of multi-agent systems. Finally, numerical simulations are provided to illustrate the theoretical results.

关键词： Mean Square average generalized consensus multi-agent systems stochastic disturbances time delays

Numerical simulation of flow past a Square cylinder with a circular bar upstream and a splitter plate downstream

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Journal of Hydrodynamics 2019年第5期31卷 949-964页

作者： Yuan Ma MMRashidi Zhi-gang Yang Shanghai Automotive Wind Tunnel Center Tongji UniversityShanghai 201804China Shanghai Key Laboratory of Vehicle Aerodynamics and Vehicle Thermal Management Systems Shanghai 201804China Department o f Civil Engineering School of EngineeringUniversity of BirminghamBirminghamUK

A numerical investigation of flow past a Square cylinder with a circular bar upstream and a splitter plate downstream is carried out in this paper by lattice Boltzmann method(LBM).The combination of the three obstacles and LBM is the main novelty of the present study.The flow patterns are analyzed by a uniform flow of Reynolds number 100 based on the side length of the Square cylinder,D.Numerical simulations are performed in the range of 1≤Ds/D≤5,0≤G/D≤7 and 1≤L/D≤6,where Ds,G and L are the center-to center distance,surface-to-surface distance and the splitter plate length,respectively.Six flow patterns are observed in the present study.The maximum percentage reduction in mean drag coefficient is 68.76%at(ds,g,l)=(2.5,0,3)which is in pattern VI.The vortex shedding from the Square cylinder and the circular bar can be completely suppressed in pattern VI.The small distance between the Square cylinder and the splitter plate plays a more vital role in suppression of vortex shedding as compared with large distance and length.

关键词： Square cylinder lattice Boltzmann method(LBM) reduction of drag forces vortex shedding control circular bar splitter plate