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Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses

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Acta Mechanica Sinica 2011年第5期27卷 833-839页

作者： fan.zhan.Yu-Bo fan Xiao-Yan Deng Key Laboratory for Biomechanics and Mechanobiologyof Ministry of Education School of Biological Science and Medical EngineeringBeihang University 100191 Beijing China

Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the *** our previous studies,it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end *** order to better understand the beneficial effect of the swirling flow,we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow *** numerical models were created based on our previous experimental *** simulation results revealed that when compared with the normal flow,the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion *** present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts,or in end-to-end anastomoses as observed in our previous experimental study,was possibly through a mechanism of platelet transport,in which the swirling flow reduced the near-wall concentration of platelets.

关键词： Platelet near-wall concentration · Swirling flow · Small-caliber arterial grafts · End-to-end anastomosis

Coupled Matrix Factorization for Question Similarity

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Chinese Journal of Electronics 2016年第4期25卷 665-671页

作者： WEI Chuyuan LI fangfang zhan Qiang fan Xiongzhong School of Computer Science and Technology Beijing Institute of Technology Department of Computer Beijing University of Civil Engineering and Architecture Advanced Analytics Institute University of TechnologySydneyAustralia

Community question answering(CQA)has provided an increasingly popular service where users ask and answer questions and access historical questionanswer *** a fundamental task in CQA,question similarity measure is to compute the similarity between the queried question and the historical questions which have been solved by other *** mine and use the most important semantic features as the semantic representation of questions,and try to incorporate the couplings of semantic features into vector space *** propose Coupled question similarity(CQS) model,and compute the similarity in matrix factorization *** conducted on real CQA data sets demonstrate that with the incorporation of such couplings,the performance of sentence similarity is improved compared to a variety of baseline methods significantly.

关键词： Sentence similarity Community question answering(CQA) Matrix factorization(MF) Coupled question similarity(CQS)

Systematic Synthesis of Compressive VDTA-Based T-T Filter with Orthogonal Control of f_o and Q

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Journal of Electronic Science and Technology 2020年第3期18卷 276-286页

作者： Yong-An Li Yan-Hua Xi zhan-Ting fan School of Physics and Electronic Engineering Xianyang Normal UniversityXianyang 712000 School of Information Engineering Shaanxi Institute of International Trade&CommerceXi’an 712046

Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic frequency(f_0) and figure of merit (Q),two different categories of the voltage-mode and transconductance-mode T-T filters are synthesized by the means of the nodal admittance matrix (NAM) expansion *** category A filter that employs two compressive VDTAs and two grounded capacitors includes four structures,and the category B filter that uses two compressive VDTAs,two grounded capacitors,and one grounded resistor,also includes four *** circuits are suitable for integrated circuit manufacture,and their parameters f_0 and Q can be orthogonally adjusted with varying the bias currents of *** the paper and pencil test is completed,the computer analyses,including alternating current (AC),parameter sweep,Monte Carlo (MC),and noise analyses,are performed to support the synthesis approach.

关键词： Compressive voltage differencing transconductance amplifier(compressive VDTA) nodal admittance matrix(NAM)expansion method systematic synthesis tow-Thomas(T-T)filter

The interactions between bloodstream and vascular structure on aortic dissecting aneurysmal model: A numerical study

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Acta Mechanica Sinica 2013年第3期29卷 462-468页

作者： Zeng-Sheng Chen zhan-Ming fan Xi-Wen zhang Department of Engineering Mechanics School of AerospaceTsinghua University Institute of Heart Pulmonary & Vascular Diseases Capital University of Medical Science Affiliated Beijing Anzhen Hospital

Stent-graft implantation is an important means of clinical treatment for aortic dissecting aneurysm （ADA）. However, researches on fluid dynamics effects of stent were rare. Computer simulation was used to investigate the interactions between bloodstream and vascular structure in a stented ADA, which endures the periodic pulse velocity and pressure. We obtained and analyzed the flow velocity distribution, the wall displacement and wall stress in the ADA. By comparing the different results between a non-stented and a stented ADA, we found that the insertion of a vascular graft can make the location of maximum stress and displacement move from the aneurysm lumen wall to the artery wall, accompanied with a greatly decrease in value. These results imply that the placement of a stent-graft of any kind to oc-clude ADA will result in a decreased chance of rupture.

关键词： Aortic dissecting aneurysm (ADA) · Stent-graft · Fluid-structure interaction (FIS)

Interfacial Bonding Mechanism and Mechanical Performance of Continuous Fiber Reinforced Composites in Additive Manufacturing

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Chinese Journal of Mechanical Engineering 2021年第1期34卷 131-141页

作者： Congze fan Zhongde Shan Guisheng Zou Li zhan Dongdong Yan State Key Laboratory of Advanced Forming Technology and Equipment Beijing 100044China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Nanjing University of Aeronautics and Astron autics Nanjing 210016China China Academy of Mach inery Science&Technology Group Co. Ltd.Beijing 100044China

The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex ***,many void defects exist between layers in the printing process of additive manufacturing;consequently,the bonding performance between layers is *** bonding neck is considered a key parameter for representing the quality of interfacial *** this study,the formation mechanism of the bonding neck was comprehensively ***,the influence of the nozzle and basement temperatures on the printing performance and bonding neck size was ***,CT scanning was used to realize the quantitative characterization of bonding neck parameters,and the reason behind the deviation of actual measurements from theoretical calculations was *** the nozzle temperature increased from 180 to 220℃,CT measurement showed that the bonding neck diameter increased from 0.29 to 0.34 mm,and the cross-sectional porosity reduced from 5.48%to 3.22%.Finally,the fracture mechanism was studied,and the influence of the interfacial bonding quality on the destruction process of the materials was *** conclusion,this study can assist in optimizing the process parameters,which improves the precision of the printing parts and performance between the layers.

关键词： 3D printing Thermoplastic resin Continuous fiber Additive manufacturing

Numerical study of thermal characteristics of double skin facade system with middle shade

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Frontiers in Energy 2021年第1期15卷 222-234页

作者： Shaoning LIU Xiangfei KONG Hua YANG Minchao fan Xin zhan School of Energy and Environmental Engineering Hebei University of TechnologyTianjin 300401China

Architectural shade is an effective method for improving building energy efficiency.A new shade combined with the double skin façade(DSF)system,called middle shade(MS),was introduced and developed for *** this paper,a 3D dynamic simulation was conducted to analyze the influence of MS combined with DSF on the indoor thermal *** research on MS for DSF involves the temperature,the ventilation rate,the velocity distribution of the air flow duct,and the indoor *** results show that the angle and position of the shade in the three seasons are different,and different conditions effectively enhance the indoor thermal *** summer,the appearance of MS in DSF makes the indoor temperature significantly *** indoor temperature is obviously lower than that of the air flow duct,and the temperature of the air flow duct is less affected by *** influence of the position of blinds on indoor temperature and ventilation rate is greater than the influence of the angle of *** to the climate characteristics of winter and transition season,in winter,early spring,and late autumn,the indoor temperature decreases with the increase of the position of blinds at daytime,but the opposite is true at *** results found in this paper can provide reference for the design and use of MS combined with DSF in hot summer and cold winter zone.

关键词： middle shade position thermal characteristics double skin facade

Effect of blank quenching on shear spinning forming precision of 2219 aluminum alloy complex thin-walled components

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Chinese Journal of Aeronautics 2023年第4期36卷 538-555页

作者： Zhixin LI Mei zhan Xiaoguang fan Yunda DONG Luopeng XU School of Science Civil Aviation Flight University of ChinaGuanghan 618307China State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of High-Performance Precision Forming

The quenching-spinning(Q-S)process,i.e.,shear spinning after blank quenching,has been increasingly utilized to form 2219 aluminum alloy complex thin-walled ***,the changes in material property,shape and stress of the blanks after quenching will affect the spin-ning forming *** this study,the rules and mechanisms of these effects are investigated based on a combined finite element(FE)model including blank quenching and component spinning *** results indicate that the increase of material strength and the existence of distortion of the quenched blank lead to a notable increase in the non-uniformity of the circumferential compres-sive stress in the spinning area and the increase of the flange swing height during *** changes result in an increase in the wall thickness and component-mandrel gap of the *** quenching residual stress has little effect on wall thickness and roundness but can noticeably reduce the component-mandrel *** is because that the existence of quenching residual stress of the blank can lead to the decrease of the maximum circumferential compressive stress of the workpiece in spinning and an obvious drop in the maximum compressive stress after reaching the stress *** distortion is the main factor affecting the ***,the opti-mized installation way of the blank for spinning is obtained.

关键词： 2219 aluminum alloy Complex thin-walled com-ponents Finite element analysis Quenching distortion Residual stress Shear spinning

An optimized texture-by-numbers synthesis method and its visual applications

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Science China(Information Sciences) 2013年第5期56卷 50-63页

作者： fan Jing SHI XiaoYing ZHOU zhan TANG Ying School of Computer Science and Technology Zhejiang University of Technology Key Laboratory of Visual Media Intelligent Processing Technology of Zhejiang Province School of Information Engineering Zhejiang University of Technology

The framework of texture-by-numbers(TBN) synthesizes images of global-varying patterns with intuitive user *** TBN synthesis methods have difficulties in achieving high-quality synthesis results and efficiency *** paper proposes a fast TBN synthesis method based on texture optimization,which uses global optimization to solve the controllable non-homogeneous texture synthesis *** algorithm produces high quality synthesis results by combining texture optimization into TBN framework with two *** initialization process is adopted to generate the initial output of the global optimization algorithm,which speeds up the algorithm’s convergence rate and enhances synthesis *** distance metrics to measure image similarities are specifically designed for different images to better match human visual perception for structural patterns and a user study is conducted to verify the effectiveness of the *** further improve the synthesis speed,the algorithm is entirely implemented on GPU based on CUDA *** optimized TBN method is applied to various visual applications including not only traditional TBN applications,but also image in-painting and texture-based flow *** experimental results show that our method synthesizes images of higher or comparable qualities with higher efficiency than other state-of-art synthesis methods.

关键词： texture-by-number texture optimization feature synthesis CUDA

Robust optimization of the billet for isothermal local loading transitional region of a Ti-alloy rib-web component based on dual-response surface method

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Frontiers of Mechanical Engineering 2018年第3期13卷 376-384页

作者： Ke WEI Xiaoguang fan Mei zhan Miao MENG State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710071 China

Billet optimization can greatly improve the forming quality of the transitional region in the isothermal local loading forming （ILLF） of large-scale Ti-alloy ribweb components. However, the final quality of the transitional region may be deteriorated by uncontrollable factors, such as the manufacturing tolerance of the preforming billet, fluctuation of the stroke length, and friction factor. Thus, a dual-response surface method （RSM）-based robust optimization of the billet was proposed to address the uncontrollable factors in transi- tional region of the ILLF. Given that the die underfilling and folding defect are two key factors that influence the forming quality of the transitional region, minimizing the mean and standard deviation of the die underfilling rate and avoiding folding defect were defined as the objective function and constraint condition in robust optimization. Then, the cross array design was constructed, a dual-RSM model was established for the mean and standard deviation of the die underfilling rate by considering the size parameters of the billet and uncontrollable factors. Subsequently, an optimum solution was derived to achieve the robust optimization of the billet. A case study on robust optimization was conducted. Good results were attained for improving the die filling and avoiding folding defect, suggesting that the robust optimization of the billet in the transitional region of the ILLF was efficient and reliable.

关键词： isothermal local loading forming rib-web component transitional region robust optimization dual response surface method