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A MIXED FINITE ELEMENT METHOD FOR THE CONTACT PROBLEM IN ELASTICITY

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Journal of Computational Mathematics 2005年第4期23卷 441-448页

作者： Dong-ying Hua Lie-heng wang ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China Graduate School of the Chinese Academy of Science Beijing 100080 China LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

Based on the analysis of [7] and [10], we present the mixed finite element approximation of the variational inequality resulting from the contact problem in elasticity. The convergence rate of the stress and displacement field are both improved from O（h3/4） to quasi-optimal O（h│logh│^1/4）. If stronger but reasonable regularity is available, the convergence rate can be optimal O（h）.

关键词： Contact problem Mixed finite element method

Nitrification performance evaluation of activated sludge under high potassium ion stress during high-ammonia nitrogen organic wastewater treatment

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Journal of Environmental Sciences 2022年第1期34卷 84-92页

作者： Xiaomei Jiang heng wang PeikeWu Hong wang Liangwei Deng Wenguo wang Key Laboratory of Development and Application of Rural Renewable Energy Biogas Institute of Ministry of Agriculture and Rural AffairsChengdu 610041China Sichuan Academy of Environmental Policy and Planning Chengdu 610041China Institute of Urban Agriculture Chinese Academy of Agricultural SciencesChengdu 610213China

The recycling reverse osmosis(RO)membrane concentrate of some high-ammonia nitrogen(NH_(4)^(+)-N)organic wastewater to the biological unit could cause potassium ion(K^(+))accumulation,thereby affecting the removal of NH_(4)^(+)-N by activated ***,the effects of high K^(+) stress on activated sludge nitrification performance was *** results showed that the high K^(+) stress promoted the floc sludge to produce more extracellular polymers(EPS),which accelerated the sludge sedimentation and enriched the biomass in sequential batch reactors(SBRs).The ammonia oxidation process and nitrite(NO_(2)^(-)-N)oxidation process were further analyzed in the nitrification *** K^(+) stress enriched ammonia oxidizing bacteria(AOB),which ensured the efficient ammonia oxidation process in SBRs,and ensured the removal rate of NH_(4)^(+)-N was maintained above 93%.However,high K^(+) stress(15g/L KCl)inhibited the activity of NO_(2)^(-)-N oxidizing bacteria(NOB)and reduced the abundance of NOB,thus leading to the accumulation of NO_(2)^(-)-N,and finally worsened the nitrification performance of activated *** short,the performance of activated sludge will not be inhibited when the K^(+) in the wastewater does not exceed 5.23 g/*** results could provide a reference for the optimization of the biological performance in treating high-NH_(4)^(+)-N organic wastewater with activated sludge coupled RO membrane treatment process.

关键词： Potassium ion(K^(+)) Activated sludge Nitrification High-ammonia nitrogen organic wastewater Microbial community

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中华美学史的性质及内在逻辑论

河北学刊 2025年第1期45卷 55-66页

作者：陈望衡武汉大学哲学学院

对于中华美学史的性质及内在逻辑,可以从五个方面展开论述:第一,中华美学的民族性。中华美学是中华民族的美学,中华民族文化以汉文化为灵魂,却绝不只是汉族文化,它熔铸了生活在中国大地上的诸多民族的文化精神,突出体现了中华民族共同... 详细信息

对于中华美学史的性质及内在逻辑,可以从五个方面展开论述:第一,中华美学的民族性。中华美学是中华民族的美学,中华民族文化以汉文化为灵魂,却绝不只是汉族文化,它熔铸了生活在中国大地上的诸多民族的文化精神,突出体现了中华民族共同的理念、精神、传统。第二,中华美学的国家性。中华美学的国家性奠基于周朝,周朝的礼乐文化既是政治文化,又是审美文化。中华文化中的主要学派儒、道、墨等的美学思想均见出鲜明的国家性。第三,中华美学的文化骨架。其根植于中华文化的三大流派:儒、道、释。儒家美学重社会,道家美学重自然,释家美学重心性。三者相对而又互补,共同构成中华美学的文化骨架。第四,中华美学的诗性品位。《诗经》《楚辞》和唐诗的巨大影响构建了中华美学的诗性品位。第五,中华美学的基本精神。其体现在对审美本体论的认识上,道家的美在自然与儒家的美在文明的统一,构成了中华美学的基本精神。

关键词：中华美学民族性国家性文化骨架诗性品位基本精神

Observer-Based Path Tracking Controller Design for Autonomous Ground Vehicles With Input Saturation

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IEEE/CAA Journal of Automatica Sinica 2023年第3期10卷 749-761页

作者： heng wang Tengfei Zhang Xiaoyu Zhang Qing Li School of Automation and Electrical Engineering and also with the Key Laboratory of Knowledge Automation for Industrial Processes of Ministry of EducationUniversity of Science and Technology BeijingBeijing 100083China School of Automation and Electrical Engineering and also with the Key Laboratory of Knowledge Automation for Industrial Processes of Ministry of EducationUniversity of Science and Technology BeijingBeijing 100083

This paper investigates the problem of path tracking control for autonomous ground vehicles(AGVs),where the input saturation,system nonlinearities and uncertainties are ***,the nonlinear path tracking system is formulated as a linear parameter varying(LPV)model where the variation of vehicle velocity is taken into ***,considering the noise effects on the measurement of lateral offset and heading angle,an observer-based control strategy is proposed,and by analyzing the frequency domain characteristics of the derivative of desired heading angle,a finite frequency H_∞index is proposed to attenuate the effects of the derivative of desired heading angle on path tracking ***,sufficient conditions are derived to guarantee robust H_∞performance of the path tracking system,and the calculation of observer and controller gains is converted into solving a convex optimization ***,simulation examples verify the advantages of the control method proposed in this paper.

关键词： Autonomous ground vehicles(AGVs) H_∞index input saturation observer-based controller path tracking control

Enhanced mechanical properties of a carbon and nitrogen co-doped interstitial high-entropy alloy via tuning ultrafine-grained microstructures

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Journal of Materials Science & Technology 2023年第13期144卷 128-137页

作者： Wei Jiang heng wang Zhiming Li Yonghao Zhao Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing210094PR.China School of Materials Science and Engineering Central South UniversityChangsha410083PR.China

C-N co-doped interstitial high entropy alloy(iHEA)was reported to have high strength and ***,iHEA with fully recrystallized ultrafine grains(UFGs)and underlying thermally activated pro-cesses associated with dislocation slip,twinning,and solute drag have not been reported *** this work,a C-N co-doped iHEA with nominal composition Fe_(48.5)Mn_(30)Co_(10)Cr_(10)C_(0.5)N_(1.0)(at.%)was prepared,and the microstructures were tuned by cold-rolling and annealing treatments to improve mechanical *** cold-rolling with a strain of 1.74,the main microstructures in the iHEA are composed of nano-grains,nano-twins,HCP laminates,and high density of dislocations,leading to ultrahigh hardness of 466.7 HV and tensile strength of 1730 MPa at the expense of ductility(2.44%).Both the nanostructures and the high hardness of the iHEA can be maintained up to an annealing temperature of 600℃(462.5 HV).After annealing at 650℃ for 1 h,the UFG microstructures are obtained in the iHEA,containing re-crystallized grains with an average grain size of 0.91μm and nanoprecipitates with an average diameter of 90.8 *** combined strengthening and hardening effects of UFGs,nanoprecipitates,twinning,and solutes contribute to high strain hardening(n=0.81),gigapascal yield strength(984 MPa),and good duc-tility(20%).The C-N co-doping leads to a strong drag effect on dislocation slip,resulting in a nano-scale mean free path of dislocation slip λ(1.44 nm)and much small apparent activation volume V^(∗)(15.8 b^(3))of the UFG iHEA.

关键词： Ultrafine-grained high-entropy alloys Interstitial atoms Thermomechanical processing Microstructures Mechanical properties

Approximate Poisson disk sampling on mesh

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Science China(Information Sciences) 2013年第9期56卷 194-205页

作者： GENG Bo ZHANG HuiJuan wang heng wang GuoPing Graphics and Interactive Technology Lab of Dept. of Computer Science Peking University The Key Lab of Machine perception and intelligent MOE

Poisson disk sampling has been widely used in many applications such as remeshing, procedural texturing, object distribution, illumination, etc. While 2D Poisson disk sampling is intensively studied in recent years, direct Poisson disk sampling on 2-manifold surface is rarely covered. In this paper, we present a novel framework which generates approximate Poisson disk distribution directly on mesh, a discrete representation of 2-manifold surfaces. Our framework is easy to implement and provides extra flexibility to specified sampling issues like feature-preserving sampling and adaptive sampling. We integrate the tensor voting method into feature detection and adaptive sample radius calculation. Remeshing as a special downstream application is also addressed. According to our experiment results, our framework is efficient, robust, and widely applicable.

关键词： Poisson disk sampling feature preserving sampling adaptive sampling remeshing tensor voting

Influence of CaxSr1-x(0≤x≤1)Substitution for Zn on Microwave Dielectric Properties of Li2ZnTi3O8 Ceramic as Temperature Stable Materials

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Journal of Wuhan University of Technology(Materials Science) 2020年第4期35卷 686-690页

作者： TIAN Shi LIAO Zelin wang heng wang Weimin School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan Institute of TechnologyWuhan 430205China Stat Key Laboratory of Advanced Technology for Materials Synthesisand Processing Wuhan University of TechnologyWuhan 430070China

A temperature stable Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1)ceramics were fabricated using a conventional solid-state route sintered at 1100℃for 4 *** XRD results indicate that the main phase Li2ZnTi3O8 and secondary phase including SrxCa1-xTiO3(0≤x≤1)solid solution and TiO2 co-exist in composite and form a stable composite system when the(CaxSr1-x)(0≤x≤1)substitutes for Zn of Li2ZnTi3O8 *** x is increased from 0 to 1,the relative permittivity(εr)increases from 26.65 to 27.12,and the quality factor(Q×f)increases from 63300 to 66600 *** the increased of x,the temperature coefficient of resonant frequency(τf)increases from 0.27 to 8.23 ppm/℃,and then decreases to 3.51 ppm/℃.On the whole,the Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1)ceramics show excellent comprehensive properties of middleεr=25-27,higher Q×f≥60000 GHz andτf≤±8.5 ppm/℃.

关键词： Li2Zn0.95(SrxCa1-x)0.05Ti3O8(0≤x≤1) microwave dielectric properties temperature stable materials substitution

Gasless laparoscopy for benign gynecological diseases using an abdominal wall-lifting system

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第11期10卷 805-812页

作者： Yue wang heng CUI Yan ZHAO Zhi-qi wang Department of Obstetrics and Gynecology Peking University People's Hospital Beijing 100044 China

Objectives: The use of gasless laparoscopy with an abdominal wall-lifting device for benign gynecological diseases was compared to conventional laparoscopy with CO2 pneumoperitoneum. Methods: From February 2007 to July 2007,76 women with uterine and/or adnexal benign diseases and candidates for laparoscopic surgery were recruited in this study. Thirty-two women underwent gasless laparoscopic surgery and 44 women underwent pneumoperitoneum laparoscopic surgery. Results: Diverse pathologies,including adnexal cyst,uterine myoma and ectopic pregnancy,were treated successfully with gasless laparoscopic surgery. Compared with the patients in the pneumoperitoneum group,the similar hospital stay (P=0.353) and intraoperative blood loss (P=0.157) were observed. However,the mean operative time in the gasless group was significantly longer than that in the pneumoperitoneum group (P=0.003). No severe intraoperative or postoperative complications were found in either group,except for one case of laparotomic conversion in the pneumoperitoneum group due to dense pelvic adhesions. The total hospital charges were significantly less in the gasless group than in the pneumoperitoneum group (P=0.001). In 38 cases of ovarian cyst resection,the mean operative time in the gasless group remained longer than that in the pneumoperitoneum group (P=0.017). The total hospital charges were also significantly less in the gasless group than in the pneumoperitoneum group (P<0.001). Conclusion: Our preliminary results demonstrated that the laparoscopic procedure using the gasless technique was a safe,effective method to treat benign gynecological diseases. Moreover,it was easy to master. As a minimally invasive treatment,gasless laparoscopic surgery provides a good choice to patients in the undeveloped regions in China without increasing the patients’ and the government’s burden significantly.

关键词： Gasless laparoscopy Pneumoperitoneum laparoscopy Ovarian cyst resection

On Dynamic Channel Emulation in Sector MPAC for Over-the-Air Testing of Beamformed Massive MIMO Devices

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China Communications 2023年第4期20卷 41-56页

作者： Xiaochen Chen heng wang Weimin wang Zheng Liu Yuanan Liu China Academy of Information and Communications Technology Beijing 100191China Beijing Key Laboratory of Work Safety Intelligent Monitoring Department of Electronic EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China

In this article,novel emulation strategies for the sectored multiple probe anechoic chamber(SMPAC)are proposed to enable the reliable evaluation of the massive multiple-input multiple-output(MIMO)device operating at beamforming mode,which requires a realistic non-stationary channel *** the dynamic propagation emulation,an efficient closed-form probe weighting strategy minimizing the power angular spectrum(PAS)emulation errors is derived,substantially reducing the associated computational *** the other hand,a novel probe selection algorithm is proposed to reproduce a more accurate fading *** standard channel models and setup configurations are comprehensively simulated to validate the capacity of the proposed *** simulation results show that more competent active probes are selected with the proposed method compared to the conventional ***,the derived closedform probe weighting strategy offers identical accuracy to that obtained with complicated numerical ***,a realistic dynamic channel measured in an indoor environment is reconstructed with the developed methodologies,and 95.6%PAS similarity can be achieved with 6 active *** satisfactory results demonstrate that the proposed algorithms are suitable for arbitrary channel emulation.

关键词： beamforming channel emulation massive MIMO device multiple probe anechoic chamber(MPAC) over-the-air testing