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Global Weak Solutions to a Fluid-particle System of an Incompressible Non-Newtonian Fluid and the Vlasov Equation

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Acta Mathematicae Applicatae Sinica 2024年第4期40卷 954-978页

作者： pei-yu ZHANG Li FANG Zhen-hua GUO Department of Mathematics Northwest UniversityXi’an 710127China School of Mathematics and Information Science&Center for Applied Mathematics of Guangxi Guangxi UniversityNanning 530004China

The purpose of this work is to investigate the existence and uniqueness of weak solutions to the initial-boundary value problem for a coupled system of an incompressible non-Newtonian fluid and the Vlasov *** coupling arises from the acceleration in the Vlasov equation and the drag force in the incompressible viscous non-Newtonian fluid with the stress tensor of a power-law structure for p≥11/*** main idea of the existence analysis is to reformulate the coupled system by means of a so-called truncation *** advantage of the new formulation is to control the external force term G=-∫Rd(u-v)fdc(d=2,3).The global existence of weak solutions to the reformulated system is shown by using the Faedo-Galerkin method and weak compactness *** further prove the uniqueness of weak solutions to the considered system.

关键词： incompressible non-Newtonian fluid Vlasov equation global weak solutions

Effect of a viscoelastic target on the impact response of a flat-nosed projectile

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Acta Mechanica Sinica 2018年第1期34卷 162-174页

作者： hu Liu Jialing Yang hua Liu Institute of Solid Mechanics Beihang University

Taylor impact is a widely used strategy in which a flat-nosed projectile is fired onto a rigid anvil directly to determine the dynamic strength of rod specimens. Nowadays, the rigid anvil is often replaced by an output target bar to ensure the accuracy of measurement via recording strain signals in the output bar. For testing the dynamic strength of low-density materials, a low-impedance target bar, which exhibits viscoelastic characteristics is often employed. In this paper, an extended Taylor model is proposed to improve the idealization of treating the target bar as perfectly rigid material in the classic Taylor model, and the viscoelastic effect of the target bar is incorporated. The viscoelastic target bar is depicted by two elastic springs and one dashpot. Based on the plastic shock wave theory in the flat-nosed projectile associated with the viscoelastic wave analysis in the target bar, the viscoelastic effect of the target bar on the impact response of the flat-nosed projectile is investigated. The finite element simulation is also carried out to verify the theoretical model,and good agreement is found. The present theoretical model is also called the Taylor-cylinder Hopkinson impact, which provides a more accurate way to identify the dynamic material parameters. The dynamic responses of the present model are further compared with previous elastic and rigid target bar models. It is found that the viscoelastic effect of the target bar should be taken into consideration in the Taylor-cylinder Hopkinson impact test for low-impedance materials.

关键词： Dynamic response Taylor impact Viscoelastic target Low-density material

RATE OF CONVERGENCE OF SCHWARZ ALTERNATING METHOD FOR TIME-DEPENDENT CONVECTION-DIFFUSION PROBLEM

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Journal of Computational Mathematics 2002年第5期20卷 479-490页

作者： Jian-wei hu Cai-hua Wang School of Mathematical Sciences Nankai University300071 Tianjin China Laboratory of Computational Physics IAPCM100088 Beijing China Department of Mathematics Tianjin Normal University300073 Tianjin China

Presents a study that examined the application of an overlapping domain decomposition method to the solution of time-dependent convection-diffusion problems. Background on the Schwartz alternating procedure; Applicati... 详细信息

关键词： rate of convergence Schwarz alternating method convection-diffusion problem

Trustworthy Service Selection Integrating Cloud Model and Possibility Degree Ranking of Interval Numbers

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Chinese Journal of Electronics 2017年第6期26卷 1177-1183页

作者： MA hua hu Zhigang CAI Meiling School of Software Central South University Computer Education Department Hunan Normal University

It has been challenging to select suitable services from abundant candidates in cloud *** to the characteristics of batch computing mode and stream computing mode, a novel trustworthy service selection approach is proposed integrating cloud model and interval numbers theory. To facilitate potential users to understand the quality of service, the trustworthiness of service is described with interval number using reverse cloud generator, and the services with poor performance are filtered out by employing deviation degree or proximity degree. Two formulas of possibility degree of interval numbers are designed to compare the trustworthiness values between cloud services by utilizing probability zone analysis and geometrical analysis respectively, and the ranking method for possibility degree of interval numbers is exploited to select the most trustworthy service. The experiments show that this approach is effective to improve the accuracy of service selection and select trustworthy service for potential users in cloud paradigm.

关键词： Service selection Trustworthiness Cloud model Possibility degree ranking Interval numbers

Dairy Consumption and Associations with Nutritional Status of Chinese Children and Adolescents

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Biomedical and Environmental Sciences 2019年第6期32卷 393-405页

作者： XU pei pei YANG Ti Ti XU Juan LI Li CAO Wei GAN Qian hu Xiao Qi PAN hui ZHAO Wen hua ZHANG Qian National Institute for Nutrition and Health Chinese Center for Disease Control and Prevention

Objective This study aimed to describe frequency and quantity of total dairy consumption of Chinese children and adolescents and explore the associations between dairy consumption and nutrition status, including stunting, wasting, overweight, and obesity. Methods Participants included 28,250 children and adolescents aged 6-17 years old. A food frequency questionnaire(FFQ) including 100 kinds of food was used to collect information about frequency and quantity of dairy consumption. Determination of stunting was with a height cutoff value for age and gender, and determination for wasting, overweight, and obesity was with BMI for age and gender. Results Of the total sample, 36.1% of children aged 6-17 reported consuming dairy food more than once per day(≥ 1/day). The average total dairy intake of all the participants was 126.7 g/day. For boys, dairy consumption had an inverse correlation with stunting and wasting after controlling for confounders. For girls, dairy consumption was negatively associated with stunting and obesity after controlling for confounders as above. Conclusion Dairy consumption in Chinese children and adolescents was relatively lower than that in developed countries, and was negatively associated with stunting and wasting for boys and with stunting and obesity for girls.

关键词： Dairy consumption Children and adolescents Nutrition status Association China

Modification of Carbon Nanotube Powder Microelectrode and Nitrite Reduction

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Chinese Chemical Letters 2002年第1期13卷 79-82页

作者： pei Fang LIU Jun Fu hu Department of Chemistry Wuhan UniversityWuhan 430072

The properties of the carbon nanotube powder microelectrodes (denoted CNTPME) are remarkably altered by anodic pretreatment and preadsorption of mediators. It seems that anodic pretreatment leads the long and tangled carbon nanotubes to be partially cut shorter, resulting in more openings as shown by TEM. Besides, the anodic pretreatment may adjust the hydrophobicity of nanotubes to match with that of Os(bpy)32+. As a result, the real surface area and the ability of adsorbing mediator Os(bpy)32+ of the nanotubes are markedly increased so as to effectively catalyze NO2- reduction in acidic solution.

关键词： Carbon nanotube powder microelectrode nitrite reduction modified electrode.

Will the symbiotic pacemaker, a self-powered cardiac implanted electronic device, be the next evolution in pacemaker technology?

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Science Bulletin 2019年第13期64卷 877-878页

作者： Yiran hu Wei hua The Cardiac Arrhythmia Center State Key Laboratory of Cardiovascular Disease National Clinical Research Center of Cardiovascular Diseases Fuwai Hospital National Center for Cardiovascular Diseases Chinese Academy of Medical Sciences and Peking Union Medical College

The first permanent implanted pacemaker was successfully used in clinical practice in 1958. In the past 60 years, the development of pacemakers has been witnessed in clinical application [1]. Early pacemakers were large and cumbersome, and had a short battery life, providing only a single-chamber asynchronous pacing (VOO) pacing mode. In 1967, on-demand pacemakers with synchronous pacing (WI) mode just came out. The emergence of the first dual chamber pacemaker in 1977 symbolized the entry into the physiologic pacing era. In 1982, pacemakers began to provide rate adaptive functions. In this age of accelerating development in scientific technologies and clinical researches, pacemakers have evolved into implantable cardioverter-defibrillators for the treatment of sudden cardiac death and cardiac resynchronization therapy for chronic heart failure, instead of simply being an electronic device that treats bradycardia by pulsing the heart (Fig. 1)[2,3].

关键词： symbiotic pacemaker self-powered cardiac implanted electronic device

Assessing the range of blasting-induced cracks in the surrounding rock of deeply buried tunnels based on the unified strength theory

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Journal of Central South University 2024年第7期31卷 2341-2364页

作者： LI Liang CHEN Jia-jun ZHAO Lian-heng HE Ke-pei hu Shi-hong LI hua-long School of Civil Engineering Central South UniversityChangsha 410075China Key Laboratory of Heavy-haul Railway Engineering Structure Ministry of EducationCentral South UniversityChangsha 410075China hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure Central South UniversityChangsha 410075China

Blasting-induced cracks in the rock surrounding deeply buried tunnels can result in water gushing and rock mass collapse,posing significant safety ***,previous theoretical studies on the range of blasting-induced cracks often ignore the impact of the in-situ stress,especially that of the intermediate principal *** particle displacement−crack radius relationship was established in this paper by utilizing the blasthole cavity expansion equation,and theoretical analytical formulas of the stress−displacement relationship and the crack radius were derived with unified strength theory to accurately assess the range of cracks in deep surrounding rock under a blasting *** analysis showed that the crushing zone size was positively correlated with in-situ stress,intermediate principal stress,and detonation pressure,whereas negatively correlated with Poisson ratio and decoupling *** dilatancy angle-crushing zone size relationship exhibited nonmonotonic *** relationships in the crushing zone and the fracture zone exhibited opposite trends under the influence of only in-situ stress or intermediate principal *** the in-situ stress increased from 0 to 70 MPa,the rate of change in the crack range and the attenuation rate of the peak vibration velocity gradually slowed.

关键词： deep drilling and blasting cracks in surrounding rock unified strength theory intermediate principle stress in-situ stress cavity expansion dilatancy characteristics

First principles study of Fenton reaction catalyzed by FeOCl:reaction mechanism and location of active site

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Rare Metals 2019年第8期38卷 783-792页

作者： Xuan-Xuan Ji Hai-Feng Wang pei-Jun hu Key Laboratory for Advanced Materials Research Institute of Industrial Catalysis and Centre for Computational Chemistry School of Chemical and Molecular Engineering East China University of Science and Technology Shanghai 200237 China School of Chemistry and Chemical Engineering The Queen’s University of Belfast Belfast BT9 5AZ UK

Fe-based solid catalysts in promoting Fenton reaction to generate ·OH radical has drawn much attention,and interestingly,FeOCl was reported to have superior activity compared with the traditional Fe2 O3 ***,the mechanism of Fenton reaction on FeOCl and the origin of high activity remain ***,by virtue of DFT+ U calculations,the H2 O2 decomposition and conversion mechanism on FeOCl(100)surface were systematically *** is found that on clean FeOCl(100)surface,the exposed[Fe^3+-Fe^3+]sites can hardly break O-O bond of H2 O2 into OH groups,but instead H2 O2 tends to dehydrogenate by the surface lattice O,resulting in a series of side reactions and final conversion into O2,while the left H atoms gradually saturate the surface lattice O and reduce Fe^3+ into Fe^2+.On fully H-covered FeOCl(100),H2O2 can efficiently dissociate at[Fe^2+-Fe^2+]sites into two OH,but OH binds with Fe^2+ so strongly that it cannot desorb as OH radical as easily as that on Fe^3+.Interestingly,FeOCl(100)tends to be partially protonated in the real acid solution,which,along with H2 O2 dehydrogenation,results in the formation of active unit [Fe^2+-Fe^3+].On[Fe^2+-Fe^3+]unit,H2 O2 can easily break its O-O bond and OH at Fe3+ can desorb as OH radical,while the other OH at Fe^2+ couples with the surface H into H2O and finish the catalytic *** comparison,Fe2 O3(012)cannot provide enough [Fe^2+-Fe^3+] active units due to the relative difficulty in H2 O2 dehydrogenation,which accounts for its inferior catalytic efficiency for Fenton reaction.

关键词： Fenton reaction FeOCl Density functional theory H2O2 Active site