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On a Vector Version of a Fundamental Lemma of ***

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Chinese Annals of Mathematics,Series B 2018年第1期39卷 33-46页

作者： Philippe G. CIARLET Maria MALIN Cristinel MARDARE Department of Mathematics City University of Hong Kong 83 Tat Chee Avenue Kowloon Hong Kong. Sorbonne Universites Universite Pierre et Marie Curie Laboratoire Jacques-Louis Lions 4 Place Jussieu 75005 Paris France

Let ? be a bounded and connected open subset of R^N with a Lipschitzcontinuous boundary,the set ? being locally on the same side of ??.A vector version of a fundamental lemma of ***,due to ***,the first author,*** and ***,asserts that any vector field v =(vi) ∈(D′(?))~N,such that all the components 1/2(?_jv_i + ?_iv_j),1 ≤ i,j ≤ N,of its symmetrized gradient matrix field are in the space H^(-1)(?),is in effect in the space(L^2(?))~*** objective of this paper is to show that this vector version of *** lemma is equivalent to a certain number of other properties of interest by *** include in particular a vector version of a well-known inequality due to ***ˇcas,weak versions of the classical Donati and Saint-Venant compatibility conditions for a matrix field to be the symmetrized gradient matrix field of a vector field,or a natural vector version of a fundamental surjectivity property of the divergence operator.

关键词： J.L.Lions lemma Neˇcas inequality Donati compatibility conditions Saint-Venant compatibility conditions

Graphene-encapsulated blackberry-like porous silicon nanospheres prepared by modest magnesiothermic reduction for high-performance lithium-ion battery anode

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Rare Metals 2021年第2期40卷 383-392页

作者： Ben Xiang Wei-Li An Ji-Jiang Fu Shi-Xiong Mei Si-Guang Guo Xu-Ming Zhang Biao Gao Paul K.Chu The State Key Laboratory of Refractories and Metallurgy Institute of Advanced Materials and NanotechnologyWuhan University of Science and TechnologyWuhan430081China BTR New Material Group Co. Ltd.Shenzhen518106China Department of Physics City University of Hong KongTat Chee AvenueKowloon999077Hong KongChina Department of Materials Science and Engineering City University of Hong KongTat Chee AvenueKowloon999077Hong KongChina Department of Biomedical Engineering City University of Hong KongTat Chee AvenueKowloon999077Hong KongChina

Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer ***,fabrication of porous structures tends to be difficult to control and complex,so,the final electrochemical performance can be ***,a modest magnesiothermic reduction(MMR)reaction is demonstrated to produce blackberry-like porous Si nanospheres(PSSs)controllably using magnesium silicide(Mg_(2)Si)as Mg source and SiO_(2)nanospheres as the *** improved MR method provides good control of the kinetics and heat release compared to the traditional MR(TMR)method using Mg powder as the *** PSSs obtained by MMR reaction has higher structural integrity than that fabricated by *** encapsulation with reduced graphene oxide,the Si/C composite exhibits superior cycling stability and rates such as a high reversible capacity of 1034 mAh·g^(-1)at0.5 C(4200 mAh·g^(-1)at 1.0 C)after 1000 cycles,capacity retention of 79.5%,and high rate capacity of 497 mAh·g^(-1)at 2.0 *** strategy offers a new route to fabricate highperformance porous Si anodes and can be extended to other materials such as germanium.

关键词： Porous silicon Graphene Anode Magnesiothermic reduction Lithium-ion battery

Room temperature and humidity decoupling control of common variable air volume air-conditioning system based on bilinear characteristics

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Energy and Built Environment 2023年第3期4卷 354-367页

作者： Yuan Zhang Tian Yan Xinhua Xu Jiajia Gao Gongsheng Huang Department of Building Environment&Energy Engineering Huazhong University of Science&TechnologyWuhan 430074China Department of Building Environment&Energy Engineering Wuhan University of Science&TechnologyWuhanChina Department of Architecture and Civil Engineering City University of Hong KongTat Chee AvenueKowloonHong Kong SARChina

Variable air volume(VAV)air-conditioning(AC)systems are widely employed to achieve a comfortable room thermal and humid environment depending on its better regulation performance and energy *** the single coil VAV AC system,conventional proportional-integral(PI)control algorithm is usually adopted to track the set-points of the room temperature and humidity by regulating the supply air flow rate and the chilled water flow rate,***,the control performance is usually not good due to the high coupling of the heat and mass transfer in the air-handling unit(AHU).A model-based control method is developed to realize the decoupling control of the room temperature and humidity according to the bilinear characteristics of the temperature and humidity *** this control method,a bilinear room temperature controller is used to track the room temperature set-point based on the real-time cooling load,while a room humidity controller is used to track the room humidity set-point depending on the real-time humidity *** control performance was validated in a simulated VAV AC *** test results show that comparing with the conventional PI control,the room temperature and humidity are controlled much more robustly and accurately by using the proposed model-based control method.

关键词： VAV air-conditioning system Room temperature control Room humidity control Bilinear control Model-based cascade control

Utilizing Multilayer Design of Organic-Inorganic Hybrids to Enhance Wearable Strain Sensor in Humid Environment

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Chinese Journal of Polymer Science 2023年第7期41卷 1037-1050页

作者： Chen-Chen Lu Wei-Chen Gao Peng Li Wei Wu Robert K.Y.Li Hui Zhao Guangxi Key Laboratory of Clean Pulp&Papermaking and Pollution Control School of Light Industry and Food EngineeringGuangxi UniversityNanning530004China Guangxi Key Laboratory of Calcium Carbonate Resources Comprehensive Utilization College of Materials and Chemical EngineeringHezhou UniversityHezhou542899China Department of Materials Science and Engineering City University of Hong KongTat Chee AvenueKowloonHong Kong999077China

Flexible strain wearable sensors have attracted considerable attention due to their advantages of low cost, lightweight, high sensitivity and good flexibility. However, the strain sensors are easy to be damaged in an extreme humidity environment or by the wearer’s sweat in the process of use, resulting in detection disorder or even a short circuit. Furthermore, preparation of sensors with stable properties under extreme environments is one of the most important research directions. To fill this gap, a flexible sensor was prepared by using polyurethane and carbon nanotubes, then modified by polydopamine and 1H,1H,2H,2H-perfluorodecane-mercaptan. A typical tunnel model was used to explain the working mechanism of the sensor, the sensitivity of the sensor is also explained and evaluated by the tunneling theory. The results show that the sensor has good sensitivity (the sensor has a stable sensing signal output under a strain range from 2% to 300%) and stability over 8500 cycles. At the same time, the sensor has good superhydrophobicity, the water contact angle reaches 152°, and it is still stable in a humid environment. Moreover, this sensor shows excellent performance in monitoring human joint motion (such as finger, elbow, wrist and knee) and physiological signals (such as speaking and drinking). This work provides an effective design method for the sensor which can be applied in a high humidity environment.

关键词： Wearable strain sensor Polyurethane Carbon nanotubes Superhydrophobicity

Metal-organic framework-derived carbon nanotubes with multi-active Fe-N/Fe sites as a bifunctional electrocatalyst for zinc-air battery

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Journal of Energy Chemistry 2022年第3期31卷 306-313,I0009页

作者： Chao Yang Shanshan Shang Qinfen Gu Jin Shang Xiao-yan Li Centre for Environmental Engineering Research Department of Civil EngineeringThe University of Hong KongPokfulamHong KongChina School of Energy and Environment City University of Hong KongTat Chee AvenueKowloonHong KongChina Australian Synchrotron ANSTO800 Blackburn RdClaytonVictoria 3168Australia Tsinghua-Berkeley Shenzhen Institute Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055GuangdongChina

Sustainable metal-air batteries demand high-efficiency,environmentally-friendly,and non-precious metal-based electrocatalysts with bifunctionality for both the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).In this research,novel functional carbon nanotubes with multi-active sites including well-dispersed single-atom iron throughout the walls and encapsulated ultrafine iron nanoparticles were synthesized as an electrocatalyst(FeNP@Fe-N-C)through one-step pyrolysis of metal-organic ***-resolution synchrotron powder X-ray diffraction and X-ray absorption spectroscopy were applied to characterize the unique structure of the *** comparison to the commercial Pt/C and Ru O_(2)electrodes,the newly prepared FeNP@Fe-N-C presented a superb bifunctional performance with its narrow potential difference(Egap)of 0.73 V,which is ascribed to the metallic Fe nanoparticles that boosts the adsorption and activation of oxygen on the active sites with an enhanced O_(2)adsorption capacity of 7.88 cm^(3)g^(-1)and synergistically functionalizes the iron atoms dispersed on the nanotubes.A rechargeable zinc-air battery based on FeNP@Fe-N-C exhibited a superior open-circuit voltage(1.45 V),power density(106.5 m W cm^(-2)),and stable cycling *** green technique developed in this work for the fabrication of functional nanotubes raises the prospect of making more efficient electrocatalysts for sustainable energy cells.

关键词： Bifunctional electrocatalyst Oxygen reduction reaction Oxygen evolution reaction Single-atom iron Encapsulated iron nanoparticles

A modelling method for large-scale open spaces orientated toward coordinated control of multiple air-terminal units

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Building Simulation 2023年第2期16卷 225-241页

作者： Pei Zhou Songjie Wang Jintao Zhou Syed Asad Hussain Xiaoping Liu Jiajia Gao Gongsheng Huang School of Civil Engineering Hefei University of TechnologyHefeiAnhuiChina Life Cycle Management Laboratory School of EngineeringUniversity of British Columbia(Okanagan Campus)KelownaBritish ColumbiaCanada Department of Building Environment&Energy Engineering Wuhan University of Science&TechnologyWuhanChina Department of Architectural and Civil Engineering City University of Hong KongTat Chee AvenueKowloonHong KongChina

The temperature distribution is always assumed to be homogeneous in a traditional singleinput-single-output(SISO)air conditioning control ***,the airflow inside is more complicated and *** study proposes a zonal temperature control strategy with a thermal coupling effect integrated for air-conditioned large-scale open *** target space was split into several subzones based on the minimum controllable air terminal units in the proposed method,and each zone can be controlled to its own set-point while considering the thermal coupling effect from its adjacent zones.A numerical method resorting to computational fluid dynamics was presented to obtain the heat transfer coefficients(HTCs)under different air supply *** relationship between heat transfer coefficient and zonal temperature difference was ***,currently available zonal models in popular software can be used to simulate the dynamic response of temperatures in large-scale indoor open *** studies showed that the introduction of HTCs across the adjacent zones was capable of enhancing the precision of temperature control of large-scale open *** could satisfy the temperature requirements of different zones,improve thermal comfort and at least 11%of energy saving can be achieved by comparing with the conventional control strategy.

关键词： large-scale open space zonal temperature control CFD thermal coupling heat transfer coefficient TRNSYS

C-176 loaded Ce DNase nanoparticles synergistically inhibit the cGAS-STING pathway for ischemic stroke treatment

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Bioactive Materials 2023年第11期29卷 230-240页

作者： Zhixin Zhu Haipeng Lu Lulu Jin Yong Gao Zhefeng Qian Pan Lu Weijun Tong Pik Kwan Lo Zhengwei Mao Haifei Shi Department of Orthopedics 1st Affiliated Hospital of Zhejiang University School of MedicineQingchun Road 79Hangzhou31000China MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou310027China Department of Chemistry and State Key Laboratory of Marine Pollution City University of Hong KongTat Chee AvenueKowloonHong Kong

The neuroinflammatory responses following ischemic stroke cause irreversible nerve cell *** free-double strand DNA(dsDNA)segments from ischemic tissue debris are engulfed by microglia and sensed by their cyclic GMP-AMP synthase(cGAS),which triggers robust activation of the innate immune stimulator of interferon genes(STING)pathway and initiate the chronic inflammatory *** decomposition of immunogenic dsDNA and inhibition of the innate immune STING are synergistic immunologic targets for ameliorating *** combine the anti-inflammatory strategies of STING inhibition and dsDNA elimination,we constructed a DNase-mimetic artificial enzyme loaded with *** are self-assembled by amphiphilic copolymers(P[CL35-b-(OEGMA20.7-co-NTAMA14.3)]),C-176,and Ce^(4+)which is coordinated with nitrilotriacetic acid(NTA)group to form corresponding catalytic *** work developed a new nano-drug that balances the cGAS-STING axis to enhance the therapeutic impact of stroke by combining the DNase-memetic Ce^(4+)enzyme and STING inhibitor *** conclusion,it is a novel approach to modulating central nervus system(CNS)inflammatory signaling pathways and improving stroke prognosis.

关键词： Ischemic stroke Ce-based nano-nuclease The cGAS-STING signaling pathway Anti-inflammation

Enhanced ion conductivity and electrode–electrolyte interphase stability of porous Si anodes enabled by silicon nitride nanocoating for high-performance Li-ion batteries

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Journal of Energy Chemistry 2022年第6期31卷 616-625,I0017页

作者： Shixiong Mei Siguang Guo Ben Xiang Jiaguo Deng Jijiang Fu Xuming Zhang Yang Zheng Biao Gao Paul K Chu Kaifu Huo The State Key Laboratory of Refractories and Metallurgy and Institute of Advanced Materials and Nanotechnology Wuhan University of Science and TechnologyWuhan 430081HubeiChina Wuhan National Laboratory for Optoelectronics(WNLO) School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074HubeiChina Department of Physics Department of Materials Science&EngineeringDepartment of Biomedical EngineeringCity University of Hong KongTat Chee AvenueKowloonHong KongChina

Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high ***,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate ***,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in *** ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during *** Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of *** fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion ***,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.

关键词： Silicon anode Ion conductivity Si_(3)N_(4) SiN_(x) Lithium-ion battery

Mg-Ni THIN FILM-A POTENTIAL NEGATIVE ELECTRODE FOR NIKEL-METAL HYDRIDE BATTERY

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Acta Metallurgica Sinica(English Letters) 2003年第3期16卷 226-230页

作者： L.Z.Ouyang C.Y.Chung M.Q.Zeng H.Wang M.Zhu College of Mechanical Engineering South China University of TechnologyGuangzhou 510641China Department of Physics and Material Science City University of Hong Kong83 Tat Chee AvenueKowloon Hong KongDepartment of Physics and Material Science City University of Hong Kong83 Tat Chee Avenue Kowloon Hong Kong College of Mechanical EngineeringSouth China University of TechnologyGuangzhou 510641ChinaCollege of Mechanical EngineeringSouth China University of TechnologyGuangzhou 510641ChinaCollege of Mechanical EngineeringSouth China University of TechnologyGuangzhou 510641China

Mg-Ni thin films for nickel-metal hydride (Ni-MH) battery negative electrode were prepared on three different substrates by using magnetron sputtering with compacted Ni and Mg mixture powder. The microstructure of Mg-Ni thin films deposited on the glass and the Ni foil substrate respectively was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the Mg-Ni thin films were in amorphous structure and the composition of the thin film was homogeneous. Electrochemical measurement show the discharge capacity of the thin film negative electrode deposited on the foam Ni substrate was 284.8mAh/g in 6M alkaline electrolyte and the internal resistance was much lower than that of the electrode prepared by the ball-milled powder during the charge-discharge cycle.

关键词： magnetron sputtering Mg-Ni thin film Ni-MH battery