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Chinese Journal of Electronics 2023年第5期32卷 1133-1150页

作者： liu guangdong School of Electrical and Control Engineering Nanjing Polytechnic Institute

In recent years, three similar versions of time-domain inverse scattering(TDIS) algorithms have been proposed for the successful estimation of the dispersive dielectric properties of several single-pole Debye media. For practical applications in common biomedical engineering, an improved TDIS algorithm is explicitly derived to provide a more versatile algorithm for the microwave tomographic imaging of biological tissues. Its three improvements are as follows. The number of poles for Debye models is extended from one to a positive integer W. The second improvement is the extension of unknowns from three to 2W+2 for each discretized cell. The third improvement is the adoption of the first-order Tikhonov regularization scheme. Based on the four classes of 2-dimensional anatomically realistic numerical phantoms with two-pole Debye dispersion from the University of Wisconsin Computational Electromagnetics Laboratory(UWCEM) database, the performance of the developed algorithm for the detection of a 3-mm-diameter tumor implanted in the four types of breast models was investigated for three scenarios. The obtained results preliminarily indicate that the modified technique is feasible and promising for the quantitative reconstruction of sparse breast tissues.

关键词： Inverse problems Phantoms Tomography Media Microwave theory and techniques Numerical models Time-domain analysis

A biorthogonality relationship for three-dimensional couple stress problem

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Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 270-276页

作者： LUO JianHui LI QiuSheng liu guangdong School of Civil Engineering Hunan UniversityChangsha 410082China Department of Building and Construction City University of Hong Kong83 Tat Chee AvenueKowloonHong KongChina

The duality solution for elasticity and the biorthogonality relationship have been well researched. Now the couple stress theory becomes a new research spot but there is few research for the biorthogonality relationship for couple stress theory comparing to classical elasticity. A new state vector is presented for three dimensional couple stress problems of prismatic structures. A new biorthogonality relation- ship of couple stress is discovered. The dual partial differential equations of couple stress problem are derived by the new state vector. By two important identical equations the new biorthogonality rela- tionship is proved based on the method of separation of variables. The symplectic orthogonality rela- tionship to three dimensional couple stress theory may be decomposed into two independently and symmetrically orthogonality relationships. The new biorthogonality relationship includes the symplec- tic orthogonality relationship. The biorthogonality relationship of couple stress may also be degener- ated into the theory of elasticity. The new state vector and biorthogonality relationship provide theo- retic foundation for the research on the schemes of separation of variables and eigenfunction expan- sion of couple stress theory.

关键词： couple stress duality solution biorthogonality relationship Hamiltonian state space

Denitrification characteristics of a marine origin psychrophilic aerobic denitrifying bacterium

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Journal of Environmental Sciences 2011年第11期23卷 1888-1893页

作者： Haiyan Zheng Ying liu guangdong Sun Xiyan Gao Qingling Zhang Zhipei liu State Key Laboratory of Microbial Resources Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China.

A psychrophilic aerobic denitrifying bacterium,strain S1-1,was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture *** S1-1 was preliminarily identified as Psychrobacter *** on the analysis of its 16S rRNA gene sequence,which showed 100% sequence similarity to that of Psychrobacter *** S1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite,and the total nitrogen removal rates could reach to 46.48% and 31.89%,*** results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low leve1 accumulation of nitrite,suggesting that the aerobic denitrification process of strain S1-1 occurred mainly in this *** GC-MS results showed that N 2 O was formed as the major intermediate during the aerobic denitrifying process of strain ***,factors affecting the growth of strain S1-1 and its aerobic denitrifying ability were also *** showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source,C/N ratio15,salinity 10 g/L NaCl,incubation temperature 20°C and initial pH 6.5.

关键词： nitrogen removal aerobic denitrification marine environment low temperature Psychrobacter sp.S1-1

Theoretical Analysis of Annular Elliptic Finned Tube Evaporative Condenser Based on Field Measurement

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Journal of Thermal Science 2020年第5期29卷 1355-1369页

作者： GU Yaxiu WANG Junwei WANG Xinru Ll Mohua PAN Song liu guangdong WANG Wentao GING Zexiang Department of Building Environment and Energy Engineering School of Civil EngineeringChang'an UniversityXi'an 710061China Research Centre for Fluid and Thermal Engineering Department of Architectural and Built EnvironmentUniversity of Nottingham Ningbo ChinaNingbo 315100China College of Architecture and Civil Engineering Beijing University of TechnologyBeijing 100124China

In this article,a new evaporative condenser with an annular elliptic firmed tube heat exchanger that includes a round inner tube and elliptic outer finned tube was designed and *** refrigerant flows between the round inner tube and the elliptic outer tube,and it simultaneously exchanges heat with the cooling water in the inner tube,the spray water,and the cooling air flowing past the outer *** field measurement for the traditional round finned tube evaporative condenser in the Futong Metro Station of Line 14 in Beijing,China,the theoretical heat transfer performance of the annular elliptic finned tube evaporative condenser was analyzed and *** with a round finned tube heat exchanger,the heat exchange capacity of the annular elliptic finned tube increased by 2.34%to 9.28%;the total heat transfer coefficient increased by 47.42%,and the power consumption of the fan in the air-conditioning system with an annular elliptic finned tube heat exchanger decreased by 11.18%to 14.65%.Therefore,the energy-saving performance and the heat transfer performance of the new annular elliptic finned tube heat exchanger were enhanced compared to the round finned tube heat exchanger.

关键词： evaporative condenser finned tube heat exchanger annular elliptic tube heat transfer enhancement air-conditioning system metro station

Engineering the high-entropy phase of Pt-Au-Cu nanowire for electrocatalytic hydrogen evolution

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Nano Research 2023年第8期16卷 10742-10747页

作者： Yanan Yu guangdong liu Shuaihu Jiang Ruya Zhang Huiqiu Deng Eric AStach Shujuan Bao Zhenhua Zeng Yijin Kang Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China School of Physics and Electronics Hunan UniversityChangsha 410082China Department of Materials Science and Engineering University of PennsylvaniaPhiladelphiaPA 19104USA Institute for Clean Energy&Advanced Materials School of Materials and EnergySouthwest UniversityChongqing 400715China Davidson School of Chemical Engineering Purdue UniversityWest LafayetteIN 47907USA

Hydrogen economy,as the most promising alternative energy system,relies on the hydrogen production through sustainable water splitting which in turn relies on the high efficiency *** A1-phase alloy has been predicted to be a promising electrocatalyst for the hydrogen *** such preferred phase of Pt-Au-Cu is not thermodynamically favored,herein,we stabilize PtAuCu alloy by engineering the high-entropy phase in the form of *** functional theory(DFT)calculations indicate that,in comparison with the ordered phase and segregated phases with discrete hydrogen binding energy,the high-entropy phase provides a diverse combination of site composition to continuously tune the hydrogen binding energy,and thus generate a series of highly active sites for the hydrogen *** the theoretical prediction,electrochemical tests show that the A1-phase PtAuCu nanowire significantly outperforms its nanoparticle counterpart with phase segregation,toward the electrocatalysis of hydrogen evolution,offering one of the best hydrogen evolution electrocatalysts.

关键词： hydrogen evolution reaction phase engineering high entropy alloys

A strategy to improve the electrochemical performance of Ni-rich positive electrodes:Na/F-co-doped LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)

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Chinese Physics B 2021年第7期30卷 184-191页

作者： Hui Wan Zhixiao liu guangdong liu Shuaiyu Yi Fei Gao Huiqiu Deng Dingwang Yuan Wangyu Hu College of Materials Science and Engineering Hunan UniversityChangsha 410082China School of Physics and Electronics Hunan UniversityChangsha 410082China Department of Nuclear Engineering and Radiological Sciences University of MichiganAnn ArborMI 48109USA

Ni-rich layered lithium transition metal oxides LiNi_xMn_yCo_zO_(2)(1-y-z≥0.6)are promising candidates for cathode materials,but their practical applications are hindered by high-voltage instability and fast capacity *** density functional theory calculations,we demonstrate that Na-,F-doping,and Na/F-co-doping can stabilize the structure and result into a higher open circuit voltage than pristine LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)(NMC622)during the charging process,which may attain greater discharge capacity.F doping may inhibit the diffusion of Li ions at the beginning and end of charging;Na doping may improve Li ion diffusion due to the increase in Li layer spacing,consistent with prior ***/F-codoping into NMC622 promotes rate performance and reduces irreversible phase transitions for two reasons:(i)a synergistic effect between Na and F can effectively restrain the Ni/Li mixing and then enhances the mobility of Li ions and(ii)Ni/Li mixing hinders the Ni ions to migrate into Li layers and thus,stabilizes the *** study proposes that a layer cathode material with high electrochemical performance can be achieved via rational dopant modification,which is a promising strategy for designing efficient Li ion batteries.

关键词： Li ion batteries ion diffusion Na/F-co-doping first-principles calculations

Ambient formaldehyde concentrations in summer in 30 Chinese cities and impacts on air cleaning of built environment

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Energy and Built Environment 2024年第4期5卷 493-499页

作者： Shuolin Qiu Zirui He guangdong liu Zhen Ding Zhongming Bu Jianping Cao Wenjing Ji Wei liu Chunxiao Su Xinke Wang Fan liu Ting Li Hua Qian Cong liu School of Energy and Environment Southeast UniversityNanjingJiangsu210096China China Green Development Investment Group Co.LTD Beijing100000China Department of Environmental Health Jiangsu Provincial Center for Disease Control and PreventionNanjingJiangsu210009China Department of Energy and Environmental System Engineering Zhejiang University of Science and TechnologyHangzhouZhejiang310023China School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhouGuangdong510006China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China Institute for Health and Environment Chongqing University of Science and TechnologyChongqing401331China School of Environment and Architecture University of Shanghai for Science and TechnologyShanghai200093China School of Human Settlements and Civil Engineering Xi’an Jiaotong UniversityXi’an710049ShaanxiChina Tsinghua University Beijing100084China

Formaldehyde is an important carcinogen commonly found *** indoor sources have been intensively *** study on outdoor formaldehyde concentration,which is potentially an important source to indoors,remains *** study attempts to characterize temporal and spatial distribution of the atmospheric formalde-hyde concentration in Chinese *** variation of ambient formaldehyde was examined in 6 cities and peak hours were identified between 12:00 pm and 3:00 ***,outdoor formaldehyde concentrations were measured in the peak hours in 30 cities during the summer months of Jul.-Aug.,*** formaldehyde concentrations in the peak hours fell into a range of 0.005-0.087 mg/m^(3)(median value is 0.027 mg/m^(3)),87.7%of which have exceeded the chronic reference exposure criteria of 0.009 mg/m^(3) set by Office of Environmental Health Hazard *** risk analysis suggests that exposure to ambient formaldehyde could cause a median carcinogenic risk of 1.9×10^(−5)(3.17×10^(−6)-6.13×10^(−5)),higher than threshold limit of 10−*** correlation analysis of the 30 cities shows that ambient summertime atmospheric formaldehyde concentrations of the city are positively correlated with its Gross Domestic Product(r=0.48).We also found that the outdoor formaldehyde concentrations in urban areas(median:0.017 mg/m^(3))is slightly higher than those in suburban areas(median:0.013 mg/m^(3)).Results here prove that outdoor formaldehyde is ubiquitous in Chinese cities and reduces effectiveness of ventilation in dilution indoor *** it would underestimate air cleaner capacity needed by a factor of about *** should be accounted for in health analysis and air quality engineering control design of built environment in the future.

关键词： Atmospheric formaldehyde Temporal distribution Health risk Ventilation efficiency

Modification of short-range repulsive interactions in ReaxFF reactive force field for Fe–Ni–Al alloy

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Chinese Physics B 2021年第8期30卷 113-119页

作者： Huaqiang Chen Lin Lang Shuaiyu Yi Jinlong Du guangdong liu Lixia liu Yufei Wang Yuehui Wang Huiqiu Deng Engang Fu State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Department of Applied Physics School of Physics and ElectronicsHunan UniversityChangsha 410082China Department of Chemistry and Biology University of Electronic Science and Technology of China Zhongshan InstituteZhongshan 528402China

The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)*** this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)*** modified interaction covers three ranges,including short range,smooth range,and primordial *** short range is totally predominated by ZBL *** primordial range means the interactions in this range is the as-is ReaxFF with no *** smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper *** energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in *** modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.

关键词： molecular dynamics force field modification Fe–Ni–Al alloy irradiation

Cr-MCM-41 Molecular Sieves Crystallized at Room Temperature for Reaction of Ethane with CO_(2)

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Journal of Natural Gas Chemistry 2005年第4期14卷 207-212页

作者： Yanan Li Xin He Shujie Wu Ke Zhang guangdong Zhou Jie liu Kaiji Zhen Tonghao Wu Tiexin Cheng College of Chemistry Jilin University Changchun 130021 China

A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework, and dispersion of some CrsO3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM- 41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with COs to ethylene at 973 K. It is suggested that both Cr^6＋ and Cr^3＋ are the catalytic activity center.

关键词： Cr-MCM-41 molecular sieves ethane CO2 ethylene dehydrogenation

Density functional theory study of active sites and reaction mechanism of ORR on Pt surfaces under anhydrous conditions

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Chinese Journal of Catalysis 2022年第12期43卷 3126-3133页

作者： guangdong liu Huiqiu Deng Jeffrey Greeley Zhenhua Zeng School of Physics and Electronics Hunan UniversityChangsha 410082HunanChina Davidson School of Chemical Engineering Purdue UniversityWest LafayetteIN 47907USA

Identifying active sites and catalytic mechanism of the oxygen reduction reaction under anhydrous conditions are crucial for the development of next generation proton exchange membrane fuel cells(PEMFCs)operated at a temperature>100℃.Here,by employing density functional theory calculations,we studied ORR on flat and stepped Pt(111)surfaces with both(110)and(100)type of *** found that,in contrast to ORR under hydrous conditions,(111)terrace sites are not active for ORR under anhydrous conditions,because of weakened binding of ORR intermediates induced by O*accumulation on the *** the other hand,step edges,which are generally not active for ORR under hydrous conditions,are predicted to be the active sites for ORR under anhydrous *** them,(110)type step edge with a unique configuration of accumulated O stabilizes O_(2)adsorption and facilitates O_(2)dissociation,which lead an overpotential<0.4 *** improve ORR catalysts in high-temperature PEMFCs,it is desirable to maximize(110)step edge sites that present between two(111)facets of nanoparticles.

关键词： Oxygen reduction Active site Anhydrous condition High-temperature PEMFCs Density functional theory