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Multiscale simulation of the urban wind environment under typhoon weather conditions

Building Simulation 2023年第9期16卷 1713-1734页

作者： Zihan Zhao Yiqing Xiao Chao Li P.w.Chan Gang Hu qingfeng Zhou School of Construction Engineering Shenzhen PolytechnicShenzhenChina School of Civil and Environmental Engineering Harbin Institute of Technology ShenzhenShenzhenChina Hong Kong Observatory KowloonHong KongChina Shenzhen Urban Planning&Land Resources Research Center ShenzhenGuangdong 518055China

Accurate simulations of planetary boundary layer(PBL)winds in urban areas require combining meteorological knowledge and fine-grained geometrical *** fluid dynamics(CFD)is widely used to assess pedestrian wind comfort and wind disasters in planning resilient ***,the CFD-predicted PBL is highly affected by the inflow *** profiles under extreme weather conditions,such as tropical cyclones,can hardly be determined,and associated uniform logarithmic or power law expressions have not been *** this study,urban wind flow over mountainous terrain was simulated using a one-way nested simulation approach between mesoscale and microscale *** inflow wind speed,turbulence scalars,and potential temperature in the CFD code are sustained by the numerical weather prediction(NwP)*** considering typhoon weather conditions were examined to improve the numerical accuracy in determining mesoscale typhoon structures and pedestrian-level wind *** numerical errors were quantified in mesoscale and microscale formulations.A new tendency assimilation was proposed by incorporating local-scale observations into the CFD *** approach entailed empirical mode decomposition to quantify the mean wind speed differences between the observations and NwP results,which were then extrapolated to NwP-CFD nested interfaces via multiplication by the spatial correlation *** numerical performance was validated against both on-site observations for meteorological purposes and wind profiles retrieved from the experimental LiDAR of the landfalling typhoon *** simulated wind field exhibited an increased accuracy in the local urban *** specifically,the index of agreement in wind speeds was improved from 0.28 to 0.72,and the mean absolute errors were reduced from 5.46 m/s to 1.89 m/s.

关键词： NwP-CFD urban wind flow data assimilation typhoon disaster resilient cities

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Tungsten Isotopic Constraints on the Nature of Earth's Accreting Materials

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Acta Geologica Sinica(English Edition) 2022年第4期96卷 1213-1220页

作者： MEI qingfeng YAng Jinhui State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

Tungsten isotope is a powerful tracer for the Earth’s accreting materials because of the distinct w isotope compositions of the non-carbonaceous meteorites and carbonaceous *** better understand the evolution of the early Earth,here we calculated the expectedμ^(183)w of the bulk silicate Earth for different assumed compositions of the proto-Earth’s mantle,the Moon-forming giant impactor,and the late veneer using a Monte Carlo *** result shows that the proto-Earth likely has a non-carbonaceous composition,while the carbonaceous chondrite-like materials were delivered to the Earth at the late stages of *** predicted difference inμ^(183)w values between the bulk silicate Earth and the non-carbonaceous meteorites of the scenarios assuming a pure carbonaceous composition for the giant impactor is slightly bigger than that of the scenarios assuming either a pure non-carbonaceous or a mixed carbonaceous-non-carbonaceous composition for the giant impactor(~5 ppm versus~2 ppm).The ancient mantle reservoir that partially lacks the late veneer with carbonaceous composition should have a negativeμ^(183)w value(from-3 to 0).Uncertainties introduced by the cosmogenic effects and mass-independent fractionation should be concerned during the high precision measurement ofμ183w for meteorites and ancient terrestrial samples in further work.

关键词： tungsten isotope nucleosynthetic anomalies Moon-forming giant impact late veneer

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Influence of the symmetry energy on the balance energy of the directed flow

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Science China(Physics,Mechanics & Astronomy) 2012年第2期55卷 252-259页

作者： GUO ChenChen w.ng YongJia LI qingfeng TRAUTMANN w LIU Ling wU LiJuan School of Science Huzhou Teachers CollegeHuzhou 313000China College of Physics Science&Technology Shenyang Normal UniversityShenyang 110034China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China GSI Helmholtzzentrum fuer Schwerionenforschung GmbH Darmstadt D-64291Germany

The influence of the density-dependent symmetry energy on the balance energy （Ebal） of directed flow from heavy ion collisions （HICs） at incident energies covered by INDRA and MSU experiments is studied, using the updated version of the ultra- relativistic quantum molecular dynamics （UrQMD） model, especially adapted to low-energy heavy ion collisions （HICs）. Four mass-symmetric reactions with total mass numbers between 192 and 394 are chosen for investigating the influence of the symmetry energy on the system-mass dependence of Eual. The results show that the uncertainty in the density dependence of the symmetry potential causes changes of Ebal of the order of several MeV, depending on the type of particle considered. The Ebal of neutrons from HICs is particularly sensitive to the density dependence of the symmetry potential energy, while the system-mass dependence of EbaI of Z = 1 particles is not.

关键词： symmetry energy directed flow balance energy

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Novel voltage signal at proximity-induced superconducting transition temperature in gold nanowires

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Science China(Physics,Mechanics & Astronomy) 2018年第8期61卷 69-74页

作者： Jian w.ng JunXiong Tang ZiQiao w.ng Yi Sun qingfeng Sun Moses H.w.Chan International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China State Key Laboratory of Low-Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Department of Physzcs The Pennsylvania State UniversityPennsylvania 16802-6300USA CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Department of Physics University of Colorado BoulderCO 80309USA

we observed a novel voltage peak in the proximity-induced superconducting gold(Au) nanowire while cooling the sample through the superconducting transition temperature. The voltage peak turned dip during warming. The voltage peak or dip was found to originate respectively from the emergence or vanishing of the proximity-induced superconductivity in the Au *** amplitude of the voltage signal depends on the temperature scanning rate, and it cannot be detected when the temperature is changed slower than 0.03 K/min. This transient feature suggests the non-equilibrium property of the effect. Ginzburg-Landau model clarified the voltage peak by considering the emergence of Cooper pairs of relatively lower free energy in superconducting w contact and the non-equilibrium diffusion of Cooper pairs and quasiparticles.

关键词： proximity-induced superconductivity Au nanowire non-equilibrium process

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A Thermo-mechanical Investigation on Laser Ablation of Aluminum Alloy

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Acta Mechanica Solida Sinica 2023年第5期36卷 658-671页

作者： Xuehai Qian Yongkang Luo qingfeng Chai Yu Zhang Lv Zhao Department of Mechanics School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan 430074China National Key Laboratory of Strength and Structural Integrity Aircraft Strength Research Institute of ChinaXi’an 710065China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Hubei Key Laboratory of Engineering Structure Analysis and Safety Assessment 1037 Luoyu RoadWuhan 430074China

The interactions between laser and metal are extremely complicated,during which material is gradually removed due to melting or *** further leads to a continuously moving ablation front and a strong temperature gradient,ultimately producing through-thickness holes and residual stresses inside the *** present work establishes a simulation framework which couples the loading of laser beam and the moving ablation front by using the"birth-death"element *** framework allows to obtain accurate temperature field and ablated area,the latter being quite close to experimental results with 2024 aluminum ***,the Johnson-Cook constitutive model is employed to assess the residual stress and damage around the ablation holes,therefore enabling the evaluation of residual strength of ablated target.

关键词： Laser ablation Moving front Aluminum alloy Johnson–Cook model Residual stress

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An Image Steganography Algorithm Based on Quantization Index Modulation Resisting Scaling Attacks and Statistical Detection

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Computers, Materials & Continua 2018年第7期56卷 151-167页

作者： Yue Zhang Dengpan Ye Junjun Gan Zhenyu Li qingfeng Cheng State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou 450001China Computer School of wuhan University Wuhan 430072China Department of Computer Science University of YorkYork YO105GHUK

In view of the fact that the current adaptive steganography algorithms are difficult to resist scaling attacks and that a method resisting scaling attack is only for the nearest neighbor interpolation method,this paper proposes an image steganography algorithm based on quantization index modulation resisting both scaling attacks and statistical *** the spatial image,this paper uses the watermarking algorithm based on quantization index modulation to extract the embedded *** construct the embedding distortion function of the new embedded domain based on S-UNIwARD steganography,and use the minimum distortion coding to realize the embedding of the secret ***,according to the embedding modification amplitude of secret messages in the new embedded domain,the quantization index modulation algorithm is applied to realize the final embedding of secret messages in the original embedded *** experimental results show that the algorithm proposed is robust to the three common interpolation attacks including the nearest neighbor interpolation,the bilinear interpolation and the bicubic *** the average correct extraction rate of embedded messages increases from 50%to over 93% after 0.5 times-fold scaling attack using the bicubic interpolation method,compared with the classical steganography algorithm *** the algorithm proposed has higher detection resistance than the original watermarking algorithm based on quantization index modulation.

关键词： Image steganography anti-scaling attack anti-statistical detection quantization index modulation

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Hierarchical Ni-Co-S@Ni-w-O core-shell nanosheet arrays on nickel foam for high-performance asymmetric supercapacitors

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Nano Research 2018年第3期11卷 1415-1425页

作者： weidong He Zhifu Liang Keyu ji qingfeng Sun Tianyou Zhai Xijin Xu School of Physics and Technology University of Jinan 336 West Road of Nan Xinzhuang Jinan 250022 China State Key Laboratory of Material Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology (HUST) Wuhan 430074 China School of Engineering Zhejiang A & F University Hangzhou 311300 China

Nickel cobalt sulfides （Ni-Co-S） have attracted extensive attention for application in electronic devices ow.ng to their excellent conductivity and high electrochemical capacitance. To facilitate the large-scale practical application of Ni-Co-S, the excellent rate capability and cyclic stability of these compounds must be fully exploited. Thus, hierarchical Ni-Co-S@Ni-w-O （Ni-Co-S-w） core/shell hybrid nanosheet arrays on nickel foam were designed and synthesized herein via a facile three-step hydrothermal method, followed by annealing in a tubular furnace under argon atmosphere. The hybrid structure was directly assembled as a free-standing electrode, which exhibited a high specific capacitance of 1,988 F·g^-1 at 2 A·g^-1 and retained an excellent capacitance of approximately 1,500 F·g^-1 at 30 A·g^-1, which is superior to the performance of the pristine Ni-Co-S nanosheet electrode. The assembled asymmetric supercapacitors achieved high specific capacitance （155 F·g^-1 at 1 A·g^-1）, electrochemical stability, and a high energy density of 55.1 w·h·kg^-1 at a power density of 799.8 w·kg^-1 with the optimized Ni-Co-S-w core/shell nanosheets as the positive electrode, activated carbon as the negative electrode, and 6 M KOH as the electrolyte.

关键词： core/shell structure free-standing electrode supercapacitors high energy density excellent stability

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Expression of liver insulin-like growth factor 1 gene and its serum level in patients with diabetes

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world Journal of Gastroenterology 2004年第2期10卷 255-259页

作者： Jian-BoLi Cheng-Yaw.ng Jia-weiChen Zhen-qingfeng Hong-TaiMa DepartmentofEndocrinology FirstAffiliatedHospitalofNanjingMedicalUniversityNanjing210029JiangsuProvinceChina MolecularLaboratory FirstAffiliatedHospitalofNanjingMedicalUniversityNanjing210029JiangsuProvinceChina DepartmentofPathology NanjingMedicalUniversityNanjing210029JiangsuProvinceChina

AIM:To explore the effect of diabetic duration and blood glucose level on insulin like growth factor 1(IGF-1) gene expression and serum IGF-1 ***: Diabetes was induced into Sprague Dawley rats by alloxan and then the rats were subdivided into different groups with varying blood glucose level and diabetic *** parameters were measured as follows:IGF-1 mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR),IGF-1 peptide and serum IGF-1 concentration by enzymelinked immunosorbent assay (ELISA).RESULTS:During early diabetic stage (week 2),in comparison with normal control group (NC), IGF-1 mRNA(1.17±0.069 vs 0.79±0.048, Png·mg^-1 vs(128.2±11.25)ng·mg^-1,Png·mg^-1 vs(74.43±5.33)ng·mg^-1, Pwere reduced in liver tissues of diabetic *** IGF-1 gene downregulation varied with glucose control level of the diabetic state,and deteriorated gradually further with duration of *** month 6, hepatic tissue IGF-1mRNA was 0.71±0.024 vs 1.12±0.056,Pwas (114.35±8.09) ng·mg^-1 vs (202.05±15.73)ng·mg^-1,Png·mg^-1 vs(202.05±15.73)ng·mg^-1,Pwas also lowered in diabetic group with poor control of blood *** week 2, serum IGF-1 concentrations were (371.0±12.5)ng·mg^-1 vs(511.2±24.7)ng·mg^-1,Png·mg^-1 vs(511.2±24.7)ng·mg^-1, Png·mg^-1 vs(520.7±26.32)ng·mg^-1,Png·mg^-1,Pnge was significantly correlated with that in liver tissue (r=-0.99, Pwas found in the above parameters between diabetic rats with euglycemia and non-diabetic control ***: The influence of diabetic status on IGF-1 gene expression in li

关键词：胰岛素样生长因子1 基因表达血清学检查糖尿病逆转录聚合酶链反应 ELISA 动物模型

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Enhanced thermoelectric performance of n-type Bi_(2)Te_(2.7)Se_(0.3) via a simple liquid-assisted shear exfoliation

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Journal of Materials Science & Technology 2022年第22期117卷 251-258页

作者： Yifeng w.ng Yilin Song Kaikai Song Lin Pan Changchun Chen Kunihito Koumoto qingfeng Liu College of Materials Science and Engineering Nanjing Tech UniversityNanjing 210009China Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites Nanjing Tech UniversityNanjing 210009China Nagoya Industrial Science Research Institute Nagoya 464-0819Japan Center of Nanotechnology King Abdulaziz UniversityJeddah 21589Saudi Arabia State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 210009China

A liquid-assisted shear exfoliation (LASE) as a new powder metallurgy method coupled with spark plasmasintering (SPS) was applied for n-type Bi_(2)Te_(2.7)Se_(0.3) and the effects on microstructure and anisotropictransport properties were investigated. Results revealed an effective reduction of average grain size dueto LASE and a high texturing in the bulks. Moreover, along the in-plane direction, electrical conductivitywas increased noticeably due to an enhanced carrier concentration, leading to a significantly improvedpower factor of 25 μw cm^(–1) K^(–2) at 303 K. Meanwhile, the total thermal conductivity was reduced effectively ow.ng to reduction both in lattice component due to enhanced phonon scattering with the grainsize reduction, and in the bipolar component inhibited by the increased carrier concentration. Ultimately,a peak thermoelectric figure of merit (ZT) value of 0.83 was obtained at 448 K along the in-plane direction, increased by 95% compared with the pristine one. These results demonstrate the LASE process as auseful assistant method for enhancing the TE performance of layered materials.

关键词： Bi_(2)Te_(2.7)Se^(0.3) Liquid-assisted shear exfoliation Textured microstructure Thermoelectric

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Hot-top direct chill casting assisted by a twin-cooling field:Improving the ingot quality of a large-size 2024 Al alloy

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Journal of Materials Science & Technology 2022年第17期112卷 114-122页

作者： Cheng Zhu Zhihao Zhao qingfeng Zhu Gaosong w.ng Yubo Zuo Qiangqiang Li Gaowu Qin Research Center for Metallic wires School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China Key Laboratory of Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

Microstructure inhomogeneity and negative segregation have long been challenges for large-size alloy ingots,directly affecting the downstream processing and final performance of ***,we used2024 aluminum alloy as a model alloy to propose a technique,named double-cooling field casting,i.e.,one 2024 Al alloy rod(Φ20 mm)at room temperature was introduced into the melt along the central axis of the hot-top with the protection of a thermal-insulation tube during the direct chill(DC)casting process of aΦ300 mm 2024 Al alloy *** results show that the introduction of the same alloy solid insert has a remarkable influence on refining grains in the center region of the ingot,reducing negative centerline segregation and decreasing the depth of the center part of the *** the application of the 2024 Al insert,the mean size of equiaxed grains at the center part of the ingot decreased from1204±132μm to 721±69μ*** relative deviation of the Cu and Mg main solutes reduced from-0.062 and-0.054 to-0.03 and-0.024,respectively,and the sump depth decreased from 280 mm to242 ***,the shape of the solidification front was changed from‘V’-shaped to‘w’-*** ingot quality was thus improved,mainly arising from the dissolution of the cold 2024 Al insert at a proper position of the hot-top counteracting some latent heat of solidification of the ingot,dissipating the heat of the central part of the hot-top by conducting the 2024 Al insert to the outside,and providing extra-nuclei from the unmoltenα-Al particles of the insert.

关键词： Aluminum alloy DC casting Solid insert Grain refinement Macrosegregation

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