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Constructal design of a rectangular porous fin considering minimization of maximum temperature difference and pumping power consumption

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Science China(Technological Sciences) 2024年第3期67卷 919-929页

作者： LIU XiaoYe FENG HuiJun CHEN LinGen GE YanLin institute of thermal Science and Power engineering Wuhan Institute of TechnologyWuhan 430205China College of Power engineering Naval University of EngineeringWuhan 430033China Hubei Provincial engineering Technology Research Center of Green Chemical Equipment Wuhan 430205China School of Mechanical&Electrical engineering Wuhan Institute of TechnologyWuhan 430205China

A heat dissipation model of a rectangular porous fin is established based on constructal theory. First, the constructal design of rectangular porous fin is conducted by selecting a complex function minimization, which composed of linear weighting sum of maximum temperature difference and pumping power consumption, as optimization objective. Effects of gap height, air inlet velocity, total porous fin volume and porosity on the optimal constructs are investigated, respectively. The findings show that the complex function can attain its double minimum at a value of 0.802 when the fin length and number are optimized, and the corresponding optimal fin length and number are 8.01 mm and 10, respectively. In comparison to original design, the complex function and maximum temperature difference after twice optimization are decreased by 19.80% and 66.31%, ***, the comprehensive performance of porous fin is improved by simultaneously optimizing the fin length and number. The artificial neural network is applied to predict the fin performances, which is used to conduct multi-objective optimization based on NSGA-II algorithm. Optimal structure of porous fin for multiple requirements is gained by LINMAP and TOPSIS decisionmaking strategies. The findings in this study can serve as theoretical guides for fin thermal designs of electronic devices.

关键词： constructal theory rectangular porous fin pumping power consumption maximum temperature difference complex function multi-objective optimization

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FedDAA:a robust federated learning framework to protect privacy and defend against adversarial attack

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Frontiers of Computer Science 2024年第2期18卷 107-122页

作者： Shiwei LU Ruihu LI Wenbin LIU Fundamentals Department Air Force Engineering UniversityXi’an 710051China institute of Advanced Computational Science and Technology Guangzhou UniversityGuangzhou 510006China

Federated learning(FL)has emerged to break data-silo and protect clients’privacy in the field of artificial ***,deep leakage from gradient(DLG)attack can fully reconstruct clients’data from the submitted gradient,which threatens the fundamental privacy of *** cryptology and differential privacy prevent privacy leakage from gradient,they bring negative effect on communication overhead or model ***,the original distribution of local gradient has been changed in these schemes,which makes it difficult to defend against adversarial *** this paper,we propose a novel federated learning framework with model decomposition,aggregation and assembling(FedDAA),along with a training algorithm,to train federated model,where local gradient is decomposed into multiple blocks and sent to different proxy servers to complete *** bring better privacy protection performance to FedDAA,an indicator is designed based on image structural similarity to measure privacy leakage under DLG attack and an optimization method is given to protect privacy with the least proxy *** addition,we give defense schemes against adversarial attack in FedDAA and design an algorithm to verify the correctness of aggregated *** results demonstrate that FedDAA can reduce the structural similarity between the reconstructed image and the original image to 0.014 and remain model convergence accuracy as 0.952,thus having the best privacy protection performance and model training *** importantly,defense schemes against adversarial attack are compatible with privacy protection in FedDAA and the defense effects are not weaker than those in the traditional ***,verification algorithm of aggregation results brings about negligible overhead to FedDAA.

关键词： federated learning privacy protection adversarial attacks aggregated rule correctness verification

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Experimental study on secondary air mixing along the bed height in a circulating fluidized bed with a multitracer-gas method

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Chinese Journal of Chemical engineering 2024年第6期70卷 54-62页

作者： Qingyu Zhang Leming Cheng Kun Li Qixun Kang Qiang Guo Chaogang Wu institute for thermal Power engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou 310027China Dongfang Boiler Group Co.Ltd. Zigong 643001China

A multitracer-gas method was proposed to study the secondary air(SA)mixing along the bed height in a circulating fluidized bed(CFB)using carbon monoxide(CO),oxygen(O_(2)),and carbon dioxide(CO_(2))as tracer *** were carried out on a cold CFB test rig with a cross-section of 0.42 m×0.73 m and a height of 5.50 *** effects of superficial velocity,SA ratio,bed inventory,and particle diameter on the SA mixing were *** results indicate that there are some differences in the measurement results obtained using different tracer gases,wherein the deviation between CO and CO_(2) ranges from 42%to 66%and that between O_(2) and CO_(2) ranges from 45%to 71%in the lower part of the fluidized ***,these differences became less pronounced as the bed height ***,the high solid concentration and fine particle diameter in the CFB may weaken the *** measurement results of different tracer gases show the same trends under the variation of operating *** superficial velocity and SA ratio and decreasing particle diameter result in better mixing of the *** effect of bed inventory on SA mixing is not monotonic.

关键词： Circulating fluidized bed Secondary air injection Gas mixing Multitracer-gas method

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Effects of Diesel Concentration on the thermal Conductivity,Specific Heat Capacity and thermal Diffusivity of Diesel-Contaminated Soil

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Journal of thermal Science 2024年第2期33卷 696-709页

作者： WU Yuhao WU Yuefei LUO Gubai ZHANG Teng WANG Qing FAN Liwu SONG Xin YU Zitao Key Laboratory of Clean Energy and Carbon Neutrality of Zhejiang Province Zhejiang UniversityHangzhou310027China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou310027China institute of thermal Science and Power Systems School of Energy EngineeringZhejiang UniversityHangzhou310027China Center Environmental protection Technology Company Limited Beijing100176China institute of Soil Science Chinese Academy of SciencesNanjing210008China

High energy consumption is a serious issue associated with in situ thermal desorption(TD)remediation of sites contaminated by petroleum hydrocarbons(PHs).The knowledge on the thermophysical properties of contaminated soil can help predict accurately the transient temperature distribution in a remediation site,for the purpose of energy ***,such data are rarely reported for PH-contaminated *** this study,by taking diesel as a representative example for PHs,soil samples with constant dry bulk density but different diesel mass concentrations ranging from 0% to 20% were prepared,and the variations of their thermal conductivity,specific heat capacity and thermal diffusivity were measured and analyzed over a wide temperature range between 0℃ and 120℃.It was found that the effect of diesel concentration on the thermal conductivity of soil is negligible when it is below 1%.When diesel concentration is below 10%,the thermal conductivity of soil increases with raising the ***,when diesel concentration becomes above 10%,the change of the thermal conductivity of soil with temperature exhibits the opposite *** is mainly due to the competition between soil minerals and diesel,because the thermal conductivity of minerals increases with temperature,whereas the thermal conductivity of diesel decreases with *** analysis results showed that,compared with temperature,the diesel concentration has more significant effects on soil thermal *** of the diesel concentration,with the increase of temperature,the specific heat capacity of soil increases,while the thermal diffusivity of soil *** addition,the results of a control experiment exhibited that the relative differences of the thermal conductivity of the soil samples containing the same concentration of both diesel and a pure alkane are all below 10%,indicating that the results obtained with diesel in this study can be extended to the family of PHs.A theo

关键词： contaminated soil diesel concentration thermal conductivity specific heat capacity thermal diffusivity thermal desorption fractal model

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Aerosol-radiation interaction and its variation in North China within 2015–2019 period under continuous PM_(2.5)improvements

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Journal of Environmental Sciences 2024年第2期136卷 81-94页

作者： Zhe Lv Xiaoqi Wang Wei Wei Huahua Bai Xiaoyu Liu Guohao Li Shuiyuan Cheng Department of Environmental Science and engineering Beijing University of TechnologyBeijing 100124China Key Laboratory of Beijing on Regional air Pollution Control Beijing 100124China Beijing Municipal Research institute of Eco-Environmental protection Beijing 100037China Beijing Key Laboratory of Urban Atmospheric Volatile Organic Compounds Pollution Control and Application Beijing 100037China

A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015–2019 ***-Chem simulations on 2017 showed that based on the six-city average,the aerosol load(PM_(2.5)concentrations)of 121.9,49.6,43.3,and 66.3μg/m^(3)in January,April,July,and October,mainly lowered the level of downward shortwave radiation by 38.9,24.0,59.1,and 24.4 W/m~2and reduced the boundary layer height by 79.9,40.8,87.4,and 31.0 m,via scattering and absorbing solar *** sensitivity of meteorological changes to identical aerosol loads varied in the order July>January>October and ***,the cooling and stabilizing effects of aerosols further led to increases in PM_(2.5),by23.0,3.4,4.6,and 7.3μg/m^(3)respectively in the four *** sensitivity of the effect of aerosols on PM_(2.5)was greatest in January rather than in July,contrary to the effect on ***,a negative linear relation was observed between daily BLH reductions and aerosol loads in fall and winter,and between PM_(2.5)increases and aerosol loads in all *** the PM_(2.5)pollution improvements in this region,the aerosol radiative forcing was effectively *** should result in daily BLH increases of 10–24 m in fall and winter,and the estimates in Beijing agreed well with the corresponding results based on AMDAR ***,the reduction in aerosol radiation effects brought about daily PM_(2.5)decreases of 1.6-2.8μg/m^(3),accounting for 7.0%–17.7%in PM_(2.5)improvements.

关键词： Radiative forcing Aerosol PM_(2.5) Boundary layer height(BLH) North China

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Microstructure and Internal Friction Behavior of Laser 3D Printed Fe-Based Amorphous Composites

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 196-204页

作者： Shuilong Huang Qingjun Chen Li Ji Kan Wang Guosheng Huang School of Material Science and engineering Nanchang Hangkong UniversityNanchang330063China State Key Laboratory for Marine Corrosion and protection Luoyang Ship Material Research Institute(LSMRI)Qingdao266237China

Laser 3D printing,also known as laser additive manufacturing(LAM),is favored for its ability to form bulk metallic glass(BMG)and its composite materials(BMGcs)with freeform *** this work,two different kinds of Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2)amorphous coatings(A and B)were prepared by using LAM technology under air-and water-cooled conditions,respectively;meanwhile,to reduce the cracks generated due to the residual thermal stresses,coating C obtained by air-sweep annealing of B with a low energy-density *** morphology and amorphous content and microstructure of the coatings were investigated,the results show many cracks in coating B deposited under water-cooled conditions,and its microstructure shows an amorphous-crystal-nanocrystalline mixed *** was suppressed in coating C,obtained by air-sweep annealing based on coating B,but the amorphous content was reduced from 32.6 to 13.4%.And the hardness and corrosion resistance of the coating will increase with the increase in the amorphous ***,the internal friction behavior of a BMGcs was prepared on the basis of the process of sample C is compared with that of as-cast amorphous *** results show that the low temperature internal friction behavior of BMGcs is affected by the defects produced during printing,and the high temperature internal friction behavior is affected by the precipitated hard phase.

关键词： Laser 3D printing Amorphous coating Microstructure Corrosion resistance Internal friction behavior

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A review on the chemical speciation and influencing factors of heavy metals in Municipal Solid Waste landfill humus

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Waste Disposal and Sustainable Energy 2024年第2期6卷 209-218页

作者： Qiongyu Sun Bo Sun Defeng Wang Yuyuan Pu Mingxiu Zhan Xu Xu Jinqing Wang Wentao Jiao College of Metrology and Measurement engineering China Jiliang UniversityHangzhou 310018Zhejiang ProvinceChina Zhongke Hualu Soil Remediation engineering Co. LtdDezhou 253011Shandong ProvinceChina Zhejiang Environmental protection Group Co. LtdHangzhou 310020Zhejiang ProvinceChina institute for thermal Power engineering Zhejiang UniversityHangzhou 310027Zhejiang ProvinceChina Research Center for Eco-Environmental Sciences Chinese Academy of SciencesHaidian District18 Shuangqing RoadBeijing 100085China

Heavy metal pollution in landfill humus can cause serious environmental problems and may endanger soil ecosystems and human *** biological toxicity of heavy metals is not only related to their total amount but also influenced to a greater extent by the distribution of their chemical *** the different chemical speciation and proportions of heavy metals can provide a more comprehensive and accurate understanding of the pollution characteristics and biological toxic-ity of heavy metals in landfill *** on a review of the relevant literature,this paper systematically summarizes the recent research status of typical heavy metal chemical speciation in landfill *** chemical speciation is diverse and *** instance,heavy metals in residual states and organically bound states have little impact on organisms,while heavy metals in exchangeable states and Fe-Mn oxide states can easily migrate and *** chemical speciation of heavy metals is affected by many factors,among which the soil pH and organic matter content are some of the most important ***,the existing gaps in the current research on the chemical speciation of heavy metals in landfills are described and future research directions are *** work provides a theoretical reference for researching the restoration of heavy metal-contaminated humus soil and the resource utilization of humus soil.

关键词： Landflls Humus soil containing heavy metal-Chemical speciation Distribution characteristics Influencing factors

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High-safety and high-voltage lithium metal batteries enabled by nonflammable diluted highly concentrated electrolyte

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Nano Research 2024年第4期17卷 2638-2645页

作者： Han Zhang Ziqi Zeng Shuping Wang Yuanke Wu Changhao Li Mengchuang Liu Xinlan Wang Shijie Cheng Jia Xie State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Advanced Electromagnetic engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Grid Anhui Electric Power Research institute Anhui Province Key Laboratory of Electric Fire and Safety Protection(State Grid Laboratory of Fire Protection for Transmission and Distribution Facilities)Hefei 230601China School of Chemistry and Chemical engineering Huazhong University of Science and TechnologyWuhan 430074China

Lithium metal batteries(LMBs)show great promise for achieving energy densities over 400 Wh·kg^(-1).However,highly flammable organic electrolytes are a long-lasting problem that triggers safety hazards and hinders the commercial application of ***,a nonflammable diluted highly concentrated electrolyte(DHCE)with ethoxy(pentafluoro)cyclotriphosphazene(PFPN)as a diluent is developed to simultaneously achieve high safety and cycling stability of high-voltage *** optimal DHCE not only ensures reversible Li deposition/dissolution behavior with a superior average Coulombic efficiency(CE)over 99.1%on lithium metal anode(LMA),but also suppresses side reactions and stress crack on the LiCoO_(2)(LCO)under high cut-off *** newly developed DHCE exhibits high thermal stability,showing complete nonflammability and reduced heat generation between the electrolyte and delithiated LCO/cycled *** work offers an opportunity for rational designing nonflammable electrolytes toward high-voltage and safe LMBs.

关键词： lithium metal batteries thermal stability nonflammable electrolyte high-voltage phosphazene

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Optical and electrical anisotropy regulation engineering of low-dimensional materials toward polarized detection and imaging applications

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Rare Metals 2024年第7期43卷 2968-2993页

作者： Jian-Bin Zhang Nan Zhou Li-Hui Zhang Cong-Hui Shang Jia-Xuan Li Yi Zhao Guo-Hui Jia Ru-Sen Yang Hua Xu Xiao-Bo Li Shaanxi Joint Key Laboratory of Graphene Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for AerospaceShaanxi Joint Key Laboratory of GrapheneSchool of Advanced Materials and NanotechnologyXidian UniversityXi'an710126China Guangzhou institute of Technology Xidian UniversityGuangzhou 710068China Xi'an thermal Power Research institute Co. LtdXi'an 710054China Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi'an Xi'an 710119China

Polarized-sensitive image sensors are a kind of photodetector with great development potential due to their enhanced ability to detect and identify the target objects from the aspect of spatial,spectral and polarized ***,low-dimensional anisotropic materials with inherent anisotropic properties,ultrathin thickness,tunable bandgap and feasible integration with complementary metal oxide semiconductor(CMOS)fabrication processes have attracted great interest for their facilitation of polarized photodetector devices *** the polarized detection performance of low-dimensional materials to satisfy realistic needs stimulates the exploration of modulation of anisotropic *** this review,we comprehensively introduce the latest research progress in modulating the optical and optoelectronic anisotropy characteristics of low-dimensional *** strategy of anisotropy regulation through crystal structure engineering and coupling system is discussed ***,the latest progress in image recognition applications using anisotropic low-dimensional materials is reviewed in ***,we summarize the challenge and propose future opportunities in the practical application of polarized-sensitive imaging photodetectors based on low-dimensional anisotropic materials.

关键词： Anisotropy Polarized detection Image recognition Low-dimensional materials

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Dynamic emission characteristics and control strategies of air pollutants from motor vehicles in downtown Beijing,China

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Journal of Environmental Sciences 2024年第2期136卷 637-646页

作者： Yan Shen Tongran Wu Aiping Lian Jie Gao Fei Peng Guohua Song Xuefang Wu Yangyang Cui Xinyu Liu Yunfei Wan Jing Yan Yifeng Xue National engineering Research Center of Urban Environmental Pollution Control Beijing Municipal Research Institute of Eco-Environmental ProtectionBeijing 100037China Beijing Municipal Ecology and Environment Bureau Beijing 100048China Beijing Jiaotong University Beijing 100091China

This study combined the real-time monitoring and investigation of traffic flows to comprehensively analyze the road traffic flow and vehicle structure in downtown Beijing.A dynamic emission inventory of motor vehicle air pollutants in downtown Beijing in 2021 was established,and the impact of these emissions on air quality was simulated and quantified,and different emission reduction control scenarios were proposed to evaluate their environmental improvement effects and explore measures to mitigate the impact of pollution *** results show that the high traffic flow and the structure of the motor vehicle emissions in downtown Beijing are the main causes of severe motor vehicle *** data shows that traffic flow in central Beijing is dominated by small passenger vehicles,while the vehicle mix is better than in other regions,with 72.0%of vehicles meeting"National V"or higher emission ***,to achieve higher air quality goals,further reducing vehicle emissions is *** on dynamic traffic flow,the average daily emissions of nitrogen oxides(NOX),particulate matters(PM_(2.5))and volatile organic compounds(VOC)from motor vehicles in central Beijing are 17.7 tons,0.6 tons and 14.0 tons,respectively,accounting for 23.0%of the city’s average daily motor vehicle *** a zero-emission zone for motor vehicles were implemented in central Beijing,the annual average emission level of pollutants will be reduced by 10.4%to 21.0%.The designation of ultra-low emission zones for motor vehicles could be effective in improving the air quality in the center of Beijing.

关键词： Motor vehicle air pollutant Emission characteristics Control strategy Beijing

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