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Voidage correction method for DEM study of 3D pebble flows in a bed of cycloidal base

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PARTIcUOLOGY 2024年第10期93卷 30-40页

作者： Xia, Zirui Shi, Minglei Zou, Quan Gui, Nan Yang, Xingtuan Tu, Jiyuan jiang, Shengyao Tsinghua Univ Inst Nucl & New Energy Technol Collaborat Innovat Ctr Adv Nucl Energy Technol Key Lab Adv Reactor Engn & SafetyMinist Educ Beijing 100084 Peoples R China Tsinghua Univ Dept Engn Phys Beijing 100084 Peoples R China Tsinghua Univ Dept Automat Beijing 100084 Peoples R China RMIT Univ Sch Engn Melbourne Vic 3083 Australia

Voidage (porosity or void fraction) in packed particles (or pebbles) is of fundamental importance in calculating the pressure drop, obtaining the drag, predicting the bed permeability, estimating the neutron streaming, etc. For the case when particles are deformed, a method of voidage correction during the packing state is proposed using a Discrete Element Method (DEM) simulation of 3D pebble flow inside a bed of cycloidal base. A function to evaluate the remaining volume of a pebble intercepted by horizontal and vertical planes is proposed for voidage calculation. After that, the process of solving voidage distribution is provided in detail. Using this method, the voidage inside the cycloidal-base pebble bed is obtained to refer to reported similar data for validation. This method can be potentially used for dynamical voidage calculation in cFD-DEM simulation which can get suitable voidage distribution after the correction. (c) 2024 chinese Society of Particuology and Institute of Process Engineering, chinese Academy of Sciences. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： Voidage Pebble flow Packed bed Discrete element method cycloidal base KD-Tree Volume correction RADIAL POROSITY GAS MODEL SIMULATION PAcKINGS SPHERES

Evolution of microstructure and texture of AZ80 magnesium alloy under hot torsion with constant decreasing temperature rate

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Journal of Magnesium and Alloys 2024年第4期12卷 1619-1637页

作者： Yongbiao Yang Jinxuan Guo cuiying Wang Wenxuan jiang Zhimin Zhang Qiang Wang Xing Zhang college of Materials Science and Engineering North University of ChinaLane 3Xueyuan RoadTaiyuanShanxi 030051China North Hongyang mechanical and electronic limited company of Henan Province China

Hot torsion tests for AZ80 magnesium alloy were carried out in the temperature range of 380℃-260℃,with a constant decreasing temperature rate of 10℃/s in order to weaken the basal texture and refine the *** results indicated that the average grain sizes were refined forming gradient structure with increasing specimen radial position from center(12.2-5.4μm),and that the initial basal texture intensity of the extruded magnesium alloy was weakened from 46.2 to ***,the extension twins(ETs)could be disintegrated from the twins forming separated twins with smaller ***,ETs with the same twin variant intersecting with each other could be coalesced forming grains with similar orientation,while ETs with different twin variants were separated by twins boundaries contributing to grain ***,in addition to the conventional continuous dynamic recrystallized(cDRX)grains with 30˚orientation rotated around c-axis of the parent grains,cDRXed grains with 30˚rotation around a-axis and random rotation axis were also ***,the cDRX evolution induced twins were also elaborated,exhibiting the complex competition between cDRX and *** torsion deformation with constant decreasing temperatures rate is an effective way of grain refinement and texture modification.

关键词： Texture Microstructure Hot torsion Decreasing temperature AZ80

Effects of thinning and understory removal on water use efficiency of Pinus massoniana:evidence from photosynthetic capacity and stable carbon isotope analyses

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Journal of Forestry Research 2024年第2期35卷 42-53页

作者： Ting Wang Qing Xu Beibei Zhang Deqiang Gao Ying Zhang Jing jiang Haijun Zuo Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Ecology and Nature Conservation InstituteChinese Academy of ForestryBeijing 100091People’s Republic of China college of Agronomy and Agricultural Engineering Liaocheng UniversityLiaocheng 252000People’s Republic of China Department of Forest and conservation Sciences Faculty of ForestryUniversity of British ColumbiaVancouverBC V6T 1Z4Canada

Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate ***,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management *** this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of *** capacity and needle stable carbon isotope composition(δ^(13)c)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were ***,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water *** removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water *** general,thinning may be an appropriate management measure to promote *** WUE to cope with seasonal droughts under future extreme climates.

关键词： Stable carbon isotope Water use efficiency Thinning Understory removal Photosynthetic capacity Needle water potential

A novel method for calculating broadband electrical performance of high-speed aircraft radome under thermo-mechanical-electrical coupling

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cHINESE JOURNAL OF AERONAUTIcS 2024年第9期37卷 463-474页

作者： Ji, Jianmin Ren, Jianhua jiang, Xunya Wang, Wei Yu, Huilong Yin, Kai chen, Bo Beijing Inst Remote Sensing Equipment Beijing 100854 Peoples R China Shanghai DongJun Informat & Technol co Ltd Shanghai 200050 Peoples R China

The electrical performance of radomes on high-speed aircraft can be influenced by the thermal and mechanical loads produced during high-speed flight, which can affect the detection distance and accuracy of the guidance system. This paper presents a new method that uses the Finite Difference Time Domain (FDTD) method to calculate the electrical performance of radomes under Thermo-Mechanical-Electrical (TME) coupling. This method can accurately characterize the effects of material dielectric temperature drift and structural deformation on the electrical performance of the radome under flight conditions, enabling high-precision full-wave calculations of the broadband electrical performance of the radome. The method initiates by utilizing a Finite Element Grid Model (FE-GM) of the radome to sequentially acquire the radome's response temperature field and structural deformation field through thermal and mechanical simulations. Subsequently, spatial mapping techniques are developed to accurately incorporate the dielectric temperature drift and structural deformation of the radome into its Yee grid Electromagnetic (EM) simulation model. A verification case was designed to test the proposed method, and the results confirmed its high computational accuracy. Additionally, the effectiveness and necessity of the method were further demonstrated by analyzing the electrical performance of a fused silica ceramic radome used on a high-speed aircraft. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of chinese Society of Aeronautics and Astronautics. This is an open access article under the cc BY-Nc-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： High-speed aircraft Radomes Thermo-Mechanical- Electrical (TME) coupling Finite Difference Time Domain (FDTD) method Spatial mapping DESIGN

Strong ferroelectric and luminescence properties of 0-3 type 0.8BaTiO_(3)-0.2caTiO_(3):Pr^(3+)composite ceramics prepared by cold sintering process

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Journal of Advanced ceramics 2024年第7期13卷 1002-1010页

作者： Xiaocui Rao Xueling Yang Renbing Sun Peng Du Hai jiang Yao Huang Laihui Luo Department of Microelectronics Science and Engineering School of Physical Science and TechnologyNingbo UniversityNingbo 315211China college of Materials Science and Engineering Ningbo University of TechnologyNingbo 315016China

0-3 type ferroelectric-phosphor composite ceramics cannot be prepared by the traditional solid-state sintering(SSS)method due to the strong chemical reaction between ferroelectrics and phosphors during high-temperature *** cold sintering process(cSP)may solve this issue by densifying ceramics at ultralow sintering *** this work,dense 0-3 type 0.8BaTiO_(3)-0.2caTiO_(3):Pr^(3+)(0.8BT-0.2cT:Pr^(3+))binary composite ceramics were fabricated at an ultralow temperature of 225℃via cSP with the Ba(OH)2·8H2O hydrated *** effects of the Ba(OH)_(2)·8H2O content,sintering temperature,and sintering time on the microstructure and densification of the ceramics were *** density of the composite ceramics prepared by the optimized sintering parameters reaches 89%.Both energy-dispersive X-ray(EDX)spectroscopy and X-ray diffraction(XRD)confirm the existence of BT and cT:Pr^(3+)phases in the prepared ceramics.A strong ferroelectric performance is obtained,and the luminescent properties of cT:Pr^(3+)are preserved for the ***,the 0.8BT-0.2cT:Pr^(3+)composite ceramics prepared by cSP have stronger photoluminescence and photo-stimulated luminescence than their counterparts prepared by cold sintering assistance(cSA)and SSS ***,cSP is a promising method for combining luminescent and ferroelectric properties into 0-3 type composite ceramics.

关键词： single-step densification cold sintering composite ceramics ferroelectric luminescence

On-chip Micro Temperature controllers Based on Freestanding Thermoelectric Nano Films for Low-Power Electronics

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Nano-Micro Letters 2024年第7期16卷 98-108页

作者： Qun Jin Tianxiao Guo Nicolas Perez Nianjun Yang Xin jiang Kornelius Nielsch Heiko Reith Institute for Metallic Materials Leibniz Institute for Solid State and Materials Research01069 DresdenGermany Institute of Materials Engineering University of Siegen57076 SiegenGermany Institute of Applied Physics Technical University of Dresden01069 DresdenGermany Institute of Materials Science Technical University of Dresden01069 DresdenGermany

Multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend Moore’s Law of modern ***,this inevitably exac-erbates the inhomogeneity of temperature distribution in microsystems,making precise temperature control for electronic components extremely ***,we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50×50μm^(2),which are fabricated from dense and flat freestanding Bi2Te3-based ther-moelectric nano films deposited on a newly developed nano graphene oxide membrane *** tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics.A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445μW,resulting in an ultrahigh temperature control capability over 100 K mW^(-1).Moreover,an ultra-fast cooling rate exceeding 2000 K s^(-1) and excellent reliability of up to 1 million cycles are *** proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.

关键词： Temperature control Low-power electronics On-chip micro temperature controller Freestanding thermoelectric nano films Temperature-sensitive components

Well-controlled Organocatalytic Ring-opening Polymerization of Seven-membered cyclic carbonates with cyclohexyl Fusion

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cHEMIcAL RESEARcH IN cHINESE UNIVERSITIES 2024年第5期40卷 856-862页

作者： Zhang, Wei Shan, Si-Yi Dai, jiang cai, Zhongzheng Zhu, Jian-Bo Tianjin Univ Sci & Technol Coll Chem Engn & Mat Sci Tianjin Key Lab Brine Chem Engn & Resource Ecoutil Tianjin 300457 Peoples R China Sichuan Univ Coll Chem Natl Engn Lab Ecofriendly Polymer Mat Sichuan Chengdu 610064 Peoples R China

Developing green and well-controlled polymerization methods is of great significance for the preparation of biomedical polymer materials. In this contribution, an efficient organocatalytic ring-opening polymerization (ROP) of a class of seven-membered cyclic carbonates (T6DO, T6HDO, c6DO, c6HDO) containing cis- or trans-cyclohexane structure was established. Organic catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) promoted living polymerization of these cyclic carbonates to deliver polycarbonate and block copolymer products with predictable molecular weights and narrow dispersity. The robust TBD-mediated ROP at 90 degrees c showcased turnover frequency (TOF) up to 10(3) h(-1). The resulting amorphous polycarbonates displayed good thermal stability.

关键词： cO2 Organic catalyst Living ring-opening polymerization Aliphatic polycarbonate KINETIc RESOLUTION POLYMERIZATION RAc-LAcTIDE

Frequent recombination in cynoglossus abbreviatus(Pleuronectiformes:cynoglossidae)ribosomal 18S rDNA

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Acta Oceanologica Sinica 2024年第8期43卷 98-103页

作者： Li Gong Tingqi jiang Bilin Hu Kaixin Wang Nannan Zhang Zengliang Miao National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization Zhejiang Ocean UniversityZhoushan 316022China Marine Science and Technology college Zhejiang Ocean UniversityZhoushan 316022China

The conventional theory of concerted evolution has been used to explain the lack of sequence variation in ribosomal RNA(rRNA)genes across diverse eukaryotic ***,recent investigations into rRNA genes in flatfish genome have resulted in controversial *** study focuses on 18S rRNA genes of the widely distributed tongue sole,cynoglossus abbreviatus(Pleuronectiformes:cynoglossidae),aiming to explore sequence *** distinct 18S rDNA sequence types(Type A,B,R1,R2,and R3)were identified,suggesting a departure from concerted evolution.A combination of general criteria and variations in highly conserved regions were employed to detect *** results pinpointed Type A sequences as potential pseudogenes due to significant sequence variations and deviations in secondary structure within highly conserved *** types(Type R1,R2,and R3)were identified as recombinants between Type A and B sequences,with simple crossing over and gene conversion as the most likely recombination *** findings not only contribute to rRNA pseudogene identification but also shed light on the evolutionary dynamics of rRNA genes in teleost genomes.

关键词： ribosomal RNA tongue sole non-concerted evolution pseudogene crossing over gene conversion

Screening the optimal co_(x)/ceO_(2)(110)(x=1–6)catalyst for methane activation in coalbed gas

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International Journal of coal Science & Technology 2024年第3期11卷 256-271页

作者： Li’nan Huang Danyang Li Lei jiang Zhiqiang Li Dong Tian Kongzhai Li Engineering Research center of Metallurgical Energy conservation and Emission Reduction Ministry of EducationKunming University of Science and TechnologyKunming650093China Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming650093China State Key Laboratory of complex Nonferrous Metal Resources clean Utilization Kunming University of Science and TechnologyKunming650093China

The challenges posed by energy and environmental issues have forced mankind to explore and utilize unconventional energy *** is imperative to convert the abundant coalbed gas(cBG)into high value-added products,i.e.,selective and efficient conversion of methane from *** activation,known as the“holy grail”,poses a challenge to the design and development of *** structural complexity of the active metal on the carrier is of particular *** this work,we have studied the nucleation growth of small co clusters(up to co_(6))on the surface of ceO_(2)(110)using density functional theory,from which a stable loaded co/ceO_(2)(110)structure was selected to investigate the methane activation *** the relatively small size of the selected co clusters,the obtained co_(x)/ceO_(2)(110)exhibits interesting *** optimized co_(5)/ceO_(2)(110)structure was selected as the optimal structure to study the activation mechanism of methane due to its competitive electronic structure,adsorption energy and binding *** energy barriers for the stepwise dissociation of methane to form cH3^(*),cH2^(*),cH^(*),and c^(*)radical fragments are 0.44,0.55,0.31,and 1.20 eV,respectively,indicating that cH^(*)dissociative dehydrogenation is the rate-determining step for the system under investigation *** fundamental study of metal-support interactions based on co growth on the ceO_(2)(110)surface contributes to the understanding of the essence of co/ceO_(2) catalysts with promising catalytic *** provides theoretical guidance for better designing the optimal co/ceO_(2) catalyst for tailored catalytic reactions.

关键词： co cluster growth ce-based catalysts Methane activation DFT