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Numerical simulation on sand sedimentation and erosion characteristics around HDPE sheet sand barrier under different wind angles

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Journal of Mountain Science 2024年第2期21卷 538-554页

作者： ZHANG Kai ZHANG Peili ZHANG hailong TIAN Jianjin WANG Zhenghui XIAO Jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion dynamics.This study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier changes.Specifically,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind side.If the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle expands.The windproof efficiency correlates directly with this angle but inversely with the wind’s speed.Notably,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind side.As the angle grows,the barrier’s windproof efficiency improves,extending its protective reach.Sedimentation is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by 14.8H.As the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.

关键词： Multi-wind direction HDPE sheet sand barrier Numerical simulation Windproof efficiency Sedimentation erosion

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Fabrication,Microstructure and Mechanical Properties of in situ GNPs Reinforced Magnesium Matrix Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 561-569页

作者： Peitang Zhao Xuejian Li hailong Shi Xiaoshi Hu Chunlei Zhang Chao Xu Xiaojun Wang The 38th Research Institute of China Electronics Technology Group Corporation Hefei 230088China National Key Laboratory of Precision Hot Processing of Metal Harbin Institute of TechnologyHarbin 150001China

Graphene reinforced magnesium matrix composites have wide applications in automotive,electronics,aerospace and military fields due to the fascinating mechanical properties.However,it is difficult to realize the high strength and ductility simultaneously.In this work,the in situ liquid-state method was utilized to prepare GNPs/Mg6Zn composites via CO_(2)/Mg chemical reaction.Tensile strength of the GNPs/Mg6Zn composites was improved with increasing content of the GNPs.Meantime,the composites also exhibit a notable plastic deformation stage,and especially the ductility of 0.12 GNPs/Mg6Zn composites reaches 27.6%.Therefore,this novel preparation method has great potential application for fabricating Mg matrix composites with high strength and high ductility.

关键词： Magnesium matrix composite In situ composite Microstructure Mechanical properties

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Improved damage tolerance and oxidation resistance of (Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC by introducing chopped carbon fibers

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Journal of Advanced Ceramics 2024年第1期13卷 101-112页

作者： Feilong Huang hailong Wang Cheng Fang Mingliang Li Gang Shao Jinpeng Zhu Yanchun Zhou School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

High-entropy diborides(HEBs)are considered as promising high-temperature structure materials owing to their high melting point and excellent thermal stability.However,the intrinsic brittleness is the main obstacle that seriously limits their practical applications.To overcome with this obstacle,carbon fibers(Cf)with outstanding mechanical properties are used in the present work as a first attempt to improve the damage tolerance of HEBs.The as-prepared C_(f)/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC composite(C_(f)/HEB–SiC)shows high relative density(97.9%)and good mechanical properties with flexural strength of 411±3 MPa and fracture toughness of 6.15±0.11 MPa·m^(1/2).More importantly,the damage tolerance parameter(Dt)has increased from 0.10 m^(1/2) for HEB–SiC to 0.29 m^(1/2) for C_(f)/HEB–SiC.Through microstructural analysis and Vickers indentation of the composite,the toughening mechanisms are disclosed.The carbon fibers coated with carbon coatings demonstrate unique capacity for prolonging the crack propagation path,which promotes the reliability of the composite effectively.Moreover,the C_(f)/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC composite also exhibits good static oxidation resistance in the temperature range of 1100–1500℃in air due to the formation of the protective oxide layer constituting of multicomponent oxides(Zr)HfTiO4 and(Zr)Hf_(6)Ta_(2)O_(17) embedded in a continuous SiO_(2) glass.These results are promising,and this primary work can be used as a reference to the synthesis of C_(f)/HEBs for thermal protection materials under hightemperature serving conditions.

关键词： high-entropy ceramics carbon fibers(Cf) toughening mechanisms oxidation resistance

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Catalytic effect in lithium metal batteries: From heterogeneous catalyst to homogenous catalyst

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Journal of Energy Chemistry 2024年第3期90卷 305-326,I0008页

作者： Haining Fan Xuan-Wen Gao hailong Xu Yichun Ding Shi-Xue Dou Wen-Bin Luo School of Fashion and Textiles The Hong Kong Polytechnic UniversityHong Kong 100872China Institute for Energy Electrochemistry and Urban Mines Metallurgy School of MetallurgyNortheastern UniversityShenyang 110819LiaoningChina Institute of Energy Materials Science University of Shanghai for Science and TechnologyShanghai 200000China State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710000ShaanxiChina

Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-electron,multi-step redox reaction associated with sluggish conversion kinetics,subsequently giving rise to a cascade of parasitic issues.In order to smooth reaction kinetics,catalysts are widely introduced to accelerate reaction rate via modulating the energy barrier.Over past decades,a large amount of research has been devoted to the catalyst design and catalytic mechanism exploration,and thus the great progress in electrochemical performance has been realized.Therefore,it is necessary to make a comprehensive review toward key progress in catalyst design and future development pathway.In this review,the basic mechanism of lithium metal batteries is provided along with corresponding advantages and existing challenges detailly described.The main catalysts employed to accelerate cathode reaction with emphasis on their catalytic mechanism are summarized as well.Finally,the rational design and innovative direction toward efficient catalysts are suggested for future application in metal-sulfur/gas battery and beyond.This review is expected to drive and benefit future research on rational catalyst design with multi-parameter synergistic impacts on the activity and stability of next-generation metal battery,thus opening new avenue for sustainable solution to climate change,energy and environmental issues,and the potential industrial economy.

关键词： Energy storage and conversion Metal battery Sulfur battery Air battery Catalytic effect Heterogeneous catalyst Homogeneous catalyst

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Taming heat with tiny pressure

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The Innovation 2024年第2期5卷 70-78页

作者： Kun Zhang Zhe Zhang hailong Pan Haoyu Wang Xueting Zhao Ji Qi Zhao Zhang Ruiqi Song Chenyang Yu Biaohong Huang Xujing Li Huaican Chen Wen Yin Changlong tan Weijin Hu Michael Wüubbenhorst Jiangshui Luo Dehong Yu Zhidong Zhang Bing Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Laboratory for Soft Matter and Biophysics Department of Physics and AstronomyKU Leuven3001 LeuvenBelgium Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China College of Materials Science and Engineering Sichuan UniversityChengdu 610064China School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150080China Australian Nuclear Science and Technology Organisation Lucas HeightsNSW 2234Australia

Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics.Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions;however,these strategies are less cost-effective and unscalable.Here,we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol(AMP)to realize an affordable,easily manageable approach for thermal energy recycling.The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal,resulting in a substantial temperature increase of 48 K within 20 s.Furthermore,we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion effi-ciency of383.Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.

关键词： illumination thermal rational

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Numerical simulation of flow field deposition and erosion characteristics around bridge-road transition section

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Journal of Mountain Science 2024年第5期21卷 1491-1508页

作者： ZHANG Kai WANG Zhenghui WANG Tao TIAN Jianjin ZHANG hailong LIU Yonghe College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind-sand flow generates erosion and deposition around obstacles such as bridges and roadbeds, resulting in sand damage and endangering railway systems in sandy regions. Previous studies have mainly focused on the flow field around roadbeds, overlooking detailed examinations of sand particle erosion and deposition patterns near bridges and roadbeds. This study employs numerical simulations to analyze the influence of varying heights and wind speeds on sand deposition and erosion characteristics at different locations: the bridge-road transition section(side piers), middle piers, and roadbeds. The results show that the side piers, experience greater accumulation than the middle piers. Similarly, the leeward side of the roadbed witnesses more deposition compared to the windward side. Another finding reveals a reduced sand deposition length as the vertical profile, in alignment with the wind direction, moves further from the bridge abutments at the same clearance height. As wind speeds rise, there’s a decline in sand deposition and a marked increase in erosion around the side piers, middle piers and roadbeds. In conclusion, a bridge clearance that’s too low can cause intense sand damage near the side piers, while an extremely high roadbed may lead to extensive surface sand deposition. Hence, railway bridges in areas prone to sandy winds should strike a balance in clearance height. This research provides valuable guidelines for determining the most suitable bridge and roadbed heights in regions affected by wind and sand.

关键词： Sandstorm Flow field Bridge-road transition section Sedimentation erosion Numerical simulation

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Realization of Low in-Band Harmonic for Compact 6–18-GHz T/R Module Under TX-Mode Operation

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Chinese Journal of Electronics 2024年第2期33卷 380-384页

作者： Jinming LAI Zhiyou LI Chaojie WANG hailong WANG Xiaohua MA School of Microelectronics Xidian University CETC 29th Research Institute

Wideband high power amplifier(PA) with poor harmonic suppression will degrade the performance of the active electronically scanned array(AESA) due to its harmonic products falling into the operating bandwidth of a wideband T/R module. In view of this, a compact reconfigurable harmonic suppress circuit(HSC) is proposed to achieve low in-band harmonic for compact T/R module with multiple octaves under TX-mode operation. The HSC consists of eight microstrip resonant stubs with high impedance and multiple p-i-n switches. By controlling the p-i-n switches, the HSC can work in three states. When six of the used p-i-n switches are “ON” state, the corresponding microstrip resonant stubs are loaded onto the 50 Ω transmission line, which performs a bandstop filter(BSF). For verification, the HSC with bandwidth of 12–15 GHz/15–18 GHz is designed to apply to a 6–18 GHz T/R module. As a result, the second harmonic of 6–9 GHz transmitting signal can be suppressed below 32 d Bc when compared to the PA's fundamental output. While the p-i-n switches are “OFF” state, the HSC is almost the same as a 50 Ω transmission line, which will have a little effect on the 9–18 GHz transmitting signal. The measurement results approximately agree with the calculated results and simulated results, which demonstrate the validity of the proposed HSC.

关键词： GaN power amplifier (PA) Harmonic suppression Low in-band harmonic p-i-n switch Wideband T/R module

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Effect of coir geotextile and geocell on ephemeral gully erosion in the Mollisol region of Northeast China

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Journal of Arid Land 2024年第4期16卷 518-530页

作者： QIN Xijin SUN Yiqiu ZHANG Yan GUAN Yinghui WU hailong WANG Xinyu WANG Guangyu School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083China Tianjin Eco-Environmental Protection Design&Research Institute Tianjin 300042China College of Environmental Science and Safety Engineering Tianjin University of TechnologyTianjin 300384China Faculty of Forestry University of British Columbia2424 Main MallVancouver BC V6T 1Z4Canada

The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion and damage during the growth stage,which brings serious problems to the restoration of grass in the early stage.Therefore,effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study.Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min,geocell and coir geotextile had a good effect on controlling EG erosion,and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82%and 73.73%–88.96%,respectively.However,when confluence intensity increased to 40 L/min,protective effect of coir geotextile decreased,and sediment yield rate increased sharply by 189.03%.When confluence intensity increased to 50 L/min,the protective effect of coir geotextile was lost.On the other hand,geocell showed that the greater the flow rate,the better the protective effect.In addition,with the increase in confluence intensity,erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill,and the protective effect was gradually weakened.In contrast,the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall.This study shows that coir geotextile and geocell can prevent EG erosion,and the effect of geocell is better than that of coir geotextile on the surface of EG.

关键词： geocell coir geotextile ephemeral gully confluence intensity erosion control

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Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

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Journal of Mountain Science 2024年第1期21卷 113-130页

作者： ZHANG Kai ZHANG hailong TIAN Jianjin QU Jianjun ZHANG Xingxin WANG Zhenghui XIAO jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

关键词： Folded linear HDPE sheet sand fence Numerical simulation Flow field characteristics Protection benefits

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Morphological and Sulfur-Isotopic Characteristics of Pyrites in the Deep Sediments from Xisha Trough,South China Sea

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Journal of Ocean University of China 2024年第1期23卷 138-148页

作者： CHANG Jingyi LIU Yujia LU hailong LU Jing’an SU Xin YE Jianliang XIE Wenwei College of Engineering Peking UniversityBeijing 100871China Beijing International Center for Gas Hydrate School of Earth and Planetary SciencesPeking UniversityBeijing 100871China School of Marine Science Nanjing University of Information Science and TechnologyNanjing 210044China MLR Key Laboratory of Marine Mineral Resources Guangzhou Marine Geological SurveyMinistry of Land and ResourcesGuangzhou 510075China School of Ocean Sciences China University of GeosciencesBeijing 100083China

Pyrite is one of the common authigenic minerals in marine sediments.Previous studies have shown that the morphological and isotopic characteristics of pyrite are closely related to the geochemical environment where it is formed.To better understand the for-mation mechanism of authigenic pyrite,we analyzed the isotopic composition,morphology,and distribution of pyrite in the sediment at 500m below the seafloor from Xisha Trough,South China Sea.Mineral morphologies were observed by scanning electron micros-copy and Raman spectrography.X-Ray computed tomography was applied to measure the particle size of pyrite.The size of pyrite crystals in the matrix sediment mainly ranged between 25 and 65µm(av.ca.40µm),although crystals were larger(av.ca.50μm)in the veins.The pyrites had a fine-grained truncated octahedral shape with occasionally well-developed growth steps,which implies the low growth rate and weak anaerobic oxidation of methane-sulfate reduction when pyrite was formed.Theδ^(34)S values of pyrites ranged from+20.8‰Vienna-defined Canyon Diablo Troilite(V-CDT)to+33.2‰V-CDT and from+44.8‰V-CDT to+48.9‰,which suggest two growth stages.In the first stage,with the continuous low methane flux,the pyrite possibly formed in an environment with good access to seawater.In the second stage,the pyrites mainly developed in sediment fractures and appeared in veins,probably due to the limited availability of sulfate.The less exposure of pyrite to the environment in the second stage was probably caused by sediment accumulation or perturbation.In this study,an episodic pyritization process was identified,and the paleoenvironment was reconstructed for the sediment investigated.

关键词： pyrite sulfur isotope AOM methane flux Xisha Trough South China Sea

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