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Hydraulic conductivity over a wide suction range of loess with different dry densities

Journal of Rock Mechanics and Geotechnical Engineering 2025年第1期17卷 481-492页

作者： Xiaokun Hou Shengwen Qi yan li Fangcui liu Tonglu li Hua li State Key Laboratory of lithospheric and Environmental Coevolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China University of Chinese Academy of Sciences Beijing100049China Innovation Academy for Earth Science Beijing100029China School of Civil Engineering University of A CoruñaA Coruña15071Spain Department of Geological Engineering Chang’an UniversityXi’an710054China School of Civil Engineering and Architecture Xi’an Jiaotong University of City CollegeXi’an710018China

Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil water characteristic curve (SWCC) based models and saturated hydraulic conductivity (SHC). However, the efficiency of the SWCC-based model is rarely assessed, and the influence of soil density and pore structure on HCC remains incomplete due to limited experimental data. To address this gap, this study employs an innovative filter-paper-based column method, which can measure the HCC over a wide suction range (e.g. 0−105 kPa), to capture the HCCs of both intact and compacted specimens with varying dry densities. The efficiency of two typical SWCC-based models is assessed using the measured data. Meanwhile, the mercury intrusion porosity (MIP) technique is employed to obtain the pore characteristic (i.e. pore size distribution (PSD)) and a method of predicting the HCC using the PSD data is proposed, emphasizing the dominant role of the pore structure in shaping the HCC. The results reveal that the dry density's influence on the HCC is primarily observed within the low suction range, corresponding to variations in the dominant and large pores. In the high suction range, the HCCs align along a linear trajectory when plotted in a log-log format. A notable finding is the overestimation of the HCC obtained from the SWCC-based models using the measured SHC. When the SHC is regarded as a fitting parameter, good agreement is achieved. The adjusted SHC value is typically 0-1 order of magnitude lower than the measured value, and this discrepancy diminishes as dry density increases. On the other hand, the proposed PSD-based model performs well with the measured SHC data. Caution is exercised when using the SHC to estimate the HCC for modeling water movement in partially saturated soil.

关键词： Hydraulic conductivity curve Wide suction range Dry density Pore size distribution Saturated hydraulic conductivity

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基于车辆运动约束的里程计误差在线标定方法

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中国惯性技术学报 2016年第4期24卷 485-489页

作者：李艳杨波薛亮周小刚长安大学信息学院西安710064 第二炮兵工程大学控制工程系西安710025

为了降低里程计误差对捷联惯导/里程计组合定位定向精度的影响,提出了基于车辆运动约束条件的里程计误差在线标定方法。通过对里程计标度因数误差进行建模,推导建立了航位推算的误差模型,将航位推算的速度输出沿车体横向、垂向的投影作... 详细信息

为了降低里程计误差对捷联惯导/里程计组合定位定向精度的影响,提出了基于车辆运动约束条件的里程计误差在线标定方法。通过对里程计标度因数误差进行建模,推导建立了航位推算的误差模型,将航位推算的速度输出沿车体横向、垂向的投影作为量测的一部分,将捷联惯导输出的速度、位置信息与航位推算输出的对应信息相减作为另一部分量测,通过卡尔曼滤波获得里程计标度因数误差等状态量的最优估计值,实现里程计误差的在线标定。仿真结果表明,该方法能够有效地标定出里程计标度因数误差,从而确保了捷联惯导/里程计组合定位定向的精度。

关键词：里程计误差标定车辆运动约束组合定位定向航位推算卡尔曼滤波

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Dynamic performance enhancement in Ti/Au ohmic contacts on β-Ga2O3-on-Si C substrates: evidence from pulsed measurements

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Science China(Information Sciences) 2025年第1期68卷 400-401页

作者： Chenyu liU Yibo WANG Wenhui XU Shuqi HUANG Chunxiao YU Zeyu yang Xiaole JIA Xiaoxi li Bochang li Zhengdong LUO Cizhe FANG yan liU Tiangui YOU Xin OU Genquan HAN School of Microelectronics Xidian University Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Hangzhou Institute of Technology Xidian University

Titanium/Gold （Ti/Au） metals have been widely employed as ohmic metal contacts on n+Ga2O3,exhibiting the specific contact resistance （ρc） of 10-5-10-6Ω·cm2[1].But previous studies have revealed the presence of a defective Ga2O3layer and reactive Ti-Ga2O3layer at the annealed Ti/*** an interfacial layer can afect the performance of ohmic contact,which may become more pronounced in power devices subjected to electrical stress and high-frequency ***,there have been no reports on the impact of bias stress effects and dynamic degradation of Ti/Au ohmic contacts on n+Ga2O3.

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On the existence of solutions for prescribing fractional Q-curvature problem on S~n

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Acta Mathematica Sinica,English Series 2025年

作者： yan li Zhongwei TANG College of Science China University of Petroleum(Beijing) School of Mathematical Sciences Laboratory of Mathematics and Complex Systems MOEBeijing Normal University

The aim of this paper is to investigate the existence of solutions to the prescribing fractional Q-curvature problem on S~n under some reasonable assumption of the Laplacian sign at the critical point of prescribing curvature function K. Due to the lack of compactness, we choose to return to the basic elements of variational theory and study the deformation along the flow lines. The novelty of the paper is that we obtain the existence without assuming any symmetry and periodicity on K. In addition,to overcome the loss of compactness for high-order operator problem, we need more delicate estimates with the second order cases.

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The GECAM ground search system for gamma-ray transients

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Science China(Physics,Mechanics & Astronomy) 2025年第3期68卷 161-174页

作者： Ce Cai yan-Qiu Zhang Shao-lin Xiong Ping Wang Jian-Hui li Xiao-Bo li Cheng-Kui li Yue Huang Shi-Jie Zheng li-Ming Song Shuo Xiao Qi-Bin Yi Yi Zhao Sheng-Lun Xie Rui Qiao yan-Qi Du Zhi-Wei Guo Wang-Chen Xue Chao Zheng Jia-Cong liu Chen-Wei Wang Wen-Jun Tan Yue Wang Jin-Peng Zhang Chao-yang li Guo-Ying Zhao Xiao-Yun Zhao Xiao-Lu Zhang Zhen Zhang Wen-Xi Peng Xiang Ma Jing-yan Shi Dong-Ya Guo Jin Wang Xin-Qiao li Xiang-yang Wen Zheng-Hua An Fan Zhang College of Physics and Hebei Key Laboratory of Photophysics Research and Application Hebei Normal UniversityShijiazhuang050024China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049China University of Chinese Academy of Sciences Beijing100049China School of Physics and Electronic Science Guizhou Normal UniversityGuiyang550001China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang550001China School of Physics and Optoelectronics Xiangtan UniversityXiangtan411105China School of Computer and Information Dezhou UniversityDezhou253023China Institute of Astrophysics Central China Normal UniversityWuhan430079China

In the era of time-domain,multi-messenger astronomy,the detection of transient events on the high-energy electromagnetic sky has become more important than *** gravitational wave high-energy electromagnetic counterpart all-sky monitor(GECAM)is a dedicated mission to monitor gamma-ray transients,launched in December,2020.A real-time on-board trigger and location software,using the traditional signal-to-noise ratio(SNR)method for blind search,is constrained to relatively bright signals due to the limitations in on-board computing resources and the need for real-time *** this work,we developed a ground-based pipeline for GECAM to search for various transients,especially for weak bursts missed by on-board *** pipeline includes both automatic and manual mode,offering options for blind search and targeted *** targeted search is specifically designed to search for interesting weak bursts,such as gravitational wave-associated gamma-ray bursts(GRBs).From the ground search of the data in the first year,GECAM has been triggered by 54 GRBs and other transients,including soft gamma-ray repeaters,X-ray binaries,solar flares,terrestrial gamma-ray *** report the properties of each type of triggers,such as trigger time and light *** this search pipeline and assuming a soft Band spectrum,the GRB detection sensitivity of GECAM is increased to about 1.1×10^(-8)erg cm^(-2)s^(-1)(10-1000 ke V,burst duration of 20 s).These results demonstrate that the GECAM ground search system(both blind search and targeted search)is a versatile pipeline to recover true astrophysical signals which were too weak to be found in the on-board search.

关键词： gamma-ray sources gravitational waves data analysis gamma-ray telescopes

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Concurrently Boosting Activity and Stability of Oxygen Reduction Reaction Catalysts via Judiciously Crafting Fe-Mn Dual Atoms for Fuel Cells

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Nano-Micro Letters 2025年第4期17卷 275-289页

作者： Lei Zhang Yuchen Dong Lubing li Yuchuan Shi yan Zhang liting Wei Chung-li Dong Zhiqun lin Jinzhan Su International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China Department of Physics Tamkang UniversityNew Taipei CityTaiwan 25137People’s Republic of China Department of Chemical and Biomolecular Engineering National University of SingaporeEngineering Drive 4Singapore 117585Singapore

The ability to unlock the interplay between the activity and stability of oxygen reduction reaction(ORR)represents an important endeavor toward creating robust ORR catalysts for efficient fuel ***,we report an effective strategy to concurrent enhance the activity and stability of ORR catalysts via constructing atomically dispersed Fe-Mn dualmetal sites on N-doped carbon(denoted(FeMn-DA)-N-C)for both anion-exchange membrane fuel cells(AEMFC)and proton exchange membrane fuel cells(PEMFC).The(FeMn-DA)-N-C catalysts possess ample dual-metal atoms consisting of adjacent Fe-N_(4)and Mn-N_(4)sites on the carbon surface,yielded via a facile doping-adsorption-pyrolysis *** introduction of Mn carries several advantageous attributes:increasing the number of active sites,effectively anchoring Fe due to effective electron transfer to Mn(revealed by X-ray absorption spectroscopy and density-functional theory(DFT),thus preventing the aggregation of Fe),and effectively circumventing the occurrence of Fenton reaction,thus reducing the consumption of ***(FeMn-DA)-N-C catalysts showcase half-wave potentials of 0.92 and 0.82 V in 0.1 M KOH and 0.1 M HClO_(4),respectively,as well as outstanding *** manifested by DFT calculations,the introduction of Mn affects the electronic structure of Fe,down-shifts the d-band Fe active center,accelerates the desorption of OH groups,and creates higher limiting *** AEMFC and PEMFC with(FeMn-DA)-N-C as the cathode catalyst display high power densities of 1060 and 746 mW cm^(-2),respectively,underscoring their promising potential for practical *** study highlights the robustness of designing Fe-containing dual-atom ORR catalysts to promote both activity and stability for energy conversion and storage materials and devices.

关键词： Doping-adsorption-pyrolysis Dual-atom catalysts Oxygen reduction reaction Fuel cells

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The Stereocomplex Crystallites Improve the Stability of Biodegradable Poly(L-lactic acid)/Poly(D-lactic acid)Melt-Blown Nonwovens

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Chinese Journal of Polymer Science 2025年第2期43卷 368-379页

作者： Jin-Shuo Yu Yue-Wei Huan Hong-Wei Pan Zhi-Gang liu yan Zhao Zhi-Yong Tan Jun-Jia Bian Hui-li yang Hui-liang Zhang Key Laboratory of Polymer Ecomaterials Chinese Academy of SciencesChangchun Institute of Applied ChemistryChangchun130022China College of Material and Engineering School of Chemical EngineeringEngineering Research Center of Synthetic Resin and Special FiberMinistry of EducationChangchun University of TechnologyChangchun130012China Shandong Fufeng Fermentation Co. Ltd.Shandong276600China National Engineering Research Center of Corn Deep Processing Jilin COFCO Biochemistry Co.Ltd.Changchun130033China

Poly(lactic acid)(PLA)is a biodegradable and eco-friendly polymer that is increasingly being incorporated into various applications in contemporary ***,the limited stability of PLA-based products remains a significant challenge for their broader use in various *** this study,poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)melt-blown nonwovens were prepared by melt *** structure,thermal properties,thermal stability,biodegradability and crystalline morphology of the melt-blown nonwovens were *** and WAXD confirmed the formation of stereocomplex(SC)crystallites in the PLLA *** storage modulus(G′),loss modulus(G″),and complex viscosity(∣η^(*)∣)of the PLLA/PDLA blend increased with an increase in SC crystallite *** thermal degradation temperatures of PLLA/PDLA melt-blown nonwovens increased with the incorporation of SC crystallites,and the maximum rate of decomposition increased to 385.5℃,thus enhancing the thermal *** with neat PLLA melt-blown nonwovens,the hydrophobicity of PLLA/PDLA melt-blown nonwovens was improved,and WCA increased to 139.7°.The SC crystallites were more resistant to degradation by proteinase K compared to neat ***,the degradation rate of PLLA/PDLA melt-blown nonwovens remained at a high *** work provides an effective strategy to obtain high-performance PLLA melt-blown nonwovens.

关键词： PLLA PDLA Melt-blown nonwovens Stereocomplex crystallites Thermal stability Enzymatic degradation

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Carbon Dots-Modified Hollow Mesoporous Photonic Crystal Materials for Sensitivityand Selectivity-Enhanced Sensing of Chloroform Vapor

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Nano-Micro Letters 2025年第4期17卷 381-398页

作者： Junchen liu Ji liu Zhipeng li liupeng Zhao Tianshuang Wang Xu yan Fangmeng liu Xiaomin li Qin li Peng Sun Geyu Lu Dongyuan Zhao State Laboratory On Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012People’s Republic of China Department of Chemistry and Laboratory of Advanced Materials Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsState Key Laboratory of Molecular Engineering of PolymersCollaborative Innovation Center of Chemistry for Energy Materials(2011-iChEM)College of Chemistry and MaterialsFudan UniversityShanghaiPeople’s Republic of China School of Engineering and Built Environment Griffith UniversityNathanQLD 4111Australia

Chloroform and other volatile organic pollutants have garnered widespread attention from the public and researchers,because of their potential harm to the respiratory system,nervous system,skin,and ***,research on chloroform vapor sensing is still in its early stages,primarily due to the lack of specific recognition *** we report a mesoporous photonic crystal sensor incorporating carbon dots-based nanoreceptor(HMSS@CDs-PCs)for enhanced chloroform *** colloidal PC packed with hollow mesoporous silica spheres provides an interconnected ordered macro-meso-hierarchical porous structure,ideal for rapid gas sensing utilizing the photonic bandgap shift as the readout *** as-synthesized CDs with pyridinic-N-oxide functional groups adsorbed in the hollow mesoporous silica spheres are found to not only serve as the chloroform adsorption sites,but also a molecular glue that prevents crack formation in the colloidal *** sensitivity of HMSS@CDs-PCs sensor is 0.79 nm ppm^(-1)and an impressively low limit of detection is 3.22 ppm,which are the best reported values in fast-response chloroform vapor sensor without multi-signal *** positive response time is 7.5 s and the negative response time 9 ***,relatively stable sensing can be maintained within a relative humidity of 20%-85%RH and temperature of 25-55℃.This study demonstrates that HMSS@CDs-PCs sensors have practical application potential in indoor and outdoor chloroform vapor detection.

关键词： Carbon dots Photonic crystal sensors Sensitivity-enhanced sensing Selectivity-enhanced sensing Chloroform vapor sensing

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Hierarchical Polyimide Nonwoven Fabric with Ultralow-Reflectivity Electromagnetic Interference Shielding and High-Temperature Resistant Infrared Stealth Performance

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Nano-Micro Letters 2025年第4期17卷 111-129页

作者： Xinwei Tang Yezi Lu Shuangshuang li Mingyang Zhu Zixuan Wang yan li Zaiyin Hu Penglun Zheng Zicheng Wang Tianxi liu The Key Laboratory of Synthetic and Biological Colloids Ministry of EducationSchool of Chemical and Material EngineeringInternational Joint Research Laboratory for Nano Energy CompositesJiangnan UniversityWuxi 214122JiangsuPeople’s Republic of China Jiangsu Ferrotec Semiconductor Technology Co. Ltd.Yancheng 214000JiangsuPeople’s Republic of China Guizhou Aerospace Wujiang Electro-Mechanical Equipment Co. Ltd.No.20-5Dalian Road Aerospace Industrial ParkHuichuan DistrictZunyi City 563000GuizhouPeople’s Republic of China Civil Aircraft Fire Science and Safety Engineering Key Laboratory of Sichuan Province College of Civil Aviation Safety EngineeringCivil Aviation Flight University of ChinaGuanghan 618307SichuanPeople’s Republic of China

Designing and fabricating a compatible low-reflectivity electromagnetic interference(EMI)shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of ***,a hierarchical polyimide(PI)nonwoven fabric is fabricated by alkali treatment,in-situ growth of magnetic particles and"self-activated"electroless Ag plating ***,the hierarchical impedance matching can be constructed by systematically assembling Fe_(3)O_(4)/Ag-loaded PI nonwoven fabric(PFA)and pure Ag-coated PI nonwoven fabric(PA),endowing it with an ultralowreflectivity EMI shielding *** addition,thermal insulation of fluffy three-dimensional(3D)space structure in PFA and low infrared emissivity of PA originated from Ag plating bring an excellent infrared stealth *** importantly,the strong bonding interaction between Fe_(3)O_(4),Ag,and PI fiber improves thermal stability in EMI shielding and high-temperature resistant infrared stealth *** excellent comprehensive performance makes it promising for military tents to protect internal equipment from electromagnetic interference stemmed from adjacent equipment and/or enemy,and inhibit external infrared detection.

关键词： Polyimide Electromagnetic interference shielding Low reflectivity Infrared stealth Compatibility

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Failure mechanisms of AlGaN/GaN HEMTs irradiated by high-energy heavy ions with and without bias

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Nuclear Science and Techniques 2025年第1期36卷 49-58页

作者： Pei-Pei Hu li-Jun Xu Sheng-Xia Zhang Peng-Fei Zhai ling Lv Xiao-Yu yan Zong-Zhen li yan-Rong Cao Xue-Feng Zheng Jian Zeng Yuan He Jie liu Institute of Modern Physics Chinese Academy of Sciences(CAS)Lanzhou 730000China Key Laboratory of Wide Band‑gap Semiconductor Materials Ministry of EducationXidian UniversityXi’an 710071China University of Chinese Academy of Sciences(UCAS) Beijing 100049China

Gallium nitride(GaN)-based devices have significant potential for space ***,the mechanisms of radiation damage to the device,particularly from strong ionizing radiation,remains *** study investigates the effects of radiation on p-gate AlGaN/GaN high-electron-mobility transistors(HEMTs).Under a high voltage,the HEMT leakage current increased sharply and was accompanied by a rapid increase in power density that caused"thermal burnout"of the *** addition,a burnout signature appeared on the surface of the burned devices,proving that a single-event burnout effect ***,degradation,including an increase in the on-resistance and a decrease in the breakdown voltage,was observed in devices irradiated with high-energy heavy ions and without *** latent tracks induced by heavy ions penetrated the heterojunction interface and extended into the GaN ***,a new type of N_(2)bubble defect was discovered inside the tracks using Fresnel *** accumulation of N_(2)bubbles in the heterojunction and buffer layers is more likely to cause leakage and *** study indicates that electrical stress accelerates the failure rate and that improving heat dissipation is an effective reinforcement method for GaN-based devices.

关键词： GaN HEMTs Heavy ions Single-event burnout Latent tracks Degradation

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