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Sliding and damming properties of granular debris with different geometric configurations and grain size distributions

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Journal of Mountain Science 2024年第3期21卷 932-951页

作者： HE Ligeng tan Longmeng YANG xingguo ZHOU Jiawen LIAO Haimei College of Civil Engineering Guizhou UniversityGuiyang 550025China Quality Supervision and Law Enforcement Detachment of Guizhou province Traffic Construction Engineering Guiyang 550081China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

Granular debris plays a significant role in determining damming deposit characteristics. An indepth understanding of how variations in grain size distribution(GSD) and geometric configurations impact the behavior of granular debris during the occurrence of granular debris is essential for precise assessment and effective mitigation of landslide hazards in mountainous terrains. This research aims to investigate the impact of GSD and geometric configurations on sliding and damming properties through laboratory experiments. The geometric configurations were categorized into three categories based on the spatial distribution of maximum volume: located at the front(Type Ⅰ), middle(Type Ⅱ), and rear(Type Ⅲ) of the granular debris. Our experimental findings highlight that the sliding and damming processes primarily depend on the interaction among the geometric configuration, grain size, and GSD in granular debris. Different sliding and damming mechanisms across various geometric configurations induce variability in motion parameters and deposition patterns. For Type Ⅰ configurations, the front debris functions as the critical and primary driving component, with energy dissipation primarily occurring through inter-grain interactions. In contrast, Type Ⅱ configurations feature the middle debris as the dominant driving component, experiencing hindrance from the front debris and propulsion from the rear, leading to complex alterations in sliding motion. Here, energy dissipation arises from a combination of inter-grain and grain-substrate interactions. Lastly, in Type Ⅲ configurations, both the middle and rear debris serve as the main driving components, with the rear sliding debris impeded by the front. In this case, energy dissipation predominantly results from grainsubstrate interaction. Moreover, we have quantitatively demonstrated that the inverse grading in damming deposits, where coarse grain moves upward and fine grain moves downward, is primarily caused by grain sortin

关键词： Landslide dam Geometric configuration Energy dissipation Inverse grading physical experiment

Effect of drying cracks on swelling and self-healing of bentonite-sand blocks used as engineered barriers for radioactive waste disposal

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1776-1787页

作者： Yu tan Guangping Zhou Huyuan Zhang xiaoya Li ping Liu School of Civil Engineering and Mechanics Lanzhou UniversityLanzhou730000China Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University) Ministry of EducationLanzhou730000China Civil and Environmental Engineering University of Wisconsin-MadisonWI53706USA

Experiments were conducted to evaluate the healing of drying cracks in air-dried bentonite-sand blocks after hydration and swelling in groundwater,providing justifications to simplify the protection of blocks prior to installation in a high-level radioactive waste *** groundwater was prepared to represent the geochemistry of Beishan groundwater,and was used to hydrate the blocks during the swelling pressure and swelling strain measurements,as Beishan is the most promising site for China's *** of the surface cracks was recorded by photography,and healing of the internal cracks was visualized by CT images and hydraulic conductivity of air-dried *** results indicate that the maximum swelling pressure and swelling strain are primarily affected by the geochemistry of Beishan groundwater,but not affected by the drying *** maximum swelling pressure and swelling strain of air-dried blocks are comparable to or even higher than the pressure and strain of fresh *** maximum swelling pressure measured in strong(*** ion strength)Beishan groundwater was 44%of the pressure measured in deionized(DI)water,and the maximum swelling strain was reduced to 23%of the strain measured in DI ***,the remained swelling of the blocks hydrated in strong Beishan groundwater was sufficient to heal the surface and internal drying cracks,as demonstrated by the pictures of surface cracks and CT *** hydraulic conductivity of the air-dried block permeated with strong groundwater was comparable(3.7×higher)to the hydraulic conductivity of the fresh block,indicating the self-healing of drying cracks after hydration and swelling in groundwater.A simplified method of protecting the block with plastic wraps before installation is recommended,since the remained swelling of the block hydrated in Beishan groundwater is sufficient to heal the drying cracks.

关键词： Beishan groundwater chemistry Bentonite buffer Drying cracks High-level radioactive waste(HLW) Self-healing Swelling

Operational requirements analysis method based on question answering of WEKG

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Journal of Systems Engineering and Electronics 2024年第2期35卷 386-395页

作者： ZHANG Zhiwei DOU Yajie xU xiangqian MA Yufeng JIANG Jiang tan Yuejin College of Systems Engineering National University of Defense TechnologyChangsha 410073China

The weapon and equipment operational requirement analysis(WEORA) is a necessary condition to win a future war,among which the acquisition of knowledge about weapons and equipment is a great challenge. The main challenge is that the existing weapons and equipment data fails to carry out structured knowledge representation, and knowledge navigation based on natural language cannot efficiently support the WEORA. To solve above problem, this research proposes a method based on question answering(QA) of weapons and equipment knowledge graph(WEKG) to construct and navigate the knowledge related to weapons and equipment in the WEORA. This method firstly constructs the WEKG, and builds a neutral network-based QA system over the WEKG by means of semantic parsing for knowledge navigation. Finally, the method is evaluated and a chatbot on the QA system is developed for the WEORA. Our proposed method has good performance in the accuracy and efficiency of searching target knowledge, and can well assist the WEORA.

关键词： operational requirement analysis weapons and equipment knowledge graph(WEKG) question answering(QA) neutral network

Effects of thawing-induced softening on fracture behaviors of frozen rock

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 979-989页

作者： Ting Wang Hailiang Jia Qiang Sun xianjun tan Liyun tang College of Geology and Environment Xi’an University of Science and TechnologyXi’an710054China College of Architecture and Civil Engineering Xi’an University of Science and TechnologyXi’an710054China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430064China

Due to the presence of ice and unfrozen water in pores of frozen rock,the rock fracture behaviors are susceptible to *** this study,the potential thawing-induced softening effects on the fracture behaviors of frozen rock is evaluated by testing the tension fracture toughness(KIC)of frozen rock at different temperatures(i.e.-20℃,-15℃,-12℃,-10℃,-8℃,-6℃,-4℃,-2℃,and 0℃).Acoustic emission(AE)and digital image correlation(DIC)methods are utilized to analyze the microcrack propagation during *** melting of pore ice is measured using nuclear magnetic resonance(NMR)*** results indicate that:(1)The KIC of frozen rock decreases moderately between-20℃ and-4℃,and rapidly between-4℃ and 0℃.(2)At-20℃ to-4℃,the fracturing process,deduced from the DIC results at the notch tip,exhibits three stages:elastic deformation,microcrack propagation and microcrack ***,at-4℃e0℃,only the latter two stages are observed.(3)At-4℃e0℃,the AE activities during fracturing are less than that at-20℃ to-4℃,while more small events are reported.(4)The NMR results demonstrate a reverse variation trend in pore ice content with increasing temperature,that is,a moderate decrease is followed by a sharp decrease and-4℃ is exactly the critical ***,we interpret the thawing-induced softening effect by linking the evolution in microscopic structure of frozen rock with its macroscopic fracture behaviors as follow:from-20℃ to-4℃,the thickening of the unfrozen water film diminishes the cementation strength between ice and rock skeleton,leading to the decrease in fracture ***-4℃ to 0℃,the cementation effect of ice almost vanishes,and the filling effect of pore ice is reduced significantly,which facilitates microcrack propagation and thus the easier fracture of frozen rocks.

关键词： Frozen sandstone Different thawing temperature Fracture toughness Microcrack propagation process Unfrozen water content

Type Synthesis of Self-Alignment parallel Ankle Rehabilitation Robot with Suitable passive Degrees of Freedom

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 160-175页

作者： Ya Liu Wenjuan Lu Dabao Fan Weijian tan Bo Hu Daxing Zeng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China School of Mechanical Engineering Dongguan University of TechnologyDongguan 523808China Dongguan Engineering Technology Research Center for parallel Robot Dongguan 523808China The DGUT Innovation Center of Robotics and Intelligent Equipment Dongguan 523808China

The current parallel ankle rehabilitation robot(ARR)suffers from the problem of difficult real-time alignment of the human-robot joint center of rotation,which may lead to secondary injuries to the *** study investigates type synthesis of a parallel self-alignment ankle rehabilitation robot(pSAARR)based on the kinematic characteristics of ankle joint rotation center drift from the perspective of introducing"suitable passive degrees of freedom(DOF)"with a suitable number and ***,the self-alignment principle of parallel ARR was proposed by deriving conditions for transforming a human-robot closed chain(HRCC)formed by an ARR and human body into a kinematic suitable constrained system and introducing conditions of"decoupled"and"less limb".Second,the relationship between the self-alignment principle and actuation wrenches(twists)of pSAARR was analyzed with the velocity Jacobian matrix as a"bridge".Subsequently,the type synthesis conditions of pSAARR were ***,a pSAARR synthesis method was proposed based on the screw theory and type of pSAARR synthesis ***,an HRCC kinematic model was established to verify the self-alignment capability of the *** this study,93 types of pSAARR limb structures were synthesized and the self-alignment capability of a human-robot joint axis was verified through kinematic analysis,which provides a theoretical basis for the design of such an ARR.

关键词： Ankle rehabilitation robot Self-alignment parallel mechanism Type synthesis Screw theory

High performance photodetector based on few-layer MoTe_(2)/CdS_(0.42)Se_(0.58) flake heterojunction

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Frontiers of physics 2024年第4期19卷 91-101页

作者： Ran Ma Qiuhong tan peizhi Yang Yingkai Liu Qianjin Wang College of physics and Electronic Information Yunnan Normal UniversityKunming 650500China Yunnan provincial Key Laboratory for photoelectric Information Technology Yunnan Normal UniversityKunming 650500China Key Laboratory of Advanced Technique&preparation for Renewable Energy Materials Ministry of EducationYunnan Normal UniversityKunming 650500China

Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance ***,their relatively low responsivities,current on/off ratios and response speeds have hindered their widespread ***,we fabricated a high-performance photodetector based on few-layer MoTe_(2) and CdS_(0.42)Se_(0.58) flake *** photodetector exhibited a high responsivity of 7221 A/W,a large current on/off ratio of 1.73×10^(4),a fast response speed of 90/120μs,external quantum efficiency(EQE)reaching up to 1.52×10^(6)%and detectivity(D*)reaching up to 1.67×10^(15) *** excellent performance of the heterojunction photodetector was analyzed by a photocurrent mapping test and first-principle ***,the visible light imaging function was successfully attained on the MoTe_(2)/CdS_(0.42)Se_(0.58) photodetectors,indicating that the device had practical imaging application *** findings provide a reference for the design of ultrahighperformance MoTe_(2)-based photodetectors.

关键词： photodetector MoTe_(2) heterojunction visible light imaging first-principles calculations

Metallogenesis of the Baidi Au-Sb deposit, southwest Guizhou province, China: mineralogical and geochemical evidence from sulfur-bearing minerals

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Acta Geochimica 2024年第2期43卷 199-213页

作者： Jun Yan Yong xia Qinping tan Zhuojun xie Guosong Ji State KeyLaboratory of Ore Deposit Geochemistry Institute of GeochemistryChineseAcademy of SciencesGuiyang 550081China Guizhou InstituteofTechnology Guiyang550003China No.102 GeologicalTeam Guizhou Bureau of Geologyand Mineral Exploration&DevelopmentZunyi563003China

The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou province, *** studies have focused on individual ores, but have not combined them to identify their paragenetic mechanism or metallogenic regularity. Therefore, we used field investigations, microscopic observations, and in situ analyses to identify the spatial distribution, mineral paragenesis, compositional evolution, and metallogenic material sources of the ore bodies. We also determined the Au and Sb paragenetic characteristics and the metallogenesis of the deposit. The main Au-bearing minerals in the deposit were early(Apy1–2) and late(Apy3) stage arsenopyrites, as well as pre-mineralization(py1), mineralization(py2–5), and late mineralization(py6–7) stage pyrites. The main Sb-bearing minerals were stibnite(Snt), skinnerite, bournonite,and valentinite. The minerals formed in the order of py1,py2–3 + Apy1, py4–5 + Apy2, Snt, and py6–7 + *** δ34S values of the arsenopyrites and pyrites ranged from-5 to 5‰, while those of stibnite were mostly less than-5‰ in the later mineralization stages. Sulfur was provided by deep magmatic hydrothermal fluids, but sedimentary sulfur was added in the later stages. Moreover,the trace elemental contents fluctuated and eventually became similar to those of the sedimentary strata. By comprehensively considering the ores along with the geological characteristics of the deposit, we determined that deep magma provided the Au during ore formation. Later tectonic changes provided Sb from the sedimentary strata,which precipitated along fault expansion areas and produced Au and Sb paragenesis.

关键词： Au-Sb mineralization Arsenopyrite pyrite Stibnite Metallogenetic process

Effect of temperature and time on the precipitation ofκ-carbides in Fe-28Mn-10Al-0.8C low-density steels:Aging mechanism and its impact on material properties

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2189-2198页

作者： Yulin Gao Min Zhang Rui Wang xinxin Zhang Zhunli tan xiaoyu Chong School of Mechanical Electronic and Control EngineeringMaterials Science and Engineering Research CenterBeijing Jiaotong UniversityBeijing 100044China Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

In low-density steel,κ-carbides primarily precipitate in the form of nanoscale particles within austenite ***,their precipitation within ferrite matrix grains has not been comprehensively explored,and the second-phase evolution mechanism during aging remains *** this study,the crystallographic characteristics and morphological evolution ofκ-carbides in Fe-28Mn-10Al-0.8C(wt%)low-density steel at different aging temperatures and times and the impacts of these changes on the steels’microhardness and properties were comprehensively *** different heat treatment conditions,intragranularκ-carbides exhibited various morpho-logical and crystallographic characteristics,such as acicular,spherical,and short rod-like *** the initial stage of aging,acicularκ-carbides primarily precipitated,accompanied by a few spherical carbides.κ-Carbides grew and coarsened with aging time,the spherical carbides were considerably reduced,and rod-like carbides *** hardness testing demonstrated that the material’s hardness was affected by the volume fraction,morphology,and size ofκ-*** aging at higher temperatures led to an increase in carbide size and volume fraction,resulting in a gradual rise in *** deformation,the primary mechanisms for strengthening were dislocation strengthening and second-phase *** on these findings,potential strategies for improving material strength are proposed.

关键词： low-density steel κ-carbide solution-aging treatment hardness

Emerging clinical relevance of microbiome in cancer:promising biomarkers and therapeutic targets

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protein & Cell 2024年第4期15卷 239-260页

作者： Jia-Hao Dai xi-Rong tan Han Qiao Na Liu State Key Laboratory of Oncology in South China Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and TherapyGuangdong Provincial Clinical Research Center for CancerSun Yat-sen University Cancer CenterGuangzhou 510050China

The profound influence of microbiota in cancer initiation and progression has been under the spotlight for years,leading to numerous researches on cancer microbiome entering clinical *** promising biomarkers and therapeutic targets,the critical involvement of microbiota in cancer clinical practice has been increasingly ***,recent progress in this field is *** describe the potential of tumor-associated microbiota as effective diagnostic and prognostic biomarkers,*** addition,we highlight the relationship between microbiota and the therapeutic efficacy,toxicity,or side effects of commonly utilized treatments for cancer,including chemotherapy,radiotherapy,and *** that microbial factors influence the cancer treatment outcome,we further summarize some dominating microbial interventions and discuss the hidden risks of these *** review aims to provide an overview of the applications and advancements of microbes in cancer clinical relevance.

关键词： microbiome cancer diagnosis prognosis therapy