检索结果-南通市图书馆

Coupled DEM-FDM analyses of the effects of falling rock’s shape and impact angle on response of granular cushion and rock shed

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3353-3364页

作者： Jingyu Xue chen Cao Jianhua yan Yaopeng Ji Jianping chen College of Construction Engineering Jilin UniversityChangchun130026China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China

Rock shed is an effective protection measure against *** investigate the influences of falling rock’s shape and impact angle on the impact effect of the cushioned rock shed,a modeling approach for a rock shed with a cushion layer using *** granular cushion is modeled as an aggregate of discrete non-cohesion particles,while the concrete plate and the beam are modeled as *** falling rock with different sphericities and impact angles is modeled as a rigid *** numerical model is validated by comparing the simulation results with experimental and numerical results from previous *** model is applied to analyze the effects of rock shape and impact angle on the dynamic interaction effects between falling rock and cushioned rock shed,including the impact force,transmitted bottom force,penetration depth,and plate *** numerical results show that the variation in the falling rock’s shape has different effects on the falling rock with different impact *** findings could support rock shed design by revealing the limitations of the assumptions in the past research,which may result in unsafe rock sheds for some rockfall cases.

关键词： Rockfall Coupled DEM-FDM analysis Rock’s shape Impact angle Granular cushion Rock shed

Stability of water yield in watersheds

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第2期67卷 483-496页

作者： Yu yan Zhiyong LIU Xiaohong chen Liyan HUANG Center for Water Resources and Environment School of Civil EngineeringSun Yat-Sen UniversityGuangzhou510275China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519082China

The hydrological system of a watershed is intricately influenced by both underlying characteristics and climate *** the variability in water yield is essential for effective water resources management and water security in the context of changing *** this study,we adopted the Budyko framework and leveraged simulations from the CMIP6 model to investigate the compensation effects of climate and underlying characteristics on watershed water *** on Taylor expansion and Budyko framework,we estimated the sensitivity of watershed water yield to climate and underlying characteristics(the first-and second-order partial derivatives).By combining external watershed characteristics(e.g.,water yield ratios and underlying characteristics)with internal sensitivity coefficients,this study further used vine copula and principal component analysis to quantify the stability of watershed water *** findings show:(1)Water-yield changes related to underlying characteristics could be offset by climate-related water-yield changes across all climate zones,maintaining the water yield ratio steady(i.e.,the compensation effects).(2)However,global watersheds will turn more sensitive to underlying characteristics and less sensitive to climate variation in the *** climate-and underlying-related sensitivities increase in watersheds with arid climates.(3)The stability of watershed water yield will gradually diminish in the *** 1901–1950to 2051–2100,the global stability of 280 watersheds drops from 0.054 to 0.021(i.e.,stability index identified by the joint probability).Particularly,the largest change in stability of water yield reaches-0.347±0.18 in arid *** semi-arid,semihumid,and humid regions,the changes are-0.039±0.010,-0.028±0.005,and-0.005±0.002,*** findings provide a reference for the future sustainable water resources development under climate change,highlighting the vulnerability of the water resources in ari

关键词： Hydrological system stability Compensation effects on water yield Sensitivities Budyko-Fu decomposition framework Global watersheds

On optimal streaming kernelization algorithms

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第8期67卷 337-338页

作者： Hao feng Wei yanG Jianer chen School of Computer Science Guangzhou University Department of Computer Science and Engineering Texas A&M University

The streaming model has been a popular model in big data computation. Streaming kernelization algorithms can be regarded as data compression processes on streaming data. In this study, we give a general method for developing computational lower bounds for streaming kernelization algorithms that is applicable to a large class of computational problems. As an example, we use the method to prove computational lower bounds for the well-known problem d-Hi TTin GSET.

关键词：

Transcription factor Foxp1 is essential for the induction of choroidal neovascularization

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Eye and Vision 2024年第3期10卷 1-12页

作者： Meifang yan Junjian Li Li yan Xue Li Jie-Guang chen School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical UniversityState Key Laboratory of OptometryOphthalmology and Vision Scienceand Zhejiang Provincial Key Laboratory of Optometry and Ophthalmology270 Xueyuan RoadWenzhouZhejiang325027People’s Republic of China Joint Shantou International Eye Center(JSIEC)of Shantou University and the Chinese University of Hong Kong ShantouGuangdong515000People’s Republic of China

Background The exudative form of age-related macular degeneration(AMD)is characterized by abnormal blood vessel growth,which is stimulated by vascular endothelial growth factor(VEGF)released from retinal pigment epithelium(RPE).The angiogenic behaviors of vascular endothelial cells in vitro depend on forkhead box protein P1(Foxp1),a transcription repressor widely expressed in human and murine tissues during *** this study,we aimed to determine whether loss of Foxp1 affects laser-induced choroidal neovascularization(CNV)in *** Eye-selective deletion of Foxp1 was obtained by crossing Foxp1flox/flox with Six3-Cre *** photocoagulation was delivered to six-to eight-week-old mice to induce *** expression of Foxp1 and Cre was determined by immunofluorescence in cryostat sections of the *** fluorescein angiography(FFA),optical coherence tomography(OCT),and B4 isolectin staining were applied to analyze the leakage,bulge height,and area of CNV lesions,***-choroid tissues were isolated for the determination of VEGF and pigment epithelium derived factor(PEDF)by Western *** Foxp1 was expressed in retinal ganglion cells,RPE,and the choroidal endothelial *** photocoagulation increased the number of Foxp1+-endothelial cells and induced ***3-Cre reduced Foxp1 expression in RPE but not the endothelium,leading to a lower level of VEGF in the ***1 knockout inhibited pathological angiogenesis and vascular leakage of the laser-induced CNV *** Foxp1 regulates the expression of VEGF in the RPE,and inhibition of Foxp1 could potentially be a novel strategy for the prevention and therapy of neovascularization related to AMD.

关键词： Foxp1 Choroidal neovascularization Angiogenesis Laser photocoagulation Age-related macular degeneration

Underdetermined direction of arrival estimation with nonuniform linear motion sampling based on a small unmanned aerial vehicle platform

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第3期33卷 352-363页

作者： Xinwei Wang Xiaopeng yan Tai An Qile chen Dingkun Huang Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China

Uniform linear array(ULA)radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles(UAVs).In practice,a ULA's multi-target direction of arrival(DOA)estimation performance suffers from significant performance degradation owing to the limited number of physical *** improve the underdetermined DOA estimation performance of a ULA radar mounted on a small UAV platform,we propose a nonuniform linear motion sampling underdetermined DOA estimation *** the motion of the UAV platform,the echo signal is sampled at different ***,according to the concept of difference co-array,a virtual ULA with multiple array elements and a large aperture is synthesized to increase the degrees of freedom(DOFs).Through position analysis of the original and motion arrays,we propose a nonuniform linear motion sampling method based on ULA for determining the optimal *** the condition of no increase in the aperture of the physical array,the proposed method obtains a high DOF with fewer sampling runs and greatly improves the underdetermined DOA estimation performance of *** results of numerical simulations conducted herein verify the superior performance of the proposed method.

关键词： Unmanned aerial vehicle(UAV) Uniform linear array(ULA) Direction of arrival(DOA) Difference co-array Nonuniform linear motion sampling method

A Magnetic-Driven Multi-motion Robot with Position/Orientation Sensing Capability

在线全文

学校读者我要写书评

暂无评论

Research 2024年第1期2023卷 675-685页

作者： Liwen Zhang Song Zhao Xinzhao Zhou Xueshan Jing Yu Zhou yan Wang yantong Zhu Xiaolin Liu Zehui Zhao Deyuan Zhang Lin feng Huawei chen School of Mechanical Engineering and Automation Beihang UniversityBeijingChina Beijing Advanced Innovation Center for Biomedical Engineering Beihang UniversityBeijingChina

Miniature magnetic-driven robots with multimode motions and high-precision pose sensing capacity(position and orientation)are greatly demanded in in situ manipulation in narrow opaque enclosed *** magnetic robots have been carried out,whereas their deformations normally remain in single mode,and the lack of the robot’s real-time status leads to its beyond-sight remagnetization and manipulation being *** function integration of pose sensing and multimode motion is still of ***,a multimotion thin-film robot is created in a novel multilayer structure with a magneticdriven layer covered by a heating-sensing conductive *** a heating-sensing layer not only can segmentally and on-demand heat the magnetic-driven layer for in situ magnetization reprogramming and multimode motions but also can precisely detect the robot’s pose(position and orientation)from its electrical-resistance effect by creating a small deformation under preset magnetic fields.

关键词： robot Robot motion

Nanopore design of sulfur doped hollow carbon nanospheres for superior potassium-ion battery anodes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第5期43卷 2103-2114页

作者： Zhen-Dong Liu Hui-yan feng Yu-chen Wang Fei Wang Yue Liu Jian-Xiao yang Yue Gu Jun Tan Chong Ye cheng-Zhi Zhang Ji Hua Laboratory Foshan 528000China School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou 510006China Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology College of Materials Science and EngineeringHunan UniversityChangsha 410082China

Sulfur doped carbonaceous materials are promising anodes for potassium-ion batteries because of their ability to bridge active sites and induce C/S electron coupling,resulting in increased ion storage capacitance However,the large potassium ions could cause significant volume expansion and structure collapse during operation in sulfur doped carbonaceous anodes,which lead to rapidly capacity sacrifice during long-term *** design for anchoring sulfur atom in carbon skeleton is a novel way to alleviate the structure collapse and maintain the cycling ***,this study developed a controlled nanopore and sulfur doped carbon sphere structure(S-NPHCSs).In potassium-ion batteries S-NPHCSs anode demonstrated exceptional performance with a high reversible capacity of 247 mAh·g^(–1)after 50 cycles at 0.2 A·g^(–1)and delivered a long cycle stability of 600 cycles at a high current density of 1.0 A·g^(–1).Interconnected nanopores and doped sulfur structure not only expand the accumulation space and offer ample active sites for diffusion and adsorption of potassium ions,but also build stable channels through nanopore structure to ensure the cyclic *** finding provides a fundamental theory for designing nanopore structures and introducing sulfur doped carbonaceous materials to enhance capacitive potassium storage and long cycle stability.

关键词： Nanopore Carbon materials Sulfur doping Anode Potassium-ionbatteries

Resistance index and browning mechanism of apple peel under high temperature stress

在线全文

学校读者我要写书评

暂无评论

Horticultural Plant Journal 2024年第2期10卷 305-317页

作者： Hui Wang Shuhui Zhang Zidun Wang Dongmei Li Leiyu yan Yifeng feng Xiaojie Liu Rongxin chen Wenmin Fan Lulong Sun Zhengyang Zhao College of Horticulture Northwest A&F UniversityYanglingShaanxi 712100China College of Horticultural Science and Engineering Shandong Agricultural University State Key Laboratory of Crop BiologyTai'anShandong 271018China

Apples are one of the most important economic crops *** of global warming and an aggravation of environmental,abnormally high temperatures occur frequently in fruit-growing season and seriously affect normal fruit growth and reduce fruit quality and *** took five-year-old Ruixue’(Qinfu 1×Pink Lady;CNA20151469.1) fruits as test materials,and the ambient temperature during fruit development was *** results showed that during the fruit-growing season,especially during the rapid growth stage (July to August),the maximum daily temperature exceeded 30℃ and lasted for more than 40 *** determine the effects of high temperature stress on the apple fruit resistance,we treated expanding,veraison,and maturity-period fruits at different *** was found that the fruits of the expanding period showed strong resistance to high temperature stress,whereas during veraison and maturity,fruit resistance to high temperature stress decreased,and the fruit peel browning phenotype ***,the content of malonaldehyde (MDA),hydrogen peroxide (H_(2)O_(2)),and superoxide anion (O._(2)^(-)) in the peel gradually increased with increasing *** content of total phenols,flavanol,and flavonoids in the peel decreased substantially at 45℃.Moreover,it was found that polyphenol oxidase gene (MdPPO1) was most sensitive to high temperature stress in ***,transient and stable MdPPO1 overexpression significantly promoted peel *** transgenic materials were more sensitive to high temperatures,and browning was more severe compared to non-genetically modified organism (WT).Stable MdPPO1 knockout calli obtained via clustered regularly interspersed short palindromic repeats (CRISPR/Cas9) gene knockout technology reduced the browning phenotype,and the resultant fruits were not sensitive to the effects of high temperature ***,MdPPO1 expression may be a key factor of high temperature-related changes observed in the browni

关键词： Malus domestica Borkh High temperature stress Peel Browning MdPPO1

Anisotropy measurements and characterization of the Qingshankou shale

在线全文

学校读者我要写书评

暂无评论

Applied Geophysics 2024年第3期21卷 468-478,617页

作者： Li Qing-feng yan Xue-hong yan Wei-lin Ren Li Wang Peng Han Jian-qiang Xia Xue chen Hao Daqing Oilfield Exploration Division Daqing163000HeilongjiangChina Daqing Branch Company of CNPC Logging Daqing163000HeilongjiangChina Exploration and Development Research Institute of Daqing Oilfield Co. Ltd.Daqing163712China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing100190China

Qingshankou shale(Gulong area,China)exhibits strong acoustic anisotropy characteristics,posing significant challenges to its exploration and *** this study,the five full elastic constants and multipole response law of the Qingshankou shale were studied using experimental *** show that the anisotropy parametersϵandγin the study region are greater than 0.4,whereas the anisotropy parameterδis smaller,generally *** simulations show that the longitudinal and transverse wave velocities of these strong anisotropic rocks vary significantly with inclination angle,and significant differences in group velocity and phase velocity are also *** logging measures the group velocity in dipped boreholes;this differs from the phase velocity to some *** the dip angle increases,the longitudinal and SH wave velocities increase accordingly,while the qSV-wave velocity initially increases and then decreases,reaching its maximum value at a dip of approximately 40°.These results provide an effective guide for the correction and modeling of acoustic logging time differences in the region.

关键词： Transverse isotropy anisotropy parameter sonic logging group velocity phase velocity