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A stability evaluation method for deep-seated toppling in the upper Lancang river,Southwestern China
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作者 Yibing Ning Huiming Tang +3 位作者 Jianbing Peng yanjun shen John V.Smith Bocheng Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第7期2388-2410,共23页
Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in depth.The slope deformation is initiated by river downcutting and evolves distinctive characteris... Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in depth.The slope deformation is initiated by river downcutting and evolves distinctive characteristics with a depth of river incision.In this study,we propose a system for evaluating the stability of deep-seated toppled slopes in different evolutionary stages.This system contains identification criteria for each evolutionary stage and provides the corresponding stability evaluation methods.Based on the mechanical and kinematic analysis of slope blocks,the specific stage of slope movement can be identified in the field through outcrop mapping,in situ tests,surface displacement monitoring,and adit and borehole explorations.The stability evaluation methods are established based on the limiting equilibrium theory and the strain compatibility between the undisturbed zone and the toppled zone.Finally,several sample slopes in different evolution stages have been investigated to verify the applicability and accuracy of the proposed stability evaluation system.The results indicate that intense tectonic activity and rapid river incision lead to a maximum principal stress ratio exceeding 10 near the slope surface,thus triggering widespread toppling deformations along the river valley.When considering the losses of joint cohesion during the further rotation process,the safety factor of the slope drops by 7%e28%.The self-stabilization of toppling deformation can be recognized by the layer symmetry configuration after the free rotation of the deflected layers.Intensely toppled rock blocks mainly suffer sliding failures beyond the layer symmetry condition.The factor of safety of the K73 rockslide decreased from 1.17 to 0.87 by considering the development of the potential sliding surface and the toesaturated zone. 展开更多
关键词 Stability evaluation Deep-seated toppling Evolutionary process Reservoir impoundment Rock slope
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Inconsistency of changes in uniaxial compressive strength and P-wave velocity of sandstone after temperature treatments 被引量:9
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作者 Jinyuan Zhang yanjun shen +5 位作者 Gengshe Yang Huan Zhang Yongzhi Wang Xin Hou Qiang Sun Guoyu Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2021年第1期143-153,共11页
It is generally accepted that the uniaxial compressive strength(UCS)and P-wave velocity of rocks tend to decrease simultaneously with increasing temperature.However,based on a great number of statistical data and syst... It is generally accepted that the uniaxial compressive strength(UCS)and P-wave velocity of rocks tend to decrease simultaneously with increasing temperature.However,based on a great number of statistical data and systematic analysis of the microstructure variation of rocks with temperature rising and corresponding propagation mechanism of elastic wave,the results show that(1)There are three different trends for the changes of UCS and P-wave velocity of sandstone when heated from room temperature(20C or 25C)to 800C:(i)Both the UCS and P-wave velocity decrease simultaneously;(ii)The UCS increases initially and then decreases,while the P-wave velocity decreases continuously;and(iii)The UCS increases initially and then fluctuates,while the P-wave velocity continuously decreases.(2)The UCS changes at room temperaturee400C,400Ce600C,and 600Ce800C are mainly attributed to the discrepancy of microstructure characteristics and quartz content,the transformation plasticity of clay minerals,and the balance between the thermal cementation and thermal damage,respectively.(3)The inconsistency in the trends of UCS and P-wave velocity changes is caused by the change of quartz content,phase transition of water and certain minerals. 展开更多
关键词 SANDSTONE High temperature Uniaxial compressive strength(UCS) P-wave velocity DISTORTION MINERALOGY
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Finite-time control of linear parameter-varying systems with norm-bounded exogenous disturbance 被引量:5
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作者 yanjun shen 《控制理论与应用(英文版)》 EI 2008年第2期184-188,共5页
In this paper, a new approach is presented for finite-time control problems for linear systems subject to time-varying parametric uncertainties and exogenous disturbance. The disturbance is assumed to be time varying ... In this paper, a new approach is presented for finite-time control problems for linear systems subject to time-varying parametric uncertainties and exogenous disturbance. The disturbance is assumed to be time varying and bounded. Sufficient conditions are obtained for the existence of a linear parameter-dependent state feedback gain, which can ensure that the closed-loop system is finite-time bounded (FTB). The conditions can be reduced to feasibility problems involving LMIs. Numerical examples show the validity of the proposed methodology. 展开更多
关键词 Finite time stability Polytopic system LMI Norm-bounded exogenous disturbance
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Sandstone-concrete interface transition zone (ITZ) damage and debonding micromechanisms under freeze-thaw 被引量:4
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作者 yanjun shen Huan Zhang +3 位作者 JinYuan Zhang HongWei Yang Xu Wang Jia Pan 《Research in Cold and Arid Regions》 CSCD 2021年第2期133-149,共17页
The sufficient bond between concrete and rock is an important prerequisite to ensure the effect of shotcrete support. However, in cold regions engineering protection system, the bond condition of rock and concrete sur... The sufficient bond between concrete and rock is an important prerequisite to ensure the effect of shotcrete support. However, in cold regions engineering protection system, the bond condition of rock and concrete surface is easily affected by freeze-thaw cycles, resulting in interface damage, debonding and even supporting failure. Understanding the micromechanisms of the damage and debonding of the rock-concrete interface is essential for improving the interface protection.Therefore, the micromorphology, micromechanical properties, and microdebonding evolution of the sandstone-concrete interface transition zone(ITZ) under varying freeze-thaw cycles(0, 5, 10, 15, 20) were studied using scanning electron microscope, stereoscopic microscope, and nano-indentation. Furthermore, the distribution range and evolution process of ITZ affected by freeze-thaw cycles were defined. Major findings of this study are as follows:(1) The microdamage evolution law of the ITZ under increasing freeze-thaw cycles is clarified, and the relationship between the number of cracks in the ITZ and freeze-thaw cycles is established;(2) As the number of freeze-thaw cycles increases, the ITZ's micromechanical strength decreases, and its development width tends to increase;(3) The damage and debonding evolution mechanisms of sandstone-concrete ITZ under freeze-thaw cycles is revealed, and its micromechanical evolution model induced by freeze-thaw cycles is proposed. 展开更多
关键词 sandstone-concrete interface transition zone(ITZ) freeze-thaw cycles nano-indentation damage and debonding
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Two Ultraviolet Radiation Datasets that Cover China 被引量:3
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作者 Hui LIU Bo HU +42 位作者 Yuesi WANG Guangren LIU Liqin TANG Dongsheng JI Yongfei BAI Weikai BAO Xin CHEN Yunming CHEN Weixin DING Xiaozeng HAN Fei HE Hui HUANG Zhenying HUANG Xinrong LI Yan LI Wenzhao LIU Luxiang LIN Zhu OUYANG Boqiang QIN Weijun shen yanjun shen Hongxin SU Changchun SONG Bo SUN Song SUN Anzhi WANG Genxu WANG Huimin WANG Silong WANG Youshao WANG Wenxue WEI Ping XIE Zongqiang XIE Xiaoyuan YAN Fanjiang ZENG Fawei ZHANG Yangjian ZHANG Yiping ZHANG Chengyi ZHAO Wenzhi ZHAO Xueyong ZHAO Guoyi ZHOU Bo ZHU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2017年第7期805-815,共11页
Ultraviolet(UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. O... Ultraviolet(UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes. 展开更多
关键词 reconstructed ozone absolute ultraviolet estimates environments climatic cumulative sunshine meteorological
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An improved approach to H-two control withregional stability constraints
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作者 yanjun shen Tingsong DU 《控制理论与应用(英文版)》 EI 2007年第4期380-384,共5页
This paper presents an improved method for H-two control with regional stability constraints for the closedloop system. The controller is given by the convex combination of a set of fixed gains. Both continuous and di... This paper presents an improved method for H-two control with regional stability constraints for the closedloop system. The controller is given by the convex combination of a set of fixed gains. Both continuous and discrete-time systems in a known polytopic domain are investigated. New LMI-based sufficient conditions for the existence of parameterdependent Lyapunov functions are proposed. Numerical examples are given to show the proposed conditions provide useful and less conservative results for the problems of H-two control with regional stability constraints. 展开更多
关键词 H2 control Regional stability constraints Polytopic domains LMI
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Flocking Control of a Group of Agents Using a Fuzzy-Logic-Based Attractive/Repulsive Function
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作者 Hui Yu Jigui Jian yanjun shen 《International Journal of Communications, Network and System Sciences》 2010年第6期569-577,共9页
In this study, a novel procedure is presented for control and analysis of a group of autonomous agents with point mass dynamics achieving flocking motion by using a fuzzy-logic-based attractive/repulsive function. Two... In this study, a novel procedure is presented for control and analysis of a group of autonomous agents with point mass dynamics achieving flocking motion by using a fuzzy-logic-based attractive/repulsive function. Two cooperative control laws are proposed for a group of autonomous agents to achieve flocking formations related to two different centers (mass center and geometric center) of the flock. The first one is designed for flocking motion guided at mass center and the other for geometric center. A virtual agent is introduced to represent a group objective for tracking purposes. Smooth graph Laplacian is introduced to overcome the difficulties in theoretical analysis. A new fuzzy-logic-based attractive/repulsive function is proposed for separation and cohesion control among agents. The theoretical results are presented to indicate the stability (separation, collision avoidance and velocity matching) of the control systems. Finally, simulation example is demonstrated to validate the theoretical results. 展开更多
关键词 FLOCKING Cooperative CONTROL MULTI-AGENT System Fuzzy LOGIC
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Enlarged fins of Tibetan catfish provide new evidence of adaptation to high plateau 被引量:2
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作者 Liandong Yang Ning Sun +14 位作者 Honghui Zeng Ying Wang Wenjun Chen Zufa Ding Yang Liu Jing Wang Minghui Meng yanjun shen Jingliang Kang Xiuhui Ma Wenqi Lv Juan Chen Axel Meyer Baocheng Guo Shunping He 《Science China(Life Sciences)》 SCIE CAS CSCD 2023年第7期1554-1568,共15页
The uplift of the Tibetan Plateau significantly altered the geomorphology and climate of the Euroasia by creating large mountains and rivers.Fishes are more likely to be affected relative to other organisms,as they ar... The uplift of the Tibetan Plateau significantly altered the geomorphology and climate of the Euroasia by creating large mountains and rivers.Fishes are more likely to be affected relative to other organisms,as they are largely restricted to river systems.Faced with the rapidly flowing water in the Tibetan Plateau,a group of catfish has evolved greatly enlarged pectoral fins with more numbers of fin-rays to form an adhesive apparatus.However,the genetic basis of these adaptations in Tibetan catfishes remains elusive.In this study,we performed comparative genomic analyses based on the chromosome-level genome of Glyptosternum maculatum in family Sisoridae and detected some proteins with conspicuously high evolutionary rates in particular in genes involved in skeleton development,energy metabolism,and hypoxia response.We found that the hoxd12a gene evolved faster and a loss-of-function assay of hoxd12a supports a potential role for this gene in shaping the enlarged fins of these Tibetan catfishes.Other genes with amino acid replacements and signatures of positive selection included proteins involved in low temperature(TRMU)and hypoxia(VHL)responses.Functional assays reveal that the G.maculatum TRMU allele generates more mitochondrial ATP than the ancestral allele found in low-altitude fishes.Functional assays of VHL alleles suggest that the G.maculatum allele has lower transactivation activity than the low-altitude forms.These findings provide a window into the genomic underpinnings of physiological adaptations that permit G.maculatum to survive in the harsh environment of the Tibetan Himalayas that mirror those that are convergently found in other vertebrates such as humans. 展开更多
关键词 Glyptosternum maculatum enlarged fins ADAPTATION Tibetan Plateau
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Decadal water storage decrease driven by vegetation changes in the Yellow River Basin 被引量:10
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作者 Congcong Li Yongqiang Zhang +1 位作者 yanjun shen Qiang Yu 《Science Bulletin》 SCIE EI CAS CSCD 2020年第22期1859-1861,M0003,共4页
The Yellow River is the second largest river in China,and it is of paramount importance as it serves various hydro-ecological functions for its inhabitants and environment.It consumes 12%of the water in China,with ann... The Yellow River is the second largest river in China,and it is of paramount importance as it serves various hydro-ecological functions for its inhabitants and environment.It consumes 12%of the water in China,with annual runoff accounting for 2%of the whole country.For sustainable water resources management under climate change and land cover changes(mainly the vegetation change),it is essential to understand the terrestrial water storage change(WSC)and its major driving factors in the Yellow River Basin(YRB)[1]. 展开更多
关键词 environment. RUNOFF driving
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Comparison of winter wheat yield sensitivity to climate variables under irrigated and rain-fed conditions 被引量:4
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作者 Dengpan XIAO yanjun shen +6 位作者 He ZHANG Juana P. MOIWO Yongqing QI Rende WANG Hongwei PEI Yucui ZHANG Huitao shen 《Frontiers of Earth Science》 SCIE CAS CSCD 2016年第3期444-454,共11页
Crop simulation models provide alternative, less time-consuming, and cost-effective means of deter- mining the sensitivity of crop yield to climate change. In this study, two dynamic mechanistic models, CERES (Crop E... Crop simulation models provide alternative, less time-consuming, and cost-effective means of deter- mining the sensitivity of crop yield to climate change. In this study, two dynamic mechanistic models, CERES (Crop Environment Resource Synthesis) and APSIM (Agricultural Production Systems Simulator), were used to simulate the yield of wheat (Triticum aestivum L.) under well irrigated (CFG) and rain-fed (YY) conditions in relation to different climate variables in the North China Plain (NCP). The study tested winter wheat yield sensitivity to different levels of temperature, radiation, precipitation, and atmospheric carbon dioxide (COa) concentration under CFG and YY conditions at Luancheng Agro-ecosystem Experimental Stations in the NCR The results from the CERES and APSIM wheat crop models were largely consistent and suggested that changes in climate variables influenced wheat grain yield in the NCR There was also significant variation in the sensitivity of winter wheat yield to climate variables under different water (CFG and YY) conditions. While a temperature increase of 2℃ was the threshold beyond which temperature negatively influenced wheat yield under CFG, a temperature rise exceeding 1℃ decreased winter wheat grain yield under YY. A decrease in solar radiation decreased wheat grain yield under both CFG and YY conditions. Although the sensitivity of winter wheat yield to precipitation was small under the CFG, yield decreased significantly with decreasing precipitation under the rain- fed YY treatment. The results also suggest that wheat yield under CFG linearly increased by ≈ 3.5% per 60 ppm (parts per million) increase in CO2 concentration from 380 to560ppm, and yield under YY increased linearly by ≈ 7.0% for the same increase in CO2 concentration. 展开更多
关键词 winter wheat yield sensitivity climate vari-ables crop model North China Plain
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Molecular phylogeny and divergence time estimates using the mitochondrial genome for the hadal snailfish from the Mariana trench
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作者 yanjun shen Wei Dai +3 位作者 Zhaoming Gao Guoyong Yan Xiaoni Gan Shunping He 《Science Bulletin》 SCIE EI CAS CSCD 2017年第16期1106-1108,共3页
Snailfishes are an important component of the hadal fish fauna[1].Based on osteological and other morphological characters,Kido[2]recognized the Cyclopteridae as a sister group to the Liparidae and the superfamily Cot... Snailfishes are an important component of the hadal fish fauna[1].Based on osteological and other morphological characters,Kido[2]recognized the Cyclopteridae as a sister group to the Liparidae and the superfamily Cottoidea as a sister group to the two families.The close relationship between Liparidae and Cyclopteridae is 展开更多
关键词 狮子鱼 分子系统发育 马里亚纳海沟 线粒体基因组 时间估计 超深 分化 分子数据
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