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187篇 您的检索式:作者名="Hongbo Zhao"
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1The Chrysanthemum nankingense Genome Provides Insights into the Evolution and Diversification of Chrysanthemum Flowers and Medicinal Traits显示文摘The Asteraceae (Compositae),a large plant family of approximately 24 000-35 000 species,accounts for^10% of all angiosperm species and contributes a lot to plant diversity.The most representative members of the Asteraceae are the economically important chrysanthemums (Chrysanthemum L.)that diversified through reticulate evolution.Biodiversity is typically created by multiple evolutionary mechanisms such as wholegenome duplication 0NGD)or polyploidization and locally repetitive genome expansion.However,the lack of genomic data from chrysanthemum species has prevented an in-depth analysis of the evolutionary mechanisms involved in their diversification.Here,we used Oxford Nanopore long-read technologyto sequence the diploid Chrysanthemum nankingense genome,which represents one of the progenitor genomes of domesticated chrysanthemums.Our analysis revealed that the evolution of the C.nankingense genome was driven by bursts of repetitive element expansion and WGD events including a recentWGD that distinguishes chrysanthemum from sunflower,which diverged from chrysanthemum approximately 38.8 million years ago.Variations of ornamental and medicinal traits in chrysanthemums are linked to the expansion of candidate gene families by duplication events including paralogous gene duplication.Collectively,our study of the assembled reference genome offers new knowledge and resources to dissect the history and pattern of evolution and diversification of chrysanthemum plants,and also to accelerate their breeding and improvement.Chi Song Yifei Liu Aiping Song Gangqiang Dong Hongbo Zhao Wei Sun Shyam Ramakrishnan Ying Wang Shuaibin Wang Tingzhao Li Yan Niu Jiafu Jiang Bin Dong Ye Xia Sumei Chen Zhigang Hu Fadi Chen Shilin Chen 2018Molecular Plant2018,11,12:24
2TRPV1 activation improves exercise endurance and energy metabolism through PGC-1α upregulation in mice显示文摘Zhidan Luo Liqun Ma Zhigang Zhao Hongbo He Dachun Yang Xiaoli Feng Shuangtao Ma Xiaoping Chen Tianqi Zhu Tingbing Cao Daoyan Liu Bernd Nilius Yu Huang Zhencheng Yan Zhiming Zhu 2012Cell Research2012,22,3:18
3Analysis and Numerical Simulation of Rolling Contact between Sphere and Cone显示文摘In non-conforming rolling contact, the contact stress is highly concentrated in the contact area. However, there are some limitations of the special contact model and stress model used for the theoretical study of the phenomenon, and this has prevented in-depth analysis of the associated friction, wear, and failure. This paper is particularly aimed at investigating the area of rolling contact between a sphere and a cone, for which purpose the boundary is determined by the Hertz theory and the geometries of the non-conforming surfaces. The phenomenon of stick-slip contact is observed to occur in the contact area under the condition of no-full-slip(Q < μ·P). Using the two-dimensional rolling contact theory developed by CARTER, the relative positions of the stick and slip regions and the distribution of the tangential force over the contact area are analyzed. Furthermore, each stress component is calculated based on the Mc Ewen theory and the idea of narrow band. The stress equations for the three-dimensional rolling contact between the sphere and the cone are obtained by the principle of superposition, and are used to perform some numerical simulations. The results show that the stress components have a large gradient along the boundary between the stick and slip regions, and that the maximum stress is inversely proportional to the contact coefficient and proportional to the friction coefficient. A new method for investigating the stress during non-classical three-dimensional rolling contact is proposed as a theoretical foundation for the analysis of the associated friction, wear, and failure.ZHAO Yanling XIA Chengtao WANG Hongbo XUAN Jiaping XIANG Jingzhong LIU Xianli SU Xiangguo 2015Chinese Journal of Mechanical Engineering2015,28,3:18
4Effects of applying lactic acid bacteria to the fermentation on a mixture of corn steep liquor and air-dried rice straw显示文摘This study was to determine the fermentation quality of a mixture of corn steep liquor(CSL)(178 g/kg wet basis) and air-dried rice straw(356 g/kg wet basis) after being treated with inoculants of different types of lactic acid bacteria(LAB). The treatments included the addition of no LAB additive(control),which was deionized water; homo-fermentative LAB alone(^(ho)LAB), which was Lactobacillus plantarum alone), and a mixture of homo-fermentative and hetero-fermentative LAB(^(he+ho)LAB), which were L. plantarum, Lactobacillus casei, and Lactobacillus buchneri. The results showed that the inoculation of the mixture of CSL and air-dried rice straw with ^(he+ho)LAB significantly increased the concentration of acetic acid and lactic acid compared with the control(P < 0.05). The addition of ^(he+ho)LAB effectively inhibited the growth of yeast in the silage. The concentration of total lactic acid bacteria in the ^(he+ho)LAB-treated silage was significant higher than those obtained in other groups(P < 0.05). The duration of the aerobic stability of the silages increased from 56 h to >372 h. The control group was the first to spoil, whereas the silage treated with ^(he+ho)LAB remained stable throughout the 372 h period of monitoring. The results demonstrated that the ^(he+ho)LAB could effectively improve the fermentation quality and aerobic stability of the silage.Xinxin Li Wenbin Xu Jinshan Yang Hongbo Zhao Chunfang Pan Xue Ding Yonggen Zhang 2016Animal Nutrition2016,,3:17
5High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse显示文摘Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties,which,however,is usually restricted by the disadvantages of the current fabrication methods.Here,by exploiting cylindrical focusing of a femtosecond laser on graphene oxide(GO)films,we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process.Strikingly,the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations.The proposed model and simulations reveal that the structure formation is based on the transverse electric(TE)surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior,which eventually results in interference intensity fringes and spatially periodic interactions.Further experiments prove that such a regular structured surface can cause enhanced optical absorption(>20%)and an anisotropic photoresponse(~0.46 ratio)for the reduced GO film.Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography,with the prospect of expansion to other two-dimensional materials for novel device applications.Tingting Zou Bo Zhao Wei Xin Ye Wang Bin Wang Xin Zheng Hongbo Xie Zhiyu Zhang Jianjun Yang Chunlei Guo 2020Light(Science & Applications)2020,9,1:17
6Overview of 5G security technology显示文摘The 5 th-generation mobile communication system(5 G) has higher security requirements than previous systems. Accordingly, international standard organizations, operators, and equipment manufacturers are focusing extensively on 5 G security technology. This paper analyzes the security requirements of 5 G business applications, network architecture, the air interface, and user privacy. The development trends of5 G security architecture are summarized, with a focus on endogenous defense architecture, which represents a new trend in 5 G security development. Several incremental 5 G security technologies are reviewed, including physical layer security, lightweight encryption, network slice security, user privacy protection, and block chain technology applied to 5 G.Xinsheng JI Kaizhi HUANG Liang JIN Hongbo TANG Caixia LIU Zhou ZHONG Wei YOU Xiaoming XU Hua ZHAO Jiangxing WU Ming YI 2018Science China(Information Sciences)2018,61,8:14
7Basement of the South China Sea Area:Tracing the Tethyan Realm显示文摘华南海( SCS )和邻近的区域的地下室能被划分成六个部门(区域)在 Beibu 海湾的古生代的 Erathem 指责graben 的地下室分割,在 Yinggehai 的古生代的 Erathem 罢工滑倒拉开流水,在东方海南的古生代的 Erathem 差错消沉,在北 Xisha ( Paracel )的古生代的 Erathem rifted ,古生代的 Erathem 罢工滑倒在在 Nansha 岛延长的南部的 Xisha ,和古生代中生代的 Erathem 延长( Spratly )水。在 SCS 和 Yunkai 大陆人区域的新生代前地下室在在新生代前时期的 Tethyan 构造领域以内是同时代的。他们在 Paleo-Tethyan 构造领域的背景上被形成,并且是东方 Tethyan multi-island-ocean 系统的重要部件。东方 Paleo-Tethys 构造领域,北方 Yunkai,诺思海南,和南方海南海盆的三个分支,演变为北方 Yunkai,诺思海南,和南方海南缝术地区分别地。这为新生代前地下室显示出本地化的一个特殊特征。 Qiongnan (即南方海南)华南海的北边缘上的缝术地区能被认为 Paleo-Tethys 的主要海洋盆的痕迹,并且与 Longmucuo-Shuanghu beltBitu 带 Changning-Menglian-Bentong-Raub 带的缝术地区连接了,华南海的西方上的 Bitu-Changning-MenglianChing Mai beltChanthaburi-Raub-Bentong 带的南方延期,并且与 Lianhua-Taidong 缝术地区(沿着在台湾的纵的山谷的东方方面的一个差错) Hida Qiongbei (诺思海南) 缝术地区可以向东沿着 Wangwu-Wenjiao 差错地区延长了,并且深与 Lufeng-Dapu-Zhenghe-Shangyu (Lianhuashan ) 连接通过珍珠河嘴盆的差错地区。Meso-Tethys 在华南海的南方上发展了。Nansha 马槽可以被认为 Meso-Tethys 的北架的痕迹。 Meso-Tethys 的海洋的外壳向南沿着 subduction-collision-thrust 有 subducted 有华南海的西方上的 Yarlung Zangbo-Mytkyina-Bago 地区的到那些的subduction杆反面的 Nansha 马槽的南部的边缘,并且 Meso-Tethyan (例如 Meso-Tethys 的北 Chichibu 海洋)在在西南日本的侏罗记早的白垩纪地球组的外部带的缝术地区 Butsozo 构造的线,在华南海的东方上。LIU Hailing ZHENG Hongbo WANG Yanlin LIN Qiujin WU Chaohua ZHAO Meisong DU Yunkong 2011Acta Geologica Sinica(English Edition)2011,85,3:13
8Chang'E-1 Lunar Mission:An Overview and Primary Science Results显示文摘Chang'E-1 is the first lunar mission in China,which was successfully launched on Oct.24th,2007.It was guided to crash on the Moon on March 1,2009,at 52.36°E,1.50°S,in the north of Mare Fecunditatis.The total mission lasted 495 days,exceeding the designed life-span about four months.1.37Terabytes raw data was received from Chang'E-1.It was then processed into 4Terabytes science data at different levels.A series of science results have been achieved by analyzing and applicating these data,especially 'global image of the Moon of China's first lunar exploration mission'.Four scientific goals of Chang'E-1 have been achieved.It provides abundant materials for the research of lunar sciences and cosmochemistry.Meanwhile these results will serve for China's future lunar missions.Ouyang Ziyuan Li Chunlai Lu Chang Liu Jianzhong Zou Yongliao Zhang Hongbo Jianjun Zuo Wei Su Yah Wen Weibin Bian Wei Zhao Baochang Wang Jianyu Yang Jianfeng Chang Jin Wang Huanyu Zhang Xiaohui Wang Shijin Wang Min Ren Xin Mu Lingli Kong Deqing Wang Xiaoqian Wang Fang Geng Liang Zhang Zhoubin Zheng Lei Zhu Xinying Zheng Yongchun Li Junduo Zou Xiaoduan Xu Chun Shi Shuobiao Gao Yifei Gao Guannan 2010空间科学学报2010,30,5:11
9A 600-year flood history in the Yangtze River drainage:Comparison between a subaqueous delta and historical records显示文摘Based on grain size analysis and high-resolution elemental scanning of core YD0901,taken from the subaqueous Yangtze River delta,a 600-year flood history was reconstructed for the Yangtze River drainage system.Zr/Rb ratios were chosen as a proxy for Yangtze River floods.Zr resides mainly in the coarse-grained minerals,and Rb is found in the fine-grained minerals.When floods occur,the discharge of the Yangtze River increases,which carries more coarse-grained minerals into the East China Sea.Therefore,deposition of coarse-grained minerals significantly increases relative to fine-grained minerals on the subaqueous delta,and subsequently the Zr/Rb ratios also increase.The higher the Zr/Rb peaks,the greater number of coarse particles deposited by saltation processes.Zr/Rb peaks correlate very well with historical records for Yangtze River floods.Especially at about AD 1870,the Zr/Rb ratio reached a maximum value over the last 600 years,which is consistent with 'the extreme flood event' in the upper and middle reaches of the Yangtze River in AD 1870,as indicated in the historical records.Results show that floods have occurred at a relatively high frequency over the last 600 years,which is consistent with historical records when,during the Ming-Qing Dynasty,floods occurred once every 4 years.In addition,spectral analysis of the Zr/Rb ratio showed that there is close link between the Yangtze River floods and ENSO intensity.WANG MinJie ZHENG HongBo XIE Xin FAN DaiDu YANG ShouYe ZHAO QuanHong WANG Ke 2011Chinese Science Bulletin2011,56,2:9
10A novel particle filter approach for indoor positioning by fusing WiFi and inertial sensors显示文摘WiFi fingerprinting is the method of recording WiFi signal strength from access points(AP) along with the positions at which they were recorded, and later matching those to new measurements for indoor positioning. Inertial positioning utilizes the accelerometer and gyroscopes for pedestrian positioning. However, both methods have their limitations, such as the WiFi fluctuations and the accumulative error of inertial sensors. Usually, the filtering method is used for integrating the two approaches to achieve better location accuracy. In the real environments, especially in the indoor field, the APs could be sparse and short range. To overcome the limitations, a novel particle filter approach based on Rao Blackwellized particle filter(RBPF) is presented in this paper. The indoor environment is divided into several local maps, which are assumed to be independent of each other. The local areas are estimated by the local particle filter, whereas the global areas are combined by the global particle filter. The algorithm has been investigated by real field trials using a WiFi tablet on hand with an inertial sensor on foot. It could be concluded that the proposed method reduces the complexity of the positioning algorithm obviously, as well as offers a significant improvement in position accuracy compared to other conventional algorithms, allowing indoor positioning error below 1.2 m.Zhu Nan Zhao Hongbo Feng Wenquan Wang Zulin 2015Chinese Journal of Aeronautics2015,28,6:8
11Experiments on mechanical properties of salt rocks under cyclic loading显示文摘The primary purpose of underground gas storages is to provide gas for seasonal consumptions or strategic reserve.The periodical operations of gas injection and extraction lead to cyclic loading on the walls and surrounding rocks of gas storages.To investigate the mechanical behaviors of different host rocks in bedded salt deposit,laboratory experiments were conducted on the samples of rock salt,thenardite,glauberite and gypsum.The mechanical properties of rock samples under monotonic and cyclic loadings were studied.Testing results show that,under monotonic loading,the uniaxial compressive stress(UCS) of glauberite is the largest(17.3 MPa),while that of rock salt is the smallest(14.0 MPa).The UCSs of thenardite and gypsum are 16.3 and 14.6 MPa,respectively.The maximum strain at the peak strength of rock salt(halite) is much greater than those of the other three rocks.The elastic moduli of halite,thenardite,glauberite and gypsum are 3.0,4.2,5.1 and 6.8 GPa,respectively.Under cyclic loading,the peak strengths of the rock specimens are deteriorated except for rock salt.The peak strengths of thenardite,glauberite and gypsum decrease by 33.7%,19.1% and 35.5%,respectively;and the strains of the three rocks at the peak strengths are almost the same.However,the strain of rock salt at the peak strength increases by 1.98%,twice more than that under monotonic loading.Under monotonic loading,deformation of the tested rock salt,thenardite and glauberite shows in an elastoplastic style.However,it changes to a ductile style under cyclic loading.Brittle deformation and failure are only observed for gypsum.The results should be helpful for engineering design and operation of gas storage in bedded salt deposit.Weiguo Liang Chuanda Zhang Hongbo Gao Xiaoqin Yang Suguo Xu Yangsheng Zhao 2012Journal of Rock Mechanics and Geotechnical Engineering2012,4,1:8
12Energy-efficient Bio-inspired Gait Planning and Control for Biped Robot Based on Human Locomotion Analysis显示文摘Hongbo Zhu Minzhou Luo Tao Mei Jianghai Zhao Tao Li Fayong Guo 2016Journal of Bionic Engineering2016,13,2:8
13Integration of GPS and low cost INS for pedestrian navigation aided by building layout显示文摘In outdoor environments,GPS is often used for pedestrian navigation by utilizing its signals for position computation,but in indoor or semi-obstructed environments,GPS signals are often unavailable.Therefore,pedestrian navigation for these environments should be realized by the integration of GPS and inertial navigation system(INS).However,the lowcost INS could induce errors that may result in a large position drift.The problem can be minimized by mounting the sensors on the pedestrian's foot,using zero velocity update(ZUPT) method with the standard navigation algorithm to restrict the error growth.However,heading drift still remains despite using ZUPT measurements since the heading error is unobservable.Also,foot mounted INS suffers from the initialization ambiguity of position and heading from GPS.In this paper,a novel algorithm is developed to mitigate the heading drift problem when using ZUPT.The method uses building layout to aid the heading measurement in Kalman flter,and it could also be combined for the initialization.The algorithm has been investigated with real feld trials using the low cost Microstrain3DM-GX3-25 inertial sensor,a Leica GS10 GPS receiver and a uBlox EVK-6T GPS receiver.It could be concluded that the proposed method offers a signifcant improvement in position accuracy for the long period,allowing pedestrian navigation for nearly40 min with mean position error less than 2.8 m.This method also has a considerable effect on the accuracy of the initialization.Feng Wenquan Zhao Hongbo Zhao Qi Li Jingwen 2013Chinese Journal of Aeronautics2013,26,5:8
14Detection of a half-microgal coseismic gravity change after the Ms7. 0 Lushan earthquake显示文摘Because only a small near-field coseismic gravity change signal remains after removal of noise from the accuracy of observations and the time and spatial resolution of the earth's surface gravity observation system,it is difficult to verify simulations of dislocation theory.In this study,it is shown that the GS15 gravimeter,located 99.5 km from the epicenter of the Ms7.0 Lushan earthquake on April 20,2013 at 08∶04 UTC+8,showed the influence of the earthquake from 2013-04-16 to 2013-04-26 after a time calibration,tide corrections,drift correction,period correction and relaxation correction were applied to its data.The post-seismic relaxation process of the spring in the gravimeter took approximately 430 minutes and showed a 2.5×10-8ms-2gravity change.After correcting for the relaxation process,it is shown that a coseismic gravity change of approximately+0.59±0.4×10-8ms-2was observed by the GS15 gravimeter;this agrees with the simulated gravity change of approximately 0.31×10-8ms-2.The rate of the coseismic gravity change and the coseismic vertical displacement,as measured by one-second and one-day sampling interval GPS units,is also consistent with the theoretical rate of change.Therefore,the GS15 gravimeter at the Pixian Station observed a coseismic gravity change after the Ms7.0 Lushan earthquake.This and similar measurements could be applied to test and confirm the theory used for these simulations.Wei Jin Zhao Bin Tan Hongbo Yu Dan Shen Chongyang Li Hui 2013Geodesy and Geodynamics2013,4,3:7
15Application of Improved Multi-Objective Ant Colony Optimization Algorithm in Ship Weather Routing显示文摘This paper presents a novel intelligent and effective method based on an improved ant colony optimization(ACO)algorithm to solve the multi-objective ship weather routing optimization problem,considering the navigation safety,fuel consumption,and sailing time.Here the improvement of the ACO algorithm is mainly reflected in two aspects.First,to make the classical ACO algorithm more suitable for long-distance ship weather routing and plan a smoother route,the basic parameters of the algorithm are improved,and new control factors are introduced.Second,to improve the situation of too few Pareto non-dominated solutions generated by the algorithm for solving multi-objective problems,the related operations of crossover,recombination,and mutation in the genetic algorithm are introduced in the improved ACO algorithm.The final simulation results prove the effectiveness of the improved algorithm in solving multi-objective weather routing optimization problems.In addition,the black-box model method was used to study the ship fuel consumption during a voyage;the model was constructed based on an artificial neural network.The parameters of the neural network model were refined repeatedly through the historical navigation data of the test ship,and then the trained black-box model was used to predict the future fuel consumption of the test ship.Compared with other fuel consumption calculation methods,the black-box model method showed higher accuracy and applicability.ZHANG Guangyu WANG Hongbo ZHAO Wei GUAN Zhiying LI Pengfei 2021Journal of Ocean University of China2021,20,1:7
16Quantificational indexes for design and evaluation of copper staves for blast furnaces显示文摘The quantificational and normative design is the precondition of improving the design of copper staves for blast furnaces. Based on a 3-dimensional temperature field calculation model,from the view point of heat transfer and long campaigns note with the core of forming accretion,the forming-accretion-ability(FAA)and the rib hot surface maximum temperature difference(ΔT_(max))as quantificational indexes to direct and evaluate the design of copper staves for blast furnaces were presented.The application of the two indexes in design essentially embodies the new long campaigns in the stage of design.With the application of the two indexes, good results can be obtained.Firstly,it was suggested that the rib height of a copper stave can be reduced to 15 mm,which is a new method and theory for the reduction of copper staves.Secondly,the influence of insert on FAA andΔT_(max)is decided by the volume of insert.According to this,the principle of design for the hot surface geometry of copper staves was put forward that the ratio of the rib hot surface to the copper stave hot surface(abbreviated as the ratio of rib to stave)must be maintained in the range of 45% to 55%; for the present copper stave with a 35-40 mm thick rib,the ratio of rib to stave in the range of 50% to 55% can optimize the design of copper staves;for the copper stave with a smaller rib thickness,for example 15 mm,the ratio of rib to stave in the range of 45% to 50% can optimize the design of copper staves.It can be summarized that the thicker the rib thickness,the larger is the ratio of rib to stave.Liang Qian Susen Cheng Hongbo Zhao 2008Journal of University of Science and Technology Beijing2008,15,1:6
17Ability to detect weak effective seismic signals by utilizing chaotic vibrator system显示文摘Taking the advantage of CVS (Chaotic Vibrator System) sensitivity of large-scale periodic phase-state response to quasi-periodic or periodic signals,a series of numerical experiments were made to understand the ability of CVS to detect weak effective seismic signals in the common-shot seismic record distorted by strong stochastic noise. The re-sults demonstrate that the large-scale periodic phase-states of CVS are correlated with the signal composition of the quasi-periodic wavelet sequence constructing from horizontal moveout of seismic events,noise strength and the noise distortion de-gree to signal. For the same kind of events,the higher the noise distortion degree is,the lower the detectable SNR can be reached by CVS. For seismic data with the same noise distortion degree,the closer the scanning seismic velocity (the trial moveout ve-locity) approaches to the accurate velocity,the higher the detectable SNR can be reached by CVS. More-over,the truncating scanning velocities form an asymmetric belt,which indirectly makes CVS achieve a large-scale periodic phase-state and then the ratio of wavelet distortion coefficients in events can be a biggish variable scope.LI Yue YANG Baojun YUAN Ye ZHAO Xueping LIN Hongbo 2006Chinese Science Bulletin2006,51,24:6
18Effect of different levels of corn steep liquor addition on fermentation characteristics and aerobic stability of fresh rice straw silage显示文摘The object of this study was to determine the proper mixing ratio of fresh rice straw to corn steep liquor(CSL) to obtain a high protein content silage feed. The following experimental silages were generated: the control(C1), composed of fresh rice straw without CSL additive, mixed with CSL in the ratios of 4:1(C4),3:1(C3) and 2:1(C2). Lactic acid bacteria(LAB) inoculant was applied at the rate of 50 mL/kg(fresh basis)of forage to achieve a final application rate of 1 x 10~6 cfu/g of fresh matter(FM). Duplicate silos for each treatment were opened after 0,3, 7,10,20,30,45 and 60 d for microbiological and chemical analysis. The results showed that the addition of CSL significantly increased crude protein(CP) contents, and decreased neutral detergent fiber(NDF) and acid detergent fiber(ADF) contents of treatments after 60 d of ensiling(P < 0.05). The lactic acid contents in C4 and C3 were significantly higher than that in C1(P <0.05). In summary, mixing fresh rice straw with CSL at addition levels of 4:1(C4) and 3:1(C3) can improve the fermentation quality and nutrient composition of fresh rice straw silage. However, a large proportion of CSL(C3) had a negative impact on the aerobic stability of fresh rice straw.Xinxin Li Wenbin Xu Jinshan Yang Hongbo Zhao Hangshu Xin Yonggen Zhang 2016Animal Nutrition2016,,4:6
19Vegetation evolution on the central Chinese Loess Plateau since late Quaternary evidenced by elemental carbon isotopic composition显示文摘There are many controversial issues in loess studies such as natural vegetation types on the Chinese Loess Plateau during the historical periods and the spatial and temporal evolution of C3/C4 plants. Elemental carbon isotopic composition (δ13Cec) in the loess section may offer new evidence for these problems. Elemental carbon (EC) is produced by incomplete combustion of vegetation, and its carbon isotopic composition has a very small difference from that of the formal vegetation, then δ13Cec can be used as a record to recover the changes of vegetation. Elemental carbon was extracted by applying the oxidation method from the loess-paleosol sequence in the central Chinese Loess Plateau, and its carbon isotope composition was analyzed by the isotope mass spectrometer. The results showed that the vegetation in this region was a mixed type of C3 and C4 plants, dominated with C3 plants in most of the time. Since late Quaternary, C3/C4 plants may not follow a simple glacial-interglacial cycle mode on the Chinese Loess Plateau, but showing fluctuations. C3 plants increased gradually in L4 period, and more C3 plants occurred during S3 period, and C4 plants increased again during L3―L2 periods, after that, C3 plants dominated again during S1―S0 periods. During periods of paleosol development, C3 plants were abundant in S3 and S1, and there were more C4 plants in S2 and S0. During periods of loess sedimen- tation, there were more C3 plants in L4 and L1, and there were more C4 plants in L3 and L2. On the or- bital timescale, the vegetation variations revealed by δ13Cec record are consistent with the results of pollen data and also similar to the results obtained by organic carbon isotopic composition since the last glacial period.ZHOU Bin SHEN ChengDe ZHENG HongBo ZHAO MeiXun SUN YanMin 2009Chinese Science Bulletin2009,54,12:6
20Probabilistic analysis of tunnel displacements based on correlative recognition of rock mass parameters显示文摘Displacement is vital in the evaluations of tunnel excavation processes,as well as in determining the postexcavation stability of surrounding rock masses.The prediction of tunnel displacement is a complex problem because of the uncertainties of rock mass properties.Meanwhile,the variation and the correlation relationship of geotechnical material properties have been gradually recognized by researchers in recent years.In this paper,a novel probabilistic method is proposed to estimate the uncertainties of rock mass properties and tunnel displacement,which integrated multivariate distribution function and a relevance vector machine(RVM).The multivariate distribution function is used to establish the probability model of related random variables.RVM is coupled with the numerical simulation methods to construct the nonlinear relationship between tunnel displacements and rock mass parameters,which avoided a large number of numerical simulations.Also,the residual rock mass parameters are taken into account to reflect the brittleness of deeply buried rock mass.Then,based on the proposed method,the uncertainty of displacement in a deep tunnel of CJPL-II laboratory are analyzed and compared with the in-situ measurements.It is found that the predicted tunnel displacements by the RVM model closely match with the measured ones.The correlations of parameters have significant impacts on the uncertainty results.The uncertainty of tunnel displacement decreases while the reliability of the tunnel increases with the increases of the negative correlations among rock mass parameters.When compared to the deterministic method,the proposed approach is more rational and scientific,and also conformed to rock engineering practices.Minzong Zheng Shaojun Li Hongbo Zhao Xiang Huang Shili Qiu 2021Geoscience Frontiers2021,12,4:6
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