期刊文献+
共找到2,446篇文章
< 1 2 123 >
每页显示 20 50 100
Mapping epistasis and environment × QTX interaction based on four-omics genotypes for the detected QTX loci controlling complex traits in tobacco 被引量:4
1
作者 Liyuan Zhou Ruiyuan Li +6 位作者 Longjiang Fan Yuewei Shi Zhihong Wang Shengdong Xie Yijie Gui Xueliang Ren Jun Zhu 《The Crop Journal》 SCIE CAS 2013年第2期151-159,共9页
Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and pheno... Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and phenotype for 60 leaf samples at four developmental stages, from three plant architectural positions and for three cultivars that were grown in two locations. Association mapping was conducted to detect genetic variants at quantitative trait SNP(QTS) loci, quantitative trait transcript(QTT) differences,quantitative trait protein(QTP) variability, and quantitative trait metabolite(QTM) changes,which can be summarized as QTX locus variation. The total heritabilities of the four-omics loci for both traits tested were 23.60% for epistasis and 15.26% for treatment interaction.Epistasis and environment × treatment interaction had important impacts on complex traits at all-omics levels. For decreasing chromium content and increasing total sugar in tobacco leaf, six methylated loci can be directly used for marker-assisted selection, and expression of ten QTTs, seven QTPs and six QTMs can be modified by selection or cultivation. 展开更多
关键词 Association MAPPING study complex trait analysis EPISTASIS effects environment × treatment INTERACTION Plant architecture control QTX locus MAPPING
下载PDF
Huanggang Intrusive Complexin Northern Tongbai Area:Island-Arc Tectonic Environment and Its Geological Significance 被引量:3
2
作者 Zhang Li Zhang Hongfei Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1998年第3期37-41,共5页
The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex be... The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex belongs to calc alkaline series. Geochemical characteristics of major and trace elements show that the complex was derived from the fractional crystallization of co source magma. It is suggested that the complex was formed in island arc tectonic environment and was closely related to the northward subduction of the Erlangping back arc basin. Thus, the subduction of the back arc basin can induce the island arc type magmatism similar to the one formed in the setting of ocean plate subduction. 展开更多
关键词 Huanggang intrusive complex island arc tectonic environment geochemistry northern Tongbai area North Qinling.
下载PDF
Path Planning Method Based on D^(*) lite Algorithm for Unmanned Surface Vehicles in Complex Environments 被引量:8
3
作者 YAO Yan-long LIANG Xiao-feng +4 位作者 LI Ming-zhi YU Kai CHEN Zhe NI Chong-ben TENG Yue 《China Ocean Engineering》 SCIE EI CSCD 2021年第3期372-383,共12页
In recent decades,path planning for unmanned surface vehicles(USVs)in complex environments,such as harbours and coastlines,has become an important concern.The existing algorithms for real-time path planning for USVs a... In recent decades,path planning for unmanned surface vehicles(USVs)in complex environments,such as harbours and coastlines,has become an important concern.The existing algorithms for real-time path planning for USVs are either too slow at replanning or unreliable in changing environments with multiple dynamic obstacles.In this study,we developed a novel path planning method based on the D^(*) lite algorithm for real-time path planning of USVs in complex environments.The proposed method has the following advantages:(1)the computational time for replanning is reduced significantly owing to the use of an incremental algorithm and a new method for modelling dynamic obstacles;(2)a constrained artificial potential field method is employed to enhance the safety of the planned paths;and(3)the method is practical in terms of vehicle performance.The performance of the proposed method was evaluated through simulations and compared with those of existing algorithms.The simulation results confirmed the efficiency of the method for real-time path planning of USVs in complex environments. 展开更多
关键词 path planning unmanned surface vehicle D^(*)lite algorithm complex environment
下载PDF
Recent Progress in Reinforcement Learning and Adaptive Dynamic Programming for Advanced Control Applications 被引量:1
4
作者 Ding Wang Ning Gao +2 位作者 Derong Liu Jinna Li Frank L.Lewis 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第1期18-36,共19页
Reinforcement learning(RL) has roots in dynamic programming and it is called adaptive/approximate dynamic programming(ADP) within the control community. This paper reviews recent developments in ADP along with RL and ... Reinforcement learning(RL) has roots in dynamic programming and it is called adaptive/approximate dynamic programming(ADP) within the control community. This paper reviews recent developments in ADP along with RL and its applications to various advanced control fields. First, the background of the development of ADP is described, emphasizing the significance of regulation and tracking control problems. Some effective offline and online algorithms for ADP/adaptive critic control are displayed, where the main results towards discrete-time systems and continuous-time systems are surveyed, respectively.Then, the research progress on adaptive critic control based on the event-triggered framework and under uncertain environment is discussed, respectively, where event-based design, robust stabilization, and game design are reviewed. Moreover, the extensions of ADP for addressing control problems under complex environment attract enormous attention. The ADP architecture is revisited under the perspective of data-driven and RL frameworks,showing how they promote ADP formulation significantly.Finally, several typical control applications with respect to RL and ADP are summarized, particularly in the fields of wastewater treatment processes and power systems, followed by some general prospects for future research. Overall, the comprehensive survey on ADP and RL for advanced control applications has d emonstrated its remarkable potential within the artificial intelligence era. In addition, it also plays a vital role in promoting environmental protection and industrial intelligence. 展开更多
关键词 Adaptive dynamic programming(ADP) advanced control complex environment data-driven control event-triggered design intelligent control neural networks nonlinear systems optimal control reinforcement learning(RL)
下载PDF
Detection of Point Sound Source Using Beamforming Technique in Complex Environments
5
作者 Navid Nassaji Masoume Shafieian 《Open Journal of Acoustics》 2018年第2期23-35,共13页
Detection and localization of acoustic events in an environment are important to protect the military and civilian installations. While there are finite paths of wave propagation in simple or low reverberant environme... Detection and localization of acoustic events in an environment are important to protect the military and civilian installations. While there are finite paths of wave propagation in simple or low reverberant environments, in complex environments (e.g. a complex urban environment) obstacles such as terrain or buildings introduce multipath propagations, reflections and diffractions which make source localization challenging. Therefore, numeric results of simulated models (simplified and Fort Benning urban models) of 3D complex environments can highly help in real applications. Some of the conventional beamformer algorithms have been used in order to localize point sound source. Analyzing results shows that MRCB beamformer has better performance than others in this issue and its accuracy superiority is more than 3 m in simplified urban model and 5 m in Fort Benning urban model with respect to the SOC. Moreover, due to possible uncertainties between the numerical model and the actual environment such as squall effect, temperature gradient etc., sensitivity of the beamformers to temperature gradient is investigated which shows higher robustness of SOC beamformer than the MRCB beamformer. According to the results, due to gradient temperature uncertainty the accuracy degradation of the SOC is about 1m while in MRCB it alters from 0.5 m to 20 m approximately at all SNRs. COMSOL Multiphysics has been used to numerically simulate the environment of wave propagation. 展开更多
关键词 Source LOCALIZATION BEAMFORMING MRCB BEAMFORMER complex environment Temperature GRADIENT
下载PDF
Dynamic analysis of wind turbine tower structures in complex ocean environment
6
作者 Guanzhong LIU Xingming GUO Li ZHU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第7期999-1010,共12页
Studying and analyzing the dynamic behavior of offshore wind turbines are of great importance to ensure the safety and improve the efficiency of such expensive equipments.In this work,a tapered beam model is proposed ... Studying and analyzing the dynamic behavior of offshore wind turbines are of great importance to ensure the safety and improve the efficiency of such expensive equipments.In this work,a tapered beam model is proposed to investigate the dynamic response of an offshore wind turbine tower on the monopile foundation assembled with rotating blades in the complex ocean environment.Several environment factors like wind,wave,current,and soil resistance are taken into account.The proposed model is ana-lytically solved with the Galerkin method.Based on the numerical results,the effects of various structure parameters including the taper angle,the height and thickness of the tower,the depth,and the diameter and the cement filler of the monopile on the funda-mental natural frequency of the wind turbine tower system are investigated in detail.It is found that the fundamental natural frequency decreases with the increase in the taper angle and the height and thickness of the tower,and increases with the increase in the diameter of the monopile.Moreover,filling cement into the monopile can effectively im-prove the fundamental natural frequency of the wind turbine tower system,but there is a critical value of the amount of cement maximizing the property of the monopile.This research may be helpful in the design and safety evaluation of offshore wind turbines. 展开更多
关键词 wind turbine tower structure dynamic analysis tapered beam fundamen-tal natural frequency complex ocean environment
下载PDF
Comprehensive analysis of safe mining to heavy and steep coal seam under complex geophysics environment 被引量:3
7
作者 王宁波 李立波 +1 位作者 来兴平 柴鑫 《Journal of Coal Science & Engineering(China)》 2008年第3期378-381,共4页
In virtue of effect of N-S intensive ground stress and mining disturbance to +579E2EB_(1+2) mining site at Weihuliang Mine,the dip angle and section height is 65° and 52 m,respectively,the collapses happed freque... In virtue of effect of N-S intensive ground stress and mining disturbance to +579E2EB_(1+2) mining site at Weihuliang Mine,the dip angle and section height is 65° and 52 m,respectively,the collapses happed frequently during mining.Firstly,mining condi- tions,spatial structure and parameters were investigated.Then physical simulation and dynamic numerical tracing and elaborate simulation relating roof and top-coal were ap- plied based on 2D-Block Program and quantitative regularity of stress at variable depths had been estimated.Furthermore,it was manifested that effective measures,i.e.,fast mining,control symmetrical top-coal-caving at dip and strike directions,optimizing ventila- tion system,active-stereo preventing gas were performed successfully in mining practice. Ultimately,the derived dynamic hazard were prevented so as to safety mining. 展开更多
关键词 复杂地质环境 重深煤井 崩落开采法 EDZ
下载PDF
SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION
8
作者 孙家跃 石春山 李有谟 《Journal of Rare Earths》 SCIE EI CAS CSCD 1990年第2期110-116,共7页
In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond d... In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence. 展开更多
关键词 Eu SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN complex OXIDES EFFECT OF THE CRYSTAL environment AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM ION
下载PDF
Microfacies and Depositional Environments of Miocene Isolated Carbonate Platforms from Central Luconia, Offshore Sarawak, Malaysia 被引量:2
9
作者 Hammad Tariq JANJUHAH José Antonio GáMEZ VINTANED +3 位作者 Ahmed Mohamed Ahmed SALIM Ibrahima FAYE Mumtaz Muhammad SHAH Deva Prasad GHOSH 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第5期1778-1796,共19页
The Luconia Province-offshore Sarawak-is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental char... The Luconia Province-offshore Sarawak-is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental characteristics of the Tertiary carbonates in the key sector of Central Luconia.We study the sedimentology and petrography of core samples from a well in Central Luconia, for which thirteen microfacies have been identified reflecting different depositional settings. This is the first microfacies scheme elaborated for Luconian carbonates. Lithofacies and microfacies distribution are compatible with deposition in a reef complex, originating around a framework reef, within the euphotic zone. Sediments were deposited in environments of backreef, reef crest, and forereef. The fair weather wave base is marked by the presence of coralline red algae, foraminifera, decreasing degree of bioclast fragmentation and other microfacies features. As a result, a depositional-environmental model is constructed, depicting a reef complex built around a framework reef developed on the margin of an isolated platform. In addition, an innovative, preliminary time series analysis of facies, microfacies and depositional environment data reveal the existence of seasonal cycles in the stacking patterns of facies and microfacies. 展开更多
关键词 central Luconia SEDImentOLOGY MICROFACIES reef complex depositional environments time series
下载PDF
GRANITOIDS,VOLCANIC ROCKS AND CHERTS FROM NORTH ALTYN TAGH,NW CHINA: IMPLICATION FOR THE TECTONIC ENVIRONMENT DISCRIMINATION
10
作者 Chen Xuanhua\+1,Wang Xiaofeng\+1,Chen Zhengle\+1,George Gehrels\+2,Yin An\+3 2.Department of Geosciences, University of Arizona,Tucson,AZ 85721,USA 3.Department of Earth and Space Science 《地学前缘》 EI CAS CSCD 2000年第S1期249-250,共2页
Granitoids,volcanic rocks and cherts,mainly of early Paleozoic,in northern Altyn Tagh(Fig.1) are analyzed here for the purpose of the determination of the tectonic environments and their development since Early Paleoz... Granitoids,volcanic rocks and cherts,mainly of early Paleozoic,in northern Altyn Tagh(Fig.1) are analyzed here for the purpose of the determination of the tectonic environments and their development since Early Paleozoic.(1) Granitoids\ The collection of 128 main\|element petrochemical data from North Altyn Tagh area shows that most of the granitoids here are granites and granodiorites of calc\|alkaline series.They consist mainly of metaluminous and peraluminous in Shand’s index,and only one of them,which belongs to Mesozoic,is peralkaline.Most of the granitoids plot in the IAG+CAG+CCG fields in the Maniar and Piccoli’s diagrams (1989) for tectonic discrimination of granitoids.IAG (Island arc granitoids)and CAG (Continental arc granitoids) can be distinguished for Early and Late Paleozoic granitoids,and maybe some CCG (Continental collision granitoids) for Early Paleozoic.Granitoids of Mesozoic and Cenozoic inherited the characteristics of those of Paleozoic.Destructive active plate margin (pre\|plate collision)and Anatectic magmatism(syn\|orogenic,S\|type granites)are distinguished (Fig.2)for Paleozoic granitoids using de la Roche R 1\| R 2 multicationic diagram (Batchelor and Bowden,1985).Mesozoic and Cenozoic granitoids inherited the characteristics of Anatectic magmatism (syn\|orogenic)of these early ones,and post\|orogenic(A\|type)granites occurred in Mesozoic.The mechanism for magma formation is mainly partial melting. 展开更多
关键词 GRANITOIDS VOLCANIC ROCKS CHERTS TECTONIC environ ment Altyn Tagh
下载PDF
Porcine Respiratory Pathogens in Swine Farms Environment in Mexico
11
作者 Victor M. Loera-Muro Abraham Loera-Muro +5 位作者 Marcela Morfín-Mata Mario Jacques Francisco J. Avelar-González Flor Ramírez-Castillo Elsa M. Ramírez-López Alma L. Guerrero-Barrera 《Open Journal of Animal Sciences》 2014年第4期196-205,共10页
Respiratory pathogens are the main health problem in the swine industry worldwide. These pathogens are transmitted by direct contact between animals or by aerosols and however are not well known yet, if the environmen... Respiratory pathogens are the main health problem in the swine industry worldwide. These pathogens are transmitted by direct contact between animals or by aerosols and however are not well known yet, if the environment works as its reservoir, inoculum and/or dispersion medium. The objective of this study was to determine the presence of respiratory pathogens in environmental samples from swine farms in Aguascalientes, Mexico, through of PCR and RT-PCR techniques. The bacteria Actinobacillus pleuropneumoniae and Pasteurella multocida were found viable in samples from water, food, soil and air. Streptococcus suis was found in a viable state in water samples. Haemophilus parasuis, Porcine Reproductive and Respiratory Syndrome virus and Swine Influenza virus (H1N1 and H3N2) were detected in drinking water samples. Mycoplasma hyopneumoniae and Porcine Circovirus type 2 (PCV2) were not detected in environmental samples. These results suggest that the environment of the farms acts as a reservoir, inoculum and/or vehicle of dispersion for these pathogens except for M. hyopneumoniae and PCV2. 展开更多
关键词 environment RESPIRATORY PATHOGEN PORCINE RESPIRATORY DISEASE complex PCR and RT-PCR
下载PDF
Contrasting Depositional Environment of Iron Formation at Endengue Area, NW Congo Craton, Southern Cameroon: New Insights from Trace and Rare Earth Elements Geochemistry
12
作者 Robinson Tchatchueng Timoléon Ngnotué +3 位作者 Evine Laure Tanko Njiosseu Sylvestre Ganno Hervé Wabo Jean Paul Nzenti 《International Journal of Geosciences》 2021年第3期280-306,共27页
The Endengue Banded Iron Formation (BIF) is located in the northwestern edge of the Congo craton in Cameroon. Here<span style="font-family:Verdana;">,</span><span style="font-family:Verda... The Endengue Banded Iron Formation (BIF) is located in the northwestern edge of the Congo craton in Cameroon. Here<span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> we report geochemical data of trace and rare earth elements (REE) of the Endengue BIF samples from the Archean Ntem complex and investigate their environmental setting. Two types of BIF occur at Endengue area, both containing minimal contamination from terrestrial material. Total REE (</span><span style="line-height:99%;font-family:Verdana;">Σ</span><span style="font-family:Verdana;">REE) contents in the Type 1 BIF are extremely low, ranging from 0.34 to 1.83 ppm, similarly to pure chemical sediments while Type 2 BIF displays</span><span style="font-family:;" "=""> </span><span style="line-height:99%;font-family:Verdana;">Σ</span><span style="font-family:Verdana;">REE contents ranging from 2.98 to 24.26 ppm. The PAAS-normalized REE</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">+</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Y patterns of the two BIF types display LREE enrichment relative to HREE and weak positive Eu anomaly, most likely suggesting that the source of iron and siliceous of the Endengue BIFs is mainly from the contribution of low-temperature hydrothermal alteration of the crust. Type 1 BIF shows very low Nd content (<1 ppm) with positive correlation between Nd and Ce/Ce</span><span style="font-family:Verdana;">*</span><span style="font-family:Verdana;"> and positive Ce anomalies which suggests suboxic or anoxic seawater similar to the depositional environment of Elom BIF in Archean Ntem complex. In contrast, Type 2 BIF displays low to moderate Nd contents (1 and 100 ppm with the exception of sample LBR65) with negative correlation between Nd and Ce/Ce</span><span style="font-family:Verdana;">*</span><span style="font-family:Verdana;"> and negative Ce anomalies. These features indicate precipatation of Type 2 BIF from oxic iron-rich solution that changed to oxidized surface by rapid precipitation of the hydrothermal Fe. The Endengue BIFs were deposited in the continental margin ocean in presence of low-temperature hydrothermal fluids mixed with seawater, similar to Paleoproterozoic Kpwa</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">Atog Boga BIFs within the Nyong group and other Paleoproterozoic Superior</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">type BIFs worldwide.</span> 展开更多
关键词 Endengue BIFs Suboxic or Anoxic Oxic Depositional environment Ntem complex
下载PDF
Environmental Radiation Measurement and Assessment of Natural Radioactivity in Soil, Water and Vegetation 被引量:1
13
作者 Nandi-Esom Chariette Ereh Meng Zhang 《Journal of Applied Mathematics and Physics》 2018年第11期2330-2337,共8页
Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human a... Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (40K), are only present due to natural processes, a few isotopes, e.g. tritium (3H), result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238 (238U), can be affected by human activity because of the constant exposure of Human beings to radiation caused by terrestrial, extra-terrestrial and anthropogenic radio nuclides, it is necessary to determine and estimate the activity of various radio nuclides in environmental media such as vegetation, soil, and water. In the present research, the activities of 226Ra, 232Th and 40K are measured in soil, vegetation and water samples, collected from Yangdong District, Yangxi County, and Yangjiang County of Guangdong Province, China using an HPGe based gamma spectrometry system. The measured mean activity of 226Ra, 232Th and 40K in soil samples was found to be 31.19 ± 1.2, 47.00 ± 2.30 and 589.31 ± 17.52 Bqkg-1, respectively. The measured mean activity of these radionuclides in all water samples was found to be below minimum detectable activity. The measured mean activity of 226Ra, 232Th and 40K in vegetation samples was 19.92 ± 3.09, 25.36 ± 8.11 and 4982.94 ± 85.68 Bqkg-1, respectively. No anthropogenic 137Cs was detected in these environmental samples. Mean radium equivalent activity (Raeq), external radiation hazard index (Hex), internal radiation hazard index (Hin) and absorbed dose rate (D) for the area under study were determined as 142.92 Bqkg-1, 0.38, 0.47 and 66.47 nGyh-1, respectively. The annual effective dose equivalent (AEDE) varied in the range from 0.03 to 0.12 mSvy-1. It is concluded that the surveyed area do not pose any significant radiological risk to the population and environment. 展开更多
关键词 High PURITY GERMANIUM Detector RADIUM THORIUM POTASSIUM RADIUM Equivalent Activity Radiation HAZARD Indices and environment Measure-ment
下载PDF
Transmission Planning and Invest ment in the Competitive Environment
14
作者 George Gross 《现代电力》 2006年第2期F0002-F0002,I0001,共2页
关键词 Transmission Planning and Invest ment in the Competitive environment
下载PDF
西天山乌孙山花岗岩和闪长岩年代学、地球化学及岩石成因
15
作者 孙吉明 马中平 +1 位作者 贠杰 王国强 《西北地质》 CAS CSCD 北大核心 2024年第3期59-72,共14页
笔者选取位于伊犁盆地内乌孙山北缘察布查尔林场花岗岩为研究对象,其地球化学、地质年代学和岩石成因研究对于探讨西天山南缘壳幔岩浆作用具有较重要的指示意义。岩石地球化学特征显示二长花岗岩属高钾钙碱性准铝质-弱过铝质岩石系列;... 笔者选取位于伊犁盆地内乌孙山北缘察布查尔林场花岗岩为研究对象,其地球化学、地质年代学和岩石成因研究对于探讨西天山南缘壳幔岩浆作用具有较重要的指示意义。岩石地球化学特征显示二长花岗岩属高钾钙碱性准铝质-弱过铝质岩石系列;轻稀土富集,弱的Eu负异常(δEu=0.74~0.84),富集大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素特征,Zr/Hf=42~44,部分样品中含有少量的刚玉标准矿物,显示出壳源花岗岩的特征。闪长岩Al_(2)O_(3)、FeOT、CaO含量明显高于二长花岗岩,Na_(2)O和K_(2)O含量低于二长花岗岩,属于高钾准铝质岩石系列;轻稀土富集,显示出Eu的轻微正异常(δEu=0.90~1.24),富集大离子亲石元素,亏损Nb、Ta等高场强元素,此外,闪长岩还显示出具有高Sr(Sr>400×10^(-6))低Y(12.83×10^(-6))及Yb(1.34×10^(-6))和高Mg^(#)特征,其源岩应为俯冲板片上覆地幔部分熔融产物。二者均显示出岛弧岩浆的特征。二长花岗岩锆石U-Pb年龄为(361.7±1.8)Ma;形成于晚泥盆世末期,结合前人的研究资料认为在~360 Ma由于南天山洋板片的回撤或俯冲流体参与,上覆地幔发生部分熔融产生了基性岩浆,岩浆上涌过程中提供大量的热导致地壳发生部分熔融形成了酸性岩浆,两种岩浆发生不均匀混合作用。上涌的岩浆引起地幔对流,导致伊犁地块内部出现一定的伸展作用(弧后伸展作用)。 展开更多
关键词 西天山 花岗岩及包体 锆石U-PB定年 岩石地球化学 构造环境
下载PDF
复杂人机共融场景中人体姿态识别及避碰策略综述
16
作者 高春艳 梁彧浩 +2 位作者 李满宏 张明路 孙立新 《科学技术与工程》 北大核心 2024年第5期1749-1755,共7页
智能机器人与人类智慧的融合,即人机协作共融,已经实现了将机器人的机械优势和人类的高级认知能力集中于同一个工作架构之中,能够在复杂环境中协同作业,从而提高效率。针对复杂的人机共融场景,特别是机器人在诸如光线条件变化、背景干... 智能机器人与人类智慧的融合,即人机协作共融,已经实现了将机器人的机械优势和人类的高级认知能力集中于同一个工作架构之中,能够在复杂环境中协同作业,从而提高效率。针对复杂的人机共融场景,特别是机器人在诸如光线条件变化、背景干扰以及运动过程,对比总结了基于机器视觉的人体姿态识别方法和基于机器学习的避碰策略,详细比较各类方法的研究现状及应用,并探讨了基于深度学习的目标识别和避碰方法的发展及应用。 展开更多
关键词 人机协作共融 复杂环境 人体姿态识别 避碰
下载PDF
复杂载荷、极端环境下焊接结构疲劳寿命预测研究综述
17
作者 董志波 王程程 +4 位作者 李承昆 李峻臣 赵耀邦 历吴恺 徐爱杰 《中国机械工程》 EI CAS CSCD 北大核心 2024年第5期829-839,共11页
焊接接头易出现缺陷和应力集中,在疲劳载荷作用下将成为疲劳裂纹萌生和扩展的薄弱区域。与均质材料相比,接头各区域微观组织及应力局部化使得焊接结构疲劳问题进一步复杂化。区别于理想实验条件,实际焊接结构服役环境复杂,疲劳寿命预测... 焊接接头易出现缺陷和应力集中,在疲劳载荷作用下将成为疲劳裂纹萌生和扩展的薄弱区域。与均质材料相比,接头各区域微观组织及应力局部化使得焊接结构疲劳问题进一步复杂化。区别于理想实验条件,实际焊接结构服役环境复杂,疲劳寿命预测须考虑环境因素与焊接结构耦合特性。为此,对影响焊接结构的内在因素进行总结分析,从复杂载荷和极端服役环境两方面对现有焊接结构寿命预测模型进行综述,结合最新研究进展对改进焊接结构疲劳寿命评估方法提出建议。 展开更多
关键词 焊接结构 影响因素 复杂载荷 极端环境 寿命预测模型
下载PDF
复杂环境下基于视觉/惯性的单兵自主定位性能评估
18
作者 常伟 黄土顺 +1 位作者 韩枫 陈刚 《现代电子技术》 北大核心 2024年第13期117-122,共6页
针对在卫星信号拒止等复杂环境下单兵自主定位精度低的问题,提出基于视觉/惯性测量单元(IMU)的单兵自主定位技术。将高效的IMU初始化方法融合到ORB-SLAM3算法并应用于单兵自主定位技术中,评估了单兵实时运动整体定位精度,重点分析了改进... 针对在卫星信号拒止等复杂环境下单兵自主定位精度低的问题,提出基于视觉/惯性测量单元(IMU)的单兵自主定位技术。将高效的IMU初始化方法融合到ORB-SLAM3算法并应用于单兵自主定位技术中,评估了单兵实时运动整体定位精度,重点分析了改进ORB-SLAM3算法在单目/IMU、双目/IMU下的定位精度准确性和鲁棒性。实验表明:在复杂树林环境下,单兵在基于视觉/IMU自主定位时,改进算法的IMU初始化时间最少提高了10 s,双目/IMU的估计轨迹曲线更加吻合实际运动轨迹曲线。在绝对轨迹误差的各项评估指标中,双目/IMU比单目/IMU的均方根误差提高了24.67%,而且定位精度和鲁棒性都要优于单目/IMU,为城市巷战中单兵自主高精度定位的实现提供了一种切实可行的思路和举措。 展开更多
关键词 单兵自主定位 惯性 视觉 复杂环境 单目 双目
下载PDF
物联网环境下复杂光纤通信传输网络节点调度
19
作者 钟耀霞 苏华 翟书娟 《激光杂志》 CAS 北大核心 2024年第4期196-201,共6页
为了解决物联网环境下,光纤通信传输网络节点能耗高、调度效率低的问题,提出一种物联网环境下复杂光纤通信传输网络节点调度方法。在物联网环境下,分析光纤通信传输网络节点的分布情况,根据动态联盟理论,以最快调度速度和最小投资为目标... 为了解决物联网环境下,光纤通信传输网络节点能耗高、调度效率低的问题,提出一种物联网环境下复杂光纤通信传输网络节点调度方法。在物联网环境下,分析光纤通信传输网络节点的分布情况,根据动态联盟理论,以最快调度速度和最小投资为目标,构建复杂光纤通信传输网络节点调度模型。通过蚁群和粒子群算法相结合的融合算法展开全部搜索,获取最佳调度方案,实现光纤通信传输网络节点调度。实验结果表明,所提方法的节点平均能耗在6.0 mJ以下,LBF值始终高于0.20,且节点调度耗时始终低于200 ms,具有良好的调度效果。 展开更多
关键词 物联网环境 复杂光纤通信 传输网络节点 节点调度方法
下载PDF
复杂信息环境下的情报快速反应机制研究
20
作者 苏成 赵润博 +1 位作者 黄雁宁 赵筱媛 《情报学报》 CSCD 北大核心 2024年第5期528-537,共10页
在科技飞速发展和大国博弈日益白热化的背景下,情报成为抢占国家发展先机的重要工具之一。在复杂信息环境的情报生产新环境和决策新要求下,本文以如何实现情报支撑国家战略决策为研究问题,通过文献调研与案例分析等方法,在总结梳理相关... 在科技飞速发展和大国博弈日益白热化的背景下,情报成为抢占国家发展先机的重要工具之一。在复杂信息环境的情报生产新环境和决策新要求下,本文以如何实现情报支撑国家战略决策为研究问题,通过文献调研与案例分析等方法,在总结梳理相关理论和实践经验的基础上,对情报快速反应机制的内涵、特征和决策支撑场景进行深入探究。本文创新性地提出一套适用于复杂信息环境下的“3+5+9情报快速反应机制”,以“早发现、早预判、早报告、早决策、早应对”为五大核心目标,以“联动协调、信息监测、信息资源、情报分析、应急处置、技术支撑、专家协作、组织保障、跟踪评估监督”为九大支撑子体系,适用于常态化监测、回应关切和突发应急三类重要决策支撑场景的情报工作机制,以期为未来相关实践提供较为扎实的理论基础。 展开更多
关键词 情报快速反应机制 复杂信息环境 常态化监测 回应关切 突发应急 决策支持
下载PDF
上一页 1 2 123 下一页 到第
使用帮助 返回顶部