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Spatial Process of Green Infrastructure Changes Associated with Rapid Urbanization in Shenzhen,China 被引量:6
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作者 CHANG Qing LI Shuangcheng +2 位作者 WANG Yanglin WU Jiansheng XIE Miaomiao 《Chinese Geographical Science》 SCIE CSCD 2013年第1期113-128,共16页
Through a case study of Shenzhen City,China,this study focused on a quantitative method for analyzing the spatial processes involved in green infrastructure changes associated with rapid urbanization.Based on RS,GIS a... Through a case study of Shenzhen City,China,this study focused on a quantitative method for analyzing the spatial processes involved in green infrastructure changes associated with rapid urbanization.Based on RS,GIS and SPSS statistics software,the approach includes selection of the square analysis units and representative landscape metrics,quantification of the change types of landscape metrics in all analysis units through two indices and hierarchical cluster analysis of the above analysis units with different landscape metric change types(i.e.spatial attributes).The analyses verify that there is a significant sequence of continuous changes in green infrastructure in Shenzhen.They are the perforation,the segmentation,the fragmentation,the evanescence and the filling-in processes,which have a good spatio-temporal correspondence with urbanization and reflect the synthetic influence of urban planning,government policies and landforms.Compared with other studies on quantifying the spatial pattern,this study provides an alternative probe into linking the spatial pattern to spatial processes and the corresponding ecological processes in the future.These spatio-temporal processes offer many opportunities for identifying,protecting and restoring key elements in an urban green infrastructure network for areas in the early stages of urbanization or for non-urbanized areas. 展开更多
关键词 spatial process landscape metrics dynamic change green infrastructure URBANIZATION
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2-D DIRECTION FINDING OF COHERENT SIGNALS VIA TEMPORO-SPATIAL PROCESSING 被引量:2
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作者 Jin Liang Yao Minli Yin Qinye 《Journal of Electronics(China)》 2000年第1期31-37,共7页
In most wireless communication systems, two-dimensional Directions-Of-Arrival (DOA) of multipath signals need to be found for spatial selective transmission. However, it is quite difficult to find their DOAs due to th... In most wireless communication systems, two-dimensional Directions-Of-Arrival (DOA) of multipath signals need to be found for spatial selective transmission. However, it is quite difficult to find their DOAs due to the coherent nature of multipath signals and considerable computations when performing 2-D searches. In this paper, a new algorithm to estimate 2-D DOA of multiple narrow-band signals is proposed. A DOA cyclic matrix is constructed whose eigenvalues and eigenvectors can be simultaneously used to extract 2-D DOA without 2-D searches. By exploiting the temporal property of cyclostationarity, the signal detection capability is significantly improved. Besides, based on the decorrelation model for mobile terminal signals, the algorithm can be effectively extended to the coherent case without spatial smoothing and the loss of array aperture. Simulation results are given to illustrate the performance of the new algorithm. 展开更多
关键词 DOA Coherent signal Temporo-spatial processing
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Spatial Processing and Coordination Design of Indoor and Outdoor Space
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作者 Yu Liu 《International Journal of Technology Management》 2013年第1期73-76,共4页
From the review of development history of indoor design in China, we can see that it develops rapidly from sprout to expansion, and has large professional scale. It goes through ignorance, misconception and comprehens... From the review of development history of indoor design in China, we can see that it develops rapidly from sprout to expansion, and has large professional scale. It goes through ignorance, misconception and comprehensive understanding. And it has developed into a perfect and independent composite subject. From the perspective of interior design continuing architectural design in time-space dimension, the paper focuses on observing the application analysis of coordinated interior design, which not only provides reference for interior design in China, but also improves the interior design in China. 展开更多
关键词 spatial processing indoor and outdoor coordinated design
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Relative importance of spatial processes and environmental factors in shaping alpine meadow communities 被引量:7
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作者 Qi Li Xue Yang +4 位作者 Janne Soininen Cheng-Jin Chu Jie-Qi Zhang Kai-Liang Yu Gang Wang 《Journal of Plant Ecology》 SCIE 2011年第4期249-258,共10页
Spatial processes and environmental control are the two distinct,yet not mutually exclusive forces of community structuring,but the relative importance of these factors is controversial due to the speciesspecific disp... Spatial processes and environmental control are the two distinct,yet not mutually exclusive forces of community structuring,but the relative importance of these factors is controversial due to the speciesspecific dispersal ability,sensitivity towards environmental variables,organism’s abundance and the effect of spatial scale.In the present paper,we explored spatial versus environmental control in shaping community composition(i.e.b-diversity)and species turnover(i.e.change of b-diversity)at an alpine meadow along a slope aspect gradient on the Qinghai–Tibetan Plateau at different spatial scales of sampling(quadrats and plots),by taking account of seed dispersal mode and abundance.Methods We examined the relative importance of spatial processes and environmental factors using all species and four additional subsets of selected species.Moreover,we attempted to explore the effect of scale(quadrat refers to scale of;0.3 m and plot of;8 m)on their counter balance.The data were analyzed both by variation partitioning and multiple regressions on distance matrices.The spatial structure was modelled using Moran’s eigenvector maps(MEM).Important Findings Both spatial processes and environmental factors were important determinants of the community composition and species turnover.The community composition in the alpine meadow was controlled by spatially structured environment(17.6%),space independent of environment(18.0%)and a negligible effect of environment independent of space(4.4%)at the scale of quadrats.These three components contributed 21.8,9.9 and 13.9%,respectively,at the scale of plots.The balance between the forces at different spatial scales drove community structures along the slope aspect gradient.The importance of environmental factors on b-diversity at alpine meadow increased with scale while that of spatial processes decreased or kept steady,depending on dispersal mode and abundance of species comprising the subset.But the‘pure’effect of spatial processes on species turnover increased with scale while that of environmental factors decreased.This discrepancy highlights that b-diversity and species turnover were determined jointly by spatial processes and environmental factors.We also found that the relative roles of these processes vary with spatial scale.These results underline the importance of considering species-specific dispersal ability and abundance of species comprising the communities and the appropriate spatial scale in understanding the mechanisms of community assembly. 展开更多
关键词 alpine meadow dispersal environmental factor slope aspect spatial process spatial scale
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Relative Contributions of Spatial and Environmental Processes and Biotic Interactions in a Soil Collembolan Community 被引量:1
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作者 SHA Di GAO Meixiang +2 位作者 SUN Xin WU Donghui ZHANG Xueping 《Chinese Geographical Science》 SCIE CSCD 2015年第5期582-590,共9页
Understanding the underlying processes of how communities are structured remains a central question in community ecology. However, the mechanisms of the soil animal community are still unclear, especially for communit... Understanding the underlying processes of how communities are structured remains a central question in community ecology. However, the mechanisms of the soil animal community are still unclear, especially for communities on a small scale. To evaluate the relative roles of biotic interactions and environmental and spatial processes in a soil collembolan community, a field experiment was carried out on a small scale(50 m) in the farmland ecosystem of the Sanjiang Plain, Northeast China. In August and October, 2011, we took 100 samples each month in a 50 m × 50 m plot using a spatially delimited sampling design. Variation partitioning was used to quantify the relative contributions of the spatial and environmental variables. A null model was selected to test for the non-randomness pattern of species co-occurrence and body size in assemblages of collembolans and to test whether the pattern observed was the result of environmental or biotic processes that structured the community on a small scale. The results showed that large variance was accounted for by spatial variables(18.99% in August and 21.83% in October, both were significant). There were relatively lower effects of environmental variation(3.56% in August and 1.45% in October, neither was significant), while the soil water content, soil p H and soybean height explained a significant portion of the variance that was observed in the spatial pattern of the collembolan community. Furthermore, the null model revealed more co-occurrence than expected by chance, suggesting that collembolan communities had a non-random co-occurrence pattern in both August and October. Additionally, environmental niche overlap and the body size ratio of co-occurrence showed that interspecific competition was not influential in collembolan community structuring. Considering all of the results together, the contributions of spatial and environmental processes were stronger than biotic interactions in the small-scale structuring of a soil collembolan community. 展开更多
关键词 spatial process environmental filtering biotic interactions variation partitioning small scale collembolan community
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Bahadur Representation of Nonparametric M-Estimators for Spatial Processes
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作者 Jia CHEN De Gui LI Li Xin ZHANG 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2008年第11期1871-1882,共12页
Under some mild conditions, we establish a strong Bahadur representation of a general class of nonparametric local linear M-estimators for mixing processes on a random field. If the socalled optimal bandwidth hn = O(... Under some mild conditions, we establish a strong Bahadur representation of a general class of nonparametric local linear M-estimators for mixing processes on a random field. If the socalled optimal bandwidth hn = O(|n|^-1/5), n ∈ Z^d, is chosen, then the remainder rates in the Bahadur representation for the local M-estimators of the regression function and its derivative are of order O(|n|^-4/5 log |n|). Moreover, we derive some asymptotic properties for the nonparametric local linear M-estimators as applications of our result. 展开更多
关键词 Bahadur representation local linear M-estimator spatial processes strongly mixing
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Environmental filtering and spatial processes equally contributed to macroinvertebrate metacommunity dynamics in the highly urbanized river networks in Shenzhen, South China
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作者 Zhenyuan Liu Tingting Zhou +4 位作者 Yongde Cui Zhengfei Li Weimin Wang Yushun Chen Zhicai Xie 《Ecological Processes》 SCIE EI 2021年第1期316-327,共12页
Background:Disentangling the relative roles of environmental filtering and spatial processes in structuring ecological communities is a central topic in metacommunity ecology.Metacommunity ecology in the temperate riv... Background:Disentangling the relative roles of environmental filtering and spatial processes in structuring ecological communities is a central topic in metacommunity ecology.Metacommunity ecology in the temperate river ecosystems has been well developed,while less attention has been paid to subtropical urban river networks.Here,we examined the ecological factors and seasonal difference in structuring macroinvertebrates metacommunity assembly in the subtropical urban river networks in Shenzhen,South China.Results:Our results revealed that there was no significant distinction of macroinvertebrate community composition among seasons,with only the relative abundance of Mollusca and Odonata significantly differed in both wet and dry seasons.One possible explanation was that most macroinvertebrates are generally pollution-tolerant taxa characterized with nonseasonal life cycle.In addition,distance-based redundancy analysis and variation partitioning approach revealed that metacommunity was determined equally by the environmental and dispersal-related factors.Further,our results showed that,although a slight temporal variation of relative contribution,the identity and explanation power of ecological factors were different among seasons.Specifically,stronger environmental filtering structuring community dynamics was observed in the dry than wet seasons,which might be owing to higher environmental heterogeneity under a low water-flow condition.Moreover,we detected that the influence of spatial processes was stronger in the wet than dry seasons,indicating an obvious dispersal processes due to high connectivity among sites.Conclusion:Overall,our results revealed that environmental and spatial factors equally explained variations of macroinvertebrate metacommunity,implying the necessity of considering dispersal-related processes structuring ecological communities in river bioassessment programs.Moreover,degraded habitat conditions and water quality were the predominant factors that affected macroinvertebrate communities,indicating the significance and feasibility of improving local abiotic conditions to sustain local biodiversity.Further,our findings revealed the importance of seasonal dynamics of these urban river networks in structuring macroinvertebrate metacommunity.Thereby,our study improves the understanding of ecological processes governing macroinvertebrate metacommunity and underlines the idea that community ecology studies should go beyond the single snapshot survey in river networks. 展开更多
关键词 Community assembly Seasonal variation Macroinvertebrate metacommunity Environmental filtering spatial processes Urban river
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Progress of the research methodologies on the temporal and spatial process of LUCC 被引量:40
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作者 LIU JiYuan DENG XiangZheng 《Chinese Science Bulletin》 SCIE EI CAS 2010年第14期1354-1362,共9页
After one decade of development,the methods to explore the temporal and spatial process of LUCC (Land Use and Land Cover Change) have been vastly improved; and in some sense a methodology framework used to study the t... After one decade of development,the methods to explore the temporal and spatial process of LUCC (Land Use and Land Cover Change) have been vastly improved; and in some sense a methodology framework used to study the temporal and spatial process is being rapidly developed. The methodology framework is based on the integration of the classical theories of Geography and the recent developed technologies of remote sensing and GIS, which is a new research field to meet the need for scientific information to promote the studies on global change adaptation and sustainable development. It addressed the following:the detection and description of the temporal and spatial process of LUCC, analysis of driving mechanism of LUCC, simulation of LUCC process and evaluation of ecological effect due to LUCC. The formation of methodology framework to study the temporal and spatial process of LUCC, to some extent, has been promoted to tackle the hard-nut topics in science through interdisciplinary efforts among geography, GIS and macro-ecology. The domestic and overseas research trends indicate that the development of detection and analytical technologies of remote sensing information and the methodological innovation of simulating the temporal and spatial process of LUCC, play an important role in promoting the development of methodology framework of the temporal and spatial process of LUCC. The synthetic application of the detection and analytical technologies of LUCC remote sensing information, the construction of multi-source and temporal-spatial data platform and the realization of massive data availability and integration are all kernel components of the methodology framework of the temporal and spatial process of LUCC. We can expect that the research methods system of the temporal and spatial process of LUCC will play a more important role in guiding the research activities of LUCC processes at regional and global levels. 展开更多
关键词 土地利用变化 时空过程 生态系统 岩石稳定性
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Tempo-spatial rupture process of the 1997Mani, Xizang(Tibet), China earthquake of Ms=7.9 被引量:9
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作者 许力生 陈运泰 《Acta Seismologica Sinica(English Edition)》 CSCD 1999年第5期495-506,共12页
An earthquake of Ms=7.4 occurred in Mani, Xizang (Tibet), China on November 8, 1997. The moment tensor ofthis earthquake was inverted using the long period body wave form data from China Digital Seismograph Network(CD... An earthquake of Ms=7.4 occurred in Mani, Xizang (Tibet), China on November 8, 1997. The moment tensor ofthis earthquake was inverted using the long period body wave form data from China Digital Seismograph Network(CDSN). The apparent source time functions (AS TFs) were retrieved from P and S waves, respectively, using thedeconvolution technique in frequency domain, and the tempo-spatial rupture process on the fault plane was imagedby inverting the azimuth dependent AS TFs from different stations. The result of the moment tensor inversionindicates that the P and T axes of earthquake-generating stress field were nearly horizontal, with the P axis in theNNE direction (29), the T axis in the SEE direction (122) and that the NEE-SWW striking nodal plane andNNW-SSE striking nodal plane are mainly left-lateral and right-lateral strike-slip, respectively; that this earthquakehad a scalar seismic moment of 3.4xl02o N. .m, and a moment magnitude of Mw=7.6. Taking the aftershock distribution into account, we proposed that the earthquake rupture occurred in the fault plane with the strike of 250,the dip of 88 and the rake of 19. On the basis of the result of the moment tensor inversion, the theoretical seismograms were synthesized, and then the AS T Fs were retrieved by deconvoving the synthetic seismograms fromthe observed seismograms. The A S T Fs retrieved from the P and S waves of different stations identically suggestedthat this earthquake was of a simple time history, whose ASTF can be approximated with a sine function with thehalf period of about 10 s. Inverting the azimuth dependent A S T Fs from P and S waveforms led to the imageshowing the tempo-spatial distribution of the rupture on the fault plane. From the 'remembering' snap-shots, therupture initiated at the western end of the fault, and then propagated eastward and downward, indicating an overallunilateral rupture. However, the slip distribution is non-uniform, being made up of three sub-areas, one in thewestern end, about 10 km deep ('western area'), another about 55 kin away from the western end and about 35 Iondeep ('eastern area'), the third about 30 km away from the western end and around 40 km deep ('central area').The total rupture area was around 70 km long and 60 km wide. From the 'forgetting' snap-shots, the rupturingappeared quite complex, with the slip occurring in different position at different time, and the earthquake being ofthe characteristics of 'healing pulse'. Another point we have to stress is that the locations in which the ruptureinitiated and terminated were not where the main rupture took place. Eventually, the static slip distribution wascalculated, and the largest slip values of the three sub-areas were 956 cm, 743 cm and 1 060 cm, for the western.eastern and central areas, respectively. From the slip distribution, the rupture mainly distributed in the fault about70 km eastern to the epicenter; from the aftershock distribution. however, the aftershocks were very sparse in thewest to the epicenter while densely clustered in the east to the epicenter It indicated that the Maul Ms=7.9 earthquake was resulted from the nearly eastward extension of the NEE-SWW to nearly E-W striking fault in thenorthwestern Tibetan plateau. 展开更多
关键词 Mani earthquake Xizang(Tibet) tempo-spatial rupture process source time function
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Spatial batch optimal design based on self-learning Gaussian process models for LPCVD processes 被引量:1
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作者 孙培 谢磊 陈荣辉 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第12期1958-1964,共7页
Low pressure chemical vapor deposition(LPCVD) is one of the most important processes during semiconductor manufacturing.However,the spatial distribution of internal temperature and extremely few samples makes it hard ... Low pressure chemical vapor deposition(LPCVD) is one of the most important processes during semiconductor manufacturing.However,the spatial distribution of internal temperature and extremely few samples makes it hard to build a good-quality model of this batch process.Besides,due to the properties of this process,the reliability of the model must be taken into consideration when optimizing the MVs.In this work,an optimal design strategy based on the self-learning Gaussian process model(GPM) is proposed to control this kind of spatial batch process.The GPM is utilized as the internal model to predict the thicknesses of thin films on all spatial-distributed wafers using the limited data.Unlike the conventional model based design,the uncertainties of predictions provided by GPM are taken into consideration to guide the optimal design of manipulated variables so that the designing can be more prudent Besides,the GPM is also actively enhanced using as little data as possible based on the predictive uncertainties.The effectiveness of the proposed strategy is successfully demonstrated in an LPCVD process. 展开更多
关键词 Batchwise LPCVD Transport processes spatial distribution Gaussian process model Optimal design
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Effect of varying spatial orientations on build time requirements for FDM process: A case study 被引量:1
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作者 Sandeep Rathee Manu Srivastava +1 位作者 Sachin Maheshwari Arshad Noor Siddiquee 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2017年第2期92-100,共9页
In this research, effect of varying spatial orientations on the build time requirements for fused deposition modelling process is studied. Constructive solid geometry cylindrical primitive is taken as work piece and m... In this research, effect of varying spatial orientations on the build time requirements for fused deposition modelling process is studied. Constructive solid geometry cylindrical primitive is taken as work piece and modeling is accomplished for it. Response surface methodology is used to design the experiments and obtain statistical models for build time requirements corresponding to different orientations of the given primitive in modeller build volume. Contour width, air gap, slice height, raster width, raster angle and angle of orientation are treated as process parameters. Percentage contribution of individual process parameter is found to change for build time corresponding to different spatial orientations. Also, the average of build time requirement changes with spatial orientation. This paper attempts to clearly discuss and describe the observations with an aim to develop a clear understanding of effect of spatial variations on the build time for Fused Deposition Modelling process. This work is an integral part of process layout optimization and these results can effectively aid designers specially while tackling nesting issues. 展开更多
关键词 FUSED deposition modeling spatial orientation process parameters Response Surface Methodology BUILD TIME
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Spatial and temporal rupture process of the January 26, 2001, Gujarat, India, M_S=7.8 earthquake 被引量:1
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作者 许力生 陈运泰 高孟潭 《Acta Seismologica Sinica(English Edition)》 CSCD 2002年第5期469-483,共15页
The source parameters, such as moment tensor, focal mechanism, source time function (STF) and temporal-spatial rupture process, were obtained for the January 26, 2001, India, MS=7.8 earthquake by inverting waveform da... The source parameters, such as moment tensor, focal mechanism, source time function (STF) and temporal-spatial rupture process, were obtained for the January 26, 2001, India, MS=7.8 earthquake by inverting waveform data of 27 GDSN stations with epicentral distances less than 90? Firstly, combining the moment tensor inversion, the spatial distribution of intensity, disaster and aftershocks and the orientation of the fault where the earthquake lies, the strike, dip and rake of the seismogenic fault were determined to be 92? 58?and 62? respectively. That is, this earthquake was a mainly thrust faulting with the strike of near west-east and the dipping direction to south. The seismic moment released was 3.51020 Nm, accordingly, the moment magnitude MW was calculated to be 7.6. And then, 27 P-STFs, 22 S-STFs and the averaged STFs of them were determined respectively using the technique of spectra division in frequency domain and the synthetic seismogram as Greens functions. The analysis of the STFs suggested that the earthquake was a continuous event with the duration time of 19 s, starting rapidly and ending slowly. Finally, the temporal-spatial distribution of the slip on the fault plane was imaged from the obtained P-STFs and S-STFs using an time domain inversion technique. The maximum slip amplitude on the fault plane was about 7 m. The maximum stress drop was 30 MPa, and the average one over the whole rupture area was 7 MPa. The rupture area was about 85 km long in the strike direction and about 60 km wide in the down-dip direction, which, equally, was 51 km deep in the depth direction. The rupture propagated 50 km eastwards and 35 km westwards. The main portion of the rupture area, which has the slip amplitude greater than 0.5 m, was of the shape of an ellipse, its major axis oriented in the slip direction of the fault, which indicated that the rupture propagation direction was in accordance with the fault slip direction. This phenomenon is popular for strike-slip faulting, but rather rare for thrust faulting. The eastern portion of the rupture area above the initiation point was larger than the western portion below the initiation point, which was indicative of the asymmetrical rupture. In other words, the rupturing was kind of unilateral from west to east and from down to up. From the snapshots of the slip-rate variation with time and space, the slip rate reached the largest at the 4th second, that was 0.2 m/s, and the rupture in this period occurred only around the initiation point. At the 6th second, the rupture around the initiation point nearly stopped, and started moving outwards. The velocity of the westward rupture was smaller than that of the eastward rupture. Such rupture behavior like a circle mostly stopped near the 15th second. After the 16th second, only some patches of rupture distributed in the outer region. From the snapshots of the slip variation with time and space, the rupture started at the initiation point and propagated outwards. The main rupture on the area with the slip amplitude greater than 5 m extended unilaterally from west to east and from down to up between the 6th and the 10th seconds, and the western segment extended a bit westwards and downwards between the 11th and the 13th seconds. The whole process lasted about 19 s. The rupture velocity over the whole rupture process was estimated to be 3.3 km/s. 展开更多
关键词 focal mechanism source time function temporal-spatial rupture process
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An overview of the spatial patterns of land surface processes over arid and semiarid regions 被引量:6
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作者 Jian Zeng Jie Shen Qiang Zhang 《Research in Cold and Arid Regions》 2010年第4期288-297,共10页
With data from the project Collaborative Observation of Semi-arid/Arid Regions in North China, collected during July and September 2008, the spatial patterns of land surface processes over arid and semiarid regions ha... With data from the project Collaborative Observation of Semi-arid/Arid Regions in North China, collected during July and September 2008, the spatial patterns of land surface processes over arid and semiarid regions have been investigated based on the ordinary Kriging interpolation approach. Generally, for the radiation processes, downward and upward short-wave radiation have a uniformly increasing trend with latitude, but the spatial patterns of long-wave radiation present notable regional differences: both upward and downward long-wave radiation increase with latitude in the west of North China, while in the east they vary inversely with latitude, suggesting surface temperature and clouds respectively have feedbacks to the long-wave radiation in the west and east of North China. The surface net radiation basically has a negative latitudinal trend. Long-wave radiation budget plays an important role in the spatial pattern of surface net radiation, particularly in the east of North China, although short-wave radiation budget largely determines the magnitude of surface net radiation. For the energy processes, latent and sensible heat flux varies conversely with latitude: more available land surface energy is consumed by evaporating soil water at lower latitudes while more is used for heating the atmosphere at higher latitudes. A soil heat flux maximum and minimum are found in Loess Plateau and Qinghai Plateau respectively, and a maximum is seen in the northeast China. 展开更多
关键词 land surface radiation processes land surface energy processes spatial pattern arid and semiarid regions
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Estimation of spatially distributed processes using mobile sensor networks with missing measurements
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作者 江正仙 崔宝同 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第2期109-115,共7页
This paper investigates the estimation problem for a spatially distributed process described by a partial differential equation with missing measurements.The randomly missing measurements are introduced in order to be... This paper investigates the estimation problem for a spatially distributed process described by a partial differential equation with missing measurements.The randomly missing measurements are introduced in order to better reflect the reality in the sensor network.To improve the estimation performance for the spatially distributed process,a network of sensors which are allowed to move within the spatial domain is used.We aim to design an estimator which is used to approximate the distributed process and the mobile trajectories for sensors such that,for all possible missing measurements,the estimation error system is globally asymptotically stable in the mean square sense.By constructing Lyapunov functionals and using inequality analysis,the guidance scheme of every sensor and the convergence of the estimation error system are obtained.Finally,a numerical example is given to verify the effectiveness of the proposed estimator utilizing the proposed guidance scheme for sensors. 展开更多
关键词 ESTIMATION spatially distributed process mobile sensor network missing measurements
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Polarimetric super-resolution algorithm for radar range imaging via spatial smoothing processing
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作者 LI Zhang-feng ZHAO Guo-qiang +3 位作者 LI Shi-yong LIU Fang SUN Hou-jun TAO Ran 《Journal of Beijing Institute of Technology》 EI CAS 2016年第3期397-402,共6页
A full-polarimetric super-resolution algorithm with spatial smoothing processing is presented for one-dimensional(1-D)radar imaging.The coherence between scattering centers is minimized by using spatial smoothing pr... A full-polarimetric super-resolution algorithm with spatial smoothing processing is presented for one-dimensional(1-D)radar imaging.The coherence between scattering centers is minimized by using spatial smoothing processing(SSP).Then the range and polarimetric scattering matrix of the scattering centers are estimated.The impact of different lengths of the smoothing window on the imaging quality is mainly analyzed with different signal-to-noise ratios(SNR).Simulation and experimental results show that an improved radar super-resolution range profile and more precise estimation can be obtained by adjusting the length of the smoothing window under different SNR conditions. 展开更多
关键词 super-resolution imaging MUSIC imaging polarimetric radar spatial smoothing processing(SSP) signal-to-noise ratio(SNR)
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Processing Constrained K Closest Pairs Query in Spatial Databases 被引量:1
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作者 LIU Xiaofeng LIU Yunsheng XIAO Yingyuan 《Wuhan University Journal of Natural Sciences》 EI CAS 2006年第3期543-546,共4页
In this paper, constrained K closest pairs query is introduced, wbich retrieves the K closest pairs satisfying the given spatial constraint from two datasets. For data sets indexed by R trees in spatial databases, thr... In this paper, constrained K closest pairs query is introduced, wbich retrieves the K closest pairs satisfying the given spatial constraint from two datasets. For data sets indexed by R trees in spatial databases, three algorithms are presented for answering this kind of query. Among of them, two-phase Range+Join and Join+Range algorithms adopt the strategy that changes the execution order of range and closest pairs queries, and constrained heap-based algorithm utilizes extended distance functions to prune search space and minimize the pruning distance. Experimental results show that constrained heap-base algorithm has better applicability and performance than two-phase algorithms. 展开更多
关键词 spatial databases query processing R-TREE closest pairs query constrained closest pairs query
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Spatial analysis of plant detritus processing in a Mediterranean River type: the case of the River Tirso Basin, Sardinia, Italy
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作者 Maurizio Pinna Franca Sangiorgio +1 位作者 Alessio Fonnesu Alberto Basset 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2003年第2期227-240,共14页
The river continuum concept represents the most general framework addressing the spatial variation of both structure and function in river ecosystems. In the Mediterranean ecoregion, summer drought events and dams con... The river continuum concept represents the most general framework addressing the spatial variation of both structure and function in river ecosystems. In the Mediterranean ecoregion, summer drought events and dams constitute the main sources of local disturbance to the structure and functioning of river ecosystems occurring in the river basin. In this study, we analysed patterns of spatial variation of detritus processing in a 7th order river of the Mediterranean ecoregion(River Tirso, Sardinia-Italy) and in three 4th order sub-basins which were exposed to different summer drought pressures. The study was carried out on Phragmites australis and Alnus glutinosa leaf detritus at 31 field sites in seasonal field experiment Detritus processing rates were higher for Alnus glutinosa than for Phragmites australis plant detritus. Processing rates of Alnus glutinosa leaves varied among seasons and study sites from 0.006 d -1 to 0.189 d -1 and those of Phragmites australis leaves ranged from 0.0008 d -1 to 0.102 d -1, with the lowest values occurring at sites exposed to summer drought. Seasons and sites accounted for a significant proportion of such variability. Alder detritus decay rates generally decreased with increasing stream order, while reed detritus decay rates generally increased on the same spatial gradient. Summer drought events affected these spatial patterns of variation by influencing significantly the decay rates of both plant detritus. The comparisons among and within sub-basins showed strong negative influence of summer drought on detritus processing rates. Similarly, in the entire River Tirso basin decay rates were always lower at disturbed than at undisturbed sites for each stream order; decay rates of reed detritus remained lower at those sites even after the end of the disturbance events, while alder decay rates recovered rapidly from the summer drought perturbations. The different recovery of the processing rates of the two leaves could also explain the different patterns of spatial variation observed between the two leaves. 展开更多
关键词 ecosystem processes spatial patterns DISTURBANCE Mediterranean ecosystem type
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Study on Spatial Windows of Stationary Processes in Communication System
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作者 LIU Gan RUAN You-lin 《通讯和计算机(中英文版)》 2007年第1期46-48,共3页
关键词 通信系统 空间窗 交通系统 无线通信
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LATE MESOZOIC SUBDUCTION PROCESS BENEATH SOUTHEASTERN CHINA AS REVEALEDBY THE SPATIAL- TEMPORAL PATTERN OFMAGMATISM
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作者 WANG Yang 1, DENG Jin fu 1, WANG Ji yang 2 and XIONG Liang ping 2 (1. Division of Petrology, China University of Geosciences, Beijing 100083, China 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China) 《Geotectonica et Metallogenia》 2001年第1期68-70,共3页
Southeastern China covers an extensive area from the lowerreaches of the Yangtze Riverto the southeast coastof China mainland.One of its main geological features isthe extensiveJura- Cretaceous (Yanshanian) magmatism ... Southeastern China covers an extensive area from the lowerreaches of the Yangtze Riverto the southeast coastof China mainland.One of its main geological features isthe extensiveJura- Cretaceous (Yanshanian) magmatism and related metallogenesis. Recently,some re-searchers advocate the mantle plume model as an explanation,but all of their evidences artoo ambiguous.Meanwhile,the seaward convex shape of the SE China coastline,which isdominantly composed of Jura- Cretaceous batholiths and volcanic strata,implies thatit was aconvergent margin between SE China continent and the palaeo- Pacific plate during the lateMesozoic era.Fora betterunderstanding on the relation among magmatism,tectonic regimeand dynamics,the spatial- temporal pattern of late Mesozoic (180 - 90 Ma) igneous rocks isconstructed by nearly2 0 0 isotope age valuesfrom literatures.Among these age values,mostwere obtained by Rb- Sr isochron method,and others from zircon U- Pb or40  Ar- 3 展开更多
关键词 LATE MESOZOIC SUBDUCTION process BENEATH SOUTHEASTERN CHINA AS REVEALEDBY THE spatial TEMPORAL PATTERN OFMAGMATISM AS
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唐宋元时期乐温县治考
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作者 马剑 《历史地理研究》 CSSCI 2024年第1期32-37,156,共7页
唐代乐温县并不治于今重庆长寿区仁和场,其迁治长江边也并非在明初。唐初设县时,乐温治于龙溪河下游山间的长寿区邻封镇,永安治于河口处的羊角堡。开元末两县合并后,乐温治所迁至废永安县治附近,于长江北岸、桃花溪西岸的河街一带设治,... 唐代乐温县并不治于今重庆长寿区仁和场,其迁治长江边也并非在明初。唐初设县时,乐温治于龙溪河下游山间的长寿区邻封镇,永安治于河口处的羊角堡。开元末两县合并后,乐温治所迁至废永安县治附近,于长江北岸、桃花溪西岸的河街一带设治,并沿用至清嘉庆年间。厘清这一空间发展过程有助于理解唐宋政区和治所调整在功能取向上由堂奥转向门户的历史趋势,并为当下地方文脉延续和地名命名、更名提供依据。 展开更多
关键词 乐温县 永安县 迁治 空间过程 地名
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