Distribution Of Patches Research Articles

Dynamics of Population Patch Distribution

The problem of selection by the patch population in the absence of information on the utility of the patch, that is, the volume of its energy resources, is considered. This problem relates to the theory of optimal foraging. U. Dieckman proposed an approach to modeling the population patch distribution. The approach is based on a utility function that takes into account the amount of resources in a patch, the population − patch distance, and the measure of information certainty on patch utility. In this case, the Boltzmann distribution is used to describe the population patch distribution. And U. Dieckman considered a static problem that does not take into account the change in the position of the population with time. In this paper, we propose a dynamic system that describes the population patch distribution, which depends on the utility of the patch. In addition the utility varies with time as a result of distance variations. The Boltzmann distribution is a particular solution of the proposed system of differential equations. The Lyapunov stability condition for the Boltzmann distribution is obtained.The utility functions of the patches, which depend on the population − patch distance and on the measure of the information certainty, are introduced. As a result, in the two-dimensional case, a space R2is divided into areas of preferred utility. Such a partition is a generalization of the Voronoi diagram.

Spatial Variation of Urban Thermal Environment and Its Relation to Green Space Patterns: Implication to Sustainable Landscape Planning

The rapid changes of land covers in urban areas are one of major environmental concerns because of their environmental impacts. Such land cover changes include the transformation of green space to impervious surface, and the increase of land surface temperature (LST). The objective of this study was to examine the spatial variation of urban landscape composition and configuration, as well as their influences on LST in Suzhou City, China. Landsat-8 image was processed to extract land covers and retrieve LSTs that were used to study relationship between spatial variation of LST and land covers. The results indicated that there was a significantly negative correlation between mean LST and green space coverage along the urban–rural gradients. With every 10% increased green space coverage, the mean LST drop was about 1.41 °C. A grid-base analysis performed at various grid sizes indicated that an increase in the percentage of surface water body area has a greater cooling effect of the mean LST than a vegetation increase. The mean LST had a significantly negative correlation with both the shape and aggregation indexes of the green space patches. Our results suggest that the sustainable landscape planning of green space in a typical city with a large water area should include both the vegetation and the surface water covers. The increased percentage of vegetation and surface water covers had the greatest cooling effect on an urban thermal environment, which is one of the ecosystem services that green space provides. A dense distribution of green space patches with complex shapes should be considered in urban sustainable landscape planning for increasing ecosystem services.

Visual adaptive tracking for monocular omnidirectional camera

This paper presents a sophisticated patch-based visual tracking algorithm using an omnidirectional camera with distortion adaptation. The omnidirectional camera is modeled using the equivalent projection theory, so that a nonlinear deformed neighbourhood can be accurately estimated in the image plane, which significantly facilitates feature coding. In order to improve the omnidirectional tracking performance, a patch-based multi-feature matching method is proposed under a probability framework. In particular, the distributions of patches covering key parts of the target are weighted adaptively according to their joint-feature response, which is able to track target robustly and filter out the outliers effectively. Extensive experiments have been conducted to verify the performance of the proposed omnidirectional tracking algorithm, which obtains promising results on challenging datasets and outperforms many state-of-the-art methods.

Effects of forest structure and harvest‐induced edges on predation risk

ABSTRACTManaged forest systems have implications for wildlife conservation because of their direct influence on condition and distribution of forest patches on the landscape. Spatial arrangement, structure, and composition of patches can influence reproductive outcomes for breeding birds by mediating nest site selection, survival, and predator–prey dynamics. Few studies have explored effects of local and adjacent forest‐stand structure and harvest‐induced edges on nest predation risk. Therefore, during summer 2014, we conducted artificial nest experiments within an intensively managed loblolly pine (Pinus taeda) landscape in Mississippi, USA. We used survival models to quantify effects of forest stand structure and proximity to harvest‐induced edges on apparent predation risk (APR). We conducted vegetation surveys and placed artificial nests (n = 146) at systematic distances from edges between 4 different pine stand types (Class 1: newly established stands; Class 2: 3–5 yr old; Class 3: 5–10 yr old; and Class 4: >10 yr old and postthinned). We sampled 4 stand pairs, each consisting of a Class 1 stand adjacent to a stand type of Class 1 (n = 4), 2 (n = 3), 3 (n = 4), or 4 (n = 4), and developed 15 a priori models relating APR to edge and vegetation characteristics. Apparent predation risk tended to be low and negatively related to edge where adjacent stands featured high proportion of shrub cover and vegetation density. We did not find strong evidence to support increased risk of nest predation near edges. These results were consistent with findings from studies in similar landscape contexts and suggest edges in forest‐dominated landscapes do not increase relative risk of nest predation. Rather, we found that APR was lowest in stands featuring dense shrub and vegetation cover that developed following clearcut harvest. Results of our study highlight some implications of forest harvest on reproductive success of birds, particularly those using early successional vegetation. © 2018 The Wildlife Society.

Impacts of Environmental Heterogeneity on Distribution Pattern of Moss Crust Patches in Temperate Desert in Central Asia

Moss crusts are the highest developmental stage of biological crusts in arid and semiarid ecosystems worldwide. Under natural conditions, elementary functional units of moss crusts are patches. However, to date, the quantitative features, distribution pattern, ecological effect and relationship with environmental factors of moss patches in desert ecosystems remain unclear. In this study, 3303 moss patches in 22 plots and relevant environmental variables were investigated and quantified in the Gurbantunggut Desert, China. Thirty-six patch classes were defined. Moss crusts accounted on average for 11.7% of the plot area, and the mean moss patch area was 23.4 cm2. Small patches dominated, indicating a serious fragmentation of moss crusts. Significant density-dependent effects between patch density and size, humped relationships between patch size and moss plant density, and soil water content under moss patches were observed. The overall distribution of moss crusts showed a tendency of moss patch size and moss plant density decreasing from the southeastern part of the desert to the northwestern part, while moss patch density showed the opposite trend. Pearson's correlation analysis and nonmetric multidimensional scaling analysis consistently demonstrated that the distributions of moss patches were dominantly influenced by non-moss crust coverage, sand particle size, latitude, mean annual precipitation (MAP) and mean annual temperature. Of these parameters, fine sand, high MAP and low latitude were beneficial to the development of moss crusts. Consequently, the factors influencing the distribution pattern of moss crusts are complex and contain the soil factor, current climatic conditions and natural and human disturbances.

Changes in forest cover in Sudety Mountains during the last 250 years: patterns, drivers, and landscape-scale implications for nature conservation

Historical ecology gives a reference point to explain the contemporary state of particular ecosystems as well as entire landscapes. In this study, we examined the quantitative changes in forest cover in the central part of the Sudety Massif (area ca. 1,120 km<sup>2</sup>) during the last 250 years. The information regarding forest patch distribution and its changes was derived by comparison of maps from 1747 and the 1970s drawn at scales of 1:33,000 and 1:25,000, respectively. To examine the effect of environmental variables (topography and soil conditions) and human population density on forest patch distribution and its changes (afforestation, deforestation), a set of 100 circular plots with a diameter of 1 km was established. The influence of explanatory variables was examined using regression tree methods. Changes at the level of the entire landscape were tested using a set of 25 landscape windows (5 × 5 km each). We found that the overall forest cover increased to 36.4% in the twentieth century from 30.4% in the middle of the eighteenth century. The ancient forests constituted 59% of the total forest area existing more recently. The forests in the eighteenth century occurred mostly on steep slopes, deep valley bottoms, and summits. The land relief explains more than half of the total variation in forest distribution (<em>R</em><sup>2</sup> = 0.56). The effects of soil type and human population density were negligible. The contemporary forest pattern results from both land relief and the historical pattern of human population density in the middle of the eighteenth century (<em>R</em><sup>2</sup> = 0.64), while the effect of soil type was negligible. The pattern of deforestation (<em>R</em><sup>2</sup> = 0.53) and afforestation (<em>R</em><sup>2</sup> = 0.36) results from both land relief as well as recent and nineteenth-century human population density. About 83% of the recent forest area is in physical contact with patches of the ancient forest, which provides an optimistic outlook for the migration of ancient forest species into new areas. Furthermore, changes in landscape structure reveal increased connectivity among forest patches, with potential benefits for the migration of forest species with long-range dispersal.

Increasing connectivity between metapopulation ecology and landscape ecology.

Metapopulation ecology and landscape ecology aim to understand how spatial structure influences ecological processes, yet these disciplines address the problem using fundamentally different modeling approaches. Metapopulation models describe how the spatial distribution of patches affects colonization and extinction, but often do not account for the heterogeneity in the landscape between patches. Models in landscape ecology use detailed descriptions of landscape structure, but often without considering colonization and extinction dynamics. We present a novel spatially explicit modeling framework for narrowing the divide between these disciplines to advance understanding of the effects of landscape structure on metapopulation dynamics. Unlike previous efforts, this framework allows for statistical inference on landscape resistance to colonization using empirical data. We demonstrate the approach using 11yr of data on a threatened amphibian in a desert ecosystem. Occupancy data for Lithobates chiricahuensis (Chiricahua leopard frog) were collected on the Buenos Aires National Wildlife Refuge (BANWR), Arizona, USA from 2007 to 2017 following a reintroduction in 2003. Results indicated that colonization dynamics were influenced by both patch characteristics and landscape structure. Landscape resistance increased with increasing elevation and distance to the nearest streambed. Colonization rate was also influenced by patch quality, with semi-permanent and permanent ponds contributing substantially more to the colonization of neighboring ponds relative to intermittent ponds. Ponds that only hold water intermittently also had the highest extinction rate. Our modeling framework can be widely applied to understand metapopulation dynamics in complex landscapes, particularly in systems in which the environment between habitat patches influences the colonization process.

3D seismic modeling in geothermal reservoirs with a distribution of steam patch sizes, permeabilities and saturations, including ductility of the rock frame

Seismic propagation in the upper part of the crust, where geothermal reservoirs are located, shows generally strong velocity dispersion and attenuation due to varying permeability and saturation conditions and is affected by the brittleness and/or ductility of the rocks, including zones of partial melting. From the elastic-plastic aspect, the seismic properties (seismic velocity, quality factor and density) depend on effective pressure and temperature. We describe the related effects with a Burgers mechanical element for the shear modulus of the dry-rock frame. The Arrhenius equation combined to the octahedral stress criterion define the Burgers viscosity responsible of the brittle-ductile behaviour.The effects of permeability, partial saturation, varying porosity and mineral composition on the seismic properties is described by a generalization of the White mesoscopic-loss model to the case of a distribution of heterogeneities of those properties. White model involves the wave-induced fluid flow attenuation mechanism, by which seismic waves propagating through small-scale heterogeneities, induce pressure gradients between regions of dissimilar properties, where part of the energy of the fast P-wave is converted to slow P (Biot)-wave. We consider a range of variations of the radius and size of the patches and thin layers whose probability density function is defined by different distributions. The White models used here are that of spherical patches (for partial saturation) and thin layers (for permeability heterogeneities). The complex bulk modulus of the composite medium is obtained with the Voigt-Reuss-Hill average. Effective pressure effects are taken into account by using exponential functions.We then solve the 3D equation of motion in the space-time domain, by approximating the White complex bulk modulus with that of a set of Zener elements connected in series. The Burgers and generalized Zener models allows us to solve the equations with a direct grid method by the introduction of memory variables. The algorithm uses the Fourier pseudospectral method to compute the spatial derivatives. It is tested against an analytical solution obtained with the correspondence principle. We consider two main cases, namely the same rock frame (uniform porosity and permeability) saturated with water and a distribution of steam patches, and water-saturated background medium with thin layers of dissimilar permeability. Our model indicates how seismic properties change with the geothermal reservoir temperature and pressure, showing that both seismic velocity and attenuation can be used as a diagnostic tool to estimate the in situ conditions.

Roof planes detection via a second-order variational model

The paper describes a unified automatic procedure for the detection of roof planes in gridded height data. The procedure exploits the Blake-Zisserman (BZ) model for segmentation in both 2D and 1D, and aims to detect, to model and to label roof planes.The BZ model relies on the minimization of a functional that depends on first- and second-order derivatives, free discontinuities and free gradient discontinuities. During the minimization, the relative strength of each competitor is controlled by a set of weight parameters. By finding the minimum of the approximated BZ functional, one obtains: (1) an approximation of the data that is smoothed solely within regions of homogeneous gradient, and (2) an explicit detection of the discontinuities and gradient discontinuities of the approximation.Firstly, input data is segmented using the 2D BZ. The maps of data and gradient discontinuities are used to isolate building candidates and planar patches (i.e. regions with homogeneous gradient) that correspond to roof planes. Connected regions that can not be considered as buildings are filtered according to both patch dimension and distribution of the directions of the normals to the boundary. The 1D BZ model is applied to the curvilinear coordinates of boundary points of building candidates in order to reduce the effect of data granularity when the normals are evaluated. In particular, corners are preserved and can be detected by means of gradient discontinuity.Lastly, a total least squares model is applied to estimate the parameters of the plane that best fits the points of each planar patch (orthogonal regression with planar model). Refinement of planar patches is performed by assigning those points that are close to the boundaries to the planar patch for which a given proximity measure assumes the smallest value. The proximity measure is defined to account for the variance of a fitting plane and a weighted distance of a point from the plane.The effectiveness of the proposed procedure is demonstrated by means of its application to urban digital surface models characterized by different spatial resolutions. Results are presented and discussed along with some promising developments.

Vegetation change alters soil profile δ15N values at the landscape scale

The assessment of spatial variation in soil δ15N could provide integrative insights on soil N cycling processes across multiple spatial scales. However, little is known about spatial patterns of δ15N within soil profiles in arid and semiarid ecosystems, especially those undergoing vegetation change with a distinct shift in dominance and/or functional type. We quantified how changes from grass to woody plant dominance altered spatial patterns of δ15N throughout a 1.2 m soil profile by collecting 320 spatially-specific soil cores in a 160 m × 100 m subtropical savanna landscape that has undergone encroachment by Prosopis glandulosa (an N2-fixer) during the past century. Leaf δ15N was comparable among different plant life-forms, while fine roots from woody species had significantly lower δ15N than herbaceous species across this landscape. Woody encroachment significantly decreased soil δ15N throughout the entire soil profile, and created horizontal spatial patterns of soil δ15N that strongly resembled the spatial distribution of woody patches and were evident within each depth increment. The lower soil δ15N values that characterized areas beneath woody canopies were mostly due to the encroaching woody species, especially the N2-fixer P. glandulosa, which delivered 15N-depleted organic matter via root turnover throughout the soil profile. Soil δ15N increased with depth, reached maximum values at intermediate depths, and slightly decreased at greater depths. This vertical pattern may be related to the decrease of 15N-depleted organic matter inputs with depth, and to the presence of a subsurface clay-rich argillic horizon at intermediate depths across this landscape, which may favor the accumulation of 15N-enriched residues. These results indicate that succession from grassland to woodland has altered the spatial variation in soil δ15N across the landscape and to considerable depth, suggesting significant changes in the relative rates of N-inputs vs. N-losses in this subtropical system after vegetation change.

Clustered or scattered? The impact of habitat quality clustering on establishment and early spread

The match between the environmental conditions of an introduction area and the preferences of an introduced species is the first prerequisite for establishment. Yet, introduction areas are usually landscapes, i.e. heterogeneous sets of habitats that are more or less favourable to the introduced species. Because individuals are able to disperse after their introduction, the quality of the habitat surrounding the introduction site is as critical to the persistence of introduced populations as the quality of the introduction site itself. Moreover, demographic mechanisms such as Allee effects or dispersal mortality can hamper dispersal and affect spread across the landscape, in interaction with the spatial distribution of favourable habitat patches. In this study, we investigate the impact of the spatial distribution of heterogeneous quality habitats on establishment and early spread. First, we simulated introductions in one‐dimensional landscapes for different dispersal rates and either dispersal mortality or Allee effects. The landscapes differed by the distribution of favourable and less favourable habitats, which were either clustered into few large aggregates of the same quality or scattered into multiple smaller ones. Second, we tested the predictions of simulations by performing experimental introductions of hymenopteran parasitoids (Trichogramma chilonis) in ‘clustered’ and ‘scattered’ microcosm landscapes. Results highlighted two impacts of the clustering of favourable habitat: by decreasing the risks of dispersal from the introduction site to unfavourable habitat early during the invasion, it increased establishment success. However, by increasing the distance between favourable habitat patches, it also hindered the subsequent spread of introduced species over larger areas.

Biofilms in 3D porous media: Delineating the influence of the pore network geometry, flow and mass transfer on biofilm development

This study investigates the functional correspondence between porescale hydrodynamics, mass transfer, pore structure and biofilm morphology during progressive biofilm colonization of a porous medium. Hydrodynamics and the structure of both the porous medium and the biofilm are experimentally measured with 3D particle tracking velocimetry and micro X-ray Computed Tomography, respectively. The analysis focuses on data obtained in a clean porous medium after 36 h of biofilm growth. Registration of the particle tracking and X-ray data sets allows to delineate the interplay between porous medium geometry, hydrodynamic and mass transfer processes on the morphology of the developing biofilm. A local analysis revealed wide distributions of wall shear stresses and concentration boundary layer thicknesses. The spatial distribution of the biofilm patches uncovered that the wall shear stresses controlled the biofilm development. Neither external nor internal mass transfer limitations were noticeable in the considered system, consistent with the excess supply of nutrient and electron acceptors. The wall shear stress remained constant in the vicinity of the biofilm but increased substantially elsewhere.

The Analysis of Inhomogeneous Barrier Height in In/SnTe/Si/Ag Diode

SnTe thin film layer was fabricated by magnetron sputtering technique on n-Si substrate, and the electrical properties of the In/SnTe/Si/Ag diode structure was investigated by using temperature dependent forward bias current-voltage (I-V) measurements. The main diode parameters were calculated according to the thermionic emission (TE) model and they were found in an abnormal behavior with change in temperate in which zero-bias barrier height ( Φ B 0 ) increases and ideality factor ( n ) decreases with increasing temperature. Therefore, the total current flow though the junction was expressed by the Gaussian distribution (GD) of barrier height. The plot of Φ B 0 vs q 2 kT showed the existence of inhomogeneous barrier formation and evidence for the application of Gaussian function to identify the distribution of low barrier height patches. The mean barrier height was found as 1.274 with the 0.166 eV standard deviation. From the modified Richardson plot, Richardson constant was calculated as 119.5A/cm 2 K 2 in very close agreement with the reported values. Additionally, the effects of the series resistance ( R S ) were analyzed by using Cheung’s function. Distribution of the interface states ( D it ) were extracted from the I-V characteristics and found in increasing behavior with decreasing temperature.

Comparing different ACES Input Device Transforms (IDTs) for the RED Scarlet-X Camera

The RED film cameras are important for professional film productions. Therefore, the Academy of Motion Picture Arts and Science (AMPAS) inserted to their new Input Device Transforms (IDTs) in ACES 1.0.3 among others a couple of conversions from RED color spaces. These transforms are intended to establish a linear relationship of the recorded pixel color to the original light of the scene. To achieve this goal the IDTs are applied to the different RED color spaces, which are provided by the camera manufacturer. This results in a linearization of the recorded image colors. Following this concept the conversion should render comparable results for each color space with an acceptable deviation from the original light of the scene. In color science color space conversions need a documentation of the three main components of the individual color spaces: primaries, whitepoint and transfer function. For the RED colorspaces in question these parameters are only available for the REDWideGamutRGB color space, whereas the other color spaces are not documented. For this reason the behavior of the color conversion can only be tested, but not calculated. The goal of this paper is to compare the results of the color conversions of the main RED color spaces: REDWideGamutRGB, REDcolor4 and REDdragoncolor2. Additionally a conversion to the for television usage important color space REC2020 (ITU-R BT.2020) is added. The test setup contains a GretagMacbeth ColorChecker, which is recorded by a RED Scarlet-X camera and a mobile spectrometer (rgbphotonics Qmini). The latter captures the spectral distribution of the individual ColorChecker patches under the same lighting conditions. To compare the results, the recordings of both devices were converted to the CIE xy-chromaticity diagram using The Foundry Nuke11X. Additionally a comparison to reference data provided by the ACES document TB- 2014-004 is included. Finally it is reviewed if the ACES IDT concept is working for the RED Scarlet-X camera.

Integrating airborne lidar and satellite imagery to model habitat connectivity dynamics for spatial conservation prioritization

The application of regional-level airborne lidar (light detection and ranging) data to characterize habitat patches and model habitat connectivity over large landscapes has not been well explored. Maintaining a connected network of habitat in the presence of anthropogenic disturbances is essential for regional-level conservation planning and the maintenance of biodiversity values. We quantified variation in connectivity following simulated changes in land cover and contrasted outcomes when different conservation priorities were emphasized. First, we defined habitat patches using vegetation structural attributes identified via lidar. Second, habitat networks were constructed for different forest types and assessed using network connectivity metrics. And finally, land cover change scenarios were simulated using a series of habitat patch removals, representing the impact of implementing different spatial prioritization schemes. Networks for different forest structure types produced very different patch distributions. Conservation scenarios based on different schemes led to contrasting changes during land cover change simulations: the scheme prioritizing only habitat area resulted in immediate near-term losses in connectivity, whereas the scheme considering both habitat area and their spatial configurations maintained the overall connectivity most effectively. Adding climate constraints did not diminish or improve overall connectivity. Both habitat area and habitat configuration should be considered in dynamic modeling of habitat connectivity under changing landscapes. This research provides a framework for integrating forest structure and cover attributes obtained from remote sensing data into network connectivity modeling, and may serve as a prototype for multi-criteria forest management and conservation planning.

To Investigate the Flow Structure of Discontinuous Vegetation Patches of Two Vertically Different Layers in an Open Channel

In the present study, the flow structure of discontinuous double-layered vegetation patches was investigated using a 3D Reynolds stress turbulence model (RSM). The channel domain was built using GAMBIT (Geometry and Mesh Building Intelligent Toolkit). For the simulation and postprocessing, FLUENT (ANSYS) was used to analyze the distribution of the mean velocity, Reynolds stresses, and other flow properties against two different flow conditions. The results captured by the turbulence model at specific locations and the cross section are presented in the form of various velocity profiles and contour plots. In the gap portion, the velocity was visibly lower than that in the vegetation areas, while the influence of patch distribution was not visible in the overlying flow layer. The velocity profiles at critical locations were categorized by numerous modulation points and velocity projections close to the bed, principally for positions straight after the vegetation structures. A distinction in the velocity at the topmost of the smaller vegetation structure was prominent. Reynolds stresses, turbulent kinetic energy, and turbulence intensity exhibited large fluctuations inside the vegetation regions and just behind the vegetation structures compared with in the gap regions.

Simulating urban growth in a megalopolitan area using a patch‐based cellular automata

AbstractAlthough traditional cellular automata (CA)‐based models can effectively simulate urban land‐use changes, they typically ignore the spatial evolution of urban patches, due to their use of cell‐based simulation strategies. This research proposes a new patch‐based CA model to incorporate a spatial constraint based on the growth patterns of urban patches into the conventional CA model for reducing the uncertainty of the distribution of simulated new urban patches. In this model, the growth pattern of urban patches is first estimated using a developed indicator that is based on the local variations in existing urban patches. The urban growth is then simulated by integrating the estimated growth pattern and land suitability using a pattern‐calibrated method. In this method, the pattern of new urban patches is gradually calibrated toward the dominant growth pattern through the steps of the CA model. The proposed model is applied to simulate urban growth in the Tehran megalopolitan area during 2000–2006–2012. The results from this model were compared with two common models: cell‐based CA and logistic‐patch CA. The proposed model yields a degree of patch‐level agreement that is 23.4 and 7.5% higher than those of these pre‐existing models, respectively. This reveals that the patch‐based CA model simulates actual development patterns much better than the two other models.

长三角城市群碳排放与城市用地增长及形态的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 长三角城市群碳排放与城市用地增长及形态的关系 DOI: 10.5846/stxb201707101242 作者: 作者单位: 浙江大学公共管理学院土地科学与不动产研究所,浙江大学公共管理学院土地科学与不动产研究所,浙江大学公共管理学院土地科学与不动产研究所,浙江大学公共管理学院土地科学与不动产研究所,浙江大学环境与资源学院农业遥感与信息技术应用研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（41771244）；国家留学基金（201706320200）；中央高校基本科研业务费专项资金资助；浙江大学文科教师教学科研发展专项项目 Relationships between carbon emission, urban growth, and urban forms of urban agglomeration in the Yangtze River Delta Author: Affiliation: Institute of Land Science and Property, School of Public Affairs, Zhejiang University,,Institute of Land Science and Property, School of Public Affairs, Zhejiang University,, Fund Project: National Natural Science Foundation of China（Grant No.41771244）; China Scholarship Council (Grant No.201706320200); supported by “the Fundamental Research Funds for the Central Universities”; supported by “the Teaching and Research Development Funds for Humanities and Social Sciences of Zhejiang University” 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:城市是一种重要的碳源，城市扩张过程中的用地面积增长和空间特征变化均会影响城市碳排放。分析1995-2015年长三角城市群碳排放重心转移，查明碳排放和城市用地增长的脱钩状态时空变化，并通过构建面板数据模型探究城市形态对碳排放的影响，得出以下结论：（1）1995-2015年长三角城市群碳排放重心经历了西南向-西北向-东南向-西北向的转移过程，这种转移过程与其相应时期内部分城市的工业发展与产业结构调整有关；（2）1995-2015年，长三角城市群碳排放与城市用地增长的脱钩状态存在着显著的时空异质性。研究区由以扩张负脱钩为主变化为以弱脱钩为主，2005年以后，区域之间的脱钩差异开始缩小，总体来看研究区脱钩状态趋向于同质。至2015年，近70%的城市已达到了脱钩，其中上海等城市实现了强脱钩；（3）连续完整的地块在区域内的主导程度会对城市碳排放产生负向的影响，而城市用地斑块的破碎化程度和聚集程度对碳排放有着正向的影响，且相对而言，聚集程度的正向影响更为显著。 Abstract:Cities are one of many carbon sources. According to the Intergovernmental Panel on Climate Change (IPCC) AR5, CO2 emissions from fossil fuel combustion and industrial processes contributed about 78% to the total Green House Gas (GHG) emission increase between 1970-2010. Total annual anthropogenic GHG emissions have increased by about 10GtCO2-eq between 2000-2010. The increase directly came from energy (47%), industry (30%), transport (11%), and building (3%) sectors, which mainly exist in cities. Urban expansion and urbanization can affect urban carbon emission. Studies show that there is a long-term and stable relationship between urbanization and carbon dioxide emissions. The relationships between urban carbon emissions and indicators, including urban development intensity, urban land use, and the industrial sector, are studied extensively. During urban expansion, the quantitative and spatial features of urban lands can both affect carbon emissions. Therefore, urban form was added to the possible factors influencing carbon emissions in this study, which may be different from previous research that has focused on the relationship between urban growth and carbon emissions. However, in some related research, when urban form has been added to the indicators, the objects were residents or the transport sector, and they lacked quantitative indicators to verify the conclusions. The definition of "urban form" in this study was landscape pattern which was characterized by landscape metrics, and the study area consisted of 13 cities in the Yangtze River Delta. In this study, we analysed the shift of the gravity center from 1995-2015 for carbon emissions of the study area, and defined the decoupling index as well as analysing the temporal-spatial changes of the decoupling relationships between carbon emissions and urban growth in the study area. We also built panel data models to estimate the impact of urban forms on carbon emissions. Based on that, the conclusions are as follows:(1) The shift of the gravity center from 1995-2015 for carbon emissions of the study area was southwest-northwest-southeast-northwest. The shift may be related to the development of industry and change of industrial structure in some cities during this period. (2) There was a significant temporal-spatial heterogeneity in the decoupling relationships between carbon emissions and urban growth from 1995-2015. The leading decoupling relationship between carbon emissions and urban growth of the study area changed from expansive negative decoupling to weak decoupling from 1995-2015. The difference of decoupling relationships between cities narrowed after 2005 and the overall decoupling relationship of the study area became homogeneous. In 2015, almost 70% of cities reached the decoupling state and the decoupling states of Shanghai, Shaoxing, and Taizhou were strong. (3) Urban carbon emissions can be negatively influenced by the dominance of complete patches, and positively influenced by the degree of fragmentation and aggregation of urban patches. Carbon emissions can be more sensitive to the more aggregative distribution of the urban patches. This study analysed the relationship between carbon emissions and urban growth, as well as exploring how urban form can affect carbon emissions. The conclusions could provide scientific references for the policy making of low-carbon development strategies and land use and urban planning of urban agglomeration in the Yangtze River Delta. 参考文献 相似文献 引证文献

Design of Chipless RFID Tag by Using Miniaturized Open-Loop Resonators

In this paper, an open-loop resonator with fragment-loading structure is used for the first time in the design of radar cross section-based chipless radio-frequency identification (RFID) tag. By optimizing the distribution of fragment patches in an open loop, a microstrip open-loop resonator can be miniaturized so that the data capacity of the chipless RFID tag designed using such a miniaturized loop resonator can be significantly increased. Moreover, the resonant frequency of the fragment-loaded resonator can be adjusted conveniently by removing or disconnecting some fragment patches, which provides great flexibility for data encoding of the chipless RFID tag. The proposed chipless RFID tag with miniaturized open-loop resonators is designed and tested and can acquire 3.56 bits per resonator and a coding density of approximately $745.1~\text {bits}/\lambda _{g}^{2}$ . Several experimental results validate the proposed design as well as its implementation in a realistic environment.

A Texture Synthesis Model Based on Semi-Discrete Optimal Transport in Patch Space

Exemplar-based texture synthesis consists in producing new synthetic images which have the same perceptual characteristics as a given texture sample while exhibiting sufficient innovation (to avoid verbatim copy). In this paper, we propose to address this problem with a model obtained as local transformations of Gaussian random fields. The local transformations operate on $3 \times 3$ patches and are designed to solve a semi-discrete optimal transport problem in order to reimpose the patch distribution of the exemplar texture. The semi-discrete optimal transport problem is solved with a stochastic gradient algorithm, whose convergence speed is evaluated on several practical transport cases. After studying the properties of such transformed Gaussian random fields, we propose a multiscale extension of the model which aims at preserving the patch distribution of the exemplar texture at multiple scales. Experiments demonstrate that this multiscale model is able to synthesize structured textures while keeping several mathematical guarantees, and with low requirements in synthesis time and memory storage. In particular, a single patch optimal transport map is shown to be better than iterated nearest neighbor assignments in terms of statistical guarantees. Besides, once the model is estimated, the resulting synthesis algorithm is fast and highly parallel since it amounts to performing weighted nearest neighbor patch assignments at each scale.