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1.
Conventional methods used to identify crime hotspots at the small‐area scale are frequentist and employ data for one time period. Methodologically, these approaches are limited by an inability to overcome the small number problem, which occurs in spatiotemporal analysis at the small‐area level when crime and population counts for areas are low. The small number problem may lead to unstable risk estimates and unreliable results. Also, conventional approaches use only one data observation per area, providing limited information about the temporal processes influencing hotspots and how law enforcement resources should be allocated to manage crime change. Examining violent crime in the Regional Municipality of York, Ontario, for 2006 and 2007, this research illustrates a Bayesian spatiotemporal modeling approach that analyzes crime trend and identifies hotspots while addressing the small number problem and overcoming limitations of conventional frequentist methods. Specifically, this research tests for an overall trend of violent crime for the study region, determines area‐specific violent crime trends for small‐area units, and identifies hotspots based on crime trend from 2006 to 2007. Overall violent crime trend was found to be insignificant despite increasing area‐specific trends in the north and decreasing area‐specific trends in the southeast. Posterior probabilities of area‐specific trends greater than zero were mapped to identify hotspots, highlighting hotspots in the north of the study region. We discuss the conceptual differences between this Bayesian spatiotemporal method and conventional frequentist approaches as well as the effectiveness of this Bayesian spatiotemporal approach for identifying hotspots from a law enforcement perspective.  相似文献   

2.
This paper is concerned with the morphological evolution of three‐dimensional chemical dissolution fronts that occur in fluid‐saturated porous media. A fully coupled system between porosity, pore‐fluid flow and reactive chemical species transport is considered to describe this phenomenon. Using the newly presented concept of the generalized dimensionless pore fluid pressure‐gradient, which can be used to represent the interaction between solute advection, solute diffusion, chemical kinetics and the shape factor of the soluble mineral, a theoretical criterion has been established to assess the likelihood of instability at a chemical dissolution front in the reactive transport system. To simulate the chemical dissolution front evolution in a three‐dimensional fluid‐saturated porous medium, a numerical procedure combining both the finite difference method and the finite element method has been proposed. As the problem belongs to a complex system science problem, a small randomly generated perturbation of porosity is added to the initial porosity of a three‐dimensional homogeneous domain to trigger instability of a planar chemical dissolution front during its propagation within the fluid‐saturated porous medium. To test the correctness and accuracy of the proposed numerical procedure, a three‐dimensional benchmark problem has been constructed and the related analytical solution has been derived. This enables using the proposed numerical procedure for simulating the morphological evolution of a three‐dimensional chemical dissolution front from a stable, planar state into an unstable, fingering state. The related numerical results demonstrate that the proposed numerical procedure is useful for, and capable of, simulating the morphological instability of a three‐dimensional chemical dissolution front within a fluid‐saturated porous medium.  相似文献   

3.
This paper develops a method for analyzing surfaces with a focus on their qualitative similarity. The method describes the qualitative similarity between surfaces defined in the same region in both quantitative and qualitative ways. Given a location and a direction in the region, mathematical functions evaluate the similarity between surfaces. Integrals of the functions with respect to location and direction give quantitative measures of the total similarity between surfaces. A qualitative method uses spatial characteristics shared by surfaces: α‐peak regions, α‐pit regions, and ß‐monotonic lines. α‐peak and α‐pit regions indicate approximate locations where many surfaces have peaks and pits, respectively. ß‐monotonic lines are line segments on which most surfaces change monotonically in the same direction. Those spatial objects reveal the spatial structure shared by surfaces. The method is applied to the analysis of the daily market structure of a supermarket in Japan as an empirical study.  相似文献   

4.
This study focuses on integration processes in European Research and Development (R&D) by analyzing the spatiotemporal dimension of three different R&D collaboration networks across Europe. The studied networks cover different types of knowledge creation, namely project‐based R&D networks within the European Union (EU) Framework Programmes (FPs), co‐patent networks, and co‐publication networks. Integration in European R&D—one of the main pillars of the EU Science Technology and Innovation policy—refers to the harmonization of fragmented national research systems across Europe and to the free movement of knowledge and researchers. The objective is to describe and compare spatiotemporal patterns at a regional level and to estimate the evolution of separation effects over the time period 1999–2006 that influence the probability of cross‐region collaborations in the distinct networks under consideration. The study adopts a spatial interaction modeling perspective, econometrically specifying a panel generalized linear model relationship, taking into account spatial autocorrelation among flows using eigenfunction spatial filtering methods. The results show that geographical factors are a lower hurdle for R&D collaborations in the FP networks than in co‐patent networks and co‐publication networks. Furthermore, it is shown that the geographical integration is higher in the FP network.  相似文献   

5.
6.
ABSTRACT This original study examines the potential of a spatiotemporal autoregressive Local (LSTAR) approach in modeling transaction prices for the housing market in inner Paris. We use a data set from the Paris Region notary office (Chambre des notaires d’Île‐de‐France) which consists of approximately 250,000 transactions units between the first quarter of 1990 and the end of 2005. We use the exact XY coordinates and transaction date to spatially and temporally sort each transaction. We first choose to use the STAR approach proposed by Pace et al., 1998 . This method incorporates a spatiotemporal filtering process into the conventional hedonic function and attempts to correct for spatial and temporal correlative effects. We find significant estimates of spatial dependence effects. Moreover, using an original methodology, we find evidence of a strong presence of both spatial and temporal heterogeneity in the model. It suggests that spatial and temporal drifts in households socio‐economic profiles and local housing market structure effects are certainly major determinants of the price level for the Paris Housing Market.  相似文献   

7.
Cluster analysis is the most widely used multivariate technique in archaeometry, with the majority of applications being exploratory in nature. Model‐based methods of clustering have their advocates, but have seen little application to archaeometric data. The paper investigates two such methods. They have potential advantages over exploratory techniques, if successful. Mixture maximum‐likelihood worked well using low‐dimensional lead isotope data, but had problems coping with higher‐dimensional ceramic compositional data. For our most challenging example, classification maximum‐likelihood performed comparably with more standard methods, but we find no evidence to suggest that it should supplant these.  相似文献   

8.
9.
Public confidence in the police is crucial to effective policing. Improving understanding of public confidence at the local level will better enable the police to conduct proactive confidence interventions to meet the concerns of local communities. Conventional approaches do not consider that public confidence varies across geographic space as well as in time. Neighborhood level approaches to modeling public confidence in the police are hampered by the small number problem and the resulting instability in the estimates and uncertainty in the results. This research illustrates a spatiotemporal Bayesian approach for estimating and forecasting public confidence at the neighborhood level and we use it to examine trends in public confidence in the police in London, UK, for Q2 2006 to Q3 2013. Our approach overcomes the limitations of the small number problem and specifically, we investigate the effect of the spatiotemporal representation structure chosen on the estimates of public confidence produced. We then investigate the use of the model for forecasting by producing one‐step ahead forecasts of the final third of the time series. The results are compared with the forecasts from traditional time‐series forecasting methods like naïve, exponential smoothing, ARIMA, STARIMA, and others. A model with spatially structured and unstructured random effects as well as a normally distributed spatiotemporal interaction term was the most parsimonious and produced the most realistic estimates. It also provided the best forecasts at the London‐wide, Borough, and neighborhood level.  相似文献   

10.
Wim Carton 《对极》2019,51(3):750-769
Models suggest that climate change mitigation now depends on negative emissions, i.e. the large‐scale removal of carbon dioxide from the atmosphere. This assumption has been criticised in the climate policy literature for being unfeasible and unjust. This article asks how critical scholars can make sense of, and contribute to these debates. It suggests that negative emissions can be conceived of as a spatiotemporal fix that promises to defer the devaluation of fixed capital. But the negative emissions example also challenges us to broaden our conception of how the socioecological contradictions of capitalism can be “fixed”. I outline three ways in which it does this by highlighting the significance of a predominantly temporal fix, the role of hegemonic, sociopolitical interventions involving multiple actors, and the possibility of safeguarding existing production processes. I conclude that spatiotemporal fixes to climate change should be seen as part of a wider political economy of delay in devaluing carbon‐intensive accumulation processes.  相似文献   

11.
A recurrent problem for scholars who investigate traditional and historical clothing is the measuring of items of clothing and subsequent pattern construction. The challenge is to produce exact data without damaging the item. The main focus of this paper is to present a new procedure for establishing a three‐dimensional model and the corresponding two‐dimensional pattern for items of skin clothing that are not flat. The new method is non‐destructive, and also accurate and fast. Furthermore, this paper presents an overview of the more traditional methods of pattern documentation and measurement. Their weaknesses and strengths are also assessed.  相似文献   

12.
There is growing interest in the German‐Polish border area's future status in the changing regional structure of Europe—contrasting scenarios contain, on the one hand, a vision of the region as a new ‘tiger’ region, and are seen at the other extreme as a ‘drainage area’ on the outskirts of the EU. In this article, border areas are treated from a point of view that pays more attention to the regions’ system of production and regulation. The first part deals with some general characteristics of border areas; the second part outlines in more detail the specific developmental conditions of the German‐Polish border area, especially the region between Berlin and Poznan along the middle part of the River Oder (comprising the Euro Region Pro Europa Viadrina). Three aspects of the border region's developmental conditions are emphasized: the region's quality of location within Europe and the respective national territories; the permeability of the border; and the economic structure in the border area, whereby forms of trans‐border economic linkage and cooperation are of particular interest. The last section discusses new challenges for European border areas as posed by economic change and the restructuring of the European spatial fabric.  相似文献   

13.
书画装裱材料——宣纸形稳定性的研究   总被引:2,自引:0,他引:2  
为了加强纸质物的保护,对书画装裱材料宣纸的湿形稳性变化规律进行了研究。通过对不同条件下干燥方法对宣纸形变影响的研究,对纸张变形的原因进行了探讨。实验结果表明,宣纸具有随湿度变形的特性,变形程度与纸的纤维组成和干燥方法有关。采用梯度干燥的方式纸张的尺寸稳定性没有明显的改善。厚度和收缩率相关分析说明二不存在相关性。随着纸张干湿交替处理次数的增多,其变形性趋于减小。为提高纸张的形稳性,可预先进行处理。  相似文献   

14.
This paper endorses recent pleas for an ‘institutional turn’ within economic geography. In particular, it reveals and connects the coherence and distinctiveness of dissenting institutional economics as a way of thinking for economic geography. Economic geographers have recognized this tradition but its continuity and compass is not fully appreciated. To provide such an appreciation, this paper argues that the paradigmatic distinctiveness of dissenting institutionalism rests especially on its recognition that real world economies are embedded, have histories or evolve, and are different. The discussion is based around these three cornerstone principles of embeddedness, evolution and difference. For the future, greater attention to the region as an institution, albeit a complex one, along with greater attention to the synthesis of multi‐dimensional processes that are normally analyzes as separate conceptual categories, is encouraged.  相似文献   

15.
This research applies a Bayesian multivariate modeling approach to analyze the spatiotemporal patterns of physical disorder, social disorder, property crime, and violent crime at the small‐area scale. Despite crime and disorder exhibiting similar spatiotemporal patterns, as hypothesized by broken windows and collective efficacy theories, past studies often analyze a single outcome and overlook the correlation structures between multiple crime and disorder types. Accounting for five covariates, the best‐fitting model partitions the residual risk of each crime and disorder type into one spatial shared component, one temporal shared component, and type‐specific spatial, temporal, and space–time components. The shared components capture the underlying spatial pattern and time trend common to all types of crime and disorder. Results show that population size, residential mobility, and the central business district are positively associated with all outcomes. The spatial shared component is found to explain the largest proportion of residual variability for all types of crime and disorder. Spatiotemporal hotspots of crime and disorder are examined to contextualize broken windows theory. Applications of multivariate spatiotemporal modeling with shared components to ecological crime theories and crime prevention policy are discussed.  相似文献   

16.
Identified human skeletal collections are those in which basic demographic data (sex, age and biological origin) are known and are crucial for developing and testing osteological methodologies. It is important that the identified collection be contextualised, and in this way the collection will be considered a reference collection. To contextualise a collection requires documentation of the basic demographic data of the individuals (sex, age, year of birth, geographical area) as well as information concerning the socio‐economic and temporal context in which the individuals lived. The contextualisation of an identified collection is very important so the researchers can understand the ‘point of reference’ when applying a method to it or developing a new method. The purpose of this study is to contextualise the identified skeletal collection of the Universitat Autónoma de Barcelona (UAB) which currently contains 35 adult skeletons of both sexes. To carry out the objectives of the present study, the information about the individuals was collected from cemetery registers and compared with the information of the demographic and statistic public institutions of Spain. The results indicate that the UAB collection is formed only by Spanish nationals who mainly lived during the 20th century in Granollers (Barcelona, Spain). Both sexes are equally represented and all of the individuals are adults. They reflect the most current adult population structure of Catalonia and be treated as a Catalan reference sample of adults living in the 20th century. This collection offers special opportunities for demographic analysis, including validation studies of skeletal ageing and sexing methods that target adult individuals. The collection can also be used in conjunction with other reference samples to investigate secular and populational change in cranial form, sexual dimorphism and stature. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

17.
This paper presents a revised version of the Coimbra method for recording fibrocartilaginous entheses. The method itself is the only biologically appropriate recording method for fibrocartilaginous entheses that scores features separately, thereby ensuring that the aetiology of individual features can be studied. The method divides the enthesis into two zones, scoring the relevant features in each zone. These features represent either bone formation or bone destruction and include erosive lesions, fine and macro‐porosity, and cavitations. The revised method includes a new feature, textural change, which is scored as absent or present when it involves 50% or more of the surface. All other features are now scored as zero (absent), one or two with the higher score representing greater expression of the feature. This change in scoring has led to the reduction of inter‐observer error with approximately 80% agreement for overall feature scores for both the common extensor origin and subscapularis insertion. The simplification of the scores and the reduction in inter‐observer error mean that the method is now recommended for widespread use. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

18.
Eight years ago, Ramenofsky et al. (2003) characterized the discussion of the impact of Old World diseases on Native American populations as almost exclusively historical in nature. They specifically argued for the application of more evolutionary, genetic, and epidemiological theory to research into this topic. We agree with their assessment and further suggest that such research would greatly benefit from spatial analyses of disease spread as well. Using trend surface analysis of existing ethnohistorical and archaeological data pertaining to population sizes and disease events, we examine the spatiotemporal dimensions of 17th century depopulation in northeastern North America. The subsequent results allow us to predict possible depopulation rates for populations with very little demographic data. Further, our use of biological, historical, and cultural data to interpret the results represents an attempt to provide a more complex explanation for the variability in cultural survivability across the region and several possible avenues for productive future research. We believe research like this can significantly improve our understanding of how Old World diseases affected historic Native American populations and cultures and continue to impact them today.  相似文献   

19.
flowAMOEBA: Identifying Regions of Anomalous Spatial Interactions   总被引:1,自引:0,他引:1  
This study aims at developing a data‐driven and bottom‐up spatial statistic method for identifying regions of anomalous spatial interactions (clusters of extremely high‐ or low‐value spatial flows), based on which it creates a spatial flow weights matrix. The method, dubbed flowAMOEBA, upgrades a multidirectional optimum ecotope‐based algorithm (AMOEBA) from areal data to spatial flow data through a proper spatial flow neighborhood definition. The method has the potential to dramatically change the way we study spatial interactions. First, it breaks the convention that spatial interaction data are always collected and modeled between spatial entities of the same granularity, as it delineates the OD region of anomalous spatial interactions, regardless of the size, shape, scale, or administrative level. Second, the method creates an empirical spatial flow weights matrix that can handle network autocorrelation embedded in spatial interaction modeling, thus improving related policy‐making or problem‐solving strategies. flowAMOEBA is tested and demonstrated on a synthetic data set as well as a county‐to‐county migration data set.  相似文献   

20.
During the 2013 fieldwork of the French archaeological mission along the shores of the Arabian Sea, mancala games were discovered on the seashore of Salalah at the site of Ad‐Dahariz. They are cup‐hole carvings made directly into rock slabs and distributed in six distinct zones of the site. They usually consist of fourteen cup‐holes aligned in two lines of seven, two supplementary holes being sometimes present on each side. They are the first of their kind in South Arabia and can be compared to similar configurations of carved games elsewhere in Arabia, such as at Jebel al‐Jassasiya, Qatar. This paper presents the potential origins of this game in the region, as well as a plausible dating of their use.  相似文献   

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