Quadrat Analysis of Urban Dispersion: 3. Bivariate Modelst

1971 ◽  
Vol 3 (4) ◽  
pp. 433-450 ◽  
Author(s):  
A Rogers ◽  
J Martin
Keyword(s):  
Empirical Study ◽  
Urban Areas ◽  
Spatial Dispersion ◽  
Spatial Clustering ◽  
Urban Dispersion ◽  
Food Stores ◽  
Residential Population ◽  
Previous Discussion ◽  
Bivariate Models ◽  
Quadrat Analysis

This paper is a continuation of an earlier two-part essay on quadrat analysis. It extends the previous discussion by introducing bivariate models of spatial dispersion to analyze statistically the correlated spatial clustering of food stores and population in urban areas. The data used for empirical study are the spatial patterns of food stores and residential population in Ljubljana, Yugoslavia.

Quadrat Analysis of Urban Dispersion: 2. Case Studies of Urban Retail Systems

1969 ◽  
Vol 1 (2) ◽  
pp. 155-171 ◽  
Author(s):  
A. Rogers
Keyword(s):  
Spatial Structure ◽  
Case Studies ◽  
San Francisco ◽  
Empirical Data ◽  
Urban Areas ◽  
Urban Dispersion ◽  
Generalized Distributions ◽  
Empirical Tests ◽  
Quadrat Analysis

This is the second part of a two part paper; the first part reviewed the methodology of quadrat analysis and in this part, two case studies are presented. A brief introduction outlines the spatial structure of retailing in urban areas and it is then demonstrated how compound and generalized distributions offer a variety of models that can be fitted to empirical data about retail spatial structure. The empirical tests use data from Ljubljana, Yugoslavia and San Francisco, California. Conclusions are drawn which relate to the description, analysis and sampling of intra-urban retail spatial dispersions.

Quadrat Analysis of Urban Dispersion: 4. Spatial Sampling

1972 ◽  
Vol 4 (3) ◽  
pp. 331-345 ◽  
Author(s):  
A Rogers ◽  
R Raquillet
Keyword(s):  
Spatial Dispersion ◽  
Spatial Sampling ◽  
Urban Dispersion ◽  
Probability Sampling ◽  
Sampling Schemes ◽  
Quadrat Analysis

This paper is the concluding part of a four-part essay on quadrat analysis. It shows how quadrat analysis of spatial dispersion may be linked with Jessen's (1970) method of probability sampling with marginal constraints to produce more efficient spatial sampling schemes.

A Digital Terrain Modeling Method in Urban Areas by the ICESat-2 (Generating precise terrain surface profiles from photon-counting technology)

2021 ◽  
Vol 87 (4) ◽  
pp. 237-248
Author(s):  
Nahed Osama ◽  
Bisheng Yang ◽  
Yue Ma ◽  
Mohamed Freeshah
Keyword(s):  
Urban Areas ◽  
Spatial Clustering ◽  
Photon Counting ◽  
Ground Surface ◽  
Ground Truth ◽  
Surface Model ◽  
Laser Altimeter ◽  
Ground Truth Data ◽  
Urban Scenes ◽  
Terrain Surface

The ICE, Cloud and land Elevation Satellite-2 (ICES at-2) can provide new measurements of the Earth's elevations through photon-counting technology. Most research has focused on extracting the ground and the canopy photons in vegetated areas. Yet the extraction of the ground photons from urban areas, where the vegetation is mixed with artificial constructions, has not been fully investigated. This article proposes a new method to estimate the ground surface elevations in urban areas. The ICES at-2 signal photons were detected by the improved Density-Based Spatial Clustering of Applications with Noise algorithm and the Advanced Topographic Laser Altimeter System algorithm. The Advanced Land Observing Satellite-1 PALSAR –derived digital surface model has been utilized to separate the terrain surface from the ICES at-2 data. A set of ground-truth data was used to evaluate the accuracy of these two methods, and the achieved accuracy was up to 2.7 cm, which makes our method effective and accurate in determining the ground elevation in urban scenes.

scholarly journals Measuring Functional Urban Shrinkage with Multi-Source Geospatial Big Data: A Case Study of the Beijing-Tianjin-Hebei Megaregion

2020 ◽  
Vol 12 (16) ◽  
pp. 2513 ◽  
Author(s):  
Qiwei Ma ◽  
Zhaoya Gong ◽  
Jing Kang ◽  
Ran Tao ◽  
Anrong Dang
Keyword(s):  
Big Data ◽  
Urban Areas ◽  
Spatial Clustering ◽  
Landscape Fragmentation ◽  
Analytical Framework ◽  
Urban Land Use ◽  
Urban Systems ◽  
Landsat 8 ◽  
Clustering Methods

Most of the shrinking cities experience an unbalanced deurbanization across different urban areas in cities. However, traditional ways of measuring urban shrinkage are focused on tracking population loss at the city level and are unable to capture the spatially heterogeneous shrinking patterns inside a city. Consequently, the spatial mechanism and patterns of urban shrinkage inside a city remain less understood, which is unhelpful for developing accommodation strategies for shrinkage. The smart city initiatives and practices have provided a rich pool of geospatial big data resources and technologies to tackle the complexity of urban systems. Given this context, we propose a new measure for the delineation of shrinking areas within cities by introducing a new concept of functional urban shrinkage, which aims to capture the mismatch between urban built-up areas and the areas where significantly intensive human activities take place. Taking advantage of a data fusion approach to integrating multi-source geospatial big data and survey data, a general analytical framework is developed to construct functional shrinkage measures. Specifically, Landsat-8 remote sensing images were used for extracting urban built-up areas by supervised neural network classifications and Geographic Information System tools, while cellular signaling data from China Unicom Inc. was used to depict human activity areas generated by spatial clustering methods. Combining geospatial big data with urban land-use functions obtained from land surveys and Points-Of-Interests data, the framework further enables the comparison between cities from dimensions characterized by indices of spatial and urban functional characteristics and the landscape fragmentation; thus, it has the capacity to facilitate an in-depth investigation of fundamental causes and internal mechanisms of urban shrinkage. With a case study of the Beijing-Tianjin-Hebei megaregion using data from various sources collected for the year of 2018, we demonstrate the validity of this approach and its potential generalizability for other spatial contexts in facilitating timely and better-informed planning decision support.

scholarly journals The casualization of black female labour in South Africa

2000 ◽  
Vol 3 (2) ◽  
pp. 165-188 ◽  
Author(s):  
T. I. Fényes ◽  
P. Lalthapersad
Keyword(s):  
South Africa ◽  
Black Women ◽  
Women Workers ◽  
Empirical Study ◽  
Urban Areas ◽  
Black Female ◽  
Job Market ◽  
Female Labour ◽  
Work Done

Black women workers in South Africa are highly marginalized in that their work has been undervalued and underpaid due to disadvantage and discrimination. They were severely curtailed by legislation that aimed to keep them away from urban areas and the formal job market. This paper reports the results of an empirical study of the work done by black women in the manufacturing and retail industries. The purpose of the study was to determine the kind of work black women do and the nature of the job processes. The article examines the main findings of the study.

Food and Chemistry Toxicology: Safety of Locally-Sold Food (Nutritional Distribution of Select Fruits and Vegetables in an Urban Food Desert)

2018 ◽  
Vol 2 (08) ◽  
Author(s):  
Kayla Dean ◽  
Nripendra Bose ◽  
Saleigh Derico ◽  
Felicia Jefferson
Keyword(s):  
Urban Areas ◽  
Inductively Coupled Plasma ◽  
Toxic Elements ◽  
Fruits And Vegetables ◽  
High Water ◽  
Food Stores ◽  
Water Abundance ◽  
Inductively Coupled ◽  
Community Area ◽  
Cadmium And Lead

There has been an increase of heavy metals in agricultural soil. The potentially harmful metals in the soil may come from the bedrock, waste deposits, agricultural inputs and urban emissions. Moreover, contaminated food is considered the main source by which humans are exposed to toxic elements. Fruits and vegetables are regarded as containing a low percentage of toxic compounds due to their high water abundance. However, dried fruits, which are often sold in areas where the abundance of fresh fruits and vegetables is low, may contain more toxic elements. Within considering all of the factors the trace metals induce on humans via the consumption of plants, one is able to analyze then disproportionate availability of toxin less foods in certain areas. Reasons that people do not consume fruits and vegetables that are not toxic are complex. This disproportionate representation is evident mainly in urban areas. Studies have shown that urban African Americans who shopped at their local neighborhood small- food stores consumed fewer fresh fruits and vegetables than their higher income peers who were able to shop in suburban supermarkets. Environmental barriers have been found the main cause for the limited availability of fresh fruits and vegetables. This research project will engage whether or not there is a disproportionate availability of toxin less foods in West End Atlanta community area by utilizing the Inductively Coupled Plasma Optic Emission Spectroscopy (ICP-OES), which will analyze the trace metal contents of arsenic, cadmium and lead in apples, bananas, and potatoes.

scholarly journals One-Way Coupling of the WRF–QUIC Urban Dispersion Modeling System

2015 ◽  
Vol 54 (10) ◽  
pp. 2119-2139 ◽  
Author(s):  
A. K. Kochanski ◽  
E. R. Pardyjak ◽  
R. Stoll ◽  
A. Gowardhan ◽  
M. J. Brown ◽  
...  
Keyword(s):  
Urban Areas ◽  
Surface Wind ◽  
Wrf Model ◽  
Conclusive Evidence ◽  
Dispersion Modeling ◽  
Industrial Complex ◽  
Urban Dispersion ◽  
Canopy Layer ◽  
Near Surface ◽  
Wind Profiles

AbstractSimulations of local weather and air quality in urban areas must account for processes spanning from meso- to microscales, including turbulence and transport within the urban canopy layer. Here, the authors investigate the performance of the building-resolving Quick Urban Industrial Complex (QUIC) Dispersion Modeling System driven with mean wind profiles from the mesoscale Weather Research and Forecasting (WRF) Model. Dispersion simulations are performed for intensive observation periods 2 and 8 of the Joint Urban 2003 field experiment conducted in Oklahoma City, Oklahoma, using an ensemble of expert-derived wind profiles from observational data as well as profiles derived from WRF runs. The results suggest that WRF can be used successfully as a source of inflow boundary conditions for urban simulations, without the collection and processing of intensive field observations needed to produce expert-derived wind profiles. Detailed statistical analysis of tracer concentration fields suggests that, for the purpose of the urban dispersion, WRF simulations provide wind forcing as good as individual or ensemble expert-derived profiles. Despite problems capturing the strength and the elevation of the Great Plains low-level jet, the WRF-simulated near-surface wind speed and direction were close to observations, thus assuring realistic forcing for urban dispersion estimates. Tests performed with multilayer and bulk urban parameterizations embedded in WRF did not provide any conclusive evidence of the superiority of one scheme over the other, although the dispersion simulations driven by the latter showed slightly better results.

scholarly journals An Empirical Study of the Impact of Metro Station Proximity on Property Value in The Case of Nanjing, China

2014 ◽  
Vol 2 (4) ◽  
pp. 61-71
Author(s):  
Xinyue Zhang ◽  
Yanqing Jiang
Keyword(s):  
Empirical Study ◽  
Urban Areas ◽  
Positive Impact ◽  
Property Value ◽  
Price Variation ◽  
Metro Station ◽  
Empirical Results ◽  
Suburban Areas ◽  
The Impact

This paper analyzes the impact of metro station proximity on property value from both theoretical and empirical perspectives. Data on second-hand apartments within six kilometers of metro line 1 and 2 stations in Nanjing are used. Our empirical results show that metro station proximity has a positive partial effect on property value. The degree of impact diminishes with the increase of the distance. The extent of impact reaches the largest when the distance is less than five hundred meters, and is still remarkable when the distance is within two kilometers. The effect becomes insignificant when the distance is larger than two kilometers. Our empirical results also show that with the distance increasing, the extent of price variation is widened first, reaching a peak when the property is within one kilometer, and then decreases. In addition, metro station proximity in suburban areas is shown to have a higher positive impact on property value compared with metro station proximity in urban areas.

scholarly journals The Eulerian urban dispersion model EPISODE. Part II: Extensions to the source dispersion and photochemistry for EPISODE-CityChem v1.2 and its application to the city of Hamburg

2019 ◽  
Author(s):  
Matthias Karl ◽  
Sam-Erik Walker ◽  
Sverre Solberg ◽  
Martin O. P. Ramacher
Keyword(s):  
Air Quality ◽  
Atmospheric Chemistry ◽  
Urban Areas ◽  
Dispersion Model ◽  
Model Performance ◽  
Pollutant Dispersion ◽  
Lower Latitude ◽  
Urban Dispersion ◽  
Grid Model ◽  
The City

Abstract. This paper describes the CityChem extension of the Eulerian urban dispersion model EPISODE. The development of the CityChem extension was driven by the need to apply the model in lower latitude cities with higher insolation than in northern European cities. The CityChem extension offers a more advanced treatment of the photochemistry in urban areas and entails specific developments within the sub-grid components for a more accurate representation of the dispersion in the proximity of urban emission sources. The WMPP (WORM Meteorological Pre-Processor) is used in the point source sub-grid model to calculate the wind speed at plume height. The simplified street canyon model (SSCM) is used in the line source sub-grid model to calculate pollutant dispersion in street canyons. The EPISODE-CityChem model integrates the CityChem extension in EPISODE, with the capability of simulating photochemistry and dispersion of multiple reactive pollutants within urban areas. The main focus of the model is the simulation of the complex atmospheric chemistry involved in the photochemical production of ozone in urban areas. EPISODE-CityChem was evaluated with a series of tests and with a first application to the air quality situation in the city of Hamburg, Germany. A performance analysis with the FAIRMODE DELTA Tool for the air quality in Hamburg showed that the model fulfils the model performance objectives for NO2 (hourly), O3 (daily max. of the 8-h running mean) and PM10 (daily mean) set forth in the Air Quality Directive, qualifying the model for use in policy applications. Observed levels of annual mean ozone at the five urban background stations in Hamburg are captured by the model within 15 %. Envisaged applications of the EPISODE-CityChem model are urban air quality studies, emission control scenarios in relation to traffic restrictions and the source attribution of sector-specific emissions to observed levels of air pollutants at urban monitoring stations.

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