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排序方式: 共有61条查询结果,搜索用时 46 毫秒
1.
PAUL J. CURRAN TIMOTHY J. MUNDAY EDWARD J. MILTON 《International journal of remote sensing》2013,34(2):185-188
Two simple photographic methods have recently been proposed for the measurement of relative bidirectional reflectance (Lillesand and Kiefer 1979, Curran 1980). These two methods were used to calculate the relative bidirectional reflectance of ten contrasting surfaces. The photographic relative bidirectional reflectance so recorded, was then compared with the radiometric bidirectional reflectance for each surface. Two conclusions were drawn: first, that relative bidirectional reflectance can be measured using these simple photographic techniques, and second, that there was no significant difference between the Lillesand and Kiefer and Curran methods for photographically deriving relative bidirectional reflectance. 相似文献
2.
IGOR VOJNOVIC ZEENAT KOTVAL‐K JIEUN LEE MINTING YE TIMOTHY LEDOUX PARIWATE VARNAKOVIDA JOSEPH MESSINA 《Journal of Urban Affairs》2014,36(2):225-255
The research explores the impact of socioeconomic and racial variables on accessibility to urban amenities and travel in compact urban built environments that have traditionally been viewed as improving access to daily destinations and promoting nonmotorized travel: urban environments characterized by high densities, mixed land uses, and high connectivity. The study focuses on six neighborhoods in the Detroit region. Two neighborhoods are within the city itself, and predominantly poor and Black, and four of the neighborhoods are in the region surrounding the city, and they are predominantly wealthy and White. This study at the neighborhood scale enables an analysis into how class and race affect accessibility and travel in neighborhoods experiencing urban disinvestment and decline. The research shows that the traditional relationship between high densities, mixed land uses, high connectivity, greater accessibility, and pedestrian activity is significantly weaker in declining inner cities. 相似文献
3.
Abstract GENITOR is a genetic algorithm which employs one-at-a-time reproduction and allocates reproductive opportunities according to rank to achieve selective pressure. Theoretical arguments and empirical evidence suggest that GENITOR is less vulnerable to some of the biases that degrade performance in standard genetic algorithms. A distributed version of GENITOR which uses many smaller distributed populations in place of a single large population is introduced. GENITOR II is able to optimize a broad range of sample problems more accurately and more consistently than GENITOR with a single population. GENITOR II also appears to be more robust than a single population genetic algorithm, yielding better performance without parameter tuning. We present some preliminary analyses to explain the performance advantage of the distributed algorithm. A distributed search is shown to yield improved search on several classes of problems, including binary encoded feedforward neural networks, the Traveling Salesman Problem, and a set of ‘ deceptive problems’ specially designed to be hard for genetic algorithms. 相似文献
4.
TIMOTHY J. HANEY 《Journal of Urban Affairs》2013,35(3):303-325
ABSTRACT: This paper endeavors to create a better understanding of the barriers to employment faced by disadvantaged urban women in the post–welfare reform era. Using data from the Project on Devolution and Urban Change, a unique geographically linked, longitudinal, multicity set of survey data, logistic regression models weighs the relative importance of individual barriers to employment (e.g., poor health, childcare, family responsibilities) and contextual or neighborhood barriers to employment (e.g., poverty rate, joblessness rate) on labor market outcomes. Results reveal that several neighborhood characteristics are predictive of employment outcomes, including automobile access, female‐headedness, vacancy, and disorder. Results suggest a more complex, nuanced interplay between neighborhood‐level variables and individually measured variables in preventing some women from obtaining both modestly paying employment with few allocated hours of work per week, and also better‐paying jobs with more hours of work per week. 相似文献
5.
FOLLOWING THE MONEY: THE INFLUENCE OF CAMPAIGN FINANCE REFORM IN THE 2011 CHICAGO MAYORAL ELECTION 下载免费PDF全文
In this research we study the effect of recently enacted campaign contribution limits in Illinois via an examination of the 2011 Chicago mayoral election. Because contribution limits for state and local campaigns were implemented in the middle of the race for mayor we are uniquely positioned to test the efficacy of the new law. In theory we expect contribution limits to cause candidates to rely on more contributors making smaller donations. Our results indicate that the reform measure did not prompt candidates to broaden their fundraising base, and only when Rahm Emanuel's campaign is considered alongside his opponents’ did the fundraising law reduce average contributions. In a concluding section we address the issue of whether the contribution limits established under the law are too high to produce meaningful reform. 相似文献
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Carrots blanched in water for 0 to 300 sec were analyzed for flavor volatiles by dynamic headspace analysis, the volatiles identified by gas chromatography/mass spectrometry, and the sensory attributes evaluated by a trained panel to determine quality changes as related to blanching times. Most volatiles, in particular terpenoids (sabinene, β-pinene, β-myrcene, limonene, trans-caryophyllene, α-humulene, β-bisabolene and α-farnesene) decreased by at least 50% within 60 sec of blanching. Ratings on quality attributes of color, texture, raw carrot aroma, sweetness, flavor and overall impression decreased with blanching time, while cooked carrot aroma increased. There were correlations (p < 0.05) between blanching times, flavor volatiles and sensory attributes. 相似文献
8.
N. SHANKAR TIMOTHY J. WILTSHIRE R. SHANKAR SUBRAMANIAN 《Chemical Engineering Communications》2013,200(5-6):263-281
The problem of the dissolution or growth of an isolated, stationary, sphere in a large fluid body is analyzed. The motion of the boundary as well as the resulting motion in the liquid are properly taken into account. The governing equations are solved using a recently developed technique (Subramanian and Weinberg, 1981) which employs an asymptotic expansion in time. Results for the radius of the sphere as a function of time are calculated. The range of utility of the present solution is established by comparison with a numerical solution of the governing equations obtained by the method of finite differences. 相似文献
9.
TIMOTHY D. MEAD 《Journal of Urban Affairs》1981,3(1):1-12
Research conducted for the Department of Housing and Urban Development (HUD) identified six processes associated with high levels of local government management capacity. They were: 1) people of competence fill both elected and key administrative positions, and there is substantial continuity among the latter; 2) fiscal management practices are used as policy tools that permit capital and operational planning and control; 3) public officials recognize the legitimacy of concern for equity in public policy and administration; 4) open decision-making processes facilitate exchange of views between citizens and officials; 5) public services are delivered effectively and efficiently; and, 6) information management systems are utilized that permit decision-making information to flow freely between policy and administrative sectors and within the administrative sector. More significant in sustaining management capacity than the form of government, size of the jurisdiction, or region of the country, these processes are subject to enhancement by capacity-building efforts by practitioners and by those engaged in training of local personnel. 相似文献
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