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1.
Economic models of urban spatial patterns have largely ignored complexity as an attribute of urban systems. Complexity theorists
on the other hand have not made sufficiently serious and sustained attempts to verify empirically the relevance of complex
systems models for urban spatial patterns. This research bridges this gap by simulating the evolution of an urban employment
pattern as a self-organizing complex system and seeking its empirical validation. It estimates the model’s parameters by using
firm data aggregated to the level of municipalities in Cleveland-Akron Consolidated Metropolitan Statistical Area in Ohio.
The interaction among four parameters, forces of attraction and dispersion and their respective rates of dissipation with
distance, are modeled as a two-dimensional complex system. The research compares the states of the modeled system with empirical
data to present viable methods for verification, calibration and validation of such models.
相似文献
2.
Maurice A. Lock Tim E. Ford Meredith A. J. Hullar Molli Kaufman J. Robie Vestal Gregg S. Volk Roy M. Ventullo 《Water research》1990,24(12):1545-1549
A fourth-order arctic river was experimentally enriched with phosphate (7.7 ± 7.0 μ g 1−1) to determine the effect of such a loading (equivalent to a community of 10,000 people) upon the trophically important biofilm. The effect upon a light-grown biofilm (an autotrophic/heterotrophic assemblage) and a dark-grown biofilm (predominantly heterotrophic assemblage) was determined after 28 days of colonization. Seven attributes of the biofilms were monitored, 2 autotrophic indices, chlorophyll , [14C]HCO3 incorporation into lipids and 5 heterotrophic indices; [14C]acetate incorporation into lipids, metabolic heat output, turn-over times of microbially labile glucose and glutamate and mineralization of microbially recalcitrant ring-labelled [14C]hydroxybenzoic acid. The findings showed that the addition of phosphorus resulted in a substantial stimulation of both autotrophic and heterotrophic processes suggesting that arctic rivers of this type would be liable to cultural eutrophication. 相似文献
3.
Kameshwari Pothukuchi Jerome L. Kaufman 《Journal of the American Planning Association. American Planning Association》2013,79(2):113-124
Shelley Jordon describes her artwork as celebrating “the power and the beauty of domestic spaces and objects…culled from daily life.” Food is among the most basic of daily human needs, yet what is most basic often gets overlooked. Alpenrose, her image of a breakfast table, brings this human need to the fore, as authors Ka-meshwari Pothukucki and Jerome L. Kaufman argue that food systems need a place among the concerns of planners. The artist, who is an associate professor of art at Oregon State University, resides in Portland, Oregon. Her works can be found in galleries and private collections throughout the West Coast. Planning lays claim to being comprehensive, future-oriented, and public-interest driven, and of wanting to enhance the livability of communities. It is concerned with community systems—such as land use, housing, transportation, the environment, and the econ-omy—and their interconnections. The food system, however, is notable by its absence from most planning practice, research, and education. We present evidence for the limited presence of the food system in planning's list of concerns by scanning leading journals, texts, and classic writings, and by reporting on a survey of 22 U.S. city planning agencies. We analyze this low level of attention and discuss reasons and ideas for planning involvement to strengthen community food systems.1 相似文献
4.
The use of the Internet for conducting research has found that the level of anonymity intrinsic to web-based surveys is useful in deterring various participant biases. Though, concerns about Internet privacy could interfere with the effects of perceived anonymity and influence how a person responds. In this study, participants were asked to take an Internet survey and then were randomly assigned to conditions with varying degrees of implied privacy in which they answered questions about their desire for casual sex (sociosexuality) and their lifetime sexual partners. Only in the condition without any threat to the participant’s anonymity was there no difference between men and women’s reports of their sexual behavior. However, in every condition men reported having a significantly higher sociosexuality than women. Findings are consistent with both the biologic and gender-biased explanations in differences of self-report for sexual information. Implications for social constraints and Internet based research are discussed. 相似文献
5.
The springback and anelastic behavior of selected Mg alloys were investigated as a function of thermo-mechanical state and loading conditions by strain-recovery experiments in three-point bending. The observed stress relaxations were primarily due to recoverable microstructural relaxations and the transformation of linear-elastic strains to recoverable time-dependent anelastic strains. This transformation occurs by thermally activated dislocation motion or reversible twin movement and influences the magnitude of the springback effect. The amount of anelastic strain observed during stress relaxation experiments was found to depend on four factors: initial dislocation density (cold work), applied strain levels, temperature, and holding time at fixed strain levels. 相似文献
6.
Automatic photo enhancement is one of the long‐standing goals in image processing and computational photography. While a variety of methods have been proposed for manipulating tone and colour, most automatic methods used in practice, operate on the entire image without attempting to take the content of the image into account. In this paper, we present a new framework for automatic photo enhancement that attempts to take local and global image semantics into account. Specifically, our content‐aware scheme attempts to detect and enhance the appearance of human faces, blue skies with or without clouds and underexposed salient regions. A user study was conducted that demonstrates the effectiveness of the proposed approach compared to existing auto‐enhancement tools. 相似文献
7.
Saurabh Das Nicholas Cadirov Sathya Chary Yair Kaufman Jack Hogan Kimberly L. Turner Jacob N. Israelachvili 《Journal of the Royal Society Interface》2015,12(104)
The discovery and understanding of gecko ‘frictional-adhesion’ adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick–slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick–slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick–slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. 相似文献
8.
A methodology to characterize particle penetration characteristics of individual protective equipment (IPE) under elevated wind conditions was developed. Performance of a complete IPE system can be determined from the knowledge of the performance characteristics of the IPE subsystems, or components. Here, particle penetration characteristics of a cylindrical-shaped component, consisting of an outer fabric sleeve enclosing an inner appendage, were studied as a function of particle size and ambient wind conditions. A component particle penetration model was developed by combining a potential flow model to calculate flow through and around a component with a filtration model. The filtration model combines classical filtration theory with simple bench-top experiments to determine net particle penetration. The component model predictions of particle penetration through a cylindrical component suggest that its filtration performance is strongly dependent on particle size and ambient wind velocities. To test model predictions, wind-tunnel experiments were conducted over an ambient wind velocity range of 10–80 mph (5–40 m s?1) and particle diameter range of 10 nm to 2 μm. The experimental results validated model predictions of particle penetration through a cylindrical component. The component model can be extended to model the integrated IPE system considering it to be composed of a combination of cylindrical components.Copyright 2013 American Association for Aerosol Research 相似文献
9.
Shank Laura K.; Kaufman Jacqueline; Leffard Stacie; Warschausky Seth 《Canadian Metallurgical Quarterly》2010,55(2):188
Objective: To examine between-groups differences in the associations between aspects of processing speed assessed with an inspection time task and attention-deficit/hyperactivity disorder (ADHD) symptoms. Research Design: Two groups comprising 34 children with cerebral palsy (CP) and 70 nonaffected peers (control), ages 8–16 years, participated in a prospective correlational study. Measures included a visual inspection time task and the Conners' Parent Rating Scale—Revised: Long Version. Results: Children with CP exhibited significantly slower processing speed and more symptoms of inattention and hyperactivity than controls. Significant associations between inspection time and ADHD symptoms were found only in the control group. Conclusions: Findings have implications for clinical assessment and understanding of attentional risks associated with CP. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
The limitations of State Standard GOST 20330-91 for determining the swelling index are demonstrated in relation to coal with
good clinkering properties. An expanded scale of standard profiles for coal identification is proposed. 相似文献