An analytic model of the core of a supernova     

Richard C. Adams  Boyd B. Cary  Jeffrey M. Cohen 《Astrophysics and Space Science》1994,213(2):205-232

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Fractal characterization of the South Australian gravity station network   总被引：1，自引：0，他引：1  

G. Korvin  D. M. Boyd  R. O'Dowd 《Geophysical Journal International》1990,100(3):535-539

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New perspectives on Titan's upper atmosphere from a reanalysis of the Voyager 1 UVS solar occultations     

Ronald J. Vervack Jr.  Bill R. Sandel 《Icarus》2004,170(1):91-112

We have reanalyzed the Voyager 1 UVS solar occultations by Titan to expand upon previous analyses and to resolve inconsistencies that have been noted in the scientific literature. To do so, we have developed a detailed model of the UVS detector and improved both the data reduction methods and retrieval techniques. In comparison to the values previously determined by Smith et al. (1982, J. Geophys. Res. 87, 1351-1359) we find N₂ densities that are 25-60% higher, CH₄ densities that are smaller by a factor of 3-7, and C₂H₂ densities that are roughly two orders of magnitude smaller. Our values for the thermospheric temperature are 153-158 K, which are approximately 20-40 K colder than previous estimates. We also report the first-ever determination from Voyager UVS data of density profile information for C₂H₄, HCN, and HC₃N. Finally, we present a simple engineering model that is consistent with our new results in the upper atmosphere and merges smoothly with the model of Yelle et al. (1997, in: HUYGENS Science, Payload and Mission, in: ESA SP, vol. 1177, pp. 243-256) in the lower atmosphere. Our results provide improved constraints for photochemical models and offer scientists a better understanding of Titan's upper atmosphere as we head into the Cassini era in the exploration of the saturnian system.  相似文献   

Retail enterprise across American regions: the role of black population size in the late nineteenth-century United States     

Robert L. Boyd 《GeoJournal》2018,83(2):305-317

Building on the idea that small-scale entrepreneurship often takes place in peripheral regions, the present study examines retail enterprise in the late nineteenth-century U.S., focusing on ethnic group differences across the North, South, and West. Applying theories of middleman minorities and internal colonialism, the study proposes that European immigrants and native whites had their highest retail enterprise levels in the South, where large, oppressed black populations were compelled to patronize non-black merchants, owing to a dearth of black retail proprietors. Multiple regression analyses of Census data support this proposition, calling attention to the importance of black population size as a heretofore neglected factor in regional variation in retail enterprise among European immigrants and native whites in late nineteenth-century America.  相似文献   

Managing Groundwater to Ensure Ecosystem Function     

Laurel Saito  Bill Christian  Jennifer Diffley  Holly Richter  Melissa M. Rohde  Scott A. Morrison 《Ground water》2021,59(3):322-333

Groundwater is a critical resource not only for human communities but also for many terrestrial, riparian, and aquatic ecosystems and species. Yet groundwater planning and management decisions frequently ignore or inadequately address the needs of these natural systems. As a consequence, ecosystems dependent on groundwater have been threatened, degraded, or eliminated, especially in arid regions. There is growing acknowledgment that governmental protections for these ecological resources are necessary, but current legal, regulatory and voluntary provisions are often inadequate. Groundwater management premised on “safe yield,” which aims to balance human withdrawals with natural recharge rates, typically provides little to no consideration for water needed by ecosystems. Alternatively, the “sustainable yield” concept aims to integrate social, economic and environmental needs for groundwater, but the complexity of groundwater systems creates substantial uncertainty about the impact that current or future groundwater withdrawals will have on ecosystems. Regardless of the legal or regulatory framework, guidance is needed to help ensure environmental water needs will be met, especially in the face of pressure to increase human uses of groundwater resources. In this paper, we describe minimum provisions for planning, managing, and monitoring groundwater that collectively can lower the risk of harm to groundwater-dependent ecosystems and species, with a special emphasis on arid systems, where ecosystems and species may be especially reliant upon and sensitive to groundwater dynamics.  相似文献   

Coal mine water management: optimization models and field application in North China     

Qiang Wu  Bill X. Hu  Li Wan 《水文科学杂志》2013,58(4):609-623

Abstract

This paper considers the complexity in resolving the conflicts between mine drainage, water supply, and environmental protection for the coal basin of North China, and presents a management optimization framework that addresses these multiple conflicting issues simultaneously in the most cost effective manner. Due to the various unpredictable accidents which may occur in the coal mining process, such as water bursts, gas leaks, fire and collapse of coal beds, the beneficial use of drainage water from the coal mines is generally low. This case study attempts to address the problem of low beneficial usage for drainage water using the Jiaozuo coal mining district in Henan Province, China. By combining a finite-element groundwater simulation model with an optimization code, the economic benefits of using the drainage water as a stable water supply is maximized, while the adverse impact of mine drainage on the environment is controlled. The results indicate that the management model developed in this study achieves an excellent economic outcome and can serve as a potentially powerful tool for solving mining-related water management problems in the coal basin of North China.

Citation Wu, Q., Hu, B. X., Wan, L. & Zheng, C. (2010) Coal mine water management: optimization models and field application in North China. Hydrol. Sci. J. 55(4), 609–623.  相似文献   

Editorial – GGR Cutting Edge Reviews     

Thomas Meisel  Michel Grégoire  Bill McDonough  Christophe Quétel  Jon Woodhead 《Geostandards and Geoanalytical Research》2013,37(2):109-109

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Editorial – New GGR Editorial Board     

Thomas Meisel  Michel Grégoire  Bill McDonough  Christophe Quétel  Jon Woodhead  Edward Williams 《Geostandards and Geoanalytical Research》2013,37(3):237-242

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Retail and wholesale enterprise among ethnic groups in core and peripheral urban centers: the late-nineteenth-century United States   总被引：1，自引：1，他引：0  

Robert L. Boyd 《Urban geography》2013,34(3):454-470

Ethnic entrepreneurs often benefit from reciprocal relationships, such as buyer–supplier linkages, among co-ethnic businesses. The present study extends this insight, analyzing census data on the relationship between ethnic enterprise in the retail trade and co-ethnic enterprise in the wholesale trade in urban centers of core and peripheral regions of the late-nineteenth-century United States. As expected, this relationship varied markedly by ethnicity and region. For some groups (e.g., Russians), co-ethnic retail and wholesale enterprises were positively related on the periphery but not in the core; conversely, for other groups (e.g., Irish), co-ethnic retail and wholesale enterprises were positively related in the core but not on the periphery. The results imply that reciprocal relationships among co-ethnic businesses are significantly affected by variation in the characteristics of local opportunity structures across urban-regional locations.  相似文献   

Family or Enterprise? What shapes the business structures of Australian farming?     

Sally Weller  Erin F. Smith  Bill Pritchard 《The Australian geographer》2013,44(2):129-142

Australian farmers navigate their contemporary circumstances through the use of different business and legal arrangements that are shaped by the commercial realities of farming and the aspirations of farm-owning households. In posing the question ‘Family or Enterprise?’, this paper examines the extent to which various household and farm business indicators are associated with different forms of farm ownership, namely sole proprietorships, partnerships, trusts and companies. Results from a postal survey of farm enterprises in Victoria, Australia suggest that both household and enterprise factors contribute to the business structure used, although the strongest determinants appear to be those factors that are less well understood in the rural geographical and sociological literature: household composition, farmer age and farm size. Greater scrutiny of the business instruments deployed by farmers to manage family and enterprise pressures should inform expectations of the fate of family farming in advanced financialised economies.  相似文献