PARAMETER ESTIMATION OF MULTI-CONSTITUENT WATER QUALITY MODEL FOR THE LIANGXI RIVER BY MARQUARDT METHOD

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EVALUATING THE STABILITY OF OUTDOOR RECREATION PARTICIPATION MODELS*

Application of forecasting models reveals that parameter estimates vary substantially among regions reflecting spatial variation in consumer preferences and behavior. We present a simulation methodology to evaluate the stability in performance of recreation participation models between different regions. The sample data consisted of 632 household interviews obtained via random digit dialing techniques as part of Oklahoma's 1980 statewide survey of outdoor recreation demand. Three variables, the age of the head of the household, the number of household members, and distance to the facility were consistently accurate predictors of participation; the performance of other variables depended directly upon unknown attributes of the specific region.     

THE EXPANSION METHOD: IMPLICATIONS FOR GEOGRAPHIC RESEARCH*

Geographic phenomena and our models of them are closely linked to the spatial-temporal contexts in which they are observed. The expansion method is a procedure that incorporates contextual effects into mathematical models. More importantly, it is the basis for a movement by some geographers away from the classical spatial science paradigm. The evolving paradigm associated with the expansion method represents a reformulation of the way in which geographers think about and use models, and is consistent with a more realistic perspective on the nature of geographic inquiry.     

A STATISTICAL APPROACH TO THE PROBLEM OF MISSING SPATIAL DATA USING A FIRST-ORDER MARKOV MODEL*

Geographical data sets sometimes contain missing observations that need to be estimated. A statistical approach to the problem is discussed for multivariate normal spatial data sets satisfying the first-order spatial Markov property with constant mean, where the information at neighboring or contiguous observed sites is used to estimate the missing values. The completed data are used to estimate the parameters of the distribution. The procedure is iterative. The approach is a special case of the Orchard and Woodbury missing information principle. The paper concludes with an illustrative empirical example using rainfall data from an area of Kansas and Nebraska. The quality of the estimates for different sites are compared.     

THE GEOGRAPHY OF TICKET-SPLITTING: A PRELIMINARY STUDY OF THE 1976 ELECTIONS USING ENTROPY-MAXIMIZING METHODS*

Ticket-splitting is becoming increasingly common in American national elections, according to the results of voter surveys. Interstate variations in the amount and nature of ticket-splitting have been estimated using entropy maximizing methods. States are classified according to the degree and direction of ticket-splitting in the 1976 elections.     

THE RANK-SIZE MODEL: A NON-LOGARITHMIC CALIBRATION*

The rank-size model of city-size distributions is ordinarily calibrated by means of a logarithmic transformation. Because this procedure gives undue weight to the smallest cities, the regression results may be unrepresentative of the overall structure and regularity of the rank-size distribution. In order to avoid this problem a non-logarithmic calibration is proposed. Empirical tests indicate that the performance of the nonlog model is superior to that of the log model.     

南极冰盖地形数据库BEDMAP 2述评

南极冰盖物质收支与不稳定性对全球气候变化和海平面升高有着重要影响,而冰盖厚度和冰下地形则是研究南极冰盖的物质平衡、动力及不稳定性极为重要的参数。自20世纪50年代以来,国际上针对南极冰盖开展了大量的冰雷达以及重、磁测量,这些测量结果被汇集并形成冰厚和冰下地形数据库,进而服务于冰盖模式和地球系统研究,最新推出的成果便是BEDMAP 2(Bedrock Mapping Project 2)。首先介绍了BEDMAP 2的数据来源、结构以及数据处理,并讨论了数据的质量评价,然后分析了BEDMAP 2中展示的整个南极冰盖与冰下地形及其特点。最后,对于BEDMAP 2对中国在南极冰盖考察和研究方面的作用进行了一些讨论与展望。     

SECOND-ORDER ANALYSIS OF POINT PATTERNS: THE CASE OF CHICAGO AS A MULTI-CENTER URBAN REGION *

A comprehensive approach to the analysis of point patterns demonstrates the usefulness of second-order methods by exploring population distribution in the Chicago region. The methods are based on the development of a distribution of all interpoint distances representing the total covariation in a pattern. Clustering and inhibition models are explored with regard to the population pattern. Some evidence supports a multi-center city hypothesis for the region.     

SPATIAL ANALYSIS A NON-EVENT? THE CASE OF ZIMBABWE'S DEVELOPMENT PLANNING *

Development planning in Zimbabwe reveals little application of formal spatial analysis because of failures to apply available relevant research and because of the inapplicability of much spatial analysis itself for developing countries in Africa. Comparative studies of spatial analysis applied within the practice of development planning could provide some insights. If spatial analysis is indeed a non-event, the matter should concern academic geography.     

BUILDING A COLONIAL RESOURCE MONOPOLY: THE EXPANSION OF SULPHUR MINING IN NEW SPAIN, 1600–1820*

The discovery, extraction, and monopolistic control of key natural resources was a priority of New Spain's colonial administration. Managing the region's abundant resources, however, often proved difficult for the Spanish Crown. Human and environmental challenges impeded protoindustrial growth and development, and monopolistic control of resources often met resistance. In this article I examine these processes in the context of New Spain's little‐known monopoly on sulphur—a yellow, powdery mineral the Crown jealously guarded as its own. Sulphur was critical for gunpowder and explosives production, yet the Crown often failed to produce enough of it to meet the growing demand by its military and the silver blast‐mining industry. Colonial documents reveal administrators’ attempts to improve sulphur production through reform measures, which included advising sulphur miners on how to discover sulphur deposits and, eventually, how to develop their mines. Efforts to improve sulphur production were moderately successful, although the process was messy and inefficient.     

A PRELIMINARY STUDY ON COMBINING TWO KINDS OF PROXY DATA USING THE CONDITIONAL QUANTILE ADJUSTMENT METHOD

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MATHEMATICAL MODEL FOR THE OPTIMIZATION OF THE REACTION BETWEEN 2,3-BIS(m-TOLYL)QUINOLIZINIUM BROMIDE AND PIPERIDINE USING A FACTORIAL DESIGN

A number of nucleophiles have been successfully identified and quantified using the Krhnke reactionwith 2,3,-diphenyl derivatives of quinolizinium salts.Optimization of the reaction conditions by meansof a mathematical model involving analysis of the response surface has led to a better understanding ofthe factors exerting an influence on the above reaction.The parameters chosen were temperature,reaction time,base concentration,water concentration andnucleophile concentration.The reaction was developed in polar aprotic solvents(acetone,acetonitrile).To facilitate the nucleophilic attack,the presence of an organic base(triethylamine)was necessary,although concentrations in excess of 0.15M did not alter the development of the reaction.Sincepharmaceutical solutions are often aqueous,the influence of water on the reaction was studied.Lowwater volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilicreagent.However,when the water proportion exceeded that of the organic solvent,the fluorescenceintensity was lower than expected.Development of the fluorescent reaction product was first detected5 min after the reaction started.The fluorescence intensity reached its optimum value after 138 min.     

A PLACE UNBECOMING: THE COFFEE FARM OF NORTHERN LATIN AMERICA*

ABSTRACT. This article examines recent transformations of the coffee landscape of northern Latin America through the optic of “place as process.” As coffee became the most important regional export crop, its “place” evolved. Coffee lands in northern Latin America now embrace 3.1 million hectares, often contiguous across international borders. Like many agricultural systems, coffee has succumbed to intensification, a process termed “technification” in the Latin American setting. The result is a landscape mosaic in which a traditional agro-forest coffee system coexists with coffee lands transformed by modernization. The institutional forces behind this process, as well as some of its social and ecological consequences, are discussed.     

FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND‐REDISTRIBUTION PROGRAM*

ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land‐reform programs. In this study we examine land‐redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross‐section of projects in these two locales we develop a political ecology of stymied land‐reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white‐owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land‐redistribution beneficiaries, as well as on an analysis of land‐use change in Limpopo Province.     

BEYOND TWISTER: A GEOGRAPHY OF RECREATIONAL STORM CHASING ON THE SOUTHERN PLAINS*

ABSTRACT. Storm chasing is widely perceived as a new form of extreme sport or adventure travel. Each spring increasing numbers of tourists descend on the Southern Plains, the center of storm chasing in the United States, but little is known about their activities. According to longtime chasers, popular portrayals of storm pursuits are highly misleading, and growing participation in the sport is affecting storm chasing in the region. This study introduces the storm-chasing enterprise. Using route information and comments supplied by veteran chasers, I describe the spatial patterns of storm-chasing on the Southern Plains. Comparing the behavior and motivations of longtime enthusiasts with popular portrayals of the activity permits me to dispel many myths and to discuss the nature and future of this growing but little-understood recreational pursuit.     

THE ECONOMIC VALUE OF RIPARIAN CORRIDORS IN CORNBELT FLOODPLAINS: A RESEARCH FRAMEWORK*

A new research framework determines the economic value of riparian corridors in floodplains of the agricultural Midwest. Market mechanisms can fail to account for many positive attributes of riparian wetland ecosystems. Individual farmers frequently make socially inappropriate decisions regarding floodplain land-uses because the benefits accruing from wetlands, such as improved water quality and enhanced recreational activities, are public goods. A spatial economic model, based on willingness-to-pay procedures, assesses the apposite mix of agricultural/wetland land uses that compares the marginal value of natural riparian vegetation and agricultural production on rural Cornbelt floodplains. A simple case study illustrates the framework.     

面向对象的电子地图创作模型—国家经济地图集（电子版）软件设计研究

本文系统地描述了电子地图创作系统ＭａｐＭａｇｉｃ的设计思想和实现技术。文章根据电子地图的新特点，运用面向对象的方法技术提出了电子地图的概念模型，并给出了其计算机形式化表示－电子地图模型。在此基础上，研究地图创作的任务，建立起面向对象的电子地图创作模型，并详细讨论了该创作模型的体系结构、组成要素及其实现机制。按照上述思想设计的ＭａｐＭａｇｉｃ软件系统应用到《中华人民共和国国家经济地图集》（电子版）开     

用雷达电磁波探测研究南极冰盖浅层散射特征:以中山站至Dome A冰盖断面为例

本研究运用双频雷达(60MHz和179MHz)获取的南极中山站-Dome A断面的雷达回波探测数据,对冰盖浅部100-700m的雷达内部反射层和接收功率变化定量计算分析表明,60MHz的雷达回波能量比179MHz衰减得更快;中山站-Dome A断面冰盖浅层700m以上的雷达反射层形成的主导原因是冰密度的变化;断面上不同测站点间同一深度的接收功率差值达到10dB,表明冰盖浅层散射存在显著差异。     

金字塔沙丘风洞流场结构的实验研究——兼论金字塔沙丘发育模式

金字塔沙丘以其大尺度、金字塔形态和放射状伸展的沙臂为特征。本文以三面体金字塔沙丘模型的风洞流场实验为基础,结合野外观测资料,发现金字塔沙丘的流场结构,特别是背风侧剖面流场除具有一般新月形沙丘的流场结构特点外,还有特殊的"E"型流场结构,正是这种多向风信产生的复杂流场结构形成具有凹面形态的多角形金字塔沙丘。据此,作者提出了由新月形沙丘(包括其复合形态)演化为金字塔沙丘的发育模式。