Seasonal Migrant Labor in the Forest Industry of the Southeastern United States: The Impact of H-2B Employment on Guatemalan Livelihoods

Migrant labor is a global phenomenon and remittances of migrant workers from non-industrial nations can play an important role in improving quality of life at family, community, and national levels. We focus on workers from Guatemala who obtain visas from the United States (US) Department of Immigration’s H-2B program that allow them to spend six or seven months a year planting and maintaining pine plantations in the southeastern US. Forestry is economically important in this region and the industry has come to depend on migrant labor. Our specific interest is how the H-2B program affects livelihood strategies of these workers, their families, and their communities. Based on primary data from 49 interviews conducted in eight Guatemalan communities, we explain motivations to engage in seasonal migration and positive changes brought about by the H-2B program in nutrition, housing, healthcare and long-term investments in agricultural lands, microenterprise development, education, and family stability.     

GIS技术支持下的龙川江流域退耕还林规划方法

利用GIS技术,结合退耕还林的基本原则,通过空间分析的研究方法,对土地利用、坡度、河流、居民点等数据库进行处理,对云南省龙川江流域进行科学、定量的退耕还林规划,解决退耕还林的耕地在哪儿、如何退,以及退耕还林时序等一系列技术难题,实现规划自动化。这将为政府决策提供翔实、高可信度的数据,也可为县级退耕还林规划做示范。     

Environmental problems in the Sudetes, Poland

Due to the abundance of mineral deposits associated with the metamorphic rocks of the Sudetes, the area was intensively settled and developed by the end of the Middle Ages. Several centuries later, the first attempts were made to rehabilitate the devastated natural environment. The advent of capitalism brought further damage to the environment, which has remained almost unchanged to this day. Improvements in the context of transfrontier cooperation have arisen out of the economic crisis and the disintegration of the Soviet bloc. However, the Sudetes are still a problem area, and various industries are competing for local resources. The main problem facing the region is the need to rehabilitate its natural environment and create a more balanced local economy. Tourism, forestry, agriculture and ‘clean’ industrial technologies have the greatest potential. This revised version was published online in July 2006 with corrections to the Cover Date.     

Where Forest Carbon Meets Its Maker: Forestry-Based Offsetting as the Subsumption of Nature

ABSTRACT

The “subsumption of nature” framework focuses on productivity increases and extractive innovations in nature-based industries. In this article, we argue that it can also be employed beyond that context in order to capture the convoluted dynamics of market environmentalism. To substantiate our argument, we draw on recent fieldwork on “Trees for Global Benefits,” a forestry-based offsetting project in western Uganda. Like industrial tree plantations, this project relies on the subsumption of carbon sequestration to market imperatives in order to guarantee the quality of its carbon credits. The ecological and socioeconomic difficulties this process engenders give rise to unintended consequences and set in motion the disciplining of the carbon offset producers themselves. The application of the subsumption framework to nonindustrial sectors in this way calls attention to the interlinked socioecological dynamics involved in the subsumption of nature, and highlights potential synergies with previous work on the subsumption of labor.     

全站仪构建全局测量空间的转站精度仿真分析

针对大尺寸工业测量范围大、精度要求高,通常需要进行转站测量来实现对全局测量空间的控制,而转站测量中的转站精度也是影响整体测量精度的关键。该文利用徕卡TM30全站仪测量系统作为测量手段,获取公共点坐标信息,采用Matlab软件编程,构建了转站精度分布模型,并对转站精度受公共点测量误差变化及待测点分布的影响进行了仿真分析。结果表明,在实际工程测量中构建全局测量空间时,通过对转站精度进行仿真分析,可实现对待测点布设方案的优化设计,提高整体的测量精度。     

基于SAPB的辐射井水平钻机方案设计研究

SAPB设计方法是目前国际上应用较广的一种设计方法及理论,该方法尤其是在产品的总体方案设计过程中,发挥着举足轻重的作用。本文利用该方法对辐射井水平钻机的整体方案设计进行研究。首先从分析水平钻机的总功能的角度出发,对钻机功能进行抽象化,然后利用SAPB设计方法中的分析工具,对总功能进行分解,建立水平钻机的功能分解树和功能结构图,最终得到钻机的整体设计方案。本文的研究可为钻机的进一步设计优化提供便利。     

页岩气井钻遇破碎地层的井身结构优化设计

页岩气的勘探开发和利用对于优化我国能源结构、促进能源工业快速发展、提高优质洁净能源的自给能力和水平,以及降低大气污染、促进环境保护等方面都有至关重要的作用。解决好页岩气井在钻遇破碎地层后的井身结构优化设计,就能够大幅度提高钻效,节省钻探成本,缩短勘探周期,从而促进页岩气资源的大规模开发利用。本文结合页岩气井的生产实践,就页岩气井钻遇破碎地层后井身结构的优化设计问题,特别是开次、选用孔径、套管规格及其下入深度等方面进行了探讨。     

中国林业发展的未来走势

以可持续发展理论为指导思想,从论述可持续林业是现代林业发展的新趋势入手,探讨了可持续林业的涵义、目标和内容,并提出了林业可持续发展的实施举措     

Forest conversion, conservation and forestry in Cross River State, Nigeria

This paper presents new data on the rate and patterns of loss of tropical moist forest cover to agriculture in Cross River State, Nigeria. Data from sequential aerial photographs and field surveys are used to derive an estimate of forest loss of 0.6 per cent per year. This rate is relatively modest, yet current conservation and forestry policy in the area is based on assumptions of rapid conversion of forest. The implications of these findings for debates about conservation and policy are discussed.     

约束最小二乘法优选单位线

在总结目前推求单位线方法的基础上,提出了一种改进的优化方法－－约束最小二乘法。它通过Ｗｉｎｄｏｗｓ平台上的可视化编程,不震拟定初始单位线和试错,就能快速准确达到单位线的最优适配,并能够在计算机上实现推求和修匀单位线。