山地地区地表一致性剩余静校正技术应用技巧

山地地区地表和地下地质条件复杂,接收条件差,原始资料信噪比低,做剩余静校正前很难准确的识别有效速度,经过几次速度分析和剩余静校正后,才得到容易辨认的速度,但是由于初始速度和初始静校正量的误差问题,往往剩余静校正的迭代不是收敛的,得不到真实的地下构造形态。只有采用比较合理的求取初始速度方法,才能保证得到真实合理的成像。     

Social capital,risk preference and adoption of improved farm land management practices in Ethiopia

Many developing countries grapple with high rates of farmland degradation and low agricultural productivity amidst increasing climate variability. Considerable efforts have been exerted to promote the diffusion of improved farmland management to address these challenges. Despite these efforts, adoption rates, especially of soil conservation and water harvesting technologies, are still low, which has been the subject of investigation in several studies in Ethiopia and elsewhere. Most studies on the adoption of these technologies, however, tend to focus on economic incentives only, paying little attention to the role of social capital. This article provides evidence of the effects of different dimensions of social capital on innovation adoption across households holding different levels of risk aversion. We address this issue by using cross section and panel data from Ethiopia. Results show that social capital plays a significant role in enhancing the adoption of improved farmland management practices. We also find evidence that the effect of social capital across households with heterogeneous risk taking behavior is different.     

Aggregating forest harvesting activities in forest plantations through Integer Linear Programming and Goal Programming

The inclusion of criteria related to the spatial patterns resulting from forest harvesting activities is an important component of forest planning. Harvesting operations are more efficient when the harvesting areas are clustered. Therewith, it is possible to reduce the displacement of machinery and costs related to construction and maintenance of the road network. In this context, the objective of this study was to evaluate different strategies for aggregating harvesting stands in a forest plantation. We applied two Goal Programming approaches aiming at aggregating harvesting stands and an Integer Linear Programming model for including road investments into strategic forest planning.     

我国植物油籽在东亚市场上的竞争力研究

运用实证研究方法,从出口价格、产品质量、市场渗透程度三个方面对我国植物油籽在东亚市场上的竞争力进行评价。结果表明：目前,我国植物油籽竞争力在日本市场上较弱,在韩国市场上较强,需要依靠科技进步、绿色环保等方式来增强竞争力。     

水稻的收割与秸秆回收系统的设计

本文主要介绍了收割部分和秸秆回收部分的总体设计。解决高产超级稻的收获问题。割前脱粒(梳脱式)机型由于作业时茎秆不进入机器中,可以减少机具对物料的处理量、降低损失、减少功耗、提高工作效率,是解决超级稻收获的理想机具之一。     

The Bioeconomics of the Spatial Distribution of an Endangered Species: The Case of the Swedish Wolf Population

Conservation of endangered species often entails significant costs, and, from a social perspective, many species can be characterized as both environmental bads and goods. This paper concerns the management of one such species, the Swedish wolf (Canis lupus). The fact that the wolf tends to disperse over a wide area causes specific management problems. The goal is to choose a harvesting strategy, such that the discounted stream of net benefits from the wolf populations in different geographical regions is maximized. The spatial dimension is involved through emigration and immigration. The solution to the management problem is shown to be a modification of the classical rule of renewable resource exploitation, caused by the migration of wolves between regions. Empirically, this problem is solved by dividing Sweden into 13 geographical regions, and accounting for the existence values, harvesting benefits, and predation costs of the wolf population in each region. The results show that the geographical distribution of wolves, in absolute numbers, is very sensitive to the abundance of prey and to different assumptions regarding the economic parameters of the model. However, the relative distribution of wolves across the country is less sensitive to these assumptions. The highest densities of wolves were found in regions with low marginal costs, due to the abundance of prey in relation to the comparatively low number of human hunters utilizing the same prey as the wolves. The lowest population densities were found in regions with a low carrying capacity for the wolf or with high costs of depredation on reindeer.     

Challenges of the maize seed industry in eastern and southern Africa: A compelling case for private–public intervention to promote growth

Following the liberalization and restructuring of the seed sector, the maize seed industry in eastern and southern Africa has witnessed a proliferation of private seed companies. Whereas the total number of registered maize seed companies in major maize producing countries increased four-fold between 1997 and 2007, the quantity of seed marketed barely doubled suggesting that the seed production and deployment environment is less than perfect.     

茶叶籽油改性制备生物柴油工艺研究

以茶叶籽油和甲醇为原料,KOH为催化剂,对酯交换制备生物柴油工艺进行研究。在单因素试验的基础上,通过正交试验得出茶叶籽油制备生物柴油的优化工艺条件为:醇油摩尔比11∶1,KOH用量(占原料油质量的百分比)1.0%,反应温度60℃,反应时间70 min。在此条件下,酯交换率为98.64%,并对所得生物柴油进行红外光谱表征。     

降低压榨油茶籽油中苯并芘含量关键加工技术的研究

针对传统压榨油茶籽油中苯并芘含量超出国家标准限量要求的情况,分析了苯并芘产生的原因和关键步骤,提出降低压榨油茶籽油中苯并芘含量的解决方案.研究表明,通过部分脱壳和控制油茶籽的干燥温度不超过45℃、炒籽不焦糊,压榨后辅以0.1％～0.2％活性炭低温吸附是有效降低压榨油茶籽油中苯并芘含量的关键加工技术.     

植物人工种子及在观赏植物中的应用

人工种子技术是20世纪80年代中期发展起来的技术,是当前研究的热点,概述了植物人工种子的制备、贮藏等问题,并探讨了在观赏植物中的应用前景。