泰国生物燃料政策及其启示

为了减少对进口石油的依赖、为了实现减排承诺、为了发挥农业资源优势、增加农民收入,泰国皇室、文官和军人政府都致力于发展乙醇汽油和生物柴油,并倡导把泰国发展成东盟的乙醇贸易中心,把东盟发展成世界生物燃料贸易中心。本文梳理了泰国生物燃料发展政策并指出其经验和存在的问题,为今后制定合理的生物燃料政策提供了思路。     

压力利用率与锤耗的关系研究

主要从六面顶压机顶锤对合成块施压的过程中,合成块所承受压力的受力分析,研究压力变化对锤耗的影响,总结出合成块组装高度设计、试验的理论依据,提出了检验组装高度的技术指标,提高设计可靠性,缩短试验周期,减少生产过程中的顶锤消耗。     

Height matters: practicing consumer agency,gender, and body politics

The significance of body and gender in the formation of consumers’ identities and agencies has been widely scrutinized. Nevertheless, this study argues that this formation is not fully understood, unless the role of height is taken into account. It leans on a practice-based perspective and critical auto-ethnographic methodology so as to examine how a distinct agency is fabricated for a short-sized female body by a whole range of social, material, and sensory practices that are continuously enacted across various domains of life. It thereby adds to the existing literature on body, gender, and consumer agency by way of incorporating height into critical inquiries this far mostly concerned with weight; by way of materializing and sensorializing the fabrication of an embodied consumer agency this far addressed in visual terms; and by way of considering everyday life as the site in which it continuously unfolds. These insights bear important implications for the development of body politics.     

Profitability and opportunity of conservation agriculture in acid savannah grasslands of Laos

In north-eastern Laos, the savannah grasslands of the Plain of Jars cover vast areas of potentially cultivable land. However, soil acidity, low inherent fertility, and the absence of alternatives to tillage represent significant constraints to the development of sustainable smallholder agriculture. Our objective was to evaluate the potential for conservation agriculture (CA) to enhance soil productivity and farming system profitability. A three-year rotation of rice/maize/soybean was tested under three fertilization levels and four agricultural systems: one conventional tillage-based (CT) system and three CA systems based on no-tillage with cover crops. After four cropping seasons, our results show that, compared with CT, CA systems led to similar-to-higher grain production, similar-to-higher profits, higher opportunity of livestock system intensification, and higher labour productivity regardless of fertilization levels. While CA represents a relevant alternative to current practices, our results suggest that its contribution to the emergence of a sustainable smallholder agriculture is conditioned by broader institutional transformations, including the enrolment of local manufacturers and traders for deploying no-till implements and seed market channels for cover crops, long-term public support to maintain active research and technical mentoring to farmers, and possibly the integration of ecosystem services in agricultural policy.     

高瓦斯条件下大采高开采技术应用

寺河矿作为原国家计委批准的九·五期间国家重点建设矿井,是国内唯一一座高瓦斯条件下开采的千万吨级大型现代化矿井。矿井在瓦斯治理、大采高采煤工艺、综采技术装备、技术创新、安全管理等方面进行了大量探索、实践,在高瓦斯等复杂地质条件下,走出了一条高产高效之路。     

Pricing farm-level agricultural insurance: a Bayesian approach

This paper applies Hierarchical Bayesian Models to price farm-level yield insurance contracts. This methodology considers the temporal effect, the spatial dependence and spatio-temporal models. One of the major advantages of this framework is that an estimate of the premium rate is obtained directly from the posterior distribution. These methods were applied to a farm-level data set of soybean in the State of the Paraná (Brazil), for the period between 1994 and 2003. The model selection was based on a posterior predictive criterion. This study improves considerably the estimation of the fair premium rates considering the small number of observations.      

种植业保险需求调查分析

我国是世界上自然灾害最为频繁的国家之一。灾害种类多、频度高、分布广、损失大。2003、2004、2005年农业成灾面积占播种面积的比重分别为21.33%、10.61%、12.84%。近几年灾害造成的粮食损失每年都在400亿公斤以上,经济损失每年都在600亿元以上。种植业保险是降低种植业风险的有效手段,伴随灾害而来的巨大损失使越来越多的农民保险意愿日益强烈。在这种情势下,种植业保险却出现了日益萎缩的怪现象,陷入了"供给不足,需求有限"的困境。笔者对鄱阳湖湖区进行了实地调查分析,以求解决种植业保险的供给与需求矛盾。     

China,More than Self-Sufficient

At the moment,the whole world faces the most severe inflation in food prices in history,as grain and soybean prices climb to all-time highs.Although some observers blame the weather for the decrease in crop yields and that the growing demand for cereals used for bio-fuel production has conspired toward continuous price rises on world grain ma ket;others regard it simply as a matter of demand outpacing supply.In seven of the last eight years,world grain production has fallen behind rates of consumption.     

深度学习方法在作物遥感分类中的应用和挑战

[目的]准确估算作物的面积和分布对粮食安全至关重要。与传统的机器学习方法相比,深度学习具有多种优势,如端到端训练、可迁移性。为有效利用高时空数据进行作物识别提供了新的机遇。已有多种模型被应用于作物分类任务中,针对不同的分类任务,如何有效地选择模型,并对其进行训练和使用已成为关键问题。[方法]文章回顾了利用深度学习模型对作物分类的主要研究。N维卷积神经网络(N-D CNN)(N=1、2、3)和递归神经网络(RNN)已被有效用于作物分类任务。长短期记忆RNN(LSTM RNN)和门控循环单元RNN(GRU RNN)是RNN的变体,解决了随着时间序列增加RNN出现的梯度消失或爆炸问题。此外,还有研究使用CNN和RNN(我们称为RCNN)的混合模型对作物进行分类。该文首先阐述了使用深度学习方法进行作物制图的背景和意义,并介绍了CNN和RNN模型结构。然后回顾了一些典型的研究,包括模型的结构、遥感数据源、数据处理方法和分类精度。最后,总结了使用深度学习方法进行作物分类的挑战以及现有解决方案的局限性。[结果](1)1-D CNN可用于提取时间特征,或时间+光谱特征,分类效果良好;2-D CNN已被广泛应用于单时相数据的空间特征提取,分类精度依赖于数据源;3-D CNN应用较少,但具有很大的潜力,尤其是时间+空间维度的特征提取;(2)相同条件下(架构、数据源、研究区域、类别),LSTM RNN和GRU RNN分类效果通常高于普通RNN,而前两者的效果差距不大,但GRU RNN训练时间较短;(3)CNN+RNN混合模型(RCNN)用RNN比3-D CNN更适合提取时间特征。这主要是由于RNN建立了对序列数据的长期依赖,而3-D CNN卷积核是局部计算的。[结论]通过分析,认为深度学习技术是作物遥感分类的有效工具。此外,与其他模型相比,RCNN,3-D CNN和GUR RNN具有更大的潜力。