高标准农田的景观生态化设计和优化——以H市为例

通过H市高标准农田建设过程中田块生态设计工程、灌溉与排水工程、田间道路生态工程、农田防护与环境保持工程等方面的设计,重点研究建设过程中的生态化设计和优化方法,调整、优化景观组分、田块的空间分布格局,使各组分之间达到和谐、有序形成生态环境的安全统一性,提高农田生产力和景观生态稳定性,为合理建设高标准农田提供了科学依据。     

Hydrogen: Its Future Role in the Nation's Energy Economy

In examining the potential role of hydrogen in the energy economy of the future, we take an optimistic view. All the technology required for implementation is feasible but a great deal of development and refinement is necessary. A pessimistic approach would obviously discourage further thinking about an important and perhaps the most reasonable alternative for the future. We have considered a limited number of alternative energy systems involving hydrogen and have shown that hydrogen could be a viable secondary source of energy derived from nuclear power; for the immediate future, hydrogen could be derived from coal. A hydrogen supply system could have greater flexibility and be competitive with a more conventional all-electric delivery system. Technological improvements could make hydrogen as an energy source an economic reality. The systems examined in this article show how hydrogen can serve as a general-purpose fuel for residential and automotive applications. Aside from being a source of heat and motive power, hydrogen could also supply the electrical needs of the household via fuel cells (19), turbines, or conventional "total energy systems." The total cost of energy to a residence supplied with hydrogen fuel depends on the ratio of the requirements for direct fuel use to the requirements for electrical use. A greater direct use of hydrogen as a fuel without conversion to electricity reduces the overall cost of energy supplied to the household because of the greater expense of electrical transmission and distribution. Hydrogen fuel is especially attractive for use in domestic residential applications where the bulk of the energy requirement is for thermal energy. Although a considerable amount of research is required before any hydrogen energy delivery system can be implemented, the necessary developments are within the capability of present-day technology and the system could be made attractive economically .Techniques for producing hydrogen from water by electrolysis, from coal, and directly from thermal energy could be found that are less expensive than those now available; inexpensive fuel cells could be developed, and high-temperature turbines could be used for the efficient conversion of hydrogen (and oxygen) to electricity. The use of hydrogen as an automotive fuel would be a key factor in the development of a hydrogen energy economy, and safe storage techniques for carrying sufficient quantities of hydrogen in automotive systems can certainly be developed. The use of hydrogen in automobiles would significantly reduce urban pollution because the dispersed fossil fuel emissions would be replaced by radioactive wastes generated at large central stations. The conversion of internal or external combustion engines for combustion of hydrogen fuel would probably have less economic impact on the automotive industry than the mass introduction of electric automobiles. However, this is a subject that requires more detailed study. All of the safety aspects of hydrogen utilization will have to be examined, especially the problems of safety in the domestic use and the long distance transport of hydrogen in pipelines at high pressures. It is our opinion that the various energy planning agencies should now begin to outline the mode of implementing hydrogen energy delivery systems in the energy economy. The initial transition to hydrogen energy derived from available fossil fuels such as coal should be considered together with the long range view of all the hydrogen being derived eventually from nuclear energy. By the year 1985 when petroleum imports may be in excess of the domestic supply, these plans could set the stage for the transition period from fossil to a predominantly nuclear energy economy able to supply abundant synthetic fuels such as hydrogen. Synthetic fuels will obviously be more expensive than fuels now derived from petroleum; however, there may be no other viable choice. Thus, it is essential that the analysis and technological feasibility of a hydrogen energy system be considered now. It is of vital importance to the nation to develop some general-purpose fuel that can be Produced from a variety of domestic energy sources and reduce our dependence on imported oil.     

生物质热解液化技术的生命周期评价

为探究生物质热解液化技术能源转化过程的效率、经济性及温室气体排放,依据全生命周期评价分析原理,建立废弃秸秆热解制备液体燃料技术全生命周期模型,对该过程进行全生命周期分析,评价范围包括秸秆的收集和运输、干燥和粉碎、生物质热解、木炭加工和余热利用。结果表明：生物质热解液化技术的能量产出投入比为20.43;处理湿秸秆的纯利润约为289.38元/t,销售利润率达52.11%;CO₂当量排放为34.10 g/MJ。生物质热解液化是一种兼具能量效益、经济效益和环境效益等极具潜力的生物质利用技术。     

Impacts of soil faunal community composition on model grassland ecosystems

Human impacts, including global change, may alter the composition of soil faunal communities, but consequences for ecosystem functioning are poorly understood. We constructed model grassland systems in the Ecotron controlled environment facility and manipulated soil community composition through assemblages of different animal body sizes. Plant community composition, microbial and root biomass, decomposition rate, and mycorrhizal colonization were all markedly affected. However, two key ecosystem processes, aboveground net primary productivity and net ecosystem productivity, were surprisingly resistant to these changes. We hypothesize that positive and negative faunal-mediated effects in soil communities cancel each other out, causing no net ecosystem effects.     

"三农服务"农业院校图书馆重新定位

农业、农村、农民问题,实质就是解决农民收入问题。“农业问题的根本出路还要靠尖端技术,”“科学技术是第一生产力”。要从根本上解决三农问题,要以科学技术为先导,以推广和普及农业科技成果,提高农业劳动生产率,提高和促进农、林、牧、副、渔全面发展的综合的系统工程。根据图书馆近一年来服务实践,探讨了情报服务的新路子。     

提高农业科技服务能力 推进农村小康社会建设

中国全面建设小康社会重点在农村,难点在如何增加农民收入,很大程度上取决于如何为八亿农民提供农业科技服务,促进农业技术创新和科技成果转化为现实生产力。本文从中国农业生产的现状、科技服务“缺位和滞后”和力量不足等问题入手,提出改革现行的农业科技运行和转化机制、开展科农携手共建利益共同体、发挥示范榜样作用、提高劳动者的科技素质等对策,促进科学研究面向生产第一线和科技成果直接应用于生产,为农民提供全方位、多层次、多领域的科技服务,推进农村全面建设小康社会进程。     

苹果品种间经济效益对比分析

本文基于“晋光“和”国光”两个品种十四年的投入产出资料,建立苹果品种间经济效益对比的指标体系及计算方法,用Y=Ax~3+Bx~2+Cx+D逐步回归拟合,确立了两品种幼树期—盛果期的树龄与产量、产值、纯收入、龄均纯收入和累计成本盈利率间的回归关系,并从树龄、资金利用、土地利用的经济效益进行对比分析。     

Methane from anaerobic fermentation

Conventional anaerobic digestion is an established technology for wastewater stabilization, but methane production rates and net energy yields are generally too low to make the process competitive as a source of methane. Numerous improvements are being developed to make conversion of plant biomass to methane and simultaneous waste stabilization-methane production practical. Among these improvements are innovative-digester designs and process configurations. Efforts to commercialize modern anaerobic digestion technology are progressing.     

生物质制备航空燃油级烷烃的研究进展

为降低航空燃油制备及使用过程中的碳排放,从1999—2017年已发表的56篇文献,总结生物质制备航空燃油的多条关键路径及特点,重点分析碳水化合物液相化学催化转化制航油的方法。结果表明,通过制备不同种类的平台化合物,控制缩合条件,利用碳水化合物可以制得具有较好物化性能的航油级烷烃。同时提出了一条利用木质素转化的有效路径——采用氧化预处理技术,预先活化木质素中的关键化学键,使之后续能在温和条件下高效可控降解,而后加氢脱氧得到含有合适碳数的芳烃或环烷烃。展望未来,该领域需开发温和高效的生物质预处理方法,合成高水热稳定性、廉价催化剂,降低氢气用量和反应温度,同时考虑生物质原料的整体一锅化转化,为规模化生产创造条件。     

生物质制备航空燃料的技术研究及应用

石油的枯竭危机和日益加重的减排压力,使航空燃料的发展面临了巨大的挑战,探寻可再生的清洁燃料成为了世界各国的研究焦点.航空生物燃料作为可持续发展的清洁燃料受到了国内外研究者的重视.主要简述了航空燃料的组成、技术要求和制备原料,主要介绍了费托合成、酯类和脂肪酸加氢工艺、热化学转化法和生物转化法4种主要工艺,其中酯类和脂肪酸的加氢工艺便于投入生产,是最有应用前景的工艺,目前已有多家国内外企业应用4种工艺投入生产和销售,未来不久航空生物燃料会为缓解石油危机和减排压力做出巨大贡献.     

Lowering the temperature of solid oxide fuel cells

Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy.     

High-performance solid Acid fuel cells through humidity stabilization

Although they hold the promise of clean energy, state-of-the-art fuel cells based on polymer electrolyte membrane fuel cells are inoperable above 100 degrees C, require cumbersome humidification systems, and suffer from fuel permeation. These difficulties all arise from the hydrated nature of the electrolyte. In contrast, "solid acids" exhibit anhydrous proton transport and high-temperature stability. We demonstrate continuous, stable power generation for both H2/O2 and direct methanol fuel cells operated at approximately 250 degrees C using a humidity-stabilized solid acid CsH2PO4 electrolyte.     

Energy and the u.s. Economy: a biophysical perspective

A series of hypotheses is presented about the relation of national energy use to national economic activity (both time series and cross-sectional) which offer a different perspective from standard economics for the assessment of historical and current economic events. The analysis incorporates nearly 100 years of time series data and 3 years of cross-sectional data on 87 sectors of the United States economy. Gross national product, labor productivity, and price levels are all correlated closely with various aspects of energy use, and these correlations are improved when corrections are made for energy quality. A large portion of the apparent increase in U.S. energy efficiency has been due to our ability to expand the relative use of high-quality fuels such as petroleum and electricity, and also to relative shifts in fuel use between sectors of the economy. The concept of energy return on investment is introduced as a major driving force in our economy, and data are provided which show a marked decline in energy return on investment for all our principal fuels in recent decades. Future economic growth will depend largely on the net energy yield of alternative fuel sources, and some standard economic models may need to be modified to account for the biophysical constraints on human economic activity.     

加强产学研合作 全力推进粮食丰产科技工程

农业院校和科研单位是科技创新成果之源。为推进其科技创新成果的转化,产学研结合的呼声越来越高。随着粮食丰产科技工程项目的实施,为加速新成果、新技术的推广应用,充分发挥课题研发成果的示范带动作用,课题积极探索产学研结合模式,取得了显著的实施效果,对进一步促进河北省粮食丰产科技创新体系建设、全面提升粮食综合生产能力起到了重要的科技支撑作用。     

推进现代农业科技入户的问题与举措

建设社会主义新农村,核心是发展农村生产力,而发展农村生产力的关键问题是依靠科技进步与创新引导和支撑农村经济社会的发展。这些年来,我国农业科技取得了一定的成绩,但是整体上不适应农村发展的需要。突出表现在农业科技创新能力不足、农业科技推广体系不健全、农业科技转化率不高等方面。为此,必须把加快农业科技进步摆在"三农"工作更加突出的位置。     

Ethanol can contribute to energy and environmental goals

To study the potential effects of increased biofuel use, we evaluated six representative analyses of fuel ethanol. Studies that reported negative net energy incorrectly ignored coproducts and used some obsolete data. All studies indicated that current corn ethanol technologies are much less petroleum-intensive than gasoline but have greenhouse gas emissions similar to those of gasoline. However, many important environmental effects of biofuel production are poorly understood. New metrics that measure specific resource inputs are developed, but further research into environmental metrics is needed. Nonetheless, it is already clear that large-scale use of ethanol for fuel will almost certainly require cellulosic technology.     

长白山阔叶红松林生态系统生产力与温度的关系

目的气候变暖背景下生态系统碳循环的温度敏感性研究是全球变化生态学的主要研究内容之一,森林生态系统生产力对温度的响应和适应机制是理解生态系统的温度敏感性的重要手段,长白山阔叶红松林作为典型的温带森林生态系统及重要的碳汇,研究其生产力对环境温度的响应,对提升中国森林植被碳循环模拟的准确性至关重要。方法本研究以长白山阔叶红松林为对象,收集长白山通量站2003—2011年共9年的观测数据,通过进行整合分析,量化了生态系统碳循环的3个关键过程:生态系统总初级生产力、净生态系统生产力和生态系统呼吸的温度响应曲线,并进一步分析环境因子对其最适温的影响。结果研究发现总初级生产力、净生态系统生产力的温度响应均表现为一条峰值曲线,并存在最适温,GPP的最适温(t_GPP)与NEP的最适温(t_NEP)存在显著线性正相关关系。在年际尺度上,一年中最高空气温度的改变是引起t_GPP和t_NEP变化的主要因素,而年均温和夏季温度对t_GPP和t_NEP的变化没有显著影响。当最高温度升高1 ℃时,t_GPP和t_NEP分别增加0.41和0.66 ℃。降水、光和有效辐射、饱和蒸汽压差等环境因子对t_GPP和t_NEP无显著影响,但夏季降水能够降低温度对t_GPP的影响。结论通过上述研究说明,生态系统的初级生产力及净生产力存在温度适应现象,当研究碳循环与气候变化相互作用的模型时需要充分考虑生态系统生产力的温度适应,从而更加准确地预测碳循环对气候变暖的响应和反馈。      

Coal conversion technologies: some health and environmental effects

Several technologies to convert coal to liquid and gaseous fuels are being developed in the United States, some with support from the Department of Energy. Substitution of these technologies for those currently being used will produce different health and environmental hazards. In this article, selected health and environmental effects of four coal conversion and four existing technologies are compared. For each technology, the emission estimates for complete fuel cycles, including all steps in fuel use from extraction to the end use of space and water heating by electricity or direct combustion, were prepared by means of the Brookhaven Energy System Network Simulator model. Quantitative occupational health and safety estimates are presented for the extraction, transportation, distribution, processing, and conversion activities associated with each technology; also included are some public health damage estimates arising from fuel transportation and air pollution impacts. Qualitative estimates of health damage due to polycyclic organic matter and reduced sulfur are discussed. In general, energy inefficiencies, environmental residuals, and hence implied environmental effects and health damage increase in the order: (i) direct combustion of natural gas and oil, (ii) direct combustion of synthetic gas and oil, (iii) central-station electric power produced from synthetic gas, (iv) central-station electric power produced from coal, and (v) central-station electric power produced by the combustion of synthetic liquid fuels. The compliance and conflict of these technologies with the amendments of the Clean Air Act and other legislation are discussed.     

农林生物质能转化利用技术论文的统计分析

基于维普《中文科技期刊数据库》,以2001～2007年为时间段,对有关农林生物质能转化利用技术的论文进行检索。检索论文包括生物质发电、生物质成型燃料、生物质热解、生物质气化、燃料乙醇和生物柴油等6方面。以检索的论文为研究对象,进行论文发表年度、主题分析。通过统计分析,可以了解当前国内生物质能在转化技术、开发利用方面的研究现状和发展趋势。     

营林造林技术在退耕还林中的应用和推广分析

本文以营林造林技术为研究对象,以其在退耕还林中的应用和推广前景为研究目标.主要包括:(1)对营林造林技术进行了简单概述;(2)重点从七个方面分析和探究了营林造林技术在退耕还林中的具体应用;(3)针对营林造林技术的推广提出了三点建议,希望能够为我国退耕还林工作以及生态林业建设的有效开展起到一定帮助.