共查询到20条相似文献，搜索用时 31 毫秒
1.
Hasselmann K Latif M Hooss G Azar C Edenhofer O Jaeger CC Johannessen OM Kemfert C Welp M Wokaun A 《Science (New York, N.Y.)》2003,302(5652):1923-1925
Climate policy needs to address the multidecadal to centennial time scale of climate change. Although the realization of short-term targets is an important first step, to be effective climate policies need to be conceived as long-term programs that will achieve a gradual transition to an essentially emission-free economy on the time scale of a century. This requires a considerably broader spectrum of policy measures than the primarily market-based instruments invoked for shorter term mitigation policies. A successful climate policy must consist of a dual approach focusing on both short-term targets and long-term goals. 相似文献
2.
河南省新型农村社区发展模式及实践特点 总被引：3，自引：0，他引：3
新型农村社区建设是中原经济区建设中的创新之举,创建符合河南省省情、各地市情的新型农村社区发展模式,不仅是推进工业化、城镇化和农业现代化"三化"协调发展的必然要求,更是解决我省农村社会发展问题的现实需要。从河南省新型农村社区的发展现状出发,以产业、地理区位、主体、改造方式等角度对当前河南省新型农村社区发展模式进行分析,并总结出政策先行、因地制宜、社会参与、目标明确、分步推进等实践特点,以期为河南省社会主义新农村建设提供重要参考,为解决河南省城乡二元体制、推进城乡一体化进程提供重要依据。 相似文献
3.
牛银栓 《河南科技大学学报(农学版)》1999,(2)
学生中非正式群体的存在是一个不争的事实，其成因是多样的、而根据我校情况，主要分为地域型和趣味型。对他的政策应该是做好其中心人物的工作，对该类人物尽量吸收到正式组织的负责岗位上，对该类组织中的犯错误者。要平等对待，给予同情、热情帮助。这是做好学生工作乃至学校管理工作的重要一环。 相似文献
4.
Sander Janssen Ioannis N. AthanasiadisIrina Bezlepkina Rob KnapenHongtao Li Ignacio Pérez DomínguezAndrea Emilio Rizzoli Martin K. van Ittersum 《Computers and Electronics in Agriculture》2011,76(2):148-160
The ex-ante assessment of the likely impacts of policy changes and technological innovations on agriculture can provide insight into policy effects on land use and other resources and inform discussion on the desirability of such changes. Integrated assessment and modeling (IAM) is an approach that can be used for ex-ante assessment. It may combine several quantitative models representing different processes and scales into a framework for integrated assessment to allow for multi scale analysis of environmental, economic and social issues. IAM is a challenging task as models from different disciplines have a different representation of data, space and time. The aim of this paper is to describe our strategy to conceptually, semantically and technically integrate a chain of models from different domains to assess land use changes. The models that were linked are based on different modeling techniques (e.g. optimization, simulation, estimation) and operate on different time and spatial scales. The conceptual integration to ensure consistent linkage of simulated processes and scales required modelers representing the different models to clarify the data exchanged and interlinking of modeling methodologies across scales. For semantic integration, ontologies provided a way to rigorously define conceptualizations that can be easily shared between various disciplines. Finally, for technical integration, OpenMI was used and supplemented with the information from ontologies. In our case, explicitly tackling the challenge of semantic, conceptual and technical integration of models forced researchers to clarify the assumptions of their model interfaces, which helped to document the model linkage and to efficiently run models together. The linked models can now easily be used for integrated assessments of policy changes, technological innovations and societal and biophysical changes. 相似文献
5.
No problem of resource or environmental management can be rationally addressed until its true space and time dimensions are known. The limitations of the universal soil loss equation and the wind erosion equation are such that we do not seem to have a truly informed idea of how much soil erosion is occurring in this country, let alone of the processes of sediment movement and deposition. The uncritical use of models is unacceptable as science and unacceptable as a basis for national policy. A comprehensive national system of monitoring soil erosion and consequent downstream sediment movement and/or blowing dust is critical. The costs would be significant; nevertheless, they would reflect efforts better focused on achieving better management of the United States' land and water resources. 相似文献
6.
Paul B. Thompson 《Agriculture and Human Values》1986,3(4):32-42
An analysis of social goals for agriculture presupposes an account of systematic interactions among economic, political, and ecological forces that influence the performance of agriculture in a given society. This account must identify functional performance criteria that lend themselves to interpretation as normative or ethical goals. Individuals who act within the system pursue personal goals. Although individual acts and decisions help satisfy functional performance criteria, individuals may never conceptualize or understand these criteria, and, hence, social goals for agriculture may not be intentionally sought or desired by any human being. The statement of social goals is not, therefore, reducible to statements about individual desires and preferences, and the validity of social goals does not depend upon deriving a social welfare function, nor upon measuring interpersonal utility. The paper examines a series of strategies for defining social goals for agriculture, beginning with the statement of goals offered by William Aiken in 1983. Aiken's view stresses individually based constraints upon action, but social goals cannot be adequately defined on this view. Successively more adequate approaches to the problem of social goals are examined with respect to production and efficiency, Jeffersonian democracy, and ecosystem goals of community and self-reliance. The role of family farms, and the change in farm structure is evaluated in light of this analysis for social goals. 相似文献
7.
Cornelia Butler Flora 《Agriculture and Human Values》1988,5(1-2):24-34
A farming systems approach to development has meant many things over the past 15 years, depending on its institutional and ecological setting, its target populations, and the goals motivating its implementation. Despite the diversity of approaches, and the sometimes rancorous discussion over which was best and why, the approach is now recognized in many places as the only one that can identify and respond to the needs of limited resource farm families, especially those in marginal ecosystems. Involving an iterative process of diagnosis, design, testing and extension, the farming system approach to date has done more to change research objectives at national and international institutions than to change actual farmer practices. By legitimizing what limited resource farmers do and why they do it, a farming systems approach lends itself to policy analysis as well. Recent research in farming systems suggests greater attention should be payed to exogenous variables, including policy and infrastructure, as well as to development of technology that really responds to the felt needs of limited resource farmers in improving their level of living. 相似文献
8.
Holden C 《Science (New York, N.Y.)》2000,290(5496):1474-1475
The U.S. Department of Agriculture requested comments earlier this year to help it decide whether to adopt a formal definition of "distress" as part of its responsibilities under the Animal Welfare Act. But the 2600 pieces of advice it received during a 4-month period that ended earlier this month suggest that its job won't be easy. The comments highlight a deep split between animal activists, who see the potential new regulations as a step toward eliminating all painful procedures, and most researchers, who say that the present system is working well and that no major changes are needed. 相似文献
9.
胡佃有 《北京林业大学学报》1988,10(4):74-79
用逐级优化的数学规划序列模型解决林场合理经营中林种、树种与龄级三级结构的优化问题。把系统分成林种、树种及龄级结构三个层次,不同层次用不同目标的线性规划模型进行优化,组成序列方法。把众多的变量逐级予以分散,把不确定的因素逐级予以确认,最终获得彻底优化的系统结构。序列模型各级的解都是建立在优化的基础之上的,各级模型之间又有联系又相互独立。决策者可在各级模型的输入端输入所需的信息,调整方案,进行再分析,有利于系统工作者与决策者之间的联系。 相似文献
10.
新型职业农民培育是实现乡村振兴战略的重要支撑。2012—2020年间新型职业农民培育研究主要集中在概念界定、内涵与特征、培育模式、面临的问题、绩效评价、未来工作优化建议六个方面。当前研究对新型职业农民培训关注较多，对培育制度关注不够；所构建的绩效考核模型较多，对如何实现培育工作绩效治理关注不够；实证研究也多从个体性视角展开，缺乏整体性分析。建议进一步加大研究力度，并重点关注培育体系中的"政策扶持"环节，以加快我国新型职业农民培育进程。 相似文献
11.
Gideonse HD 《Science (New York, N.Y.)》1970,170(3962):1054-1059
A policy framework for analyzing educational research and development has been proposed. The framework consists of five primary elements focusing on the contexts in which educational R & D operates, its goals, its characteristics, its manpower, and its decision structures. These five primary elements interact to produce two secondary elements concerned with priorities and objectives, and strategies and tactics. The framework was applied to three current policy proposals in educational R & D including directed R & D programming in the U.S. Office of Education, the request for funds for experimental schools, and the proposed National Institute of Education. Rigorous application of the framework to major policy questions such as these three can help us examine issues before they arise. It can help prevent errors. Its application can provide greater assurance that primary, secondary, and tertiary consequences-those that arise from the interaction of the consequences we most directly perceive-will receive examination. This kind of consideration can help produce the desirable and intended effects and avoid the detrimental consequences of unanticipated impacts in unintended areas. 相似文献
12.
中文：本文从种植农户的视角分析了我国种植业保险的实施效果,探讨连续几年农户对种植业保险的认知变化、评价变化和并对变化背后的原因进行深入分析。通过对内蒙古自治区7个盟市农户的问卷调查以及有关单位的部门访谈,得出以下结论：第一,农户对种植业保险政策认知度呈上升趋势,但了解深度不够；第二,随着农户对农业保险政策认知度的逐步提高,其对农业保险总体评价反而呈下降趋势；第三,农户对种植业保险不满意的原因主要是保险的保障水平低,农户遭受自然灾害后获得的赔偿对弥补灾害的作用不大,农业保险产品覆盖面窄,不能满足农户的需求。 相似文献
13.
14.
A general planner for agro-ecosystem models 总被引：1，自引：0，他引：1
In agro-ecosystem simulation models involving a farm, management is usually controlled through some combination of calendar- and logic-based rules. This approach has been quite successful but despite their apparent naturalness and simplicity, rules do present some difficulties in use and implementation. Even relatively simple rule sets can become quite large and difficult to follow, and they are based on the current state of the system rather than anticipating the likely future state of the system. Systems based on alternative approaches may have the capability to improve on the performance of rule-based systems and here we describe the implementation of such an alternative, called the general planner for agro-ecosystem models (GPAM), and discuss how the GPAM makes decisions in the presence of complex interactions.The GPAM works by constructing a decision tree of all possible decisions up to some defined point in the future, assessing which pathway through the decision tree leads to the best outcome, and then passing set of decisions defining that pathway to the simulation model to implement. To test its capabilities, the GPAM was instructed to control a grazing rotation in a very simple agro-ecosystem model. Tests were conducted to examine the reaction of the GPAM's performance to a range of parameters, including how far forward in time it looked when optimising the rotation length, how often it revised the rotation length plan, and how often it was allowed to change the rotation length. In all of these tests the GPAM reacted as expected and, without being provided with any prior knowledge, decided to implement the long winter rotation lengths normally used by farm managers in year-round grazing systems to make best use of limited pasture. The highest levels of animal production were obtained when the GPAM was able to make swift changes in the rotation length, when it looked further into the future when optimising the rotation length, and when it re-planned often.Initial testing indicated that the GPAM showed promise as a new way of emulating the manager in simulation models. More work is needed to assess the performance and potential of the GPAM when it is provided with imperfect or biased information on the likely future states and to allow the GPAM to manage multi-objective systems, such as when balancing production and environmental goals. 相似文献
15.
16.
应用状态空间法研究系统的控制,不仅有利于把系统划分为若干组分或子系统对各种因子分别进行动态描述,同时更好地解决多输入和多输出的研究技术,因而有可能成为种群生命系统控制研究的重要手段。本文拟通过网络模型着重讨论适应于昆虫种群研究的状态空间方程的建立问题。 相似文献
17.
本文基于对1950—2018年中国农村宅基地管理政策文本的量化分析,结合政策文本的参照网络关系和政策工具分布特征,从政策扩散强度、广度、速度和方向4个维度探讨了农村宅基地管理政策的扩散过程和特征,以及不同扩散模式下的政策效应。结果表明:中国农村宅基地管理政策中的法律类政策和专门性政策的扩散强度较大,在年度分布中具有显著的集聚特征;法律类政策的扩散广度和扩散速度均大于专门性政策;借助规划管理和申请审批两种行政型政策工具的时序分布特征可以看出,两种政策工具在中央政府-省级政府间呈现出自上而下和先自上而下后自下而上的扩散,其扩散路径分别表现为S型扩散曲线和S+R型扩散曲线,在农村宅基地管理政策扩散过程中产生了有利于政策目标实现的递增效应和激励效应。 相似文献
18.
贵州杉木人工林生长收获模型系统的研究 总被引：1，自引：0，他引：1
丁贵杰 《东北林业大学学报》1997,25(5):43-49
为建立经营模型系统和提高森林培育的定量化管理水平用多年积累的各类试验林、固定样地等资料．在立地盾量评价基础上．利用优势高(Ho)受密度和人为干扰小的特点．把以作为独立变量引入有关模型．采用计算机模拟方法。建立了自然状态下直径和断面积生长预测模型、直径分布和树高曲线模型、疏伐木和疏伐后林分平均高、平均胸径预测模型、疏伐后林分平均胸径生长预测模型、优化密度等模型．形成了以立地质量评价为起点的生长收获模型系统．解决了密度控制、林分结构和生长收获的动态预测、疏伐效益分析．疏伐带来的非生长性增长等问题．模型系统经验验．可在相应研究区域内应用。 相似文献
19.