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301.
本文对混杂随机时滞微分方程的当前发展及最新的研究成果进行了概述.主要回顾了混杂随机微分方程解的存在唯一性定理、稳定性、鲁棒有界性以及离散时间反馈镇定性等部分对混杂随机微分方程的研究起到关键推动作用的成果.  相似文献   
302.
This study evaluated the efficacy of geospatial technology (GT) learning experiences in two geography curriculum courses to determine their effectiveness for developing preservice teacher confidence and preparing preservice teachers to incorporate GT in their teaching practices. Surveys were used to collect data from preservice teachers at three intervals over one semester. Results indicate preservice teachers' confidence and competencies to successfully integrate GT in their teaching increased over the duration of the study. The findings highlight the value of providing GT learning experiences in geography curriculum courses and contribute to the literature on preparing preservice teachers to incorporate GT in teaching geography.  相似文献   
303.
大气边界层物理学的研究进展和面临的科学问题   总被引:26,自引:3,他引:26  
回顾了大气边界层物理学的发展历史,总结了该领域国际上目前所取得的主要研究进展,提出国内外在未来大气边界层物理学研究方面可能面临的一些主要科学问题,还对未来大气边界层物理学的发展方向提出若干建议,同时也指出了大气边界层物理学研究在思想和方法上应该注意的一些相关问题。  相似文献   
304.
The aim of the submitted study was to illustrate the development of the number of local authorities in all current EU states in the long period between 1950 and 2011 comprehensively, and also by particular decades, thus demonstrating the originality and uniqueness of the topic analysed in this context. Thus, we obtain a more detailed picture of the development of the number of local authorities in EU countries, and we can monitor how local authorities within a specific country gradually developed. (The stabilisation of the number of local units and an increase or gradual or sudden drop in local units are shown, for example). A sudden drop in local units can be associated with significant administrative reforms and with the development of large units of the so-called municipalities. When it becomes necessary to merge local authorities, many countries look to other countries where extensive reforms took place in the past for inspiration. However, it must be borne in mind that in a general European context, we cannot apply a universal system of public administration reforms, and solutions in the form of these reforms inspired by other countries may not always be appropriate.  相似文献   
305.
306.
科学数据共享实践:以国家地球系统科学数据中心为例   总被引:2,自引:0,他引:2  
地球系统科学是一门综合性交叉学科,起源于全球变化研究,受益于遥感技术进步,现已进入大数据时代,人工智能技术成为解决地球系统科学前沿问题的新手段。科学数据共享是推动科学发展、提升数据价值的关键,经过长期的探索和实践,全球已形成完善的数据资源管理政策与机制、持续的数据共享服务体系、多元化的科学数据整合模式,并且新的理念不断推动数据共享创新发展,其中“可发现、可访问、可互操作和可重用”原则和数据出版备受推崇。我国颁布了国家层面的政策法规,着重推动国家级科学数据中心建设、科技项目数据资源汇交及数据出版。借鉴国外数据共享经验,结合国内实际发展情况,我国探索出具有中国特色的地球系统科学数据资源分类体系,在元数据、分布式互操作、大数据分析和共享服务等关键技术方面都取得了重大突破。本文以国家地球系统科学数据中心为例,系统梳理了国内地球系统科学领域的数据共享实践进展,详细介绍了国家在地球系统科学领域的数据共享实践及其成效。国家地球系统科学数据共享工作已探索形成成熟稳定的运行服务机制、研制出适用于多源分散地球系统科学数据的标准体系、 建成多学科多时空尺度的地球系统科学数据库群、自主研发海量异构数据共享网络技术体系与服务系统,促进了地球系统科学的科学发展,同时也推动了数据共享理念的传播与推广。然而,数据孤岛现象、共享服务系统标准化程度低、系统技术标准未对接国际规范等问题仍然较为突出,阻碍了地球系统科学数据开放与共享。未来,随着共享个性化需求被激活,定制化的“数据+知识”服务有望成为主流趋势,将给数据共享带来新的机遇和挑战。  相似文献   
307.
文章阐述了基础地理信息服务基本特征及趋势,并结合笔者在生产实际中积累的基础地理信息经验和总结的服务中存在的不足。在以后的地理信息生产管理工作中,提出了从提升服务能力、拓展服务领域、深化服务力度、注重服务细节等几方面来提高基础地理信息服务水平的见解。  相似文献   
308.
Many actions to reduce GHG emissions have wider impacts on health, the economy, and the environment, beyond their role in mitigating climate change. These ancillary impacts can be positive (co-benefits) or negative (conflicts). This article presents the first quantitative review of the wider impacts on health and the environment likely to arise from action to meet the UK's legally-binding carbon budgets. Impacts were assessed for climate measures directed at power generation, energy use in buildings, and industry, transport, and agriculture. The study considered a wide range of health and environmental impacts including air pollution, noise, the upstream impacts of fuel extraction, and the lifestyle benefits of active travel. It was not possible to quantify all impacts, but for those that were monetized the co-benefits of climate action (i.e. excluding climate benefits) significantly outweigh the negative impacts, with a net present value of more than £85 billion from 2008 to 2030. Substantial benefits arise from reduced congestion, pollution, noise, and road accidents as a result of avoided journeys. There is also a large health benefit as a result of increased exercise from walking and cycling instead of driving. Awareness of these benefits could strengthen the case for more ambitious climate mitigation action.

Policy relevance

This article demonstrates that actions to mitigate GHG emissions have significant wider benefits for health and the environment. Including these impacts in cost–benefit analysis would strengthen the case for the UK (and similar countries) to set ambitious emissions reduction targets. Understanding co-benefits and trade-offs will also improve coordination across policy areas and cut costs. In addition, co-benefits such as air quality improvements are often immediate and local, whereas climate benefits may occur on a longer timescale and mainly in a distant region, as well as being harder to demonstrate. Dissemination of the benefits, along with better anticipation of trade-offs, could therefore boost public support for climate action.  相似文献   

309.
Ecosystem-Based Management (EBM) has gained international popularity in recent years, but the lack of consensus on its definition has precluded the use of a universal implementation framework. The large number and variety of principles that make up EBM, and the diversity in perspectives among key management players, has impeded the practical application of EBM. Agreement on a list of the essential ingredients of EBM is vital to successful application. A frequency analysis of EBM principles was conducted to identify the Key Principles that currently define EBM, from a list of twenty-six principles extracted from a subset of the EBM theoretical/conceptual literature (covering a range of published sources across disciplines and application types). Fifteen Key Principles were identified (in descending frequency of appearance in the literature): Consider Ecosystem Connections, Appropriate Spatial & Temporal Scales, Adaptive Management, Use of Scientific Knowledge, Integrated Management, Stakeholder Involvement, Account for Dynamic Nature of Ecosystems, Ecological Integrity & Biodiversity, Sustainability, Recognise Coupled Social-Ecological Systems, Decisions reflect Societal Choice, Distinct Boundaries, Interdisciplinarity, Appropriate Monitoring, and Acknowledge Uncertainty. This paper also examines the development of EBM principles over time, leading to predictions on the directions EBM will take in the future. The frequency analysis methodology used here can be replicated to update the Key Principles of EBM in the future. Indeed, further research on potential emerging Key Principles such as ‘Consider Cumulative Impacts’, ‘Apply the Precautionary Approach’ and ‘Explicitly Acknowledge Trade Offs’ will help shape EBM and its successful application in the management of marine activities.  相似文献   
310.
基于3S技术的海岸带综合管理研究进展   总被引:3,自引:0,他引:3  
通过剖析海岸带管理的涵义,从综合和协调管理海岸带系统的角度,总结了海岸带管理的研究现状,重点阐述3S(即GIS,RS,GPS)等关键技术在海岸带管理中的应用,并对其应用前景进行了展望。  相似文献   
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