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山地人工林集材作业技术 总被引:19,自引:3,他引:19
以山地人工林集材作业为研究对象,应用技术经济分析方法,对人工林主要集材作业方式的经济效益、生态效益和社会效益进行分析。用综合评价法对集材作业方式综合效益进行评价,提出适合南方林区人工林考虑生态的集材作业技术。 相似文献
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The Environmental benefits and costs of conservation tillage 总被引:1,自引:0,他引:1
Every production practice, including conservation tillage, has positive or negative environmental consequences that may involve
air, land, water, and/or the health and ecological status of wildlife. The negative impacts associated with agricultural production,
and the use of conventional tillage systems in particular, include soil erosion, energy use, leaching and runoff of agricultural
chemicals, and carbon emissions. Several of these impacts are quantified. The conclusions suggest that the use of conservation
tillage does result in less of an adverse impact on the environment from agricultural production than does conventional tillage
by reducing surface water runoff and wind erosion. Additionally, wildlife habitat will be enhanced to some extent with the
adoption of conservation tillage and the benefits to be gained from carbon sequestration will depend on the soil remaining
undisturbed. Finally, further expansion of conservation tillage on highly erodible land will unquestionably result in an increase
in social benefits, but the expected gains will be modest. 相似文献
35.
利用灰色局势决策理论综合评价了金刚石钻头的技术经济效益。结合近几a的钻探生产实践和科研成果,经验证和对比,为豫西地区优选高效、长寿、综合效益好的钻头提供了参考。 相似文献
36.
警用视频监控的犯罪转移和效益扩散 总被引:1,自引:0,他引:1
基于加权转移系数法和双重差分法提出象限统计法,分析了警用治安视频监控对苏州市姑苏区2014—2016年警情数据的犯罪转移和效益扩散现象。研究结果表明,警用治安视频监控设备的安装对于总体犯罪、不同类型案件、不同时段案件均有效益扩散现象,且效益扩散现象比犯罪转移现象更加明显。在案件类型上,盗窃类案件及违反公共秩序类案件的犯罪转移现象较为明显,斗殴类案件次之,而诈骗类案件最不明显。盗窃电动车电瓶类案件的犯罪转移情况相对于盗窃电动车案件更为明显。在时间维度上,节假日和白天的犯罪转移现象更为明显,而工作日和夜晚的效益扩散现象更为明显。 相似文献
37.
Global assessment of the European Union fishing fleet: An update 总被引:1,自引:0,他引:1
This paper provides a global analysis of recent trends in the EU fishing fleet. Analysis of the capital productivity, labour rates, and economic benefits of the fleet revealed that considerable replacement of fishermen by better technology and well-equipped vessels occurred between 1990 and 2006. The analysis confirms that the Common Fisheries Policy (CFP) has been ineffective in reducing fishing capacity. In addition, the changes in capacity that occurred in this time interval differed among the different sectors of the fleet. Some members of the high sea fishing fleet increased their capacity (range 11–57%), and the deep-sea sector, which has greater tonnage and fishing power, increased its fishing capacity by 34–44%. These results confirm the ineffectiveness of the CFP in reducing overcapacity and illustrate the continuing threat of overcapacity to the long-term sustainability of fishery resources. 相似文献
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Land cover classification with multi-source data using evidential reasoning approach 总被引:1,自引:1,他引:0
Land cover classification is the core of converting satellite imagery to available geographic data.However,spectral signatures do not always provide enough information in classification decisions.Thus,the application of multi-source data becomes necessary.This paper presents an evidential reasoning (ER) approach to incorporate Landsat TM imagery,altitude and slope data.Results show that multi-source data contribute to the classification accuracy achieved by the ER method,whereas play a negative role to that... 相似文献
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