Application of optimal harvesting decision model to the analysis of Chinese forestry economic policy

This paper firstly extends the single period forest optimal harvesting decision model to infinite periods,in order to indicate how to determine the optimal rotation period aimed at maximizing forest revenue in all directions when repeat planting and harvesting trees on the same plot of earth till infinite future.The study also analyzes the influence of discounted rates,timber price,harvesting costs,planting costs,and tax on the determination of optimal rotation period;and how the optimal rotation period will change when we introduce the factors of continuously rising timber price and ecological revenue.Secondly,the authors introduce the intergenerational equity principle into the above model to design a resource-exploiting mode which satisfies bom the dynamic efficiency principle and the intergenerational equity principle.Last but not least,the research applies the above model to the analysis of Chinese forestry economic policy and explains the economic theory of institutions such as Government Purchasing Ecological Forest,Tree Compensation,and Forestry Subsidization,which provides a necessary theoretical foundation for future application of these new institutions.Besides,in regard to mis theoretical framework,the authors analyze the necessity of the Natural Forest Protection and Grain for Green projects which are currently being implemented in China.We also point out the emphasis of work to insure the project sustainable and successful.Finally,the research discusses the enterprise’s incentive to over-the-quota harvesting and the government’s means of restricting such behavior,which highlights the fact mat improved supervision and higher penalties are helpful in restricting over-the-quota harvesting.     

基于ISM和模糊故障树的铁路黄土隧道塌方风险分析

研究如何对铁路黄土隧道塌方风险事故进行管理控制,先从地质因素、施工方法因素、监控量测因素和施工管理因素分析了黄土隧道塌方事故的成因。接着依据铁路行业隧道风险评估指南矿山法隧道施工风险因素列表,识别影响兰渝铁路某黄土隧道项目塌方的18项主要风险因素。然后运用系统工程解释结构模型方法(ISM)分析项目各风险因素间的相互关系,得出影响该隧道项目塌方的直接原因为施工扰动过大、支护不及时、拱脚悬空时间过长和信息反馈处理不及时。底层原因则为开挖方式、特殊地质条件。在上述基础上建立项目塌方事件模糊故障树模型,进行模糊定量分析,得到项目塌方事件发生的模糊概率和关键风险因素的模糊重要度。结果表明,实例黄土隧道项目塌方事故风险概率很大,地质因素、开挖方法等对塌方事故影响最大。解释结构模型方法能揭示各风险要素间的不确定性因果关系,有利于把握事故发生机理,模糊数能客观地描述风险事件的发生概率,增强故障树诊断方法的可靠性。     

专家系统在垃圾焚烧炉故障诊断中的应用

基于垃圾焚烧炉的历史工况记录以及相应数据,将故障树分析法与基于规则的诊断专家系统相结合。实现对垃圾焚烧炉的在线早期故障诊断。并以实际数据验证了该专家系统对焚烧炉进行早期故障的在线诊断的正确率在90%左右,具有实用性。     

Mitigation needs adaptation: Tropical forestry and climate change

The relationship between tropical forests and global climate change has so far focused on mitigation, while much less emphasis has been placed on how management activities may help forest ecosystems adapt to this change. This paper discusses how tropical forestry practices can contribute to maintaining or enhancing the adaptive capacity of natural and planted forests to global climate change and considers challenges and opportunities for the integration of tropical forest management in broader climate change adaptation. In addition to the use of reduced impact logging to maintain ecosystem integrity, other approaches may be needed, such as fire prevention and management, as well as specific silvicultural options aimed at facilitating genetic adaptation. In the case of planted forests, the normally higher intensity of management (with respect to natural forest) offers additional opportunities for implementing adaptation measures, at both industrial and smallholder levels. Although the integration in forest management of measures aimed at enhancing adaptation to climate change may not involve substantial additional effort with respect to current practice, little action appears to have been taken to date. Tropical foresters and forest-dependent communities appear not to appreciate the risks posed by climate change and, for those who are aware of them, practical guidance on how to respond is largely non-existent. The extent to which forestry research and national policies will promote and adopt management practices in order to assist production forests adapt to climate change is currently uncertain. Mainstreaming adaptation into national development and planning programs may represent an initial step towards the incorporation of climate change considerations into tropical forestry.     

基于事件树的危险化学品污染事故应急技术库构建

近年来我国危险化学品环境污染事故频发,如何及时有效地对污染物进行应急控制及消除显得尤为重要。本文基于事件树分析法原理,根据危险化学品理化性质及其环境污染事故的特征,从污染物种类、污染介质和污染物性质三个方面归纳出危险化学品环境污染事故的42种事故情形,给出每种污染事故情形所对应的处理处置技术方案,构建危险化学品环境污染事故应急处理处置技术树。基于Web服务器Apache、PHP语言和MySQL数据库管理系统开发,建立了危险化学品环境污染事故应急处理处置技术库,实现对技术方案方便快速地查询。     

Agronomic application of olive mill wastewaters with phosphate rock in a semi-arid Mediterranean soil modifies the soil properties and decreases the extractable soil phosphorus

Olive mill wastewater (OMW), a by-product of the olive-mill industry, is produced in large amounts in Mediterranean countries. The presence of indigenous phosphate deposits in some countries like Tunisia provides an incentive for direct application or local chemical treatment at low cost to improve the solubility of low reactive phosphate rocks (PRs). The use of naturally occurring low-molecular weight organic acids (LMWOAs) that are present in OMW represents a new perspective in PR research and a possible solution for the recycling of the OMW. The present work was aimed at evaluating, under natural situations (field of olive trees), the effects of agronomic application of OMW (amounts applied: 30, 60 m(3) ha(-1)) with PR (amounts applied: 150 kg ha(-1)) on olive trees soil properties. We measured organic C, nitrogen (N), extractable phosphorus (P), exchangeable calcium (Ca), and exchangeable potassium (K), as well as other properties (pH and electrical conductivity). Our data provide evidence that agronomic application of OMW with PR has important effects on soil properties. Increases in organic C, total N, extractable P and exchangeable potassium (K) were found after the first agronomic application of OMW and PR. These increases were only temporary, following the second agronomic application of OMW and PR, significant reductions were detected in the extractable soil P (19.67 mg kg(-1) in the control soil vs. 8.99 mg kg(-1) in the amended soil). Changes in the extractable soil P could alter plant productivity and plant community structure because shifts in nutriment availability can affect the balance between limiting and non-limiting nutrients.     

Identifying Biotic Integrity and Water Chemistry Relations in Nonwadeable Rivers of Wisconsin: Toward the Development of Nutrient Criteria

We sampled 41 sites on 34 nonwadeable rivers that represent the types of rivers in Wisconsin, and the kinds and intensities of nutrient and other anthropogenic stressors upon each river type. Sites covered much of United States Environmental Protection Agency national nutrient ecoregions VII—Mostly Glaciated Dairy Region, and VIII—Nutrient Poor, Largely Glaciated upper Midwest. Fish, macroinvertebrates, and three categories of environmental variables including nutrients, other water chemistry, and watershed features were collected using standard protocols. We summarized fish assemblages by index of biotic integrity (IBI) and its 10 component measures, and macroinvertebrates by 2 organic pollution tolerance and 12 proportional richness measures. All biotic and environmental variables represented a wide range of conditions, with biotic measures ranging from poor to excellent status, despite nutrient concentrations being consistently higher than reference concentrations reported for the regions. Regression tree analyses of nutrients on a suite of biotic measures identified breakpoints in total phosphorus (~0.06 mg/l) and total nitrogen (~0.64 mg/l) concentrations at which biotic assemblages were consistently impaired. Redundancy analyses (RDA) were used to identify the most important variables within each of the three environmental variable categories, which were then used to determine the relative influence of each variable category on the biota. Nutrient measures, suspended chlorophyll a, water clarity, and watershed land cover type (forest or row-crop agriculture) were the most important variables and they explained significant amounts of variation within the macroinvertebrate (R ² = 60.6%) and fish (R ² = 43.6%) assemblages. The environmental variables selected in the macroinvertebrate model were correlated to such an extent that partial RDA analyses could not attribute variation explained to individual environmental categories, assigning 89% of the explained variation to interactions among the categories. In contrast, partial RDA attributed much of the explained variation to the nutrient (25%) and other water chemistry (38%) categories for the fish model. Our analyses suggest that it would be beneficial to develop criteria based upon a suite of biotic and nutrient variables simultaneously to deem waters as not meeting their designated uses.     

基于FTA法的潜射武器通道可靠性分析

应用故障树分析法,对潜射武器通道可靠性进行了分析,建立了该系统的故障树,并在此基础上计算了武器通道的可靠性参数.讨论了部件的概率重要度和关键重要度,结合所建的故障树给出了相应的结果.通过重要度分析,找到了提高系统可靠性的途径.     

基于故障树分析法的舰载武器装备电子元器件及PCB的失效研究

目的 对极端海洋环境下某型舰声呐装置中的多功能信号发生器进行失效研究。方法 使用故障树分析法作为失效分析基本方法。首先通过微焦点CT检测技术对样品进行准确的失效定位,并通过扫描电子显微镜和能谱分析样品的失效机理。然后结合应用背景,分析归纳样品失效的机理因子和影响因素。最后,针对每种失效形式提出具体的改善方案。结果 由电阻本身表面形貌、额定温度及外部环境（高温、高湿、高盐）等原因,导致含有盐雾的水汽进入电阻内部,致使电阻内部出现电化学迁移现象,电阻阻值因此明显降低,最终导致多功能信号发生器出现失效。结论 舰艇中的电子设备,如多功能信号发生器的失效往往是由设计制造及各种海洋环境因素综合作用所造成的。这就要求舰载电子设备的研制方、使用方都应重视海洋环境适应性问题,并采取一定的改善措施。     

基于决策树的矿井通风阻变型故障诊断及传感器优化布置

为实现矿井通风阻变型故障智能诊断,解决风速传感器优化布置与诊断模型不匹配的问题,提出基于决策树的矿井通风故障位置分类判断、故障量回归预测及嵌入式风速传感器优化布置一体化方法;以唐安矿为例对上述方法进行验证.结果表明:矿井通风空间数据集无量纲化能提高故障诊断准确率、提升模型收敛速度,剪枝能提高模型泛化能力;以基尼系数为嵌...