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51.
利用专业噪声测量设备及噪声频谱分析设备,对地铁站附属地下餐饮空间区域噪声进行监测,绘制噪声小时频谱。经分析发现地铁附属地下餐饮空间声环境会受到客流、空间位置及餐铺建筑结构影响,因此在该类空间进行降噪设计中应充分考虑这些因素的影响。  相似文献   
52.
针对时间因素对钻屑瓦斯解吸指标K1测定结果的影响,采用恒温瓦斯放散试验深入分析钻屑瓦斯解吸指标K1测定理论的准确性,总结因时间因素导致K1值测定误差所带来的现场问题。研究结果表明:K1值的测定误差与时间关系密切,测定启动时间越晚,误差越大;测定启动时间由第1 min延后至第2 min,绝对误差和相对误差最大值分别增加0.081 cm3/(g·min1/2)和2.20%;高瓦斯压力条件矿井或煤层的局部高瓦斯压力区域、构造煤发育区的钻屑瓦斯解吸指标K1值测定结果偏低,测定误差偏大。研究结果可为煤与瓦斯突出预测水平的提升提供技术支撑。  相似文献   
53.
Seventy-two squares of 100 ha were selected by stratified random sampling with probabilities proportional to size (pps) to survey landscape changes in the period 1996–2003. The area of the plots times the urbanization pressure was used as a size measure. The central question of this study is whether the sampling with probabilities proportional to size leads to gain in precision compared to equal probability sampling. On average 1.03 isolated buildings per 100 ha have been built, while 0.90 buildings per 100 ha have been removed, leading to a net change of 0.13 building per 100 ha. The area with unspoiled natural relief has been reduced by 2.3 ha per 100 ha, and the length of linear relicts by 137 m per 100 ha. On average 74 m of linear green elements have been planted per 100 ha, while 106 m have been removed, leading to a net change of −31 m per 100 ha. For the state variables ‘unspoiled natural relief', ‘ linear relicts', ‘removed linear green elements', and ‘new – removed linear green elements' there is a gain in precision due to the pps-sampling. For the remaining state variables there is no gain or even a loss of precision (`new buildings', ‘removed buildings', ‘new – removed buildings', ‘new linear green elements'). Therefore, if many state variables must be monitored or when interest is not only in the change but also in the current totals, we recommend to keep things simple, and to select plots with equal probability.  相似文献   
54.
Objective: This study investigated drivers' evaluation of a conventional autonomous emergency braking (AEB) system on high and reduced tire–road friction and compared these results to those of an AEB system adaptive to the reduced tire–road friction by earlier braking. Current automated systems such as the AEB do not adapt the vehicle control strategy to the road friction; for example, on snowy roads. Because winter precipitation is associated with a 19% increase in traffic crashes and a 13% increase in injuries compared to dry conditions, the potential of conventional AEB to prevent collisions could be significantly improved by including friction in the control algorithm. Whereas adaption is not legally required for a conventional AEB system, higher automated functions will have to adapt to the current tire–road friction because human drivers will not be required to monitor the driving environment at all times. For automated driving functions to be used, high levels of perceived safety and trust of occupants have to be reached with new systems. The application case of an AEB is used to investigate drivers' evaluation depending on the road condition in order to gain knowledge for the design of future driving functions.

Methods: In a driving simulator, the conventional, nonadaptive AEB was evaluated on dry roads with high friction (μ = 1) and on snowy roads with reduced friction (μ = 0.3). In addition, an AEB system adapted to road friction was designed for this study and compared with the conventional AEB on snowy roads with reduced friction. Ninety-six drivers (48 males, 48 females) assigned to 5 age groups (20–29, 30–39, 40–49, 50–59, and 60–75 years) drove with AEB in the simulator. The drivers observed and evaluated the AEB's braking actions in response to an imminent rear-end collision at an intersection.

Results: The results show that drivers' safety and trust in the conventional AEB were significantly lower on snowy roads, and the nonadaptive autonomous braking strategy was considered less appropriate on snowy roads compared to dry roads. As expected, the adaptive AEB braking strategy was considered more appropriate for snowy roads than the nonadaptive strategy. In conditions of reduced friction, drivers' subjective safety and trust were significantly improved when driving with the adaptive AEB compared to the conventional AEB. Women felt less safe than men when AEB was braking. Differences between age groups were not of statistical significance.

Conclusions: Drivers notice the adaptation of the autonomous braking strategy on snowy roads with reduced friction. On snowy roads, they feel safer and trust the adaptive system more than the nonadaptive automation.  相似文献   

55.
分析了2009年9月26日美国对中国轮胎进口实施的特别保护措施,运用国际贸易和国际经济学的相关理论,对美国轮胎特保法案进行了剖析。在目前中美轮胎贸易情况下,从宏观和微观的角度探讨了轮胎贸易顺差形成的原因,以及长期和短期内对中国经济的影响,并对中国轮胎出口贸易提出了几点政策建议。  相似文献   
56.
Although contingent valuation is the dominant technique for the valuation of public projects, especially in the environmental sector, the high costs of contingent valuation surveys prevent the use of this method for the assessment of relatively small projects. The reason for this cost problem is that typically only contingent valuation studies which are based on face-to-face interviews are accepted as leading to valid results. Particularly in countries with high wages, face-to-face surveys are extremely costly considering that for a valid contingent valuation study a minimum of 1000 completed face-to-face interviews is required. This paper tries a rehabilitation of mail surveys as low-budget substitutes for costly face-to-face surveys. Based on an empirical contingent valuation study in Northern Thailand, it is shown that the validity of mail surveys can be improved significantly if so-called Citizen Expert Groups are employed for a thorough survey design.  相似文献   
57.
介绍了“电改袋”除尘系统的工艺特征,分析了130t/h煤粉炉烟气除尘器系统改造为长袋低压脉冲袋式除尘器的技术方案。改造后,除尘器已经稳定运行1年多,各项技术指标均达到设计要求,环境效益与经济效益显著。  相似文献   
58.
In recent decades, many changes have occurred in the approach to financing and operating water services in developing countries. The demand‐responsive approach is now adopted in many countries in a context of donor‐supported decentralization processes, which gives more responsibility to end users. However, the government's responsibility at different levels is enforced by the international recognition of the human right to water. This paper examines specific actions that build the role of local government authorities in this scenario. A collaboration between an international NGO and a rural district in Tanzania from 2006 to 2009 is used as an action research case study that is representative of local capacity‐building needs in decentralized contexts and rural areas. Three main challenges were detected: i) lack of reliable information; ii) poor allocation of resources in terms of equity; and iii) lack of long‐term community management support from the district. Two mechanisms were established: i) water point mapping as a tool for information and planning; and ii) a District Water and Sanitation Unit Support (DWUS) for community management. The results show how the framework provided by the goal of human right to water helps to define useful strategies for equity‐oriented planning and post‐project support at the local level.  相似文献   
59.
环境健康价值评估中的年龄效应研究   总被引:1,自引:0,他引:1  
在环境健康价值评估研究中,统计寿命价值和年龄之间的关系是理论和实证研究焦点之一,也是重要的学术问题。长久以来,环境政策效益评估中是否应该赋予老年人较低的统计寿命价值一直存在广泛争议,且尚未得到一致性结论。通过设计选择实验,对北京市空气质量改善的健康效益进行了抽样调查,并采用MNL模型对北京市约500个居民的调查数据进行回归分析,估算了不同年龄人群对健康风险减少的支付意愿,针对中国人群中统计寿命价值和年龄之间的关系进行实证探讨。结果表明:一方面,在总体样本中设置年龄虚拟变量,回归结果表明年龄变量系数的符号均显著为负,即年龄因素对减少空气污染带来的死亡风险降低的支付意愿具有显著的影响,年龄越大支付意愿相对越小;另一方面,不同年龄人群分组样本结果显示,统计寿命价值与年龄之间呈现"倒U型"关系,统计寿命价值在中国存在"老年折扣"现象。研究结果可为我国环境政策的健康效益分析中如何考虑年龄的影响提供重要依据。  相似文献   
60.
为检验意愿价值评估法(Contingent Valuation Method,CVM)中争论的焦点问题——支付意愿的问卷"内容依赖性",本文以上海城市内河生态修复为评估对象,构建CVM的假想市场,设计评估顺序、评估对象尺度、嵌套物品等四重方案,通过720份问卷平行调查对同一评估对象在不同问卷中获得的支付意愿,并进行估计值比较和t检验。研究结果显示:支付意愿的数值随评估尺度的增加并不显著增加;单独评估比作为嵌套物品评估具有更高的支付意愿值;在问卷中先被评估的物品居民给出的支付意愿较高;整体物品的支付意愿小于各部分的加总。研究结果验证了国外实证研究文献报道的"范围不敏感"、"嵌入效应"、"顺序效应"、"部分—整体效应"等现象的存在。对此现象的解释主要是收入效应和替代效应。因此,在将CVM研究结果应用于公共政策中应充分考虑上述因素引起的偏差。  相似文献   
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