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1.
科学评估国土空间脆弱性与恢复力并解释其时空分布特征,能为国土空间开发与保护相关决策提供参考。采用综合指数法和有序加权平均(Ordered Weighted Averaging, OWA)法分别评价和模拟长江经济带市域国土空间脆弱性及国土空间恢复力,并对二者的组合情况进行综合分析。结果表明:(1)2008-2017年间长江经济带国土空间脆弱性指数有明显下降趋势,累计下降率为16.49%,脆弱性指数从西向东逐步下降;(2)长江经济带“生态优先型”“维持现状型”“开发优先型”政策情景下国土空间恢复力分别处于较高(占47.22%)、中等(占35.19%)、低恢复力(占99.07%)水平;(3)长江经济带国土空间以低脆弱性-中等恢复力、低脆弱性-较低恢复力为主导,占30.63%,国土空间整体脆弱性低,恢复力处于较低至中等水平。  相似文献   
2.
Introduction: While improved safety is a highly cited potential benefit of autonomous vehicles (AVs), at the same time a frequently cited concern is the new safety challenges that AVs introduce. The literature lacks a rigorous exploration of the safety perceptions of road users who will interact with AVs, including vulnerable road users. Addressing this gap is essential because the successful integration of AVs into transportation systems hinges on an understanding of how all road users will react to their presence. Methods: A stated preference survey of the Phoenix, Arizona, metropolitan statistical area (Phoenix MSA) was conducted in July 2018. A series of ordered probit models was estimated to analyze the survey responses and identify differences between various population groups with respect to the perceived safety of driving, cycling, and walking near AVs. Results: Greater exposure to and awareness of AVs are not uniformly associated with increases in perceived safety. Various attitudinal factors, level of AV automation, and other intrinsic and extrinsic factors are related to safety perceptions of driving, walking, and cycling near AVs. Socioeconomic and demographic characteristics, such as gender, age, income, employment, and automobile usage and ownership, have various relationships with perceived safety. Conclusions: Cycling near an AV was perceived as the least safe activity, followed by walking and then driving near an AV. Both similarities and differences were observed among the factors associated with the perceived safety of different travel alternatives. Practical Applications: Public perception will guide the development and adoption of AVs directly and indirectly. To help maintain control of public perception, transportation planners, decision makers, and other stakeholders should consider more deliberate and targeted messaging to address the concerns of different road users. In addition, more careful pilot testing and more direct attention to vulnerable road users may help avoid a backlash that could delay the rollout of this technology.  相似文献   
3.
The difficulty in achieving high removal efficiency for contaminants in textile wastewater over a wide range of pH impedes the progress of its treatment technique greatly. Herein, a facile and sustainable strategy was adopted for constructing magnetic ordered mesoporous polymers (M-OMPs) without the assistance of organic solvent and catalyst. The prepared M-OMPs were endowed with high special surface area and good superparamagnetism simultaneously, and exhibited high removal efficiency (>99%) for Methylene Blue (MB) within a short time (10 min) at a concentration of 50 mg/L. What's more, high removal efficiency was achieved over a wide range of pH 2-12 and the adsorption capacity for MB on M-OMPs was substantially retained even after 5 adsorption-desorption cycles, further demonstrating the application potential of M-OMPs in the decontamination of textile wastewater.  相似文献   
4.
Modeling perceived collision risk in port water navigation   总被引:1,自引:0,他引:1  
An increase in the likelihood of navigational collisions in port waters has put focus on the collision avoidance process in port traffic safety. The most widely used on-board collision-avoidance system is the automatic radar plotting aid which is a passive warning system that triggers an alert based on the pilot’s pre-defined indicators of distance and time proximities at the closest point of approaches in encounters with nearby vessels. To better help pilot in decision making in close quarter situations, collision risk should be considered as a continuous monotonic function of the proximities and risk perception should be considered probabilistically. This paper derives an ordered probit regression model to study perceived collision risks. To illustrate the procedure, the risks perceived by Singapore port pilots were obtained to calibrate the regression model. The results demonstrate that a framework based on the probabilistic risk assessment model can be used to give a better understanding of collision risk and to define a more appropriate level of evasive actions.  相似文献   
5.
Problem: Motorcycles constitute about 19% of all motorized vehicles in Singapore and are generally overrepresented in traffic accidents, accounting for 40% of total fatalities. Method: In this paper, an ordered probit model is used to examine factors that affect the injury severity of motorcycle accidents and the severity of damage to the vehicle for those crashes. Nine years of motorcycle accident data were obtained for Singapore through police reports. These data included categorical assessments of the severity of accidents based on three levels. Damage severity to the vehicle was also assessed and categorized into four levels. Categorical data of this type are best analyzed using ordered probit models because they require no assumptions regarding the ordinality of the dependent variable, which in this case is the severity score. Various models are examined to determine what factors are related to increased injury and damage severity of motorcycle accidents. Results: Factors found to lead to increases in the probability of severe injuries include the motorcyclist having non-Singaporean nationality, increased engine capacity, headlight not turned on during daytime, collisions with pedestrians and stationary objects, driving during early morning hours, having a pillion passenger, and when the motorcyclist is determined to be at fault for the accident. Factors leading to increased probability of vehicle damage include some similar factors but also show some differences, such as less damage associated with pedestrian collisions and with female drivers. In addition, it was also found that both injury severity and vehicle damage severity levels are decreasing over time.  相似文献   
6.
Phenolic compounds and their derivatives have been found in industrial wastewater, which pose threats to the natural environment. Ordered mesoporous carbon(OMC) has been identified as an ideal adsorbent possessing high specific surface area and large pore volume to alleviate these pollutants. A novel ordered mesoporous carbon was prepared using COK-19 template with the cubic Fm3 m structure for the first time. Ordered mesoporous silica COK-19 was synthesized and reported in 2015. Sucrose as the carbon precursor was impregnated into the mesopores of silica and converted to carbon through carbonization process using sulfuric acid as a catalyst. Ordered mesoporous carbon was obtained after the removal of silica framework using hydrofluoric acid. Boric acid was employed for the preparation of OMCs with tunable pore sizes in the range of 6.9–16.6 nm. Several characterization techniques such as nitrogen adsorption–desorption isotherms, transmission electron microscope(TEM), Fourier transform infrared spectroscopy, Boehm titration and elemental analysis were employed to characterize the OMCs. The pore size analysis and TEM images confirmed that OMC has replicated the mesostructure of the COK-19. Results obtained from adsorption kinetics and isotherms suggest that the Pseudo-second-order model and Langmuir isotherm well described the experimental data.  相似文献   
7.
Farmers in the Sahel have been acknowledged for reclaiming degraded lands and improving food security by ingeniously modifying traditional agroforestry, water, and soil management practices. Despite the advantages offered by this range of farming techniques, their adoption rate is influenced by several factors. Using multivariate probit models and a correlation coefficient, this article examines the factors influencing the adoption of five land management practices based on 220 household and 40 farm surveys in four adjacent rural communities in southern Burkina Faso. The model results indicate that household labor force, education of household head, land tenure security, livestock holding, and membership in farmers’ groups influence the adoption of zaï practice, composting, improved fallow, stone bunds, and live hedges. However, two of the surveyed factors ‐ number of farms and visit by agricultural extension staff during the 12 months prior to the survey ‐ were not significant. Furthermore, a significant correlation was found between different land management practices, e.g., the decision to practice zaï is significantly linked to that of live hedges and composting. Zaï practice and stone bunds are considered labor intensive, which explains their significant correlations with household labor force at the 1% and 5% levels of significance, respectively.  相似文献   
8.
Establishing marine protected areas (MPAs) helps to restore and sustain marine and fishery resources, but in the Philippines only 20% of total MPAs are achieving their management objectives. We conducted a case study of a small MPA in Northern Philippines to understand socio-economic status and livelihoods of the fishermen stakeholders, and examine their attitudes and perceptions on marine resource values and conservation. Using an ordered probit model, we also investigated factors affecting these perceptions. We found a lower fish income ratio in higher income quartiles, a small share of local non-fishery income, and an apparent lack of other livelihood opportunities within the rural economy. The majority of fishermen had positive perceptions of the non-market value of marine resources, agreed with the need for MPAs, and perceived positive potential income benefit from MPAs. Level of education and fishing income were consistent significant positive determinants of these perceptions. Policy implications suggest: involving likely-to-be-displaced reef fishers in the crafting of management plans; conducting intensive research on appropriate and feasible livelihood options, for example, marine culture technologies; and designing explicit strategies to increase the propensity of coastal households to invest in children's education as a strategy for long-term sustainability of resource management.  相似文献   
9.
This paper presents a GIS-based multi-criteria decision analysis approach for evaluating the suitability for landfill site selection in the Polog Region, Macedonia. The multi-criteria decision framework considers environmental and economic factors which are standardized by fuzzy membership functions and combined by integration of analytical hierarchy process (AHP) and ordered weighted average (OWA) techniques. The AHP is used for the elicitation of attribute weights while the OWA operator function is used to generate a wide range of decision alternatives for addressing uncertainty associated with interaction between multiple criteria. The usefulness of the approach is illustrated by different OWA scenarios that report landfill suitability on a scale between 0 and 1. The OWA scenarios are intended to quantify the level of risk taking (i.e., optimistic, pessimistic, and neutral) and to facilitate a better understanding of patterns that emerge from decision alternatives involved in the decision making process.  相似文献   
10.
生命线工程网络抗震可靠性分析方法的比较研究   总被引:2,自引:0,他引:2  
生命线工程网络抗震可靠性分析是进行生命线工程系统规划、设计、改造与优化的基础。因此 ,寻找一种高效的适应性强的系统可靠性分析方法对实际工程应用具有重要的意义。本文主要介绍两种高效的网络系统两终端连通可靠性分析方法———递推分解算法和有序二分决策图算法。首先 ,分别对两种算法的原理及实现过程进行了详细的论述和说明 ,并且用c语言编制了二分决策图算法的计算程序。然后 ,利用这两种方法及随机模拟算法对 2 0个以往研究中的经典算例和两个实际工程网络———河南省电力网和上海市浦西供水管网 ,进行了网络系统抗震连通可靠性分析。通过对实例分析结果的比较研究 ,得到了一些经验性的结论 ,以期为优化设计工程网络时选择系统可靠性的分析工具提供参考。研究表明 ,由于递推分解算法具有适应性强和能够求得问题近似解的优点 ,因此有良好的实际工程应用前景。  相似文献   
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