基于存活概率的动态车龄分布模型

城市车辆的年龄组成(简称车龄分布)是体现城市车辆老化程度和确定车辆报废年限的重要指标。目前已有的车龄分布算法要求数据量大,在我国大部分城市很难得到完整的数据。笔者提出一种符合威布尔分布的车辆存活概率算法。该算法根据车辆保有量数据和报废车辆总数(或新车数据)推导出各年的车龄分布,且能够动态预测将来年份的车龄分布。同时,利用北京市小客数据对算法进行了实例应用,证明该法的实用可行性。由于该算法所需数据量小,计算简便,特别适用于我国在用车统计不完备的地区,利用该算法根据有限的数据来推导出当地的车龄分布,具有通用性。该算法的有效性检验和敏感度分析需进一步研究。     

工厂安全性评价指标体系科学性的间接测定方法

工厂安全性评价指标体系是评价工厂安全性工作的测定标准，指标体系的科学性和合理性与工厂安全性评价工作密切相关。工厂安全性评价指标体系科学性的间接测定方法是，采用直接测定结果作为间接测定指标体系的样本，再利用各指标之间的相关量，求出间接测定结果，通过直接评价结果与间接评价结果的比较，检查直接评价结果的准确程度，以分析修正指标体系。     

A PROCEDURE FOR ASSESSING WATER RESOURCES FOR URBAN PLANNING1

A matrix has been developed to guide the assessment of urban water resources. The matrix provides a means for determining the relative importance of water-related problems, and for identifying the data needed to evaluate these problems for the purpose of urban planning. The matrix columns list nine categories of potential water-related urban problems. The rows list 51 categories of data inputs which may be needed to evaluate the potential problems. The inputs include standard types of basic hydrologic data, information based on analysis and interpretation of these data, and information on the interfacing factors of climate, land, and culture. A system is described for ranking the relative importance of the problem categories and data inputs on a numerical scale of 0 to 3. From this, an index is derived that evaluates the relative importance of each input item to an overall program for water resource assessment. From the completed matrix the hydrologist can determine the availability of data to meet the identified requirements. Judgement can then be made as to priorities on work elements to provide the planner with maximum information in minimum time. The matrix also provides a basis for the development of programs and their funding in order to overcome critical data deficiencies.     

路面预防性养护时机确定方法探讨

介绍了路面预防性养护时机的确定方法 :应用行驶质量指数或破坏指数、基于时间或路况、效益费用评估、生命周期费用分析、决策树或决策矩阵、评分排序方法进行路面预防性养护时机的确定 ;挖掘了目前路面预防性养护时机选取方法中存在的不足。根据路面破坏的复杂性以及目前路面预防性养护时机选取方法的不足 ,提出应对措施 ,路面预防性养护时机研究应该在一个多标准、基于路面性能的基础上进行 ;在路面结构性能良好的情况下 ,基于预防性养护的路面功能性能衰变是进行路面预防性养护时机研究的关键     

General concepts for measuring cumulative impacts on wetland ecosystems

Because environmental impacts accumulate over space and time, analysis is difficult, and we must incorporate the most recent scientifically defensible information and methods into the process. Methods designed to deal specifically with cumulative impacts include checklists of characteristics or processes, matrices of interactions (rated according to their level of importance) between disturbance activities and environmental conditions, nodal networks or pathways that depict probable effects of disturbances, and dynamic system models. These methods have been tested over the past decade and have proven generally successful.Landscape perspectives have emerged as especially helpful in analyzing cumulative effects, and have focused specific attention on questions of spatial and temporal scale, while leading to recognition of the complexity of ecosystem processes in general. An evaluation of several cases studies by the Commission on Life Sciences of the U.S. National Academy of Sciences emphasizes the importance of interactions and cumulative effects, but recognizes that current knowledge of the processes involved is insufficient to make specific recommendations for conceptual frameworks.The conceptual approach suggested by Preston and Bedford (1988) addresses many critical issues, such as the need to define dimensions of scale, and the importance of wetland size, shape, and location in the landscape. This approach and similar ones must be tested and evaluated so that a consensus may eventually emerge.A cumulative impact matrix is proposed that sets up additive, synergistic, and indirect categories, each capable of variation in space and time. Every interaction would be carefully examined to determine the likelihood of cumulative impact in any of the six categories. Because of its magnifying glass approach, such a matrix could be a very useful analytical tool, using existing methods to uncover all the information presently available about the behavior of the ecosystem of concern.     

基于历史资料的中国北方草原火灾风险评价

根据我国北方草原区各省、自治区1991—2005年的草原火灾资料，利用信息扩散理论和风险矩阵对我国北方草原区的草原火灾风险进行了计算，给出了我国北方各草原区的草原火灾年发生次数和草原火灾年受灾率在各个风险水平下的风险值，定量地评价了我国北方草原区的草原火灾风险。并给出几个重要风险水平下草原火灾风险的空间分布趋势和综合指标下的我国草原火灾风险空间分布趋势。     

Ethical Analysis of the Use of GM Fish: Emerging Issues for Aquaculture Development

Improvements in production methods over the last two decades have resulted in aquaculture becoming a significant contributor to food production in many countries. Increased efficiency and production levels are off-setting unsustainable capture fishing practices and contributing to food security, particularly in a number of developing countries. The challenge for the rapidly growing aquaculture industry is to develop and apply technologies that ensure sustainable production methods that will reduce environmental damage, increase productivity across the sector, and respect the diverse social and cultural dimensions of fish farming that are observed globally. The aquaculture industry currently faces a number of technology trajectories, which include the option to commercially produce genetically modified (GM) fish. The use of genetic modification in aquaculture has the potential to contribute to increased food security and is claimed to be the next logical step for the industry. However, the potential use of these technologies raises a number of important ethical questions. Using an ethical framework, the Ethical Matrix, this paper explores a number of the ethical issues potentially raised by the use of GM technologies in aquaculture. Several key issues have been identified. These include aspects of distributive justice for producers; use of a precautionary approach in the management of environmental risk and food safety; and impacts on the welfare and intrinsic value of the fish. There is a need to conduct a comparative analysis of the full economic cycle of the use of GM fish in aquaculture production for developing countries. There is also a need to initiate an informed dialogue between stakeholders and strenuous efforts should be made to ensure the participation of producers and their representatives from developing nations. An additional concern is that any national licensing of the first generation of GM fish, i.e., in the USA, may initiate and frame an assessment cycle, mediated by the WTO, which could dominate the conditions under which the technology will be applied and regulated globally. Therefore, an integrated analysis of the technology development trajectories, in terms of international policy, IPR, and operational implications, as well as an analysis of a broader range of ethical concerns, is needed.     

基于MATLAB的灰色预测系统及其对抽采瓦斯钻孔流量的数值模拟

研究钻孔瓦斯流量的变化及其变化趋势对抽采煤层瓦斯涌出量及钻孔瓦斯涌出初速度等参量的判定具有较大的实用价值。笔者将煤层抽采瓦斯钻孔看作一个灰色系统,利用灰色系统理论,以原始时间序列数据为基础,建立抽采瓦斯钻孔流量的模拟和预测GM(1,1)模型。针对数值模拟中大量的矩阵计算,利用MATLAB软件编制高效的计算机程序,实现了对抽采瓦斯钻孔流量的模拟和预测。为了检验模型模拟和预测结果的精度,选择了合理的误差检验模型。通过工程实例证明了GM(1,1)模型可信度较高,关联度较好,均方差比值为一级,拟合优度高。对瓦斯抽采设计和矿井安全生产具有一定的指导意义。     

Air Pollution Potential: Regional Study in Argentina

/ Air pollution potential is a measure of the atmospheric conditions that are unable to transport and dilute pollutants into the air, independently of the existence of sources. This potential can be determined from two atmospheric parameters: mixing height and transport wind. In this paper a statistical analysis of the mixing height and transport wind, in order to determine the areas with high or poor atmospheric ventilation in Argentina, is presented. In order to achieve this, meteorological data registered during 1979-1982 at eight meteorological stations were used. Daily values of the maximum mixing height were calculated from observations of daily temperatures at different heights and maximum surface temperature. At the same time as the maximum mixing height, the values of the transport wind were determined from the surface windspeed and the characteristics of the ground in the surroundings of each meteorological station. The mean seasonal values for both parameters were obtained. Isopleths of the mean seasonal of the maximum mixing heights were drawn. The percentage of seasonal frequencies of poor ventilation conditions were calculated and the frequency isopleths were also drawn to determine areas with minor and major relative frequencies. It was found that the northeastern and central-eastern regions of Argentina had a high air pollution potential during the whole year. Unfavorable atmospheric ventilation conditions were also found in the central-western side of the country during the cold seasons (37.5% in autumn and 56.9% in winter). The region with the greatest atmospheric ventilation is located south of 40 degrees S, where the frequency of poor ventilation varies between 8.0% in summer and 10.8% in winter.     

Seasonal variability in CDOM absorption and fluorescence properties in the Barataria Basin, Louisiana, USA

Absorption and fluorescence properties of chromophoric dissolved organic matter(CDOM) along a 124 km transect in the Barataria Basin,a large estuary located in Louisiana,USA,were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged from(3.25 ± 0.56) to(20.76 ± 2.43) m-1 for the three month high flow period whereas it varied from(1.48 ± 1.08) to(25.45 ± 7.03) m-1 for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runofl in the upper basin. An inverse relationship of CDOM absorbance and fluorescence with salinity observed in the basin could be a useful indicator of salinity. CDOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak,lowest the T-peak,and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM in the basin.