Parameterization of the roughness length over the sea in forced and free convection

In the condition of free convection, the Charnock relation is inadequate. In this paper we extend the Charnock relation to include the effect of free convection on the roughness length. As a result, the singularity in the Monin–Obukhov similarity theory can be avoided. This paper shows two approaches to derive the roughness length formula in the forced and free convections. The first approach is based on the mixing length theory and the use of the observational data of the vertical velocity variance. We introduce a new vertical velocity scale based on the vertical velocity variance; this velocity variance is well behaved in the atmospheric boundary layer and easy to obtain from field experiments. The second approach is based on the theoretical framework of Sykes et al. (Q R Met Soc, 119: 409–421). From that framework, we develop a theory to obtain the roughness length formula. The results of these two approaches are in agreement with each other. In the past, a multiplication factor associated with free convection was considered to be a constant. This paper shows that this multiplication factor is, in fact, also dependent on the depth of the mixing height. In previous studies, experimental works were often conducted without taking into account the depth of the mixing height. Not taking into account the mixing height in the estimation of the roughness length in free convection would result in an inaccurate estimate of the roughness length and hence the drag coefficient. An erratum to this article can be found at     

Anthropogenic factors and their potential impacts on the sustainable development of Abu Dhabi's terrestrial biological resources

SUMMARY

Since the discovery of oil, the United Arab Emirates has undergone a process of rapid development, increasingly affecting the ecosystems of the country. Limited scientific literature dealing with these ecosystems is available, although a process of comprehensive ecological research has been initiated over the last few years. Further information on the soils, vegetation, fauna and climate are required in order to initiate a process of sustainable use of natural resources.

Abu Dhabi Emirate was surveyed for anthropogenic factors in its habitats using an off-road vehicle, a global positioning system (GPS) and satellite imagery. The emirate was divided into six geomorphological units. Livestock was found to be the most common anthropogenic factor and is believed to have caused degradation of the natural vegetation. Agriculture, silviculture and urbanization were common and caused habitat loss and fragmentation. Rubbish dumping, earth moving and car tracks were also widespread, whereas air pollution and fences were limited. Four of Abu Dhabi's geomorphological units were classified as low-impact zones, two as low- to medium-impact zones and one as a medium- to major-impact zone. Environmental Impact Assessments (EIA) and detailed ecological research were suggested as future mechanisms to implement sustainable development, and livestock control was suggested as a tool for habitat restoration.     

淮河水质变清的产业规模制约与规划漏洞补丁

为分析产业规模对淮河水质变清的制约作用,论证实现淮河水质变清目标的必要条件,考察规划方案的不充分性缺陷,首先计算了少数几个行业的部分产品在完全达标排放情形下的COD排污总量。根据1995年淮河流域四省少数几个行业的部分产品实际产量和当时执行的水污染物排放标准,计算得到的COD达标排污总量值(36.95万t)就已超过水质变清目标下的最大允许排放总量值(36.8万t),其中流域内造纸行业的COD达标排放总量就高达27.66万t,占实现淮河流域水质变清目标时所允许最大排放量36.8万t的75.2%。《淮河流域水污染防治规划及"九五"计划》未涉及行业或产品的规模控制、最大允许COD排污总量的行业或产品分配、目标可达性与方案充分性的论证等内容。规划方案与规划目标是相互脱节的,无法保障规划目标的实现。产业结构中排污负荷高的产品生产规模过大且没有得到严格有效的压缩控制是导致淮河流域水质变清目标未能实现的重要原因之一。要想实现淮河水质变清,严格控制全流域内排污负荷高的工业产品总产量规模是必要条件之一。     

Cognitive and affective identification: Exploring the links between different forms of social identification and personality with work attitudes and behavior

Individuals often identify with groups in order to either reduce perceived uncertainty or to feel better about who they are as individuals. This suggests that cognitive and affective identification are two distinctive forms of social identification in organizational settings. Because neurotic individuals are highly motivated to reduce perceived uncertainty, they will tend to identify cognitively with groups. Extraverted individuals, on the other hand, are highly motivated to enhance how they feel about themselves and thus identify affectively with groups. Across three studies, we develop measures of cognitive and affective identification and then show that neuroticism is positively related to cognitive identification, whereas extraversion is positively related to affective identification. We also find that affective identification provides incremental predictive validity over and above cognitive identification in the prediction of organizational commitment, organizational involvement, and organizational citizenship behaviors. Copyright © 2012 John Wiley & Sons, Ltd.     

SARS流行期的气候学尺度分析

对SARS疫区流行期的气候特征作了统计分析.发现它们共同的特征是月均温在5～22 ℃,降水偏少,约在90 mm以下,其中疫情爆发月均温13～17 ℃.在疫区,如果出现气温日较差较小、大气污染指数高的天气,大约8 d后出现疫情峰值.由于SARS第一次在人群中发现,并且缺乏病毒学研究,本项研究的结论是解释性的.     

北京地区湿式脱硫除尘系统管路结垢现象分析

分析了北京地区供热企业湿式脱硫除尘系统普遍存在的循环水管路结垢问题,指出体系中Ca^2 和SO^2-4的积累是造成结垢的根本原因,采用合适的烟气脱硫方法和工艺是解决脱硫设备结垢问题的根本所在;添加少量合适絮凝剂是减少循环水系统管路结垢的重要措施。     

多重密度布点对土壤有机质空间特性的解析

论文以张家港市耕层土壤有机质（Soil organic matter, SOM）为目标变量,通过网格布点建立11种样点密度梯度,运用经典统计学和地统计学方法研究其空间特性随布点密度变化的趋势规律。结果表明,各密度下SOM的变异系数稳定在21.70%~23.12%之间,表现出中等程度变异;随着布点密度降低,SOM的块基比和分维数分别由37.52%、1.838波动降至18.70%、1.714,Moran’s I则由0.485起伏升高至0.857,相应地其空间变异中结构变异组分增多、随机变异贡献减少,空间自相关性也逐渐增强;SOM呈现西南-东北递减分布,随着样点密度减小,其空间格局趋于简化。论文以布点密度为视窗,揭示了SOM的多重空间尺度特征,可为解析土壤属性的层级结构提供参考依据。     

江汉平原县域尺度土壤有机质空间变异特征与合理采样数研究

土壤有机质含量是衡量土壤肥力和评价耕地质量的重要指标。在县域尺度下,利用合理数量的样点反映其空间分异特征具有重要意义。论文选取位于江汉平原腹地的湖北省公安县为研究区,布设了4 045个样点并测定其有机质含量,采用半方差分析得到土壤有机质空间变异特征,基于Moran’s I揭示空间变异较大地区,并通过二分法的思想逼近最佳合理采样数值。结果表明：研究区土壤有机质分布呈中等空间相关性,有6个局部区域的空间变异明显高于邻近地区,采样点数量与插值精度呈正相关,合理采样数为598个。研究结果可以为江汉平原县域耕地质量监测和管控提供指导。     

城市家庭规模与结构对生活污水排放特征影响分析

以北京、上海、广州、兰州、昆明等5个城市30个中等收入城市家庭为研究对象,探讨了家庭规模、家庭结构对生活污水排放特征的影响.结果表明,城市家庭生活污水中各污染物排放量随家庭规模增大而增大,其中受家庭规模经济影响,COD、BOD的排放强度呈现出较为明显的边际递减规律,而TN、TP主要受家庭居民个体因素影响;综合考虑家庭规模、家庭结构的影响,首次提出家庭污染等效因子,把所考察的家庭转换成“等价(参照)家庭”,相对于参照家庭而言,所考察的家庭的污染排放状况与家庭污染等效因子成正比,由此反映不同家庭类型与生活污水排放之间的特定关系.     

An empirical investigation of returns to scale: The Welsh coal industry

This article attempts to study both returns to scale and optimal size of production. Specifically, the authors estimate a ray-homothetic production function which allows the returns to scale to vary with ouput size and input mix. The production model is estimated using data from the Welsh coal industry for the period 1961–1976. Findings showed that, first, the Welsh coal industry suffers from a level of production which is either too small or below its optimal level and, second, this discrepancy between actual and optimal production worsened over the period considered.