Three-Dimensional Modelling of Concentration Fluctuations in Complicated Geometry

The strong fluctuating component in the measured concentration time series of a dispersing gaseous pollutant in the atmospheric boundary layer, and the hazard level associated to short-term concentration levels, demonstrate the necessity of calculating the magnitude of turbulent fluctuations of concentration using computational simulation models. Moreover the computation of concentration fluctuations in cases of dispersion in realistic situations, such as built-up areas or street canyons, is of special practical interest for hazard assessment purposes. In this paper, the formulation and evaluation of a model for concentration fluctuations, based on a transport equation, are presented. The model is applicable in cases of complex geometry. It is included in the framework of a computational code, developed for simulating the dispersion of buoyant pollutants over complex geometries. The experimental data used for the model evaluation concerned the dispersion of a passive gas in a street canyon between 4 identical rectangular buildings performed in a wind tunnel. The experimental concentration fluctuations data have been derived from measured high frequency concentrations. The concentration fluctuations model is evaluated by comparing the model's predictions with the observations in the form of scatter plots, quantile-quantile plots, contour plots and statistical indices as the fractional bias, the geometrical mean variance and the factor-of-two percentage. From the above comparisons it is concluded that the overall model performance in the present complex geometry case is satisfactory. The discrepancies between model predictions and observations are attributed to inaccuracies in prescribing the actual wind tunnel boundary conditions to the computational code.     

近十年生态工程在中国的进展

我国生态工程近 1 0多年有进一步发展 ,研究和应用对象扩展为社会 -经济 -自然复合生态系统 ,目标明确为可持续发展 ,从追求一维的经济增长或环境与自然保护 ,走向富裕、健康、文明三维一体的复合生态繁荣。在充实“整体、协调、循环、自生”的生态工程原理和生态控制论的基础上 ,总结出生态工程设计的 8项原则。方法论发展为从物理过程的量化走向生态过程的序化 ,从工程结构的优化走向生态格局的进化 ,从机器的人工智能走向人的生态智能。技术路线发展了硬件、软件、心件耦合 ;多学科、多技术的系统组合 ;调控复合生态系统全生态过程 ;寓环境保护于生产和消费中 ,寓废弃物处理于利用中 ;结构和功能纵横耦合成食物链网式、生命周期式、生态系统式等网络结构     

太湖地区“禁磷”措施的效果及在富营养化控制中的作用

通过太湖地区采取“禁磷”措施前后城市生活污水、主要入湖河水和湖体水域中磷浓度与富营养化指数变化的分析 ,证实“禁磷”措施对降低居民生活污水中磷浓度的作用较为明显 ,降幅为 2 4 %左右 ,但对入湖河道和湖体水域中磷浓度与水体富营养化的影响则不明显。表明太湖富营养化的改善 ,除了实施“禁磷”措施外 ,尚需结合流域内其它污染治理措施 ,进行综合治理 ,才能取得较好的效果。     

Are we planning for sustainable disaster recovery? Evaluating recovery plans after the Wenchuan earthquake

This article examines local recovery plans that were created in response to the Wenchuan earthquake and then suggests ways that planners can better apply the concept of sustainability to the recovery process. We utilize a plan evaluation protocol to analyze 16 recovery plans in counties and towns that were severely affected by the earthquake. We also conducted semi-structured interviews with public officials and planners, with the qualitative data gleaned from these interviews being used to supplement the plan quality assessment. The results reveal that local recovery plans do not appear to have incorporated sufficiently the concepts of sustainability. We conclude the paper with the following recommendations: emphasizing sustainability as a policy priority during vision and goal development; developing solid databases and planning techniques; designing a diversified set of regulatory- and incentive-based policy tools suitable for local governments; enhancing social and institutional learning; and further integrating multi-level and interagency governmental units.     

Determinants of workers’ attitude toward low-carbon technology adoption: empirical evidence from Chinese firms

As the main contribution of China’s carbon emissions, low-carbon production in industrial firms becomes an inevitable choice, and industrial firm employees’ attitudes on low-carbon new technology directly influence the results of low-carbon production. Based on the Unified Theory of Acceptance and Use of Technology model, structural equation modeling was used to analyze the main factors influencing firm staff to accept low-carbon new technology. The study reveals that the employee’s social impact, performance expectation, effort expectations and convenient conditions, and employee characteristics are all main factors affecting their acceptance attitudes on low-carbon new technology. And social influence has the largest effect on employees’ acceptance attitudes toward low-carbon new technology. Accordingly, relevant policy recommendations are put forward for the future research direction.     

Techno-economic and environmental analysis of an integrated standalone hybrid solar hydrogen system to supply CCHP loads of a greenhouse in Iran

The techno-economic and environmental performance of hybrid solar hydrogen energy systems was investigated to provide combined cooling, heating and power (CCHP) demands of a standalone greenhouse in Iran to achieve sustainable agriculture based on an optimization procedure. From the environmental point of view, by deploying hybrid energy systems, 83%, to 100% of emissions can be avoided. Also a sensitivity analysis was performed on the hybrid energy systems in order to study the effect of major parameter variation on the systems justification. It was concluded that hybrid solar systems are economically competitive with conventional systems, for high solar intensity locations with high diesel fuel prices and decreased prices for PV and hydrogen storage technology.     

Co-composting of livestock manure with rice straw: Characterization and establishment of maturity evaluation system

Composting is considered to be a primary treatment method for livestock manure and rice straw, and high degree of maturity is a prerequisite for safe land application of the composting products. In this study pilot-scale experiments were carried out to characterize the co-composting process of livestock manure with rice straw, as well as to establish a maturity evaluation index system for the composts obtained. Two pilot composting piles with different feedstocks were conducted for 3 months: (1) swine manure and rice straw (SM–RS); and (2) dairy manure and rice straw (DM–RS). During the composting process, parameters including temperature, moisture, pH, total organic carbon (TOC), organic matter (OM), different forms of nitrogen (total, ammonia and nitrate), and humification index (humic acid and fulvic acid) were monitored in addition to germination index (GI), plant growth index (PGI) and Solvita maturity index. OM loss followed the first-order kinetic model in both piles, and a slightly faster OM mineralization was achieved in the SM–RS pile. Also, the SM–RS pile exhibited slightly better performance than the DM–RS according to the evolutions of temperature, OM degradation, GI and PGI. The C/N ratio, GI and PGI could be included in the maturity evaluation index system in which GI > 120% and PGI > 1.00 signal mature co-composts.     

Chemical oxidation of sulfadiazine by the Fenton process: Kinetics,pathways, toxicity evaluation

This paper investigated sulfadiazine oxidation by the Fenton process under various reaction conditions. The reaction conditions tested in the experiments included the initial pH value of reaction solutions, and the dosages of ferrous ions and hydrogen peroxide. Under the reaction conditions with pH 3, 0.25 mM of ferrous ion and 2 mM of hydrogen peroxide, a removal efficiency of nearly 100% was achieved for sulfadiazine. A series of intermediate products including 4-OH-sulfadiazine/or 5-OH-sulfadiazine, 2-aminopyrimidine, sulfanilamide, formic acid, and oxalic acid were identified. Based on these products, the possible oxidation pathway of sulfadiazine by Fenton's reagent was proposed. The toxicity evaluation of reaction solutions showed increased antimicrobial effects following the Fenton oxidation process. The results from this study suggest that the Fenton oxidation process could remove sulfadiazine, but also increase solution toxicity due to the presence of more toxic products.     

基于层次分析法的古村落旅游资源评价——以世界遗产地西递、宏村为例

以世界遗产地皖南古村落——西递、宏村为研究区域,从研究区域的资源价值和区位条件两个方面,选取了5个Ⅰ级指标：历史文化价值、科学价值、艺术价值、区域规模、交通便利程度,12个Ⅱ级指标：年代久远程度、民俗代表性、历史事件名人影响度、科学考察、科普教育、完整性、典型性、观赏性、地域组合、环境容量、通达性与服务中心距离,建立评价指标体系,并结合YAAHP软件对该指标体系进行层次分析,得出了各指标的相对权重。结果表明,西递、宏村的历史文化价值与艺术价值在其旅游资源评价中具有重要地位。在此基础上对其进行了分析并提出了相应的保护措施和对策,以期达到对西递、宏村旅游资源合理保护与开发的目的。     

知识管理导向的煤炭城市技术创新路径创造

技术创新是煤炭城市协调发展的重要支撑和根本保证,现有的煤炭城市技术创新存在着历史遗留及因其特性产生的固有障碍因素。知识管理是通过对知识资源的有效管理和利用,创造新价值和增强竞争优势的持续管理创新活动,它是破解煤炭城市技术创新路径闭锁的有力工具。