岷江上游典型河段水电梯级开发水环境累积影响

岷江上游水能资源丰富,近几十年水电开发程度较大,选取两河口—都江堰段为典型河段,针对该河段10级水电开发的情况,运用幕景分析法进行水环境累积影响评价。研究表明:岷江上游干流两河口—都江堰典型河段水电梯级开发对水环境已经产生了一定的累积影响;在径流量的变化上表现为水量逐年下降,且趋势明显;水量年内分配经水电梯级调节明显发生改变;水质累积影响变化不大,但随着水电规划梯级的建成,有明显恶化的趋势;水温上累积影响较大,可能会对下游鱼类生长、繁殖,浮游植物、动物的生长及分布等产生一定的影响,但对农业灌溉不会产生较大不利影响。     

南方山地丘陵区规模畜禽养殖对水环境影响及评价

选择南方山地丘陵区典型规模畜禽养殖集中地为研究区域,通过对该研究区域周边地表水及地下水的调查采样,分析主要污染物时空变异及污染物形态之间的变化,并对周边水环境进行初步评价。结果表明:规模化畜禽养殖区域的浅层地下水和地表水已经受到严重污染;养殖场的环保处理设施与养殖规模不配套造成大量污染物进入地表水环境;生物氧化塘的护堤和塘底未经防渗处理,造成下游地下水污染;养殖场排放的污水经厌氧和好氧生物处理后富含有机质、氨氮、可溶态有机磷,利于作物吸收和生长,应尽量循环使用。指出由于养殖污水变化较大,为避免二次环境污染,必须处理达标后结合配方施肥技术按需回用农田。     

玄武岩纤维水泥土的冲击劈裂性能试验研究

为了研究玄武岩纤维掺量对水泥土冲击劈裂性能的影响,进行了不同冲击气压条件下水泥土的霍普金森压杆(SHPB)试验.试验结果表明:随着玄武岩纤维掺量的不断增大,水泥土试件劈裂面的破碎程度逐渐变小,吻合程度逐渐变好,但过量的玄武岩纤维具有负面效应,试件冲击劈裂强度和吸收能均出现先提高后降低的趋势,在玄武岩纤维掺量为1.5％时...     

当前规划环评存在的问题与对策

以流域综合规划及梯级开发规划为例,分析了目前规划环评中存在的早期介入不足、整体性作用不明显、片面追求经济利益忽视规划环评、编制主体主动性不强和规划环评技术力量薄弱等问题。提出了加强法规宣传、抓紧相关法规和技术标准的完善与出台、重视技术力量建设及提高政策公开性等措施,解决目前规划环评存在的问题。     

Indoor air pollution and its impact on children under five years old in Bangladesh

Indoor air concentrations of volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), and dust particles were measured for 49 biomass and 46 fossil fuel users in urban slums of Dhaka, Bangladesh. The health impacts of these pollutants were assessed on 65 and 51 children under five years old from families who use biomass and fossil fuel as main source of energy, respectively. Mean concentrations of CO were found to be significantly higher in biomass fuel users (P = 0.010), while geometric mean concentrations of benzene, xylene, toluene, hexane, total VOCs, and NO2 were significantly higher (P < 0.01) in the fossil fuel users. Symptoms such as redness of eyes, itching of skin, nasal discharge, cough, shortness of breath, chest tightness, wheezing, or whistling chest were found to be associated with the choice of biomass fuel, with the odds ratio ranging from 4.0 to 6.3. No significant association of use of biomass fuel with respiratory diseases, eczema, diarrhea, or viral fever was observed after adjustment for potential confounders. These results suggest a significant association between the biomass fuel-using population and respiratory symptoms. These symptoms may not be due to the pollutants only, as some other underlying causes may be present. PRACTICAL IMPLICATIONS: The health of children under five years old in Bangladesh, especially those living in poor socioeconomic conditions, is considered to be worsening because of indoor air pollution. It is commonly suggested that biomass fuel should be replaced by fossil fuel, as pollution levels are believed to be higher with biomass fuel. Our findings, however, suggest that pollution can be higher with fossil fuels, and indicate that a switch in fuel from biomass to fossil does not necessarily improve the children's health. Awareness programs should therefore be undertaken to avoid the unnecessary use of gas. Clean fuels and clean stoves should also be ensured to reduce emissions of indoor air pollutants.     

Analysis of fracture mechanisms of ultrathin glass for flexible cover window under pen drop conditions

The fracture mechanism of a chemically strengthened ultrathin glass (UTG) for the cover window of flexible display devices was investigated under pen loading conditions for the first time to better understand the UTG impact resistance characteristics. High-speed camera analysis, fracture fragment analysis, and finite element modeling were employed to investigate the fracture mechanism of the UTG under pen drop conditions. A pen-on-plate (POP) test was also employed to examine the fracture characteristics under static loading condition, and its results were compared with those of the pen drop test (PDT) to find a correlation between the static and dynamic loading conditions. The correlation found between the POP and PDT tests indicates that a quantitative estimation of contact displacement under PDT can be obtained by measuring the first ring crack size, to more easily determine the impact resistance characteristics of UTG.     

Preparation of laminated safety glass based on high strength polyurethane film by solution annealing

Compared with the traditional polyvinyl butyral (PVB) laminated glass, the polyurethane (PU) based laminated glass has the advantages of higher impact strength and longer service life. Thus, aromatic polyurethane films have attracted more attentions in recent years due to their high light transmittance, adhesion and functionality. In this paper, the tensile strength of polyurethane films based on bis(4-isocyanatocyclohexyl)-methane (HMDI) have been increased from 27 to 51 MPa and their elongation at break have been increased from 330% to 525% after solvent annealing in toluene. It is attributed to molecular segments with high crystallization and hydrogen bond formation of PU, which are confirmed by FT-IR and XRD characterization. Based on this, laminated glasses with higher impact strength based on the thermoplastic polyurethane films are constructed successfully.     

Effect of imbibed moisture on monotonic and low-velocity impact behavior of injection over-molded short/continuous fiber reinforced polypropylene composites

Design of automotive components with over-molded short/continuous fiber reinforced thermoplastic composites necessitates understanding of their behavior under extreme outdoor conditions. The short, quasi-isotropic and over-molded short/continuous glass fiber reinforced polypropylene (PP) composite specimens were prepared as per standard and immersed in water until equilibration to study their relative moisture absorption characteristics and consequent mechanical behavior. As the absorbed moisture mostly occupied the interface between fiber and matrix in laminated composite inserts and moisture absorption of short fiber composite core is insignificant, the moisture absorption of over-molded composites is just above 50% of that of laminated composites. The flexural, interlaminar shear and impact behavior of equilibrated composites is primarily governed by the quantum of imbibed moisture of composite materials. Optical analysis of failed moisture equilibrated over-molded specimens showed a marginal delamination between plies of the inserts without any perceptible damage within the short fiber composite similar to dry as molded specimens.     

Critical review of methods for risk ranking of food-related hazards,based on risks for human health

This study aimed to critically review methods for ranking risks related to food safety and dietary hazards on the basis of their anticipated human health impacts. A literature review was performed to identify and characterize methods for risk ranking from the fields of food, environmental science and socio-economic sciences. The review used a predefined search protocol, and covered the bibliographic databases Scopus, CAB Abstracts, Web of Sciences, and PubMed over the period 1993–2013.

All references deemed relevant, on the basis of predefined evaluation criteria, were included in the review, and the risk ranking method characterized. The methods were then clustered—based on their characteristics—into eleven method categories. These categories included: risk assessment, comparative risk assessment, risk ratio method, scoring method, cost of illness, health adjusted life years (HALY), multi-criteria decision analysis, risk matrix, flow charts/decision trees, stated preference techniques and expert synthesis. Method categories were described by their characteristics, weaknesses and strengths, data resources, and fields of applications.

It was concluded there is no single best method for risk ranking. The method to be used should be selected on the basis of risk manager/assessor requirements, data availability, and the characteristics of the method. Recommendations for future use and application are provided.     

电力系统停电影响评价指标体系及其应用

为提升停电事故处理效率和事故分析准确率,从停电范围,停电用户,停电时间,停电损失等方面建立停电影响评价指标体系及其支撑系统.使用层次分析法确定各指标权重,然后使用模糊综合评价的方法分层次量化各指标进行综合评价,提出了用来评价一次停电事故大小的停电影响因子的概念.通过对某市级电网实例进行停电影响评价体系的构建,并针对一次具体的停电事件的影响进行评价,提出了后续抢修及避免影响扩大的具体措施,说明了该指标体系及其评价方法的实用性和有效性.