Spatial heterogeneity of lake eutrophication caused by physiogeographic conditions: An analysis of 143 lakes in China

In order to identify the effect of geographic characteristics on the variations of nutrient concentrations and the utilization efficiency of nutrients by phytoplankton, data from 143 lakes, from 2008 to 2010, including three very different types of topography, i.e., the first topography ladder(FTL), second topography ladder(STL), and third topography ladder(TTL), were statistically analyzed. Lakes in the FTL and STL, located at high elevation(above1000 m) and low longitudes(lower than 105° E), were sporadically oligotrophic, whereas lakes in the TTL were almost all mesotrophic and eutrophic. The trophic level index(TLI)became higher with the rise of longitude. Two turning points(5 and 15°C) on the curve of TLI as function of the average annual temperature(AAT) corresponded with the AAT in different lake regions in the STL and TTL. Because the responses of TLI to AAT differ significantly, there were variations of nutrient and algal biomass concentrations in different lake regions in the same type of topography ladder. According to the differences in utilization efficiency of total nitrogen or total phosphorus by phytoplankton, China could be partitioned into six lake regions. Scientific nutrient criteria for each lake region shall be established considering these differences in China.     

福建国有林场森林防火工程体系建设成效

福建是我国重点林区,也是森林火灾的重灾区,福建国有林场系统重视森林防火工程体系建设,强化林火阻隔网络、林火预报与监控,林火交通通讯,组建快速扑火队伍等“四网二化”建设,取得显著成效。     

邻苯二酚1,2-双加氧酶(C12O)基因的定位、克隆和表达

射性同位素标记ｔｆｄＣ基因片段作探针,Ｓｏｕｔｈｅｒｎｂｌｏｔ杂交定位Ｌ１菌株的邻苯二酚１,２双加氧酶基因位于ＰｓｔⅠ的Ｉ片段和ＢａｍＨⅠ的Ｍ和Ｎ片段．低熔点琼脂糖回收ＰｓｔⅠ的Ｉ段,直接克隆至表达载体ｐＫＴ２３０上,获得重组子ｐＫＴ２３０ｐ．重组子转化不具开环酶活性的甲胺磷降解菌Ｐ２,获得高效的Ｃ１２Ｏ酶活     

细水雾抑制熄灭书架火的模拟实验研究

细水雾灭火系统被建议用于保护对水敏感的环境,例如图书馆的珍稀图书收藏室。该文通过实验研究了细水雾控制与扑灭图书库火灾的可能性;论述了确定细水雾应用在图书库火灾防治中的局限性;得到了细水雾的灭火效率与书架火的点火位置以及火源的尺寸(功率)之间的关系,并作出了相应的解释。     

基于安全保障的分布式电源选址定容优化研究

分布式电源的发展是我国智能电网发展中的重要方面之一,基于安全保障性,合理地对分布式电源进行选址定容,对于中低压配电网规划具有重要意义。分析了分布式电源对配网的具体安全性影响。提出以安全第一、成本最小、网损最小、电压偏移最小为目标的综合效用目标函数模型,并采用遗传算法求解。通过对IEEE9节点配电网络的算例分析验证了所提算法在分布式电源选址定容求解问题中的可行性和实用性。     

杭州市农贸市场的噪声特点分析

对农贸市场噪声进行了监测分析。结果发现,农贸市场营业时,市场内的噪声超标,其最小值出现在中午,最大值出现在下午下班高峰期;农贸市场一天内不同时段噪声污染级的数值大小有一定的差距;用噪声冲击指数来评定农贸市场声环境质量,其声环境质量极差。     

三通管支管位置对爆炸火焰传播影响分析*

为研究分支管道位置对丙烷爆炸火焰传播的影响规律,通过多组数值模拟与已有实验数据对比,分析不同工况下三通管内火焰传播形态变化特征及温度变化。结果表明:向右传播的爆炸气流在支管左侧形成湍流旋涡,火焰受到拖拽及壁面制约,贴支管右侧壁面呈尖刀状传播;封闭管道中,火焰传播受主管道高速前驱压力波回波影响更显著,垂直支管中火焰与高温风险更大;实验支管位置距离点火源5.6 m时岔口处监测点温度高达2 214.08 K,支管位置增加至5.71 m时,支管处湍流旋涡拖拽火焰,使火焰出现中断,支管移至5.825 m后高温火焰无法传播至支管口,支管中的爆炸风险显著降低。研究结果为工业生产三通管支管位置的选择和支管内二次爆炸风险预测提供科学参考。     

火源位置对腔室火流动特性影响的实验研究

腔室火流动特性是影响腔室火灾蔓延与通风状况的重要因素。通过一系列小尺度腔室火实验,研究了火源位置变化对腔室火流动特性的影响。实验结果表明,随着火源沿腔室底部从壁面向开口方向移动,在开口中性面以上,同一高度处压差与流速增大,中性面高度和烟气层高度均降低,并导致开口质量流率增大。与火源强度相比,火源位置变化对烟气层高度的影响更为显著。火源位置对中性面高度及烟气层高度的影响在壁面处及开口处更为显著,腔室中部位置变化的影响相对较小。火源由壁面向开口移动,会造成火焰高度降低和水平伸长量增加。基于实验数据,给出了考虑耦合火源位置的腔室内火焰水平伸长量的表达式。研究结果可为相关场景下的腔室火灾理论模型提供实验结果支撑。     

基于城市火灾风险的消防站分级覆盖选址模型——以济南市区为例

为更科学规划消防站选址,实现有限资源下应急资源的合理配置,提高消防站联动效率,根据“不同火灾风险等级的需求点应得到主管消防站和不同数量增援消防站服务”的原则,提出1种消防站分级覆盖选址模型,同时使用覆盖衰减函数表示消防站对需求点的覆盖度;基于遗传算法设计消防站分级覆盖选址模型的求解流程;以济南市区为例,基于POI和火灾数据,使用核密度分析法进行城市火灾风险分级,进而对选址模型进行验证。结果表明:以覆盖火灾风险值为评价指标,分级覆盖选址模型的选址结果优于现状消防站、广义最大覆盖模型、P-中位模型和P-中心模型。     

Factors affecting post-disaster location choices of businesses: an analysis of the 1999 earthquake

Despite global policies advocating risk reduction and community level recovery, post-disaster implementations usually focus on households, but fail to focus on businesses in spatial terms. Due to the lack of appropriate policy and tools, businesses often make their own location choices as part of their recovery strategy. In view of this, this study aims to establish the factors affecting the location choices of businesses challenged by disasters in the absence of any specific spatial strategies designed for them. In order to determine these factors, empirical research was conducted in Adapazari, Turkey on 232 firms selected as a result of a stratified random sampling procedure. According to the analysis of the results, the most notable impacts on business location choices after a disaster shock are associated with occupancy status, education level, and extent of damage. In line with these findings, the impacts of business location choices are discussed to highlight the role of businesses in spatial decisions.