高压单芯电缆金属护套环流影响因素及抑制方法分析

随着社会经济飞速发展,人们用电需求持续增长,使得同一隧道中的电缆输电线路不断增加,各线路之间相互影响,导致金属护套环流问题日益严重。一旦出现环流,不仅会影响电缆运行安全,而且可能会造成严重的电力事故,因此研究高压单芯电缆金属护套环流影响因素及有效的抑制方法具有重要的现实意义。分析了高压单芯电缆金属护套环流的产生机理及影响因素,提出有效抑制电缆金属护套环流的方法,以期为相关行业工作人员提供参考和借鉴。

福建省极端降水时空变化特征及其环流因素分析

利用福建省22个气象观测站1961-2013年逐日降水量实测资料,应用趋势分析法、Mann-Kendall突变分析法、小波分析法、点值法和相关分析法,分析了极端降水的时空变化特征及其环流因素。研究结果表明:(1)在时间尺度上,福建省极端降水整体上表现出增加的趋势,其中SDII、R50mm和CWD存在明显的突变现象,突变时间分别在1994年左右、1995年左右和1998年左右;各极端降水指数普遍存在着2~3a、6~8a的短周期和10~12a的中周期;(2)在空间尺度上,极端降水受海陆位置、纬度位置影响存在明显的空间差异,具体表现为PRCPTOT变化趋势由东部沿海向西部内陆减小;(3)随着季节变换,影响或登陆福建省台风数、副热带高压带的强度引发明显的环流季节变化对福建省极端降水产生重要影响,福建省在850hPa和1000hPa位势高度差值均存在负的低值中心,有利于极端降水事件的发生。研究结果为未来福建省的极端气候变化趋势预测、福建农业气象灾害影响预估、决策提供参考。

Maixi River estuary to the Baihua Reservoir in the Maotiao River catchment:phytoplankton community and environmental factors

Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment, southwestern China, to understand phytoplankton community structure and environmental factors. The relationship between phytoplankton community structure and environmental factors including hydrological, meteorological, physical, and chemical variables were explored using multivariate analysis. A total of 81 taxa of phytoplankton were identified, which were mainly composed of chlorophyta, bacillariophyta, and cyanobacteria. The phytoplankton community was dominated by Pseudanabaena limnetica during summer and fall and by Cyclotella meneghiniana during winter and spring. The abundance of phytoplankton ranged from 0.24~ 104 cells/L to 33.45x 106 cells/L, with the minimum occurring during February 2010 and the maximum during July 2009. The phytoplankton community was dominated mainly by cyanobacteria from April to September, and by bacillariophyta and pyrrophyta from October to March. Canonical correspondence analysis showed that temperature, pH values, and orthophosphate were the most important driving factors regulating the composition and dynamics of the phytoplankton community in the estuary. Cyanobacteria and euglenophyta abundance and biomass were affected mainly by temperature and pH values, while most chlorophyta and bacillariophyta were influenced by the concentrations of nutrients.

Sap Flow of Abies georgei var. smithii and Its Relationship with the Environment Factors in the Tibetan Subalpine Region, China

Abies georgei var. smithii is a dominant species playing an important role in protecting biodiversity and sustaining the forestry ecosystems in Southeastern Tibetan Plateau. Stem sap flows of five different diameters at the breast height(DBH) A. georgei var. smithii samples were monitored continuously with the thermal dissipation probe for the entire growing period in order to understand the water transportation mechanism and the effects of environmental factors on its transpiration and growth. Relative environment factors, temperature and humidity of air, photosynthetically active radiation, rainfall, and wind speed, soil moisture, etc. were measured by the automatic weather stations. Diurnal and seasonal variations in sap flow rate with the different stem diameters and their correlations with meteorological factors were analyzed. The diurnal change in sap flow velocity showed a single-peak curve at the daily time scale, whereas a lower sap flow velocity can be observed in the largest DBH sample tree at night. The maximum average velocity was observed in August, whereas the minimum velocity was observed in January, and a large amount of water evaporated in summer owing to the higher sap flow velocity. In addition, sap flow velocity was closely related to changes in the micrometeorological factors, with average sap flow velocity showing significant linear correlations with air temperature, photosynthetically active radiation, rainfall, and vapor pressure deficit of air and soil moisture. Therefore, some measures, improving the light and temperature conditions, should be taken for protecting A. georgei var. smithii population in the Tibetan Plateau.

Identifying Key Environmental Factors Influencing Spatial Variation of Water Quality in Upper Shitoukoumen Reservoir Basin in Jilin Province,China

Based on the observed data in monitored drainage areas and GIS spatial analysis tools,watershed basic database of Shitoukoumen Reservoir Basin was built.The multivariate analysis and redundancy analysis(RDA) were used to analyze the spatial and temporal variations of water quality,identify the key environmental factors and their patterns influencing the spatial variation of water quality,and determine the main types and forms of the non-point source(NPS) pollutant export controlled by the key environmental factors.The results show that different patterns of environmental factors lead to great changes in water quality at spatial and seasonal scales.All selected environmental factors explain 64.5% and 68.2% of the spatial variation of water quality over dry season and rainy season,respectively,which shows clear seasonal difference.Over dry season,residential land is the most important environmental factor,which possesses 35.4% of the spatial variation,and drainage area is the second key environmental factor,which possesses 17.0% of spatial variation in the total variance.Over rainy season,slope length and drainage area are the key environmental factors,which possess 29.3% of the spatial variation together.Residential land influences nitrogen export by changing NH4+-N and particulate organic nitrogen(PON) discharge over dry season,and drainage area controls phosphorus export by regulating dissolved phosphorus(DP) drainage over dry season and phosphorus associated particulate(PAP) loss over rainy season,respectively.Although slope length is an important environmental factor,it does not influence NPS pollutant export.It is interesting that soil organic matter,as a minor environmental factor,highly determines phosphorus and nitrogen export by enhancing the DP,PAP and PON loss.

Withdrawing from Agrarian Livelihoods: Environmental Migration in Nepal

Although about two-thirds of Nepalese families depend on agriculture as their major source of income, the agriculture is mostly rain-fed and it has been adversely affected by water hazards and the subsequent degradation of resources. Based on case studies from three different geographical regions in Nepal, this research examines how environmental factors cause decreasing crop production and push people to abandon agriculture and accept emigration for employment. The research findings suggest a chain of push factors starting from drought or erratic rainfall causing water hazards, which impacts on depletion of crops and livestock, losses in income and employment and increased human mobility and emigration. The paper argues that the Government of Nepal and development partners can be more effective in enabling agrarian families to cope with the water hazards and shocks by formulating pro-poor mitigation and adaptation policies and strategies,focusing both on ‘rapid-onset' and ‘slow-onset' water hazards.

Economic Factors in the Use of Renewable Energy Sources in Kazakhstan

The purpose of this research was to study economic incentives to use renewable energy sources in the Republic of Kazakhstan and to give suggestions for production and circulation of the ＂green＂ certificates as a new financial instrument. The author analyzed European Union and Kazakhstani experience of economic incentives to reduce emissions and introduction of renewable energy sources. As a result of conducted research, the proposal to produce and circulate new financial instruments in Kazakhstan is made; as well as economic and environmental factors of renewable energy sources in the Republic of Kazakhstan are defined.

Empirical study on evaluation of regional agri-food logistics capability in e-commerce environment based on factor analysis A case study of Hebei province

With SPSS16.0 software, this paper chooses the statistical data of 11 cities in Hebei province to empirically study the agri-food logistics capability based on the method of factor analysis, and finally obtains the ranking of the 11 cities. It shows that, factor-cluster analysis is an effective method to analyze the logistics capability of agri-food. It can simplify the original complicated problem and lead to an objective, reliable and convincing conclusion.

Morphometric Comparison of White Tambaqui （Piaractus brachypomus） in Lentic and Lotic Environments

The purpose of this paper is looking for associations between environmental factors and morphological parameters in tambaqui （Piaractus brachypomus） individuals to differentiate this species in lentic environments （lake） and lotic （river）. In this, regard studied 30 specimens, 15 from lentic environment （lake） and 15 from lotic （river）. Also, on right profile of these 25 morphometric variables were measured. On data matrix a PCA （principal components analysis） based on morphometric correlations matrix, which was defined in the new morphologic space of these specimens （3 principal components） which explain 73.23% of variability. Fish projection in first two principal components showed a morphological differentiation between two environments （lentic and lotic）, with variables as, horizontal eye diameter, length maxilla, suggesting greater response of these fish in lotic environment by their adaptation to light conditions, predators threat and food distribution. Finally, in lotic environment these fish have thinner caudal peduncle, indicating greater plasticity, namely stylized fish.