湿热环境下配电自动化终端的腐蚀失效分析

目的解决配电自动化终端在湿热环境下的腐蚀失效问题,保障配网自动化系统的安全运行,延长配电自动化终端的使用寿命。方法分别选用三台架空终端FTU作为研究对象,研究配电自动化终端在湿热环境下的腐蚀失效特点,并提出针对性防护措施。采用SEM和EDS表征方法展开配电自动化终端的腐蚀失效分析。结果由EDS数据结果发现,相比较于轻微腐蚀区域,腐蚀区域的氧含量均大幅增加,且出现硫元素和氯元素,表明腐蚀环境主要是含硫和氯的潮湿环境。航空插头表面覆盖镍和铜两层镀层,腐蚀后的试样表面不仅检测到铜,有的甚至检测到基材铁,说明腐蚀后镀层已逐步失效,部分基材裸露,且已开始腐蚀。结合SEM发现,样品表面有大量颗粒粗大的腐蚀产物,且明显看出镀层已被破坏。结论材料腐蚀失效主要是由于高温度、湿度、含氯及硫等大气环境加速终端设备腐蚀,以及镀层被破坏或漏镀等问题造成基材裸露,腐蚀进一步深入发展。因此,根据湿热环境下配电自动化终端的腐蚀特点,提出针对性的防护措施。保障配网自动化系统的安全运行的同时,延长配电自动化终端的使用寿命,为今后的实证测试提供可靠依据。     

新疆典型城市气溶胶光学厚度变化特征

利用2006~2017年Aqua-MODIS C006气溶胶日产品数据,选取新疆地区11个代表性城市进行分类,分析典型城市的AOD近12a变化趋势及特征.结果表明：2006~2017年间,除乌鲁木齐市AOD小幅度上升外,其余10个城市AOD均出现不同程度下降,北疆城市年均降幅较小,吐鲁番市12a间AOD下降了0.13,为哈密、焉耆等同纬度城市群中的最大降幅,南疆城市AOD年均降幅最为显著,阿克苏、喀什、和田和若羌地区AOD分别下降了0.18、0.16、0.16和0.09;AOD空间分布上,南疆为AOD峰值中心,年均值达0.50以上,北疆和东疆地区AOD年均值维持在0.20~0.22;同时,AOD具有典型的季节变化特征,春季为AOD峰值季节,夏季次之,秋、冬季AOD较低;此外,12a间新疆全区AOD出现不同程度降低,其中南疆沙尘源区为AOD下降的典型区域,减少区域呈现出沿昆仑山脉自南向北的带状分布.     

黑龙江哈尔滨地区近60年极端气温变化研究

用1955~2013年哈尔滨市、尚志市(县)和通河县逐日气温资料,采用线性倾向法、距平及累积距平法、Morlet复数小波、主成分分析、相关性分析和Mann-Kendall检验法,对11个常用气候指标进行分析。结果表明,哈尔滨夏、秋、冬季气温呈上升趋势,冬季升温极为显著,春季气温以0.60℃/10a的速度显著下降;年均气温、年均最低温、年均最高温均有所增加,年均最低气温升幅最大。年极端最高气温、年极端最低气温、夏日日数、热夜日数、暖夜日数和暖日日数6个指标呈上升趋势变化;结冰日数、霜冻日数、冷夜日数、冷日日数及气温年较差5个指数呈下降趋势。年极端最高气温、年极端最低气温及变化率较大的暖夜日数,均有28~30 a的第一主周期和17~18 a的第二主周期,冷夜主要有3、6和8 a的短周期。主成分分析结果表明,高载荷的指数暖夜、冷夜和暖日这些相对指数的变化是哈尔滨极端气温变化的主要原因。相关关系矩阵表明,相对指数间的相关性极为显著;各暖指标、各冷指标间呈正相关,暖指标和冷指标间呈负相关。Mann-Kendall检验得知,冰日、冷夜和冷日三个冷指标的突变发生在20世纪70s、80s,其他指标的突变主要发生在1990~1999年间。总之,哈尔滨平均气温以0.32℃/10a的速率增加,升温幅度高于全国平均升温值0.26℃/10a,研究结果可为防灾减灾提供理论依据。     

Lake area changes in the middle Yangtze region of China over the 20th century

The Jianghan Plain and the Dongting lake area, located in the middle reaches of the Yangtze River are famous for their abundant freshwater lakes. The lakes have undergone changes in size and number over thousands of years due to natural causes and human activities. The 20th century particularly, witnessed dramatic changes in the freshwater resources of this region. This paper traces and analyzes lake evolution in the middle reaches of the Yangtze River over the past century. Lakes greater than 0.1 km(2) in size are mapped using Geographic Information System. Data is acquired and integrated from drainage network maps, relief maps, historical maps and remotely sensed images for different time periods. The results indicate that while there has been little change in the number of lakes over the past century, the lake area has experienced a dramatic decrease of 58.06%. The paper also examines the natural processes and human activities that may have contributed to the decrease in lake area. The results show that the decrease in total lake area appears to coincide with periods of rapid land reclamation in the middle reaches of the Yangtze River. Moreover, uncontrolled land reclamation activities can create an increase in sediment deposition in lakes thereby further reducing the lake size. Reduction of the lake area directly affects flood-control and has a negative ecological impact on the environment and on human life and property.     

区域地震灾害承载力评价的突变模型

为提高区域地震灾害承载力评价的准确性,基于拓扑学与系统论的基本原理,运用突变理论,构建区域地震灾害承载力评价突变模型。首先,在区域地震灾害承载力与突变理论结合分析的基础上,构建区域地震灾害承载力评价指标体系;其次,进行原始数据标准化处理;接着采用相应的突变归一公式和突变原则进行递归计算区域地震灾害承载力突变隶属值,并与评判标准比较得其地震灾害承载力等级;最后计算29个城市的地震灾害承载力,并将所得计算结果与模糊可变识别评价方法、指数评价方法所得结果进行比较。结果表明,该方法评价结果与模糊可变识别评价方法、指数评价方法的评价结果基本一致。     

济钢210t转炉钢水罐热修除尘系统的设计及应用

介绍了钢水罐热修除尘系统的自主开发,除尘技术的设计,详细阐述可移动抽风罩、抗结露袋除尘器、覆膜玻璃纤维膨体纱等技术特点,以及整个除尘系统的控制技术,仅供同行参考借鉴。     

Evaluating weather effects on interannual variation in net ecosystem productivity of a coastal temperate forest landscape: A model intercomparison

Forest productivity is strongly affected by seasonal weather patterns and by natural or anthropogenic disturbances. However weather effects on forest productivity are not currently represented in inventory-based models such as CBM-CFS3 used in national forest C accounting programs. To evaluate different approaches to modelling these effects, a model intercomparison was conducted among CBM-CFS3 and four process models (ecosys, CN-CLASS, Can-IBIS and 3PG) over a 2500 ha landscape in the Oyster River (OR) area of British Columbia, Canada. The process models used local weather data to simulate net primary productivity (NPP), net ecosystem productivity (NEP) and net biome productivity (NBP) from 1920 to 2005. Other inputs used by the process and inventory models were generated from soil, land cover and disturbance records. During a period of intense disturbance from 1928 to 1943, simulated NBP diverged considerably among the models. This divergence was attributed to differences among models in the sizes of detrital and humus C stocks in different soil layers to which a uniform set of soil C transformation coefficients was applied during disturbances. After the disturbance period, divergence in modelled NBP among models was much smaller, and attributed mainly to differences in simulated NPP caused by different approaches to modelling weather effects on productivity. In spite of these differences, age-detrended variation in annual NPP and NEP of closed canopy forest stands was negatively correlated with mean daily maximum air temperature during July-September (T_amax) in all process models (R² = 0.4-0.6), indicating that these correlations were robust. The negative correlation between T_amax and NEP was attributed to different processes in different models, which were tested by comparing CO₂ fluxes from these models with those measured by eddy covariance (EC) under contrasting air temperatures (T_a). The general agreement in sensitivity of annual NPP to T_amax among the process models led to the development of a generalized algorithm for weather effects on NPP of coastal temperate coniferous forests for use in inventory-based models such as CBM-CFS3: NPP′ = NPP − 57.1 (T_amax − 18.6), where NPP and NPP′ are the current and temperature-adjusted annual NPP estimates from the inventory-based model, 18.6 is the long-term mean daily maximum air temperature during July-September, and T_amax is the mean value for the current year. Our analysis indicated that the sensitivity of NPP to T_amax was nonlinear, so that this algorithm should not be extrapolated beyond the conditions of this study. However the process-based methodology to estimate weather effects on NPP and NEP developed in this study is widely applicable to other forest types and may be adopted for other inventory based forest carbon cycle models.     

寒冷地区流域水污染防治问题

我国寒冷地区河流冰封期最长可达180天,其间水体自净功能差,加之城镇污水处理水平低于全国平均水平,工业点源污染负荷沉重,流域水污染问题显得格外突出,水环境压力巨大.因此,有针对性地解决寒冷地区流域水环境问题已经成为协调资源供求、经济发展与环境保护的核心问题.通过分析寒冷地区流域水污染特点及成因,提出了建立流域水污染防治...     

基于空间马尔科夫链的关中地区生态安全时空演变分析

生态系统内部和生态系统之间都不是封闭的,各要素间均存在着相互作用。利用已获得的陕西关中地区生态安全格网化评价结果数据,运用空间马尔科夫链对该区域的生态安全时空演变进行了分析,得出以下四个结论：①区域背景在关中地区生态安全趋同时空演变过程中起着相当重要作用;②不同区域背景在区域生态安全等级转移中所起的作用也各不相同;③一个区域生态安全等级向上或向下转移的概率与该区域和周围邻居之间的差异程度不成比例;④空间马尔可夫转移概率矩阵为＂区域趋同的时空演变＂现象提供了空间上的解释。实践表明,空间马尔可夫链方法为定量分析地理环境对区域生态安全变化的空间效应提供了方法依据,值得进一步研究和讨论。     

Cardiovascular Load During Summer Work of Two Age Groups of Van-Rickshaw Pullers in West Bengal,India

Van-rickshaw is a popular mode of transport of people and merchandise in developing countries. The purpose of this study was to assess the effect of age on cardiovascular load of van-rickshaw pullers in the summer season (March-June) in real situations. In 142 participants, divided into 2 age groups (25-40 and 41-55 years), cardiovascular load was assessed on the basis of working and partial recovery heart rate (HR), predicted maximal HR, working maximal HR, average working HR, percentage of reserved HR, sum of recovery heart beats, percentage of recovery, relative and net cardiac cost, etc. Except for percentage of recovery, all parameters differed significantly between the groups and were significantly correlated with age. As this activity is very stressful, it places a heavy demand on the cardiovascular system. Therefore, age is an important factor for sustainability of the work, especially in a hot environment. Some ergonomic interventions are necessary to reduce cardiovascular load.