动车组关键板卡失效分析与预防措施

目的 对动车组关键板卡进行失效分析,并提出预防改进措施.方法 通过对动车组运用过程中的环境分析,确定影响板卡性能的主要因素为温度与湿度应力.为缩短试验周期,设计恒温恒湿加速应力试验,快速暴露板卡及其元器件的薄弱环节.试验中受应力影响,板卡与元器件发生了不同程度的失效.通过对失效部件的物理化学性能进行分析,对板卡的使用环境与分析方法提出建议.结果 动车组板卡在高温高湿环境下的失效模式为电性能故障,由于密封不良,电感表面有纤毛和白色附着物,工作时温度过热导致漆包膜破损,从而使电感失效,焊点、PCB基材与三防漆未检测到失效老化.结论 电感、MOS管、电解电容等元器件受温湿度应力影响较大,且板卡的密封与使用环境也影响着板卡的使用寿命,日常使用应注重散热与密封.通过该项目研究为板卡失效预防提供了可行方法.     

西江流域农村环境整治项目长效管理机制研究——以贵港市农村环境整治项目为例

本文针对当前农村生态文明建设和环境保护的形势,结合西江流域农村环境实际,以贵港市农村环境整治项目为例,深入研究农村环境整治项目推行的现状和建设运营上的问题,运用公共产品理论、多元治理理论与公民参与理论等公共管理理论,分析目前长效管理存在的问题,从政府、市场企业、社群类织组和公民个人等四个方面,分析多元治理西江流域农村环境整治项目的模式,探求长效管理机制的构建途径。     

新疆喀纳斯景区道路灰尘的磁学特征及环境意义

为了验证环境磁学方法监测旅游景区道路灰尘环境的可行性，以新疆喀纳斯5A级景区道路灰尘为研究对象，采用磁测和统计方法对其进行磁学特征、空间变异特征及环境意义研究。结果显示，道路灰尘样品磁性矿物含量偏高；载磁矿物以亚铁磁性矿物为主，同时含有一些不完全反铁磁性矿物；磁性矿物粒度主要是多畴和稳定单畴粗颗粒；考虑到研究区远离工业区、城市等污染源，景区道路灰尘样品磁性增强主要来自旅游交通活动输入的磁性污染物颗粒，其次来自路旁表土和自然大气降尘；从道路样品磁性参数的空间分布看，χ_LF、SIRM、SOFT的空间变化趋势类似，高值区位于景区换乘中心，中值区出现在湖口区域和通往新村和观鱼亭的主干道，低值区分布在新村和通往湖口别墅区的主干道。景区不同道路旅游交通流量和强度是形成磁性特征空间分布格局的主因。研究发现，环境磁学方法基本具备大范围监测景区道路环境质量、圈定潜在污染范围和判别污染物来源的潜力，可以为景区道路交通污染防治提供参考依据。     

有多少生命可以重来

小读国际生物多样性 生物多样性指的是地球上生物圈中所有的生物，即动物、植物、微生物，以及它们所拥有的基因和生存环境。它包含三个层次：遗传多样性，物种多样性，生态系统多样性。     

绿色城镇化进程中的资源环境问题研究

从社会学角度看,城镇化是经济社会发展基础上的人口再分布和社会组织制度体系转型过程。我国快速城镇化大幅度地改变了社会系统与资源环境之间的关系,产生了广泛而深远的资源环境影响,需要从其复合性、过程性、双向性、阶段性和社会性等方面予以理解和把握。迈向绿色城镇化需要加速推进制度建设,促进社会组织制度体系转型。     

Diurnal variation of aethalometer correction factors and optical absorption assessment of nucleation events using multi-wavelength photoacoustic spectroscopy

A field measurement campaign was carried out during the late winter and early spring of2015 in Budapest, the capital of Hungary. The size distribution(SD) and optical absorption of carbonaceous particulate matter(CPM) was measured online using a Scanning Mobility Particle Sizer(SMPS), a 7λ-aethalometer and an inhouse developed 4λ-Photoacoustic Spectrometer. Based on the SD data, the measurement period could be classified into days with and without new particle formation events(normal days and nucleation days),although particular nucleation-like events were observed on normal days as well. Three characteristic size modes were observed with CMDs of circa 15, 25 and 110 nm that corresponded to the nucleation, traffic and heating modes. Based on the temporal behavior of these modes both types of days were divided into distinctive daily periods(heating hours,traffic hours and nucleation hours). The optical absorption spectra(OAC and AAE) also displayed the same part of day behavior to that of SD. That way this paper is among the first to assess the optical response of urban nucleation events. Due to the simultaneous measurement of OAC by the 7λ-aethalometer and a 4λ-Photoacoustic Spectrometer, OAC was measured overall at 11 wavelengths. That way aethalometer correction factors(f and C)were determined at all aethalometer wavelengths using in situ reference photoacoustic measurements. Correction factors were found to have both wavelength and time of the day variation. In the case of f, no clear trend could be observed, however, Cref values increased both as a function of wavelength.     

增白、护肤小心中毒

冬季,很多女士喜欢用增白粉蜜、增白奶等来美容,但要注意,有的增白剂具有一定的毒性。增白化妆品中含有的有毒化合物主要分成两类：一是无机汞盐类,多以汞的氯盐或磺性形式加入增白化妆品中。汞离子能干扰正常酶催化的由酪氨变成黑色素的反应,从而使皮肤增白。但无论有机汞还是无机汞,在与皮肤接触时都很容易被吸收。皮肤搽上这种化妆品五小时内有百分之六的汞被吸收。如果长期用这种化妆品,皮肤吸收的汞元素将造成不可低估的危害。 另一类是氢醌类增白剂,属于苯酚的衍生物,它影响色素颗粒的形成及沉着,对黑色细胞有损害,可以有一些增白剂效果,但高于百分之三的氢醌可引起皮肤萎缩,色素沉着,变态性接触过敏,造成皮肤红斑、水肿等中毒现象。     

交通安全四法

笔者在松藻矿区和到重庆、成都、北京等大城市 ,多次听到、读到或亲眼见的车辆肇事悲剧 ,使我受到了交通安全必须从小事做起的教育 ,并归纳出个人“交通安全四法”,供广大读者借鉴和参考。(1 )走安全道法凡有天桥或地下通道之处 ,宁可多走点路也不乱穿马路。为减少爬梯上坎的劳     

Slope aspect modifies community responses to clear-cutting in boreal forests

Slope aspect modifies microclimate and influences ecological processes and spatial distribution of species across forest landscapes, but the impact of slope aspect on community responses to disturbance is poorly understood. Such insight is necessary to understand landscape community dynamics and resilience. We compared bryophyte (liverworts and mosses) communities in matched 0.02-ha plots of four boreal stand types in central Sweden: recently clear-felled and mature stands dominated by Norway spruce in south-facing and north-facing slopes. Differences between forests and clear-cuts were interpreted as effects of clear-cutting, and differences between south- and north-facing slopes as effects of aspect. In response to clear-cutting, bryophyte cover and composition changed more in south-facing slopes. Only one out of ten significantly declining species in south-facing slopes also declined significantly in north-facing slopes. North-facing slopes lost fewer bryophyte species, and among those, fewer forest species and fewer species associated with wood and bark. In north-facing slopes, the average proportions of mosses and liverworts shared between the forest and the clear-cut plot were 88% and 74%, respectively. Corresponding numbers for south-facing slopes were 79% and 33%. In addition, more bryophyte species were added in north- than south-facing slopes after clear-cutting, somewhat reducing the difference in compositional change between aspects. South- and north-facing mature forests differed in species composition, mostly due to higher richness of mosses in south-facing slopes. The smaller changes in bryophyte communities on north-facing slopes in response to clear-cutting have implications for ecosystem dynamics and management as high local survival may enhance landscape-level resilience.