电厂屏式过热器弯头开裂原因失效分析

通过外观检查、硬度、金相等检测方法,从金属管壁超温运行、蒸汽侧氧化行为、析出相及冷弯变形对组织性能影响等方面分析了某电厂1 000 MW超超临界机组屏式过热器弯头开裂原因,得出TP347HFG弯头开裂的主要原因是弯头组织富含较多的σ相、NbC等硬脆析出相,同时冷弯加工导致管子内部产生残余应力,加剧了弯头脆性开裂的倾向。     

缓倾斜煤层孤岛工作面巷道底鼓机制及控制

针对缓倾斜煤层孤岛工作面回采巷道底鼓严重的状况,以庞庞塔矿5煤107工作面运输顺槽为研究背景,测试了顶底板的矿物成分、微观结构,利用物理模拟研究了底鼓机制,结果表明:①107工作面运输顺槽底板以高岭石为主,膨胀性岩石成分较低,岩石内部空隙较少,结构致密,强度高;②107工作面运输顺槽底鼓属于挤压流动性底鼓,掘进期间发生的是浅部岩层整体弯曲,在采动超前支承压力影响阶段,底板上位坚硬岩层超过其抗弯强度而发生破断,下位软弱底板解除约束,变形急剧增加,帮角出现裂隙,底板变形出现剧烈变形区、受限变形区、变形过渡区;③107工作面运输顺槽底鼓机制为:坚硬底板在高应力下的挤压流动是造成底鼓的主要原因,缓倾斜煤层巷道底板存在三角煤和底板岩石中存在少量膨胀性岩石对底鼓影响较小。针对性提出了采用开挖卸压槽释放压力方式进行底鼓治理,现场实测表明所提措施可有效降低巷道底鼓量。     

GIS设备内部检查机器人的模块化设计及实现

由于GIS设备内部存在缺陷或故障需要进行检查时,GIS罐体较长、管径细小,采用人工的方法无法有效查看内部状态并难以进入内部进行检修作业,因此本文研究了GIS设备内部检查机器人,采用模块化设计并实现了柔性机械臂功能、异物清扫功能及环境感知监测功能的模块化替换,可根据不同的作业场所选择对应的机器人功能模块进行内部工作。在实验室搭建了GIS设备罐体进行功能模块实验验证,实验结果表明：柔性机械臂模块旋转角、弯曲角满足GIS内部复杂环境作业要求,异物清扫模块能够完全清理GIS腔体底部的不同类型微小异物,环境监测感知模块可实现罐体内O2、H2S、SO2成分检测,确保机器人在110 kV及以上GIS设备内部发挥效用。     

外循环厌氧处理工艺中布水和三相分离的改进研究

污水处理中的布水设备和三相分离设备存在很多缺点,通过旋流配水装置和传统配水装置、小间距斜板三相分离装置和传统三相分离装置的比较试验,研究了旋流配水装置和小间距斜板三相分离装置的性能.研究结果表明:在相同膨胀率的条件下,旋流配水装置所需的回流量小,能耗相对较少;在水力上升流速为8 m/h时,采用旋流配水装置进水时,污泥分布曲线较平缓,污泥在高度上分布较均匀,而采用传统配水装置进水时,污泥主要分布在反应器底部,污泥浓度分布不均匀;在上升流速相同的情况下,采用小间距三相分离装置的反应器出水携带的颗粒污泥浓度较小;在相同的进水COD浓度时,小间距三相分离装置分离的沼气量较多.改进的布水和三相分离装置的性能明显优于传统的布水和三相分离装置.     

三元乙丙橡胶超细纤维复合膜的制备及其截留性能

以四氢呋喃和N,N-二甲基甲酰胺为溶剂,配制三元乙丙橡胶(EPDM)纺丝液,通过静电纺丝技术制备了EPDM超细纤维,进而以聚偏氟乙烯(PVDF)微滤膜为基膜制备了EPDM超细纤维复合膜。采用红外光谱(FTIR)和扫描电子显微镜(SEM)对EPDM超细纤维的结构和形态进行了表征。考察了复合膜对苯乙烯废水的截留效果和复合膜通量的变化情况。实验结果表明:EPDM超细纤维具有类似无纺布形式的多孔纤维网状结构,其直径在0.2~2.0μm之间;复合膜在操作压力为0.1MPa的条件下,处理质量浓度为100μg/mL的模拟苯乙烯废水,膜通量约为5.90mL/(cm2.h),苯乙烯去除率可达89.7%。     

张衡地动仪工作原理探究∗

张衡地动仪至今仍未得到公认的复原模型,通过对张衡的哲学思想、科学成就等史料研究,对袁宏著《后汉纪》中描述地动仪的文字内容进行分析,对张衡研制的“地动仪”和“水运浑象”进行比较,认为地动仪为自动运行一体化精密仪器,可实现对微弱地振动信号感知、放大和记录功能。结合当时的历史背景和科技水平,提出了三点悬挂复合物理摆+机械杠杆放大的地动仪复原技术方案,详细介绍了地动仪摆锤的悬挂方式、八个方向地振动信号的提取、机械杠杆放大机构和擒纵机构的设计思路,并研制了实验样机,证实地动仪工作原理具有科学性,且能与文献中描述地动仪的文字内容相互验证。     

Effects of productivity on biodiversity in forest ecosystems across the United States and China

In the global campaign against biodiversity loss in forest ecosystems, land managers need to know the status of forest biodiversity, but practical guidelines for conserving biodiversity in forest management are lacking. A major obstacle is the incomplete understanding of the relationship between site primary productivity and plant diversity, due to insufficient ecosystem‐wide data, especially for taxonomically and structurally diverse forest ecosystems. We investigated the effects of site productivity (the site's inherent capacity to grow timber) on tree species richness across 19 types of forest ecosystems in North America and China through 3 ground‐sourced forest inventory data sets (U.S. Forest Inventory and Analysis, Cooperative Alaska Forest Inventory, and Chinese Forest Management Planning Inventory). All forest types conformed to a consistent and highly significant (P < 0.001) hump‐shaped unimodal relationship, of which the generalized coefficients of determination averaged 20.5% over all the forest types. That is, tree species richness first increased as productivity increased at a progressively slower rate, and, after reaching a maximum, richness started to decline. Our consistent findings suggest that forests of high productivity would sustain few species because they consist mostly of flat homogeneous areas lacking an environmental gradient along which a diversity of species with different habitats can coexist. The consistency of the productivity–biodiversity relationship among the 3 data sets we examined makes it possible to quantify the expected tree species richness that a forest stand is capable of sustaining, and a comparison between the actual species richness and the sustainable values can be useful in prioritizing conservation efforts.     

城市电力供应系统公共安全风险评估体系及应用

城市电力供应系统与城市公共安全关系紧密，文章分析了导致城市电力供应系统故障或事故的主要风险因素、事故类型及其风险程度，建立了城市电力供应系统公共安全风险评估体系。利用建立的风险评估体系，对某市电力供应系统的安全性进行了风险评估，同时验证了该体系在城市电力供应系统风险评估中的良好适用性。     

Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.

     

The permeability of dredged material-bentonite backfills

Environmental Science and Pollution Research - Extensive attention has been paid to the treatment and disposal of dredged material, and there is a need to clarify the feasibility of recycling...