某型武器复合材料漆层开裂原因分析及试验研究

对某型武器进行环境试验考核时,碳纤维复合材料出现了不同程度的漆层开裂现象,针对这些问题,进行了技术性分析,并进行措施改进。通过确定合理的喷漆环境、表面质量、喷漆工艺及油漆厚度等,某型武器碳纤维复合材料顺利通过环境试验,漆层无开裂现象,取得了良好的效果。     

韩江流域河水地球化学特征与硅酸盐岩风化——风化过程硫酸作用

流域岩石化学风化是全球碳循环的重要环节之一,硅酸盐岩风化过程消耗大气CO_2,是在地质时间尺度上调节大气CO_2浓度的重要机制。本工作在对我国东南花岗岩地区流经典型的硅酸盐岩地质背景河流——韩江流域河流水化学组成研究的基础上,分析和定量计算了河流水体主要物质来源,并对硫酸参与岩石风化和碳循环过程的作用进行了分析,进而对韩江流域岩石风化速率及其大气CO_2消耗通量进行了估算。结果表明,韩江流域河流主离子组成主要来源于硅酸盐岩和碳酸盐岩风化,并计算得出约41%的硫酸根离子来自于大气降水;流域碳酸盐岩的风化速率为21.7 t/(km~2·a),硅酸盐岩为18.9 t/(km~2·a)。硫酸参与岩石风化提供的离子贡献占流域岩石风化提供总离子量的65.9%;流域风化带来的CO_2消耗速率被高估了约61%。     

Assessing vulnerability to invasion by nonnative plant species at multiple spatial scales

Basic information on where nonnative plant species have successfully invaded is lacking. We assessed the vulnerability of 22 vegetation types (25 sets of four plots in nine study areas) to nonnative plant invasions in the north–central United States. In general, habitats with high native species richness were more heavily invaded than species-poor habitats, low-elevation areas were more invaded than high-elevation areas, and riparian zones were more invaded than nearby upland sites. For the 100 1000-m² plots (across all vegetation types), 50% of the variation in nonnative species richness was explained by longitude, latitude, native plant species richness, soil total percentage nitrogen, and mean maximum July temperature (n = 100 plots; P < 0.001). At the vegetation-type scale (n = 25 sets of four 1000-m² plots/type), 64% of the variation in nonnative species richness was explained by native plant species richness, elevation, and October to June precipitation (P < 0.001). The foliar cover of nonnative species (log) was strongly positively correlated with the nonnative species richness at the plot scale (r = 0.77, P < 0.001) and vegetation-type scale (r = 0.83, P < 0.001). We concluded that, at the vegetation-type and regional scales in the north–central United States, (1) vegetation types rich in native species are often highly vulnerable to invasion by nonnative plant species; (2) where several nonnative species become established, nonnative species cover can substantially increase; (3) the attributes that maintain high native plant species richness (high light, water, nitrogen, and temperatures) also help maintain nonnative plant species richness; and (4) more care must be taken to preserve native species diversity in highly vulnerable habitats.     

Contribution of mangrove detritus to juvenile prawn nutrition: a dual stable isotope study in a Malaysian mangrove forest

Dual stable C and N ratio analyses of primary producers and prawns have clarified the important role of mangrove detritus as the primary food source of juvenile prawns inhabiting the upper estuaries of the Matang mangrove swamp in Malaysia. The contribution of mangrove carbon to prawn tissues, as high as 84%, decreased in the offshore direction, as the contribution by phytoplankton became progressively more important. Prawns located 2 km outside the mangrove swamp still exhibited a dependency of 15–25% on mangrove carbon, but farther offshore (7–10 km) in shallow waters, the prawn's food was basically phytoplankton, with some contribution from benthic microalgae. Comparative stable C and N isotope ratios of tissue and gut contents indicate that prawns basically assimilated what they consumed. Received: 29 February 2000 / Accepted: 26 August 2000     

基于APCS-MLR模型的开封市公交站周边灰尘重金属源解析及健康风险评估

为揭示城市交通系统对城市生态环境质量的影响,选择受交通影响扰动较强的环境指示物——公交站地表灰尘作为研究对象,利用电感耦合等离子体质谱仪（ICP-MS）和电感耦合等离子体发射光谱仪（ICP-ASE）分别测定灰尘中8种重金属（V、Cr、Co、Ni、Cu、Zn、Cd和Pb）含量,应用地累积指数和污染负荷指数法分析灰尘重金属的污染程度和空间分布特征,通过定性（相关性分析、主成分分析）和定量[绝对因子得分-多元线性回归模型（APCS-MLR）]相结合的方法开展公交站附近地表灰尘重金属来源探讨,应用克里格空间插值法明晰重金属不同来源的空间分布特征,利用美国环境保护署提出的健康风险评价模型来评价人体健康风险.结果表明,开封市公交站地表灰尘重金属ω（V）、ω（Cr）、ω（Co）、ω（Ni）、ω（Cu）、ω（Zn）、ω（Cd）和ω（Pb）平均值依次为:68.36、59.73、5.81、19.34、40.10、208.32、1.01和49.46 mg·kg^-1,灰尘中重金属（Cd、Zn、Pb、Cu、Cr）含量平均值均高于开封市周边灰尘背景值,分别是背景值的3.37、2.70、2.01、1.95和1.28倍;8种重金属的地累积指数顺序为:Cd > Zn > Pb > Cu > Cr > V > Ni > Co,其中Cd、Zn、Cu和Pb属于轻度污染水平,其他元素为无污染;源解析结果显示,Cr、Co和Ni为自然源元素,Cu、Zn、Pb和Cd为交通源元素,V则来源于工业-自然混合源.APCS-MLR结果表明,4种来源的平均贡献率依次为自然源为34.17 %,交通源为29.84 %,工业-自然混合源为14.64 %,未知源为21.35 %,其中交通源贡献率空间分布规律与交通量及公交线路密集度分布趋势一致.由健康风险评价可知,儿童的总致癌风险指数和总非致癌风险指数均高于成人,Cr为主要的非致癌因子,Cd为主要的致癌因子,自然源和交通源分别对非致癌风险和致癌风险的贡献率最高.     

Experimental determination of optimum gutter brush parameters and road sweeping criteria for different types of waste

The removal ability of gutter brushes for road sweeping for various debris types and different sweeping parameters is studied through experimental tests. The brushing test rig used comprises two commercial gutter brushes, a concrete test bed, and an asphalt test road with a gutter of 0.25 cm width and 10° slope. The brush-surface contact area is determined by sweeping sand on the concrete test bed. Sweeping problems are identified and discussed, and sweeping criteria for the different debris types are suggested. Also, optimum sweeping parameters are proposed for each debris type. In addition, debris removal mechanisms are discussed and analysed. The results indicate that for large heavy debris such as stones and gravel, it is not difficult to achieve large removal forces, because the steel bristles are relatively stiff. Conversely, high removal forces are not needed for particles of millimetre or micron sizes, but bristle curvature has to be appropriate to remove particles from road concavities. Finally, it is found that mud, especially dry mud on a rough surface, is the hardest debris to sweep, requiring a brush with a large tilt angle and a very large penetration to produce large removal forces.     

基于RBI的输气站场分离器风险评估方法研究

通过对输气站场常用的风险评估方法与RBI的技术方法进行对比分析,提出采用RBI技术对输气站场的分离器进行风险评估.根据输气站场分离器的失效机理和运行环境,对其失效概率和失效后果进行了定量分析,建立了输气站场分离器RBI风险评估流程.然后通过一个实际案例验证了基于RBI的风险评估方法在输气站场分离器风险评估中的合理性和实用性,并根据评估结果提出了分离器的优化检验策略.本研究为输气站场设备的风险评估提供了一种新的方法.     

安全系统可靠性分析方法

讨论了安全系统可靠性分析的最新趋势,即:由对系统的定性分析转向定量分析.给出了可靠性分析的一些方法,包括定性和定量方法.重点研究了马尔可夫故障模型法.针对马尔可夫故障模型法计算量大的缺点,提出了相应的改进方法微马尔可夫故障模型法,分析了此法在可靠性分析中的应用.     

Multi-effects of gravity and geometric flow channel on the performance of continuous microbial fuel cells

Nowadays microbial fuel cells (MFCs) are a rapidly evolving field and studied extensively because of their simultaneous dual functions of decomposing organic waste matter and eco-power generation. Now, facing their low power density, multiple effects including various gravity conditions ranging from 0 G to 2 G and three kinds of geometric flow channel (serpentine channel, serpentine tapered channel and bio-mixer channel) in MFCs were studied because of their ability to significantly impact the performance of MFCs.Numerical simulation technology, with its significant lessening of time needed and saving experimental costs required was used in this study. Results show that a better power performance was found at a condition of 0.125 G and Reynolds number Re = 41.3 regardless of flow channel in MFCs. In addition, the bio-mixer channel of the flow channels in MFCs will have a better performance than the other two channels because of its lower pressure drop and higher power generation. These findings will provide useful information on enhancing the performance of MFCs, especially with the application of low gravity conditions in the future.     

Effects of chaotic acclimation applied on performance of microbial fuel cells

Microbial fuel cells (MFCs) are one of the bioreactors that produce electrons by metabolizing substrate from microorganisms, and have the ability to both degrade waste solution and produce electrons. Recently, the activity of microorganisms has limited the power performance of MFCs. Chaos has been used to stimulate activity of microorganisms, but it has not been used previously in MFCs. In this study, three types of acclimations – native acclimation (NA), MFC acclimation (MFCA), and MFC embedded with chaotic electric field acclimation (CMFCA) – are applied to realize their performance and chemical oxygen demand (COD) removal in MFCs, respectively. Results show that the current density and the power density of CMFCA were improved by 1.33 and 1.25 times than MFCA, and the COD removal of CMFCA reached 85% after five days. In addition, the acclimation stage at the condition of CMFCA appeared after 10 days, but was not found for the MFCA system. These observations would provide positive information for improving the performance of MCFs in the future.