泥石流暴发频率与其形成区块石粒径的关系

泥石流是山区常见的地质灾害之一,重大的泥石流灾害往往是由低频率泥石流造成的。通过对四川省西部地区17条泥石流沟的野外实地考察,测量了泥石流沟道内不同位置的块石粒径,研究了泥石流形成区、堆积区粗大块石粒径与泥石流暴发频率之间的关系。通过统计调查研究,得出坚硬岩石地区的块石粒径较大,泥石流暴发频率较低的结论,并初步给出由块石岩性、粒径来判定泥石流暴发频率的方法。用块石岩性和块石的平均粒径推测该泥石流沟的暴发频率,在低频泥石流的判断上简单可行,较为实用：可以通过查询地质图、判断主要岩性、对块石粒径赋值、选取影响因素进行修正、判定泥石流暴发频率。为深入研究低频率泥石流的形成机理提供了基础数据,为有效地预测和防治低频率泥石流提供了依据     

Atmospheric organochlorine pesticide (OCP) levels in a metropolitan city in Turkey

Air concentrations of organochlorine pesticides (OCPs) were measured at four different sites in Bursa, Turkey to determine current levels. For this purpose, about 35 samples were collected from June 2008 to June 2009 using a high volume air sampler (HVAS) equipped with particle and gas-phase units. Ten OCP compounds (alpha-, beta-, gamma-, delta-hexachlorocyclohexane, Heptachlor epoxide, Endrin, Endosulfan beta, Endrin aldehyde, p,p′-DDT and Methoxychlor) were reported within the scope of this study. The average concentrations of total (particle + gas) ∑OCPs were 550.9 ± 277.6 pg m⁻³ (coastal), 1030.7 ± 453.5 pg m⁻³ (urban/traffic), 519.7 ± 277.5 pg m⁻³ (semi-rural) and 722.8 ± 351.8 pg m⁻³ (urban/residential). The individual OCP concentrations were in line with reported concentrations. The maximum particle and gas-phase concentrations were determined for Endosulfan beta and beta-HCH for all sites, respectively. Available gas/particle partitioning models were applied in order to investigate the compatibility of the experimental data and the significant relationships were observed.     

Coarsening of extracellularly biosynthesized cadmium crystal particles induced by thioacetamide in solution

A novel coarsening route for extracellularly biosynthesized cadmium nanocrystals was investigated for the first time. In this process, the white rot fungus Coriolus versicolor was employed to take up cadmium ions and synthesize extracellular cadmium crystal particles. The coarsening of the particles was induced by thioacetamide under certain conditions. Scanning electron microscopy showed that the formed cadmium crystal particles were coarsened from about 100 nm to 2-3 μm. The corresponding energy-dispersive X-ray spectra confirmed the presence of proteins in the particles. The maximum removal efficiency of Cd(II) increased from 17% to 87%, and the corresponding sorption capacity of biomass increased from 4 to 24 mg g⁻¹ with the completion of the coarsening process. The properties of the coarsened particles were also examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD analysis of fungal mycelial pellets embedded with the coarsened particles confirmed the formation of cubic crystalline cadmium sulfide particles. The TEM results suggest that the coarsened particles were composed of clusters of several smaller particles. The changes in the functional groups on the biomass surface were studied through Fourier transform infrared spectroscopy. Based on the results above, a possible mechanism for the formation and coarsening of cadmium crystal particle is also discussed.     

柴油机排放多环芳香烃气/颗粒相分配研究

为了对柴油机排放PAHs在气相和颗粒相中的分配进行研究,采用了滤膜串联＂PUF/XAD-2/PUF＂吸附柱的方法采集柴油机排气中的气相和颗粒相PAHs,使用程序升温挥发（PTV）技术结合气相色谱-质谱联用（GC-MS）方法对PAHs进行了定性和定量分析。所用分析方法重复性的相对标准偏差（RSD）低于6.1%,检出限范围...     

滤膜在颗粒物无机元素监测中的适用性研究

筛选国内外12个制造商的玻璃纤维、石英、特氟龙、聚丙烯、乙酸纤维、硝酸纤维和混合纤维等7类材质34种滤膜,测定滤膜中的铍、铬、锰、钴、镍、铜、锌、砷、钼、镉、锡、锑、铊和铅等14种元素含量,探讨不同材质滤膜中各元素的质量分数分布,采用大气固定源污染物排放标准中项目限值和分析方法标准中质量控制要求,对铜、锌之外的12种元素进行适用性评价。结果表明:玻璃纤维滤膜比其他材质滤膜中无机元素的质量分数高1～5个数量级,进口玻璃纤维滤膜中铬、镍、砷、镉等4种元素质量分数高于多数国产玻璃纤维滤膜,国产A、H玻璃纤维滤膜中14种元素质量分数相对较低;仅混合纤维滤膜中镉、铅的测定值浓度低于最严标准限值的10%,玻璃纤维滤膜之外的其他材质滤膜均能满足监测其余10种元素的本底需求。     

固定污染源排放可凝结颗粒物采样方法综述

综述了国内外固定污染源可凝结颗粒物(CPM)冲击冷凝法和稀释冷凝法2种采样方法,指出CPM是固定污染源排放颗粒物的重要组成部分,国内对于固定污染源CPM排放的监测和研究尚处于起步阶段,缺乏必要的CPM采样标准方法。通过分析2种采样方法的优缺点,提出冲击冷凝采样法需进一步降低SO_2等水溶性气体的影响,提高气相CPM冷凝效果及超细颗粒态CPM的捕集效率;稀释冷凝法需提高采样装置的便携性实现可过滤颗粒物(FPM)和CPM的分离采样,提高采样管路壁面颗粒物回收率。同时,针对我国固定污染源如燃煤电厂大量使用湿法脱硫设备的情况,CPM采样方法需提高对低温高湿且夹带液滴烟气采样的适用性。     

Design and analysis of artificial bee-colony-based MPPT algorithm for DFIG-based wind energy conversion systems

In this article, the proposed maximum power point tracking (MPPT) method is designed by taking rotor speed as an optimization problem, which is solved by artificial bee colony (ABC) algorithm to generate the maximum power output. The main advantage of this algorithm is that its optimal solution is independent of the initial positions and requirement of lesser number of control parameters, which leads to simple and robust MPPT algorithm than other algorithm. Furthermore, the hill climb search and particle swarm optimization-based MPPT algorithm are also discussed and the results obtained by these are compared to verify the effectiveness of proposed algorithm. Simulations for MPPT control along with doubly fed induction-generator-based wind energy conversion system is carried out in MATLAB/Simulink environment. Three statistical methods are used to evaluate the accuracy of each MPPT algorithm. All results are analyzed and compared under randomly selected wind as well as real wind speed configuration. Comparison of both numerical and simulation results under two different varying wind speed conditions strongly suggest that the proposed ABC-based MPPT algorithm is superior than other two MPPT algorithms.     

The effect of cerium oxide additive on the performance and emission characteristics of a CI engine operated with rice bran biodiesel and its blends

In this study, the rice bran oil (RBO) has been converted into methyl ester with an aid of transesterification reaction. Chemically, transesterification means conversion of triglyceride molecule or a complex fatty acid into alcohol and ester by removing the glycerin and neutralizing the free fatty acids. The B20 blend samples [80% diesel + 20% biodiesel] were prepared for each methyl ester obtained from RBO and then the cerium oxide (CeO₂) nanoparticles were added to the each B20 blend samples at a dosage of 50 ppm and 100 ppm with an aid of ultrasonicator. Moreover, in the absence of any engine modifications, the performance and emission characteristics of those blend samples have been investigated from the experimentally measured values such as density, viscosity, cloud point, pour point, and calorific value while the engine performance was also analyzed through the parameters like exhaust gas temperature (EGT), brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), exhaust emission of carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx). The experimental results reveal that the use of CeO₂ blended biodiesel in diesel engine has exhibited good improvement in performance characteristic and reduction in exhaust emissions.     

粗粒料湿化变形数值模拟研究

粗粒料湿化变形特性对土石坝静力稳定有着显著影响。目前开展的三轴试验和直剪试验研究,一般只能进行干样和饱和样的试验,而对于非饱和情况研究较少。基于粗粒料不同围压下湿化变形试验研究成果开展数值模拟研究,结果表明:湿化变形的影响可以通过改变细观剪切模量和细观摩擦系数来实现;随着颗粒破碎随饱和度和围压的增加,湿化后粗粒料的强度低、内聚力降低,但摩擦角变化不大。