预防粉尘灾害

1良好的管理有助于预防粉尘爆炸 引起粉尘爆炸需要4个要素:燃料来源,如谷物粉尘;着火来源,如来自设备故障或摩擦的火花;空气,它在设备中始终存在;以及上述3个要素在有限的空间同时存在,诸如提升机机筒或输送机机壳、立筒库工作塔、地道、下麦坑以及立筒库.     

Gaschromatographische und dünnschichtchromatographische Untersuchung von Fettsäuren: Die Anwendung von gepackten Glaskapillarsäulen zur Trennung von cis- und trans-ungesättigten Fettsäuren

Gas Chromatographic and Thin-Layer Chromatographic Studies on Fatty Acids: The Application of Packed Glass Capillary Columns for Separation of cis- and trans-Unsaturated Fatty Acids from Saturated Fatty Acids Packed glass capillary columns were used for the quantitative determination of trans- and cis-unsaturated fatty acids in the presence of saturated fatty acids by gas chromatography. The fatty acids were analyzed as methyl esters after interesterification of the triglyceride samples. The conversion of glyceryl esters of fatty acids into methyl esters could be followed using short GC columns and by thin-layer chromatography.     

Remotely sensed indicators of habitat heterogeneity: Use of synthetic aperture radar in mapping vegetation structure and bird habitat

An integrated remote sensing/field ecology project linked the use of synthetic aperture radar (SAR) and aerial photography to studies of landscape spatial heterogeneity and bird community ecology. P-, L-, and C-band SAR data, collected over a section of Kakadu National Park in Australia's Northern Territory during the Joint NASA/Australia DC-8 data acquisition campaign, were analyzed in light of field data integrating vegetation structure and floristics with bird abundances across a heterogeneous study site. Results indicate that SAR data are able to discern structural differences relevant to bird habitat quality within floristically homogeneous stands, while multispectral sensors successfully identified floristic differences among habitat types. Simplifying indices of bird diversity showed ambiguous changes across the site; however, the abundances of individual species were observed to change significantly across both floristic and structural gradients. These results suggest that efforts to map bird diversity should focus on species-specific habitat relationships and that some measure of vegetation structure is needed to understand bird habitat. The approach employed here advances the use of SAR data in the three-dimensional mapping of animal habitats from remotely sensed data, and extends current capabilities for mapping and modeling large-scale patterns in the distribution of biological diversity.     

Influence of High-Permeability Layers for Enhancing Landfill Gas Capture and Reducing Fugitive Methane Emissions from Landfills

Gas collection systems of various designs have been used to control landfill gas emissions, which can be problematic, particularly before installation of final landfill covers. In this work, an innovative gas collection system that includes a permeable layer near the top surface of landfills was evaluated for enhancing capture of landfill gas and reducing fugitive methane emissions. A computational model that accounts for advective and diffusive fluxes of multiple gas components was used to evaluate the efficiency of this new design for intermediate landfill covers. The utility of the high-permeability gas-conductive layer was illustrated for several conditions of interest including varying refuse permeability, varying degrees of permeability anisotropy, and temporal atmospheric pressure changes. Simulations showed that the permeable layer decreased methane emissions by 43% when the horizontal to vertical permeability ratio for refuse was kh/kv = 3 and the domain average kh = 3×10?12?m2, while reductions in methane emissions decreased to 17% for the same anisotropy but with kh = 10?11?m2. With this design, barometric pressure changes did not significantly affect oxygen intrusion or methane emission rates.     

Optical properties and local atomic order in non hydrogenated amorphous silicon carbonitride films

Non hydrogenated a-SiCN films have been prepared by Radio Frequency (RF)reactive sputtering of a SiC target in an Ar + N₂ plasma. The N content has been varied from 0 to 66 at.% of the sample composition. The structural and chemical orders have been investigated by X ray diffraction and X ray Absorption Near Edge Spectroscopy. The optical absorption properties of the films have been studied by transmittance measurements and by ellipsometry. A particular attention has been paid to the relation between the local order and the complex dielectric function. It has been shown that the atomic Short Range Order (SRO) rules the optical absorption while the index of refraction is dominated by the Medium Range Order (MRO). The as deposited samples have an heterogeneous microstructure containing zones where mixed tetrahedra Si (C_1–x N _x )₄ have been formed contiguously with other zones inside of which the basic SiC₄ and SiN₄ tetrahedra of the carbide and nitride are already present. The optical absorption edges of the SiCN deposits, remain close to the one of a-SiC, up to about 50% of nitrogen. The absence of hydrogen in a sample containing less than 1% of N allowed the study of the nitrogen induced relaxation of the network during heating treatements at 1200°C. The crystallization temperature of a-SiC is increased of about 200° and N atoms are located in substitution sites with a four fold coordinence. The optical gap widens after the annealing at 1200°C, from 1.6 to 2.4 ev which last value is in the same range that the gaps of non annealed a-SiC : H materials containing about 10% of hydrogen.     

Prediction of psychological symptoms under high-risk psychosocial circumstances: Life events, social support, and symptom specificity.

Examined life events, perceived dimensions of events, and social support in predicting different types of psychological symptoms (e.g., depressive and anxiety symptoms), all within the context of a specific high-risk situation for psychological distress: the final-examination period for university students (N?=?167). Ss were administered a battery of tests that included the State-Trait Anxiety Inventory and the Beck Depression Inventory. Results indicate that (a) certain dimensions of events and particular aspects of social support are directly related to symptoms manifested during final-examination stress, (b) perceived dimensions of events and social support interactively predict symptoms, and (c) depressive symptoms—in contrast to general distress or anxiety symptoms—are relatively specifically a function of events and support. Findings are discussed within the context of existing research; the implications for extending similar strategies employing other high-risk psychosocial circumstances are advanced. (59 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using the Climate Assessment Tool (CAT) in U.S. EPA BASINS integrated modeling system to assess watershed vulnerability to climate change.

During the last century, much of the United States experienced warming temperatures and changes in amount and intensity of precipitation. Changes in future climate conditions present additional risk to water and watershed managers. The most recent release of U.S. EPA's BASINS watershed modeling system includes a Climate Assessment Tool (CAT) that provides new capabilities for assessing impacts of climate change on water resources. The BASINS CAT provides users with the ability to modify historical climate and conduct systematic sensitivity analyses of specific hydrologic and water quality endpoints to changes in climate using the BASINS models (Hydrologic Simulation Program - FORTRAN (HSPF)). These capabilities are well suited for addressing questions about the potential impacts of climate change on key hydrologic and water quality goals using the watershed scale at which most important planning decisions are made. This paper discusses the concepts that motivated the CAT development effort; the resulting capabilities incorporated into BASINS CAT; and the opportunities that result from integrating climate assessment capabilities into a comprehensive watershed water quality modeling system.