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11.
结构面长期强度的确定对工程岩体长期安全稳定性评价具有重要意义。在对水泥砂浆结构面试件分别进行了不同法向应力条件的剪切应力分级剪切蠕变试验和循环剪切应力松弛试验的基础上,分别利用过渡蠕变法、应力-应变等时曲线法和应力松弛法对结构面的长期强度进行了求解。结果表明:过渡蠕变法确定的长期强度精度依赖于蠕变试验中加载应力级的划分;等时曲线法将长期强度值视为考虑时效作用的屈服强度值,结果偏保守;应力松弛法考虑了循环加载条件应力松弛的终止条件和长期强度之间的关系求得,结果合理明确。该研究对考虑时效作用的工程岩体安全稳定性支护提供设计依据。 相似文献
12.
A stain-based screening method was developed to screen different catalyst coatings for their germicidal activity. A Baclight dead/live bacteria viability kit (invitrogen, molecular probes) was used for staining the cell. The screening was carried out following a standard procedure. This included loading cell suspension to solid surface and maintaining contact for 30 min, then staining with a mixture containing dyes. The stained cells were observed using an epifluorescent microscope and photographed with a CCD camera under UV. Metal-doped TiO2 coatings on AI plates were prepared and tested for non-UV germicidal activity without using UV. It was tested using model microorganisms such as Bakers Yeast (Saccharomyces cerevisiae), Bacillus subtilis, Pseudomonas putida, and Escherichia coli. On the basis of the germicidal activity of catalyst and the degree of damage caused to the cells, the stained cells may appear green (viable), green with red or yellow nuclei and yellow (compromised) or red (nonviable). According to their stained color, cells were counted to calculate the percentage of dead, live, and compromised cells. Compromised cells are cells that grow very slowly after reculturing indicating a degree of reversible cell damage. Screening the germicidal activity using this staining method is accurate and efficient, and requires less time than the culture-based method. A modification to the procedure for measuring germicidal activity of rough surfaces or fibrous coatings was developed. Both TiO2 and metal-doped TiO2 (Ag, Pt, Au, Cu) possess non-UV based germicidal activity. The germicidal activity of TiO2 was found to be related with its wetting property and can be improved by UV irradiation before testing. It is not greatly affected by contact time, indicating a fast acting germicidal activity. 相似文献
13.
德兴-黄山断裂带及其邻区的地质研究进展 总被引:3,自引:0,他引:3
德兴-黄山断裂带以往都被认为是由伏川蛇绿岩套、赣东北蛇绿岩带组成的中元新古代蛇绿混杂岩带,代表扬子板块与华夏板块拼贴的北西界缝合线。近年来的地质调查表明,扬子和华夏两板块拼贴带大致介于宜丰-景德镇断裂、萍乡-广丰-江山断裂带之间,是一个多期碰撞造山带,称江南复合混杂岩带,而德兴-黄山断裂带则不具板块边界性质,仅是该混杂岩带内的一条分隔次级构造单元的边界断裂,总体呈NNE向展布,包括赣东北蛇绿混杂岩和一系列NNE向韧性剪切带和脆性断裂。伏川蛇绿岩和赣东北蛇绿岩走向上无法连接,分别代表江南复合混杂岩带内不同拉分小洋盆的沉积-构造混杂产物。本文对断裂带及其邻区前震旦纪地层重新划分进行了论述。 相似文献
14.
James E. Mitchell 《Journal of the American Water Resources Association》1993,29(5):863-870
ABSTRACT: In geohydrology, three-dimensional surfaces are typically represented as a series of contours. Water levels, saturated thickness, precipitation, and geological formation boundaries are a few examples of this practice. These surfaces start as point measurements that are then analyzed to interpolate between the known point measurements. This first step typically creates a raster or a set of grid points. In modeling, subsequent processing uses these to represent the shape of a surface. For display, they are usually converted to contour lines. Unfortunately, in many field applications, the (x, y) location on the earth's surface is much less confidently known than the data in the z dimension. To test the influence of (x, y) locational accuracy on z dimension point predictions and their resulting contours, a Monte Carlo study was performed on water level data from northwestern Kansas. Four levels of (x, y) uncertainty were tested ranging in accuracy from one arc degree-minute (± 2384 feet in the x dimension and ± 3036 feet in the y dimension) to Global Positioning Systems (GPS) accuracy (± 20 feet for relatively low cost systems). These span the range of common levels of locational uncertainty in data available to hydrologists in the United States. This work examines the influence that locational uncertainty can have on both point predictions and contour lines. Results indicate that overall mean error exhibits a small sensitivity to locational uncertainty. However, measures of spread and maximum errors in the z domain are greatly affected. In practical application, this implies that estimates over large regions should be asymptotically consistent. However, local errors in z can be quite large and increase with (x, y) uncertainty. 相似文献
15.
Photolysis of some polycyclic aromatic hydrocarbons (PAHs) on soil surfaces may play an important role in the fate of PAHs in the environment.Photolysis of PAHs on soil surfaces under UV irradiation was investigated.The effects of oxygen,irradiation intensity and soil moisture on the degradation of the three PAHs were observed.The results showed that oxygen,soil moisture and irradiation intensity enhanced the photolysis of the three PAHs on soil surfaces.The degradation of the three PAHs on soil surfaces is related to their absorption spectra and the oxidation-half-wave potential.The photolysis of PAHs on soil surfaces in the presence of oxygen followed pseudo first-order kinetics.The photolysis half-lives ranged from 37.87 days for benzo[a]pyrene to 58.73 days for phenanthrene.The results indicate that photolysis is a successful way to remediate PAHs-contaminated soils. 相似文献
16.
The pollutant loads of surface runoff in an urban tourist area have been investigated for two years in the Wuhan City Zoo, China. Eight sampling sites, including two woodlands, three animal yards, two roofs and one road, were selected for sampling and study. The results indicate that pollutants ranked in a predictable order of decreasing load (e.g. animal yard〉roof〉woodland〉road), with animal yards acting as the key pollution source in the zoo. Pollutants were transported mainly by particulate form in runoff. Particulate nitrogen and particulate phosphorous accounted on average for 61%, 78% of total pollutant, respectively, over 13 monitored rainfall events. These results indicate the treatment practices should be implemented to improve particulate nutrient removal. Analysis of the M(V) curve indicate that no first flush effect existed in the surface runoff from pervious areas (e.g. woodland, animal ground yard), whereas a first flush effect was evident in runoff from impervious surfaces (e.g. animal cement yard, roof, road). 相似文献
17.
We propose a hierarchical modeling approach for explaining a collection of spatially referenced time series of extreme values.
We assume that the observations follow generalized extreme value (GEV) distributions whose locations and scales are jointly
spatially dependent where the dependence is captured using multivariate Markov random field models specified through coregionalization.
In addition, there is temporal dependence in the locations. There are various ways to provide appropriate specifications;
we consider four choices. The models can be fitted using a Markov Chain Monte Carlo (MCMC) algorithm to enable inference for
parameters and to provide spatio–temporal predictions. We fit the models to a set of gridded interpolated precipitation data
collected over a 50-year period for the Cape Floristic Region in South Africa, summarizing results for what appears to be
the best choice of model.
相似文献
Alan E. GelfandEmail: |
18.
19.
Nilkanth N. Shinde 《International Journal of Sustainable Engineering》2016,9(3):189-196
The paper explores the experimental results of the prototype compound parabolic trough made of mild steel and silver-coated selective surface. This prototype has been tested with top cover. The performance of the collector has been evaluated with two kinds of receivers coated with three types of black coatings. First receiver is of copper coated with black copper, second receiver is of mild steel coated with black copper and third receiver is of copper coated with black zinc. From actual field experiments, it has been observed that the efficiency of the system achieved with copper receiver coated with black copper is comparatively higher than the other two types of receivers. A simple regression analysis is used to correlate the thermal performance parameters of the system. 相似文献
20.
Rosa W. Wu Tom Harner Miriam L. Diamond 《Atmospheric environment (Oxford, England : 1994)》2008,42(24):6131-6143
Surface films on impervious surfaces mediate the fate of organic contaminants in urban areas. Using sheltered 3-mm diameter glass beads as a surrogate impervious urban surface, studies in downtown Toronto showed that surface films developed at a consistent rate of 1.6–2.6 nm day−1. Linear film growth was observed up to and including the last day of three studies of 89-, 273-, and 84-day duration. Total PCB content (sum of 15 PCB congeners) also increased linearly, at a similar rate as the surface film. A complementary study using unsheltered beads showed that up to 80% of film mass and PCB content were removed by film wash-off during rain events. The film growth rate on beads exposed at a rural site, 200 km northeast of Toronto, was 12–20 times lower with PCB burdens that were 7–22 times lower compared to Toronto. Based on these findings, it is estimated that approximately 56–226 g of PCBs are captured by a 70 nm thick film covering just the horizontal surface area of Toronto. This is a substantial quantity of PCB that is available for rapid surface–air exchange and wash-off. 相似文献