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31.
E. Karimzade M. Sharifzadeh H. R. Zarei K. Shahriar M. Cheraghi Seifabad 《Arabian Journal of Geosciences》2017,10(9):206
Groundwater flow is a major issue in underground opening in fractured rocks. Because of finding the fracture connectivity, contribution of each fracture in flow, and fracture connectivity to excavation boundary, the prediction of water flow to underground excavations is difficult. Simulation of fracture characteristics and spatial distribution is necessary to obtain realistic estimation of inflow quantity to tunnel and underground excavations. In this research, a computer code for three-dimensional discrete fracture network modeling of water inflow into underground excavations was developed. In this code, the fractures are simulated as ellipsoid while geometrical properties of the fractures are reproduced using a stochastic method. Properties such as the size, orientation, and density of the fractures are modeled by their respective probability distributions, which are obtained from field measurements. According to the fracture condition, the flow paths in rock mass are determined. The flow paths are considered as channels with rectangular sections in which channel width and fracture aperture determine geometry of channel section. Inflow into excavation is predicted ignoring matrix permeability and considering the hydrogeological conditions. To verify presented model, simulation results were compared to a part of the Cheshmeh-Roozieh water transfer tunnel in Iran. The results obtained from this research are in good agreement with the field data. Thus, the average of the predicted inflow has just an approximation error equal to 17.8%, and its standard deviation is 8.6 l/s, which is equal to 21% of the observed value that demonstrates low dispersion of the predicted values. 相似文献
32.
Pure and Applied Geophysics - 相似文献
33.
Anisotropy Effects on Microseismic Event Location 总被引:2,自引:0,他引:2
Seismic anisotropy in sedimentary environments is significant—microseismic waveforms often show strong shear-wave splitting,
with differences reaching 40% between horizontally and vertically-polarized shear-wave velocities. Failure to account for
this anisotropy is shown to result in large microseismic event location errors. A method is presented here for determining
the five elastic parameters of a homogeneous, vertical transverse-isotropic (VTI) model from calibration shot data. The method
can also use data from mining-induced seismic events, which are then simultaneously located. This simple model provides a
good fit to arrival times from coal-environment data, and results in dramatic shifts in interpreted event locations. 相似文献
34.
China Ocean Engineering - Conventional design of pier structures is based on the assumption of fully rigid joints. In practice, the real connections are semi-rigid that cause changes in dynamic... 相似文献
35.
Environmental impact assessment of open pit mining in Iran 总被引:2,自引:0,他引:2
Mining is widely regarded as having adverse effects on environment of both magnitude and diversity. Some of these effects
include erosion, formation of sinkhole, biodiversity loss and contamination of groundwater by chemical from the mining process
in general and open-pit mining in particular. As such, a repeatable process to evaluate these effects primarily aims to diminish
them. This paper applies Folchi method to evaluate the impact of open-pit mining in four Iranian mines that lacked previous
geo-environmental assessment. Having key geologic resources, these mines are: Mouteh gold mine, Gol-e-Gohar and Chogart iron
mines, and Sarcheshmeh copper mine. The environmental components can be defined as public health and safety, social relationships,
air and water quality, flora and fauna hence, various impacting factors from the mining activities were estimated for each
environmental component. For this purpose, each impacting factor was first given a magnitude, based solely on the range of
possible scenarios. Thereafter, a matrix of weighted factors was derived to systematically quantify and normalize the effects
of each impacting factor. The overall impact upon each individual environmental component was then calculated by summing the
weighted rates. Here, Folchi method was applied to evaluate those environmental conditions. Based on the acquired results,
the present paper finally concludes that amongst four case histories in Iran, Sarcheshmeh copper mine significantly affects
the environment, with critical level of air pollution there. 相似文献
36.
37.
P. A. Wani O. O. Sunday A. M. Kehinde L. A. Oluwaseyi I. A. Wasiu S. Wahid 《International Journal of Environmental Science and Technology》2018,15(7):1531-1542
Hexavalent chromium [Cr(VI)] is used in various industries, but its improper and uncontrolled discharge contaminates the environment. In order to circumvent chromium toxicity, several physicochemical and biological strategies have been employed. Among biological approach, microbes convert toxic Cr(VI) to less soluble Cr(III) form and hence can be used to detoxify/remove Cr(VI) from contaminated environment. Considering these, present study was designed to assess the effect of chromium reductases and antioxidants secreted by Penibacillus species to detoxify Cr(VI) and concurrently to augment soybean growth. Bacterial strains (MAI1 and MAI2) were identified as Penibacillus sp. using 16S rRNA gene. Penibacillus species reduced Cr(VI) significantly at pH 7. Maximum Cr(VI) was reduced at 50 and 100 µg/ml of Cr(VI) concentrations. Penibacillus sp. also reduced Cr(VI) significantly at 25 and 35 °C as well as 1 g sodium alginate in 1 g polyvinyl alcohol. Bacterial strains reduced Cr(VI) into Cr(III) which were detected as 33 ± 1 and 35 ± 1 µg/ml in supernatant and 67 ± 2.5 and 65 ± 1 µg/ml in cell debris, respectively, after 120 h. Chromium reductase found in cell-free extract reduced almost all Cr(VI) compared to those observed in cell debris. Both malondialdehyde and antioxidant levels were increased with gradual increase in Cr(VI) concentration. Penibacillus species inoculated soybean plants had better growth and photosynthetic pigments under Cr(VI) stress. 相似文献
38.
Shahriar Negahdaripour Caroline Barufaldi Ali Khamene 《Oceanic Engineering, IEEE Journal of》2006,31(3):533-550
Estimating the relative positions and (or) trajectory of a camera from video images is a fundamental problem in motion vision. Of special relevance is the closed-form solution for planar scenes, for processing fly-over imagery from airborne and underwater robotics platforms, automated airplane landing utilizing runway landmarks, photomosaicing, etc. However, the method's robustness can break down in certain scenarios, e.g., due to inherent translation-rotation ambiguity of visual motion with short baselines and narrow field of view. The robustness can be improved by devising methods that compute a smaller set of motion parameters, utilizing other sensors to measure the remaining components. This paper addressed key issues in six degrees of freedom positioning from fly-over imagery by integrating vision with rotational angle sensors. First, we propose and utilize robust closed-form solutions for estimating the motion and orientation of a planar surface from the image flow variations up to first order, given measurements of pitch and roll motions. We also describe a calibration technique to enable the integration of angle sensor and visual measurements. Next, an error analysis enables us to evaluate the impact of inaccurate pitch and roll measurements on the estimates from the new closed-form solutions. Finally, the performance of our new methods and the integrated positioning system are evaluated in various experiments with synthetic and real data 相似文献
39.
On retrieving patterns in environmental sensor data 总被引:1,自引:0,他引:1
As many sensor networks are currently being deployed for environmental monitoring, there is a growing need to develop systems
and applications for managing, processing and retrieving massive amounts of data generated from those networks. In this research,
a query answering system with pattern mining techniques is investigated specifically for marine sensor data. We consider three
applications of pattern mining: similar pattern search, predictive query and query by clustering. In pattern mining for query
answering, we adopt the dynamic time warping (DTW) method for similarity measurement. We also propose the use of a query relaxation
approach that recommends users change parameters of a given query to get an answer. Finally, we show implementation results
of pattern query answering in a marine sensor network deployed in the South East of Tasmania, Australia. Pattern query answering
system benefits in accessing and discovering knowledge from sensor data for decision making purposes. 相似文献
40.
Omran Frihy Wahid Moufaddal Essam Deabes Essam El Din Helmy 《Arabian Journal of Geosciences》2016,9(14):637
The present study is the first attempt in Egypt to assess feasibility of using of dredging material from Damietta Harbor in the northwestern Nile Delta for erosion control. The study also provides an economic evaluation for the shoreline management alternatives selected to mitigate for the effects of coastal erosion at two pilot eroding areas (namely, A and B) located near the Damietta Harbor. Results of compatibility analysis reveal that the dredging material is fairly compatible with the native sand of the nearby eroding beaches. In addition to soft nourishment by dredged sand, other types of coastal engineering measures which are often used in erosion management area were also evaluated as alternatives for erosion control and mitigation solution. Economic feasibility assessment by means of cost-benefit analysis of direct and indirect items has been carried out to facilitate comparison between these alternatives. Analysis of alternatives has been also supported by other criteria to select the cost-effective and environmentally acceptable option to protect the eroding pilot areas. These criteria include the high total cost paid for maintenance of the Damietta Harbor channel with no use, anticipated impacts on the littoral system, sustainability, future plans for protection of the existing coastlines, and lessons learned from previous shore protection works in the Nile Delta. The final selection of the best viable alternative indicates that the procedure of beach nourishment is the most appropriate form for protection area A, while a combination of groins and sand nourishment is more relevant for area B. In any case, material dredged from the navigation approach of the Damietta Harbor should be utilized as a borrow material in the nourishment schemes and excluding use of the terrestrial sources. 相似文献