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Sofiane Khelifa Bachir Gourine Habib Taibi Hicham Dekkiche 《Arabian Journal of Geosciences》2018,11(12):329
Several methods of time series analysis and forecasting require data at regular time intervals. But in space geodesy, most datasets are often full of gaps, resulting for example from hardware issue, modification of models, change of analysis strategy, and local geophysical phenomenon. The purpose of this paper is to fill the gaps in time series of space-geodetic station positions, by the use of two different approaches: the iterative singular spectrum analysis (ISSA) and the generalized regression neural network (GRNN). In order to test the efficiency of the proposed methods to properly process missing data, we created synthetic gaps at random points in regular time series (i.e., time series without gaps) of Global Positioning System (GPS) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) station positions with data span longer than 4 years. For each analyzed time series, we created gaps (by removing successive points) of different lengths ranging from 1 to 52 gaps, and then, we filled these gaps by ISSA, GRNN, and other classical methods of interpolation such as nearest neighbor, linear, and cubic interpolations.The interpolation precision was evaluated by the technique of cross-validation which compares the estimated values with the original data. After several simulations on position time series with different lengths, we found that the ISSA technique provides better results in terms of root mean square error. 相似文献
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Three-dimensional numerical and analytical study of horizontal group of square anchor plates in sand
Hicham Mokhbi Mekki Mellas Abdelhak Mabrouki Jean-Michel Pereira 《Acta Geotechnica》2018,13(1):159-174
In this paper, numerical and analytical methods are used to evaluate the ultimate pullout capacity of a group of square anchor plates in row or square configurations, installed horizontally in dense sand. The elasto-plastic numerical study of square anchor plates is carried out using three-dimensional finite element analysis. The soil is modeled by an elasto-plastic model with a Mohr–Coulomb yield criterion. An analytical method based on a simplified three-dimensional failure mechanism is developed in this study. The interference effect is evaluated by group efficiency η, defined as the ratio of the ultimate pullout capacity of group of N anchor plates to that of a single isolated plate multiplied by number of plates. The variation of the group efficiency η was computed with respect to change in the spacing between plates. Results of the analyses show that the spacing between the plates, the internal friction angle of soil and the installation depth are the most important parameters influencing the group efficiency. New equations are developed in this study to evaluate the group efficiency of square anchor plates embedded horizontally in sand at shallow depth (H = 4B). The results obtained by numerical and analytical solutions are in excellent agreement. 相似文献
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Geophysical data sets are growing at an ever-increasing rate, requiring computationally efficient data selection(thinning)methods to preserve essential information. Satellites, such as Wind Sat, provide large data sets for assessing the accuracy and computational efficiency of data selection techniques. A new data thinning technique, based on support vector regression(SVR), is developed and tested. To manage large on-line satellite data streams, observations from Wind Sat are formed into subsets by Voronoi tessellation and then each is thinned by SVR(TSVR). Three experiments are performed. The first confirms the viability of TSVR for a relatively small sample, comparing it to several commonly used data thinning methods(random selection, averaging and Barnes filtering), producing a 10% thinning rate(90% data reduction), low mean absolute errors(MAE) and large correlations with the original data. A second experiment, using a larger dataset, shows TSVR retrievals with MAE < 1 m s-1and correlations 0.98. TSVR was an order of magnitude faster than the commonly used thinning methods. A third experiment applies a two-stage pipeline to TSVR, to accommodate online data. The pipeline subsets reconstruct the wind field with the same accuracy as the second experiment, is an order of magnitude faster than the nonpipeline TSVR. Therefore, pipeline TSVR is two orders of magnitude faster than commonly used thinning methods that ingest the entire data set. This study demonstrates that TSVR pipeline thinning is an accurate and computationally efficient alternative to commonly used data selection techniques. 相似文献
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The estimation of wave transmission across the fractured rock masses is of great importance for rock engineers to assess the stability of rock slopes in open pit mines. Presence of fault, as a major discontinuity, in the jointed rock mass can significantly impact on the peak particle velocity and transmission of blast waves, particularly where a fault contains a thick infilling with weak mechanical properties. This paper aims to study the effect of fault properties on transmission of blasting waves using the distinct element method. First, a validation study was carried out on the wave transmission across a single joint and different rock mediums through undertaking a comparative study against analytical models. Then, the transmission of blast wave across a fault with thick infilling in the Golgohar iron mine, Iran, was numerically studied, and the results were compared with the field measurements. The blast wave was numerically simulated using a hybrid finite element and finite difference code which then the outcome was used as the input for the distinct element method analysis. The measured uplift of hanging wall, as a result of wave transmission across the fault, in the numerical model agrees well with the recorded field measurement. Finally, the validated numerical model was used to study the effect of fault properties on wave transmission. It was found that the fault inclination angle is the most effective parameter on the peak particle velocity and uplift. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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A. Aryanasl J. Ghodousi R. Arjmandi N. Mansouri 《International Journal of Environmental Science and Technology》2016,13(5):1269-1276
“Environmental issues” along with raising awareness of people about the value of ecological systems and the growth of environmentalism have affected businesses systems and models by introducing new concepts and models for business such as sustainable business model. European Foundation for Quality Management (EFQM) Excellence Model provides a clear path for a company to follow in order to achieve its planned results which can be called sustainable business. The purpose of this study is to explore whether the mentioned model is suitable for the businesses that are based on cleaner production and sustainable business models. The method used in this study is an explorative one based on the literature review and exploration of the adaptability of EFQM Excellence Model (2013), including its fundamental concepts and its criteria, to eight archetypes of sustainable business. The results showed that out of eight fundamental concepts of this model, four are aligned with sustainable business model and four need redefining. Moreover, it was found that environmentalism should be added to the five enablers of the model, and results criteria of it needed to be restructured and redefined. In conclusion, it was shown that despite adoptability of the fundamental concepts of EFQM Excellence Model, there were some lacking criteria for adapting them to sustainable business model. Having this in mind, a modified type of model with the new defined criteria was proposed in this study. 相似文献
7.
F. Atabi F. Moattar N. Mansouri A. A. Alesheikh S. A. H. Mirzahosseini 《International Journal of Environmental Science and Technology》2013,10(2):283-294
This study investigates the variations of benzene concentration levels in district 1, situated in the north part of Tehran, capital of Iran. Thirty-three stations in five categories, namely roadsides, busy roads, residential areas, traffic intersections, and the vicinity of gas stations, were monitored during the rush hours in the afternoon once a week over a period of 1 year. Accordingly, benzene concentration levels were measured and predicted by inverse distance weight model. The recorded benzene concentration levels were then compared with those reported in other parts of the world. According to the results, the annual concentration levels of benzene was 13.85 ppb for roads with heavy traffic flow, 14.98 ppb for traffic intersections, 29.01 ppb for the vicinity of the gas stations, 3.26 ppb for residential areas, and 9.97 ppb for roadsides. The concentration of benzene in the vicinity of the gas station sampling point was higher than in the other stations, and at all locations was found to be so much more than the standard concentration levels (1.56 ppb) prescribed by Environmental Protection Agency for the ambient air quality. The results of the study revealed that the benzene concentration levels in Tehran are distinctly more than its standard level. This is mainly attributed to the poor quality of fuel and lack of a standard system for controlling petrol vapors in the gas stations. 相似文献
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This research work has an objective to determine the effective variables in socioeconomic category of Integrated Water Resources Management for Saf-Saf river basin characterized by fast growing demand of urban and rural populations and the demand of economic sectors including industry and agriculture. In this paper, the artificial neural network models were used to model and predict the relationship between water resources mobilization and socioeconomic variables in the Saf-Saf river basin. The study area chosen is Saf-Saf river basin and real data were collected from 30 municipalities for reference year 2010. The results indicate that the feed-forward multilayer perceptron models with back-propagation are useful tools to define and prioritize the most effective variable on water resources mobilization and use. The model evaluation shows that the correlation coefficients are more than 94 % for training, verification, and testing data. The model aims to link the water resources mobilization and driving forces variables with the objective to strengthen the Integrated Water Resources Management approach. 相似文献
9.
Hakim Khelfaoui Hicham Chaffai Jacques Mudry Azzedine Hani 《Arabian Journal of Geosciences》2013,6(11):4517-4527
The continuous increase of industrial activities in the area of Berrahal (northeast of Algeria) resulted in an increase of waste disposal, inducing environmental pollution and contamination of groundwater. Available data on groundwater contamination were used to develop a statistical study for contaminated regions and to identify exposure scenarios of pollution. Chemical analysis of the samples shows that water of most wells and drillings is in bad quality or not drinkable, whereas statistical processing of these data by principal component analysis and discriminant factorial analysis suggests that wastewater coming from companies of the industrial park of Berrahal is very rich in organic pollutants (high percentages of BOD5 and NO2 ?) and has high mineralization (has strong concentration in major elements and high electric conductivity); these constitute the main factors of the deterioration of the quality of this water. The considered exposure pathways were drinking water exploited from wells and drillings implanted in this area and its contact with soil (ingestion and dermal contact) that could threaten either humans or wildlife, on site or off site. In addition, groundwater was considered to be a potential risk pathway, especially for the ecosystem of Lake Fetzara and for the aquiferous system. 相似文献
10.
Determination of the origin of mineralization and groundwater salinity in the Adrar region in the southwest of Algeria 
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下载免费PDF全文 KHELFAOUI Hakim DAJBRI Larbi LAKHAL Fatima Zohra CHAFFAI Hicham HANI Azzedine SAYAD Lamine 《地下水科学与工程》2020,8(2):158-171
To some extent, the sedimentary sequence with the largest groundwater reserves in northern Sahara is marked by a certain water table level, regionally known as the "Continental Intercalaire"(CI). "Continental Intercalaire"(CI) refers to "Continental Intercalary" widely distributed among three countries. Algeria, Tunisia and Libya, which have significant potential of water resources. As it is the only water resource relatively easily accessible to the inhabitants of the Sahara, it is widely developed. The physico-chemical characteristics of statistical processing in principal component analysis(PCA) and the chemical phase measurement of groundwater in the unconfined aquifer captured by "Foggaras"(traditional system irrigation composed of well system linked by a horizontal channel from their bases) and the deep drillings located in the study area were accessible. Therefore, there were some favorable conditions for comparing the chemistry of these waters with the standards of potability established by the World Health Organization. Then, the study detected the origin of excessive mineralization and the excessive content of Na, Cl, K, Mg and Ca that originated from the leaching of the clay and carbonate layers of the "Continental Intercalaire". In addition, the enrichment in NO_2~-, NO_3~- and SO_4~(2-) was due to the excessive use of fertilizer in the whole region for shallower Foggaras waters, and this study also showed the dominant chemical facies of groundwater related to the significant abundance of these mineral salts in this thick aquifer horizon. 相似文献