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61.
An Integrated Study of the Dynamics of Electromagnetic and Acoustic Regimes During Failure of Complex Macrosystems Using Rock Blocks 总被引:1,自引:0,他引:1
Kamel Baddari Anatoly D. Frolov Victor Tourtchine Fayçal Rahmoune 《Rock Mechanics and Rock Engineering》2011,44(3):269-280
The development of the failure process in complex macrosystems using large rock samples subjected to biaxial compression has
been studied by means of electromagnetic radiation (EMR) and acoustic emission (AE). In order to increase the stage of macrofailure
development, a special procedure of rock loading was used to reveal regularities of nucleation and evolution of electromagnetic
and acoustic structures. The synchronised measurements of EMR and AE allowed the control of the stress–strain state in the
rocks and the structural developments of fracturing. Non-homogeneous distribution of the rock spatial crystalline structure
subject to load leads to a mosaic distribution of EMR and AE characteristics. As a result, the crack scale effect may be observed
in the EMR and AE structure behaviours. The EMR and AE following the failure at different levels behave differently according
to the difference in the scale and type of cracks. Intense high-frequency EMR pulses were recorded during the initial stage
of microcrack generation occurring prior to major failure of material. This was not the case for AE. The nucleation and development
of the macroscopic progressive failure evolution caused an alternation in energetic and frequencial properties of electromagnetic
and acoustic events. It has been detected that the tensile cracks were more efficient than shear cracks in capacity of EMR
generation. The analysis of self potentials allowed reaching the maximum of registered anomalous variations in the stage of
microcracking interaction. This stage showed an increase in the EMR activity, which implies the nucleation of microcracks
in various regions of rock interfaces. The gradual accumulation of these defects led to weakening some parts of the rock along
with a disintegration of electric anomalies, increase of AE and a significant fluctuation in the rate of EMR. When crack concentration
attains its critical value, which results in the formation of dangerous macroscopic failure of higher level, AE shows an intense
activity as well as an EMR lower frequency. The hierarchical development of rock failure using the ratio of the average crack
size and the mean distance between cracks as a statistical concentration criterion is used to control the boundary of the
transition from small dispersed cracks accumulation to gradual crack merger and the formation of the main macrofailure. These
results could be transferred into larger scale levels to forecast dynamic events in the earth crust. 相似文献
62.
Ahmed Aly Kamel 《Celestial Mechanics and Dynamical Astronomy》1975,12(4):425-438
Ignoring luni-solar perturbations, analytical solution for longitude deviation of the ‘stroboscopic’ mean center of 24-h satellites ground trace in the neighborhood of a prespecified station is obtained. The initial semimajor axis for two-maneuver east-west stationkeeping is then deduced. Finally, the luni-solar long and short period effects on this initial semimajor axis are discussed. 相似文献
63.
We extend the construction of the Jupiter-Saturn theory to include all the terms up to the seventh order in the masses. The Hori-Lie transformation technique is employed. The Jacobian coordinates are adopted and the theory is expressed in terms of the canonical non-singular variables of H. Poincaré. 相似文献
64.
In this part we find out the 24 equations of secular perturbation equations for the subsystem J-S-U-N. The solution of these equations by the Lagrange-Laplace procedure and the Eigen value Eigen vector is analysed. Also we refer to Hurwitz theorem to test stability. 相似文献
65.
Osman M. Kamel 《Earth, Moon, and Planets》1996,74(1):1-6
We present a literal approach to evaluate –s
necessary for the construction of high order planetary theories. This approach is valid to be applied on very large scale digital computers with standard Poisson series programs, for high order and high degree planetary theories. We apply the method of symbolic differential operators for single variable functions, and the binomial theorem expansions, for the evaluation of –s
. We utilize Laplace coefficients and its derivatives to carry out the development, without dealing with Newcomb operators or Hansen's coefficients. 相似文献
66.
A solution of the Uranus-Neptune planetary canonical equations of motion through the Von Zeipel technique is presented. A unique determinging function which depends upon mixed canonical variables, reduces the 12 critical terms of the Hamiltonian to the set of its secular terms. The Poincaré canonical variables are used. We refer to a common fixed plane, and apply the Jacobi-Radau set of origins. In our expansion we neglected terms of power higher than the fourth with respect to the eccentricities and sines of the inclinations. 相似文献
67.
In this part we obtain the expression for –s
by the application of Smart's method, which involves Taylor's theorem for functions of several variables. We neglected terms of power higher than the fourth with respect to eccentricities and tangents of inclinations. 相似文献
68.
In this paper, a pan-sharpening method, using non-subsampled contourlet transform (NSCT) and the theory of compressive sensing (CS), is proposed. The NSCT is used for sparse image representation to perform a multiscale and directional decomposition of source images in order to express their detail and express the sparsity of their high frequency. The CS is used to merge the multispectral (MS) and panchromatic (pan) images from partial random measurements. Two different fusion rules are then applied. The final pan-sharpened image is obtained by inverse NSCT. Experimental results show the efficiency of the proposed method, compared with pan sharpening based on standard NSCT, in terms of visual quality and objective assessment. Moreover, the proposed technique is very effective when the storage and transmission bandwidth are limited. 相似文献
69.
Siwar Kammoun Viviana Re Rim Trabelsi Kamel Zouari Salvatore Daniele 《Hydrogeology Journal》2018,26(8):2575-2594
The Grombalia aquifer (NE Tunisia) is an example of an important source of water supply for regional and national development, where the weak controls over abstraction, fertilizer application and waste disposal, coupled with limited knowledge of aquifer dynamics, is causing aquifer over-exploitation and water quality degradation. Assessing the key role of groundwater in water-resources security is therefore of paramount importance to support new actions to preserve water quality and quantity in the long-run. This study presents one of the first investigations targeted at a complete assessment of aquifer dynamics in the Grombalia aquifer. A multi-tracer hydrogeochemical and isotopic (δ2H, δ18O and 3H) approach was used to study the influence of seasonal variation on piezometric levels, chemical and isotopic compositions, and groundwater recharge. A total of 116 samples were collected from private wells and boreholes during three periods in a 1 year monitoring campaign (February–March 2014, September 2014 and February 2015). Results revealed the overall unsuitability of groundwater for drinking and irrigation purposes (NO3?>?50 mg/L in 51% of the wells; EC >1,000 μS/cm in 99% of the wells). Isotopic balance coupled to piezometric investigation indicated the contribution of the shallow aquifer to deep groundwater recharge. The study also revealed the weakness of ‘business as usual’ management practices, highlighting possible solutions to tackle water-related challenges in the Grombalia region, where climate change, population growth and intensive agricultural activities have generated a large gap between demand and available water reserves, hence becoming a possible driver for social insecurity. 相似文献
70.
Samir Kamel 《Arabian Journal of Geosciences》2013,6(6):2103-2117
The shallow Plio-Quaternary (PQ) water table, present over almost the whole Djerid and Chott El Gharsa basins (southern Tunisia), is used as a complement of oases irrigation, especially in summer season. The simplicity of the Plio-Quaternary lithology is confronted to the complexity of the mineralisation mechanisms and the water origin in this aquifer. An approach combining the use of water-dissolved chemical species and isotopic contents has been used to better understand the PQ behaviour under severe increasing exploitation and to determinate the origin of its different water bodies. In southern Tunisia, the aquifer system is composed of the upper unconfined PQ aquifer, the intermediate semi-confined/confined Complexe Terminal (CT) and the deeper confined Continental Intercalaire (CI). Chemical analyses highlighted an origin of mineralisation in close relationship to the dissolution of both sulphated salts (MgSO4 and Na2SO4) and chlorinated salts (NaCl and MgCl) abundant in the surface and subsurface gypsum crust. Positive correlations between gypsum anhydrite, mirabilite, thenardite and halite saturation indexes with respective mineral species, confirm evaporites dissolutions. Isotopic data showed that in addition of sporadic rainfall events, there is a contribution from the CI and the CT Saharan groundwaters, recharging the PQ aquifer in the study area. Return flow irrigation is partly affected by evaporation, before recharging the shallow aquifer, in oases limits. 相似文献