3D Doppler Tomography of the X-Ray Binary System Cygnus X-1 from Spectral Observations in 2007 in the HeII λ 4686 Å Line     

M. I. Agafonov  E. A. Karitskaya  O. I. Sharova  N. G. Bochkarev  S. V. Zharikov  G. Z. Butenko  A. V. Bondar’  M. Yu. Sidorov 《Astronomy Reports》2018,62(2):89-102

The results of a 3D Doppler tomography analysis for the X-ray binary system Cyg X-1 in the HeII λ 4686 Å line are presented. Information about the motions of gaseous flows outside the orbital plane has been obtained for the first time. Line profiles obtained in June 2007 on the 2-m telescope of the Terskol Branch of the Institute of Astronomy (Russia) and on the 2.1-m telescope of the National Astronomical Observatory of Mexico were used. A detailed analysis of these spectral data is presented: the distribution of the data in time, distribution of orbital phases for the projections, comparison of the line profile shapes for the data from two observatories. The geometry of the total transfer function obtained in the reconstruction is considered. The possibility of applying the profiles obtained to realize 3D tomography is justified. The resolution of the constructed 3D tomogram in velocity space is 60 × 60 × 40 km/s for V _x , V _y , V _z . Fifteen cross sections for 15 different V _z values perpendicular to the orbital plane are presented. The intensity distributions corresponding to the velocities of gaseous structures in the binary system are obtained. The reconstruction was realized using the radio-astronomical approach, developed for solving problems in tomography with a limited number of projections.  相似文献   

Fractal dimension of pore space in carbonate samples from Tushka area (Egypt)     

Yi Ding  Andreas Weller  Zeyu Zhang  Mohamed Kassab 《Arabian Journal of Geosciences》2017,10(17):388

To investigate inhomogeneous and porous structures in nature, the concept of fractal dimension was established. This paper briefly introduces the definition and measurement methods of fractal dimension. Three different methods including mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and nitrogen adsorption (BET) were applied to determine the fractal dimensions of the pore space of eight carbonate rock samples taken from West Tushka area, Egypt. In the case of fractal behavior, the capillary pressure P _c and cumulative fraction V _c resulting from MICP are linearly related with a slope of D-3 in a double logarithmic plot with D being the value of fractal dimension. For NMR, the cumulative intensity fraction V _c and relaxation time T ₂ show a linear relation with a slope of 3-D in a double logarithmic plot. Fractal dimension can also be determined by the specific surface area S _por derived from nitrogen adsorption measurements and the effective hydraulic radius. The fractal dimension D shows a linear relation with the logarithm of S _por . The fractal dimension is also used in models of permeability prediction. To consider a more comprehensive data set, another 34 carbonate samples taken from the same study area were integrated in the discussion on BET method and permeability prediction. Most of the 42 rock samples show a good agreement between measured permeability and predicted permeability if the mean surface fractal dimension for each facies is used.  相似文献   

Research on probability integration parameter inversion of mining-induced surface subsidence based on quantum annealing     

Lei Wang  Tao Wei  Nan Li  Shen-shen Chi  Chuang Jiang  Su-yang Fang 《Environmental Earth Sciences》2018,77(21):740

Probability integral method is an official prediction method for mining subsidence in China. However, how to obtain the probability integral method parameters based on the measured data is the premise of realizing the accurate prediction of the probability integral method. Simulated annealing (SA) is an effective nonlinear optimization algorithm that has recently been introduced into the mining subsidence field to obtain the parameters of the probability integration method. To solve the problems of slow convergence speed and easily falling into the local optimal solution in the method of parameters inversion in probability integral method based on SA (MPIPIMSA), the method of parameters inversion in probability integral method based on quantum annealing (MPIPIMQA) is proposed by combining the quantum fluctuation mechanism and simulated annealing theory. The simulation experimental results show that MPIPIMQA is superior to MPIPIMSA in the accuracy and stability of parameters, and MPIPIMQA has a stronger anti-interference ability for local losing observation points, random errors and gross errors in observation data. Finally, the parameters of probability integral method for the 1414(1) working face of the Guqiao Coal Mine in Huainan mining area were obtained by using MPIPIMQA, namely, q?=?0.9916, tanβ?=?1.9277, b?=?0.4190, θ?=?84.3381, S_u = ??7.3715, S_d = ??14.7126, S_l = 59.0695, and S_r = 32.6381, and the fitting error is 106.8863 mm. The research results have important reference values for accurate inversion of probability integral parameters.  相似文献   

Absorption in the H(93–95)<Emphasis Type="Italic">α</Emphasis> and H(78–79)<Emphasis Type="Italic">α</Emphasis> recombination lines in the HII region of the quasar 3C 345     

L. I. Matveyenko  D. A. Graham  J. A. Zensus 《Astronomy Reports》2005,49(4):259-268

Absorption of the synchrotron emission of the quasar 3C 345 in the continuum and H(93–95)α and H(78–79)α radio recombination lines is studied. The upper limit for absorption in the H(93–95)α lines is T_al/T_ac < 0.7%; absorption in the H(78–79)α lines with antenna temperature T_al = 25 mK, linewidth Δf = 5.3 ± 0.08 MHz, and T_al/T_ac ≥ 0.3% has been detected. A correction to the redshift Δz = 0.00135 ± 0.00008 (z = 0.59365) has been determined.  相似文献   

The stress regime in a Rotliegend reservoir of the Northeast German Basin   总被引：2，自引：0，他引：2  

Inga Moeck  Heinz Schandelmeier  Heinz-Gerd Holl 《International Journal of Earth Sciences》2009,98(7):1643-1654

In-situ stresses have significant impact, either positive or negative, on the short and long term behaviour of fractured reservoirs. The knowledge of the stress conditions are therefore important for planning and utilization of man-made geothermal reservoirs. The geothermal field Groß Schönebeck (40 km north of Berlin/Germany) belongs to the key sites in the northeastern German Basin. We present a stress state determination for this Lower Permian (Rotliegend) reservoir by an integrated approach of 3D structural modelling, 3D fault mapping, stress ratio definition based on frictional constraints, and slip-tendency analysis. The results indicate stress ratios of the minimum horizontal stress S _hmin being equal or increasing 0.55 times the amount of the vertical stress S _V (S _hmin ≥ 0.55S _V ) and of the maximum horizontal stress S _Hmax ≤ 0.78–1.00S _V in stress regimes from normal to strike slip faulting. Thus, acting stresses in the 4,100-m deep reservoir are S _V  = 100 MPa, S _hmin = 55 MPa and S _Hmax = 78?100 MPa. Values from hydraulic fracturing support these results. Various fault sets of the reservoir are characterized in terms of their potential to conduct geothermal fluids based on their slip and dilatation tendency. This combined approach can be adopted to any other geothermal site investigation.  相似文献   

Accuracy assessment of near-shore bathymetry information retrieved from Landsat-8 imagery     

Keivan Kabiri 《Earth Science Informatics》2017,10(2):235-245

The improvement in the capabilities of Landsat-8 imagery to retrieve bathymetric information in shallow coastal waters was examined. Landsat-8 images have an additional band named coastal/aerosol, Band 1: 435–451 nm in comparison with former generation of Landsat imagery. The selected Landsat-8 operational land image (OLI) was of Chabahar Bay, located in the southern part of Iran (acquired on February 22, 2014 in calm weather and relatively low turbidity). Accurate and high resolution bathymetric data from the study area, produced by field surveys using a single beam echo-sounder, were selected for calibrating the models and validating the results. Three methods, including traditional linear and ratio transform techniques, as well as a novel proposed integrated method, were used to determine depth values. All possible combinations of the three bands [coastal/aerosol (CB), blue (B), and green (G)] have been considered (11 options) using the traditional linear and ratio transform techniques, together with five model options for the integrated method. The accuracy of each model was assessed by comparing the determined bathymetric information with field measured values. The standard error of the estimates, correlation coefficients (R ² ) for both calibration and validation points, and root mean square errors (RMSE) were calculated for all cases. When compared with the ratio transform method, the method employing linear transformation with a combination of CB, B, and G bands yielded more accurate results (standard error = 1.712 m, R ² _calibration = 0.594, R ² _validation = 0.551, and RMSE =1.80 m). Adding the CB band to the ratio transform methodology also dramatically increased the accuracy of the estimated depths, whereas this increment was not statistically significant when using the linear transform methodology. The integrated transform method in form of Depth = b ₀  + b ₁ X _CB  + b ₂ X _B  + b ₅ ln(R _CB )/ln(R _G ) + b ₆ ln(R _B )/ln(R _G ) yielded the highest accuracy (standard error = 1.634 m, R ² _calibration = 0.634, R ² _validation = 0.595, and RMSE = 1.71 m), where R _i (i = CB, B, or G) refers to atmospherically corrected reflectance values in the i ^th band [X _i  = ln(R _i -R _{deep water})].  相似文献   

The impact of reflection effects on the parameters of the old pre-cataclysmic variables MS Peg and LM Com     

V. V. Shimansky  N. V. Borisov  N. N. Shimanskaya 《Astronomy Reports》2003,47(9):763-776

We have determined the main parameters of the old precataclysmic variable stars MS Peg and LM Com. The radial velocities of the components, reflection effects in the spectra, and light curves of the systems are studied based on model stellar atmospheres subject to external irradiation. Forty-seven moderate-resolution spectra for MS Peg and 57 for LM Com obtained with the 6-m telescope of the Special Astrophysical Observatory are used to derive the refined orbital periods of 0.1736660 days and 0.2586873 days, respectively; the orbital eccentricities do not exceed e=0.04. The mass (M _w =0.49e_⊙) and radius (e _w =0.015R_⊙) of the MS Peg primary calculated using the gravitational redshift correspond to those for a cooling carbon white dwarf with a thin hydrogen envelope. The parameters of the red dwarf (M _r =0.19M_⊙, T_eff=3560 K, R _r =0.18R_⊙) are close to those derived from evolutionary tracks for main-sequence M stars with solar chemical composition. The radius (R _r =0.22R_⊙) and temperature (T_eff=3650 K) of the LM Com secondary exceed theoretical estimates for main-sequence stars with masses of M _r =0.17M_⊙. The luminosity excess of the red dwarf in LM Com can be explained by a prolonged (T>5×10⁶ yrs) relaxation of the M star to its normal state after the binary leaves the common-envelope stage. For both systems, theoretical U, B, V, and R light curves and spectra calculated using the adopted sets of parameters are generally consistent with the observations. This confirms the radiative origin of the hot spots, the unimportance of horizontal radiative transport, and the absence of large-scale velocity fields with high values (V_trans>50 km/s) at the surfaces of the secondaries. Most of the emission lines in the spectra of these objects are formed under conditions close to thermalization, enabling modeling of their pro files in an LTE approximation. A strong λ3905 Å emission line has been identified as the 3s²3p4s 1P⁰-3s²3p² 1S SiI λ3905.52 Å line formed in the atmosphere of the hot spot. The observed intensity can be explained by non-LTE “superionization” of SiI atoms by soft UV radiation from the white dwarf. We suggest a technique for identifying binaries whose cool components are subject to UV irradiation based on observations of λ3905 Å emission in their spectra.  相似文献   

Characteristic scale of heterogeneity of seismically active fault and its manifestation in scaling of earthquake source spectra     

A. A. Gusev 《Doklady Earth Sciences》2016,470(2):1104-1108

Previously, similarity of source spectra of Kamchatka earthquakes with respect to the common corner frequency f_c1 and the expressed deviations from similarity for the second f_c2 and the third f_c3 corner frequencies were revealed. The value of f_c3 reflects the characteristic size L_is of fault surface; correspondingly, L_is ≈ v_rT_is, where v_r is the rupture speed and T_is ≈ 1/f_c3 is characteristic time. The estimates of f_c3 are used for normalizing f_c1 and f_c2. In this way one obtains dimensionless rupture temporal parametres τ₁ and τ₂ and can further study the dependence τ₂ (τ₁). The growth of a rupture is considered as a process of aggregation of elementary fault spots of the size L_is. The dimensionless width of the random front of aggregation is on the order of τ₂. The relationship τ₂ (τ₁) approximately follows power law with exponent β. The estimates of β derived from earthquake populations of Kamchatka, USA and Central Asia (β = 0.35–0.6) agree with values expected from the known Eden’s theory of random aggregation growth and from its generalizations.  相似文献   

Reliability back analysis of shear strength parameters of landslide with three-dimensional upper bound limit analysis theory   总被引：1，自引：1，他引：0  

Lian-Heng Zhao  Shi Zuo  Yu-Liang Lin  Liang Li  Yingbin Zhang 《Landslides》2016,13(4):711-724

It is essential to determine the shear strength parameters c and φ on the sliding surface for stability evaluation and engineering design of a landslide. In this study, a new parameter back analysis method is proposed by combining the 2D/3D upper bound method of limit analysis and reliability theory to accurately determine the shear strength parameters for a 3D slope with a single failure surface. The proposed reliability back analysis method overcomes the shortcomings of the traditional deterministic analysis method of slope stability that cannot take into account the randomness and uncertainty of geotechnical parameters. Based on the reliability theory, two methods were studied: first-order reliability method (implemented by spreadsheet and Matlab, called spreadsheet method and constrained optimization method, respectively, in this paper) and Monte Carlo simulation. The optimized values of c and φ were obtained by establishing only one balance equation with the consideration of the pore water pressure or other complex conditions, which can solve the problem of the back analysis of strength parameters for a single 3D sliding surface condition. The correlation research showed that the negative correlation between c and φ greatly affected the back analysis results, and the reliability index values were conservative without considering such a negative correlation. A case study for the back analysis of shear strength parameters is conducted based on a practical landslide model with a broken line slip surface slope in Zhuquedong village, Luxi town, Xiangxi County, Hunan Province, China, and a suggestion for the selection of landslide cross section is presented. The results show that the back analysis results determined by the reliability theory coincide well with the survey and experimental results. The proposed method is found to be more accurate and effective in determining the values of shear parameters than that of the traditional deterministic inversion method.  相似文献   

Towards a better understanding of the evolution of the flood risk in Mediterranean urban areas: the case of Barcelona     

Cort&#;s  Maria  Llasat  Maria Carmen  Gilabert  Joan  Llasat-Botija  Montserrat  Turco  Marco  Marcos  Ra&#;l  Mart&#;n Vide  Juan Pedro  Falc&#;n  Llu&#;s 《Natural Hazards》2017,85(1):39-57

Dam failure constitutes a grave threat to human life. However, there is still a lack of systematic and comprehensive research on the loss of life (L) caused by dam break in China. From the perspective of protecting human life, a new calculation method for L occurred in dam break floods is put forward. Fourteen dam failure cases in China are selected as the basic data by three-dimensional stratified sampling, balancing spatial, vertical elevation and temporal representations, as well as considering various conditions of the dam collapse. The method includes three progressive steps: Firstly, some impact factors of loss of life (IFL) are selected by literature survey, i.e., severity of dam break flood (S _F), population at risk (P _R), understanding of dam break (U _B), warning time (T _W) and evacuation condition (E _C). And the other IFL of weather during dam break (W _B), dam break mode (M _B), water storage (S _W), building vulnerability (V _B), dam break time (T _B) and average distance from affected area to dam (D _D) are also taken into account to get a more comprehensive consideration. According to disaster system and disaster risk, these eleven IFL are divided into four categories. Through the improved entropy method, eight key IFL are further selected out of the eleven. Secondly, four L modules are built based on four categories, which are L-causing factor module (M ₁), L-prone environment module (M ₂), affected body module (M ₃) and rescue condition module (M ₄). Eventually, by using two methods of multivariate nonlinear regression and leave-one-out cross-validation in combination with coupled four modules, the calculation method for L is established. Compared with the results of Graham method and D&M method, the result of the proposed one is much closer to the actual value and performs better in fitting effect and regional applicability. In the application, L calculation and consequence assessment are carried out in the example of Hengjiang reservoir that has already broken down. At the same time, L calculation and risk prediction are used in the analysis of Yunshan reservoir, which is under planning. The proposed method can not only be applied to estimate L and its rate (f _L ) under various types of dam break conditions in China, but also provide a reliable consequence assessment and prediction approach to reduce the risk of L.  相似文献   

High-pressure displacive phase transition of a natural Mg-rich pigeonite     

Matteo Alvaro  Fabrizio Nestola  Fernando Cámara  M. Chiara Domeneghetti  Vittorio Tazzoli 《Physics and Chemistry of Minerals》2011,38(5):379-385

A high-pressure single-crystal X-ray diffraction study has been carried out on a P2₁/c natural Mg-rich pigeonite sample with composition ca. Wo₆En₇₆Fs₁₈ using a diamond anvil-cell. The unit-cell parameters were determined at 14 different pressures to 7.14 GPa. The sudden disappearance of the b-type reflections (h + k = odd) and a strong discontinuity (about 2.8%) in the unit-cell volume indicated a first-order P2₁/c–C2/c phase transition between 4.66 and 4.88 GPa. The P(V) data of the P2₁/c phase were fitted to 4.66 GPa by a third-order Birch–Murnaghan equation of state (BM3 EoS), whereas the limited number of experimental data collected within the C2/c phase between 4.88 and 7.14 GPa were fitted using the same equation of state but with K′ constrained to the value obtained for the P2₁/c fitting. The equation of state coefficients are V ₀ = 424.66(6) ų, K _T0 = 104(2) GPa and K′ = 8(1) for the P2₁/c phase, and V ₀ = 423.6(1) ų, K _T0 = 112.4(8) GPa, and K′ fixed to 8(1) for the C2/c phase. The axial moduli for a, b, and c for the P2₁/c phase were obtained using also a BM3-EoS, while for the C2/c phase only a linear calculation could be performed, and therefore the same approach was applied for comparison also to the P2₁/c phase. In general the C2/c phase exhibits axial compressibilities (β _c > β _a >> β _b) lower than those of the P2₁/c phase (β _b > β _c ≈ β _a; similar to those found in previous studies in clinopyroxenes and orthopyroxenes). The lower compressibility of the C2/c phase compared with that of the P2₁/c could be ascribed to the greater stiffness along the b direction. A previously published relationship between P _c and M2 average cation radius (i.r.) has been updated using all the literature data on P2₁/c clinopyroxene containing large cations at M2 site and our new data. The following weighted regression was obtained: P _c (GPa) = 26(4) ? 28(5) ×  i.r (Å), R ² = 0.97. This improved equation can be used to predict the critical pressure of natural P2₁/c clinopyroxene samples just knowing the composition at M2 site.  相似文献   

Seismic hazard scenario and attenuation model of the Garhwal Himalaya using near-field synthesis from weak motion seismometry     

Sankar Kumar Nath  Khemraj Shukla  Madhav Vyas 《Journal of Earth System Science》2008,117(2):649-670

  相似文献   

Physicochemical model for the crystallization of rocks of the calc-alkaline series     

N. V. Surkov  Yu. G. Gartvich 《Geochemistry International》2012,50(10):799-815

The Al-rich region of the CaO-MgO-Al₂O₃-SiO₂ system was experimentally studied at pressures of 1.0–2.8 GPa and temperatures of 1300–1535°C. The slopes of the lines of the monovariant reactions An + Sp = Cpx + Cor + (Ga) and L = Cpx + Ga + Cor + Sp and the compositions of the phases involved in these reactions are determined. The results are utilized in the topological analysis of the aluminous region of the CaO-MgO-Al₂O₃-SiO₂ system. On this basis, the principal structure of the phase diagram is analyzed, and a phase diagram is constructed for the junction region of the quaternary system and the CaO-Al₂O₃-SiO₂ ternary system. A continuous series of the monovariant eutectic: L = Cpx + Opx + Fo + An, L = Cpx + Opx + An + Sp, L = Cpx + (Ga) + An + Sp, L = Cpx + Cor + (Ga) + An, L = An + Ga + Cpx + Ky and L = Ga + Cpx + Ky + Qz is examined within the pressure range from atmospheric to 3.0 GPa and higher. Analogous “telescoped” eutectic series are of fundamental character for interpreting the evolution of magmatic melts. A physicochemical model is suggested for the evolution of magmatic melts that produce rocks of the calc-alkaline series, with this model underlain by the fact that a change in the composition of magmatic melt at a pressure decrease should correspond to the minimum melting temperatures, i.e., to melts in the fundamental series of eutectic reactions. The comparison of our physicochemical model and rocks of the calc-alkaline series shows that the compositions of rocks of the calc-alkaline series are close to the compositions determined for the eutectic equilibria, and the mineralogical composition of xenoliths and megacrysts in volcanic and dike varieties of the rocks are similar to the subsolidus phases of the established fundamental eutectic system.  相似文献   

Crystal chemistry of natural and synthetic lead oxyhalides. Part I. Crystal structure of Pb<Subscript>13</Subscript>O<Subscript>10</Subscript>Cl<Subscript>6</Subscript>     

O. I. Siidra  S. V. Krivovichev  W. Depmeier 《Geology of Ore Deposits》2007,49(8):827-834

Crystals of lead oxychloride Pb₁₃O₁₀Cl₆ have been synthesized on the basis of high-temperature solid-state reactions. The Pb₁₃O₁₀Cl₆ structure was studied using X-ray single-crystal diffraction analysis. The compound is monoclinic, and the space group is C2/c; the unit-cell dimensions are a = 16.1699(14), b = 7.0086(6), c = 23.578(2) Å, β = 97.75°, and V = 2647.6(4) ų. The structure has been solved by direct methods and refined to R ₁ = 0.0505 for 2671 observed unique reflections. The structure is a 3D framework consisting of OPb₄ tetrahedrons. Chlorine atoms are located in the framework channels. The structure contains seven symmetrically independent Pb atoms, which are coordinated by 2 to 4 O^2? and 2 to 4 Cl^? anions. The synthesized compound is compared with other natural and synthetic lead oxyhalides.  相似文献   

On the crystal chemistry and elastic behavior of a phlogopite 3<Emphasis Type="Italic">T</Emphasis>     

G. D. Gatta  Marco Merlini  Nicola Rotiroti  Nadia Curetti  Alessandro Pavese 《Physics and Chemistry of Minerals》2011,38(8):655-664

The crystal chemistry and the elastic behavior under isothermal conditions up to 9 GPa of a natural, and extremely rare, 3T-phlogopite from Traversella (Valchiusella, Turin, Western Alps) [(K_0.99Na_0.05Ba_0.01)(Mg_2.60Al_0.20Fe _0.21 ²⁺ )[Si_2.71Al_1.29O₁₀](OH)₂, space group P3₁12, with a = 5.3167(4), c = 30.440(2) Å, and V = 745.16(9) ų] have been investigated by electron microprobe analysis in wavelength dispersion mode, single-crystal X-ray diffraction at 100 K, and in situ high-pressure synchrotron radiation powder diffraction (at room temperature) with a diamond anvil cell. The single-crystal refinement confirms the general structure features expected for trioctahedral micas, with the inter-layer site partially occupied by potassium and sodium, iron almost homogeneously distributed over the three independent octahedral sites, and the average bond distances of the two unique tetrahedra suggesting a disordered Si/Al-distribution (i.e., 〈T1-O〉 ~ 1.658 and 〈T2-O〉 ~ 1.656 Å). The location of the H-site confirms the orientation of the O–H vector nearly perpendicular to (0001). The refinement converged with R ₁(F) = 0.0382, 846 unique reflections with F _O > 4σ(F _O) and 61 refined parameters, and not significant residuals in the final difference-Fourier map of the electron density (+0.77/?0.37 e ^?/ų). The high-pressure experiments showed no phase transition within the pressure range investigated. The P–V data were fitted with a Murnaghan (M-EoS) and a third-order Birch-Murnaghan equation of state (BM-EoS), yielding: (1) M-EoS, V ₀ = 747.0(3) ų, K _T0 = 44.5(24) GPa, and K′ = 8.0(9); (2) BM-EoS, V ₀ = 747.0(3) ų, K _T0 = 42.8(29) GPa, and K′ = 9.9(17). A comparison between the elastic behavior in response to pressure observed in 1M- and 3T-phlogopite is made.  相似文献   

A numerical approach to the design parameters of permanent stoppings (seals and bulkheads) in Turkish underground coal mines     

Ozgur Yilmaz  Kemal Baris 《Arabian Journal of Geosciences》2018,11(11):284

Observing permanent seals with different physical and mechanical characteristics under various conditions in the field is almost impossible. In conjunction with the development of high-speed computer algorithms, numerical simulation has become one of the major means to study the dynamics of such problems. Therefore, this study covers only the numerical approach to analyze the stability of underground seals. In this regard, the purpose of this study is to provide an insight to the design of underground seals by numerically analyzing their behaviors under different static and dynamic explosion overpressures using a geo-technical commercial software FLAC3D. For this purpose, a series of numerical models were constructed for a typical seal in an underground gallery with different properties such as seal thickness, seal dimensions, gallery geometry, and strength of the seal material to investigate the stability of seals exposed to various static and dynamic explosion overpressures. A total of 896 numerical analyses (512 static and 384 dynamic) were performed and evaluated. Regarding the gallery geometry, it was found that seals constructed in trapeze-shaped galleries are more stable than those constructed in horseshoe-shaped galleries having the same dimensions. Moreover, the results showed that the seal stability increases with the increasing seal thickness rather than the strength of the seal material. The statistical analyses suggest that there is a very strong exponential relationship between the seal thickness and the maximum displacement measured at the midpoints of the outer surfaces of the seals. The coefficients of determination values obtained are in the range of 0.92–0.93 and 0.92–0.95 for static and dynamic analyses, respectively. We proposed formulas which use the longer dimension of the seal (W _max ), maximum allowable displacement on the seal (D _max ), explosion overpressure applied onto the seal (P _exp ), and compressive strength of the seal material (σ _c and σ _cd for static and dynamic conditions, respectively) to predict the minimum required seal thickness (T _s ) for static and dynamic conditions. The proposed formulas enable calculating the necessary seal thickness easily if the explosion overpressure (or hydrostatic pressure) is known or approximated.  相似文献   

Polymorphism of the hydroxide perovskite Ga(OH)<Subscript>3</Subscript> and possible proton-driven transformational behaviour     

M. D. Welch  A. K. Kleppe 《Physics and Chemistry of Minerals》2016,43(7):515-526

  相似文献   

Paleogene biostratigraphy of the North Circum-Caspian region (implication of the dinocysts and nannoplankton from the Novouzensk reference borehole), Part 1: Age substantiation and correlation of deposits     

O. N. Vasil’eva  V. A. Musatov 《Stratigraphy and Geological Correlation》2010,18(1):83-104

Eight zonal dinocyst assemblages and three bio stratigraphic units ranked as “beds with flora” are first distinguished in the Danian—lower Lutetian interval of the Paleogene succession, penetrated by the reference borehole Novousensk no. 1, where eight standard and one local nannoplankton zones are simultaneously recognized. The direct correlation of nannoplankton and dinocyst zones is used to refine the paleon-tological substantiation and stratigraphic position of regional lithostratigraphic units, ranges of hiatuses, and the correlation with the general stratigraphie scale. The nannoplankton of the Danian NP2 Cruciplacolithus tenuis and NP3 Chiasmolithus danicus zones is characteristic of the Algai Formation (Fm). The nannoplankton of the NP4 Coccolithus robustus Zone and dinocysts of the D3a Alterbidinium circulum Zone from the Tsyganovo Fm characterizes the Danian top. The Lower Syzran Subformation (Subfm) corresponds to the upper part of the NP4 Coccolithus robustus Zone (Neochiastizygus junctus local zone) and to the D3b (part) Cerodinium depressum Zone of the Selandian dinocysts. The latter spans part of the Upper Syzran Subformation, whose characteristic nannofossils are the nannoplankton of the NP5 Fasciculithus tympaniformis Zone and the dinocysts of the D3b (part) Isabelidinium? viborgense Zone of the Selandian. The Novouzensk Fm is represented by a succession of the dinocyst Cerodinium markovae Beds and the standard D4c Apectodinium hyperacanthum Zone of the upper Thanetian. The coccolitophorids of the lower Thanetian NP6 Heliolithus kleinpelli Zone occur at the formation base. The Bostandyk Fm includes successive bio stratigraphie units of the Ypresian. In the dinocyst scale, these are the D5a Apectodinium augustum Zone, the Pterospermella Beds (DEla Zone of the North Sea scale), and zones DBlb-c Deflandrea oebisfeldensis, D7c Dracodinium varielon-gitudum, and D8 Dracodinium politum—Charlesdowniea coleothrypta, while units of the nannoplankton scale correspond to the NP12 Martasterites tribrachiatus and NP13 Discoaster lodoensis zones. The Kopterek Fm yields Lutetian nannofossils: the nannoplankton of the NP14 Discoaster sublodoensis Zone and the dinocysts of the Wetzeliella coronata—Areosphaeridium diktyoplokum Beds. Three meaningful hiatuses are established at the Danian base, Selandian top, and in the lower Ypresian.  相似文献   

Simultaneous inversion application for characterizing Hamra Quartzite tight sand reservoir: a case study from Hassi Messaoud (Algeria)     

M. Iddir Sadi  A. Yahiaoui  M. Djeddi 《Arabian Journal of Geosciences》2017,10(13):279

Channel sand acts as a stratigraphic trap for hydrocarbon accumulation in many parts of the world. Delineation of this type of reservoir is crucial as channel sand may be scarce, and inaccurate location of the drilling wells could lose a huge currency. The Hassi Messaoud (HMD) field was subjected to multiphase tectonic events, where deep-seated structures were rejuvenated leading to intensive fault complexity. The main effective tectonic events upon the studied area are the Hercynian compression and deep erosion till the Ordovician Hamra Quartzite (HQZ) oil reservoir, followed by active Triassic rifting and filling the deeply eroded areas or the graben areas by eruptive volcanic rocks at Triassic time. Hercynian erosion and volcanic rocks distribution introduce a big uncertainty to the reservoir structural model. Amplitude versus offset (AVO) method is used as a helpful tool to differentiate channel sand from surrounding formations. Several attributes (P-impedance, S-impedance, longitudinal velocity Vp, shear velocity Vs and density ρ) are estimated from pre-stack seismic inversion. They have different sensitivity to the reservoir properties. Derived attributes such as Lamé parameters, incompressibility × density (λρ) and rigidity × density (μρ) can provide key lithology and fluid indicators (Goodway et al. 1997, Goodway CSEG Rec 26(6):39-60 2001). Petrophysically relating AVO attributes both to λρ and μρ and to each other in Lambda–Mu–Rho (LMR) cross-plot space can be a good tool for AVO interpretation (Rutherford and Williams Geophysics 54:680–688 1989 and Castagna and Swan Lead Edge 16(4):337–342 1997). After proper data conditioning, simultaneous inversion of pre-stack angle gathers is performed to get acoustic wave impedance (P-impedance), elastic wave impedances (S-impedance) and density ρ, then to calculate λρ and μρ volumes. In the studied area, λρ and μρ are used as a very important key to separate reservoir sands. The λρ and μρ curves are generated at each well location. Cross plots showed a fair separation of sand in the formation, i.e. higher μρ and lower λρ can detect sand. The output λρ and μρ volumes after simultaneous inversion follow the distribution of the sand which is consistent with the wells penetrating the target reservoir. This finding on the extension of the sand reservoir in terms of λρ and μρ. 3D cross-plot zonations are used for lithology discrimination. In this study, well logs were used to constrain lithology and to control the zonation filters by reducing the limits ambiguity. Other types of advanced attributes are calculated and tested. The obtained (μρ–λρ) volume acts as a good indicator for the sand distribution. It was finally used as sand presence index in the area. Also μρ has shown a good linear relationship with porosity. To note that the porosity volume is created based on the linear relationship with μρ. A product of derived porosity and the sand presence index (μρ–λρ) provides a good tool for reservoir characterization and lead to reservoir management, future planning of the field, and setting location for new wells.  相似文献   

The probable quadruple systems FK Aql and FZ Del     

A. I. Khaliullina 《Astronomy Reports》2017,61(7):612-623

Orbital-period variations of the eclipsing binaries FK Aql and FZ Del are analyzed. For each of the systems, a superposition of two cyclic variations of their orbital periods is found. FK Aql may be a quadruple system that contains two more bodies, besides the eclipsing binary, with masses M ₃ ? 1.75M _⊙ and M ₄ ? 1.47M _⊙, and the corresponding periods 15 and 82 yrs. This could also be a triple system with a third body of mass M ₃ ? 1.75M _⊙ and a period of the long-period orbit P ₃ = 15 yrs, or with a third body of mass M ₃ ? 1.30M _⊙ and a period of the long-period orbit P ₃ = 82 yrs. FZ Del may be a quadruple system with the additional componentmasses M ₃ ? 0.2M _⊙ and M ₄ ? 0.3M _⊙, with the periods 10.2 and 53.7 yrs. This could also be a triple system with a third-body mass M ₃ ? 0.2M _⊙ and a period of the long-period orbit P ₃ = 10.2 yrs. In both systems, the residual period variations could be due to magnetic cycles of the secondary. The period variations of the eclipsing binary FZ Del could also be due to apsidal motion, together with the influence of a third body or the effects of magnetic activity.  相似文献