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1.
We suggest that the dynamical regime(s) underlying quasi-periodic oscillations observed in the spectra of bright galactic-bulge
X-ray sources are nonlinear with a mixed phase space. The important feature of such regimes is that they are generic among
nonlinear Hamiltonian and nearly Hamiltonian systems of more than two degrees of freedom. We give a simple example of such
chaotic (deterministic) systems whose spectra share a number of features with those observed for quasiperiodic oscillations
of such sources. 相似文献
2.
S. Amir Reza Beyabanaki Roozbeh Geraili Mikola Kianoosh Hatami 《Computers and Geotechnics》2008,35(3):346-356
This paper presents a new contact calculating algorithm for contacts between two polyhedra with planar boundaries in the three-dimensional discontinuous deformation analysis (3-D DDA). In this algorithm, all six type contacts in 3-D (vertex-to-face, vertex-to-edge, vertex-to-vertex, face-to-face, edge-to-edge, and edge-to-face) are simply transformed into the form of point-to-face contacts. The presented algorithm is a simple and efficient method and it can be easily coded into a computer program. In this paper, formulations of normal contact, shear contact and frictional force submatrices based on the new method are derived and the algorithm has been programmed in VC++. Examples are provided to demonstrate the new contact rule between two blocks. 相似文献
3.
High precision center-limb spectrograms of the K i resonance doublet line at λ 7699 Å were used to study the line formation and to determine the abundance of potassium in the solar atmosphere. The LTE assumption is not valid for these lines. Synthetic profiles computed in NLTE reproduce very well the observed center-limb line behaviour and yield log? K = 5.14±0.10 for the solar abundance of potassium (on the scale of log? H = 12 for Hydrogen). 相似文献
4.
An economic analysis was conducted for temporal yield variations of four local grape cultivars grown in rain-fed microcatchments in the Bajgah area of Fars province, in Islamic Republic of Iran. For this study, four local cultivars of grapes were considered. The cultivars examined were Black Rishbaba, Rotabi, Asgari and Black grapes. The soil type was a gravely loam with an average slope of 5–6%, in microcatchment systems, and in plots without microcatchments. Analysis of yield data with a multiple regression model indicated that a 9 m2 (3×3 m) microcatchment area for each individual plant (vine) was the most appropriate area for vineyards in this region. The results also demonstrated that by using this area for each grapevine, yields (kg/ha) were 40% greater than yields obtained for vines in the standard vineyard (without microcatchments) in this area. Economic analysis was performed and the cost and income were compared for a depreciation period (life-span period) of 50 years and interest rate of 14%. The analysis showed that a microcatchment area of 9 m2 is economically feasible. The Black Rishbaba rain-fed vines were the most suitable cultivar for this region. The benefit probabilities of rain-fed Black Rishbaba, Rotabi, Asgari and Black grapes with a microcatchment area of 9 m2 and without such an area were 63.3% (i.e. two of 3 years), 52.4% (i.e. one of 2 years), 32.9% (i.e. one of 3 years), 13.3% (i.e. one of 8 years), and 59.5% (i.e. two of 3 years), 39.4% (i.e. two of 5 years), 31.8% (i.e. one of 3 years), and 10.7% (i.e. one of 9 years), respectively. Therefore, the Black Rishbaba and Rotabi cultivars are economically more stable in microcatchment system, while only the Black Rishbaba cultivar would be such in the standard vineyard system. 相似文献
5.
Multivariate statistical techniques, i.e., correlation coefficient analysis, principal components analysis (PCA), and hierarchical
cluster analysis (CA), were applied to the total and water-soluble concentrations of potentially hazardous metals in sediments
associated with the Sarcheshmeh mine, one of the largest Oligo-Miocene porphyry copper deposits in the world. The samples
were analyzed for hazardous metal concentration levels by inductively coupled plasma mass spectrometry method. Results indicate
that the contaminant metals As, Cd, Cu, Mo, S, Sb, Sn, Se, Pb, and Zn were positively correlated with the total concentrations.
These hazardous metals also have strong association in the PCA and CA results. Different anthropic versus natural sources
of contaminant metals were distinguished by using CA method. Water-soluble fraction of hazardous metals showed that the hydro-geochemical
behavior of these metals in sediments is different considerably. Elements such as Cd, Co, Cr, Cu, Fe, Mn, Ni, S, and Zn are
readily water soluble from contaminated samples, especially from evaporative mineral phases, while the release of As, Mo,
Sb, and Pb into the water is limited by adsorption processes. Results obtained from the application of multivariate techniques
on the water-soluble fraction data set show that the hazardous metals are categorized into three groups including (1) Ni,
S, Co, Cu, Cr, and Fe; (2) Se, Mn, Cd, and Zn; and (3) Sb, As, Mo, and Sn. This classification describes the hydro-geochemical
behavior of hazardous metals in water–sediment environments of the Sarcheshmeh porphyry copper mine and can be used as a basis
in remedial and treatment strategies. 相似文献
6.
Maryam TAJBAKHSHIAN Abolfazl MOSAEDI Mohamad Hosein MAHMUDY GHARAIE Sayyed Reza MOUSSAVI HARAMI 《山地科学学报》2021,(6):1591-1608
Erosion of geological units and sediment load in rivers can be considered as the serious problems in recent decades.Increasing sediment loads generate major hazards for water resources development,particularly in terms of loss of reservoir storage due to sedimentation and siltation of water distribution systems.In this paper,the performance of four sediment rating curve (SRC) development methods was evaluated for the Shirin Darreh River(SDR) basin (1750 km2),located in North Khorasan Province,Iran.Data of flow discharge (Q) and suspended sediment flux (SSF)(Q-SSF pairs,N=957)and daily flow discharge,recorded by the Regional Water Company of North Khorasan (RWCNK) at the Qaleh-Barbar (QB) gauging site during 1989-2018were used.The flow discharge classification method performed best by meeting the desired criteria of most statistical indices,including normalized root mean square error (NRMSE),mean bias error (MBE),mean absolute error (MAE),index of agreement (d),and coefficient of determination (R~2).Based on the optimized method,the rate of suspended sediment transportation at the study site was estimated about2.7×10~6 ton year~(-1).Erodibility of the exposed formations in the study area was estimated based on a factorial scoring model (FSM).Three indices,focused on the outcrop and erodibility,were calculated for the geological units at sub-basin and total scales.Marl deposits are the most extensive geological unit in the three sub-basins and the maximum formation outcrop ratio (FOR) and participation in erosion (PCE)were obtained for these rocks at total scale.In fact,marl unit can be regarded as the main source to supply the suspended sediments in the study basin. 相似文献
7.
Seyedeh Fatemeh NEMATI Naser HAFEZI MOGHADAS Gholam Reza LASHKARIPOUR Hosein SADEGHI 《山地科学学报》2021,18(12):3261-3274
Characterizing the subsurface structure is an important parameter for the improvement of seismic hazard assessment.Due to the tectonic complexity of the earth,s... 相似文献
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10.
Raziyeh Hendizadeh Mazda Kompanizare Mohammad R. Hashemi G. Reza Rakhshandehroo 《Hydrogeology Journal》2016,24(4):865-876
In this study, the critical (or maximum) discharge rates before saline water enters a well were determined for vertical and horizontal wells in a freshwater aquifer which is separated from a static saline aquifer by a sharp interface. Flow around the well was solved by integration of a point sink solution along the well axis, and both the critical discharge rate and critical interface rise were determined through a comparison of the heads and vertical gradients at the saline–fresh water interface. The rates were determined for vertical and horizontal wells with various lengths and depths for different aquifer salinities. Results were generalized by drawing dimensionless type curves. The results showed that the dimensionless total critical discharge rates are higher for the longer horizontal wells and longer vertical wells with a certain bottom depth, and they almost linearly decrease with well depth at rates of 0.7–0.9. For the dimensionless well length of 0.2, the dimensionless total discharge rate of a horizontal well is about 0.1 more than that of a vertical well with the same length and well-top depth. Also, the critical discharge rates per unit length of well are inversely proportional to well length and remarkably higher for shallower wells. Additionally, the critical pumping rate is proportional to the salinity difference of the aquifers. These results were confirmed by comparison to existing solutions for vertical wells with dimensionless lengths of 0.2, 0.5 and 0.6, and for critical interface rises in the range of 0.75–0.9. 相似文献