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排序方式: 共有919条查询结果,搜索用时 62 毫秒
1.
Siahsarani Amir Karami Khaniki Ali Aliakbari Bidokhti Abbas-Ali Azadi Majid 《Ocean Science Journal》2021,56(3):225-240
Ocean Science Journal - A storm surge is a complex phenomenon in which current, tide, and waves interact with each other. Even if the wind is the main force of driving the surge, waves and tide are... 相似文献
2.
《New Astronomy》2021
We study the motion of negligible mass in the frame work of Sitnikov five-body problem where four equal oblate spheroids known as primaries symmetrical in all respect are placed at the vertices of square. These primaries are also considered as source of radiations moving in a circular orbit around their common center of mass. The fifth negligible mass performs oscillations along z-axis which is perpendicular to the orbital plane of motion of the primaries and passes through the center of mass of the primaries. Under the combined effects of radiation pressure and oblateness, we have developed the series solution by the Lindstedt-Poincare technique and established averaged Hamiltonians by applying the Van der Pol transformation and averaging technique of Guckenheimer and Holmes (1983). The orbits such as regular, periodic, quasi-periodic, chaotic, or stochastic have been examined with the help of Poincare surfaces of section. 相似文献
3.
In this paper, we study an interacting holographic dark energy model in the framework of fractal cosmology. The features of fractal cosmology could pass ultraviolet divergencies and also make a better understanding of the universe in different dimensions. We discuss a fractal FRW universe filled with the dark energy and cold dark matter interacting with each other. It is observed that the Hubble parameter embraces the recent observational range while the deceleration parameter demonstrates an accelerating universe and a behavior similar to \(\Lambda \mbox{CDM}\). Plotting the equation of state shows that it lies in phantom region for interaction mode. We use \(\mathit{Om}\)-diagnostic tool and it shows a phantom behavior of dark energy which is a condition of avoiding the formation of black holes. Finally we execute the StateFinder diagnostic pair and all the trajectories for interacting and non-interacting state of the model meet the fixed point \(\Lambda \mbox{CDM}\) at the start of the evolution. A behavior similar to Chaplygin gas also can be observed in statefinder plane. We find that new holographic dark energy model (NHDE) in fractal cosmology expressed the consistent behavior with recent observational data and can be considered as a model to avoid the formation of black holes in comparison with the main model of NHDE in the simple FRW universe. It has also been observed that for the interaction term varying with matter density, the model generates asymptotic de-Sitter solution. However, if the interaction term varies with energy density, then the model shows Big-Rip singularity. Using our modified CAMB code, we observed that the interacting model suppresses the CMB spectrum at low multipoles \(l<50\) and enhances the acoustic peaks. Based on the observational data sets used in this paper and using Metropolis-Hastings method of MCMC numerical calculation, it seems that the best value with \(1\sigma \) and \(2\sigma \) confidence interval are \(\Omega _{m0}=0.278^{+0.008~+0.010} _{-0.007~-0.009}\), \(H_{0}=69.9^{+0.95~+1.57}_{-0.95~-1.57}\), \(r_{c}=0.08^{+0.02~+0.027}_{-0.002~-0.0027}\), \(\beta =0.496^{+0.005~+0.009} _{-0.005~-0.009}\), \(c= 0.691^{+0.024~+0.039}_{-0.025~-0.037}\) and \(b^{2}=0.035\) according to which we find that the proposed model in the presence of interaction is compatible with the recent observational data. 相似文献
4.
5.
Natural Resources Research - Assessing reservoir properties and knowing the relationship between different reservoir parameters can significantly help to plan for production from a reservoir. In... 相似文献
6.
In this paper the steady lateral growth of three-dimensional turbulent inclined turbidity current is investigated. To simulate the current, an experimental setup is developed to analyze the turbidity current for different regimes in the particle laden density currents environment. The Buckingham's π theorem together with a dimensional analysis is implemented to derive the appropriate non-dimensional variables. The experimental results were normalized and plotted in the form of non-dimensional graphs from which a theoretical model is developed and analyzed. Based on the results obtained for the steady lateral growth, three different regimes, namely, inertia-viscous one as the first regime, buoyancy-viscous and gravity-viscous as the second and third regimes are distinguished within the current.In these regimes, the force balance is between the driving and resisting forces. Namely, in the first regime, the force balance is between the inertia and viscous forces, in the second regime, the buoyancy and viscous forces, and in the third regime, gravity and viscous forces are balanced. The experimental results indicate that the lateral growth rate in the first regime is smaller than that in the second and third regimes due to the magnitude and type of the forces involved in those regimes. According to the graphical results, the three different lateral growth rates appear when the normalized current length is smaller than about 3, between about 3 and 10, and larger than about 10. In those regions,the slopes of the data are different with respect to one another. 相似文献
7.
In this study, comparison of blocking climatological behaviors is presented for the two periods of 1959–1988 and 1989–2018 in a part of the Northern Hemisphere including the Atlantic Ocean, Europe and West Asia regions. Blocking events were detected using a modified blocking index that is based on vertically integrated potential vorticity. By applying this index, the characteristics of detected blocking events such as frequency, duration, intensity and area were determined and compared for both the periods.According to the results, on average, 16 and 15 blocking events per year were identified in the first and second periods, respectively. The trend analysis shows that the number of blocking events in the period 1959–1988 was significantly decreased, while it was slightly increased in the period 1989–2018. Blocking activity was most prevalent from the eastern Atlantic through Europe to West Asia, but this longitude band exhibits a relatively eastward shift in the second period. In addition, the seasonal distributions are similar to those found in previous studies with the higher occurrence of blocking events during winter and autumn seasons and the lowest frequency in summer, as well as long-lasting events and greater intensity and extension in winter than the summer time, especially in the second period. These seasonal variations of blocking frequency may be due to synoptic scale eddies and planetary waves which are more active and stronger in the colder seasons than the other seasons. On the other hand, a comparison between the two periods shows that the blocking events tend to be more frequent over West Asia especially during summer in recent years. Although discrepancies between the two periods are not significant, they could be partly due to the impacts of climate change in recent decades. 相似文献
8.
Nourollah Teimouri Derikvand Ehsan Kharazi Hossein Ghorbanizadeh Eslami Hossein Jafari Mohammad Reza 《Water Resources》2020,47(3):421-429
Water Resources - The present study aimed to locate the areas prone to flood spreading in order to manage surface water resources. Therefore, the information layers of slope, land capability,... 相似文献
9.
Homa Razmkhah 《Water Resources》2018,45(1):34-49
Conceptual hydrological models are popular tools for simulating land phase of hydrological cycle. Uncertainty arises from a variety of sources such as input error, calibration and parameters. Hydrologic modeling researches indicate that parametric uncertainty has been considered as one of the most important source. The objective of this study was to evaluate parameter uncertainty and its propagation in rainfall-runoff modeling. This study tried to model daily flows and calculate uncertainty bounds for Karoon-III basin, Southwest of Iran, using HEC-HMS (SMA). The parameters were represented by probability distribution functions (PDF), and the effect on simulated runoff was investigated using Latin Hypercube Sampling (LHS) on Monte Carlo (MC). Three chosen parameters, based on sensitivity analysis, were saturated-hydraulic-conductivity (Ks), Clark storage coefficient (R) and time of concentration (t c ). Uncertainty associated with parameters were accounted for, by representing each with a probability distribution. Uncertainty bounds was calculated, using parameter sets captured from LHS on parameters PDF of sub-basins and propagating to the model. Results showed that maximum reliability (11%) resulted from Ks propagating. For three parameters, underestimation was more than overestimation. Maximum sharpness and standard deviation (STD) was resulted from propagating Ks. Cumulative Distribution Function (CDF) of flow and uncertainty bounds showed that as flow increased, the width of uncertainty bounds increased for all parameters. 相似文献
10.
Storage of water in aquifers using injection wells is an efficient way for utilizing excess desalinated water in arid regions. In this investigation we estimate the benefits of optimally recharging seasonal surplus desalinated water into a strategic coastal aquifer already benefitting from natural recharge of flash-floods water by a recharge dam. Since, usually the buyers of desalinated water commit to purchase surplus desalinated water under take-or-pay contracts, any attempt in utilizing the paid water is beneficial. Coastal cities are observing an increased urbanization leaving limited space for aquifer recharge infrastructure. In order to determine the optimal location of wells and maximize the use of surplus desalinated water available in winter period, a decision tool combining a numerical groundwater flow simulation model (MODFLOW) with an optimization model is developed. The results of this study show that increasing the number of wells from the existing 45 wells to 173 would allow storing 31.4 million cubic meter per year of excess desalinated water into the aquifer that can be used during later during summer months. The net benefit would reach US$55 million/year while the cost of drilling the new wells is US$5.11 million. 相似文献