In this article, we discussed about the petrography and geochemistry of magmatic rocks of the?Mbip massif?located SW of Tcholliré, in Central North Cameroon (Central African Fold Belt). Petrographic study shows t...In this article, we discussed about the petrography and geochemistry of magmatic rocks of the?Mbip massif?located SW of Tcholliré, in Central North Cameroon (Central African Fold Belt). Petrographic study shows that this massif is made of granodiorite, amphibole-biotite granite, and biotite granite which often contain enclave of mafic rocks (gabbro). Granodiorites and granites show porphyritic texture and consist dominantly of plagioclase and alkaline feldspar phenocrysts, quartz, biotite and often few amphibole. The gabbro enclaves are characterized by a granular porphyroid texture constituted of amphibole, plagioclase and olivine phenocrysts, all in a matrix of small crystals of plagioclase, olivine, amphibole, pyroxene and opaque minerals. All the analyzed rocks provide geochemical features of sublkaline serie and have nothing to do with the alkaline nature previously signaled in the former works. Granodiorites and granites are shoshonitic to calc-alkaline strongly potassic affinity consistent with emplacement in the continental collision setting. They present positive anomalies in Rb, Th, U;negative anomalies in Sr, P, Ti, Nb, Ta and some facies contain hydrated minerals such as amphibole. These characters are consistent with crustal and mantle contribution in their genesis. The mafic rocks (gabbro) have geochemical characteristics conferring a mantle origin, as confirmed by the high Mg# value (49.9). On the whole, the fractional crystallization of the magma formed by melting of crustal material and the magmatic mixing are the main petrogenetic process in the Mbip massif. Petrographic studies and geochemical data shows that the Mbip massif was emplaced in an active continental margin, into transitional regime from the end of maximum compression to the beginning of relaxation.展开更多
The purpose of this work is to describe the suitable methods for aerodynamic characteristics calculation of hypersonic vehicles in free molecular flow and the transitional regimes. Moving of the hypersonic vehicles at...The purpose of this work is to describe the suitable methods for aerodynamic characteristics calculation of hypersonic vehicles in free molecular flow and the transitional regimes. Moving of the hypersonic vehicles at high altitude, it is necessary to know the behavior of its aerodynamic characteristics for all flow regimes. Nowadays, various engineering approaches have been developed for modelling of aerodynamics of aircraft vehicle designs at initial state. The engineering method that described in this paper provides good results for the aerodynamic characteristics of various geometry designs of hypersonic vehicles in the transitional regime. In this paper present the calculation results of aerodynamic characteristics of various hypersonic vehicles in all range of regimes by using engineering method.展开更多
The vacuum component of the Universe is investigated in both the quantum and the classical regimes of its evolution. The associated vacuum energy density was reduced by more than 78 orders of magnitude in 10-6 sec in ...The vacuum component of the Universe is investigated in both the quantum and the classical regimes of its evolution. The associated vacuum energy density was reduced by more than 78 orders of magnitude in 10-6 sec in the quantum regime and by nearly 45 orders of magnitude in 4 × 1017 sec in the classical regime. The vacuum energy was spent for the organization of new microstates during the expansion of the Universe. In the quantum regime, phase transitions were more effective in reducing the vacuum energy than in producing new microstates. Both of these phenomena have been recorded in the history of the Universe. Herein, the need for the evolution of the Universe’s vacuum component is discussed. Indeed, through this evolution, all 123 crisis orders of dark energy are reduced by conventional physical processes. A table of the vacuum energy’s evolution as the function of red shift and a short discussion about vacuum stability are presented.展开更多
In this paper, we find the optimal precursors which can cause double-gyre regime transitions based on conditional nonlinear optimal perturbation (CNOP) method with Regional Ocean Modeling System (ROMS). Firstly, we si...In this paper, we find the optimal precursors which can cause double-gyre regime transitions based on conditional nonlinear optimal perturbation (CNOP) method with Regional Ocean Modeling System (ROMS). Firstly, we simulate the multiple-equilibria regimes of double-gyre circulation under different viscosity coefficient and obtain the bifurcation diagram, then choose two equilibrium states (called jet-up state and jet-down state) as reference states respectively, propose Principal Component Analysis-based Simulated Annealing (PCASA) algorithm to solve CNOP-type initial perturbations which can induce double-gyre regime transitions between jet-up state and jet-down state. PCASA algorithm is an adjoint-free method which searches optimal solution randomly in the whole solution space. In addition, we investigate CNOP-type initial perturbations how to evolve with time. The results show:(1) the CNOP-type perturbations present a two-cell structure, and gradually evolves into a three-cell structure at predictive time;(2) by superimposing CNOP-type perturbations on the jet-up state and integrating ROMS, double-gyre circulation transfers from jet-up state to jet-down state, and vice versa, and random initial perturbations don't cause the transitions, which means CNOP-type perturbations are the optimal precursors of double-gyre regime transitions;(3) by analyzing the transition process of double-gyre regime transitions, we find that CNOP-type initial perturbations obtain energy from the background state through both barotropic and baroclinic instabilities, and barotropic instability contributes more significantly to the fast-growth of the perturbations. The optimal precursors and the dynamic mechanism of double-gyre regime transitions revealed in this paper have an important significance to enhance the predictability of double-gyre circulation.展开更多
文摘In this article, we discussed about the petrography and geochemistry of magmatic rocks of the?Mbip massif?located SW of Tcholliré, in Central North Cameroon (Central African Fold Belt). Petrographic study shows that this massif is made of granodiorite, amphibole-biotite granite, and biotite granite which often contain enclave of mafic rocks (gabbro). Granodiorites and granites show porphyritic texture and consist dominantly of plagioclase and alkaline feldspar phenocrysts, quartz, biotite and often few amphibole. The gabbro enclaves are characterized by a granular porphyroid texture constituted of amphibole, plagioclase and olivine phenocrysts, all in a matrix of small crystals of plagioclase, olivine, amphibole, pyroxene and opaque minerals. All the analyzed rocks provide geochemical features of sublkaline serie and have nothing to do with the alkaline nature previously signaled in the former works. Granodiorites and granites are shoshonitic to calc-alkaline strongly potassic affinity consistent with emplacement in the continental collision setting. They present positive anomalies in Rb, Th, U;negative anomalies in Sr, P, Ti, Nb, Ta and some facies contain hydrated minerals such as amphibole. These characters are consistent with crustal and mantle contribution in their genesis. The mafic rocks (gabbro) have geochemical characteristics conferring a mantle origin, as confirmed by the high Mg# value (49.9). On the whole, the fractional crystallization of the magma formed by melting of crustal material and the magmatic mixing are the main petrogenetic process in the Mbip massif. Petrographic studies and geochemical data shows that the Mbip massif was emplaced in an active continental margin, into transitional regime from the end of maximum compression to the beginning of relaxation.
文摘The purpose of this work is to describe the suitable methods for aerodynamic characteristics calculation of hypersonic vehicles in free molecular flow and the transitional regimes. Moving of the hypersonic vehicles at high altitude, it is necessary to know the behavior of its aerodynamic characteristics for all flow regimes. Nowadays, various engineering approaches have been developed for modelling of aerodynamics of aircraft vehicle designs at initial state. The engineering method that described in this paper provides good results for the aerodynamic characteristics of various geometry designs of hypersonic vehicles in the transitional regime. In this paper present the calculation results of aerodynamic characteristics of various hypersonic vehicles in all range of regimes by using engineering method.
文摘The vacuum component of the Universe is investigated in both the quantum and the classical regimes of its evolution. The associated vacuum energy density was reduced by more than 78 orders of magnitude in 10-6 sec in the quantum regime and by nearly 45 orders of magnitude in 4 × 1017 sec in the classical regime. The vacuum energy was spent for the organization of new microstates during the expansion of the Universe. In the quantum regime, phase transitions were more effective in reducing the vacuum energy than in producing new microstates. Both of these phenomena have been recorded in the history of the Universe. Herein, the need for the evolution of the Universe’s vacuum component is discussed. Indeed, through this evolution, all 123 crisis orders of dark energy are reduced by conventional physical processes. A table of the vacuum energy’s evolution as the function of red shift and a short discussion about vacuum stability are presented.
基金Supported by the National Natural Science Foundation of China(No.41405097)the Fundamental Research Funds for the Central Universities of China in 2017
文摘In this paper, we find the optimal precursors which can cause double-gyre regime transitions based on conditional nonlinear optimal perturbation (CNOP) method with Regional Ocean Modeling System (ROMS). Firstly, we simulate the multiple-equilibria regimes of double-gyre circulation under different viscosity coefficient and obtain the bifurcation diagram, then choose two equilibrium states (called jet-up state and jet-down state) as reference states respectively, propose Principal Component Analysis-based Simulated Annealing (PCASA) algorithm to solve CNOP-type initial perturbations which can induce double-gyre regime transitions between jet-up state and jet-down state. PCASA algorithm is an adjoint-free method which searches optimal solution randomly in the whole solution space. In addition, we investigate CNOP-type initial perturbations how to evolve with time. The results show:(1) the CNOP-type perturbations present a two-cell structure, and gradually evolves into a three-cell structure at predictive time;(2) by superimposing CNOP-type perturbations on the jet-up state and integrating ROMS, double-gyre circulation transfers from jet-up state to jet-down state, and vice versa, and random initial perturbations don't cause the transitions, which means CNOP-type perturbations are the optimal precursors of double-gyre regime transitions;(3) by analyzing the transition process of double-gyre regime transitions, we find that CNOP-type initial perturbations obtain energy from the background state through both barotropic and baroclinic instabilities, and barotropic instability contributes more significantly to the fast-growth of the perturbations. The optimal precursors and the dynamic mechanism of double-gyre regime transitions revealed in this paper have an important significance to enhance the predictability of double-gyre circulation.
