| 6 | Warm tachyon inflation and swampland criteria显示文摘In this study,the scenario of a two-component warm tachyon inflation is considered,where the tachyon field plays the role of the inflaton by driving the inflation.During inflation,the tachyon scalar field interacts with the other component of the Universe,which is assumed to be photon gas,i.e.,radiation.The interacting term contains a dissipation coefficient,and the study is modeled based on two different and familiar choices of the coefficient that were studied in the literature.By employing the latest observational data,the acceptable ranges for the free parameters of the model are obtained.For any choice within the estimated ranges,there is an acceptable concordance between the theoretical predictions and observations.Although the model is established based on several assumptions,it is crucial to verify their validity for the obtained values of the free parameters of the model.It is found that the model is not self-consistent for all values of the ranges,and for some cases,the assumptions are violated.Therefore,to achieve both self-consistency and agreement with the data,the parameters of the model must be constrained.Subsequently,we consider the recently proposed swampland conjecture,which imposes two conditions on the inflationary models.These criteria rule out some inflationary models;however,warm inflation is among those that successfully satisfy the swampland criteria.We conduct a precise investigation,which indicates that the proposed warm tachyon inflation cannot satisfy the swampland criteria for some cases.In fact,for the first case of the dissipation coefficient,in which,there is dependency only on the scalar field,the model agrees with observational data.However,it is in direct tension with the swampland criteria.Nevertheless,for the second case,wherein the dissipation coefficient has a dependency on both the scalar field and temperature,the model exhibits acceptable agreement with observational data,and suitably satisfies the swampland criteria. | Abolhassan Mohammadi Tayeb Golanbari Haidar Sheikhahmadi Kosar Sayar Lila Akhtari M.A.Rasheed Khaled Saaidi | 2020 | Chinese Physics C2020，44，9： | 0 |
| 7 | 3D Face Reconstruction Using Images from Cameras with Varying Parameters显示文摘In this paper, we present a new technique of 3D face reconstruction from a sequence of images taken with cameras having varying parameters without the need to grid. This method is based on the estimation of the projection matrices of the cameras from a symmetry property which characterizes the face, these projections matrices are used with points matching in each pair of images to determine the 3D points cloud, subsequently, 3D mesh of the face is constructed with 3D Crust algorithm. Lastly, the 2D image is projected on the 3D model to generate the texture mapping. The strong point of the proposed approach is to minimize the constraints of the calibration system: we calibrated the cameras from a symmetry property which characterizes the face, this property gives us the opportunity to know some points of 3D face in a specific well-chosen global reference, to formulate a system of linear and nonlinear equations according to these 3D points, their projection in the image plan and the elements of the projections matrix. Then to solve these equations, we use a genetic algorithm which consists of finding the global optimum without the need of the initial estimation and allows to avoid the local minima of the formulated cost function. Our study is conducted on real data to demonstrate the validity and the performance of the proposed approach in terms of robustness, simplicity, stability and convergence. | Mostafa Merras Soulaiman El Hazzat Abderrahim Saaidi Khalid Satori Abderrazak Gadhi Nazih | 2017 | International Journal of Automation and computing2017，14，6： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员