Time filter

Source Type

Golmakani A.,Khavaran Institute of Higher Education | Golmakani A.,Abdus Salam International Center For Theoretical Physics | Homburg A.J.,University of Amsterdam
Dynamical Systems | Year: 2011

Lorenz-like attractors are known to appear in unfoldings from certain codimension two homoclinic bifurcations for differential equations in ℝ3 that possess a reflectional symmetry. This includes homoclinic loops under a resonance condition and the inclination-flip homoclinic loops. We show that Lorenz-like attractors also appear in the third possible codimension two homoclinic bifurcation (for homoclinic loops to equilibria with real different eigenvalues); the orbit-flip homoclinic bifurcation. We moreover provide a bifurcation analysis computing the bifurcation curves of bifurcations from periodic orbits and discussing the creation and destruction of the Lorenz-like attractors. Known results for the inclination flip are extended to include a bifurcation analysis. © 2011 Taylor & Francis.

Abbassi S.,Damghan University | Abbassi S.,Institute for Research in Fundamental Sciences | Ghanbari J.,Ferdowsi University of Mashhad | Ghanbari J.,Khavaran Institute of Higher Education | Ghasemnezhad M.,Ferdowsi University of Mashhad
Monthly Notices of the Royal Astronomical Society | Year: 2010

We examine the effects of a hydrodynamical wind on advection-dominated accretion flows (ADAFs) with thermal conduction in the presence of a toroidal magnetic field under a self-similar treatment. The disc gas is assumed to be isothermal. For a steady state structure of such accretion flows a set of self-similar solutions are presented. The mass-accretion rate decreases with radius r as Ṁ α rs+1/2, where s is an arbitrary constant. We show that existence of wind will lead to an increase of the accretion velocity. Cooling effects of outflows or winds are noticeable and should be taken into account for calculating luminosity and effective temperature of optically thin and thick ADAFs. Increasing the effect of wind decreases the disc's temperature because of energy flux which is taken away by winds. We will see that for a given set of input parameters, the solution reaches a non-rotating limit at a specific value of φs. The values of this limitation on φs will increase by adding s, the wind parameter. In fact, the higher values of s will allow the disc to have a physical rotating solution for larger φs. © 2010 The Authors. Journal compilation © 2010 RAS.

Amraei E.,Khavaran Institute of Higher Education | Mobasheri M.R.,K. N. Toosi University of Technology
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014

CCD Camera is a multi-spectral sensor that is carried by CBERS 2 satellite. Imaging technique in this sensor is push broom. In images acquired by the CCD Camera, some vertical striping noise can be seen. This is due to the detectors mismatch, inter detector variability, improper calibration of detectors and low signal-to-noise ratio. These noises are more profound in images acquired from the homogeneous surfaces, which are processed at level 2. However, the existence of these noises render the interpretation of the data and extracting information from these images difficult. In this work, spatial moment matching method is proposed to modify these images. In this method, the statistical moments such as mean and standard deviation of columns in each band are used to balance the statistical specifications of the detector array to those of reference values. After the removal of the noise, some periodic diagonal stripes remain in the image where their removal by using the aforementioned method seems impossible. Therefore, to omit them, frequency domain Butterworth notch filter was applied. Finally to evaluate the results, the image statistical moments such as the mean and standard deviation were deployed. The study proves the effectiveness of the method in noise removal.

Yadollahvand R.,Tarbiat Modares University | Rahnama B.,Khavaran Institute of Higher Education
Journal of Aquaculture Research and Development | Year: 2014

This study was conducted to determine the age of Black Pomfret (Parastromateus niger), based on otolith cross sections. The age of Black Pomfret was determined in the Oman Sea (Sistan and Baluchistan province), examining 94 specimens, in September 2012. From 94 otolith, 36 was sectioned and determined by age. The oldest specimen belonged to the female, with the total length of 56 cm, 6 years old and also the youngest specimen belonged to the female, with the total length of 21 cm, was estimated in 1 year. The smallest and largest specimens were 21 and 56 cm and 190 and 2161 g, respectively. The relationship between otolith size and the size and age of the fish showed that the otolith size has a strong and direct correlation with the age, total length and weight of the fish. © 2014 Yadollahvand R, et al.

Ahanj A.,Khavaran Institute of Higher Education | Ahanj A.,Institute for Research in Fundamental Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We consider a hidden-variable theoretic description of successive measurements of noncommuting spin observables on an input spin-s state. In this scenario, the hidden-variable theory leads to a Hardy-type argument that quantum predictions violate it. We show that the maximum probability of success of Hardy's argument in quantum theory is (12)4s, which is more than in the spatial case. © 2010 The American Physical Society.

Discover hidden collaborations