فهرست مطالب

  • Volume:2 Issue:1, 2008
  • تاریخ انتشار: 1387/02/11
  • تعداد عناوین: 10
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  • H. Hora, G. H. Miley, K. Philberth Page 1
    The discovery of nuclear fission by Hahn and Strassmann was based on a very rare microanalytical result what initially could not indicate the very complicate details of this most important process. A similarity is discussed for the low energy nuclear reactions LENR being proved from analogies of measurements of the uranium fission. The distributionof the elements at uranium fission has a similarity with the element distribution at LENR measured repeatedly in a reproduced way, what was observed at high density deuteron concentration in palladium. This is specifically focussed to the Maruhn-Greiner local maximum of the distribution within the large-scale minimum if the fission nuclei are excited. Consequences of the complications in uranium fission are discussed in comparison with LENR with respect to the studies of a hypothetical fissioning compound nuclear reaction via a concluded element 306X126 with double magic numbers. Some observations are reported which specifically refer to these results and comparison.
  • Y. Seyed Jalili, A. J. Bennett, E. Soderberg, P. N. Stavrinou, G. Parry Page 7
    The temperature dependence of lasing wavelength in 1.3-1.5 μm-range GaInNAs based low dimensional emitters is found to be quite small. We report room temperature (RT) GaInAsN vertical-cavity surface emitting laser emission at 1.3 μm developed using MBE with plasma source for nitrogen activation. RT photopumped operation is demonstratedat a wavelength of 1283 nm. Stimulated emission was observed to a record high temperature of 143 C, resulting in an emission wavelength of 1294 nm.
  • A. A. Masoudi, N. Ahmadi Page 11
    The two-dimensional Markovian surface, which has a Hamiltonian similar to restricted solid on solid (RSOS) model, has been investigated with the scattering method. The correlation functions, roughness parameters and structure factors have been obtained by analytical methods.
  • D. Dorranian, Z. Abedini, A. Hojabri, M. Ghoranneviss Page 17
    In this work RF oxygen plasma is used to modify the surface of poly methyl methacrylate (PMMA) sheets. Samples are immersed in plasma, produced by plane parallel capacitively coupled RF discharge at 13.56 MHz frequency and 25 W powers from 2 to 10 minutes. Modification of the treated surfaces are studied by using attenuated total reflectionFourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), contact angle measurement and UV-Vis-NIR spectroscopy. Based on the results the surface roughness is significantly altered. The water contact angle is decreased noticeably by this treatment. Weight loss per area unit of samples doesn’t increase linearly with time of treatment. Real and imaginary parts of refractive index and dielectric constant of samples are calculated with using the transmission and reflection spectrum of samples. Energy gaps are calculated which indicate that with this RF power, energy gaps are not changed significantly.
  • A. H. Sari, S. H. Mortazavi, N. Bolouki, M. Khoramabadi, H. R. Ghomi Page 23
    In this paper new structure of a plasma electron source has been described. This electron source can produce a powerful and monochromatic electron beam by a simple obstructed discharge mechanism. The beam current and diode current has been measured for low pressure He discharges under the influence of an external longitudinal magnetic field. The magnetic field could vary from 0 to 45 mT. Voltage-current characteristics and Paschen curves has been obtained under mentioned conditions. The results show that by increasing of magnetic field, efficiency of the system significantly enhances but it decreases at higher magnetic field values.
  • M. Elahi, N. Ghobadi Page 27
    In this article we report the preparation of CdSe thin films by chemical bath deposition method (CBD).The as deposited film grew with nanocrystalline cubic phase. The effect of annealing temperature, annealing time, deposition time and the temperature dependent of the DC-conductivity of CdSe nanoparticle films has been studied. It is shown that the optical gap and electrical properties are function of the key parameters and the electrical conductivity in the temperature range 300-475 K is dominated by the hopping of charge carrier between localized states.
  • Sh. Zorriasatein Page 33
    Density-functional theory has been applied to investigate systematics of sodium clusters Nan in the size range of n= 20-55. A clear evolutionary trend in the growth of their ground-state geometries emerges. The clusters at the beginning of the series (n=20-34) are disordered. For (n=35-43) clusters are symmetric and have partial icosahedral(two-shell) structure. The growth then goes through a series of disordered clusters (n=44-52) where the icosahedral core is lost. However, for n ≥53 a three shell icosahedral structure emerges. This change in the nature of the geometry is abrupt. In addition, density-functional molecular dynamics has been used to calculate the specific heat curves for the representative sizes n= 43, 45, 48 and 52. These results along with already available thermodynamic calculations for n= 20, 25, 40, and 55 enable us to carry out a detailed analysis of the heat capacity curves and their relationship with respective geometries for the entire series. Our results clearly bring out strong correlation between the evolution of the geometries and the nature of the shape of the heat capacities. The results also firmly establish the size-sensitive nature of the heat capacities in sodium clusters.
  • S. H. Hashemi, M. R. Abolhasani Page 43
    In this article, the theoretical study about structure of spin electron bands and magnetic properties of Bulk CrSb in ZinceBlende structure have been considered according to density functional theory by using LSDA approximation for exchange-correlation energy and potential calculations using FP-LAPW method by theoretical calculation of electronic band structure, spin energy bands, total and partial states density, electronic charge density of atoms at (110) and (100) crystalline plane. In this calculation, the degree of spin polarization and the total energy of bulk state are also studied by considering magnetic coupling between Cr spins and its neighbors. The results indicate thatCr by positive local magnetic momentum cause to arising total magnetic momentum equals to 3.0000μB in a unit cell, which confirm by a theoretical rule known as Rule of 8, too. This material completely shows metallic properties in up spin, energy bands of up spin have cut Fermi surface, so valence electrons with up spin can easily movefrom valence band to conduction band. But at down spin, valence bands were separated from conduction bands by indirect gap equals to 1.64377 eV, that indicates the clear characteristic of a nonconductor, therefore in this material only electrons with up spin participate in density of Fermi surface''s states and appearance of metal property, CrSbcan be considered as a half metal, in general the total density of up and down spin states also proves this result and CrSb''s half metallic property and introduces its electronic properties related.
  • S. Behnia, A. Akhshani, H. Mahmodi, H. Hobbenagi Page 53
    Recent developments in the theory of nonlinear dynamics have paved the way for analyzing signals generated from nonlinear biological systems. The main purpose of the present work is based on the analysis of the ECG signal, initially extracting the features of ECG, which are used for the detection and/or classification of ECGs. For this work,Correlation Dimension (D2), Largest Lyapunov Exponent (LLE), Ap-proximate Entropy (ApEn), Sample Entropy (SampEn) and Poincare plot methods were used from nonlinear time series analysis to characterize human ECG signals obtained from 24 hour-Holter recording. Four groups of ECG signals have been investigated. D2 and LLE are increasingly used to classify ECG signals. ECG time series were classified according to the results obtained from computation of above chaotic features. Our results, obtained from clinical data, improved the previous studies, which allow one to distinguish between healthy group and patients groups with more confidence than the standard methods for heart rate time series and gain more significant understanding of heart dynamics using Entropy features and Poincare plot along with D2 and LLE.
  • Z. Ghoranevis, T. Kato, T. Kaneko, R. Hatakeyama Page 63