فهرست مطالب

Iranian Journal of science and Technology (A: Siences)
Volume:33 Issue: 3, Summer 2009

  • A3
  • تاریخ انتشار: 1389/09/06
  • تعداد عناوین: 8
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  • V. Karakaya, T. A. Chishti Page 219
  • M. R. Eskandari, M. Bahadoran Page 225
  • E. Savas Page 235
    The object of this paper is to establish a summability factor theorem for summability |A, δ|k, k≥1 where A is the lower triangular matrix with non-negative entries satisfying certain conditions.
  • A. Tayebi, E. Peyghan Page 241
    In this paper, we study a class of Finsler metrics which contains the class of P-reducible and general relatively isotropic Landsberg metrics, as special cases. We prove that on a compact Finsler manifold, this class of metrics is nothing other than Randers metrics. Finally, we study this class of Finsler metrics with scalar flag curvature and find a condition under which these metrics reduce to Randers metric.
  • S. H. Khan, M. Abbas, A. R. Khan Page 249
    We introduce a new one-step iteration process to approximate common fixed points of two nonexpansive mappings in Banach spaces and prove weak convergence of the iterative sequence using (i) Opial’s condition and (ii) Kadec-Klee property. Strong convergence theorems are also established in Banach spaces and uniformly convex Banach spaces under the so-called Condition (A'), which is weaker than compactness.
  • A. Ezzatpanah Latifi, F. Abbasi Davani, M. Shahriari, A. Sharghi Ido Page 259
    In this paper we discuss an approach to the design and construction of an accurate timing single channel analyzer (TSCA) for the timing of pulses over a wide dynamic range. A brief overview of the timing methods and uncertainty factors as "walk and jitter" and a detailed description of the TSCA circuit are given together with some insight into the application and reasons that led us to the design and construction of constructed TSCA. The advantages of this instrument are then highlighted and the experimental results are presented.
  • K. Hadad, M. Hashemi Page 269
    In this study, a general theoretical model to foresee and calculate the current-voltage characteristics in a plateau zone and the associated efficiency of the neutron detector (sensitivity) is presented. This study is to complete the previous studies in this field. The model also considers electric field distortion resulting from the charge collection effect. The characteristics curve is obtained as a function of fission rate, chamber geometry, and filling gas pressure. The output current at the saturation domain is calculated. The applied voltages about two phenomena, recombination and avalanche, for working the chamber in an ionization zone are an important part of the calculation. In developing the theoretical model, the MCNP code for fission rate, the SRIM code for electron-ion pair and GEANT4 for gamma sensitivity calculations were used.
  • T. Kakavand, M. Haji-Shafeieha, H. Ghafourian Page 277
    Beryllium chemical combination has a considerable effect on the design and fabrication of the neutron source. In this investigation the beryllium combinations were studied as a generator of neutrons with various mass percentage, and the neutron yields were also calculated using the results of the ALICE and SRIM codes calculations per unit incident charge. The neutron yields of Beryllium Hydride, Beryllium Carbide, Beryllium Hydroxide, Beryllium Oxide, Beryllium Acetate, Beryllium Acetylacetonate and Beryllium Sulfate were calculated as 4397.992x10-7, 1511.184x10-7, 976.609x10-7, 595.299x10-7,336.163x10-7,169.62x10-7 and1 49.053x10-7 respectively. Our calculations indicate that, the Beryllium Hydride is a proper material for use in the 241Am-9Be neutron source.