

مجله پژوهش فيزيك ايران
Iranian Journal of Physics Research (IJPR)
ISSN 16826957
فصلنامه داراي رتبه علمي  پژوهشي (علوم پايه) به زبان فارسي و انگليسي
سال هجدهم، شماره 3، پاييز 1397




 Elastic scattering of 15N ions by 12C at 23 MeV (Text in Persian) H Nanakar *,O Kakuee Pages 379389 Abstract   Scattering of 15N ions with the energy of Elab = 23 MeV on the CH2(Au) target is investigated. Elastic scattering of these ions in the angular range of 7°19° was measured by employing the silicon strip detector، “LEDA”. Using the measured scattering data، deviation of ion beam، number of incident ions on the target and differential cross sections of the 12C(15N، 15N)12C elastic scattering in the angular range of 7°19° were determined. Moreover، by applying the optical model and using the Fresco software، the scattering cross sections in the angular range of 0°60° in the laboratory framework were obtained by entering the extrapolated optical parameters. The obtained cross section data were then compared with the experimental ones. The theoretical cross section data resulting from the optical potential exhibit meaningful difference with the experimental data obtained in this research work in the covered angular range.
Keywords: Elastic scattering, nucleusnucleus collision, 15N ion beam, 12C target, Optical Model, LEDA Detector
  
 Design and fabrication of a heterodyne electrooptic modulator in lithium niobate (Text in Persian) H Dehghan nayeri *,R Asadi,M Khaje Pages 391400 Abstract   In this research، design and fabrication of an integrated heterodyne electrooptic modulator in lithium niobate have been presented. In this modulator، the waveguide is made by using proton exchange process; to exert two high frequency signals، deposited electrodes with MachZender arms between them are used. In this method، every electrical signal is applied on one of the MachZender arms، so that it can be stimulated by one specific frequency; these two signals are united optically to create frequencies equal to sum and subtraction of the input signal frequencies in the output. Also، by using finite element method، the influence of proton diffusion scale in the output light mode، electrode dimension، and configuration in the overlap integral of the light mode and electrical field، as well as electrode impedance، is estimated.
Keywords: optical modulator, heterodyne, lithium niobate, waveguide, proton diffusion
  
 Raising flux pinning by Ni substitution in YBa2Cu3O7? (Text in Persian) B Hadisichani,H Shakeripour *,H Salamati Pages 421425 Abstract   The highTc Y1xNixBa2Cu3O7δ samples doped by Ni for Y atom، with x=0، 0.002، 0.004، 0.006 and 0.01 were synthesized by the standard solidstate reaction method. The XRD diffraction of samples showed no impurity phase in all samples. Magnetic susceptibility of the samples under two different magnetic fields of 0.8 and 400 A/m was measured. The results showed that by increasing nickel element to an optimum value، the intragranular connection and flux pinning were improved.
Keywords: highTc superconductor, magnetic susceptibility, flux pinning
  
 Frequency?driven chaos in the electrical circuit of DuffingHolmes oscillator and its control S Bhattacharya * , M. D Moinul Islam , S Basu , D Halder , A De Pages 5969 Abstract Full Text [PDF 1525KB]   Accurate detection of weak periodic signals within noise and possibility of secure messaging have made Duffing oscillator (DO) highly important in the field of communication. Investigation on the properties of DO is thus ardently sought for. An elegant approach to accomplish the same is to fabricate electronic circuit simulating DO nonlinear equation and to study the effect of input signal amplitude (Vin) and frequency (f)، disentangling each other. Recently، Vindriven chaotic dynamics was studied by constructing a simple DuffingHolmes (DH) oscillator circuit. However، the fdriven characteristics of the oscillator remain unknown at constant Vin. The present work is based on the MATLAB simulation of fdriven chaotic dynamics of the DH equation. Similar output، mixed with chaos and nonchaos، is obtained by constructing the circuit، both in lab and PSPICE simulation. The circuit moves into complete chaos at f=270 Hz، while period2 bifurcation appears at f=680 Hz for constant Vin 0.9V. The chaos control is also achieved by two simple methods. In the first method، the variation of circuit parameter (capacitance) induces chaos control. In the second method، synchronization is achieved by coupling two similar oscillators. These two methods، though apparently simple، could be highly beneficial for using DH in secure communication.
Keywords: Nonlinear dynamics, chaos, DuffingHolmes oscillator, electronic circuit, MATLAB, PSPICE, chaos control
  
تاريخ انتشار: 10/9/97 تلفن: 33912877، 33912878 (031)
تاريخ درج در سايت: 2/11/97
شمار بازديدکنندگان اين شماره: 176




