Sharif Digital Repository

An experiment has been developed for the measurement of the muon charge ratio (ratio of positive to negative muons) in the cosmic ray flux in energy range 0.236-0.242 GeV. The muon charge ratio is found to be 1.35 ± 0.10 with a mean zenith angle of 32° ± 5°. Meanwhile, the distributions of muons in zenith (θ) and azimuth angles have been studied. A cosnθ distribution with n = 1.95 ± 0.13 has been obtained. An asymmetry has been observed in East-West directions because of geomagnetic field. © 2005 Elsevier B.V. All rights reserved  

We have monitored multi-TeV cosmic rays by a small air shower array in Tehran (35°43′ N, 51°20′ E, 1200 m ≤ 890 g cm -2). More than 1.1 × 106 extensive air shower events were recorded. These observations enabled us to analyse sidereal variation of the galactic cosmic ray intensity. The observed sidereal daily variation is compared to the expected variation which includes the Compton-Getting effect due to the motion of the earth in the Galaxy. In addition to the Compton-Getting effect, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms  

Previously it was shown that the most important inclination of the EAS events due to geomagnetic field is the effect over the secondary particles of them and the contribution of the primary is so small [1]. These secondary particles are mostly e± and μ ±, so we limited our study over these particles. It was simulated over 520,000 EAS events with (ON) and without (OFF) geomagnetic field for our site (B0 = 28:1 μT i + 38:4 μT k, h = 1200m a.s.l.). It is observed a quite North-South anisotropy in ON events and a quite random anisotropy in OFF events. This anisotropy is comparable with the recorded results in our site (ALBORZ observatory), but the simulated anisotropy is a little more than the... 

a small array of Water Cherenkov Detectors (WCDs) has recorded 600000 events related to extensive air showers in Tehran during one year at an altitude of 1200m. By employing the method of obtaining count in each time interval distributions we obtained the distribution of extensive air showers. 17 events were found in our data set which are more probable to be related to primary gamma ray photons. For more certainty we did a simulation to compare acquired results from simulation and data to become sure if 17 extensive air showers are electromagnetic or not  

Data from a small air shower array were used to examine the cosmic ray shadow of the Moon at energies more than 100 TeV. A simple technique has been used for the analysis of this data. In this technique the number of EAS events with arrival directions falling in error circles centered about the moving moon is compared to the mean number of events falling in error circles with centers randomly chosen in the sky. For any assumed angular radius of the error circle the deficit in EAS event count in the direction of moon which is a moon-related effect is interpreted as the shadow of the moon. A simple theoretical model has been developed to relate the mean number of EAS events, Nsky, to the... 

At ALBORZ Observatory in Tehran (51° 200 , 35 ° 430' , 1200 m) we accumulated a complete year of data by a 4-fold square array of Water Cherenkov Detectors (WCDs) with the side 6.08 m. It is recorded about 800,000 fine EAS events from 2006/11/12 to 2007/11/20 by the approximate recording rate of 0.03. Time differences between each two, three, four, five and ... have a very good agreement with gammafunction, which shows the correct random nature of the events. Of course we expect that about less than 1% of the EAS events (≤9000 events) be electromagnetic and naturally not random, but the contribution is so small. Then by Farley/Storey procedure [1] we found a signature of real sidereal data.... 

A new small array of cherenkov detectors has been deployed in Tehran, 1200 m above sea level. This array contains of four tanks full of distilled water with diameter of 64 cm and height of 130 cm. The effective area of each tank is about 6.5 × 103cm2 . They are used to detect the air showers and to record the arrival time of the secondary particles. We have collected about 486643 EAS in 5270 h of observation time from Nov-2006 to May-2007. We find zenith and azimuth distribution of EAS with this array. A cosn θ distribution with n = 7.3±0.1 was obtained for zenith angle. Since this tank of distilled water is cheaper and more available than Scintillators it is preferable to use them instead... 

A new small array of Cherenkov detectors has been deployed in Tehran, 1200 m above sea level. This array contains four tanks of distilled water with a diameter of 64 cm and a height of 130 cm. The effective area of each tank is about 1382 cm2. They are used to detect air showers and to record the arrival time of the secondary particles. We have collected about 640 000 extensive air showers (EAS) in 8298 h of observation time from November 2006 to October 2007. The distribution of air showers in zenith and azimuth angles has been studied and a cosn distribution with n = 6.02 0.01 was obtained for the zenith angle distribution. An asymmetry has been observed in the azimuthal distribution of... 

In this paper, a new procedure is developed for the solution of a general two-dimensional uncoupled symmetric double contact problem with smooth contact zones in which the indenter geometry is described by a piecewise biquadratic function. This procedure gives an approximate closed-form solution for any smooth indenter profile. In order to evaluate the accuracy of this approach, it is applied to the symmetric indentation of a flat surface by two rigidly interconnected parabolic indenters and results are compared with the exact unclosed-form solution. Moreover, this procedure is applied to the symmetric indentation of a flat surface by two rigidly interconnected cylinders to compare the... 

We recorded 600,000 (EASs) from Dec. 2006 to Oct. 2007 with a small array of water Cherenkov detectors. We found zenith and azimuth distributions of these events that confirm previous distributions from array of scintillator detectors. The study on EGRET sources are under consideration, besides, we have improved the size of our detectors to yield the best efficiency. The best shape for each detector will be a tank with 40 cm in diameter and 60 cm in height with a PMT in the center of lid. © 2009 American Institute of Physics  

The study of the anisotropy of the arrival directions is an essential tool to investigate the origin and propagation of cosmic ray primaries. A simple way of recording many cosmic rays is to record coincidences between a number of detectors. We have monitored multi-TeV cosmic rays by a small array of water Cherenkov detectors in Tehran (35°43′N, 51°20′E, 1200 m above sea level). More than 1.1×106 extensive air shower events were recorded. In addition to the Compton-Getting effect due to the motion of the Earth in the Galaxy, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms. © 2007 The American Physical Society  

Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some... 

Most part of Iran is dominated by arid and semi-arid areas due to low annual rainfall. The need for production of fresh water from brackish water is considerably high, especially in dry regions. In this study 1 month daily-based experimental data from a solar still site has been reported. The technical and operational problems of this site which finally contributed to the total cease of the site are described. Then a detailed analysis is investigated on progress of a prototype which constructed in order to solve the site's problems. The results of 1 month of experimental data of the final design showed that the last prototype could be used to solve the current problems of the site. The... 

Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and... 

Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance... 

In this letter, we propose a method for real-time high density impulse noise suppression from images. In our method, we first apply an impulse detector to identify the corrupted pixels and then employ an innovative weighted-average filter to restore them. The filter takes the nearest neighboring interpolated image as the initial image and computes the weights according to the relative positions of the corrupted and uncorrupted pixels. Experimental results show that the proposed method outperforms the best existing methods in both PSNR measure and visual quality and is quite suitable for real-time applications  

The disposal of used tires is a major environmental problem. With increasing interest on recovery of wastes, pyrolysis is considered as an alternative process for recovering some of the value in scrap tires. An accurate kinetic model is required to predict product yields during thermal or catalytic pyrolysis of scrap tires. Pyrolysis products contain a variety of hydrocarbons over a wide boiling range. A common approach for kinetic modeling of such complex systems is lumping where each lump is defined by a boiling point range. Available experimental data for thermal and catalytic pyrolysis of scrap tires from the literature were used to evaluate two types of lumping models; discrete and...