Sharif Digital Repository

Several efforts have been performed to improve LBM defects related to its computational performance. In this work, a new algorithm has been introduced to reduce memory consumption. In the past, most LBM developers have not paid enough attention to retain LBM simplicity in their modified version, while it has been one of the main concerns in developing of the present algorithm. Note, there is also a deficiency in our new algorithm. Besides the memory reduction, because of high memory call back from the main memory, some computational efficiency reduction occurs. To overcome this difficulty, an optimization approach has been introduced, which has recovered this efficiency to the original... 

The hardening behavior of heat treatable alloys during deformation is attributed to three mechanisms of forest dislocations, solid solution and precipitation hardening which hinder the motion of dislocations and increase the density of statistically stored dislocation. In this paper, a model for the flow stress of a 2024 heat treatable aluminum alloy during plastic deformation is developed combining the superposition of these three hardening mechanisms. This model was then implemented into the finite element model in order to evaluate the evolution of the flow stress of 2024 aluminum alloy during multi-directional forging (MDF). Subsequently, an equation is developed for evaluating the... 

In this work we propose using heterogeneous interconnects in power-aware chip multiprocessors (also referred to as Helia). Helia improves energy efficiency in snoop-based chip multiprocessors as it eliminates unnecessary activities in both interconnect and cache. This is achieved by using innovative snoop filtering mechanisms coupled with wire management techniques. Our optimizations rely on the observation that a high percentage of cache mismatches could be detected by utilizing a small subset but highly informative portion of the tag bits. Helia comes in two variations: source-based (S-Helia) and destination-based (D-Helia). S-Helia relies on a global snapshot of remote caches collected in... 

Effects of both electron beam irradiation on the properties of polypropylene (PP) films and the irradiation on the different layers of a multilayer PP film are studied. A Fourier transform infrared spectroscope was used to investigate the chemical structure of the films. The results showed that the chemical properties of the first layer were improved, that is, more functional groups responsible for dye ability and hydrophilicity of the film were produced on its surface, while noticeable improvement was not detected on the surface of other layers. This was also confirmed by testing the dye ability of the layers. However, the results obtained by atomic force microscopy showed that the electron... 

Scour phenomenon around piles could endanger the stability of the structures placed on them. Therefore, an accurate estimation of the scour depth around piles is very important for engineers. Due to the complexity of the interaction between the current, seabed and pile group; prediction of the scour depth is a difficult task and the available empirical formulas have limited accuracy. Recently, soft computing methods such as artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) have been used for the prediction of the scour depth. However, these methods do not give enough insight into the generated models and are not as easy to use as the empirical formulas. In... 

4-Aminoperoxybenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of ketones to esters. Copyright © Taylor & Francis Group, LLC  

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  

The atmosphere effect before shower maximum is dominantly: an environment for development of Extensive Air Shower(EAS) events, but after that, the absorbtion effect of the atmosphere will be dominant. The shower maximum for about 100 TeV is near 500 gr/cm2 (∼5200m a.s.l), and most of EAS arrays in this energy range are at heights below the shower maximum height, specially for higher zenith angle EAS events, so we need to more concentration on the absorbtion effect specially in this energy range and our site. Therefore for this investigation we logged 476,675 true EAS events by an array of particle water Cherenkov detectors. We calculated the local coordinates (θ, φ) of each EAS event by... 

EAS events are developing in the last few 10 kilometers of their path in the atmosphere. But geomagnetic field has been extended until a few thousand kilometers around the Earth. This field deflects charged particles and the deflection is different for different directions and observers. These differences depend on the amount and direction of the geomagnetic field (a dipole inside the earth) and direction of the charged particle. It was accurately investigated for 100 TeV primary particles from H0 = 20, 000 kilometers from the center of the earth (BH = 0.03 * B 0) to the ground and it was observed that the deflection is less than 10-6 degrees in azimuth angle φ. Therefore we investigated the... 

Low temperature plasma (LTP) is nowadays an intensively investigated superficial treatment of wool. In this work we have investigated the effect of LTP on wool fabric under different conditions. The effect of the position of samples inside the reactor and the kind of gases used as discharge medium has been also investigated. The results show that not only the topography of the surface is modified but also the chemical composition of the surface. It is shown that the hydrophilicity of the samples and also their shrink resistance and anti-felting behavior have improved significantly under LTP treatment. The results show that the shrinkage of 30.1% for untreated samples has reduced to about...