Sharif Digital Repository

Since oil reservoirs are limited and energy demand is increasing, seeking for high efficient EOR processes or enhancing the efficiency of current proposed EOR methods for producing trapped oil from reservoirs are highly investigated. As a way out, it is possible to couple the EOR and nanotechnology to utilize the efficiency of both methods together. Regarding this possibility, in the present study, in the first stage of investigation stable and uniform water-based solution of nano-sized particles of copper oxide with different concentrations (0.01–0.05 M) were prepared and then injected into the core samples. In the first stage, the effects of different surfactants with respect to their... 

As a bone tissue engineering material, polylactic acid (PLA) has received significant attention and interest due to its ease of processing and biocompatibility. However, its insufficient mechanical properties and poor wettability are two major drawbacks that limit its extensive use. For this purpose, the present study uses in-situ cold argon plasma treatment coupled with a fused deposition modeling printer to enhance the physio-mechanical and biological behavior of 3D-printed PLA scaffolds. Following plasma treatment, field emission scanning electron microscopy images indicated that the surface of the modified scaffold became rough, and the interlayer bonding was enhanced. This resulted in... 

Despite tremendous efforts toward vaccination, influenza remains an ongoing global threat. The induction of strain-specific neutralizing antibody responses is a common phenomenon during vaccination with the current inactivated influenza vaccines, so the protective effect of these vaccines is mostly strain-specific. There is an essential need for the development of next-generation vaccines, with a broad range of immunogenicity against antigenically drifted or shifted influenza viruses. Here, we evaluate the potential of whole inactivated vaccines, based on chemical and physical methods, as well as new approaches to generate cross-protective immune responses. We also consider the mechanisms by... 

Nowadays networks-on-chip are emerging as a hot topic in IC designs with high integration. In addition to popular mesh topologies, other structures can also be considered especially in 3D VLSI design. The Kautz topology is one of the interconnection architectures for multiprocessors. In this paper we propose an efficient three dimensional layout for a novel 2D mesh structure based on the Kautz topology. Simulation results show that by using the third dimension, performance and latency can be improved compared to the 2D VLSI implementation. ©2008 IEEE  

This paper proposes two-dimensional directed graphs (or digraphs for short) as a promising alternative to the popular 2D mesh topology for networks-onchip (NoCs). Mesh is the most popular topology for the NoCs, mainly due to its suitability for on-chip implementation and low cost. However, the fact that a digraph offers a lower diameter than its equivalent linear array of equal cost motivated us to evaluate digraphs as the underlying topology of NoCs. This paper introduces a family of NoC topologies based on three well-known digraphs, namely de Bruijn, shuffleexchange, and Kautz. We study topological properties of the proposed topologies. We show that the proposed digraph-based topologies... 

In this paper, a 2D shuffle-exchange based mesh topology, or 2D shuffle-exchange mesh (SEM) for short, is presented for network-on-chips. The proposed 2D topology applies the conventional well-known shuffle-exchange structure in each row and each column of the network. Compared to an equal sized mesh which is the most common topology in on-chip networks, the proposed shuffle-exchange based mesh network has smaller diameter but for an equal cost. Finally for better performance cross-shuffle is proposed. Simulation results show that the 2D SEM and 2D cross-shuffle effectively reduce the power consumption and improve performance metrics of the on-chip networks compared to the conventional mesh... 

This paper proposes two-dimensional directed graphs (or digraphs for short) as a promising alternative to the popular 2D mesh topology for networks-onchip (NoCs). Mesh is the most popular topology for the NoCs, mainly due to its suitability for on-chip implementation and low cost. However, the fact that a digraph offers a lower diameter than its equivalent linear array of equal cost motivated us to evaluate digraphs as the underlying topology of NoCs. This paper introduces a family of NoC topologies based on three well-known digraphs, namely de Bruijn, shuffleexchange, and Kautz. We study topological properties of the proposed topologies. We show that the proposed digraph-based topologies... 

This study investigates a supply chain of perishable fruits and vegetables. A simulation model using system dynamics approach is proposed to study the behaviors and relationships within the supply chain and to determine the impact of the supply, demand and price interactions. The proposed model yields an insight into the overall agricultural system, taking into account the influence of import quota policies. The purpose of this study is to develop a multi-objective model identifying the best import quota policy for Tehran Municipality Organization of Fruits and Vegetables. The multiple objectives are considered to be price mean, price variation and markup. Key conclusions were reached on how... 

In this paper, a 2D shuffle-exchange based mesh topology, or 2D shuffle-exchange mesh (SEM) for short, is presented for network-on-chips. The proposed 2D topology applies the conventional well-known shuffle-exchange structure in each row and each column of the network. Compared to an equal sized mesh which is the most common topology in on-chip networks, the proposed shuffle-exchange based mesh network has smaller diameter but for an equal cost. Finally for better performance cross-shuffle is proposed. Simulation results show that the 2D SEM and 2D cross-shuffle effectively reduce the power consumption and improve performance metrics of the on-chip networks compared to the conventional mesh... 

During the recent years, 2D mesh network-onchip has attracted much attention due to its suitability for VLSI implementation. The 2-dimensional de Bruijn topology for network-on-chip is introduced in this paper as an attractive alternative to the popular simple 2D mesh NoC. Its cost is equal to that of the simple 2D mesh but it has a logarithmic diameter. We compare the proposed network and the popular mesh network in terms of power consumption and network performance. Compared to the equal sized simple mesh NoC, the proposed de Bruijn-based network has better performance while consuming less energy. © 2008 IEEE  

In this paper, a 2D shuffle-exchange based mesh topology, or 2D SEM (Shuffle-exchange Mesh) for short, is presented for network-on-chips. The proposed two-dimensional topology applies the conventional well-known shuffle-exchange structure in each row and each column of the network. Compared to an equal sized mesh which is the most common topology in on-chip networks, the proposed shuffle-exchange based mesh network has smaller diameter but for an equal cost. Simulation results show that the 2D SEM effectively reduces the power consumption and improves performance metrics of the on-chip networks with regard to the conventional mesh topology. ©2008 IEEE  

A novel intelligent semi-active control system for an eleven degrees of freedom passenger car's suspension system using magnetorheological (MR) damper with neuro-fuzzy (NF) control strategy to enhance desired suspension performance is proposed. In comparison with earlier studies, an improvement in problem modeling is made. The proposed method consists of two parts: a fuzzy control strategy to establish an efficient controller to improve ride comfort and road handling (RCH) and an inverse mapping model to estimate the force needed for a semi-active damper. The fuzzy logic rules are extracted based on Sugeno inference engine. The inverse mapping model is based on an artificial neural network... 

Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the... 

With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost... 

Gaining insight into possible vibratory responses of dynamical systems around their stable equilibria is an essential step, which must be taken before their design and application. The results of such a study can significantly help prevent instability in closed-loop stabilized systems by avoiding the excitation of the system in the neighborhood of its resonance. This paper investigates nonlinear oscillations of a rotary inverted pendulum (RIP) with a full-state feedback controller. Lagrange’s equations are employed to derive an accurate 2-DoF mathematical model, whose parameter values are extracted by both the measurement and 3D modeling of the real system components. Although the governing... 

A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring... 

We introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (GT), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems. The modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-APA) by means of Escherichia coli ATCC11105 with penicillin G acylase (PGA) activity. The results show that GT beads can not only serve as a proper matrix for immobilization, but show enhanced hydrolysis rate and stability compared to other immobilization systems used for this reaction. This signifies the potential of GT as a biocompatible matrix for...