Sharif Digital Repository

Content base image retrieval is an important research field with many applications. In this paper we presents a new approach for finding similar images to a given query, in a general-purpose image database using content-based image retrieval. Color and texture are used as basic features to describe images. In addition, a binary tree structure is used to describe higher level features of an image. It has been used to keep information about separate segments of the images. The performance of the proposed system has been compared with the SIMPLIcity system using COREL image database. Our experimental results showed that among 10 image categories available in COREL database, our system had a... 

A variational theory (VT), in which the potential energy of a real system is evaluated relative to the hard-sphere system, was used to investigate the medium's effects on the pair potential parameters. By adding the medium's effects to the isolated pair potential, the concept of an 'effective pair potential' (EPP) was introduced. The EPP parameters were compared with those of the average effective pair potential (AEPP) for Ar, which showed the importance of the medium effects and the long range interactions of the AEPP in dense fluids. The study showed that the depth parameter of the AEPP is much larger than that of the EPP  

The turbulent heat transfer in gas-solid flows through an inclined pipe under various inclination angles is studied with constant wall heat flux. The hydrodynamic k- τ and kθ- τθ thermal two phase model is used in a lagrangian/Eulerian four way approach. The numerical results agreed reasonably with available experimental data in vertical and horizontal pipe flows. The effects of inclination angles on the flow patterns are reported. The pressure drop and Nusselt number are enhanced significantly as the inclination increases up to a certain angle. The mass loading ratio has influence on the optimal inclination angle. With increasing loading ratio, the optimal inclination angle of maximum... 

The conventional Polymethyl methacrylate (PMMA) bone cement is not biodegradable and not bioactive to bond with the native bone and causes tissue necrosis resulting from its high exothermic polymerization. Hence, biodegradable bioactive bone cements with suitable setting time and mechanical properties should be introduced. In this study, novel bioactive bone cements containing Calcium Sulfate Hemihydrate (CSH), Bioactive Glass (BG), and Tricalcium Silicate (TSC) were developed. Firstly, CSH and BG binary system was optimized based on preliminary setting and mechanical tests. Secondly, the composite bioactive bone cements were obtained by adding different quantities of TCS to the optimized... 

MCM-41 nanoparticles were prepared by in situ assembly of inorganic precursors and CTAB. The structure of nanoparticles was characterized by XRD, TEM, particle size analysis, N2 adsorption techniques. The surface modification of particles in order to perfect dispersion in polysulfone (PSf) matrix was performed by dimethyldichlorosilane (DMDCS) and aminopropyltrimethoxysilane (APTMS) as new modification agents. Thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and SEM analysis were applied to investigate thermal stability, glass transition temperature and quality of distribution of particle in the nanocomposite membrane, respectively. The PDMS was used to coat the... 

Cardiovascular diseases are caused by hereditary factors, environmental conditions, and medication-related issues. On the other hand, the cardiotoxicity of drugs should be thoroughly examined before entering the market. In this regard, heart-on-chip (HOC) systems have been developed as a more efficient and cost-effective solution than traditional methods, such as 2D cell culture and animal models. HOCs must replicate the biology, physiology, and pathology of human heart tissue to be considered a reliable platform for heart disease modeling and drug testing. Therefore, many efforts have been made to find the best methods to fabricate different parts of HOCs and to improve the bio-mimicry of... 

This study examines the air quality on line 1 and 2 of Tehran underground metro. The total suspended particulate (TSP), PM10, PM2.5, PM1, CO2, NO, NO2, SO2, relative humidity and air temperature were measured. An integrated air quality index was also calculated for each location. The results revealed that, PMlO, PM2.5, and SO2 concentrations are higher than their environmental standard levels. The in station CO2 levels are higher while its' in train levels are lower than environmental permissible level. The air quality index showed that the in-train air quality is more acceptable than the instation air quality  

Estimation of physical parameters in dynamical systems driven by linear partial differential equations is an important problem. In this paper, we introduce the least costly experiment design framework for these systems. It enables parameter estimation with an accuracy that is specified by the experimenter prior to the identification experiment, while at the same time minimising the cost of the experiment. We show how to adapt the classical framework for these systems and take into account scaling and stability issues. We also introduce a progressive subdivision algorithm that further generalises the experiment design framework in the sense that it returns the lowest cost by finding the... 

This study presents a novel perspective on pressure-transient analysis (PTA) of downhole-pressure and flow-rate data by use of system-identification (SI) techniques as widely used in advanced process engineering. Key features of the paper are that it considers the classic PTA process from a system-theoretical perspective; derives the causal structure of the flow dynamics; proposes a method to deal with continuously varying pressure and flow-rate signals contaminated with correlated noise, which estimates physical reservoir parameters through a systematic matching procedure in the frequency domain; and can cope with arbitrary (i.e., not necessarily piecewise constant) flow-rate signals. To... 

The one-dimensional cutting stock problem has many applications in industries and during the past few years has been one of the centers of attention among the researchers in the field of applied operations research. In this paper, a revised version of Ant Colony Optimization (ACO) technique is presented to solve this problem. This paper is a sequel to the previous ACO algorithm presented by the authors. In this algorithm, according to some probabilistic rules, artificial ants will select cutting patterns and generate a feasible solution. Computational results show the high efficiency and accuracy of the proposed algorithm for solving one- dimensional cutting stock problem