Sharif Digital Repository

In the last few years there has been growing interest in the use of functional Magnetic Resonance Imaging (fMRI) for brain mapping. To decode brain patterns in fMRI data, we need reliable and accurate classifiers. Towards this goal, we compared performance of eleven popular pattern recognition methods. Before performing pattern recognition, applying the dimensionality reduction methods can improve the classification performance; therefore, seven methods in region of interest (RDI) have been compared to answer the following question: which dimensionality reduction procedure performs best? In both tasks, in addition to measuring prediction accuracy, we estimated standard deviation of... 

This study presents an innovative approach for the integration of flood hazard into the site selection of detention basins. The site selection process is conducted by taking into account multiple criteria and disciplines. Hydraulic modeling results derived from stormwater management model are employed by Technique for the Order of Prioritization by Similarity to Ideal Solution (TOPSIS) to determine flood hazard score. The score generated by TOPSIS is used in a spatial multi-criteria decision-making site selection framework. Applying the framework, a suitability map is generated in which primary locations for detention basin placement are determined. The method is demonstrated through the... 

A developed route to form TiO2 self cleaning coatings on polycarbonate substrates is reported. TiO2 coatings on plastics may find widespread application in auto and construction industries if possess desired photocatalytic and mechanical properties. A chemical surface treatment method was used to create hydrophilic groups on the surface. X-ray photoelectron spectroscopy showed the treatment led to the oxidation of surface groups. TiO2 deposition was based on wet coating using an anatase sol of TiO2 nanoparticles of 30 nm size. The sol was synthesized using a sol-gel route. A pre-coat of peroxotitanium complex was employed to improve adhesion and inhibit the substrate degradation. The coating... 

Flood as a natural disaster causes heavy human and economic losses and social unrests in most areas of the world. As flood control cost and flood damage compensation is a heavy burden over countries' budget, traditional flood design methods are being replaced by more reliable risk-based methods employing comprehensive risk analysis. In this respect, flood damage estimation is an important step in flood control systems design and analysis. In large river basins with complex reservoir systems and various land uses, flood damage estimation is complex, data-intensive, time demanding, and uncertain task requiring an intensive hydrologic and hydraulic analysis. In this study a simple approach is... 

Post-deposition annealing effects on nanomechanical properties of granular TiO2 films on soda-lime glass substrates were studied. In particular, the effects of Na diffusion on the films' mechanical properties were examined. TiO2 photocatalyst films, 330 nm thick, were prepared by dip-coating using a TiO2 sol, and were annealed between 100 °C and 500 °C. Film's morphology, physical and nanomechanical properties were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, differential thermo-gravimetric analysis, and nanoindentation. Contrary to expectations, the maximum film hardness was achieved for 300°C annealing, with a value of 0.69 ± 0.05 GPa.... 

Re/Mo separation is studied by a new solvent extraction technique which is based on extraction mechanisms of the constituent metals. Based on McCabe-Thiele plots, a flow diagram has been proposed for separation and purification of Re over Mo. Re-recovery section of the diagram shows that Re is extracted when major amount of Mo is removed. For removal of the remained Mo, a two-stage extraction is required at pH = 2 and V a/V o = 1. In order to obtain Re, the resulted aqueous phase is stripped by adding sulfuric acid. According to the results, while more Re is extracted at less pH, optimum extraction of Mo happens at pH = 1.2. Re selectivity over Mo maximizes by approaching of the pH to zero  

For several years, a substantial effort has been devoted to the study of 3-D source localization based on 2-D arrays by measuring the well-known azimuth and elevation angles. However, studies on 3-D source localization performed by 1-D arrays are still lacking. Perhaps, the most important drawback in the deployment of a 2-D array structure lies in the fact that it needs a planar space, which might not be available in some applications. This letter concentrates on the problem of 3-D source localization based on 1-D angle measurement provided by a linear array. Different from the traditional 2-D structures where each measurement induces a straight line, each measurement in the 1-D array... 

Thermodynamics of extraction of Zn2+ from sulfuric acid media contacting to a mixture of DEHPA and MEHPA diluted with 80 wt% aromatic - aliphatic kerosene with a constant DEHPA to MEHPA ratio is investigated at different acidities, concentrations and temperatures. As a result, the extraction reaction is found to be endothermic with a zinc distribution factor that increases with increasing of the temperature, acidity of the solution and the concentration of the extradant. The mechanism of the extraction reaction is shown to be different for pH > 1 with that at pH <1. The pH of the aqueous media has also an important influence on progressing of the extraction reaction  

Rhenium distribution between Tri-n-butyl phosphate (TBP) dissolved in kerosene and sulfuric aqueous media is investigated under different temperatures, acidities, and TBP concentrations. Results show an exothermic extraction reaction with a distribution factor that decreases with the increase of the temperature and increases with the increase of the acidity and the TBP concentration. The stoichiometry of the reaction indicates neutralization of 1 mole of H+ with 1 mole of ReO4- and solvating of a neutral molecule with four molecules of TBP. The structure of the complexes formed is, therefore, 4TBP · HReO4. The apparent Gibbs free energy of the formation of 4TBP · HReO4 from TBP, ReO4-, and... 

For the 4th IUPAP International Conference of Women in Physics, we report on activities in science and engineering in Iran, and conditions for women in physics, in the three years since the 3rd IUPAP International Conference of Women in Physics was held in 2008. Iran has made prominent advancements and astonishing progress in laser technology, biotechnology, nanotechnology, genetics, computer software and hardware, and robotics. Iranian scientists have been very productive in several experimental fields, such as pharmaceutical, organic, and polymer chemistry. Conditions for women in physics have improved greatly in recent years. A project to improve the environment for learning physics, and... 

The hierarchical coexistence of femtocells and macrocells is a promising approach for heterogeneous networks (HetNets), dealing mainly with indoor coverage issues and providing high data rates in cellular networks. As for any HetNet, mobility management with handoff issues on top, should be studied prior to hindering the successful deployment of these networks. The current study introduces a new handoff algorithm in hierarchical macro/femtocell HetNets based on the combination of quality of service metrics for efficient network selection including: received signal strength, co-channel interference level, and outage probability of each of femtocell and macrocell networks. The proposed... 

Effects of pH, D2EHPA, Cyanex® 272 and Cyanex® 302 on extraction of zinc, manganese and cobalt from a Zn-Mn-Co-Cd-Ni containing solution at the room temperature was comprehensively investigated. Addition of Cyanex® 302 indicated a left-shifting-effect on the extraction curve of zinc, a right-shifting-effect on the extraction curve of manganese and no effect on the extraction of cobalt. Addition of Cyanex® 272 shifted all three curves to the right. Therefore, the most suitable extractant for separation of zinc from manganese was therefore 0.3-0.3 mixture of D2EHPA and Cyanex® 302, and that for separation of manganese from cobalt was pure D2EHPA. The stoichiometric coefficient for the... 

Simultaneous extraction of zinc and cadmium by a mixture of di-2-ethyl hexyl phosphoric acid (DEHPA) and mono-2-ethyl hexyl phosphoric acid (MEHPA), and the synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA have been investigated. It was shown that the extraction of zinc and cadmium by DEHPA and/or MEHPA can be increased by an increase of pH. The results also illustrate that the pH0.5 of zinc, by increase in MEHPA from 0.1 to 8 vol%, did not vary significantly while that of cadmium varies from 0.63 to 2.4. In other words MEHPA prevents selective extraction of zinc from aqueous media containing both zinc and cadmium. Studies on the selective separation parameter... 

Micro and nanotechnology can potentially revolutionize drug delivery systems. Novel microfluidic systems have been employed for the cell culture applications and drug delivery by micro and nanocarriers. Cells in the microchannels are under static and dynamic flow perfusion of culture media that provides nutrition and removes waste from the cells. This exerts hydrostatic and hydrodynamic forces on the cells. These forces can considerably affect the functions of the living cells. In this paper, we simulated the flow of air, culture medium, and the particle transport and deposition in the microchannels under different angles of connection inlet. It was found that the shear stress induced by the... 

Thin porous membranes are important components in a microfluidic device, serving as separators, filters, and scaffolds for cell culture. However, the fabrication and the integration of these membranes possess many challenges, which restrict their widespread applications. This paper reports a facile technique to fabricate robust membrane-embedded microfluidic devices. We integrated an electrospun membrane into a polydimethylsiloxane (PDMS) device using the simple plasma-activated bonding technique. To increase the flexibility of the membrane and to address the leakage problem, the electrospun membrane was fabricated with the highest weight ratio of PDMS to polymethylmethacrylate (i.e., 6:1... 

Microfluidic devices have been widely used for biological and cellular studies. Microbioreactors for three-dimensional (3D) multicellular spheroid culture are now considered as the next generation in in vitro diagnostic tools. The feasibility of using 3D cell aggregates to form multicellular spheroids in a microbioreactor with U-shaped barriers has been demonstrated experimentally. A barrier array is an alternative to commonly used microwell traps. The present study investigates oxygen and glucose concentration distributions as key parameters in a U-shaped array microbioreactor using finite element simulation. The effect of spheroid diameter, inlet concentration and flow rate of the medium... 

Dielectrophoresis is a robust approach for manipulating bioparticles in microfluidic devices. In recent years, many groups have developed dielectrophoresis-based microfluidic systems for separation and concentration of various types of bioparticles, where the gradient of the electric field causes dielectrophoresis force acting on the suspended particles. Enhancing the gradient of the electric field with three-dimensional (3D) electrodes can significantly improve the efficiency of the system. Implementing planar electrodes in a 3D arrangement is a simple option to form a 3D-electrode configuration. This paper reports the development of a novel dielectrophoretic microfluidic system for... 

Carbon dioxide miscible flooding has become a popular method for Enhanced Oil Recovery (EOR) because it not only efficiently enhances oil recovery but also considerably reduces green house gas emissions. However, it can significantly cause asphaltene deposition, which leads to serious production problems such as wettability alteration, plugging of the reservoir formation, blocking the transportation pipelines, etc. It is crucial to investigate the effects of different factors on asphaltene deposition. A novel experimental setup was prepared to employ a high-pressure visual cell for investigation of asphaltene deposition on a model rock under typical reservoir conditions. The evolution of...