Sharif Digital Repository

Performance and mechanical properties of concrete such as tensile strength, compressive strength, conductivity, etc change with creation and emission of cracks. As health monitoring of important structures is a vital subject that demands a large amount of budget annualy. Studying problems and disadvantages of concrete is one of the most important branches of research.
There are many ways to detect damage in concrete. Electrical resistance method that has been used in this thesis. In this study, an instrument called Risistivity Meter is used to measuring the electrical conductivity. This instrument measured the electrical conductivity, that it can be appropriate way to detect cracks... 

Scientists want to know how they can control fluids motion. They use electric fields for controlling the fluids in different dimensions. In small size, application of electric fields is very important because of biological applications. We use electric current and field for rotating freely suspended films. Here, we study soap, polar and non-polar liquids, MBBA liquid crystal and ferrofluids films. We show that the surface charge plays the crucial role in rotating the films.We study the correlation between rotation of a film and different physical quantities.Our experiments confirm that dipole moments of fluid molecules do not show a clear effect on the rotation. Increasing the dipole moment... 

The electrical conductivity of the solution has been one of the important physical quantities in many application. In this respect many probes and devices such as conductive sensors have been devised. In this study electrical properties of different water samples at frequency step range of 100-100000 Hz are measured by using the long cylindrical capacitive sensor and a measuring module (LCR-703). Operation of the capacitance measurement module for such probes is based on the auto balancing bridge method. Comparison of the measured capacitances and measured resistances for different water samples shows a decrease by increasing the measurement frequency. In another study the dielectric... 

In a one-dimensional disordered system, Anderson localization is known to occur at any energy in the thermodynamic limit when the disorder is uncorrelated and white noise structure.
A great interest for 1D disordered models with correlated disorder has been growing since 2002, as it has become progressively clear that the correlation of the random potentials can deeply affect the electronic localization properties. Spatial correlation of disorder can unexpectedly create extended states at some particular energies.
In this thesis, we study the metal-insulator transition in one dimensional Anderson binary alloy with long range disordered hopping integral and on-site energy, using the... 

Scale deposition is one of the reasons of formation damage during water injection process. This phenomenon often ocuures when two incompatible waters that interact chemically and precipitate minerals, mix within the reservoir. A typical example is sea water, with high concentration of sulfate ion and formation water, with high concentrations of calcium and/or barium ions. Mixing of these waters, therefore, can cause precipitation of calcium sulfate and/or barium sulfate. This study was conducted to investigate the permeability reduction caused by deposition of calcium and barium sulfates in carbonate cores from mixing of injected sea water and formation water in two flow rates and two... 

Graphene is two dimensional nanomaterial, single layer of carbon atoms that exhibited excellent properties like high electrical conductivity and stiffness, but producing graphene and obtaining a good dispersion of graphene in a polymer matrix is still a major challenge. In this study by using the electrochemical route several graphene with different degree of oxidation produced in different electrolyte medium. According to XRD data, product of electrochemical exfoliation in dilute HNO3 medium includes 50% few-layer graphene (5 layers) and 25% GO and the rest are multi-layer graphene. Nonsolvent induced phase separation method were used to prepare TPU/Graphene nanocomposite. Different methods... 

Flexible polymers (elastomers) are especially suitable for dynamic applications, and carbon fillers are well-known filler for elastomers. These are widely used in elastomer matrices for various commercial applications. Some of carbon nano fillers like Nano Diamond cannot impart such high degree of reinforcement to polymer matrices mainly because of improper filler dispersion and lack of strong filler-polymer interaction. In this effort, we examine the effects of two different nanostructured carbons when they are incorporated in a rubber matric in terms of mechanical, thermal and electrical properties of the nanocomposites. Different ingredients and hybrid nanofillers were added to matric by... 

Nowadays, the use of processed conductive polymers for conducting matrix polymers, as well as improving other properties for planting in the body, is very common. In this project, the fabrication and identification of electrically conductive films and fibers from biocompatible poly lactic acid and conductive polyAniline polymer in the form of nano-fibers or nanoparticles was intended. These fibers and films have been made in form of a plate or tube then, have been used as biosensors. These polymeric prostheses should be sterilized before planting in human body. Gamma rays are the best sterilization methods and are used at low doses (25 kGy) to sterilize plastic medical supplies. On the other... 

Neural system in human body due to limitated cell proliferation requires high care, because the damage causes serious hurts and disables different tissues. Limit regeneration in central neural system can cause different neural diseases including brain exhaustions specially in old people, but the peripheral neural system may have been disabled and intrupt some other tissue beacuase of possible external injuries before aging. So that while some damages like neural fibers severing, some new medical care methods are required. Some of these methods are outograft, allograft and xenograft which implants neural tissues either between other patient's tissues or from somebody else's; however these... 

Flexible thermoelectric (TE) fabrics were prepared by dip coating of a mixture solution of water base colloidal geraphen nano sheet(GNS) and carbon nano tube(CNT) and polyaniline (PANI) on polyester fabric. The phase composition and morphology of the TE fabrics were investigated by FTIR-ATR diffraction and feld emission scanning electron microscopy. The TE properties of the PANI/GNS or CNT coated fabrics with different GNS and CNT loadings were measured in the temperature range from 303 to 338 K. As the content of GNS increased from 0.5 to 10 wt% and CNT increased from 0.5 to 20 wt%, the electrical conductivity of the PANI/GNS or CNT coated polyester fabrics increased, while the Seebeck... 

Deficiency of water leads to extensive researches on alternative water resources. recycling of wastewater for non-drinking purposes such as irrigation, industrial, green belts, forestry and streets and drainage channels washing is One of the existing methods. Therefore, sewage treatment with the purpose of reducing its electrical conductivity has been done in the current research using a real scale vermifilter. Hence, the effluent from a septic tank with a daily loading of 2 (m3/day) was pumped into the vermifilter during 45 days through a pumping system.Then, the effluent from the vermifilter by another pump entered on the surface of the substrate. The results showed that electrical... 

Polyamide 6 (PA6) / Polyphenylene oxide (PPO) nanoblends containing carbon naotube (CNT)/conductive carbon black (CCB) with incorporation of PPO-g-MA compatibilizer, physical and chemical dispersing agents were prepared via melt blending method. The effect of carbonic nano additives weight percent, incorporation of physical dispersing agent, PA6 viscosity, PPO weight percent and sequential mixing were investigated. Modified CNT with physical dispersing agent studied by thermal gravimetric analysis (TGA), fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy and PPO-g-MA studied by FTIR and titration. Also, nanoblend morphologies, CNT/CCB dispersability and CNT/CCB selective... 

Nowday, one of the important goals of researchers is to develop and improve the properties of intermediate tempreture solid oxide fuel cells with range of 600-800˚C. Therefore, choosing the right material as a cathode with good performance in this temperature range is very important. For this purpose, various materials with ionic and electron conductivity mixtures (MIECs) are used, especially oxides with a Radelsden-Paper structure. These oxides are shown by the formula An+1BnC3n+1, which are actually composed of a combination of perovskite layers (ABO3) that are alternately superimposed between two layers of rock salt (AO). In the present study, Sr3Fe2O7 powder with different amounts... 

Supercapacitors are safe and environmentally friendly energy storage devices that have been considered for their diverse applications. One of the most important factors that control supercapacitors' capacity is the electrode material's structure and properties. Adding heteroatoms or composite materials synthesis is one way to improve electrode performance. In this study, a facile, fast, and economical hydrothermal method was used to synthesize N doped, P doped or N/P co-doped 3D reduced graphene oxide (rGO) for high-performance supercapacitor application. Nitrogen and phosphorus elements were replaced by carbon atoms simultaneously during the graphene oxide hydrothermal reduction procedure.... 

In this research, a nanocomposite blend of polyamide 6/polystyrene containing polyaniline-coated carbon nanotubes was fabricated via melt blending method, aiming to achieve electrical conductivity in the range of static dissipation. The effect of weight percentage of nanofillers and surface modification of carbon nanotubes with polyaniline on the electrical properties and microstructure of the nanocomposite was investigated. To promote compatibility between the immiscible polyamide 6 and polystyrene polymers, PS-g-MA compatibilizer was utilized, and its effect on the morphology of the nanocomposite blend was examined. Additionally, the influence of weight percentage of nanofillers and the...