Sharif Digital Repository

Base isolation is a method for controlling the vibration of structure by modifying the transmission between the source of excitation and the vibration structure.In this thesis, the feasibility of using magnetic field in seismic response control of structures has been investigated. It is tried with the inspiration of magnetic trains. While the old trains ran on the rail lost a large amount of energy because of the friction between the wheels and the rails that decreased the train speed, in the maglev trains with separating them from the rail the friction is reduced to the least amount so that today these trains are able to run with the speed about 550 km/h. It has been tried in two concepts... 

Membrane bioreactors can replace the activated sludge process and the final clarification step in municipal wastewater treatment. The combination of bioreactor and crossflow microfiltration allows for a high chemical oxygen demand (COD) reduction of synthetic wastewater. In this study, experimental data from a laboratory scale membrane bioreactor are presented. In order to investigate the influence of various operating parameters such as hydraulic retention time (HRT), biomass concentration and organic loading rate on organic pollutant removal, the pilot scale submerged membrane bioreactor (SMBR) with a Polyvinylidene Fluoride (PVDF) hollow fiber membrane module was conducted using synthetic... 

When a fire breaks out in a tunnel, due to the enclosure of the interior of the road tunnels, hot and poison smoke quickly spreads in the tunnel. This phenomenon, in addition to destroy the tunnel structure, causes a lot of financial and human losses. In recent years, research into fire control has become more important with the occurrence of numerous accidents in road tunnels and fatalities. Longitudinal ventilation is still the main method for controlling smoke distribution in tunnels due to lower construction costs and acceptable efficiency. Numerous studies have been conducted to investigate the effect of different and effective parameters on fire control and smoke emissions in direct... 

Supersonic impinging jets, similar to the jet flows exhausted from a nozzle, generate high unsteady pressure and acoustic loads on the rocket payload or the VTOL aircraft structure with possible mission failure during the launch/starting phase. In the past, experimental studies were concentrated on characterizing the steady impingement flow and not the initial transient process. It was shown that one of the main characteristics of supersonic impinging jets is the dominance of the feedback loop mechanism. The present investigation is an attempt to examine the flow characteristics of a high temperature supersonic impinging jet through a convergent-divergent nozzle during the transient starting... 

In the preceding years, hydroxyapatite (HA)-based coatings and scaffolds have been known as the best biomaterials for dental and orthopedics applications. Biocompatible and bioactive hydroxyapatite-based Coatings on metallic implants is one of the best methods for reaching both suitable mechanical properties and appropriate bioactivity, leading to better osseointegration and osteoblast proliferation. The ultimate goal of this project is characterization as well as mechanical and electrochemical behavior investigation of Hydroxyapatite- Chitosan nanocomposite coating by electrophoretic deposition (EPD) method on Plasma Electrolyte Oxidation (PEO) treated titanium substrates and Magnesium (Mg)... 

Most of the current routing protocols in the WMSNs only consider the inter-path interference and not necessarily intra-path interference factor which is considered as one of the main causes of energy consumption in these networks. Among those protocols that consider this factor, none of them has ever come up with an algorithm capable of performing the routing without the need to use either the special hardware in the nodes (referred to as the GPS or directional antennas) or with the unrealistic assumption that the interference range is equal to the transmission range. The previously mentioned factors are critical in the sense that the former assumption results in more expensive sensor nodes... 

Control surfaces are used in combat aircrafts to control the pitching moment and to help the aircraft perform high angle of attack manoeuvres. For delta wing configuration, the flow characteristics around the horizontal tail depend on the wing and tail flow field and their interactions. The flow over delta wing is mainly characterised by strong vortices. These vortices move downstream and affect the tail flow field making the problem more complicated. The goal of this research is to study the effect of tail up wash on the horizontal wing-body- tail configurations in subsonic flow. For this purpose a series of wind tunnel tests were conducted on a model containing a moveable horizontal tail... 

Titanium anodes activated by noble metal oxides under the trade name of dimensionally stable anodes (DSAs) are widely used in the electrolytic industry, particularly in chlor – alkali electrolysis. Over 20 years of use, the fundamental aspects of their long – lasting performance are not fully understand and the corrosion mechanisms are still the subject of many investigations. RuO2 – TiO2 coatings on titanium substrate, due to proper electrochemical characteristics and good corrosion resistance, is most applicable as an anode in chlor – alkali systems. In the present investigation, the first layer of Pt – Ir coating is applied via electrodeposition method on the pretreated titanium substrate... 

Ni-SiC composite coatings are widely used in industry (equipment high wear resistance coatings, corrosion resistant coatings, ship and boiler coatings, . . . ). Its unique properties in high wear resistance, corrosion resistance and tribological properties, researchers tend to investigate this coating. This study covers Ni-SiC composite coating under pulsed current using a rotating disk electrode to achieve optimal conditions in synthsis process, increaseing hardness and resistance to corrosion in coatings.waats' bath established for electrodeposition in this research. Bath parameters, current parameters and hydrodynamic of solution is examined. Changing of current type from direct current... 

At the first stage, chitosan-hydroxyapatite-multiwalled carbon nanotube (CH-HA-MWCNT) composite coatings were synthesized by electrophoretic deposition technique (EPD) on Ti6Al4V and 316L stainless steel substrates at different levels of pH and characterized by X-ray diffraction (XRD), Raman spectroscopy, FTIR and field emission scanning electron microscopy (FESEM). A smooth distribution of HA and MWCNT particles in a chitosan matrix with strong interfacial bonding was obtained. At the second stage, effect of pH and MWCNT content of the suspension on corrosion behavior and mechanism of deposition were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)... 

Main aim of this work was to obtain the harder zinc coating and increasing the anti corrosive properties by mean of adding SiO2 particles by electrophoretic method.
The coating was applied on the substrate surface by mean of electro co-deposition technique in three different electrolytes ethanol, methanol and water. The morphology of the coating in each electrolyte studied by scanning electron microscope (SEM).For the Zn/SiO2 coatings achieved in ethanol solvent the polarization and EIS tests was took place and found that for the Zn/SiO2 coating contain less than 10% SiO2 the corrosion rate decreased but for the coatings contains more than 10% SiO2 the paradox occurred because of the... 

In nanometer technologies, the effect of process variation is observed in Multi-Processor System on Chip (MPSoC) in terms of variation in processors‟ frequency and leakage power. Traditionally, only worst case values of the system parameters were concerned and a worst-case optimization algorithm was employed for an application under design. As previous researches have shown these algorithms are not optimal in terms of parametric yield compared with newly employed statistical optimization algorithms. In this project, we have considered the problem of simultaneously selecting MPSoC architecture (which includes type and number of processors and the communication media) and task and... 

This thesis is concerned with the synthesis and characterization of high porous Ti based on thin films and the effect of polymer agents on their photocatalytic properties. Ti films can demonstrate different properties like self -cleaning and treatment of broad range of aqueous pollutants when it is exposed to light of wavelength less than 400 nm. This is due to photocatalytic reaction occurring on film surface which results in film superhydrophilicity and the active oxygen species production. This active sites and radicals will cause oxidize organic pollutants and microbe adherent to the material surface.
In this study Ti thin films have been prepared by the sol-gel method from...