Sharif Digital Repository

In the present study the hot deformation behavior and the effect of hor rolling variables on the shape memory properties of a Ni-Ti shape memory alloy was studied. In order to simulate the hot compression test Abaqus softeware was employd. The results proved the pronounced increase in the specimen temperature at high strain rates and low temperatures (47 °C at strain rate of 1 s-1 and temperature of 700 °C). Thus, the effect temperature rise due to deformation heating on the characterisitics of the flow curves was eliminated. Afterwards, the corrected constitutive equation of the alloy was obtained and the rolling plan was designed. Shape memory measurments showed that two-way shape memory... 

Acidophilic microorganisms such as Thiobacillus ferrooxidans have the capability to carry out process of biorecovery of heavy metals. Its principle is the microbial production of the sulphuric acid and simultaneous recovery of metals. Acidithiobacillus ferrooxidans derives the energy for their metabolism from ferrous iron oxidation process which can be affected by the presence of heavy metals in the medium. In this study the ability of Acidithiobacillus ferrooxidans, on the biorecovery of heavy metals in shake flask has been investigated The adaptation of the Acidithiobacillus ferrooxidans to a kind of heavy metal such as Nickel, Cobalt, Vanadium, Molybdenum, Tungsten and the mixture of the... 

In this research, a comprehensive examination on hot and cold deformation of Al-Mg6 alloy has been performed. In order to find out hot deformation behavior of Al-Mg6, hot compression tests at 350, 450, and 550 oC and at strain rates of 0.001, 0.1, and 1 s-1 have been carried out. After the correction of the curves due to friction and adiabatic heating effects, constitutive equation of this alloy has been derived. Corrected curves show the occurrence of dynamic recovery. A new method for developing strain dependent constitutive equation has been employed using normalized stress and strain curve. After normalization, the curves at all deformation conditions follow a similar behavior.Rolling of... 

In this research, Nickel recovery has been investigated from spent catalyst (NiO/Al2O3) in reformers of direct reduction iron plant (Midrex). Genetic Algorithm method was applied for screening and optimization of the parameters affecting on the Ni dissolution in sulphuric acid by means of Design Expert Software. In accordance with the results, temperature, time, acid concentration and particle size were introduced as the effective parameters on the catalyst leaching. In the next step, the optimization experiments, the optimal parameters were achieved as following: Temperature = 95 C, Acid concentration = 5 Molar, Time = 255 minute, Stirring speed = 600 rpm, Particle size = 50-60 micron and... 

A brass vortex tube (VT) with changeable parts is used to investigate the effect of nozzle intakes number and diameter, distance between cold end orifice and nozzle intakes, cold end orifice diameter, main tube length and diameter on inlet, cold and hot exit temperature difference, isentropic efficiency and Coefficient of Performance. A series of experiments conducted to investigate the inlet pressure and cold fraction effect on VT performance and an optimum amount for this parameter is found. The separation performances of a VT for a hydrocarbon mixture is also investigated. Effects of nozzle intakes number and cold fraction on the gas species separation at specific inlet pressure in a VT... 

Embedded systems are employed as crucial control components in safety-critical and real-time areas such as medical devices, automobile, and aviation. To maintaining the dependability of such applications, several fault tolerance techniques have been proposed in the recent decades.In the recent years, the improvements in the performance of hardware devices lead to excessive attentions to software fault tolerance techniques. The software fault tolerance techniques can be implemented at the application code or operating system of an embedded system. Applying the fault tolerance techniques in operating system allow the designers to develop their application without worrying about the... 

The growing use of nanomaterials leads to causing harm to the aquatic environment resulting in a demand for effective methods to remove these nanomaterials from aquatic environment. On the other hand, the high cost of raw materials used for the production of noble metal nanomaterial limits their use or requires the development of recycling and recovery methods. In this study, we found that citrate capped gold nanoparticles (cit-AuNPs) could be removed effectively from waste water using aluminum chloride (AlCl3) coagulant. The effect of pH, of coagulant concentration, and alkalinity on the performance of this coagulant was investigated. It has... 

Tin Oxide Nanoparticle (SnO2) with the band gap of around 3.6 eV is one of the promising materials in various fields such as photocatalysis water splitting, pollutant removal and also biotechnology. Inorder to use this material in a visible-light rang, some promotions should be conducted.By combining SnO2 nanoparticles with the non-metalic graphitic carbon nitride (g-C3N4), a proper nanocomposite with wide range of application can be obtained. But, in order to industrialize this material, the cost of the final product is an imperative issue to consider.Here we have introduced a novel and low-cost method for synthesis of g-C3N4/SnO2 nanocomposite by using urea as a precursor for g-C3N4 and... 

In the aftermath of earthquakes, hospitals serve the critical role of treating casualties and reducing mortalities and severe injuries. A hospital must be resilient to play its role correctly after the earthquake. A resilient hospital is able to maintain its functionality at an acceptable level and provide service to the injured. In order to enhance the resilience of a hospital, an appropriate framework is needed to evaluate the hospital resilience and determines the impact of modification actions. This framework should characterize the serviceability of a hospital in terms of an appropriate metric. In this framework, the behavior of a given hospital building in the event of an earthquake as... 

In this thesis the resilience of a neural network is examined under structural perturbation.The network consists of Spiking neurons with specific dynamics or they are binary neurons and the network is non-spiking. Neural network is a multi-dimensional and multi-stable system therefore we can map their dynamical equations to effective one-dimensional equation with one parameter which shows the environmental conditions.The resilience of the system is evaluated with respect to changes in weights and edges of the network and the the resilience pattern of the system is obtained.Finally, the recovery and control methods are briefly discussed  

In this study, community resilience after a disaster is optimally enhanced for interdependent infrastructures through prioritization of recovery operations considering limited resources. Optimal enhancement of community resilience can be performed at two levels: Pre-disaster and Post-disaster. In the pre-disaster level, resilience enhancement is achieved through optimization of long-term decision making that includes optimized allocation of resources to retrofit of buildings. However, in the post-disaster response and recovery period, allocating resources to retrofit or backup systems is infeasible. Therefore, in the post-disaster level considered in this study, resilience enhancement is... 

Spent Caustic is the waste resulting from scrubbing of hydrocarbon streams with caustic solution. A thorough research on wastewater treatment to be performed at Tehran Oil Refinery in order to eliminate acid gases such as CO2 and H2S from LPG obtained from scrubbing given the fact that these gases are not eco-friendly, and the current systems of wastewater treatment are inefficient. Therefore, after investigating different methods used in Spent Caustic treatment, WAO method has been chosen to treat the wastewater at Tehran Oil Refinery. In this method, wastewater is oxidized with air at high temperature and pressure to reduce its COD. However, its high cost and operational difficulty of... 

The development of the methods to evaluate the seismic resilience of communities, infrastructures, and structures has attracted many researches. To estimate the resilience with accuracy, developing a model that can simulate the events during the recovery time is very important. For the same, modelling the aftershocks with their accumulative effects on the damaged buildings during the recovery time has been the main focus of the current study. The proposed approach to simulate the aftershocks’ effect utilizes the Monte-Carlo sampling, in which each sample includes the two following steps. The first step is the simulation of the cumulative damage caused by the mainshock-aftershocks sequence... 

The fundamental objective of this study is to present seismic hazard, risk and resilience assessment of a virtual city using sampling and agent-based simulation in two levels of refinement. In this context, hazard is the exceedance probability of ground shaking intensity, risk is exceedance probability of measures such as loss, and resilience is the ability to quickly recover after a hazard event. This study utilizes the Rtx risk and resilience assessment framework established at the Center for Infrastructure Sustainability and Resilience Research (INSURER) at Sharif University of Technology. This framework employs multiple interacting probabilistic models to quantify the risk and... 

This thesis proposes a probabilistic framework for evaluating and enhancing the community recovery process following an earthquake occurrence. This framework serves as a recovery decision support tool, aiming to enhance community resilience through the optimal allocation of limited available resources following a disaster occurrence. To this end, Bayesian network and agent-based simulation are integrated, each of which forming one of the modules of the proposed framework. The first module, namely, the Bayesian network, leads to situational awareness of the status of the community after the earthquake by fusing data from various sources. The data, such as the earthquake event characteristics... 

In this study, Lithium recovery process from lithium-ion battery was investigated by electrodialysis method. First, the cathode of the battery was leached in NMP to separate cathode from aluminum foil. Then, the cathode was leached in sulfuric acid with concentration 3.25 M and 10 volume percent hydrogen peroxide that pulp density was 55 g/L at 60°C for 100 minutes. in the next step, an electrodialysis cell was designed and created to recover lithium. And the influence of time, voltage, flow rate of feed solution, concentration of electrode solution and concentration of feed solution on process was investigated. Purpose of this project were investigated lithium ion recovery rate, lithium...