Sharif Digital Repository

In this work, a virtualized ball-end milling model is presented in Unity game engine environment, in which the machining process is simulated by proposing a new geometric approach. The model calculates and illustrates cutter-workpiece engagement area and cutting forces in a real-time manner. To calculate cutter-workpiece engagement, the workpiece’s top surface is considered a set of nodes. Then, using a new geometric method, the engagement area is calculated at any node on the engaging surface. Utilizing the calculated engagement area and adopting mechanistic force model, the cutting forces applied from each node on the workpiece surface to the tool’s cutting edge are calculated. The cutting... 

In this thesis we are about to simulate and control an MTBE production unit which use membrane instead of azeotropic distillation tower. At first an MTBE Production Unit with two distillation towers in separation part is simulated whit traditional method. One of these distillation towers is azeotropic. Then azeotropic distillation tower is replaced with membrane.After simulation the unit with best process indicators is selected. The goal is minimization of fixed and operating costs.In the next stage the best control loops in each unit is selected. The unit with best control indicators is determined. Control indicators are load rejection and set point tracking. All units have been simulated... 

Plantwide control plays a significant role in both industrial and academic fields. In this work, two plantwide control methodologies, “Self-Optimiaing Control (SOC)” and “Integrated Framework of Simulation and Heuristic (IFSH)”, have been applied on toluene hydrodealkilation process. Consequently, the performance of each methodology has been evaluated and compared due to the same process disturbance scenarios.The results are as follows: Although self-optimiaing control includes lots of optimization efforts, dynamic performance of the plant dose not exhibit notable differences. Therefore, Integrated framework of simulation and heuristic methodology is preferable for hydrodealkilation... 

Industrial rotating parts experiencing high angular velocities must be examined for structural integrity and strength before being installed in an operating machine. This includes performing non-destructive tests such as rotating at high speeds that generate near yield stresses in part critical points. The dangers associated with performing such tests require that these tests be performed in devices named “Spin Testers”. In this device the test is normally carried out in vacuum and within armored walls. A critical component of the spin tester is the spindle to which the rotating part is attached. Besides carrying weight of the test piece and rotating at high speeds, the spindle must be... 

Cell of fuel methanol can store fuel easily, because they can suitable for resources of energy with ambulant applications. As for with the extensive of electrical haul instruments, they attention to the use of fuel cell methanol. In this project a fuel cell methanol consist of different branches such as cathode, Anode, substrates of membrane and influx, has modeled with the form of flat three dimensional. This model consist of ambulant theorems, transfer of mass, chemistry theorems and reflexes of electro chemistry in spongy environment. As for with a little knowledge that is related to the oxidation of methanol, the first research is related to this reflex and the knowledge of mathematic... 

One of the main challenges in managing flow batteries usage is estimating their state of charge. Since The concentration of ions in the battery indicates the battery's charge and, on the other hand, the sensors for measuring the concentration are expensive, observers should be used to estimate the concentrations of the ions in the battery. This work is done by measuring the cell voltage, and finally, using the mathematical model of the battery, the amount of concentrations and state of charge is calculated. In this work, a vanadium flow battery was initially modeled accurately and mechanistically using COMSOL software to replace an actual flow battery in subsequent studies. Also, two... 

Many petroleum engineering operations, such as drilling, well completions, and workover, may cause an alteration in the properties of hydrocarbon-bearing formations, including porosity and permeability. Solid and fluid influx into the reservoir in an overbalanced pressure condition can cause permeability reduction from formation damage in the invaded zone. While the solid invasion is limited to a few inches away from the wellbore, the fluids will invade significantly deeper into the formation. Therefore, the invasion of fluids may be considered as the primary mechanism that causes the near-wellbore damage. Correct quantification of the damage is an important component for predicting well... 

Lightweight cryptography is a new area in cryptography developed as a solution to the security requirements in pervasive, low cost and lightweight systems, such as RFID networks. Due to the pervasive nature of these systems, the users’ privacy is seriously threatened while severe restrictions are imposed on computational, memory and power resources. Therefore, the conventional design rules of cryptographic primitives and protocols are not accountable here and the designers have adopted innovative methods for lightweight designs. This makes the design of a lightweight primitive/protocol a very challenging and sensitive task which is not still reliable enough. Such a trust can not be made... 

Two-phase fluid flow physics in porous media is applied in various fields. Studies have shown that wettability and surface tension, which represent fluid-rock and fluid-fluid interactions, have a significant effect on the dynamics of the immiscible displacement. Although the effects of wettability and surface tension on the macroscopic behavior of fluid flow are known, there is less understanding of it at the micro scale. Considering the essential role of wettability and surface tension in various fields, this project seeks to investigate the effects of wettability and surface tension on the movement and distribution of fluids and the dominant displacement mechanisms within the porous media... 

Multi-Scale finite volume (MSFV) method have been developed and applied for multiphase flow in porous media. The most important advantage of MSFV method is its computational efficiency. In this thesis we apply and implement this method to porous media simulation. Then, computational parameters such as coarsening ratio, effect of threshold on adaptive computation and different boundary conditions for computing basis functions are investigated. The two difficulties of sMSFV method are problems with high permeability contrast and problems with high course grid aspect ratio which are considered. In standard MSFV (sMSFV) method reduced boundary condition is used to determine the basis and... 

In this thesis, a typical dynamic model of syngas fermentation, refered as hybrid method for biofuels production, coupled with a distillation column is developed in SimDFBA. The bioreactor is simulated in MATLAB/Simulink by using Clostridium ljungdahlii acetogenic micro-organism metabolic network. Bioreactor modeling is accomplished with a bubble column reactor in both liquid and gas phases, while the separator was simulated with ASPEN. PDE equiations of bioreactor modeing are dicretized to ODE equation by using QUICK scheme of finite volume method. A new econometric optimization study for outlet gas purification through a pressure swing adsorption unit to recycle relatively pure hydrogen is... 

Layer melt crystallization is one of the most attractive and productive separation methods in the chemical industry. One of the most important coal tar components, which is present in concentration between 10 to 12% is naphthalene. One of the most commonly used techniques for producing naphthalene crystallization. In this thesis, the layer melt crystallization in a mixture of naphthalene and benzothiophene has been investigated using computational fluid dynamics. The simulation of crystallization was performed in Comsol Multiphisics version 5.6 and the thickness of the crystal layer was obtained according to the time. At first, simulation results were verified with the labroratory results of... 

Management decisions, enhanced oil recovery, and reservoir development plans in petroleum industries are based on predictions by reservoir simulation. Due to uncertainties in model parameters or engineering assumptions, the simulation results are not accurate, while they are correct. For more accurate estimation of unknown production quantities, it is required to characterize the unknown parameters and its uncertainty. By using static data alone the result of characterization is unreliable and unsure, therefore dynamic data use practically. In reservoir engineering literature, this is called “History Matching”.The ensemble Kalman filter is an optimal recursive data processing algorithm based... 

Energy and environmental crises force different countries to consider new clean sources of energy, especially renewable energies. Fortunately, Iran is located on the solar belt and has a great potential to utilize this huge source of clean, sustainable, accessible and cheap energy. One of the applications of the solar energy is desalination of salty and polluted waters. In this regard, the performance of Multiple Active Solar Stills is investigated in this research. To do so, four similar samples of this device with one, two, three and four stages, were constructed on which many experiments were conducted for 24 hours periods. Experiments were conducted in both continuous (several days) and... 

One of the most important methods of controlling discharge in water industry which is widely used in irrigation, water distribution, waste-water engineering, drainage, flood control and other water related projects, is side weir. The hydraulic behavior of flow over side weir is spatially varied flow with decreasing discharge. Various investigators have related the weir discharge coefficient as a function of main channel upstream Froude number and the fraction of weir height to upstream depth . Performance of sharp crested side weirs with extended length (as labyrinth side weir with asymmetric geometry) has been studied in this thesis. The variables for this study are height of weir ,... 

Air enterance in to flowing water is something that is commonly seen in the water conveyance systems. The mixture of Air and water that flow together create a kind of flow that is called two phase flow. This kind of flow is often seen in culverts and water conveyance systems. There are different flow patterns in two phase flow. Considering pressure fluctuation, pressure drop and pressure recovery, slug flow pattern is the most complicated pattern among all.
Sometimes a singularity is used in a tunnel; one of the singularities that are frequently used in water conveyance system is expansion transition. In this study an experimental setup is used to model two phase slug flow, which passes... 

Local scouring at the downstream of sluice gates in the erosive beds is one of the main concerns of hydraulic engineers because of the significant damage that it can cause to the hydraulic structures. It is important to control the local scour depth at downstream of hydraulic structures to ensure safety operation of these systems. Many researchers have conducted various studies to predict the maximum depth and diameter of scour hole and develop new methods in order to control this phenomenon. One way to overcome this problem is the use of apron, or non-erosive bed. In order to shorten the apron length or decrease the effect of the... 

It is well known that arrays of antennas make it possible to steer the radiation pattern without steering a physical structure. For the past few decades this has been considered for many civil and military communication systems. Recently, ultra-short pulses are considered for high resolution radars and ultra-wideband communication systems. Systems with short pulses and large antenna arrays may benefit from high resolution in both temporal and spatial domains. But the implementation of the ultra-wideband feeding circuits for such antenna arrays is a hard job even with state of the art electronics. Optical technology has been applied, successfully, to a number of radio applications such as... 

Sharp crested weirs are one of the main and oldest means of measuring discharge in water conveyance systems. Many studies have been done on sharp rectangular weirs and have provided many relationships regarding the effect of geometric parameters and various factors on discharge coefficient of the weirs.In some places, due to existence of obstacles or barriers in the channel, it is impossible to create a symmetrical continuous weir some other cases,multiple or asymmetric weirs should be used, which is the main concept of this project.Since it seems unlikely that a purely mathematical model can review the impact of the multiplicity and asymmetry of these weirs without using empirical...