Sharif Digital Repository

The manufacture of ultra high strength materials has always been a target for aerospace and transportation industries. Currently, the limitation of energy resources even makes this goal more serious. Nowadays, more than 50% of total extrusion products are made from Al alloys and around 90% of them are the 6000 series alloys. Therefore, regarding to high strength, low weight, and hardening aluminum AA6000 alloys capabilities can play a major role in fulfilling this task. Over the last decade, a number of techniques collectively referred to as severe plastic deformation (SPD), have emerged as a promising approach for the production of bulk ultrafine-grained (UFG) nano-structured materials.... 

In recent years, requirement engineering and goal modeling have gained more attention among different organisations. Therefore, different methods have been designed to discover stakeholders’ requirements and translate them into process and organizational goals. Various goal models have been introduced to represent these goals and their relations towards each other. Still, these methods are manual representations of different process scenarios and do not relate to the actual behavior. In 2014, Map Miner Method (MMM) was introduced to discover intentional process models from event logs. MMM uses Hidden Markov Model (HMM) as a means to represent the process as a map model of strategies and... 

Recommending routes to city taxis in order to improve their performance in finding passengers can reduce traffic, pollution and waiting time for passengers, as well as this, increasing the efficiency of taxis can increase their income. In this study, by analyzing trajectory data obtained from 536 taxis in San Francisco over a period of one month, we generated networks of cells, each of which has time-dependent characteristics such as the probability of finding a passenger, the capacity of each cell, or the amount of demand exists is in the cell and the average speed of passing through that cell. also, the connections between these cells in order to make more use of the experiences of taxi... 

Soil-Structure Interaction (SSI) has been widely studied theoretically and experimentally due to its importance effects on the responses of structures. In experimental studies, acceleration responses recorded during previous earthquakes are generally used in order to investigate the contribution of underlying soil to the response of soil-structure systems. Since acceleration responses are affected by higher modes of vibration, studying the effect of SSI on dynamic characteristics of higher modes are of great importance in these studies. However recent theoretical studies indicate that the influence of SSI on the higher vibrational modes is very much dependent on the behavioral model (bending... 

The purpose of the present study is to develop neural network estimation method for hybrid or panel data which have a combination of two cross-sectional and time series structures and because of the features of both structures, their use in different sciences offers many advantages; and the analytical methods for this data structure are also different from other one-dimensional structures, so different and specific regression models are presented for this data structure. However, in the artificial neural network method, modeling the development for this data structure is neglected, so in the present study, using the concepts of panel regression methods and their application to the... 

One of the utmost important factors during salvage operation of drowned ships is raising velocity. Uncontrolled raise is a dynamic phenomenon which can lead to the sudden tensions, collapse in airbags or ships. Studing this issue helps the engineers which kinds of problems are more important during salvage operations. This study focus on modeling and analysis of raising movment of the ship with FLOW-3D and ABAQUS software.
In FLOW-3D environment, hydrodynamic analysis of rising movment of drowned ship has been done. We should mention that applied forces and velocities and other parameters from the FLOW-3D output should be passed IMCA Criteria to avoid uncontrollable raise. In ABAQUS... 

Profile Monitoring is a new research topics in the field of statistical process control. In many applications of statistical quality control, sometimes quality of a process or product described by a relationship between a response variable and one or more independent variables.The researchers call this relationship profile. The study seeks to demonstrate that monitoring profiles In addition, the industry can be effective in medical field and improves control of the patient's condition by a doctor. Profiles are usually modeled with a linear regression equation, non-linear or polynomial. finally, the results of this study, using actual data, models and methods to predict and control... 

Two experimental models were designed and tested to extract energy from vortex induced vibrations of a elastically mounted one degree of freedom rigid cylinder in the Reynolds range of 120000 < Re <220000. In the first model the amplitude and frequency of the movement was measured then a second model was designed to be tested in the Emam Hossein marine laboratory. The model was designed in a way that many of its properties like mass ratio, spring constant and damping coefficient were able to be altered. In this study the vortex induced vibration of an elastically mounted cylinder was scrutinized in high Reynolds and very low mass ratios for the first time and an amplitude ratio of 2.49 were... 

As a method of cancer treatment or improvement of cancer-related complications, external radiation therapy is prescribed by physicians, in case of detection of a tumor in a region of patient’s body. Over time, various techniques have been developed for external beam radiation therapy. Among which, Intensity Modulated Radiation Therapy (IMRT), due to its ability to adjust the intensity of radiation beams, has a higher capacity to generate appropriate dose distribution based on tumor size and volume and it is one of the most widely used techniques in cancer treatment centers.The core process in treatment planning is using appropriate computer algorithms which results in posing enough damage to... 

The aim of Emergency Medical Services (EMS) is to provide fast medical care and to transport patients to hospitals at the earliest possible time, so as to reduce injury and fatality rate. Healthcare managers try to improve healthcare systems by reducing the response time to demands. In this thesis, we present mathematical models for the problem of location and relocation of emergency vehicles after the end of their service time or after they have returned to a hospital. We believe that implementing these models can help managers improve the performance of emergency medical services. In the first part of this study, we present a two-level deterministic optimization model considering demand... 

Supplier selection and order quantity allocation problem is one of the most complex making decision problems comes into account. In the past, supplier selection done based on criteria such as price, quality and delivery time. Today's supply chains with the aim of expanding business activities and improving their performances, Follow process such as outsourcing, product development, and selection of multi-supplier strategies. This conditions will bring opportunities and threats for supply chains. One of the possible risks to supply chains are disruption risks and disruption has been a great concern in the past decade and disruption of suppliers are one of the new topics that have recently... 

At the present, End-stage renal disease(ESRD) is the ninth-leading cause of death in the USA.according methods of medical treatment for End-stage renal disease (ESRD), transplantation is the most viable renal replacement therapy for ESRD patients, there is a disparity between the demand for kidneys for transplantion and the supply. Incompatible inblood-type and antigen matching between patient-donor pairs is cause of shortage in disparity between the demand and the supply.paired kidney exchange of kidney among incompatible patient-donor pairs.PKE can be solve many difficulties in matching patient with incompatible donors. Kidney transplant surgeries in PKE must take place simultaneously... 

Marine current power has been utilized in recent years as one of the most foreseeable renewable energy sources. In this study a multi-objective hydrofoil optimal design is carried out for use in marine current turbine in order to improve hydrodynamic performance due to low speed current in Qeshm channel. A particle swarm optimization code using FORTRAN is developed and coupled with XFoil software as flow solver that is based on panel method. B-spline curve is used to parameterize the hydrofoil shape and the coordinates values of the control points are designated to act as optimization parameters. Validity of flow solver examined by comparison made between computed data against experimental...