Sharif Digital Repository

Incidence of brain metastases (BM) from any tumor varies according to the method of data collection and date reported, ranging from 8 to 14 per 100,000 people per year. According to current population, about 6400 to 11000 BM Patients per year is expected. Without treatment, prognosis is dismal with survival of only 1–2 months. However, survival can be extended to 3–6 months with whole-brain radiotherapy (WBRT) and to 11 months with either surgery followed by adjuvant WBRT or surgery plus adjuvant stereotactic radiosurgery (SRS). Intravascular brachytherapy (generally iodine-125 (125I)) into the surgical cavity is another treatment strategy. 125I has been shown to confer local control... 

Flow control means changing the optimal flow behavior of the fluid in accordance with the desired targets, such as decreasing drag force, increasing the lift force or lift to drag ration, as well as manipulating the separation of the flow from the surface. So far, little research has been done on increasing the airflow performance through the active control of the trailing edge flow. Gurney flap is a great tool, and its experimental results show a significant increase lift force in the airfoil. In this study, it is possible experimentally to use plasma actuators to create microtap and garney flap artificial for enhancing the aerodynamic performance of airfoil by controlling the flow field at... 

Amount of strain has been always considered as the primary parameter affecting the microstructural and strength evolutions during Severe Plastic Deformation (SPD). However, these evolutions unavoidably saturate in large strains under deformation with constant conditions, i.e. constant deformation temperature, strain rate and strain path. In this study, effects of these factors on the microstructural and flow behavior of Ultra-Fine Grain (UFG) aluminum (AA 1050 and AA 5052) processed by Accumulative Roll-Bonding (ARB) are investigated. The flow behavior and its time-dependent aspect are evaluated up to large strains by Plane Strain Compression (PSC) and Stress Relaxation (SR) tests. ... 

In this study, utilizing the so-called “flow forming”, a cold-bonding process is developed to produce multi-layered thin-walled tubes and cylinders. In this process, which is entitled as “spin-bonding”, two layers of tubes are bonded by thickness reduction. Al/Al and Cu/Al tubes were bonded at various temperatures, thickness reductions, feed rates and roller attack angles. The bonding quality was examined by peel test, metallography and SEM fractography. Moreover, spin-bonding was accumulatively applied to aluminum tubes up to 4 cycles as a severe plastic deformation (SPD) for thin-walled tubes and cylinders entitled as “Accumulative Spin-Bonding” (ASB). Beside of experimental works,... 

In this research, it has been tried to design two controllers for a KVLCC2 tanker assuming unknown hydrodynamic characteristics and its mathematical model in order to maintain its course and speed. At first, due to the lack of an experimental model of a vessel, a three-degree-of-freedom MMG model of the KVLCC2 vessel was modeled in the SIMULINK, MATLAB, to be used as a basis for other tests and simulations. Therefore, by using the designed three degree of freedom model, all parameters affecting the floating maneuver were examined. In the next section, using the DNV standard, we designed two wind and sea current systems for system input disturbances. And finally, by using dynamic models of... 

In this project, a model which had been suggested for a lithium battery is used with the assumption of using C.N.T instead of activated carbon for the cathode. This battery include lithium foil, C.N.T and solution as anode, cathode and electrolyte. The electrolyte solution consist of lithium salt and a separator. The mathematical solving of the model consisted of using two CPM and DFM methods. In DFM method, a concentration gradient was considered as the driving force for diffusion and in the CPM method chemical potential as the driving force. Furthermore CPM method considered energy interaction between ions. Changing physical parameters of cathode and modification of model parameters... 

Despite the promising features of blockchain, such as enhancing efficiency, transparency, immutability, cost savings, and traceability, the technology is still not widely adopted across industries. This research examines the applications of blockchain technology in supply chain management, highlighting its potential benefits and the barriers preventing its full adoption in industries, discussing the existing challenges. To this end, the study proposes a multi-criteria decision-making (MCDM) framework for assessing blockchain adoption strategies. This framework is based on key factors for blockchain adoption and four adoption strategies, including single-use, localization, substitution, and... 

The low female labor force participation rate in the Iranian labor market relative to the global average and even to countries that do not differ significantly from the socio-economic characteristics of our country is one of the important questions of the Iranian labor market. In this study, we seek to answer the question of whether the economic participation rate of married women will increase if the gender gaps in wages, job findings and job losses among women and men are eliminated in the Iranian labor market. To answer this question using household expenditure and income data and labor force data, we show that between the two categories of occupations, in terms of the share of women's... 

Fatigue crack growth can have harmful effects on the reliability rotary machine. While an early warning to crack, can be used to extend the life of these expensive machines and increase reliability.Structural Vibration Condition Monitoring as a primary fault detection method, achieved to a lot amazing result and for this reason studies vibration behavior of cracked rotational shaft is a big issue for engineers of dynamic machine.In this research, first check the fault detection methods based on structural vibration condition monitoring, mode shape methods were extracted. Then by modeling rotational shaft in computer and creation of crack on it, fault detection quality of these methods have... 

It is important to provide an appropriate and economically method with technical and engineering considerations to stabilize excavated underground spaces. The necessity of this, especially for the construction of underground metro stations located in the cities which faces many problems, is more evident. In this research, it has been tried to introduce an optimal method according to the type of area for the construction of the underground station. In order to obtain stress and strain condition in structural elements and surface deformations due to different stages of excavating, numerical modeling in FLAC3D has been used. By examining the parameters that affect the sustainability of this... 

In the present study, the effects of increasing the value of shale gas production, either due to increased production or price increases, have been studied on economic variables such as employment, wage, property value and the number of births. In this regard, the data for each of these variables was used at the county level in the United States of America between 2000 and 2011. In order to estimate the desired effects, counties are divided into two types of boom and non-boom counties. The findings indicate that increasing natural gas production will lead to more employment and wage growth in boom counties than non-boom counties. Also, during the period of increasing production, the value of... 

Co-movement between inflation and nominal interest in response to an interest rate shock, dubbed neo-fisherianism, has been the subject of contentious debate since the advent of non-inflationary ZLB environment. We design an economic model rich with banking features to understand the economic responses to permanent and long-term interest rate shocks. We find that responses to a permanent positive interest rate shock depend on the monetary authorities’ speculation of the new long-term inflation rate, with the most probable outcome being a permanent increase in inflation. Responses to a long-term positive interest rate shock depict an increase and then decrease in inflation. We also discover... 

In this study, we aim to learn representations from microscopic cell images that effectively capture the features of drugs affecting the cells, allowing us to identify effective drugs for treating a disease. We employ two parallel learning paths using predictive and generative models. Specifically, we have achieved a predictive model on the RxRx19a dataset that, unlike previous models, is interpretable, optimized, and robust to dras- tic changes in drug properties. Additionally, we have developed the first generative model on this dataset, which not only generates high-quality images but also discovers a meaningful latent space. This latent space divides the representation into relevant... 

Influence of excavating the Tehran metro line 7 tunnel on surface settlement, stresses and deformations induced in Towhid tunnel is investigated using numerical modeling. Construction of Metro tunnel as the new one must be carried out without imposing any damage to the Towhid tunnel as the existing tunnel. Towhid tunnel is a set of twin tunnels along the Chamran highway in Tehran. The tunnels were constructed using sequential excavation method and lined with cast in place reinforced concrete; on the other side metro line 7 is being constructed using 2 EPB tunnel boring machines and lined with reinforced concrete segments. This research consists of the study of the effects of pillar width,... 

Foam injection for enhanced oil recovery is concerned by petroleum engineers because it decreases adverse effects of fingering and gravity segregation caused by the injected fluid .Obviously foam stability is an important factor in the efficiency of this process. So investigating it is an imperative. One of the ways that less studied and can improve foam stability is using of nanoparticles. In this project effect of nanoparticles on foam stability and displacement mechanism during foam flooding has been discussed.
Study consisted of two sets of experiments. In the first part, the static foam stability in the presence of silica nanoparticles has been investigated. Also influence of... 

Miscible displacement in fluid flowing through a porous medium plays an important role in many environmental and industrial applications; for instance, miscible displacements in enhanced oil recovery processes and pollutant spreading in groundwater. A large number of numerical approaches have been developed to solve the advection-dispersion equation that describes the behavior of miscible displacement in porous media. Most of these numerical models suffer from numerical dispersion. Random walk seems to be an effective method to overcome this problem especially in heterogeneous media. Here, a random walk model was developed and used for simulating miscible displacement in heterogeneous porous...