Sharif Digital Repository

One of the satellite time-critical launch methods is air-launch, which is considered in this research thoroughly. The Large number of important parameters of this method makes the system highly complex. In such complex systems, usual methods of design and development will not be effective. Moreover, based on systemic approaches, interfaces between different elements of a complex system have significant effects on the performance of the whole system. One of the methods for analysis of such systems is “Design Structure Matrix” or DSM. This method is based on system engineering principles and has confirmed capabilities in analysis of highly coupled systems.
In this research, the air launch... 

Samples of the V2O5 catalysts supported on nanostructures of TiO2 and γ-Al2O3 were synthesized via hydrothermal method for the oxidative dehydrogenation of propane (ODHP) to propylene. The TiO2 support was utilized in both commercial microstructures and prepared nanostructures from their corresponding salts. Furthermore,the γ-Al2O3 was also prepared from two novel methods. Moreover, the vanadium catalysts supported on hybrid TiO2 and γ-Al2O3 were prepared. The performances of the prepared catalysts were subsequently examined in a fixed-bed reactor. The main products were propylene, ethylene and COx.The vanadium catalyst over TiO2 and γ-Al2O3 had the best performance under the reactor test... 

The everyday increasing electricity consumption of household and industrial sectors across the world, and also the limited generation capacity and fuel supplies has led electricity companies, whether in private or government sectors, to focus deliberately on power generation planning, its costs, risks and constraints Because of many reasons including high efficiency, low cost of capital investment, expeditious permitting, and operation flexibility of gas-fired generating units, electricity companies prefer them to old ones like coal-fired or oil-fired generating units. Thus natural gas has gained a significant share in the portfolio of electricity generation fuel resources, and it is... 

Tolerance allocation in the recent mechanical assembly is significant because it straightly affects product performance and cost. Loose tolerances may cause the quality defect while tight tolerances can increase the cost. Thermal effects and the temperature gradients are one of the factors that caused changes in the size and geometry of the components during the performance of mechanical assemblies. This thesis proposes a new approach for tolerance design considering the thermal effects, to achieve lower manufacturing cost and good product quality. Finite element analysis is used to determine the deformation of components in an assembly. The neural network is trained using experimental... 

Correct and timely extraction of smoke is very important in fire incidents. Statistics show that more than seventy percent of fire casualties are caused by breathing toxic gases. One of the destructive factors in the operation of the smoke exhaust system is the plugholing phenomenon. In this phenomenon, due to the improper design of the ventilation system, the exhaust vent extracts air instead of smoke. The plugholing phenomenon causes the accumulation of smoke in the structure, therefore it is essential to know this phenomenon to prevent it. In this research, the plugholing phenomenon in the smoke extraction process has been investigated by the numerical simulation method. To investigate... 

One of the important tasks in machine vision is 3D structure reconstruction or depth estimation. In recent decades, methods based on machine learning have been presented, which can be used to perform this costly task more optimally. For this purpose, two branches of supervised and unsupervised learning have been considered. In supervised learning, the available data is in the form of image-depth map pairs, such as the kitti dataset. The image is fed to the network and the output is made in the form of a depth map. The cost function of this network is obtained by comparing the generated depth map and the depth map in the data set calculated by laser. In unsupervised learning, there is no... 

In the last few decades Seismic Regulations attitude’s has been undergone significant changes from various aspects. One of these aspects is entering new topics based on the latest scientific achievements. Soil-Structure Interaction terms was from such issues which had found their ways into Seismic codes as an optional effective factor. In recent years, Based on this new attitude and Scientific achievements, Soil-Structure Interaction terms entrance into Iranian seismic code (2800 Standard), is also has been studied. Naturally, applying these criteria will impact on the design and performance of structures, because of reducing effect of soil structure interaction on decreasing base shear... 

The present study seeks to focus on social entrepreneurs to address how these entrepreneurs continue to have sufficient motivation to overcome the challenges they face in the course of their careers and continue this path. This research has tried to use the concept of self-leadership - which keeps a person motivated to achieve his goals for which he has an inner motivation - to answer this question. So the main research question is how do social entrepreneurs use their leadership in the face of the challenges of their careers? To answer this question, this study used a qualitative research method with an exploratory approach and conducted semi-structured interviews with 14 social... 

In order to perform laparoscopic surgery of large intra-abdominal organs with minimum trauma on patient’s body, an endoscopic tool is designed, analyzed and fabricated in this project. This instrument is capable of passing through a 10mm incision point on patient’s abdomen and then be opened to grasp and hold large organs up to 80mm in diameter. It acts as a miniature hand with three fingers which are opened and closed parallel with each other. Using this tool, there will be no need for a 7-9 cm incision for entering surgeon hand which is required in hand assisted laparoscopic surgery method. In order to evaluate the capability of the tool in grasping and manipulating large organs, the... 

Walking on legs using orthosis for spinal cord injury patients has many advantages and decreases the physiological and psychological problems comparing with wheelchair application, however high energy consumption and early exhaustion of patients are disadvantages of orthosis usage. The most important group of orthosis for spinal cord injury patients is RGO (Reciprocating Gait Orhtosis) which a reciprocating cable mechanism links two hip joints motion. So swinging of mobile leg gets easier and stability of patient in standing and walking step increases. Regarding to existent reports about high energy consumption in walking by orthosis, this project has been fulfilled to design an improved... 

Common fracture treatments include open reduction and intramedullary nailing technology. However, these methods have disadvantages such as intraoperative X-ray radiation, delayed union or nonunion and postoperative rotation. Robots provide a novel solution to the aforementioned problems while having new challenges. The robotic system used in the study by providing more precise motion and exerting higher amount of forces makes the operation procedure more straightforward. In a normal operation 300-400 N of extension force would be needed which is fully provided by the surgen which leads to physical his/her (khastegi), by using the robotic system however, this force is simply provided without... 

In recent years, computer haptics research area have gradually grown all around the world. It deals with displaying the rendered contact properties in a virtual environment to a human user while interaction to a haptic interface. In general, a haptic interface provides essential haptic feedback information of a remote environment to a human user. The human operator, as a part of computer haptic system, will usually make an interaction by the haptic interface in a real environment which is usually limited to the end-effector of the physical device. On the other hand, the virtual tool in the virtual environment will interact by the virtual based remote environment which is generated from the... 

Sina surgical system is a telesurgery robotic system which is capable of using the conventional laparoscopic tools. In order to provide the wrist degree of freedom and increase the surgical maneuverability, a mechanism is introduced here which enables Sina to use and activate the wristed laparoscopic instrument Laparo-Angle. At first, the kinematics and dynamics characteristics of Laparo-Angle were identified experimentally. This tool contains 4 degrees of freedom, pitch, yaw, grasp and distal Roll. Activation of pitch and Yaw degrees of freedom requires a mechanism which at least has two rotational degrees of freedom to move the tool handle in a cone shape workspace with an apex angle of 36... 

A popular way for performing minimally invasive heart surgery is to use cardiac stabilizers that fix the heart during surgery. In the recent years several research works have been conducted to develop effective cardiac stabilizers. While these developments have attempted to improve fixation of the heart, there are reports indicating that a rigid cardiac stabilization may induce injury to heart muscle tissues due to restricting the heart motion in all directions. A more efficient approach than rigid cardiac stabilization might be to use a flexible cardiac stabilizer in combination with a surgical robot having motion compensation capability. The scope of this research is designing a device to... 

2D-3D image registration has been adopted in many clinical applications such as kinematic analysis of bones in knee and ankle joints. Because it is not possible to take dynamic images in 3D and 2D dynamic images such as fluoroscopic images lack spatial information. For comparing two images it’s necessary to make their dimensions the same. So in this research we prepared a code in MATLAB to generate digitally Reconstructed Radiograph (DRR) from the CT image in different positions and then be compared with 2D fluoroscopic image. Registering two images could be done either with comparing their intensities or their mutual features. We combined these two methods and developed a cost function with... 

In this study, pyrolysis features and corresponding kinetic behavior of non-metallic fractions of the paper-laminated phenol resin printed circuit boards (P-PCB) and fiberglass-reinforced epoxy resin printed circuit boards (E-PCB) were investigated by the use of simultaneous thermogravimetric analysis (TGA/DTG). The kinetic parameters of the P-PCB abs E-PCB during pyrolysis process were estimated from the experimental data by means of three iso-conversional kinetic models, including Friedman, Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) methods. The activation energy range obtained for P-PCB and E-PCB utilizing the Friedman method was within 117–594.1 and 88.42-295.3 kJ.mol-1,... 

Every year, a significant number of people around the world suffer from anterior cruciate ligament injury. Rapid and low-cost diagnosis of anterior cruciate ligament injury is important to prevent further complications as well as timely treatment. Due to the disadvantages of each diagnostic methods, the development of alternative methods for diagnosing anterior cruciate ligament injury is still of interest to researchers. Meanwhile, several studies have shown that the kinematics of the knee joint are different for injured and healthy anterior cruciate ligament. Due to the capability of inertial sensors for kinematic measurement of joints, their use to diagnose damaged anterior cruciate...