Sharif Digital Repository

In this study, the effect of the Cu interlayer thickness was studied on St52 steel. Specimens with different thickness of the interlayer, were subjected to 1150 °C at different times. Isothermal solidification was completed for the thickness of the 50 μm, 30 μm, and 10 μm in 30, 25 and 20 minutes. Afterwards, homogenizing and dual-phase heat treatment were used for 75 minutes at 730°C. Optical microscopy and SEM were used to analyze the microstructure of the joints. Mechanical properties of the joints, including micro hardness of different parts of the joint and also shear strength of the joint zone were studied. The results show that after homogenizing treatment, microstructure and harness... 

Software product line (SPL) engineering offers several advantages such as reduced costs, high quality and less time to market in development of family of software products. The goal of software product line is systematic and effective development of a set of software products which share common and managed set of features. Software product line testing has its special challenges such as scalability and variability, and has significant importance due to the importance of quality in software product line and enormous number of possible products. Most of the popular methods in this domain have shortcomings such as having seam between development and testing processes, limited application scope... 

Rehabilitation science has been proved that, in most cases, manipulation of injured body part, repeatedly, can help in returning the performance of that part. So robots can be useful for rehabilitation applications. Rehabilitation robots can record physical parameters such as position, velocity and force, so can play important role in developmentof making decisions on exercise types. Among the existing robots, cable-driven robots have specifications such as vast workspace, low cost, flexibility and light weight which make them suitable for rehabilitation applications.
The purpose of this research is kinematic design of a multi-link cable-driven robot for arm rehabilitation.In the most of... 

Dynamic positioning system is a controller system used to maintain the position and heading of a vessel with no use of anchors, jack ups but only using the propellers installed on the vessel. A vessel has six degrees of freedom, including three rotations and three transfer. In dynamic positioning systems, the vessel is controlled only on the horizontal plane such that its position and heading are controlled according to predetermined values. To achieve this, position and heading of the vessel is determined and the controller system computes the direction and required power of each propeller. Preliminary systems utilized PID controllers. As the control science has advanced, model based... 

Traffic accidents around the world kill a large number of people every year, and their lightest consequences are temporary disabilities for citizens. According to the statistics, the number and severity of accidents have been growing, due to the expansion of cities and the human population there, and this increases the need to pay attention to traffic safety. One of the substantial subcategories of traffic safety research is public transportation. However, limited studies have been done in this field. One of the main modes of public transportation are buses, which bring more risk of accidents to passengers, due to their size and higher passenger capacity compared to passenger vehicles.... 

Freight transportation by trucks plays a critical role in economic development and shaping human life. A significant portion of the total and operational costs of countries is accounted for by transportation, and efforts to optimize it have always been considered of utmost importance. One of the emerging technologies aimed at transforming traditional transportation is vehicle automation. Due to its more uniform nature compared to urban transportation, road freight transportation has greater potential for adopting this technology. Numerous studies have addressed this issue; however, the assumption of fixed variables and the lack of an optimal program for the gradual transition from... 

Because of severe weather events (such as floods and storms), transportation infrastructures are directly and indirectly damaged, which may cause many undesirable economic and social losses for people and cities. Among various severe events, flood is known as an important factor in the breakdown (closure of roads and bridges) of the components of the transportation network. Evaluating the performance of the city's road transport network against flood events leads to a better understanding of the network's condition and allows decision-makers to identify the weaknesses in the system and reduce potential damages as much as possible. In this research, with the aim of investigating the... 

Among motorized vehicles, motorcycles are recognized as a common mode of transportation in countries with low to moderate income. Iran is also one of the countries where motorcycles are considered a primary means of transportation. However, in recent years, motorcycle accidents have sharply increased, with 30 percent of accidents in Iran involving motorcycles. This highlights the importance and necessity of taking measures to enhance safety and reduce motorcycle accidents in Iran. In this study, data on intercity motorcycle accidents in the provinces of Khorasan Razavi, Isfahan, Qom, Mazandaran, Gilan, Hamedan, Hormozgan, and Ilam were used. The main objective was to identify and compare the... 

This thesis examines the accessibility gap between different modes of transportation in Tehran Province, with a particular focus on public transportation and cycling. The main objective of this research is to calculate and analyze accessibility indicators to various land uses (such as commercial, service, and recreational) around metro stations using two modes of travel: cycling and bus-walking. The study utilizes simulations in Python and geographic libraries to compare these two modes of travel based on four key accessibility indicators: 1) nearest Opportunity, 2) cumulative opportunity, 3) average distance, and 4) gravity-based accessibility to measure the accessibility gap between the... 

Politicians and urban planners aim to improve citizens' overall life satisfaction. Researchers have offered various definitions of life satisfaction, making it difficult to provide a specific definition. However, life satisfaction can be seen as an assessment of different aspects of life. The method of travel and transportation factors undoubtedly play a crucial role in this assessment. Due to personal and social constraints, users' behavior in transportation can either may or may not align with their attitudes. This behavior leads to the categorization of users into two groups: consonant and dissonant users. Consequently, planning and policy-making to increase life satisfaction will differ... 

With respect to the introduction of bio-material into cells (transfection) , microinjection is a highly efficient technique amongst existing methodologies. In cell injection, a manipulator injects the needle into a cellwhich is hold by a pipet mechanism. The moving range for the needle in this operation is of centimeter order and the resolution for the needle tip should be less than the cell’s diameter. In this thesis a Stewart system is used as for the manipulator. Stewart systems are used in flight simulators systems for decades, as mechanisms which are capable of providing multi-axis movements. In high accuracy positioning and multi-axis applications Stewart systems are highly reliable.... 

In this research, a dashboard has been developed to support decision-making in the integration of freight companies. Freight companies usually consist of a limited number of vehicles due to the high cost of vehicles, while the fixed costs of a freight company constitute a significant part of that company's total cost. Therefore, if these companies are merged, their total cost will be substantially decreased. Moreover, under particular demand levels, the integration of freight companies reduces the mileage, travel time, and the number of required cars. Therefore, the integration of freight companies not only reduces fixed costs but also reduces other costs including greenhouse gas costs by... 

In recent years, energy storage systems have received widespread attention from researchers to increase the reliability of the power grid. These systems have different types that compressed air system is of special importance due to its high stored energy and long life. In this system, the surplus of electricity generated from renewable energy sources or grid electricity at low power consumption is compressed and stored in a tank. When there is a need for power consumption or peak power consumption, compressed air will generate electricity by passing through the turbine and will help the network. Large-scale type of the system requires special geographical location for air storage; for this... 

Various public transportation types, e.g., Trains, Buses, and Airplanes, are susceptible to damages made by the impacts of the external objects, which are typically classified as low to medium velocity impacts. This problem reveals the significance of investigating the effects of impact on thin-walled structures, which are the main components of these vehicles' bodies. Owing to the controllable rheological properties of the Magnetorheological fluid with respect to the magnetic field, it can be utilized to control the structure exposed to impact adaptively and minimize the damages. Due to this purpose, sandwich structures such as sandwich beams and plates, thanks to their extended response... 

The purpose of this thesis is designing and implementation of a Carry Skip Adder using CMOS traditional technology and Gate Diffusion Input technique (GDI). I present a carry skip adder (CSKA) structure that has a higher speed, lower energy consumption compared with the conventional one. The Gate Diffusion Input is a novel technique for low power digital circuit design. This technique reduces the power dissipation, propagation delay, area of digital circuits and it maintains low complexity of logic design  

Pulse compression techniques such as linear frequency modulation (LFM) and phase-coded pulse are an active research topic in radar systems, spread spectrum communication applications, etc. Pulse compression technique is employed to achieve high range resolution with enough low average power. A problem in pulse compression is masking of small targets by the range sidelobes of large nearby targets. Furthermore, the range sidelobes may be detected as separate targets and thus increase the false alarm. The most popular waveform among pulse compression techniques is the LFM (also known as chirp). However, the LFM waveform is susceptible to electronic warfare; hence using the biphase coded... 

Software systems often rely on external libraries and tools for their construction and execution. These dependencies can exist in multiple versions and configurations, posing challenges for software development and maintenance. While a software application may function correctly with a specific version of a dependency, compatibility with other versions is not guaranteed. This lack of compatibility can make updating legacy systems a complex and costly endeavor, as many libraries have versions that are incompatible with one another. Furthermore, failing to update dependency versions can leave software vulnerable to security risks and prevent it from running in newer environments. The sheer... 

Rehabilitation usually involves physical therapy, occupational therapy and counseling for the patient's morale to help to restore his power and performance. Considering the economic outlook and the costs of rehabilitation methods and due to the increasing prevalence of stroke and the need to recover the patients in a short period, only the use of robotic systems opens the door to the medical community. Since a large rehabilitation robots designed and built and each been used according to their advantages and shortcomings. In this project, the major shortcomings examined and exoskeleton designed on two major features including portability and covering shoulder workspace. Shoulder movement was... 

The control approaches in Exoskeletons are different from Autonomous robot. Because the Exoskeletons are in connection and interaction with the user. On the other hand they can use the wearer’s abilities such as intelligence, sensory organs, self-control and etc. Therefore, one of the most important parts of exoskeletons control algorithms is its interaction with the user. This part should recognize the goal and purpose of the wearer such as stopping, walking start, change in stepping and direction and etc. properly. Utilizing these algorithms properly, one can reduce the muscle activities and energy consumption up to 20 percent [1]. This investigations demonstrate the importance of the...