Sharif Digital Repository

This thesis focuses on the development of a flight formation control algorithm and obstacle avoidance of a UAV team using fuzzy predictive artificial potential field (FPAPF) method. One of the common methods for path generation and obstacle avoidance is the artificial potential field (APF) method. The basis of the APF method is that the UAV is attracted to the target point and repelled from the obstacles by using the potential fields of attraction and repulsion. The popularity of this method is due to its computational simplicity and efficiency. The APF method has limitations due to constant attraction and repulsion coefficients. The proposed real-time FPAPF method uses fuzzy logic to... 

The escalating demand for energy, coupled with significant environmental concerns, has underscored the importance of ground heat exchange systems as a sustainable solution for building heating and cooling. Among these technologies, energy piles—representing the most common form of thermally activated foundations—play a pivotal role in facilitating heat transfer between structures and the subsurface. Despite the rapid development of these systems, a comprehensive understanding of their thermomechanical behavior and sensitivity to various design parameters remains a critical area requiring further investigation. In this study, the coupled thermal and mechanical response of energy piles... 

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... 

Other research has examined the category of soft robots and their use in various applications, including rehabilitation, the construction of artificial limbs, and the use of high versatility for the safe capture of objects and living organisms in any exploration atmosphere. Surgical robots have always drawn the attention of researchers over the past thirty years because they reduce errors during surgical operations and the injuries that result from them. These robots fall into a number of categories, including master and slave surgical robots.In the 1990s, the da Vinci robot was unveiled as a successful illustration of this type of robot. Following that, the medical robotics sector made... 

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... 

In this Thesis we study the string theory discription of non-relativistic quantum ?eld theories.In other statement we study the duality between gravity and gauge theory with non-relativistic symmetry.We discuss that this duality works in non rel- ativistic sense.We study two kind of non-relativistic theories that one of them camefrom string theory and other model obtained by special transformation of original relativistic theory and we see that how duality can be work for these models.Also dual picture of semi-classical string in the background that found from string theorystudied.We also study the motion of particle in a hot plasma and we ?nd a sign of non-relativisic duality really works  

In last decades as the international volume of trade increased significantly, examination of the relationship between trade and economic growth is one of the interesting topics for economists and policymakers. Trade can affect performance of economics by many channels, such as trade specialization, human and physical capital accumulation, knowledge and technology transfer. In this regard the aim of this thesis is the examination of trade specialization in industries with high productivity (as one of the trade influences) effects on economic growth.In this research based on Hausmann et al. (2006), we use an economic model with two sectors: modern and traditional. This model gives a primary... 

In this thesis, design and fabrication of wide band frequency synthesizer with low spurious and low phase noise is investigted. It is very important to use an apropriate frequency synthesizer structure which would meet intended properties. In order to reach a low step size and high switching speed, using DDS is recomended; as well as using composition of DDS and PLL in order to meet a low spurious level. The main objective of this thesis is to investigate the best composition of outlet spures; so beside optimization of other properties, the main motivation has been focused on decreasing spures. Moreover, after studying Mechanisms of spures production in DDS outlet, some methods for... 

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... 

Evaluating the performance of public transport systems solely based on objective indicators may provide an incomplete picture of the reality experienced by citizens. This study aimed to assess and compare objective and perceived public transport accessibility and to analyze the accessibility mismatch between them in the city of Qazvin. To measure objective accessibility, the first standard General Transit Feed Specification (GTFS) dataset for Qazvin was produced, and a door-to-door travel time matrix was calculated. Accessibility to 14 key urban opportunities was then measured using a gravity model at the level of 105 traffic analysis zones and subsequently aggregated to eight residential...