Sharif Digital Repository

concrete-filled steel tube offers many practical advantagescompared withconventional structural systems. The concrete infill provides stiffness and strength in compression and restrains local and global buckling. The inelastic deformation capacity of the CFT system is increased by the confinement of the concrete fill by the thin, ductile steel tube, and this significantly contributes to the seismic performance.
In this research, Formation and development of plastic hinges in CFST frames using pushover analysis was investigated. Different frames with rectangular and circular column and I beam weredesigned and Using nonlinear finite element analysis, interaction between steel and concrete... 

Reinforced concrete (RC) column in building often needs strengthening either due to defects in the column themselves, having to support higher loads than those foreseen in the initial design of the structure or as the result of ageing or accidental damage such as earthquake force. The use of FRP wrapping, steel caging or reinforce concrete jacketing for this purpose is now a common practice in many countries throughout the world. Even though a considerable number of researches have been conducted on retrofitting methods during past years, but very limited researches have been done to compare these methods. This research has investigated the effect of jacketing from different views. The... 

One of the methods to detect an unknown environment, is using the visual information about the environment. In this problem, we have an unknown two-dimensional environment consists of a set of edges and vertices that the geometric positions of vertices is not specified and only the combinatorial structure of the environment is available. In addition, certain information such as visibility of two vertices in the environment is known. The goal is to recognize the geometric shape of the environment with this information.This problem has many applications in Robotics particularly in dynamic envi- ronment where objects are moving.
In this thesis, we examine this problem in different conditions... 

Optomechanical systems have attracted much attention over the last decades, especially as a macroscopic lab for observing quantum mechanical effects . In this thesis , optomechanical quantum memories are studied . In p articularl , we study cooling of the mechanical resonator down to its ground state, which is the necessary condition to obtain a good quantum memory and also explore the limitations of cooling and storing protocols . Quantum state of light can be stored in the mechanical mode of the system by optomchanically induced transparency effect (OMIT) . This effect is formally equivalent to electromagnetically induced transparency effect (EIT) which is seen in an ensemble of... 

Modeling is one of the most important steps in analysis and design of structures. Most of the time behavior of floor diaphragms is assumed completely rigid in their plane in order to simplicity in practical design. Although this assumption leads to acceptable results in analysis and design of conventional buildings, erroneous results may assess in some particular buildings—for instance narrow buildings with stiff end walls. Accordingly, behavior of these buildings in future earthquakes opposes those were predicted in design phase, and they are so vulnerable since in-plane deflection of floor diaphragms are striking which cannot be ignored. This thesis investigates the significance of... 

Many industrial systems have on/off actuators. Traditionally, these systems are controlled using traditional control methods, like PID controller. The performance of this controller is not ideal for these systems, especially in term of transient response and power consumption. Due to the large number of constraints for these systems, to improve the performance of them, it is necessary to use the model predictive control technic. The decision variables of these systems are integer, hence it is necessary to develop the model predictive control method based on integer programming, which is the subject of this thesis. The main challenge in the development of this model predictive control method,... 

Temporary or permanent overload commonly occurs in soft real-time systems. In such situations,the scheduler cannot guarantee the completion of all tasks prior to their deadlines.Hence, some tasks are usually aborted before or during the execution with the aim of maximizing system utility. For this purpose, time-utility function (TUF) of tasks is used to determine how to maximize the accrual utility of the system. Tasks which can provide more utility are more preferable for execution. Previous works on utility accrual maximizing algorithms have not considered memory allocation in accruing utility of soft real time systems. In this thesis, we present an online scheme for multicore embedded... 

We design a new algorithm for clustering data streams in any fixed di- mension, that use the framework of core-set to summarize data, in order to reduce the complexity of computation. Clustering is to separate data into distinct sets called clusters, which objects in the same cluster has the most similarity and objects in the different clusters has the least similarity.This problem has many application in the areas such as: machine learning,image processing, financial and stock transactions. Data stream has recently emerged as an important concept because in many applications, data is inherently streaming over a network or the data base is extremely large and sequential access is way faster... 

Due to recent advancements and wide usage of location detection devices, huge amount of data are collected by GPS and cellular technologies which exhibits moving objects trajectories. Using this information, it is possible to track a set of objects over a long period of time, as happens for instance in studying animal migration. Always, in these situations it is undesirable or even impossible (due to process and storage limits) to store the complete stream of positioning data. Then, simplifying a trajectory as a data reduction technique is the option for resolving such problems. Moreover, there is an increasing interest in queries capturing ”aggregate” behavior of trajectories as groups like... 

This thesis is concerned with an optimal trade-off between communication overhead and the number and size of neighborhoods in a distributed optimal control technique for large-scale systems that is based on the Jacobi iteration and two-layer architecture for communication. Although this method efficiently reduces computational overhead, continuous and proper data transfer between subsystems that are very often far from each other, is required to achieve an acceptable performance. However, limited transmission bandwidth and short communication range result in significant communication overhead. This causes significant time latency between measurement and applied calculated control actions,... 

Given the increased competition in supply chains and enlargement of their scale along with increasingly significant role of distribution systems, design and optimization of novel systems with comprehensive approaches in a timely manner has become important more than ever. One of such modern, efficient systems is cross docking in which the distribution network is omitted and thus operations are carried out faster and the productivity is increased. In this system, processes like packaging is done in cross docking and the goods and products are directly sent to customers. This study investigates a long-term and a short-term approach to the design of in two distinct problems. In the first... 

Single-layer steel grid shell structures are a good structural solution to new buildings by specific properties that are required by long-span structures and provide at the same time the opportunity to produce immense verity of design shapes and free form architecture; complex curved surfaces expect to be covered with low weight material. A grid shell is essentially a shell with its structure concentrated into individual linear element in relatively thin grid compared to the overall dimension of the grid shell. This research investigates single-layer grid structures with emphasis on design of load details. The application of single-layer for transparent structures enhances use of glazed... 

Technology scaling allows integrating multiple cores onto a single chip to make the mainstream for advanced embedded systems. However, technology scaling is envisaged to aggravate the reliability of on-chip systems due to increasing transient fault rate due to lower voltages and shrinking transistor dimensions that lead to smaller critical charges. Transient faults are typically resulted due to high-energy particle strikes in hardware and manifest as bit flips. Multi-core systems provide a great opportunity to implement reliability mechanisms such as redundant multithreading (RMT) and process level redundancy. Task replication (e.g. RMT) is a well-established technique to achieve high... 

VLSI technology scaling has resulted in the integration of a larger number of cores in a single chip in successive technology nodes, offering a great potential to realize task-level redundancy for reliability enhancement in safety-critical applications. However, since battery technology no longer advances commensurately with integration density, multi-core platforms may have limited utility in battery-powered embedded systems. In this thesis, we propose an energy-budget-aware reliability management (enBudRM) method for multi-core embedded systems featuring hybrid energy source (with renewable and non-renewable energy sources). Our method is composed of two phases. In the offline phase, we... 

Project is defined as all activities with a definite beginning (start) and end (finish) aiming to achieve a defined target through defined resources. Literature reviews in the field of project management have shown the importance of project management capabilities for evaluation and optimization. There are many factors in project management which can lonely disrupt the timing and progress of the project. One of the most important factors that in effective and unfortunately has been less measured due to its intangible characteristic in the project is known to be the "human factor". This factor is involved from the first day a project starts and will continue till the end of the project.... 

Spin-Transfer-Torque-RAM (STT-RAM) has recently been widely accepted as a promising replacement for SRAM technology through the technology scaling due to its high density, zero standby power and comparable-to-SRAM read access latency. However, there are two major obstacles to use STT-RAM, namely, high write access latency and energy. In this study, we propose two approaches to solve these challenges in embedded systems. The conventional latency of the STT-RAM write operation is 10ns and lowering the write latency causes the required write current exponentially increase, leading to a larger memory cell area and a shorter memory lifetime. As the first proposed method, we have assessed the... 

In recent years, in order to investigate the structural performance in seismic zones, concrete column reinforcement and observing their behavior under cyclic loading have attracted considerable attentions. The ductility and energy absorption capability of structure play an important role in structural performance against earthquake and consequently its failure patterns. A new chapter of these investigations has begun by the reinforcement of the concrete members, a major part of which is concerned with the confinement of concrete members in order to increase their ductility and energy absorption against the forces induced by earthquake. In this study, three prominent methods of concrete... 

The main problem of steel-reinforced concrete structures is corrosion of steel reinforcements which leads to premature failure of the concrete structures. This problem costs a lot annually to rehabilitate and repair these structures. In order to improve the longterm performance of reinforced concrete structures and for preventing this corrosion problem, Fiber Reinforced Polymer (FRP) bars can be substituted of conventional steel bars for reinforcing concrete structures. This study is a numerical study to evaluate structural behavior of the simply supported concrete beams reinforced with FRP bars in comparison with steel-reinforced concrete beams. The commercial Finite Element Modeling... 

Many embedded multicore systems can benefit from a memory hierarchy to bridge the processor/memory speed gap. Embedded systems usually utilize a cacheless architecture to avoid the unpredictable behavior. Unlike caches, scratchpad memories (SPM) are software controlled and hence the execution time of applications on such systems can be accurately predicted. Scheduling the tasks of an embedded multicore application and partitioning the available SPM budget among these cores are two critical issues in such systems. Often, these are considered separately, such a decoupled approach may miss better quality schedules. In this paper, we present an integrated approach to task scheduling and SPM...