Sharif Digital Repository

Wireless power transfer provides many medical applications. Recently, power electronic devices are available with high power transmission capability at higher frequencies. This makes it possible to transfer wireless power with considerable amount of power. Due to the reductions of battery size and cost with using wireless power transfer system, this technology is introduced as one of the most interesting topics among researchers. There are obstacles in front of the progressing wireless power transfer applications. Lateral misalignment, load variations, component uncertainties in value are common in wireless power transfer applications. In order to bring this application in large scales, all... 

The propagation behavior of Love wave in functionally graded magneto-electro-elastic half-spaces with a quadratic variation is addressed. The magneto-electromechanical coupling factor, the dispersion relations, electric potential, magnetic potential and displacement are obtained analytically for both magneto-electrically open and short conditions. The effect of gradient coefficient on phase velocity, group velocity and magneto-electromechanical coupling factor are plotted and discussed. Research on the wave propagation in magneto-electro-elastic materials is still very limited. This work provides us with a theoretical foundation to design and practically apply SAW devices with high... 

An important class of applications which have been rapidly growing recently is the one that create and use time series data. These types of data sets are ordered based on the timestamps associated to their data items. In practice, traditional relational databases are unable to satisfy the requirements of these data sets; however, NoSQL databases with column-wide data structure are appropriate infrastructure for them. These databases are very efficient in read and write operations (especially for time series data, which are ordered) and are able to store unstructured data. Time series data may contain valuable and sensitive information; hence, they should be protected from the information... 

In this study, a new concrete slab stiffened by concrete pedestals and steel cables is introduced. The slab system is studied by employing both analytical and numerical methods. The steel cables are connected to the edges of slab and the concrete pedestals mounted at the bottom face of slab act as the middle supports of cables. The tension force in the cable and its inclination results in upward forces acting at the bottom face of slab. With the aims of classical theory of thin plates and the superposition technique, the problem of a simply supported rectangular slab stiffened by cables is studied analytically. The obtained results are verified by a numerical modelling implemented in SAP2000... 

The parametric study of a new introduced metallic yielding damper called telescopic damper is addressed. The telescopic damper comprises of three concentric steel pipes connected together by lead shear keys. The inner and outer steel pipes are subjected to axial loading which results in the shear yielding of the embedded lead cylinders. The inner steel pipe has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Employing ABAQUS software, the behavior of damper under cyclic loading is studied numerically. The finite element model is verified by available results in the literature. The effects of inner and outer steel pipes thickness,... 

In this study, a new type of metallic yielding damper called Telescopic damper is proposed and analyzed numerically. The damper comprises of three concentric steel tubes connected together by lead shear keys. The relative axial deformation of steel tubes under axial forces results in shear deformation and yielding in lead shear keys and dissipates energy. The inner steel tube has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Therefore, a multi-linear force-deformation behavior with two different yield plateaus is expected for the introduced telescopic damper. The multi-level yield plateaus of damper makes it effective in both low and... 

The tree structure of neuron morphologies has excited neuroscientists since their discovery in the 19-th century. Many theories assign computational meaning to morphologies, but it is still hard to generate realistic looking morphologies. There are a few growth models for generating neuron morphologies that correctly reproduce some features (e.g. branching angles) of morphologies, but they tend to fall short on other features. Here we present an approach that builds a generative model by extracting a set of human-chosen features from a database of neurons by using the naïve Bayes approach. Then by starting from a neuron with a soma we use statistical sampling techniques to generate... 

In this study, elastic analysis of a functionally graded full-space with quadratic variations under various types of loading is addressed. The elastic responses of the medium are obtained in closed-form under various types of loading including point load, concentrated moment, distributed patch load of rectangular and circular shape, normal ring load, and concentrated torsion. The displacement fields are derived by virtue of the appropriate Green’s functions corresponding to the FGMs with a quadratic variation of elastic moduli and constant poisons ratio of = 0.25 .For the special case of homogeneous medium, the results are verified with available solutions. Furthermore, effects of degree of... 

In this study the axisymmetric and asymmetric problem of interaction between a transversely isotropic half-space and various rst order shear deformation plate theories including Mindlin, Reissner and Vasil'ev are addressed. In order to improve the accuracy of solution, the surface boundary conditions of the half-space are modied.Moreover, the results compared with the exact solution and the most appropriate result is identied. The displacement Green's functions are obtained for both cases, modied and unmodied boundary conditions which can be expressed in a closed form and a numerically evaluated part. The latter is calculated exploiting Built-in numerical interrelation function of... 

In recent years, the increase in the pace of data generation and costs of maintaining personal servers resulted in the demands for cloud-based services. Map-Reduce model is a programming model for parallel computations in distributed environments such as public clouds. While this model facilitates the process of big data for customers, there are concerns that the integrity of computation is violated since cloud owners are motivated to reduce the costs. To solve this problem, different approaches are proposed in four general categories which there are constraints and flaws in each of them. These four categories are such as based on replication, watermarking, report analysis and based on... 

The rapid growth of Android operating system alongside its open-source nature has made it as the most popular operating system of mobile devices. On the other hand, regarding the increasing computational power of mobile devices, a wide variety of applications are coming to this type of devices. Meanwhile unfortunately many malicious softwares trying to keep up with other applications, are targeting this popular operating system. Therefore with regard to the fact that this type of devices usually store private and sensitive information of their users, security of mobile operating systems is considered very important. Having this matter in mind, the goal of this research work has been... 

Privacy preserving data mining helps organizations and companies not only to deal with privacy concerns of customers and regular limitations, but also to benefit from collaborative data mining. Utilizing cryptographic techniques and secure multiparty computation (SMC) are among widely employed approaches for preserving privacy in distributed data mining. The general purpose of secure multiparty computation protocols to compute specific functions on private inputs of parties in a collaborative manner and without revealing their private inputs. Providing rigorous security proof of secure multiparty computation makes it a good choice for privacy preservation, despite of its cryptographic... 

In this thesis, static and dynamic analysis of nano beams based on second strain gradient theory is presented. Due to their small sizes, nano electro mechanical devices (NEMS) hold tremendous promise for novel, versatile and very sensitive devices for different applications ranging from actuators, transducers and also mass, force, light and frequency detectors. Therefore accurate modeling and analysis of such devices has an important role in their design and performance improvement. Neglecting the size effect, traditional theory of elasticity can not be suitable to predict mechanical behavior of these systems and so, it should be used non-classical theories which include size dependency... 

The expansion of technology and the increasing use of mobile devices and smartphones have aected various aspects of personal and social life. These include the use of personal mobile devices in enterprise environments called BYODs have a number of positive and negative eects. On the one hand, it would be more cost-eective for an organization or business environment for users to use their own devices, but on the other hand, it poses numerous security and information challenges that are important to manage. These include disrupting the user’s privacy or disseminating organization information to personal devices and thus violating the organization’s security policies. In this study, a model is... 

Advanced Persistent Threats (APTs) by multi step , low-level and sometimes slowmoving behaviors try to hiding malicious behaviors. These attacks are complex, costly and the attacker violates the security policy explicitly or implicitly by distributing his or her behavior to multi agents and infiltrate trusted subjects. One of the challenges is the discovery of these attacks in the early stages of the attack and before the complete violation of confidentiality. the lack of deep intercepting of events, content with intrusion detection systems warnings, the lack of simultaneous tracking of host and network-level events and the lack of real-time processing is limitations of existing detection... 

The main purpose of this study is Performance Based Analysis of steel bridges equipped with Telescopic Dampers and also to design a suitable damper in order to improve the behavior of the structural system and, consequently, reduce the damage to the structure after the earthquake. Different models of dampers such as Buckling Restrained Braces (BRB’s), Hydraulic Dampers, Viscous Dampers, Shear Panel Dampers, Visco-Elastic Dampers, etc., are used according to their specifications along with Laminated Rubber Bearings (LRB’s) to control the structural behavior of bridge, reduce deck displacement and base shear. The result of this project is the design of a special type of telescopic dampers,... 

Smart grids are the new generation of power grids that combine the power distribution grid with the communications network. The purpose of these networks is to create a secure, two-way infrastructure for the transmission of power and information. The complex structure of smart grids, along with the inherent vulnerabilities of physical systems, old devices and protocols on the network and the need for backward compatibility, have created serious cyber risks to critical assets and infrastructures. The difference between these types of networks and conventional computer networks has made the security mechanisms developed in conventional computer networks not very suitable for these types of... 

The long-term Attacks are some special multi-level attacks which remain inside of systems for a long time to finally perform the damage. One of the most famous kinds of these attacks is Advanced Persistent Threats. These kinds of attack are low-level, distributed inside of the network and their goal is stealing information or corrupting a process in the organization. Banks are one of the most vulnerable organizations which have suffered from these attacks, so the main purpose of this research is detecting them and give warning to the security admin. The goal of financial APTs is stealing money and to achieve that, they have to create some transactions and send them to the core banking. We... 

In this research, a homogeneous elastic half-space with transversely isotropic behavior, reinforced by an isotropic thin membrane is investigated under static loading with an analytical approach. The membrane is considered as an infinite plane with a thickness of negligible and buried at the arbitrary depth from the surface of the half-space, also its flexural strength is neglected and only the in-plane stiffness is considered for it. The reinforced half-space is investigated under several concentrated and distributed static loads, which are applied to the surface of the half-space or buried at the depth of the membrane. The membrane is first modeled as a three-dimensional elastic layer and...