Sharif Digital Repository

In this thesis, we introduce limited-sharing multi-party computation; in which there is a network of workers (processors) and a set of sources, each having access to a massive matrix as a private input. These sources aim to offload the task of computing a polynomial function of the matrices to the workers, while preserving the privacy of data. We also assume that the load of the link between each source and each worker is upper bounded by a fraction of each input. The objective is to minimize the number of workers needed to perform the computation, such that even if an arbitrary subset of t 1 workers, for some t 2 N, collude, they cannot gain any information about the input matrices. This... 

In recent years, Rheological behavior and heat transfer of nanofluid studies have been increasing considerably and results show significant progress in this area. In this study we analyze the laboratory examination of the influence of parameters of volume fraction and temperature on thermal conductivity coefficient, dynamic viscosity of new and useful nanofluid carbon nanotube in engine oil. Most of fluid comparing to solid has lower thermal conductivity coefficient therefore solid particles increase thermal conductivity coefficient. On the other hand by adding particles, the dynamic viscosity of nanofluid also increases. Since nanoparticles have high volume ratio to surface (SSA) they have... 

Pulse tube refrigerator due to the relatively high efficiency, high reliability of linear compressor and the absence of moving parts in the cold area is known as one of the best options to generate up to one kW of cooling power at temperatures from 4 to 123 K. More recently, the use of the device at a temperature of about 150 K, makes use of it even outside of cryogenic temperature. The most important part of the device is regenerator, so understanding the nature of the flow and interaction of gas and solid network in the retrievers is necessary. In this study, Inertance pulse tube refrigerator (IPTR) is simulated using Ansys Fluent in two different conditions. In the first condition the... 

In local transportation service companies, there is a need for estimation of arrival times (ETA) for customers. These companies not having the sufficient number of active online users, they are not able to obtain a proper estimation for ETA from that data. However, there are some overseas companies that have the established user base, and provide access to necessary data with a service fee. It is possible to solve this problem using the data which they provide.In this thesis, the problem of learning a hidden graph for the purpose of aiding local companies is explained and different aspects of it are introduced. In order to tackle this problem, first we define the idea of vertex separators,... 

AdS/CFT correspondence is a suitable framework for studying strongly coupled gauge theories. It corresponds a strongly coupled gauge theory to a classical gravity theory with an extra dimension. Quark-gluon plasma which is produced in accelerators is strongly coupled. We use AdS/CFT correspondence to calculate Meson thermalization time by approximating the collisions by a sudden change of baryon number chemical potential. On the gravity side, this is followed with an apparent horizon formation on probe-brane which is the signal of thermalization  

The purpose of the study was four-fold: first to investigate the predictive adequacy of the Task-Induced Involvement Load Hypothesis which contends that higher-load inducing tasks yield better retention rates in incidental learning situations, second, to examine whether type of dictionary search could affect vocabulary retention, third, to investigate the effect of translation direction on retention rate, and finally to determine the most effective tasks. To meet these ends, six groups of EFL learners - all male, aging 19-25, majoring in various fields of engineering sciences were assigned to the study. Each one of the groups performed distinct tasks which were as follow: reading... 

In this dissertation we aim to survey the concepts and results concerning Total Domination Set. Consider graph G = (V;E). Let S be a subset of V . S is Total Domination Set in G if every vertex in V is adjacent to at least one vertex in S.Furthermore, we call S a k-Total Domination Set if every vertex in V is adjacent to at least k vertices in S. The size of the smallest Total Domination and k-Total Domination Set in a graph G is respectively called the Total Domination and k-Total Domination Number of G.Now, if there is a sequence of subsets of V like S = V0; V1; V2; : : : ; Vl = V so that for each i, every vertex in Vi is connected to at least k vertices in Vi1, S is a Dynamical k-Total... 

In this project the effect of rolling temperature on mechanical properties and microstructure evolution of a low carbon steel was studied. The steel was rolled up to a nominal strain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Micreohardnessand tensile tests were used to characterize the recrystallization kinetics. Optical and scanning electron microscopic examinations were carried out to evaluate the mechanical, grain size, and the kinetics of static recrystallization by the Avrami equation. The results indicated that the volume fraction of static recrystallization increases with the increase in annealing period. The Avrami exponent... 

Statistical studies indicate the fact that in Iran, like many other developing countries, a significant percentage of buildings are made of traditional materials and most of them are adobe buildings especially in rural areas. Furthermore, geological data indicates that Iran is located in alps-Himalayas seismic zone and exposed by destructive earthquakes and adobe buildings suffer the most damages comparing with other type of the structures. According to these explanations, this research deals with adobe buildings behavior and provides solutions for reinforcing them and improving the seismic response of these buildings. These studies include numerical modeling with finite elements methods by... 

Kanban inventory system has been applied as a tool of implementing lean production and just in time philosophy since three decades ago. By implementing kanban in supply chain which consist of suppliers , producers , distributors and consumers, real information of demands transfers upstream and materials flows downstream and integrated supply chain can be optained. Therefore a lot of mathematical models for optimizing kanban inventory system in supply chain has been developed to implement just in time philosophy and reduce total inventory cost in supply chain systems this research consist of two main section. In the first section , kanban and supply chain primary concepts are reviewed and... 

Transfer functions of some important classes of infinite-dimensional LTI systems contain semi-polynomials in fractional powers of Laplace variable , possibly in combination with delay terms or exponentials of fractional powers of . They can be observed in many systems and subjects such as biological systems, distributed parameter systems and heat flowing phenomena. Some appropriate theorems relevant to the subject of BIBO-stability are available for a large class of such systems, though many difficulties arise in applying them analytically. In this work, some parameters of the transfer functions of such systems (e.g., the coefficients of the numerators and denominators) are considered as... 

Let G = (V(G),E(G)) be a Himple graph. An independent Het in a graph iH a et. of vert.iceH no t\vo of thE-'m are adjacE-'nt. The C'ardinality of a rnaxirnnrn independE-'ut fet in agraph G is r-ailed the independence number of G and is denoted b:y a:( G). The ndependencE- polynomial of G, I(G, :r), iH dE-'fined a l:ill'l I(G.1:) = ik(G)x'l \vhere iA.(G) is the number of iwh-•pendent ::->etH of G of Hize k and io(G) = 1. Then-' is nother graph polynomial \Vhir-h is called the domination poJ:ynomial and is defined as·ollmvs. A dominating sE-'t of G is a set 8 of vertices of G so that every vertex of G is fither in 5 or adjacent to a vertex in S. The domination... 

With growth in using the Internet and entrance of online stores and internet banks to daily people life, security has become a vital part of this new world. This causes, industrial companies started to produce security devices such as fire walls for protecting network from outside attackers and Intrusion Detection/Prevention Systems (IPS/IDS) for detection of attacks inside network. IPS/IDS causes network overload due to requiring copy of packet or flow information. With introducing Software Defined Networking (SDN) architecture, there is a hope to solve the issue with combining IPS/IDS and SDN features. Therefore, we propose two novel approaches for fast network scanning and SYN Flood...