Sharif Digital Repository

In this research, first of all, the main question of Heidegger and his epoch is investigated. If we read Heidegger along the tradition of German philosophy, then it is perceived that the problem of science is the most central subject matter standing against Heidegger. My question is this: how Heidegger reaches to this existential phenomenological view about science. Regarding that, by giving a coherent narration about a crucial problem called 'the crisis of science', in the first chapter I gave a short view to philosophies preceding Heidegger, some important of which is Dilthey's philosophy of life, phenomenology of Husserl, and south-west school of neo-Kantianism. The second chapter... 

In the present study, design and manufacturing of a connected pipe liquid fuel ramjet test platform is implemented for performance investigation of a research liquid fuel ramjet burner in the thermodynamic flight conditions. Design and manufacturing of platform systems include: the hot air supply system, the liquid fuel system and the square cross-sectional combustion chamber with the v-gutter shape flame holder. In order to determine the performance range of subsystems, calibration process has been carried out. Calibration process of the hot air supply system includes: determining of the burner inlet velocity and temperature. Also, calibration of the liquid fuel system includes: determining... 

Recently, the advent of online platforms as an intermediary tool has provided an opportunity for service providers and manufacturers to offer their services/products to consumers. Ride-hailing platforms are an example of these businesses where independent drivers and passengers are matched via an online platform. One of the most significant challenges faced by these companies is the emergence of strategic behaviors on both the demand and the supply side, which might affect the performance and profitability of the platform.In this thesis, we study the strategic behavior of drivers and its impact on their performance, using the data of one of the largest ride-hailing companies in Iran. We use... 

The main purpose of this research is to evaluate the probabilistic benefit of the implementation of second isolation layer in isolated structures to both the structure and the constructor. The innovation of this research is in the utilization of a seemingly useless part of the structure, which is the ridge, for mitigating the structure’s displacement. For this purpose, a five-story residential structure and its ridge have been isolated and modeled as an MDOF system with two degree of freedom in MATLAB software and the benefits due to the reduction in displacement and acceleration has been calculated. The results indicate 40 percent reduction in the main structure’s displacement and a benefit... 

Chattering in cutting process is one of the destructive phenomena in machining, which results in ripple of workpiece surfaces. In this phenomenon, the displacement of the tool tip moves towards instability and the tool vibration continues. Eventually, the tool jumps or breaks out with relatively large shear forces, which leads to a reduction in the rate of production and machining. Since machining processes are very widespread, phenomenological studies of chatter have progressed in the field of modeling and empirical experiments. Research in the field of modeling is mainly intended to examine the dynamics of the tool in two ways: analytic and finite element. In these methods, there are... 

In this thesis we review different approaches to the theory of value laden technology and realize that there are at least two major ideas about this. Some philosophers believe that technology is not a mere instrument and has a value laden nature. In contrast some others count technology as something neutral which contains no social or moral value. After explaining this ideas, in the second chapter we examine different models which explain the relation between technology and moral and social values and show how this values can contribute in design and use of technologies. In chapter three we talk about different methods used to steer technology in a desirable way which is in accordance with... 

Cerebral palsy (CP) is one the most prevalent neuromusculoskeletal disease amongst children. Damage in the central nervous system (CNS) causes defective growth of the musculoskeletal system during infancy to maturity, then leading to impairment of selective motor control (SMC), spasticity and sometimes contracture of musculotendinous junction. Treatment of Cerebral Palsy is limited to reduce complications. Medical procedures such as neurosurgery and orthopaedic surgeries or rehabilitation used as a common operation. Recently studies in the field of synergy directed a new path to understanding of human motor control complexity besides identification of functionality of musculoskeletal... 

Let M be a connected, compact, Riemannian manifold. Geodesic flow is a flow on the unit tangent bundle of M . This flow can be studied in dynamics prespective. for example entropy or complexity of the geodesic flow. in this thesis we will follow methods of entropy estimation or computing for geodesic flow. we will follow the method of anthony manning and Ricardo Mañe for proving such result. Maning present two results linking the topological entropy of the geodesic flow on M. we expalin how he find exponential growth rate volume of balls in universal cover as a lower bound for topologycal entropy. another theorem , Mañe represent the equlity between exponential growth rate of avrage of... 

In this dissertation, we will study partially hyperbolic diffeomorphisms. First, we are going to introduce partially hyperbolic diffeomorphisms and construct some examples. One of the important questions in the study of partially hyperbolic diffeomorphisms is their classification problem, which provides a deeper understanding of manifolds and also of partially hyperbolic diffeomorphisms themselves. We will go through this problem by examining Hammerlindl, Potrie’s [1]’s work. They have proved that a partially hyperbolic diffeomorphism on a 3-manifold with a virtually solvable fundamental group, that has no periodic torus tangent to contraction-center or expansion-center, is dynamically... 

As the traditional MOSFET is reaching to its scaling limit, it is crucial to find an alternative. Single Electron Devices have shown promising features, such as nano-scale dimensions and extremely low power consumption that can lead to new generation of integrated circuits. In this thesis we have presented an analytical study of metallic single electron devices, particularly single electron transistors (SET). We have illustrated our study with some major logic applications of SET. The main goal of this thesis is to develop simulation software for single electron circuits, comparable with the well-known commercial software “SIMON”, which can provide steady-state and transient analysis of the... 

This dissertation deals with nonwandering (e.g. area-preserving) homeomorphisms of the torus which are homotopic to the identity and strictly toral, in the sense that they exhibit dynamical properties that are not present in homeomorphisms of the annulus or the plane. This includes all homeomorphisms which have a rotation set with nonempty interior. There are two types of points: inessential and essential. It is known that the set of inessential points Ine(f ) is a disjoint union of periodic topological disks ("elliptic islands"), while the set of essential points Ess(f ) is an essential continuum, with typically rich dynamics ("the chaotic region"). One of the key results in this context is... 

Let be a sub-semigroup of SL(d;Z) which acts strongly irreducible on Rd, i.e. there is not any invariant finite union of nontrivial proper subspaces of Rd. acts on Td by homeomorphisms. We will show that under these assumptions every infinite invariant subset of Td under the action of is dense in Td. For instance, if x is a point in Td which is not rational, then x = Td. In this thesis, we will follow the method of Y. Benoist and J.F. Quint for proving such results. Their method is to prove some kind of rigidity for the stationary measures for the action of on Td. Actually, every atomless stationary measure is the lebesgue measure on Td which is invariant under all the elements of... 

The object of this study is to determine the buckling load of reinforced composite conical shells under axial compression. . Shells are reinforced by stringers and rings and the boundary conditions are assumed to be simply supported. At first the equilibrium equations are obtained using the first order shear deformation theory (FSDT), smeared stiffener technique and principle of minimum potential energy. In the following, the resulting equations which are the system of five variable coefficient partial differential equations in terms of displacement components are investigated by generalized differential quadrature method (GDQM). Finally the standard eigenvalue equation is formed and the... 

In this thesis non-ideal behavior of fluids and its effects on hydrodynamic and mass transfer in multiphase flow is studied. A numerical framework has been proposed to model the interacting effects of mixture non-ideality and mass transfer on hydrodynamics of a multiphase system using CFD methods. Using the numerical framework mass and momentum transfer in a system was simulated. The system consists of a cylindrical vessel filled with vapor and liquid hydrocarbons which selected as the benchmark. The liquid hydrocarbon is chosen to be pure Octane and the hydrocarbon in the gas phase is assumed to be Propane. Due to operating condition (T=323 K, P =445 kpa) the behavior of fluid is non-ideal... 

Non-statistical dynamics are those dynamical systems for which a large subset of points in the phase space (positive measure subset) have non-statistical behavior, meaning that the orbit of these points does not have asymptotic distribution in the phase space. We introduce two new classes of these kinds of dynamics: non-statistical rational maps on the Reimann sphere and non-statistical Anosov-Katok maps of the annulus. We then give a general formalization of the notion of "statistical (in)stability" and show how it is connected to the existence of non-statistical dynamics in a general family of maps  

Today, the pollution of heavy metals in wastewater and surface waters, which is a global environmental problem, has increased with the expansion of various industrial activities. Heavy metals cause serious health problems due to their accumulation in human and animal tissues. Thorium, is a radioactive element with an atomic number of 90 that is widely used in the optics, aerospace, metallurgy and chemical industries, in the manufacture of high-strength alloys, in UV photocells, and especially in the nuclear industry. The primary sources of radioactive wastewater include nuclear power plants, nuclear energy industry research centers, medical institutions, industrial production, universities,...