Sharif Digital Repository

In this work feasibility of concentrating zinc carbonate ore from Anguran mine by froth flotation process has been studied. Potasium Amyl Xhantate and Oleic Acid have been studied as possible collectors. The initial tests indicate that oleic acid might be a better collector. Experimental were conducted to determined important factors and to optimize the process by careful control of the pulp chemical composition and flotation variables. A concentrate containing 24.9% zinc has been attained. The recovery of zinc in the concentrate is 76.1%.
 

There are many ways to color the vertices and edges of graphs, such as, rainbow connection, vertex coloring and dynamic coloring. In this thesis, in Chapter 1 we introduce a new coloring, we consider its relationship with some other colorings and we investigate its computational complexity. In chapter 1, we focus on the proper orientation number. The problem of orienting the edges of a given simple graph so that the maximum indegree of vertices is minimized was introduced in 2004. We show that there is a polynomial time algorithm for determining the proper orientation number of a given 3-regular graph. But it is NP-complete to decide if the proper orientation number of a 4-regular graph is 3... 

Concept drift is a challenging problem in the context of data stream processing. As a result of increasing applications of data streams, including network intrusion detection, weather forecasting, and detection of unconventional behavior in financial transactions; numerous studies have been conducted in the field of concept drift detection. In order to solve the problem of concept drift detection, an ideal method should be able to quickly and correctly identify a variety of changes, adapt quickly to new concepts, in the presence of limitations of memory and processing power. In this thesis, a new explicit concept drift detection method based on ensemble classifiers has been proposed for data... 

In the present work, the combination of single drop liquid phase microextraction and gas chromatography-mass detector (GC-MS) was used for determination of pesticides, Clodinafop, Haloxyfop and Fenoxyprop in natural water samples. a novel techniques based on SDME for develop in which solvents with higher density than water was successfully used. this technique could overcome some limitations of conventional SDME such as instability of organic droplet and limited stirrer rate in which result increasing the mass transfer rate and extraction efficiency. Experimental liquid phase microextraction (LPME) conditions, such as extracting solvent, stirring rate, micro drop volume, extraction time, pH... 

In this thesis, we study the dependence structure between the Tehran Stock Exchange and over-the-counter market, as the two main Iranian capital market institutions. Several constant and time-varying conditional Copula functions are used to model this dependence structure from October 2009 to August 2014. It is shown that, compared to constant conditional copulas, time-varying conditional copulas, provide a better performance. Analyzing the conditional tail dependence of these indices shows an asymmetric dependence structure. Also, investigating the dynamic conditional correlation and conditional tail dependence, using time-varying conditional copulas, reveals large variations and an... 

This study aims to evaluate aerodynamic coefficients of an airplane with air breathing engine experimentally. In these experiments, an ejector is used to better simulate flying conditions and aerodynamic interferences generated in inlet and exhaust engine. Therefore, at first, an ejector was designed for simultaneous simulation of exit cold flow and inlet flow of engine. All tests were conducted at QRC Trisonic wind tunnel and at Mach number of 0.5 to 0.85, angles of -4 to 6 deg. and for various amounts of pressure ejector and control surfaces angles. Finally, for the Mach number of 0.5, effect of roughness on the aerodynamic coefficients was examined. The results showed that, drag... 

Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during load-handling activities in the stoop and squat using a detailed musculoskeletal model,that is, the AnyBody Modeling System.Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. In addition, NLE does not include the posture of the knee during manual material handling. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their... 

Magnesium and its alloys have gained significant attention in medical applications due to their good biocompatibility. However, their widespread use has been limited by some inherent drawbacks, such as poor mechanical properties. The ZX00 magnesium alloy has been used in medical applications, including implants, due to its slow degradation rate and good ossification. However, this alloy lacks sufficient strength and ductility. The severe plastic deformation method can create an ultrafine grain structure and improve mechanical properties. In this study, to improve the mechanical properties and create an ultrafine grain structure, the multi-directional forging process was performed on... 

This thesis investigates various modulation recognition systems both in analogue and digital forms. We are looking for a recognition technique considering practical implementation issues. To recognize the modulation, the career frequency is supposed to be known and a bandpass signal is received. Besides, we investigate some digital Automatic Modulation Recognition (AMR) methods. The techniques based on the features of the signal have less computational complexity compared to Maximum Likelihood (ML) techniques; hence they are more desirable for practical implementation. In this project, analog modulations are implemented using C++ software. For the convenience of users, here, two graphical... 

In this thesis, a new non-linear control synthsis technique (θ - D) approximation) is discussed. This approach achieves suboptimal solutions to a class of non-linear optimal control problems characterized by a quadratic cost function and a plant model that is a_ne in control. An approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation is sought by adding perturbations to the cost function. By manipulating the perturbation terms both asymptotic stability and suboptimality properties are obtained. The new technique overcomes the large-control-for-large-initial-states problem that occurs in some other Taylor series expansion based methods. Also this method does not require excessive... 

Spinal diseases are prevalent and costly. Excessive mechanical loads on the spine play a crucial role in the etiology of back disorders. To estimate spinal loads one needs to calculate unknown muscle forces through either an optimization or EMG-driven approach. Both approaches involve several assumptions and simplifications regarding anatomy of muscles,mechanical properties of the spinal tissues, and estimation of the muscle forces. An alternative approach is to estimate spinal loads through effect of muscle forces, i.e., kinematics generated by muscles rather than forces generated by muscles. The present study hence aims to estimate spinal loads using a detailed finite element (FE) model of... 

Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration... 

The importance of aircraft mass properties, including mass, center of gravity position and moments of inertia, and the effect of these parameters on the aircraft performance, stability and control is clearly bright for aviation science specialists. The ability to in-flight estimation of the aircraft mass properties in all flight conditions is a powerful technology for improving conditioned based maintenance systems, automatic flight control systems, flight safety, airplane performance, flight path planning, air traffic management, cooperative and formation flight management, facilitating investigation of aerial accidents caused by uncertainty of the mass properties, and increasing...