Sharif Digital Repository

One of the best methods of gait analysis is to use analytical models. In this project, first, the normal human gait was simulated using a two-dimensional biped model with 7 segments, i.e., a HAT segment representing head, arms and trunk, and 6 segments representing thighs, shanks and feet of the two legs. The foot-ground contact was simulated using a five-point penetration contact model. The elastic impact and friction effects are considered in the ground reaction force modeling. Optimization of the normal human walking model provided constant coefficients for simple PD controllers’ (driving torque) equations that could reasonably reproduce the normal kinematical pattern. Then, in the second... 

Nanopositioning systems are devices with the ability of moving objects within nanometer resolution. In the recent years according to the advancements in the nanotechnology fields, there is an urgent and growing need for these systems as precision motion drivers. In the most of the nanopositiong devices some active materials such as piezoelectric elements are widely used as actuators. Piezoelectric materials can generate a mechanical deformation proportional to the applied electrical field. Therefore, theoretically these devices have the ability to set the desired position with the infinite precision.Design, optimization and fabrication of an ultrasonic piezoelectric motor are performed in... 

Wide lands in IRAN are covered by the “Hydro – Collapsible” soils. These types of soils possess high apparent shear strength in their natural condition but are highly susceptible to volume collapse upon wetting. This behavior is generally attributed to their open, unstable soil fabric and their weak inter-particle bonding forces, which together yield a soil void structure that is susceptible to collapse.
Previous studies rarely investigated the roles of stress state level, matric suction and stress path on the hydro-mechanical nature of the collapse phenomenon. Also most studies dealt with conducting laboratory tests on remolded soil specimens through which the role of natural soil... 

Collapsible soils, such as loess, found naturally in unsaturated conditions, constitute a group of problematic soils that experience sudden volume reduction due to an increase in moisture content, external loading, or a combination of them. Numerous cases exist in nature or engineering projects where these soils are subjected to anisotropic stress states. Therefore, studying the hydromechanical behavior of unsaturated collapsible soils under anisotropic stress conditions holds significant importance. To date, extensive research has been conducted to examine the behavior of unsaturated collapsible soils using conventional or unsaturated oedometer, direct shear, and triaxial devices. However,... 

We study the general nonlinear integer programming problem. We consider two general classes of this problem: nonlinear integer programming problem and mixed integer nonlinear programming problem (MINLP). We explain the basic concepts for solving these problems and describe common methods for solving them, including branch and bound, Benders decomposition and outer approximation. Furthermore, we introduce two methods based on using penalty methods. Penalty based methods, by using appropriate penalty functions, convert a general nonlinear integer programming problem into a sequence of nonlinear programming problems and these problems are solved by a global optimization algorithm. Computational... 

Permeability is an essential parameter used for reservoir evaluation, simulation and management to optimize oil recovery. The conventional approach to estimate reservoir connectivity, conductivity, sweep efficiency and other critical information for decision-making is to build detailed geological models, which are then upscaled to a coarser grid where flow simulations are run. However, this takes many hours to be carried out even for a single realization practically. In practice, a very small number of realizations are considered and consequently the true uncertainty in the results is very poorly estimated. In this study, a statistical model of isotropic overlying sandbodies is used to... 

Metabonomics is a quantitative measurement of time dependent metabolic interactions for living systems in response to the pathological or genetic variations. NMR spectroscopy has emerged as a key tool for understanding metabolic processes in living systems. In this project, the study of metabolomics was performed as classification and regression on samples of parkinson’s disease, multiple sclerosis disease, celiac disease and crohn’s disease. In classification part, various methods were applied using optimal parameters.classification methods in Parkinson’s disease, multiple sclerosis disease, celiac disease and crohn’s disease were RF, CART, PLS-DA, RF and RF respectively. Based on the... 

Gravity dams are solid concrete structures that maintain their stability against design loads from the geometric shape and the mass and strength of the concrete. Because of their critical role in supplying portable and agricultural water and problems which would happen if they broke, it is required to consider their stability and keep them in safe conditions. They should be able to continue their function after a disaster such as earthquake. But most of them are aged dams with some have been built near faults. Indeed, there are some concerns regarding the performance of these dams under the effect of seismic loads. This research deals with performance evaluation of concerete gravity . The... 

Soil nailing is an in-situ technique of mechanically stabilizing soil masses which has been used in France, Germany, United states, and recently in Iran. A review of literature shows that Soil-Nailed walls have performed well during strong ground motions in comparison with the gravity retaining structures. After the 1989 Loma Prieta earthquake, minor signs of distress or corresponding deformation were found on the Soil-Nailed walls, indicating excellent performance of such structures during moderate and strong shakings. These observations indicate that Soil-Nailed walls have an inherent satisfactory seismic response. This has been attributed to the intrinsic flexibility of the Soil-Nailed...