Sharif Digital Repository

In this paper, the stick-slip motion of a new type of micro-robot with two perpendicular vibratory actuators is studied which is based on the friction drive principle. The actuators are based on piezo-electric phenomenon which are driven by a harmonic voltage, and both of them are mounted on the micro-robot body. These actuators cause the micro-robot moves forward or backward due to the specified phase difference between the voltages applied to vertical and horizontal actuators. Since the dynamics of the actuators affects on the micro-robot motion, so to derive the equations of motion the coupled dynamics between the body of robot and vibratory masses of actuators are considered, and the... 

Moisture control of food products is of great importance in drying processes. Improving the dryer control system results in consistent production and reduction in energy consumption. In this paper, a state observer is used to estimate the moisture content and other state variables online. Estimated states are used in a control system including the regulator for disturbance rejection and robust controller for tracking objective. Since the bed dryer mechanism is a multivariable complex system associated with various uncertainties, a realistic uncertain model is considered. Moisture content and temperature of tea leaves (or other food products) are controlled at desired set points by... 

Vertical drilling methods have been often used for oil and gas extraction so far. In some places, for further extraction and access to the locations that cannot be obtained by the vertical drilling (due to its restrictions); horizontal drilling has become more popular. In horizontal drilling, a variety of longitudinal, torsional and lateral vibrations occur. These vibrations, if left uncontrolled, can damage the drilling rig and equipment, as well as reduce the efficiency of the drilling process and increase the processing time. The purpose of this research is to obtain the coupled axial and torsional vibration equations by analysing the vibrational modes in the horizontal section of the... 

The mechatronic design of a novel mechanism for ball and plate system is discussed. A webcam provides the system with feedback of the ball's position. A heuristic technique for image processing is introduced. The kinematics and dynamics of the system are also described. Supervisory fuzzy control and sliding control techniques are proposed to perform position control for the system. Experimental results corroborate the validity of the controllers. © 2008 IEEE  

In this research, to overcome the challenging problem of the vibration suppression in the wind turbine blade, an active robust adaptive finite-time model reference controller is introduced. First, edgewise vibrations of the wind turbine blade, with consideration of the platform heave displacements, is modeled by Euler-Bernoulli beam theory. Then, the appropriate adaptation laws and control laws are introduced to compensate the uncertainties and guarantee the convergence to the desired reference model. The robustness and convergence of the designed adaptation and control laws are mathematically proved via finite-time Lyapunov theory. Performance of the designed robust adaptive finite-time... 

In this article, the effects of the changes in the mass of the floating wind turbine (as a multi-body system) on its nonlinear vertical vibrations are investigated. The fluctuations of the hydrodynamic added mass of the floating platform and the mass of the vibration absorbers, which added to the structure to mitigate the lateral vibrations, change the mass and consequently the dynamics of the vertical vibrations. In this regard, first, the governing equations of the vertical vibrations of the floating wind turbine are derived. The FAST code is used to validate the proposed model of the dynamics of the vertical vibrations through numerical simulations. Then, derived equations are solved... 

Blend drug-loading method in electrospun scaffolds has gained much attention as a cost-effective and simple delivery system in regenerative medicine. However, it has some drawbacks, such as the burst release of encapsulated drugs and denaturing active agents in harsh organic solvents. In this study, a new silk fibroin-gelatin (SF–G) fibrous sheet has been introduced as an engineered scaffold and a straightforward drug delivery system for skin tissue engineering applications. The hybrid sheets have been prepared via co-electrospinning and in-situ crosslinking methods without corrosive solvents and toxic crosslinking agents. To evaluate the proposed scaffold as a controlled release system, the... 

The design of a novel Continuous Fractional-Order Nonsingular Terminal Sliding Mode controller is the focus of this study. Time Delay Estimation technique is incorporated into the controller. The proposed method is responsible for controlling the human knee joint neuromusculoskeletal model via Functional Electrical Stimulation. A second-order nonlinear model with time-varying coefficients is used for characterizing the FES-stimulated neuromusculoskeletal model. The presence of time-varying coefficients often complicates precise control of knee joint through FES and impairs the performance of conventional methods. To this end, the TDECFONTSM has been proposed consisting of three components, a... 

A batch extraction of an essential amino acid, phenylalanine, from an aqueous solution of different concentrations by an Emulsion Liquid Membrane (ELM) was developed using D2EHPA as a cationic carrier, Span 80 as the surfactant, paraffin, and kerosene as the diluents, and HCl as the internal electrolyte. All effective parameters such as the initial pH of the aqueous external phase, the electrolyte concentration in the aqueous internal phase, carrier, and surfactant concentration in the emulsion, the volume ratio of the organic to aqueous internal phase (Roi), the volume ratio of the W/O emulsion to the aqueous external phase (Rew) and time were examined and optimized using the Taguchi... 

The oxidation of ferrous iron (Fe2+) in solution using Acidithiobacillus ferrooxidans has industrial applications exclusively in the regeneration of ferric iron (Fe3+) as an oxidizing agent for the removal of hydrogen sulfide from waste gases, desulfurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this investigation was to increase the bio-oxidation rate of ferrous sulfate by using immobilized cells. Rate of Fe2+ oxidation was determined in a packed-bed bioreactor configuration with monolithic particles being used as support material. Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and... 

An extension to the classical mass-spring model for more realistic simulation of soft tissues for surgery simulation was proposed. The conventional equations of mass-spring model were generalized for non-linear springs, and model parameters were tuned using experimental data. Results show that the proposed model is fast and interactive, and also demonstrate the typical nonlinear and visco-elastic behaviors of soft tissues well. © 2008 The authors. All rights reserved  

Convenient medical diagnostics and treatments can replace conventional healthcare procedures because of their fast and profitable applications with reduced infection risk. Meanwhile, early diagnosis of cancer is a leading research subject due to the high fatality rate of the disease and being a vital precursor in the treatment effectiveness. Electrochemical-based micro-biosensors are the best candidates for measuring particular biomarker concentrations in body fluids. To address this need, we used a simple fabrication approach to develop an effective immunosensor for the early detection of cancer, in particular prostate cancer. The carbon fibers, obtained from the electrospinning technique,... 

In this paper the effect of the COD/SO4 ratio on the performance of an anaerobic baffled reactor (ABR) was investigated. Synthetic wastewater (3000 mg-COD/l) was used as the sole organic substrate. ABR was maintained at a hydraulic retention time (HRT) of 1 day and at a temperature of 35 °C. The results of this study showed that when COD/SO4 ratios were changed from 16.7 to 6 with increasing sulfate concentration from 180 to 500 mg/l, COD conversion was not decreased, but a slight increase in COD removal was observed. These phenomena indicated that both methanogenic bacteria and sulfate reducing bacteria (SRB) could exist in the system as synthrophism. Maximum COD and sulfate removal were 86... 

In this paper, a biopolymer flocculant-producing bacteria, strain As-101, isolated from activated sludge and identified as Bacillus species is considered. Study of the basic characteristics and comparison of the strain were carried out according to Bergey's manual of bacteriology and the bacterium was identified as Bacillus Coagulants. The activated sludge was treated by a commercial protease (trypsin) with an optimum concentration of 0.4 mg/ml for producing the maximum extent of deflocculation, which was near 16%. The production of bioflocculant by Bacillus As-101 was not parallel to the cell growth and a large amount of the bioflocculant was released into the culture at the end of the... 

The main scope of this study is to analyse muscle-driven forward dynamics simulation of stair locomotion to understand the functional differences of individual muscles during the movement. A static optimization was employed to minimize a performance criterion based on the muscle energy consumption to resolve muscle redundancy during forward dynamics simulation. The proposed method was employed to simulate a musculoskeletal system with ten degrees of freedom in the sagittal plane and containing 18 Hill-type musculotendon actuators per leg. Simulation results illustrated that simulated joint kinematics closely tracked experimental quantities with root-mean-squared errors less than 1 degree. In...