Sharif Digital Repository

This paper offers a systematic framework for the design of suboptimal integer-order controllers based on fractional-order structures. The proposed approach is built upon the integer-order approximations that are traditionally used to implement fractional-order controllers after they are designed. Accordingly, the fractional-order structures are exploited to derive a suitable parameterization for a fixed-structure integer-order controller. The parameters, which describe the structure of the fixed-order integer controller, are the same as those used to describe the original fractional structure. Optimal tuning is then performed in the parameter space of the fractional structure and the... 

Plasma focus is a copious source of electrons, ions, neutrons, and X-rays. SUT-PF is a 7 kJ Mather type plasma focus device. In order to study soft X-rays emitted by this device a bent crystal spectrometer has been designed and constructed based on Johann method. Before recording spectral lines, using a photodiode detector and a pinhole camera, optimum parameters for maximum emission of soft X-rays have been studied and registered. Results show that ionized Argon atomic lines mostly have wavelengths between 3 and 4 Å. Among them 1s2–1s2p transition with a wavelength of 3.943 Å represents the most intense line  

The use of advanced cycles to take advantage of the gas turbine's thermodynamic characteristics has received increasing attention in recent years. These cycles have been developed for large scale power generation. Due to the powerful abilities of bio-inspired computing techniques such as Genetic Algorithm in locating the optimal (or near optimal) solutions to a given optimization problem, they are widely utilized for determining the parameters of different engineering systems in order to meet the specified performance objectives for a given problem. In order to illustrate the performance of one of these techniques, development and application of it for an engineering problem is presented. In... 

Zero discharge desalination process is the most promising technology to prevent salinity and thermal shocks to ecosystem by effluent streams of desalination unit drained into the sea. Pretreatment, solar pond and forced circulation crystallizer are the major steps of one option to provide the purposes of zero discharge desalination process. Reduction of total hardness of wastewater occurs in pretreatment unit and the solar pond is proposed for effluent concentrated brine wastewater of pretreatment unit which seeks production of potable water and concentrated brine. The effluent stream from solar pond is conveyed to one forced circulation evaporator in order to produce salt and distilled... 

Intelligent deep-drawing is an instrumental research field in sheet metal forming. A set of 28 different experimental data have been employed in this paper, investigating the roles of die radius, punch radius, friction coefficients and drawing ratios for axisymmetric workpieces deep drawing. This paper focuses an evolutionary neural network, specifically, error back propagation in collaboration with genetic algorithm. The neural network encompasses a number of different functional nodes defined through the established principles. The input parameters, i.e., punch radii, die radii, friction coefficients and drawing ratios are set to the network; thereafter, the material outputs at two... 

In this study, effect of desiccant wheel, heat exchanger and cooling coil will be evaluated on decreasing the wet bulb temperature of entering air to cooling tower and decreasing the outlet cold water temperature. For this purpose, change effect of desiccant wheel parameters will be investigated on wet bulb temperature of outlet air from heat exchanger. After that, optimum parameters and minimum wet bulb temperature will be selected. Then, outlet cold water temperature will be achieved for various cooling coil surface temperature with definition of by pass factor and also by using optimum desiccant wheel parameters and entrance air wet bulb temperature to tower related to cooling coil... 

Purpose - The purpose of this paper is to analyze a squared lattice cylindrical shell under compressive axial load and to optimize the geometric parameters to achieve the maximum buckling load. Also a comparison between buckling loads of a squared lattice cylinder and a solid hollow cylinder with equal weight, length and outer diameter is performed to reveal the superior performance of the squared lattice cylindrical shells. Design/methodology/ approach - A cylindrical lattice shell includes circumferential and longitudinal rods with geometric parameters such as crosssection areas of the rods, distances and angles between them. In this study, the governing differential equation for buckling... 

Atomic force microscopes (AFM) are widely used for feature detection and scanning surface topography of different materials. Contrast of topography images is significantly influenced by the sensitivity of AFM micro cantilever which means enhancement of sensitivity leads to increase of topography images resolution So, in the last years numerous scientists interested in studying the effects of different parameters such as geometric one on the sensitivity of AFM micro cantilevers. V-shape micro cantilever types of AFMs probe are widely used to scan various types of surfaces. In V-shape micro cantilevers, there are many geometric and design parameters which influence the flexural sensitivity of... 

OBJECTIVE: This study aims to benchmark a Monte Carlo (MC) model of the 18 MV photon beam produced by the Siemens Oncor® linac using the BEAMnrc and DOSXYZnrc codes. METHODS: By matching the percentage depth doses and beam profiles calculated by MC simulations with measurements, the initial electron beam parameters including electron energy, full width at half maximum (spatial FWHM), and mean angular spread were derived for the 10×10 cm2 and 20×20 cm2 field sizes. The MC model of the 18 MV photon beam was then validated against the measurements for different field sizes (5×5, 30×30 and 40×40 cm2) by gamma index analysis. RESULTS: The optimum values for electron energy, spatial FWHM and mean... 

Acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also called COVID-19, is one of the most contagious viruses resulting in a progressive pandemic. Since specific antiviral treatments have not been developed yet and its fatal rate is almost high, early and fast detection is critical for controlling the outbreak. In this study, a piezoelectric microcantilever biosensor has been designed for detecting COVID-19 samples directly without requiring preparation steps. The biosensor acts as a transducer and is coated with the related antibody. When the SARS-CoV-2 antigens adsorbed on the microcantilever top surface through their spike proteins, a surface stress due to the mass change would be... 

In this paper, the truly Meshless Local Petrov-Galerkin (MLPG) method is extended for computation of steady incompressible flows, governed by the Navier-Stokes equations (NSE), in vorticity-stream function formulation. The present method is a truly meshless method based on only a number of randomly located nodes. The formulation is based on two equations including stream function Poisson equation and vorticity advection-dispersion-reaction equation (ADRE). The meshless method is based on a local weighted residual method with the Heaviside step function and quartic spline as the test functions respectively over a local subdomain. Radial basis functions (RBF) interpolation is employed in shape...