Sharif Digital Repository

Noise reduction is a major concern in digital image processing systems, which have been investigated by several techniques. One kind of important noises in images is known as Salt & Pepper, which may have different causes. In this paper a new approach for eliminating this type of noise is presented. The approach is different from all previous works in this field, and is based on classification. More precisely, it tries to classify pixels of an image to one of two categories: noisy or not noisy. Afterward, it employs a median filter for pixels which have been classified as noisy, and remains others unchanged; hence, edges and other fine details are kept. Experimental results show this... 

Effect of alkaline metal salts on the solvent extraction of platinum from leached spent dehydrogenation catalysts (Pt/Al2O3) in aqua-regia by the Trioctylphosphine oxide (TOPO) has been investigated. Best salting out effect was achieved using KCl as the additive salt in which process upto 90% of Platinum extraction achieved. Response Surface methodology utilized in order to design the experiments, model the extraction process for platinum and aluminum as well as; optimize the whole process. It was shown that solvent extraction of platinum by TOPO was kinetically fast and the needed equilibrium time for it was less than 30 seconds. In the present study, proposed models for platinum and... 

In this research, data on liquid-liquid extraction of platinum from commercial spent catalysts by trioctylphosphine oxide (TOPO) in toluene were experimentally obtained. Alkaline metal salts were used to optimize the separation process. Best Salting-out effect was obtained by KCl which extracted up to 90% of platinum utilizing TOPO. Furthermore, extraction percentages of Pt and Al depending upon different factors were investigated. It was observed that the extraction process was kinetically fast and achieving the equilibrium time took less than 30 seconds. Optimized points obtained utilizing response surface methodology (RSM) by the "Design Expert" software in order to minimize the... 

Progressive use of Web based information retrieval systems such as general purpose search engines and dynamic nature of the Web make it necessary to continually maintain Web based information retrieval systems. Crawlers facilitate this process by following hyperlinks in Web pages to automatically download new and updated Web pages. Freshness (recency) is one of the important maintaining factors of Web search engine crawlers that takes weeks to months. Many large Web crawlers start from seed pages, fetch every links from them, and continually repeat this process without any policies that help them to better crawling and improving performance of those. We believe that data mining techniques... 

A new reduced-order modeling approach is presented. This approach is based on fluid eigenmodes and without using the static correction. The vortex lattice method is used to analyze unsteady flows over two-dimensional airfoils and three-dimensional wings. Eigenanalysis and reduced-order modeling are performed using a conventional method with and without the static correction technique. In addition to the conventional method, eigenanalysis and reduced-order modeling are also performed using the new proposed method, that is, without static correction requirement. Numerical examples are presented to demonstrate the accuracy and computational efficiency of the proposed method. Based on the... 

This paper presents a new reduced-order modeling approach based on boundary element method. In this approach the eigenvalue problem of the unsteady flows is defined based on the unknown wake singularities. By constructing this reduced-order model, the body quasi-static eigenmodes are removed from the eigensystem and it is possible to obtain satisfactory results without static correction technique when enough eigenmodes are used. In addition to the conventional method, Eigenanalysis and reduced-order modeling of unsteady flows over a NACA 0012 airfoil and a wing with NACA 0012 section are performed using this new ROM method. Numerical examples are presented that demonstrate the accuracy and... 

Statistical and biochemical studies have revealed nonrandom patterns in codon assignments. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslational errors and point mutations, since it is known that, when an amino acid is converted to another due to error, the biochemical properties of the resulted amino acid are usually very similar to those of the original one. In this study, we have taken into consideration both relative frequencies of amino acids and relative gene copy frequencies of tRNAs in genomic sequences in order to introduce a fitness function which models the mistranslational probabilities more accurately in modern organisms. The... 

This article presents the result of an analysis to determine the distance that the fuselage of a Flapping Flyer moves up and down when the wing flap and comparison it with experiments that was done on fuselage phenomena during flight of an ornithopters and Winged animals in Wind tunnel. It is suggested that this motion may reduce the efficiency of design, whereas the tendency for fuselage motion may be largely cancelled in the bi plane configuration. The article also answers a question that has puzzled for scientist. Why bodies of winged animals don't move up and down noticeably when they flaps their wing during flight? Finally we offer one solution for reduce this unwanted motion near 50 %... 

Inferring the structure of molecular networks from time series protein or gene expression data provides valuable information about the complex biological processes of the cell. Causal network structure inference has been approached using different methods in the past. Most causal network inference techniques, such as Dynamic Bayesian Networks and ordinary differential equations, are limited by their computational complexity and thus make large scale inference infeasible. This is specifically true if a Bayesian framework is applied in order to deal with the unavoidable uncertainty about the correct model. We devise a novel Bayesian network reverse engineering approach using ordinary... 

Due to the nonlinear dynamics of hydraulic systems, applying high performance closed-loop controllers is complicated. In this paper, a single-rod hydraulic actuator is considered in which load displacement (for positioning purposes) is controlled via manipulation of the input voltage to the servo-valve. Dynamics of the servo-valve is described by first and second order transfer functions (named as Models 1 and 2). Through linearization of the system around its operating points, dynamics of the hydraulic actuator is represented in the state space. A full-order observer is designed for on-line states estimation. Then, feedback control system is designed for both regulation and tracking... 

Asphalt concrete is a complex mixture, the behavior of which is dependent on its components while showing different nonlinear behaviors under various conditions. Application of rest time between compressive loading cycles causes hardening-relaxation (H-R) behavior in the sample and increases the deformation potential of the sample. This process might induce changes in the microstructure and the pattern of the placement and rotation of the aggregates. These changes cause a relaxation in the hardening of the material, pose a higher potential of reception of viscoplastic strain in the following cycles, and increase the rate of accumulation of the permanent deformation in contrast with creep... 

The use of Computer Science in order to categorize and store information, improve diagnostic and therapeutic procedures, patient education and the training of a skilled labor force, has taken important steps and there are constantly new developments in this area  

Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated water. P.... 

Statistical and biochemical studies have revealed non-random patterns in codon assignments. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslation errors and point mutations, since it is known that when an amino acid is converted to another due to error, the biochemical properties of the resulted amino acid are usually very similar to those of the original one. In this study, using altered forms of the fitness functions used in the prior studies, we have optimized the parameters involved in the calculation of the error minimizing property of the genetic code so that the genetic code outscores the random codes as much as possible. This work also... 

Block method approach to solve EIT problem results exact solution if the measurements are done with enough accuracy. However, solving the EIT problem with this method brings complexity to the required calculations. In this article, the 3D model of EIT with block method is extracted. The required equations to solve the forward problem are then generated. To solve the problem, a series of extra equations are added to the set of equations. These equations helped to devise a non-iterative method to find the parameters in forward problem. ©2004 IEEE  

This article presents a new QoS architecture for IEEE 802.16 Broadband Wireless MAN. The newly proposed strategy of providing QoS in packet-based networks via IEEE 802.16 has been analyzed. A mapping rule for providing layer 2.5 (MPLS protocol) and MAC layer has been proposed. A fast signaling mechanism has been designed to provide QoS in Point to Multipoint (PMP) mode. Although IEEE 802.16 standards define different mechanisms to provide Quality of Service requirements, it is the responsibility of the developers to obtain efficient designs. In this paper, we introduce a novel architecture for providing QoS requirements such as bandwidth utilization and delay. Simulation result shows the... 

Polychlorinated biphenyls (PCBs) cause many significant ecological problems because of their low degradability, high harmfulness, and solid bioaccumulation.Two bacterial strains were isolated from soil that had been polluted with electrical transformer liquid for more than 40 years. The isolates were distinguished as Lysinibacillus macrolides DSM54Tand Bacillus firmus NBRC15306Tthrough 16S rRNA sequencing analysis.This is the primary report of an agent of the genus Bacillus firmus equipped for the removal of PCBs. The strains could develop broadly on 2-Chlorobiphenyl and 2,4-dichlorobiphenyl. GC/MS analysis of individual congeners revealed up to 80% degradation of the xenobiotics in 96h,... 

A general three-dimensional aeroelastic solver is developed based on coupled finite element and boundary element methods and applied to investigate the flutter boundaries in supersonic flows. The boundary element method is applied to three-dimensional unsteady supersonic potential flow as the aerodynamic model and coupled with the finite element method for structural modelling, in order to construct the system of aeroelastic equations. The aeroelastic equations are solved for the flutter prediction using the frequency domain approach. Flutter boundaries for two types of wing planforms at supersonic speeds are determined and compared with the existing experimental results and previous... 

In this research, the recovery of uranium from the phosphate ore of the Sheikh Habil-Iran mine using flotation/calcination-leaching processes has been investigated. A 75–150 μm phosphate ore particle size, sodium oleate as a collector with a concentration of 2,000 g/ton of rock, pH = 10, and 5 min flotation time were obtained as the optimum parameters of flotation using the reverse method, leading to phosphate ore with a grade of 180 ppm UO2, 36.1% P₂O₅, 7.22% SiO2, and CaO/P₂O₅ = 1.23. The optimum calcination parameters were selected as 100 μm phosphate ore particles size at D80, 900°C temperature, and 2 h heating time, which resulted in phosphate ore with a grade of 173 ppm UO2 and 31.9%... 

Simulation is the gold standard for training in aviation and trauma medicine. Now it is available for diseases diagnosis and treatment. With simulation, clinicians can practice their art in a realistic, consequence free environment, combining both theory and practice in a comprehensive program. Method and materials - In the virtual clinical environment of "VPsoft mentor" software, the practitioner reviews a patient's history, orders laboratory tests and procedures, interprets findings, renders diagnoses, and prescribes medication. Every diagnostic or treatment decision the clinician makes for the patient is analyzed by E-mentor, providing instant feedback.Results - This software have been...