Sharif Digital Repository

A comprehensive model for pervaporation in thin membrane channels was developed to study the effect of changing temperature and concentration on mass flux. This model consists of momentum, energy and species mass balances along and across the membrane in the flow channel. A computational fluid dynamics (CFD) code was written in C++ programming language to solve the coupled non-linear transport equations in the channel by finite volume method. The Semi-Implicit Pressure Link Equation (SIMPLE) CFD algorithm is used to modify the dependent variables in each of the iterations. The effect of variation of temperature and concentration on transport and thermodynamic properties were considered by... 

In this study, active poly lactic acid (PLA) films containing 0, 10, 20 and 40% w/w propolis extract (PE), as active agent, were developed. A high amount of phenolic content (PC) was measured in PE. The antioxidant effect of active PLA films was determined by measuring the PC of sausage slices after 0, 2 and 4 days storage at refrigerator. Results showed that phenolic compounds of PE were released from PLA films in quantities proportional to PE concentration. Disc diffusion test indicated that PE showed an inhibitory effect against Staphylococcus aureus and Pseudomonas aeruginosa bacterial species but was more effective against gram-positive species. PE containing PLA films had antimicrobial... 

This paper presents a new method for spectrophotometirc detection of sulfide applying fungal peroxidase immobilized on sodium alginate. The sensing scheme was based on decrease of the absorbance of the orange compound, purpurogallin produced from pyrogallol and H2O2 as substrates, due to the inhibition of peroxidase by sulfide. Absorbance of purpurogallin was detected at 420nm by using a spectrophotometer. The proposed method could successfully detect the sulfide in the concentration range of 0.6-7.0μM with a detection limit of 0.4μM. The kinetic parameters of Michaelis-Menten with and without sulfide were also calculated. Possible inhibition mechanism of peroxidase by sulfide was deduced... 

[No abstract available]  

[No abstract available]  

This paper presents a novel method fortuning the parameters of an sliding mode (SM) controller to obtain near-optimal performance. In order to do so the Linear Quadratic Regulator (LQR) was implemented on a linearized system. The input history of the LQR was used as a reference to obtain an optimal space for sliding mode controller parameters. Afterwards, the optimal space boundaries were dedicated to Genetic Algorithm (GA) to search for the optimal parameter for the nonlinear model. Also, the center of the obtained optimal space was used as an initial guess to the Particle Swarm Optimization (PSO) Algorithm. The proposed algorithm was implemented to regulate SM controller for the attitude... 

Fatty acids are among the most important components of many biological systems and have been highlighted in many research fields in recent decades. In the food industry, it is important to check the amount and types of fatty acids in edible oils, beverages and other foods products, and checking the fatty acids parameters are among the quality control parameters for those products. In medical applications, investigation of fatty acids in biological samples and comparing imbalances in them can help to diagnose some diseases. On the other hand, the development of cell factories for the production of biofuels and other valuable chemicals requires the accurate analysis of fatty acids, which serve... 

In this paper, a parallel algorithm for data clustering is presented on a multi-computer with star topology. This algorithm is fast and requires a small amount of memory per processing element, which makes it even suitable for SIMD implementation. The proposed parallel algorithm completes in O(K+S 2-T 2) steps for a clustering problem of N data patterns with M features per pattern and K clusters, where N.M = S!, K.M = T!, and M=R!, on a s-star interconnection network. © Springer-Verlag Berlin Heidelberg 2005  

This paper presents two effective methods to reduce power consumption of branch target buffer (BTB): 1) the first method is based on storing distance to next branch address in tag array instead of storing whole branch address, 2) the second method is to use a new field in data array of BTB namely Next Branch Distance (NBD) which holds distance of next branch address from current branch address. When a new hit is performed in BTB, based on NBD field, there would be no access through NBD number of instructions, so BTB can be shutdown not to consume power. The new architecture does not impose extra delay and reduction in prediction accuracy. Both methods were implemented and simulated using... 

In this study the bioleaching of a low-grade uranium ore containing 480 ppm uranium has been reported. The studies involved extraction of uranium using Acidithiobacillus ferrooxidans derived from the uranium mine samples. The maximum specific growth rate (μ max) and doubling time (t d) were obtained 0.08 h-1 and 8.66 h, respectively. Parameters such as Fe2+ concentration, particle size, temperature and pH were optimized. The effect of pulp density (PD) was also studied. Maximum uranium bio-dissolution of 100 ± 5 % was achieved under the conditions of pH 2.0, 5 % PD and 35 °C in 48 h with the particles of d 80 = 100 μm. The optimum concentration of supplementary Fe2+ was dependent to the PD.... 

This paper presents two effective methods to reduce power consumption of branch target buffer (BTB): 1) the first method is based on storing distance to next branch address in tag array instead of storing whole branch address, 2) the second method is to use a new field in data array of BTB namely Next Branch Distance (NBD) which holds distance of next branch address from current branch address. When a new hit is performed in BTB, based on NBD field, there would be no access through NBD number of instructions, so BTB can be shutdown not to consume power. The new architecture does not impose extra delay and reduction in prediction accuracy. Both methods were implemented and simulated using... 

In this paper, a parallel algorithm is presented for data clustering on a multicomputer with star topology. This algorithm is fast and requires a small amount of memory per processing element, which makes it even suitable for SIMD implementation. The proposed parallel algorithm completes in O(K+S2-T2) steps for a clustering problem of N data patterns with M features per pattern and K clusters where S and T are the minimum numbers such that NM≤S! and KM≤T!, on the S-dimensional star graph  

The authors regret Acknowledgement: The authors would like to express his gratitude to Iran National Science Foundation (INSF) for supporting this research under grant number 92037628. The authors would like to apologise for any inconvenience caused. © 2019 Elsevier B.V  

In this paper Time-Based Random Waypoint (TBRWP) model is analyzed in detail. Random waypoint model has been studied in mobility literature extensively. Traditional RWP model is based on the independency of the velocity and trajectory; TBRWP, instead, focuses on the independency of motion time and trajectory. Basic model is introduced and general method to evaluate the asymptotical probability density function (PDF) is presented. The model for the one-dimensional and two-dimensional cases with uniform destination distribution in unit square area is solved and exact closed form formulas is obtained. Moreover, normal distribution of nodes in one- and two- dimensional models is investigated and... 

Nowadays networks-on-chip are emerging as a hot topic in IC designs with high integration. In addition to popular mesh and torus topologies, other structures can also be considered especially in 3D VLSI design. The shuffle-exchange topology is one of the popular interconnection architectures for multiprocessors due to its scalability and self-routing capability. By vertically stacking two or more silicon wafers, connected with a high-density and high-speed interconnect, it is now possible to combine multiple active device layers within a single IC. In this paper we propose an efficient three dimensional layout for a novel 2D mesh structure based on the shuffle-exchange topology. Simulation... 

In the present work, an amperometric inhibition biosensor for the determination of sulfide has been fabricated by immobilizing Coprinus cinereus peroxidase (CIP) on the surface of screen printed electrode (SPE). Chitosan/acrylamide was applied for immobilization of peroxidase on the working electrode. The amperometric measurement was performed at an applied potential of -150. mV versus Ag/AgCl with a scan rate of 100. mV in the presence of hydroquinone as electron mediator and 0.1. M phosphate buffer solution of pH 6.5. The variables influencing the performance of sensor including the amount of substrate, mediator concentration and electrolyte pH were optimized. The determination of sulfide... 

CuO flower-like microcrystals, prepared by a facile template-free thermal method, showed incredible photocatalytic activity towards degradation of Acid Blue 92 (AB92), an organic wastewater, Escherichia coli and Staphylococcus aureus pathogenic bacteria under visible light. The products were well characterised by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), Fourier transform infrared (FTIR), photoluminescence spectroscopy (PL) and diffuse reflectance spectra (DRS) analysis methods. The XRD pattern of the products well confirmed the formation of copper oxide crystalline phase without any other impurities. The results of the photocatalytic... 

CuO flower-like microcrystals, prepared by a facile template-free thermal method, showed incredible photocatalytic activity towards degradation of Acid Blue 92 (AB92), an organic wastewater, Escherichia coli and Staphylococcus aureus pathogenic bacteria under visible light. The products were well characterised by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), Fourier transform infrared (FTIR), photoluminescence spectroscopy (PL) and diffuse reflectance spectra (DRS) analysis methods. The XRD pattern of the products well confirmed the formation of copper oxide crystalline phase without any other impurities. The results of the photocatalytic... 

In this paper, a mathematical model for the mesophilic bioleaching of uraninite is developed. The case of constant temperature, pH, and initial ore concentration is considered. The model is validated by comparing the calculated and measured values of uranium extraction, ferric and ferrous iron in solution, and cell concentration. Good fits of the model were obtained, while the values of the parameters were within the range expected. New rate expressions were used for the iron precipitation and uranium leaching rates. The rates of chemical leaching and ferric precipitation are related to the ratio of ferric to ferrous in solution. The fitted parameters can be considered applicable only to... 

Future GPUs should have larger L2 caches based on the current trends in VLSI technology and GPU architectures toward increase of processing core count. Larger L2 caches inevitably have proportionally larger power consumption. In this article, having investigated the behavior of GPGPU applications, we present an efficient L2 cache architecture for GPUs based on STT-RAM technology. Due to its high-density and low-power characteristics, STT-RAM technology can be utilized in GPUs where numerous cores leave a limited area for on-chip memory banks. They have, however, two important issues, high energy and latency of write operations, that have to be addressed. Low retention time STT-RAMs can...