Sharif Digital Repository

In this study, the authors consider the designing of a new set of uniquely decodable codes for uncoded synchronous overloaded code division multiple access for the number of codes exceeding the assigned code length. For the construction, the proposed recursive method at iteration-k generates a matrix that can be classified into k orthogonal subsets of different dimensions. Out of them, all besides the largest (binary Hadamard) one are ternary in nature. There resides an inbuilt twin tree structured cross-correlation hierarchy that facilitates an advantageous balance between the auto and intergroup cross-correlation for the signatures in a subset. This opportunity is further leveraged by the... 

This paper proposes a class of estimators for population correlation coefficient when information about the population mean and population variance of one of the variables is not available but information about these parameters of another variable (auxiliary) is available, in two phase sampling and analyzes its properties. Optimum estimator in the class is identified with its variance formula. The estimators of the class involve unknown constants whose optimum values depend on unknown population parameters. In earlier research it has been shown that when these population parameters are replaced by their consistent estimates the resulting class of estimators has the same asymptotic variance... 

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... 

We consider the designing of a new set of uniquely decodable codes for uncoded synchronous overloaded CDMA system that exists for arbitrary values of spreading gain (code length). A fast and recursive method of construction is proposed where the orthogonal Hadamard matrix of least dimension (two), as the basis of construction regularizes a ternary pattern which is further leveraged to attain a rich simplicity in decoder design. The simplicity gained in designing of the proposed Comparison Aided Decoder (CAD) is prominent enough to neglect the marginal sacrifice in Bit Error Rate (BER) as compared to the optimum Maximum Likelihood Decoder (MLD) for noisy transmission. Despite its low complex... 

Overloaded code division multiple access being the only means of the capacity extension for conventional code division multiple access accommodates more number of signatures than the spreading gain. Recently, ternary Signature Matrices with Orthogonal Subsets (SMOS) has been proposed, where the capacity maximization is 200%. The proposed multi-user detector using matched filter exploits the twin tree hierarchy of correlation among the subsets to guarantee the errorless recovery. In this paper, we feature the non-ternary version of SMOS (i.e., 2k-ary SMOS) of same capacity, where the binary alphabets in all the k constituent (orthogonal) subsets are unique. Unlike ternary, the tree hierarchy... 

Abstract: The convection–diffusion process of carbon dioxide (CO2) dissolution in a saline reservoir is investigated to shed light on the effects of the permeability heterogeneity. Using sequential Gaussian simulation method, random permeability fields in two and three-dimension (2D and 3D) structures are generated. Quantitative (average amount of the dissolved CO2 and dissolution flux) and qualitative (pattern of the dissolved CO2 and velocity streamlines) measurements are used to investigate the results. A 3D structure shows a slightly higher dissolution flux than a 2D structure in the homogeneous condition. Results in the random permeability fields in 2D indicates an increase in the... 

A cost-effective design of reusable enzyme-functionalized particles with better catalytic activity is of great scientific interest due to their applications in a wide range of catalytic reactions in several industrial processes. In this work, a systematic approach for preparing amine-functionalized magnetic nanocomposite particles through the surface modification of core/shell type Fe3O4 cluster@SiO2 particles by the small molecules of 3-(2-aminoethyl)aminopropyltrimethoxysilane (AAS) or the large molecules of polyethyleneimine (PEI) with two different molecular weights, as the support materials for enzyme immobilization, has been demonstrated. The functional... 

A facile approach for the preparation of core-shell structured poly(acrylic acid) (PAA)-coated Fe3O4 cluster@SiO2 nanocomposite particles as the support materials for the lipase immobilization is reported. Low- or high-molecular-weight (1800 and 100 000, respectively) PAA molecules were covalently attached onto the surface of amine-functionalized magnetic silica nanoacomposite particles. The successful preparation of particles were verified by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential measurement, and Fourier-transform infrared (FTIR) techniques. Once lipase is covalently... 

This study reports the importance of physicochemical characteristics of the core-shell structured polymer-coated Fe3O4 cluster@SiO2 nanocomposite particles for designing the biocatalysts used for transesterification of soybean oil. To demonstrate this issue, two different types of polymer molecules such as polyethylenimine (PEI) and polyacrylic acid (PAA) each with two different molecular weights are employed. The highest fatty acid methyl esters (FAMEs) synthesis yield values are achieved by the lipases immobilized onto the low- and high-molecular-weight PEI-coated particles as compared to those of the low- and high-molecular-weight PAA-coated particles (i.e., ∼64.8% and ∼73.1% versus... 

Ageing is one of the main contributing factors towards increasing arterial stiffness, leading to changes in peripheral pulses propagation. Therefore the characteristics of the photoplethysmogram (PPG) pulse, especially the rising edge and peak position, are greatly affected. In this study, the PPG pulse rising edge and corresponding peak position have been investigated non-invasively in human subjects as a function of age. Fifteen healthy subjects were selected and grouped in five age intervals, from 20 to 59 years, based on their comparable systolic-diastolic blood pressure and PPG amplitude. As expected, the peripheral pulse shows a steep rise and early peak in younger subjects. With age,... 

This paper presents the results of an experimental study on the flexural behavior of ten 10 × 15 × 120 (cm) steel reinforced high strength concrete beams under deflection control loading conditions. Test variable includes volumetric percentage of steel fibers (0%, 1.5%, 3%, 4%, 5%). The plain concrete strength was 30MPa. The monotonic concentrated load was applied at the center of the beam, the relative deflection was measured, and demec points were used to determine curvature of the beam. Load-deflection and moment-curvature diagrams have been obtained and plotted for each beam individually. Test results indicate that higher fiber content considerably improves flexural behavior and provides... 

Single-cell resolution technologies warrant computational methods that capture cell heterogeneity while allowing efficient comparisons of populations. Here, we summarize cell populations by adding features’ dispersion and covariances to population averages, in the context of image-based profiling. We find that data fusion is critical for these metrics to improve results over the prior alternatives, providing at least ~20% better performance in predicting a compound’s mechanism of action (MoA) and a gene’s pathway. © 2019, The Author(s)  

Data science as a flourishing interdisciplinary domain of computer and mathematical sciences is playing an important role in guiding the porous material research streams. In the present narrative review, we have examined recent trends and issues in data-driven methods used in the image-based porous material research studies relevant to water resources researchers and scientists. Initially, the recent trends in porous material data-related issues have been investigated through search engine queries in terms of data source, data storage hub, programing languages, and software packages. Subsequent to a diligent analysis of the existing trends, a review of the common concepts of porous material... 

The aggregation of an amyloid protein, α-synuclein (α-Syn), has been suggested as a potential cause of Parkinson's and several other neurodegenerative diseases. To explore the possibility of using nanoparticle-based therapeutic agents for the treatment of such diseases, we investigated the influence of surface chemistry and concentration of mesoporous silica nanoparticles (MSNPs) on the fibrillation of recombinant human α-Syn protein in the present work. Bare MSNPs as well as MSNPs of different surface functionalities, including 3-(2-aminoethyl amino) propyltrimethoxysilane (AAS), succinic anhydride (carboxyl), and polyethyleneimine (PEI) were prepared and characterized by electron... 

Cu2O nanocubes, octahedra, spheres and truncated rhombic dodecahedral were prepared and their structural, morphological, and electronic properties were investigated by X-ray diffraction analysis, X-ray absorption near edge structure, scanning electron microscope and transmission electron microscope and X-ray absorption near edge structure. Cu2O nanocrystals were successfully employed to catalyze the 1,3-dipolar cycloaddition reaction for the synthesis of 1,4-disubstituted triazoles. Cu2O nanocubes and octahedral showed the superior catalytic performance in the cycloaddition reaction. These results reveal that crystal-plane engineering of oxide catalysts is a useful strategy for developing... 

Cu2O nanocubes, octahedra, spheres and truncated rhombic dodecahedral were prepared and their structural, morphological, and electronic properties were investigated by X-ray diffraction analysis, X-ray absorption near edge structure, scanning electron microscope and transmission electron microscope and X-ray absorption near edge structure. Cu2O nanocrystals were successfully employed to catalyze the 1,3-dipolar cycloaddition reaction for the synthesis of 1,4-disubstituted triazoles. Cu2O nanocubes and octahedral showed the superior catalytic performance in the cycloaddition reaction. These results reveal that crystal-plane engineering of oxide catalysts is a useful strategy for developing... 

The present research examines the effects of UV radiation, moisture and elevated temperature on the mechanical properties of GFRP pultruded profiles. Flexural, compressive and tensile properties of different GFRP sections were studied after they were exposed for 1000, 1500, 2000 and 3000 h to UV radiation and water vapour condensation cycles. Mechanical tests, including three-point bending, compression and tension tests, SEM analyses, and statistical studies were conducted to gather comprehensive results. The results showed that the mechanical properties of various GFRP sections generally decreased with the duration of conditioning: however, the rate of the decrease that was only slight up... 

In this research, the mechanical properties of various glass fibre reinforced polymer (GFRP) pultruded profiles exposed to seawater sea sand concrete (SWSSC) and its combination with UV radiation and water vapour condensation were studied. The effect of different conditions, duration of conditioning, and the profile cross-section configuration on the mechanical properties were investigated. Three-point bending, tension, and compression tests were carried out to obtain the mechanical properties, including flexural, tensile and compressive strengths and tensile elastic modulus. Furthermore, in order to scrutiny the mechanisms and extent of damage, scanning electron microscopy (SEM) was carried...