Sharif Digital Repository

This research is dedicated to show the possibility of using solar radiation pressure by solar sails for interplanetary flights. In this paper, in addition to the Introduction of solar sailing and physics of solar radiation pressure, the solar sail orbital dynamics for optimal trajectory of an ideal solar sail spacecraft has been studied. It considers the problem of optimal controlling the sail angle so as to execute a minimum-time coplanar orbit transfer from the circular initial orbit to the circular target orbit. The direct collocation optimal control technique is used to transform the state equations to a set of nonlinear algebraic constraint equations. The results of state and control... 

Rainfall characteristics, which include spatial variability, exert a major influence on runoff properties. Many techniques have been proposed for determining the spatial distribution of daily rainfall. One of these techniques is spatial modeling, based on rainfall data measured by rain-gauge networks. In this study, application of different interpolation methods in the GIS environment, for estimating the spatial distribution of daily rainfall in the southwest of Iran with low rain-gauge density, have been compared on a regional scale. The cross validation technique was selected as an accuracy index and statistical parameters, such as MAE (Mean Absolute Error) and MBE (Mean Bias Error), were... 

In the current work, the results of full-scale laboratory testing of 114.3 and 168.3 mm in diameter steel gas distribution pipes buried at different depths and in two different soil types under a reverse fault offset of 0.6 m are presented and discussed in terms of longitudinal strain distribution, pipe deformation, and cross-section distortion. Results show that the pipe deformation and accordingly its failure mode, and soil failure planes change with increasing burial depth. It was also found that severe cross-section distortion occurs at about 2.3 times the strain limit for onset of wrinkling suggested by various guidelines. © 2018, © 2018 Taylor & Francis Group, LLC  

In the current work, the results of full-scale laboratory testing of 114.3 and 168.3 mm in diameter steel gas distribution pipes buried at different depths and in two different soil types under a reverse fault offset of 0.6 m are presented and discussed in terms of longitudinal strain distribution, pipe deformation, and cross-section distortion. Results show that the pipe deformation and accordingly its failure mode, and soil failure planes change with increasing burial depth. It was also found that severe cross-section distortion occurs at about 2.3 times the strain limit for onset of wrinkling suggested by various guidelines. © 2017 Taylor & Francis Group, LLC  

The tear energy and heat build up of NR, SBR and BR vulcanizates and their corresponding blends were measured at several temperatures via modified trouser tear and Goodrich flexometer experiments. In all single component samples, by increasing temperature from -10 to 125°C, the fracture energy decreases, goes through a minimum and increases again. Nevertheless, in SBR and BR, a level off and a level off followed by second drop occur at higher temperatures, respectively. On the other hand, for aforementioned samples the heat build up decreases monotonically by raising the temperature. For two-component blends, the fracture energy and heat build up show different dependencies on temperature in... 

Permanent ground displacement (PGD) caused by surface faulting is considered as one of the most significant hazards affecting buried pipelines. Pipelines crossing reverse-slip faults are subjected to compressive actions (stresses and strains) which can result in buckling of the pipe. In current work, the results obtained from the full-scale laboratory testing and finite element analyses of 4″ (114.3 mm) and 6″ (168.3 mm) steel gas pipes (without internal pressure) buried inside a split box and subjected to a reverse faulting of 0.6 m (pure dip-slip) are presented. These pipes are commonly used in gas distribution lines and networks. The experimental setup, procedure and instrumentation as... 

Since there have been many difficulties in clinical administration of anticancer drugs due to their poor solubility & targeting, development of new biodegradable Nano-carriers can provide good solutions to overcome the most of recent problems to obtain a better controlled release and targeted delivery of drugs with better efficiency and less side-effects. Acidic pH is regarded as a phenotypic characteristic of cancer tumors. Under this acidic condition, it is known that the surface charge of Chitosan-modified nano-particles become more positive. On the other hand, cancer cells are negatively charged. It is worth mentioning that by loading of anticancer drugs into this novel system, a strong... 

A numerical study is carried out on buried steel and high density polyethylene (HDPE) pipelines subjected to oblique-reverse faulting. The components of the oblique-reverse offset along the horizontal and normal directions in the fault plane are determined using well-known empirical equations. The numerical model is validated using the experimental results and detailed finite element model of a 114.3 mm (4==) steel gas pipe subjected to a reverse fault offset up to 0.6 m along the faulting direction. Different parameters such as the pipe material, the burial depth to the pipe diameter ratio (H/D), the pipe diameter to wall thickness ratio (D/t), and the fault–pipe crossing angle are... 

Support vector machines (SVMs) were used as a novel learning machine in the authentication of the origin of salmon. SVMs have the advantage of relying on a well-developed theory and have already proved to be successful in a number of practical applications. This paper provides a new and effective method for the discrimination between wild and farm salmon and eliminates the possibility of fraud through misrepresentation of the country of origin of salmon. The method requires a very simple sample preparation of the fish oils extracted from the white muscle of salmon samples. 1H NMR spectroscopic analysis provides data that is very informative for analysing the fatty acid constituents of the... 

The learning vector quantization (LVQ) neural network is a useful tool for pattern recognition. Based on the network weights obtained from the training set, prediction can be made for the unknown objects. In this paper, discrimination of wines based on 2D NMR spectra is performed using LVQ neural networks with orthogonal signal correction (OSC). OSC has been proposed as a data preprocessing method that removes from X information not correlated to Y. Moreover, the partial least squares discriminant analysis (PLS-DA) method has also been used to treat the same data set. It has been found that the OSC-LVQ neural networks method gives slightly better prediction results than OSC-PLS-DA © 2005... 

The dependency of amino acid chemical shifts on φ and ψ torsion angle is, independently, studied using a five-residue fragment of ubiquitin and ONIOM(DFT:HF) approach. The variation of absolute deviation of 13Cα chemical shifts relative to φ dihedral angle is specifically dependent on secondary structure of protein not on amino acid type and fragment sequence. This dependency is observed neither on any of 13Cβ, and 1Hα chemical shifts nor on the variation of absolute deviation of 13Cα chemical shifts relative to ψ dihedral angle. The 13Cα absolute deviation chemical shifts (ADCC) plots are found as a suitable and simple tool to predict secondary structure of protein with no requirement of... 

We use the Fokker-Planck equation and model the dispersive dynamics of solid particles in annular protoplanetary disks whose gas component is more massive than the particle phase. We model particle-gas interactions as hard sphere collisions, determine the functional form of diffusion coefficients, and show the existence of two global unstable modes in the particle phase. These modes have spiral patterns with the azimuthal wavenumber m = 1 and rotate slowly. We show that in ring-shaped disks, the phase-space density of solid particles increases linearly in time toward an accumulation point near the location of pressure maximum, while instabilities grow exponentially. Therefore, planetesimals... 

I formulate a general finite element method (FEM) for self-gravitating stellar systems. I split the configuration space to finite elements, and express the potential and density functions over each element in terms of their nodal values and suitable interpolating functions. General expressions are then introduced for the Hamiltonian and phase-space distribution functions of the stars that visit a given element. Using the weighted residual form of Poisson's equation, I derive the Galerkin projection of the perturbed collisionless Boltzmann equation, and assemble the global evolutionary equations of nodal distribution functions. The FEM is highly adaptable to all kinds of potential and density... 

I utilize the Petrov-Galerkin formulation and develop a new method for solving the unsteady collisionless Boltzmann equation in both the linear and nonlinear regimes. In the first-order approximation, the method reduces to a linear eigen-value problem which is solved using standard numerical methods. I apply the method to the dynamics of a model stellar disk which is embedded in the field of a soft-centered logarithmic potential. The outcome is the full spectrum of eigen-frequencies and their conjugate normal modes for prescribed azimuthal wavenumbers. The results show that the fundamental bar mode is isolated in the frequency space, while spiral modes belong to discrete families that... 

This chapter covers a part of the spectrum of neural-network uses in analytical chemistry. Different architectures of neural networks are described briefly. The chapter focuses on the development of three-layer artificial neural network for modeling the anti-HIV activity of the HETP derivatives and activity parameters (pIC 50) of heparanase inhibitors. The use of a genetic algorithm-kernel partial least squares algorithm combined with an artificial neural network (GA-KPLS-ANN) is described for predicting the activities of a series of aromatic sulfonamides. The retention behavior of terpenes and volatile organic compounds and predicting the response surface of different detection systems are... 

I decompose the unstable growing modes of stellar disks to their Fourier components and present the physical mechanism of instabilities in the context of resonances. When the equilibrium distribution function is a nonunifonn function of the orbital angular momentum, the capture of stars into the corotation resonance imbalances the disk angular momentum and triggers growing bar and spiral modes. The stellar disk can then recover its angular momentum balance through the response of nonresonant stars. I carry out a complete analysis of orbital structure corresponding to each Fourier component in the radial angle and present a mathematical condition for the occurrence of van Kampen modes, which... 

Hydroxylated aromatic compounds (HACs) are considered to be primary pollutants in a wide variety of industrial wastewaters. Horseradish peroxidase (HRP) is suitable for the removal of these toxic substances. However, development of a mathematical model and optimization of the HRP-based treatment considering the economical issues by novel methods is a necessity. In the present study, optimization of phenol removal from wastewater by horseradish peroxidase (HRP) was carried out using response surface methodology (RSM) and central composite design (CCD). As the initial experimental design, 2 4-1 half-fraction factorial design (H-FFD) is accomplished in triplicate at two levels to select the... 

In this letter, we study a receiver architecture technique for joint resource allocation in a downlink (DL) multi-user multi-carrier non-orthogonal multiple access (MC-NOMA) network with simultaneous wireless information and power transfer (SWIPT). In this framework, the subcarrier set is partitioned into two groups that are assigned to perform information decoding (ID) and energy harvesting (EH) at the receiver side based on the optimization problem. This letter seeks to maximize energy harvesting while meeting a minimum data-rate requirement for each user. The underlying optimization problem is mixed-integer non-linear programming (MINLP). To that end, we employ the monotonic optimization...