Sharif Digital Repository

The effect of the asymmetric water entry over a submerged part of a ship on the hydrodynamic impact is investigated numerically. A wedge body is considered and the problem is assumed to be two-dimensional. The results of symmetric and asymmetric impacts are compared. The effect is found significant in the numerical simulation. The maximum hydro-dynamic pressure at a heel angle of 10 degrees becomes about 95% more than that of the symmetric entry. The result of the present work proves the importance of asymmetrical hydrodynamic impact loading for structural design of a ship. Besides, the numerical procedure is not limited to a wedge type cross section and it is possible to apply it for any... 

The effect of ihe asymmetric water entry over a submerged part of a ship on the hydrodynamic impact is investigated numerically. A wedge body is considered 10 study and the problem is assumed to be two-dimensional. The Results of symmetric and asymmetric impacts are compared together. The effect is found significant in the numerical simulation. The maximum hydrodynamic pressure at a heel angle of 10 degrees becomes about 95% more than that of the symmetric entry. The result of the present, work proves the importance of asymmetrical hydrodynamic impact leading for structural design of a ship. Besides, the numerical procedure is not limited to a wedge type cross section and it is possible to... 

In this paper, "Subspace" method is generalized to asymmetrical case. In the new algorithm described here, "Lanczos" method is used to find the first subspace and to solve the eigenvalue problem resulted in generalized subspace method. To solve the standard eigenvalue problem developed by "Lanczos" method "Jacoby" method is used. If eigenvalue problem includes damping matrix, that will be imported in new defined mass and stiffness matrices  

We consider a macroscopic quantum system subjected to an asymmetric double-well potential in a harmonic environment. By using a time-dependent approach, we calculate tunnelling probabilities for the system which contain oscillation effects. To show how one can decide between quantum mechanics and the implications of macrorealism assumptions, a given form of Leggett-Garg inequality is considered. The violation of this inequality occurs for a broader range of the system-environment interactions, compared to previous results obtained for two-level systems. Assuming that the coupling strength between the system and the environment can be controlled with time, one can see the violation even for... 

We consider a Dynkin game where the seller possesses additional information compared to the buyer. The additional information is described by a random variable taking finitely many values. We show that the game possesses a value and we provide a necessary and sufficient condition for the existence of a Nash equilibrium. Results are illustrated with an explicit example. © 2018, Iranian Mathematical Society  

At the first glance, it seems that asymmetry in geometry, mass, and stiffness cause torsion, while there are systems in which, despite the symmetry in all these parameters, the transferred energy to the torsional mode is more than the translational mode. The main purpose of this research was to study the torsional mode of a symmetric system in terms of geometry, mass, and stiffness, then investigate the effect of mass eccentricity and stiffness eccentricity. This is a fundamental problem and its main applications are in the buildings, automobile industry, and offshore structures. Parametric calculations on the free vibration equation of a completely symmetric system show that in a system... 

Asymmetric Half-Bridge converters are widely used as the front-end DC-DC converter in Distributed Power Systems. Added Range windings are proposed to increase the efficiency of these converters. Activating and deactivating these windings produce transient effect in the output voltage. In this study, an optinml controller based on the Linear Quadratic Gaussian (LQG) method is designed for the efficient regulation of the output voltage of an asymnetric half-bridge controller. The intent of implementing LQG control is to ninimize the output voltage transient produced by range switch operation due to input voltage variations. Simulation results are presented to compare the performance of the new... 

We consider a multi-species generalization of the Asymmetric Simple Exclusion Process on an open chain, in which particles hop with their characteristic hopping rates and fast particles can overtake slow ones. The number of species is arbitrary and the hopping rates can be selected from a discrete or continuous distribution. We determine exactly the phase structure of this model and show how the phase diagram of the 1-species ASEP is modified. Depending on the distribution of hopping rates, the system can exist in a three-phase regime or a two-phase regime. In the three-phase regime the phase structure is almost the same as in the one species case, that is, there are the low density, the... 

In this article, the one-dimensional phenomenological constitutive model originally proposed by Brinson for shape memory alloys is improved to predict asymmetric behavior in tension and compression. We propose an approach that decomposes stress-induced martensite volume fraction into two parts, one in tension and one in compression. Results of numerical examples show reasonable agreement with experimental data. Moreover, we implement the proposed model in a user-defined material subroutine in the nonlinear finite element software ABAQUS/Standard as a two-dimensional Euler-Bernoulli beam element. We simulate several beam problems and a shape memory alloy staple. Regarding the results, the... 

Estimation of petroleum fractions properties is one of the major problems in the reservoir fluids analysis, due to the fact that they cannot exactly be diagnosed and their constituents are not available clearly. In this study, a simple model has been developed to estimate the viscosity of pure hydrocarbon substances, bitumens, size-asymmetric mixtures and reservoir fluids (containing unknown hydrocarbon mixtures or petroleum fractions). The proposed model has been extended based on the two conventional and physical properties which can be measured for both pure components and unknown mixtures, without requiring to have their components and compositions. This model uses the pressure (P),... 

In this study, N-way partial least squares (NPLS) is proposed to correlate comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC × GC-TOFMS) data of different aromatic oil fractions (fresh and weathered) to their toxicity values. Before NPLS modeling, since drift and wander of baseline interfere with information of sought analytes in GC × GC-TOFMS data, a novel method called two-dimensional asymmetric least squares is thus developed for comprehensive correction of the baseline contributions in both chromatographic dimensions. The algorithm is termed comprehensive because it functions to correct the entire chromatogram in both dimensions and it preserves the... 

We consider an American contingent claim on a financial market where the buyer has additional information. Both agents (seller and buyer) observe the same prices, while the information available to them may differ due to some extra exogenous knowledge the buyer has. The buyer's information flow is modeled by an initial enlargement of the reference filtration. It seems natural to investigate the value of the American contingent claim with asymmetric information. We provide a representation for the cost of the additional information relying on some results on reflected backward stochastic differential equations (RBSDE). This is done by using an interpretation of prices of American contingent... 

The Brushless Doubly-fed Induction Generator (BDFIG) has high potential for wind energy systems, especially for offshore applications where minimum maintenance is vital. The machine low voltage ride through (LVRT) capability in the light of current grid code requirements was investigated using a precise dynamic model. This is particularly important for future multi- MW BDFIGs. This paper shows the necessity for improvements of the BDFIG LVRT capability with presenting a comprehensive analytical study during asymmetrical voltage dips. Analytical studies are conducted to extract a more precise equivalent circuit model of the BDFIG used for analyzing machine dynamic behavior under various fault... 

In this paper, the elastic contact problem of an asymmetrical shallow wedge with a half-plane is considered. The potential function of the contact problem has been obtained through a simple approach. This approach simplifies the routine method of determination of potential functions in elastic contact problems. Then this approach was utilized to solve the aforementioned geometry under frictionless and frictional condition. Utilization of the new relation not only simplifies the procedure of solving contact problems but also is very helpful for fretting fatigue studies. © 2007 Elsevier Ltd. All rights reserved  

Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β-unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β-unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon-carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92% and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β-unsaturated aldehydes, and provide proof of principle that... 

Stepped planing hulls have the potential to reach high-speeds in the sea. The step on the bottom of these vessels influence the pressure distribution and thus stability of the vessel, especially in transverse plane. Understanding the behavior of these vessels in a non-zero heel condition is fundamental in the early stage design. In the current paper, numerical simulation of the viscous flow field around a heeled one-stepped planing hull is performed to evaluate influences of the asymmetric planing on the performance of the vessel. The numerical model is validated in two steps. At the first step, performance of a heeled stepless planing hull operating in calm water is simulated using the... 

We present an emulation design method for converting asymmetrical transmitters to nonreciprocal isolators equipped with time-varying metasurfaces. To illustrate the model, we design a structure using a combination of the photonic crystal (PhC) and time-varying metasurface. Moreover, we propose a general approach for numerical analysis of the time-modulated proposed structure using the extension of the transfer matrix method (TMM) which consists of working through the device one layer at a time and calculating an overall transfer matrix including the time-variation of the permittivity and permeability in each layer. Also, we use an optimization algorithm that is less used in the field of...