Sharif Digital Repository

Scaled model test in towing tank is a common method to predict the ship resistance in calm water. The scale effects are dominant in these tests because the Reynolds and Froude numbers of the model and full-scale ship cannot be equal. There is a sufficient amount of knowledge about the displacement hulls which have limited speed ranges in most cases. However, scarcity of published data on high-speed crafts is noticed. The influence of the model length on ship resistance varies in different speeds, so it should be studied in more detail. The extrapolation method of model ship resistance to full scale is studied in this paper for high-speed monohulls. Resistance model tests of semi-displacement... 

Enlargement of ship size in recent decades and no change in the harbors and approach channels have resulted in global attention toward navigation in shallow and confined waters. A phenomenon which restricts ship navigation in shallow waters is reduction of under-keel clearance in terms of sinkage and dynamic trim, which is called squatting. Due to the complexity of flow around the ship hull, one of the best methods for predicting the ship squat is the experimental approach based on systematic model tests in the towing tank. In this study, model tests for tanker ship model and traditional Persian Gulf and Oman Sea vessel called dhow had been performed in the towing tank and the squat of the... 

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained  

Plasmonic Sierpinski nanocarpet as back structure for a thin film Si solar cell is investigated. We demonstrate that ultra-broadband light trapping can be obtained by placing square metallic nanoridges with Sierpinski pattern on the back contact of the thin film solar cell. The multiple-scale plasmonic fractal structure allows excitation of localized surface plasmons and surface plasmon polaritons in multiple wavelengths leading to obvious absorption enhancements in a wide frequency range. Full wave simulations show that 109 % increase of the short-circuit current density for a 200 nm thick solar cell, is achievable by the proposed fractal back structure. The amount of light absorbed in the... 

In this paper, we evaluate how traffic-load dependent vehicle routing at intersections is able to improve the connectivity status of all streets. To this end, we consider a VANET scenario, comprised of several streets and intersections. Then, we focus on two vehicle routing algorithms, one based on the distance to destination, i.e., traffic-load independent (TLI) algorithm, and another one based on both distance to destination and traffic load status of the local streets, i.e., traffic-load dependent (TLD) algorithm. By employing a simple mobility model based on an open BCMP queueing network, we derive the spatial traffic distribution at two cases. Afterwards, we propose a simple algorithm... 

Aim: The aim of this study was to search for metabolic biomarkers of Crohn's disease (CD). Background: Crohn's disease (CD) is a type of inflammatory bowel disease that causes a wide variety of symptoms. CD can influence any part of the gastrointestinal tract from mouth to anus. CD is not easily diagnosed because monitoring tools are currently insufficient. Thus, the discovery of proper methods is needed for early diagnosis of CD. Patients and methods: We utilized metabolic profiling using proton nuclear magnetic resonance spectroscopy (1HNMR) to find the metabolites in serum. Classification of CD and healthy subject was done using partial least squares discriminant analysis (PLS-DA).... 

The effect of bulging of domain wall (DW) on the magnetoresistance (MR) is investigated. With taking into account the auto-correlation between the points of the interface, one can formulate the mobility within the relaxation time approximation scheme. The results show that the bulging of DW, evaluated with the commonly accepted magnetic parameters for typical ferromagnetic materials of Co, Fe and Ni, has a countable role into the MR  

This paper presents a new method for eye detection in a sequence of video pictures. We first find the face region using the features of skin's color, then the location of eye is determined by applying three cues on the detected face region. The first cue is the eye intensity and color, because the intensity of each eye region is relatively low and its color differs from the color of surrounding skin. The second cue is based on the position and size of eyes. The third cue is based on the convolution of proposed-eye-variance-filter with the eye-window candidates. After finding the precise location of eye, it will be tracked in a finite search window. We have evaluated and tested the presented... 

In this article, a v2f model is employed to conduct a series of computations of incompressible flow in a periodic array of square cylinders simulating a porous media. A Galerkin/least-squares finite element formulation employing equal order velocity-pressure elements is used to discretize the governing equations. The Reynolds number is varied from 1000 to 84,000 and different values of porosities are considered in the calculations. Results are compared to the available data in the literature. The v2f model exhibits superior accuracy with respect to κ - ε results and is closer to LES calculations. The macroscopic pressure gradients for all porosities studied showed a good agreement with... 

In this article a v2f model is employed to conduct a series of computations of incompressible flow in a periodic array of square cylinders simulating a porous media. Galerkin/Least-Squares finite element formulation employing equal order velocity-pressure elements is used to discretize the governing equations. The Reynolds number is varied from 1000 to 50,000 and different values of porosities are considered in the calculations. Results are compared with the available data in the literature. v2f model exhibits superior accuracy with respect to k - ε results and is closer to LES calculations. The macroscopic pressure gradients for all porosities studied, showed a good agreement with... 

Aim: This study evaluated serum levels of zinc in patient with CD compare to healthy subjects. Background: Celiac disease (CD) is characterized by small intestinal malabsorption of nutrients as a consequence of ingestion of wheat gluten. Zinc is an essential trace element that it has vital biological functions. Patients and methods: Sera of 30 celiac cases and 30 healthy normal cohorts as control group were obtained. Atomic absorption spectrophotometer was employed for estimating serum zinc level. Results: Zinc concentrations in patients diagnosed with CD were significantly lower than healthy subjects (75.97±12 compared with 92.83±18, P-value < 0.0001). Conclusion: The result of this study... 

This research has modelled a queuing system with no standard states. In order to analyse these systems, some parameters such as the mean of waiting time and the length of queue are computed. These situations usually occur when there is delay in the service, for example, in the gas queuing system that cars are unable to leave after receiving the required services due to the presence of other cars in front of them. These kinds of non-standard queuing systems are usually applied to the assembly and production lines. In this paper, a queuing model for the special non-standard state queuing system is developed to be used in gas stations. The proposed model is implemented in fuel stations in Iran... 

In some industries such as the consumable product industry because of small differences between products made by various companies, customer loyalty is directly related to the availability of products required at that time. In other words, in such industries demand cannot be backlogged but can be totally or partly lost. So companies of this group use make-to-stock (MTS) production policy. Therefore, in these supply chains, final product warehouses play a very important role, which will be highlighted by considering the demand uncertainty as it happens in real world, especially in the consumable product industries in which demand easily varies according to the customer's taste variation,... 

The iterated perturbation theory (IPT) equations of the dynamical mean field theory (DMFT) for the half-filled Hubbard model are solved on nearly real frequencies at various values of the Hubbard parameters, U, to investigate the nature of metal-insulator transition (MIT) at finite temperatures. This method avoids the instabilities associated with the infamous Padé analytic continuation and reveals fine structures across the MIT at finite temperatures, which cannot be captured by conventional methods for solving DMFT-IPT equations on Matsubara frequencies. Our method suggests that at finite temperatures, there is a crossover from a bad metal to a bad insulator in which the height of the... 

This study is dedicated to order penetration point (OPP) strategic decision making which is the boundary between make-to-order (MTO) and make-to-stock (MTS) policies. A multiproduct multiechelon production supply chain is considered where the first production stage manufactures semifinished products based on an MTS policy to supply the second production stage which operates on the MTO policy. The producer desires to find the optimal fraction of processing time fulfilled by supplier and optimal semifinished products buffer capacity in OPP. To calculate system performance indexes, the matrix geometric method is employed. Afterward, optimal solutions are obtained by enumeration and direct... 

Speed and price are the two most important factors in customer satisfaction and business success in today's competitive environment. Time-based product differentiation and segment pricing have provided firms with a great opportunity to profit enhancement. This paper presents a coding system for pricing/queuing models in the literature. In this article, a service/make-to-order firm with heterogeneous price and delivery time-sensitive customers as an M/M/1 queuing system is analyzed. The firm uses customers' heterogeneity to create market segments. Products offered to each segment differ only in price and delivery time. The objective of this profit-maximizing firm is to determine optimal...