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An efficient algorithm for the design optimization of the compressible fluid flow problem through a flexible structure is presented. The methodology has three essential parts: first the behavior of compressible flow in a supersonic diffuser was studied numerically in quasi-one-dimensional form using a flux splitting method. Second, a fully coupled sequential iterative procedure was used to solve the steady state aeroelastic problem of a flexible wall diffuser. Finally, a robust Genetic Algorithm was implemented and used to calculate the optimum shape of the flexible wall diffuser for a prescribed pressure distribution. © 2006 Elsevier Ltd. All rights reserved  

In this paper, the compressible gas flow through a pipe subjected to wall heat flux in unsteady condition in the entrance region is investigated numerically. The coupled conservation equations governing turbulent compressible viscous flow in the developing region of a pipe are solved numerically under different thermal boundary conditions. The numerical procedure is a finite-volume-based finite-element method applied to unstructured grids. The convection terms are discretized by the well-defined Roe method, whereas the diffusion terms are discretized by a Galerkin finite-element formulation. The temporal terms are evaluated based on an explicit fourth-order Runge-Kutta scheme. The effect of... 

The authors' research work on pressure drop along gas transmission pipelines raised questions regarding the development length of the corresponding compressible flow and the effect of heat transfer in the entrance region on the pressure drop along the whole length of the pipe. In this paper, laminar, viscous, compressible flow in the entrance region of a pipe is investigated numerically in two dimensions. The numerical procedure is a finite-volume based finite-element method applied on unstructured grids. This combination together with a new method applied for boundary conditions allows accurate computation of the variables in the entrance region. The method is applied to some incompressible... 

The wellhead flow control valve bodies which are the focal point of this failure case study were installed in some of the upstream facilities of Khangiran's sour gas wells. These valve bodies have been operating satisfactorily for 3 years in wet H2S environment before some pits and cracks were detected in all of them during the periodical technical inspections. One failed valve body was investigated by chemical and microstructural analytical techniques to find out the failure cause and provide preventive measures. The valve body alloy was A216-WCC cast carbon steel. During investigation many cracks were observed on the inner surface of the valve body grown from the surface pits. The results... 

The wellhead flow control valve bodies which are the focal point of this failure case study were installed in some of the upstream facilities of Khangiran's sour gas wells. These valve bodies have been operating satisfactorily for 3 years in wet H2S environment before some pits and cracks were detected in all of them during the periodical technical inspections. One failed valve body was investigated by chemical and microstructural analytical techniques to find out the failure cause and provide preventive measures. The valve body alloy was A216-WCC cast carbon steel. During investigation many cracks were observed on the inner surface of the valve body grown from the surface pits. The results... 

In this paper, the authors analyze conditions under which they can be certain on the intensity addition of a given device, such as tapped-delay lines, used in digital incoherent all-optical communication systems. A general expression for phase-induced intensity noise that is applicable to all types of semiconductor lasers is derived by defining an optical self-SNR expression that can be used to analyze and measure phase-induced intensity noise. The result shows that in order to have a minimal phase-induced intensity noise in most digital optical incoherent systems, a large optical self-SNR, e.g., 20 dB or more, is needed. This in turn is shown to place a limit on the maximum rate of... 

Nowadays, the number of digital images has increased so that the management of this volume of data needs an efficient system for browsing, categorising and searching. Automatic image annotation is designed for assigning tags to images for more accurate retrieval. Non-negative matrix factorisation (NMF) is a traditional machine learning technique for decomposing a matrix into a set of basis and coefficients under the non-negative constraints. In this study, the authors propose a two-step algorithm for designing an automatic image annotation system that employs the NMF framework for its first step and a variant of K-nearest neighbourhood as its second step. In the first step, a new multimodal... 

In automatic image annotation (AIA) different features describe images from different aspects or views. Part of information embedded in some views is common for all views, while other parts are individual and specific. In this paper, we present the Mvg-NMF approach, a multi-view-group non-negative matrix factorization (NMF) method for an AIA system which considers both common and individual factors. The NMF framework discovers a latent space by decomposing data into a set of non-negative basis vectors and coefficients. The views divided into homogeneous groups and latent spaces are extracted for each group. After mapping the test images into these spaces, a unified distance matrix is... 

In automatic image annotation (AIA) different features describe images from different aspects or views. Part of information embedded in some views is common for all views, while other parts are individual and specific. In this paper, we present the Mvg-NMF approach, a multi-view-group non-negative matrix factorization (NMF) method for an AIA system which considers both common and individual factors. The NMF framework discovers a latent space by decomposing data into a set of non-negative basis vectors and coefficients. The views divided into homogeneous groups and latent spaces are extracted for each group. After mapping the test images into these spaces, a unified distance matrix is... 

Automatic Image Annotation (AIA) helps image retrieval systems by predicting tags for images. In this paper, we propose an AIA system using Non-negative Matrix Factorization (NMF) framework. The NMF framework discovers a latent space, by factorizing data into a set of non-negative basis and coefficients. To model the images, multiple features are extracted, each one represents images from a specific view. We use multi-view graph regularization NMF and allow NMF to choose a different number of basis vectors for each view. For tag prediction, each test image is mapped onto the multiple latent spaces. The distances of images in these spaces are used to form a unified distance matrix. The... 

Real time road traffic monitoring is one of the challenging problems in machine vision, especially when one is using commercially available PCs as the main processor. In this paper, we describe a real-time method for extracting a few traffic parameters in highways such as, lane change detection, vehicle classification and vehicle counting. In addition, we will explain a real time method for multiple vehicles tracking that has the capability of occlusion detection. Our tracing algorithm uses Kalman filter and background differencing techniques. We used morphological operations for vehicle contour extraction and its recognition. Our algorithm has three phases, detection of pixels on moving... 

With the significant role that warehouse plays in connection to suppliers, distributors, and clients, and considering the costliness of storage systems, efforts have focused on the reduction of procedural expenses. Among the most significant expenses, one involves the distance traveled by operators or S/R machinery for the selection of ordered items; the common solution to which has been through the classification of stored items. Previous articles have focused on linear solutions to the abovementioned problem, such as P-Median. This article shall focus on the problems arising from the said solution, and instead a non-linear method proposed. Further, a heuristic algorithm is produced for the... 

A new and simple receiver structure for reducing the multipath inter-symbole interference (ISI) effect is proposed for infrared diffuse links. In this new method, bit-error rate (BER) performance of the system will be improved significantly without any essential change in the receiver structure. In our analysis, all major noise sources such as ambient light, signal shotnoise, dark current and thermal noise of the receiver are considered. © 2009 IEEE  

Veronica genus (Plantaginaceae) is broadly distributed in different habitats. In this study, the inhibitory activity of free soluble and conjugated phenolic extracts of Veronica persica on key enzymes associated to type 2 diabetes (α-glucosidase and α-amylase) and hypertension (angiotensin I converting enzyme, ACE) was assessed, as well as their antioxidant power. Our results showed that both the extracts inhibited α-amylase, α-glucosidase and ACE in a dose-dependent manner. In particular, free phenolic extract significantly (P < 0.05) inhibited α-glucosidase (IC50 532.97 μg/mL), whereas conjugated phenolic extract significantly (P < 0.05) inhibited a-amylase (IC50 489.73 μg/mL) and ACE... 

In the present work tensile and tear properties of commercially pure titanium with different rolling reductions and specimens directions were investigated. The experimental results showed that in low levels of deformation the microstructure refining and mechanical twins have fewer significant effects on the anisotropic behavior of both tear and tensile properties and the crystallographic texture controls the mechanical properties anisotropy. The increase in rolling reduction up to 50% led to the formation of strong-basal texture and resulted in the activation of almost same deformation systems and isotropic mechanical response. However, at high levels of deformation, due to the split... 

The environmental impact of asbestos fibers on human health and their consequent safety-related problems indicate that there is a significant need to replace this material in all asbestos-containing products. Many different types of fibers have been introduced to replace asbestos fibers. In this study, the performance of silica nano-particles combined with waste paper pulp fibers (sulfite fibers) has been investigated. Different mechanical (compressive and flexural strengths and bending performance), durability (water absorption), physical (bulk density and flowability), and microstructural (scanning electron microscopy) tests were conducted to examine the properties of manufactured green... 

The suspension of titania nanoparticles in different alcohols (methanol, ethanol, and butanol) was prepared and triethanolamine (TEA) was used as a dispersant. The suspensions were characterized by different tests such as sedimentation, zeta potential, and Fourier transform infrared spectroscopy. The electrophoretic deposition (EPD) was performed at various voltages and times. EPD from butanolic suspension (0.8 g/L TEA) showed the slowest kinetics, because of the low electrophoretic mobility of titania nanoparticles in it (2.40 × 10-5 cm2·(V·s)-1). Also, it was observed that at low voltages (5, 10, and 20 V), the EPD kinetics from methanolic suspension (0 g/L TEA) was the fastest; however,... 

The alcoholic suspensions of titania nano-particles were prepared using the methanol, ethanol, isopropanol and butanol as the solvents as well as triethanolamine (TEA) as an dispersant. The colloidal stability of suspensions, both in the absence as well as presence of TEA, was studied by measuring the zeta potential, sedimentation, pH and electrical conductivity of suspensions, dispersant adsorption and particles size distribution. Results showed that in the absence of TEA, the stability of the suspensions increases with the molecular size of alcohol (from methanol to butanol), while the zeta potential decreases. It was also observed that with the addition of TEA up to the optimum dosage (4... 

Lithium ion batteries as one of the most important energy storage equipments, have several challenges including capacity drop as number of cycles increases. Cathode particle coating is an effective approach in improvement of electrochemical performance of the batteries. In this study, TiO2-Ag coating was used to improve NCM cathode performance. The microstructure and crystal structure properties of coated NCMs were evaluated by the FE-SEM and XRD. Electrochemical behavior of the batteries was investigated by cycling performance analysis and EIS. TiO2 coating was deposited as a uniform layer and Ag coating was precipitated as dispersed nanoparticles. The results shows that using of TiO2-Ag... 

This paper introduces the connection-graph-stability method and uses it to establish a new lower bound on the algebraic connectivity of graphs (the second smallest eigenvalue of the Laplacian matrix of the graph) that is sharper than the previously published bounds. The connection-graph-stability score for each edge is defined as the sum of the lengths of the shortest paths making use of that edge. We prove that the algebraic connectivity of the graph is bounded below by the size of the graph divided by the maximum connection-graph-stability score assigned to the edges