Showing papers by "Iran University of Science and Technology published in 2014"

ISRM-Suggested Method for Determining the Mode I Static Fracture Toughness Using Semi-Circular Bend Specimen

Abstract: The International Society for Rock Mechanics has so far developed two standard methods for the determination of static fracture toughness of rock. They used three different core-based specimens and tests were to be performed on a typical laboratory compression or tension load frame. Another method to determine the mode I fracture toughness of rock using semi-circular bend specimen is herein presented. The specimen is semi-circular in shape and made from typical cores taken from the rock with any relative material directions noted. The specimens are tested in three-point bending using a laboratory compression test instrument. The failure load along with its dimensions is used to determine the fracture toughness. Most sedimentary rocks which are layered in structure may exhibit fracture properties that depend on the orientation and therefore measurements in more than one material direction may be necessary. The fracture toughness measurements are expected to yield a size-independent material property if certain minimum specimen size requirements are satisfied.

Dynamic supply chain network design for the supply of blood in disasters: A robust model with real world application

Abstract: This paper presents a robust network design model for the supply of blood during and after disasters. A practical optimization model is developed that can assist in blood facility location and allocation decisions for multiple post-disaster periods. The application of the proposed model is investigated in a case problem where real data is utilized to design a network for emergency supply of blood during potential disasters. Our analysis on the tradeoff between solution robustness and model robustness arrives at important practical insights. The performance of the proposed ‘robust optimization’ approach is also compared with that of an ‘expected value’ approach.

An accelerated Benders decomposition algorithm for sustainable supply chain network design under uncertainty: A case study of medical needle and syringe supply chain

Abstract: This paper proposes a multi-objective possibilistic programming model to design a sustainable medical supply chain network under uncertainty considering conflicting economic, environmental and social objectives. Effective social and environmental life cycle assessment-based methods are incorporated in the model to estimate the relevant environmental and social impacts. An accelerated Benders decomposition algorithm utilizing three efficient acceleration mechanisms is devised to cope with computational complexity of solving the proposed model. Computational analysis is also provided by using a medical industrial case study to present the significance of the proposed model as well as the efficiency of the accelerated Benders decomposition algorithm.

Common fixed point of generalized weak contractive mappings in partially ordered b-metric spaces

Abstract: We prove some common fixed point results for four mappings satisfying generalized weak contractive condition in partially ordered complete b-metric spaces. Our results extend and improve several comparable results in the existing literature

A Multiobjective Particle Swarm Optimization for Sizing and Placement of DGs from DG Owner's and Distribution Company's Viewpoints

Abstract: Distributed generations (DGs) have significant benefits in the electric power industry, such as a reduction in CO2 and NOX emissions in electricity generation, improvement of voltage profile in distribution feeders, amending voltage stability in heavy load levels, enhancement of reliability and power quality, as well as securing the power market. Despite the numerous advantages of DG technologies, weak capability in dispatching and management of DGs is a major challenge for distribution system operators. Hence, during recent years, several studies about various aspects of control, operation, placement, and sizing of DGs have been conducted. This paper presents a novel application of multiobjective particle swarm optimization with the aim of determining the optimal DGs places, sizes, and their generated power contract price. In the proposed multiobjective optimization, not only are the operational aspects, such as improving voltage profile and stability, power-loss reduction, and reliability enhancement taken into account, but also an economic analysis is performed based on the distribution company's and DG owner's viewpoints. The simulation study is performed on the IEEE 33-bus distribution test system and the consequent discussions prove the effectiveness of the proposed approach.

Preparation and Mechanical Properties of Graphene Oxide: Cement Nanocomposites

Abstract: We investigate the performance of graphene oxide (GO) in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1–2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found that the tensile strength of the cement mortar increased with GO content, reaching 1.5%, a 48% increase in tensile strength. Ultra high-resolution field emission scanning electron microscopy (FE-SEM) used to observe the fracture surface of samples containing 1.5 wt% GO indicated that the nano-GO flakes were well dispersed in the matrix, and no aggregates were observed. FE-SEM observation also revealed good bonding between the GO surfaces and the surrounding cement matrix. In addition, XRD diffraction data showed growth of the calcium silicate hydrates (C-S-H) gels in GO cement mortar compared with the normal cement mortar.

Various battery models for various simulation studies and applications

Abstract: Batteries are one of the most common devices used for saving electrical energy in various applications. It is necessary to understand the battery behavior and performance during charge and discharge cycles. An accurate model of a battery with a specific application is needed for an appropriate analysis and simulation. Therefore, in the field of battery modeling, various models have been proposed. This paper presents an overview of several electrical battery models. These models are classified into six categories. The parameter details of a battery model will not be computed but a brief description of them is given. Furthermore, the applications of each model are discussed. Finally, a comparison between presented models will be made.

Design and evaluation of chitosan/hydroxyapatite composite nanofiber membrane for the removal of heavy metal ions from aqueous solution

Abstract: The performance of chitosan/hydroxyapatite (Cs/HAp) composite nanofiber membrane prepared by electrospinning process for the removal of lead, cobalt and nickel ions from aqueous solution was investigated. The prepared nanofiber membranes were characterized by FTIR, SEM and BET analysis. A response surface methodology based on Box–Behnken Design (BBD) was used to predict the average diameter of electrospun nanofibers. In optimum conditions (voltage of 18.90 kV, tip-collector distance of 15.60 cm and flow rate of 0.43 ml/h), the minimum experimental fiber diameter was obtained 198 nm which was in good agreement with the predicted value by the BBD analysis (200.6 nm). Then, the adsorption experiments were carried out to investigate the effect of different adsorption parameters, such as contact time, initial concentration and temperature in a batch system. The kinetic and equilibrium data were well described by pseudo-second-order and Langmuir models, respectively. Thermodynamic parameters were evaluated to obtain the nature of adsorption process onto the Cs/HAp composite nanofibers. The obtained results of reusability of nanofiber membrane after five sorption–desorption cycles offer promising potential in industrial activities.

A simple, sensitive and secure image encryption algorithm based on hyper-chaotic system with only one round diffusion process

Abstract: Based on hyper-chaotic systems, a novel image encryption algorithm is introduced in this paper. The advantages of our proposed approach are that it can be realized easily in one round diffusion process and is computationally very simple while attaining high security level, high key sensitivity, high plaintext sensitivity and other properties simultaneously. The key stream generated by hyper-chaotic system is related to the original image. Moreover, to encrypt each pixel, we use the sum of pixels which are located after that pixel. The algorithm uses different summations when encrypting different input images (even with the same sequence based on hyper-chaotic system). This, in turn, will considerably enhance the cryptosystem resistance against known/chosen-plaintext and differential attacks. The change rate of the number of pixels in the cipher-image when only one pixel of the original image is modified (NPCR) and the Unified Average Changing Intensity (UACI) are already very high (NPCR?>?99.80233 % and UACI?>?33.55484 %). Also, experimental results such as key space analysis, histograms, correlation coefficients, information entropy, peak signal-to-noise ratio, key sensitivity analysis, differential analysis and decryption quality, show that the proposed image encryption algorithm is secure and reliable, with high potential to be adopted for the secure image communication applications.

Three-Dimensional Beamforming: A new enabling technology for 5G wireless networks

Abstract: It is anticipated that the mobile data traffic will grow 1,000 times higher from 2010 to 2020 with a rate of roughly a factor of two per year [1]. This increasing demand for data in next-generation mobile broadband networks will lead to many challenges for system engineers and service providers. To address these issues and meet the stringent demands in coming years, innovative and practical solutions should be identified that are able to provide higher spectral efficiency, better performance, and broader coverage. Next generations of wireless cellular networks, which are known as fifth generation (5G) or beyond fourth generation (B4G) wireless networks, are expected to produce higher data rates for mobile subscribers in the order of tens of gigabits per second (Gbit/s) and support a wide range of services. Despite the absence of official standards for the 5G, the data rate of 1?Gbit/s per user anywhere for 5G mobile networks is expected to be deployed beyond 2020.

An Iranian License Plate Recognition System Based on Color Features

Abstract: In this paper, an Iranian vehicle license plate recognition system based on a new localization approach, which is modified to reflect the local context, is proposed, along with a hybrid classifier that recognizes license plate characters. The method presented here is based on a modified template-matching technique by the analysis of target color pixels to detect the location of a vehicle's license plate. A modified strip search enables localization of the standard color-geometric template utilized in Iran and several European countries. This approach uses periodic strip search to find the hue of each pixel on demand. In addition, when a group of target pixels is detected, it is analyzed to verify that its shape and aspect ratio match those of the standard license plate. In addition to being scale and rotation invariant, this method avoids time-consuming image algorithms and transformations for the whole image pixels, such as resizing and Hough, Fourier, and wavelet transforms, thereby cutting down the detection response time. License plate characters are recognized by a hybrid classifier that comprises a decision tree and a support vector machine with a homogeneous fifth-degree polynomial kernel. The performance detection rate and the overall system performance achieved are 96% and 94%, respectively.

One-pot three-component synthesis of pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolines using Fe3O4@SiO2–OSO3H as an efficient heterogeneous nanocatalyst

Abstract: The synthesis of pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolines via a one-pot three-component reaction by using benzene-1,2-dicarbaldehyde, trimethylsilylcyanide and various pyridin-2-amines in the presence of a catalytic amount of superparamagnetic nano-Fe3O4@SiO2 anchored sulfuric acid in ethanol in good-to-high yields is described.