4,045 research outputs found

    On groups with the same character degrees as almost simple groups with socle the Mathieu groups

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    Let GG be a finite group and cd(G)cd(G) denote the set of complex irreducible character degrees of GG. In this paper, we prove that if GG is a finite group and HH is an almost simple group whose socle is Mathieu group such that cd(G)=cd(H)cd(G) =cd(H), then there exists an Abelian subgroup AA of GG such that G/AG/A is isomorphic to HH. This study is heading towards the study of an extension of Huppert's conjecture (2000) for almost simple groups.Comment: arXiv admin note: text overlap with arXiv:1108.0010 by other author

    Challenges of Inductive Electric Vehicle Charging Systems in both Stationary and Dynamic Modes

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    Inductive power transfer as an emerging technology has become applicable in wide power ranges including Electric Vehicle, Electric Aircraft, wheelchair, cellphone, scooter and so on. Among them, inductive Electric Vehicle (EV) charging has gained great interest in the last decade due to many merits namely contactless technology, more convenience, full automotive charging process. However, inductive EV charging systems could bring about so many issues and concerns which are addressed in this dissertation. One of the critical challenges addressed in this dissertation is a virtual inertia based IPT controller to prevent the undesirable dynamics imposed by the EVs increasing number in the grid. Another adverse issue solved in this dissertation is detecting any metal object intrusions into the charging zone to the Inductive Power Transfer (IPT) systems before leading to heat generation on the metal or risk of fire. Moreover, in this dissertation, a new self-controlled multi-power level IPT controller is developed that enables EV charging level regulation in a wide range of power; suitable for different applications from golf-cart charging system (light duty EV) to truck (heavy duty EV). The proposed controller has many merits including easy to be implemented, cons-effective, and the least complexities compared to conventional PWM methods. Additionally, in this dissertation, the online estimation of IPT parameters using primary measurement including coupling factor, battery current and battery voltage is introduced; the developed method can find immediate applications for the development of adaptive controllers for static and dynamic inductive charging systems. Finally, the last objective of this research is physics-based design optimization techniques for the magnetic structures of inductive EV charging systems for dynamic application (getting charged while in motion). New configuration of IPT transmitting couplers with objective of high-power density, low power loss, low cost and less electromagnetic emission are designed and developed in the lab

    A Routing Algorithm Based on Ant Colony, Local Search and Fuzzy Inference to Improve Energy Consumption in Wireless Sensor Networks

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    Wireless sensor network is a new generation of networks in which the main aim is to collect data from the surrounding environment of network sensors. The major differences of wireless sensor networks with other networks are limited energy resources and relatively low processing capabilities. Therefore, managing power and reducing energy consumption are of great importance in these networks. In this paper, there was presented a mechanism for Wireless sensor network routing which can be more effective regarding the criteria of route length, end–to–end delay and network node energy for the quality of mechanism service. The proposed method used ant colony–based routing algorithm and local enquiry to find optimal routes. Also, a fuzzy inference system was used to determine the route quality which showed better performance compared with equation of route quality. The results of simulating mechanism showed that energy consumption and network efficiency had improved compared with those of previous methods.DOI:http://dx.doi.org/10.11591/ijece.v3i5.362

    Analysis of exerted stresses of final drive in MF 285 tractor by Theoretical and Finite Element Method (FEM)

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    Gears is a rotating cylindrical wheel having tooth cut on it and which meshes with another toothed part to transmit the power or torque.. In this investigation, at first, bending stress and contact stress between sun gear and planet gear tooth were determined using of Lewis and Hertzian equations. Afterward, a 3D model of final drives gear was investigated via FEM method. According to the obtained results, maximum of bending stress and contact stress occurred in Gear 1 and low status of helping gear, according to the results that given in the table 3, maximum bending stress using of theoretical and FEM simulation methods were obtained 918.62 Mpa and 951.82 Mpa, respectively. Also, maximum contact stress in same status using of theoretical and FEM simulation methods were obtained 2952.71 Mpa and 2903.20 Mpa, respectively. The percentage difference between the theoretical and FEM bending stress results and contact stress results are of average 3.48% and 11%, respectively, which are still acceptable. As regards, some parameters are ignored in theoretical calculation such as: radial forces in Lewis equation and tangential forces in Hertzian equation, FEM simulation results are acceptable than theoretical results

    A New Approach for Solving System of Local Fractional Partial Differential Equations

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    In this paper, we apply a new method for solving system of partial differential equations within local fractional derivative operators. The approximate analytical solutions are obtained by using the local fractional Laplace variational iteration method, which is the coupling method of local fractional variational iteration method and Laplace transform. Illustrative examples are included to demonstrate the high accuracy and fast convergence of this new algorithm. The obtained results show that the introduced approach is a promising tool for solving system of linear and nonlinear local fractional differential equations. Furthermore, we show that local fractional Laplace variational iteration method is able to solve a large class of nonlinear problems involving local fractional operators effectively, more easily and accurately; and thus it has been widely applicable in physics and engineering

    Local Fractional Variational Iteration Method for Solving Nonlinear Partial Differential Equations within Local Fractional Operators

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    In this article, the local fractional variational iteration method is proposed to solve nonlinear partial differential equations within local fractional derivative operators. To illustrate the ability and reliability of the method, some examples are illustrated. A comparison between local fractional variational iteration method with the other numerical methods is given, revealing that the proposed method is capable of solving effectively a large number of nonlinear differential equations with high accuracy. In addition, we show that local fractional variational iteration method is able to solve a large class of nonlinear problems involving local fractional operators effectively, more easily and accurately, and thus it has been widely applicable in engineering and physics

    Importance-performance analysis of port’s services quality form perspective of containerized liner shipping

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    One of the important issues in port services is to evaluate the performance of the services. Without evaluating port services and their related components, these services cannot be considered desirable and its quality cannot be enhanced. However, the evaluation and the quality assurance of port services should be accomplished based on a scientific framework and a coherent framework to have desirable results. The importance-performance analysis model is an appropriate framework where each component is evaluated in terms of two dimensions of importance and performance. This study performs performance-importance analysis of ports’ services quality form perspective of containerized liner shipping in the Imam Khomeini port. In this exploratory study, 150 shipping lines experts are chosen, randomly in 2012. The study identifies 28 components of quality in port services and shipping lines’ experts are requested to evaluate these components in terms of two dimensions of importance and performance. Results reveal that there is a gap between the importance and performance of all port services components except three components of 6, 19 and 24. In addition, the results indicate that Importance-Performance Analysis (IPA) model is capable of evaluating and assuring quality in port services and can precisely identify the strengths and weaknesses of the seaport system and provide guidance for strategy formulation for quality improvement

    Surgically Induces Scleral Melting Improved by Topical Erythropoietin: A Case Report

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    Surgically induced scleral necrosis is a rare complication after many types of ocular surgery, including cataract surgery, pterygium surgery, glaucoma surgery, and vitrectomies. This report discusses a 35-year-old woman with Type I diabetes mellitus with multiple episodes of ocular surgeries, including glaucoma device implantation. The subject presented to our clinic with ocular pain and vision loss in the right eye following reoperation for glaucoma device implantation. The subject was managed successfully with topical erythropoietin in her episode of scleral melting. In this case, successful epithelialization and vascularization of the conjunctival defect were observed with the use of topical erythropoietin, resulting in putting off another reoperation. This indicates the usefulness of topical erythropoietin in successfully managing surgically-induced scleral melting cases

    Silicon photonic modulator based on coupled Bragg grating resonators used as phase shifters

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    Bragg gratings with phase-shifts are inserted in a Mach-Zehnder modulator to enhance phase modulation, reduce device length and improve efficiency (Vπ×L=0.28 Vcm). Simulations show 3 nm optical bandwidth corresponding to 50 K operating temperature range
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