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Found 6289 publications

Regularization and multi-level tools in the method of fundamental solutions

Csaba Gáspár

Publication Name: Lecture Notes in Computational Science and Engineering

Publication Date: 2015-01-01

Volume: 100

Issue: Unknown

Page Range: 145-162

Description:

The Method of Fundamental Solution is applied to potential problems. The source and collocation points are supposed to coincide and are located along the boundary. The singularities due to the singularity of the fundamental solution are avoided by several techniques (regularization and desingularization). Both the monopole and the dipole formulations are investigated. The resulting algebraic systems have advantageous properties provided that pure Dirichlet or pure Neumann boundary condition is prescribed. Otherwise, the original problem is converted to a sequence of pure Dirichlet and pure Neumann subproblems, the solutions of which converge rapidly to the solution of the original mixed problem. The iteration is embedded to a multi-level context in a natural way. Thus, the computational cost can be significantly reduced, and the problem of large and ill-conditioned matrices is also avoided.

Open Access: Yes

DOI: 10.1007/978-3-319-06898-5_8

Detection of corrosion resistance of components in cyclic salt spray

Jan Mareček Tamás Ibriksz Vladimír Kročko Štefan Álló

Publication Name: Acta Universitatis Agriculturae Et Silviculturae Mendelianae Brunensis

Publication Date: 2015-01-01

Volume: 63

Issue: 1

Page Range: 9-13

Description:

The aim of this research is, to investigate the influence of two types of cyclic salt spray tests on parts surface treated with galvanizing. On the selected components was performed the method Zn-Ni surface treating on the bath line. Subsequently were the components embedded in the corrosion chamber, where was performed two types of cyclic salt test. In the first test was performed 4 hour salt spray, 8 hours drying, 60 hours condensation and 24 hours drying. Once cycle lasted 96 hours, and it was repeated 4 times. During the second test was performed 2 hours salt spray, 2 hours condensation. The cycle was repeated 4 times, that means 96 hours. After the cycle was performed 72 hours free relaxation in the corrosion chamber, on 20-25 °C temperature. As the research showed, after the cyclic salt spray was no red corrosion on the selected components. The white corrosion appeared only slightly.

Open Access: Yes

DOI: 10.11118/actaun201563010009

Multi-Physics thermal analysis of permanent magnets motors with exterior rotor

Lotfi Abdelhakim

Publication Name: Civil Comp Proceedings

Publication Date: 2015-01-01

Volume: 108

Issue: Unknown

Page Range: Unknown

Description:

This paper presents a magneto-thermal analysis of an external-rotor permanent magnet synchronous machine based on finite element method. The model developed can be used to predict the temperature distribution inside the motor during the rated operation. Electromagnetic computation is carried out with the aid of two twodimensional finite-element simulations of the cross-section of the permanent magnet motor [1]. In addition, the magnetic core losses of the stator and rotor are modelled based on the results from the electromagnetic analysis and a post-processing formula based on the loss-separation principle. To analyse the process of heat transfer in an electrical machine, empirical correlations are used to describe the convective heat transfer from the different surfaces of the permanent magnet motor. The heat transfer coefficients are determined using dimensionless numbers and the Nusselt number [2]. After the loss calculation, the temperatures of the machine are calculated using a three-dimensional finite element method. The results obtained from the model are compared with the experimental results from testing the prototype electric motor.

Open Access: Yes

DOI: DOI not available

Numerical modeling of levees according to Eurocode 7

Edina Koch Ákos Wolf Róbert Szepesházi

Publication Name: Geotechnical Engineering for Infrastructure and Development Proceedings of the Xvi European Conference on Soil Mechanics and Geotechnical Engineering Ecsmge 2015

Publication Date: 2015-01-01

Volume: 4

Issue: Unknown

Page Range: 2019-2024

Description:

In many European countries, flood protection and development of levees has a great importance due to ever-increasing flood levels. The final version of Eurocode 7 includes three chapters that govern the levee design. They suggest mainly conventional concepts and principles but do not provide a comprehensive design methodology for use in practice as it was formerly given in the national standards. Analytical seepage calculations used in present-day practice are based on numerous simplifying assumptions, so they often do not simulate actual conditions. The method of slices, generally used for stability analysis, is sometimes criticized for theoretical reasons. Recently, development of numerical modeling and software have employed coupled finite element analysis for mechanical and hydraulic problems. A single FEM model can apply to levee design, stability analysis, underseepage and through seepage, and analysis of seepage forces. This paper reports research results gained about modeling levees by Plaxis to meet the requirements of the Eurocode 7.

Open Access: Yes

DOI: DOI not available

Structured learning for extraction of daily life log measured by smart phone sensors

János Botzheim Naoyuki Kubota

Publication Name: Smart Innovation Systems and Technologies

Publication Date: 2015-01-01

Volume: 30

Issue: Unknown

Page Range: 277-293

Description:

This chapter deals with producing information using structured learning to extract daily life log measured by smart phone sensors. Acceleration, angular velocity, and movement distance are measured by smart phone sensors and stored as the entries of the daily life log together with the activity information and timestamp.First, this chapter introduces the concept of Informationally Structured Space (ISS) and explains how smart phones can be used for collecting data for the daily life log. Then, structured learning is proposed for estimating the human activities based on the time series of the measured data. The method applies growing neural gas for performing clustering on the data, and spiking neural network for estimating the activity. A modified simple spike response model is applied to reduce the computational cost. The external input values of the spiking neurons depend on the growing neurons, and various metrics are investigated in the input calculation.Experiments are performed for verifying the effectiveness of the proposed method. Finally, the future direction on this research is discussed.

Open Access: Yes

DOI: 10.1007/978-3-319-13545-8_16

Efficient power consumption strategies for stationary sensors connected to GSM network

Gábor Paller Peter Szarmes Gábor Élo

Publication Name: Sensornets 2015 4th International Conference on Sensor Networks Proceedings

Publication Date: 2015-01-01

Volume: Unknown

Issue: Unknown

Page Range: 63-68

Description:

The number of large sensor systems are rapidly growing nowadays in many fields. Well-designed Big Data solutions are able to manage the enormous data flow and create real business benefits. One dynamically growing application area is precision farming. It requires robust and energy-efficient sensors, because the devices are placed outdoors, often in harsh conditions, and there is no power outlet in the middle of a corn field. Power efficiency is one of the major themes of the Internet of Things (IoT). According to the IoT vision, embedded sensors send their data to processing units (either located near to the sensor or on some intermediate gateway device or in the cloud) using heterogeneous transport networks. Some sensors employ short-range network like Bluetooth and some gateway device like a tablet. Other sensors directly connect to wide-area networks like cellular networks. This paper will analyse different communication patterns accomplished over GSM network from the viewpoint of the energy consumption of the sensor device with the assumption that the sensor is stationary. The measurements were done using two different GSM modems designed for embedded systems to ensure that the results represent a wider picture and not some implementation property of a particular GSM modem. Recommendations are given about the strategies applications should follow in order to minimize the energy consumption of their GSM subsystems.

Open Access: Yes

DOI: 10.5220/0005262500630068

Multi-physics thermal analysis of permanent magnets motors with exterior rotor

Lotfi Abdelhakim

Publication Name: Civil Comp Proceedings

Publication Date: 2015-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

This paper presents a magneto-thermal analysis of an external-rotor permanent magnet synchronous machine based on finite element method. The model developed can be used to predict the temperature distribution inside the motor during the rated operation. Electromagnetic computation is carried out with the aid of two twodimensional finite-element simulations of the cross-section of the permanent magnet motor [1]. In addition, the magnetic core losses of the stator and rotor are modelled based on the results from the electromagnetic analysis and a post-processing formula based on the loss-separation principle. To analyse the process of heat transfer in an electrical machine, empirical correlations are used to describe the convective heat transfer from the different surfaces of the permanent magnet motor. The heat transfer coefficients are determined using dimensionless numbers and the Nusselt number [2]. After the loss calculation, the temperatures of the machine are calculated using a three-dimensional finite element method. The results obtained from the model are compared with the experimental results from testing the prototype electric motor.

Open Access: Yes

DOI: DOI not available

Development of a new method for comparing the cold startand the idling operation of internal combustion engines

István Lakatos

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2015-01-01

Volume: 43

Issue: 4

Page Range: 225-231

Description:

In case of public transportation, the protection of the environment and the economic operation are highlighted issues. The cold start and the cold operational procedure of buses must be optimal both in the scope of environment protection and economic aspects (fuel consumption, wear and tear). By taking these factors into consideration, we have analysed the relevant influential factors and elaborated such a measuring system with the aid of which the fuel consumption can be measured continuously during the operation. Fuel consumption measurements were accomplished with the aid of a new measuring system during cold operation and running and on the basis of processing and evaluating the findings we have suggested a new operational procedure.

Open Access: Yes

DOI: 10.3311/PPtr.8087

Enhancement and assessment of engineering soft skills in a game-based learning environment

Lorenzo Ros-McDonnell Csilla Fejes Péter Bajor

Publication Name: Proceedings of the European Conference on Games Based Learning

Publication Date: 2015-01-01

Volume: 2015-January

Issue: Unknown

Page Range: 178-185

Description:

Engineering education literature shares a consensual vision of the importance of soft skills for every workplace. Despite of the growing demand for graduates with high EQ (Emotional Intelligence Quotient), one of the main challenges of the industry is the lack of soft skills, in particular, communication and negotiation skills, problem-solving skills, interpersonal skills, as well as critical and creative thinking skills. This paper investigates the enhancement of skills in a game-based learning environment, which was specifically designed to develop both hard (technical) and soft (personal) skills of engineering students through hands on experiences and observations. The acquired data is gathered using data triangulation, and it consists of self-assessments, observations, questionnaires and technical measurements. Preliminary results indicate that the environment has a significant impact on soft skill development, and show a correlation between soft-skill development and the level of motivation and self-evaluation.

Open Access: Yes

DOI: DOI not available