Techno Press
Tp_Editing System.E (TES.E)
Login Search

Volume 2, Number 4, October 2017
All Articles are Open Access

There are many plain concrete arch bridges in Iran that have been used as railway bridges for more than seventy years. Owe to the fact that these bridges have not been designed seismically, and even may be loaded under high-speed trains, evaluation of fundamental frequencies of the bridges against earthquake and high-speed train vibrations is necessary for considering dynamics effects. To evaluate complex behavior of these bridges, results of field tests are useful. Since it is not possible to perform field tests for all arch bridges, these structures should be simulated correctly by computers for structural assessment. Several parameters are employed to describe the bridges, such as number of spans, length of spans, geometrical and material properties. In this study, results of field tests are used for modal analysis and adapted for 64 three dimensional finite element models with various physical parameters. Computer simulations show length of spans has important effect on fundamental frequencies of plain concrete arch bridge and modal deformations of bridges is in longitudinal and transverse directions. Also, these results demonstrate that fundamental frequencies of bridges decrease after increasing span length and number of spans. Plus, some relations based in the number of spans (n) and span length (l) are proposed for calculation of fundamental frequencies of plain concrete arch bridge.

Key Words
plain concrete arch bridges; three dimensional finite element modeling; modal analysis; fundamental frequencies

Adel Mahmoudi Moazam: Research Institute of Shakhes Pajouh, Esfahan, Iran
Nemat Hasani: Abbaspour School of Engineering, Shahid Beheshti University, Tehran, Iran
Mahdi Yazdani: Department of Civil Engineering, Faculty of Engineering, Arak University, Arak, Iran

In this work, a comparative study of multi-objective meta-heuristics (MOMHs) for optimum design of a walking tractor handlebar is conducted in order to reduce the structural mass and increase structural static and dynamic stiffness. The design problem has objective functions as maximising structural natural frequencies, minimising structural mass, bending deflection and torsional deflection with stress constraints. The problem is classified as a many-objective optimisation since there are more than three objectives. Design variables are structural shape and size. Several well established multi-objective optimisers are employed to solve the proposed many-objective optimisation problems of the walking tractor handlebar. The results are compared whereas optimum design solutions of the walking tractor handlebar are illustrated.

Key Words
many-objective optimisation; natural frequency; walking tractor handlebar; structural stiffness; vibration suppression

Apichit Mahachai, Sujin Bureerat and Nantiwat Pholdee: Sustainable and Infrastructure Research and Development Center, Department of Mechanical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen, 40002, Thailand

High frequency full bridge series resonant inverters have become increasingly popular among power supply designers. One of the most important parameter for a High Frequency Full Bridge Series Resonant Inverter is optimal coil design. The optimal coil designing procedure is not a easy task.. This paper deals with the New Approach to Optimal Design Procedure for a Real-time High Frequency Full Bridge Series Resonant Inverter in Induction Heating Equipment devices. A new design to experimental modelling of the physical properties and a practical power input simulation process for the non-sinusoidal input waveform is accepted. The design sensitivity analysis with Levenberg-Marquardt technique is used for the optimal design process. The proposed technique is applied to an Induction Heating Equipment devices model and the result is verified by real-time experiment. The main advantages of this design technique is to achieve more accurate temperature control with a huge amount of power saving.

Key Words
induction heating; optimal design; COMSOL; full bridge inverter; resonant

Sujit Dhar: Department of Electrical and Electronics Engineering, Neotia Institute of Technology Management and Science,
Jhinga, Diamond Harbour Road, South 24 Parganas, West Bengal 743368, India
Biswajit Dutta: Department of Electrical Engineering, Seacom Engineering College, JL-2, Jaladhulagori, Sankrail, Howrah, West Bengal 711302, India
Debasmita Ghoshroy: Department of Electronics Engineering, Banasthali University, Niwai-Jodhpuriya Road, Vanasthali, Rajasthan 304022, India
Debabrata Roy and Ankur Ganguly: Department of Electrical Engineering, Techno India-Batanagar, B7-360/New, Ward No. 30, Maheshtala, West Bengal 700141, India
Pradip Kumar Sadhu: Department of Electrical Engineering, Indian Institute of Technology (Indian School of Mines),
Dhanbad, Jharkhand 826004, India
Amar Nath Sanyal: Department of Electrical Engineering, Jadavpur University, Jadavpur, Kolkata, West Bengal 700032, India
Soumya Das: Department of Electrical Engineering, University Institute of Technology, Burdwan, West Bengal, India

There are several claimed benefits for the impact of design patterns (DPs) on software quality. However, the association between design patterns and fault-proneness has been a controversial issue. In this work, we evaluate the fault-proneness of design patterns at four levels: the design level, category level, pattern level, and role level. We used five subject systems in our empirical study. As a result, we found that, at the design level, the classes that participate in the design patterns are less fault-prone than the non-participant classes. At the category level, we found that the classes that participate in the behavioral and structural categories are less fault-prone than the non-participant classes. In addition, we found that the classes that participate in the structural design patterns are less fault-prone than the classes that participate in the other categories. At the pattern level, we found that only five patterns show significant associations with fault-proneness: builder, factory method, adapter, composite, and decorator. All of these patterns except for builder show that the classes that participate in each one of them are less fault-prone than the non-participant classes in that pattern. The classes that participate in the builder design pattern were more fault-prone than the non-participant classes and the classes that participate in several patterns: the adapter, the composite, and the decorator design patterns. At the role level, the most significant differences were between the classes that participate in some roles and the non-participant classes. Only three pairs of design pattern roles show significant differences. These roles are concrete-product vs. concrete-creator, adapter vs. adaptee, and adapter vs. client. The results recommend the use of design patterns because they are less fault-prone in general except for the builder design pattern, which should be applied with care and addressed with more test cases.

Key Words
design patterns; fault-proneness; software quality

Mawal A. Mohammed: Information and Computer Science Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
Mahmoud O. Elish: Computer Science Department, Gulf University for Science and Technology, Mishref, Kuwait

In this study, teaching-learning based optimization (TLBO) is improved by incorporating model of multiple teachers, adaptive teaching factor, self-motivated learning, and learning through tutorial. Modified TLBO (MTLBO) is applied for simultaneous topology, shape, and size optimization of space and planar trusses to study its effectiveness. All the benchmark problems are subjected to stress, displacement, and kinematic stability constraints while design variables are discrete and continuous. Analyses of unacceptable and singular topologies are prohibited by seeing element connectivity through Grubler\'s criterion and the positive definiteness. Performance of MTLBO is compared to TLBO and state-of-the-art algorithms available in literature, such as a genetic algorithm (GA), improved GA, force method and GA, ant colony optimization, adaptive multi-population differential evolution, a firefly algorithm, group search optimization (GSO), improved GSO, and intelligent garbage can decision-making model evolution algorithm. It is observed that MTLBO has performed better or found nearly the same optimum solutions.

Key Words
meta-heuristic algorithms; truss design; topology; shape, and size optimization; structural optimization

Ghanshyam G. Tejani: Department of Mechanical Engineering, RK University, Rajkot, Gujarat, India
Vimal J. Savsani and Vivek K. Patel: Department of Mechanical Engineering, Pandit deendayal petroleum University, Gandhinagar, Gujarat, India
Sujin Bureerat: Sustainable Infrastructure Research and Development Center, Department of Mechanical Engineering,
Khon Kaen University, Thailand

Inspections of ancient metallic bridges have illustrated fatigue cracking in riveted connections. This paper presents a comparison between two alternative finite element (FE) models proposed to predict the fatigue strength of a single shear and single rivet connection. The first model is based on solid finite elements as well as on contact elements, to simulate contact between the components of the connection. The second model is built using shell finite elements in order to model the plates of the riveted connection. Fatigue life predictions are carried out for the shear splice, integrating both crack initiation and crack propagation lives, resulting from the two alternative FE models. Global fatigue results, taking into account several clamping stresses on rivet, are compared with available experimental results. Proposed comparisons between predictions and experimental data illustrated that the proposed two-stage model yields consistent results.

Key Words
fatigue; S-N curve; finite element model; riveted connections; ancient bridges

Jose A.F.O. Correia, Abílio M.P. de Jesus, Antonio L.L. Silva and Rui A.B. Calcada: Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
Bruno Pedrosa and Carlos Rebelo: Department of Civil Engineering, University of Coimbra, Rua Luis Reis Santos, 3030-788 Coimbra, Portugal

Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2021 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-2-736-6800, Fax : +82-2-736-6801, Email: