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CONTENTS
Volume 6, Number 2, June 2017
 

Abstract
In this paper, thermal vibration behavior of nanoscale beams made of functionally graded (FG) materials subjected to various types of thermal loading are investigated. A Reddy shear deformation beam theory which captures both the microstructural and shear deformation effects without the need for any shear correction factors is employed. Material properties of FG nanobeam are assumed to be temperature-dependent and vary gradually along the thickness according to the power-law form. The influence of small scale is captured based on nonlocal elasticity theory of Eringen. The nonlocal equations of motion are derived through Hamilton\'s principle and they are solved applying analytical solution. The comparison of the obtained results is conducted with those of nonlocal Euler-Bernoulli beam theory and it is demonstrated that the proposed modeling predict correctly the vibration responses of FG nanobeams. The effects of nonlocal parameter, material graduation, mode number, slenderness ratio and thermal loading on vibration behavior of the nanobeams are studied in detail.

Key Words
third-order shear deformation beam theory; thermo-mechanical vibration; functionally graded nanobeam; Eringen elasticity theory

Address
Farzad Ebrahimi and Mohammad Reza Barati: Department of Mechanical Engineering, Faculty of Engineering, Imam Khomeini International University, Qazvin, P.O.B. 16818-34149, Iran

Abstract
Platinum is a transition metal that is very resistant to corrosion. It is used as catalyst for converting methyl alcohol to formaldehyde, as catalytic converter in cars, for hydrocracking of heavy oils, in Fuel Cell devices etc. Moreover, Platinum compounds are important ingredient for cancer chemotherapy drugs. The nano forms of Platinum due to its unique physico-chemical properties that are not found in its bulk counterpart, has been found to be of great importance in electronics, optoelectronics, enzyme immobilization etc. The stability of Platinum nanoparticles has supported its use for the development of efficient and durable proton exchange membrane Fuel Cells. The present review concentrates on the use of Platinum conjugated with various metal or compounds, to fabricate nanocomposites, to enhance the efficiency of Platinum nanoparticles. The recent advances in the synthesis methods of different Platinum-based nanocomposites and their applications in Fuel Cell, sensors, bioimaging, light emitting diode, dye sensitized solar cell, hydrogen generation and in biosystems has also been discussed.

Key Words
Pt; nanocomposite; electrocatalyst; Pt NP; nanoparticles

Address
Madhuri Sharon, Isaac Nandgavkar and Maheshwar Sharon: Walchand Centre for Research in Nanotechnology and Bionanotechnology, W.H. Marg, Ashok Chowk, Solapur 413006, Maharashtra, India


Abstract
The terrorist attacks and dangers by bomb blast have turned into an emerging issue throughout the world and the protection of the people and structures against terrorist acts depends on the prediction of the response of structures under blast and shock load. In this paper, behavior of aluminum and unidirectionally reinforced E-Glass Epoxy composite plates with and without focal circular holes subjected to shock loading has been identified. For isotropic and orthotropic plates (with and without holes) the classical normal mode approach has been utilized as a part of the processing of theoretical results. To obtain the accurate results, convergence of the results was considered and a number of modes were selected for plate with and without hole individually. Using a shock tube as a loading device, tests have been conducted to composite plates to verify the theoretical results. Moreover, peak dynamic strains, investigated by experiments are also compared with the theoretical values and deviation of the results are discussed accordingly. The strain-time histories are likewise indicated for a specific gauge area for aluminum and composite plates. Comparison of dynamic-amplification factors between the isotropic and the orthotropic plates with and without hole has been discussed.

Key Words
aluminum; blast; composite plate; dynamic-amplification factor, epoxy plate; isotropic plate; orthotropic plate; shock load; shock tube

Address
Imrose B. Muhit: School of Civil and Environmental Engineering, Chung-Ang University, Seoul, Korea
Mostofa N. Sakib: Institute of Water and Flood Management, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
Sheikh S. Ahmed: Department of Civil Engineering, University of Asia Pacific, Dhaka, Bangladesh

Abstract
Electro-Discharge machining (EDM) is a thermal process comprising a complex metal removal mechanism. This method works by forming of a plasma channel between the tool and the workpiece electrodes leading to the melting and evaporation of the material to be removed. EDM is considered especially suitable for machining complex contours with high accuracy, as well as for materials that are not amenable to conventional removal methods. However, several phenomena can arise and adversely affect the surface integrity of EDMed workpieces. These have to be taken into account and studied in order to optimize the process. Recently, artificial neural networks (ANN) have emerged as a novel modeling technique that can provide reliable results and readily, be integrated into several technological areas. In this paper, we use an ANN, namely, the multi-layer perceptron and the back propagation network (BPNN) to predict the mean surface roughness of electro-discharge machined surfaces. The comparison of the derived results with experimental findings demonstrates the promising potential of using back propagation neural networks (BPNNs) for getting a reliable and robust approximation of the Surface Roughness of Electro-discharge Machined Components.

Key Words
artificial neural networks (ANNs); back propagation neural networks (BPNNs); mean surface roughness; electro-discharge machining (EDM); normalization

Address
Liborio Cavaleri and Fabio Di Trapani: Department of Civil, Environmental, Aerospace and Materials Engineering (DICAM), University of Palermo, Palermo, Italy
George E. Chatzarakis: Department of Electrical and Electronic Engineering Educators, School of Pedagogical and Technological Education, Athens, Greece
Maria G. Douvika, Konstantinos Roinos and Panagiotis G. Asteris: Computational Mechanics Laboratory, School of Pedagogical and Technological Education, Athens, Greece
Nikolaos M. Vaxevanidis: Laboratory of Manufacturing Processes & Machine Tools, School of Pedagogical and Technological Education, Athens, Greece

Abstract
Merits, attributes and challenges associated with the application of analytical modeling in electronics and photonics materials science are addressed, based mostly on the author\'s research during his tenure with Bell Labs, University-of-California, Portland State University, and small business innovative research (SBIR) ERS Co., USA. The emphasis is on practically important, yet often paradoxical, i.e., intuitively non-obvious, material behaviors. It is concluded that when material reliability is crucial, ability to effectively quantify it is imperative, and that analytical modeling is the most suitable, although never straightforward, technique to understand, explain and quantify material behaviors, especially in extreme, extraordinary and paradoxical situations.

Key Words
analytical modeling; thermal stresses; assemblies comprised of dissimilar materials; electronics and photonics packaging

Address
Ephraim Suhir: Department of Mechanical and Materials Engineering, Portland State University, Portland, OR, and
ERS Co., 727 Alvina Ct., Los Altos, CA, 94024, USA


Abstract
The concept design of the typha strawbale masonry came up as a result of the urgent demand for a means of constructing sustainable buildings, both in rural and urban settlement, not only suitable for dwellers but for keeping farm products by structures that will respond to the environmental eco-system, coupled with the fact that such structures are also affordable, durable and easy to maintain during their service period. The effects of contact between plaster and the stacked strawbale of a masonry needs to be established and design optimization for durability and stability of the masonry be obtained. The assessment will involve the application of plaster materials (cement and natural earth) to the wall specimen panels. Past works have shown that plastered strawbale walls have adequate resistance against the appropriate vertical loads, and further showed that the earth plaster can bear higher stress than the cement plastered straw bale. There is the implication that the collapse or response of the earth-strawbale wall is significantly higher compared to that of cement-strawbale from other straw-based masonries. Therefore the allowable stresses of plastered typha strawbale shall be predicted for their optimum values using SAP2000. The stress stability of each masonry is obtained by analytical model using the best fit variables for the wall height and thickness.

Key Words
typha strawbale; finite element; degradation; wood; plaster; optimal design

Address
Ofuyatan Olatokunbo: Department of Civil Engineering, Covenant University, Ota, Ogun State, Nigeria
Adedeji Adeola: Department of Civil Engineering, University of Ilorin, Kwara State, Ilorin, Nigeria
Omeje Maxwell: Department of Physics, College of Science and Technology, Covenant University, Ota, Ogun State, Nigeria
Olawale Simon: Department of Civil Engineering Faculty of Engineering and Environmental Sciences, Osun State University, Osogbo, Nigeria


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