Effect of temperature on geosynthetic rutting performance in asphalt pavement

In this research study, a 3D finite element model using ABAQUS software is used to evaluate the rutting performance of reinforced asphalt pavement. In this research study, the effects of three types of geosynthetic layers on the optimum location are studied at temperatures of 20°C, 40°C, and 50°C. According to the model analysis, the middle of asphalt layer is determined as the optimized location of geosynthetic layers in the pavement structure. The results showed that the effect of geosynthetic layers on rutting performance increased with increasing elastic modulus of geosynthetic at high temperature of pavement.     

Transfer of Ultrafine Particles and Air in Multi-storey Buildings

An emerging issue in Denmark is passive smoking in residential buildings where non-smokers are exposed to smoke from their neighbours. There are various ways that smoke is transferred from one flat to another. The air transfer rate between two flats in a multi-storey building depends on its construction, tightness and age. This paper presents results of a study on the transfer of ultrafine particles and tracer gas in an older multi-storey building in Copenhagen. The aim of the study was to quantify the transfer ofultrafine particles and gases from one flat to another fiat before and after sealing the floor. A new floor-sealing method was applied to seal the floor between the two flats. The sealing method was developed by a firm specialising in sealing. Indoor ultrafine particle concentrations and tracer gas were measured continuously in the two fiats during the measuring periods. In the unoccupied fiat, the gas source was N20 and the particle source was burning cigarettes. Reduction of the concentration of ultrafine particles and tracer gas by sealing the floor with polyethylene and joint filler made of bitumen was studied. It was evaluated how the sealing performed with regard to decreasing the amount of ultrafine particles and a tracer gas transferred between two fiats separated by a floor. When the floor between the flats was not sealed, the results showed that about 4% of the ultraflne particles and 14% of the tracer gas were transferred. After sealing, the amount transferred was reduced to 1.6% and 5%, respectively.     

A micromechanical approach for the prediction of the time-dependent failure of high temperature polymer matrix composites

In the present study, a novel micromechanical approach is introduced to study the time-dependent failure of unidirectional polymer matrix composites. The main advantage of the present micromechanical model lies in its ability to give closed-form solutions for the effective nonlinear response of unidirectional composites and to predict the material response to any combination of shear and normal loading. The creep failure criterion is expressed in terms of the creep failure functions of the viscoelastic matrix material. The micromechanical model is also used to calculate these creep failure functions from the knowledge of the creep behavior of the composite material in only transverse and shear loadings, thus eliminating the need for any further experimentation. The composite material used in this study is T300/934, which is suitable for service at high temperatures in aerospace applications. The use of micromechanics can give a more accurate insight into the failure mechanisms of the composite materials in particular at high temperatures where the general behavior of the polymer matrix composite is governed by matrix viscoelasticity and the time-dependent failure of the matrix is a localized phenomenon. The obtained creep failure stresses are found to be in reasonable agreement with the experimental data.     

Study of Structural and Magnetic Properties of Superparamagnetic Fe3O4–ZnO Core–Shell Nanoparticles

In this work, Fe₃O₄–ZnO core–shell nanoparticles have been successfully synthesized using a simple two-step co-precipitation method. In this regard, Fe₃O₄ (magnetite) and ZnO (zincite) nanoparticles (NPs) were synthesized separately. Then, the surface of the Fe₃O₄ NPs was modified with trisodium citrate in order to improve the attachment of ZnO NPs to the surface of Fe₃O₄ NPs. Afterwards, the modified magnetite NPs were coated with ZnO NPs. Moreover, the influence of the core to shell molar ratio on the structural and magnetic properties of the core–shell NPs has been investigated. The prepared nanoparticles have been characterized utilizing transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometer (VSM). The results of XRD indicate that Fe₃O₄ NPs with inverse spinel phase were formed. The results of VSM imply that the Fe₃O₄–ZnO core–shell NPs are superparamagnetic. The saturation magnetization of prepared Fe₃O₄ NPs is 54.24 emu/g and it decreases intensively down to 29.88, 10.51 and 5.75 emu/g, after ZnO coating with various ratios of core to shell as 1:1, 1:10 and 1:20, respectively. This reduction is attributed to core–shell interface effects and shielding. TEM images and XRD results imply that ZnO-coated magnetite NPs are formed. According to the TEM images, the estimated average size for most of core–shell NPs is about 12 nm.     

Fuzzy-based sustainable manufacturing assessment model for SMEs

Now-a-days, in the manufacturing, sustainability has become a necessity partly due to the threats created by traditional manufacturing practices, and due to regulations imposed by stakeholders. Sustainable manufacturing implies the creation of products that utilize minimum resources, has minimum negative impacts on environment and are safe for society at large at an affordable cost. This study proposes a fuzzy inference system-based model for the evaluation of manufacturing sustainability of small and medium enterprises (SMEs). In order to assess the manufacturing SMEs, decision makers’ opinion of the importance of sustainability measures and indicators and also the performance of enterprise with respect to indicators are gathered using linguistic variables. An illustrative list of sustainability indicators for manufacturing SMEs is identified considering the characteristics of SMEs. The implementation of our model for a manufacturing SME identified weak areas of performance which require appropriate strategy to enhance the overall sustainability. Based on the output of this assessment model and further deliberations with decision makers, case company is in process of selecting an appropriate strategy to reduce the environmental impacts. This model serves as a tool to assists the decision makers in assessing various dimensions of sustainability within their manufacturing SMEs.     

Analysis of capacity and coverage region for Rayleigh fading MIMO relay channel

In this paper, we consider Rayleigh fading MIMO relay channel with channel state information at the receivers. First, we extend the previously obtained results for the ergodic capacity of uncorrelated and semi‐correlated MIMO channels and derive closed‐form expressions for the capacity bounds of MIMO relay channel. Next, we study this channel from a new point of view, maximizing coverage region for a desired transmission rate, and investigate the optimal relay location in the sense of maximizing coverage region. However, in order to overcome the mathematical complexity in desired transmission rate analysis, because of the randomness of the multiple antenna channel matrices, we evaluate this rate by using an existing exact formula and also by an approximation we find in the high signal‐to‐noise ratio regime. Numerical results show a perfect match between the Monte Carlo simulations and the obtained analytical closed‐form expressions and also confirm the effectiveness of our approach in cooperative vehicular communication for determining optimal relay location at which the coverage region is maximum. Copyright © 2013 John Wiley & Sons, Ltd.     

A Comprehensive Experimental Study on Finishing Aluminum Tube by Proposed UAMAF Process

In this paper, a new noncontact ultrasonic magnetic abrasive finishing mechanism is presented. An ultrasonic vibration producer is used to vibrate the permanent magnets. The ferromagnetic steel grits in the created magnetic field form a flexible finishing tool. To take advantage of cavitation collapse pressure, the finishing zone components are immersed in water. The present work also studies the effect of parameters, i.e., time duration for finishing and working gap between magnetic poles and the workpiece on the surface roughness (Ra). The microscopic pictures and the roughness profile diagrams demonstrate the advantages of the proposed method.     

Dual-Rotation Speed Friction Stir Welding: Experimentation and Modeling

Implementing differential rotation speeds of pin and shoulder in the friction stir welding process is considered. Experimental investigations were carried out using a newly designed and fabricated apparatus for dual-rotation speed friction stir welding. Metallographic studies demonstrated that appropriate selection of separate pin and the shoulder rotation speeds not only results in defect-free joints, but also affects the weld zone by controlling the heat input delivered. An energy model for predicting maximum temperature was extended to the dual-rotation speed friction stir process. The model was verified using the previous experimental results reported in the literature.     

The logical precedence network planning of projects, considering the finish-to-start (FS) relations, using neural networks

One of the important steps in the process of project planning is the designing of logical precedence network. As the procedure of the logical precedence network planning is case dependent and varies in different projects, it could be considered as an unstructured and complex problem which should be solved by implementing the implicit domain knowledge of the planner. In this paper, we have shown how the artificial neural networks could be implemented to plan the finish-to-start logical precedence network of projects. The implementation results depict that the proposed methodology could result reasonable, accurate, and reliable outcomes, which could be used as a primary solution, which can enrich the acquired knowledge, after the accomplishment of the project and its practical corrections.     

Improving the quality of surface in polishing process with the magnetic abrasive powder polishing (MAPP) by use of ultrasonic oscillation of work-piece on a CNC table

In this research work, polishing inside, outside and over the cylindrical parts has been done by using a completely new and innovative method. The work-pieces have been placed on a two-axis Cartesian CNC Table for polishing operations. The Magnetic Rotary Head continuously changes its rotation direction from CW to CCW and CCW to CW and meanwhile the part begin to oscillate up-and-down under a High Frequency (20 kHz) conditions. The Frequency of changing direction From CW to CCW and CCW to CW is one of the important parameters in this method. This method is a kind of Ultrasonic Assisted Polishing (UAP) and novelty of this research work is combining this method with motion of work piece under CNC trajectory with continuously changing direction of Magnetic Rotary Head. Gap between Rotary Magnetic Polishing Head and the Work piece Surface can be controlled by a power transmission screw which operates in the direction of the vertical axis. Several experiments have proved high performance of this new proposed method in the process of polishing in short times.