Synthesis and Characterization of Nano-Composite Alumina–Titania Ceramic Membrane for Gas Separation

A ceramic composite membrane was prepared using a commercial titania ceramic membrane coated by alumina oxide via a sol–gel technique where polyvinyl alcohol (PVA) was used as a binder. The characteristic of the membrane was analyzed in terms of the effect of PVA concentration and sintering temperature on viscosity, pore size, density, porosity and surface area of the membrane. Two vol% of PVA solution containing 4 g of PVA in 100 mL of water was adequate to achieve an appropriate porosity level to avoid cracks on the gel layer. Sol viscosity and pore size of the membrane essentially increased when the PVA concentration was increased. The density of the membrane increased as the sintering temperature increased. The porosity level however, decreased when the temperature was increased. The composite membrane was further characterized in terms of permeability of pure gas at low-temperature region (301 K) where an experimental platform has been developed to perform the permeability studies.     

Technology application in project-based learning

Project-based learning is a student-centered comprehensive instructional approach where students collectively engage themselves in complex learning tasks. Recent advances in educational technologies have made student-centered learning in a technology rich environment both possible and feasible. This paper will report part of a larger study carried out at a school in the United States of America on the use ofconstructivism and technology in project-based learning. Data collection techniques included those typically associated with qualitative field research. In this paper, the technological infrastructure of the school and how technology is used in one of the project-based learning classes will be provided. Based on this study, some suggestions are also provided on how technology can be used in the context of other countries including in Malaysia.     

Construction related factors influencing the choice of concrete floor systems

Designers have a wide choice of concrete floor systems for their buildings. They can choose from three basic types available: in situ, precast or hybrid construction. A survey was conducted within the UK construction industry to investigate, in particular, the construction related factors influencing the choice of concrete floor systems. The data collected were subjected to frequency and severity index analyses, Kendall's concordance test and the chi-squared tests to produce a rank ordering of 12 construction related factors. Five factors were identified as being the most important, namely ‘appropriateness of use’, ‘cost’, ‘constructability’, ‘speed’ and ‘health and safety’. These five factors reflect current industry emphasis, and therefore could be adopted as the principal criteria for evaluating and selecting concrete floor systems during the design stage. They could also be used as assessment criteria for developing future systems.     

Detection and measurement of damage to surfaces after static contact loading

A system for three-dimensional measurements of surfaces has been developed and used to determine contact areas and spot distributions (following incremental loadings) of ground aluminium surfaces contacting a smooth platten.     

Numerical analysis of laser transmitter nonlinearity compensation technique for radio over fiber system

The task of reducing the noise and distortion generated by a laser transmitter has always been a challenge to improve the performance of radio over fiber systems. This paper presents a compensation system for nonlinear distortion of a laser transmitter supporting 5.2 GHz radio transmission over fiber employing a feed‐forward linearization technique. The nonlinearity of the laser diode is modeled using Volterra series analysis. The proposed linearization system is also simulated using commercial optical system software. The novel design has achieved 30 dB nonlinearity reduction considering 800 MHz modulation bandwidth. As an addition, this work also analyzes the effect of transmission length towards distortion reduction of the proposed system. Copyright © 2011 John Wiley & Sons, Ltd.     

3-D conjugate heat transfer analysis of PLCC packages mounted in-line on a Printed Circuit Board

This paper presents a three dimensional heat and fluid flow analysis of two Plastic Leaded Chip Carrier (PLCC) packages mounted in tandem arrangement on a Printed Circuit Board (PCB) exposed to the free stream velocity. The numerical simulation was done using FLUENT 6.3 and the experiments were performed by using an air chamber with nozzle, at different approach air velocities to emulate the forced convection heat transfer phenomena. Parameters such as junction temperature, thermal resistance and top surface average Nusselt number have been studied for each package by varying the chip power, spacing between the packages and approach air velocities. The decrease in the junction temperature of the packages with the increase in approach air velocity is clearly observed. Furthermore, the Nusselt number of PLCC 1 is always slightly higher than PLCC 2 for all approach velocities considered. The results also show that the spacing between packages influences the thermal resistance and average Nusselt number for both packages at a particular approach air velocity. The simulation results obtained are found in satisfactory agreement with the experimental results.     

Post‐Disaster least loaded lightpath routing in elastic optical networks

Disaster events directly affect the physical topology of core networks and may lead to simultaneous failure of multiple lightpaths leading to massive service outages for network operators. To recover from such a failure scenario, the existing routing algorithms running on network nodes (routers or switches) typically attempt to reestablish the connections over new routes with shortest distances and hop count approach. However, this approach may result in congestion on some links, while other links may have the unutilized capacity. Hence, intelligent lightpath computing techniques are required to efficiently route network traffic over the new routes by considering traffic load of each link in addition to distance and hop count to minimize network congestion. In this paper, we have proposed a capacity‐constrained maximally spatial disjoint lightpath algorithm to tackle the provisioning and restoration of disrupted lightpaths in a postdisaster scenario in the context of elastic optical networking. This algorithm computes an alternate least loaded lightpath for disrupted primary lightpath using capacity‐constrained shortest lightpath. Alternate lightpath selection is based on a criteria parameter for a lightpath to be least loaded and constrained by either the length or the spatial distance between primary and alternate lightpaths. The spatial distance between lightpaths enables to reestablish the disrupted connection request away from disaster proximity. The performance of the proposed algorithm is evaluated through simulation for several parameters like blocking probability, network utilization, connection success rates, and minimum spatial distance.     

Self‐Limiting Galvanic Growth of MnO2 Monolayers on a Liquid Metal—Applied to Photocatalysis

Liquid metals offer unprecedented chemistry. Here it is shown that they can facilitate self‐limiting oxidation processes on their surfaces, which enables the growth of metal oxides that are atomically thin. This claim is exemplified by creating atomically thin hydrated MnO₂ using a Galvanic replacement reaction between permanganate ions and a liquid gallium–indium alloy (EGaIn). The “liquid solution”–“liquid metal” process leads to the reduction of the permanganate ions, resulting in the formation of the oxide monolayer at the interface. It is presented that under mechanical agitation liquid metal droplets are established, and simultaneously, hydrated gallium oxides and manganese oxide sheets delaminate themselves from the interfacial boundaries. The produced nanosheets encapsulate a metallic core, which is found to consist of solid indium only, with the full migration of gallium out of the droplets. This process produces core/shell structures, where the shells are made of stacked atomically thin nanosheets. The obtained core/shell structures are found to be an efficient photocatalyst for the degradation of an organic dye under simulated solar irradiation. This study presents a new research direction toward the modification and functionalization of liquid metals through spontaneous interfacial redox reactions, which has implications for many applications beyond photocatalysis.     

Development of project cost contingency estimation model using risk analysis and fuzzy expert system

Contractors traditionally estimate cost contingency based on subjective judgment, such as 5–10% from the cost estimated by considering past similar project. However, such method does not have a sound basis and is difficult to justify or defend. Therefore, more objective methods for estimating project cost contingency have been presented. However, most of the methods still rely on formal modeling techniques, which is not easy to be applied in construction industry. This research proposes a method to estimate cost contingency using a flexible and rational approach that could accommodate contractors’ subjective judgment based on risk analysis and fuzzy expert system concept. In this research, the proposed method involved the development of cost contingency model for building and infrastructure projects in Malaysia. According to the validation result, it was found that the predictions given by the system were within 20% accuracy compared to actual cost contingencies.