Aerodynamic and Mobility Size Distribution Measurements to Reveal Biodiesel Effects on Diesel Exhaust Aerosol

This article examines the effect of biodiesel blends on the exhaust aerosol from a Euro 3 passenger car. Five different feedstock oils (soybean, palm, sunflower, rapeseed, and used frying oil) were used to produce fuels with 10% vol. content in biodiesel (B10). Use of the B10 blends led to a systematic reduction of PM mass emissions in the range of ～9% (rapeseed) to 23% (used frying oil) on average. The combination of particle size distributions based on the aerodynamic and the mobility diameters led to the estimation of the fractal dimension (DF) for non-volatile particles. This was found to range from 2.52 for the baseline (fossil) fuel to 2.62 for the palm oil blend, suggesting that biodiesel can affect the particle morphology, even at this low blending ratio. The differences were statistically significant. The increase of the DF is translated to more compact particle structure, which in turn denotes lower specific surface area. The volatile fraction of PM lies within a range of 1–9% when fossil diesel fuel is employed. Use of palm, sunflower and rapeseed B10 blends results to PM that contain up to 28% volatile particulate mass. The higher emissions of volatile components together with the lower specific area of non-volatile particles, promotes the formation of volatile particles, especially at high speed conditions. This increases the total particle population under motorway driving by up to three times over the baseline levels.     

Creating Conductive Copper–Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

We report production of bimetallic nanostructured copper– silver coatings by in situ deposition and sintering of metal nanoparticles produced as an aerosol. The metal nanoparticles themselves have potential applications in printed electronics, catalysis, antibacterial coatings, and heat transfer fluids. In many applications, nanoparticles are dispersed in an ink, which is then printed or coated onto a substrate and converted into a nanostructured thin film. Direct deposition from the aerosol allows us to produce nanostructured thin films without first dispersing the particles in a solvent. The high temperature reducing jet process allows formation of these metal nanoparticles from low-cost metal salt precursors in the gas phase. In this method, a fuel-rich hydrogen flame provides a low-cost source of energy to drive nanoparticle formation in a reducing environment. The aqueous precursor solution is delivered into the hot combustion product gases within a converging–diverging nozzle. The high-speed gas flow atomizes the precursor and provides exceptionally rapid mixing of the precursor with the hot gases. Here, particles are formed, then immediately quenched and deposited on a glass substrate. The effect of the silver content of the mixed copper–silver films on their electrical conductivity was studied systematically, revealing an abrupt transition from low conductivity to high conductivity between 30 wt.% and 40 wt.% silver.

Copyright 2013 American Association for Aerosol Research     

Surface Reconstruction for free-space 360 degrees fluorescence molecular tomography and the effects of animal motion.

Complete projection (360 degrees ) free-space fluorescence tomography of opaque media is poised to enable 3-D imaging through entire small animals in vivo with improved depth resolution compared to 360 degrees -projection fiber-based systems or limited-view angle systems. This approach can lead to a new generation of Fluorescence Molecular Tomography (FMT) performance since it allows high spatial sampling of photon fields propagating through tissue at any projection, employing nonconstricted animal surfaces. Herein, we employ a volume carving method to capture 3-D surfaces of diffusive objects and register the captured surface in the geometry of an FMT 360 degrees -projection acquisition system to obtain 3-D fluorescence image reconstructions. Using experimental measurements we evaluate the accuracy of the surface capture procedure by reconstructing the surfaces of phantoms of known dimensions. We then employ this methodology to characterize the animal movement of anaesthetized animals. We find that the effects of animal movement on the FMT reconstructed image were within system resolution limits (approximately 0.07 cm).     

Active load alleviation potential of adaptive wind turbine blades using shape memory alloy actuators

Upscaling of wind turbine blades calls for implementation of innovative active load control concepts that will facilitate the flawless operation of the machine and reduce the fatigue and ultimate loads that hinder its service life. Based on aeroelastic simulations that prove the enhanced capabilities of combined individual pitch and individual flap control at global wind turbine scale level, a shape adaptive concept that encompasses an articulated mechanism consisting of two subparts is presented. Shape memory alloy (SMA) actuators are investigated and assessed as means to control the shape adaptive mechanism at airfoil section level in order to alleviate the developed structural loads. The concept is embedded in the trailing edge region of the blade of a 10‐MW horizontal axis wind turbine and acts as a flap mechanism. Numerical simulations are performed considering various wind velocities and morphing target shapes and trajectories for both normal and extreme turbulence conditions. The results prove the potential of the concept, since the SMA controlled actuators can accurately follow the target trajectories. Power requirements are estimated at 0.22% of the AEP of the machine, while fatigue and ultimate load reduction of the flap‐wise bending moment at the blade root is 27.6% and 7.4%, respectively.     

Making (in) the smart city: The emergence of makerspaces

Critical approaches to the smart city concept are used to begin highlighting the promises of makerspaces, that is to say, those emerging urban sites that promote sharing practices; exercise community-based forms of governance; and utilize local manufacturing technologies. A bird’s-eye-view of the history of makerspaces is provided tracing their roots back to the hacker movement. Drawing from secondary sources, their community-building, learning and innovation potential is briefly discussed. Makerspaces, this essay argues, can serve as hubs and vehicles for citizen-driven transformation and, thus, play a key part in a more inclusive, participatory and commons-oriented vision of the smart city.     

THE FEASIBILITY OF CONTROLLING UNCONFINED RELEASES OF TOXIC GASES BY LIQUID SPRAYING

The technical and theoretical feasibility of liquid spraying as a means to control accidental unconfincd releases of toxic gases is investigated. Experimental and field information on water spraying of hazardous gases is analyzed, and the effectiveness of i) dilution, and ii) absorption is assessed. In addition, a mass-transfer model is developed and used to determine theoretically the effectiveness of liquid spraying in absorbing and inactivating unconfined releases of toxic gases. It is shown that the dilution achieved by water spraying is insufficient for toxic gases which pose health hazards at very low concentrations, whereas absorption and chemical reaction of the gas in the liquid phase can be a very effective control.     

Multi-objective optimization with fuzzy measures and its application to flow-shop scheduling

Most of the research in multi-objective scheduling optimization uses the classical weighted arithmetic mean operator to aggregate the various optimization criteria. However, there are scheduling problems where criteria are considered interact and thus a different operator should be adopted. This paper is devoted to the search of Pareto-optimal solutions in a tri-criterion flow-shop scheduling problem (FSSP) considering the interactions among the objectives. A new hybrid meta-heuristic is proposed to solve the problem which combines a genetic algorithm (GA) for solutions evolution and a reduced variable neighborhood search (RVNS) technique for fast solution improvement. To deal with the interactions among the three criteria the discrete Choquet integral method is adopted as a means to aggregate the criteria in the fitness function of each individual solution. Experimental comparisons (over public available FSSP test instances) with five existing multi-objective evolutionary algorithms (including the well known SPEA2 and NSGAII algorithms as well as the recently published L-NSGA algorithm) showed a superior performance for the developed approach in terms of diversity and domination of solutions.     

In-service and pre-service early childhood teachers’ views and intentions about ICT use in early childhood settings: A comparative study

This paper regards a comparative study which investigates in-service and pre-service Greek early childhood teachers’ views and intentions about integrating and using computers in early childhood settings. Views and intentions were investigated via a questionnaire administered to 240 in-service and 428 pre-service early childhood teachers. Confirmatory Factor Analysis showed that the one-factor structure of the questionnaire holds in both populations. Measurement partial invariance between the two populations was confirmed. Comparing the two populations with regard to the degree of adopting positive views–intentions and the level of computer self-efficacy, teachers expressed more positive views–intentions and students reported higher computer self-efficacy. Implications for teacher training are discussed.