Aluminium foam–polymer composites: processing and characteristics

Dissemination of closed cell metal foam unique properties (low density, efficient energy absorption, high vibration/sound attenuation) in real life products has often been difficult to realise. With advanced pore morphology (APM) aluminium foam–polymer hybrids a new and simplified process route targeted at application in foam-filled structures (e.g. automotive A-pillar) has been introduced. APM foams are made from spherical, small volume foam elements joined to each other in a separate process step. Joining the aluminium foam elements by adhesive bonding delivers composite foam with approximately 80–95 wt.% aluminium foam and 5–20 wt.% adhesive (polymer). Setting up cellular structures from spherical foam elements allows for automatic part production, good pore morphology control and cost effective aluminium foam application. An automated production line is displayed and discussed. Mechanical properties of APM aluminium foam–polymer hybrids are similar to other closed cell aluminium foams. Integration of APM foams in profiles resulted in significantly improved properties as observed for conventional closed cell aluminium foam fillings. The unique properties of APM composite foams make them an attractive alternative as a cost effective and easily applicable material of construction with targeted uses such as energy absorbing reinforcement of composite structures.     

Biomimetic hydroxyapatite coating on glass coverslips for the assay of osteoclast activity in vitro

The osteoclast (OC) is the cell type responsible for the resorption of bone. The activity of this cell is important in the aetiology of a large number of skeletal pathologies, and also for the biocompatibility and osseointegration of orthopaedic implant materials. OC mediated acid hydrolysis of calcium phosphate from the bone matrix offers a prime means of studying the biology and activity of this cell type. We have developed a method of coating glass coverslips with a hydroxyapatite (HA)-like mineral, using a biomimetic approach. Hydroxylation followed by formation of a self assembled monolayer (SAM) using the surfactant triethoxysilylpropyl succinic anhydride (TESPSA), allowed biomimetic deposition of HA-like mineral from a simulated body fluid (SBF). The biocompatibility of the TESPSA SAM-HA coated glass coverslips was tested by culturing human mature OC present in samples of giant cell tumour of bone (GCT). Parameters of OC activity were assayed, including F-actin ring formation, release of calcium and formation of osteoclastic resorption pits, confirming that OC were able to attach to and resorb the coated surface. This approach for the preparation of HA coatings on glass coverslips could have wide applicability for the study of osteoclast behaviour in vitro. Gerald J. Atkins and Peter Majewski share senior author status.     

The association between price of regular-grade gasoline and injury and mortality rates among occupants involved in motorcycle- and automobile-related motor vehicle collisions

Motorcyclists have been reported to be more likely to die in a motor vehicle collision (MVC) than automobile occupants. With the recent increase in the pump price of gasoline, it has been reported that people are switching to motorcycles as main modes of transportation. This study evaluated the association between motor vehicle collision-related injury and mortality rates and increases in gasoline prices for occupants of automobiles and riders of motorcycles.There were an estimated 1,270,512 motorcycle MVC and 238,390,853 automobile MVC involved occupants in the U.S. from 1992 to 2007. Higher gasoline prices were associated with increased motorcycle-related injuries and deaths; however, this association no longer remained after accounting for changes in the number of registered vehicles.The current study observed that, while the number of injuries and fatalities in motorcycle-related MVCs increase with increasing gasoline price, rates remained largely unchanged. This suggests that the observed increase in motorcycle-related injuries and fatalities with increasing gasoline price is more a factor of the number of motorcycles on the road rather than operator characteristics.     

Gradient-based target localization in robotic sensor networks

Fast target localization without a map is a challenging problem in search and rescue applications. We propose and evaluate a novel gradient-based method which uses statistical techniques to estimate the position of a stationary target. Mobile nodes can then be directed toward the target using the shortest path. Moreover, localization can be achieved without any assistance from stationary sensor networks. Simulation results demonstrate nearly a 40% reduction in target acquisition time compared to a random walk model. In addition, our method can generate a position prediction map which closely matches the actual distribution in the field. Finally, experiments have been performed using MicaZ motes which further validate our techniques.     

FORECASTING GLOBAL ICE VOLUME

Abstract. Forecasts and associated probability limits of total ice volume for the next 100 000 years are found based upon a historical record of 440 000 years of oxygen-18 from deep sea cores. The forecasts are found using two different time series models, one based on the assumption that ice volume contains deterministic sinusoids, and one assuming that the record contains 'disturbed periodicities', i.e. the sinusoids do not have the same cycle length and amplitude from one cycle to another. The results for the two models are seen to be very similar, with both predicting a small probability for a future ice volume event to be as large as the last ice age, which was one of the largest glaciations of the last 2 million years.     

Control policies for an industrial acetylene hydrogenation reactor

This paper addresses the problem of finding optimal operational policies for an acetylene reactor for day to day operation. A lumped parameter model based on four main reactions is developed and used to examine the effects of the reactor manipulated variables on key reaction parameters. An optimal and a sub-optimal operational policy which minimize the ethylene loss over time are formulated and the solution techniques are presented. The results indicate that the reactor model is in good agreement with industrial plant data. The performance of the optimal control policy is very similar to the performance of the sub-optimal control policy. However, the sub-optimal formulation, while retaining the dominant features of the optimal response, reduces the computational requirements. Finally, some issues concerning the real-time implementation of an advanced acetylene reactor control scheme are presented. These include the estimation of the optimum regeneration cycle, a recursive model update algorithm, the process optimizer and their overall coordination. A preliminary analysis of the benefits associated with the advanced control scheme suggests a considerable reduction in the yearly ethylene loss.     

Closed channel fabrication using micromolding of metallic glass

Casting and molding are attractive options for low cost mass production. Metallic glasses may avoid many of the problems associated with micromolding of metals such as high temperatures and pressures, costly mold production, and shrinkage due to crystallization. In this study, we have produced 100 μm², enclosed channels in metallic glass using a novel multilayer Si stack micromolding process. Scanning electron microscope (SEM) images of the enclosed channels are provided to verify that the closed channels extended through the sample.     

Development and application of an automated subcatchment generator for SWMM using open data

An open source subcatchment generator program was developed for the Stormwater Management Model (SWMM) to automate tedious stages in the model construction process. The generator divides the investigated area into subcatchments using a uniform computation grid and connects the grid cells together and to the underlying stormwater network. The system was tested by applying it to two small urban catchments with different fractions of impervious surfaces in Helsinki, Finland, using mostly openly available data. The simulated discharge results were compared to measured data and to results obtained from manually built models. The proposed system significantly accelerated the setup of a SWMM modelling project, as the routing between the subcatchments as well as the subcatchment slopes and flow widths were directly derived from the computation grid. Automatically generated and manually constructed SWMM models produced discharge results that differed only slightly from each other.     

Liquefaction of coal using supercritical fluid mixtures

Powhatan No. 5 and Bruceton coals were liquefied for 15–60 min at 653 K and 30 MPa in supercritical aqueous mixtures containing 10–20 wt% tetrahydroquinoline (THQ), quinoline or tetralin. The THQ-water mixtures produced the highest conversion to tetrahydrofuran (THF) soluble products (up to 74%). Tetralin-water, quinoline-water and pure water solvents gave increasingly lower yields of THF solubles. Addition of hydrogen to the quinoline-water solvent mixture increased yields slightly, but not to the level obtained using the THQ-water mixture.The yields of THF solubles in all instances depended upon the concentration of solvent in the mixture, with the 10 wt% THQ and 10 wt% tetralin (in water) giving higher yields than either 0 or 20 wt% concentrations. The nitrogen-containing solvents were chemically bonded to the THF-soluble product, as observed by g.p.c.