Enabling flexible queries with guarantees in P2P systems

The Squid peer-to-peer information discovery system supports flexible queries using partial keywords, wildcards, and ranges. It is built on a structured overlay and uses data lookup protocols to guarantee that all existing data elements that match a query are found efficiently. Its main innovation is a dimension-reducing indexing scheme that effectively maps multidimensional information space to physical peers.     

Plastic micropump with ferrofluidic actuation

We present the realization and characterization of a new type of plastic micropump based on the magnetic actuation of a magnetic liquid. The pump consists of two serial check-valves that convert the periodic motion of a ferrofluidic plug into a pulsed quasi-continuous flow. The ferrofluid is actuated by the mechanical motion of an external NdFeB permanent magnet. The water-based ferrofluid is synthesized in-house using a coprecipitation method and has a saturation magnetization of 32 mT. The micropump consists of various layers of polymethylmethacrylate (PMMA), which are microstructured by powder blasting or by standard mechanical micromachining techniques, and are assembled in a single plastic structure using a monomer gluing solution. Two soft silicone membranes are integrated in the microfluidic structure to form two check-valves. Water has been successfully pumped at flow rates of up to 30 /spl mu/L/min and pumping is achieved at backpressures of up to 25 mbar.     

Effect of additives on the thermal nitridation of sol-gel derived silica gel

Silica gels derived by the sol-gel technique with and without additives such as hexamethylene tetramine, carbon fibre, glucose, etc., were nitrided at different temperatures employing a mixture of nitrogen gas and liquid ammonia. The gels and the nitrided products are characterized by infrared, X-ray diffraction, differential scanning calorimetry, thermogravimetry and surface area studies to investigate the extent of nitrogen incorporation and the effect caused by the nitrogen introduction on the physico-chemical properties of the gel. The gel sintered in air is also investigated for comparison purposes. It is shown that gels synthesized with additives incorporate more nitrogen compared to the gels without additives. It is also shown that nitrided products are thermally stable, tend to have a crystalline structure depending upon the processing conditions, and that the surface area of the gels decreases upon nitridation, the extent of which is influenced by the nitrogen content and nitridation temperature.     

Multiscale model to investigate the effect of graphene on the fracture characteristics of graphene/polymer nanocomposites

In this theoretical research work, the fracture characteristics of graphene-modified polymer nanocomposites were studied. A three-dimensional representative volume element-based multiscale model was developed in a finite element environment. Graphene sheets were modeled in an atomistic state, whereas the polymer matrix was modeled as a continuum. Van der Waals interactions between the matrix and graphene sheets were simulated employing truss elements. Fracture characteristics of graphene/polymer nanocomposites were investigated in conjunction with the virtual crack closure technique. The results demonstrate that fracture characteristics in terms of the strain energy release rate were affected for a crack lying in a polymer reinforced with graphene. A shielding effect from the crack driving forces is considered to be the reason for enhanced fracture resistance in graphene-modified polymer nanocomposites.     

Synthesis of Silicon Carbide through the Sol—Gel Process from Rayon Fibers

Silicon carbide whiskers (SiC( w )) are synthesized by the pyrolysis of rayon fibers impregnated with sol—gel-derived SiO₂. The influence of boric acid on whisker growth and the effect of varying the TEOS:rayon weight ratio are studied and reported. Evolution of SiC( w ) from impregnated rayon fibers in the carbonized and in the carbothermal stages is investigated.     

Duodenal atresia: a comparison of three modes of treatment

To determine the most successful mode of treatment, 33 consecutive cases of duodenal atresia treated by duodenoduodenostomy and not associated with other gastro-intestinal anomalies were analysed retrospectively. These patients have been placed in a nonrandomised fashion into one of three groups: Group A: Duodenostomy (side to side) with gastrostomy and transanastomotic feeding tube (n = 12); Group B: Duodenoduodenostomy (diamond shape) with jejunostomy feeding tube (n = 12); Group C: Duodenoduodenostomy (diamond shape) only (n = 9). A nasogastric tube was used in all cases. There was no difference between the groups for gestational age, birthweight, and age at operation. The outcome measures used to compare these groups were the time taken to achieve full preanastomotic feeds and the duration of hospital stay. There was no difference in time taken to achieve full pre-anastomotic feeds between Group A and Group B. Patients in Group C took significantly less time to achieve full pre-anastomotic feeds than either of the other two groups (p < 0.05, Mann-Whitney U). The duration of hospital stay was also significantly shorter for patients in Group C (median = 12 days) than for patients in either Group A or B (median = 24, 20 days respectively) (p < 0.05, Mann-Whitney U).     

Optical setup with high power transmission for creating gratings at the focusing length

A simple optical configuration has been proposed to fabricate surface-relief gratings which are key elements in integrated optical devices. This configuration is simple and easy to align thus enabling precise fabrication of a grating which is near to the wavelength used for machining. The system comparatively requires less alignment in order to get the maximum power transmission efficiency. In this paper we are interfering nanosecond pulses from Nd: VYO₄ laser system in the infrared regime. The pulses were made to interfere at the focal plane on a stainless steel sample target to fabricate surface relief gratings. Surface characteristics of the gratings have been studied by scanning electron microscopy and optical microscope. The change in the grating period by a simple modification in setup has been shown in this work. Feasibility of the new configuration with respect to alignments and machining efficiency has been verified by our experimental results.     

Enhancement of heat transfer by water–Al2O3 and water–TiO2 nanofluids jet impingement in cooling hot steel surface

Two different nanofluids, namely water–Al₂O₃ and water–TiO₂, were impinged in the form of jet on hot steel surface to remove high heat flux, and their performance was compared. The dimension of the test steel sample was 120 mm × 120 mm and 4 mm thickness. Four K-type thermocouples were embedded on the bottom surface of the plate to measure the transient temperature distribution. The time-temperature data were recorded by the help of a data acquisition system (make: CHINO, model: KR2000), and the results were analysed by ZAILA application software. Effect of impinging nanofluids with weight concentrations of 0.01%, 0.03%, 0.05% and 0.07% Al₂O₃ and TiO₂ nanoparticles on heat transfer from the hot surface was tested. The surface heat transfer coefficient (HTC) was computed from the time-temperature history recorded during experimentation. Experimental results revealed that addition of nanoparticles to the base fluid (water) surprisingly enhanced the heat transfer rate and HTC as expected. The heat transfer rate increased up to certain limit of nanoparticle concentrations, and then declined. Application of nanofluids for the steel strip cooling was found very effective in terms of heat transfer phenomena as compared to the conventional fluid cooling methods.     

Technology and learning at home: findings from the evaluation of the Home Access Programme pilot

This paper examines the impact of a UK government initiative, introduced in late 2008 and closed in 2011, to provide a computer and 1 year of Internet connectivity to low‐income households with children aged 5–19 years. This paper presents and discusses the findings from the evaluation of the initiative, the Home Access Programme (HAP) pilot study in two local authorities in England in 2009–2010. The evaluation found that HAP impacted positively on children and young people's computer access; more specifically, it led to increased student time engaged in homework and independent learning activities on the computer at home. The evaluation found evidence of pockets of increased parental engagement with their child's learning. Finally, the survey found some evidence of benefits of HAP in relation to economic and social benefits at home. The paper concludes that the pilot HAP made a material impact on closing the digital divide and delivered educational benefits for students and for households.