Electric-field-induced self-assembled one-dimensional nanostructures in CdX and HgX (X=Se, Te) thin films

Self-assembling due to the presence of electric field during deposition in the spray deposited nanocrystalline CdX and HgX (X=Se and Te) thin films is reported. The films are deposited using solvothermally synthesized nanoparticles dispersed in 1-butanol and sprayed on the glass substrates at 200 °C without any voltage as well as by applying a voltage to the nozzle. The electron microscopy studies reveal the formation of nanorods for the films deposited with the voltage. The X-ray diffractograms of CdSe films deposited without voltage and with voltage show hexagonal crystal structure. On the other hand, CdTe films deposited without voltage show cubic crystal structure and the films deposited with voltage show hexagonal crystal structure. HgX films deposited without and with voltage show cubic crystal structure and there is no nanorod formation below 700 V. HRTEM studies show the growth direction of the CdX nanostructures. In view of the self-assembly observed under voltage, the induced dipole moment and the resultant electrostatic interaction are expected to be the driving force for the growth of nanorods. Blueshift in the band gap is observed for all the films deposited without and with voltages, and it is attributed to the quantum confinement effect due to the formation self-assembled one-dimensional nanostructures.     

Large Eddy Simulation of Turbulent Slot Jet Impingement Heat Transfer at Small Nozzle-to-Plate Spacing

We present fluid flow and heat transfer of a slot jet impingement heat transfer at a small value of the nozzle-to-plate spacing at which a secondary peak in the Nusselt number is observed. Large eddy simulation has been performed with a finite-volume-based computational fluid dynamics code and using a dynamic Smagorinsky model. The optimum domain size and grid for large eddy simulation (LES) have been produced based on LES computations on a coarse mesh and Reynolds-averaged Navier–Stokes-based computations. Two inflow conditions, namely, using the vortex method and no perturbations, were compared. The present LES results, using the vortex method, capture the secondary peak in the Nusselt number better as compared to the case with no perturbations. Results show that mean velocity profile in the stagnation region deviates from the standard law of the wall. Further, large-scale vortical structures were observed near the location of the secondary Nusselt number peak. Increases in both the streamwise and wall normal turbulence fluctuations are observed near the secondary peak in the Nusselt number. The secondary peak in Nusselt number is found to be associated with the combined effect of flow acceleration and an increase in the turbulence kinetic energy.     

A semantic geo-catalogue for a local administration

The enhancement of the search capabilities of geo-spatial tools occupies one of the highest positions in the agenda of the INSPIRE initiative. This can be done by equipping applications with tools able to understand user terminology. However, this is in contrast with current approaches, which tend to fix in advance the terminology with a consequent rigidity in the way users interact with the system. In this paper we present the work we have done with the Semantic Geo-Catalogue (SGC) project in providing a semantic extension to the geo-catalogue of the Autonomous Province of Trento (PAT) in Italy. This was done through the adoption of a semantic matching tool and a faceted ontology that codifies knowledge about the geography of the PAT and that was created by reorganizing data extracted from the local geographical dataset. Thanks to the semantic extension, queries to the geo-catalogue are expanded with domain specific terms taken from the ontology thus obtaining a higher number of relevant documents in output. We also complied with the Open Government Data (OGD) initiative by publishing in RDF and by linking to relevant dictionaries some useful data taken from the local repository.     

Exploring the Influence of Methylene Diphenyl Diisocyanate as a Modifier for Ethylene Vinyl Acetate/Thermoplastic Polyurethane Blends

Ethylene vinyl acetate (EVA)/thermoplastic polyurethane (TPU) blend at various blend ratios has been modified via reactive processing with 4,4′-methylene diphenyl diisocyanate (MDI). Modification of the blends with even small amount of MDI shows significant improvement in physico-mechanical properties for EVA/TPU 50/50 and 30/70 blends, and it is also supported by the superior melt rheological behavior and dramatic improvement in oil resistance property. After the treatment of electron beam (dose range: 50–150?kGy), radiation crosslinked EVA/TPU (30:70) blend reveals further improvement in various properties. This particular material can find potential application as cable sheathing component.     

Low-Temperature Processing of PZT Thick Film by Seeding and High-Energy Ball Milling and Studies on Electrical Properties

Lead zirconate titanate thick film with molecular formula PbZr_0.52Ti_0.42O₃ (PZT) was prepared by a modified conventional sol–gel method through seeding and high-energy ball milling, resulting in perovskite phase formation at lower temperatures. The ball-milling time was optimized by keeping the seed particle loading (5 wt.%) constant in the sol–gel solution. This methodology helped in reduction of the crystalline phase formation temperature to 300°C, which is much lower than that reported in the literature (450°C). The well-established perovskite phase was confirmed by x-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) of PZT films revealed uniform and crystalline microstructure. Film prepared by this methodology showed higher spontaneous polarization (2.22 μC/cm²), higher capacitance (1.17 nF), and low leakage current density (18 μA/cm²). The results obtained from ferroelectric characterization showed a strong correlation with the XRD and SEM results.     

Design of efficient fir digital differentiators of second and higher degrees by using universal weights

We propose in this paper an efficient design of FIR digital differentiators of degree k, k= 1, 2, 3,…, and their implementation in a novel structure which allows the order to be varied without having to alter the weights used in it. More precisely, we show that by using these ‘universal weights’ in a structure of order N_max, the order can be varied from N= 3 to N_max while keeping the weights fixed and retaining the optimality of performance. Mathematical formulae have been derived for these ‘universal weights’ for differentiators performing in the low- or midband-frequency ranges.     

Effect of channel geometry on solute dispersion in pressure-driven microfluidic systems

Pressure-driven transport of fluid and solute samples is often desirable in microfluidic devices, particularly where sufficient electroosmotic flow rates cannot be realized or the use of an electric field is restricted. Unfortunately, this mode of actuation also leads to hydrodynamic dispersion due to the inherent fluid shear in the system. While such dispersivity is known to scale with the square of the Peclet number based on the narrower dimension of the conduit (often the channel depth), the proportionality constant can vary significantly depending on its actual cross section. In this article, we review previous studies to understand the effect of commonly microfabricated channel cross sections on the Taylor–Aris dispersion of solute slugs in simple pressure-driven flow systems. We also analyze some recently proposed optimum designs which can reduce the contribution to this band broadening arising from the presence of the channel sidewalls. Finally, new simulation results have been presented in the last section of this paper which describe solutal spreading due to bowing of microchannels that can occur from stresses developed during their fabrication or operation under high-pressure conditions.     

Utilization of ultrasound sensors for anti-collision systems of powered wheelchairs

Anti-collision systems have been developed for use with powered wheelchairs in order to enable people with cognitive or physical impairments to safely operate a powered wheelchair. Anti-collision systems consist of sensors that have the ability to detect objects near the wheelchair and a computer that can stop the chair if a collision is determined to be likely. This investigation considered the suitability of using ultrasound sensors in such a system when encountering objects typically found within a home or a long-term care facility. An ultrasound sensor's ability to detect an object was dependent on the object's size, shape, specularity, reflectivity, and sound absorption characteristics. Ultrasound sensors, by themselves, were found to be unsuitable for anti-collision systems due to an inability to detect objects commonly encountered in the target environment (the home or long-term care facility) without increasing the complexity of the system to such a degree that it would be prohibitive to deploy this technology to the public.     

The inherent price of indulgence

An indulgent algorithm is a distributed algorithm that tolerates asynchronous periods of the network when process crash detection is unreliable. This paper presents a tight bound on the time complexity of indulgent consensus algorithms. We consider a round-based eventually synchronous model, and we show that any t-resilient consensus algorithm in this model, requires at least t+2 rounds for a global decision even in runs that are synchronous. We contrast our lower bound with the well-known t+1 round tight bound on consensus in the synchronous model. We then prove the bound to be tight by exhibiting a new t-resilient consensus algorithm in the eventually synchronous model that reaches a global decision at round t+2 in every synchronous run. Our new algorithm is in this sense significantly faster than the most efficient indulgent algorithm we know of, which requires 2t+2 rounds in synchronous runs. Our lower bound applies to round-based consensus algorithms with unreliable failure detectors such as ⋄ P and ⋄ S, and our matching algorithm can be adapted to such failure detectors. This work is partially supported by the Swiss National Science Foundation (project number 510-207).     

Temperature dependence of threshold and electrical characteristics of InGaAsP-InP d.h. lasers

Measurements are reported of the electrical characteristics and temperature dependence of threshold current of InGaAsP-InP d.h. lasers (? = 1.3 ?m). Analysis of the I dV/dI characteristics of these devices indicates that drift leakage of carriers from the active region is not responsible for the high temperature sensitivity of threshold in this material system.