Experimental Approach for Evaluating an UAV COTS-Based Embedded Sensors System

Fixed-wing Unmanned Aerial Vehicles (UAVs) are a class of UAVs which present many advantages notably long range of action. However, design of this kind of UAVs requires heavy logistics like outdoor tests, runways and experimented pilots. These constraints impact the development of embedded systems for fixed-wing UAVs. The purpose of this paper is to present an experimental approach for evaluating an embedded sensors system of a micro-fixed-wing UAV. Our idea is to test the sensors system using a vehicle that emulate the behavior of this UAV but without the constraints imposed by flight experimentations. Looking for the best emulation vehicle, first a theoretical and then an experimental study is conducted on a mobile robot and a bicycle models. We also show that, contrary to trend in literature, a mobile robot is not the optimal choice to emulate a fixed-wing UAV.     

Preparation and characterization of thin organosilicon films deposited on SPR chip

The paper reports on the preparation and characterization of organosilicon thin polymer films deposited on glass slides coated with 5 nm adhesion layer of titanium and 50 nm of gold. The polymer was obtained by the decomposition of 1,1,3,3-tetramethyldisiloxane precursor (TMDSO) premixed with oxygen induced in a N₂ plasma afterglow using remote plasma-enhanced chemical vapor deposition (PECVD) technique. The film thickness was controlled by laser interferometry and was 9 nm. The chemical stability of the gold substrate coated with the organosilicon polymer film (p-TMDSO) was studied in different acidic and basic solutions (pH 1-14). While the gold/polymer interface showed a high stability in acidic media, the film was almost completely removed in basic solutions. The resulting surfaces were characterized using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), water contact angle measurements, cyclic voltammetry, and surface plasmon resonance (SPR).     

Biomass concentration and biofilm characteristics in high-performance fluidized-bed biofilm reactors.

Two laboratory scale fluidized-bed biofilm reactors (FBBRs) were used to investigate the biomass concentration and the biofilm characteristics in a high performance FBBR used for the denitrification of exceptionally high-nitrate wastewater (1000 mg-N/L). Reported correlations by other workers for predicting the biomass concentration in FBBR were examined for their validity in comparison with the experimental results of this study and the best set of applicable correlations was recommended. The effects of the two main operational parameters, the superficial velocity and nitrogen loading rate on the biomass concentration in the FBBR were also studied. Correlations for the drag coefficient and the expansion index from the literature, together with the biofilm dry density correlation produced from this study were found to produce the best prediction of the FBBR biomass concentration compared to other reported correlations. The average biomass concentration in the FBBR decreased with the increase of the superficial velocity in the range of 45 to 65 m/h at all the applied nitrogen loadings (i.e. 6, 8, 12 and 16 kg-N/m3(bed).d).     

Mature macrophage cell lines exhibit variable responses to LPS

Bacterial lipopolysaccharide (LPS) is a potent activator of cells of the macrophage/monocyte lineage. Two mature macrophage cell lines, P388D1 and RAW264.7, exhibit very different biological responses to LPS. Although RAW264.7 cells release arachidonic acid from phospholipid in response to LPS stimulation, P388D1 cells do not respond in this manner. However, LPS primes P388D1 cells to release arachidonic acid in response to other stimuli. The goal of this work is to contrast the biochemical events that occur in LPS-treated P388D1 and RAW264.7 macrophages. Enzyme assays indicate that LPS treatment induces the activation of cytosolic PLA2 in RAW264.7, but not in P388D1 cells. Phorbol ester (PMA), a receptor-independent stimulus, also fails to induce arachidonic acid release from P388D1 cells, suggesting that these cells may have a defect in the signal transduction machinery that is common to LPS and PMA. This hypothesis is supported by the observation that the expression of the LPS receptors CD14 and CD11b/CD18 is similar on P388D1 and RAW264.7 cells. Western blot analyses indicate that the erk kinases are activated upon LPS treatment of RAW264.7 but not P388D1 cells. LPS-induced arachidonic acid release is reduced in cells treated with the MEK inhibitor PD98059, suggesting that activated erk kinases mediate the phosphorylation and activation of cPLA2 in this system. Interestingly, the p42 isoform of erk (erk2) appears to be activated in resting P388D1 cells. This observation indicates that the MAP kinase cascade may be constitutively activated in P388D1 cells which may in turn limit their ability to respond to LPS. Together, these data provide evidence that mature macrophages from different sources can exhibit variable responses to LPS and highlight the danger of making generalizations regarding the effects of LPS on macrophages.     

FeS2 thin films prepared by spray pyrolysis

In the present work FeS₂ films have been grown by spray pyrolysis followed by sulfidation. The structural, optical and electrical properties of these films have been investigated. The films were found to be n-type with an indirect band gap of 1.17 eV. These films have a high potential for use in thin film solar cells and photoelectrochemical cells.     

Theoretical Investigation of Capture,Collection, and Targeted Transfer of Underwater Gas Bubbles Using Janus-Faced Carbon Cloth

Recently, a straightforward method for the preparation of a Janus carbon cloth (Janus-CC) is reported. The method relies on polydimethylsiloxane (PDMS) coating, followed by flame exposure of one face of the PDMS-coated CC. The nonexposed to the flame face of the Janus-CC is superhydrophobic, while the exposed to the flame face is superhydrophilic. Underwater, the superhydrophobic face shows superaerophilicity, while the supherhydophilic face shows superaerophobicity. A tethered gas bubble onto the superhydrophobic face has a paraboloid of revolution shape due to the cohesion force between the bubble and the gaseous film. Herein, the geometrical parameters of underwater tethered gas bubbles onto the Janus-CC are obtained, and the tendency of Janus-CC for capturing of bubbles is interpreted based on the derived Gibbs free-energy change equation. It is experimentally observed that a small sited bubble moves toward the bigger one through the formed gaseous film, but this observation cannot be interpreted based on the classical Young–Laplace equation because here the smaller bubble has bigger curvature radius. Herein, a modified Young–Laplace equation is derived and applied for interpretation of the movement of a small bubble toward the bigger one. Also, the buoyancy force for a sited bubble on the gaseous film is discussed.     

Electrosynthesis and analysis of the electrochemical properties of a composite material: Polyaniline + titanium oxide

The analysis of the electrochemical and spectroscopic properties of a composite material obtained starting from the polyaniline and TiO₂ in H₂SO₄ medium, using cyclic voltamperometry, shows three redox couples characteristic of the different oxidation and reduction states of produced polymer. The electroactivity of the composite in acid medium was better than that obtained in basic medium. The impedance spectroscopy study shows that the resistance of the film increases with the aniline concentration, but is not significantly affected by the amount of TiO₂ incorporated in polymer. The increase of pH decreases the resistance of the films and consequently increases its conductivity.     

Contribution of angular measurements to intelligent gear faults diagnosis

Currently, work on the automation of vibration diagnosis is mainly based on indicators extracted from Time sampled Acceleration signals. There are other attractive alternatives such as those based on Angle synchronized measurements, which can provide a considerable number of more relevant and diverse indicators and, thus, lead to better performance in gear fault classification. The diversity of angular measurements (Instantaneous Angular Speed, Transmission Error and Angular sampled Acceleration) represents potential sources of relevant information in fault detection and diagnosis systems. These complementary measurements of existing signals or new relevant signals allow the construction of Feature Vector (FV) offering robust and effective classification methods even for different or non-stationary running speed conditions. In this paper, we propose to build several FVs based on indicators derived from the angular techniques to compare them to the ones calculated from the time signals, proving their superior performance in detection and identification of gear faults. It will be a question to demonstrate the effectiveness of angular indicators in increasing classification performances, using a supervised classifier based on Artificial Neural Networks and thus determining the most suitable signals.     

Heat transfer enhancement in self-sustained oscillatory flow in a staggered baffled vertical channel under the buoyancy effect

Unsteady laminar heat transfer enhancement in asymmetrically heated vertical baffled channel under buoyancy effect is investigated numerically. The baffles are installed on the two walls in an offset manner with constant spacing. The governing equations are solved by the finite volume formulation using openFoam© open-source code. Air (Pr?=?0.71) is used as working fluid. The effects of Reynolds number (100–1400) and Grashof number (2.5?×?10⁴ to 2?×?10⁵) in addition to the baffle height (0.1–0.5) on heat transfer and friction factor are studied. The results are given in the form of dimensionless isotherm contours and streamlines in addition to the Nusselt number and friction factor. The results obtained revealed that the flow bifurcates to self-sustained oscillatory flow at moderate Reynolds number (below 600 for a blockage ratio of 0.25). The unsteady self-sustained flow leads to heat transfer enhancement up to 2.8 times for baffle height h_b?=?0.25 and up to 3.7 when compared to the smooth channel. Unfortunately, this heat transfer is accompanied by an important increase in pumping power.     

Crystalline ZnO and ZnO/TiO2 nanoparticles derived from tert-butyl N-(2 mercaptoethyl)carbamatozinc(II) chelate: Electrocatalytic studies for H2 generation in alkaline electrolytes

A newly synthesized zinc(II) complex, namely tert-butyl N-(2 mercaptoethyl)carbamatozinc(II) complex [Zn(Boc-S)₂] (Boc = tert-butyl N-[2-mercaptoethyl]carbamate), has been used as an organozinc precursor for the production of crystalline ZnO and ZnO/TiO₂ nanoparticles. The synthesized complex and the obtained nanomaterials were fully characterized using various spectroscopic and surface analysis techniques. Their surface morphology, chemical purity and stoichiometry have been investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) as well as X-ray fluorescence. The synthesized Zn(II) molecular complex, ZnO and ZnO/TiO₂ nanomaterials have been tested in alkaline aqueous solution (1.0 MNaOH) for the hydrogen evolution reaction (HER) using various electrochemical techniques. The results revealed high HER catalytic performance of ZnO and ZnO/TiO₂ cathode materials, with the latter exhibiting higher catalytic activity recording an exchange current density (j_o) of 0.3 mA cm⁻². This current value, which approaches that of Pt wire (0.5 mA cm⁻²), cross-sectional area ~0.008 cm², is about 11 and 100 times greater than those measured for ZnO alone (0.028 mA cm⁻²) and TiO₂ alone (0.0032 mA cm⁻²), respectively. Moderate catalytic activity was recorded for the complex catalyst, namely GC-Zn(Boc-S)₂ with j_o value of (0.01 mA cm⁻²). Tafel slope values of 130 and 122 mV dec⁻¹ were calculated for ZnO and ZnO/TiO₂, respectively. Such Tafel slope values, which are close to that of the Pt wire (120 mV dec⁻¹), referred to a Volmer-controlled HER kinetics. Other important electrochemical parameters describing the kinetics of the HER, such as roughness factor (R_f) and turnover frequency (TOF) were also estimated and discussed. The high numerical values of the various HER kinetic parameters recorded for the ZnO/TiO₂ catalyst, in addition to its high stability and durability (stable for up to 10 000 continuous cathodic polarization cycles), besides maintaining its morphology and chemical composition after stability test (confirmed from SEM/EDX and XRD examinations), located it in a privileged position among the most efficient HER electrocatalysts reported in the literature.